maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[C++2a] Add __builtin_bit_cast, used to implement std::bit_cast 

This commit adds a new builtin, __builtin_bit_cast(T, v), which performs a
bit_cast from a value v to a type T. This expression can be evaluated at
compile time under specific circumstances.

The compile time evaluation currently doesn't support bit-fields, but I'm
planning on fixing this in a follow up (some of the logic for figuring this out
is in CodeGen). I'm also planning follow-ups for supporting some more esoteric
types that the constexpr evaluator supports, as well as extending
__builtin_memcpy constexpr evaluation to use the same infrastructure.

rdar://44987528

Differential revision: https://reviews.llvm.org/D62825

llvm-svn: 364954
This commit is contained in:
Erik Pilkington 2019-07-02 18:28:13 +00:00
parent 5613874947
commit eee944e7f9
41 changed files with 1397 additions and 63 deletions

6
clang/include/clang-c/Index.h
View File

@ -2546,7 +2546,11 @@ enum CXCursorKind {
*/
CXCursor_OMPTargetTeamsDistributeSimdDirective = 279,
CXCursor_LastStmt = CXCursor_OMPTargetTeamsDistributeSimdDirective,
/** C++2a std::bit_cast expression.
*/
CXCursor_BuiltinBitCastExpr = 280,
CXCursor_LastStmt = CXCursor_BuiltinBitCastExpr,
/**
* Cursor that represents the translation unit itself.

29
clang/include/clang/AST/ExprCXX.h
View File

@ -4716,6 +4716,35 @@ public:
}
};
/// Represents a C++2a __builtin_bit_cast(T, v) expression. Used to implement
/// std::bit_cast. These can sometimes be evaluated as part of a constant
/// expression, but otherwise CodeGen to a simple memcpy in general.
class BuiltinBitCastExpr final
: public ExplicitCastExpr,
private llvm::TrailingObjects<BuiltinBitCastExpr, CXXBaseSpecifier *> {
friend class ASTStmtReader;
friend class CastExpr;
friend class TrailingObjects;
SourceLocation KWLoc;
SourceLocation RParenLoc;
public:
BuiltinBitCastExpr(QualType T, ExprValueKind VK, CastKind CK, Expr *SrcExpr,
TypeSourceInfo *DstType, SourceLocation KWLoc,
SourceLocation RParenLoc)
: ExplicitCastExpr(BuiltinBitCastExprClass, T, VK, CK, SrcExpr, 0,
DstType),
KWLoc(KWLoc), RParenLoc(RParenLoc) {}
SourceLocation getBeginLoc() const LLVM_READONLY { return KWLoc; }
SourceLocation getEndLoc() const LLVM_READONLY { return RParenLoc; }
static bool classof(const Stmt *T) {
return T->getStmtClass() == BuiltinBitCastExprClass;
}
};
} // namespace clang
#endif // LLVM_CLANG_AST_EXPRCXX_H

4
clang/include/clang/AST/OperationKinds.def
View File

@ -66,6 +66,10 @@ CAST_OPERATION(BitCast)
/// bool b; reinterpret_cast<char&>(b) = 'a';
CAST_OPERATION(LValueBitCast)
/// CK_LValueToRValueBitCast - A conversion that causes us to reinterpret an
/// lvalue as an rvalue of a different type. Created by __builtin_bit_cast.
CAST_OPERATION(LValueToRValueBitCast)
/// CK_LValueToRValue - A conversion which causes the extraction of
/// an r-value from the operand gl-value. The result of an r-value
/// conversion is always unqualified.

4
clang/include/clang/AST/RecursiveASTVisitor.h
View File

@ -2282,6 +2282,10 @@ DEF_TRAVERSE_STMT(CXXStaticCastExpr, {
TRY_TO(TraverseTypeLoc(S->getTypeInfoAsWritten()->getTypeLoc()));
})
DEF_TRAVERSE_STMT(BuiltinBitCastExpr, {
TRY_TO(TraverseTypeLoc(S->getTypeInfoAsWritten()->getTypeLoc()));
})
template <typename Derived>
bool RecursiveASTVisitor<Derived>::TraverseSynOrSemInitListExpr(
InitListExpr *S, DataRecursionQueue *Queue) {

13
clang/include/clang/Basic/DiagnosticASTKinds.td
View File

@ -215,6 +215,19 @@ def note_constexpr_memcpy_unsupported : Note<
"size to copy (%4) is not a multiple of size of element type %3 (%5)|"
"source is not a contiguous array of at least %4 elements of type %3|"
"destination is not a contiguous array of at least %4 elements of type %3}2">;
def note_constexpr_bit_cast_unsupported_type : Note<
"constexpr bit_cast involving type %0 is not yet supported">;
def note_constexpr_bit_cast_unsupported_bitfield : Note<
"constexpr bit_cast involving bit-field is not yet supported">;
def note_constexpr_bit_cast_invalid_type : Note<
"bit_cast %select{from|to}0 a %select{|type with a }1"
"%select{union|pointer|member pointer|volatile|reference}2 "
"%select{type|member}1 is not allowed in a constant expression">;
def note_constexpr_bit_cast_invalid_subtype : Note<
"invalid type %0 is a %select{member|base}1 of %2">;
def note_constexpr_bit_cast_indet_dest : Note<
"indeterminate value can only initialize an object of type 'unsigned char'"
"%select{, 'char',|}1 or 'std::byte'; %0 is invalid">;
def warn_integer_constant_overflow : Warning<
"overflow in expression; result is %0 with type %1">,

4
clang/include/clang/Basic/DiagnosticSemaKinds.td
View File

@ -9734,4 +9734,8 @@ def err_builtin_launder_invalid_arg : Error<
"%select{non-pointer|function pointer|void pointer}0 argument to "
"'__builtin_launder' is not allowed">;
def err_bit_cast_non_trivially_copyable : Error<
"__builtin_bit_cast %select{source|destination}0 type must be trivially copyable">;
def err_bit_cast_type_size_mismatch : Error<
"__builtin_bit_cast source size does not equal destination size (%0 vs %1)">;
} // end of sema component.

1
clang/include/clang/Basic/StmtNodes.td
View File

@ -192,6 +192,7 @@ def ConvertVectorExpr : DStmt<Expr>;
def BlockExpr : DStmt<Expr>;
def OpaqueValueExpr : DStmt<Expr>;
def TypoExpr : DStmt<Expr>;
def BuiltinBitCastExpr : DStmt<ExplicitCastExpr>;
// Microsoft Extensions.
def MSPropertyRefExpr : DStmt<Expr>;

2
clang/include/clang/Basic/TokenKinds.def
View File

@ -670,7 +670,7 @@ ALIAS("_pascal" , __pascal , KEYBORLAND)
KEYWORD(__builtin_convertvector , KEYALL)
ALIAS("__char16_t" , char16_t , KEYCXX)
ALIAS("__char32_t" , char32_t , KEYCXX)
KEYWORD(__builtin_bit_cast , KEYALL)
KEYWORD(__builtin_available , KEYALL)
// Clang-specific keywords enabled only in testing.

3
clang/include/clang/Parse/Parser.h
View File

@ -1780,6 +1780,9 @@ private:
// C++ 5.2p1: C++ Casts
ExprResult ParseCXXCasts();
/// Parse a __builtin_bit_cast(T, E), used to implement C++2a std::bit_cast.
ExprResult ParseBuiltinBitCast();
//===--------------------------------------------------------------------===//
// C++ 5.2p1: C++ Type Identification
ExprResult ParseCXXTypeid();

7
clang/include/clang/Sema/Sema.h
View File

@ -5236,6 +5236,13 @@ public:
SourceRange AngleBrackets,
SourceRange Parens);
ExprResult ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &Dcl,
ExprResult Operand,
SourceLocation RParenLoc);
ExprResult BuildBuiltinBitCastExpr(SourceLocation KWLoc, TypeSourceInfo *TSI,
Expr *Operand, SourceLocation RParenLoc);
ExprResult BuildCXXTypeId(QualType TypeInfoType,
SourceLocation TypeidLoc,
TypeSourceInfo *Operand,

4
clang/lib/AST/Expr.cpp
View File

@ -1862,6 +1862,7 @@ bool CastExpr::CastConsistency() const {
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToBoolean:
case CK_LValueBitCast: // -> bool&
case CK_LValueToRValueBitCast:
case CK_UserDefinedConversion: // operator bool()
case CK_BuiltinFnToFnPtr:
case CK_FixedPointToBoolean:
@ -3506,7 +3507,8 @@ bool Expr::HasSideEffects(const ASTContext &Ctx,
case CXXStaticCastExprClass:
case CXXReinterpretCastExprClass:
case CXXConstCastExprClass:
case CXXFunctionalCastExprClass: {
case CXXFunctionalCastExprClass:
case BuiltinBitCastExprClass: {
// While volatile reads are side-effecting in both C and C++, we treat them
// as having possible (not definite) side-effects. This allows idiomatic
// code to behave without warning, such as sizeof(*v) for a volatile-

1
clang/lib/AST/ExprClassification.cpp
View File

@ -343,6 +343,7 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
case Expr::CXXReinterpretCastExprClass:
case Expr::CXXConstCastExprClass:
case Expr::ObjCBridgedCastExprClass:
case Expr::BuiltinBitCastExprClass:
// Only in C++ can casts be interesting at all.
if (!Lang.CPlusPlus) return Cl::CL_PRValue;
return ClassifyUnnamed(Ctx, cast<ExplicitCastExpr>(E)->getTypeAsWritten());

511
clang/lib/AST/ExprConstant.cpp
View File

@ -47,6 +47,7 @@
#include "clang/Basic/Builtins.h"
#include "clang/Basic/FixedPoint.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
@ -56,8 +57,10 @@
#define DEBUG_TYPE "exprconstant"
using namespace clang;
using llvm::APInt;
using llvm::APSInt;
using llvm::APFloat;
using llvm::Optional;
static bool IsGlobalLValue(APValue::LValueBase B);
@ -2657,10 +2660,6 @@ static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E,
return true;
}
static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv,
QualType Type, const LValue &LVal,
APValue &RVal);
/// Try to evaluate the initializer for a variable declaration.
///
/// \param Info Information about the ongoing evaluation.
@ -5376,6 +5375,489 @@ static bool HandleConstructorCall(const Expr *E, const LValue &This,
//===----------------------------------------------------------------------===//
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?");
}
}
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) {
CharUnits Width = Info.Ctx.getTypeSizeInChars(Ty);
SmallVector<unsigned char, 8> Bytes(Width.getQuantity());
llvm::StoreIntToMemory(Val, &*Bytes.begin(), Width.getQuantity());
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;
}
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);
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 ? (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());
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 BuiltinType *AsBuiltin =
RepresentationType.getCanonicalType()->getAs<BuiltinType>();
assert(AsBuiltin && "non-integral enum underlying type?");
// 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.def"
}
}
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))
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> {
@ -5510,6 +5992,9 @@ public:
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()) {
@ -5802,6 +6287,14 @@ public:
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);
}
}
return Error(E);
@ -6651,7 +7144,6 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
break;
case CK_BitCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
@ -8176,7 +8668,7 @@ public:
}
bool Success(const APValue &V, const Expr *E) {
if (V.isLValue() || V.isAddrLabelDiff()) {
if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) {
Result = V;
return true;
}
@ -10598,6 +11090,7 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
case CK_LValueToRValueBitCast:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_MemberPointerToBoolean:
@ -11210,6 +11703,7 @@ bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
case CK_LValueToRValue:
case CK_AtomicToNonAtomic:
case CK_NoOp:
case CK_LValueToRValueBitCast:
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_Dependent:
@ -12512,6 +13006,11 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &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!");

1
clang/lib/AST/ItaniumMangle.cpp
View File

@ -3634,6 +3634,7 @@ recurse:
case Expr::AtomicExprClass:
case Expr::SourceLocExprClass:
case Expr::FixedPointLiteralClass:
case Expr::BuiltinBitCastExprClass:
{
if (!NullOut) {
// As bad as this diagnostic is, it's better than crashing.

8
clang/lib/AST/StmtPrinter.cpp
View File

@ -1703,6 +1703,14 @@ void StmtPrinter::VisitCXXConstCastExpr(CXXConstCastExpr *Node) {
VisitCXXNamedCastExpr(Node);
}
void StmtPrinter::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *Node) {
OS << "__builtin_bit_cast(";
Node->getTypeInfoAsWritten()->getType().print(OS, Policy);
OS << ", ";
PrintExpr(Node->getSubExpr());
OS << ")";
}
void StmtPrinter::VisitCXXTypeidExpr(CXXTypeidExpr *Node) {
OS << "typeid(";
if (Node->isTypeOperand()) {

5
clang/lib/AST/StmtProfile.cpp
View File

@ -1569,6 +1569,11 @@ void StmtProfiler::VisitCXXConstCastExpr(const CXXConstCastExpr *S) {
VisitCXXNamedCastExpr(S);
}
void StmtProfiler::VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *S) {
VisitExpr(S);
VisitType(S->getTypeInfoAsWritten()->getType());
}
void StmtProfiler::VisitUserDefinedLiteral(const UserDefinedLiteral *S) {
VisitCallExpr(S);
}

1
clang/lib/CodeGen/CGExpr.cpp
View File

@ -4209,6 +4209,7 @@ LValue CodeGenFunction::EmitCastLValue(const CastExpr *E) {
switch (E->getCastKind()) {
case CK_ToVoid:
case CK_BitCast:
case CK_LValueToRValueBitCast:
case CK_ArrayToPointerDecay:
case CK_FunctionToPointerDecay:
case CK_NullToMemberPointer:

19
clang/lib/CodeGen/CGExprAgg.cpp
View File

@ -711,6 +711,25 @@ void AggExprEmitter::VisitCastExpr(CastExpr *E) {
break;
}
case CK_LValueToRValueBitCast: {
if (Dest.isIgnored()) {
CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
/*ignoreResult=*/true);
break;
}
LValue SourceLV = CGF.EmitLValue(E->getSubExpr());
Address SourceAddress =
Builder.CreateElementBitCast(SourceLV.getAddress(), CGF.Int8Ty);
Address DestAddress =
Builder.CreateElementBitCast(Dest.getAddress(), CGF.Int8Ty);
llvm::Value *SizeVal = llvm::ConstantInt::get(
CGF.SizeTy,
CGF.getContext().getTypeSizeInChars(E->getType()).getQuantity());
Builder.CreateMemCpy(DestAddress, SourceAddress, SizeVal);
break;
}
case CK_DerivedToBase:
case CK_BaseToDerived:
case CK_UncheckedDerivedToBase: {

9
clang/lib/CodeGen/CGExprComplex.cpp
View File

@ -464,6 +464,15 @@ ComplexPairTy ComplexExprEmitter::EmitCast(CastKind CK, Expr *Op,
return EmitLoadOfLValue(CGF.MakeAddrLValue(V, DestTy), Op->getExprLoc());
}
case CK_LValueToRValueBitCast: {
LValue SourceLVal = CGF.EmitLValue(Op);
Address Addr = Builder.CreateElementBitCast(SourceLVal.getAddress(),
CGF.ConvertTypeForMem(DestTy));
LValue DestLV = CGF.MakeAddrLValue(Addr, DestTy);
DestLV.setTBAAInfo(TBAAAccessInfo::getMayAliasInfo());
return EmitLoadOfLValue(DestLV, Op->getExprLoc());
}
case CK_BitCast:
case CK_BaseToDerived:
case CK_DerivedToBase:

1
clang/lib/CodeGen/CGExprConstant.cpp
View File

@ -1115,6 +1115,7 @@ public:
case CK_ToVoid:
case CK_Dynamic:
case CK_LValueBitCast:
case CK_LValueToRValueBitCast:
case CK_NullToMemberPointer:
case CK_UserDefinedConversion:
case CK_CPointerToObjCPointerCast:

9
clang/lib/CodeGen/CGExprScalar.cpp
View File

@ -2033,6 +2033,15 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
return EmitLoadOfLValue(LV, CE->getExprLoc());
}
case CK_LValueToRValueBitCast: {
LValue SourceLVal = CGF.EmitLValue(E);
Address Addr = Builder.CreateElementBitCast(SourceLVal.getAddress(),
CGF.ConvertTypeForMem(DestTy));
LValue DestLV = CGF.MakeAddrLValue(Addr, DestTy);
DestLV.setTBAAInfo(TBAAAccessInfo::getMayAliasInfo());
return EmitLoadOfLValue(DestLV, CE->getExprLoc());
}
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
case CK_AnyPointerToBlockPointerCast:

1
clang/lib/Edit/RewriteObjCFoundationAPI.cpp
View File

@ -1042,6 +1042,7 @@ static bool rewriteToNumericBoxedExpression(const ObjCMessageExpr *Msg,
case CK_Dependent:
case CK_BitCast:
case CK_LValueBitCast:
case CK_LValueToRValueBitCast:
case CK_BaseToDerived:
case CK_DerivedToBase:
case CK_UncheckedDerivedToBase:

1
clang/lib/Lex/PPMacroExpansion.cpp
View File

@ -1630,6 +1630,7 @@ void Preprocessor::ExpandBuiltinMacro(Token &Tok) {
.Case("__builtin_FILE", true)
.Case("__builtin_FUNCTION", true)
.Case("__builtin_COLUMN", true)
.Case("__builtin_bit_cast", true)
.Default(false);
}
});

3
clang/lib/Parse/ParseExpr.cpp
View File

@ -1223,6 +1223,9 @@ ExprResult Parser::ParseCastExpression(bool isUnaryExpression,
case tok::kw_static_cast:
Res = ParseCXXCasts();
break;
case tok::kw___builtin_bit_cast:
Res = ParseBuiltinBitCast();
break;
case tok::kw_typeid:
Res = ParseCXXTypeid();
break;

34
clang/lib/Parse/ParseExprCXX.cpp
View File

@ -3513,3 +3513,37 @@ Parser::ParseCXXAmbiguousParenExpression(ParenParseOption &ExprType,
ConsumeAnyToken();
return Result;
}
/// Parse a __builtin_bit_cast(T, E).
ExprResult Parser::ParseBuiltinBitCast() {
SourceLocation KWLoc = ConsumeToken();
BalancedDelimiterTracker T(*this, tok::l_paren);
if (T.expectAndConsume(diag::err_expected_lparen_after, "__builtin_bit_cast"))
return ExprError();
// Parse the common declaration-specifiers piece.
DeclSpec DS(AttrFactory);
ParseSpecifierQualifierList(DS);
// Parse the abstract-declarator, if present.
Declarator DeclaratorInfo(DS, DeclaratorContext::TypeNameContext);
ParseDeclarator(DeclaratorInfo);
if (ExpectAndConsume(tok::comma)) {
Diag(Tok.getLocation(), diag::err_expected) << tok::comma;
SkipUntil(tok::r_paren, StopAtSemi);
return ExprError();
}
ExprResult Operand = ParseExpression();
if (T.consumeClose())
return ExprError();
if (Operand.isInvalid() || DeclaratorInfo.isInvalidType())
return ExprError();
return Actions.ActOnBuiltinBitCastExpr(KWLoc, DeclaratorInfo, Operand,
T.getCloseLocation());
}

70
clang/lib/Sema/SemaCast.cpp
View File

@ -87,6 +87,7 @@ namespace {
void CheckDynamicCast();
void CheckCXXCStyleCast(bool FunctionalCast, bool ListInitialization);
void CheckCStyleCast();
void CheckBuiltinBitCast();
void updatePartOfExplicitCastFlags(CastExpr *CE) {
// Walk down from the CE to the OrigSrcExpr, and mark all immediate
@ -331,6 +332,38 @@ Sema::BuildCXXNamedCast(SourceLocation OpLoc, tok::TokenKind Kind,
}
}
ExprResult Sema::ActOnBuiltinBitCastExpr(SourceLocation KWLoc, Declarator &D,
ExprResult Operand,
SourceLocation RParenLoc) {
assert(!D.isInvalidType());
TypeSourceInfo *TInfo = GetTypeForDeclaratorCast(D, Operand.get()->getType());
if (D.isInvalidType())
return ExprError();
return BuildBuiltinBitCastExpr(KWLoc, TInfo, Operand.get(), RParenLoc);
}
ExprResult Sema::BuildBuiltinBitCastExpr(SourceLocation KWLoc,
TypeSourceInfo *TSI, Expr *Operand,
SourceLocation RParenLoc) {
CastOperation Op(*this, TSI->getType(), Operand);
Op.OpRange = SourceRange(KWLoc, RParenLoc);
TypeLoc TL = TSI->getTypeLoc();
Op.DestRange = SourceRange(TL.getBeginLoc(), TL.getEndLoc());
if (!Operand->isTypeDependent() && !TSI->getType()->isDependentType()) {
Op.CheckBuiltinBitCast();
if (Op.SrcExpr.isInvalid())
return ExprError();
}
BuiltinBitCastExpr *BCE =
new (Context) BuiltinBitCastExpr(Op.ResultType, Op.ValueKind, Op.Kind,
Op.SrcExpr.get(), TSI, KWLoc, RParenLoc);
return Op.complete(BCE);
}
/// Try to diagnose a failed overloaded cast. Returns true if
/// diagnostics were emitted.
static bool tryDiagnoseOverloadedCast(Sema &S, CastType CT,
@ -2764,6 +2797,43 @@ void CastOperation::CheckCStyleCast() {
checkCastAlign();
}
void CastOperation::CheckBuiltinBitCast() {
QualType SrcType = SrcExpr.get()->getType();
if (SrcExpr.get()->isRValue())
SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(),
/*IsLValueReference=*/false);
CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType);
CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType);
if (DestSize != SourceSize) {
Self.Diag(OpRange.getBegin(), diag::err_bit_cast_type_size_mismatch)
<< (int)SourceSize.getQuantity() << (int)DestSize.getQuantity();
SrcExpr = ExprError();
return;
}
if (!DestType.isTriviallyCopyableType(Self.Context)) {
Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
<< 1;
SrcExpr = ExprError();
return;
}
if (!SrcType.isTriviallyCopyableType(Self.Context)) {
Self.Diag(OpRange.getBegin(), diag::err_bit_cast_non_trivially_copyable)
<< 0;
SrcExpr = ExprError();
return;
}
if (Self.Context.hasSameUnqualifiedType(DestType, SrcType)) {
Kind = CK_NoOp;
return;
}
Kind = CK_LValueToRValueBitCast;
}
/// DiagnoseCastQual - Warn whenever casts discards a qualifiers, be it either
/// const, volatile or both.
static void DiagnoseCastQual(Sema &Self, const ExprResult &SrcExpr,

1
clang/lib/Sema/SemaExceptionSpec.cpp
View File

@ -1201,6 +1201,7 @@ CanThrowResult Sema::canThrow(const Expr *E) {
case Expr::CoyieldExprClass:
case Expr::CXXConstCastExprClass:
case Expr::CXXReinterpretCastExprClass:
case Expr::BuiltinBitCastExprClass:
case Expr::CXXStdInitializerListExprClass:
case Expr::DesignatedInitExprClass:
case Expr::DesignatedInitUpdateExprClass:

26
clang/lib/Sema/TreeTransform.h
View File

@ -2652,6 +2652,16 @@ public:
ListInitialization);
}
/// Build a new C++ __builtin_bit_cast expression.
///
/// By default, performs semantic analysis to build the new expression.
/// Subclasses may override this routine to provide different behavior.
ExprResult RebuildBuiltinBitCastExpr(SourceLocation KWLoc,
TypeSourceInfo *TSI, Expr *Sub,
SourceLocation RParenLoc) {
return getSema().BuildBuiltinBitCastExpr(KWLoc, TSI, Sub, RParenLoc);
}
/// Build a new C++ typeid(type) expression.
///
/// By default, performs semantic analysis to build the new expression.
@ -10245,6 +10255,22 @@ TreeTransform<Derived>::TransformCXXNamedCastExpr(CXXNamedCastExpr *E) {
E->getAngleBrackets().getEnd(), SubExpr.get(), E->getRParenLoc());
}
template<typename Derived>
ExprResult
TreeTransform<Derived>::TransformBuiltinBitCastExpr(BuiltinBitCastExpr *BCE) {
TypeSourceInfo *TSI =
getDerived().TransformType(BCE->getTypeInfoAsWritten());
if (!TSI)
return ExprError();
ExprResult Sub = getDerived().TransformExpr(BCE->getSubExpr());
if (Sub.isInvalid())
return ExprError();
return getDerived().RebuildBuiltinBitCastExpr(BCE->getBeginLoc(), TSI,
Sub.get(), BCE->getEndLoc());
}
template<typename Derived>
ExprResult
TreeTransform<Derived>::TransformCXXStaticCastExpr(CXXStaticCastExpr *E) {

6
clang/lib/Serialization/ASTReaderStmt.cpp
View File

@ -1510,6 +1510,12 @@ void ASTStmtReader::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E) {
E->setRParenLoc(ReadSourceLocation());
}
void ASTStmtReader::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *E) {
VisitExplicitCastExpr(E);
E->KWLoc = ReadSourceLocation();
E->RParenLoc = ReadSourceLocation();
}
void ASTStmtReader::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
VisitCallExpr(E);
E->UDSuffixLoc = ReadSourceLocation();

6
clang/lib/Serialization/ASTWriterStmt.cpp
View File

@ -1451,6 +1451,12 @@ void ASTStmtWriter::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E) {
Code = serialization::EXPR_CXX_FUNCTIONAL_CAST;
}
void ASTStmtWriter::VisitBuiltinBitCastExpr(BuiltinBitCastExpr *E) {
VisitExplicitCastExpr(E);
Record.AddSourceLocation(E->getBeginLoc());
Record.AddSourceLocation(E->getEndLoc());
}
void ASTStmtWriter::VisitUserDefinedLiteral(UserDefinedLiteral *E) {
VisitCallExpr(E);
Record.AddSourceLocation(E->UDSuffixLoc);

1
clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
View File

@ -1687,6 +1687,7 @@ void ExprEngine::Visit(const Stmt *S, ExplodedNode *Pred,
case Stmt::CXXReinterpretCastExprClass:
case Stmt::CXXConstCastExprClass:
case Stmt::CXXFunctionalCastExprClass:
case Stmt::BuiltinBitCastExprClass:
case Stmt::ObjCBridgedCastExprClass: {
Bldr.takeNodes(Pred);
const auto *C = cast<CastExpr>(S);

1
clang/lib/StaticAnalyzer/Core/ExprEngineC.cpp
View File

@ -380,6 +380,7 @@ void ExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex,
case CK_Dependent:
case CK_ArrayToPointerDecay:
case CK_BitCast:
case CK_LValueToRValueBitCast:
case CK_AddressSpaceConversion:
case CK_BooleanToSignedIntegral:
case CK_IntegralToPointer:

19
clang/test/CodeGenCXX/builtin-bit-cast-no-tbaa.cpp Normal file
View File

@ -0,0 +1,19 @@
// RUN: %clang_cc1 -O3 -std=c++2a -S -emit-llvm -o - -disable-llvm-passes -triple x86_64-apple-macos10.14 %s | FileCheck %s
void test_scalar() {
// CHECK-LABEL: define void @_Z11test_scalarv
__builtin_bit_cast(float, 42);
// CHECK: load float, float* {{.*}}, align 4, !tbaa ![[MAY_ALIAS_TBAA:.*]]
}
void test_scalar2() {
// CHECK-LABEL: define void @_Z12test_scalar2v
struct S {int m;};
__builtin_bit_cast(int, S{42});
// CHECK: load i32, i32* {{.*}}, align 4, !tbaa ![[MAY_ALIAS_TBAA]]
}
// CHECK: ![[CHAR_TBAA:.*]] = !{!"omnipotent char", {{.*}}, i64 0}
// CHECK: ![[MAY_ALIAS_TBAA]] = !{![[CHAR_TBAA]], ![[CHAR_TBAA]], i64 0}

106
clang/test/CodeGenCXX/builtin-bit-cast.cpp Normal file
View File

@ -0,0 +1,106 @@
// RUN: %clang_cc1 -std=c++2a -S -emit-llvm -o - -disable-llvm-passes -triple x86_64-apple-macos10.14 %s | FileCheck %s
void test_scalar(int &oper) {
// CHECK-LABEL: define void @_Z11test_scalarRi
__builtin_bit_cast(float, oper);
// CHECK: [[OPER:%.*]] = alloca i32*
// CHECK: [[REF:%.*]] = load i32*, i32**
// CHECK-NEXT: [[CASTED:%.*]] = bitcast i32* [[REF]] to float*
// CHECK-NEXT: load float, float* [[CASTED]]
}
struct two_ints {
int x;
int y;
};
unsigned long test_aggregate_to_scalar(two_ints &ti) {
// CHECK-LABEL: define i64 @_Z24test_aggregate_to_scalarR8two_ints
return __builtin_bit_cast(unsigned long, ti);
// CHECK: [[TI_ADDR:%.*]] = alloca %struct.two_ints*, align 8
// CHECK: [[TI_LOAD:%.*]] = load %struct.two_ints*, %struct.two_ints** [[TI_ADDR]]
// CHECK-NEXT: [[CASTED:%.*]] = bitcast %struct.two_ints* [[TI_LOAD]] to i64*
// CHECK-NEXT: load i64, i64* [[CASTED]]
}
struct two_floats {
float x;
float y;
};
two_floats test_aggregate_record(two_ints& ti) {
// CHECK-LABEL: define <2 x float> @_Z21test_aggregate_recordR8two_int
return __builtin_bit_cast(two_floats, ti);
// CHECK: [[RETVAL:%.*]] = alloca %struct.two_floats, align 4
// CHECK: [[TI:%.*]] = alloca %struct.two_ints*, align 8
// CHECK: [[LOAD_TI:%.*]] = load %struct.two_ints*, %struct.two_ints** [[TI]]
// CHECK: [[MEMCPY_SRC:%.*]] = bitcast %struct.two_ints* [[LOAD_TI]] to i8*
// CHECK: [[MEMCPY_DST:%.*]] = bitcast %struct.two_floats* [[RETVAL]] to i8*
// CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 [[MEMCPY_DST]], i8* align 4 [[MEMCPY_SRC]]
}
two_floats test_aggregate_array(int (&ary)[2]) {
// CHECK-LABEL: define <2 x float> @_Z20test_aggregate_arrayRA2_i
return __builtin_bit_cast(two_floats, ary);
// CHECK: [[RETVAL:%.*]] = alloca %struct.two_floats, align 4
// CHECK: [[ARY:%.*]] = alloca [2 x i32]*, align 8
// CHECK: [[LOAD_ARY:%.*]] = load [2 x i32]*, [2 x i32]** [[ARY]]
// CHECK: [[MEMCPY_SRC:%.*]] = bitcast [2 x i32]* [[LOAD_ARY]] to i8*
// CHECK: [[MEMCPY_DST:%.*]] = bitcast %struct.two_floats* [[RETVAL]] to i8*
// CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 [[MEMCPY_DST]], i8* align 4 [[MEMCPY_SRC]]
}
two_ints test_scalar_to_aggregate(unsigned long ul) {
// CHECK-LABEL: define i64 @_Z24test_scalar_to_aggregatem
return __builtin_bit_cast(two_ints, ul);
// CHECK: [[TI:%.*]] = alloca %struct.two_ints, align 4
// CHECK: [[TITMP:%.*]] = bitcast %struct.two_ints* [[TI]] to i8*
// CHECK-NEXT: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 [[TITMP]]
}
unsigned long test_complex(_Complex unsigned &cu) {
// CHECK-LABEL: define i64 @_Z12test_complexRCj
return __builtin_bit_cast(unsigned long, cu);
// CHECK: [[REF_ALLOCA:%.*]] = alloca { i32, i32 }*, align 8
// CHECK-NEXT: store { i32, i32 }* {{.*}}, { i32, i32 }** [[REF_ALLOCA]]
// CHECK-NEXT: [[REF:%.*]] = load { i32, i32 }*, { i32, i32 }** [[REF_ALLOCA]]
// CHECK-NEXT: [[CASTED:%.*]] = bitcast { i32, i32 }* [[REF]] to i64*
// CHECK-NEXT: load i64, i64* [[CASTED]], align 4
}
_Complex unsigned test_to_complex(unsigned long &ul) {
// CHECK-LABEL: define i64 @_Z15test_to_complexRm
return __builtin_bit_cast(_Complex unsigned, ul);
// CHECK: [[REF:%.*]] = alloca i64*
// CHECK: [[LOAD_REF:%.*]] = load i64*, i64** [[REF]]
// CHECK: [[CASTED:%.*]] = bitcast i64* [[LOAD_REF]] to { i32, i32 }*
}
unsigned long test_array(int (&ary)[2]) {
// CHECK-LABEL: define i64 @_Z10test_arrayRA2_i
return __builtin_bit_cast(unsigned long, ary);
// CHECK: [[REF_ALLOCA:%.*]] = alloca [2 x i32]*
// CHECK: [[LOAD_REF:%.*]] = load [2 x i32]*, [2 x i32]** [[REF_ALLOCA]]
// CHECK: [[CASTED:%.*]] = bitcast [2 x i32]* [[LOAD_REF]] to i64*
// CHECK: load i64, i64* [[CASTED]], align 4
}
two_ints test_rvalue_aggregate() {
// CHECK-LABEL: define i64 @_Z21test_rvalue_aggregate
return __builtin_bit_cast(two_ints, 42ul);
// CHECK: [[TI:%.*]] = alloca %struct.two_ints, align 4
// CHECK: [[CASTED:%.*]] = bitcast %struct.two_ints* [[TI]] to i8*
// CHECK: call void @llvm.memcpy.p0i8.p0i8.i64(i8* align 4 [[CASTED]]
}

39
clang/test/SemaCXX/builtin-bit-cast.cpp Normal file
View File

@ -0,0 +1,39 @@
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s -fno-signed-char
#if !__has_builtin(__builtin_bit_cast)
#error
#endif
template <class T, T v>
T instantiate() {
return __builtin_bit_cast(T, v);
}
int x = instantiate<int, 32>();
struct secret_ctor {
char member;
private: secret_ctor() = default;
};
void test1() {
secret_ctor c = __builtin_bit_cast(secret_ctor, (char)0);
}
void test2() {
constexpr int i = 0;
// expected-error@+1{{__builtin_bit_cast source size does not equal destination size (4 vs 1)}}
constexpr char c = __builtin_bit_cast(char, i);
}
struct not_trivially_copyable {
virtual void foo() {}
};
// expected-error@+1{{__builtin_bit_cast source type must be trivially copyable}}
constexpr unsigned long ul = __builtin_bit_cast(unsigned long, not_trivially_copyable{});
// expected-error@+1 {{__builtin_bit_cast destination type must be trivially copyable}}
constexpr long us = __builtin_bit_cast(unsigned long &, 0L);

383
clang/test/SemaCXX/constexpr-builtin-bit-cast.cpp Normal file
View File

@ -0,0 +1,383 @@
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple x86_64-apple-macosx10.14.0 %s -fno-signed-char
// RUN: %clang_cc1 -verify -std=c++2a -fsyntax-only -triple aarch64_be-linux-gnu %s
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
# define LITTLE_END 1
#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
# define LITTLE_END 0
#else
# error "huh?"
#endif
template <class T, class V> struct is_same {
static constexpr bool value = false;
};
template <class T> struct is_same<T, T> {
static constexpr bool value = true;
};
static_assert(sizeof(int) == 4);
static_assert(sizeof(long long) == 8);
template <class To, class From>
constexpr To bit_cast(const From &from) {
static_assert(sizeof(To) == sizeof(From));
#ifdef __CHAR_UNSIGNED__
// expected-note@+4 2 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'signed char' is invalid}}
#else
// expected-note@+2 2 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'signed char' is invalid}}
#endif
return __builtin_bit_cast(To, from);
}
template <class Intermediate, class Init>
constexpr bool round_trip(const Init &init) {
return bit_cast<Init>(bit_cast<Intermediate>(init)) == init;
}
void test_int() {
static_assert(round_trip<unsigned>((int)-1));
static_assert(round_trip<unsigned>((int)0x12345678));
static_assert(round_trip<unsigned>((int)0x87654321));
static_assert(round_trip<unsigned>((int)0x0C05FEFE));
}
void test_array() {
constexpr unsigned char input[] = {0xCA, 0xFE, 0xBA, 0xBE};
constexpr unsigned expected = LITTLE_END ? 0xBEBAFECA : 0xCAFEBABE;
static_assert(bit_cast<unsigned>(input) == expected);
}
void test_record() {
struct int_splicer {
unsigned x;
unsigned y;
constexpr bool operator==(const int_splicer &other) const {
return other.x == x && other.y == y;
}
};
constexpr int_splicer splice{0x0C05FEFE, 0xCAFEBABE};
static_assert(bit_cast<unsigned long long>(splice) == LITTLE_END
? 0xCAFEBABE0C05FEFE
: 0x0C05FEFECAFEBABE);
static_assert(bit_cast<int_splicer>(0xCAFEBABE0C05FEFE).x == LITTLE_END
? 0x0C05FEFE
: 0xCAFEBABE);
static_assert(round_trip<unsigned long long>(splice));
static_assert(round_trip<long long>(splice));
struct base2 {
};
struct base3 {
unsigned z;
};
struct bases : int_splicer, base2, base3 {
unsigned doublez;
};
struct tuple4 {
unsigned x, y, z, doublez;
constexpr bool operator==(tuple4 const &other) const {
return x == other.x && y == other.y &&
z == other.z && doublez == other.doublez;
}
};
constexpr bases b = {{1, 2}, {}, {3}, 4};
constexpr tuple4 t4 = bit_cast<tuple4>(b);
static_assert(t4 == tuple4{1, 2, 3, 4});
static_assert(round_trip<tuple4>(b));
}
void test_partially_initialized() {
struct pad {
signed char x;
int y;
};
struct no_pad {
signed char x;
signed char p1, p2, p3;
int y;
};
static_assert(sizeof(pad) == sizeof(no_pad));
constexpr pad pir{4, 4};
// expected-error@+2 {{constexpr variable 'piw' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'bit_cast(pir)'}}
constexpr int piw = bit_cast<no_pad>(pir).x;
// expected-error@+2 {{constexpr variable 'bad' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'bit_cast(pir)'}}
constexpr no_pad bad = bit_cast<no_pad>(pir);
constexpr pad fine = bit_cast<pad>(no_pad{1, 2, 3, 4, 5});
static_assert(fine.x == 1 && fine.y == 5);
}
void no_bitfields() {
// FIXME!
struct S {
unsigned char x : 8;
};
struct G {
unsigned char x : 8;
};
constexpr S s{0};
// expected-error@+2 {{constexpr variable 'g' must be initialized by a constant expression}}
// expected-note@+1 {{constexpr bit_cast involving bit-field is not yet supported}}
constexpr G g = __builtin_bit_cast(G, s);
}
void array_members() {
struct S {
int ar[3];
constexpr bool operator==(const S &rhs) {
return ar[0] == rhs.ar[0] && ar[1] == rhs.ar[1] && ar[2] == rhs.ar[2];
}
};
struct G {
int a, b, c;
constexpr bool operator==(const G &rhs) {
return a == rhs.a && b == rhs.b && c == rhs.c;
}
};
constexpr S s{{1, 2, 3}};
constexpr G g = bit_cast<G>(s);
static_assert(g.a == 1 && g.b == 2 && g.c == 3);
static_assert(round_trip<G>(s));
static_assert(round_trip<S>(g));
}
void bad_types() {
union X {
int x;
};
struct G {
int g;
};
// expected-error@+2 {{constexpr variable 'g' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a union type is not allowed in a constant expression}}
constexpr G g = __builtin_bit_cast(G, X{0});
// expected-error@+2 {{constexpr variable 'x' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast to a union type is not allowed in a constant expression}}
constexpr X x = __builtin_bit_cast(X, G{0});
struct has_pointer {
// expected-note@+1 2 {{invalid type 'int *' is a member of 'has_pointer'}}
int *ptr;
};
// expected-error@+2 {{constexpr variable 'ptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a pointer type is not allowed in a constant expression}}
constexpr unsigned long ptr = __builtin_bit_cast(unsigned long, has_pointer{0});
// expected-error@+2 {{constexpr variable 'hptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast to a pointer type is not allowed in a constant expression}}
constexpr has_pointer hptr = __builtin_bit_cast(has_pointer, 0ul);
}
void backtrace() {
struct A {
// expected-note@+1 {{invalid type 'int *' is a member of 'A'}}
int *ptr;
};
struct B {
// expected-note@+1 {{invalid type 'A [10]' is a member of 'B'}}
A as[10];
};
// expected-note@+1 {{invalid type 'B' is a base of 'C'}}
struct C : B {
};
struct E {
unsigned long ar[10];
};
// expected-error@+2 {{constexpr variable 'e' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a pointer type is not allowed in a constant expression}}
constexpr E e = __builtin_bit_cast(E, C{});
}
void test_array_fill() {
constexpr unsigned char a[4] = {1, 2};
constexpr unsigned int i = bit_cast<unsigned int>(a);
static_assert(i == LITTLE_END ? 0x00000201 : 0x01020000, "");
}
typedef decltype(nullptr) nullptr_t;
#ifdef __CHAR_UNSIGNED__
// expected-note@+5 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'unsigned long' is invalid}}
#else
// expected-note@+3 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'unsigned long' is invalid}}
#endif
// expected-error@+1 {{constexpr variable 'test_from_nullptr' must be initialized by a constant expression}}
constexpr unsigned long test_from_nullptr = __builtin_bit_cast(unsigned long, nullptr);
constexpr int test_from_nullptr_pass = (__builtin_bit_cast(unsigned char[8], nullptr), 0);
constexpr int test_to_nullptr() {
nullptr_t npt = __builtin_bit_cast(nullptr_t, 0ul);
struct indet_mem {
unsigned char data[sizeof(void *)];
};
indet_mem im = __builtin_bit_cast(indet_mem, nullptr);
nullptr_t npt2 = __builtin_bit_cast(nullptr_t, im);
return 0;
}
constexpr int ttn = test_to_nullptr();
// expected-warning@+2 {{returning reference to local temporary object}}
// expected-note@+1 {{temporary created here}}
constexpr const long &returns_local() { return 0L; }
// expected-error@+2 {{constexpr variable 'test_nullptr_bad' must be initialized by a constant expression}}
// expected-note@+1 {{read of temporary whose lifetime has ended}}
constexpr nullptr_t test_nullptr_bad = __builtin_bit_cast(nullptr_t, returns_local());
constexpr int test_indeterminate(bool read_indet) {
struct pad {
char a;
int b;
};
struct no_pad {
char a;
unsigned char p1, p2, p3;
int b;
};
pad p{1, 2};
no_pad np = bit_cast<no_pad>(p);
int tmp = np.a + np.b;
unsigned char& indet_ref = np.p1;
if (read_indet) {
// expected-note@+1 {{read of uninitialized object is not allowed in a constant expression}}
tmp = indet_ref;
}
indet_ref = 0;
return 0;
}
constexpr int run_test_indeterminate = test_indeterminate(false);
// expected-error@+2 {{constexpr variable 'run_test_indeterminate2' must be initialized by a constant expression}}
// expected-note@+1 {{in call to 'test_indeterminate(true)'}}
constexpr int run_test_indeterminate2 = test_indeterminate(true);
struct ref_mem {
const int &rm;
};
constexpr int global_int = 0;
// expected-error@+2 {{constexpr variable 'run_ref_mem' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a type with a reference member is not allowed in a constant expression}}
constexpr unsigned long run_ref_mem = __builtin_bit_cast(
unsigned long, ref_mem{global_int});
union u {
int im;
};
// expected-error@+2 {{constexpr variable 'run_u' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a union type is not allowed in a constant expression}}
constexpr int run_u = __builtin_bit_cast(int, u{32});
struct vol_mem {
volatile int x;
};
// expected-error@+2 {{constexpr variable 'run_vol_mem' must be initialized by a constant expression}}
// expected-note@+1 {{non-literal type 'vol_mem' cannot be used in a constant expression}}
constexpr int run_vol_mem = __builtin_bit_cast(int, vol_mem{43});
struct mem_ptr {
int vol_mem::*x; // expected-note{{invalid type 'int vol_mem::*' is a member of 'mem_ptr'}}
};
// expected-error@+2 {{constexpr variable 'run_mem_ptr' must be initialized by a constant expression}}
// expected-note@+1 {{bit_cast from a member pointer type is not allowed in a constant expression}}
constexpr int run_mem_ptr = __builtin_bit_cast(unsigned long, mem_ptr{nullptr});
struct A { char c; /* char padding : 8; */ short s; };
struct B { unsigned char x[4]; };
constexpr B one() {
A a = {1, 2};
return bit_cast<B>(a);
}
constexpr char good_one = one().x[0] + one().x[2] + one().x[3];
// expected-error@+2 {{constexpr variable 'bad_one' must be initialized by a constant expression}}
// expected-note@+1 {{read of uninitialized object is not allowed in a constant expression}}
constexpr char bad_one = one().x[1];
constexpr A two() {
B b = one(); // b.x[1] is indeterminate.
b.x[0] = 'a';
b.x[2] = 1;
b.x[3] = 2;
return bit_cast<A>(b);
}
constexpr short good_two = two().c + two().s;
namespace std {
enum byte : unsigned char {};
}
enum my_byte : unsigned char {};
struct pad {
char a;
int b;
};
constexpr int ok_byte = (__builtin_bit_cast(std::byte[8], pad{1, 2}), 0);
constexpr int ok_uchar = (__builtin_bit_cast(unsigned char[8], pad{1, 2}), 0);
#ifdef __CHAR_UNSIGNED__
// expected-note@+5 {{indeterminate value can only initialize an object of type 'unsigned char', 'char', or 'std::byte'; 'my_byte' is invalid}}}}
#else
// expected-note@+3 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'my_byte' is invalid}}
#endif
// expected-error@+1 {{constexpr variable 'bad_my_byte' must be initialized by a constant expression}}
constexpr int bad_my_byte = (__builtin_bit_cast(my_byte[8], pad{1, 2}), 0);
#ifndef __CHAR_UNSIGNED__
// expected-error@+3 {{constexpr variable 'bad_char' must be initialized by a constant expression}}
// expected-note@+2 {{indeterminate value can only initialize an object of type 'unsigned char' or 'std::byte'; 'char' is invalid}}
#endif
constexpr int bad_char = (__builtin_bit_cast(char[8], pad{1, 2}), 0);
struct pad_buffer { unsigned char data[sizeof(pad)]; };
constexpr bool test_pad_buffer() {
pad x = {1, 2};
pad_buffer y = __builtin_bit_cast(pad_buffer, x);
pad z = __builtin_bit_cast(pad, y);
return x.a == z.a && x.b == z.b;
}
static_assert(test_pad_buffer());

2
clang/tools/libclang/CIndex.cpp
View File

@ -5194,6 +5194,8 @@ CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
return cxstring::createRef("CallExpr");
case CXCursor_ObjCMessageExpr:
return cxstring::createRef("ObjCMessageExpr");
case CXCursor_BuiltinBitCastExpr:
return cxstring::createRef("BuiltinBitCastExpr");
case CXCursor_UnexposedStmt:
return cxstring::createRef("UnexposedStmt");
case CXCursor_DeclStmt:

2
clang/tools/libclang/CXCursor.cpp
View File

@ -716,6 +716,8 @@ CXCursor cxcursor::MakeCXCursor(const Stmt *S, const Decl *Parent,
case Stmt::OMPTargetTeamsDistributeSimdDirectiveClass:
K = CXCursor_OMPTargetTeamsDistributeSimdDirective;
break;
case Stmt::BuiltinBitCastExprClass:
K = CXCursor_BuiltinBitCastExpr;
}
CXCursor C = { K, 0, { Parent, S, TU } };

11
llvm/include/llvm/ADT/APInt.h
View File

@ -2212,6 +2212,15 @@ Optional<APInt> SolveQuadraticEquationWrap(APInt A, APInt B, APInt C,
// See friend declaration above. This additional declaration is required in
// order to compile LLVM with IBM xlC compiler.
hash_code hash_value(const APInt &Arg);
} // End of llvm namespace
/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
/// with the integer held in IntVal.
void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst, unsigned StoreBytes);
/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
/// from Src into IntVal, which is assumed to be wide enough and to hold zero.
void LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes);
} // namespace llvm
#endif

53
llvm/lib/ExecutionEngine/ExecutionEngine.cpp
View File

@ -1019,32 +1019,6 @@ GenericValue ExecutionEngine::getConstantValue(const Constant *C) {
return Result;
}
/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
/// with the integer held in IntVal.
static void StoreIntToMemory(const APInt &IntVal, uint8_t *Dst,
unsigned StoreBytes) {
assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!");
const uint8_t *Src = (const uint8_t *)IntVal.getRawData();
if (sys::IsLittleEndianHost) {
// Little-endian host - the source is ordered from LSB to MSB. Order the
// destination from LSB to MSB: Do a straight copy.
memcpy(Dst, Src, StoreBytes);
} else {
// Big-endian host - the source is an array of 64 bit words ordered from
// LSW to MSW. Each word is ordered from MSB to LSB. Order the destination
// from MSB to LSB: Reverse the word order, but not the bytes in a word.
while (StoreBytes > sizeof(uint64_t)) {
StoreBytes -= sizeof(uint64_t);
// May not be aligned so use memcpy.
memcpy(Dst + StoreBytes, Src, sizeof(uint64_t));
Src += sizeof(uint64_t);
}
memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes);
}
}
void ExecutionEngine::StoreValueToMemory(const GenericValue &Val,
GenericValue *Ptr, Type *Ty) {
const unsigned StoreBytes = getDataLayout().getTypeStoreSize(Ty);
@ -1092,33 +1066,6 @@ void ExecutionEngine::StoreValueToMemory(const GenericValue &Val,
std::reverse((uint8_t*)Ptr, StoreBytes + (uint8_t*)Ptr);
}
/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
/// from Src into IntVal, which is assumed to be wide enough and to hold zero.
static void LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) {
assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!");
uint8_t *Dst = reinterpret_cast<uint8_t *>(
const_cast<uint64_t *>(IntVal.getRawData()));
if (sys::IsLittleEndianHost)
// Little-endian host - the destination must be ordered from LSB to MSB.
// The source is ordered from LSB to MSB: Do a straight copy.
memcpy(Dst, Src, LoadBytes);
else {
// Big-endian - the destination is an array of 64 bit words ordered from
// LSW to MSW. Each word must be ordered from MSB to LSB. The source is
// ordered from MSB to LSB: Reverse the word order, but not the bytes in
// a word.
while (LoadBytes > sizeof(uint64_t)) {
LoadBytes -= sizeof(uint64_t);
// May not be aligned so use memcpy.
memcpy(Dst, Src + LoadBytes, sizeof(uint64_t));
Dst += sizeof(uint64_t);
}
memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes);
}
}
/// FIXME: document
///
void ExecutionEngine::LoadValueFromMemory(GenericValue &Result,

53
llvm/lib/Support/APInt.cpp
View File

@ -2934,3 +2934,56 @@ llvm::APIntOps::SolveQuadraticEquationWrap(APInt A, APInt B, APInt C,
LLVM_DEBUG(dbgs() << __func__ << ": solution (wrap): " << X << '\n');
return X;
}
/// StoreIntToMemory - Fills the StoreBytes bytes of memory starting from Dst
/// with the integer held in IntVal.
void llvm::StoreIntToMemory(const APInt &IntVal, uint8_t *Dst,
unsigned StoreBytes) {
assert((IntVal.getBitWidth()+7)/8 >= StoreBytes && "Integer too small!");
const uint8_t *Src = (const uint8_t *)IntVal.getRawData();
if (sys::IsLittleEndianHost) {
// Little-endian host - the source is ordered from LSB to MSB. Order the
// destination from LSB to MSB: Do a straight copy.
memcpy(Dst, Src, StoreBytes);
} else {
// Big-endian host - the source is an array of 64 bit words ordered from
// LSW to MSW. Each word is ordered from MSB to LSB. Order the destination
// from MSB to LSB: Reverse the word order, but not the bytes in a word.
while (StoreBytes > sizeof(uint64_t)) {
StoreBytes -= sizeof(uint64_t);
// May not be aligned so use memcpy.
memcpy(Dst + StoreBytes, Src, sizeof(uint64_t));
Src += sizeof(uint64_t);
}
memcpy(Dst, Src + sizeof(uint64_t) - StoreBytes, StoreBytes);
}
}
/// LoadIntFromMemory - Loads the integer stored in the LoadBytes bytes starting
/// from Src into IntVal, which is assumed to be wide enough and to hold zero.
void llvm::LoadIntFromMemory(APInt &IntVal, uint8_t *Src, unsigned LoadBytes) {
assert((IntVal.getBitWidth()+7)/8 >= LoadBytes && "Integer too small!");
uint8_t *Dst = reinterpret_cast<uint8_t *>(
const_cast<uint64_t *>(IntVal.getRawData()));
if (sys::IsLittleEndianHost)
// Little-endian host - the destination must be ordered from LSB to MSB.
// The source is ordered from LSB to MSB: Do a straight copy.
memcpy(Dst, Src, LoadBytes);
else {
// Big-endian - the destination is an array of 64 bit words ordered from
// LSW to MSW. Each word must be ordered from MSB to LSB. The source is
// ordered from MSB to LSB: Reverse the word order, but not the bytes in
// a word.
while (LoadBytes > sizeof(uint64_t)) {
LoadBytes -= sizeof(uint64_t);
// May not be aligned so use memcpy.
memcpy(Dst, Src + LoadBytes, sizeof(uint64_t));
Dst += sizeof(uint64_t);
}
memcpy(Dst + sizeof(uint64_t) - LoadBytes, Src, LoadBytes);
}
}