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llvm-project/clang/lib/AST/ExprConstant.cpp

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//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the Expr constant evaluator.
//
// Constant expression evaluation produces four main results:
//
// * A success/failure flag indicating whether constant folding was successful.
// This is the 'bool' return value used by most of the code in this file. A
// 'false' return value indicates that constant folding has failed, and any
// appropriate diagnostic has already been produced.
//
// * An evaluated result, valid only if constant folding has not failed.
//
// * A flag indicating if evaluation encountered (unevaluated) side-effects.
// These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1),
// where it is possible to determine the evaluated result regardless.
//
// * A set of notes indicating why the evaluation was not a constant expression
// (under the C++11 / C++1y rules only, at the moment), or, if folding failed
// too, why the expression could not be folded.
//
// If we are checking for a potential constant expression, failure to constant
// fold a potential constant sub-expression will be indicated by a 'false'
// return value (the expression could not be folded) and no diagnostic (the
// expression is not necessarily non-constant).
//
//===----------------------------------------------------------------------===//
#include "Interp/Context.h"
#include "Interp/Frame.h"
#include "Interp/State.h"
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Attr.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/CurrentSourceLocExprScope.h"
#include "clang/AST/Expr.h"
#include "clang/AST/OSLog.h"
#include "clang/AST/OptionalDiagnostic.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/TypeLoc.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/APFixedPoint.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include <cstring>
#include <functional>
#define DEBUG_TYPE "exprconstant"
using namespace clang;
using llvm::APFixedPoint;
using llvm::APInt;
using llvm::APSInt;
using llvm::APFloat;
using llvm::FixedPointSemantics;
using llvm::Optional;
namespace {
struct LValue;
class CallStackFrame;
class EvalInfo;
using SourceLocExprScopeGuard =
CurrentSourceLocExprScope::SourceLocExprScopeGuard;
static QualType getType(APValue::LValueBase B) {
return B.getType();
}
/// Get an LValue path entry, which is known to not be an array index, as a
/// field declaration.
static const FieldDecl *getAsField(APValue::LValuePathEntry E) {
return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer());
}
/// Get an LValue path entry, which is known to not be an array index, as a
/// base class declaration.
static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) {
return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer());
}
/// Determine whether this LValue path entry for a base class names a virtual
/// base class.
static bool isVirtualBaseClass(APValue::LValuePathEntry E) {
return E.getAsBaseOrMember().getInt();
}
/// Given an expression, determine the type used to store the result of
/// evaluating that expression.
static QualType getStorageType(const ASTContext &Ctx, const Expr *E) {
if (E->isRValue())
return E->getType();
return Ctx.getLValueReferenceType(E->getType());
}
/// Given a CallExpr, try to get the alloc_size attribute. May return null.
static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) {
if (const FunctionDecl *DirectCallee = CE->getDirectCallee())
return DirectCallee->getAttr<AllocSizeAttr>();
if (const Decl *IndirectCallee = CE->getCalleeDecl())
return IndirectCallee->getAttr<AllocSizeAttr>();
return nullptr;
}
/// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr.
/// This will look through a single cast.
///
/// Returns null if we couldn't unwrap a function with alloc_size.
static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) {
if (!E->getType()->isPointerType())
return nullptr;
E = E->IgnoreParens();
// If we're doing a variable assignment from e.g. malloc(N), there will
// probably be a cast of some kind. In exotic cases, we might also see a
// top-level ExprWithCleanups. Ignore them either way.
if (const auto *FE = dyn_cast<FullExpr>(E))
E = FE->getSubExpr()->IgnoreParens();
if (const auto *Cast = dyn_cast<CastExpr>(E))
E = Cast->getSubExpr()->IgnoreParens();
if (const auto *CE = dyn_cast<CallExpr>(E))
return getAllocSizeAttr(CE) ? CE : nullptr;
return nullptr;
}
/// Determines whether or not the given Base contains a call to a function
/// with the alloc_size attribute.
static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) {
const auto *E = Base.dyn_cast<const Expr *>();
return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E);
}
/// Determines whether the given kind of constant expression is only ever
/// used for name mangling. If so, it's permitted to reference things that we
/// can't generate code for (in particular, dllimported functions).
static bool isForManglingOnly(ConstantExprKind Kind) {
switch (Kind) {
case ConstantExprKind::Normal:
case ConstantExprKind::ClassTemplateArgument:
case ConstantExprKind::ImmediateInvocation:
// Note that non-type template arguments of class type are emitted as
// template parameter objects.
return false;
case ConstantExprKind::NonClassTemplateArgument:
return true;
}
llvm_unreachable("unknown ConstantExprKind");
}
static bool isTemplateArgument(ConstantExprKind Kind) {
switch (Kind) {
case ConstantExprKind::Normal:
case ConstantExprKind::ImmediateInvocation:
return false;
case ConstantExprKind::ClassTemplateArgument:
case ConstantExprKind::NonClassTemplateArgument:
return true;
}
llvm_unreachable("unknown ConstantExprKind");
}
/// The bound to claim that an array of unknown bound has.
/// The value in MostDerivedArraySize is undefined in this case. So, set it
/// to an arbitrary value that's likely to loudly break things if it's used.
static const uint64_t AssumedSizeForUnsizedArray =
std::numeric_limits<uint64_t>::max() / 2;
/// Determines if an LValue with the given LValueBase will have an unsized
/// array in its designator.
/// Find the path length and type of the most-derived subobject in the given
/// path, and find the size of the containing array, if any.
static unsigned
findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base,
ArrayRef<APValue::LValuePathEntry> Path,
uint64_t &ArraySize, QualType &Type, bool &IsArray,
bool &FirstEntryIsUnsizedArray) {
// This only accepts LValueBases from APValues, and APValues don't support
// arrays that lack size info.
assert(!isBaseAnAllocSizeCall(Base) &&
"Unsized arrays shouldn't appear here");
unsigned MostDerivedLength = 0;
Type = getType(Base);
for (unsigned I = 0, N = Path.size(); I != N; ++I) {
if (Type->isArrayType()) {
const ArrayType *AT = Ctx.getAsArrayType(Type);
Type = AT->getElementType();
MostDerivedLength = I + 1;
IsArray = true;
if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
ArraySize = CAT->getSize().getZExtValue();
} else {
assert(I == 0 && "unexpected unsized array designator");
FirstEntryIsUnsizedArray = true;
ArraySize = AssumedSizeForUnsizedArray;
}
} else if (Type->isAnyComplexType()) {
const ComplexType *CT = Type->castAs<ComplexType>();
Type = CT->getElementType();
ArraySize = 2;
MostDerivedLength = I + 1;
IsArray = true;
} else if (const FieldDecl *FD = getAsField(Path[I])) {
Type = FD->getType();
ArraySize = 0;
MostDerivedLength = I + 1;
IsArray = false;
} else {
// Path[I] describes a base class.
ArraySize = 0;
IsArray = false;
}
}
return MostDerivedLength;
}
/// A path from a glvalue to a subobject of that glvalue.
struct SubobjectDesignator {
/// True if the subobject was named in a manner not supported by C++11. Such
/// lvalues can still be folded, but they are not core constant expressions
/// and we cannot perform lvalue-to-rvalue conversions on them.
unsigned Invalid : 1;
/// Is this a pointer one past the end of an object?
unsigned IsOnePastTheEnd : 1;
/// Indicator of whether the first entry is an unsized array.
unsigned FirstEntryIsAnUnsizedArray : 1;
/// Indicator of whether the most-derived object is an array element.
unsigned MostDerivedIsArrayElement : 1;
/// The length of the path to the most-derived object of which this is a
/// subobject.
unsigned MostDerivedPathLength : 28;
/// The size of the array of which the most-derived object is an element.
/// This will always be 0 if the most-derived object is not an array
/// element. 0 is not an indicator of whether or not the most-derived object
/// is an array, however, because 0-length arrays are allowed.
///
/// If the current array is an unsized array, the value of this is
/// undefined.
uint64_t MostDerivedArraySize;
/// The type of the most derived object referred to by this address.
QualType MostDerivedType;
typedef APValue::LValuePathEntry PathEntry;
/// The entries on the path from the glvalue to the designated subobject.
SmallVector<PathEntry, 8> Entries;
SubobjectDesignator() : Invalid(true) {}
explicit SubobjectDesignator(QualType T)
: Invalid(false), IsOnePastTheEnd(false),
FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
MostDerivedPathLength(0), MostDerivedArraySize(0),
MostDerivedType(T) {}
SubobjectDesignator(ASTContext &Ctx, const APValue &V)
: Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false),
FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false),
MostDerivedPathLength(0), MostDerivedArraySize(0) {
assert(V.isLValue() && "Non-LValue used to make an LValue designator?");
if (!Invalid) {
IsOnePastTheEnd = V.isLValueOnePastTheEnd();
ArrayRef<PathEntry> VEntries = V.getLValuePath();
Entries.insert(Entries.end(), VEntries.begin(), VEntries.end());
if (V.getLValueBase()) {
bool IsArray = false;
bool FirstIsUnsizedArray = false;
MostDerivedPathLength = findMostDerivedSubobject(
Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize,
MostDerivedType, IsArray, FirstIsUnsizedArray);
MostDerivedIsArrayElement = IsArray;
FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
}
}
}
void truncate(ASTContext &Ctx, APValue::LValueBase Base,
unsigned NewLength) {
if (Invalid)
return;
assert(Base && "cannot truncate path for null pointer");
assert(NewLength <= Entries.size() && "not a truncation");
if (NewLength == Entries.size())
return;
Entries.resize(NewLength);
bool IsArray = false;
bool FirstIsUnsizedArray = false;
MostDerivedPathLength = findMostDerivedSubobject(
Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray,
FirstIsUnsizedArray);
MostDerivedIsArrayElement = IsArray;
FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray;
}
void setInvalid() {
Invalid = true;
Entries.clear();
}
/// Determine whether the most derived subobject is an array without a
/// known bound.
bool isMostDerivedAnUnsizedArray() const {
assert(!Invalid && "Calling this makes no sense on invalid designators");
return Entries.size() == 1 && FirstEntryIsAnUnsizedArray;
}
/// Determine what the most derived array's size is. Results in an assertion
/// failure if the most derived array lacks a size.
uint64_t getMostDerivedArraySize() const {
assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size");
return MostDerivedArraySize;
}
/// Determine whether this is a one-past-the-end pointer.
bool isOnePastTheEnd() const {
assert(!Invalid);
if (IsOnePastTheEnd)
return true;
if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement &&
Entries[MostDerivedPathLength - 1].getAsArrayIndex() ==
MostDerivedArraySize)
return true;
return false;
}
/// Get the range of valid index adjustments in the form
/// {maximum value that can be subtracted from this pointer,
/// maximum value that can be added to this pointer}
std::pair<uint64_t, uint64_t> validIndexAdjustments() {
if (Invalid || isMostDerivedAnUnsizedArray())
return {0, 0};
// [expr.add]p4: For the purposes of these operators, a pointer to a
// nonarray object behaves the same as a pointer to the first element of
// an array of length one with the type of the object as its element type.
bool IsArray = MostDerivedPathLength == Entries.size() &&
MostDerivedIsArrayElement;
uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
: (uint64_t)IsOnePastTheEnd;
uint64_t ArraySize =
IsArray ? getMostDerivedArraySize() : (uint64_t)1;
return {ArrayIndex, ArraySize - ArrayIndex};
}
/// Check that this refers to a valid subobject.
bool isValidSubobject() const {
if (Invalid)
return false;
return !isOnePastTheEnd();
}
/// Check that this refers to a valid subobject, and if not, produce a
/// relevant diagnostic and set the designator as invalid.
bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK);
/// Get the type of the designated object.
QualType getType(ASTContext &Ctx) const {
assert(!Invalid && "invalid designator has no subobject type");
return MostDerivedPathLength == Entries.size()
? MostDerivedType
: Ctx.getRecordType(getAsBaseClass(Entries.back()));
}
/// Update this designator to refer to the first element within this array.
void addArrayUnchecked(const ConstantArrayType *CAT) {
Entries.push_back(PathEntry::ArrayIndex(0));
// This is a most-derived object.
MostDerivedType = CAT->getElementType();
MostDerivedIsArrayElement = true;
MostDerivedArraySize = CAT->getSize().getZExtValue();
MostDerivedPathLength = Entries.size();
}
/// Update this designator to refer to the first element within the array of
/// elements of type T. This is an array of unknown size.
void addUnsizedArrayUnchecked(QualType ElemTy) {
Entries.push_back(PathEntry::ArrayIndex(0));
MostDerivedType = ElemTy;
MostDerivedIsArrayElement = true;
// The value in MostDerivedArraySize is undefined in this case. So, set it
// to an arbitrary value that's likely to loudly break things if it's
// used.
MostDerivedArraySize = AssumedSizeForUnsizedArray;
MostDerivedPathLength = Entries.size();
}
/// Update this designator to refer to the given base or member of this
/// object.
void addDeclUnchecked(const Decl *D, bool Virtual = false) {
Entries.push_back(APValue::BaseOrMemberType(D, Virtual));
// If this isn't a base class, it's a new most-derived object.
if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) {
MostDerivedType = FD->getType();
MostDerivedIsArrayElement = false;
MostDerivedArraySize = 0;
MostDerivedPathLength = Entries.size();
}
}
/// Update this designator to refer to the given complex component.
void addComplexUnchecked(QualType EltTy, bool Imag) {
Entries.push_back(PathEntry::ArrayIndex(Imag));
// This is technically a most-derived object, though in practice this
// is unlikely to matter.
MostDerivedType = EltTy;
MostDerivedIsArrayElement = true;
MostDerivedArraySize = 2;
MostDerivedPathLength = Entries.size();
}
void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E);
void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E,
const APSInt &N);
/// Add N to the address of this subobject.
void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) {
if (Invalid || !N) return;
uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue();
if (isMostDerivedAnUnsizedArray()) {
diagnoseUnsizedArrayPointerArithmetic(Info, E);
// Can't verify -- trust that the user is doing the right thing (or if
// not, trust that the caller will catch the bad behavior).
// FIXME: Should we reject if this overflows, at least?
Entries.back() = PathEntry::ArrayIndex(
Entries.back().getAsArrayIndex() + TruncatedN);
return;
}
// [expr.add]p4: For the purposes of these operators, a pointer to a
// nonarray object behaves the same as a pointer to the first element of
// an array of length one with the type of the object as its element type.
bool IsArray = MostDerivedPathLength == Entries.size() &&
MostDerivedIsArrayElement;
uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex()
: (uint64_t)IsOnePastTheEnd;
uint64_t ArraySize =
IsArray ? getMostDerivedArraySize() : (uint64_t)1;
if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) {
// Calculate the actual index in a wide enough type, so we can include
// it in the note.
N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65));
(llvm::APInt&)N += ArrayIndex;
assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index");
diagnosePointerArithmetic(Info, E, N);
setInvalid();
return;
}
ArrayIndex += TruncatedN;
assert(ArrayIndex <= ArraySize &&
"bounds check succeeded for out-of-bounds index");
if (IsArray)
Entries.back() = PathEntry::ArrayIndex(ArrayIndex);
else
IsOnePastTheEnd = (ArrayIndex != 0);
}
};
/// A scope at the end of which an object can need to be destroyed.
enum class ScopeKind {
Block,
FullExpression,
Call
};
/// A reference to a particular call and its arguments.
struct CallRef {
CallRef() : OrigCallee(), CallIndex(0), Version() {}
CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version)
: OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {}
explicit operator bool() const { return OrigCallee; }
/// Get the parameter that the caller initialized, corresponding to the
/// given parameter in the callee.
const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const {
return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex())
: PVD;
}
/// The callee at the point where the arguments were evaluated. This might
/// be different from the actual callee (a different redeclaration, or a
/// virtual override), but this function's parameters are the ones that
/// appear in the parameter map.
const FunctionDecl *OrigCallee;
/// The call index of the frame that holds the argument values.
unsigned CallIndex;
/// The version of the parameters corresponding to this call.
unsigned Version;
};
/// A stack frame in the constexpr call stack.
class CallStackFrame : public interp::Frame {
public:
EvalInfo &Info;
/// Parent - The caller of this stack frame.
CallStackFrame *Caller;
/// Callee - The function which was called.
const FunctionDecl *Callee;
/// This - The binding for the this pointer in this call, if any.
const LValue *This;
/// Information on how to find the arguments to this call. Our arguments
/// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a
/// key and this value as the version.
CallRef Arguments;
/// Source location information about the default argument or default
/// initializer expression we're evaluating, if any.
CurrentSourceLocExprScope CurSourceLocExprScope;
// Note that we intentionally use std::map here so that references to
// values are stable.
typedef std::pair<const void *, unsigned> MapKeyTy;
typedef std::map<MapKeyTy, APValue> MapTy;
/// Temporaries - Temporary lvalues materialized within this stack frame.
MapTy Temporaries;
/// CallLoc - The location of the call expression for this call.
SourceLocation CallLoc;
/// Index - The call index of this call.
unsigned Index;
/// The stack of integers for tracking version numbers for temporaries.
SmallVector<unsigned, 2> TempVersionStack = {1};
unsigned CurTempVersion = TempVersionStack.back();
unsigned getTempVersion() const { return TempVersionStack.back(); }
void pushTempVersion() {
TempVersionStack.push_back(++CurTempVersion);
}
void popTempVersion() {
TempVersionStack.pop_back();
}
CallRef createCall(const FunctionDecl *Callee) {
return {Callee, Index, ++CurTempVersion};
}
// FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact
// on the overall stack usage of deeply-recursing constexpr evaluations.
// (We should cache this map rather than recomputing it repeatedly.)
// But let's try this and see how it goes; we can look into caching the map
// as a later change.
/// LambdaCaptureFields - Mapping from captured variables/this to
/// corresponding data members in the closure class.
llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields;
FieldDecl *LambdaThisCaptureField;
CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
CallRef Arguments);
~CallStackFrame();
// Return the temporary for Key whose version number is Version.
APValue *getTemporary(const void *Key, unsigned Version) {
MapKeyTy KV(Key, Version);
auto LB = Temporaries.lower_bound(KV);
if (LB != Temporaries.end() && LB->first == KV)
return &LB->second;
// Pair (Key,Version) wasn't found in the map. Check that no elements
// in the map have 'Key' as their key.
assert((LB == Temporaries.end() || LB->first.first != Key) &&
(LB == Temporaries.begin() || std::prev(LB)->first.first != Key) &&
"Element with key 'Key' found in map");
return nullptr;
}
// Return the current temporary for Key in the map.
APValue *getCurrentTemporary(const void *Key) {
auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
return &std::prev(UB)->second;
return nullptr;
}
// Return the version number of the current temporary for Key.
unsigned getCurrentTemporaryVersion(const void *Key) const {
auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX));
if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key)
return std::prev(UB)->first.second;
return 0;
}
/// Allocate storage for an object of type T in this stack frame.
/// Populates LV with a handle to the created object. Key identifies
/// the temporary within the stack frame, and must not be reused without
/// bumping the temporary version number.
template<typename KeyT>
APValue &createTemporary(const KeyT *Key, QualType T,
ScopeKind Scope, LValue &LV);
/// Allocate storage for a parameter of a function call made in this frame.
APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV);
void describe(llvm::raw_ostream &OS) override;
Frame *getCaller() const override { return Caller; }
SourceLocation getCallLocation() const override { return CallLoc; }
const FunctionDecl *getCallee() const override { return Callee; }
bool isStdFunction() const {
for (const DeclContext *DC = Callee; DC; DC = DC->getParent())
if (DC->isStdNamespace())
return true;
return false;
}
private:
APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T,
ScopeKind Scope);
};
/// Temporarily override 'this'.
class ThisOverrideRAII {
public:
ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable)
: Frame(Frame), OldThis(Frame.This) {
if (Enable)
Frame.This = NewThis;
}
~ThisOverrideRAII() {
Frame.This = OldThis;
}
private:
CallStackFrame &Frame;
const LValue *OldThis;
};
}
static bool HandleDestruction(EvalInfo &Info, const Expr *E,
const LValue &This, QualType ThisType);
static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
APValue::LValueBase LVBase, APValue &Value,
QualType T);
namespace {
/// A cleanup, and a flag indicating whether it is lifetime-extended.
class Cleanup {
llvm::PointerIntPair<APValue*, 2, ScopeKind> Value;
APValue::LValueBase Base;
QualType T;
public:
Cleanup(APValue *Val, APValue::LValueBase Base, QualType T,
ScopeKind Scope)
: Value(Val, Scope), Base(Base), T(T) {}
/// Determine whether this cleanup should be performed at the end of the
/// given kind of scope.
bool isDestroyedAtEndOf(ScopeKind K) const {
return (int)Value.getInt() >= (int)K;
}
bool endLifetime(EvalInfo &Info, bool RunDestructors) {
if (RunDestructors) {
SourceLocation Loc;
if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
Loc = VD->getLocation();
else if (const Expr *E = Base.dyn_cast<const Expr*>())
Loc = E->getExprLoc();
return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T);
}
*Value.getPointer() = APValue();
return true;
}
bool hasSideEffect() {
return T.isDestructedType();
}
};
/// A reference to an object whose construction we are currently evaluating.
struct ObjectUnderConstruction {
APValue::LValueBase Base;
ArrayRef<APValue::LValuePathEntry> Path;
friend bool operator==(const ObjectUnderConstruction &LHS,
const ObjectUnderConstruction &RHS) {
return LHS.Base == RHS.Base && LHS.Path == RHS.Path;
}
friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) {
return llvm::hash_combine(Obj.Base, Obj.Path);
}
};
enum class ConstructionPhase {
None,
Bases,
AfterBases,
AfterFields,
Destroying,
DestroyingBases
};
}
namespace llvm {
template<> struct DenseMapInfo<ObjectUnderConstruction> {
using Base = DenseMapInfo<APValue::LValueBase>;
static ObjectUnderConstruction getEmptyKey() {
return {Base::getEmptyKey(), {}}; }
static ObjectUnderConstruction getTombstoneKey() {
return {Base::getTombstoneKey(), {}};
}
static unsigned getHashValue(const ObjectUnderConstruction &Object) {
return hash_value(Object);
}
static bool isEqual(const ObjectUnderConstruction &LHS,
const ObjectUnderConstruction &RHS) {
return LHS == RHS;
}
};
}
namespace {
/// A dynamically-allocated heap object.
struct DynAlloc {
/// The value of this heap-allocated object.
APValue Value;
/// The allocating expression; used for diagnostics. Either a CXXNewExpr
/// or a CallExpr (the latter is for direct calls to operator new inside
/// std::allocator<T>::allocate).
const Expr *AllocExpr = nullptr;
enum Kind {
New,
ArrayNew,
StdAllocator
};
/// Get the kind of the allocation. This must match between allocation
/// and deallocation.
Kind getKind() const {
if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr))
return NE->isArray() ? ArrayNew : New;
assert(isa<CallExpr>(AllocExpr));
return StdAllocator;
}
};
struct DynAllocOrder {
bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const {
return L.getIndex() < R.getIndex();
}
};
/// EvalInfo - This is a private struct used by the evaluator to capture
/// information about a subexpression as it is folded. It retains information
/// about the AST context, but also maintains information about the folded
/// expression.
///
/// If an expression could be evaluated, it is still possible it is not a C
/// "integer constant expression" or constant expression. If not, this struct
/// captures information about how and why not.
///
/// One bit of information passed *into* the request for constant folding
/// indicates whether the subexpression is "evaluated" or not according to C
/// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
/// evaluate the expression regardless of what the RHS is, but C only allows
/// certain things in certain situations.
class EvalInfo : public interp::State {
public:
ASTContext &Ctx;
/// EvalStatus - Contains information about the evaluation.
Expr::EvalStatus &EvalStatus;
/// CurrentCall - The top of the constexpr call stack.
CallStackFrame *CurrentCall;
/// CallStackDepth - The number of calls in the call stack right now.
unsigned CallStackDepth;
/// NextCallIndex - The next call index to assign.
unsigned NextCallIndex;
/// StepsLeft - The remaining number of evaluation steps we're permitted
/// to perform. This is essentially a limit for the number of statements
/// we will evaluate.
unsigned StepsLeft;
/// Enable the experimental new constant interpreter. If an expression is
/// not supported by the interpreter, an error is triggered.
bool EnableNewConstInterp;
/// BottomFrame - The frame in which evaluation started. This must be
/// initialized after CurrentCall and CallStackDepth.
CallStackFrame BottomFrame;
/// A stack of values whose lifetimes end at the end of some surrounding
/// evaluation frame.
llvm::SmallVector<Cleanup, 16> CleanupStack;
/// EvaluatingDecl - This is the declaration whose initializer is being
/// evaluated, if any.
APValue::LValueBase EvaluatingDecl;
enum class EvaluatingDeclKind {
None,
/// We're evaluating the construction of EvaluatingDecl.
Ctor,
/// We're evaluating the destruction of EvaluatingDecl.
Dtor,
};
EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None;
/// EvaluatingDeclValue - This is the value being constructed for the
/// declaration whose initializer is being evaluated, if any.
APValue *EvaluatingDeclValue;
/// Set of objects that are currently being constructed.
llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase>
ObjectsUnderConstruction;
/// Current heap allocations, along with the location where each was
/// allocated. We use std::map here because we need stable addresses
/// for the stored APValues.
std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs;
/// The number of heap allocations performed so far in this evaluation.
unsigned NumHeapAllocs = 0;
struct EvaluatingConstructorRAII {
EvalInfo &EI;
ObjectUnderConstruction Object;
bool DidInsert;
EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object,
bool HasBases)
: EI(EI), Object(Object) {
DidInsert =
EI.ObjectsUnderConstruction
.insert({Object, HasBases ? ConstructionPhase::Bases
: ConstructionPhase::AfterBases})
.second;
}
void finishedConstructingBases() {
EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases;
}
void finishedConstructingFields() {
EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields;
}
~EvaluatingConstructorRAII() {
if (DidInsert) EI.ObjectsUnderConstruction.erase(Object);
}
};
struct EvaluatingDestructorRAII {
EvalInfo &EI;
ObjectUnderConstruction Object;
bool DidInsert;
EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object)
: EI(EI), Object(Object) {
DidInsert = EI.ObjectsUnderConstruction
.insert({Object, ConstructionPhase::Destroying})
.second;
}
void startedDestroyingBases() {
EI.ObjectsUnderConstruction[Object] =
ConstructionPhase::DestroyingBases;
}
~EvaluatingDestructorRAII() {
if (DidInsert)
EI.ObjectsUnderConstruction.erase(Object);
}
};
ConstructionPhase
isEvaluatingCtorDtor(APValue::LValueBase Base,
ArrayRef<APValue::LValuePathEntry> Path) {
return ObjectsUnderConstruction.lookup({Base, Path});
}
/// If we're currently speculatively evaluating, the outermost call stack
/// depth at which we can mutate state, otherwise 0.
unsigned SpeculativeEvaluationDepth = 0;
/// The current array initialization index, if we're performing array
/// initialization.
uint64_t ArrayInitIndex = -1;
/// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further
/// notes attached to it will also be stored, otherwise they will not be.
bool HasActiveDiagnostic;
/// Have we emitted a diagnostic explaining why we couldn't constant
/// fold (not just why it's not strictly a constant expression)?
bool HasFoldFailureDiagnostic;
/// Whether or not we're in a context where the front end requires a
/// constant value.
bool InConstantContext;
/// Whether we're checking that an expression is a potential constant
/// expression. If so, do not fail on constructs that could become constant
/// later on (such as a use of an undefined global).
bool CheckingPotentialConstantExpression = false;
/// Whether we're checking for an expression that has undefined behavior.
/// If so, we will produce warnings if we encounter an operation that is
/// always undefined.
///
/// Note that we still need to evaluate the expression normally when this
/// is set; this is used when evaluating ICEs in C.
bool CheckingForUndefinedBehavior = false;
enum EvaluationMode {
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression.
EM_ConstantExpression,
/// Evaluate as a constant expression. Stop if we find that the expression
/// is not a constant expression. Some expressions can be retried in the
/// optimizer if we don't constant fold them here, but in an unevaluated
/// context we try to fold them immediately since the optimizer never
/// gets a chance to look at it.
EM_ConstantExpressionUnevaluated,
/// Fold the expression to a constant. Stop if we hit a side-effect that
/// we can't model.
EM_ConstantFold,
/// Evaluate in any way we know how. Don't worry about side-effects that
/// can't be modeled.
EM_IgnoreSideEffects,
} EvalMode;
/// Are we checking whether the expression is a potential constant
/// expression?
bool checkingPotentialConstantExpression() const override {
return CheckingPotentialConstantExpression;
}
/// Are we checking an expression for overflow?
// FIXME: We should check for any kind of undefined or suspicious behavior
// in such constructs, not just overflow.
bool checkingForUndefinedBehavior() const override {
return CheckingForUndefinedBehavior;
}
EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode)
: Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr),
CallStackDepth(0), NextCallIndex(1),
StepsLeft(C.getLangOpts().ConstexprStepLimit),
EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp),
BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()),
EvaluatingDecl((const ValueDecl *)nullptr),
EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false),
HasFoldFailureDiagnostic(false), InConstantContext(false),
EvalMode(Mode) {}
~EvalInfo() {
discardCleanups();
}
void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value,
EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) {
EvaluatingDecl = Base;
IsEvaluatingDecl = EDK;
EvaluatingDeclValue = &Value;
}
bool CheckCallLimit(SourceLocation Loc) {
// Don't perform any constexpr calls (other than the call we're checking)
// when checking a potential constant expression.
if (checkingPotentialConstantExpression() && CallStackDepth > 1)
return false;
if (NextCallIndex == 0) {
// NextCallIndex has wrapped around.
FFDiag(Loc, diag::note_constexpr_call_limit_exceeded);
return false;
}
if (CallStackDepth <= getLangOpts().ConstexprCallDepth)
return true;
FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded)
<< getLangOpts().ConstexprCallDepth;
return false;
}
std::pair<CallStackFrame *, unsigned>
getCallFrameAndDepth(unsigned CallIndex) {
assert(CallIndex && "no call index in getCallFrameAndDepth");
// We will eventually hit BottomFrame, which has Index 1, so Frame can't
// be null in this loop.
unsigned Depth = CallStackDepth;
CallStackFrame *Frame = CurrentCall;
while (Frame->Index > CallIndex) {
Frame = Frame->Caller;
--Depth;
}
if (Frame->Index == CallIndex)
return {Frame, Depth};
return {nullptr, 0};
}
bool nextStep(const Stmt *S) {
if (!StepsLeft) {
FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded);
return false;
}
--StepsLeft;
return true;
}
APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV);
Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) {
Optional<DynAlloc*> Result;
auto It = HeapAllocs.find(DA);
if (It != HeapAllocs.end())
Result = &It->second;
return Result;
}
/// Get the allocated storage for the given parameter of the given call.
APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) {
CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first;
return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version)
: nullptr;
}
/// Information about a stack frame for std::allocator<T>::[de]allocate.
struct StdAllocatorCaller {
unsigned FrameIndex;
QualType ElemType;
explicit operator bool() const { return FrameIndex != 0; };
};
StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const {
for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame;
Call = Call->Caller) {
const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee);
if (!MD)
continue;
const IdentifierInfo *FnII = MD->getIdentifier();
if (!FnII || !FnII->isStr(FnName))
continue;
const auto *CTSD =
dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent());
if (!CTSD)
continue;
const IdentifierInfo *ClassII = CTSD->getIdentifier();
const TemplateArgumentList &TAL = CTSD->getTemplateArgs();
if (CTSD->isInStdNamespace() && ClassII &&
ClassII->isStr("allocator") && TAL.size() >= 1 &&
TAL[0].getKind() == TemplateArgument::Type)
return {Call->Index, TAL[0].getAsType()};
}
return {};
}
void performLifetimeExtension() {
// Disable the cleanups for lifetime-extended temporaries.
CleanupStack.erase(std::remove_if(CleanupStack.begin(),
CleanupStack.end(),
[](Cleanup &C) {
return !C.isDestroyedAtEndOf(
ScopeKind::FullExpression);
}),
CleanupStack.end());
}
/// Throw away any remaining cleanups at the end of evaluation. If any
/// cleanups would have had a side-effect, note that as an unmodeled
/// side-effect and return false. Otherwise, return true.
bool discardCleanups() {
for (Cleanup &C : CleanupStack) {
if (C.hasSideEffect() && !noteSideEffect()) {
CleanupStack.clear();
return false;
}
}
CleanupStack.clear();
return true;
}
private:
interp::Frame *getCurrentFrame() override { return CurrentCall; }
const interp::Frame *getBottomFrame() const override { return &BottomFrame; }
bool hasActiveDiagnostic() override { return HasActiveDiagnostic; }
void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; }
void setFoldFailureDiagnostic(bool Flag) override {
HasFoldFailureDiagnostic = Flag;
}
Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; }
ASTContext &getCtx() const override { return Ctx; }
// If we have a prior diagnostic, it will be noting that the expression
// isn't a constant expression. This diagnostic is more important,
// unless we require this evaluation to produce a constant expression.
//
// FIXME: We might want to show both diagnostics to the user in
// EM_ConstantFold mode.
bool hasPriorDiagnostic() override {
if (!EvalStatus.Diag->empty()) {
switch (EvalMode) {
case EM_ConstantFold:
case EM_IgnoreSideEffects:
if (!HasFoldFailureDiagnostic)
break;
// We've already failed to fold something. Keep that diagnostic.
LLVM_FALLTHROUGH;
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
setActiveDiagnostic(false);
return true;
}
}
return false;
}
unsigned getCallStackDepth() override { return CallStackDepth; }
public:
/// Should we continue evaluation after encountering a side-effect that we
/// couldn't model?
bool keepEvaluatingAfterSideEffect() {
switch (EvalMode) {
case EM_IgnoreSideEffects:
return true;
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
case EM_ConstantFold:
// By default, assume any side effect might be valid in some other
// evaluation of this expression from a different context.
return checkingPotentialConstantExpression() ||
checkingForUndefinedBehavior();
}
llvm_unreachable("Missed EvalMode case");
}
/// Note that we have had a side-effect, and determine whether we should
/// keep evaluating.
bool noteSideEffect() {
EvalStatus.HasSideEffects = true;
return keepEvaluatingAfterSideEffect();
}
/// Should we continue evaluation after encountering undefined behavior?
bool keepEvaluatingAfterUndefinedBehavior() {
switch (EvalMode) {
case EM_IgnoreSideEffects:
case EM_ConstantFold:
return true;
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
return checkingForUndefinedBehavior();
}
llvm_unreachable("Missed EvalMode case");
}
/// Note that we hit something that was technically undefined behavior, but
/// that we can evaluate past it (such as signed overflow or floating-point
/// division by zero.)
bool noteUndefinedBehavior() override {
EvalStatus.HasUndefinedBehavior = true;
return keepEvaluatingAfterUndefinedBehavior();
}
/// Should we continue evaluation as much as possible after encountering a
/// construct which can't be reduced to a value?
bool keepEvaluatingAfterFailure() const override {
if (!StepsLeft)
return false;
switch (EvalMode) {
case EM_ConstantExpression:
case EM_ConstantExpressionUnevaluated:
case EM_ConstantFold:
case EM_IgnoreSideEffects:
return checkingPotentialConstantExpression() ||
checkingForUndefinedBehavior();
}
llvm_unreachable("Missed EvalMode case");
}
/// Notes that we failed to evaluate an expression that other expressions
/// directly depend on, and determine if we should keep evaluating. This
/// should only be called if we actually intend to keep evaluating.
///
/// Call noteSideEffect() instead if we may be able to ignore the value that
/// we failed to evaluate, e.g. if we failed to evaluate Foo() in:
///
/// (Foo(), 1) // use noteSideEffect
/// (Foo() || true) // use noteSideEffect
/// Foo() + 1 // use noteFailure
LLVM_NODISCARD bool noteFailure() {
// Failure when evaluating some expression often means there is some
// subexpression whose evaluation was skipped. Therefore, (because we
// don't track whether we skipped an expression when unwinding after an
// evaluation failure) every evaluation failure that bubbles up from a
// subexpression implies that a side-effect has potentially happened. We
// skip setting the HasSideEffects flag to true until we decide to
// continue evaluating after that point, which happens here.
bool KeepGoing = keepEvaluatingAfterFailure();
EvalStatus.HasSideEffects |= KeepGoing;
return KeepGoing;
}
class ArrayInitLoopIndex {
EvalInfo &Info;
uint64_t OuterIndex;
public:
ArrayInitLoopIndex(EvalInfo &Info)
: Info(Info), OuterIndex(Info.ArrayInitIndex) {
Info.ArrayInitIndex = 0;
}
~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; }
operator uint64_t&() { return Info.ArrayInitIndex; }
};
};
/// Object used to treat all foldable expressions as constant expressions.
struct FoldConstant {
EvalInfo &Info;
bool Enabled;
bool HadNoPriorDiags;
EvalInfo::EvaluationMode OldMode;
explicit FoldConstant(EvalInfo &Info, bool Enabled)
: Info(Info),
Enabled(Enabled),
HadNoPriorDiags(Info.EvalStatus.Diag &&
Info.EvalStatus.Diag->empty() &&
!Info.EvalStatus.HasSideEffects),
OldMode(Info.EvalMode) {
if (Enabled)
Info.EvalMode = EvalInfo::EM_ConstantFold;
}
void keepDiagnostics() { Enabled = false; }
~FoldConstant() {
if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() &&
!Info.EvalStatus.HasSideEffects)
Info.EvalStatus.Diag->clear();
Info.EvalMode = OldMode;
}
};
/// RAII object used to set the current evaluation mode to ignore
/// side-effects.
struct IgnoreSideEffectsRAII {
EvalInfo &Info;
EvalInfo::EvaluationMode OldMode;
explicit IgnoreSideEffectsRAII(EvalInfo &Info)
: Info(Info), OldMode(Info.EvalMode) {
Info.EvalMode = EvalInfo::EM_IgnoreSideEffects;
}
~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; }
};
/// RAII object used to optionally suppress diagnostics and side-effects from
/// a speculative evaluation.
class SpeculativeEvaluationRAII {
EvalInfo *Info = nullptr;
Expr::EvalStatus OldStatus;
unsigned OldSpeculativeEvaluationDepth;
void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) {
Info = Other.Info;
OldStatus = Other.OldStatus;
OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth;
Other.Info = nullptr;
}
void maybeRestoreState() {
if (!Info)
return;
Info->EvalStatus = OldStatus;
Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth;
}
public:
SpeculativeEvaluationRAII() = default;
SpeculativeEvaluationRAII(
EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr)
: Info(&Info), OldStatus(Info.EvalStatus),
OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) {
Info.EvalStatus.Diag = NewDiag;
Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1;
}
SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete;
SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) {
moveFromAndCancel(std::move(Other));
}
SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) {
maybeRestoreState();
moveFromAndCancel(std::move(Other));
return *this;
}
~SpeculativeEvaluationRAII() { maybeRestoreState(); }
};
/// RAII object wrapping a full-expression or block scope, and handling
/// the ending of the lifetime of temporaries created within it.
template<ScopeKind Kind>
class ScopeRAII {
EvalInfo &Info;
unsigned OldStackSize;
public:
ScopeRAII(EvalInfo &Info)
: Info(Info), OldStackSize(Info.CleanupStack.size()) {
// Push a new temporary version. This is needed to distinguish between
// temporaries created in different iterations of a loop.
Info.CurrentCall->pushTempVersion();
}
bool destroy(bool RunDestructors = true) {
bool OK = cleanup(Info, RunDestructors, OldStackSize);
OldStackSize = -1U;
return OK;
}
~ScopeRAII() {
if (OldStackSize != -1U)
destroy(false);
// Body moved to a static method to encourage the compiler to inline away
// instances of this class.
Info.CurrentCall->popTempVersion();
}
private:
static bool cleanup(EvalInfo &Info, bool RunDestructors,
unsigned OldStackSize) {
assert(OldStackSize <= Info.CleanupStack.size() &&
"running cleanups out of order?");
// Run all cleanups for a block scope, and non-lifetime-extended cleanups
// for a full-expression scope.
bool Success = true;
for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) {
if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) {
if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) {
Success = false;
break;
}
}
}
// Compact any retained cleanups.
auto NewEnd = Info.CleanupStack.begin() + OldStackSize;
if (Kind != ScopeKind::Block)
NewEnd =
std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) {
return C.isDestroyedAtEndOf(Kind);
});
Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end());
return Success;
}
};
typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII;
typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII;
typedef ScopeRAII<ScopeKind::Call> CallScopeRAII;
}
bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E,
CheckSubobjectKind CSK) {
if (Invalid)
return false;
if (isOnePastTheEnd()) {
Info.CCEDiag(E, diag::note_constexpr_past_end_subobject)
<< CSK;
setInvalid();
return false;
}
// Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there
// must actually be at least one array element; even a VLA cannot have a
// bound of zero. And if our index is nonzero, we already had a CCEDiag.
return true;
}
void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info,
const Expr *E) {
Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed);
// Do not set the designator as invalid: we can represent this situation,
// and correct handling of __builtin_object_size requires us to do so.
}
void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info,
const Expr *E,
const APSInt &N) {
// If we're complaining, we must be able to statically determine the size of
// the most derived array.
if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement)
Info.CCEDiag(E, diag::note_constexpr_array_index)
<< N << /*array*/ 0
<< static_cast<unsigned>(getMostDerivedArraySize());
else
Info.CCEDiag(E, diag::note_constexpr_array_index)
<< N << /*non-array*/ 1;
setInvalid();
}
CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
CallRef Call)
: Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This),
Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) {
Info.CurrentCall = this;
++Info.CallStackDepth;
}
CallStackFrame::~CallStackFrame() {
assert(Info.CurrentCall == this && "calls retired out of order");
--Info.CallStackDepth;
Info.CurrentCall = Caller;
}
static bool isRead(AccessKinds AK) {
return AK == AK_Read || AK == AK_ReadObjectRepresentation;
}
static bool isModification(AccessKinds AK) {
switch (AK) {
case AK_Read:
case AK_ReadObjectRepresentation:
case AK_MemberCall:
case AK_DynamicCast:
case AK_TypeId:
return false;
case AK_Assign:
case AK_Increment:
case AK_Decrement:
case AK_Construct:
case AK_Destroy:
return true;
}
llvm_unreachable("unknown access kind");
}
static bool isAnyAccess(AccessKinds AK) {
return isRead(AK) || isModification(AK);
}
/// Is this an access per the C++ definition?
static bool isFormalAccess(AccessKinds AK) {
return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy;
}
/// Is this kind of axcess valid on an indeterminate object value?
static bool isValidIndeterminateAccess(AccessKinds AK) {
switch (AK) {
case AK_Read:
case AK_Increment:
case AK_Decrement:
// These need the object's value.
return false;
case AK_ReadObjectRepresentation:
case AK_Assign:
case AK_Construct:
case AK_Destroy:
// Construction and destruction don't need the value.
return true;
case AK_MemberCall:
case AK_DynamicCast:
case AK_TypeId:
// These aren't really meaningful on scalars.
return true;
}
llvm_unreachable("unknown access kind");
}
namespace {
struct ComplexValue {
private:
bool IsInt;
public:
APSInt IntReal, IntImag;
APFloat FloatReal, FloatImag;
ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {}
void makeComplexFloat() { IsInt = false; }
bool isComplexFloat() const { return !IsInt; }
APFloat &getComplexFloatReal() { return FloatReal; }
APFloat &getComplexFloatImag() { return FloatImag; }
void makeComplexInt() { IsInt = true; }
bool isComplexInt() const { return IsInt; }
APSInt &getComplexIntReal() { return IntReal; }
APSInt &getComplexIntImag() { return IntImag; }
void moveInto(APValue &v) const {
if (isComplexFloat())
v = APValue(FloatReal, FloatImag);
else
v = APValue(IntReal, IntImag);
}
void setFrom(const APValue &v) {
assert(v.isComplexFloat() || v.isComplexInt());
if (v.isComplexFloat()) {
makeComplexFloat();
FloatReal = v.getComplexFloatReal();
FloatImag = v.getComplexFloatImag();
} else {
makeComplexInt();
IntReal = v.getComplexIntReal();
IntImag = v.getComplexIntImag();
}
}
};
struct LValue {
APValue::LValueBase Base;
CharUnits Offset;
SubobjectDesignator Designator;
bool IsNullPtr : 1;
bool InvalidBase : 1;
const APValue::LValueBase getLValueBase() const { return Base; }
CharUnits &getLValueOffset() { return Offset; }
const CharUnits &getLValueOffset() const { return Offset; }
SubobjectDesignator &getLValueDesignator() { return Designator; }
const SubobjectDesignator &getLValueDesignator() const { return Designator;}
bool isNullPointer() const { return IsNullPtr;}
unsigned getLValueCallIndex() const { return Base.getCallIndex(); }
unsigned getLValueVersion() const { return Base.getVersion(); }
void moveInto(APValue &V) const {
if (Designator.Invalid)
V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr);
else {
assert(!InvalidBase && "APValues can't handle invalid LValue bases");
V = APValue(Base, Offset, Designator.Entries,
Designator.IsOnePastTheEnd, IsNullPtr);
}
}
void setFrom(ASTContext &Ctx, const APValue &V) {
assert(V.isLValue() && "Setting LValue from a non-LValue?");
Base = V.getLValueBase();
Offset = V.getLValueOffset();
InvalidBase = false;
Designator = SubobjectDesignator(Ctx, V);
IsNullPtr = V.isNullPointer();
}
void set(APValue::LValueBase B, bool BInvalid = false) {
#ifndef NDEBUG
// We only allow a few types of invalid bases. Enforce that here.
if (BInvalid) {
const auto *E = B.get<const Expr *>();
assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) &&
"Unexpected type of invalid base");
}
#endif
Base = B;
Offset = CharUnits::fromQuantity(0);
InvalidBase = BInvalid;
Designator = SubobjectDesignator(getType(B));
IsNullPtr = false;
}
void setNull(ASTContext &Ctx, QualType PointerTy) {
Base = (const ValueDecl *)nullptr;
Offset =
CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy));
InvalidBase = false;
Designator = SubobjectDesignator(PointerTy->getPointeeType());
IsNullPtr = true;
}
void setInvalid(APValue::LValueBase B, unsigned I = 0) {
set(B, true);
}
std::string toString(ASTContext &Ctx, QualType T) const {
APValue Printable;
moveInto(Printable);
return Printable.getAsString(Ctx, T);
}
private:
// Check that this LValue is not based on a null pointer. If it is, produce
// a diagnostic and mark the designator as invalid.
template <typename GenDiagType>
bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) {
if (Designator.Invalid)
return false;
if (IsNullPtr) {
GenDiag();
Designator.setInvalid();
return false;
}
return true;
}
public:
bool checkNullPointer(EvalInfo &Info, const Expr *E,
CheckSubobjectKind CSK) {
return checkNullPointerDiagnosingWith([&Info, E, CSK] {
Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK;
});
}
bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E,
AccessKinds AK) {
return checkNullPointerDiagnosingWith([&Info, E, AK] {
Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
});
}
// Check this LValue refers to an object. If not, set the designator to be
// invalid and emit a diagnostic.
bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) {
return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) &&
Designator.checkSubobject(Info, E, CSK);
}
void addDecl(EvalInfo &Info, const Expr *E,
const Decl *D, bool Virtual = false) {
if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base))
Designator.addDeclUnchecked(D, Virtual);
}
void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) {
if (!Designator.Entries.empty()) {
Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array);
Designator.setInvalid();
return;
}
if (checkSubobject(Info, E, CSK_ArrayToPointer)) {
assert(getType(Base)->isPointerType() || getType(Base)->isArrayType());
Designator.FirstEntryIsAnUnsizedArray = true;
Designator.addUnsizedArrayUnchecked(ElemTy);
}
}
void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) {
if (checkSubobject(Info, E, CSK_ArrayToPointer))
Designator.addArrayUnchecked(CAT);
}
void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) {
if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real))
Designator.addComplexUnchecked(EltTy, Imag);
}
void clearIsNullPointer() {
IsNullPtr = false;
}
void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E,
const APSInt &Index, CharUnits ElementSize) {
// An index of 0 has no effect. (In C, adding 0 to a null pointer is UB,
// but we're not required to diagnose it and it's valid in C++.)
if (!Index)
return;
// Compute the new offset in the appropriate width, wrapping at 64 bits.
// FIXME: When compiling for a 32-bit target, we should use 32-bit
// offsets.
uint64_t Offset64 = Offset.getQuantity();
uint64_t ElemSize64 = ElementSize.getQuantity();
uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64);
if (checkNullPointer(Info, E, CSK_ArrayIndex))
Designator.adjustIndex(Info, E, Index);
clearIsNullPointer();
}
void adjustOffset(CharUnits N) {
Offset += N;
if (N.getQuantity())
clearIsNullPointer();
}
};
struct MemberPtr {
MemberPtr() {}
explicit MemberPtr(const ValueDecl *Decl) :
DeclAndIsDerivedMember(Decl, false), Path() {}
/// The member or (direct or indirect) field referred to by this member
/// pointer, or 0 if this is a null member pointer.
const ValueDecl *getDecl() const {
return DeclAndIsDerivedMember.getPointer();
}
/// Is this actually a member of some type derived from the relevant class?
bool isDerivedMember() const {
return DeclAndIsDerivedMember.getInt();
}
/// Get the class which the declaration actually lives in.
const CXXRecordDecl *getContainingRecord() const {
return cast<CXXRecordDecl>(
DeclAndIsDerivedMember.getPointer()->getDeclContext());
}
void moveInto(APValue &V) const {
V = APValue(getDecl(), isDerivedMember(), Path);
}
void setFrom(const APValue &V) {
assert(V.isMemberPointer());
DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl());
DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember());
Path.clear();
ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath();
Path.insert(Path.end(), P.begin(), P.end());
}
/// DeclAndIsDerivedMember - The member declaration, and a flag indicating
/// whether the member is a member of some class derived from the class type
/// of the member pointer.
llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember;
/// Path - The path of base/derived classes from the member declaration's
/// class (exclusive) to the class type of the member pointer (inclusive).
SmallVector<const CXXRecordDecl*, 4> Path;
/// Perform a cast towards the class of the Decl (either up or down the
/// hierarchy).
bool castBack(const CXXRecordDecl *Class) {
assert(!Path.empty());
const CXXRecordDecl *Expected;
if (Path.size() >= 2)
Expected = Path[Path.size() - 2];
else
Expected = getContainingRecord();
if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) {
// C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*),
// if B does not contain the original member and is not a base or
// derived class of the class containing the original member, the result
// of the cast is undefined.
// C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to
// (D::*). We consider that to be a language defect.
return false;
}
Path.pop_back();
return true;
}
/// Perform a base-to-derived member pointer cast.
bool castToDerived(const CXXRecordDecl *Derived) {
if (!getDecl())
return true;
if (!isDerivedMember()) {
Path.push_back(Derived);
return true;
}
if (!castBack(Derived))
return false;
if (Path.empty())
DeclAndIsDerivedMember.setInt(false);
return true;
}
/// Perform a derived-to-base member pointer cast.
bool castToBase(const CXXRecordDecl *Base) {
if (!getDecl())
return true;
if (Path.empty())
DeclAndIsDerivedMember.setInt(true);
if (isDerivedMember()) {
Path.push_back(Base);
return true;
}
return castBack(Base);
}
};
/// Compare two member pointers, which are assumed to be of the same type.
static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) {
if (!LHS.getDecl() || !RHS.getDecl())
return !LHS.getDecl() && !RHS.getDecl();
if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl())
return false;
return LHS.Path == RHS.Path;
}
}
static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E);
static bool EvaluateInPlace(APValue &Result, EvalInfo &Info,
const LValue &This, const Expr *E,
bool AllowNonLiteralTypes = false);
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK = false);
static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK = false);
static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
EvalInfo &Info);
static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info);
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
EvalInfo &Info);
static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info);
static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
EvalInfo &Info);
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result);
/// Evaluate an integer or fixed point expression into an APResult.
static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
EvalInfo &Info);
/// Evaluate only a fixed point expression into an APResult.
static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
EvalInfo &Info);
//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//
/// Negate an APSInt in place, converting it to a signed form if necessary, and
/// preserving its value (by extending by up to one bit as needed).
static void negateAsSigned(APSInt &Int) {
if (Int.isUnsigned() || Int.isMinSignedValue()) {
Int = Int.extend(Int.getBitWidth() + 1);
Int.setIsSigned(true);
}
Int = -Int;
}
template<typename KeyT>
APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T,
ScopeKind Scope, LValue &LV) {
unsigned Version = getTempVersion();
APValue::LValueBase Base(Key, Index, Version);
LV.set(Base);
return createLocal(Base, Key, T, Scope);
}
/// Allocate storage for a parameter of a function call made in this frame.
APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD,
LValue &LV) {
assert(Args.CallIndex == Index && "creating parameter in wrong frame");
APValue::LValueBase Base(PVD, Index, Args.Version);
LV.set(Base);
// We always destroy parameters at the end of the call, even if we'd allow
// them to live to the end of the full-expression at runtime, in order to
// give portable results and match other compilers.
return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call);
}
APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key,
QualType T, ScopeKind Scope) {
assert(Base.getCallIndex() == Index && "lvalue for wrong frame");
unsigned Version = Base.getVersion();
APValue &Result = Temporaries[MapKeyTy(Key, Version)];
assert(Result.isAbsent() && "local created multiple times");
// If we're creating a local immediately in the operand of a speculative
// evaluation, don't register a cleanup to be run outside the speculative
// evaluation context, since we won't actually be able to initialize this
// object.
if (Index <= Info.SpeculativeEvaluationDepth) {
if (T.isDestructedType())
Info.noteSideEffect();
} else {
Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope));
}
return Result;
}
APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) {
if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) {
FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded);
return nullptr;
}
DynamicAllocLValue DA(NumHeapAllocs++);
LV.set(APValue::LValueBase::getDynamicAlloc(DA, T));
auto Result = HeapAllocs.emplace(std::piecewise_construct,
std::forward_as_tuple(DA), std::tuple<>());
assert(Result.second && "reused a heap alloc index?");
Result.first->second.AllocExpr = E;
return &Result.first->second.Value;
}
/// Produce a string describing the given constexpr call.
void CallStackFrame::describe(raw_ostream &Out) {
unsigned ArgIndex = 0;
bool IsMemberCall = isa<CXXMethodDecl>(Callee) &&
!isa<CXXConstructorDecl>(Callee) &&
cast<CXXMethodDecl>(Callee)->isInstance();
if (!IsMemberCall)
Out << *Callee << '(';
if (This && IsMemberCall) {
APValue Val;
This->moveInto(Val);
Val.printPretty(Out, Info.Ctx,
This->Designator.MostDerivedType);
// FIXME: Add parens around Val if needed.
Out << "->" << *Callee << '(';
IsMemberCall = false;
}
for (FunctionDecl::param_const_iterator I = Callee->param_begin(),
E = Callee->param_end(); I != E; ++I, ++ArgIndex) {
if (ArgIndex > (unsigned)IsMemberCall)
Out << ", ";
const ParmVarDecl *Param = *I;
APValue *V = Info.getParamSlot(Arguments, Param);
if (V)
V->printPretty(Out, Info.Ctx, Param->getType());
else
Out << "<...>";
if (ArgIndex == 0 && IsMemberCall)
Out << "->" << *Callee << '(';
}
Out << ')';
}
/// Evaluate an expression to see if it had side-effects, and discard its
/// result.
/// \return \c true if the caller should keep evaluating.
static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) {
assert(!E->isValueDependent());
APValue Scratch;
if (!Evaluate(Scratch, Info, E))
// We don't need the value, but we might have skipped a side effect here.
return Info.noteSideEffect();
return true;
}
/// Should this call expression be treated as a string literal?
static bool IsStringLiteralCall(const CallExpr *E) {
unsigned Builtin = E->getBuiltinCallee();
return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString ||
Builtin == Builtin::BI__builtin___NSStringMakeConstantString);
}
static bool IsGlobalLValue(APValue::LValueBase B) {
// C++11 [expr.const]p3 An address constant expression is a prvalue core
// constant expression of pointer type that evaluates to...
// ... a null pointer value, or a prvalue core constant expression of type
// std::nullptr_t.
if (!B) return true;
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
// ... the address of an object with static storage duration,
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return VD->hasGlobalStorage();
if (isa<TemplateParamObjectDecl>(D))
return true;
// ... the address of a function,
// ... the address of a GUID [MS extension],
return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D);
}
if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>())
return true;
const Expr *E = B.get<const Expr*>();
switch (E->getStmtClass()) {
default:
return false;
case Expr::CompoundLiteralExprClass: {
const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E);
return CLE->isFileScope() && CLE->isLValue();
}
case Expr::MaterializeTemporaryExprClass:
// A materialized temporary might have been lifetime-extended to static
// storage duration.
return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static;
// A string literal has static storage duration.
case Expr::StringLiteralClass:
case Expr::PredefinedExprClass:
case Expr::ObjCStringLiteralClass:
case Expr::ObjCEncodeExprClass:
return true;
case Expr::ObjCBoxedExprClass:
return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer();
case Expr::CallExprClass:
return IsStringLiteralCall(cast<CallExpr>(E));
// For GCC compatibility, &&label has static storage duration.
case Expr::AddrLabelExprClass:
return true;
// A Block literal expression may be used as the initialization value for
// Block variables at global or local static scope.
case Expr::BlockExprClass:
return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures();
case Expr::ImplicitValueInitExprClass:
// FIXME:
// We can never form an lvalue with an implicit value initialization as its
// base through expression evaluation, so these only appear in one case: the
// implicit variable declaration we invent when checking whether a constexpr
// constructor can produce a constant expression. We must assume that such
// an expression might be a global lvalue.
return true;
}
}
static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) {
return LVal.Base.dyn_cast<const ValueDecl*>();
}
static bool IsLiteralLValue(const LValue &Value) {
if (Value.getLValueCallIndex())
return false;
const Expr *E = Value.Base.dyn_cast<const Expr*>();
return E && !isa<MaterializeTemporaryExpr>(E);
}
static bool IsWeakLValue(const LValue &Value) {
const ValueDecl *Decl = GetLValueBaseDecl(Value);
return Decl && Decl->isWeak();
}
static bool isZeroSized(const LValue &Value) {
const ValueDecl *Decl = GetLValueBaseDecl(Value);
if (Decl && isa<VarDecl>(Decl)) {
QualType Ty = Decl->getType();
if (Ty->isArrayType())
return Ty->isIncompleteType() ||
Decl->getASTContext().getTypeSize(Ty) == 0;
}
return false;
}
static bool HasSameBase(const LValue &A, const LValue &B) {
if (!A.getLValueBase())
return !B.getLValueBase();
if (!B.getLValueBase())
return false;
if (A.getLValueBase().getOpaqueValue() !=
B.getLValueBase().getOpaqueValue())
return false;
return A.getLValueCallIndex() == B.getLValueCallIndex() &&
A.getLValueVersion() == B.getLValueVersion();
}
static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) {
assert(Base && "no location for a null lvalue");
const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
// For a parameter, find the corresponding call stack frame (if it still
// exists), and point at the parameter of the function definition we actually
// invoked.
if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) {
unsigned Idx = PVD->getFunctionScopeIndex();
for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) {
if (F->Arguments.CallIndex == Base.getCallIndex() &&
F->Arguments.Version == Base.getVersion() && F->Callee &&
Idx < F->Callee->getNumParams()) {
VD = F->Callee->getParamDecl(Idx);
break;
}
}
}
if (VD)
Info.Note(VD->getLocation(), diag::note_declared_at);
else if (const Expr *E = Base.dyn_cast<const Expr*>())
Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here);
else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) {
// FIXME: Produce a note for dangling pointers too.
if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA))
Info.Note((*Alloc)->AllocExpr->getExprLoc(),
diag::note_constexpr_dynamic_alloc_here);
}
// We have no information to show for a typeid(T) object.
}
enum class CheckEvaluationResultKind {
ConstantExpression,
FullyInitialized,
};
/// Materialized temporaries that we've already checked to determine if they're
/// initializsed by a constant expression.
using CheckedTemporaries =
llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>;
static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
EvalInfo &Info, SourceLocation DiagLoc,
QualType Type, const APValue &Value,
ConstantExprKind Kind,
SourceLocation SubobjectLoc,
CheckedTemporaries &CheckedTemps);
/// Check that this reference or pointer core constant expression is a valid
/// value for an address or reference constant expression. Return true if we
/// can fold this expression, whether or not it's a constant expression.
static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc,
QualType Type, const LValue &LVal,
ConstantExprKind Kind,
CheckedTemporaries &CheckedTemps) {
bool IsReferenceType = Type->isReferenceType();
APValue::LValueBase Base = LVal.getLValueBase();
const SubobjectDesignator &Designator = LVal.getLValueDesignator();
const Expr *BaseE = Base.dyn_cast<const Expr *>();
const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>();
// Additional restrictions apply in a template argument. We only enforce the
// C++20 restrictions here; additional syntactic and semantic restrictions
// are applied elsewhere.
if (isTemplateArgument(Kind)) {
int InvalidBaseKind = -1;
StringRef Ident;
if (Base.is<TypeInfoLValue>())
InvalidBaseKind = 0;
else if (isa_and_nonnull<StringLiteral>(BaseE))
InvalidBaseKind = 1;
else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) ||
isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD))
InvalidBaseKind = 2;
else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) {
InvalidBaseKind = 3;
Ident = PE->getIdentKindName();
}
if (InvalidBaseKind != -1) {
Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg)
<< IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind
<< Ident;
return false;
}
}
if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) {
if (FD->isConsteval()) {
Info.FFDiag(Loc, diag::note_consteval_address_accessible)
<< !Type->isAnyPointerType();
Info.Note(FD->getLocation(), diag::note_declared_at);
return false;
}
}
// Check that the object is a global. Note that the fake 'this' object we
// manufacture when checking potential constant expressions is conservatively
// assumed to be global here.
if (!IsGlobalLValue(Base)) {
if (Info.getLangOpts().CPlusPlus11) {
const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>();
Info.FFDiag(Loc, diag::note_constexpr_non_global, 1)
<< IsReferenceType << !Designator.Entries.empty()
<< !!VD << VD;
auto *VarD = dyn_cast_or_null<VarDecl>(VD);
if (VarD && VarD->isConstexpr()) {
// Non-static local constexpr variables have unintuitive semantics:
// constexpr int a = 1;
// constexpr const int *p = &a;
// ... is invalid because the address of 'a' is not constant. Suggest
// adding a 'static' in this case.
Info.Note(VarD->getLocation(), diag::note_constexpr_not_static)
<< VarD
<< FixItHint::CreateInsertion(VarD->getBeginLoc(), "static ");
} else {
NoteLValueLocation(Info, Base);
}
} else {
Info.FFDiag(Loc);
}
// Don't allow references to temporaries to escape.
return false;
}
assert((Info.checkingPotentialConstantExpression() ||
LVal.getLValueCallIndex() == 0) &&
"have call index for global lvalue");
if (Base.is<DynamicAllocLValue>()) {
Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc)
<< IsReferenceType << !Designator.Entries.empty();
NoteLValueLocation(Info, Base);
return false;
}
if (BaseVD) {
if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) {
// Check if this is a thread-local variable.
if (Var->getTLSKind())
// FIXME: Diagnostic!
return false;
// A dllimport variable never acts like a constant, unless we're
// evaluating a value for use only in name mangling.
if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>())
// FIXME: Diagnostic!
return false;
}
if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) {
// __declspec(dllimport) must be handled very carefully:
// We must never initialize an expression with the thunk in C++.
// Doing otherwise would allow the same id-expression to yield
// different addresses for the same function in different translation
// units. However, this means that we must dynamically initialize the
// expression with the contents of the import address table at runtime.
//
// The C language has no notion of ODR; furthermore, it has no notion of
// dynamic initialization. This means that we are permitted to
// perform initialization with the address of the thunk.
if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) &&
FD->hasAttr<DLLImportAttr>())
// FIXME: Diagnostic!
return false;
}
} else if (const auto *MTE =
dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) {
if (CheckedTemps.insert(MTE).second) {
QualType TempType = getType(Base);
if (TempType.isDestructedType()) {
Info.FFDiag(MTE->getExprLoc(),
diag::note_constexpr_unsupported_temporary_nontrivial_dtor)
<< TempType;
return false;
}
APValue *V = MTE->getOrCreateValue(false);
assert(V && "evasluation result refers to uninitialised temporary");
if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
Info, MTE->getExprLoc(), TempType, *V,
Kind, SourceLocation(), CheckedTemps))
return false;
}
}
// Allow address constant expressions to be past-the-end pointers. This is
// an extension: the standard requires them to point to an object.
if (!IsReferenceType)
return true;
// A reference constant expression must refer to an object.
if (!Base) {
// FIXME: diagnostic
Info.CCEDiag(Loc);
return true;
}
// Does this refer one past the end of some object?
if (!Designator.Invalid && Designator.isOnePastTheEnd()) {
Info.FFDiag(Loc, diag::note_constexpr_past_end, 1)
<< !Designator.Entries.empty() << !!BaseVD << BaseVD;
NoteLValueLocation(Info, Base);
}
return true;
}
/// Member pointers are constant expressions unless they point to a
/// non-virtual dllimport member function.
static bool CheckMemberPointerConstantExpression(EvalInfo &Info,
SourceLocation Loc,
QualType Type,
const APValue &Value,
ConstantExprKind Kind) {
const ValueDecl *Member = Value.getMemberPointerDecl();
const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member);
if (!FD)
return true;
if (FD->isConsteval()) {
Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0;
Info.Note(FD->getLocation(), diag::note_declared_at);
return false;
}
return isForManglingOnly(Kind) || FD->isVirtual() ||
!FD->hasAttr<DLLImportAttr>();
}
/// Check that this core constant expression is of literal type, and if not,
/// produce an appropriate diagnostic.
static bool CheckLiteralType(EvalInfo &Info, const Expr *E,
const LValue *This = nullptr) {
if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx))
return true;
// C++1y: A constant initializer for an object o [...] may also invoke
// constexpr constructors for o and its subobjects even if those objects
// are of non-literal class types.
//
// C++11 missed this detail for aggregates, so classes like this:
// struct foo_t { union { int i; volatile int j; } u; };
// are not (obviously) initializable like so:
// __attribute__((__require_constant_initialization__))
// static const foo_t x = {{0}};
// because "i" is a subobject with non-literal initialization (due to the
// volatile member of the union). See:
// http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677
// Therefore, we use the C++1y behavior.
if (This && Info.EvaluatingDecl == This->getLValueBase())
return true;
// Prvalue constant expressions must be of literal types.
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_nonliteral)
<< E->getType();
else
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
static bool CheckEvaluationResult(CheckEvaluationResultKind CERK,
EvalInfo &Info, SourceLocation DiagLoc,
QualType Type, const APValue &Value,
ConstantExprKind Kind,
SourceLocation SubobjectLoc,
CheckedTemporaries &CheckedTemps) {
if (!Value.hasValue()) {
Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized)
<< true << Type;
if (SubobjectLoc.isValid())
Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here);
return false;
}
// We allow _Atomic(T) to be initialized from anything that T can be
// initialized from.
if (const AtomicType *AT = Type->getAs<AtomicType>())
Type = AT->getValueType();
// Core issue 1454: For a literal constant expression of array or class type,
// each subobject of its value shall have been initialized by a constant
// expression.
if (Value.isArray()) {
QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType();
for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) {
if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
Value.getArrayInitializedElt(I), Kind,
SubobjectLoc, CheckedTemps))
return false;
}
if (!Value.hasArrayFiller())
return true;
return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy,
Value.getArrayFiller(), Kind, SubobjectLoc,
CheckedTemps);
}
if (Value.isUnion() && Value.getUnionField()) {
return CheckEvaluationResult(
CERK, Info, DiagLoc, Value.getUnionField()->getType(),
Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(),
CheckedTemps);
}
if (Value.isStruct()) {
RecordDecl *RD = Type->castAs<RecordType>()->getDecl();
if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) {
unsigned BaseIndex = 0;
for (const CXXBaseSpecifier &BS : CD->bases()) {
if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(),
Value.getStructBase(BaseIndex), Kind,
BS.getBeginLoc(), CheckedTemps))
return false;
++BaseIndex;
}
}
for (const auto *I : RD->fields()) {
if (I->isUnnamedBitfield())
continue;
if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(),
Value.getStructField(I->getFieldIndex()),
Kind, I->getLocation(), CheckedTemps))
return false;
}
}
if (Value.isLValue() &&
CERK == CheckEvaluationResultKind::ConstantExpression) {
LValue LVal;
LVal.setFrom(Info.Ctx, Value);
return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind,
CheckedTemps);
}
if (Value.isMemberPointer() &&
CERK == CheckEvaluationResultKind::ConstantExpression)
return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind);
// Everything else is fine.
return true;
}
/// Check that this core constant expression value is a valid value for a
/// constant expression. If not, report an appropriate diagnostic. Does not
/// check that the expression is of literal type.
static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc,
QualType Type, const APValue &Value,
ConstantExprKind Kind) {
// Nothing to check for a constant expression of type 'cv void'.
if (Type->isVoidType())
return true;
CheckedTemporaries CheckedTemps;
return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression,
Info, DiagLoc, Type, Value, Kind,
SourceLocation(), CheckedTemps);
}
/// Check that this evaluated value is fully-initialized and can be loaded by
/// an lvalue-to-rvalue conversion.
static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc,
QualType Type, const APValue &Value) {
CheckedTemporaries CheckedTemps;
return CheckEvaluationResult(
CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value,
ConstantExprKind::Normal, SourceLocation(), CheckedTemps);
}
/// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless
/// "the allocated storage is deallocated within the evaluation".
static bool CheckMemoryLeaks(EvalInfo &Info) {
if (!Info.HeapAllocs.empty()) {
// We can still fold to a constant despite a compile-time memory leak,
// so long as the heap allocation isn't referenced in the result (we check
// that in CheckConstantExpression).
Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr,
diag::note_constexpr_memory_leak)
<< unsigned(Info.HeapAllocs.size() - 1);
}
return true;
}
static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) {
// A null base expression indicates a null pointer. These are always
// evaluatable, and they are false unless the offset is zero.
if (!Value.getLValueBase()) {
Result = !Value.getLValueOffset().isZero();
return true;
}
// We have a non-null base. These are generally known to be true, but if it's
// a weak declaration it can be null at runtime.
Result = true;
const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>();
return !Decl || !Decl->isWeak();
}
static bool HandleConversionToBool(const APValue &Val, bool &Result) {
switch (Val.getKind()) {
case APValue::None:
case APValue::Indeterminate:
return false;
case APValue::Int:
Result = Val.getInt().getBoolValue();
return true;
case APValue::FixedPoint:
Result = Val.getFixedPoint().getBoolValue();
return true;
case APValue::Float:
Result = !Val.getFloat().isZero();
return true;
case APValue::ComplexInt:
Result = Val.getComplexIntReal().getBoolValue() ||
Val.getComplexIntImag().getBoolValue();
return true;
case APValue::ComplexFloat:
Result = !Val.getComplexFloatReal().isZero() ||
!Val.getComplexFloatImag().isZero();
return true;
case APValue::LValue:
return EvalPointerValueAsBool(Val, Result);
case APValue::MemberPointer:
Result = Val.getMemberPointerDecl();
return true;
case APValue::Vector:
case APValue::Array:
case APValue::Struct:
case APValue::Union:
case APValue::AddrLabelDiff:
return false;
}
llvm_unreachable("unknown APValue kind");
}
static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition");
APValue Val;
if (!Evaluate(Val, Info, E))
return false;
return HandleConversionToBool(Val, Result);
}
template<typename T>
static bool HandleOverflow(EvalInfo &Info, const Expr *E,
const T &SrcValue, QualType DestType) {
Info.CCEDiag(E, diag::note_constexpr_overflow)
<< SrcValue << DestType;
return Info.noteUndefinedBehavior();
}
static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E,
QualType SrcType, const APFloat &Value,
QualType DestType, APSInt &Result) {
unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
// Determine whether we are converting to unsigned or signed.
bool DestSigned = DestType->isSignedIntegerOrEnumerationType();
Result = APSInt(DestWidth, !DestSigned);
bool ignored;
if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored)
& APFloat::opInvalidOp)
return HandleOverflow(Info, E, Value, DestType);
return true;
}
/// Get rounding mode used for evaluation of the specified expression.
/// \param[out] DynamicRM Is set to true is the requested rounding mode is
/// dynamic.
/// If rounding mode is unknown at compile time, still try to evaluate the
/// expression. If the result is exact, it does not depend on rounding mode.
/// So return "tonearest" mode instead of "dynamic".
static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E,
bool &DynamicRM) {
llvm::RoundingMode RM =
E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode();
DynamicRM = (RM == llvm::RoundingMode::Dynamic);
if (DynamicRM)
RM = llvm::RoundingMode::NearestTiesToEven;
return RM;
}
/// Check if the given evaluation result is allowed for constant evaluation.
static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E,
APFloat::opStatus St) {
// In a constant context, assume that any dynamic rounding mode or FP
// exception state matches the default floating-point environment.
if (Info.InConstantContext)
return true;
FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts());
if ((St & APFloat::opInexact) &&
FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) {
// Inexact result means that it depends on rounding mode. If the requested
// mode is dynamic, the evaluation cannot be made in compile time.
Info.FFDiag(E, diag::note_constexpr_dynamic_rounding);
return false;
}
if ((St != APFloat::opOK) &&
(FPO.getRoundingMode() == llvm::RoundingMode::Dynamic ||
FPO.getFPExceptionMode() != LangOptions::FPE_Ignore ||
FPO.getAllowFEnvAccess())) {
Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
return false;
}
if ((St & APFloat::opStatus::opInvalidOp) &&
FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) {
// There is no usefully definable result.
Info.FFDiag(E);
return false;
}
// FIXME: if:
// - evaluation triggered other FP exception, and
// - exception mode is not "ignore", and
// - the expression being evaluated is not a part of global variable
// initializer,
// the evaluation probably need to be rejected.
return true;
}
static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E,
QualType SrcType, QualType DestType,
APFloat &Result) {
assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E));
bool DynamicRM;
llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
APFloat::opStatus St;
APFloat Value = Result;
bool ignored;
St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored);
return checkFloatingPointResult(Info, E, St);
}
static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
QualType DestType, QualType SrcType,
const APSInt &Value) {
unsigned DestWidth = Info.Ctx.getIntWidth(DestType);
// Figure out if this is a truncate, extend or noop cast.
// If the input is signed, do a sign extend, noop, or truncate.
APSInt Result = Value.extOrTrunc(DestWidth);
Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType());
if (DestType->isBooleanType())
Result = Value.getBoolValue();
return Result;
}
static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
const FPOptions FPO,
QualType SrcType, const APSInt &Value,
QualType DestType, APFloat &Result) {
Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
APFloat::rmNearestTiesToEven);
if (!Info.InConstantContext && St != llvm::APFloatBase::opOK &&
FPO.isFPConstrained()) {
Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
return false;
}
return true;
}
static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
APValue &Value, const FieldDecl *FD) {
assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
if (!Value.isInt()) {
// Trying to store a pointer-cast-to-integer into a bitfield.
// FIXME: In this case, we should provide the diagnostic for casting
// a pointer to an integer.
assert(Value.isLValue() && "integral value neither int nor lvalue?");
Info.FFDiag(E);
return false;
}
APSInt &Int = Value.getInt();
unsigned OldBitWidth = Int.getBitWidth();
unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx);
if (NewBitWidth < OldBitWidth)
Int = Int.trunc(NewBitWidth).extend(OldBitWidth);
return true;
}
static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E,
llvm::APInt &Res) {
APValue SVal;
if (!Evaluate(SVal, Info, E))
return false;
if (SVal.isInt()) {
Res = SVal.getInt();
return true;
}
if (SVal.isFloat()) {
Res = SVal.getFloat().bitcastToAPInt();
return true;
}
if (SVal.isVector()) {
QualType VecTy = E->getType();
unsigned VecSize = Info.Ctx.getTypeSize(VecTy);
QualType EltTy = VecTy->castAs<VectorType>()->getElementType();
unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
Res = llvm::APInt::getNullValue(VecSize);
for (unsigned i = 0; i < SVal.getVectorLength(); i++) {
APValue &Elt = SVal.getVectorElt(i);
llvm::APInt EltAsInt;
if (Elt.isInt()) {
EltAsInt = Elt.getInt();
} else if (Elt.isFloat()) {
EltAsInt = Elt.getFloat().bitcastToAPInt();
} else {
// Don't try to handle vectors of anything other than int or float
// (not sure if it's possible to hit this case).
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
unsigned BaseEltSize = EltAsInt.getBitWidth();
if (BigEndian)
Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize);
else
Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize);
}
return true;
}
// Give up if the input isn't an int, float, or vector. For example, we
// reject "(v4i16)(intptr_t)&a".
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
/// Perform the given integer operation, which is known to need at most BitWidth
/// bits, and check for overflow in the original type (if that type was not an
/// unsigned type).
template<typename Operation>
static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E,
const APSInt &LHS, const APSInt &RHS,
unsigned BitWidth, Operation Op,
APSInt &Result) {
if (LHS.isUnsigned()) {
Result = Op(LHS, RHS);
return true;
}
APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false);
Result = Value.trunc(LHS.getBitWidth());
if (Result.extend(BitWidth) != Value) {
if (Info.checkingForUndefinedBehavior())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_integer_constant_overflow)
<< Result.toString(10) << E->getType();
return HandleOverflow(Info, E, Value, E->getType());
}
return true;
}
/// Perform the given binary integer operation.
static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS,
BinaryOperatorKind Opcode, APSInt RHS,
APSInt &Result) {
switch (Opcode) {
default:
Info.FFDiag(E);
return false;
case BO_Mul:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2,
std::multiplies<APSInt>(), Result);
case BO_Add:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
std::plus<APSInt>(), Result);
case BO_Sub:
return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1,
std::minus<APSInt>(), Result);
case BO_And: Result = LHS & RHS; return true;
case BO_Xor: Result = LHS ^ RHS; return true;
case BO_Or: Result = LHS | RHS; return true;
case BO_Div:
case BO_Rem:
if (RHS == 0) {
Info.FFDiag(E, diag::note_expr_divide_by_zero);
return false;
}
Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS);
// Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports
// this operation and gives the two's complement result.
if (RHS.isNegative() && RHS.isAllOnesValue() &&
LHS.isSigned() && LHS.isMinSignedValue())
return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1),
E->getType());
return true;
case BO_Shl: {
if (Info.getLangOpts().OpenCL)
// OpenCL 6.3j: shift values are effectively % word size of LHS.
RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
static_cast<uint64_t>(LHS.getBitWidth() - 1)),
RHS.isUnsigned());
else if (RHS.isSigned() && RHS.isNegative()) {
// During constant-folding, a negative shift is an opposite shift. Such
// a shift is not a constant expression.
Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
RHS = -RHS;
goto shift_right;
}
shift_left:
// C++11 [expr.shift]p1: Shift width must be less than the bit width of
// the shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
if (SA != RHS) {
Info.CCEDiag(E, diag::note_constexpr_large_shift)
<< RHS << E->getType() << LHS.getBitWidth();
} else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) {
// C++11 [expr.shift]p2: A signed left shift must have a non-negative
// operand, and must not overflow the corresponding unsigned type.
// C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to
// E1 x 2^E2 module 2^N.
if (LHS.isNegative())
Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS;
else if (LHS.countLeadingZeros() < SA)
Info.CCEDiag(E, diag::note_constexpr_lshift_discards);
}
Result = LHS << SA;
return true;
}
case BO_Shr: {
if (Info.getLangOpts().OpenCL)
// OpenCL 6.3j: shift values are effectively % word size of LHS.
RHS &= APSInt(llvm::APInt(RHS.getBitWidth(),
static_cast<uint64_t>(LHS.getBitWidth() - 1)),
RHS.isUnsigned());
else if (RHS.isSigned() && RHS.isNegative()) {
// During constant-folding, a negative shift is an opposite shift. Such a
// shift is not a constant expression.
Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS;
RHS = -RHS;
goto shift_left;
}
shift_right:
// C++11 [expr.shift]p1: Shift width must be less than the bit width of the
// shifted type.
unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
if (SA != RHS)
Info.CCEDiag(E, diag::note_constexpr_large_shift)
<< RHS << E->getType() << LHS.getBitWidth();
Result = LHS >> SA;
return true;
}
case BO_LT: Result = LHS < RHS; return true;
case BO_GT: Result = LHS > RHS; return true;
case BO_LE: Result = LHS <= RHS; return true;
case BO_GE: Result = LHS >= RHS; return true;
case BO_EQ: Result = LHS == RHS; return true;
case BO_NE: Result = LHS != RHS; return true;
case BO_Cmp:
llvm_unreachable("BO_Cmp should be handled elsewhere");
}
}
/// Perform the given binary floating-point operation, in-place, on LHS.
static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E,
APFloat &LHS, BinaryOperatorKind Opcode,
const APFloat &RHS) {
bool DynamicRM;
llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM);
APFloat::opStatus St;
switch (Opcode) {
default:
Info.FFDiag(E);
return false;
case BO_Mul:
St = LHS.multiply(RHS, RM);
break;
case BO_Add:
St = LHS.add(RHS, RM);
break;
case BO_Sub:
St = LHS.subtract(RHS, RM);
break;
case BO_Div:
// [expr.mul]p4:
// If the second operand of / or % is zero the behavior is undefined.
if (RHS.isZero())
Info.CCEDiag(E, diag::note_expr_divide_by_zero);
St = LHS.divide(RHS, RM);
break;
}
// [expr.pre]p4:
// If during the evaluation of an expression, the result is not
// mathematically defined [...], the behavior is undefined.
// FIXME: C++ rules require us to not conform to IEEE 754 here.
if (LHS.isNaN()) {
Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN();
return Info.noteUndefinedBehavior();
}
return checkFloatingPointResult(Info, E, St);
}
static bool handleLogicalOpForVector(const APInt &LHSValue,
BinaryOperatorKind Opcode,
const APInt &RHSValue, APInt &Result) {
bool LHS = (LHSValue != 0);
bool RHS = (RHSValue != 0);
if (Opcode == BO_LAnd)
Result = LHS && RHS;
else
Result = LHS || RHS;
return true;
}
static bool handleLogicalOpForVector(const APFloat &LHSValue,
BinaryOperatorKind Opcode,
const APFloat &RHSValue, APInt &Result) {
bool LHS = !LHSValue.isZero();
bool RHS = !RHSValue.isZero();
if (Opcode == BO_LAnd)
Result = LHS && RHS;
else
Result = LHS || RHS;
return true;
}
static bool handleLogicalOpForVector(const APValue &LHSValue,
BinaryOperatorKind Opcode,
const APValue &RHSValue, APInt &Result) {
// The result is always an int type, however operands match the first.
if (LHSValue.getKind() == APValue::Int)
return handleLogicalOpForVector(LHSValue.getInt(), Opcode,
RHSValue.getInt(), Result);
assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
return handleLogicalOpForVector(LHSValue.getFloat(), Opcode,
RHSValue.getFloat(), Result);
}
template <typename APTy>
static bool
handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode,
const APTy &RHSValue, APInt &Result) {
switch (Opcode) {
default:
llvm_unreachable("unsupported binary operator");
case BO_EQ:
Result = (LHSValue == RHSValue);
break;
case BO_NE:
Result = (LHSValue != RHSValue);
break;
case BO_LT:
Result = (LHSValue < RHSValue);
break;
case BO_GT:
Result = (LHSValue > RHSValue);
break;
case BO_LE:
Result = (LHSValue <= RHSValue);
break;
case BO_GE:
Result = (LHSValue >= RHSValue);
break;
}
return true;
}
static bool handleCompareOpForVector(const APValue &LHSValue,
BinaryOperatorKind Opcode,
const APValue &RHSValue, APInt &Result) {
// The result is always an int type, however operands match the first.
if (LHSValue.getKind() == APValue::Int)
return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode,
RHSValue.getInt(), Result);
assert(LHSValue.getKind() == APValue::Float && "Should be no other options");
return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode,
RHSValue.getFloat(), Result);
}
// Perform binary operations for vector types, in place on the LHS.
static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E,
BinaryOperatorKind Opcode,
APValue &LHSValue,
const APValue &RHSValue) {
assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI &&
"Operation not supported on vector types");
const auto *VT = E->getType()->castAs<VectorType>();
unsigned NumElements = VT->getNumElements();
QualType EltTy = VT->getElementType();
// In the cases (typically C as I've observed) where we aren't evaluating
// constexpr but are checking for cases where the LHS isn't yet evaluatable,
// just give up.
if (!LHSValue.isVector()) {
assert(LHSValue.isLValue() &&
"A vector result that isn't a vector OR uncalculated LValue");
Info.FFDiag(E);
return false;
}
assert(LHSValue.getVectorLength() == NumElements &&
RHSValue.getVectorLength() == NumElements && "Different vector sizes");
SmallVector<APValue, 4> ResultElements;
for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) {
APValue LHSElt = LHSValue.getVectorElt(EltNum);
APValue RHSElt = RHSValue.getVectorElt(EltNum);
if (EltTy->isIntegerType()) {
APSInt EltResult{Info.Ctx.getIntWidth(EltTy),
EltTy->isUnsignedIntegerType()};
bool Success = true;
if (BinaryOperator::isLogicalOp(Opcode))
Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult);
else if (BinaryOperator::isComparisonOp(Opcode))
Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult);
else
Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode,
RHSElt.getInt(), EltResult);
if (!Success) {
Info.FFDiag(E);
return false;
}
ResultElements.emplace_back(EltResult);
} else if (EltTy->isFloatingType()) {
assert(LHSElt.getKind() == APValue::Float &&
RHSElt.getKind() == APValue::Float &&
"Mismatched LHS/RHS/Result Type");
APFloat LHSFloat = LHSElt.getFloat();
if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode,
RHSElt.getFloat())) {
Info.FFDiag(E);
return false;
}
ResultElements.emplace_back(LHSFloat);
}
}
LHSValue = APValue(ResultElements.data(), ResultElements.size());
return true;
}
/// Cast an lvalue referring to a base subobject to a derived class, by
/// truncating the lvalue's path to the given length.
static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result,
const RecordDecl *TruncatedType,
unsigned TruncatedElements) {
SubobjectDesignator &D = Result.Designator;
// Check we actually point to a derived class object.
if (TruncatedElements == D.Entries.size())
return true;
assert(TruncatedElements >= D.MostDerivedPathLength &&
"not casting to a derived class");
if (!Result.checkSubobject(Info, E, CSK_Derived))
return false;
// Truncate the path to the subobject, and remove any derived-to-base offsets.
const RecordDecl *RD = TruncatedType;
for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) {
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]);
if (isVirtualBaseClass(D.Entries[I]))
Result.Offset -= Layout.getVBaseClassOffset(Base);
else
Result.Offset -= Layout.getBaseClassOffset(Base);
RD = Base;
}
D.Entries.resize(TruncatedElements);
return true;
}
static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj,
const CXXRecordDecl *Derived,
const CXXRecordDecl *Base,
const ASTRecordLayout *RL = nullptr) {
if (!RL) {
if (Derived->isInvalidDecl()) return false;
RL = &Info.Ctx.getASTRecordLayout(Derived);
}
Obj.getLValueOffset() += RL->getBaseClassOffset(Base);
Obj.addDecl(Info, E, Base, /*Virtual*/ false);
return true;
}
static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj,
const CXXRecordDecl *DerivedDecl,
const CXXBaseSpecifier *Base) {
const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl();
if (!Base->isVirtual())
return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl);
SubobjectDesignator &D = Obj.Designator;
if (D.Invalid)
return false;
// Extract most-derived object and corresponding type.
DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl();
if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength))
return false;
// Find the virtual base class.
if (DerivedDecl->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl);
Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl);
Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true);
return true;
}
static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E,
QualType Type, LValue &Result) {
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end();
PathI != PathE; ++PathI) {
if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(),
*PathI))
return false;
Type = (*PathI)->getType();
}
return true;
}
/// Cast an lvalue referring to a derived class to a known base subobject.
static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result,
const CXXRecordDecl *DerivedRD,
const CXXRecordDecl *BaseRD) {
CXXBasePaths Paths(/*FindAmbiguities=*/false,
/*RecordPaths=*/true, /*DetectVirtual=*/false);
if (!DerivedRD->isDerivedFrom(BaseRD, Paths))
llvm_unreachable("Class must be derived from the passed in base class!");
for (CXXBasePathElement &Elem : Paths.front())
if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base))
return false;
return true;
}
/// Update LVal to refer to the given field, which must be a member of the type
/// currently described by LVal.
static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal,
const FieldDecl *FD,
const ASTRecordLayout *RL = nullptr) {
if (!RL) {
if (FD->getParent()->isInvalidDecl()) return false;
RL = &Info.Ctx.getASTRecordLayout(FD->getParent());
}
unsigned I = FD->getFieldIndex();
LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I)));
LVal.addDecl(Info, E, FD);
return true;
}
/// Update LVal to refer to the given indirect field.
static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E,
LValue &LVal,
const IndirectFieldDecl *IFD) {
for (const auto *C : IFD->chain())
if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C)))
return false;
return true;
}
/// Get the size of the given type in char units.
static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc,
QualType Type, CharUnits &Size) {
// sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
// extension.
if (Type->isVoidType() || Type->isFunctionType()) {
Size = CharUnits::One();
return true;
}
if (Type->isDependentType()) {
Info.FFDiag(Loc);
return false;
}
if (!Type->isConstantSizeType()) {
// sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
// FIXME: Better diagnostic.
Info.FFDiag(Loc);
return false;
}
Size = Info.Ctx.getTypeSizeInChars(Type);
return true;
}
/// Update a pointer value to model pointer arithmetic.
/// \param Info - Information about the ongoing evaluation.
/// \param E - The expression being evaluated, for diagnostic purposes.
/// \param LVal - The pointer value to be updated.
/// \param EltTy - The pointee type represented by LVal.
/// \param Adjustment - The adjustment, in objects of type EltTy, to add.
static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
APSInt Adjustment) {
CharUnits SizeOfPointee;
if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee))
return false;
LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee);
return true;
}
static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
int64_t Adjustment) {
return HandleLValueArrayAdjustment(Info, E, LVal, EltTy,
APSInt::get(Adjustment));
}
/// Update an lvalue to refer to a component of a complex number.
/// \param Info - Information about the ongoing evaluation.
/// \param LVal - The lvalue to be updated.
/// \param EltTy - The complex number's component type.
/// \param Imag - False for the real component, true for the imaginary.
static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
LValue &LVal, QualType EltTy,
bool Imag) {
if (Imag) {
CharUnits SizeOfComponent;
if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent))
return false;
LVal.Offset += SizeOfComponent;
}
LVal.addComplex(Info, E, EltTy, Imag);
return true;
}
/// Try to evaluate the initializer for a variable declaration.
///
/// \param Info Information about the ongoing evaluation.
/// \param E An expression to be used when printing diagnostics.
/// \param VD The variable whose initializer should be obtained.
/// \param Version The version of the variable within the frame.
/// \param Frame The frame in which the variable was created. Must be null
/// if this variable is not local to the evaluation.
/// \param Result Filled in with a pointer to the value of the variable.
static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E,
const VarDecl *VD, CallStackFrame *Frame,
unsigned Version, APValue *&Result) {
APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version);
// If this is a local variable, dig out its value.
if (Frame) {
Result = Frame->getTemporary(VD, Version);
if (Result)
return true;
if (!isa<ParmVarDecl>(VD)) {
// Assume variables referenced within a lambda's call operator that were
// not declared within the call operator are captures and during checking
// of a potential constant expression, assume they are unknown constant
// expressions.
assert(isLambdaCallOperator(Frame->Callee) &&
(VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) &&
"missing value for local variable");
if (Info.checkingPotentialConstantExpression())
return false;
// FIXME: This diagnostic is bogus; we do support captures. Is this code
// still reachable at all?
Info.FFDiag(E->getBeginLoc(),
diag::note_unimplemented_constexpr_lambda_feature_ast)
<< "captures not currently allowed";
return false;
}
}
// If we're currently evaluating the initializer of this declaration, use that
// in-flight value.
if (Info.EvaluatingDecl == Base) {
Result = Info.EvaluatingDeclValue;
return true;
}
if (isa<ParmVarDecl>(VD)) {
// Assume parameters of a potential constant expression are usable in
// constant expressions.
if (!Info.checkingPotentialConstantExpression() ||
!Info.CurrentCall->Callee ||
!Info.CurrentCall->Callee->Equals(VD->getDeclContext())) {
if (Info.getLangOpts().CPlusPlus11) {
Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown)
<< VD;
NoteLValueLocation(Info, Base);
} else {
Info.FFDiag(E);
}
}
return false;
}
// Dig out the initializer, and use the declaration which it's attached to.
// FIXME: We should eventually check whether the variable has a reachable
// initializing declaration.
const Expr *Init = VD->getAnyInitializer(VD);
if (!Init) {
// Don't diagnose during potential constant expression checking; an
// initializer might be added later.
if (!Info.checkingPotentialConstantExpression()) {
Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1)
<< VD;
NoteLValueLocation(Info, Base);
}
return false;
}
if (Init->isValueDependent()) {
// The DeclRefExpr is not value-dependent, but the variable it refers to
// has a value-dependent initializer. This should only happen in
// constant-folding cases, where the variable is not actually of a suitable
// type for use in a constant expression (otherwise the DeclRefExpr would
// have been value-dependent too), so diagnose that.
assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx));
if (!Info.checkingPotentialConstantExpression()) {
Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
? diag::note_constexpr_ltor_non_constexpr
: diag::note_constexpr_ltor_non_integral, 1)
<< VD << VD->getType();
NoteLValueLocation(Info, Base);
}
return false;
}
// Check that we can fold the initializer. In C++, we will have already done
// this in the cases where it matters for conformance.
if (!VD->evaluateValue()) {
Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
NoteLValueLocation(Info, Base);
return false;
}
// Check that the variable is actually usable in constant expressions. For a
// const integral variable or a reference, we might have a non-constant
// initializer that we can nonetheless evaluate the initializer for. Such
// variables are not usable in constant expressions. In C++98, the
// initializer also syntactically needs to be an ICE.
//
// FIXME: We don't diagnose cases that aren't potentially usable in constant
// expressions here; doing so would regress diagnostics for things like
// reading from a volatile constexpr variable.
if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() &&
VD->mightBeUsableInConstantExpressions(Info.Ctx)) ||
((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) &&
!Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) {
Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD;
NoteLValueLocation(Info, Base);
}
// Never use the initializer of a weak variable, not even for constant
// folding. We can't be sure that this is the definition that will be used.
if (VD->isWeak()) {
Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD;
NoteLValueLocation(Info, Base);
return false;
}
Result = VD->getEvaluatedValue();
return true;
}
/// Get the base index of the given base class within an APValue representing
/// the given derived class.
static unsigned getBaseIndex(const CXXRecordDecl *Derived,
const CXXRecordDecl *Base) {
Base = Base->getCanonicalDecl();
unsigned Index = 0;
for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(),
E = Derived->bases_end(); I != E; ++I, ++Index) {
if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base)
return Index;
}
llvm_unreachable("base class missing from derived class's bases list");
}
/// Extract the value of a character from a string literal.
static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit,
uint64_t Index) {
assert(!isa<SourceLocExpr>(Lit) &&
"SourceLocExpr should have already been converted to a StringLiteral");
// FIXME: Support MakeStringConstant
if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) {
std::string Str;
Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str);
assert(Index <= Str.size() && "Index too large");
return APSInt::getUnsigned(Str.c_str()[Index]);
}
if (auto PE = dyn_cast<PredefinedExpr>(Lit))
Lit = PE->getFunctionName();
const StringLiteral *S = cast<StringLiteral>(Lit);
const ConstantArrayType *CAT =
Info.Ctx.getAsConstantArrayType(S->getType());
assert(CAT && "string literal isn't an array");
QualType CharType = CAT->getElementType();
assert(CharType->isIntegerType() && "unexpected character type");
APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
CharType->isUnsignedIntegerType());
if (Index < S->getLength())
Value = S->getCodeUnit(Index);
return Value;
}
// Expand a string literal into an array of characters.
//
// FIXME: This is inefficient; we should probably introduce something similar
// to the LLVM ConstantDataArray to make this cheaper.
static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
APValue &Result,
QualType AllocType = QualType()) {
const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
AllocType.isNull() ? S->getType() : AllocType);
assert(CAT && "string literal isn't an array");
QualType CharType = CAT->getElementType();
assert(CharType->isIntegerType() && "unexpected character type");
unsigned Elts = CAT->getSize().getZExtValue();
Result = APValue(APValue::UninitArray(),
std::min(S->getLength(), Elts), Elts);
APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(),
CharType->isUnsignedIntegerType());
if (Result.hasArrayFiller())
Result.getArrayFiller() = APValue(Value);
for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) {
Value = S->getCodeUnit(I);
Result.getArrayInitializedElt(I) = APValue(Value);
}
}
// Expand an array so that it has more than Index filled elements.
static void expandArray(APValue &Array, unsigned Index) {
unsigned Size = Array.getArraySize();
assert(Index < Size);
// Always at least double the number of elements for which we store a value.
unsigned OldElts = Array.getArrayInitializedElts();
unsigned NewElts = std::max(Index+1, OldElts * 2);
NewElts = std::min(Size, std::max(NewElts, 8u));
// Copy the data across.
APValue NewValue(APValue::UninitArray(), NewElts, Size);
for (unsigned I = 0; I != OldElts; ++I)
NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I));
for (unsigned I = OldElts; I != NewElts; ++I)
NewValue.getArrayInitializedElt(I) = Array.getArrayFiller();
if (NewValue.hasArrayFiller())
NewValue.getArrayFiller() = Array.getArrayFiller();
Array.swap(NewValue);
}
/// Determine whether a type would actually be read by an lvalue-to-rvalue
/// conversion. If it's of class type, we may assume that the copy operation
/// is trivial. Note that this is never true for a union type with fields
/// (because the copy always "reads" the active member) and always true for
/// a non-class type.
static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD);
static bool isReadByLvalueToRvalueConversion(QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
return !RD || isReadByLvalueToRvalueConversion(RD);
}
static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) {
// FIXME: A trivial copy of a union copies the object representation, even if
// the union is empty.
if (RD->isUnion())
return !RD->field_empty();
if (RD->isEmpty())
return false;
for (auto *Field : RD->fields())
if (!Field->isUnnamedBitfield() &&
isReadByLvalueToRvalueConversion(Field->getType()))
return true;
for (auto &BaseSpec : RD->bases())
if (isReadByLvalueToRvalueConversion(BaseSpec.getType()))
return true;
return false;
}
/// Diagnose an attempt to read from any unreadable field within the specified
/// type, which might be a class type.
static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK,
QualType T) {
CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD)
return false;
if (!RD->hasMutableFields())
return false;
for (auto *Field : RD->fields()) {
// If we're actually going to read this field in some way, then it can't
// be mutable. If we're in a union, then assigning to a mutable field
// (even an empty one) can change the active member, so that's not OK.
// FIXME: Add core issue number for the union case.
if (Field->isMutable() &&
(RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) {
Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return true;
}
if (diagnoseMutableFields(Info, E, AK, Field->getType()))
return true;
}
for (auto &BaseSpec : RD->bases())
if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType()))
return true;
// All mutable fields were empty, and thus not actually read.
return false;
}
static bool lifetimeStartedInEvaluation(EvalInfo &Info,
APValue::LValueBase Base,
bool MutableSubobject = false) {
// A temporary or transient heap allocation we created.
if (Base.getCallIndex() || Base.is<DynamicAllocLValue>())
return true;
switch (Info.IsEvaluatingDecl) {
case EvalInfo::EvaluatingDeclKind::None:
return false;
case EvalInfo::EvaluatingDeclKind::Ctor:
// The variable whose initializer we're evaluating.
if (Info.EvaluatingDecl == Base)
return true;
// A temporary lifetime-extended by the variable whose initializer we're
// evaluating.
if (auto *BaseE = Base.dyn_cast<const Expr *>())
if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE))
return Info.EvaluatingDecl == BaseMTE->getExtendingDecl();
return false;
case EvalInfo::EvaluatingDeclKind::Dtor:
// C++2a [expr.const]p6:
// [during constant destruction] the lifetime of a and its non-mutable
// subobjects (but not its mutable subobjects) [are] considered to start
// within e.
if (MutableSubobject || Base != Info.EvaluatingDecl)
return false;
// FIXME: We can meaningfully extend this to cover non-const objects, but
// we will need special handling: we should be able to access only
// subobjects of such objects that are themselves declared const.
QualType T = getType(Base);
return T.isConstQualified() || T->isReferenceType();
}
llvm_unreachable("unknown evaluating decl kind");
}
namespace {
/// A handle to a complete object (an object that is not a subobject of
/// another object).
struct CompleteObject {
/// The identity of the object.
APValue::LValueBase Base;
/// The value of the complete object.
APValue *Value;
/// The type of the complete object.
QualType Type;
CompleteObject() : Value(nullptr) {}
CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type)
: Base(Base), Value(Value), Type(Type) {}
bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const {
// If this isn't a "real" access (eg, if it's just accessing the type
// info), allow it. We assume the type doesn't change dynamically for
// subobjects of constexpr objects (even though we'd hit UB here if it
// did). FIXME: Is this right?
if (!isAnyAccess(AK))
return true;
// In C++14 onwards, it is permitted to read a mutable member whose
// lifetime began within the evaluation.
// FIXME: Should we also allow this in C++11?
if (!Info.getLangOpts().CPlusPlus14)
return false;
return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true);
}
explicit operator bool() const { return !Type.isNull(); }
};
} // end anonymous namespace
static QualType getSubobjectType(QualType ObjType, QualType SubobjType,
bool IsMutable = false) {
// C++ [basic.type.qualifier]p1:
// - A const object is an object of type const T or a non-mutable subobject
// of a const object.
if (ObjType.isConstQualified() && !IsMutable)
SubobjType.addConst();
// - A volatile object is an object of type const T or a subobject of a
// volatile object.
if (ObjType.isVolatileQualified())
SubobjType.addVolatile();
return SubobjType;
}
/// Find the designated sub-object of an rvalue.
template<typename SubobjectHandler>
typename SubobjectHandler::result_type
findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj,
const SubobjectDesignator &Sub, SubobjectHandler &handler) {
if (Sub.Invalid)
// A diagnostic will have already been produced.
return handler.failed();
if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, Sub.isOnePastTheEnd()
? diag::note_constexpr_access_past_end
: diag::note_constexpr_access_unsized_array)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
APValue *O = Obj.Value;
QualType ObjType = Obj.Type;
const FieldDecl *LastField = nullptr;
const FieldDecl *VolatileField = nullptr;
// Walk the designator's path to find the subobject.
for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) {
// Reading an indeterminate value is undefined, but assigning over one is OK.
if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) ||
(O->isIndeterminate() &&
!isValidIndeterminateAccess(handler.AccessKind))) {
if (!Info.checkingPotentialConstantExpression())
Info.FFDiag(E, diag::note_constexpr_access_uninit)
<< handler.AccessKind << O->isIndeterminate();
return handler.failed();
}
// C++ [class.ctor]p5, C++ [class.dtor]p5:
// const and volatile semantics are not applied on an object under
// {con,de}struction.
if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) &&
ObjType->isRecordType() &&
Info.isEvaluatingCtorDtor(
Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(),
Sub.Entries.begin() + I)) !=
ConstructionPhase::None) {
ObjType = Info.Ctx.getCanonicalType(ObjType);
ObjType.removeLocalConst();
ObjType.removeLocalVolatile();
}
// If this is our last pass, check that the final object type is OK.
if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) {
// Accesses to volatile objects are prohibited.
if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) {
if (Info.getLangOpts().CPlusPlus) {
int DiagKind;
SourceLocation Loc;
const NamedDecl *Decl = nullptr;
if (VolatileField) {
DiagKind = 2;
Loc = VolatileField->getLocation();
Decl = VolatileField;
} else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) {
DiagKind = 1;
Loc = VD->getLocation();
Decl = VD;
} else {
DiagKind = 0;
if (auto *E = Obj.Base.dyn_cast<const Expr *>())
Loc = E->getExprLoc();
}
Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1)
<< handler.AccessKind << DiagKind << Decl;
Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind;
} else {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
}
return handler.failed();
}
// If we are reading an object of class type, there may still be more
// things we need to check: if there are any mutable subobjects, we
// cannot perform this read. (This only happens when performing a trivial
// copy or assignment.)
if (ObjType->isRecordType() &&
!Obj.mayAccessMutableMembers(Info, handler.AccessKind) &&
diagnoseMutableFields(Info, E, handler.AccessKind, ObjType))
return handler.failed();
}
if (I == N) {
if (!handler.found(*O, ObjType))
return false;
// If we modified a bit-field, truncate it to the right width.
if (isModification(handler.AccessKind) &&
LastField && LastField->isBitField() &&
!truncateBitfieldValue(Info, E, *O, LastField))
return false;
return true;
}
LastField = nullptr;
if (ObjType->isArrayType()) {
// Next subobject is an array element.
const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType);
assert(CAT && "vla in literal type?");
uint64_t Index = Sub.Entries[I].getAsArrayIndex();
if (CAT->getSize().ule(Index)) {
// Note, it should not be possible to form a pointer with a valid
// designator which points more than one past the end of the array.
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_access_past_end)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
ObjType = CAT->getElementType();
if (O->getArrayInitializedElts() > Index)
O = &O->getArrayInitializedElt(Index);
else if (!isRead(handler.AccessKind)) {
expandArray(*O, Index);
O = &O->getArrayInitializedElt(Index);
} else
O = &O->getArrayFiller();
} else if (ObjType->isAnyComplexType()) {
// Next subobject is a complex number.
uint64_t Index = Sub.Entries[I].getAsArrayIndex();
if (Index > 1) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_access_past_end)
<< handler.AccessKind;
else
Info.FFDiag(E);
return handler.failed();
}
ObjType = getSubobjectType(
ObjType, ObjType->castAs<ComplexType>()->getElementType());
assert(I == N - 1 && "extracting subobject of scalar?");
if (O->isComplexInt()) {
return handler.found(Index ? O->getComplexIntImag()
: O->getComplexIntReal(), ObjType);
} else {
assert(O->isComplexFloat());
return handler.found(Index ? O->getComplexFloatImag()
: O->getComplexFloatReal(), ObjType);
}
} else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) {
if (Field->isMutable() &&
!Obj.mayAccessMutableMembers(Info, handler.AccessKind)) {
Info.FFDiag(E, diag::note_constexpr_access_mutable, 1)
<< handler.AccessKind << Field;
Info.Note(Field->getLocation(), diag::note_declared_at);
return handler.failed();
}
// Next subobject is a class, struct or union field.
RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl();
if (RD->isUnion()) {
const FieldDecl *UnionField = O->getUnionField();
if (!UnionField ||
UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) {
if (I == N - 1 && handler.AccessKind == AK_Construct) {
// Placement new onto an inactive union member makes it active.
O->setUnion(Field, APValue());
} else {
// FIXME: If O->getUnionValue() is absent, report that there's no
// active union member rather than reporting the prior active union
// member. We'll need to fix nullptr_t to not use APValue() as its
// representation first.
Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member)
<< handler.AccessKind << Field << !UnionField << UnionField;
return handler.failed();
}
}
O = &O->getUnionValue();
} else
O = &O->getStructField(Field->getFieldIndex());
ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable());
LastField = Field;
if (Field->getType().isVolatileQualified())
VolatileField = Field;
} else {
// Next subobject is a base class.
const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl();
const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]);
O = &O->getStructBase(getBaseIndex(Derived, Base));
ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base));
}
}
}
namespace {
struct ExtractSubobjectHandler {
EvalInfo &Info;
const Expr *E;
APValue &Result;
const AccessKinds AccessKind;
typedef bool result_type;
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
Result = Subobj;
if (AccessKind == AK_ReadObjectRepresentation)
return true;
return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result);
}
bool found(APSInt &Value, QualType SubobjType) {
Result = APValue(Value);
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
Result = APValue(Value);
return true;
}
};
} // end anonymous namespace
/// Extract the designated sub-object of an rvalue.
static bool extractSubobject(EvalInfo &Info, const Expr *E,
const CompleteObject &Obj,
const SubobjectDesignator &Sub, APValue &Result,
AccessKinds AK = AK_Read) {
assert(AK == AK_Read || AK == AK_ReadObjectRepresentation);
ExtractSubobjectHandler Handler = {Info, E, Result, AK};
return findSubobject(Info, E, Obj, Sub, Handler);
}
namespace {
struct ModifySubobjectHandler {
EvalInfo &Info;
APValue &NewVal;
const Expr *E;
typedef bool result_type;
static const AccessKinds AccessKind = AK_Assign;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
// We've been given ownership of NewVal, so just swap it in.
Subobj.swap(NewVal);
return true;
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!NewVal.isInt()) {
// Maybe trying to write a cast pointer value into a complex?
Info.FFDiag(E);
return false;
}
Value = NewVal.getInt();
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
Value = NewVal.getFloat();
return true;
}
};
} // end anonymous namespace
const AccessKinds ModifySubobjectHandler::AccessKind;
/// Update the designated sub-object of an rvalue to the given value.
static bool modifySubobject(EvalInfo &Info, const Expr *E,
const CompleteObject &Obj,
const SubobjectDesignator &Sub,
APValue &NewVal) {
ModifySubobjectHandler Handler = { Info, NewVal, E };
return findSubobject(Info, E, Obj, Sub, Handler);
}
/// Find the position where two subobject designators diverge, or equivalently
/// the length of the common initial subsequence.
static unsigned FindDesignatorMismatch(QualType ObjType,
const SubobjectDesignator &A,
const SubobjectDesignator &B,
bool &WasArrayIndex) {
unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size());
for (/**/; I != N; ++I) {
if (!ObjType.isNull() &&
(ObjType->isArrayType() || ObjType->isAnyComplexType())) {
// Next subobject is an array element.
if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) {
WasArrayIndex = true;
return I;
}
if (ObjType->isAnyComplexType())
ObjType = ObjType->castAs<ComplexType>()->getElementType();
else
ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType();
} else {
if (A.Entries[I].getAsBaseOrMember() !=
B.Entries[I].getAsBaseOrMember()) {
WasArrayIndex = false;
return I;
}
if (const FieldDecl *FD = getAsField(A.Entries[I]))
// Next subobject is a field.
ObjType = FD->getType();
else
// Next subobject is a base class.
ObjType = QualType();
}
}
WasArrayIndex = false;
return I;
}
/// Determine whether the given subobject designators refer to elements of the
/// same array object.
static bool AreElementsOfSameArray(QualType ObjType,
const SubobjectDesignator &A,
const SubobjectDesignator &B) {
if (A.Entries.size() != B.Entries.size())
return false;
bool IsArray = A.MostDerivedIsArrayElement;
if (IsArray && A.MostDerivedPathLength != A.Entries.size())
// A is a subobject of the array element.
return false;
// If A (and B) designates an array element, the last entry will be the array
// index. That doesn't have to match. Otherwise, we're in the 'implicit array
// of length 1' case, and the entire path must match.
bool WasArrayIndex;
unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex);
return CommonLength >= A.Entries.size() - IsArray;
}
/// Find the complete object to which an LValue refers.
static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E,
AccessKinds AK, const LValue &LVal,
QualType LValType) {
if (LVal.InvalidBase) {
Info.FFDiag(E);
return CompleteObject();
}
if (!LVal.Base) {
Info.FFDiag(E, diag::note_constexpr_access_null) << AK;
return CompleteObject();
}
CallStackFrame *Frame = nullptr;
unsigned Depth = 0;
if (LVal.getLValueCallIndex()) {
std::tie(Frame, Depth) =
Info.getCallFrameAndDepth(LVal.getLValueCallIndex());
if (!Frame) {
Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1)
<< AK << LVal.Base.is<const ValueDecl*>();
NoteLValueLocation(Info, LVal.Base);
return CompleteObject();
}
}
bool IsAccess = isAnyAccess(AK);
// C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type
// is not a constant expression (even if the object is non-volatile). We also
// apply this rule to C++98, in order to conform to the expected 'volatile'
// semantics.
if (isFormalAccess(AK) && LValType.isVolatileQualified()) {
if (Info.getLangOpts().CPlusPlus)
Info.FFDiag(E, diag::note_constexpr_access_volatile_type)
<< AK << LValType;
else
Info.FFDiag(E);
return CompleteObject();
}
// Compute value storage location and type of base object.
APValue *BaseVal = nullptr;
QualType BaseType = getType(LVal.Base);
if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl &&
lifetimeStartedInEvaluation(Info, LVal.Base)) {
// This is the object whose initializer we're evaluating, so its lifetime
// started in the current evaluation.
BaseVal = Info.EvaluatingDeclValue;
} else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) {
// Allow reading from a GUID declaration.
if (auto *GD = dyn_cast<MSGuidDecl>(D)) {
if (isModification(AK)) {
// All the remaining cases do not permit modification of the object.
Info.FFDiag(E, diag::note_constexpr_modify_global);
return CompleteObject();
}
APValue &V = GD->getAsAPValue();
if (V.isAbsent()) {
Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
<< GD->getType();
return CompleteObject();
}
return CompleteObject(LVal.Base, &V, GD->getType());
}
// Allow reading from template parameter objects.
if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) {
if (isModification(AK)) {
Info.FFDiag(E, diag::note_constexpr_modify_global);
return CompleteObject();
}
return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()),
TPO->getType());
}
// In C++98, const, non-volatile integers initialized with ICEs are ICEs.
// In C++11, constexpr, non-volatile variables initialized with constant
// expressions are constant expressions too. Inside constexpr functions,
// parameters are constant expressions even if they're non-const.
// In C++1y, objects local to a constant expression (those with a Frame) are
// both readable and writable inside constant expressions.
// In C, such things can also be folded, although they are not ICEs.
const VarDecl *VD = dyn_cast<VarDecl>(D);
if (VD) {
if (const VarDecl *VDef = VD->getDefinition(Info.Ctx))
VD = VDef;
}
if (!VD || VD->isInvalidDecl()) {
Info.FFDiag(E);
return CompleteObject();
}
bool IsConstant = BaseType.isConstant(Info.Ctx);
// Unless we're looking at a local variable or argument in a constexpr call,
// the variable we're reading must be const.
if (!Frame) {
if (IsAccess && isa<ParmVarDecl>(VD)) {
// Access of a parameter that's not associated with a frame isn't going
// to work out, but we can leave it to evaluateVarDeclInit to provide a
// suitable diagnostic.
} else if (Info.getLangOpts().CPlusPlus14 &&
lifetimeStartedInEvaluation(Info, LVal.Base)) {
// OK, we can read and modify an object if we're in the process of
// evaluating its initializer, because its lifetime began in this
// evaluation.
} else if (isModification(AK)) {
// All the remaining cases do not permit modification of the object.
Info.FFDiag(E, diag::note_constexpr_modify_global);
return CompleteObject();
} else if (VD->isConstexpr()) {
// OK, we can read this variable.
} else if (BaseType->isIntegralOrEnumerationType()) {
if (!IsConstant) {
if (!IsAccess)
return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
if (Info.getLangOpts().CPlusPlus) {
Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
} else if (!IsAccess) {
return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
} else if (IsConstant && Info.checkingPotentialConstantExpression() &&
BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) {
// This variable might end up being constexpr. Don't diagnose it yet.
} else if (IsConstant) {
// Keep evaluating to see what we can do. In particular, we support
// folding of const floating-point types, in order to make static const
// data members of such types (supported as an extension) more useful.
if (Info.getLangOpts().CPlusPlus) {
Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11
? diag::note_constexpr_ltor_non_constexpr
: diag::note_constexpr_ltor_non_integral, 1)
<< VD << BaseType;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.CCEDiag(E);
}
} else {
// Never allow reading a non-const value.
if (Info.getLangOpts().CPlusPlus) {
Info.FFDiag(E, Info.getLangOpts().CPlusPlus11
? diag::note_constexpr_ltor_non_constexpr
: diag::note_constexpr_ltor_non_integral, 1)
<< VD << BaseType;
Info.Note(VD->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(E);
}
return CompleteObject();
}
}
if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal))
return CompleteObject();
} else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) {
Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA);
if (!Alloc) {
Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK;
return CompleteObject();
}
return CompleteObject(LVal.Base, &(*Alloc)->Value,
LVal.Base.getDynamicAllocType());
} else {
const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
if (!Frame) {
if (const MaterializeTemporaryExpr *MTE =
dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) {
assert(MTE->getStorageDuration() == SD_Static &&
"should have a frame for a non-global materialized temporary");
// C++20 [expr.const]p4: [DR2126]
// An object or reference is usable in constant expressions if it is
// - a temporary object of non-volatile const-qualified literal type
// whose lifetime is extended to that of a variable that is usable
// in constant expressions
//
// C++20 [expr.const]p5:
// an lvalue-to-rvalue conversion [is not allowed unless it applies to]
// - a non-volatile glvalue that refers to an object that is usable
// in constant expressions, or
// - a non-volatile glvalue of literal type that refers to a
// non-volatile object whose lifetime began within the evaluation
// of E;
//
// C++11 misses the 'began within the evaluation of e' check and
// instead allows all temporaries, including things like:
// int &&r = 1;
// int x = ++r;
// constexpr int k = r;
// Therefore we use the C++14-onwards rules in C++11 too.
//
// Note that temporaries whose lifetimes began while evaluating a
// variable's constructor are not usable while evaluating the
// corresponding destructor, not even if they're of const-qualified
// types.
if (!MTE->isUsableInConstantExpressions(Info.Ctx) &&
!lifetimeStartedInEvaluation(Info, LVal.Base)) {
if (!IsAccess)
return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK;
Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here);
return CompleteObject();
}
BaseVal = MTE->getOrCreateValue(false);
assert(BaseVal && "got reference to unevaluated temporary");
} else {
if (!IsAccess)
return CompleteObject(LVal.getLValueBase(), nullptr, BaseType);
APValue Val;
LVal.moveInto(Val);
Info.FFDiag(E, diag::note_constexpr_access_unreadable_object)
<< AK
<< Val.getAsString(Info.Ctx,
Info.Ctx.getLValueReferenceType(LValType));
NoteLValueLocation(Info, LVal.Base);
return CompleteObject();
}
} else {
BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion());
assert(BaseVal && "missing value for temporary");
}
}
// In C++14, we can't safely access any mutable state when we might be
// evaluating after an unmodeled side effect. Parameters are modeled as state
// in the caller, but aren't visible once the call returns, so they can be
// modified in a speculatively-evaluated call.
//
// FIXME: Not all local state is mutable. Allow local constant subobjects
// to be read here (but take care with 'mutable' fields).
unsigned VisibleDepth = Depth;
if (llvm::isa_and_nonnull<ParmVarDecl>(
LVal.Base.dyn_cast<const ValueDecl *>()))
++VisibleDepth;
if ((Frame && Info.getLangOpts().CPlusPlus14 &&
Info.EvalStatus.HasSideEffects) ||
(isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth))
return CompleteObject();
return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType);
}
/// Perform an lvalue-to-rvalue conversion on the given glvalue. This
/// can also be used for 'lvalue-to-lvalue' conversions for looking up the
/// glvalue referred to by an entity of reference type.
///
/// \param Info - Information about the ongoing evaluation.
/// \param Conv - The expression for which we are performing the conversion.
/// Used for diagnostics.
/// \param Type - The type of the glvalue (before stripping cv-qualifiers in the
/// case of a non-class type).
/// \param LVal - The glvalue on which we are attempting to perform this action.
/// \param RVal - The produced value will be placed here.
/// \param WantObjectRepresentation - If true, we're looking for the object
/// representation rather than the value, and in particular,
/// there is no requirement that the result be fully initialized.
static bool
handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type,
const LValue &LVal, APValue &RVal,
bool WantObjectRepresentation = false) {
if (LVal.Designator.Invalid)
return false;
// Check for special cases where there is no existing APValue to look at.
const Expr *Base = LVal.Base.dyn_cast<const Expr*>();
AccessKinds AK =
WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read;
if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) {
if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
// In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
// initializer until now for such expressions. Such an expression can't be
// an ICE in C, so this only matters for fold.
if (Type.isVolatileQualified()) {
Info.FFDiag(Conv);
return false;
}
APValue Lit;
if (!Evaluate(Lit, Info, CLE->getInitializer()))
return false;
CompleteObject LitObj(LVal.Base, &Lit, Base->getType());
return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK);
} else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) {
// Special-case character extraction so we don't have to construct an
// APValue for the whole string.
assert(LVal.Designator.Entries.size() <= 1 &&
"Can only read characters from string literals");
if (LVal.Designator.Entries.empty()) {
// Fail for now for LValue to RValue conversion of an array.
// (This shouldn't show up in C/C++, but it could be triggered by a
// weird EvaluateAsRValue call from a tool.)
Info.FFDiag(Conv);
return false;
}
if (LVal.Designator.isOnePastTheEnd()) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK;
else
Info.FFDiag(Conv);
return false;
}
uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex();
RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex));
return true;
}
}
CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type);
return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK);
}
/// Perform an assignment of Val to LVal. Takes ownership of Val.
static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal,
QualType LValType, APValue &Val) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val);
}
namespace {
struct CompoundAssignSubobjectHandler {
EvalInfo &Info;
const CompoundAssignOperator *E;
QualType PromotedLHSType;
BinaryOperatorKind Opcode;
const APValue &RHS;
static const AccessKinds AccessKind = AK_Assign;
typedef bool result_type;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
switch (Subobj.getKind()) {
case APValue::Int:
return found(Subobj.getInt(), SubobjType);
case APValue::Float:
return found(Subobj.getFloat(), SubobjType);
case APValue::ComplexInt:
case APValue::ComplexFloat:
// FIXME: Implement complex compound assignment.
Info.FFDiag(E);
return false;
case APValue::LValue:
return foundPointer(Subobj, SubobjType);
case APValue::Vector:
return foundVector(Subobj, SubobjType);
default:
// FIXME: can this happen?
Info.FFDiag(E);
return false;
}
}
bool foundVector(APValue &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!SubobjType->isVectorType()) {
Info.FFDiag(E);
return false;
}
return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS);
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!SubobjType->isIntegerType()) {
// We don't support compound assignment on integer-cast-to-pointer
// values.
Info.FFDiag(E);
return false;
}
if (RHS.isInt()) {
APSInt LHS =
HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value);
if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS))
return false;
Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS);
return true;
} else if (RHS.isFloat()) {
const FPOptions FPO = E->getFPFeaturesInEffect(
Info.Ctx.getLangOpts());
APFloat FValue(0.0);
return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value,
PromotedLHSType, FValue) &&
handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) &&
HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType,
Value);
}
Info.FFDiag(E);
return false;
}
bool found(APFloat &Value, QualType SubobjType) {
return checkConst(SubobjType) &&
HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType,
Value) &&
handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) &&
HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value);
}
bool foundPointer(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
QualType PointeeType;
if (const PointerType *PT = SubobjType->getAs<PointerType>())
PointeeType = PT->getPointeeType();
if (PointeeType.isNull() || !RHS.isInt() ||
(Opcode != BO_Add && Opcode != BO_Sub)) {
Info.FFDiag(E);
return false;
}
APSInt Offset = RHS.getInt();
if (Opcode == BO_Sub)
negateAsSigned(Offset);
LValue LVal;
LVal.setFrom(Info.Ctx, Subobj);
if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset))
return false;
LVal.moveInto(Subobj);
return true;
}
};
} // end anonymous namespace
const AccessKinds CompoundAssignSubobjectHandler::AccessKind;
/// Perform a compound assignment of LVal <op>= RVal.
static bool handleCompoundAssignment(EvalInfo &Info,
const CompoundAssignOperator *E,
const LValue &LVal, QualType LValType,
QualType PromotedLValType,
BinaryOperatorKind Opcode,
const APValue &RVal) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType);
CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode,
RVal };
return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
}
namespace {
struct IncDecSubobjectHandler {
EvalInfo &Info;
const UnaryOperator *E;
AccessKinds AccessKind;
APValue *Old;
typedef bool result_type;
bool checkConst(QualType QT) {
// Assigning to a const object has undefined behavior.
if (QT.isConstQualified()) {
Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT;
return false;
}
return true;
}
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
// Stash the old value. Also clear Old, so we don't clobber it later
// if we're post-incrementing a complex.
if (Old) {
*Old = Subobj;
Old = nullptr;
}
switch (Subobj.getKind()) {
case APValue::Int:
return found(Subobj.getInt(), SubobjType);
case APValue::Float:
return found(Subobj.getFloat(), SubobjType);
case APValue::ComplexInt:
return found(Subobj.getComplexIntReal(),
SubobjType->castAs<ComplexType>()->getElementType()
.withCVRQualifiers(SubobjType.getCVRQualifiers()));
case APValue::ComplexFloat:
return found(Subobj.getComplexFloatReal(),
SubobjType->castAs<ComplexType>()->getElementType()
.withCVRQualifiers(SubobjType.getCVRQualifiers()));
case APValue::LValue:
return foundPointer(Subobj, SubobjType);
default:
// FIXME: can this happen?
Info.FFDiag(E);
return false;
}
}
bool found(APSInt &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (!SubobjType->isIntegerType()) {
// We don't support increment / decrement on integer-cast-to-pointer
// values.
Info.FFDiag(E);
return false;
}
if (Old) *Old = APValue(Value);
// bool arithmetic promotes to int, and the conversion back to bool
// doesn't reduce mod 2^n, so special-case it.
if (SubobjType->isBooleanType()) {
if (AccessKind == AK_Increment)
Value = 1;
else
Value = !Value;
return true;
}
bool WasNegative = Value.isNegative();
if (AccessKind == AK_Increment) {
++Value;
if (!WasNegative && Value.isNegative() && E->canOverflow()) {
APSInt ActualValue(Value, /*IsUnsigned*/true);
return HandleOverflow(Info, E, ActualValue, SubobjType);
}
} else {
--Value;
if (WasNegative && !Value.isNegative() && E->canOverflow()) {
unsigned BitWidth = Value.getBitWidth();
APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false);
ActualValue.setBit(BitWidth);
return HandleOverflow(Info, E, ActualValue, SubobjType);
}
}
return true;
}
bool found(APFloat &Value, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
if (Old) *Old = APValue(Value);
APFloat One(Value.getSemantics(), 1);
if (AccessKind == AK_Increment)
Value.add(One, APFloat::rmNearestTiesToEven);
else
Value.subtract(One, APFloat::rmNearestTiesToEven);
return true;
}
bool foundPointer(APValue &Subobj, QualType SubobjType) {
if (!checkConst(SubobjType))
return false;
QualType PointeeType;
if (const PointerType *PT = SubobjType->getAs<PointerType>())
PointeeType = PT->getPointeeType();
else {
Info.FFDiag(E);
return false;
}
LValue LVal;
LVal.setFrom(Info.Ctx, Subobj);
if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType,
AccessKind == AK_Increment ? 1 : -1))
return false;
LVal.moveInto(Subobj);
return true;
}
};
} // end anonymous namespace
/// Perform an increment or decrement on LVal.
static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal,
QualType LValType, bool IsIncrement, APValue *Old) {
if (LVal.Designator.Invalid)
return false;
if (!Info.getLangOpts().CPlusPlus14) {
Info.FFDiag(E);
return false;
}
AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement;
CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType);
IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old};
return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler);
}
/// Build an lvalue for the object argument of a member function call.
static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object,
LValue &This) {
if (Object->getType()->isPointerType() && Object->isRValue())
return EvaluatePointer(Object, This, Info);
if (Object->isGLValue())
return EvaluateLValue(Object, This, Info);
if (Object->getType()->isLiteralType(Info.Ctx))
return EvaluateTemporary(Object, This, Info);
Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType();
return false;
}
/// HandleMemberPointerAccess - Evaluate a member access operation and build an
/// lvalue referring to the result.
///
/// \param Info - Information about the ongoing evaluation.
/// \param LV - An lvalue referring to the base of the member pointer.
/// \param RHS - The member pointer expression.
/// \param IncludeMember - Specifies whether the member itself is included in
/// the resulting LValue subobject designator. This is not possible when
/// creating a bound member function.
/// \return The field or method declaration to which the member pointer refers,
/// or 0 if evaluation fails.
static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
QualType LVType,
LValue &LV,
const Expr *RHS,
bool IncludeMember = true) {
MemberPtr MemPtr;
if (!EvaluateMemberPointer(RHS, MemPtr, Info))
return nullptr;
// C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to
// member value, the behavior is undefined.
if (!MemPtr.getDecl()) {
// FIXME: Specific diagnostic.
Info.FFDiag(RHS);
return nullptr;
}
if (MemPtr.isDerivedMember()) {
// This is a member of some derived class. Truncate LV appropriately.
// The end of the derived-to-base path for the base object must match the
// derived-to-base path for the member pointer.
if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() >
LV.Designator.Entries.size()) {
Info.FFDiag(RHS);
return nullptr;
}
unsigned PathLengthToMember =
LV.Designator.Entries.size() - MemPtr.Path.size();
for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) {
const CXXRecordDecl *LVDecl = getAsBaseClass(
LV.Designator.Entries[PathLengthToMember + I]);
const CXXRecordDecl *MPDecl = MemPtr.Path[I];
if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) {
Info.FFDiag(RHS);
return nullptr;
}
}
// Truncate the lvalue to the appropriate derived class.
if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(),
PathLengthToMember))
return nullptr;
} else if (!MemPtr.Path.empty()) {
// Extend the LValue path with the member pointer's path.
LV.Designator.Entries.reserve(LV.Designator.Entries.size() +
MemPtr.Path.size() + IncludeMember);
// Walk down to the appropriate base class.
if (const PointerType *PT = LVType->getAs<PointerType>())
LVType = PT->getPointeeType();
const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl();
assert(RD && "member pointer access on non-class-type expression");
// The first class in the path is that of the lvalue.
for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) {
const CXXRecordDecl *Base = MemPtr.Path[N - I - 1];
if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base))
return nullptr;
RD = Base;
}
// Finally cast to the class containing the member.
if (!HandleLValueDirectBase(Info, RHS, LV, RD,
MemPtr.getContainingRecord()))
return nullptr;
}
// Add the member. Note that we cannot build bound member functions here.
if (IncludeMember) {
if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) {
if (!HandleLValueMember(Info, RHS, LV, FD))
return nullptr;
} else if (const IndirectFieldDecl *IFD =
dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) {
if (!HandleLValueIndirectMember(Info, RHS, LV, IFD))
return nullptr;
} else {
llvm_unreachable("can't construct reference to bound member function");
}
}
return MemPtr.getDecl();
}
static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info,
const BinaryOperator *BO,
LValue &LV,
bool IncludeMember = true) {
assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI);
if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) {
if (Info.noteFailure()) {
MemberPtr MemPtr;
EvaluateMemberPointer(BO->getRHS(), MemPtr, Info);
}
return nullptr;
}
return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV,
BO->getRHS(), IncludeMember);
}
/// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on
/// the provided lvalue, which currently refers to the base object.
static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E,
LValue &Result) {
SubobjectDesignator &D = Result.Designator;
if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived))
return false;
QualType TargetQT = E->getType();
if (const PointerType *PT = TargetQT->getAs<PointerType>())
TargetQT = PT->getPointeeType();
// Check this cast lands within the final derived-to-base subobject path.
if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) {
Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
<< D.MostDerivedType << TargetQT;
return false;
}
// Check the type of the final cast. We don't need to check the path,
// since a cast can only be formed if the path is unique.
unsigned NewEntriesSize = D.Entries.size() - E->path_size();
const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl();
const CXXRecordDecl *FinalType;
if (NewEntriesSize == D.MostDerivedPathLength)
FinalType = D.MostDerivedType->getAsCXXRecordDecl();
else
FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]);
if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) {
Info.CCEDiag(E, diag::note_constexpr_invalid_downcast)
<< D.MostDerivedType << TargetQT;
return false;
}
// Truncate the lvalue to the appropriate derived class.
return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize);
}
/// Get the value to use for a default-initialized object of type T.
/// Return false if it encounters something invalid.
static bool getDefaultInitValue(QualType T, APValue &Result) {
bool Success = true;
if (auto *RD = T->getAsCXXRecordDecl()) {
if (RD->isInvalidDecl()) {
Result = APValue();
return false;
}
if (RD->isUnion()) {
Result = APValue((const FieldDecl *)nullptr);
return true;
}
Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
std::distance(RD->field_begin(), RD->field_end()));
unsigned Index = 0;
for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(),
End = RD->bases_end();
I != End; ++I, ++Index)
Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index));
for (const auto *I : RD->fields()) {
if (I->isUnnamedBitfield())
continue;
Success &= getDefaultInitValue(I->getType(),
Result.getStructField(I->getFieldIndex()));
}
return Success;
}
if (auto *AT =
dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
if (Result.hasArrayFiller())
Success &=
getDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
return Success;
}
Result = APValue::IndeterminateValue();
return true;
}
namespace {
enum EvalStmtResult {
/// Evaluation failed.
ESR_Failed,
/// Hit a 'return' statement.
ESR_Returned,
/// Evaluation succeeded.
ESR_Succeeded,
/// Hit a 'continue' statement.
ESR_Continue,
/// Hit a 'break' statement.
ESR_Break,
/// Still scanning for 'case' or 'default' statement.
ESR_CaseNotFound
};
}
static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) {
// We don't need to evaluate the initializer for a static local.
if (!VD->hasLocalStorage())
return true;
LValue Result;
APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(),
ScopeKind::Block, Result);
const Expr *InitE = VD->getInit();
if (!InitE) {
if (VD->getType()->isDependentType())
return Info.noteSideEffect();
return getDefaultInitValue(VD->getType(), Val);
}
if (InitE->isValueDependent())
return false;
if (!EvaluateInPlace(Val, Info, Result, InitE)) {
// Wipe out any partially-computed value, to allow tracking that this
// evaluation failed.
Val = APValue();
return false;
}
return true;
}
static bool EvaluateDecl(EvalInfo &Info, const Decl *D) {
bool OK = true;
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
OK &= EvaluateVarDecl(Info, VD);
if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D))
for (auto *BD : DD->bindings())
if (auto *VD = BD->getHoldingVar())
OK &= EvaluateDecl(Info, VD);
return OK;
}
static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) {
assert(E->isValueDependent());
if (Info.noteSideEffect())
return true;
assert(E->containsErrors() && "valid value-dependent expression should never "
"reach invalid code path.");
return false;
}
/// Evaluate a condition (either a variable declaration or an expression).
static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl,
const Expr *Cond, bool &Result) {
if (Cond->isValueDependent())
return false;
FullExpressionRAII Scope(Info);
if (CondDecl && !EvaluateDecl(Info, CondDecl))
return false;
if (!EvaluateAsBooleanCondition(Cond, Result, Info))
return false;
return Scope.destroy();
}
namespace {
/// A location where the result (returned value) of evaluating a
/// statement should be stored.
struct StmtResult {
/// The APValue that should be filled in with the returned value.
APValue &Value;
/// The location containing the result, if any (used to support RVO).
const LValue *Slot;
};
struct TempVersionRAII {
CallStackFrame &Frame;
TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) {
Frame.pushTempVersion();
}
~TempVersionRAII() {
Frame.popTempVersion();
}
};
}
static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S,
const SwitchCase *SC = nullptr);
/// Evaluate the body of a loop, and translate the result as appropriate.
static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info,
const Stmt *Body,
const SwitchCase *Case = nullptr) {
BlockScopeRAII Scope(Info);
EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case);
if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
ESR = ESR_Failed;
switch (ESR) {
case ESR_Break:
return ESR_Succeeded;
case ESR_Succeeded:
case ESR_Continue:
return ESR_Continue;
case ESR_Failed:
case ESR_Returned:
case ESR_CaseNotFound:
return ESR;
}
llvm_unreachable("Invalid EvalStmtResult!");
}
/// Evaluate a switch statement.
static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info,
const SwitchStmt *SS) {
BlockScopeRAII Scope(Info);
// Evaluate the switch condition.
APSInt Value;
{
if (const Stmt *Init = SS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
ESR = ESR_Failed;
return ESR;
}
}
FullExpressionRAII CondScope(Info);
if (SS->getConditionVariable() &&
!EvaluateDecl(Info, SS->getConditionVariable()))
return ESR_Failed;
if (!EvaluateInteger(SS->getCond(), Value, Info))
return ESR_Failed;
if (!CondScope.destroy())
return ESR_Failed;
}
// Find the switch case corresponding to the value of the condition.
// FIXME: Cache this lookup.
const SwitchCase *Found = nullptr;
for (const SwitchCase *SC = SS->getSwitchCaseList(); SC;
SC = SC->getNextSwitchCase()) {
if (isa<DefaultStmt>(SC)) {
Found = SC;
continue;
}
const CaseStmt *CS = cast<CaseStmt>(SC);
APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx);
APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx)
: LHS;
if (LHS <= Value && Value <= RHS) {
Found = SC;
break;
}
}
if (!Found)
return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
// Search the switch body for the switch case and evaluate it from there.
EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found);
if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy())
return ESR_Failed;
switch (ESR) {
case ESR_Break:
return ESR_Succeeded;
case ESR_Succeeded:
case ESR_Continue:
case ESR_Failed:
case ESR_Returned:
return ESR;
case ESR_CaseNotFound:
// This can only happen if the switch case is nested within a statement
// expression. We have no intention of supporting that.
Info.FFDiag(Found->getBeginLoc(),
diag::note_constexpr_stmt_expr_unsupported);
return ESR_Failed;
}
llvm_unreachable("Invalid EvalStmtResult!");
}
// Evaluate a statement.
static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info,
const Stmt *S, const SwitchCase *Case) {
if (!Info.nextStep(S))
return ESR_Failed;
// If we're hunting down a 'case' or 'default' label, recurse through
// substatements until we hit the label.
if (Case) {
switch (S->getStmtClass()) {
case Stmt::CompoundStmtClass:
// FIXME: Precompute which substatement of a compound statement we
// would jump to, and go straight there rather than performing a
// linear scan each time.
case Stmt::LabelStmtClass:
case Stmt::AttributedStmtClass:
case Stmt::DoStmtClass:
break;
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
if (Case == S)
Case = nullptr;
break;
case Stmt::IfStmtClass: {
// FIXME: Precompute which side of an 'if' we would jump to, and go
// straight there rather than scanning both sides.
const IfStmt *IS = cast<IfStmt>(S);
// Wrap the evaluation in a block scope, in case it's a DeclStmt
// preceded by our switch label.
BlockScopeRAII Scope(Info);
// Step into the init statement in case it brings an (uninitialized)
// variable into scope.
if (const Stmt *Init = IS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
if (ESR != ESR_CaseNotFound) {
assert(ESR != ESR_Succeeded);
return ESR;
}
}
// Condition variable must be initialized if it exists.
// FIXME: We can skip evaluating the body if there's a condition
// variable, as there can't be any case labels within it.
// (The same is true for 'for' statements.)
EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case);
if (ESR == ESR_Failed)
return ESR;
if (ESR != ESR_CaseNotFound)
return Scope.destroy() ? ESR : ESR_Failed;
if (!IS->getElse())
return ESR_CaseNotFound;
ESR = EvaluateStmt(Result, Info, IS->getElse(), Case);
if (ESR == ESR_Failed)
return ESR;
if (ESR != ESR_CaseNotFound)
return Scope.destroy() ? ESR : ESR_Failed;
return ESR_CaseNotFound;
}
case Stmt::WhileStmtClass: {
EvalStmtResult ESR =
EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
break;
}
case Stmt::ForStmtClass: {
const ForStmt *FS = cast<ForStmt>(S);
BlockScopeRAII Scope(Info);
// Step into the init statement in case it brings an (uninitialized)
// variable into scope.
if (const Stmt *Init = FS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case);
if (ESR != ESR_CaseNotFound) {
assert(ESR != ESR_Succeeded);
return ESR;
}
}
EvalStmtResult ESR =
EvaluateLoopBody(Result, Info, FS->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
if (const auto *Inc = FS->getInc()) {
if (Inc->isValueDependent()) {
if (!EvaluateDependentExpr(Inc, Info))
return ESR_Failed;
} else {
FullExpressionRAII IncScope(Info);
if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
return ESR_Failed;
}
}
break;
}
case Stmt::DeclStmtClass: {
// Start the lifetime of any uninitialized variables we encounter. They
// might be used by the selected branch of the switch.
const DeclStmt *DS = cast<DeclStmt>(S);
for (const auto *D : DS->decls()) {
if (const auto *VD = dyn_cast<VarDecl>(D)) {
if (VD->hasLocalStorage() && !VD->getInit())
if (!EvaluateVarDecl(Info, VD))
return ESR_Failed;
// FIXME: If the variable has initialization that can't be jumped
// over, bail out of any immediately-surrounding compound-statement
// too. There can't be any case labels here.
}
}
return ESR_CaseNotFound;
}
default:
return ESR_CaseNotFound;
}
}
switch (S->getStmtClass()) {
default:
if (const Expr *E = dyn_cast<Expr>(S)) {
if (E->isValueDependent()) {
if (!EvaluateDependentExpr(E, Info))
return ESR_Failed;
} else {
// Don't bother evaluating beyond an expression-statement which couldn't
// be evaluated.
// FIXME: Do we need the FullExpressionRAII object here?
// VisitExprWithCleanups should create one when necessary.
FullExpressionRAII Scope(Info);
if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy())
return ESR_Failed;
}
return ESR_Succeeded;
}
Info.FFDiag(S->getBeginLoc());
return ESR_Failed;
case Stmt::NullStmtClass:
return ESR_Succeeded;
case Stmt::DeclStmtClass: {
const DeclStmt *DS = cast<DeclStmt>(S);
for (const auto *D : DS->decls()) {
// Each declaration initialization is its own full-expression.
FullExpressionRAII Scope(Info);
if (!EvaluateDecl(Info, D) && !Info.noteFailure())
return ESR_Failed;
if (!Scope.destroy())
return ESR_Failed;
}
return ESR_Succeeded;
}
case Stmt::ReturnStmtClass: {
const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue();
FullExpressionRAII Scope(Info);
if (RetExpr && RetExpr->isValueDependent()) {
EvaluateDependentExpr(RetExpr, Info);
// We know we returned, but we don't know what the value is.
return ESR_Failed;
}
if (RetExpr &&
!(Result.Slot
? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr)
: Evaluate(Result.Value, Info, RetExpr)))
return ESR_Failed;
return Scope.destroy() ? ESR_Returned : ESR_Failed;
}
case Stmt::CompoundStmtClass: {
BlockScopeRAII Scope(Info);
const CompoundStmt *CS = cast<CompoundStmt>(S);
for (const auto *BI : CS->body()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case);
if (ESR == ESR_Succeeded)
Case = nullptr;
else if (ESR != ESR_CaseNotFound) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
}
if (Case)
return ESR_CaseNotFound;
return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
}
case Stmt::IfStmtClass: {
const IfStmt *IS = cast<IfStmt>(S);
// Evaluate the condition, as either a var decl or as an expression.
BlockScopeRAII Scope(Info);
if (const Stmt *Init = IS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, Init);
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
}
bool Cond;
if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond))
return ESR_Failed;
if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt);
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
}
return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
}
case Stmt::WhileStmtClass: {
const WhileStmt *WS = cast<WhileStmt>(S);
while (true) {
BlockScopeRAII Scope(Info);
bool Continue;
if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(),
Continue))
return ESR_Failed;
if (!Continue)
break;
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody());
if (ESR != ESR_Continue) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
if (!Scope.destroy())
return ESR_Failed;
}
return ESR_Succeeded;
}
case Stmt::DoStmtClass: {
const DoStmt *DS = cast<DoStmt>(S);
bool Continue;
do {
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case);
if (ESR != ESR_Continue)
return ESR;
Case = nullptr;
if (DS->getCond()->isValueDependent()) {
EvaluateDependentExpr(DS->getCond(), Info);
// Bailout as we don't know whether to keep going or terminate the loop.
return ESR_Failed;
}
FullExpressionRAII CondScope(Info);
if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) ||
!CondScope.destroy())
return ESR_Failed;
} while (Continue);
return ESR_Succeeded;
}
case Stmt::ForStmtClass: {
const ForStmt *FS = cast<ForStmt>(S);
BlockScopeRAII ForScope(Info);
if (FS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !ForScope.destroy())
return ESR_Failed;
return ESR;
}
}
while (true) {
BlockScopeRAII IterScope(Info);
bool Continue = true;
if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(),
FS->getCond(), Continue))
return ESR_Failed;
if (!Continue)
break;
EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody());
if (ESR != ESR_Continue) {
if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy()))
return ESR_Failed;
return ESR;
}
if (const auto *Inc = FS->getInc()) {
if (Inc->isValueDependent()) {
if (!EvaluateDependentExpr(Inc, Info))
return ESR_Failed;
} else {
FullExpressionRAII IncScope(Info);
if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy())
return ESR_Failed;
}
}
if (!IterScope.destroy())
return ESR_Failed;
}
return ForScope.destroy() ? ESR_Succeeded : ESR_Failed;
}
case Stmt::CXXForRangeStmtClass: {
const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S);
BlockScopeRAII Scope(Info);
// Evaluate the init-statement if present.
if (FS->getInit()) {
EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
}
// Initialize the __range variable.
EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
// Create the __begin and __end iterators.
ESR = EvaluateStmt(Result, Info, FS->getBeginStmt());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
ESR = EvaluateStmt(Result, Info, FS->getEndStmt());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && !Scope.destroy())
return ESR_Failed;
return ESR;
}
while (true) {
// Condition: __begin != __end.
{
if (FS->getCond()->isValueDependent()) {
EvaluateDependentExpr(FS->getCond(), Info);
// We don't know whether to keep going or terminate the loop.
return ESR_Failed;
}
bool Continue = true;
FullExpressionRAII CondExpr(Info);
if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info))
return ESR_Failed;
if (!Continue)
break;
}
// User's variable declaration, initialized by *__begin.
BlockScopeRAII InnerScope(Info);
ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt());
if (ESR != ESR_Succeeded) {
if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
return ESR_Failed;
return ESR;
}
// Loop body.
ESR = EvaluateLoopBody(Result, Info, FS->getBody());
if (ESR != ESR_Continue) {
if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy()))
return ESR_Failed;
return ESR;
}
if (FS->getInc()->isValueDependent()) {
if (!EvaluateDependentExpr(FS->getInc(), Info))
return ESR_Failed;
} else {
// Increment: ++__begin
if (!EvaluateIgnoredValue(Info, FS->getInc()))
return ESR_Failed;
}
if (!InnerScope.destroy())
return ESR_Failed;
}
return Scope.destroy() ? ESR_Succeeded : ESR_Failed;
}
case Stmt::SwitchStmtClass:
return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S));
case Stmt::ContinueStmtClass:
return ESR_Continue;
case Stmt::BreakStmtClass:
return ESR_Break;
case Stmt::LabelStmtClass:
return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case);
case Stmt::AttributedStmtClass:
// As a general principle, C++11 attributes can be ignored without
// any semantic impact.
return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(),
Case);
case Stmt::CaseStmtClass:
case Stmt::DefaultStmtClass:
return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case);
case Stmt::CXXTryStmtClass:
// Evaluate try blocks by evaluating all sub statements.
return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case);
}
}
/// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial
/// default constructor. If so, we'll fold it whether or not it's marked as
/// constexpr. If it is marked as constexpr, we will never implicitly define it,
/// so we need special handling.
static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc,
const CXXConstructorDecl *CD,
bool IsValueInitialization) {
if (!CD->isTrivial() || !CD->isDefaultConstructor())
return false;
// Value-initialization does not call a trivial default constructor, so such a
// call is a core constant expression whether or not the constructor is
// constexpr.
if (!CD->isConstexpr() && !IsValueInitialization) {
if (Info.getLangOpts().CPlusPlus11) {
// FIXME: If DiagDecl is an implicitly-declared special member function,
// we should be much more explicit about why it's not constexpr.
Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1)
<< /*IsConstexpr*/0 << /*IsConstructor*/1 << CD;
Info.Note(CD->getLocation(), diag::note_declared_at);
} else {
Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr);
}
}
return true;
}
/// CheckConstexprFunction - Check that a function can be called in a constant
/// expression.
static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc,
const FunctionDecl *Declaration,
const FunctionDecl *Definition,
const Stmt *Body) {
// Potential constant expressions can contain calls to declared, but not yet
// defined, constexpr functions.
if (Info.checkingPotentialConstantExpression() && !Definition &&
Declaration->isConstexpr())
return false;
// Bail out if the function declaration itself is invalid. We will
// have produced a relevant diagnostic while parsing it, so just
// note the problematic sub-expression.
if (Declaration->isInvalidDecl()) {
Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
return false;
}
// DR1872: An instantiated virtual constexpr function can't be called in a
// constant expression (prior to C++20). We can still constant-fold such a
// call.
if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) &&
cast<CXXMethodDecl>(Declaration)->isVirtual())
Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call);
if (Definition && Definition->isInvalidDecl()) {
Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
return false;
}
// Can we evaluate this function call?
if (Definition && Definition->isConstexpr() && Body)
return true;
if (Info.getLangOpts().CPlusPlus11) {
const FunctionDecl *DiagDecl = Definition ? Definition : Declaration;
// If this function is not constexpr because it is an inherited
// non-constexpr constructor, diagnose that directly.
auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl);
if (CD && CD->isInheritingConstructor()) {
auto *Inherited = CD->getInheritedConstructor().getConstructor();
if (!Inherited->isConstexpr())
DiagDecl = CD = Inherited;
}
// FIXME: If DiagDecl is an implicitly-declared special member function
// or an inheriting constructor, we should be much more explicit about why
// it's not constexpr.
if (CD && CD->isInheritingConstructor())
Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1)
<< CD->getInheritedConstructor().getConstructor()->getParent();
else
Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1)
<< DiagDecl->isConstexpr() << (bool)CD << DiagDecl;
Info.Note(DiagDecl->getLocation(), diag::note_declared_at);
} else {
Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr);
}
return false;
}
namespace {
struct CheckDynamicTypeHandler {
AccessKinds AccessKind;
typedef bool result_type;
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) { return true; }
bool found(APSInt &Value, QualType SubobjType) { return true; }
bool found(APFloat &Value, QualType SubobjType) { return true; }
};
} // end anonymous namespace
/// Check that we can access the notional vptr of an object / determine its
/// dynamic type.
static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This,
AccessKinds AK, bool Polymorphic) {
if (This.Designator.Invalid)
return false;
CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType());
if (!Obj)
return false;
if (!Obj.Value) {
// The object is not usable in constant expressions, so we can't inspect
// its value to see if it's in-lifetime or what the active union members
// are. We can still check for a one-past-the-end lvalue.
if (This.Designator.isOnePastTheEnd() ||
This.Designator.isMostDerivedAnUnsizedArray()) {
Info.FFDiag(E, This.Designator.isOnePastTheEnd()
? diag::note_constexpr_access_past_end
: diag::note_constexpr_access_unsized_array)
<< AK;
return false;
} else if (Polymorphic) {
// Conservatively refuse to perform a polymorphic operation if we would
// not be able to read a notional 'vptr' value.
APValue Val;
This.moveInto(Val);
QualType StarThisType =
Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx));
Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type)
<< AK << Val.getAsString(Info.Ctx, StarThisType);
return false;
}
return true;
}
CheckDynamicTypeHandler Handler{AK};
return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
}
/// Check that the pointee of the 'this' pointer in a member function call is
/// either within its lifetime or in its period of construction or destruction.
static bool
checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E,
const LValue &This,
const CXXMethodDecl *NamedMember) {
return checkDynamicType(
Info, E, This,
isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false);
}
struct DynamicType {
/// The dynamic class type of the object.
const CXXRecordDecl *Type;
/// The corresponding path length in the lvalue.
unsigned PathLength;
};
static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator,
unsigned PathLength) {
assert(PathLength >= Designator.MostDerivedPathLength && PathLength <=
Designator.Entries.size() && "invalid path length");
return (PathLength == Designator.MostDerivedPathLength)
? Designator.MostDerivedType->getAsCXXRecordDecl()
: getAsBaseClass(Designator.Entries[PathLength - 1]);
}
/// Determine the dynamic type of an object.
static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E,
LValue &This, AccessKinds AK) {
// If we don't have an lvalue denoting an object of class type, there is no
// meaningful dynamic type. (We consider objects of non-class type to have no
// dynamic type.)
if (!checkDynamicType(Info, E, This, AK, true))
return None;
// Refuse to compute a dynamic type in the presence of virtual bases. This
// shouldn't happen other than in constant-folding situations, since literal
// types can't have virtual bases.
//
// Note that consumers of DynamicType assume that the type has no virtual
// bases, and will need modifications if this restriction is relaxed.
const CXXRecordDecl *Class =
This.Designator.MostDerivedType->getAsCXXRecordDecl();
if (!Class || Class->getNumVBases()) {
Info.FFDiag(E);
return None;
}
// FIXME: For very deep class hierarchies, it might be beneficial to use a
// binary search here instead. But the overwhelmingly common case is that
// we're not in the middle of a constructor, so it probably doesn't matter
// in practice.
ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries;
for (unsigned PathLength = This.Designator.MostDerivedPathLength;
PathLength <= Path.size(); ++PathLength) {
switch (Info.isEvaluatingCtorDtor(This.getLValueBase(),
Path.slice(0, PathLength))) {
case ConstructionPhase::Bases:
case ConstructionPhase::DestroyingBases:
// We're constructing or destroying a base class. This is not the dynamic
// type.
break;
case ConstructionPhase::None:
case ConstructionPhase::AfterBases:
case ConstructionPhase::AfterFields:
case ConstructionPhase::Destroying:
// We've finished constructing the base classes and not yet started
// destroying them again, so this is the dynamic type.
return DynamicType{getBaseClassType(This.Designator, PathLength),
PathLength};
}
}
// CWG issue 1517: we're constructing a base class of the object described by
// 'This', so that object has not yet begun its period of construction and
// any polymorphic operation on it results in undefined behavior.
Info.FFDiag(E);
return None;
}
/// Perform virtual dispatch.
static const CXXMethodDecl *HandleVirtualDispatch(
EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found,
llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) {
Optional<DynamicType> DynType = ComputeDynamicType(
Info, E, This,
isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall);
if (!DynType)
return nullptr;
// Find the final overrider. It must be declared in one of the classes on the
// path from the dynamic type to the static type.
// FIXME: If we ever allow literal types to have virtual base classes, that
// won't be true.
const CXXMethodDecl *Callee = Found;
unsigned PathLength = DynType->PathLength;
for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) {
const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength);
const CXXMethodDecl *Overrider =
Found->getCorrespondingMethodDeclaredInClass(Class, false);
if (Overrider) {
Callee = Overrider;
break;
}
}
// C++2a [class.abstract]p6:
// the effect of making a virtual call to a pure virtual function [...] is
// undefined
if (Callee->isPure()) {
Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee;
Info.Note(Callee->getLocation(), diag::note_declared_at);
return nullptr;
}
// If necessary, walk the rest of the path to determine the sequence of
// covariant adjustment steps to apply.
if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(),
Found->getReturnType())) {
CovariantAdjustmentPath.push_back(Callee->getReturnType());
for (unsigned CovariantPathLength = PathLength + 1;
CovariantPathLength != This.Designator.Entries.size();
++CovariantPathLength) {
const CXXRecordDecl *NextClass =
getBaseClassType(This.Designator, CovariantPathLength);
const CXXMethodDecl *Next =
Found->getCorrespondingMethodDeclaredInClass(NextClass, false);
if (Next && !Info.Ctx.hasSameUnqualifiedType(
Next->getReturnType(), CovariantAdjustmentPath.back()))
CovariantAdjustmentPath.push_back(Next->getReturnType());
}
if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(),
CovariantAdjustmentPath.back()))
CovariantAdjustmentPath.push_back(Found->getReturnType());
}
// Perform 'this' adjustment.
if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength))
return nullptr;
return Callee;
}
/// Perform the adjustment from a value returned by a virtual function to
/// a value of the statically expected type, which may be a pointer or
/// reference to a base class of the returned type.
static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E,
APValue &Result,
ArrayRef<QualType> Path) {
assert(Result.isLValue() &&
"unexpected kind of APValue for covariant return");
if (Result.isNullPointer())
return true;
LValue LVal;
LVal.setFrom(Info.Ctx, Result);
const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl();
for (unsigned I = 1; I != Path.size(); ++I) {
const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl();
assert(OldClass && NewClass && "unexpected kind of covariant return");
if (OldClass != NewClass &&
!CastToBaseClass(Info, E, LVal, OldClass, NewClass))
return false;
OldClass = NewClass;
}
LVal.moveInto(Result);
return true;
}
/// Determine whether \p Base, which is known to be a direct base class of
/// \p Derived, is a public base class.
static bool isBaseClassPublic(const CXXRecordDecl *Derived,
const CXXRecordDecl *Base) {
for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) {
auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl();
if (BaseClass && declaresSameEntity(BaseClass, Base))
return BaseSpec.getAccessSpecifier() == AS_public;
}
llvm_unreachable("Base is not a direct base of Derived");
}
/// Apply the given dynamic cast operation on the provided lvalue.
///
/// This implements the hard case of dynamic_cast, requiring a "runtime check"
/// to find a suitable target subobject.
static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E,
LValue &Ptr) {
// We can't do anything with a non-symbolic pointer value.
SubobjectDesignator &D = Ptr.Designator;
if (D.Invalid)
return false;
// C++ [expr.dynamic.cast]p6:
// If v is a null pointer value, the result is a null pointer value.
if (Ptr.isNullPointer() && !E->isGLValue())
return true;
// For all the other cases, we need the pointer to point to an object within
// its lifetime / period of construction / destruction, and we need to know
// its dynamic type.
Optional<DynamicType> DynType =
ComputeDynamicType(Info, E, Ptr, AK_DynamicCast);
if (!DynType)
return false;
// C++ [expr.dynamic.cast]p7:
// If T is "pointer to cv void", then the result is a pointer to the most
// derived object
if (E->getType()->isVoidPointerType())
return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength);
const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl();
assert(C && "dynamic_cast target is not void pointer nor class");
CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C));
auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) {
// C++ [expr.dynamic.cast]p9:
if (!E->isGLValue()) {
// The value of a failed cast to pointer type is the null pointer value
// of the required result type.
Ptr.setNull(Info.Ctx, E->getType());
return true;
}
// A failed cast to reference type throws [...] std::bad_cast.
unsigned DiagKind;
if (!Paths && (declaresSameEntity(DynType->Type, C) ||
DynType->Type->isDerivedFrom(C)))
DiagKind = 0;
else if (!Paths || Paths->begin() == Paths->end())
DiagKind = 1;
else if (Paths->isAmbiguous(CQT))
DiagKind = 2;
else {
assert(Paths->front().Access != AS_public && "why did the cast fail?");
DiagKind = 3;
}
Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed)
<< DiagKind << Ptr.Designator.getType(Info.Ctx)
<< Info.Ctx.getRecordType(DynType->Type)
<< E->getType().getUnqualifiedType();
return false;
};
// Runtime check, phase 1:
// Walk from the base subobject towards the derived object looking for the
// target type.
for (int PathLength = Ptr.Designator.Entries.size();
PathLength >= (int)DynType->PathLength; --PathLength) {
const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength);
if (declaresSameEntity(Class, C))
return CastToDerivedClass(Info, E, Ptr, Class, PathLength);
// We can only walk across public inheritance edges.
if (PathLength > (int)DynType->PathLength &&
!isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1),
Class))
return RuntimeCheckFailed(nullptr);
}
// Runtime check, phase 2:
// Search the dynamic type for an unambiguous public base of type C.
CXXBasePaths Paths(/*FindAmbiguities=*/true,
/*RecordPaths=*/true, /*DetectVirtual=*/false);
if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) &&
Paths.front().Access == AS_public) {
// Downcast to the dynamic type...
if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength))
return false;
// ... then upcast to the chosen base class subobject.
for (CXXBasePathElement &Elem : Paths.front())
if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base))
return false;
return true;
}
// Otherwise, the runtime check fails.
return RuntimeCheckFailed(&Paths);
}
namespace {
struct StartLifetimeOfUnionMemberHandler {
EvalInfo &Info;
const Expr *LHSExpr;
const FieldDecl *Field;
bool DuringInit;
bool Failed = false;
static const AccessKinds AccessKind = AK_Assign;
typedef bool result_type;
bool failed() { return Failed; }
bool found(APValue &Subobj, QualType SubobjType) {
// We are supposed to perform no initialization but begin the lifetime of
// the object. We interpret that as meaning to do what default
// initialization of the object would do if all constructors involved were
// trivial:
// * All base, non-variant member, and array element subobjects' lifetimes
// begin
// * No variant members' lifetimes begin
// * All scalar subobjects whose lifetimes begin have indeterminate values
assert(SubobjType->isUnionType());
if (declaresSameEntity(Subobj.getUnionField(), Field)) {
// This union member is already active. If it's also in-lifetime, there's
// nothing to do.
if (Subobj.getUnionValue().hasValue())
return true;
} else if (DuringInit) {
// We're currently in the process of initializing a different union
// member. If we carried on, that initialization would attempt to
// store to an inactive union member, resulting in undefined behavior.
Info.FFDiag(LHSExpr,
diag::note_constexpr_union_member_change_during_init);
return false;
}
APValue Result;
Failed = !getDefaultInitValue(Field->getType(), Result);
Subobj.setUnion(Field, Result);
return true;
}
bool found(APSInt &Value, QualType SubobjType) {
llvm_unreachable("wrong value kind for union object");
}
bool found(APFloat &Value, QualType SubobjType) {
llvm_unreachable("wrong value kind for union object");
}
};
} // end anonymous namespace
const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind;
/// Handle a builtin simple-assignment or a call to a trivial assignment
/// operator whose left-hand side might involve a union member access. If it
/// does, implicitly start the lifetime of any accessed union elements per
/// C++20 [class.union]5.
static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr,
const LValue &LHS) {
if (LHS.InvalidBase || LHS.Designator.Invalid)
return false;
llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths;
// C++ [class.union]p5:
// define the set S(E) of subexpressions of E as follows:
unsigned PathLength = LHS.Designator.Entries.size();
for (const Expr *E = LHSExpr; E != nullptr;) {
// -- If E is of the form A.B, S(E) contains the elements of S(A)...
if (auto *ME = dyn_cast<MemberExpr>(E)) {
auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl());
// Note that we can't implicitly start the lifetime of a reference,
// so we don't need to proceed any further if we reach one.
if (!FD || FD->getType()->isReferenceType())
break;
// ... and also contains A.B if B names a union member ...
if (FD->getParent()->isUnion()) {
// ... of a non-class, non-array type, or of a class type with a
// trivial default constructor that is not deleted, or an array of
// such types.
auto *RD =
FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl();
if (!RD || RD->hasTrivialDefaultConstructor())
UnionPathLengths.push_back({PathLength - 1, FD});
}
E = ME->getBase();
--PathLength;
assert(declaresSameEntity(FD,
LHS.Designator.Entries[PathLength]
.getAsBaseOrMember().getPointer()));
// -- If E is of the form A[B] and is interpreted as a built-in array
// subscripting operator, S(E) is [S(the array operand, if any)].
} else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) {
// Step over an ArrayToPointerDecay implicit cast.
auto *Base = ASE->getBase()->IgnoreImplicit();
if (!Base->getType()->isArrayType())
break;
E = Base;
--PathLength;
} else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) {
// Step over a derived-to-base conversion.
E = ICE->getSubExpr();
if (ICE->getCastKind() == CK_NoOp)
continue;
if (ICE->getCastKind() != CK_DerivedToBase &&
ICE->getCastKind() != CK_UncheckedDerivedToBase)
break;
// Walk path backwards as we walk up from the base to the derived class.
for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) {
--PathLength;
(void)Elt;
assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(),
LHS.Designator.Entries[PathLength]
.getAsBaseOrMember().getPointer()));
}
// -- Otherwise, S(E) is empty.
} else {
break;
}
}
// Common case: no unions' lifetimes are started.
if (UnionPathLengths.empty())
return true;
// if modification of X [would access an inactive union member], an object
// of the type of X is implicitly created
CompleteObject Obj =
findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType());
if (!Obj)
return false;
for (std::pair<unsigned, const FieldDecl *> LengthAndField :
llvm::reverse(UnionPathLengths)) {
// Form a designator for the union object.
SubobjectDesignator D = LHS.Designator;
D.truncate(Info.Ctx, LHS.Base, LengthAndField.first);
bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) ==
ConstructionPhase::AfterBases;
StartLifetimeOfUnionMemberHandler StartLifetime{
Info, LHSExpr, LengthAndField.second, DuringInit};
if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime))
return false;
}
return true;
}
static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg,
CallRef Call, EvalInfo &Info,
bool NonNull = false) {
LValue LV;
// Create the parameter slot and register its destruction. For a vararg
// argument, create a temporary.
// FIXME: For calling conventions that destroy parameters in the callee,
// should we consider performing destruction when the function returns
// instead?
APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV)
: Info.CurrentCall->createTemporary(Arg, Arg->getType(),
ScopeKind::Call, LV);
if (!EvaluateInPlace(V, Info, LV, Arg))
return false;
// Passing a null pointer to an __attribute__((nonnull)) parameter results in
// undefined behavior, so is non-constant.
if (NonNull && V.isLValue() && V.isNullPointer()) {
Info.CCEDiag(Arg, diag::note_non_null_attribute_failed);
return false;
}
return true;
}
/// Evaluate the arguments to a function call.
static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call,
EvalInfo &Info, const FunctionDecl *Callee,
bool RightToLeft = false) {
bool Success = true;
llvm::SmallBitVector ForbiddenNullArgs;
if (Callee->hasAttr<NonNullAttr>()) {
ForbiddenNullArgs.resize(Args.size());
for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) {
if (!Attr->args_size()) {
ForbiddenNullArgs.set();
break;
} else
for (auto Idx : Attr->args()) {
unsigned ASTIdx = Idx.getASTIndex();
if (ASTIdx >= Args.size())
continue;
ForbiddenNullArgs[ASTIdx] = 1;
}
}
}
for (unsigned I = 0; I < Args.size(); I++) {
unsigned Idx = RightToLeft ? Args.size() - I - 1 : I;
const ParmVarDecl *PVD =
Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr;
bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx];
if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) {
// If we're checking for a potential constant expression, evaluate all
// initializers even if some of them fail.
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success;
}
/// Perform a trivial copy from Param, which is the parameter of a copy or move
/// constructor or assignment operator.
static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param,
const Expr *E, APValue &Result,
bool CopyObjectRepresentation) {
// Find the reference argument.
CallStackFrame *Frame = Info.CurrentCall;
APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param);
if (!RefValue) {
Info.FFDiag(E);
return false;
}
// Copy out the contents of the RHS object.
LValue RefLValue;
RefLValue.setFrom(Info.Ctx, *RefValue);
return handleLValueToRValueConversion(
Info, E, Param->getType().getNonReferenceType(), RefLValue, Result,
CopyObjectRepresentation);
}
/// Evaluate a function call.
static bool HandleFunctionCall(SourceLocation CallLoc,
const FunctionDecl *Callee, const LValue *This,
ArrayRef<const Expr *> Args, CallRef Call,
const Stmt *Body, EvalInfo &Info,
APValue &Result, const LValue *ResultSlot) {
if (!Info.CheckCallLimit(CallLoc))
return false;
CallStackFrame Frame(Info, CallLoc, Callee, This, Call);
// For a trivial copy or move assignment, perform an APValue copy. This is
// essential for unions, where the operations performed by the assignment
// operator cannot be represented as statements.
//
// Skip this for non-union classes with no fields; in that case, the defaulted
// copy/move does not actually read the object.
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee);
if (MD && MD->isDefaulted() &&
(MD->getParent()->isUnion() ||
(MD->isTrivial() &&
isReadByLvalueToRvalueConversion(MD->getParent())))) {
assert(This &&
(MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator()));
APValue RHSValue;
if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue,
MD->getParent()->isUnion()))
return false;
if (Info.getLangOpts().CPlusPlus20 && MD->isTrivial() &&
!HandleUnionActiveMemberChange(Info, Args[0], *This))
return false;
if (!handleAssignment(Info, Args[0], *This, MD->getThisType(),
RHSValue))
return false;
This->moveInto(Result);
return true;
} else if (MD && isLambdaCallOperator(MD)) {
// We're in a lambda; determine the lambda capture field maps unless we're
// just constexpr checking a lambda's call operator. constexpr checking is
// done before the captures have been added to the closure object (unless
// we're inferring constexpr-ness), so we don't have access to them in this
// case. But since we don't need the captures to constexpr check, we can
// just ignore them.
if (!Info.checkingPotentialConstantExpression())
MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields,
Frame.LambdaThisCaptureField);
}
StmtResult Ret = {Result, ResultSlot};
EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body);
if (ESR == ESR_Succeeded) {
if (Callee->getReturnType()->isVoidType())
return true;
Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return);
}
return ESR == ESR_Returned;
}
/// Evaluate a constructor call.
static bool HandleConstructorCall(const Expr *E, const LValue &This,
CallRef Call,
const CXXConstructorDecl *Definition,
EvalInfo &Info, APValue &Result) {
SourceLocation CallLoc = E->getExprLoc();
if (!Info.CheckCallLimit(CallLoc))
return false;
const CXXRecordDecl *RD = Definition->getParent();
if (RD->getNumVBases()) {
Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
return false;
}
EvalInfo::EvaluatingConstructorRAII EvalObj(
Info,
ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
RD->getNumBases());
CallStackFrame Frame(Info, CallLoc, Definition, &This, Call);
// FIXME: Creating an APValue just to hold a nonexistent return value is
// wasteful.
APValue RetVal;
StmtResult Ret = {RetVal, nullptr};
// If it's a delegating constructor, delegate.
if (Definition->isDelegatingConstructor()) {
CXXConstructorDecl::init_const_iterator I = Definition->init_begin();
if ((*I)->getInit()->isValueDependent()) {
if (!EvaluateDependentExpr((*I)->getInit(), Info))
return false;
} else {
FullExpressionRAII InitScope(Info);
if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) ||
!InitScope.destroy())
return false;
}
return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed;
}
// For a trivial copy or move constructor, perform an APValue copy. This is
// essential for unions (or classes with anonymous union members), where the
// operations performed by the constructor cannot be represented by
// ctor-initializers.
//
// Skip this for empty non-union classes; we should not perform an
// lvalue-to-rvalue conversion on them because their copy constructor does not
// actually read them.
if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() &&
(Definition->getParent()->isUnion() ||
(Definition->isTrivial() &&
isReadByLvalueToRvalueConversion(Definition->getParent())))) {
return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result,
Definition->getParent()->isUnion());
}
// Reserve space for the struct members.
if (!Result.hasValue()) {
if (!RD->isUnion())
Result = APValue(APValue::UninitStruct(), RD->getNumBases(),
std::distance(RD->field_begin(), RD->field_end()));
else
// A union starts with no active member.
Result = APValue((const FieldDecl*)nullptr);
}
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
// A scope for temporaries lifetime-extended by reference members.
BlockScopeRAII LifetimeExtendedScope(Info);
bool Success = true;
unsigned BasesSeen = 0;
#ifndef NDEBUG
CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin();
#endif
CXXRecordDecl::field_iterator FieldIt = RD->field_begin();
auto SkipToField = [&](FieldDecl *FD, bool Indirect) {
// We might be initializing the same field again if this is an indirect
// field initialization.
if (FieldIt == RD->field_end() ||
FieldIt->getFieldIndex() > FD->getFieldIndex()) {
assert(Indirect && "fields out of order?");
return;
}
// Default-initialize any fields with no explicit initializer.
for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) {
assert(FieldIt != RD->field_end() && "missing field?");
if (!FieldIt->isUnnamedBitfield())
Success &= getDefaultInitValue(
FieldIt->getType(),
Result.getStructField(FieldIt->getFieldIndex()));
}
++FieldIt;
};
for (const auto *I : Definition->inits()) {
LValue Subobject = This;
LValue SubobjectParent = This;
APValue *Value = &Result;
// Determine the subobject to initialize.
FieldDecl *FD = nullptr;
if (I->isBaseInitializer()) {
QualType BaseType(I->getBaseClass(), 0);
#ifndef NDEBUG
// Non-virtual base classes are initialized in the order in the class
// definition. We have already checked for virtual base classes.
assert(!BaseIt->isVirtual() && "virtual base for literal type");
assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) &&
"base class initializers not in expected order");
++BaseIt;
#endif
if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD,
BaseType->getAsCXXRecordDecl(), &Layout))
return false;
Value = &Result.getStructBase(BasesSeen++);
} else if ((FD = I->getMember())) {
if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout))
return false;
if (RD->isUnion()) {
Result = APValue(FD);
Value = &Result.getUnionValue();
} else {
SkipToField(FD, false);
Value = &Result.getStructField(FD->getFieldIndex());
}
} else if (IndirectFieldDecl *IFD = I->getIndirectMember()) {
// Walk the indirect field decl's chain to find the object to initialize,
// and make sure we've initialized every step along it.
auto IndirectFieldChain = IFD->chain();
for (auto *C : IndirectFieldChain) {
FD = cast<FieldDecl>(C);
CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent());
// Switch the union field if it differs. This happens if we had
// preceding zero-initialization, and we're now initializing a union
// subobject other than the first.
// FIXME: In this case, the values of the other subobjects are
// specified, since zero-initialization sets all padding bits to zero.
if (!Value->hasValue() ||
(Value->isUnion() && Value->getUnionField() != FD)) {
if (CD->isUnion())
*Value = APValue(FD);
else
// FIXME: This immediately starts the lifetime of all members of
// an anonymous struct. It would be preferable to strictly start
// member lifetime in initialization order.
Success &= getDefaultInitValue(Info.Ctx.getRecordType(CD), *Value);
}
// Store Subobject as its parent before updating it for the last element
// in the chain.
if (C == IndirectFieldChain.back())
SubobjectParent = Subobject;
if (!HandleLValueMember(Info, I->getInit(), Subobject, FD))
return false;
if (CD->isUnion())
Value = &Value->getUnionValue();
else {
if (C == IndirectFieldChain.front() && !RD->isUnion())
SkipToField(FD, true);
Value = &Value->getStructField(FD->getFieldIndex());
}
}
} else {
llvm_unreachable("unknown base initializer kind");
}
// Need to override This for implicit field initializers as in this case
// This refers to innermost anonymous struct/union containing initializer,
// not to currently constructed class.
const Expr *Init = I->getInit();
if (Init->isValueDependent()) {
if (!EvaluateDependentExpr(Init, Info))
return false;
} else {
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent,
isa<CXXDefaultInitExpr>(Init));
FullExpressionRAII InitScope(Info);
if (!EvaluateInPlace(*Value, Info, Subobject, Init) ||
(FD && FD->isBitField() &&
!truncateBitfieldValue(Info, Init, *Value, FD))) {
// If we're checking for a potential constant expression, evaluate all
// initializers even if some of them fail.
if (!Info.noteFailure())
return false;
Success = false;
}
}
// This is the point at which the dynamic type of the object becomes this
// class type.
if (I->isBaseInitializer() && BasesSeen == RD->getNumBases())
EvalObj.finishedConstructingBases();
}
// Default-initialize any remaining fields.
if (!RD->isUnion()) {
for (; FieldIt != RD->field_end(); ++FieldIt) {
if (!FieldIt->isUnnamedBitfield())
Success &= getDefaultInitValue(
FieldIt->getType(),
Result.getStructField(FieldIt->getFieldIndex()));
}
}
EvalObj.finishedConstructingFields();
return Success &&
EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed &&
LifetimeExtendedScope.destroy();
}
static bool HandleConstructorCall(const Expr *E, const LValue &This,
ArrayRef<const Expr*> Args,
const CXXConstructorDecl *Definition,
EvalInfo &Info, APValue &Result) {
CallScopeRAII CallScope(Info);
CallRef Call = Info.CurrentCall->createCall(Definition);
if (!EvaluateArgs(Args, Call, Info, Definition))
return false;
return HandleConstructorCall(E, This, Call, Definition, Info, Result) &&
CallScope.destroy();
}
static bool HandleDestructionImpl(EvalInfo &Info, SourceLocation CallLoc,
const LValue &This, APValue &Value,
QualType T) {
// Objects can only be destroyed while they're within their lifetimes.
// FIXME: We have no representation for whether an object of type nullptr_t
// is in its lifetime; it usually doesn't matter. Perhaps we should model it
// as indeterminate instead?
if (Value.isAbsent() && !T->isNullPtrType()) {
APValue Printable;
This.moveInto(Printable);
Info.FFDiag(CallLoc, diag::note_constexpr_destroy_out_of_lifetime)
<< Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T));
return false;
}
// Invent an expression for location purposes.
// FIXME: We shouldn't need to do this.
OpaqueValueExpr LocE(CallLoc, Info.Ctx.IntTy, VK_RValue);
// For arrays, destroy elements right-to-left.
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
uint64_t Size = CAT->getSize().getZExtValue();
QualType ElemT = CAT->getElementType();
LValue ElemLV = This;
ElemLV.addArray(Info, &LocE, CAT);
if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size))
return false;
// Ensure that we have actual array elements available to destroy; the
// destructors might mutate the value, so we can't run them on the array
// filler.
if (Size && Size > Value.getArrayInitializedElts())
expandArray(Value, Value.getArraySize() - 1);
for (; Size != 0; --Size) {
APValue &Elem = Value.getArrayInitializedElt(Size - 1);
if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) ||
!HandleDestructionImpl(Info, CallLoc, ElemLV, Elem, ElemT))
return false;
}
// End the lifetime of this array now.
Value = APValue();
return true;
}
const CXXRecordDecl *RD = T->getAsCXXRecordDecl();
if (!RD) {
if (T.isDestructedType()) {
Info.FFDiag(CallLoc, diag::note_constexpr_unsupported_destruction) << T;
return false;
}
Value = APValue();
return true;
}
if (RD->getNumVBases()) {
Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD;
return false;
}
const CXXDestructorDecl *DD = RD->getDestructor();
if (!DD && !RD->hasTrivialDestructor()) {
Info.FFDiag(CallLoc);
return false;
}
if (!DD || DD->isTrivial() ||
(RD->isAnonymousStructOrUnion() && RD->isUnion())) {
// A trivial destructor just ends the lifetime of the object. Check for
// this case before checking for a body, because we might not bother
// building a body for a trivial destructor. Note that it doesn't matter
// whether the destructor is constexpr in this case; all trivial
// destructors are constexpr.
//
// If an anonymous union would be destroyed, some enclosing destructor must
// have been explicitly defined, and the anonymous union destruction should
// have no effect.
Value = APValue();
return true;
}
if (!Info.CheckCallLimit(CallLoc))
return false;
const FunctionDecl *Definition = nullptr;
const Stmt *Body = DD->getBody(Definition);
if (!CheckConstexprFunction(Info, CallLoc, DD, Definition, Body))
return false;
CallStackFrame Frame(Info, CallLoc, Definition, &This, CallRef());
// We're now in the period of destruction of this object.
unsigned BasesLeft = RD->getNumBases();
EvalInfo::EvaluatingDestructorRAII EvalObj(
Info,
ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries});
if (!EvalObj.DidInsert) {
// C++2a [class.dtor]p19:
// the behavior is undefined if the destructor is invoked for an object
// whose lifetime has ended
// (Note that formally the lifetime ends when the period of destruction
// begins, even though certain uses of the object remain valid until the
// period of destruction ends.)
Info.FFDiag(CallLoc, diag::note_constexpr_double_destroy);
return false;
}
// FIXME: Creating an APValue just to hold a nonexistent return value is
// wasteful.
APValue RetVal;
StmtResult Ret = {RetVal, nullptr};
if (EvaluateStmt(Ret, Info, Definition->getBody()) == ESR_Failed)
return false;
// A union destructor does not implicitly destroy its members.
if (RD->isUnion())
return true;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
// We don't have a good way to iterate fields in reverse, so collect all the
// fields first and then walk them backwards.
SmallVector<FieldDecl*, 16> Fields(RD->field_begin(), RD->field_end());
for (const FieldDecl *FD : llvm::reverse(Fields)) {
if (FD->isUnnamedBitfield())
continue;
LValue Subobject = This;
if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout))
return false;
APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex());
if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
FD->getType()))
return false;
}
if (BasesLeft != 0)
EvalObj.startedDestroyingBases();
// Destroy base classes in reverse order.
for (const CXXBaseSpecifier &Base : llvm::reverse(RD->bases())) {
--BasesLeft;
QualType BaseType = Base.getType();
LValue Subobject = This;
if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD,
BaseType->getAsCXXRecordDecl(), &Layout))
return false;
APValue *SubobjectValue = &Value.getStructBase(BasesLeft);
if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue,
BaseType))
return false;
}
assert(BasesLeft == 0 && "NumBases was wrong?");
// The period of destruction ends now. The object is gone.
Value = APValue();
return true;
}
namespace {
struct DestroyObjectHandler {
EvalInfo &Info;
const Expr *E;
const LValue &This;
const AccessKinds AccessKind;
typedef bool result_type;
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
return HandleDestructionImpl(Info, E->getExprLoc(), This, Subobj,
SubobjType);
}
bool found(APSInt &Value, QualType SubobjType) {
Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
return false;
}
bool found(APFloat &Value, QualType SubobjType) {
Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem);
return false;
}
};
}
/// Perform a destructor or pseudo-destructor call on the given object, which
/// might in general not be a complete object.
static bool HandleDestruction(EvalInfo &Info, const Expr *E,
const LValue &This, QualType ThisType) {
CompleteObject Obj = findCompleteObject(Info, E, AK_Destroy, This, ThisType);
DestroyObjectHandler Handler = {Info, E, This, AK_Destroy};
return Obj && findSubobject(Info, E, Obj, This.Designator, Handler);
}
/// Destroy and end the lifetime of the given complete object.
static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc,
APValue::LValueBase LVBase, APValue &Value,
QualType T) {
// If we've had an unmodeled side-effect, we can't rely on mutable state
// (such as the object we're about to destroy) being correct.
if (Info.EvalStatus.HasSideEffects)
return false;
LValue LV;
LV.set({LVBase});
return HandleDestructionImpl(Info, Loc, LV, Value, T);
}
/// Perform a call to 'perator new' or to `__builtin_operator_new'.
static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E,
LValue &Result) {
if (Info.checkingPotentialConstantExpression() ||
Info.SpeculativeEvaluationDepth)
return false;
// This is permitted only within a call to std::allocator<T>::allocate.
auto Caller = Info.getStdAllocatorCaller("allocate");
if (!Caller) {
Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20
? diag::note_constexpr_new_untyped
: diag::note_constexpr_new);
return false;
}
QualType ElemType = Caller.ElemType;
if (ElemType->isIncompleteType() || ElemType->isFunctionType()) {
Info.FFDiag(E->getExprLoc(),
diag::note_constexpr_new_not_complete_object_type)
<< (ElemType->isIncompleteType() ? 0 : 1) << ElemType;
return false;
}
APSInt ByteSize;
if (!EvaluateInteger(E->getArg(0), ByteSize, Info))
return false;
bool IsNothrow = false;
for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) {
EvaluateIgnoredValue(Info, E->getArg(I));
IsNothrow |= E->getType()->isNothrowT();
}
CharUnits ElemSize;
if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize))
return false;
APInt Size, Remainder;
APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity());
APInt::udivrem(ByteSize, ElemSizeAP, Size, Remainder);
if (Remainder != 0) {
// This likely indicates a bug in the implementation of 'std::allocator'.
Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size)
<< ByteSize << APSInt(ElemSizeAP, true) << ElemType;
return false;
}
if (ByteSize.getActiveBits() > ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
if (IsNothrow) {
Result.setNull(Info.Ctx, E->getType());
return true;
}
Info.FFDiag(E, diag::note_constexpr_new_too_large) << APSInt(Size, true);
return false;
}
QualType AllocType = Info.Ctx.getConstantArrayType(ElemType, Size, nullptr,
ArrayType::Normal, 0);
APValue *Val = Info.createHeapAlloc(E, AllocType, Result);
*Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue());
Result.addArray(Info, E, cast<ConstantArrayType>(AllocType));
return true;
}
static bool hasVirtualDestructor(QualType T) {
if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
if (CXXDestructorDecl *DD = RD->getDestructor())
return DD->isVirtual();
return false;
}
static const FunctionDecl *getVirtualOperatorDelete(QualType T) {
if (CXXRecordDecl *RD = T->getAsCXXRecordDecl())
if (CXXDestructorDecl *DD = RD->getDestructor())
return DD->isVirtual() ? DD->getOperatorDelete() : nullptr;
return nullptr;
}
/// Check that the given object is a suitable pointer to a heap allocation that
/// still exists and is of the right kind for the purpose of a deletion.
///
/// On success, returns the heap allocation to deallocate. On failure, produces
/// a diagnostic and returns None.
static Optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E,
const LValue &Pointer,
DynAlloc::Kind DeallocKind) {
auto PointerAsString = [&] {
return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy);
};
DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>();
if (!DA) {
Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc)
<< PointerAsString();
if (Pointer.Base)
NoteLValueLocation(Info, Pointer.Base);
return None;
}
Optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA);
if (!Alloc) {
Info.FFDiag(E, diag::note_constexpr_double_delete);
return None;
}
QualType AllocType = Pointer.Base.getDynamicAllocType();
if (DeallocKind != (*Alloc)->getKind()) {
Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch)
<< DeallocKind << (*Alloc)->getKind() << AllocType;
NoteLValueLocation(Info, Pointer.Base);
return None;
}
bool Subobject = false;
if (DeallocKind == DynAlloc::New) {
Subobject = Pointer.Designator.MostDerivedPathLength != 0 ||
Pointer.Designator.isOnePastTheEnd();
} else {
Subobject = Pointer.Designator.Entries.size() != 1 ||
Pointer.Designator.Entries[0].getAsArrayIndex() != 0;
}
if (Subobject) {
Info.FFDiag(E, diag::note_constexpr_delete_subobject)
<< PointerAsString() << Pointer.Designator.isOnePastTheEnd();
return None;
}
return Alloc;
}
// Perform a call to 'operator delete' or '__builtin_operator_delete'.
bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) {
if (Info.checkingPotentialConstantExpression() ||
Info.SpeculativeEvaluationDepth)
return false;
// This is permitted only within a call to std::allocator<T>::deallocate.
if (!Info.getStdAllocatorCaller("deallocate")) {
Info.FFDiag(E->getExprLoc());
return true;
}
LValue Pointer;
if (!EvaluatePointer(E->getArg(0), Pointer, Info))
return false;
for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I)
EvaluateIgnoredValue(Info, E->getArg(I));
if (Pointer.Designator.Invalid)
return false;
// Deleting a null pointer would have no effect, but it's not permitted by
// std::allocator<T>::deallocate's contract.
if (Pointer.isNullPointer()) {
Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null);
return true;
}
if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator))
return false;
Info.HeapAllocs.erase(Pointer.Base.get<DynamicAllocLValue>());
return true;
}
//===----------------------------------------------------------------------===//
// Generic Evaluation
//===----------------------------------------------------------------------===//
namespace {
class BitCastBuffer {
// FIXME: We're going to need bit-level granularity when we support
// bit-fields.
// FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but
// we don't support a host or target where that is the case. Still, we should
// use a more generic type in case we ever do.
SmallVector<Optional<unsigned char>, 32> Bytes;
static_assert(std::numeric_limits<unsigned char>::digits >= 8,
"Need at least 8 bit unsigned char");
bool TargetIsLittleEndian;
public:
BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian)
: Bytes(Width.getQuantity()),
TargetIsLittleEndian(TargetIsLittleEndian) {}
LLVM_NODISCARD
bool readObject(CharUnits Offset, CharUnits Width,
SmallVectorImpl<unsigned char> &Output) const {
for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) {
// If a byte of an integer is uninitialized, then the whole integer is
// uninitalized.
if (!Bytes[I.getQuantity()])
return false;
Output.push_back(*Bytes[I.getQuantity()]);
}
if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
std::reverse(Output.begin(), Output.end());
return true;
}
void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) {
if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian)
std::reverse(Input.begin(), Input.end());
size_t Index = 0;
for (unsigned char Byte : Input) {
assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?");
Bytes[Offset.getQuantity() + Index] = Byte;
++Index;
}
}
size_t size() { return Bytes.size(); }
};
/// Traverse an APValue to produce an BitCastBuffer, emulating how the current
/// target would represent the value at runtime.
class APValueToBufferConverter {
EvalInfo &Info;
BitCastBuffer Buffer;
const CastExpr *BCE;
APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth,
const CastExpr *BCE)
: Info(Info),
Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()),
BCE(BCE) {}
bool visit(const APValue &Val, QualType Ty) {
return visit(Val, Ty, CharUnits::fromQuantity(0));
}
// Write out Val with type Ty into Buffer starting at Offset.
bool visit(const APValue &Val, QualType Ty, CharUnits Offset) {
assert((size_t)Offset.getQuantity() <= Buffer.size());
// As a special case, nullptr_t has an indeterminate value.
if (Ty->isNullPtrType())
return true;
// Dig through Src to find the byte at SrcOffset.
switch (Val.getKind()) {
case APValue::Indeterminate:
case APValue::None:
return true;
case APValue::Int:
return visitInt(Val.getInt(), Ty, Offset);
case APValue::Float:
return visitFloat(Val.getFloat(), Ty, Offset);
case APValue::Array:
return visitArray(Val, Ty, Offset);
case APValue::Struct:
return visitRecord(Val, Ty, Offset);
case APValue::ComplexInt:
case APValue::ComplexFloat:
case APValue::Vector:
case APValue::FixedPoint:
// FIXME: We should support these.
case APValue::Union:
case APValue::MemberPointer:
case APValue::AddrLabelDiff: {
Info.FFDiag(BCE->getBeginLoc(),
diag::note_constexpr_bit_cast_unsupported_type)
<< Ty;
return false;
}
case APValue::LValue:
llvm_unreachable("LValue subobject in bit_cast?");
}
llvm_unreachable("Unhandled APValue::ValueKind");
}
bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) {
const RecordDecl *RD = Ty->getAsRecordDecl();
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
// Visit the base classes.
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
if (!visitRecord(Val.getStructBase(I), BS.getType(),
Layout.getBaseClassOffset(BaseDecl) + Offset))
return false;
}
}
// Visit the fields.
unsigned FieldIdx = 0;
for (FieldDecl *FD : RD->fields()) {
if (FD->isBitField()) {
Info.FFDiag(BCE->getBeginLoc(),
diag::note_constexpr_bit_cast_unsupported_bitfield);
return false;
}
uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 &&
"only bit-fields can have sub-char alignment");
CharUnits FieldOffset =
Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset;
QualType FieldTy = FD->getType();
if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset))
return false;
++FieldIdx;
}
return true;
}
bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) {
const auto *CAT =
dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe());
if (!CAT)
return false;
CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType());
unsigned NumInitializedElts = Val.getArrayInitializedElts();
unsigned ArraySize = Val.getArraySize();
// First, initialize the initialized elements.
for (unsigned I = 0; I != NumInitializedElts; ++I) {
const APValue &SubObj = Val.getArrayInitializedElt(I);
if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth))
return false;
}
// Next, initialize the rest of the array using the filler.
if (Val.hasArrayFiller()) {
const APValue &Filler = Val.getArrayFiller();
for (unsigned I = NumInitializedElts; I != ArraySize; ++I) {
if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth))
return false;
}
}
return true;
}
bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) {
APSInt AdjustedVal = Val;
unsigned Width = AdjustedVal.getBitWidth();
if (Ty->isBooleanType()) {
Width = Info.Ctx.getTypeSize(Ty);
AdjustedVal = AdjustedVal.extend(Width);
}
SmallVector<unsigned char, 8> Bytes(Width / 8);
llvm::StoreIntToMemory(AdjustedVal, &*Bytes.begin(), Width / 8);
Buffer.writeObject(Offset, Bytes);
return true;
}
bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) {
APSInt AsInt(Val.bitcastToAPInt());
return visitInt(AsInt, Ty, Offset);
}
public:
static Optional<BitCastBuffer> convert(EvalInfo &Info, const APValue &Src,
const CastExpr *BCE) {
CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType());
APValueToBufferConverter Converter(Info, DstSize, BCE);
if (!Converter.visit(Src, BCE->getSubExpr()->getType()))
return None;
return Converter.Buffer;
}
};
/// Write an BitCastBuffer into an APValue.
class BufferToAPValueConverter {
EvalInfo &Info;
const BitCastBuffer &Buffer;
const CastExpr *BCE;
BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer,
const CastExpr *BCE)
: Info(Info), Buffer(Buffer), BCE(BCE) {}
// Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast
// with an invalid type, so anything left is a deficiency on our part (FIXME).
// Ideally this will be unreachable.
llvm::NoneType unsupportedType(QualType Ty) {
Info.FFDiag(BCE->getBeginLoc(),
diag::note_constexpr_bit_cast_unsupported_type)
<< Ty;
return None;
}
llvm::NoneType unrepresentableValue(QualType Ty, const APSInt &Val) {
Info.FFDiag(BCE->getBeginLoc(),
diag::note_constexpr_bit_cast_unrepresentable_value)
<< Ty << Val.toString(/*Radix=*/10);
return None;
}
Optional<APValue> visit(const BuiltinType *T, CharUnits Offset,
const EnumType *EnumSugar = nullptr) {
if (T->isNullPtrType()) {
uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0));
return APValue((Expr *)nullptr,
/*Offset=*/CharUnits::fromQuantity(NullValue),
APValue::NoLValuePath{}, /*IsNullPtr=*/true);
}
CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T);
// Work around floating point types that contain unused padding bytes. This
// is really just `long double` on x86, which is the only fundamental type
// with padding bytes.
if (T->isRealFloatingType()) {
const llvm::fltSemantics &Semantics =
Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
unsigned NumBits = llvm::APFloatBase::getSizeInBits(Semantics);
assert(NumBits % 8 == 0);
CharUnits NumBytes = CharUnits::fromQuantity(NumBits / 8);
if (NumBytes != SizeOf)
SizeOf = NumBytes;
}
SmallVector<uint8_t, 8> Bytes;
if (!Buffer.readObject(Offset, SizeOf, Bytes)) {
// If this is std::byte or unsigned char, then its okay to store an
// indeterminate value.
bool IsStdByte = EnumSugar && EnumSugar->isStdByteType();
bool IsUChar =
!EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) ||
T->isSpecificBuiltinType(BuiltinType::Char_U));
if (!IsStdByte && !IsUChar) {
QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0);
Info.FFDiag(BCE->getExprLoc(),
diag::note_constexpr_bit_cast_indet_dest)
<< DisplayType << Info.Ctx.getLangOpts().CharIsSigned;
return None;
}
return APValue::IndeterminateValue();
}
APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true);
llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size());
if (T->isIntegralOrEnumerationType()) {
Val.setIsSigned(T->isSignedIntegerOrEnumerationType());
unsigned IntWidth = Info.Ctx.getIntWidth(QualType(T, 0));
if (IntWidth != Val.getBitWidth()) {
APSInt Truncated = Val.trunc(IntWidth);
if (Truncated.extend(Val.getBitWidth()) != Val)
return unrepresentableValue(QualType(T, 0), Val);
Val = Truncated;
}
return APValue(Val);
}
if (T->isRealFloatingType()) {
const llvm::fltSemantics &Semantics =
Info.Ctx.getFloatTypeSemantics(QualType(T, 0));
return APValue(APFloat(Semantics, Val));
}
return unsupportedType(QualType(T, 0));
}
Optional<APValue> visit(const RecordType *RTy, CharUnits Offset) {
const RecordDecl *RD = RTy->getAsRecordDecl();
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
unsigned NumBases = 0;
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD))
NumBases = CXXRD->getNumBases();
APValue ResultVal(APValue::UninitStruct(), NumBases,
std::distance(RD->field_begin(), RD->field_end()));
// Visit the base classes.
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) {
for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) {
const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I];
CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl();
if (BaseDecl->isEmpty() ||
Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero())
continue;
Optional<APValue> SubObj = visitType(
BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset);
if (!SubObj)
return None;
ResultVal.getStructBase(I) = *SubObj;
}
}
// Visit the fields.
unsigned FieldIdx = 0;
for (FieldDecl *FD : RD->fields()) {
// FIXME: We don't currently support bit-fields. A lot of the logic for
// this is in CodeGen, so we need to factor it around.
if (FD->isBitField()) {
Info.FFDiag(BCE->getBeginLoc(),
diag::note_constexpr_bit_cast_unsupported_bitfield);
return None;
}
uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx);
assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0);
CharUnits FieldOffset =
CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) +
Offset;
QualType FieldTy = FD->getType();
Optional<APValue> SubObj = visitType(FieldTy, FieldOffset);
if (!SubObj)
return None;
ResultVal.getStructField(FieldIdx) = *SubObj;
++FieldIdx;
}
return ResultVal;
}
Optional<APValue> visit(const EnumType *Ty, CharUnits Offset) {
QualType RepresentationType = Ty->getDecl()->getIntegerType();
assert(!RepresentationType.isNull() &&
"enum forward decl should be caught by Sema");
const auto *AsBuiltin =
RepresentationType.getCanonicalType()->castAs<BuiltinType>();
// Recurse into the underlying type. Treat std::byte transparently as
// unsigned char.
return visit(AsBuiltin, Offset, /*EnumTy=*/Ty);
}
Optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
size_t Size = Ty->getSize().getLimitedValue();
CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
APValue ArrayValue(APValue::UninitArray(), Size, Size);
for (size_t I = 0; I != Size; ++I) {
Optional<APValue> ElementValue =
visitType(Ty->getElementType(), Offset + I * ElementWidth);
if (!ElementValue)
return None;
ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue);
}
return ArrayValue;
}
Optional<APValue> visit(const Type *Ty, CharUnits Offset) {
return unsupportedType(QualType(Ty, 0));
}
Optional<APValue> visitType(QualType Ty, CharUnits Offset) {
QualType Can = Ty.getCanonicalType();
switch (Can->getTypeClass()) {
#define TYPE(Class, Base) \
case Type::Class: \
return visit(cast<Class##Type>(Can.getTypePtr()), Offset);
#define ABSTRACT_TYPE(Class, Base)
#define NON_CANONICAL_TYPE(Class, Base) \
case Type::Class: \
llvm_unreachable("non-canonical type should be impossible!");
#define DEPENDENT_TYPE(Class, Base) \
case Type::Class: \
llvm_unreachable( \
"dependent types aren't supported in the constant evaluator!");
#define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \
case Type::Class: \
llvm_unreachable("either dependent or not canonical!");
#include "clang/AST/TypeNodes.inc"
}
llvm_unreachable("Unhandled Type::TypeClass");
}
public:
// Pull out a full value of type DstType.
static Optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer,
const CastExpr *BCE) {
BufferToAPValueConverter Converter(Info, Buffer, BCE);
return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0));
}
};
static bool checkBitCastConstexprEligibilityType(SourceLocation Loc,
QualType Ty, EvalInfo *Info,
const ASTContext &Ctx,
bool CheckingDest) {
Ty = Ty.getCanonicalType();
auto diag = [&](int Reason) {
if (Info)
Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type)
<< CheckingDest << (Reason == 4) << Reason;
return false;
};
auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) {
if (Info)
Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype)
<< NoteTy << Construct << Ty;
return false;
};
if (Ty->isUnionType())
return diag(0);
if (Ty->isPointerType())
return diag(1);
if (Ty->isMemberPointerType())
return diag(2);
if (Ty.isVolatileQualified())
return diag(3);
if (RecordDecl *Record = Ty->getAsRecordDecl()) {
if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) {
for (CXXBaseSpecifier &BS : CXXRD->bases())
if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx,
CheckingDest))
return note(1, BS.getType(), BS.getBeginLoc());
}
for (FieldDecl *FD : Record->fields()) {
if (FD->getType()->isReferenceType())
return diag(4);
if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx,
CheckingDest))
return note(0, FD->getType(), FD->getBeginLoc());
}
}
if (Ty->isArrayType() &&
!checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty),
Info, Ctx, CheckingDest))
return false;
return true;
}
static bool checkBitCastConstexprEligibility(EvalInfo *Info,
const ASTContext &Ctx,
const CastExpr *BCE) {
bool DestOK = checkBitCastConstexprEligibilityType(
BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true);
bool SourceOK = DestOK && checkBitCastConstexprEligibilityType(
BCE->getBeginLoc(),
BCE->getSubExpr()->getType(), Info, Ctx, false);
return SourceOK;
}
static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue,
APValue &SourceValue,
const CastExpr *BCE) {
assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 &&
"no host or target supports non 8-bit chars");
assert(SourceValue.isLValue() &&
"LValueToRValueBitcast requires an lvalue operand!");
if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE))
return false;
LValue SourceLValue;
APValue SourceRValue;
SourceLValue.setFrom(Info.Ctx, SourceValue);
if (!handleLValueToRValueConversion(
Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue,
SourceRValue, /*WantObjectRepresentation=*/true))
return false;
// Read out SourceValue into a char buffer.
Optional<BitCastBuffer> Buffer =
APValueToBufferConverter::convert(Info, SourceRValue, BCE);
if (!Buffer)
return false;
// Write out the buffer into a new APValue.
Optional<APValue> MaybeDestValue =
BufferToAPValueConverter::convert(Info, *Buffer, BCE);
if (!MaybeDestValue)
return false;
DestValue = std::move(*MaybeDestValue);
return true;
}
template <class Derived>
class ExprEvaluatorBase
: public ConstStmtVisitor<Derived, bool> {
private:
Derived &getDerived() { return static_cast<Derived&>(*this); }
bool DerivedSuccess(const APValue &V, const Expr *E) {
return getDerived().Success(V, E);
}
bool DerivedZeroInitialization(const Expr *E) {
return getDerived().ZeroInitialization(E);
}
// Check whether a conditional operator with a non-constant condition is a
// potential constant expression. If neither arm is a potential constant
// expression, then the conditional operator is not either.
template<typename ConditionalOperator>
void CheckPotentialConstantConditional(const ConditionalOperator *E) {
assert(Info.checkingPotentialConstantExpression());
// Speculatively evaluate both arms.
SmallVector<PartialDiagnosticAt, 8> Diag;
{
SpeculativeEvaluationRAII Speculate(Info, &Diag);
StmtVisitorTy::Visit(E->getFalseExpr());
if (Diag.empty())
return;
}
{
SpeculativeEvaluationRAII Speculate(Info, &Diag);
Diag.clear();
StmtVisitorTy::Visit(E->getTrueExpr());
if (Diag.empty())
return;
}
Error(E, diag::note_constexpr_conditional_never_const);
}
template<typename ConditionalOperator>
bool HandleConditionalOperator(const ConditionalOperator *E) {
bool BoolResult;
if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) {
if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) {
CheckPotentialConstantConditional(E);
return false;
}
if (Info.noteFailure()) {
StmtVisitorTy::Visit(E->getTrueExpr());
StmtVisitorTy::Visit(E->getFalseExpr());
}
return false;
}
Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
return StmtVisitorTy::Visit(EvalExpr);
}
protected:
EvalInfo &Info;
typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy;
typedef ExprEvaluatorBase ExprEvaluatorBaseTy;
OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
return Info.CCEDiag(E, D);
}
bool ZeroInitialization(const Expr *E) { return Error(E); }
public:
ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {}
EvalInfo &getEvalInfo() { return Info; }
/// Report an evaluation error. This should only be called when an error is
/// first discovered. When propagating an error, just return false.
bool Error(const Expr *E, diag::kind D) {
Info.FFDiag(E, D);
return false;
}
bool Error(const Expr *E) {
return Error(E, diag::note_invalid_subexpr_in_const_expr);
}
bool VisitStmt(const Stmt *) {
llvm_unreachable("Expression evaluator should not be called on stmts");
}
bool VisitExpr(const Expr *E) {
return Error(E);
}
bool VisitConstantExpr(const ConstantExpr *E) {
if (E->hasAPValueResult())
return DerivedSuccess(E->getAPValueResult(), E);
return StmtVisitorTy::Visit(E->getSubExpr());
}
bool VisitParenExpr(const ParenExpr *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitUnaryExtension(const UnaryOperator *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitUnaryPlus(const UnaryOperator *E)
{ return StmtVisitorTy::Visit(E->getSubExpr()); }
bool VisitChooseExpr(const ChooseExpr *E)
{ return StmtVisitorTy::Visit(E->getChosenSubExpr()); }
bool VisitGenericSelectionExpr(const GenericSelectionExpr *E)
{ return StmtVisitorTy::Visit(E->getResultExpr()); }
bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E)
{ return StmtVisitorTy::Visit(E->getReplacement()); }
bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) {
TempVersionRAII RAII(*Info.CurrentCall);
SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
return StmtVisitorTy::Visit(E->getExpr());
}
bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) {
TempVersionRAII RAII(*Info.CurrentCall);
// The initializer may not have been parsed yet, or might be erroneous.
if (!E->getExpr())
return Error(E);
SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope);
return StmtVisitorTy::Visit(E->getExpr());
}
bool VisitExprWithCleanups(const ExprWithCleanups *E) {
FullExpressionRAII Scope(Info);
return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy();
}
// Temporaries are registered when created, so we don't care about
// CXXBindTemporaryExpr.
bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
return StmtVisitorTy::Visit(E->getSubExpr());
}
bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 0;
return static_cast<Derived*>(this)->VisitCastExpr(E);
}
bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) {
if (!Info.Ctx.getLangOpts().CPlusPlus20)
CCEDiag(E, diag::note_constexpr_invalid_cast) << 1;
return static_cast<Derived*>(this)->VisitCastExpr(E);
}
bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) {
return static_cast<Derived*>(this)->VisitCastExpr(E);
}
bool VisitBinaryOperator(const BinaryOperator *E) {
switch (E->getOpcode()) {
default:
return Error(E);
case BO_Comma:
VisitIgnoredValue(E->getLHS());
return StmtVisitorTy::Visit(E->getRHS());
case BO_PtrMemD:
case BO_PtrMemI: {
LValue Obj;
if (!HandleMemberPointerAccess(Info, E, Obj))
return false;
APValue Result;
if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result))
return false;
return DerivedSuccess(Result, E);
}
}
}
bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) {
return StmtVisitorTy::Visit(E->getSemanticForm());
}
bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) {
// Evaluate and cache the common expression. We treat it as a temporary,
// even though it's not quite the same thing.
LValue CommonLV;
if (!Evaluate(Info.CurrentCall->createTemporary(
E->getOpaqueValue(),
getStorageType(Info.Ctx, E->getOpaqueValue()),
ScopeKind::FullExpression, CommonLV),
Info, E->getCommon()))
return false;
return HandleConditionalOperator(E);
}
bool VisitConditionalOperator(const ConditionalOperator *E) {
bool IsBcpCall = false;
// If the condition (ignoring parens) is a __builtin_constant_p call,
// the result is a constant expression if it can be folded without
// side-effects. This is an important GNU extension. See GCC PR38377
// for discussion.
if (const CallExpr *CallCE =
dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts()))
if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
IsBcpCall = true;
// Always assume __builtin_constant_p(...) ? ... : ... is a potential
// constant expression; we can't check whether it's potentially foldable.
// FIXME: We should instead treat __builtin_constant_p as non-constant if
// it would return 'false' in this mode.
if (Info.checkingPotentialConstantExpression() && IsBcpCall)
return false;
FoldConstant Fold(Info, IsBcpCall);
if (!HandleConditionalOperator(E)) {
Fold.keepDiagnostics();
return false;
}
return true;
}
bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) {
if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E))
return DerivedSuccess(*Value, E);
const Expr *Source = E->getSourceExpr();
if (!Source)
return Error(E);
if (Source == E) { // sanity checking.
assert(0 && "OpaqueValueExpr recursively refers to itself");
return Error(E);
}
return StmtVisitorTy::Visit(Source);
}
bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) {
for (const Expr *SemE : E->semantics()) {
if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) {
// FIXME: We can't handle the case where an OpaqueValueExpr is also the
// result expression: there could be two different LValues that would
// refer to the same object in that case, and we can't model that.
if (SemE == E->getResultExpr())
return Error(E);
// Unique OVEs get evaluated if and when we encounter them when
// emitting the rest of the semantic form, rather than eagerly.
if (OVE->isUnique())
continue;
LValue LV;
if (!Evaluate(Info.CurrentCall->createTemporary(
OVE, getStorageType(Info.Ctx, OVE),
ScopeKind::FullExpression, LV),
Info, OVE->getSourceExpr()))
return false;
} else if (SemE == E->getResultExpr()) {
if (!StmtVisitorTy::Visit(SemE))
return false;
} else {
if (!EvaluateIgnoredValue(Info, SemE))
return false;
}
}
return true;
}
bool VisitCallExpr(const CallExpr *E) {
APValue Result;
if (!handleCallExpr(E, Result, nullptr))
return false;
return DerivedSuccess(Result, E);
}
bool handleCallExpr(const CallExpr *E, APValue &Result,
const LValue *ResultSlot) {
CallScopeRAII CallScope(Info);
const Expr *Callee = E->getCallee()->IgnoreParens();
QualType CalleeType = Callee->getType();
const FunctionDecl *FD = nullptr;
LValue *This = nullptr, ThisVal;
auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
bool HasQualifier = false;
CallRef Call;
// Extract function decl and 'this' pointer from the callee.
if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) {
const CXXMethodDecl *Member = nullptr;
if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) {
// Explicit bound member calls, such as x.f() or p->g();
if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal))
return false;
Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl());
if (!Member)
return Error(Callee);
This = &ThisVal;
HasQualifier = ME->hasQualifier();
} else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) {
// Indirect bound member calls ('.*' or '->*').
const ValueDecl *D =
HandleMemberPointerAccess(Info, BE, ThisVal, false);
if (!D)
return false;
Member = dyn_cast<CXXMethodDecl>(D);
if (!Member)
return Error(Callee);
This = &ThisVal;
} else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) {
if (!Info.getLangOpts().CPlusPlus20)
Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor);
return EvaluateObjectArgument(Info, PDE->getBase(), ThisVal) &&
HandleDestruction(Info, PDE, ThisVal, PDE->getDestroyedType());
} else
return Error(Callee);
FD = Member;
} else if (CalleeType->isFunctionPointerType()) {
LValue CalleeLV;
if (!EvaluatePointer(Callee, CalleeLV, Info))
return false;
if (!CalleeLV.getLValueOffset().isZero())
return Error(Callee);
FD = dyn_cast_or_null<FunctionDecl>(
CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>());
if (!FD)
return Error(Callee);
// Don't call function pointers which have been cast to some other type.
// Per DR (no number yet), the caller and callee can differ in noexcept.
if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec(
CalleeType->getPointeeType(), FD->getType())) {
return Error(E);
}
// For an (overloaded) assignment expression, evaluate the RHS before the
// LHS.
auto *OCE = dyn_cast<CXXOperatorCallExpr>(E);
if (OCE && OCE->isAssignmentOp()) {
assert(Args.size() == 2 && "wrong number of arguments in assignment");
Call = Info.CurrentCall->createCall(FD);
if (!EvaluateArgs(isa<CXXMethodDecl>(FD) ? Args.slice(1) : Args, Call,
Info, FD, /*RightToLeft=*/true))
return false;
}
// Overloaded operator calls to member functions are represented as normal
// calls with '*this' as the first argument.
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
if (MD && !MD->isStatic()) {
// FIXME: When selecting an implicit conversion for an overloaded
// operator delete, we sometimes try to evaluate calls to conversion
// operators without a 'this' parameter!
if (Args.empty())
return Error(E);
if (!EvaluateObjectArgument(Info, Args[0], ThisVal))
return false;
This = &ThisVal;
Args = Args.slice(1);
} else if (MD && MD->isLambdaStaticInvoker()) {
// Map the static invoker for the lambda back to the call operator.
// Conveniently, we don't have to slice out the 'this' argument (as is
// being done for the non-static case), since a static member function
// doesn't have an implicit argument passed in.
const CXXRecordDecl *ClosureClass = MD->getParent();
assert(
ClosureClass->captures_begin() == ClosureClass->captures_end() &&
"Number of captures must be zero for conversion to function-ptr");
const CXXMethodDecl *LambdaCallOp =
ClosureClass->getLambdaCallOperator();
// Set 'FD', the function that will be called below, to the call
// operator. If the closure object represents a generic lambda, find
// the corresponding specialization of the call operator.
if (ClosureClass->isGenericLambda()) {
assert(MD->isFunctionTemplateSpecialization() &&
"A generic lambda's static-invoker function must be a "
"template specialization");
const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs();
FunctionTemplateDecl *CallOpTemplate =
LambdaCallOp->getDescribedFunctionTemplate();
void *InsertPos = nullptr;
FunctionDecl *CorrespondingCallOpSpecialization =
CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos);
assert(CorrespondingCallOpSpecialization &&
"We must always have a function call operator specialization "
"that corresponds to our static invoker specialization");
FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization);
} else
FD = LambdaCallOp;
} else if (FD->isReplaceableGlobalAllocationFunction()) {
if (FD->getDeclName().getCXXOverloadedOperator() == OO_New ||
FD->getDeclName().getCXXOverloadedOperator() == OO_Array_New) {
LValue Ptr;
if (!HandleOperatorNewCall(Info, E, Ptr))
return false;
Ptr.moveInto(Result);
return CallScope.destroy();
} else {
return HandleOperatorDeleteCall(Info, E) && CallScope.destroy();
}
}
} else
return Error(E);
// Evaluate the arguments now if we've not already done so.
if (!Call) {
Call = Info.CurrentCall->createCall(FD);
if (!EvaluateArgs(Args, Call, Info, FD))
return false;
}
SmallVector<QualType, 4> CovariantAdjustmentPath;
if (This) {
auto *NamedMember = dyn_cast<CXXMethodDecl>(FD);
if (NamedMember && NamedMember->isVirtual() && !HasQualifier) {
// Perform virtual dispatch, if necessary.
FD = HandleVirtualDispatch(Info, E, *This, NamedMember,
CovariantAdjustmentPath);
if (!FD)
return false;
} else {
// Check that the 'this' pointer points to an object of the right type.
// FIXME: If this is an assignment operator call, we may need to change
// the active union member before we check this.
if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember))
return false;
}
}
// Destructor calls are different enough that they have their own codepath.
if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) {
assert(This && "no 'this' pointer for destructor call");
return HandleDestruction(Info, E, *This,
Info.Ctx.getRecordType(DD->getParent())) &&
CallScope.destroy();
}
const FunctionDecl *Definition = nullptr;
Stmt *Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) ||
!HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Call,
Body, Info, Result, ResultSlot))
return false;
if (!CovariantAdjustmentPath.empty() &&
!HandleCovariantReturnAdjustment(Info, E, Result,
CovariantAdjustmentPath))
return false;
return CallScope.destroy();
}
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return StmtVisitorTy::Visit(E->getInitializer());
}
bool VisitInitListExpr(const InitListExpr *E) {
if (E->getNumInits() == 0)
return DerivedZeroInitialization(E);
if (E->getNumInits() == 1)
return StmtVisitorTy::Visit(E->getInit(0));
return Error(E);
}
bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
return DerivedZeroInitialization(E);
}
bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) {
return DerivedZeroInitialization(E);
}
bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) {
return DerivedZeroInitialization(E);
}
/// A member expression where the object is a prvalue is itself a prvalue.
bool VisitMemberExpr(const MemberExpr *E) {
assert(!Info.Ctx.getLangOpts().CPlusPlus11 &&
"missing temporary materialization conversion");
assert(!E->isArrow() && "missing call to bound member function?");
APValue Val;
if (!Evaluate(Val, Info, E->getBase()))
return false;
QualType BaseTy = E->getBase()->getType();
const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
if (!FD) return Error(E);
assert(!FD->getType()->isReferenceType() && "prvalue reference?");
assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
FD->getParent()->getCanonicalDecl() && "record / field mismatch");
// Note: there is no lvalue base here. But this case should only ever
// happen in C or in C++98, where we cannot be evaluating a constexpr
// constructor, which is the only case the base matters.
CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy);
SubobjectDesignator Designator(BaseTy);
Designator.addDeclUnchecked(FD);
APValue Result;
return extractSubobject(Info, E, Obj, Designator, Result) &&
DerivedSuccess(Result, E);
}
bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) {
APValue Val;
if (!Evaluate(Val, Info, E->getBase()))
return false;
if (Val.isVector()) {
SmallVector<uint32_t, 4> Indices;
E->getEncodedElementAccess(Indices);
if (Indices.size() == 1) {
// Return scalar.
return DerivedSuccess(Val.getVectorElt(Indices[0]), E);
} else {
// Construct new APValue vector.
SmallVector<APValue, 4> Elts;
for (unsigned I = 0; I < Indices.size(); ++I) {
Elts.push_back(Val.getVectorElt(Indices[I]));
}
APValue VecResult(Elts.data(), Indices.size());
return DerivedSuccess(VecResult, E);
}
}
return false;
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
break;
case CK_AtomicToNonAtomic: {
APValue AtomicVal;
// This does not need to be done in place even for class/array types:
// atomic-to-non-atomic conversion implies copying the object
// representation.
if (!Evaluate(AtomicVal, Info, E->getSubExpr()))
return false;
return DerivedSuccess(AtomicVal, E);
}
case CK_NoOp:
case CK_UserDefinedConversion:
return StmtVisitorTy::Visit(E->getSubExpr());
case CK_LValueToRValue: {
LValue LVal;
if (!EvaluateLValue(E->getSubExpr(), LVal, Info))
return false;
APValue RVal;
// Note, we use the subexpression's type in order to retain cv-qualifiers.
if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
LVal, RVal))
return false;
return DerivedSuccess(RVal, E);
}
case CK_LValueToRValueBitCast: {
APValue DestValue, SourceValue;
if (!Evaluate(SourceValue, Info, E->getSubExpr()))
return false;
if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E))
return false;
return DerivedSuccess(DestValue, E);
}
case CK_AddressSpaceConversion: {
APValue Value;
if (!Evaluate(Value, Info, E->getSubExpr()))
return false;
return DerivedSuccess(Value, E);
}
}
return Error(E);
}
bool VisitUnaryPostInc(const UnaryOperator *UO) {
return VisitUnaryPostIncDec(UO);
}
bool VisitUnaryPostDec(const UnaryOperator *UO) {
return VisitUnaryPostIncDec(UO);
}
bool VisitUnaryPostIncDec(const UnaryOperator *UO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(UO);
LValue LVal;
if (!EvaluateLValue(UO->getSubExpr(), LVal, Info))
return false;
APValue RVal;
if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(),
UO->isIncrementOp(), &RVal))
return false;
return DerivedSuccess(RVal, UO);
}
bool VisitStmtExpr(const StmtExpr *E) {
// We will have checked the full-expressions inside the statement expression
// when they were completed, and don't need to check them again now.
llvm::SaveAndRestore<bool> NotCheckingForUB(
Info.CheckingForUndefinedBehavior, false);
const CompoundStmt *CS = E->getSubStmt();
if (CS->body_empty())
return true;
BlockScopeRAII Scope(Info);
for (CompoundStmt::const_body_iterator BI = CS->body_begin(),
BE = CS->body_end();
/**/; ++BI) {
if (BI + 1 == BE) {
const Expr *FinalExpr = dyn_cast<Expr>(*BI);
if (!FinalExpr) {
Info.FFDiag((*BI)->getBeginLoc(),
diag::note_constexpr_stmt_expr_unsupported);
return false;
}
return this->Visit(FinalExpr) && Scope.destroy();
}
APValue ReturnValue;
StmtResult Result = { ReturnValue, nullptr };
EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI);
if (ESR != ESR_Succeeded) {
// FIXME: If the statement-expression terminated due to 'return',
// 'break', or 'continue', it would be nice to propagate that to
// the outer statement evaluation rather than bailing out.
if (ESR != ESR_Failed)
Info.FFDiag((*BI)->getBeginLoc(),
diag::note_constexpr_stmt_expr_unsupported);
return false;
}
}
llvm_unreachable("Return from function from the loop above.");
}
/// Visit a value which is evaluated, but whose value is ignored.
void VisitIgnoredValue(const Expr *E) {
EvaluateIgnoredValue(Info, E);
}
/// Potentially visit a MemberExpr's base expression.
void VisitIgnoredBaseExpression(const Expr *E) {
// While MSVC doesn't evaluate the base expression, it does diagnose the
// presence of side-effecting behavior.
if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx))
return;
VisitIgnoredValue(E);
}
};
} // namespace
//===----------------------------------------------------------------------===//
// Common base class for lvalue and temporary evaluation.
//===----------------------------------------------------------------------===//
namespace {
template<class Derived>
class LValueExprEvaluatorBase
: public ExprEvaluatorBase<Derived> {
protected:
LValue &Result;
bool InvalidBaseOK;
typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy;
typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy;
bool Success(APValue::LValueBase B) {
Result.set(B);
return true;
}
bool evaluatePointer(const Expr *E, LValue &Result) {
return EvaluatePointer(E, Result, this->Info, InvalidBaseOK);
}
public:
LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK)
: ExprEvaluatorBaseTy(Info), Result(Result),
InvalidBaseOK(InvalidBaseOK) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(this->Info.Ctx, V);
return true;
}
bool VisitMemberExpr(const MemberExpr *E) {
// Handle non-static data members.
QualType BaseTy;
bool EvalOK;
if (E->isArrow()) {
EvalOK = evaluatePointer(E->getBase(), Result);
BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType();
} else if (E->getBase()->isRValue()) {
assert(E->getBase()->getType()->isRecordType());
EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info);
BaseTy = E->getBase()->getType();
} else {
EvalOK = this->Visit(E->getBase());
BaseTy = E->getBase()->getType();
}
if (!EvalOK) {
if (!InvalidBaseOK)
return false;
Result.setInvalid(E);
return true;
}
const ValueDecl *MD = E->getMemberDecl();
if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) {
assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() ==
FD->getParent()->getCanonicalDecl() && "record / field mismatch");
(void)BaseTy;
if (!HandleLValueMember(this->Info, E, Result, FD))
return false;
} else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) {
if (!HandleLValueIndirectMember(this->Info, E, Result, IFD))
return false;
} else
return this->Error(E);
if (MD->getType()->isReferenceType()) {
APValue RefValue;
if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result,
RefValue))
return false;
return Success(RefValue, E);
}
return true;
}
bool VisitBinaryOperator(const BinaryOperator *E) {
switch (E->getOpcode()) {
default:
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
case BO_PtrMemD:
case BO_PtrMemI:
return HandleMemberPointerAccess(this->Info, E, Result);
}
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
if (!this->Visit(E->getSubExpr()))
return false;
// Now figure out the necessary offset to add to the base LV to get from
// the derived class to the base class.
return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(),
Result);
}
}
};
}
//===----------------------------------------------------------------------===//
// LValue Evaluation
//
// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
// function designators (in C), decl references to void objects (in C), and
// temporaries (if building with -Wno-address-of-temporary).
//
// LValue evaluation produces values comprising a base expression of one of the
// following types:
// - Declarations
// * VarDecl
// * FunctionDecl
// - Literals
// * CompoundLiteralExpr in C (and in global scope in C++)
// * StringLiteral
// * PredefinedExpr
// * ObjCStringLiteralExpr
// * ObjCEncodeExpr
// * AddrLabelExpr
// * BlockExpr
// * CallExpr for a MakeStringConstant builtin
// - typeid(T) expressions, as TypeInfoLValues
// - Locals and temporaries
// * MaterializeTemporaryExpr
// * Any Expr, with a CallIndex indicating the function in which the temporary
// was evaluated, for cases where the MaterializeTemporaryExpr is missing
// from the AST (FIXME).
// * A MaterializeTemporaryExpr that has static storage duration, with no
// CallIndex, for a lifetime-extended temporary.
// * The ConstantExpr that is currently being evaluated during evaluation of an
// immediate invocation.
// plus an offset in bytes.
//===----------------------------------------------------------------------===//
namespace {
class LValueExprEvaluator
: public LValueExprEvaluatorBase<LValueExprEvaluator> {
public:
LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) :
LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {}
bool VisitVarDecl(const Expr *E, const VarDecl *VD);
bool VisitUnaryPreIncDec(const UnaryOperator *UO);
bool VisitDeclRefExpr(const DeclRefExpr *E);
bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); }
bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E);
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
bool VisitMemberExpr(const MemberExpr *E);
bool VisitStringLiteral(const StringLiteral *E) { return Success(E); }
bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); }
bool VisitCXXTypeidExpr(const CXXTypeidExpr *E);
bool VisitCXXUuidofExpr(const CXXUuidofExpr *E);
bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E);
bool VisitUnaryDeref(const UnaryOperator *E);
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitUnaryPreInc(const UnaryOperator *UO) {
return VisitUnaryPreIncDec(UO);
}
bool VisitUnaryPreDec(const UnaryOperator *UO) {
return VisitUnaryPreIncDec(UO);
}
bool VisitBinAssign(const BinaryOperator *BO);
bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO);
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_LValueBitCast:
this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
if (!Visit(E->getSubExpr()))
return false;
Result.Designator.setInvalid();
return true;
case CK_BaseToDerived:
if (!Visit(E->getSubExpr()))
return false;
return HandleBaseToDerivedCast(Info, E, Result);
case CK_Dynamic:
if (!Visit(E->getSubExpr()))
return false;
return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
}
}
};
} // end anonymous namespace
/// Evaluate an expression as an lvalue. This can be legitimately called on
/// expressions which are not glvalues, in three cases:
/// * function designators in C, and
/// * "extern void" objects
/// * @selector() expressions in Objective-C
static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info,
bool InvalidBaseOK) {
assert(!E->isValueDependent());
assert(E->isGLValue() || E->getType()->isFunctionType() ||
E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E));
return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
}
bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
const NamedDecl *D = E->getDecl();
if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl>(D))
return Success(cast<ValueDecl>(D));
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return VisitVarDecl(E, VD);
if (const BindingDecl *BD = dyn_cast<BindingDecl>(D))
return Visit(BD->getBinding());
return Error(E);
}
bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) {
// If we are within a lambda's call operator, check whether the 'VD' referred
// to within 'E' actually represents a lambda-capture that maps to a
// data-member/field within the closure object, and if so, evaluate to the
// field or what the field refers to.
if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) &&
isa<DeclRefExpr>(E) &&
cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) {
// We don't always have a complete capture-map when checking or inferring if
// the function call operator meets the requirements of a constexpr function
// - but we don't need to evaluate the captures to determine constexprness
// (dcl.constexpr C++17).
if (Info.checkingPotentialConstantExpression())
return false;
if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) {
// Start with 'Result' referring to the complete closure object...
Result = *Info.CurrentCall->This;
// ... then update it to refer to the field of the closure object
// that represents the capture.
if (!HandleLValueMember(Info, E, Result, FD))
return false;
// And if the field is of reference type, update 'Result' to refer to what
// the field refers to.
if (FD->getType()->isReferenceType()) {
APValue RVal;
if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result,
RVal))
return false;
Result.setFrom(Info.Ctx, RVal);
}
return true;
}
}
CallStackFrame *Frame = nullptr;
unsigned Version = 0;
if (VD->hasLocalStorage()) {
// Only if a local variable was declared in the function currently being
// evaluated, do we expect to be able to find its value in the current
// frame. (Otherwise it was likely declared in an enclosing context and
// could either have a valid evaluatable value (for e.g. a constexpr
// variable) or be ill-formed (and trigger an appropriate evaluation
// diagnostic)).
CallStackFrame *CurrFrame = Info.CurrentCall;
if (CurrFrame->Callee && CurrFrame->Callee->Equals(VD->getDeclContext())) {
// Function parameters are stored in some caller's frame. (Usually the
// immediate caller, but for an inherited constructor they may be more
// distant.)
if (auto *PVD = dyn_cast<ParmVarDecl>(VD)) {
if (CurrFrame->Arguments) {
VD = CurrFrame->Arguments.getOrigParam(PVD);
Frame =
Info.getCallFrameAndDepth(CurrFrame->Arguments.CallIndex).first;
Version = CurrFrame->Arguments.Version;
}
} else {
Frame = CurrFrame;
Version = CurrFrame->getCurrentTemporaryVersion(VD);
}
}
}
if (!VD->getType()->isReferenceType()) {
if (Frame) {
Result.set({VD, Frame->Index, Version});
return true;
}
return Success(VD);
}
if (!Info.getLangOpts().CPlusPlus11) {
Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1)
<< VD << VD->getType();
Info.Note(VD->getLocation(), diag::note_declared_at);
}
APValue *V;
if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, V))
return false;
if (!V->hasValue()) {
// FIXME: Is it possible for V to be indeterminate here? If so, we should
// adjust the diagnostic to say that.
if (!Info.checkingPotentialConstantExpression())
Info.FFDiag(E, diag::note_constexpr_use_uninit_reference);
return false;
}
return Success(*V, E);
}
bool LValueExprEvaluator::VisitMaterializeTemporaryExpr(
const MaterializeTemporaryExpr *E) {
// Walk through the expression to find the materialized temporary itself.
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
const Expr *Inner =
E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
// If we passed any comma operators, evaluate their LHSs.
for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I)
if (!EvaluateIgnoredValue(Info, CommaLHSs[I]))
return false;
// A materialized temporary with static storage duration can appear within the
// result of a constant expression evaluation, so we need to preserve its
// value for use outside this evaluation.
APValue *Value;
if (E->getStorageDuration() == SD_Static) {
// FIXME: What about SD_Thread?
Value = E->getOrCreateValue(true);
*Value = APValue();
Result.set(E);
} else {
Value = &Info.CurrentCall->createTemporary(
E, E->getType(),
E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression
: ScopeKind::Block,
Result);
}
QualType Type = Inner->getType();
// Materialize the temporary itself.
if (!EvaluateInPlace(*Value, Info, Result, Inner)) {
*Value = APValue();
return false;
}
// Adjust our lvalue to refer to the desired subobject.
for (unsigned I = Adjustments.size(); I != 0; /**/) {
--I;
switch (Adjustments[I].Kind) {
case SubobjectAdjustment::DerivedToBaseAdjustment:
if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath,
Type, Result))
return false;
Type = Adjustments[I].DerivedToBase.BasePath->getType();
break;
case SubobjectAdjustment::FieldAdjustment:
if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field))
return false;
Type = Adjustments[I].Field->getType();
break;
case SubobjectAdjustment::MemberPointerAdjustment:
if (!HandleMemberPointerAccess(this->Info, Type, Result,
Adjustments[I].Ptr.RHS))
return false;
Type = Adjustments[I].Ptr.MPT->getPointeeType();
break;
}
}
return true;
}
bool
LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) &&
"lvalue compound literal in c++?");
// Defer visiting the literal until the lvalue-to-rvalue conversion. We can
// only see this when folding in C, so there's no standard to follow here.
return Success(E);
}
bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) {
TypeInfoLValue TypeInfo;
if (!E->isPotentiallyEvaluated()) {
if (E->isTypeOperand())
TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr());
else
TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr());
} else {
if (!Info.Ctx.getLangOpts().CPlusPlus20) {
Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic)
<< E->getExprOperand()->getType()
<< E->getExprOperand()->getSourceRange();
}
if (!Visit(E->getExprOperand()))
return false;
Optional<DynamicType> DynType =
ComputeDynamicType(Info, E, Result, AK_TypeId);
if (!DynType)
return false;
TypeInfo =
TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr());
}
return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType()));
}
bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) {
return Success(E->getGuidDecl());
}
bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
// Handle static data members.
if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) {
VisitIgnoredBaseExpression(E->getBase());
return VisitVarDecl(E, VD);
}
// Handle static member functions.
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) {
if (MD->isStatic()) {
VisitIgnoredBaseExpression(E->getBase());
return Success(MD);
}
}
// Handle non-static data members.
return LValueExprEvaluatorBaseTy::VisitMemberExpr(E);
}
bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
// FIXME: Deal with vectors as array subscript bases.
if (E->getBase()->getType()->isVectorType())
return Error(E);
APSInt Index;
bool Success = true;
// C++17's rules require us to evaluate the LHS first, regardless of which
// side is the base.
for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) {
if (SubExpr == E->getBase() ? !evaluatePointer(SubExpr, Result)
: !EvaluateInteger(SubExpr, Index, Info)) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success &&
HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index);
}
bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) {
return evaluatePointer(E->getSubExpr(), Result);
}
bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (!Visit(E->getSubExpr()))
return false;
// __real is a no-op on scalar lvalues.
if (E->getSubExpr()->getType()->isAnyComplexType())
HandleLValueComplexElement(Info, E, Result, E->getType(), false);
return true;
}
bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
assert(E->getSubExpr()->getType()->isAnyComplexType() &&
"lvalue __imag__ on scalar?");
if (!Visit(E->getSubExpr()))
return false;
HandleLValueComplexElement(Info, E, Result, E->getType(), true);
return true;
}
bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(UO);
if (!this->Visit(UO->getSubExpr()))
return false;
return handleIncDec(
this->Info, UO, Result, UO->getSubExpr()->getType(),
UO->isIncrementOp(), nullptr);
}
bool LValueExprEvaluator::VisitCompoundAssignOperator(
const CompoundAssignOperator *CAO) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(CAO);
bool Success = true;
// C++17 onwards require that we evaluate the RHS first.
APValue RHS;
if (!Evaluate(RHS, this->Info, CAO->getRHS())) {
if (!Info.noteFailure())
return false;
Success = false;
}
// The overall lvalue result is the result of evaluating the LHS.
if (!this->Visit(CAO->getLHS()) || !Success)
return false;
return handleCompoundAssignment(
this->Info, CAO,
Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(),
CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS);
}
bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) {
if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure())
return Error(E);
bool Success = true;
// C++17 onwards require that we evaluate the RHS first.
APValue NewVal;
if (!Evaluate(NewVal, this->Info, E->getRHS())) {
if (!Info.noteFailure())
return false;
Success = false;
}
if (!this->Visit(E->getLHS()) || !Success)
return false;
if (Info.getLangOpts().CPlusPlus20 &&
!HandleUnionActiveMemberChange(Info, E->getLHS(), Result))
return false;
return handleAssignment(this->Info, E, Result, E->getLHS()->getType(),
NewVal);
}
//===----------------------------------------------------------------------===//
// Pointer Evaluation
//===----------------------------------------------------------------------===//
/// Attempts to compute the number of bytes available at the pointer
/// returned by a function with the alloc_size attribute. Returns true if we
/// were successful. Places an unsigned number into `Result`.
///
/// This expects the given CallExpr to be a call to a function with an
/// alloc_size attribute.
static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
const CallExpr *Call,
llvm::APInt &Result) {
const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call);
assert(AllocSize && AllocSize->getElemSizeParam().isValid());
unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex();
unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType());
if (Call->getNumArgs() <= SizeArgNo)
return false;
auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) {
Expr::EvalResult ExprResult;
if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects))
return false;
Into = ExprResult.Val.getInt();
if (Into.isNegative() || !Into.isIntN(BitsInSizeT))
return false;
Into = Into.zextOrSelf(BitsInSizeT);
return true;
};
APSInt SizeOfElem;
if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem))
return false;
if (!AllocSize->getNumElemsParam().isValid()) {
Result = std::move(SizeOfElem);
return true;
}
APSInt NumberOfElems;
unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex();
if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems))
return false;
bool Overflow;
llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow);
if (Overflow)
return false;
Result = std::move(BytesAvailable);
return true;
}
/// Convenience function. LVal's base must be a call to an alloc_size
/// function.
static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx,
const LValue &LVal,
llvm::APInt &Result) {
assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
"Can't get the size of a non alloc_size function");
const auto *Base = LVal.getLValueBase().get<const Expr *>();
const CallExpr *CE = tryUnwrapAllocSizeCall(Base);
return getBytesReturnedByAllocSizeCall(Ctx, CE, Result);
}
/// Attempts to evaluate the given LValueBase as the result of a call to
/// a function with the alloc_size attribute. If it was possible to do so, this
/// function will return true, make Result's Base point to said function call,
/// and mark Result's Base as invalid.
static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base,
LValue &Result) {
if (Base.isNull())
return false;
// Because we do no form of static analysis, we only support const variables.
//
// Additionally, we can't support parameters, nor can we support static
// variables (in the latter case, use-before-assign isn't UB; in the former,
// we have no clue what they'll be assigned to).
const auto *VD =
dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>());
if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified())
return false;
const Expr *Init = VD->getAnyInitializer();
if (!Init)
return false;
const Expr *E = Init->IgnoreParens();
if (!tryUnwrapAllocSizeCall(E))
return false;
// Store E instead of E unwrapped so that the type of the LValue's base is
// what the user wanted.
Result.setInvalid(E);
QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType();
Result.addUnsizedArray(Info, E, Pointee);
return true;
}
namespace {
class PointerExprEvaluator
: public ExprEvaluatorBase<PointerExprEvaluator> {
LValue &Result;
bool InvalidBaseOK;
bool Success(const Expr *E) {
Result.set(E);
return true;
}
bool evaluateLValue(const Expr *E, LValue &Result) {
return EvaluateLValue(E, Result, Info, InvalidBaseOK);
}
bool evaluatePointer(const Expr *E, LValue &Result) {
return EvaluatePointer(E, Result, Info, InvalidBaseOK);
}
bool visitNonBuiltinCallExpr(const CallExpr *E);
public:
PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK)
: ExprEvaluatorBaseTy(info), Result(Result),
InvalidBaseOK(InvalidBaseOK) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(Info.Ctx, V);
return true;
}
bool ZeroInitialization(const Expr *E) {
Result.setNull(Info.Ctx, E->getType());
return true;
}
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitCastExpr(const CastExpr* E);
bool VisitUnaryAddrOf(const UnaryOperator *E);
bool VisitObjCStringLiteral(const ObjCStringLiteral *E)
{ return Success(E); }
bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) {
if (E->isExpressibleAsConstantInitializer())
return Success(E);
if (Info.noteFailure())
EvaluateIgnoredValue(Info, E->getSubExpr());
return Error(E);
}
bool VisitAddrLabelExpr(const AddrLabelExpr *E)
{ return Success(E); }
bool VisitCallExpr(const CallExpr *E);
bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
bool VisitBlockExpr(const BlockExpr *E) {
if (!E->getBlockDecl()->hasCaptures())
return Success(E);
return Error(E);
}
bool VisitCXXThisExpr(const CXXThisExpr *E) {
// Can't look at 'this' when checking a potential constant expression.
if (Info.checkingPotentialConstantExpression())
return false;
if (!Info.CurrentCall->This) {
if (Info.getLangOpts().CPlusPlus11)
Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit();
else
Info.FFDiag(E);
return false;
}
Result = *Info.CurrentCall->This;
// If we are inside a lambda's call operator, the 'this' expression refers
// to the enclosing '*this' object (either by value or reference) which is
// either copied into the closure object's field that represents the '*this'
// or refers to '*this'.
if (isLambdaCallOperator(Info.CurrentCall->Callee)) {
// Ensure we actually have captured 'this'. (an error will have
// been previously reported if not).
if (!Info.CurrentCall->LambdaThisCaptureField)
return false;
// Update 'Result' to refer to the data member/field of the closure object
// that represents the '*this' capture.
if (!HandleLValueMember(Info, E, Result,
Info.CurrentCall->LambdaThisCaptureField))
return false;
// If we captured '*this' by reference, replace the field with its referent.
if (Info.CurrentCall->LambdaThisCaptureField->getType()
->isPointerType()) {
APValue RVal;
if (!handleLValueToRValueConversion(Info, E, E->getType(), Result,
RVal))
return false;
Result.setFrom(Info.Ctx, RVal);
}
}
return true;
}
bool VisitCXXNewExpr(const CXXNewExpr *E);
bool VisitSourceLocExpr(const SourceLocExpr *E) {
assert(E->isStringType() && "SourceLocExpr isn't a pointer type?");
APValue LValResult = E->EvaluateInContext(
Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
Result.setFrom(Info.Ctx, LValResult);
return true;
}
// FIXME: Missing: @protocol, @selector
};
} // end anonymous namespace
static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info,
bool InvalidBaseOK) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->hasPointerRepresentation());
return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E);
}
bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() != BO_Add &&
E->getOpcode() != BO_Sub)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
const Expr *PExp = E->getLHS();
const Expr *IExp = E->getRHS();
if (IExp->getType()->isPointerType())
std::swap(PExp, IExp);
bool EvalPtrOK = evaluatePointer(PExp, Result);
if (!EvalPtrOK && !Info.noteFailure())
return false;
llvm::APSInt Offset;
if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK)
return false;
if (E->getOpcode() == BO_Sub)
negateAsSigned(Offset);
QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType();
return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset);
}
bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
return evaluateLValue(E->getSubExpr(), Result);
}
bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr *SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
break;
case CK_BitCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_AddressSpaceConversion:
if (!Visit(SubExpr))
return false;
// Bitcasts to cv void* are static_casts, not reinterpret_casts, so are
// permitted in constant expressions in C++11. Bitcasts from cv void* are
// also static_casts, but we disallow them as a resolution to DR1312.
if (!E->getType()->isVoidPointerType()) {
if (!Result.InvalidBase && !Result.Designator.Invalid &&
!Result.IsNullPtr &&
Info.Ctx.hasSameUnqualifiedType(Result.Designator.getType(Info.Ctx),
E->getType()->getPointeeType()) &&
Info.getStdAllocatorCaller("allocate")) {
// Inside a call to std::allocator::allocate and friends, we permit
// casting from void* back to cv1 T* for a pointer that points to a
// cv2 T.
} else {
Result.Designator.setInvalid();
if (SubExpr->getType()->isVoidPointerType())
CCEDiag(E, diag::note_constexpr_invalid_cast)
<< 3 << SubExpr->getType();
else
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
}
}
if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr)
ZeroInitialization(E);
return true;
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
if (!evaluatePointer(E->getSubExpr(), Result))
return false;
if (!Result.Base && Result.Offset.isZero())
return true;
// Now figure out the necessary offset to add to the base LV to get from
// the derived class to the base class.
return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()->
castAs<PointerType>()->getPointeeType(),
Result);
case CK_BaseToDerived:
if (!Visit(E->getSubExpr()))
return false;
if (!Result.Base && Result.Offset.isZero())
return true;
return HandleBaseToDerivedCast(Info, E, Result);
case CK_Dynamic:
if (!Visit(E->getSubExpr()))
return false;
return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result);
case CK_NullToPointer:
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
case CK_IntegralToPointer: {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
APValue Value;
if (!EvaluateIntegerOrLValue(SubExpr, Value, Info))
break;
if (Value.isInt()) {
unsigned Size = Info.Ctx.getTypeSize(E->getType());
uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue();
Result.Base = (Expr*)nullptr;
Result.InvalidBase = false;
Result.Offset = CharUnits::fromQuantity(N);
Result.Designator.setInvalid();
Result.IsNullPtr = false;
return true;
} else {
// Cast is of an lvalue, no need to change value.
Result.setFrom(Info.Ctx, Value);
return true;
}
}
case CK_ArrayToPointerDecay: {
if (SubExpr->isGLValue()) {
if (!evaluateLValue(SubExpr, Result))
return false;
} else {
APValue &Value = Info.CurrentCall->createTemporary(
SubExpr, SubExpr->getType(), ScopeKind::FullExpression, Result);
if (!EvaluateInPlace(Value, Info, Result, SubExpr))
return false;
}
// The result is a pointer to the first element of the array.
auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType());
if (auto *CAT = dyn_cast<ConstantArrayType>(AT))
Result.addArray(Info, E, CAT);
else
Result.addUnsizedArray(Info, E, AT->getElementType());
return true;
}
case CK_FunctionToPointerDecay:
return evaluateLValue(SubExpr, Result);
case CK_LValueToRValue: {
LValue LVal;
if (!evaluateLValue(E->getSubExpr(), LVal))
return false;
APValue RVal;
// Note, we use the subexpression's type in order to retain cv-qualifiers.
if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(),
LVal, RVal))
return InvalidBaseOK &&
evaluateLValueAsAllocSize(Info, LVal.Base, Result);
return Success(RVal, E);
}
}
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
static CharUnits GetAlignOfType(EvalInfo &Info, QualType T,
UnaryExprOrTypeTrait ExprKind) {
// C++ [expr.alignof]p3:
// When alignof is applied to a reference type, the result is the
// alignment of the referenced type.
if (const ReferenceType *Ref = T->getAs<ReferenceType>())
T = Ref->getPointeeType();
if (T.getQualifiers().hasUnaligned())
return CharUnits::One();
const bool AlignOfReturnsPreferred =
Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7;
// __alignof is defined to return the preferred alignment.
// Before 8, clang returned the preferred alignment for alignof and _Alignof
// as well.
if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred)
return Info.Ctx.toCharUnitsFromBits(
Info.Ctx.getPreferredTypeAlign(T.getTypePtr()));
// alignof and _Alignof are defined to return the ABI alignment.
else if (ExprKind == UETT_AlignOf)
return Info.Ctx.getTypeAlignInChars(T.getTypePtr());
else
llvm_unreachable("GetAlignOfType on a non-alignment ExprKind");
}
static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E,
UnaryExprOrTypeTrait ExprKind) {
E = E->IgnoreParens();
// The kinds of expressions that we have special-case logic here for
// should be kept up to date with the special checks for those
// expressions in Sema.
// alignof decl is always accepted, even if it doesn't make sense: we default
// to 1 in those cases.
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
return Info.Ctx.getDeclAlign(DRE->getDecl(),
/*RefAsPointee*/true);
if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
/*RefAsPointee*/true);
return GetAlignOfType(Info, E->getType(), ExprKind);
}
static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) {
if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>())
return Info.Ctx.getDeclAlign(VD);
if (const auto *E = Value.Base.dyn_cast<const Expr *>())
return GetAlignOfExpr(Info, E, UETT_AlignOf);
return GetAlignOfType(Info, Value.Base.getTypeInfoType(), UETT_AlignOf);
}
/// Evaluate the value of the alignment argument to __builtin_align_{up,down},
/// __builtin_is_aligned and __builtin_assume_aligned.
static bool getAlignmentArgument(const Expr *E, QualType ForType,
EvalInfo &Info, APSInt &Alignment) {
if (!EvaluateInteger(E, Alignment, Info))
return false;
if (Alignment < 0 || !Alignment.isPowerOf2()) {
Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment;
return false;
}
unsigned SrcWidth = Info.Ctx.getIntWidth(ForType);
APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1));
if (APSInt::compareValues(Alignment, MaxValue) > 0) {
Info.FFDiag(E, diag::note_constexpr_alignment_too_big)
<< MaxValue << ForType << Alignment;
return false;
}
// Ensure both alignment and source value have the same bit width so that we
// don't assert when computing the resulting value.
APSInt ExtAlignment =
APSInt(Alignment.zextOrTrunc(SrcWidth), /*isUnsigned=*/true);
assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 &&
"Alignment should not be changed by ext/trunc");
Alignment = ExtAlignment;
assert(Alignment.getBitWidth() == SrcWidth);
return true;
}
// To be clear: this happily visits unsupported builtins. Better name welcomed.
bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) {
if (ExprEvaluatorBaseTy::VisitCallExpr(E))
return true;
if (!(InvalidBaseOK && getAllocSizeAttr(E)))
return false;
Result.setInvalid(E);
QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType();
Result.addUnsizedArray(Info, E, PointeeTy);
return true;
}
bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
if (IsStringLiteralCall(E))
return Success(E);
if (unsigned BuiltinOp = E->getBuiltinCallee())
return VisitBuiltinCallExpr(E, BuiltinOp);
return visitNonBuiltinCallExpr(E);
}
// Determine if T is a character type for which we guarantee that
// sizeof(T) == 1.
static bool isOneByteCharacterType(QualType T) {
return T->isCharType() || T->isChar8Type();
}
bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
unsigned BuiltinOp) {
switch (BuiltinOp) {
case Builtin::BI__builtin_addressof:
return evaluateLValue(E->getArg(0), Result);
case Builtin::BI__builtin_assume_aligned: {
// We need to be very careful here because: if the pointer does not have the
// asserted alignment, then the behavior is undefined, and undefined
// behavior is non-constant.
if (!evaluatePointer(E->getArg(0), Result))
return false;
LValue OffsetResult(Result);
APSInt Alignment;
if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
Alignment))
return false;
CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue());
if (E->getNumArgs() > 2) {
APSInt Offset;
if (!EvaluateInteger(E->getArg(2), Offset, Info))
return false;
int64_t AdditionalOffset = -Offset.getZExtValue();
OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset);
}
// If there is a base object, then it must have the correct alignment.
if (OffsetResult.Base) {
CharUnits BaseAlignment = getBaseAlignment(Info, OffsetResult);
if (BaseAlignment < Align) {
Result.Designator.setInvalid();
// FIXME: Add support to Diagnostic for long / long long.
CCEDiag(E->getArg(0),
diag::note_constexpr_baa_insufficient_alignment) << 0
<< (unsigned)BaseAlignment.getQuantity()
<< (unsigned)Align.getQuantity();
return false;
}
}
// The offset must also have the correct alignment.
if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) {
Result.Designator.setInvalid();
(OffsetResult.Base
? CCEDiag(E->getArg(0),
diag::note_constexpr_baa_insufficient_alignment) << 1
: CCEDiag(E->getArg(0),
diag::note_constexpr_baa_value_insufficient_alignment))
<< (int)OffsetResult.Offset.getQuantity()
<< (unsigned)Align.getQuantity();
return false;
}
return true;
}
case Builtin::BI__builtin_align_up:
case Builtin::BI__builtin_align_down: {
if (!evaluatePointer(E->getArg(0), Result))
return false;
APSInt Alignment;
if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info,
Alignment))
return false;
CharUnits BaseAlignment = getBaseAlignment(Info, Result);
CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Result.Offset);
// For align_up/align_down, we can return the same value if the alignment
// is known to be greater or equal to the requested value.
if (PtrAlign.getQuantity() >= Alignment)
return true;
// The alignment could be greater than the minimum at run-time, so we cannot
// infer much about the resulting pointer value. One case is possible:
// For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we
// can infer the correct index if the requested alignment is smaller than
// the base alignment so we can perform the computation on the offset.
if (BaseAlignment.getQuantity() >= Alignment) {
assert(Alignment.getBitWidth() <= 64 &&
"Cannot handle > 64-bit address-space");
uint64_t Alignment64 = Alignment.getZExtValue();
CharUnits NewOffset = CharUnits::fromQuantity(
BuiltinOp == Builtin::BI__builtin_align_down
? llvm::alignDown(Result.Offset.getQuantity(), Alignment64)
: llvm::alignTo(Result.Offset.getQuantity(), Alignment64));
Result.adjustOffset(NewOffset - Result.Offset);
// TODO: diagnose out-of-bounds values/only allow for arrays?
return true;
}
// Otherwise, we cannot constant-evaluate the result.
Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust)
<< Alignment;
return false;
}
case Builtin::BI__builtin_operator_new:
return HandleOperatorNewCall(Info, E, Result);
case Builtin::BI__builtin_launder:
return evaluatePointer(E->getArg(0), Result);
case Builtin::BIstrchr:
case Builtin::BIwcschr:
case Builtin::BImemchr:
case Builtin::BIwmemchr:
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
LLVM_FALLTHROUGH;
case Builtin::BI__builtin_strchr:
case Builtin::BI__builtin_wcschr:
case Builtin::BI__builtin_memchr:
case Builtin::BI__builtin_char_memchr:
case Builtin::BI__builtin_wmemchr: {
if (!Visit(E->getArg(0)))
return false;
APSInt Desired;
if (!EvaluateInteger(E->getArg(1), Desired, Info))
return false;
uint64_t MaxLength = uint64_t(-1);
if (BuiltinOp != Builtin::BIstrchr &&
BuiltinOp != Builtin::BIwcschr &&
BuiltinOp != Builtin::BI__builtin_strchr &&
BuiltinOp != Builtin::BI__builtin_wcschr) {
APSInt N;
if (!EvaluateInteger(E->getArg(2), N, Info))
return false;
MaxLength = N.getExtValue();
}
// We cannot find the value if there are no candidates to match against.
if (MaxLength == 0u)
return ZeroInitialization(E);
if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
Result.Designator.Invalid)
return false;
QualType CharTy = Result.Designator.getType(Info.Ctx);
bool IsRawByte = BuiltinOp == Builtin::BImemchr ||
BuiltinOp == Builtin::BI__builtin_memchr;
assert(IsRawByte ||
Info.Ctx.hasSameUnqualifiedType(
CharTy, E->getArg(0)->getType()->getPointeeType()));
// Pointers to const void may point to objects of incomplete type.
if (IsRawByte && CharTy->isIncompleteType()) {
Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy;
return false;
}
// Give up on byte-oriented matching against multibyte elements.
// FIXME: We can compare the bytes in the correct order.
if (IsRawByte && !isOneByteCharacterType(CharTy)) {
Info.FFDiag(E, diag::note_constexpr_memchr_unsupported)
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
<< CharTy;
return false;
}
// Figure out what value we're actually looking for (after converting to
// the corresponding unsigned type if necessary).
uint64_t DesiredVal;
bool StopAtNull = false;
switch (BuiltinOp) {
case Builtin::BIstrchr:
case Builtin::BI__builtin_strchr:
// strchr compares directly to the passed integer, and therefore
// always fails if given an int that is not a char.
if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy,
E->getArg(1)->getType(),
Desired),
Desired))
return ZeroInitialization(E);
StopAtNull = true;
LLVM_FALLTHROUGH;
case Builtin::BImemchr:
case Builtin::BI__builtin_memchr:
case Builtin::BI__builtin_char_memchr:
// memchr compares by converting both sides to unsigned char. That's also
// correct for strchr if we get this far (to cope with plain char being
// unsigned in the strchr case).
DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue();
break;
case Builtin::BIwcschr:
case Builtin::BI__builtin_wcschr:
StopAtNull = true;
LLVM_FALLTHROUGH;
case Builtin::BIwmemchr:
case Builtin::BI__builtin_wmemchr:
// wcschr and wmemchr are given a wchar_t to look for. Just use it.
DesiredVal = Desired.getZExtValue();
break;
}
for (; MaxLength; --MaxLength) {
APValue Char;
if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) ||
!Char.isInt())
return false;
if (Char.getInt().getZExtValue() == DesiredVal)
return true;
if (StopAtNull && !Char.getInt())
break;
if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1))
return false;
}
// Not found: return nullptr.
return ZeroInitialization(E);
}
case Builtin::BImemcpy:
case Builtin::BImemmove:
case Builtin::BIwmemcpy:
case Builtin::BIwmemmove:
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
LLVM_FALLTHROUGH;
case Builtin::BI__builtin_memcpy:
case Builtin::BI__builtin_memmove:
case Builtin::BI__builtin_wmemcpy:
case Builtin::BI__builtin_wmemmove: {
bool WChar = BuiltinOp == Builtin::BIwmemcpy ||
BuiltinOp == Builtin::BIwmemmove ||
BuiltinOp == Builtin::BI__builtin_wmemcpy ||
BuiltinOp == Builtin::BI__builtin_wmemmove;
bool Move = BuiltinOp == Builtin::BImemmove ||
BuiltinOp == Builtin::BIwmemmove ||
BuiltinOp == Builtin::BI__builtin_memmove ||
BuiltinOp == Builtin::BI__builtin_wmemmove;
// The result of mem* is the first argument.
if (!Visit(E->getArg(0)))
return false;
LValue Dest = Result;
LValue Src;
if (!EvaluatePointer(E->getArg(1), Src, Info))
return false;
APSInt N;
if (!EvaluateInteger(E->getArg(2), N, Info))
return false;
assert(!N.isSigned() && "memcpy and friends take an unsigned size");
// If the size is zero, we treat this as always being a valid no-op.
// (Even if one of the src and dest pointers is null.)
if (!N)
return true;
// Otherwise, if either of the operands is null, we can't proceed. Don't
// try to determine the type of the copied objects, because there aren't
// any.
if (!Src.Base || !Dest.Base) {
APValue Val;
(!Src.Base ? Src : Dest).moveInto(Val);
Info.FFDiag(E, diag::note_constexpr_memcpy_null)
<< Move << WChar << !!Src.Base
<< Val.getAsString(Info.Ctx, E->getArg(0)->getType());
return false;
}
if (Src.Designator.Invalid || Dest.Designator.Invalid)
return false;
// We require that Src and Dest are both pointers to arrays of
// trivially-copyable type. (For the wide version, the designator will be
// invalid if the designated object is not a wchar_t.)
QualType T = Dest.Designator.getType(Info.Ctx);
QualType SrcT = Src.Designator.getType(Info.Ctx);
if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) {
// FIXME: Consider using our bit_cast implementation to support this.
Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T;
return false;
}
if (T->isIncompleteType()) {
Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T;
return false;
}
if (!T.isTriviallyCopyableType(Info.Ctx)) {
Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T;
return false;
}
// Figure out how many T's we're copying.
uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity();
if (!WChar) {
uint64_t Remainder;
llvm::APInt OrigN = N;
llvm::APInt::udivrem(OrigN, TSize, N, Remainder);
if (Remainder) {
Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
<< Move << WChar << 0 << T << OrigN.toString(10, /*Signed*/false)
<< (unsigned)TSize;
return false;
}
}
// Check that the copying will remain within the arrays, just so that we
// can give a more meaningful diagnostic. This implicitly also checks that
// N fits into 64 bits.
uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second;
uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second;
if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) {
Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported)
<< Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T
<< N.toString(10, /*Signed*/false);
return false;
}
uint64_t NElems = N.getZExtValue();
uint64_t NBytes = NElems * TSize;
// Check for overlap.
int Direction = 1;
if (HasSameBase(Src, Dest)) {
uint64_t SrcOffset = Src.getLValueOffset().getQuantity();
uint64_t DestOffset = Dest.getLValueOffset().getQuantity();
if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) {
// Dest is inside the source region.
if (!Move) {
Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
return false;
}
// For memmove and friends, copy backwards.
if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) ||
!HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1))
return false;
Direction = -1;
} else if (!Move && SrcOffset >= DestOffset &&
SrcOffset - DestOffset < NBytes) {
// Src is inside the destination region for memcpy: invalid.
Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar;
return false;
}
}
while (true) {
APValue Val;
// FIXME: Set WantObjectRepresentation to true if we're copying a
// char-like type?
if (!handleLValueToRValueConversion(Info, E, T, Src, Val) ||
!handleAssignment(Info, E, Dest, T, Val))
return false;
// Do not iterate past the last element; if we're copying backwards, that
// might take us off the start of the array.
if (--NElems == 0)
return true;
if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) ||
!HandleLValueArrayAdjustment(Info, E, Dest, T, Direction))
return false;
}
}
default:
break;
}
return visitNonBuiltinCallExpr(E);
}
static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
APValue &Result, const InitListExpr *ILE,
QualType AllocType);
static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
APValue &Result,
const CXXConstructExpr *CCE,
QualType AllocType);
bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
if (!Info.getLangOpts().CPlusPlus20)
Info.CCEDiag(E, diag::note_constexpr_new);
// We cannot speculatively evaluate a delete expression.
if (Info.SpeculativeEvaluationDepth)
return false;
FunctionDecl *OperatorNew = E->getOperatorNew();
bool IsNothrow = false;
bool IsPlacement = false;
if (OperatorNew->isReservedGlobalPlacementOperator() &&
Info.CurrentCall->isStdFunction() && !E->isArray()) {
// FIXME Support array placement new.
assert(E->getNumPlacementArgs() == 1);
if (!EvaluatePointer(E->getPlacementArg(0), Result, Info))
return false;
if (Result.Designator.Invalid)
return false;
IsPlacement = true;
} else if (!OperatorNew->isReplaceableGlobalAllocationFunction()) {
Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
<< isa<CXXMethodDecl>(OperatorNew) << OperatorNew;
return false;
} else if (E->getNumPlacementArgs()) {
// The only new-placement list we support is of the form (std::nothrow).
//
// FIXME: There is no restriction on this, but it's not clear that any
// other form makes any sense. We get here for cases such as:
//
// new (std::align_val_t{N}) X(int)
//
// (which should presumably be valid only if N is a multiple of
// alignof(int), and in any case can't be deallocated unless N is
// alignof(X) and X has new-extended alignment).
if (E->getNumPlacementArgs() != 1 ||
!E->getPlacementArg(0)->getType()->isNothrowT())
return Error(E, diag::note_constexpr_new_placement);
LValue Nothrow;
if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info))
return false;
IsNothrow = true;
}
const Expr *Init = E->getInitializer();
const InitListExpr *ResizedArrayILE = nullptr;
const CXXConstructExpr *ResizedArrayCCE = nullptr;
bool ValueInit = false;
QualType AllocType = E->getAllocatedType();
if (Optional<const Expr*> ArraySize = E->getArraySize()) {
const Expr *Stripped = *ArraySize;
for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Stripped);
Stripped = ICE->getSubExpr())
if (ICE->getCastKind() != CK_NoOp &&
ICE->getCastKind() != CK_IntegralCast)
break;
llvm::APSInt ArrayBound;
if (!EvaluateInteger(Stripped, ArrayBound, Info))
return false;
// C++ [expr.new]p9:
// The expression is erroneous if:
// -- [...] its value before converting to size_t [or] applying the
// second standard conversion sequence is less than zero
if (ArrayBound.isSigned() && ArrayBound.isNegative()) {
if (IsNothrow)
return ZeroInitialization(E);
Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative)
<< ArrayBound << (*ArraySize)->getSourceRange();
return false;
}
// -- its value is such that the size of the allocated object would
// exceed the implementation-defined limit
if (ConstantArrayType::getNumAddressingBits(Info.Ctx, AllocType,
ArrayBound) >
ConstantArrayType::getMaxSizeBits(Info.Ctx)) {
if (IsNothrow)
return ZeroInitialization(E);
Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_large)
<< ArrayBound << (*ArraySize)->getSourceRange();
return false;
}
// -- the new-initializer is a braced-init-list and the number of
// array elements for which initializers are provided [...]
// exceeds the number of elements to initialize
if (!Init) {
// No initialization is performed.
} else if (isa<CXXScalarValueInitExpr>(Init) ||
isa<ImplicitValueInitExpr>(Init)) {
ValueInit = true;
} else if (auto *CCE = dyn_cast<CXXConstructExpr>(Init)) {
ResizedArrayCCE = CCE;
} else {
auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType());
assert(CAT && "unexpected type for array initializer");
unsigned Bits =
std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
llvm::APInt InitBound = CAT->getSize().zextOrSelf(Bits);
llvm::APInt AllocBound = ArrayBound.zextOrSelf(Bits);
if (InitBound.ugt(AllocBound)) {
if (IsNothrow)
return ZeroInitialization(E);
Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small)
<< AllocBound.toString(10, /*Signed=*/false)
<< InitBound.toString(10, /*Signed=*/false)
<< (*ArraySize)->getSourceRange();
return false;
}
// If the sizes differ, we must have an initializer list, and we need
// special handling for this case when we initialize.
if (InitBound != AllocBound)
ResizedArrayILE = cast<InitListExpr>(Init);
}
AllocType = Info.Ctx.getConstantArrayType(AllocType, ArrayBound, nullptr,
ArrayType::Normal, 0);
} else {
assert(!AllocType->isArrayType() &&
"array allocation with non-array new");
}
APValue *Val;
if (IsPlacement) {
AccessKinds AK = AK_Construct;
struct FindObjectHandler {
EvalInfo &Info;
const Expr *E;
QualType AllocType;
const AccessKinds AccessKind;
APValue *Value;
typedef bool result_type;
bool failed() { return false; }
bool found(APValue &Subobj, QualType SubobjType) {
// FIXME: Reject the cases where [basic.life]p8 would not permit the
// old name of the object to be used to name the new object.
if (!Info.Ctx.hasSameUnqualifiedType(SubobjType, AllocType)) {
Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type) <<
SubobjType << AllocType;
return false;
}
Value = &Subobj;
return true;
}
bool found(APSInt &Value, QualType SubobjType) {
Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
return false;
}
bool found(APFloat &Value, QualType SubobjType) {
Info.FFDiag(E, diag::note_constexpr_construct_complex_elem);
return false;
}
} Handler = {Info, E, AllocType, AK, nullptr};
CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType);
if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler))
return false;
Val = Handler.Value;
// [basic.life]p1:
// The lifetime of an object o of type T ends when [...] the storage
// which the object occupies is [...] reused by an object that is not
// nested within o (6.6.2).
*Val = APValue();
} else {
// Perform the allocation and obtain a pointer to the resulting object.
Val = Info.createHeapAlloc(E, AllocType, Result);
if (!Val)
return false;
}
if (ValueInit) {
ImplicitValueInitExpr VIE(AllocType);
if (!EvaluateInPlace(*Val, Info, Result, &VIE))
return false;
} else if (ResizedArrayILE) {
if (!EvaluateArrayNewInitList(Info, Result, *Val, ResizedArrayILE,
AllocType))
return false;
} else if (ResizedArrayCCE) {
if (!EvaluateArrayNewConstructExpr(Info, Result, *Val, ResizedArrayCCE,
AllocType))
return false;
} else if (Init) {
if (!EvaluateInPlace(*Val, Info, Result, Init))
return false;
} else if (!getDefaultInitValue(AllocType, *Val)) {
return false;
}
// Array new returns a pointer to the first element, not a pointer to the
// array.
if (auto *AT = AllocType->getAsArrayTypeUnsafe())
Result.addArray(Info, E, cast<ConstantArrayType>(AT));
return true;
}
//===----------------------------------------------------------------------===//
// Member Pointer Evaluation
//===----------------------------------------------------------------------===//
namespace {
class MemberPointerExprEvaluator
: public ExprEvaluatorBase<MemberPointerExprEvaluator> {
MemberPtr &Result;
bool Success(const ValueDecl *D) {
Result = MemberPtr(D);
return true;
}
public:
MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result)
: ExprEvaluatorBaseTy(Info), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result.setFrom(V);
return true;
}
bool ZeroInitialization(const Expr *E) {
return Success((const ValueDecl*)nullptr);
}
bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryAddrOf(const UnaryOperator *E);
};
} // end anonymous namespace
static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isMemberPointerType());
return MemberPointerExprEvaluator(Info, Result).Visit(E);
}
bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_NullToMemberPointer:
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
case CK_BaseToDerivedMemberPointer: {
if (!Visit(E->getSubExpr()))
return false;
if (E->path_empty())
return true;
// Base-to-derived member pointer casts store the path in derived-to-base
// order, so iterate backwards. The CXXBaseSpecifier also provides us with
// the wrong end of the derived->base arc, so stagger the path by one class.
typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter;
for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin());
PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl();
if (!Result.castToDerived(Derived))
return Error(E);
}
const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass();
if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl()))
return Error(E);
return true;
}
case CK_DerivedToBaseMemberPointer:
if (!Visit(E->getSubExpr()))
return false;
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end(); PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "memptr cast through vbase");
const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
if (!Result.castToBase(Base))
return Error(E);
}
return true;
}
}
bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
// C++11 [expr.unary.op]p3 has very strict rules on how the address of a
// member can be formed.
return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl());
}
//===----------------------------------------------------------------------===//
// Record Evaluation
//===----------------------------------------------------------------------===//
namespace {
class RecordExprEvaluator
: public ExprEvaluatorBase<RecordExprEvaluator> {
const LValue &This;
APValue &Result;
public:
RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result)
: ExprEvaluatorBaseTy(info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
return ZeroInitialization(E, E->getType());
}
bool ZeroInitialization(const Expr *E, QualType T);
bool VisitCallExpr(const CallExpr *E) {
return handleCallExpr(E, Result, &This);
}
bool VisitCastExpr(const CastExpr *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitCXXConstructExpr(E, E->getType());
}
bool VisitLambdaExpr(const LambdaExpr *E);
bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T);
bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E);
bool VisitBinCmp(const BinaryOperator *E);
};
}
/// Perform zero-initialization on an object of non-union class type.
/// C++11 [dcl.init]p5:
/// To zero-initialize an object or reference of type T means:
/// [...]
/// -- if T is a (possibly cv-qualified) non-union class type,
/// each non-static data member and each base-class subobject is
/// zero-initialized
static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E,
const RecordDecl *RD,
const LValue &This, APValue &Result) {
assert(!RD->isUnion() && "Expected non-union class type");
const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD);
Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0,
std::distance(RD->field_begin(), RD->field_end()));
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
if (CD) {
unsigned Index = 0;
for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(),
End = CD->bases_end(); I != End; ++I, ++Index) {
const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl();
LValue Subobject = This;
if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout))
return false;
if (!HandleClassZeroInitialization(Info, E, Base, Subobject,
Result.getStructBase(Index)))
return false;
}
}
for (const auto *I : RD->fields()) {
// -- if T is a reference type, no initialization is performed.
if (I->isUnnamedBitfield() || I->getType()->isReferenceType())
continue;
LValue Subobject = This;
if (!HandleLValueMember(Info, E, Subobject, I, &Layout))
return false;
ImplicitValueInitExpr VIE(I->getType());
if (!EvaluateInPlace(
Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE))
return false;
}
return true;
}
bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) {
const RecordDecl *RD = T->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
if (RD->isUnion()) {
// C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the
// object's first non-static named data member is zero-initialized
RecordDecl::field_iterator I = RD->field_begin();
while (I != RD->field_end() && (*I)->isUnnamedBitfield())
++I;
if (I == RD->field_end()) {
Result = APValue((const FieldDecl*)nullptr);
return true;
}
LValue Subobject = This;
if (!HandleLValueMember(Info, E, Subobject, *I))
return false;
Result = APValue(*I);
ImplicitValueInitExpr VIE(I->getType());
return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE);
}
if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) {
Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD;
return false;
}
return HandleClassZeroInitialization(Info, E, RD, This, Result);
}
bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ConstructorConversion:
return Visit(E->getSubExpr());
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase: {
APValue DerivedObject;
if (!Evaluate(DerivedObject, Info, E->getSubExpr()))
return false;
if (!DerivedObject.isStruct())
return Error(E->getSubExpr());
// Derived-to-base rvalue conversion: just slice off the derived part.
APValue *Value = &DerivedObject;
const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl();
for (CastExpr::path_const_iterator PathI = E->path_begin(),
PathE = E->path_end(); PathI != PathE; ++PathI) {
assert(!(*PathI)->isVirtual() && "record rvalue with virtual base");
const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl();
Value = &Value->getStructBase(getBaseIndex(RD, Base));
RD = Base;
}
Result = *Value;
return true;
}
}
}
bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
if (E->isTransparent())
return Visit(E->getInit(0));
const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD);
auto *CXXRD = dyn_cast<CXXRecordDecl>(RD);
EvalInfo::EvaluatingConstructorRAII EvalObj(
Info,
ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries},
CXXRD && CXXRD->getNumBases());
if (RD->isUnion()) {
const FieldDecl *Field = E->getInitializedFieldInUnion();
Result = APValue(Field);
if (!Field)
return true;
// If the initializer list for a union does not contain any elements, the
// first element of the union is value-initialized.
// FIXME: The element should be initialized from an initializer list.
// Is this difference ever observable for initializer lists which
// we don't build?
ImplicitValueInitExpr VIE(Field->getType());
const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE;
LValue Subobject = This;
if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout))
return false;
// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
isa<CXXDefaultInitExpr>(InitExpr));
if (EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr)) {
if (Field->isBitField())
return truncateBitfieldValue(Info, InitExpr, Result.getUnionValue(),
Field);
return true;
}
return false;
}
if (!Result.hasValue())
Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0,
std::distance(RD->field_begin(), RD->field_end()));
unsigned ElementNo = 0;
bool Success = true;
// Initialize base classes.
if (CXXRD && CXXRD->getNumBases()) {
for (const auto &Base : CXXRD->bases()) {
assert(ElementNo < E->getNumInits() && "missing init for base class");
const Expr *Init = E->getInit(ElementNo);
LValue Subobject = This;
if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base))
return false;
APValue &FieldVal = Result.getStructBase(ElementNo);
if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) {
if (!Info.noteFailure())
return false;
Success = false;
}
++ElementNo;
}
EvalObj.finishedConstructingBases();
}
// Initialize members.
for (const auto *Field : RD->fields()) {
// Anonymous bit-fields are not considered members of the class for
// purposes of aggregate initialization.
if (Field->isUnnamedBitfield())
continue;
LValue Subobject = This;
bool HaveInit = ElementNo < E->getNumInits();
// FIXME: Diagnostics here should point to the end of the initializer
// list, not the start.
if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E,
Subobject, Field, &Layout))
return false;
// Perform an implicit value-initialization for members beyond the end of
// the initializer list.
ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType());
const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE;
// Temporarily override This, in case there's a CXXDefaultInitExpr in here.
ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This,
isa<CXXDefaultInitExpr>(Init));
APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) ||
(Field->isBitField() && !truncateBitfieldValue(Info, Init,
FieldVal, Field))) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
EvalObj.finishedConstructingFields();
return Success;
}
bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
QualType T) {
// Note that E's type is not necessarily the type of our class here; we might
// be initializing an array element instead.
const CXXConstructorDecl *FD = E->getConstructor();
if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false;
bool ZeroInit = E->requiresZeroInitialization();
if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) {
// If we've already performed zero-initialization, we're already done.
if (Result.hasValue())
return true;
if (ZeroInit)
return ZeroInitialization(E, T);
return getDefaultInitValue(T, Result);
}
const FunctionDecl *Definition = nullptr;
auto Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
return false;
// Avoid materializing a temporary for an elidable copy/move constructor.
if (E->isElidable() && !ZeroInit)
if (const MaterializeTemporaryExpr *ME
= dyn_cast<MaterializeTemporaryExpr>(E->getArg(0)))
return Visit(ME->getSubExpr());
if (ZeroInit && !ZeroInitialization(E, T))
return false;
auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs());
return HandleConstructorCall(E, This, Args,
cast<CXXConstructorDecl>(Definition), Info,
Result);
}
bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr(
const CXXInheritedCtorInitExpr *E) {
if (!Info.CurrentCall) {
assert(Info.checkingPotentialConstantExpression());
return false;
}
const CXXConstructorDecl *FD = E->getConstructor();
if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl())
return false;
const FunctionDecl *Definition = nullptr;
auto Body = FD->getBody(Definition);
if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body))
return false;
return HandleConstructorCall(E, This, Info.CurrentCall->Arguments,
cast<CXXConstructorDecl>(Definition), Info,
Result);
}
bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
const CXXStdInitializerListExpr *E) {
const ConstantArrayType *ArrayType =
Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
LValue Array;
if (!EvaluateLValue(E->getSubExpr(), Array, Info))
return false;
// Get a pointer to the first element of the array.
Array.addArray(Info, E, ArrayType);
auto InvalidType = [&] {
Info.FFDiag(E, diag::note_constexpr_unsupported_layout)
<< E->getType();
return false;
};
// FIXME: Perform the checks on the field types in SemaInit.
RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
RecordDecl::field_iterator Field = Record->field_begin();
if (Field == Record->field_end())
return InvalidType();
// Start pointer.
if (!Field->getType()->isPointerType() ||
!Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType()))
return InvalidType();
// FIXME: What if the initializer_list type has base classes, etc?
Result = APValue(APValue::UninitStruct(), 0, 2);
Array.moveInto(Result.getStructField(0));
if (++Field == Record->field_end())
return InvalidType();
if (Field->getType()->isPointerType() &&
Info.Ctx.hasSameType(Field->getType()->getPointeeType(),
ArrayType->getElementType())) {
// End pointer.
if (!HandleLValueArrayAdjustment(Info, E, Array,
ArrayType->getElementType(),
ArrayType->getSize().getZExtValue()))
return false;
Array.moveInto(Result.getStructField(1));
} else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
// Length.
Result.getStructField(1) = APValue(APSInt(ArrayType->getSize()));
else
return InvalidType();
if (++Field != Record->field_end())
return InvalidType();
return true;
}
bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) {
const CXXRecordDecl *ClosureClass = E->getLambdaClass();
if (ClosureClass->isInvalidDecl())
return false;
const size_t NumFields =
std::distance(ClosureClass->field_begin(), ClosureClass->field_end());
assert(NumFields == (size_t)std::distance(E->capture_init_begin(),
E->capture_init_end()) &&
"The number of lambda capture initializers should equal the number of "
"fields within the closure type");
Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields);
// Iterate through all the lambda's closure object's fields and initialize
// them.
auto *CaptureInitIt = E->capture_init_begin();
const LambdaCapture *CaptureIt = ClosureClass->captures_begin();
bool Success = true;
const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass);
for (const auto *Field : ClosureClass->fields()) {
assert(CaptureInitIt != E->capture_init_end());
// Get the initializer for this field
Expr *const CurFieldInit = *CaptureInitIt++;
// If there is no initializer, either this is a VLA or an error has
// occurred.
if (!CurFieldInit)
return Error(E);
LValue Subobject = This;
if (!HandleLValueMember(Info, E, Subobject, Field, &Layout))
return false;
APValue &FieldVal = Result.getStructField(Field->getFieldIndex());
if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) {
if (!Info.keepEvaluatingAfterFailure())
return false;
Success = false;
}
++CaptureIt;
}
return Success;
}
static bool EvaluateRecord(const Expr *E, const LValue &This,
APValue &Result, EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isRecordType() &&
"can't evaluate expression as a record rvalue");
return RecordExprEvaluator(Info, This, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Temporary Evaluation
//
// Temporaries are represented in the AST as rvalues, but generally behave like
// lvalues. The full-object of which the temporary is a subobject is implicitly
// materialized so that a reference can bind to it.
//===----------------------------------------------------------------------===//
namespace {
class TemporaryExprEvaluator
: public LValueExprEvaluatorBase<TemporaryExprEvaluator> {
public:
TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) :
LValueExprEvaluatorBaseTy(Info, Result, false) {}
/// Visit an expression which constructs the value of this temporary.
bool VisitConstructExpr(const Expr *E) {
APValue &Value = Info.CurrentCall->createTemporary(
E, E->getType(), ScopeKind::FullExpression, Result);
return EvaluateInPlace(Value, Info, Result, E);
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return LValueExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ConstructorConversion:
return VisitConstructExpr(E->getSubExpr());
}
}
bool VisitInitListExpr(const InitListExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCallExpr(const CallExpr *E) {
return VisitConstructExpr(E);
}
bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) {
return VisitConstructExpr(E);
}
bool VisitLambdaExpr(const LambdaExpr *E) {
return VisitConstructExpr(E);
}
};
} // end anonymous namespace
/// Evaluate an expression of record type as a temporary.
static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isRecordType());
return TemporaryExprEvaluator(Info, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Vector Evaluation
//===----------------------------------------------------------------------===//
namespace {
class VectorExprEvaluator
: public ExprEvaluatorBase<VectorExprEvaluator> {
APValue &Result;
public:
VectorExprEvaluator(EvalInfo &info, APValue &Result)
: ExprEvaluatorBaseTy(info), Result(Result) {}
bool Success(ArrayRef<APValue> V, const Expr *E) {
assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements());
// FIXME: remove this APValue copy.
Result = APValue(V.data(), V.size());
return true;
}
bool Success(const APValue &V, const Expr *E) {
assert(V.isVector());
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E);
bool VisitUnaryReal(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
bool VisitCastExpr(const CastExpr* E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
// FIXME: Missing: unary -, unary ~, conditional operator (for GNU
// conditional select), shufflevector, ExtVectorElementExpr
};
} // end anonymous namespace
static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue");
return VectorExprEvaluator(Info, Result).Visit(E);
}
bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) {
const VectorType *VTy = E->getType()->castAs<VectorType>();
unsigned NElts = VTy->getNumElements();
const Expr *SE = E->getSubExpr();
QualType SETy = SE->getType();
switch (E->getCastKind()) {
case CK_VectorSplat: {
APValue Val = APValue();
if (SETy->isIntegerType()) {
APSInt IntResult;
if (!EvaluateInteger(SE, IntResult, Info))
return false;
Val = APValue(std::move(IntResult));
} else if (SETy->isRealFloatingType()) {
APFloat FloatResult(0.0);
if (!EvaluateFloat(SE, FloatResult, Info))
return false;
Val = APValue(std::move(FloatResult));
} else {
return Error(E);
}
// Splat and create vector APValue.
SmallVector<APValue, 4> Elts(NElts, Val);
return Success(Elts, E);
}
case CK_BitCast: {
// Evaluate the operand into an APInt we can extract from.
llvm::APInt SValInt;
if (!EvalAndBitcastToAPInt(Info, SE, SValInt))
return false;
// Extract the elements
QualType EltTy = VTy->getElementType();
unsigned EltSize = Info.Ctx.getTypeSize(EltTy);
bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian();
SmallVector<APValue, 4> Elts;
if (EltTy->isRealFloatingType()) {
const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy);
unsigned FloatEltSize = EltSize;
if (&Sem == &APFloat::x87DoubleExtended())
FloatEltSize = 80;
for (unsigned i = 0; i < NElts; i++) {
llvm::APInt Elt;
if (BigEndian)
Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize);
else
Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize);
Elts.push_back(APValue(APFloat(Sem, Elt)));
}
} else if (EltTy->isIntegerType()) {
for (unsigned i = 0; i < NElts; i++) {
llvm::APInt Elt;
if (BigEndian)
Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize);
else
Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize);
Elts.push_back(APValue(APSInt(Elt, !EltTy->isSignedIntegerType())));
}
} else {
return Error(E);
}
return Success(Elts, E);
}
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
}
bool
VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
const VectorType *VT = E->getType()->castAs<VectorType>();
unsigned NumInits = E->getNumInits();
unsigned NumElements = VT->getNumElements();
QualType EltTy = VT->getElementType();
SmallVector<APValue, 4> Elements;
// The number of initializers can be less than the number of
// vector elements. For OpenCL, this can be due to nested vector
// initialization. For GCC compatibility, missing trailing elements
// should be initialized with zeroes.
unsigned CountInits = 0, CountElts = 0;
while (CountElts < NumElements) {
// Handle nested vector initialization.
if (CountInits < NumInits
&& E->getInit(CountInits)->getType()->isVectorType()) {
APValue v;
if (!EvaluateVector(E->getInit(CountInits), v, Info))
return Error(E);
unsigned vlen = v.getVectorLength();
for (unsigned j = 0; j < vlen; j++)
Elements.push_back(v.getVectorElt(j));
CountElts += vlen;
} else if (EltTy->isIntegerType()) {
llvm::APSInt sInt(32);
if (CountInits < NumInits) {
if (!EvaluateInteger(E->getInit(CountInits), sInt, Info))
return false;
} else // trailing integer zero.
sInt = Info.Ctx.MakeIntValue(0, EltTy);
Elements.push_back(APValue(sInt));
CountElts++;
} else {
llvm::APFloat f(0.0);
if (CountInits < NumInits) {
if (!EvaluateFloat(E->getInit(CountInits), f, Info))
return false;
} else // trailing float zero.
f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
Elements.push_back(APValue(f));
CountElts++;
}
CountInits++;
}
return Success(Elements, E);
}
bool
VectorExprEvaluator::ZeroInitialization(const Expr *E) {
const auto *VT = E->getType()->castAs<VectorType>();
QualType EltTy = VT->getElementType();
APValue ZeroElement;
if (EltTy->isIntegerType())
ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
else
ZeroElement =
APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
return Success(Elements, E);
}
bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
VisitIgnoredValue(E->getSubExpr());
return ZeroInitialization(E);
}
bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
BinaryOperatorKind Op = E->getOpcode();
assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp &&
"Operation not supported on vector types");
if (Op == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
Expr *LHS = E->getLHS();
Expr *RHS = E->getRHS();
assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() &&
"Must both be vector types");
// Checking JUST the types are the same would be fine, except shifts don't
// need to have their types be the same (since you always shift by an int).
assert(LHS->getType()->castAs<VectorType>()->getNumElements() ==
E->getType()->castAs<VectorType>()->getNumElements() &&
RHS->getType()->castAs<VectorType>()->getNumElements() ==
E->getType()->castAs<VectorType>()->getNumElements() &&
"All operands must be the same size.");
APValue LHSValue;
APValue RHSValue;
bool LHSOK = Evaluate(LHSValue, Info, LHS);
if (!LHSOK && !Info.noteFailure())
return false;
if (!Evaluate(RHSValue, Info, RHS) || !LHSOK)
return false;
if (!handleVectorVectorBinOp(Info, E, Op, LHSValue, RHSValue))
return false;
return Success(LHSValue, E);
}
//===----------------------------------------------------------------------===//
// Array Evaluation
//===----------------------------------------------------------------------===//
namespace {
class ArrayExprEvaluator
: public ExprEvaluatorBase<ArrayExprEvaluator> {
const LValue &This;
APValue &Result;
public:
ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result)
: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
assert(V.isArray() && "expected array");
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
const ConstantArrayType *CAT =
Info.Ctx.getAsConstantArrayType(E->getType());
if (!CAT) {
if (E->getType()->isIncompleteArrayType()) {
// We can be asked to zero-initialize a flexible array member; this
// is represented as an ImplicitValueInitExpr of incomplete array
// type. In this case, the array has zero elements.
Result = APValue(APValue::UninitArray(), 0, 0);
return true;
}
// FIXME: We could handle VLAs here.
return Error(E);
}
Result = APValue(APValue::UninitArray(), 0,
CAT->getSize().getZExtValue());
if (!Result.hasArrayFiller()) return true;
// Zero-initialize all elements.
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
ImplicitValueInitExpr VIE(CAT->getElementType());
return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE);
}
bool VisitCallExpr(const CallExpr *E) {
return handleCallExpr(E, Result, &This);
}
bool VisitInitListExpr(const InitListExpr *E,
QualType AllocType = QualType());
bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E);
bool VisitCXXConstructExpr(const CXXConstructExpr *E,
const LValue &Subobject,
APValue *Value, QualType Type);
bool VisitStringLiteral(const StringLiteral *E,
QualType AllocType = QualType()) {
expandStringLiteral(Info, E, Result, AllocType);
return true;
}
};
} // end anonymous namespace
static bool EvaluateArray(const Expr *E, const LValue &This,
APValue &Result, EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue");
return ArrayExprEvaluator(Info, This, Result).Visit(E);
}
static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This,
APValue &Result, const InitListExpr *ILE,
QualType AllocType) {
assert(!ILE->isValueDependent());
assert(ILE->isRValue() && ILE->getType()->isArrayType() &&
"not an array rvalue");
return ArrayExprEvaluator(Info, This, Result)
.VisitInitListExpr(ILE, AllocType);
}
static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This,
APValue &Result,
const CXXConstructExpr *CCE,
QualType AllocType) {
assert(!CCE->isValueDependent());
assert(CCE->isRValue() && CCE->getType()->isArrayType() &&
"not an array rvalue");
return ArrayExprEvaluator(Info, This, Result)
.VisitCXXConstructExpr(CCE, This, &Result, AllocType);
}
// Return true iff the given array filler may depend on the element index.
static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) {
// For now, just allow non-class value-initialization and initialization
// lists comprised of them.
if (isa<ImplicitValueInitExpr>(FillerExpr))
return false;
if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) {
for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) {
if (MaybeElementDependentArrayFiller(ILE->getInit(I)))
return true;
}
return false;
}
return true;
}
bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E,
QualType AllocType) {
const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(
AllocType.isNull() ? E->getType() : AllocType);
if (!CAT)
return Error(E);
// C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...]
// an appropriately-typed string literal enclosed in braces.
if (E->isStringLiteralInit()) {
auto *SL = dyn_cast<StringLiteral>(E->getInit(0)->IgnoreParens());
// FIXME: Support ObjCEncodeExpr here once we support it in
// ArrayExprEvaluator generally.
if (!SL)
return Error(E);
return VisitStringLiteral(SL, AllocType);
}
bool Success = true;
assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) &&
"zero-initialized array shouldn't have any initialized elts");
APValue Filler;
if (Result.isArray() && Result.hasArrayFiller())
Filler = Result.getArrayFiller();
unsigned NumEltsToInit = E->getNumInits();
unsigned NumElts = CAT->getSize().getZExtValue();
const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr;
// If the initializer might depend on the array index, run it for each
// array element.
if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr))
NumEltsToInit = NumElts;
LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: "
<< NumEltsToInit << ".\n");
Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts);
// If the array was previously zero-initialized, preserve the
// zero-initialized values.
if (Filler.hasValue()) {
for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I)
Result.getArrayInitializedElt(I) = Filler;
if (Result.hasArrayFiller())
Result.getArrayFiller() = Filler;
}
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
for (unsigned Index = 0; Index != NumEltsToInit; ++Index) {
const Expr *Init =
Index < E->getNumInits() ? E->getInit(Index) : FillerExpr;
if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
Info, Subobject, Init) ||
!HandleLValueArrayAdjustment(Info, Init, Subobject,
CAT->getElementType(), 1)) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
if (!Result.hasArrayFiller())
return Success;
// If we get here, we have a trivial filler, which we can just evaluate
// once and splat over the rest of the array elements.
assert(FillerExpr && "no array filler for incomplete init list");
return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject,
FillerExpr) && Success;
}
bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
LValue CommonLV;
if (E->getCommonExpr() &&
!Evaluate(Info.CurrentCall->createTemporary(
E->getCommonExpr(),
getStorageType(Info.Ctx, E->getCommonExpr()),
ScopeKind::FullExpression, CommonLV),
Info, E->getCommonExpr()->getSourceExpr()))
return false;
auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
uint64_t Elements = CAT->getSize().getZExtValue();
Result = APValue(APValue::UninitArray(), Elements, Elements);
LValue Subobject = This;
Subobject.addArray(Info, E, CAT);
bool Success = true;
for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) {
if (!EvaluateInPlace(Result.getArrayInitializedElt(Index),
Info, Subobject, E->getSubExpr()) ||
!HandleLValueArrayAdjustment(Info, E, Subobject,
CAT->getElementType(), 1)) {
if (!Info.noteFailure())
return false;
Success = false;
}
}
return Success;
}
bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) {
return VisitCXXConstructExpr(E, This, &Result, E->getType());
}
bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
const LValue &Subobject,
APValue *Value,
QualType Type) {
bool HadZeroInit = Value->hasValue();
if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
unsigned N = CAT->getSize().getZExtValue();
// Preserve the array filler if we had prior zero-initialization.
APValue Filler =
HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller()
: APValue();
*Value = APValue(APValue::UninitArray(), N, N);
if (HadZeroInit)
for (unsigned I = 0; I != N; ++I)
Value->getArrayInitializedElt(I) = Filler;
// Initialize the elements.
LValue ArrayElt = Subobject;
ArrayElt.addArray(Info, E, CAT);
for (unsigned I = 0; I != N; ++I)
if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I),
CAT->getElementType()) ||
!HandleLValueArrayAdjustment(Info, E, ArrayElt,
CAT->getElementType(), 1))
return false;
return true;
}
if (!Type->isRecordType())
return Error(E);
return RecordExprEvaluator(Info, Subobject, *Value)
.VisitCXXConstructExpr(E, Type);
}
//===----------------------------------------------------------------------===//
// Integer Evaluation
//
// As a GNU extension, we support casting pointers to sufficiently-wide integer
// types and back in constant folding. Integer values are thus represented
// either as an integer-valued APValue, or as an lvalue-valued APValue.
//===----------------------------------------------------------------------===//
namespace {
class IntExprEvaluator
: public ExprEvaluatorBase<IntExprEvaluator> {
APValue &Result;
public:
IntExprEvaluator(EvalInfo &info, APValue &result)
: ExprEvaluatorBaseTy(info), Result(result) {}
bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() &&
"Invalid evaluation result.");
assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(SI);
return true;
}
bool Success(const llvm::APSInt &SI, const Expr *E) {
return Success(SI, E, Result);
}
bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(APSInt(I));
Result.getInt().setIsUnsigned(
E->getType()->isUnsignedIntegerOrEnumerationType());
return true;
}
bool Success(const llvm::APInt &I, const Expr *E) {
return Success(I, E, Result);
}
bool Success(uint64_t Value, const Expr *E, APValue &Result) {
assert(E->getType()->isIntegralOrEnumerationType() &&
"Invalid evaluation result.");
Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
return true;
}
bool Success(uint64_t Value, const Expr *E) {
return Success(Value, E, Result);
}
bool Success(CharUnits Size, const Expr *E) {
return Success(Size.getQuantity(), E);
}
bool Success(const APValue &V, const Expr *E) {
if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) {
Result = V;
return true;
}
return Success(V.getInt(), E);
}
bool ZeroInitialization(const Expr *E) { return Success(0, E); }
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitIntegerLiteral(const IntegerLiteral *E) {
return Success(E->getValue(), E);
}
bool VisitCharacterLiteral(const CharacterLiteral *E) {
return Success(E->getValue(), E);
}
bool CheckReferencedDecl(const Expr *E, const Decl *D);
bool VisitDeclRefExpr(const DeclRefExpr *E) {
if (CheckReferencedDecl(E, E->getDecl()))
return true;
return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
}
bool VisitMemberExpr(const MemberExpr *E) {
if (CheckReferencedDecl(E, E->getMemberDecl())) {
VisitIgnoredBaseExpression(E->getBase());
return true;
}
return ExprEvaluatorBaseTy::VisitMemberExpr(E);
}
bool VisitCallExpr(const CallExpr *E);
bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitOffsetOfExpr(const OffsetOfExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitCastExpr(const CastExpr* E);
bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E);
bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
return Success(E->getValue(), E);
}
bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) {
return Success(E->getValue(), E);
}
bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) {
if (Info.ArrayInitIndex == uint64_t(-1)) {
// We were asked to evaluate this subexpression independent of the
// enclosing ArrayInitLoopExpr. We can't do that.
Info.FFDiag(E);
return false;
}
return Success(Info.ArrayInitIndex, E);
}
// Note, GNU defines __null as an integer, not a pointer.
bool VisitGNUNullExpr(const GNUNullExpr *E) {
return ZeroInitialization(E);
}
bool VisitTypeTraitExpr(const TypeTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) {
return Success(E->getValue(), E);
}
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E);
bool VisitSizeOfPackExpr(const SizeOfPackExpr *E);
bool VisitSourceLocExpr(const SourceLocExpr *E);
bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E);
bool VisitRequiresExpr(const RequiresExpr *E);
// FIXME: Missing: array subscript of vector, member of vector
};
class FixedPointExprEvaluator
: public ExprEvaluatorBase<FixedPointExprEvaluator> {
APValue &Result;
public:
FixedPointExprEvaluator(EvalInfo &info, APValue &result)
: ExprEvaluatorBaseTy(info), Result(result) {}
bool Success(const llvm::APInt &I, const Expr *E) {
return Success(
APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E);
}
bool Success(uint64_t Value, const Expr *E) {
return Success(
APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E);
}
bool Success(const APValue &V, const Expr *E) {
return Success(V.getFixedPoint(), E);
}
bool Success(const APFixedPoint &V, const Expr *E) {
assert(E->getType()->isFixedPointType() && "Invalid evaluation result.");
assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(V);
return true;
}
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitFixedPointLiteral(const FixedPointLiteral *E) {
return Success(E->getValue(), E);
}
bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
};
} // end anonymous namespace
/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
/// produce either the integer value or a pointer.
///
/// GCC has a heinous extension which folds casts between pointer types and
/// pointer-sized integral types. We support this by allowing the evaluation of
/// an integer rvalue to produce a pointer (represented as an lvalue) instead.
/// Some simple arithmetic on such values is supported (they are treated much
/// like char*).
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType());
return IntExprEvaluator(Info, Result).Visit(E);
}
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) {
assert(!E->isValueDependent());
APValue Val;
if (!EvaluateIntegerOrLValue(E, Val, Info))
return false;
if (!Val.isInt()) {
// FIXME: It would be better to produce the diagnostic for casting
// a pointer to an integer.
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
Result = Val.getInt();
return true;
}
bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) {
APValue Evaluated = E->EvaluateInContext(
Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr());
return Success(Evaluated, E);
}
static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
if (E->getType()->isFixedPointType()) {
APValue Val;
if (!FixedPointExprEvaluator(Info, Val).Visit(E))
return false;
if (!Val.isFixedPoint())
return false;
Result = Val.getFixedPoint();
return true;
}
return false;
}
static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
if (E->getType()->isIntegerType()) {
auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType());
APSInt Val;
if (!EvaluateInteger(E, Val, Info))
return false;
Result = APFixedPoint(Val, FXSema);
return true;
} else if (E->getType()->isFixedPointType()) {
return EvaluateFixedPoint(E, Result, Info);
}
return false;
}
/// Check whether the given declaration can be directly converted to an integral
/// rvalue. If not, no diagnostic is produced; there are other things we can
/// try.
bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
// Enums are integer constant exprs.
if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) {
// Check for signedness/width mismatches between E type and ECD value.
bool SameSign = (ECD->getInitVal().isSigned()
== E->getType()->isSignedIntegerOrEnumerationType());
bool SameWidth = (ECD->getInitVal().getBitWidth()
== Info.Ctx.getIntWidth(E->getType()));
if (SameSign && SameWidth)
return Success(ECD->getInitVal(), E);
else {
// Get rid of mismatch (otherwise Success assertions will fail)
// by computing a new value matching the type of E.
llvm::APSInt Val = ECD->getInitVal();
if (!SameSign)
Val.setIsSigned(!ECD->getInitVal().isSigned());
if (!SameWidth)
Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType()));
return Success(Val, E);
}
}
return false;
}
/// Values returned by __builtin_classify_type, chosen to match the values
/// produced by GCC's builtin.
enum class GCCTypeClass {
None = -1,
Void = 0,
Integer = 1,
// GCC reserves 2 for character types, but instead classifies them as
// integers.
Enum = 3,
Bool = 4,
Pointer = 5,
// GCC reserves 6 for references, but appears to never use it (because
// expressions never have reference type, presumably).
PointerToDataMember = 7,
RealFloat = 8,
Complex = 9,
// GCC reserves 10 for functions, but does not use it since GCC version 6 due
// to decay to pointer. (Prior to version 6 it was only used in C++ mode).
// GCC claims to reserve 11 for pointers to member functions, but *actually*
// uses 12 for that purpose, same as for a class or struct. Maybe it
// internally implements a pointer to member as a struct? Who knows.
PointerToMemberFunction = 12, // Not a bug, see above.
ClassOrStruct = 12,
Union = 13,
// GCC reserves 14 for arrays, but does not use it since GCC version 6 due to
// decay to pointer. (Prior to version 6 it was only used in C++ mode).
// GCC reserves 15 for strings, but actually uses 5 (pointer) for string
// literals.
};
/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
/// as GCC.
static GCCTypeClass
EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) {
assert(!T->isDependentType() && "unexpected dependent type");
QualType CanTy = T.getCanonicalType();
const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy);
switch (CanTy->getTypeClass()) {
#define TYPE(ID, BASE)
#define DEPENDENT_TYPE(ID, BASE) case Type::ID:
#define NON_CANONICAL_TYPE(ID, BASE) case Type::ID:
#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID:
#include "clang/AST/TypeNodes.inc"
case Type::Auto:
case Type::DeducedTemplateSpecialization:
llvm_unreachable("unexpected non-canonical or dependent type");
case Type::Builtin:
switch (BT->getKind()) {
#define BUILTIN_TYPE(ID, SINGLETON_ID)
#define SIGNED_TYPE(ID, SINGLETON_ID) \
case BuiltinType::ID: return GCCTypeClass::Integer;
#define FLOATING_TYPE(ID, SINGLETON_ID) \
case BuiltinType::ID: return GCCTypeClass::RealFloat;
#define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \
case BuiltinType::ID: break;
#include "clang/AST/BuiltinTypes.def"
case BuiltinType::Void:
return GCCTypeClass::Void;
case BuiltinType::Bool:
return GCCTypeClass::Bool;
case BuiltinType::Char_U:
case BuiltinType::UChar:
case BuiltinType::WChar_U:
case BuiltinType::Char8:
case BuiltinType::Char16:
case BuiltinType::Char32:
case BuiltinType::UShort:
case BuiltinType::UInt:
case BuiltinType::ULong:
case BuiltinType::ULongLong:
case BuiltinType::UInt128:
return GCCTypeClass::Integer;
case BuiltinType::UShortAccum:
case BuiltinType::UAccum:
case BuiltinType::ULongAccum:
case BuiltinType::UShortFract:
case BuiltinType::UFract:
case BuiltinType::ULongFract:
case BuiltinType::SatUShortAccum:
case BuiltinType::SatUAccum:
case BuiltinType::SatULongAccum:
case BuiltinType::SatUShortFract:
case BuiltinType::SatUFract:
case BuiltinType::SatULongFract:
return GCCTypeClass::None;
case BuiltinType::NullPtr:
case BuiltinType::ObjCId:
case BuiltinType::ObjCClass:
case BuiltinType::ObjCSel:
#define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \
case BuiltinType::Id:
#include "clang/Basic/OpenCLImageTypes.def"
#define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \
case BuiltinType::Id:
#include "clang/Basic/OpenCLExtensionTypes.def"
case BuiltinType::OCLSampler:
case BuiltinType::OCLEvent:
case BuiltinType::OCLClkEvent:
case BuiltinType::OCLQueue:
case BuiltinType::OCLReserveID:
#define SVE_TYPE(Name, Id, SingletonId) \
case BuiltinType::Id:
#include "clang/Basic/AArch64SVEACLETypes.def"
#define PPC_VECTOR_TYPE(Name, Id, Size) \
case BuiltinType::Id:
#include "clang/Basic/PPCTypes.def"
#define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id:
#include "clang/Basic/RISCVVTypes.def"
return GCCTypeClass::None;
case BuiltinType::Dependent:
llvm_unreachable("unexpected dependent type");
};
llvm_unreachable("unexpected placeholder type");
case Type::Enum:
return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer;
case Type::Pointer:
case Type::ConstantArray:
case Type::VariableArray:
case Type::IncompleteArray:
case Type::FunctionNoProto:
case Type::FunctionProto:
return GCCTypeClass::Pointer;
case Type::MemberPointer:
return CanTy->isMemberDataPointerType()
? GCCTypeClass::PointerToDataMember
: GCCTypeClass::PointerToMemberFunction;
case Type::Complex:
return GCCTypeClass::Complex;
case Type::Record:
return CanTy->isUnionType() ? GCCTypeClass::Union
: GCCTypeClass::ClassOrStruct;
case Type::Atomic:
// GCC classifies _Atomic T the same as T.
return EvaluateBuiltinClassifyType(
CanTy->castAs<AtomicType>()->getValueType(), LangOpts);
case Type::BlockPointer:
case Type::Vector:
case Type::ExtVector:
case Type::ConstantMatrix:
case Type::ObjCObject:
case Type::ObjCInterface:
case Type::ObjCObjectPointer:
case Type::Pipe:
case Type::ExtInt:
// GCC classifies vectors as None. We follow its lead and classify all
// other types that don't fit into the regular classification the same way.
return GCCTypeClass::None;
case Type::LValueReference:
case Type::RValueReference:
llvm_unreachable("invalid type for expression");
}
llvm_unreachable("unexpected type class");
}
/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
/// as GCC.
static GCCTypeClass
EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) {
// If no argument was supplied, default to None. This isn't
// ideal, however it is what gcc does.
if (E->getNumArgs() == 0)
return GCCTypeClass::None;
// FIXME: Bizarrely, GCC treats a call with more than one argument as not
// being an ICE, but still folds it to a constant using the type of the first
// argument.
return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts);
}
/// EvaluateBuiltinConstantPForLValue - Determine the result of
/// __builtin_constant_p when applied to the given pointer.
///
/// A pointer is only "constant" if it is null (or a pointer cast to integer)
/// or it points to the first character of a string literal.
static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) {
APValue::LValueBase Base = LV.getLValueBase();
if (Base.isNull()) {
// A null base is acceptable.
return true;
} else if (const Expr *E = Base.dyn_cast<const Expr *>()) {
if (!isa<StringLiteral>(E))
return false;
return LV.getLValueOffset().isZero();
} else if (Base.is<TypeInfoLValue>()) {
// Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to
// evaluate to true.
return true;
} else {
// Any other base is not constant enough for GCC.
return false;
}
}
/// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to
/// GCC as we can manage.
static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) {
// This evaluation is not permitted to have side-effects, so evaluate it in
// a speculative evaluation context.
SpeculativeEvaluationRAII SpeculativeEval(Info);
// Constant-folding is always enabled for the operand of __builtin_constant_p
// (even when the enclosing evaluation context otherwise requires a strict
// language-specific constant expression).
FoldConstant Fold(Info, true);
QualType ArgType = Arg->getType();
// __builtin_constant_p always has one operand. The rules which gcc follows
// are not precisely documented, but are as follows:
//
// - If the operand is of integral, floating, complex or enumeration type,
// and can be folded to a known value of that type, it returns 1.
// - If the operand can be folded to a pointer to the first character
// of a string literal (or such a pointer cast to an integral type)
// or to a null pointer or an integer cast to a pointer, it returns 1.
//
// Otherwise, it returns 0.
//
// FIXME: GCC also intends to return 1 for literals of aggregate types, but
// its support for this did not work prior to GCC 9 and is not yet well
// understood.
if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() ||
ArgType->isAnyComplexType() || ArgType->isPointerType() ||
ArgType->isNullPtrType()) {
APValue V;
if (!::EvaluateAsRValue(Info, Arg, V) || Info.EvalStatus.HasSideEffects) {
Fold.keepDiagnostics();
return false;
}
// For a pointer (possibly cast to integer), there are special rules.
if (V.getKind() == APValue::LValue)
return EvaluateBuiltinConstantPForLValue(V);
// Otherwise, any constant value is good enough.
return V.hasValue();
}
// Anything else isn't considered to be sufficiently constant.
return false;
}
/// Retrieves the "underlying object type" of the given expression,
/// as used by __builtin_object_size.
static QualType getObjectType(APValue::LValueBase B) {
if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) {
if (const VarDecl *VD = dyn_cast<VarDecl>(D))
return VD->getType();
} else if (const Expr *E = B.dyn_cast<const Expr*>()) {
if (isa<CompoundLiteralExpr>(E))
return E->getType();
} else if (B.is<TypeInfoLValue>()) {
return B.getTypeInfoType();
} else if (B.is<DynamicAllocLValue>()) {
return B.getDynamicAllocType();
}
return QualType();
}
/// A more selective version of E->IgnoreParenCasts for
/// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only
/// to change the type of E.
/// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo`
///
/// Always returns an RValue with a pointer representation.
static const Expr *ignorePointerCastsAndParens(const Expr *E) {
assert(E->isRValue() && E->getType()->hasPointerRepresentation());
auto *NoParens = E->IgnoreParens();
auto *Cast = dyn_cast<CastExpr>(NoParens);
if (Cast == nullptr)
return NoParens;
// We only conservatively allow a few kinds of casts, because this code is
// inherently a simple solution that seeks to support the common case.
auto CastKind = Cast->getCastKind();
if (CastKind != CK_NoOp && CastKind != CK_BitCast &&
CastKind != CK_AddressSpaceConversion)
return NoParens;
auto *SubExpr = Cast->getSubExpr();
if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue())
return NoParens;
return ignorePointerCastsAndParens(SubExpr);
}
/// Checks to see if the given LValue's Designator is at the end of the LValue's
/// record layout. e.g.
/// struct { struct { int a, b; } fst, snd; } obj;
/// obj.fst // no
/// obj.snd // yes
/// obj.fst.a // no
/// obj.fst.b // no
/// obj.snd.a // no
/// obj.snd.b // yes
///
/// Please note: this function is specialized for how __builtin_object_size
/// views "objects".
///
/// If this encounters an invalid RecordDecl or otherwise cannot determine the
/// correct result, it will always return true.
static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
assert(!LVal.Designator.Invalid);
auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) {
const RecordDecl *Parent = FD->getParent();
Invalid = Parent->isInvalidDecl();
if (Invalid || Parent->isUnion())
return true;
const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent);
return FD->getFieldIndex() + 1 == Layout.getFieldCount();
};
auto &Base = LVal.getLValueBase();
if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) {
if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(FD, Invalid))
return Invalid;
} else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) {
for (auto *FD : IFD->chain()) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid))
return Invalid;
}
}
}
unsigned I = 0;
QualType BaseType = getType(Base);
if (LVal.Designator.FirstEntryIsAnUnsizedArray) {
// If we don't know the array bound, conservatively assume we're looking at
// the final array element.
++I;
if (BaseType->isIncompleteArrayType())
BaseType = Ctx.getAsArrayType(BaseType)->getElementType();
else
BaseType = BaseType->castAs<PointerType>()->getPointeeType();
}
for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) {
const auto &Entry = LVal.Designator.Entries[I];
if (BaseType->isArrayType()) {
// Because __builtin_object_size treats arrays as objects, we can ignore
// the index iff this is the last array in the Designator.
if (I + 1 == E)
return true;
const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
uint64_t Index = Entry.getAsArrayIndex();
if (Index + 1 != CAT->getSize())
return false;
BaseType = CAT->getElementType();
} else if (BaseType->isAnyComplexType()) {
const auto *CT = BaseType->castAs<ComplexType>();
uint64_t Index = Entry.getAsArrayIndex();
if (Index != 1)
return false;
BaseType = CT->getElementType();
} else if (auto *FD = getAsField(Entry)) {
bool Invalid;
if (!IsLastOrInvalidFieldDecl(FD, Invalid))
return Invalid;
BaseType = FD->getType();
} else {
assert(getAsBaseClass(Entry) && "Expecting cast to a base class");
return false;
}
}
return true;
}
/// Tests to see if the LValue has a user-specified designator (that isn't
/// necessarily valid). Note that this always returns 'true' if the LValue has
/// an unsized array as its first designator entry, because there's currently no
/// way to tell if the user typed *foo or foo[0].
static bool refersToCompleteObject(const LValue &LVal) {
if (LVal.Designator.Invalid)
return false;
if (!LVal.Designator.Entries.empty())
return LVal.Designator.isMostDerivedAnUnsizedArray();
if (!LVal.InvalidBase)
return true;
// If `E` is a MemberExpr, then the first part of the designator is hiding in
// the LValueBase.
const auto *E = LVal.Base.dyn_cast<const Expr *>();
return !E || !isa<MemberExpr>(E);
}
/// Attempts to detect a user writing into a piece of memory that's impossible
/// to figure out the size of by just using types.
static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) {
const SubobjectDesignator &Designator = LVal.Designator;
// Notes:
// - Users can only write off of the end when we have an invalid base. Invalid
// bases imply we don't know where the memory came from.
// - We used to be a bit more aggressive here; we'd only be conservative if
// the array at the end was flexible, or if it had 0 or 1 elements. This
// broke some common standard library extensions (PR30346), but was
// otherwise seemingly fine. It may be useful to reintroduce this behavior
// with some sort of list. OTOH, it seems that GCC is always
// conservative with the last element in structs (if it's an array), so our
// current behavior is more compatible than an explicit list approach would
// be.
return LVal.InvalidBase &&
Designator.Entries.size() == Designator.MostDerivedPathLength &&
Designator.MostDerivedIsArrayElement &&
isDesignatorAtObjectEnd(Ctx, LVal);
}
/// Converts the given APInt to CharUnits, assuming the APInt is unsigned.
/// Fails if the conversion would cause loss of precision.
static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int,
CharUnits &Result) {
auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max();
if (Int.ugt(CharUnitsMax))
return false;
Result = CharUnits::fromQuantity(Int.getZExtValue());
return true;
}
/// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will
/// determine how many bytes exist from the beginning of the object to either
/// the end of the current subobject, or the end of the object itself, depending
/// on what the LValue looks like + the value of Type.
///
/// If this returns false, the value of Result is undefined.
static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc,
unsigned Type, const LValue &LVal,
CharUnits &EndOffset) {
bool DetermineForCompleteObject = refersToCompleteObject(LVal);
auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) {
if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType())
return false;
return HandleSizeof(Info, ExprLoc, Ty, Result);
};
// We want to evaluate the size of the entire object. This is a valid fallback
// for when Type=1 and the designator is invalid, because we're asked for an
// upper-bound.
if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) {
// Type=3 wants a lower bound, so we can't fall back to this.
if (Type == 3 && !DetermineForCompleteObject)
return false;
llvm::APInt APEndOffset;
if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
if (LVal.InvalidBase)
return false;
QualType BaseTy = getObjectType(LVal.getLValueBase());
return CheckedHandleSizeof(BaseTy, EndOffset);
}
// We want to evaluate the size of a subobject.
const SubobjectDesignator &Designator = LVal.Designator;
// The following is a moderately common idiom in C:
//
// struct Foo { int a; char c[1]; };
// struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar));
// strcpy(&F->c[0], Bar);
//
// In order to not break too much legacy code, we need to support it.
if (isUserWritingOffTheEnd(Info.Ctx, LVal)) {
// If we can resolve this to an alloc_size call, we can hand that back,
// because we know for certain how many bytes there are to write to.
llvm::APInt APEndOffset;
if (isBaseAnAllocSizeCall(LVal.getLValueBase()) &&
getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset))
return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset);
// If we cannot determine the size of the initial allocation, then we can't
// given an accurate upper-bound. However, we are still able to give
// conservative lower-bounds for Type=3.
if (Type == 1)
return false;
}
CharUnits BytesPerElem;
if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem))
return false;
// According to the GCC documentation, we want the size of the subobject
// denoted by the pointer. But that's not quite right -- what we actually
// want is the size of the immediately-enclosing array, if there is one.
int64_t ElemsRemaining;
if (Designator.MostDerivedIsArrayElement &&
Designator.Entries.size() == Designator.MostDerivedPathLength) {
uint64_t ArraySize = Designator.getMostDerivedArraySize();
uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex();
ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex;
} else {
ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1;
}
EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining;
return true;
}
/// Tries to evaluate the __builtin_object_size for @p E. If successful,
/// returns true and stores the result in @p Size.
///
/// If @p WasError is non-null, this will report whether the failure to evaluate
/// is to be treated as an Error in IntExprEvaluator.
static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type,
EvalInfo &Info, uint64_t &Size) {
// Determine the denoted object.
LValue LVal;
{
// The operand of __builtin_object_size is never evaluated for side-effects.
// If there are any, but we can determine the pointed-to object anyway, then
// ignore the side-effects.
SpeculativeEvaluationRAII SpeculativeEval(Info);
IgnoreSideEffectsRAII Fold(Info);
if (E->isGLValue()) {
// It's possible for us to be given GLValues if we're called via
// Expr::tryEvaluateObjectSize.
APValue RVal;
if (!EvaluateAsRValue(Info, E, RVal))
return false;
LVal.setFrom(Info.Ctx, RVal);
} else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info,
/*InvalidBaseOK=*/true))
return false;
}
// If we point to before the start of the object, there are no accessible
// bytes.
if (LVal.getLValueOffset().isNegative()) {
Size = 0;
return true;
}
CharUnits EndOffset;
if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset))
return false;
// If we've fallen outside of the end offset, just pretend there's nothing to
// write to/read from.
if (EndOffset <= LVal.getLValueOffset())
Size = 0;
else
Size = (EndOffset - LVal.getLValueOffset()).getQuantity();
return true;
}
bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
if (unsigned BuiltinOp = E->getBuiltinCallee())
return VisitBuiltinCallExpr(E, BuiltinOp);
return ExprEvaluatorBaseTy::VisitCallExpr(E);
}
static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info,
APValue &Val, APSInt &Alignment) {
QualType SrcTy = E->getArg(0)->getType();
if (!getAlignmentArgument(E->getArg(1), SrcTy, Info, Alignment))
return false;
// Even though we are evaluating integer expressions we could get a pointer
// argument for the __builtin_is_aligned() case.
if (SrcTy->isPointerType()) {
LValue Ptr;
if (!EvaluatePointer(E->getArg(0), Ptr, Info))
return false;
Ptr.moveInto(Val);
} else if (!SrcTy->isIntegralOrEnumerationType()) {
Info.FFDiag(E->getArg(0));
return false;
} else {
APSInt SrcInt;
if (!EvaluateInteger(E->getArg(0), SrcInt, Info))
return false;
assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() &&
"Bit widths must be the same");
Val = APValue(SrcInt);
}
assert(Val.hasValue());
return true;
}
bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
unsigned BuiltinOp) {
switch (BuiltinOp) {
default:
return ExprEvaluatorBaseTy::VisitCallExpr(E);
case Builtin::BI__builtin_dynamic_object_size:
case Builtin::BI__builtin_object_size: {
// The type was checked when we built the expression.
unsigned Type =
E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
assert(Type <= 3 && "unexpected type");
uint64_t Size;
if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size))
return Success(Size, E);
if (E->getArg(0)->HasSideEffects(Info.Ctx))
return Success((Type & 2) ? 0 : -1, E);
// Expression had no side effects, but we couldn't statically determine the
// size of the referenced object.
switch (Info.EvalMode) {
case EvalInfo::EM_ConstantExpression:
case EvalInfo::EM_ConstantFold:
case EvalInfo::EM_IgnoreSideEffects:
// Leave it to IR generation.
return Error(E);
case EvalInfo::EM_ConstantExpressionUnevaluated:
// Reduce it to a constant now.
return Success((Type & 2) ? 0 : -1, E);
}
llvm_unreachable("unexpected EvalMode");
}
case Builtin::BI__builtin_os_log_format_buffer_size: {
analyze_os_log::OSLogBufferLayout Layout;
analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout);
return Success(Layout.size().getQuantity(), E);
}
case Builtin::BI__builtin_is_aligned: {
APValue Src;
APSInt Alignment;
if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
return false;
if (Src.isLValue()) {
// If we evaluated a pointer, check the minimum known alignment.
LValue Ptr;
Ptr.setFrom(Info.Ctx, Src);
CharUnits BaseAlignment = getBaseAlignment(Info, Ptr);
CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Ptr.Offset);
// We can return true if the known alignment at the computed offset is
// greater than the requested alignment.
assert(PtrAlign.isPowerOfTwo());
assert(Alignment.isPowerOf2());
if (PtrAlign.getQuantity() >= Alignment)
return Success(1, E);
// If the alignment is not known to be sufficient, some cases could still
// be aligned at run time. However, if the requested alignment is less or
// equal to the base alignment and the offset is not aligned, we know that
// the run-time value can never be aligned.
if (BaseAlignment.getQuantity() >= Alignment &&
PtrAlign.getQuantity() < Alignment)
return Success(0, E);
// Otherwise we can't infer whether the value is sufficiently aligned.
// TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N)
// in cases where we can't fully evaluate the pointer.
Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute)
<< Alignment;
return false;
}
assert(Src.isInt());
return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E);
}
case Builtin::BI__builtin_align_up: {
APValue Src;
APSInt Alignment;
if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
return false;
if (!Src.isInt())
return Error(E);
APSInt AlignedVal =
APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1),
Src.getInt().isUnsigned());
assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
return Success(AlignedVal, E);
}
case Builtin::BI__builtin_align_down: {
APValue Src;
APSInt Alignment;
if (!getBuiltinAlignArguments(E, Info, Src, Alignment))
return false;
if (!Src.isInt())
return Error(E);
APSInt AlignedVal =
APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned());
assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth());
return Success(AlignedVal, E);
}
case Builtin::BI__builtin_bitreverse8:
case Builtin::BI__builtin_bitreverse16:
case Builtin::BI__builtin_bitreverse32:
case Builtin::BI__builtin_bitreverse64: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.reverseBits(), E);
}
case Builtin::BI__builtin_bswap16:
case Builtin::BI__builtin_bswap32:
case Builtin::BI__builtin_bswap64: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.byteSwap(), E);
}
case Builtin::BI__builtin_classify_type:
return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E);
case Builtin::BI__builtin_clrsb:
case Builtin::BI__builtin_clrsbl:
case Builtin::BI__builtin_clrsbll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.getBitWidth() - Val.getMinSignedBits(), E);
}
case Builtin::BI__builtin_clz:
case Builtin::BI__builtin_clzl:
case Builtin::BI__builtin_clzll:
case Builtin::BI__builtin_clzs: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
if (!Val)
return Error(E);
return Success(Val.countLeadingZeros(), E);
}
case Builtin::BI__builtin_constant_p: {
const Expr *Arg = E->getArg(0);
if (EvaluateBuiltinConstantP(Info, Arg))
return Success(true, E);
if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) {
// Outside a constant context, eagerly evaluate to false in the presence
// of side-effects in order to avoid -Wunsequenced false-positives in
// a branch on __builtin_constant_p(expr).
return Success(false, E);
}
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
case Builtin::BI__builtin_is_constant_evaluated: {
const auto *Callee = Info.CurrentCall->getCallee();
if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression &&
(Info.CallStackDepth == 1 ||
(Info.CallStackDepth == 2 && Callee->isInStdNamespace() &&
Callee->getIdentifier() &&
Callee->getIdentifier()->isStr("is_constant_evaluated")))) {
// FIXME: Find a better way to avoid duplicated diagnostics.
if (Info.EvalStatus.Diag)
Info.report((Info.CallStackDepth == 1) ? E->getExprLoc()
: Info.CurrentCall->CallLoc,
diag::warn_is_constant_evaluated_always_true_constexpr)
<< (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated"
: "std::is_constant_evaluated");
}
return Success(Info.InConstantContext, E);
}
case Builtin::BI__builtin_ctz:
case Builtin::BI__builtin_ctzl:
case Builtin::BI__builtin_ctzll:
case Builtin::BI__builtin_ctzs: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
if (!Val)
return Error(E);
return Success(Val.countTrailingZeros(), E);
}
case Builtin::BI__builtin_eh_return_data_regno: {
int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue();
Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand);
return Success(Operand, E);
}
case Builtin::BI__builtin_expect:
case Builtin::BI__builtin_expect_with_probability:
return Visit(E->getArg(0));
case Builtin::BI__builtin_ffs:
case Builtin::BI__builtin_ffsl:
case Builtin::BI__builtin_ffsll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
unsigned N = Val.countTrailingZeros();
return Success(N == Val.getBitWidth() ? 0 : N + 1, E);
}
case Builtin::BI__builtin_fpclassify: {
APFloat Val(0.0);
if (!EvaluateFloat(E->getArg(5), Val, Info))
return false;
unsigned Arg;
switch (Val.getCategory()) {
case APFloat::fcNaN: Arg = 0; break;
case APFloat::fcInfinity: Arg = 1; break;
case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break;
case APFloat::fcZero: Arg = 4; break;
}
return Visit(E->getArg(Arg));
}
case Builtin::BI__builtin_isinf_sign: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E);
}
case Builtin::BI__builtin_isinf: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isInfinity() ? 1 : 0, E);
}
case Builtin::BI__builtin_isfinite: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isFinite() ? 1 : 0, E);
}
case Builtin::BI__builtin_isnan: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isNaN() ? 1 : 0, E);
}
case Builtin::BI__builtin_isnormal: {
APFloat Val(0.0);
return EvaluateFloat(E->getArg(0), Val, Info) &&
Success(Val.isNormal() ? 1 : 0, E);
}
case Builtin::BI__builtin_parity:
case Builtin::BI__builtin_parityl:
case Builtin::BI__builtin_parityll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.countPopulation() % 2, E);
}
case Builtin::BI__builtin_popcount:
case Builtin::BI__builtin_popcountl:
case Builtin::BI__builtin_popcountll: {
APSInt Val;
if (!EvaluateInteger(E->getArg(0), Val, Info))
return false;
return Success(Val.countPopulation(), E);
}
case Builtin::BI__builtin_rotateleft8:
case Builtin::BI__builtin_rotateleft16:
case Builtin::BI__builtin_rotateleft32:
case Builtin::BI__builtin_rotateleft64:
case Builtin::BI_rotl8: // Microsoft variants of rotate right
case Builtin::BI_rotl16:
case Builtin::BI_rotl:
case Builtin::BI_lrotl:
case Builtin::BI_rotl64: {
APSInt Val, Amt;
if (!EvaluateInteger(E->getArg(0), Val, Info) ||
!EvaluateInteger(E->getArg(1), Amt, Info))
return false;
return Success(Val.rotl(Amt.urem(Val.getBitWidth())), E);
}
case Builtin::BI__builtin_rotateright8:
case Builtin::BI__builtin_rotateright16:
case Builtin::BI__builtin_rotateright32:
case Builtin::BI__builtin_rotateright64:
case Builtin::BI_rotr8: // Microsoft variants of rotate right
case Builtin::BI_rotr16:
case Builtin::BI_rotr:
case Builtin::BI_lrotr:
case Builtin::BI_rotr64: {
APSInt Val, Amt;
if (!EvaluateInteger(E->getArg(0), Val, Info) ||
!EvaluateInteger(E->getArg(1), Amt, Info))
return false;
return Success(Val.rotr(Amt.urem(Val.getBitWidth())), E);
}
case Builtin::BIstrlen:
case Builtin::BIwcslen:
// A call to strlen is not a constant expression.
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
LLVM_FALLTHROUGH;
case Builtin::BI__builtin_strlen:
case Builtin::BI__builtin_wcslen: {
// As an extension, we support __builtin_strlen() as a constant expression,
// and support folding strlen() to a constant.
LValue String;
if (!EvaluatePointer(E->getArg(0), String, Info))
return false;
QualType CharTy = E->getArg(0)->getType()->getPointeeType();
// Fast path: if it's a string literal, search the string value.
if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>(
String.getLValueBase().dyn_cast<const Expr *>())) {
// The string literal may have embedded null characters. Find the first
// one and truncate there.
StringRef Str = S->getBytes();
int64_t Off = String.Offset.getQuantity();
if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() &&
S->getCharByteWidth() == 1 &&
// FIXME: Add fast-path for wchar_t too.
Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) {
Str = Str.substr(Off);
StringRef::size_type Pos = Str.find(0);
if (Pos != StringRef::npos)
Str = Str.substr(0, Pos);
return Success(Str.size(), E);
}
// Fall through to slow path to issue appropriate diagnostic.
}
// Slow path: scan the bytes of the string looking for the terminating 0.
for (uint64_t Strlen = 0; /**/; ++Strlen) {
APValue Char;
if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) ||
!Char.isInt())
return false;
if (!Char.getInt())
return Success(Strlen, E);
if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1))
return false;
}
}
case Builtin::BIstrcmp:
case Builtin::BIwcscmp:
case Builtin::BIstrncmp:
case Builtin::BIwcsncmp:
case Builtin::BImemcmp:
case Builtin::BIbcmp:
case Builtin::BIwmemcmp:
// A call to strlen is not a constant expression.
if (Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_invalid_function)
<< /*isConstexpr*/0 << /*isConstructor*/0
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'");
else
Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr);
LLVM_FALLTHROUGH;
case Builtin::BI__builtin_strcmp:
case Builtin::BI__builtin_wcscmp:
case Builtin::BI__builtin_strncmp:
case Builtin::BI__builtin_wcsncmp:
case Builtin::BI__builtin_memcmp:
case Builtin::BI__builtin_bcmp:
case Builtin::BI__builtin_wmemcmp: {
LValue String1, String2;
if (!EvaluatePointer(E->getArg(0), String1, Info) ||
!EvaluatePointer(E->getArg(1), String2, Info))
return false;
uint64_t MaxLength = uint64_t(-1);
if (BuiltinOp != Builtin::BIstrcmp &&
BuiltinOp != Builtin::BIwcscmp &&
BuiltinOp != Builtin::BI__builtin_strcmp &&
BuiltinOp != Builtin::BI__builtin_wcscmp) {
APSInt N;
if (!EvaluateInteger(E->getArg(2), N, Info))
return false;
MaxLength = N.getExtValue();
}
// Empty substrings compare equal by definition.
if (MaxLength == 0u)
return Success(0, E);
if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
!String2.checkNullPointerForFoldAccess(Info, E, AK_Read) ||
String1.Designator.Invalid || String2.Designator.Invalid)
return false;
QualType CharTy1 = String1.Designator.getType(Info.Ctx);
QualType CharTy2 = String2.Designator.getType(Info.Ctx);
bool IsRawByte = BuiltinOp == Builtin::BImemcmp ||
BuiltinOp == Builtin::BIbcmp ||
BuiltinOp == Builtin::BI__builtin_memcmp ||
BuiltinOp == Builtin::BI__builtin_bcmp;
assert(IsRawByte ||
(Info.Ctx.hasSameUnqualifiedType(
CharTy1, E->getArg(0)->getType()->getPointeeType()) &&
Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2)));
// For memcmp, allow comparing any arrays of '[[un]signed] char' or
// 'char8_t', but no other types.
if (IsRawByte &&
!(isOneByteCharacterType(CharTy1) && isOneByteCharacterType(CharTy2))) {
// FIXME: Consider using our bit_cast implementation to support this.
Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported)
<< (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'")
<< CharTy1 << CharTy2;
return false;
}
const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) {
return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) &&
handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) &&
Char1.isInt() && Char2.isInt();
};
const auto &AdvanceElems = [&] {
return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) &&
HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1);
};
bool StopAtNull =
(BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp &&
BuiltinOp != Builtin::BIwmemcmp &&
BuiltinOp != Builtin::BI__builtin_memcmp &&
BuiltinOp != Builtin::BI__builtin_bcmp &&
BuiltinOp != Builtin::BI__builtin_wmemcmp);
bool IsWide = BuiltinOp == Builtin::BIwcscmp ||
BuiltinOp == Builtin::BIwcsncmp ||
BuiltinOp == Builtin::BIwmemcmp ||
BuiltinOp == Builtin::BI__builtin_wcscmp ||
BuiltinOp == Builtin::BI__builtin_wcsncmp ||
BuiltinOp == Builtin::BI__builtin_wmemcmp;
for (; MaxLength; --MaxLength) {
APValue Char1, Char2;
if (!ReadCurElems(Char1, Char2))
return false;
if (Char1.getInt().ne(Char2.getInt())) {
if (IsWide) // wmemcmp compares with wchar_t signedness.
return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E);
// memcmp always compares unsigned chars.
return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E);
}
if (StopAtNull && !Char1.getInt())
return Success(0, E);
assert(!(StopAtNull && !Char2.getInt()));
if (!AdvanceElems())
return false;
}
// We hit the strncmp / memcmp limit.
return Success(0, E);
}
case Builtin::BI__atomic_always_lock_free:
case Builtin::BI__atomic_is_lock_free:
case Builtin::BI__c11_atomic_is_lock_free: {
APSInt SizeVal;
if (!EvaluateInteger(E->getArg(0), SizeVal, Info))
return false;
// For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power
// of two less than or equal to the maximum inline atomic width, we know it
// is lock-free. If the size isn't a power of two, or greater than the
// maximum alignment where we promote atomics, we know it is not lock-free
// (at least not in the sense of atomic_is_lock_free). Otherwise,
// the answer can only be determined at runtime; for example, 16-byte
// atomics have lock-free implementations on some, but not all,
// x86-64 processors.
// Check power-of-two.
CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue());
if (Size.isPowerOfTwo()) {
// Check against inlining width.
unsigned InlineWidthBits =
Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth();
if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) {
if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free ||
Size == CharUnits::One() ||
E->getArg(1)->isNullPointerConstant(Info.Ctx,
Expr::NPC_NeverValueDependent))
// OK, we will inline appropriately-aligned operations of this size,
// and _Atomic(T) is appropriately-aligned.
return Success(1, E);
QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()->
castAs<PointerType>()->getPointeeType();
if (!PointeeType->isIncompleteType() &&
Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) {
// OK, we will inline operations on this object.
return Success(1, E);
}
}
}
return BuiltinOp == Builtin::BI__atomic_always_lock_free ?
Success(0, E) : Error(E);
}
case Builtin::BI__builtin_add_overflow:
case Builtin::BI__builtin_sub_overflow:
case Builtin::BI__builtin_mul_overflow:
case Builtin::BI__builtin_sadd_overflow:
case Builtin::BI__builtin_uadd_overflow:
case Builtin::BI__builtin_uaddl_overflow:
case Builtin::BI__builtin_uaddll_overflow:
case Builtin::BI__builtin_usub_overflow:
case Builtin::BI__builtin_usubl_overflow:
case Builtin::BI__builtin_usubll_overflow:
case Builtin::BI__builtin_umul_overflow:
case Builtin::BI__builtin_umull_overflow:
case Builtin::BI__builtin_umulll_overflow:
case Builtin::BI__builtin_saddl_overflow:
case Builtin::BI__builtin_saddll_overflow:
case Builtin::BI__builtin_ssub_overflow:
case Builtin::BI__builtin_ssubl_overflow:
case Builtin::BI__builtin_ssubll_overflow:
case Builtin::BI__builtin_smul_overflow:
case Builtin::BI__builtin_smull_overflow:
case Builtin::BI__builtin_smulll_overflow: {
LValue ResultLValue;
APSInt LHS, RHS;
QualType ResultType = E->getArg(2)->getType()->getPointeeType();
if (!EvaluateInteger(E->getArg(0), LHS, Info) ||
!EvaluateInteger(E->getArg(1), RHS, Info) ||
!EvaluatePointer(E->getArg(2), ResultLValue, Info))
return false;
APSInt Result;
bool DidOverflow = false;
// If the types don't have to match, enlarge all 3 to the largest of them.
if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
BuiltinOp == Builtin::BI__builtin_sub_overflow ||
BuiltinOp == Builtin::BI__builtin_mul_overflow) {
bool IsSigned = LHS.isSigned() || RHS.isSigned() ||
ResultType->isSignedIntegerOrEnumerationType();
bool AllSigned = LHS.isSigned() && RHS.isSigned() &&
ResultType->isSignedIntegerOrEnumerationType();
uint64_t LHSSize = LHS.getBitWidth();
uint64_t RHSSize = RHS.getBitWidth();
uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType);
uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize);
// Add an additional bit if the signedness isn't uniformly agreed to. We
// could do this ONLY if there is a signed and an unsigned that both have
// MaxBits, but the code to check that is pretty nasty. The issue will be
// caught in the shrink-to-result later anyway.
if (IsSigned && !AllSigned)
++MaxBits;
LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned);
RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned);
Result = APSInt(MaxBits, !IsSigned);
}
// Find largest int.
switch (BuiltinOp) {
default:
llvm_unreachable("Invalid value for BuiltinOp");
case Builtin::BI__builtin_add_overflow:
case Builtin::BI__builtin_sadd_overflow:
case Builtin::BI__builtin_saddl_overflow:
case Builtin::BI__builtin_saddll_overflow:
case Builtin::BI__builtin_uadd_overflow:
case Builtin::BI__builtin_uaddl_overflow:
case Builtin::BI__builtin_uaddll_overflow:
Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow)
: LHS.uadd_ov(RHS, DidOverflow);
break;
case Builtin::BI__builtin_sub_overflow:
case Builtin::BI__builtin_ssub_overflow:
case Builtin::BI__builtin_ssubl_overflow:
case Builtin::BI__builtin_ssubll_overflow:
case Builtin::BI__builtin_usub_overflow:
case Builtin::BI__builtin_usubl_overflow:
case Builtin::BI__builtin_usubll_overflow:
Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow)
: LHS.usub_ov(RHS, DidOverflow);
break;
case Builtin::BI__builtin_mul_overflow:
case Builtin::BI__builtin_smul_overflow:
case Builtin::BI__builtin_smull_overflow:
case Builtin::BI__builtin_smulll_overflow:
case Builtin::BI__builtin_umul_overflow:
case Builtin::BI__builtin_umull_overflow:
case Builtin::BI__builtin_umulll_overflow:
Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow)
: LHS.umul_ov(RHS, DidOverflow);
break;
}
// In the case where multiple sizes are allowed, truncate and see if
// the values are the same.
if (BuiltinOp == Builtin::BI__builtin_add_overflow ||
BuiltinOp == Builtin::BI__builtin_sub_overflow ||
BuiltinOp == Builtin::BI__builtin_mul_overflow) {
// APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead,
// since it will give us the behavior of a TruncOrSelf in the case where
// its parameter <= its size. We previously set Result to be at least the
// type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth
// will work exactly like TruncOrSelf.
APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType));
Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType());
if (!APSInt::isSameValue(Temp, Result))
DidOverflow = true;
Result = Temp;
}
APValue APV{Result};
if (!handleAssignment(Info, E, ResultLValue, ResultType, APV))
return false;
return Success(DidOverflow, E);
}
}
}
/// Determine whether this is a pointer past the end of the complete
/// object referred to by the lvalue.
static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx,
const LValue &LV) {
// A null pointer can be viewed as being "past the end" but we don't
// choose to look at it that way here.
if (!LV.getLValueBase())
return false;
// If the designator is valid and refers to a subobject, we're not pointing
// past the end.
if (!LV.getLValueDesignator().Invalid &&
!LV.getLValueDesignator().isOnePastTheEnd())
return false;
// A pointer to an incomplete type might be past-the-end if the type's size is
// zero. We cannot tell because the type is incomplete.
QualType Ty = getType(LV.getLValueBase());
if (Ty->isIncompleteType())
return true;
// We're a past-the-end pointer if we point to the byte after the object,
// no matter what our type or path is.
auto Size = Ctx.getTypeSizeInChars(Ty);
return LV.getLValueOffset() == Size;
}
namespace {
/// Data recursive integer evaluator of certain binary operators.
///
/// We use a data recursive algorithm for binary operators so that we are able
/// to handle extreme cases of chained binary operators without causing stack
/// overflow.
class DataRecursiveIntBinOpEvaluator {
struct EvalResult {
APValue Val;
bool Failed;
EvalResult() : Failed(false) { }
void swap(EvalResult &RHS) {
Val.swap(RHS.Val);
Failed = RHS.Failed;
RHS.Failed = false;
}
};
struct Job {
const Expr *E;
EvalResult LHSResult; // meaningful only for binary operator expression.
enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind;
Job() = default;
Job(Job &&) = default;
void startSpeculativeEval(EvalInfo &Info) {
SpecEvalRAII = SpeculativeEvaluationRAII(Info);
}
private:
SpeculativeEvaluationRAII SpecEvalRAII;
};
SmallVector<Job, 16> Queue;
IntExprEvaluator &IntEval;
EvalInfo &Info;
APValue &FinalResult;
public:
DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result)
: IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { }
/// True if \param E is a binary operator that we are going to handle
/// data recursively.
/// We handle binary operators that are comma, logical, or that have operands
/// with integral or enumeration type.
static bool shouldEnqueue(const BinaryOperator *E) {
return E->getOpcode() == BO_Comma || E->isLogicalOp() ||
(E->isRValue() && E->getType()->isIntegralOrEnumerationType() &&
E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
}
bool Traverse(const BinaryOperator *E) {
enqueue(E);
EvalResult PrevResult;
while (!Queue.empty())
process(PrevResult);
if (PrevResult.Failed) return false;
FinalResult.swap(PrevResult.Val);
return true;
}
private:
bool Success(uint64_t Value, const Expr *E, APValue &Result) {
return IntEval.Success(Value, E, Result);
}
bool Success(const APSInt &Value, const Expr *E, APValue &Result) {
return IntEval.Success(Value, E, Result);
}
bool Error(const Expr *E) {
return IntEval.Error(E);
}
bool Error(const Expr *E, diag::kind D) {
return IntEval.Error(E, D);
}
OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) {
return Info.CCEDiag(E, D);
}
// Returns true if visiting the RHS is necessary, false otherwise.
bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
bool &SuppressRHSDiags);
bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
const BinaryOperator *E, APValue &Result);
void EvaluateExpr(const Expr *E, EvalResult &Result) {
Result.Failed = !Evaluate(Result.Val, Info, E);
if (Result.Failed)
Result.Val = APValue();
}
void process(EvalResult &Result);
void enqueue(const Expr *E) {
E = E->IgnoreParens();
Queue.resize(Queue.size()+1);
Queue.back().E = E;
Queue.back().Kind = Job::AnyExprKind;
}
};
}
bool DataRecursiveIntBinOpEvaluator::
VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E,
bool &SuppressRHSDiags) {
if (E->getOpcode() == BO_Comma) {
// Ignore LHS but note if we could not evaluate it.
if (LHSResult.Failed)
return Info.noteSideEffect();
return true;
}
if (E->isLogicalOp()) {
bool LHSAsBool;
if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) {
// We were able to evaluate the LHS, see if we can get away with not
// evaluating the RHS: 0 && X -> 0, 1 || X -> 1
if (LHSAsBool == (E->getOpcode() == BO_LOr)) {
Success(LHSAsBool, E, LHSResult.Val);
return false; // Ignore RHS
}
} else {
LHSResult.Failed = true;
// Since we weren't able to evaluate the left hand side, it
// might have had side effects.
if (!Info.noteSideEffect())
return false;
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
// Don't ignore RHS and suppress diagnostics from this arm.
SuppressRHSDiags = true;
}
return true;
}
assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
if (LHSResult.Failed && !Info.noteFailure())
return false; // Ignore RHS;
return true;
}
static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index,
bool IsSub) {
// Compute the new offset in the appropriate width, wrapping at 64 bits.
// FIXME: When compiling for a 32-bit target, we should use 32-bit
// offsets.
assert(!LVal.hasLValuePath() && "have designator for integer lvalue");
CharUnits &Offset = LVal.getLValueOffset();
uint64_t Offset64 = Offset.getQuantity();
uint64_t Index64 = Index.extOrTrunc(64).getZExtValue();
Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64
: Offset64 + Index64);
}
bool DataRecursiveIntBinOpEvaluator::
VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult,
const BinaryOperator *E, APValue &Result) {
if (E->getOpcode() == BO_Comma) {
if (RHSResult.Failed)
return false;
Result = RHSResult.Val;
return true;
}
if (E->isLogicalOp()) {
bool lhsResult, rhsResult;
bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult);
bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult);
if (LHSIsOK) {
if (RHSIsOK) {
if (E->getOpcode() == BO_LOr)
return Success(lhsResult || rhsResult, E, Result);
else
return Success(lhsResult && rhsResult, E, Result);
}
} else {
if (RHSIsOK) {
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
if (rhsResult == (E->getOpcode() == BO_LOr))
return Success(rhsResult, E, Result);
}
}
return false;
}
assert(E->getLHS()->getType()->isIntegralOrEnumerationType() &&
E->getRHS()->getType()->isIntegralOrEnumerationType());
if (LHSResult.Failed || RHSResult.Failed)
return false;
const APValue &LHSVal = LHSResult.Val;
const APValue &RHSVal = RHSResult.Val;
// Handle cases like (unsigned long)&a + 4.
if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
Result = LHSVal;
addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub);
return true;
}
// Handle cases like 4 + (unsigned long)&a
if (E->getOpcode() == BO_Add &&
RHSVal.isLValue() && LHSVal.isInt()) {
Result = RHSVal;
addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false);
return true;
}
if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) {
// Handle (intptr_t)&&A - (intptr_t)&&B.
if (!LHSVal.getLValueOffset().isZero() ||
!RHSVal.getLValueOffset().isZero())
return false;
const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>();
const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>();
if (!LHSExpr || !RHSExpr)
return false;
const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
if (!LHSAddrExpr || !RHSAddrExpr)
return false;
// Make sure both labels come from the same function.
if (LHSAddrExpr->getLabel()->getDeclContext() !=
RHSAddrExpr->getLabel()->getDeclContext())
return false;
Result = APValue(LHSAddrExpr, RHSAddrExpr);
return true;
}
// All the remaining cases expect both operands to be an integer
if (!LHSVal.isInt() || !RHSVal.isInt())
return Error(E);
// Set up the width and signedness manually, in case it can't be deduced
// from the operation we're performing.
// FIXME: Don't do this in the cases where we can deduce it.
APSInt Value(Info.Ctx.getIntWidth(E->getType()),
E->getType()->isUnsignedIntegerOrEnumerationType());
if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(),
RHSVal.getInt(), Value))
return false;
return Success(Value, E, Result);
}
void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) {
Job &job = Queue.back();
switch (job.Kind) {
case Job::AnyExprKind: {
if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) {
if (shouldEnqueue(Bop)) {
job.Kind = Job::BinOpKind;
enqueue(Bop->getLHS());
return;
}
}
EvaluateExpr(job.E, Result);
Queue.pop_back();
return;
}
case Job::BinOpKind: {
const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
bool SuppressRHSDiags = false;
if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) {
Queue.pop_back();
return;
}
if (SuppressRHSDiags)
job.startSpeculativeEval(Info);
job.LHSResult.swap(Result);
job.Kind = Job::BinOpVisitedLHSKind;
enqueue(Bop->getRHS());
return;
}
case Job::BinOpVisitedLHSKind: {
const BinaryOperator *Bop = cast<BinaryOperator>(job.E);
EvalResult RHS;
RHS.swap(Result);
Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val);
Queue.pop_back();
return;
}
}
llvm_unreachable("Invalid Job::Kind!");
}
namespace {
enum class CmpResult {
Unequal,
Less,
Equal,
Greater,
Unordered,
};
}
template <class SuccessCB, class AfterCB>
static bool
EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E,
SuccessCB &&Success, AfterCB &&DoAfter) {
assert(!E->isValueDependent());
assert(E->isComparisonOp() && "expected comparison operator");
assert((E->getOpcode() == BO_Cmp ||
E->getType()->isIntegralOrEnumerationType()) &&
"unsupported binary expression evaluation");
auto Error = [&](const Expr *E) {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
};
bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp;
bool IsEquality = E->isEqualityOp();
QualType LHSTy = E->getLHS()->getType();
QualType RHSTy = E->getRHS()->getType();
if (LHSTy->isIntegralOrEnumerationType() &&
RHSTy->isIntegralOrEnumerationType()) {
APSInt LHS, RHS;
bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK)
return false;
if (LHS < RHS)
return Success(CmpResult::Less, E);
if (LHS > RHS)
return Success(CmpResult::Greater, E);
return Success(CmpResult::Equal, E);
}
if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) {
APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy));
APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy));
bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK)
return false;
if (LHSFX < RHSFX)
return Success(CmpResult::Less, E);
if (LHSFX > RHSFX)
return Success(CmpResult::Greater, E);
return Success(CmpResult::Equal, E);
}
if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) {
ComplexValue LHS, RHS;
bool LHSOK;
if (E->isAssignmentOp()) {
LValue LV;
EvaluateLValue(E->getLHS(), LV, Info);
LHSOK = false;
} else if (LHSTy->isRealFloatingType()) {
LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info);
if (LHSOK) {
LHS.makeComplexFloat();
LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics());
}
} else {
LHSOK = EvaluateComplex(E->getLHS(), LHS, Info);
}
if (!LHSOK && !Info.noteFailure())
return false;
if (E->getRHS()->getType()->isRealFloatingType()) {
if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK)
return false;
RHS.makeComplexFloat();
RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics());
} else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
return false;
if (LHS.isComplexFloat()) {
APFloat::cmpResult CR_r =
LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
APFloat::cmpResult CR_i =
LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual;
return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
} else {
assert(IsEquality && "invalid complex comparison");
bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
LHS.getComplexIntImag() == RHS.getComplexIntImag();
return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E);
}
}
if (LHSTy->isRealFloatingType() &&
RHSTy->isRealFloatingType()) {
APFloat RHS(0.0), LHS(0.0);
bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK)
return false;
assert(E->isComparisonOp() && "Invalid binary operator!");
llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS);
if (!Info.InConstantContext &&
APFloatCmpResult == APFloat::cmpUnordered &&
E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) {
// Note: Compares may raise invalid in some cases involving NaN or sNaN.
Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
return false;
}
auto GetCmpRes = [&]() {
switch (APFloatCmpResult) {
case APFloat::cmpEqual:
return CmpResult::Equal;
case APFloat::cmpLessThan:
return CmpResult::Less;
case APFloat::cmpGreaterThan:
return CmpResult::Greater;
case APFloat::cmpUnordered:
return CmpResult::Unordered;
}
llvm_unreachable("Unrecognised APFloat::cmpResult enum");
};
return Success(GetCmpRes(), E);
}
if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
LValue LHSValue, RHSValue;
bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
return false;
// Reject differing bases from the normal codepath; we special-case
// comparisons to null.
if (!HasSameBase(LHSValue, RHSValue)) {
// Inequalities and subtractions between unrelated pointers have
// unspecified or undefined behavior.
if (!IsEquality) {
Info.FFDiag(E, diag::note_constexpr_pointer_comparison_unspecified);
return false;
}
// A constant address may compare equal to the address of a symbol.
// The one exception is that address of an object cannot compare equal
// to a null pointer constant.
if ((!LHSValue.Base && !LHSValue.Offset.isZero()) ||
(!RHSValue.Base && !RHSValue.Offset.isZero()))
return Error(E);
// It's implementation-defined whether distinct literals will have
// distinct addresses. In clang, the result of such a comparison is
// unspecified, so it is not a constant expression. However, we do know
// that the address of a literal will be non-null.
if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) &&
LHSValue.Base && RHSValue.Base)
return Error(E);
// We can't tell whether weak symbols will end up pointing to the same
// object.
if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue))
return Error(E);
// We can't compare the address of the start of one object with the
// past-the-end address of another object, per C++ DR1652.
if ((LHSValue.Base && LHSValue.Offset.isZero() &&
isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) ||
(RHSValue.Base && RHSValue.Offset.isZero() &&
isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue)))
return Error(E);
// We can't tell whether an object is at the same address as another
// zero sized object.
if ((RHSValue.Base && isZeroSized(LHSValue)) ||
(LHSValue.Base && isZeroSized(RHSValue)))
return Error(E);
return Success(CmpResult::Unequal, E);
}
const CharUnits &LHSOffset = LHSValue.getLValueOffset();
const CharUnits &RHSOffset = RHSValue.getLValueOffset();
SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
// C++11 [expr.rel]p3:
// Pointers to void (after pointer conversions) can be compared, with a
// result defined as follows: If both pointers represent the same
// address or are both the null pointer value, the result is true if the
// operator is <= or >= and false otherwise; otherwise the result is
// unspecified.
// We interpret this as applying to pointers to *cv* void.
if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational)
Info.CCEDiag(E, diag::note_constexpr_void_comparison);
// C++11 [expr.rel]p2:
// - If two pointers point to non-static data members of the same object,
// or to subobjects or array elements fo such members, recursively, the
// pointer to the later declared member compares greater provided the
// two members have the same access control and provided their class is
// not a union.
// [...]
// - Otherwise pointer comparisons are unspecified.
if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) {
bool WasArrayIndex;
unsigned Mismatch = FindDesignatorMismatch(
getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex);
// At the point where the designators diverge, the comparison has a
// specified value if:
// - we are comparing array indices
// - we are comparing fields of a union, or fields with the same access
// Otherwise, the result is unspecified and thus the comparison is not a
// constant expression.
if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() &&
Mismatch < RHSDesignator.Entries.size()) {
const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]);
const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]);
if (!LF && !RF)
Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes);
else if (!LF)
Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
<< getAsBaseClass(LHSDesignator.Entries[Mismatch])
<< RF->getParent() << RF;
else if (!RF)
Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field)
<< getAsBaseClass(RHSDesignator.Entries[Mismatch])
<< LF->getParent() << LF;
else if (!LF->getParent()->isUnion() &&
LF->getAccess() != RF->getAccess())
Info.CCEDiag(E,
diag::note_constexpr_pointer_comparison_differing_access)
<< LF << LF->getAccess() << RF << RF->getAccess()
<< LF->getParent();
}
}
// The comparison here must be unsigned, and performed with the same
// width as the pointer.
unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
uint64_t CompareLHS = LHSOffset.getQuantity();
uint64_t CompareRHS = RHSOffset.getQuantity();
assert(PtrSize <= 64 && "Unexpected pointer width");
uint64_t Mask = ~0ULL >> (64 - PtrSize);
CompareLHS &= Mask;
CompareRHS &= Mask;
// If there is a base and this is a relational operator, we can only
// compare pointers within the object in question; otherwise, the result
// depends on where the object is located in memory.
if (!LHSValue.Base.isNull() && IsRelational) {
QualType BaseTy = getType(LHSValue.Base);
if (BaseTy->isIncompleteType())
return Error(E);
CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
uint64_t OffsetLimit = Size.getQuantity();
if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
return Error(E);
}
if (CompareLHS < CompareRHS)
return Success(CmpResult::Less, E);
if (CompareLHS > CompareRHS)
return Success(CmpResult::Greater, E);
return Success(CmpResult::Equal, E);
}
if (LHSTy->isMemberPointerType()) {
assert(IsEquality && "unexpected member pointer operation");
assert(RHSTy->isMemberPointerType() && "invalid comparison");
MemberPtr LHSValue, RHSValue;
bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK)
return false;
// C++11 [expr.eq]p2:
// If both operands are null, they compare equal. Otherwise if only one is
// null, they compare unequal.
if (!LHSValue.getDecl() || !RHSValue.getDecl()) {
bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl();
return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
}
// Otherwise if either is a pointer to a virtual member function, the
// result is unspecified.
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl()))
if (MD->isVirtual())
Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl()))
if (MD->isVirtual())
Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD;
// Otherwise they compare equal if and only if they would refer to the
// same member of the same most derived object or the same subobject if
// they were dereferenced with a hypothetical object of the associated
// class type.
bool Equal = LHSValue == RHSValue;
return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E);
}
if (LHSTy->isNullPtrType()) {
assert(E->isComparisonOp() && "unexpected nullptr operation");
assert(RHSTy->isNullPtrType() && "missing pointer conversion");
// C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t
// are compared, the result is true of the operator is <=, >= or ==, and
// false otherwise.
return Success(CmpResult::Equal, E);
}
return DoAfter();
}
bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) {
if (!CheckLiteralType(Info, E))
return false;
auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
ComparisonCategoryResult CCR;
switch (CR) {
case CmpResult::Unequal:
llvm_unreachable("should never produce Unequal for three-way comparison");
case CmpResult::Less:
CCR = ComparisonCategoryResult::Less;
break;
case CmpResult::Equal:
CCR = ComparisonCategoryResult::Equal;
break;
case CmpResult::Greater:
CCR = ComparisonCategoryResult::Greater;
break;
case CmpResult::Unordered:
CCR = ComparisonCategoryResult::Unordered;
break;
}
// Evaluation succeeded. Lookup the information for the comparison category
// type and fetch the VarDecl for the result.
const ComparisonCategoryInfo &CmpInfo =
Info.Ctx.CompCategories.getInfoForType(E->getType());
const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(CCR))->VD;
// Check and evaluate the result as a constant expression.
LValue LV;
LV.set(VD);
if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
return false;
return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
ConstantExprKind::Normal);
};
return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
return ExprEvaluatorBaseTy::VisitBinCmp(E);
});
}
bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
// We don't support assignment in C. C++ assignments don't get here because
// assignment is an lvalue in C++.
if (E->isAssignmentOp()) {
Error(E);
if (!Info.noteFailure())
return false;
}
if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E))
return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E);
assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() ||
!E->getRHS()->getType()->isIntegralOrEnumerationType()) &&
"DataRecursiveIntBinOpEvaluator should have handled integral types");
if (E->isComparisonOp()) {
// Evaluate builtin binary comparisons by evaluating them as three-way
// comparisons and then translating the result.
auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) {
assert((CR != CmpResult::Unequal || E->isEqualityOp()) &&
"should only produce Unequal for equality comparisons");
bool IsEqual = CR == CmpResult::Equal,
IsLess = CR == CmpResult::Less,
IsGreater = CR == CmpResult::Greater;
auto Op = E->getOpcode();
switch (Op) {
default:
llvm_unreachable("unsupported binary operator");
case BO_EQ:
case BO_NE:
return Success(IsEqual == (Op == BO_EQ), E);
case BO_LT:
return Success(IsLess, E);
case BO_GT:
return Success(IsGreater, E);
case BO_LE:
return Success(IsEqual || IsLess, E);
case BO_GE:
return Success(IsEqual || IsGreater, E);
}
};
return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() {
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
});
}
QualType LHSTy = E->getLHS()->getType();
QualType RHSTy = E->getRHS()->getType();
if (LHSTy->isPointerType() && RHSTy->isPointerType() &&
E->getOpcode() == BO_Sub) {
LValue LHSValue, RHSValue;
bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info);
if (!LHSOK && !Info.noteFailure())
return false;
if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK)
return false;
// Reject differing bases from the normal codepath; we special-case
// comparisons to null.
if (!HasSameBase(LHSValue, RHSValue)) {
// Handle &&A - &&B.
if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero())
return Error(E);
const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>();
const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>();
if (!LHSExpr || !RHSExpr)
return Error(E);
const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr);
const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr);
if (!LHSAddrExpr || !RHSAddrExpr)
return Error(E);
// Make sure both labels come from the same function.
if (LHSAddrExpr->getLabel()->getDeclContext() !=
RHSAddrExpr->getLabel()->getDeclContext())
return Error(E);
return Success(APValue(LHSAddrExpr, RHSAddrExpr), E);
}
const CharUnits &LHSOffset = LHSValue.getLValueOffset();
const CharUnits &RHSOffset = RHSValue.getLValueOffset();
SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator();
SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator();
// C++11 [expr.add]p6:
// Unless both pointers point to elements of the same array object, or
// one past the last element of the array object, the behavior is
// undefined.
if (!LHSDesignator.Invalid && !RHSDesignator.Invalid &&
!AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator,
RHSDesignator))
Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array);
QualType Type = E->getLHS()->getType();
QualType ElementType = Type->castAs<PointerType>()->getPointeeType();
CharUnits ElementSize;
if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize))
return false;
// As an extension, a type may have zero size (empty struct or union in
// C, array of zero length). Pointer subtraction in such cases has
// undefined behavior, so is not constant.
if (ElementSize.isZero()) {
Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size)
<< ElementType;
return false;
}
// FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime,
// and produce incorrect results when it overflows. Such behavior
// appears to be non-conforming, but is common, so perhaps we should
// assume the standard intended for such cases to be undefined behavior
// and check for them.
// Compute (LHSOffset - RHSOffset) / Size carefully, checking for
// overflow in the final conversion to ptrdiff_t.
APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false);
APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false);
APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true),
false);
APSInt TrueResult = (LHS - RHS) / ElemSize;
APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType()));
if (Result.extend(65) != TrueResult &&
!HandleOverflow(Info, E, TrueResult, E->getType()))
return false;
return Success(Result, E);
}
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
}
/// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with
/// a result as the expression's type.
bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr(
const UnaryExprOrTypeTraitExpr *E) {
switch(E->getKind()) {
case UETT_PreferredAlignOf:
case UETT_AlignOf: {
if (E->isArgumentType())
return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()),
E);
else
return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()),
E);
}
case UETT_VecStep: {
QualType Ty = E->getTypeOfArgument();
if (Ty->isVectorType()) {
unsigned n = Ty->castAs<VectorType>()->getNumElements();
// The vec_step built-in functions that take a 3-component
// vector return 4. (OpenCL 1.1 spec 6.11.12)
if (n == 3)
n = 4;
return Success(n, E);
} else
return Success(1, E);
}
case UETT_SizeOf: {
QualType SrcTy = E->getTypeOfArgument();
// C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
// the result is the size of the referenced type."
if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
SrcTy = Ref->getPointeeType();
CharUnits Sizeof;
if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof))
return false;
return Success(Sizeof, E);
}
case UETT_OpenMPRequiredSimdAlign:
assert(E->isArgumentType());
return Success(
Info.Ctx.toCharUnitsFromBits(
Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType()))
.getQuantity(),
E);
}
llvm_unreachable("unknown expr/type trait");
}
bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) {
CharUnits Result;
unsigned n = OOE->getNumComponents();
if (n == 0)
return Error(OOE);
QualType CurrentType = OOE->getTypeSourceInfo()->getType();
for (unsigned i = 0; i != n; ++i) {
OffsetOfNode ON = OOE->getComponent(i);
switch (ON.getKind()) {
case OffsetOfNode::Array: {
const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex());
APSInt IdxResult;
if (!EvaluateInteger(Idx, IdxResult, Info))
return false;
const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType);
if (!AT)
return Error(OOE);
CurrentType = AT->getElementType();
CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType);
Result += IdxResult.getSExtValue() * ElementSize;
break;
}
case OffsetOfNode::Field: {
FieldDecl *MemberDecl = ON.getField();
const RecordType *RT = CurrentType->getAs<RecordType>();
if (!RT)
return Error(OOE);
RecordDecl *RD = RT->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
unsigned i = MemberDecl->getFieldIndex();
assert(i < RL.getFieldCount() && "offsetof field in wrong type");
Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i));
CurrentType = MemberDecl->getType().getNonReferenceType();
break;
}
case OffsetOfNode::Identifier:
llvm_unreachable("dependent __builtin_offsetof");
case OffsetOfNode::Base: {
CXXBaseSpecifier *BaseSpec = ON.getBase();
if (BaseSpec->isVirtual())
return Error(OOE);
// Find the layout of the class whose base we are looking into.
const RecordType *RT = CurrentType->getAs<RecordType>();
if (!RT)
return Error(OOE);
RecordDecl *RD = RT->getDecl();
if (RD->isInvalidDecl()) return false;
const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
// Find the base class itself.
CurrentType = BaseSpec->getType();
const RecordType *BaseRT = CurrentType->getAs<RecordType>();
if (!BaseRT)
return Error(OOE);
// Add the offset to the base.
Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl()));
break;
}
}
}
return Success(Result, OOE);
}
bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
switch (E->getOpcode()) {
default:
// Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
// See C99 6.6p3.
return Error(E);
case UO_Extension:
// FIXME: Should extension allow i-c-e extension expressions in its scope?
// If so, we could clear the diagnostic ID.
return Visit(E->getSubExpr());
case UO_Plus:
// The result is just the value.
return Visit(E->getSubExpr());
case UO_Minus: {
if (!Visit(E->getSubExpr()))
return false;
if (!Result.isInt()) return Error(E);
const APSInt &Value = Result.getInt();
if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() &&
!HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1),
E->getType()))
return false;
return Success(-Value, E);
}
case UO_Not: {
if (!Visit(E->getSubExpr()))
return false;
if (!Result.isInt()) return Error(E);
return Success(~Result.getInt(), E);
}
case UO_LNot: {
bool bres;
if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
return false;
return Success(!bres, E);
}
}
}
/// HandleCast - This is used to evaluate implicit or explicit casts where the
/// result type is integer.
bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr *SubExpr = E->getSubExpr();
QualType DestType = E->getType();
QualType SrcType = SubExpr->getType();
switch (E->getCastKind()) {
case CK_BaseToDerived:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
case CK_Dynamic:
case CK_ToUnion:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
case CK_BaseToDerivedMemberPointer:
case CK_DerivedToBaseMemberPointer:
case CK_ReinterpretMemberPointer:
case CK_ConstructorConversion:
case CK_IntegralToPointer:
case CK_ToVoid:
case CK_VectorSplat:
case CK_IntegralToFloating:
case CK_FloatingCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_ObjCObjectLValueCast:
case CK_FloatingRealToComplex:
case CK_FloatingComplexToReal:
case CK_FloatingComplexCast:
case CK_FloatingComplexToIntegralComplex:
case CK_IntegralRealToComplex:
case CK_IntegralComplexCast:
case CK_IntegralComplexToFloatingComplex:
case CK_BuiltinFnToFnPtr:
case CK_ZeroToOCLOpaqueType:
case CK_NonAtomicToAtomic:
case CK_AddressSpaceConversion:
case CK_IntToOCLSampler:
case CK_FloatingToFixedPoint:
case CK_FixedPointToFloating:
case CK_FixedPointCast:
case CK_IntegralToFixedPoint:
case CK_MatrixCast:
llvm_unreachable("invalid cast kind for integral value");
case CK_BitCast:
case CK_Dependent:
case CK_LValueBitCast:
case CK_ARCProduceObject:
case CK_ARCConsumeObject:
case CK_ARCReclaimReturnedObject:
case CK_ARCExtendBlockObject:
case CK_CopyAndAutoreleaseBlockObject:
return Error(E);
case CK_UserDefinedConversion:
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
case CK_LValueToRValueBitCast:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_MemberPointerToBoolean:
case CK_PointerToBoolean:
case CK_IntegralToBoolean:
case CK_FloatingToBoolean:
case CK_BooleanToSignedIntegral:
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToBoolean: {
bool BoolResult;
if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
return false;
uint64_t IntResult = BoolResult;
if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral)
IntResult = (uint64_t)-1;
return Success(IntResult, E);
}
case CK_FixedPointToIntegral: {
APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType));
if (!EvaluateFixedPoint(SubExpr, Src, Info))
return false;
bool Overflowed;
llvm::APSInt Result = Src.convertToInt(
Info.Ctx.getIntWidth(DestType),
DestType->isSignedIntegerOrEnumerationType(), &Overflowed);
if (Overflowed && !HandleOverflow(Info, E, Result, DestType))
return false;
return Success(Result, E);
}
case CK_FixedPointToBoolean: {
// Unsigned padding does not affect this.
APValue Val;
if (!Evaluate(Val, Info, SubExpr))
return false;
return Success(Val.getFixedPoint().getBoolValue(), E);
}
case CK_IntegralCast: {
if (!Visit(SubExpr))
return false;
if (!Result.isInt()) {
// Allow casts of address-of-label differences if they are no-ops
// or narrowing. (The narrowing case isn't actually guaranteed to
// be constant-evaluatable except in some narrow cases which are hard
// to detect here. We let it through on the assumption the user knows
// what they are doing.)
if (Result.isAddrLabelDiff())
return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType);
// Only allow casts of lvalues if they are lossless.
return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
}
return Success(HandleIntToIntCast(Info, E, DestType, SrcType,
Result.getInt()), E);
}
case CK_PointerToIntegral: {
CCEDiag(E, diag::note_constexpr_invalid_cast) << 2;
LValue LV;
if (!EvaluatePointer(SubExpr, LV, Info))
return false;
if (LV.getLValueBase()) {
// Only allow based lvalue casts if they are lossless.
// FIXME: Allow a larger integer size than the pointer size, and allow
// narrowing back down to pointer width in subsequent integral casts.
// FIXME: Check integer type's active bits, not its type size.
if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
return Error(E);
LV.Designator.setInvalid();
LV.moveInto(Result);
return true;
}
APSInt AsInt;
APValue V;
LV.moveInto(V);
if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx))
llvm_unreachable("Can't cast this!");
return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E);
}
case CK_IntegralComplexToReal: {
ComplexValue C;
if (!EvaluateComplex(SubExpr, C, Info))
return false;
return Success(C.getComplexIntReal(), E);
}
case CK_FloatingToIntegral: {
APFloat F(0.0);
if (!EvaluateFloat(SubExpr, F, Info))
return false;
APSInt Value;
if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value))
return false;
return Success(Value, E);
}
}
llvm_unreachable("unknown cast resulting in integral value");
}
bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info))
return false;
if (!LV.isComplexInt())
return Error(E);
return Success(LV.getComplexIntReal(), E);
}
return Visit(E->getSubExpr());
}
bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isComplexIntegerType()) {
ComplexValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info))
return false;
if (!LV.isComplexInt())
return Error(E);
return Success(LV.getComplexIntImag(), E);
}
VisitIgnoredValue(E->getSubExpr());
return Success(0, E);
}
bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) {
return Success(E->getPackLength(), E);
}
bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) {
return Success(E->getValue(), E);
}
bool IntExprEvaluator::VisitConceptSpecializationExpr(
const ConceptSpecializationExpr *E) {
return Success(E->isSatisfied(), E);
}
bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) {
return Success(E->isSatisfied(), E);
}
bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
switch (E->getOpcode()) {
default:
// Invalid unary operators
return Error(E);
case UO_Plus:
// The result is just the value.
return Visit(E->getSubExpr());
case UO_Minus: {
if (!Visit(E->getSubExpr())) return false;
if (!Result.isFixedPoint())
return Error(E);
bool Overflowed;
APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed);
if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType()))
return false;
return Success(Negated, E);
}
case UO_LNot: {
bool bres;
if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
return false;
return Success(!bres, E);
}
}
}
bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr *SubExpr = E->getSubExpr();
QualType DestType = E->getType();
assert(DestType->isFixedPointType() &&
"Expected destination type to be a fixed point type");
auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType);
switch (E->getCastKind()) {
case CK_FixedPointCast: {
APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
if (!EvaluateFixedPoint(SubExpr, Src, Info))
return false;
bool Overflowed;
APFixedPoint Result = Src.convert(DestFXSema, &Overflowed);
if (Overflowed) {
if (Info.checkingForUndefinedBehavior())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_fixedpoint_constant_overflow)
<< Result.toString() << E->getType();
if (!HandleOverflow(Info, E, Result, E->getType()))
return false;
}
return Success(Result, E);
}
case CK_IntegralToFixedPoint: {
APSInt Src;
if (!EvaluateInteger(SubExpr, Src, Info))
return false;
bool Overflowed;
APFixedPoint IntResult = APFixedPoint::getFromIntValue(
Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
if (Overflowed) {
if (Info.checkingForUndefinedBehavior())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_fixedpoint_constant_overflow)
<< IntResult.toString() << E->getType();
if (!HandleOverflow(Info, E, IntResult, E->getType()))
return false;
}
return Success(IntResult, E);
}
case CK_FloatingToFixedPoint: {
APFloat Src(0.0);
if (!EvaluateFloat(SubExpr, Src, Info))
return false;
bool Overflowed;
APFixedPoint Result = APFixedPoint::getFromFloatValue(
Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed);
if (Overflowed) {
if (Info.checkingForUndefinedBehavior())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_fixedpoint_constant_overflow)
<< Result.toString() << E->getType();
if (!HandleOverflow(Info, E, Result, E->getType()))
return false;
}
return Success(Result, E);
}
case CK_NoOp:
case CK_LValueToRValue:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
default:
return Error(E);
}
}
bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
const Expr *LHS = E->getLHS();
const Expr *RHS = E->getRHS();
FixedPointSemantics ResultFXSema =
Info.Ctx.getFixedPointSemantics(E->getType());
APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType()));
if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info))
return false;
APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType()));
if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info))
return false;
bool OpOverflow = false, ConversionOverflow = false;
APFixedPoint Result(LHSFX.getSemantics());
switch (E->getOpcode()) {
case BO_Add: {
Result = LHSFX.add(RHSFX, &OpOverflow)
.convert(ResultFXSema, &ConversionOverflow);
break;
}
case BO_Sub: {
Result = LHSFX.sub(RHSFX, &OpOverflow)
.convert(ResultFXSema, &ConversionOverflow);
break;
}
case BO_Mul: {
Result = LHSFX.mul(RHSFX, &OpOverflow)
.convert(ResultFXSema, &ConversionOverflow);
break;
}
case BO_Div: {
if (RHSFX.getValue() == 0) {
Info.FFDiag(E, diag::note_expr_divide_by_zero);
return false;
}
Result = LHSFX.div(RHSFX, &OpOverflow)
.convert(ResultFXSema, &ConversionOverflow);
break;
}
case BO_Shl:
case BO_Shr: {
FixedPointSemantics LHSSema = LHSFX.getSemantics();
llvm::APSInt RHSVal = RHSFX.getValue();
unsigned ShiftBW =
LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding();
unsigned Amt = RHSVal.getLimitedValue(ShiftBW - 1);
// Embedded-C 4.1.6.2.2:
// The right operand must be nonnegative and less than the total number
// of (nonpadding) bits of the fixed-point operand ...
if (RHSVal.isNegative())
Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal;
else if (Amt != RHSVal)
Info.CCEDiag(E, diag::note_constexpr_large_shift)
<< RHSVal << E->getType() << ShiftBW;
if (E->getOpcode() == BO_Shl)
Result = LHSFX.shl(Amt, &OpOverflow);
else
Result = LHSFX.shr(Amt, &OpOverflow);
break;
}
default:
return false;
}
if (OpOverflow || ConversionOverflow) {
if (Info.checkingForUndefinedBehavior())
Info.Ctx.getDiagnostics().Report(E->getExprLoc(),
diag::warn_fixedpoint_constant_overflow)
<< Result.toString() << E->getType();
if (!HandleOverflow(Info, E, Result, E->getType()))
return false;
}
return Success(Result, E);
}
//===----------------------------------------------------------------------===//
// Float Evaluation
//===----------------------------------------------------------------------===//
namespace {
class FloatExprEvaluator
: public ExprEvaluatorBase<FloatExprEvaluator> {
APFloat &Result;
public:
FloatExprEvaluator(EvalInfo &info, APFloat &result)
: ExprEvaluatorBaseTy(info), Result(result) {}
bool Success(const APValue &V, const Expr *e) {
Result = V.getFloat();
return true;
}
bool ZeroInitialization(const Expr *E) {
Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
return true;
}
bool VisitCallExpr(const CallExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitFloatingLiteral(const FloatingLiteral *E);
bool VisitCastExpr(const CastExpr *E);
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
// FIXME: Missing: array subscript of vector, member of vector
};
} // end anonymous namespace
static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isRealFloatingType());
return FloatExprEvaluator(Info, Result).Visit(E);
}
static bool TryEvaluateBuiltinNaN(const ASTContext &Context,
QualType ResultTy,
const Expr *Arg,
bool SNaN,
llvm::APFloat &Result) {
const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
if (!S) return false;
const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
llvm::APInt fill;
// Treat empty strings as if they were zero.
if (S->getString().empty())
fill = llvm::APInt(32, 0);
else if (S->getString().getAsInteger(0, fill))
return false;
if (Context.getTargetInfo().isNan2008()) {
if (SNaN)
Result = llvm::APFloat::getSNaN(Sem, false, &fill);
else
Result = llvm::APFloat::getQNaN(Sem, false, &fill);
} else {
// Prior to IEEE 754-2008, architectures were allowed to choose whether
// the first bit of their significand was set for qNaN or sNaN. MIPS chose
// a different encoding to what became a standard in 2008, and for pre-
// 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as
// sNaN. This is now known as "legacy NaN" encoding.
if (SNaN)
Result = llvm::APFloat::getQNaN(Sem, false, &fill);
else
Result = llvm::APFloat::getSNaN(Sem, false, &fill);
}
return true;
}
bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
switch (E->getBuiltinCallee()) {
default:
return ExprEvaluatorBaseTy::VisitCallExpr(E);
case Builtin::BI__builtin_huge_val:
case Builtin::BI__builtin_huge_valf:
case Builtin::BI__builtin_huge_vall:
case Builtin::BI__builtin_huge_valf128:
case Builtin::BI__builtin_inf:
case Builtin::BI__builtin_inff:
case Builtin::BI__builtin_infl:
case Builtin::BI__builtin_inff128: {
const llvm::fltSemantics &Sem =
Info.Ctx.getFloatTypeSemantics(E->getType());
Result = llvm::APFloat::getInf(Sem);
return true;
}
case Builtin::BI__builtin_nans:
case Builtin::BI__builtin_nansf:
case Builtin::BI__builtin_nansl:
case Builtin::BI__builtin_nansf128:
if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
true, Result))
return Error(E);
return true;
case Builtin::BI__builtin_nan:
case Builtin::BI__builtin_nanf:
case Builtin::BI__builtin_nanl:
case Builtin::BI__builtin_nanf128:
// If this is __builtin_nan() turn this into a nan, otherwise we
// can't constant fold it.
if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
false, Result))
return Error(E);
return true;
case Builtin::BI__builtin_fabs:
case Builtin::BI__builtin_fabsf:
case Builtin::BI__builtin_fabsl:
case Builtin::BI__builtin_fabsf128:
// The C standard says "fabs raises no floating-point exceptions,
// even if x is a signaling NaN. The returned value is independent of
// the current rounding direction mode." Therefore constant folding can
// proceed without regard to the floating point settings.
// Reference, WG14 N2478 F.10.4.3
if (!EvaluateFloat(E->getArg(0), Result, Info))
return false;
if (Result.isNegative())
Result.changeSign();
return true;
// FIXME: Builtin::BI__builtin_powi
// FIXME: Builtin::BI__builtin_powif
// FIXME: Builtin::BI__builtin_powil
case Builtin::BI__builtin_copysign:
case Builtin::BI__builtin_copysignf:
case Builtin::BI__builtin_copysignl:
case Builtin::BI__builtin_copysignf128: {
APFloat RHS(0.);
if (!EvaluateFloat(E->getArg(0), Result, Info) ||
!EvaluateFloat(E->getArg(1), RHS, Info))
return false;
Result.copySign(RHS);
return true;
}
}
}
bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue CV;
if (!EvaluateComplex(E->getSubExpr(), CV, Info))
return false;
Result = CV.FloatReal;
return true;
}
return Visit(E->getSubExpr());
}
bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue CV;
if (!EvaluateComplex(E->getSubExpr(), CV, Info))
return false;
Result = CV.FloatImag;
return true;
}
VisitIgnoredValue(E->getSubExpr());
const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType());
Result = llvm::APFloat::getZero(Sem);
return true;
}
bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
switch (E->getOpcode()) {
default: return Error(E);
case UO_Plus:
return EvaluateFloat(E->getSubExpr(), Result, Info);
case UO_Minus:
// In C standard, WG14 N2478 F.3 p4
// "the unary - raises no floating point exceptions,
// even if the operand is signalling."
if (!EvaluateFloat(E->getSubExpr(), Result, Info))
return false;
Result.changeSign();
return true;
}
}
bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
APFloat RHS(0.0);
bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info);
if (!LHSOK && !Info.noteFailure())
return false;
return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK &&
handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS);
}
bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
Result = E->getValue();
return true;
}
bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
const Expr* SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_IntegralToFloating: {
APSInt IntResult;
const FPOptions FPO = E->getFPFeaturesInEffect(
Info.Ctx.getLangOpts());
return EvaluateInteger(SubExpr, IntResult, Info) &&
HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(),
IntResult, E->getType(), Result);
}
case CK_FixedPointToFloating: {
APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(SubExpr->getType()));
if (!EvaluateFixedPoint(SubExpr, FixResult, Info))
return false;
Result =
FixResult.convertToFloat(Info.Ctx.getFloatTypeSemantics(E->getType()));
return true;
}
case CK_FloatingCast: {
if (!Visit(SubExpr))
return false;
return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(),
Result);
}
case CK_FloatingComplexToReal: {
ComplexValue V;
if (!EvaluateComplex(SubExpr, V, Info))
return false;
Result = V.getComplexFloatReal();
return true;
}
}
}
//===----------------------------------------------------------------------===//
// Complex Evaluation (for float and integer)
//===----------------------------------------------------------------------===//
namespace {
class ComplexExprEvaluator
: public ExprEvaluatorBase<ComplexExprEvaluator> {
ComplexValue &Result;
public:
ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result)
: ExprEvaluatorBaseTy(info), Result(Result) {}
bool Success(const APValue &V, const Expr *e) {
Result.setFrom(V);
return true;
}
bool ZeroInitialization(const Expr *E);
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitImaginaryLiteral(const ImaginaryLiteral *E);
bool VisitCastExpr(const CastExpr *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitCallExpr(const CallExpr *E);
};
} // end anonymous namespace
static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isAnyComplexType());
return ComplexExprEvaluator(Info, Result).Visit(E);
}
bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) {
QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType();
if (ElemTy->isRealFloatingType()) {
Result.makeComplexFloat();
APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy));
Result.FloatReal = Zero;
Result.FloatImag = Zero;
} else {
Result.makeComplexInt();
APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy);
Result.IntReal = Zero;
Result.IntImag = Zero;
}
return true;
}
bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) {
const Expr* SubExpr = E->getSubExpr();
if (SubExpr->getType()->isRealFloatingType()) {
Result.makeComplexFloat();
APFloat &Imag = Result.FloatImag;
if (!EvaluateFloat(SubExpr, Imag, Info))
return false;
Result.FloatReal = APFloat(Imag.getSemantics());
return true;
} else {
assert(SubExpr->getType()->isIntegerType() &&
"Unexpected imaginary literal.");
Result.makeComplexInt();
APSInt &Imag = Result.IntImag;
if (!EvaluateInteger(SubExpr, Imag, Info))
return false;
Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned());
return true;
}
}
bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
case CK_BitCast:
case CK_BaseToDerived:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:
case CK_Dynamic:
case CK_ToUnion:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToPointer:
case CK_NullToMemberPointer:
case CK_BaseToDerivedMemberPointer:
case CK_DerivedToBaseMemberPointer:
case CK_MemberPointerToBoolean:
case CK_ReinterpretMemberPointer:
case CK_ConstructorConversion:
case CK_IntegralToPointer:
case CK_PointerToIntegral:
case CK_PointerToBoolean:
case CK_ToVoid:
case CK_VectorSplat:
case CK_IntegralCast:
case CK_BooleanToSignedIntegral:
case CK_IntegralToBoolean:
case CK_IntegralToFloating:
case CK_FloatingToIntegral:
case CK_FloatingToBoolean:
case CK_FloatingCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:
case CK_ObjCObjectLValueCast:
case CK_FloatingComplexToReal:
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToReal:
case CK_IntegralComplexToBoolean:
case CK_ARCProduceObject:
case CK_ARCConsumeObject:
case CK_ARCReclaimReturnedObject:
case CK_ARCExtendBlockObject:
case CK_CopyAndAutoreleaseBlockObject:
case CK_BuiltinFnToFnPtr:
case CK_ZeroToOCLOpaqueType:
case CK_NonAtomicToAtomic:
case CK_AddressSpaceConversion:
case CK_IntToOCLSampler:
case CK_FloatingToFixedPoint:
case CK_FixedPointToFloating:
case CK_FixedPointCast:
case CK_FixedPointToBoolean:
case CK_FixedPointToIntegral:
case CK_IntegralToFixedPoint:
case CK_MatrixCast:
llvm_unreachable("invalid cast kind for complex value");
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
case CK_LValueToRValueBitCast:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_Dependent:
case CK_LValueBitCast:
case CK_UserDefinedConversion:
return Error(E);
case CK_FloatingRealToComplex: {
APFloat &Real = Result.FloatReal;
if (!EvaluateFloat(E->getSubExpr(), Real, Info))
return false;
Result.makeComplexFloat();
Result.FloatImag = APFloat(Real.getSemantics());
return true;
}
case CK_FloatingComplexCast: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->castAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) &&
HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag);
}
case CK_FloatingComplexToIntegralComplex: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->castAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
Result.makeComplexInt();
return HandleFloatToIntCast(Info, E, From, Result.FloatReal,
To, Result.IntReal) &&
HandleFloatToIntCast(Info, E, From, Result.FloatImag,
To, Result.IntImag);
}
case CK_IntegralRealToComplex: {
APSInt &Real = Result.IntReal;
if (!EvaluateInteger(E->getSubExpr(), Real, Info))
return false;
Result.makeComplexInt();
Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned());
return true;
}
case CK_IntegralComplexCast: {
if (!Visit(E->getSubExpr()))
return false;
QualType To = E->getType()->castAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal);
Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag);
return true;
}
case CK_IntegralComplexToFloatingComplex: {
if (!Visit(E->getSubExpr()))
return false;
const FPOptions FPO = E->getFPFeaturesInEffect(
Info.Ctx.getLangOpts());
QualType To = E->getType()->castAs<ComplexType>()->getElementType();
QualType From
= E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType();
Result.makeComplexFloat();
return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal,
To, Result.FloatReal) &&
HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag,
To, Result.FloatImag);
}
}
llvm_unreachable("unknown cast resulting in complex value");
}
bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma)
return ExprEvaluatorBaseTy::VisitBinaryOperator(E);
// Track whether the LHS or RHS is real at the type system level. When this is
// the case we can simplify our evaluation strategy.
bool LHSReal = false, RHSReal = false;
bool LHSOK;
if (E->getLHS()->getType()->isRealFloatingType()) {
LHSReal = true;
APFloat &Real = Result.FloatReal;
LHSOK = EvaluateFloat(E->getLHS(), Real, Info);
if (LHSOK) {
Result.makeComplexFloat();
Result.FloatImag = APFloat(Real.getSemantics());
}
} else {
LHSOK = Visit(E->getLHS());
}
if (!LHSOK && !Info.noteFailure())
return false;
ComplexValue RHS;
if (E->getRHS()->getType()->isRealFloatingType()) {
RHSReal = true;
APFloat &Real = RHS.FloatReal;
if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK)
return false;
RHS.makeComplexFloat();
RHS.FloatImag = APFloat(Real.getSemantics());
} else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK)
return false;
assert(!(LHSReal && RHSReal) &&
"Cannot have both operands of a complex operation be real.");
switch (E->getOpcode()) {
default: return Error(E);
case BO_Add:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
if (LHSReal)
Result.getComplexFloatImag() = RHS.getComplexFloatImag();
else if (!RHSReal)
Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
} else {
Result.getComplexIntReal() += RHS.getComplexIntReal();
Result.getComplexIntImag() += RHS.getComplexIntImag();
}
break;
case BO_Sub:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
if (LHSReal) {
Result.getComplexFloatImag() = RHS.getComplexFloatImag();
Result.getComplexFloatImag().changeSign();
} else if (!RHSReal) {
Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
}
} else {
Result.getComplexIntReal() -= RHS.getComplexIntReal();
Result.getComplexIntImag() -= RHS.getComplexIntImag();
}
break;
case BO_Mul:
if (Result.isComplexFloat()) {
// This is an implementation of complex multiplication according to the
// constraints laid out in C11 Annex G. The implementation uses the
// following naming scheme:
// (a + ib) * (c + id)
ComplexValue LHS = Result;
APFloat &A = LHS.getComplexFloatReal();
APFloat &B = LHS.getComplexFloatImag();
APFloat &C = RHS.getComplexFloatReal();
APFloat &D = RHS.getComplexFloatImag();
APFloat &ResR = Result.getComplexFloatReal();
APFloat &ResI = Result.getComplexFloatImag();
if (LHSReal) {
assert(!RHSReal && "Cannot have two real operands for a complex op!");
ResR = A * C;
ResI = A * D;
} else if (RHSReal) {
ResR = C * A;
ResI = C * B;
} else {
// In the fully general case, we need to handle NaNs and infinities
// robustly.
APFloat AC = A * C;
APFloat BD = B * D;
APFloat AD = A * D;
APFloat BC = B * C;
ResR = AC - BD;
ResI = AD + BC;
if (ResR.isNaN() && ResI.isNaN()) {
bool Recalc = false;
if (A.isInfinity() || B.isInfinity()) {
A = APFloat::copySign(
APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
B = APFloat::copySign(
APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
if (C.isNaN())
C = APFloat::copySign(APFloat(C.getSemantics()), C);
if (D.isNaN())
D = APFloat::copySign(APFloat(D.getSemantics()), D);
Recalc = true;
}
if (C.isInfinity() || D.isInfinity()) {
C = APFloat::copySign(
APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
D = APFloat::copySign(
APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
if (A.isNaN())
A = APFloat::copySign(APFloat(A.getSemantics()), A);
if (B.isNaN())
B = APFloat::copySign(APFloat(B.getSemantics()), B);
Recalc = true;
}
if (!Recalc && (AC.isInfinity() || BD.isInfinity() ||
AD.isInfinity() || BC.isInfinity())) {
if (A.isNaN())
A = APFloat::copySign(APFloat(A.getSemantics()), A);
if (B.isNaN())
B = APFloat::copySign(APFloat(B.getSemantics()), B);
if (C.isNaN())
C = APFloat::copySign(APFloat(C.getSemantics()), C);
if (D.isNaN())
D = APFloat::copySign(APFloat(D.getSemantics()), D);
Recalc = true;
}
if (Recalc) {
ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D);
ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C);
}
}
}
} else {
ComplexValue LHS = Result;
Result.getComplexIntReal() =
(LHS.getComplexIntReal() * RHS.getComplexIntReal() -
LHS.getComplexIntImag() * RHS.getComplexIntImag());
Result.getComplexIntImag() =
(LHS.getComplexIntReal() * RHS.getComplexIntImag() +
LHS.getComplexIntImag() * RHS.getComplexIntReal());
}
break;
case BO_Div:
if (Result.isComplexFloat()) {
// This is an implementation of complex division according to the
// constraints laid out in C11 Annex G. The implementation uses the
// following naming scheme:
// (a + ib) / (c + id)
ComplexValue LHS = Result;
APFloat &A = LHS.getComplexFloatReal();
APFloat &B = LHS.getComplexFloatImag();
APFloat &C = RHS.getComplexFloatReal();
APFloat &D = RHS.getComplexFloatImag();
APFloat &ResR = Result.getComplexFloatReal();
APFloat &ResI = Result.getComplexFloatImag();
if (RHSReal) {
ResR = A / C;
ResI = B / C;
} else {
if (LHSReal) {
// No real optimizations we can do here, stub out with zero.
B = APFloat::getZero(A.getSemantics());
}
int DenomLogB = 0;
APFloat MaxCD = maxnum(abs(C), abs(D));
if (MaxCD.isFinite()) {
DenomLogB = ilogb(MaxCD);
C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven);
D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven);
}
APFloat Denom = C * C + D * D;
ResR = scalbn((A * C + B * D) / Denom, -DenomLogB,
APFloat::rmNearestTiesToEven);
ResI = scalbn((B * C - A * D) / Denom, -DenomLogB,
APFloat::rmNearestTiesToEven);
if (ResR.isNaN() && ResI.isNaN()) {
if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) {
ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A;
ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B;
} else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() &&
D.isFinite()) {
A = APFloat::copySign(
APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A);
B = APFloat::copySign(
APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B);
ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D);
ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D);
} else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) {
C = APFloat::copySign(
APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C);
D = APFloat::copySign(
APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D);
ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D);
ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D);
}
}
}
} else {
if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0)
return Error(E, diag::note_expr_divide_by_zero);
ComplexValue LHS = Result;
APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() +
RHS.getComplexIntImag() * RHS.getComplexIntImag();
Result.getComplexIntReal() =
(LHS.getComplexIntReal() * RHS.getComplexIntReal() +
LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den;
Result.getComplexIntImag() =
(LHS.getComplexIntImag() * RHS.getComplexIntReal() -
LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den;
}
break;
}
return true;
}
bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
// Get the operand value into 'Result'.
if (!Visit(E->getSubExpr()))
return false;
switch (E->getOpcode()) {
default:
return Error(E);
case UO_Extension:
return true;
case UO_Plus:
// The result is always just the subexpr.
return true;
case UO_Minus:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().changeSign();
Result.getComplexFloatImag().changeSign();
}
else {
Result.getComplexIntReal() = -Result.getComplexIntReal();
Result.getComplexIntImag() = -Result.getComplexIntImag();
}
return true;
case UO_Not:
if (Result.isComplexFloat())
Result.getComplexFloatImag().changeSign();
else
Result.getComplexIntImag() = -Result.getComplexIntImag();
return true;
}
}
bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
if (E->getNumInits() == 2) {
if (E->getType()->isComplexType()) {
Result.makeComplexFloat();
if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info))
return false;
if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info))
return false;
} else {
Result.makeComplexInt();
if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info))
return false;
if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info))
return false;
}
return true;
}
return ExprEvaluatorBaseTy::VisitInitListExpr(E);
}
bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) {
switch (E->getBuiltinCallee()) {
case Builtin::BI__builtin_complex:
Result.makeComplexFloat();
if (!EvaluateFloat(E->getArg(0), Result.FloatReal, Info))
return false;
if (!EvaluateFloat(E->getArg(1), Result.FloatImag, Info))
return false;
return true;
default:
break;
}
return ExprEvaluatorBaseTy::VisitCallExpr(E);
}
//===----------------------------------------------------------------------===//
// Atomic expression evaluation, essentially just handling the NonAtomicToAtomic
// implicit conversion.
//===----------------------------------------------------------------------===//
namespace {
class AtomicExprEvaluator :
public ExprEvaluatorBase<AtomicExprEvaluator> {
const LValue *This;
APValue &Result;
public:
AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result)
: ExprEvaluatorBaseTy(Info), This(This), Result(Result) {}
bool Success(const APValue &V, const Expr *E) {
Result = V;
return true;
}
bool ZeroInitialization(const Expr *E) {
ImplicitValueInitExpr VIE(
E->getType()->castAs<AtomicType>()->getValueType());
// For atomic-qualified class (and array) types in C++, initialize the
// _Atomic-wrapped subobject directly, in-place.
return This ? EvaluateInPlace(Result, Info, *This, &VIE)
: Evaluate(Result, Info, &VIE);
}
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_NonAtomicToAtomic:
return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr())
: Evaluate(Result, Info, E->getSubExpr());
}
}
};
} // end anonymous namespace
static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result,
EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isAtomicType());
return AtomicExprEvaluator(Info, This, Result).Visit(E);
}
//===----------------------------------------------------------------------===//
// Void expression evaluation, primarily for a cast to void on the LHS of a
// comma operator
//===----------------------------------------------------------------------===//
namespace {
class VoidExprEvaluator
: public ExprEvaluatorBase<VoidExprEvaluator> {
public:
VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {}
bool Success(const APValue &V, const Expr *e) { return true; }
bool ZeroInitialization(const Expr *E) { return true; }
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_ToVoid:
VisitIgnoredValue(E->getSubExpr());
return true;
}
}
bool VisitCallExpr(const CallExpr *E) {
switch (E->getBuiltinCallee()) {
case Builtin::BI__assume:
case Builtin::BI__builtin_assume:
// The argument is not evaluated!
return true;
case Builtin::BI__builtin_operator_delete:
return HandleOperatorDeleteCall(Info, E);
default:
break;
}
return ExprEvaluatorBaseTy::VisitCallExpr(E);
}
bool VisitCXXDeleteExpr(const CXXDeleteExpr *E);
};
} // end anonymous namespace
bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) {
// We cannot speculatively evaluate a delete expression.
if (Info.SpeculativeEvaluationDepth)
return false;
FunctionDecl *OperatorDelete = E->getOperatorDelete();
if (!OperatorDelete->isReplaceableGlobalAllocationFunction()) {
Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
<< isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete;
return false;
}
const Expr *Arg = E->getArgument();
LValue Pointer;
if (!EvaluatePointer(Arg, Pointer, Info))
return false;
if (Pointer.Designator.Invalid)
return false;
// Deleting a null pointer has no effect.
if (Pointer.isNullPointer()) {
// This is the only case where we need to produce an extension warning:
// the only other way we can succeed is if we find a dynamic allocation,
// and we will have warned when we allocated it in that case.
if (!Info.getLangOpts().CPlusPlus20)
Info.CCEDiag(E, diag::note_constexpr_new);
return true;
}
Optional<DynAlloc *> Alloc = CheckDeleteKind(
Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New);
if (!Alloc)
return false;
QualType AllocType = Pointer.Base.getDynamicAllocType();
// For the non-array case, the designator must be empty if the static type
// does not have a virtual destructor.
if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 &&
!hasVirtualDestructor(Arg->getType()->getPointeeType())) {
Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor)
<< Arg->getType()->getPointeeType() << AllocType;
return false;
}
// For a class type with a virtual destructor, the selected operator delete
// is the one looked up when building the destructor.
if (!E->isArrayForm() && !E->isGlobalDelete()) {
const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(AllocType);
if (VirtualDelete &&
!VirtualDelete->isReplaceableGlobalAllocationFunction()) {
Info.FFDiag(E, diag::note_constexpr_new_non_replaceable)
<< isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete;
return false;
}
}
if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(),
(*Alloc)->Value, AllocType))
return false;
if (!Info.HeapAllocs.erase(Pointer.Base.dyn_cast<DynamicAllocLValue>())) {
// The element was already erased. This means the destructor call also
// deleted the object.
// FIXME: This probably results in undefined behavior before we get this
// far, and should be diagnosed elsewhere first.
Info.FFDiag(E, diag::note_constexpr_double_delete);
return false;
}
return true;
}
static bool EvaluateVoid(const Expr *E, EvalInfo &Info) {
assert(!E->isValueDependent());
assert(E->isRValue() && E->getType()->isVoidType());
return VoidExprEvaluator(Info).Visit(E);
}
//===----------------------------------------------------------------------===//
// Top level Expr::EvaluateAsRValue method.
//===----------------------------------------------------------------------===//
static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
assert(!E->isValueDependent());
// In C, function designators are not lvalues, but we evaluate them as if they
// are.
QualType T = E->getType();
if (E->isGLValue() || T->isFunctionType()) {
LValue LV;
if (!EvaluateLValue(E, LV, Info))
return false;
LV.moveInto(Result);
} else if (T->isVectorType()) {
if (!EvaluateVector(E, Result, Info))
return false;
} else if (T->isIntegralOrEnumerationType()) {
if (!IntExprEvaluator(Info, Result).Visit(E))
return false;
} else if (T->hasPointerRepresentation()) {
LValue LV;
if (!EvaluatePointer(E, LV, Info))
return false;
LV.moveInto(Result);
} else if (T->isRealFloatingType()) {
llvm::APFloat F(0.0);
if (!EvaluateFloat(E, F, Info))
return false;
Result = APValue(F);
} else if (T->isAnyComplexType()) {
ComplexValue C;
if (!EvaluateComplex(E, C, Info))
return false;
C.moveInto(Result);
} else if (T->isFixedPointType()) {
if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false;
} else if (T->isMemberPointerType()) {
MemberPtr P;
if (!EvaluateMemberPointer(E, P, Info))
return false;
P.moveInto(Result);
return true;
} else if (T->isArrayType()) {
LValue LV;
APValue &Value =
Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
if (!EvaluateArray(E, LV, Value, Info))
return false;
Result = Value;
} else if (T->isRecordType()) {
LValue LV;
APValue &Value =
Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV);
if (!EvaluateRecord(E, LV, Value, Info))
return false;
Result = Value;
} else if (T->isVoidType()) {
if (!Info.getLangOpts().CPlusPlus11)
Info.CCEDiag(E, diag::note_constexpr_nonliteral)
<< E->getType();
if (!EvaluateVoid(E, Info))
return false;
} else if (T->isAtomicType()) {
QualType Unqual = T.getAtomicUnqualifiedType();
if (Unqual->isArrayType() || Unqual->isRecordType()) {
LValue LV;
APValue &Value = Info.CurrentCall->createTemporary(
E, Unqual, ScopeKind::FullExpression, LV);
if (!EvaluateAtomic(E, &LV, Value, Info))
return false;
} else {
if (!EvaluateAtomic(E, nullptr, Result, Info))
return false;
}
} else if (Info.getLangOpts().CPlusPlus11) {
Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType();
return false;
} else {
Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr);
return false;
}
return true;
}
/// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some
/// cases, the in-place evaluation is essential, since later initializers for
/// an object can indirectly refer to subobjects which were initialized earlier.
static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This,
const Expr *E, bool AllowNonLiteralTypes) {
assert(!E->isValueDependent());
if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This))
return false;
if (E->isRValue()) {
// Evaluate arrays and record types in-place, so that later initializers can
// refer to earlier-initialized members of the object.
QualType T = E->getType();
if (T->isArrayType())
return EvaluateArray(E, This, Result, Info);
else if (T->isRecordType())
return EvaluateRecord(E, This, Result, Info);
else if (T->isAtomicType()) {
QualType Unqual = T.getAtomicUnqualifiedType();
if (Unqual->isArrayType() || Unqual->isRecordType())
return EvaluateAtomic(E, &This, Result, Info);
}
}
// For any other type, in-place evaluation is unimportant.
return Evaluate(Result, Info, E);
}
/// EvaluateAsRValue - Try to evaluate this expression, performing an implicit
/// lvalue-to-rvalue cast if it is an lvalue.
static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) {
assert(!E->isValueDependent());
if (Info.EnableNewConstInterp) {
if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result))
return false;
} else {
if (E->getType().isNull())
return false;
if (!CheckLiteralType(Info, E))
return false;
if (!::Evaluate(Result, Info, E))
return false;
if (E->isGLValue()) {
LValue LV;
LV.setFrom(Info.Ctx, Result);
if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result))
return false;
}
}
// Check this core constant expression is a constant expression.
return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result,
ConstantExprKind::Normal) &&
CheckMemoryLeaks(Info);
}
static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result,
const ASTContext &Ctx, bool &IsConst) {
// Fast-path evaluations of integer literals, since we sometimes see files
// containing vast quantities of these.
if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) {
Result.Val = APValue(APSInt(L->getValue(),
L->getType()->isUnsignedIntegerType()));
IsConst = true;
return true;
}
// This case should be rare, but we need to check it before we check on
// the type below.
if (Exp->getType().isNull()) {
IsConst = false;
return true;
}
// FIXME: Evaluating values of large array and record types can cause
// performance problems. Only do so in C++11 for now.
if (Exp->isRValue() && (Exp->getType()->isArrayType() ||
Exp->getType()->isRecordType()) &&
!Ctx.getLangOpts().CPlusPlus11) {
IsConst = false;
return true;
}
return false;
}
static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result,
Expr::SideEffectsKind SEK) {
return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) ||
(SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior);
}
static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result,
const ASTContext &Ctx, EvalInfo &Info) {
assert(!E->isValueDependent());
bool IsConst;
if (FastEvaluateAsRValue(E, Result, Ctx, IsConst))
return IsConst;
return EvaluateAsRValue(Info, E, Result.Val);
}
static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult,
const ASTContext &Ctx,
Expr::SideEffectsKind AllowSideEffects,
EvalInfo &Info) {
assert(!E->isValueDependent());
if (!E->getType()->isIntegralOrEnumerationType())
return false;
if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) ||
!ExprResult.Val.isInt() ||
hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
return false;
return true;
}
static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult,
const ASTContext &Ctx,
Expr::SideEffectsKind AllowSideEffects,
EvalInfo &Info) {
assert(!E->isValueDependent());
if (!E->getType()->isFixedPointType())
return false;
if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info))
return false;
if (!ExprResult.Val.isFixedPoint() ||
hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
return false;
return true;
}
/// EvaluateAsRValue - Return true if this is a constant which we can fold using
/// any crazy technique (that has nothing to do with language standards) that
/// we want to. If this function returns true, it returns the folded constant
/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
/// will be applied to the result.
bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = InConstantContext;
return ::EvaluateAsRValue(this, Result, Ctx, Info);
}
bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalResult Scratch;
return EvaluateAsRValue(Scratch, Ctx, InConstantContext) &&
HandleConversionToBool(Scratch.Val, Result);
}
bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = InConstantContext;
return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info);
}
bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = InConstantContext;
return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info);
}
bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx,
SideEffectsKind AllowSideEffects,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
if (!getType()->isRealFloatingType())
return false;
EvalResult ExprResult;
if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) ||
!ExprResult.Val.isFloat() ||
hasUnacceptableSideEffect(ExprResult, AllowSideEffects))
return false;
Result = ExprResult.Val.getFloat();
return true;
}
bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx,
bool InConstantContext) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold);
Info.InConstantContext = InConstantContext;
LValue LV;
CheckedTemporaries CheckedTemps;
if (!EvaluateLValue(this, LV, Info) || !Info.discardCleanups() ||
Result.HasSideEffects ||
!CheckLValueConstantExpression(Info, getExprLoc(),
Ctx.getLValueReferenceType(getType()), LV,
ConstantExprKind::Normal, CheckedTemps))
return false;
LV.moveInto(Result.Val);
return true;
}
static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base,
APValue DestroyedValue, QualType Type,
SourceLocation Loc, Expr::EvalStatus &EStatus,
bool IsConstantDestruction) {
EvalInfo Info(Ctx, EStatus,
IsConstantDestruction ? EvalInfo::EM_ConstantExpression
: EvalInfo::EM_ConstantFold);
Info.setEvaluatingDecl(Base, DestroyedValue,
EvalInfo::EvaluatingDeclKind::Dtor);
Info.InConstantContext = IsConstantDestruction;
LValue LVal;
LVal.set(Base);
if (!HandleDestruction(Info, Loc, Base, DestroyedValue, Type) ||
EStatus.HasSideEffects)
return false;
if (!Info.discardCleanups())
llvm_unreachable("Unhandled cleanup; missing full expression marker?");
return true;
}
bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx,
ConstantExprKind Kind) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression;
EvalInfo Info(Ctx, Result, EM);
Info.InConstantContext = true;
// The type of the object we're initializing is 'const T' for a class NTTP.
QualType T = getType();
if (Kind == ConstantExprKind::ClassTemplateArgument)
T.addConst();
// If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to
// represent the result of the evaluation. CheckConstantExpression ensures
// this doesn't escape.
MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true);
APValue::LValueBase Base(&BaseMTE);
Info.setEvaluatingDecl(Base, Result.Val);
LValue LVal;
LVal.set(Base);
if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects)
return false;
if (!Info.discardCleanups())
llvm_unreachable("Unhandled cleanup; missing full expression marker?");
if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this),
Result.Val, Kind))
return false;
if (!CheckMemoryLeaks(Info))
return false;
// If this is a class template argument, it's required to have constant
// destruction too.
if (Kind == ConstantExprKind::ClassTemplateArgument &&
(!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result,
true) ||
Result.HasSideEffects)) {
// FIXME: Prefix a note to indicate that the problem is lack of constant
// destruction.
return false;
}
return true;
}
bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx,
const VarDecl *VD,
SmallVectorImpl<PartialDiagnosticAt> &Notes,
bool IsConstantInitialization) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
// FIXME: Evaluating initializers for large array and record types can cause
// performance problems. Only do so in C++11 for now.
if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) &&
!Ctx.getLangOpts().CPlusPlus11)
return false;
Expr::EvalStatus EStatus;
EStatus.Diag = &Notes;
EvalInfo Info(Ctx, EStatus,
(IsConstantInitialization && Ctx.getLangOpts().CPlusPlus11)
? EvalInfo::EM_ConstantExpression
: EvalInfo::EM_ConstantFold);
Info.setEvaluatingDecl(VD, Value);
Info.InConstantContext = IsConstantInitialization;
SourceLocation DeclLoc = VD->getLocation();
QualType DeclTy = VD->getType();
if (Info.EnableNewConstInterp) {
auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext();
if (!InterpCtx.evaluateAsInitializer(Info, VD, Value))
return false;
} else {
LValue LVal;
LVal.set(VD);
if (!EvaluateInPlace(Value, Info, LVal, this,
/*AllowNonLiteralTypes=*/true) ||
EStatus.HasSideEffects)
return false;
// At this point, any lifetime-extended temporaries are completely
// initialized.
Info.performLifetimeExtension();
if (!Info.discardCleanups())
llvm_unreachable("Unhandled cleanup; missing full expression marker?");
}
return CheckConstantExpression(Info, DeclLoc, DeclTy, Value,
ConstantExprKind::Normal) &&
CheckMemoryLeaks(Info);
}
bool VarDecl::evaluateDestruction(
SmallVectorImpl<PartialDiagnosticAt> &Notes) const {
Expr::EvalStatus EStatus;
EStatus.Diag = &Notes;
// Only treat the destruction as constant destruction if we formally have
// constant initialization (or are usable in a constant expression).
bool IsConstantDestruction = hasConstantInitialization();
// Make a copy of the value for the destructor to mutate, if we know it.
// Otherwise, treat the value as default-initialized; if the destructor works
// anyway, then the destruction is constant (and must be essentially empty).
APValue DestroyedValue;
if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent())
DestroyedValue = *getEvaluatedValue();
else if (!getDefaultInitValue(getType(), DestroyedValue))
return false;
if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue),
getType(), getLocation(), EStatus,
IsConstantDestruction) ||
EStatus.HasSideEffects)
return false;
ensureEvaluatedStmt()->HasConstantDestruction = true;
return true;
}
/// isEvaluatable - Call EvaluateAsRValue to see if this expression can be
/// constant folded, but discard the result.
bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalResult Result;
return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) &&
!hasUnacceptableSideEffect(Result, SEK);
}
APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx,
SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalResult EVResult;
EVResult.Diag = Diag;
EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = true;
bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info);
(void)Result;
assert(Result && "Could not evaluate expression");
assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
return EVResult.Val.getInt();
}
APSInt Expr::EvaluateKnownConstIntCheckOverflow(
const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
EvalResult EVResult;
EVResult.Diag = Diag;
EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = true;
Info.CheckingForUndefinedBehavior = true;
bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val);
(void)Result;
assert(Result && "Could not evaluate expression");
assert(EVResult.Val.isInt() && "Expression did not evaluate to integer");
return EVResult.Val.getInt();
}
void Expr::EvaluateForOverflow(const ASTContext &Ctx) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
bool IsConst;
EvalResult EVResult;
if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) {
EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects);
Info.CheckingForUndefinedBehavior = true;
(void)::EvaluateAsRValue(Info, this, EVResult.Val);
}
}
bool Expr::EvalResult::isGlobalLValue() const {
assert(Val.isLValue());
return IsGlobalLValue(Val.getLValueBase());
}
/// isIntegerConstantExpr - this recursive routine will test if an expression is
/// an integer constant expression.
/// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero,
/// comma, etc
// CheckICE - This function does the fundamental ICE checking: the returned
// ICEDiag contains an ICEKind indicating whether the expression is an ICE,
// and a (possibly null) SourceLocation indicating the location of the problem.
//
// Note that to reduce code duplication, this helper does no evaluation
// itself; the caller checks whether the expression is evaluatable, and
// in the rare cases where CheckICE actually cares about the evaluated
// value, it calls into Evaluate.
namespace {
enum ICEKind {
/// This expression is an ICE.
IK_ICE,
/// This expression is not an ICE, but if it isn't evaluated, it's
/// a legal subexpression for an ICE. This return value is used to handle
/// the comma operator in C99 mode, and non-constant subexpressions.
IK_ICEIfUnevaluated,
/// This expression is not an ICE, and is not a legal subexpression for one.
IK_NotICE
};
struct ICEDiag {
ICEKind Kind;
SourceLocation Loc;
ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {}
};
}
static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); }
static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; }
static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) {
Expr::EvalResult EVResult;
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
Info.InConstantContext = true;
if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects ||
!EVResult.Val.isInt())
return ICEDiag(IK_NotICE, E->getBeginLoc());
return NoDiag();
}
static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
assert(!E->isValueDependent() && "Should not see value dependent exprs!");
if (!E->getType()->isIntegralOrEnumerationType())
return ICEDiag(IK_NotICE, E->getBeginLoc());
switch (E->getStmtClass()) {
#define ABSTRACT_STMT(Node)
#define STMT(Node, Base) case Expr::Node##Class:
#define EXPR(Node, Base)
#include "clang/AST/StmtNodes.inc"
case Expr::PredefinedExprClass:
case Expr::FloatingLiteralClass:
case Expr::ImaginaryLiteralClass:
case Expr::StringLiteralClass:
case Expr::ArraySubscriptExprClass:
case Expr::MatrixSubscriptExprClass:
case Expr::OMPArraySectionExprClass:
case Expr::OMPArrayShapingExprClass:
case Expr::OMPIteratorExprClass:
case Expr::MemberExprClass:
case Expr::CompoundAssignOperatorClass:
case Expr::CompoundLiteralExprClass:
case Expr::ExtVectorElementExprClass:
case Expr::DesignatedInitExprClass:
case Expr::ArrayInitLoopExprClass:
case Expr::ArrayInitIndexExprClass:
case Expr::NoInitExprClass:
case Expr::DesignatedInitUpdateExprClass:
case Expr::ImplicitValueInitExprClass:
case Expr::ParenListExprClass:
case Expr::VAArgExprClass:
case Expr::AddrLabelExprClass:
case Expr::StmtExprClass:
case Expr::CXXMemberCallExprClass:
case Expr::CUDAKernelCallExprClass:
case Expr::CXXAddrspaceCastExprClass:
case Expr::CXXDynamicCastExprClass:
case Expr::CXXTypeidExprClass:
case Expr::CXXUuidofExprClass:
case Expr::MSPropertyRefExprClass:
case Expr::MSPropertySubscriptExprClass:
case Expr::CXXNullPtrLiteralExprClass:
case Expr::UserDefinedLiteralClass:
case Expr::CXXThisExprClass:
case Expr::CXXThrowExprClass:
case Expr::CXXNewExprClass:
case Expr::CXXDeleteExprClass:
case Expr::CXXPseudoDestructorExprClass:
case Expr::UnresolvedLookupExprClass:
case Expr::TypoExprClass:
case Expr::RecoveryExprClass:
case Expr::DependentScopeDeclRefExprClass:
case Expr::CXXConstructExprClass:
case Expr::CXXInheritedCtorInitExprClass:
case Expr::CXXStdInitializerListExprClass:
case Expr::CXXBindTemporaryExprClass:
case Expr::ExprWithCleanupsClass:
case Expr::CXXTemporaryObjectExprClass:
case Expr::CXXUnresolvedConstructExprClass:
case Expr::CXXDependentScopeMemberExprClass:
case Expr::UnresolvedMemberExprClass:
case Expr::ObjCStringLiteralClass:
case Expr::ObjCBoxedExprClass:
case Expr::ObjCArrayLiteralClass:
case Expr::ObjCDictionaryLiteralClass:
case Expr::ObjCEncodeExprClass:
case Expr::ObjCMessageExprClass:
case Expr::ObjCSelectorExprClass:
case Expr::ObjCProtocolExprClass:
case Expr::ObjCIvarRefExprClass:
case Expr::ObjCPropertyRefExprClass:
case Expr::ObjCSubscriptRefExprClass:
case Expr::ObjCIsaExprClass:
case Expr::ObjCAvailabilityCheckExprClass:
case Expr::ShuffleVectorExprClass:
case Expr::ConvertVectorExprClass:
case Expr::BlockExprClass:
case Expr::NoStmtClass:
case Expr::OpaqueValueExprClass:
case Expr::PackExpansionExprClass:
case Expr::SubstNonTypeTemplateParmPackExprClass:
case Expr::FunctionParmPackExprClass:
case Expr::AsTypeExprClass:
case Expr::ObjCIndirectCopyRestoreExprClass:
case Expr::MaterializeTemporaryExprClass:
case Expr::PseudoObjectExprClass:
case Expr::AtomicExprClass:
case Expr::LambdaExprClass:
case Expr::CXXFoldExprClass:
case Expr::CoawaitExprClass:
case Expr::DependentCoawaitExprClass:
case Expr::CoyieldExprClass:
return ICEDiag(IK_NotICE, E->getBeginLoc());
case Expr::InitListExprClass: {
// C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the
// form "T x = { a };" is equivalent to "T x = a;".
// Unless we're initializing a reference, T is a scalar as it is known to be
// of integral or enumeration type.
if (E->isRValue())
if (cast<InitListExpr>(E)->getNumInits() == 1)
return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx);
return ICEDiag(IK_NotICE, E->getBeginLoc());
}
case Expr::SizeOfPackExprClass:
case Expr::GNUNullExprClass:
case Expr::SourceLocExprClass:
return NoDiag();
case Expr::SubstNonTypeTemplateParmExprClass:
return
CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx);
case Expr::ConstantExprClass:
return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx);
case Expr::ParenExprClass:
return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx);
case Expr::GenericSelectionExprClass:
return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx);
case Expr::IntegerLiteralClass:
case Expr::FixedPointLiteralClass:
case Expr::CharacterLiteralClass:
case Expr::ObjCBoolLiteralExprClass:
case Expr::CXXBoolLiteralExprClass:
case Expr::CXXScalarValueInitExprClass:
case Expr::TypeTraitExprClass:
case Expr::ConceptSpecializationExprClass:
case Expr::RequiresExprClass:
case Expr::ArrayTypeTraitExprClass:
case Expr::ExpressionTraitExprClass:
case Expr::CXXNoexceptExprClass:
return NoDiag();
case Expr::CallExprClass:
case Expr::CXXOperatorCallExprClass: {
// C99 6.6/3 allows function calls within unevaluated subexpressions of
// constant expressions, but they can never be ICEs because an ICE cannot
// contain an operand of (pointer to) function type.
const CallExpr *CE = cast<CallExpr>(E);
if (CE->getBuiltinCallee())
return CheckEvalInICE(E, Ctx);
return ICEDiag(IK_NotICE, E->getBeginLoc());
}
case Expr::CXXRewrittenBinaryOperatorClass:
return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(),
Ctx);
case Expr::DeclRefExprClass: {
const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl();
if (isa<EnumConstantDecl>(D))
return NoDiag();
// C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified
// integer variables in constant expressions:
//
// C++ 7.1.5.1p2
// A variable of non-volatile const-qualified integral or enumeration
// type initialized by an ICE can be used in ICEs.
//
// We sometimes use CheckICE to check the C++98 rules in C++11 mode. In
// that mode, use of reference variables should not be allowed.
const VarDecl *VD = dyn_cast<VarDecl>(D);
if (VD && VD->isUsableInConstantExpressions(Ctx) &&
!VD->getType()->isReferenceType())
return NoDiag();
return ICEDiag(IK_NotICE, E->getBeginLoc());
}
case Expr::UnaryOperatorClass: {
const UnaryOperator *Exp = cast<UnaryOperator>(E);
switch (Exp->getOpcode()) {
case UO_PostInc:
case UO_PostDec:
case UO_PreInc:
case UO_PreDec:
case UO_AddrOf:
case UO_Deref:
case UO_Coawait:
// C99 6.6/3 allows increment and decrement within unevaluated
// subexpressions of constant expressions, but they can never be ICEs
// because an ICE cannot contain an lvalue operand.
return ICEDiag(IK_NotICE, E->getBeginLoc());
case UO_Extension:
case UO_LNot:
case UO_Plus:
case UO_Minus:
case UO_Not:
case UO_Real:
case UO_Imag:
return CheckICE(Exp->getSubExpr(), Ctx);
}
llvm_unreachable("invalid unary operator class");
}
case Expr::OffsetOfExprClass: {
// Note that per C99, offsetof must be an ICE. And AFAIK, using
// EvaluateAsRValue matches the proposed gcc behavior for cases like
// "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect
// compliance: we should warn earlier for offsetof expressions with
// array subscripts that aren't ICEs, and if the array subscripts
// are ICEs, the value of the offsetof must be an integer constant.
return CheckEvalInICE(E, Ctx);
}
case Expr::UnaryExprOrTypeTraitExprClass: {
const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E);
if ((Exp->getKind() == UETT_SizeOf) &&
Exp->getTypeOfArgument()->isVariableArrayType())
return ICEDiag(IK_NotICE, E->getBeginLoc());
return NoDiag();
}
case Expr::BinaryOperatorClass: {
const BinaryOperator *Exp = cast<BinaryOperator>(E);
switch (Exp->getOpcode()) {
case BO_PtrMemD:
case BO_PtrMemI:
case BO_Assign:
case BO_MulAssign:
case BO_DivAssign:
case BO_RemAssign:
case BO_AddAssign:
case BO_SubAssign:
case BO_ShlAssign:
case BO_ShrAssign:
case BO_AndAssign:
case BO_XorAssign:
case BO_OrAssign:
// C99 6.6/3 allows assignments within unevaluated subexpressions of
// constant expressions, but they can never be ICEs because an ICE cannot
// contain an lvalue operand.
return ICEDiag(IK_NotICE, E->getBeginLoc());
case BO_Mul:
case BO_Div:
case BO_Rem:
case BO_Add:
case BO_Sub:
case BO_Shl:
case BO_Shr:
case BO_LT:
case BO_GT:
case BO_LE:
case BO_GE:
case BO_EQ:
case BO_NE:
case BO_And:
case BO_Xor:
case BO_Or:
case BO_Comma:
case BO_Cmp: {
ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
if (Exp->getOpcode() == BO_Div ||
Exp->getOpcode() == BO_Rem) {
// EvaluateAsRValue gives an error for undefined Div/Rem, so make sure
// we don't evaluate one.
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) {
llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx);
if (REval == 0)
return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
if (REval.isSigned() && REval.isAllOnesValue()) {
llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx);
if (LEval.isMinSignedValue())
return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
}
}
}
if (Exp->getOpcode() == BO_Comma) {
if (Ctx.getLangOpts().C99) {
// C99 6.6p3 introduces a strange edge case: comma can be in an ICE
// if it isn't evaluated.
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE)
return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc());
} else {
// In both C89 and C++, commas in ICEs are illegal.
return ICEDiag(IK_NotICE, E->getBeginLoc());
}
}
return Worst(LHSResult, RHSResult);
}
case BO_LAnd:
case BO_LOr: {
ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx);
ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx);
if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) {
// Rare case where the RHS has a comma "side-effect"; we need
// to actually check the condition to see whether the side
// with the comma is evaluated.
if ((Exp->getOpcode() == BO_LAnd) !=
(Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0))
return RHSResult;
return NoDiag();
}
return Worst(LHSResult, RHSResult);
}
}
llvm_unreachable("invalid binary operator kind");
}
case Expr::ImplicitCastExprClass:
case Expr::CStyleCastExprClass:
case Expr::CXXFunctionalCastExprClass:
case Expr::CXXStaticCastExprClass:
case Expr::CXXReinterpretCastExprClass:
case Expr::CXXConstCastExprClass:
case Expr::ObjCBridgedCastExprClass: {
const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr();
if (isa<ExplicitCastExpr>(E)) {
if (const FloatingLiteral *FL
= dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) {
unsigned DestWidth = Ctx.getIntWidth(E->getType());
bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType();
APSInt IgnoredVal(DestWidth, !DestSigned);
bool Ignored;
// If the value does not fit in the destination type, the behavior is
// undefined, so we are not required to treat it as a constant
// expression.
if (FL->getValue().convertToInteger(IgnoredVal,
llvm::APFloat::rmTowardZero,
&Ignored) & APFloat::opInvalidOp)
return ICEDiag(IK_NotICE, E->getBeginLoc());
return NoDiag();
}
}
switch (cast<CastExpr>(E)->getCastKind()) {
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NonAtomicToAtomic:
case CK_NoOp:
case CK_IntegralToBoolean:
case CK_IntegralCast:
return CheckICE(SubExpr, Ctx);
default:
return ICEDiag(IK_NotICE, E->getBeginLoc());
}
}
case Expr::BinaryConditionalOperatorClass: {
const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E);
ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx);
if (CommonResult.Kind == IK_NotICE) return CommonResult;
ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
if (FalseResult.Kind == IK_NotICE) return FalseResult;
if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult;
if (FalseResult.Kind == IK_ICEIfUnevaluated &&
Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag();
return FalseResult;
}
case Expr::ConditionalOperatorClass: {
const ConditionalOperator *Exp = cast<ConditionalOperator>(E);
// If the condition (ignoring parens) is a __builtin_constant_p call,
// then only the true side is actually considered in an integer constant
// expression, and it is fully evaluated. This is an important GNU
// extension. See GCC PR38377 for discussion.
if (const CallExpr *CallCE
= dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts()))
if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p)
return CheckEvalInICE(E, Ctx);
ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx);
if (CondResult.Kind == IK_NotICE)
return CondResult;
ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx);
ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx);
if (TrueResult.Kind == IK_NotICE)
return TrueResult;
if (FalseResult.Kind == IK_NotICE)
return FalseResult;
if (CondResult.Kind == IK_ICEIfUnevaluated)
return CondResult;
if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE)
return NoDiag();
// Rare case where the diagnostics depend on which side is evaluated
// Note that if we get here, CondResult is 0, and at least one of
// TrueResult and FalseResult is non-zero.
if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0)
return FalseResult;
return TrueResult;
}
case Expr::CXXDefaultArgExprClass:
return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx);
case Expr::CXXDefaultInitExprClass:
return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx);
case Expr::ChooseExprClass: {
return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx);
}
case Expr::BuiltinBitCastExprClass: {
if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E)))
return ICEDiag(IK_NotICE, E->getBeginLoc());
return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx);
}
}
llvm_unreachable("Invalid StmtClass!");
}
/// Evaluate an expression as a C++11 integral constant expression.
static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx,
const Expr *E,
llvm::APSInt *Value,
SourceLocation *Loc) {
if (!E->getType()->isIntegralOrUnscopedEnumerationType()) {
if (Loc) *Loc = E->getExprLoc();
return false;
}
APValue Result;
if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc))
return false;
if (!Result.isInt()) {
if (Loc) *Loc = E->getExprLoc();
return false;
}
if (Value) *Value = Result.getInt();
return true;
}
bool Expr::isIntegerConstantExpr(const ASTContext &Ctx,
SourceLocation *Loc) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
if (Ctx.getLangOpts().CPlusPlus11)
return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc);
ICEDiag D = CheckICE(this, Ctx);
if (D.Kind != IK_ICE) {
if (Loc) *Loc = D.Loc;
return false;
}
return true;
}
Optional<llvm::APSInt> Expr::getIntegerConstantExpr(const ASTContext &Ctx,
SourceLocation *Loc,
bool isEvaluated) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
APSInt Value;
if (Ctx.getLangOpts().CPlusPlus11) {
if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc))
return Value;
return None;
}
if (!isIntegerConstantExpr(Ctx, Loc))
return None;
// The only possible side-effects here are due to UB discovered in the
// evaluation (for instance, INT_MAX + 1). In such a case, we are still
// required to treat the expression as an ICE, so we produce the folded
// value.
EvalResult ExprResult;
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects);
Info.InConstantContext = true;
if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info))
llvm_unreachable("ICE cannot be evaluated!");
return ExprResult.Val.getInt();
}
bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
return CheckICE(this, Ctx).Kind == IK_ICE;
}
bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result,
SourceLocation *Loc) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
// We support this checking in C++98 mode in order to diagnose compatibility
// issues.
assert(Ctx.getLangOpts().CPlusPlus);
// Build evaluation settings.
Expr::EvalStatus Status;
SmallVector<PartialDiagnosticAt, 8> Diags;
Status.Diag = &Diags;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression);
APValue Scratch;
bool IsConstExpr =
::EvaluateAsRValue(Info, this, Result ? *Result : Scratch) &&
// FIXME: We don't produce a diagnostic for this, but the callers that
// call us on arbitrary full-expressions should generally not care.
Info.discardCleanups() && !Status.HasSideEffects;
if (!Diags.empty()) {
IsConstExpr = false;
if (Loc) *Loc = Diags[0].first;
} else if (!IsConstExpr) {
// FIXME: This shouldn't happen.
if (Loc) *Loc = getExprLoc();
}
return IsConstExpr;
}
bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx,
const FunctionDecl *Callee,
ArrayRef<const Expr*> Args,
const Expr *This) const {
assert(!isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated);
Info.InConstantContext = true;
LValue ThisVal;
const LValue *ThisPtr = nullptr;
if (This) {
#ifndef NDEBUG
auto *MD = dyn_cast<CXXMethodDecl>(Callee);
assert(MD && "Don't provide `this` for non-methods.");
assert(!MD->isStatic() && "Don't provide `this` for static methods.");
#endif
if (!This->isValueDependent() &&
EvaluateObjectArgument(Info, This, ThisVal) &&
!Info.EvalStatus.HasSideEffects)
ThisPtr = &ThisVal;
// Ignore any side-effects from a failed evaluation. This is safe because
// they can't interfere with any other argument evaluation.
Info.EvalStatus.HasSideEffects = false;
}
CallRef Call = Info.CurrentCall->createCall(Callee);
for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end();
I != E; ++I) {
unsigned Idx = I - Args.begin();
if (Idx >= Callee->getNumParams())
break;
const ParmVarDecl *PVD = Callee->getParamDecl(Idx);
if ((*I)->isValueDependent() ||
!EvaluateCallArg(PVD, *I, Call, Info) ||
Info.EvalStatus.HasSideEffects) {
// If evaluation fails, throw away the argument entirely.
if (APValue *Slot = Info.getParamSlot(Call, PVD))
*Slot = APValue();
}
// Ignore any side-effects from a failed evaluation. This is safe because
// they can't interfere with any other argument evaluation.
Info.EvalStatus.HasSideEffects = false;
}
// Parameter cleanups happen in the caller and are not part of this
// evaluation.
Info.discardCleanups();
Info.EvalStatus.HasSideEffects = false;
// Build fake call to Callee.
CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, Call);
// FIXME: Missing ExprWithCleanups in enable_if conditions?
FullExpressionRAII Scope(Info);
return Evaluate(Value, Info, this) && Scope.destroy() &&
!Info.EvalStatus.HasSideEffects;
}
bool Expr::isPotentialConstantExpr(const FunctionDecl *FD,
SmallVectorImpl<
PartialDiagnosticAt> &Diags) {
// FIXME: It would be useful to check constexpr function templates, but at the
// moment the constant expression evaluator cannot cope with the non-rigorous
// ASTs which we build for dependent expressions.
if (FD->isDependentContext())
return true;
Expr::EvalStatus Status;
Status.Diag = &Diags;
EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression);
Info.InConstantContext = true;
Info.CheckingPotentialConstantExpression = true;
// The constexpr VM attempts to compile all methods to bytecode here.
if (Info.EnableNewConstInterp) {
Info.Ctx.getInterpContext().isPotentialConstantExpr(Info, FD);
return Diags.empty();
}
const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD);
const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr;
// Fabricate an arbitrary expression on the stack and pretend that it
// is a temporary being used as the 'this' pointer.
LValue This;
ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy);
This.set({&VIE, Info.CurrentCall->Index});
ArrayRef<const Expr*> Args;
APValue Scratch;
if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) {
// Evaluate the call as a constant initializer, to allow the construction
// of objects of non-literal types.
Info.setEvaluatingDecl(This.getLValueBase(), Scratch);
HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch);
} else {
SourceLocation Loc = FD->getLocation();
HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr,
Args, CallRef(), FD->getBody(), Info, Scratch, nullptr);
}
return Diags.empty();
}
bool Expr::isPotentialConstantExprUnevaluated(Expr *E,
const FunctionDecl *FD,
SmallVectorImpl<
PartialDiagnosticAt> &Diags) {
assert(!E->isValueDependent() &&
"Expression evaluator can't be called on a dependent expression.");
Expr::EvalStatus Status;
Status.Diag = &Diags;
EvalInfo Info(FD->getASTContext(), Status,
EvalInfo::EM_ConstantExpressionUnevaluated);
Info.InConstantContext = true;
Info.CheckingPotentialConstantExpression = true;
// Fabricate a call stack frame to give the arguments a plausible cover story.
CallStackFrame Frame(Info, SourceLocation(), FD, /*This*/ nullptr, CallRef());
APValue ResultScratch;
Evaluate(ResultScratch, Info, E);
return Diags.empty();
}
bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx,
unsigned Type) const {
if (!getType()->isPointerType())
return false;
Expr::EvalStatus Status;
EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold);
return tryEvaluateBuiltinObjectSize(this, Type, Info, Result);
}
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