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llvm-project/clang/lib/Analysis/CFG.cpp

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//===- CFG.cpp - Classes for representing and building CFGs ---------------===//
//
// 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 defines the CFG and CFGBuilder classes for representing and
// building Control-Flow Graphs (CFGs) from ASTs.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/CFG.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/Attr.h"
#include "clang/AST/Decl.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclGroup.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/OperationKinds.h"
#include "clang/AST/PrettyPrinter.h"
#include "clang/AST/Stmt.h"
#include "clang/AST/StmtCXX.h"
#include "clang/AST/StmtObjC.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/Type.h"
#include "clang/Analysis/ConstructionContext.h"
#include "clang/Analysis/Support/BumpVector.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/ExceptionSpecificationType.h"
#include "clang/Basic/JsonSupport.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/LangOptions.h"
#include "clang/Basic/SourceLocation.h"
#include "clang/Basic/Specifiers.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/DOTGraphTraits.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/Format.h"
#include "llvm/Support/GraphWriter.h"
#include "llvm/Support/SaveAndRestore.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <memory>
#include <string>
#include <tuple>
#include <utility>
#include <vector>
using namespace clang;
static SourceLocation GetEndLoc(Decl *D) {
if (VarDecl *VD = dyn_cast<VarDecl>(D))
if (Expr *Ex = VD->getInit())
return Ex->getSourceRange().getEnd();
return D->getLocation();
}
/// Returns true on constant values based around a single IntegerLiteral.
/// Allow for use of parentheses, integer casts, and negative signs.
static bool IsIntegerLiteralConstantExpr(const Expr *E) {
// Allow parentheses
E = E->IgnoreParens();
// Allow conversions to different integer kind.
if (const auto *CE = dyn_cast<CastExpr>(E)) {
if (CE->getCastKind() != CK_IntegralCast)
return false;
E = CE->getSubExpr();
}
// Allow negative numbers.
if (const auto *UO = dyn_cast<UnaryOperator>(E)) {
if (UO->getOpcode() != UO_Minus)
return false;
E = UO->getSubExpr();
}
return isa<IntegerLiteral>(E);
}
/// Helper for tryNormalizeBinaryOperator. Attempts to extract an IntegerLiteral
/// constant expression or EnumConstantDecl from the given Expr. If it fails,
/// returns nullptr.
static const Expr *tryTransformToIntOrEnumConstant(const Expr *E) {
E = E->IgnoreParens();
if (IsIntegerLiteralConstantExpr(E))
return E;
if (auto *DR = dyn_cast<DeclRefExpr>(E->IgnoreParenImpCasts()))
return isa<EnumConstantDecl>(DR->getDecl()) ? DR : nullptr;
return nullptr;
}
/// Tries to interpret a binary operator into `Expr Op NumExpr` form, if
/// NumExpr is an integer literal or an enum constant.
///
/// If this fails, at least one of the returned DeclRefExpr or Expr will be
/// null.
static std::tuple<const Expr *, BinaryOperatorKind, const Expr *>
tryNormalizeBinaryOperator(const BinaryOperator *B) {
BinaryOperatorKind Op = B->getOpcode();
const Expr *MaybeDecl = B->getLHS();
const Expr *Constant = tryTransformToIntOrEnumConstant(B->getRHS());
// Expr looked like `0 == Foo` instead of `Foo == 0`
if (Constant == nullptr) {
// Flip the operator
if (Op == BO_GT)
Op = BO_LT;
else if (Op == BO_GE)
Op = BO_LE;
else if (Op == BO_LT)
Op = BO_GT;
else if (Op == BO_LE)
Op = BO_GE;
MaybeDecl = B->getRHS();
Constant = tryTransformToIntOrEnumConstant(B->getLHS());
}
return std::make_tuple(MaybeDecl, Op, Constant);
}
/// For an expression `x == Foo && x == Bar`, this determines whether the
/// `Foo` and `Bar` are either of the same enumeration type, or both integer
/// literals.
///
/// It's an error to pass this arguments that are not either IntegerLiterals
/// or DeclRefExprs (that have decls of type EnumConstantDecl)
static bool areExprTypesCompatible(const Expr *E1, const Expr *E2) {
// User intent isn't clear if they're mixing int literals with enum
// constants.
if (isa<DeclRefExpr>(E1) != isa<DeclRefExpr>(E2))
return false;
// Integer literal comparisons, regardless of literal type, are acceptable.
if (!isa<DeclRefExpr>(E1))
return true;
// IntegerLiterals are handled above and only EnumConstantDecls are expected
// beyond this point
assert(isa<DeclRefExpr>(E1) && isa<DeclRefExpr>(E2));
auto *Decl1 = cast<DeclRefExpr>(E1)->getDecl();
auto *Decl2 = cast<DeclRefExpr>(E2)->getDecl();
assert(isa<EnumConstantDecl>(Decl1) && isa<EnumConstantDecl>(Decl2));
const DeclContext *DC1 = Decl1->getDeclContext();
const DeclContext *DC2 = Decl2->getDeclContext();
assert(isa<EnumDecl>(DC1) && isa<EnumDecl>(DC2));
return DC1 == DC2;
}
namespace {
class CFGBuilder;
/// The CFG builder uses a recursive algorithm to build the CFG. When
/// we process an expression, sometimes we know that we must add the
/// subexpressions as block-level expressions. For example:
///
/// exp1 || exp2
///
/// When processing the '||' expression, we know that exp1 and exp2
/// need to be added as block-level expressions, even though they
/// might not normally need to be. AddStmtChoice records this
/// contextual information. If AddStmtChoice is 'NotAlwaysAdd', then
/// the builder has an option not to add a subexpression as a
/// block-level expression.
class AddStmtChoice {
public:
enum Kind { NotAlwaysAdd = 0, AlwaysAdd = 1 };
AddStmtChoice(Kind a_kind = NotAlwaysAdd) : kind(a_kind) {}
bool alwaysAdd(CFGBuilder &builder,
const Stmt *stmt) const;
/// Return a copy of this object, except with the 'always-add' bit
/// set as specified.
AddStmtChoice withAlwaysAdd(bool alwaysAdd) const {
return AddStmtChoice(alwaysAdd ? AlwaysAdd : NotAlwaysAdd);
}
private:
Kind kind;
};
/// LocalScope - Node in tree of local scopes created for C++ implicit
/// destructor calls generation. It contains list of automatic variables
/// declared in the scope and link to position in previous scope this scope
/// began in.
///
/// The process of creating local scopes is as follows:
/// - Init CFGBuilder::ScopePos with invalid position (equivalent for null),
/// - Before processing statements in scope (e.g. CompoundStmt) create
/// LocalScope object using CFGBuilder::ScopePos as link to previous scope
/// and set CFGBuilder::ScopePos to the end of new scope,
/// - On every occurrence of VarDecl increase CFGBuilder::ScopePos if it points
/// at this VarDecl,
/// - For every normal (without jump) end of scope add to CFGBlock destructors
/// for objects in the current scope,
/// - For every jump add to CFGBlock destructors for objects
/// between CFGBuilder::ScopePos and local scope position saved for jump
/// target. Thanks to C++ restrictions on goto jumps we can be sure that
/// jump target position will be on the path to root from CFGBuilder::ScopePos
/// (adding any variable that doesn't need constructor to be called to
/// LocalScope can break this assumption),
///
class LocalScope {
public:
friend class const_iterator;
using AutomaticVarsTy = BumpVector<VarDecl *>;
/// const_iterator - Iterates local scope backwards and jumps to previous
/// scope on reaching the beginning of currently iterated scope.
class const_iterator {
const LocalScope* Scope = nullptr;
/// VarIter is guaranteed to be greater then 0 for every valid iterator.
/// Invalid iterator (with null Scope) has VarIter equal to 0.
unsigned VarIter = 0;
public:
/// Create invalid iterator. Dereferencing invalid iterator is not allowed.
/// Incrementing invalid iterator is allowed and will result in invalid
/// iterator.
const_iterator() = default;
/// Create valid iterator. In case when S.Prev is an invalid iterator and
/// I is equal to 0, this will create invalid iterator.
const_iterator(const LocalScope& S, unsigned I)
: Scope(&S), VarIter(I) {
// Iterator to "end" of scope is not allowed. Handle it by going up
// in scopes tree possibly up to invalid iterator in the root.
if (VarIter == 0 && Scope)
*this = Scope->Prev;
}
VarDecl *const* operator->() const {
assert(Scope && "Dereferencing invalid iterator is not allowed");
assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
return &Scope->Vars[VarIter - 1];
}
const VarDecl *getFirstVarInScope() const {
assert(Scope && "Dereferencing invalid iterator is not allowed");
assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
return Scope->Vars[0];
}
VarDecl *operator*() const {
return *this->operator->();
}
const_iterator &operator++() {
if (!Scope)
return *this;
assert(VarIter != 0 && "Iterator has invalid value of VarIter member");
--VarIter;
if (VarIter == 0)
*this = Scope->Prev;
return *this;
}
const_iterator operator++(int) {
const_iterator P = *this;
++*this;
return P;
}
bool operator==(const const_iterator &rhs) const {
return Scope == rhs.Scope && VarIter == rhs.VarIter;
}
bool operator!=(const const_iterator &rhs) const {
return !(*this == rhs);
}
explicit operator bool() const {
return *this != const_iterator();
}
int distance(const_iterator L);
const_iterator shared_parent(const_iterator L);
bool pointsToFirstDeclaredVar() { return VarIter == 1; }
};
private:
BumpVectorContext ctx;
/// Automatic variables in order of declaration.
AutomaticVarsTy Vars;
/// Iterator to variable in previous scope that was declared just before
/// begin of this scope.
const_iterator Prev;
public:
/// Constructs empty scope linked to previous scope in specified place.
LocalScope(BumpVectorContext ctx, const_iterator P)
: ctx(std::move(ctx)), Vars(this->ctx, 4), Prev(P) {}
/// Begin of scope in direction of CFG building (backwards).
const_iterator begin() const { return const_iterator(*this, Vars.size()); }
void addVar(VarDecl *VD) {
Vars.push_back(VD, ctx);
}
};
} // namespace
/// distance - Calculates distance from this to L. L must be reachable from this
/// (with use of ++ operator). Cost of calculating the distance is linear w.r.t.
/// number of scopes between this and L.
int LocalScope::const_iterator::distance(LocalScope::const_iterator L) {
int D = 0;
const_iterator F = *this;
while (F.Scope != L.Scope) {
assert(F != const_iterator() &&
"L iterator is not reachable from F iterator.");
D += F.VarIter;
F = F.Scope->Prev;
}
D += F.VarIter - L.VarIter;
return D;
}
/// Calculates the closest parent of this iterator
/// that is in a scope reachable through the parents of L.
/// I.e. when using 'goto' from this to L, the lifetime of all variables
/// between this and shared_parent(L) end.
LocalScope::const_iterator
LocalScope::const_iterator::shared_parent(LocalScope::const_iterator L) {
llvm::SmallPtrSet<const LocalScope *, 4> ScopesOfL;
while (true) {
ScopesOfL.insert(L.Scope);
if (L == const_iterator())
break;
L = L.Scope->Prev;
}
const_iterator F = *this;
while (true) {
if (ScopesOfL.count(F.Scope))
return F;
assert(F != const_iterator() &&
"L iterator is not reachable from F iterator.");
F = F.Scope->Prev;
}
}
namespace {
/// Structure for specifying position in CFG during its build process. It
/// consists of CFGBlock that specifies position in CFG and
/// LocalScope::const_iterator that specifies position in LocalScope graph.
struct BlockScopePosPair {
CFGBlock *block = nullptr;
LocalScope::const_iterator scopePosition;
BlockScopePosPair() = default;
BlockScopePosPair(CFGBlock *b, LocalScope::const_iterator scopePos)
: block(b), scopePosition(scopePos) {}
};
/// TryResult - a class representing a variant over the values
/// 'true', 'false', or 'unknown'. This is returned by tryEvaluateBool,
/// and is used by the CFGBuilder to decide if a branch condition
/// can be decided up front during CFG construction.
class TryResult {
int X = -1;
public:
TryResult() = default;
TryResult(bool b) : X(b ? 1 : 0) {}
bool isTrue() const { return X == 1; }
bool isFalse() const { return X == 0; }
bool isKnown() const { return X >= 0; }
void negate() {
assert(isKnown());
X ^= 0x1;
}
};
} // namespace
static TryResult bothKnownTrue(TryResult R1, TryResult R2) {
if (!R1.isKnown() || !R2.isKnown())
return TryResult();
return TryResult(R1.isTrue() && R2.isTrue());
}
namespace {
class reverse_children {
llvm::SmallVector<Stmt *, 12> childrenBuf;
ArrayRef<Stmt *> children;
public:
reverse_children(Stmt *S);
using iterator = ArrayRef<Stmt *>::reverse_iterator;
iterator begin() const { return children.rbegin(); }
iterator end() const { return children.rend(); }
};
} // namespace
reverse_children::reverse_children(Stmt *S) {
if (CallExpr *CE = dyn_cast<CallExpr>(S)) {
children = CE->getRawSubExprs();
return;
}
switch (S->getStmtClass()) {
// Note: Fill in this switch with more cases we want to optimize.
case Stmt::InitListExprClass: {
InitListExpr *IE = cast<InitListExpr>(S);
children = llvm::makeArrayRef(reinterpret_cast<Stmt**>(IE->getInits()),
IE->getNumInits());
return;
}
default:
break;
}
// Default case for all other statements.
for (Stmt *SubStmt : S->children())
childrenBuf.push_back(SubStmt);
// This needs to be done *after* childrenBuf has been populated.
children = childrenBuf;
}
namespace {
/// CFGBuilder - This class implements CFG construction from an AST.
/// The builder is stateful: an instance of the builder should be used to only
/// construct a single CFG.
///
/// Example usage:
///
/// CFGBuilder builder;
/// std::unique_ptr<CFG> cfg = builder.buildCFG(decl, stmt1);
///
/// CFG construction is done via a recursive walk of an AST. We actually parse
/// the AST in reverse order so that the successor of a basic block is
/// constructed prior to its predecessor. This allows us to nicely capture
/// implicit fall-throughs without extra basic blocks.
class CFGBuilder {
using JumpTarget = BlockScopePosPair;
using JumpSource = BlockScopePosPair;
ASTContext *Context;
std::unique_ptr<CFG> cfg;
// Current block.
CFGBlock *Block = nullptr;
// Block after the current block.
CFGBlock *Succ = nullptr;
JumpTarget ContinueJumpTarget;
JumpTarget BreakJumpTarget;
JumpTarget SEHLeaveJumpTarget;
CFGBlock *SwitchTerminatedBlock = nullptr;
CFGBlock *DefaultCaseBlock = nullptr;
// This can point either to a try or a __try block. The frontend forbids
// mixing both kinds in one function, so having one for both is enough.
CFGBlock *TryTerminatedBlock = nullptr;
// Current position in local scope.
LocalScope::const_iterator ScopePos;
// LabelMap records the mapping from Label expressions to their jump targets.
using LabelMapTy = llvm::DenseMap<LabelDecl *, JumpTarget>;
LabelMapTy LabelMap;
// A list of blocks that end with a "goto" that must be backpatched to their
// resolved targets upon completion of CFG construction.
using BackpatchBlocksTy = std::vector<JumpSource>;
BackpatchBlocksTy BackpatchBlocks;
// A list of labels whose address has been taken (for indirect gotos).
using LabelSetTy = llvm::SmallSetVector<LabelDecl *, 8>;
LabelSetTy AddressTakenLabels;
// Information about the currently visited C++ object construction site.
// This is set in the construction trigger and read when the constructor
// or a function that returns an object by value is being visited.
llvm::DenseMap<Expr *, const ConstructionContextLayer *>
ConstructionContextMap;
using DeclsWithEndedScopeSetTy = llvm::SmallSetVector<VarDecl *, 16>;
DeclsWithEndedScopeSetTy DeclsWithEndedScope;
bool badCFG = false;
const CFG::BuildOptions &BuildOpts;
// State to track for building switch statements.
bool switchExclusivelyCovered = false;
Expr::EvalResult *switchCond = nullptr;
CFG::BuildOptions::ForcedBlkExprs::value_type *cachedEntry = nullptr;
const Stmt *lastLookup = nullptr;
// Caches boolean evaluations of expressions to avoid multiple re-evaluations
// during construction of branches for chained logical operators.
using CachedBoolEvalsTy = llvm::DenseMap<Expr *, TryResult>;
CachedBoolEvalsTy CachedBoolEvals;
public:
explicit CFGBuilder(ASTContext *astContext,
const CFG::BuildOptions &buildOpts)
: Context(astContext), cfg(new CFG()), // crew a new CFG
ConstructionContextMap(), BuildOpts(buildOpts) {}
// buildCFG - Used by external clients to construct the CFG.
std::unique_ptr<CFG> buildCFG(const Decl *D, Stmt *Statement);
bool alwaysAdd(const Stmt *stmt);
private:
// Visitors to walk an AST and construct the CFG.
CFGBlock *VisitAddrLabelExpr(AddrLabelExpr *A, AddStmtChoice asc);
CFGBlock *VisitBinaryOperator(BinaryOperator *B, AddStmtChoice asc);
CFGBlock *VisitBreakStmt(BreakStmt *B);
CFGBlock *VisitCallExpr(CallExpr *C, AddStmtChoice asc);
CFGBlock *VisitCaseStmt(CaseStmt *C);
CFGBlock *VisitChooseExpr(ChooseExpr *C, AddStmtChoice asc);
CFGBlock *VisitCompoundStmt(CompoundStmt *C, bool ExternallyDestructed);
CFGBlock *VisitConditionalOperator(AbstractConditionalOperator *C,
AddStmtChoice asc);
CFGBlock *VisitContinueStmt(ContinueStmt *C);
CFGBlock *VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E,
AddStmtChoice asc);
CFGBlock *VisitCXXCatchStmt(CXXCatchStmt *S);
CFGBlock *VisitCXXConstructExpr(CXXConstructExpr *C, AddStmtChoice asc);
CFGBlock *VisitCXXNewExpr(CXXNewExpr *DE, AddStmtChoice asc);
CFGBlock *VisitCXXDeleteExpr(CXXDeleteExpr *DE, AddStmtChoice asc);
CFGBlock *VisitCXXForRangeStmt(CXXForRangeStmt *S);
CFGBlock *VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
AddStmtChoice asc);
CFGBlock *VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C,
AddStmtChoice asc);
CFGBlock *VisitCXXThrowExpr(CXXThrowExpr *T);
CFGBlock *VisitCXXTryStmt(CXXTryStmt *S);
CFGBlock *VisitDeclStmt(DeclStmt *DS);
CFGBlock *VisitDeclSubExpr(DeclStmt *DS);
CFGBlock *VisitDefaultStmt(DefaultStmt *D);
CFGBlock *VisitDoStmt(DoStmt *D);
CFGBlock *VisitExprWithCleanups(ExprWithCleanups *E,
AddStmtChoice asc, bool ExternallyDestructed);
CFGBlock *VisitForStmt(ForStmt *F);
CFGBlock *VisitGotoStmt(GotoStmt *G);
CFGBlock *VisitGCCAsmStmt(GCCAsmStmt *G, AddStmtChoice asc);
CFGBlock *VisitIfStmt(IfStmt *I);
CFGBlock *VisitImplicitCastExpr(ImplicitCastExpr *E, AddStmtChoice asc);
CFGBlock *VisitConstantExpr(ConstantExpr *E, AddStmtChoice asc);
CFGBlock *VisitIndirectGotoStmt(IndirectGotoStmt *I);
CFGBlock *VisitLabelStmt(LabelStmt *L);
CFGBlock *VisitBlockExpr(BlockExpr *E, AddStmtChoice asc);
CFGBlock *VisitLambdaExpr(LambdaExpr *E, AddStmtChoice asc);
CFGBlock *VisitLogicalOperator(BinaryOperator *B);
std::pair<CFGBlock *, CFGBlock *> VisitLogicalOperator(BinaryOperator *B,
Stmt *Term,
CFGBlock *TrueBlock,
CFGBlock *FalseBlock);
CFGBlock *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE,
AddStmtChoice asc);
CFGBlock *VisitMemberExpr(MemberExpr *M, AddStmtChoice asc);
CFGBlock *VisitObjCAtCatchStmt(ObjCAtCatchStmt *S);
CFGBlock *VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S);
CFGBlock *VisitObjCAtThrowStmt(ObjCAtThrowStmt *S);
CFGBlock *VisitObjCAtTryStmt(ObjCAtTryStmt *S);
CFGBlock *VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S);
CFGBlock *VisitObjCForCollectionStmt(ObjCForCollectionStmt *S);
CFGBlock *VisitObjCMessageExpr(ObjCMessageExpr *E, AddStmtChoice asc);
CFGBlock *VisitPseudoObjectExpr(PseudoObjectExpr *E);
CFGBlock *VisitReturnStmt(Stmt *S);
CFGBlock *VisitSEHExceptStmt(SEHExceptStmt *S);
CFGBlock *VisitSEHFinallyStmt(SEHFinallyStmt *S);
CFGBlock *VisitSEHLeaveStmt(SEHLeaveStmt *S);
CFGBlock *VisitSEHTryStmt(SEHTryStmt *S);
CFGBlock *VisitStmtExpr(StmtExpr *S, AddStmtChoice asc);
CFGBlock *VisitSwitchStmt(SwitchStmt *S);
CFGBlock *VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E,
AddStmtChoice asc);
CFGBlock *VisitUnaryOperator(UnaryOperator *U, AddStmtChoice asc);
CFGBlock *VisitWhileStmt(WhileStmt *W);
CFGBlock *Visit(Stmt *S, AddStmtChoice asc = AddStmtChoice::NotAlwaysAdd,
bool ExternallyDestructed = false);
CFGBlock *VisitStmt(Stmt *S, AddStmtChoice asc);
CFGBlock *VisitChildren(Stmt *S);
CFGBlock *VisitNoRecurse(Expr *E, AddStmtChoice asc);
CFGBlock *VisitOMPExecutableDirective(OMPExecutableDirective *D,
AddStmtChoice asc);
void maybeAddScopeBeginForVarDecl(CFGBlock *B, const VarDecl *VD,
const Stmt *S) {
if (ScopePos && (VD == ScopePos.getFirstVarInScope()))
appendScopeBegin(B, VD, S);
}
/// When creating the CFG for temporary destructors, we want to mirror the
/// branch structure of the corresponding constructor calls.
/// Thus, while visiting a statement for temporary destructors, we keep a
/// context to keep track of the following information:
/// - whether a subexpression is executed unconditionally
/// - if a subexpression is executed conditionally, the first
/// CXXBindTemporaryExpr we encounter in that subexpression (which
/// corresponds to the last temporary destructor we have to call for this
/// subexpression) and the CFG block at that point (which will become the
/// successor block when inserting the decision point).
///
/// That way, we can build the branch structure for temporary destructors as
/// follows:
/// 1. If a subexpression is executed unconditionally, we add the temporary
/// destructor calls to the current block.
/// 2. If a subexpression is executed conditionally, when we encounter a
/// CXXBindTemporaryExpr:
/// a) If it is the first temporary destructor call in the subexpression,
/// we remember the CXXBindTemporaryExpr and the current block in the
/// TempDtorContext; we start a new block, and insert the temporary
/// destructor call.
/// b) Otherwise, add the temporary destructor call to the current block.
/// 3. When we finished visiting a conditionally executed subexpression,
/// and we found at least one temporary constructor during the visitation
/// (2.a has executed), we insert a decision block that uses the
/// CXXBindTemporaryExpr as terminator, and branches to the current block
/// if the CXXBindTemporaryExpr was marked executed, and otherwise
/// branches to the stored successor.
struct TempDtorContext {
TempDtorContext() = default;
TempDtorContext(TryResult KnownExecuted)
: IsConditional(true), KnownExecuted(KnownExecuted) {}
/// Returns whether we need to start a new branch for a temporary destructor
/// call. This is the case when the temporary destructor is
/// conditionally executed, and it is the first one we encounter while
/// visiting a subexpression - other temporary destructors at the same level
/// will be added to the same block and are executed under the same
/// condition.
bool needsTempDtorBranch() const {
return IsConditional && !TerminatorExpr;
}
/// Remember the successor S of a temporary destructor decision branch for
/// the corresponding CXXBindTemporaryExpr E.
void setDecisionPoint(CFGBlock *S, CXXBindTemporaryExpr *E) {
Succ = S;
TerminatorExpr = E;
}
const bool IsConditional = false;
const TryResult KnownExecuted = true;
CFGBlock *Succ = nullptr;
CXXBindTemporaryExpr *TerminatorExpr = nullptr;
};
// Visitors to walk an AST and generate destructors of temporaries in
// full expression.
CFGBlock *VisitForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
TempDtorContext &Context);
CFGBlock *VisitChildrenForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
TempDtorContext &Context);
CFGBlock *VisitBinaryOperatorForTemporaryDtors(BinaryOperator *E,
bool ExternallyDestructed,
TempDtorContext &Context);
CFGBlock *VisitCXXBindTemporaryExprForTemporaryDtors(
CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context);
CFGBlock *VisitConditionalOperatorForTemporaryDtors(
AbstractConditionalOperator *E, bool ExternallyDestructed,
TempDtorContext &Context);
void InsertTempDtorDecisionBlock(const TempDtorContext &Context,
CFGBlock *FalseSucc = nullptr);
// NYS == Not Yet Supported
CFGBlock *NYS() {
badCFG = true;
return Block;
}
// Remember to apply the construction context based on the current \p Layer
// when constructing the CFG element for \p CE.
void consumeConstructionContext(const ConstructionContextLayer *Layer,
Expr *E);
// Scan \p Child statement to find constructors in it, while keeping in mind
// that its parent statement is providing a partial construction context
// described by \p Layer. If a constructor is found, it would be assigned
// the context based on the layer. If an additional construction context layer
// is found, the function recurses into that.
void findConstructionContexts(const ConstructionContextLayer *Layer,
Stmt *Child);
// Scan all arguments of a call expression for a construction context.
// These sorts of call expressions don't have a common superclass,
// hence strict duck-typing.
template <typename CallLikeExpr,
typename = typename std::enable_if<
std::is_same<CallLikeExpr, CallExpr>::value ||
std::is_same<CallLikeExpr, CXXConstructExpr>::value ||
std::is_same<CallLikeExpr, ObjCMessageExpr>::value>>
void findConstructionContextsForArguments(CallLikeExpr *E) {
for (unsigned i = 0, e = E->getNumArgs(); i != e; ++i) {
Expr *Arg = E->getArg(i);
if (Arg->getType()->getAsCXXRecordDecl() && !Arg->isGLValue())
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(),
ConstructionContextItem(E, i)),
Arg);
}
}
// Unset the construction context after consuming it. This is done immediately
// after adding the CFGConstructor or CFGCXXRecordTypedCall element, so
// there's no need to do this manually in every Visit... function.
void cleanupConstructionContext(Expr *E);
void autoCreateBlock() { if (!Block) Block = createBlock(); }
CFGBlock *createBlock(bool add_successor = true);
CFGBlock *createNoReturnBlock();
CFGBlock *addStmt(Stmt *S) {
return Visit(S, AddStmtChoice::AlwaysAdd);
}
CFGBlock *addInitializer(CXXCtorInitializer *I);
void addLoopExit(const Stmt *LoopStmt);
void addAutomaticObjDtors(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S);
void addLifetimeEnds(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S);
void addAutomaticObjHandling(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S);
void addImplicitDtorsForDestructor(const CXXDestructorDecl *DD);
void addScopesEnd(LocalScope::const_iterator B, LocalScope::const_iterator E,
Stmt *S);
void getDeclsWithEndedScope(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S);
// Local scopes creation.
LocalScope* createOrReuseLocalScope(LocalScope* Scope);
void addLocalScopeForStmt(Stmt *S);
LocalScope* addLocalScopeForDeclStmt(DeclStmt *DS,
LocalScope* Scope = nullptr);
LocalScope* addLocalScopeForVarDecl(VarDecl *VD, LocalScope* Scope = nullptr);
void addLocalScopeAndDtors(Stmt *S);
const ConstructionContext *retrieveAndCleanupConstructionContext(Expr *E) {
if (!BuildOpts.AddRichCXXConstructors)
return nullptr;
const ConstructionContextLayer *Layer = ConstructionContextMap.lookup(E);
if (!Layer)
return nullptr;
cleanupConstructionContext(E);
return ConstructionContext::createFromLayers(cfg->getBumpVectorContext(),
Layer);
}
// Interface to CFGBlock - adding CFGElements.
void appendStmt(CFGBlock *B, const Stmt *S) {
if (alwaysAdd(S) && cachedEntry)
cachedEntry->second = B;
// All block-level expressions should have already been IgnoreParens()ed.
assert(!isa<Expr>(S) || cast<Expr>(S)->IgnoreParens() == S);
B->appendStmt(const_cast<Stmt*>(S), cfg->getBumpVectorContext());
}
void appendConstructor(CFGBlock *B, CXXConstructExpr *CE) {
if (const ConstructionContext *CC =
retrieveAndCleanupConstructionContext(CE)) {
B->appendConstructor(CE, CC, cfg->getBumpVectorContext());
return;
}
// No valid construction context found. Fall back to statement.
B->appendStmt(CE, cfg->getBumpVectorContext());
}
void appendCall(CFGBlock *B, CallExpr *CE) {
if (alwaysAdd(CE) && cachedEntry)
cachedEntry->second = B;
if (const ConstructionContext *CC =
retrieveAndCleanupConstructionContext(CE)) {
B->appendCXXRecordTypedCall(CE, CC, cfg->getBumpVectorContext());
return;
}
// No valid construction context found. Fall back to statement.
B->appendStmt(CE, cfg->getBumpVectorContext());
}
void appendInitializer(CFGBlock *B, CXXCtorInitializer *I) {
B->appendInitializer(I, cfg->getBumpVectorContext());
}
void appendNewAllocator(CFGBlock *B, CXXNewExpr *NE) {
B->appendNewAllocator(NE, cfg->getBumpVectorContext());
}
void appendBaseDtor(CFGBlock *B, const CXXBaseSpecifier *BS) {
B->appendBaseDtor(BS, cfg->getBumpVectorContext());
}
void appendMemberDtor(CFGBlock *B, FieldDecl *FD) {
B->appendMemberDtor(FD, cfg->getBumpVectorContext());
}
void appendObjCMessage(CFGBlock *B, ObjCMessageExpr *ME) {
if (alwaysAdd(ME) && cachedEntry)
cachedEntry->second = B;
if (const ConstructionContext *CC =
retrieveAndCleanupConstructionContext(ME)) {
B->appendCXXRecordTypedCall(ME, CC, cfg->getBumpVectorContext());
return;
}
B->appendStmt(const_cast<ObjCMessageExpr *>(ME),
cfg->getBumpVectorContext());
}
void appendTemporaryDtor(CFGBlock *B, CXXBindTemporaryExpr *E) {
B->appendTemporaryDtor(E, cfg->getBumpVectorContext());
}
void appendAutomaticObjDtor(CFGBlock *B, VarDecl *VD, Stmt *S) {
B->appendAutomaticObjDtor(VD, S, cfg->getBumpVectorContext());
}
void appendLifetimeEnds(CFGBlock *B, VarDecl *VD, Stmt *S) {
B->appendLifetimeEnds(VD, S, cfg->getBumpVectorContext());
}
void appendLoopExit(CFGBlock *B, const Stmt *LoopStmt) {
B->appendLoopExit(LoopStmt, cfg->getBumpVectorContext());
}
void appendDeleteDtor(CFGBlock *B, CXXRecordDecl *RD, CXXDeleteExpr *DE) {
B->appendDeleteDtor(RD, DE, cfg->getBumpVectorContext());
}
void prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk,
LocalScope::const_iterator B, LocalScope::const_iterator E);
void prependAutomaticObjLifetimeWithTerminator(CFGBlock *Blk,
LocalScope::const_iterator B,
LocalScope::const_iterator E);
const VarDecl *
prependAutomaticObjScopeEndWithTerminator(CFGBlock *Blk,
LocalScope::const_iterator B,
LocalScope::const_iterator E);
void addSuccessor(CFGBlock *B, CFGBlock *S, bool IsReachable = true) {
B->addSuccessor(CFGBlock::AdjacentBlock(S, IsReachable),
cfg->getBumpVectorContext());
}
/// Add a reachable successor to a block, with the alternate variant that is
/// unreachable.
void addSuccessor(CFGBlock *B, CFGBlock *ReachableBlock, CFGBlock *AltBlock) {
B->addSuccessor(CFGBlock::AdjacentBlock(ReachableBlock, AltBlock),
cfg->getBumpVectorContext());
}
void appendScopeBegin(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
if (BuildOpts.AddScopes)
B->appendScopeBegin(VD, S, cfg->getBumpVectorContext());
}
void prependScopeBegin(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
if (BuildOpts.AddScopes)
B->prependScopeBegin(VD, S, cfg->getBumpVectorContext());
}
void appendScopeEnd(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
if (BuildOpts.AddScopes)
B->appendScopeEnd(VD, S, cfg->getBumpVectorContext());
}
void prependScopeEnd(CFGBlock *B, const VarDecl *VD, const Stmt *S) {
if (BuildOpts.AddScopes)
B->prependScopeEnd(VD, S, cfg->getBumpVectorContext());
}
/// Find a relational comparison with an expression evaluating to a
/// boolean and a constant other than 0 and 1.
/// e.g. if ((x < y) == 10)
TryResult checkIncorrectRelationalOperator(const BinaryOperator *B) {
const Expr *LHSExpr = B->getLHS()->IgnoreParens();
const Expr *RHSExpr = B->getRHS()->IgnoreParens();
const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
const Expr *BoolExpr = RHSExpr;
bool IntFirst = true;
if (!IntLiteral) {
IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
BoolExpr = LHSExpr;
IntFirst = false;
}
if (!IntLiteral || !BoolExpr->isKnownToHaveBooleanValue())
return TryResult();
llvm::APInt IntValue = IntLiteral->getValue();
if ((IntValue == 1) || (IntValue == 0))
return TryResult();
bool IntLarger = IntLiteral->getType()->isUnsignedIntegerType() ||
!IntValue.isNegative();
BinaryOperatorKind Bok = B->getOpcode();
if (Bok == BO_GT || Bok == BO_GE) {
// Always true for 10 > bool and bool > -1
// Always false for -1 > bool and bool > 10
return TryResult(IntFirst == IntLarger);
} else {
// Always true for -1 < bool and bool < 10
// Always false for 10 < bool and bool < -1
return TryResult(IntFirst != IntLarger);
}
}
/// Find an incorrect equality comparison. Either with an expression
/// evaluating to a boolean and a constant other than 0 and 1.
/// e.g. if (!x == 10) or a bitwise and/or operation that always evaluates to
/// true/false e.q. (x & 8) == 4.
TryResult checkIncorrectEqualityOperator(const BinaryOperator *B) {
const Expr *LHSExpr = B->getLHS()->IgnoreParens();
const Expr *RHSExpr = B->getRHS()->IgnoreParens();
const IntegerLiteral *IntLiteral = dyn_cast<IntegerLiteral>(LHSExpr);
const Expr *BoolExpr = RHSExpr;
if (!IntLiteral) {
IntLiteral = dyn_cast<IntegerLiteral>(RHSExpr);
BoolExpr = LHSExpr;
}
if (!IntLiteral)
return TryResult();
const BinaryOperator *BitOp = dyn_cast<BinaryOperator>(BoolExpr);
if (BitOp && (BitOp->getOpcode() == BO_And ||
BitOp->getOpcode() == BO_Or)) {
const Expr *LHSExpr2 = BitOp->getLHS()->IgnoreParens();
const Expr *RHSExpr2 = BitOp->getRHS()->IgnoreParens();
const IntegerLiteral *IntLiteral2 = dyn_cast<IntegerLiteral>(LHSExpr2);
if (!IntLiteral2)
IntLiteral2 = dyn_cast<IntegerLiteral>(RHSExpr2);
if (!IntLiteral2)
return TryResult();
llvm::APInt L1 = IntLiteral->getValue();
llvm::APInt L2 = IntLiteral2->getValue();
if ((BitOp->getOpcode() == BO_And && (L2 & L1) != L1) ||
(BitOp->getOpcode() == BO_Or && (L2 | L1) != L1)) {
if (BuildOpts.Observer)
BuildOpts.Observer->compareBitwiseEquality(B,
B->getOpcode() != BO_EQ);
TryResult(B->getOpcode() != BO_EQ);
}
} else if (BoolExpr->isKnownToHaveBooleanValue()) {
llvm::APInt IntValue = IntLiteral->getValue();
if ((IntValue == 1) || (IntValue == 0)) {
return TryResult();
}
return TryResult(B->getOpcode() != BO_EQ);
}
return TryResult();
}
TryResult analyzeLogicOperatorCondition(BinaryOperatorKind Relation,
const llvm::APSInt &Value1,
const llvm::APSInt &Value2) {
assert(Value1.isSigned() == Value2.isSigned());
switch (Relation) {
default:
return TryResult();
case BO_EQ:
return TryResult(Value1 == Value2);
case BO_NE:
return TryResult(Value1 != Value2);
case BO_LT:
return TryResult(Value1 < Value2);
case BO_LE:
return TryResult(Value1 <= Value2);
case BO_GT:
return TryResult(Value1 > Value2);
case BO_GE:
return TryResult(Value1 >= Value2);
}
}
/// Find a pair of comparison expressions with or without parentheses
/// with a shared variable and constants and a logical operator between them
/// that always evaluates to either true or false.
/// e.g. if (x != 3 || x != 4)
TryResult checkIncorrectLogicOperator(const BinaryOperator *B) {
assert(B->isLogicalOp());
const BinaryOperator *LHS =
dyn_cast<BinaryOperator>(B->getLHS()->IgnoreParens());
const BinaryOperator *RHS =
dyn_cast<BinaryOperator>(B->getRHS()->IgnoreParens());
if (!LHS || !RHS)
return {};
if (!LHS->isComparisonOp() || !RHS->isComparisonOp())
return {};
const Expr *DeclExpr1;
const Expr *NumExpr1;
BinaryOperatorKind BO1;
std::tie(DeclExpr1, BO1, NumExpr1) = tryNormalizeBinaryOperator(LHS);
if (!DeclExpr1 || !NumExpr1)
return {};
const Expr *DeclExpr2;
const Expr *NumExpr2;
BinaryOperatorKind BO2;
std::tie(DeclExpr2, BO2, NumExpr2) = tryNormalizeBinaryOperator(RHS);
if (!DeclExpr2 || !NumExpr2)
return {};
// Check that it is the same variable on both sides.
if (!Expr::isSameComparisonOperand(DeclExpr1, DeclExpr2))
return {};
// Make sure the user's intent is clear (e.g. they're comparing against two
// int literals, or two things from the same enum)
if (!areExprTypesCompatible(NumExpr1, NumExpr2))
return {};
Expr::EvalResult L1Result, L2Result;
if (!NumExpr1->EvaluateAsInt(L1Result, *Context) ||
!NumExpr2->EvaluateAsInt(L2Result, *Context))
return {};
llvm::APSInt L1 = L1Result.Val.getInt();
llvm::APSInt L2 = L2Result.Val.getInt();
// Can't compare signed with unsigned or with different bit width.
if (L1.isSigned() != L2.isSigned() || L1.getBitWidth() != L2.getBitWidth())
return {};
// Values that will be used to determine if result of logical
// operator is always true/false
const llvm::APSInt Values[] = {
// Value less than both Value1 and Value2
llvm::APSInt::getMinValue(L1.getBitWidth(), L1.isUnsigned()),
// L1
L1,
// Value between Value1 and Value2
((L1 < L2) ? L1 : L2) + llvm::APSInt(llvm::APInt(L1.getBitWidth(), 1),
L1.isUnsigned()),
// L2
L2,
// Value greater than both Value1 and Value2
llvm::APSInt::getMaxValue(L1.getBitWidth(), L1.isUnsigned()),
};
// Check whether expression is always true/false by evaluating the following
// * variable x is less than the smallest literal.
// * variable x is equal to the smallest literal.
// * Variable x is between smallest and largest literal.
// * Variable x is equal to the largest literal.
// * Variable x is greater than largest literal.
bool AlwaysTrue = true, AlwaysFalse = true;
// Track value of both subexpressions. If either side is always
// true/false, another warning should have already been emitted.
bool LHSAlwaysTrue = true, LHSAlwaysFalse = true;
bool RHSAlwaysTrue = true, RHSAlwaysFalse = true;
for (const llvm::APSInt &Value : Values) {
TryResult Res1, Res2;
Res1 = analyzeLogicOperatorCondition(BO1, Value, L1);
Res2 = analyzeLogicOperatorCondition(BO2, Value, L2);
if (!Res1.isKnown() || !Res2.isKnown())
return {};
if (B->getOpcode() == BO_LAnd) {
AlwaysTrue &= (Res1.isTrue() && Res2.isTrue());
AlwaysFalse &= !(Res1.isTrue() && Res2.isTrue());
} else {
AlwaysTrue &= (Res1.isTrue() || Res2.isTrue());
AlwaysFalse &= !(Res1.isTrue() || Res2.isTrue());
}
LHSAlwaysTrue &= Res1.isTrue();
LHSAlwaysFalse &= Res1.isFalse();
RHSAlwaysTrue &= Res2.isTrue();
RHSAlwaysFalse &= Res2.isFalse();
}
if (AlwaysTrue || AlwaysFalse) {
if (!LHSAlwaysTrue && !LHSAlwaysFalse && !RHSAlwaysTrue &&
!RHSAlwaysFalse && BuildOpts.Observer)
BuildOpts.Observer->compareAlwaysTrue(B, AlwaysTrue);
return TryResult(AlwaysTrue);
}
return {};
}
/// A bitwise-or with a non-zero constant always evaluates to true.
TryResult checkIncorrectBitwiseOrOperator(const BinaryOperator *B) {
const Expr *LHSConstant =
tryTransformToIntOrEnumConstant(B->getLHS()->IgnoreParenImpCasts());
const Expr *RHSConstant =
tryTransformToIntOrEnumConstant(B->getRHS()->IgnoreParenImpCasts());
if ((LHSConstant && RHSConstant) || (!LHSConstant && !RHSConstant))
return {};
const Expr *Constant = LHSConstant ? LHSConstant : RHSConstant;
Expr::EvalResult Result;
if (!Constant->EvaluateAsInt(Result, *Context))
return {};
if (Result.Val.getInt() == 0)
return {};
if (BuildOpts.Observer)
BuildOpts.Observer->compareBitwiseOr(B);
return TryResult(true);
}
/// Try and evaluate an expression to an integer constant.
bool tryEvaluate(Expr *S, Expr::EvalResult &outResult) {
if (!BuildOpts.PruneTriviallyFalseEdges)
return false;
return !S->isTypeDependent() &&
!S->isValueDependent() &&
S->EvaluateAsRValue(outResult, *Context);
}
/// tryEvaluateBool - Try and evaluate the Stmt and return 0 or 1
/// if we can evaluate to a known value, otherwise return -1.
TryResult tryEvaluateBool(Expr *S) {
if (!BuildOpts.PruneTriviallyFalseEdges ||
S->isTypeDependent() || S->isValueDependent())
return {};
if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(S)) {
if (Bop->isLogicalOp() || Bop->isEqualityOp()) {
// Check the cache first.
CachedBoolEvalsTy::iterator I = CachedBoolEvals.find(S);
if (I != CachedBoolEvals.end())
return I->second; // already in map;
// Retrieve result at first, or the map might be updated.
TryResult Result = evaluateAsBooleanConditionNoCache(S);
CachedBoolEvals[S] = Result; // update or insert
return Result;
}
else {
switch (Bop->getOpcode()) {
default: break;
// For 'x & 0' and 'x * 0', we can determine that
// the value is always false.
case BO_Mul:
case BO_And: {
// If either operand is zero, we know the value
// must be false.
Expr::EvalResult LHSResult;
if (Bop->getLHS()->EvaluateAsInt(LHSResult, *Context)) {
llvm::APSInt IntVal = LHSResult.Val.getInt();
if (!IntVal.getBoolValue()) {
return TryResult(false);
}
}
Expr::EvalResult RHSResult;
if (Bop->getRHS()->EvaluateAsInt(RHSResult, *Context)) {
llvm::APSInt IntVal = RHSResult.Val.getInt();
if (!IntVal.getBoolValue()) {
return TryResult(false);
}
}
}
break;
}
}
}
return evaluateAsBooleanConditionNoCache(S);
}
/// Evaluate as boolean \param E without using the cache.
TryResult evaluateAsBooleanConditionNoCache(Expr *E) {
if (BinaryOperator *Bop = dyn_cast<BinaryOperator>(E)) {
if (Bop->isLogicalOp()) {
TryResult LHS = tryEvaluateBool(Bop->getLHS());
if (LHS.isKnown()) {
// 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 (LHS.isTrue() == (Bop->getOpcode() == BO_LOr))
return LHS.isTrue();
TryResult RHS = tryEvaluateBool(Bop->getRHS());
if (RHS.isKnown()) {
if (Bop->getOpcode() == BO_LOr)
return LHS.isTrue() || RHS.isTrue();
else
return LHS.isTrue() && RHS.isTrue();
}
} else {
TryResult RHS = tryEvaluateBool(Bop->getRHS());
if (RHS.isKnown()) {
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
if (RHS.isTrue() == (Bop->getOpcode() == BO_LOr))
return RHS.isTrue();
} else {
TryResult BopRes = checkIncorrectLogicOperator(Bop);
if (BopRes.isKnown())
return BopRes.isTrue();
}
}
return {};
} else if (Bop->isEqualityOp()) {
TryResult BopRes = checkIncorrectEqualityOperator(Bop);
if (BopRes.isKnown())
return BopRes.isTrue();
} else if (Bop->isRelationalOp()) {
TryResult BopRes = checkIncorrectRelationalOperator(Bop);
if (BopRes.isKnown())
return BopRes.isTrue();
} else if (Bop->getOpcode() == BO_Or) {
TryResult BopRes = checkIncorrectBitwiseOrOperator(Bop);
if (BopRes.isKnown())
return BopRes.isTrue();
}
}
bool Result;
if (E->EvaluateAsBooleanCondition(Result, *Context))
return Result;
return {};
}
bool hasTrivialDestructor(VarDecl *VD);
};
} // namespace
inline bool AddStmtChoice::alwaysAdd(CFGBuilder &builder,
const Stmt *stmt) const {
return builder.alwaysAdd(stmt) || kind == AlwaysAdd;
}
bool CFGBuilder::alwaysAdd(const Stmt *stmt) {
bool shouldAdd = BuildOpts.alwaysAdd(stmt);
if (!BuildOpts.forcedBlkExprs)
return shouldAdd;
if (lastLookup == stmt) {
if (cachedEntry) {
assert(cachedEntry->first == stmt);
return true;
}
return shouldAdd;
}
lastLookup = stmt;
// Perform the lookup!
CFG::BuildOptions::ForcedBlkExprs *fb = *BuildOpts.forcedBlkExprs;
if (!fb) {
// No need to update 'cachedEntry', since it will always be null.
assert(!cachedEntry);
return shouldAdd;
}
CFG::BuildOptions::ForcedBlkExprs::iterator itr = fb->find(stmt);
if (itr == fb->end()) {
cachedEntry = nullptr;
return shouldAdd;
}
cachedEntry = &*itr;
return true;
}
// FIXME: Add support for dependent-sized array types in C++?
// Does it even make sense to build a CFG for an uninstantiated template?
static const VariableArrayType *FindVA(const Type *t) {
while (const ArrayType *vt = dyn_cast<ArrayType>(t)) {
if (const VariableArrayType *vat = dyn_cast<VariableArrayType>(vt))
if (vat->getSizeExpr())
return vat;
t = vt->getElementType().getTypePtr();
}
return nullptr;
}
void CFGBuilder::consumeConstructionContext(
const ConstructionContextLayer *Layer, Expr *E) {
assert((isa<CXXConstructExpr>(E) || isa<CallExpr>(E) ||
isa<ObjCMessageExpr>(E)) && "Expression cannot construct an object!");
if (const ConstructionContextLayer *PreviouslyStoredLayer =
ConstructionContextMap.lookup(E)) {
(void)PreviouslyStoredLayer;
// We might have visited this child when we were finding construction
// contexts within its parents.
assert(PreviouslyStoredLayer->isStrictlyMoreSpecificThan(Layer) &&
"Already within a different construction context!");
} else {
ConstructionContextMap[E] = Layer;
}
}
void CFGBuilder::findConstructionContexts(
const ConstructionContextLayer *Layer, Stmt *Child) {
if (!BuildOpts.AddRichCXXConstructors)
return;
if (!Child)
return;
auto withExtraLayer = [this, Layer](const ConstructionContextItem &Item) {
return ConstructionContextLayer::create(cfg->getBumpVectorContext(), Item,
Layer);
};
switch(Child->getStmtClass()) {
case Stmt::CXXConstructExprClass:
case Stmt::CXXTemporaryObjectExprClass: {
// Support pre-C++17 copy elision AST.
auto *CE = cast<CXXConstructExpr>(Child);
if (BuildOpts.MarkElidedCXXConstructors && CE->isElidable()) {
findConstructionContexts(withExtraLayer(CE), CE->getArg(0));
}
consumeConstructionContext(Layer, CE);
break;
}
// FIXME: This, like the main visit, doesn't support CUDAKernelCallExpr.
// FIXME: An isa<> would look much better but this whole switch is a
// workaround for an internal compiler error in MSVC 2015 (see r326021).
case Stmt::CallExprClass:
case Stmt::CXXMemberCallExprClass:
case Stmt::CXXOperatorCallExprClass:
case Stmt::UserDefinedLiteralClass:
case Stmt::ObjCMessageExprClass: {
auto *E = cast<Expr>(Child);
if (CFGCXXRecordTypedCall::isCXXRecordTypedCall(E))
consumeConstructionContext(Layer, E);
break;
}
case Stmt::ExprWithCleanupsClass: {
auto *Cleanups = cast<ExprWithCleanups>(Child);
findConstructionContexts(Layer, Cleanups->getSubExpr());
break;
}
case Stmt::CXXFunctionalCastExprClass: {
auto *Cast = cast<CXXFunctionalCastExpr>(Child);
findConstructionContexts(Layer, Cast->getSubExpr());
break;
}
case Stmt::ImplicitCastExprClass: {
auto *Cast = cast<ImplicitCastExpr>(Child);
// Should we support other implicit cast kinds?
switch (Cast->getCastKind()) {
case CK_NoOp:
case CK_ConstructorConversion:
findConstructionContexts(Layer, Cast->getSubExpr());
break;
default:
break;
}
break;
}
case Stmt::CXXBindTemporaryExprClass: {
auto *BTE = cast<CXXBindTemporaryExpr>(Child);
findConstructionContexts(withExtraLayer(BTE), BTE->getSubExpr());
break;
}
case Stmt::MaterializeTemporaryExprClass: {
// Normally we don't want to search in MaterializeTemporaryExpr because
// it indicates the beginning of a temporary object construction context,
// so it shouldn't be found in the middle. However, if it is the beginning
// of an elidable copy or move construction context, we need to include it.
if (Layer->getItem().getKind() ==
ConstructionContextItem::ElidableConstructorKind) {
auto *MTE = cast<MaterializeTemporaryExpr>(Child);
findConstructionContexts(withExtraLayer(MTE), MTE->getSubExpr());
}
break;
}
case Stmt::ConditionalOperatorClass: {
auto *CO = cast<ConditionalOperator>(Child);
if (Layer->getItem().getKind() !=
ConstructionContextItem::MaterializationKind) {
// If the object returned by the conditional operator is not going to be a
// temporary object that needs to be immediately materialized, then
// it must be C++17 with its mandatory copy elision. Do not yet promise
// to support this case.
assert(!CO->getType()->getAsCXXRecordDecl() || CO->isGLValue() ||
Context->getLangOpts().CPlusPlus17);
break;
}
findConstructionContexts(Layer, CO->getLHS());
findConstructionContexts(Layer, CO->getRHS());
break;
}
case Stmt::InitListExprClass: {
auto *ILE = cast<InitListExpr>(Child);
if (ILE->isTransparent()) {
findConstructionContexts(Layer, ILE->getInit(0));
break;
}
// TODO: Handle other cases. For now, fail to find construction contexts.
break;
}
default:
break;
}
}
void CFGBuilder::cleanupConstructionContext(Expr *E) {
assert(BuildOpts.AddRichCXXConstructors &&
"We should not be managing construction contexts!");
assert(ConstructionContextMap.count(E) &&
"Cannot exit construction context without the context!");
ConstructionContextMap.erase(E);
}
/// BuildCFG - Constructs a CFG from an AST (a Stmt*). The AST can represent an
/// arbitrary statement. Examples include a single expression or a function
/// body (compound statement). The ownership of the returned CFG is
/// transferred to the caller. If CFG construction fails, this method returns
/// NULL.
std::unique_ptr<CFG> CFGBuilder::buildCFG(const Decl *D, Stmt *Statement) {
assert(cfg.get());
if (!Statement)
return nullptr;
// Create an empty block that will serve as the exit block for the CFG. Since
// this is the first block added to the CFG, it will be implicitly registered
// as the exit block.
Succ = createBlock();
assert(Succ == &cfg->getExit());
Block = nullptr; // the EXIT block is empty. Create all other blocks lazily.
assert(!(BuildOpts.AddImplicitDtors && BuildOpts.AddLifetime) &&
"AddImplicitDtors and AddLifetime cannot be used at the same time");
if (BuildOpts.AddImplicitDtors)
if (const CXXDestructorDecl *DD = dyn_cast_or_null<CXXDestructorDecl>(D))
addImplicitDtorsForDestructor(DD);
// Visit the statements and create the CFG.
CFGBlock *B = addStmt(Statement);
if (badCFG)
return nullptr;
// For C++ constructor add initializers to CFG. Constructors of virtual bases
// are ignored unless the object is of the most derived class.
// class VBase { VBase() = default; VBase(int) {} };
// class A : virtual public VBase { A() : VBase(0) {} };
// class B : public A {};
// B b; // Constructor calls in order: VBase(), A(), B().
// // VBase(0) is ignored because A isn't the most derived class.
// This may result in the virtual base(s) being already initialized at this
// point, in which case we should jump right onto non-virtual bases and
// fields. To handle this, make a CFG branch. We only need to add one such
// branch per constructor, since the Standard states that all virtual bases
// shall be initialized before non-virtual bases and direct data members.
if (const auto *CD = dyn_cast_or_null<CXXConstructorDecl>(D)) {
CFGBlock *VBaseSucc = nullptr;
for (auto *I : llvm::reverse(CD->inits())) {
if (BuildOpts.AddVirtualBaseBranches && !VBaseSucc &&
I->isBaseInitializer() && I->isBaseVirtual()) {
// We've reached the first virtual base init while iterating in reverse
// order. Make a new block for virtual base initializers so that we
// could skip them.
VBaseSucc = Succ = B ? B : &cfg->getExit();
Block = createBlock();
}
B = addInitializer(I);
if (badCFG)
return nullptr;
}
if (VBaseSucc) {
// Make a branch block for potentially skipping virtual base initializers.
Succ = VBaseSucc;
B = createBlock();
B->setTerminator(
CFGTerminator(nullptr, CFGTerminator::VirtualBaseBranch));
addSuccessor(B, Block, true);
}
}
if (B)
Succ = B;
// Backpatch the gotos whose label -> block mappings we didn't know when we
// encountered them.
for (BackpatchBlocksTy::iterator I = BackpatchBlocks.begin(),
E = BackpatchBlocks.end(); I != E; ++I ) {
CFGBlock *B = I->block;
if (auto *G = dyn_cast<GotoStmt>(B->getTerminator())) {
LabelMapTy::iterator LI = LabelMap.find(G->getLabel());
// If there is no target for the goto, then we are looking at an
// incomplete AST. Handle this by not registering a successor.
if (LI == LabelMap.end())
continue;
JumpTarget JT = LI->second;
prependAutomaticObjLifetimeWithTerminator(B, I->scopePosition,
JT.scopePosition);
prependAutomaticObjDtorsWithTerminator(B, I->scopePosition,
JT.scopePosition);
const VarDecl *VD = prependAutomaticObjScopeEndWithTerminator(
B, I->scopePosition, JT.scopePosition);
appendScopeBegin(JT.block, VD, G);
addSuccessor(B, JT.block);
};
if (auto *G = dyn_cast<GCCAsmStmt>(B->getTerminator())) {
CFGBlock *Successor = (I+1)->block;
for (auto *L : G->labels()) {
LabelMapTy::iterator LI = LabelMap.find(L->getLabel());
// If there is no target for the goto, then we are looking at an
// incomplete AST. Handle this by not registering a successor.
if (LI == LabelMap.end())
continue;
JumpTarget JT = LI->second;
// Successor has been added, so skip it.
if (JT.block == Successor)
continue;
addSuccessor(B, JT.block);
}
I++;
}
}
// Add successors to the Indirect Goto Dispatch block (if we have one).
if (CFGBlock *B = cfg->getIndirectGotoBlock())
for (LabelSetTy::iterator I = AddressTakenLabels.begin(),
E = AddressTakenLabels.end(); I != E; ++I ) {
// Lookup the target block.
LabelMapTy::iterator LI = LabelMap.find(*I);
// If there is no target block that contains label, then we are looking
// at an incomplete AST. Handle this by not registering a successor.
if (LI == LabelMap.end()) continue;
addSuccessor(B, LI->second.block);
}
// Create an empty entry block that has no predecessors.
cfg->setEntry(createBlock());
if (BuildOpts.AddRichCXXConstructors)
assert(ConstructionContextMap.empty() &&
"Not all construction contexts were cleaned up!");
return std::move(cfg);
}
/// createBlock - Used to lazily create blocks that are connected
/// to the current (global) succcessor.
CFGBlock *CFGBuilder::createBlock(bool add_successor) {
CFGBlock *B = cfg->createBlock();
if (add_successor && Succ)
addSuccessor(B, Succ);
return B;
}
/// createNoReturnBlock - Used to create a block is a 'noreturn' point in the
/// CFG. It is *not* connected to the current (global) successor, and instead
/// directly tied to the exit block in order to be reachable.
CFGBlock *CFGBuilder::createNoReturnBlock() {
CFGBlock *B = createBlock(false);
B->setHasNoReturnElement();
addSuccessor(B, &cfg->getExit(), Succ);
return B;
}
/// addInitializer - Add C++ base or member initializer element to CFG.
CFGBlock *CFGBuilder::addInitializer(CXXCtorInitializer *I) {
if (!BuildOpts.AddInitializers)
return Block;
bool HasTemporaries = false;
// Destructors of temporaries in initialization expression should be called
// after initialization finishes.
Expr *Init = I->getInit();
if (Init) {
HasTemporaries = isa<ExprWithCleanups>(Init);
if (BuildOpts.AddTemporaryDtors && HasTemporaries) {
// Generate destructors for temporaries in initialization expression.
TempDtorContext Context;
VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(),
/*ExternallyDestructed=*/false, Context);
}
}
autoCreateBlock();
appendInitializer(Block, I);
if (Init) {
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), I),
Init);
if (HasTemporaries) {
// For expression with temporaries go directly to subexpression to omit
// generating destructors for the second time.
return Visit(cast<ExprWithCleanups>(Init)->getSubExpr());
}
if (BuildOpts.AddCXXDefaultInitExprInCtors) {
if (CXXDefaultInitExpr *Default = dyn_cast<CXXDefaultInitExpr>(Init)) {
// In general, appending the expression wrapped by a CXXDefaultInitExpr
// may cause the same Expr to appear more than once in the CFG. Doing it
// here is safe because there's only one initializer per field.
autoCreateBlock();
appendStmt(Block, Default);
if (Stmt *Child = Default->getExpr())
if (CFGBlock *R = Visit(Child))
Block = R;
return Block;
}
}
return Visit(Init);
}
return Block;
}
/// Retrieve the type of the temporary object whose lifetime was
/// extended by a local reference with the given initializer.
static QualType getReferenceInitTemporaryType(const Expr *Init,
bool *FoundMTE = nullptr) {
while (true) {
// Skip parentheses.
Init = Init->IgnoreParens();
// Skip through cleanups.
if (const ExprWithCleanups *EWC = dyn_cast<ExprWithCleanups>(Init)) {
Init = EWC->getSubExpr();
continue;
}
// Skip through the temporary-materialization expression.
if (const MaterializeTemporaryExpr *MTE
= dyn_cast<MaterializeTemporaryExpr>(Init)) {
Init = MTE->getSubExpr();
if (FoundMTE)
*FoundMTE = true;
continue;
}
// Skip sub-object accesses into rvalues.
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
const Expr *SkippedInit =
Init->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments);
if (SkippedInit != Init) {
Init = SkippedInit;
continue;
}
break;
}
return Init->getType();
}
// TODO: Support adding LoopExit element to the CFG in case where the loop is
// ended by ReturnStmt, GotoStmt or ThrowExpr.
void CFGBuilder::addLoopExit(const Stmt *LoopStmt){
if(!BuildOpts.AddLoopExit)
return;
autoCreateBlock();
appendLoopExit(Block, LoopStmt);
}
void CFGBuilder::getDeclsWithEndedScope(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S) {
if (!BuildOpts.AddScopes)
return;
if (B == E)
return;
// To go from B to E, one first goes up the scopes from B to P
// then sideways in one scope from P to P' and then down
// the scopes from P' to E.
// The lifetime of all objects between B and P end.
LocalScope::const_iterator P = B.shared_parent(E);
int Dist = B.distance(P);
if (Dist <= 0)
return;
for (LocalScope::const_iterator I = B; I != P; ++I)
if (I.pointsToFirstDeclaredVar())
DeclsWithEndedScope.insert(*I);
}
void CFGBuilder::addAutomaticObjHandling(LocalScope::const_iterator B,
LocalScope::const_iterator E,
Stmt *S) {
getDeclsWithEndedScope(B, E, S);
if (BuildOpts.AddScopes)
addScopesEnd(B, E, S);
if (BuildOpts.AddImplicitDtors)
addAutomaticObjDtors(B, E, S);
if (BuildOpts.AddLifetime)
addLifetimeEnds(B, E, S);
}
/// Add to current block automatic objects that leave the scope.
void CFGBuilder::addLifetimeEnds(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S) {
if (!BuildOpts.AddLifetime)
return;
if (B == E)
return;
// To go from B to E, one first goes up the scopes from B to P
// then sideways in one scope from P to P' and then down
// the scopes from P' to E.
// The lifetime of all objects between B and P end.
LocalScope::const_iterator P = B.shared_parent(E);
int dist = B.distance(P);
if (dist <= 0)
return;
// We need to perform the scope leaving in reverse order
SmallVector<VarDecl *, 10> DeclsTrivial;
SmallVector<VarDecl *, 10> DeclsNonTrivial;
DeclsTrivial.reserve(dist);
DeclsNonTrivial.reserve(dist);
for (LocalScope::const_iterator I = B; I != P; ++I)
if (hasTrivialDestructor(*I))
DeclsTrivial.push_back(*I);
else
DeclsNonTrivial.push_back(*I);
autoCreateBlock();
// object with trivial destructor end their lifetime last (when storage
// duration ends)
for (SmallVectorImpl<VarDecl *>::reverse_iterator I = DeclsTrivial.rbegin(),
E = DeclsTrivial.rend();
I != E; ++I)
appendLifetimeEnds(Block, *I, S);
for (SmallVectorImpl<VarDecl *>::reverse_iterator
I = DeclsNonTrivial.rbegin(),
E = DeclsNonTrivial.rend();
I != E; ++I)
appendLifetimeEnds(Block, *I, S);
}
/// Add to current block markers for ending scopes.
void CFGBuilder::addScopesEnd(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S) {
// If implicit destructors are enabled, we'll add scope ends in
// addAutomaticObjDtors.
if (BuildOpts.AddImplicitDtors)
return;
autoCreateBlock();
for (auto I = DeclsWithEndedScope.rbegin(), E = DeclsWithEndedScope.rend();
I != E; ++I)
appendScopeEnd(Block, *I, S);
return;
}
/// addAutomaticObjDtors - Add to current block automatic objects destructors
/// for objects in range of local scope positions. Use S as trigger statement
/// for destructors.
void CFGBuilder::addAutomaticObjDtors(LocalScope::const_iterator B,
LocalScope::const_iterator E, Stmt *S) {
if (!BuildOpts.AddImplicitDtors)
return;
if (B == E)
return;
// We need to append the destructors in reverse order, but any one of them
// may be a no-return destructor which changes the CFG. As a result, buffer
// this sequence up and replay them in reverse order when appending onto the
// CFGBlock(s).
SmallVector<VarDecl*, 10> Decls;
Decls.reserve(B.distance(E));
for (LocalScope::const_iterator I = B; I != E; ++I)
Decls.push_back(*I);
for (SmallVectorImpl<VarDecl*>::reverse_iterator I = Decls.rbegin(),
E = Decls.rend();
I != E; ++I) {
if (hasTrivialDestructor(*I)) {
// If AddScopes is enabled and *I is a first variable in a scope, add a
// ScopeEnd marker in a Block.
if (BuildOpts.AddScopes && DeclsWithEndedScope.count(*I)) {
autoCreateBlock();
appendScopeEnd(Block, *I, S);
}
continue;
}
// If this destructor is marked as a no-return destructor, we need to
// create a new block for the destructor which does not have as a successor
// anything built thus far: control won't flow out of this block.
QualType Ty = (*I)->getType();
if (Ty->isReferenceType()) {
Ty = getReferenceInitTemporaryType((*I)->getInit());
}
Ty = Context->getBaseElementType(Ty);
if (Ty->getAsCXXRecordDecl()->isAnyDestructorNoReturn())
Block = createNoReturnBlock();
else
autoCreateBlock();
// Add ScopeEnd just after automatic obj destructor.
if (BuildOpts.AddScopes && DeclsWithEndedScope.count(*I))
appendScopeEnd(Block, *I, S);
appendAutomaticObjDtor(Block, *I, S);
}
}
/// addImplicitDtorsForDestructor - Add implicit destructors generated for
/// base and member objects in destructor.
void CFGBuilder::addImplicitDtorsForDestructor(const CXXDestructorDecl *DD) {
assert(BuildOpts.AddImplicitDtors &&
"Can be called only when dtors should be added");
const CXXRecordDecl *RD = DD->getParent();
// At the end destroy virtual base objects.
for (const auto &VI : RD->vbases()) {
// TODO: Add a VirtualBaseBranch to see if the most derived class
// (which is different from the current class) is responsible for
// destroying them.
const CXXRecordDecl *CD = VI.getType()->getAsCXXRecordDecl();
if (!CD->hasTrivialDestructor()) {
autoCreateBlock();
appendBaseDtor(Block, &VI);
}
}
// Before virtual bases destroy direct base objects.
for (const auto &BI : RD->bases()) {
if (!BI.isVirtual()) {
const CXXRecordDecl *CD = BI.getType()->getAsCXXRecordDecl();
if (!CD->hasTrivialDestructor()) {
autoCreateBlock();
appendBaseDtor(Block, &BI);
}
}
}
// First destroy member objects.
for (auto *FI : RD->fields()) {
// Check for constant size array. Set type to array element type.
QualType QT = FI->getType();
if (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
if (AT->getSize() == 0)
continue;
QT = AT->getElementType();
}
if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl())
if (!CD->hasTrivialDestructor()) {
autoCreateBlock();
appendMemberDtor(Block, FI);
}
}
}
/// createOrReuseLocalScope - If Scope is NULL create new LocalScope. Either
/// way return valid LocalScope object.
LocalScope* CFGBuilder::createOrReuseLocalScope(LocalScope* Scope) {
if (Scope)
return Scope;
llvm::BumpPtrAllocator &alloc = cfg->getAllocator();
return new (alloc.Allocate<LocalScope>())
LocalScope(BumpVectorContext(alloc), ScopePos);
}
/// addLocalScopeForStmt - Add LocalScope to local scopes tree for statement
/// that should create implicit scope (e.g. if/else substatements).
void CFGBuilder::addLocalScopeForStmt(Stmt *S) {
if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
!BuildOpts.AddScopes)
return;
LocalScope *Scope = nullptr;
// For compound statement we will be creating explicit scope.
if (CompoundStmt *CS = dyn_cast<CompoundStmt>(S)) {
for (auto *BI : CS->body()) {
Stmt *SI = BI->stripLabelLikeStatements();
if (DeclStmt *DS = dyn_cast<DeclStmt>(SI))
Scope = addLocalScopeForDeclStmt(DS, Scope);
}
return;
}
// For any other statement scope will be implicit and as such will be
// interesting only for DeclStmt.
if (DeclStmt *DS = dyn_cast<DeclStmt>(S->stripLabelLikeStatements()))
addLocalScopeForDeclStmt(DS);
}
/// addLocalScopeForDeclStmt - Add LocalScope for declaration statement. Will
/// reuse Scope if not NULL.
LocalScope* CFGBuilder::addLocalScopeForDeclStmt(DeclStmt *DS,
LocalScope* Scope) {
if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
!BuildOpts.AddScopes)
return Scope;
for (auto *DI : DS->decls())
if (VarDecl *VD = dyn_cast<VarDecl>(DI))
Scope = addLocalScopeForVarDecl(VD, Scope);
return Scope;
}
bool CFGBuilder::hasTrivialDestructor(VarDecl *VD) {
// Check for const references bound to temporary. Set type to pointee.
QualType QT = VD->getType();
if (QT->isReferenceType()) {
// Attempt to determine whether this declaration lifetime-extends a
// temporary.
//
// FIXME: This is incorrect. Non-reference declarations can lifetime-extend
// temporaries, and a single declaration can extend multiple temporaries.
// We should look at the storage duration on each nested
// MaterializeTemporaryExpr instead.
const Expr *Init = VD->getInit();
if (!Init) {
// Probably an exception catch-by-reference variable.
// FIXME: It doesn't really mean that the object has a trivial destructor.
// Also are there other cases?
return true;
}
// Lifetime-extending a temporary?
bool FoundMTE = false;
QT = getReferenceInitTemporaryType(Init, &FoundMTE);
if (!FoundMTE)
return true;
}
// Check for constant size array. Set type to array element type.
while (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
if (AT->getSize() == 0)
return true;
QT = AT->getElementType();
}
// Check if type is a C++ class with non-trivial destructor.
if (const CXXRecordDecl *CD = QT->getAsCXXRecordDecl())
return !CD->hasDefinition() || CD->hasTrivialDestructor();
return true;
}
/// addLocalScopeForVarDecl - Add LocalScope for variable declaration. It will
/// create add scope for automatic objects and temporary objects bound to
/// const reference. Will reuse Scope if not NULL.
LocalScope* CFGBuilder::addLocalScopeForVarDecl(VarDecl *VD,
LocalScope* Scope) {
assert(!(BuildOpts.AddImplicitDtors && BuildOpts.AddLifetime) &&
"AddImplicitDtors and AddLifetime cannot be used at the same time");
if (!BuildOpts.AddImplicitDtors && !BuildOpts.AddLifetime &&
!BuildOpts.AddScopes)
return Scope;
// Check if variable is local.
switch (VD->getStorageClass()) {
case SC_None:
case SC_Auto:
case SC_Register:
break;
default: return Scope;
}
if (BuildOpts.AddImplicitDtors) {
if (!hasTrivialDestructor(VD) || BuildOpts.AddScopes) {
// Add the variable to scope
Scope = createOrReuseLocalScope(Scope);
Scope->addVar(VD);
ScopePos = Scope->begin();
}
return Scope;
}
assert(BuildOpts.AddLifetime);
// Add the variable to scope
Scope = createOrReuseLocalScope(Scope);
Scope->addVar(VD);
ScopePos = Scope->begin();
return Scope;
}
/// addLocalScopeAndDtors - For given statement add local scope for it and
/// add destructors that will cleanup the scope. Will reuse Scope if not NULL.
void CFGBuilder::addLocalScopeAndDtors(Stmt *S) {
LocalScope::const_iterator scopeBeginPos = ScopePos;
addLocalScopeForStmt(S);
addAutomaticObjHandling(ScopePos, scopeBeginPos, S);
}
/// prependAutomaticObjDtorsWithTerminator - Prepend destructor CFGElements for
/// variables with automatic storage duration to CFGBlock's elements vector.
/// Elements will be prepended to physical beginning of the vector which
/// happens to be logical end. Use blocks terminator as statement that specifies
/// destructors call site.
/// FIXME: This mechanism for adding automatic destructors doesn't handle
/// no-return destructors properly.
void CFGBuilder::prependAutomaticObjDtorsWithTerminator(CFGBlock *Blk,
LocalScope::const_iterator B, LocalScope::const_iterator E) {
if (!BuildOpts.AddImplicitDtors)
return;
BumpVectorContext &C = cfg->getBumpVectorContext();
CFGBlock::iterator InsertPos
= Blk->beginAutomaticObjDtorsInsert(Blk->end(), B.distance(E), C);
for (LocalScope::const_iterator I = B; I != E; ++I)
InsertPos = Blk->insertAutomaticObjDtor(InsertPos, *I,
Blk->getTerminatorStmt());
}
/// prependAutomaticObjLifetimeWithTerminator - Prepend lifetime CFGElements for
/// variables with automatic storage duration to CFGBlock's elements vector.
/// Elements will be prepended to physical beginning of the vector which
/// happens to be logical end. Use blocks terminator as statement that specifies
/// where lifetime ends.
void CFGBuilder::prependAutomaticObjLifetimeWithTerminator(
CFGBlock *Blk, LocalScope::const_iterator B, LocalScope::const_iterator E) {
if (!BuildOpts.AddLifetime)
return;
BumpVectorContext &C = cfg->getBumpVectorContext();
CFGBlock::iterator InsertPos =
Blk->beginLifetimeEndsInsert(Blk->end(), B.distance(E), C);
for (LocalScope::const_iterator I = B; I != E; ++I) {
InsertPos =
Blk->insertLifetimeEnds(InsertPos, *I, Blk->getTerminatorStmt());
}
}
/// prependAutomaticObjScopeEndWithTerminator - Prepend scope end CFGElements for
/// variables with automatic storage duration to CFGBlock's elements vector.
/// Elements will be prepended to physical beginning of the vector which
/// happens to be logical end. Use blocks terminator as statement that specifies
/// where scope ends.
const VarDecl *
CFGBuilder::prependAutomaticObjScopeEndWithTerminator(
CFGBlock *Blk, LocalScope::const_iterator B, LocalScope::const_iterator E) {
if (!BuildOpts.AddScopes)
return nullptr;
BumpVectorContext &C = cfg->getBumpVectorContext();
CFGBlock::iterator InsertPos =
Blk->beginScopeEndInsert(Blk->end(), 1, C);
LocalScope::const_iterator PlaceToInsert = B;
for (LocalScope::const_iterator I = B; I != E; ++I)
PlaceToInsert = I;
Blk->insertScopeEnd(InsertPos, *PlaceToInsert, Blk->getTerminatorStmt());
return *PlaceToInsert;
}
/// Visit - Walk the subtree of a statement and add extra
/// blocks for ternary operators, &&, and ||. We also process "," and
/// DeclStmts (which may contain nested control-flow).
CFGBlock *CFGBuilder::Visit(Stmt * S, AddStmtChoice asc,
bool ExternallyDestructed) {
if (!S) {
badCFG = true;
return nullptr;
}
if (Expr *E = dyn_cast<Expr>(S))
S = E->IgnoreParens();
if (Context->getLangOpts().OpenMP)
if (auto *D = dyn_cast<OMPExecutableDirective>(S))
return VisitOMPExecutableDirective(D, asc);
switch (S->getStmtClass()) {
default:
return VisitStmt(S, asc);
case Stmt::AddrLabelExprClass:
return VisitAddrLabelExpr(cast<AddrLabelExpr>(S), asc);
case Stmt::BinaryConditionalOperatorClass:
return VisitConditionalOperator(cast<BinaryConditionalOperator>(S), asc);
case Stmt::BinaryOperatorClass:
return VisitBinaryOperator(cast<BinaryOperator>(S), asc);
case Stmt::BlockExprClass:
return VisitBlockExpr(cast<BlockExpr>(S), asc);
case Stmt::BreakStmtClass:
return VisitBreakStmt(cast<BreakStmt>(S));
case Stmt::CallExprClass:
case Stmt::CXXOperatorCallExprClass:
case Stmt::CXXMemberCallExprClass:
case Stmt::UserDefinedLiteralClass:
return VisitCallExpr(cast<CallExpr>(S), asc);
case Stmt::CaseStmtClass:
return VisitCaseStmt(cast<CaseStmt>(S));
case Stmt::ChooseExprClass:
return VisitChooseExpr(cast<ChooseExpr>(S), asc);
case Stmt::CompoundStmtClass:
return VisitCompoundStmt(cast<CompoundStmt>(S), ExternallyDestructed);
case Stmt::ConditionalOperatorClass:
return VisitConditionalOperator(cast<ConditionalOperator>(S), asc);
case Stmt::ContinueStmtClass:
return VisitContinueStmt(cast<ContinueStmt>(S));
case Stmt::CXXCatchStmtClass:
return VisitCXXCatchStmt(cast<CXXCatchStmt>(S));
case Stmt::ExprWithCleanupsClass:
return VisitExprWithCleanups(cast<ExprWithCleanups>(S),
asc, ExternallyDestructed);
case Stmt::CXXDefaultArgExprClass:
case Stmt::CXXDefaultInitExprClass:
// FIXME: The expression inside a CXXDefaultArgExpr is owned by the
// called function's declaration, not by the caller. If we simply add
// this expression to the CFG, we could end up with the same Expr
// appearing multiple times.
// PR13385 / <rdar://problem/12156507>
//
// It's likewise possible for multiple CXXDefaultInitExprs for the same
// expression to be used in the same function (through aggregate
// initialization).
return VisitStmt(S, asc);
case Stmt::CXXBindTemporaryExprClass:
return VisitCXXBindTemporaryExpr(cast<CXXBindTemporaryExpr>(S), asc);
case Stmt::CXXConstructExprClass:
return VisitCXXConstructExpr(cast<CXXConstructExpr>(S), asc);
case Stmt::CXXNewExprClass:
return VisitCXXNewExpr(cast<CXXNewExpr>(S), asc);
case Stmt::CXXDeleteExprClass:
return VisitCXXDeleteExpr(cast<CXXDeleteExpr>(S), asc);
case Stmt::CXXFunctionalCastExprClass:
return VisitCXXFunctionalCastExpr(cast<CXXFunctionalCastExpr>(S), asc);
case Stmt::CXXTemporaryObjectExprClass:
return VisitCXXTemporaryObjectExpr(cast<CXXTemporaryObjectExpr>(S), asc);
case Stmt::CXXThrowExprClass:
return VisitCXXThrowExpr(cast<CXXThrowExpr>(S));
case Stmt::CXXTryStmtClass:
return VisitCXXTryStmt(cast<CXXTryStmt>(S));
case Stmt::CXXForRangeStmtClass:
return VisitCXXForRangeStmt(cast<CXXForRangeStmt>(S));
case Stmt::DeclStmtClass:
return VisitDeclStmt(cast<DeclStmt>(S));
case Stmt::DefaultStmtClass:
return VisitDefaultStmt(cast<DefaultStmt>(S));
case Stmt::DoStmtClass:
return VisitDoStmt(cast<DoStmt>(S));
case Stmt::ForStmtClass:
return VisitForStmt(cast<ForStmt>(S));
case Stmt::GotoStmtClass:
return VisitGotoStmt(cast<GotoStmt>(S));
case Stmt::GCCAsmStmtClass:
return VisitGCCAsmStmt(cast<GCCAsmStmt>(S), asc);
case Stmt::IfStmtClass:
return VisitIfStmt(cast<IfStmt>(S));
case Stmt::ImplicitCastExprClass:
return VisitImplicitCastExpr(cast<ImplicitCastExpr>(S), asc);
case Stmt::ConstantExprClass:
return VisitConstantExpr(cast<ConstantExpr>(S), asc);
case Stmt::IndirectGotoStmtClass:
return VisitIndirectGotoStmt(cast<IndirectGotoStmt>(S));
case Stmt::LabelStmtClass:
return VisitLabelStmt(cast<LabelStmt>(S));
case Stmt::LambdaExprClass:
return VisitLambdaExpr(cast<LambdaExpr>(S), asc);
case Stmt::MaterializeTemporaryExprClass:
return VisitMaterializeTemporaryExpr(cast<MaterializeTemporaryExpr>(S),
asc);
case Stmt::MemberExprClass:
return VisitMemberExpr(cast<MemberExpr>(S), asc);
case Stmt::NullStmtClass:
return Block;
case Stmt::ObjCAtCatchStmtClass:
return VisitObjCAtCatchStmt(cast<ObjCAtCatchStmt>(S));
case Stmt::ObjCAutoreleasePoolStmtClass:
return VisitObjCAutoreleasePoolStmt(cast<ObjCAutoreleasePoolStmt>(S));
case Stmt::ObjCAtSynchronizedStmtClass:
return VisitObjCAtSynchronizedStmt(cast<ObjCAtSynchronizedStmt>(S));
case Stmt::ObjCAtThrowStmtClass:
return VisitObjCAtThrowStmt(cast<ObjCAtThrowStmt>(S));
case Stmt::ObjCAtTryStmtClass:
return VisitObjCAtTryStmt(cast<ObjCAtTryStmt>(S));
case Stmt::ObjCForCollectionStmtClass:
return VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S));
case Stmt::ObjCMessageExprClass:
return VisitObjCMessageExpr(cast<ObjCMessageExpr>(S), asc);
case Stmt::OpaqueValueExprClass:
return Block;
case Stmt::PseudoObjectExprClass:
return VisitPseudoObjectExpr(cast<PseudoObjectExpr>(S));
case Stmt::ReturnStmtClass:
case Stmt::CoreturnStmtClass:
return VisitReturnStmt(S);
case Stmt::SEHExceptStmtClass:
return VisitSEHExceptStmt(cast<SEHExceptStmt>(S));
case Stmt::SEHFinallyStmtClass:
return VisitSEHFinallyStmt(cast<SEHFinallyStmt>(S));
case Stmt::SEHLeaveStmtClass:
return VisitSEHLeaveStmt(cast<SEHLeaveStmt>(S));
case Stmt::SEHTryStmtClass:
return VisitSEHTryStmt(cast<SEHTryStmt>(S));
case Stmt::UnaryExprOrTypeTraitExprClass:
return VisitUnaryExprOrTypeTraitExpr(cast<UnaryExprOrTypeTraitExpr>(S),
asc);
case Stmt::StmtExprClass:
return VisitStmtExpr(cast<StmtExpr>(S), asc);
case Stmt::SwitchStmtClass:
return VisitSwitchStmt(cast<SwitchStmt>(S));
case Stmt::UnaryOperatorClass:
return VisitUnaryOperator(cast<UnaryOperator>(S), asc);
case Stmt::WhileStmtClass:
return VisitWhileStmt(cast<WhileStmt>(S));
}
}
CFGBlock *CFGBuilder::VisitStmt(Stmt *S, AddStmtChoice asc) {
if (asc.alwaysAdd(*this, S)) {
autoCreateBlock();
appendStmt(Block, S);
}
return VisitChildren(S);
}
/// VisitChildren - Visit the children of a Stmt.
CFGBlock *CFGBuilder::VisitChildren(Stmt *S) {
CFGBlock *B = Block;
// Visit the children in their reverse order so that they appear in
// left-to-right (natural) order in the CFG.
reverse_children RChildren(S);
for (reverse_children::iterator I = RChildren.begin(), E = RChildren.end();
I != E; ++I) {
if (Stmt *Child = *I)
if (CFGBlock *R = Visit(Child))
B = R;
}
return B;
}
CFGBlock *CFGBuilder::VisitAddrLabelExpr(AddrLabelExpr *A,
AddStmtChoice asc) {
AddressTakenLabels.insert(A->getLabel());
if (asc.alwaysAdd(*this, A)) {
autoCreateBlock();
appendStmt(Block, A);
}
return Block;
}
CFGBlock *CFGBuilder::VisitUnaryOperator(UnaryOperator *U,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, U)) {
autoCreateBlock();
appendStmt(Block, U);
}
if (U->getOpcode() == UO_LNot)
tryEvaluateBool(U->getSubExpr()->IgnoreParens());
return Visit(U->getSubExpr(), AddStmtChoice());
}
CFGBlock *CFGBuilder::VisitLogicalOperator(BinaryOperator *B) {
CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
appendStmt(ConfluenceBlock, B);
if (badCFG)
return nullptr;
return VisitLogicalOperator(B, nullptr, ConfluenceBlock,
ConfluenceBlock).first;
}
std::pair<CFGBlock*, CFGBlock*>
CFGBuilder::VisitLogicalOperator(BinaryOperator *B,
Stmt *Term,
CFGBlock *TrueBlock,
CFGBlock *FalseBlock) {
// Introspect the RHS. If it is a nested logical operation, we recursively
// build the CFG using this function. Otherwise, resort to default
// CFG construction behavior.
Expr *RHS = B->getRHS()->IgnoreParens();
CFGBlock *RHSBlock, *ExitBlock;
do {
if (BinaryOperator *B_RHS = dyn_cast<BinaryOperator>(RHS))
if (B_RHS->isLogicalOp()) {
std::tie(RHSBlock, ExitBlock) =
VisitLogicalOperator(B_RHS, Term, TrueBlock, FalseBlock);
break;
}
// The RHS is not a nested logical operation. Don't push the terminator
// down further, but instead visit RHS and construct the respective
// pieces of the CFG, and link up the RHSBlock with the terminator
// we have been provided.
ExitBlock = RHSBlock = createBlock(false);
// Even though KnownVal is only used in the else branch of the next
// conditional, tryEvaluateBool performs additional checking on the
// Expr, so it should be called unconditionally.
TryResult KnownVal = tryEvaluateBool(RHS);
if (!KnownVal.isKnown())
KnownVal = tryEvaluateBool(B);
if (!Term) {
assert(TrueBlock == FalseBlock);
addSuccessor(RHSBlock, TrueBlock);
}
else {
RHSBlock->setTerminator(Term);
addSuccessor(RHSBlock, TrueBlock, !KnownVal.isFalse());
addSuccessor(RHSBlock, FalseBlock, !KnownVal.isTrue());
}
Block = RHSBlock;
RHSBlock = addStmt(RHS);
}
while (false);
if (badCFG)
return std::make_pair(nullptr, nullptr);
// Generate the blocks for evaluating the LHS.
Expr *LHS = B->getLHS()->IgnoreParens();
if (BinaryOperator *B_LHS = dyn_cast<BinaryOperator>(LHS))
if (B_LHS->isLogicalOp()) {
if (B->getOpcode() == BO_LOr)
FalseBlock = RHSBlock;
else
TrueBlock = RHSBlock;
// For the LHS, treat 'B' as the terminator that we want to sink
// into the nested branch. The RHS always gets the top-most
// terminator.
return VisitLogicalOperator(B_LHS, B, TrueBlock, FalseBlock);
}
// Create the block evaluating the LHS.
// This contains the '&&' or '||' as the terminator.
CFGBlock *LHSBlock = createBlock(false);
LHSBlock->setTerminator(B);
Block = LHSBlock;
CFGBlock *EntryLHSBlock = addStmt(LHS);
if (badCFG)
return std::make_pair(nullptr, nullptr);
// See if this is a known constant.
TryResult KnownVal = tryEvaluateBool(LHS);
// Now link the LHSBlock with RHSBlock.
if (B->getOpcode() == BO_LOr) {
addSuccessor(LHSBlock, TrueBlock, !KnownVal.isFalse());
addSuccessor(LHSBlock, RHSBlock, !KnownVal.isTrue());
} else {
assert(B->getOpcode() == BO_LAnd);
addSuccessor(LHSBlock, RHSBlock, !KnownVal.isFalse());
addSuccessor(LHSBlock, FalseBlock, !KnownVal.isTrue());
}
return std::make_pair(EntryLHSBlock, ExitBlock);
}
CFGBlock *CFGBuilder::VisitBinaryOperator(BinaryOperator *B,
AddStmtChoice asc) {
// && or ||
if (B->isLogicalOp())
return VisitLogicalOperator(B);
if (B->getOpcode() == BO_Comma) { // ,
autoCreateBlock();
appendStmt(Block, B);
addStmt(B->getRHS());
return addStmt(B->getLHS());
}
if (B->isAssignmentOp()) {
if (asc.alwaysAdd(*this, B)) {
autoCreateBlock();
appendStmt(Block, B);
}
Visit(B->getLHS());
return Visit(B->getRHS());
}
if (asc.alwaysAdd(*this, B)) {
autoCreateBlock();
appendStmt(Block, B);
}
if (B->isEqualityOp() || B->isRelationalOp())
tryEvaluateBool(B);
CFGBlock *RBlock = Visit(B->getRHS());
CFGBlock *LBlock = Visit(B->getLHS());
// If visiting RHS causes us to finish 'Block', e.g. the RHS is a StmtExpr
// containing a DoStmt, and the LHS doesn't create a new block, then we should
// return RBlock. Otherwise we'll incorrectly return NULL.
return (LBlock ? LBlock : RBlock);
}
CFGBlock *CFGBuilder::VisitNoRecurse(Expr *E, AddStmtChoice asc) {
if (asc.alwaysAdd(*this, E)) {
autoCreateBlock();
appendStmt(Block, E);
}
return Block;
}
CFGBlock *CFGBuilder::VisitBreakStmt(BreakStmt *B) {
// "break" is a control-flow statement. Thus we stop processing the current
// block.
if (badCFG)
return nullptr;
// Now create a new block that ends with the break statement.
Block = createBlock(false);
Block->setTerminator(B);
// If there is no target for the break, then we are looking at an incomplete
// AST. This means that the CFG cannot be constructed.
if (BreakJumpTarget.block) {
addAutomaticObjHandling(ScopePos, BreakJumpTarget.scopePosition, B);
addSuccessor(Block, BreakJumpTarget.block);
} else
badCFG = true;
return Block;
}
static bool CanThrow(Expr *E, ASTContext &Ctx) {
QualType Ty = E->getType();
if (Ty->isFunctionPointerType() || Ty->isBlockPointerType())
Ty = Ty->getPointeeType();
const FunctionType *FT = Ty->getAs<FunctionType>();
if (FT) {
if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
if (!isUnresolvedExceptionSpec(Proto->getExceptionSpecType()) &&
Proto->isNothrow())
return false;
}
return true;
}
CFGBlock *CFGBuilder::VisitCallExpr(CallExpr *C, AddStmtChoice asc) {
// Compute the callee type.
QualType calleeType = C->getCallee()->getType();
if (calleeType == Context->BoundMemberTy) {
QualType boundType = Expr::findBoundMemberType(C->getCallee());
// We should only get a null bound type if processing a dependent
// CFG. Recover by assuming nothing.
if (!boundType.isNull()) calleeType = boundType;
}
// If this is a call to a no-return function, this stops the block here.
bool NoReturn = getFunctionExtInfo(*calleeType).getNoReturn();
bool AddEHEdge = false;
// Languages without exceptions are assumed to not throw.
if (Context->getLangOpts().Exceptions) {
if (BuildOpts.AddEHEdges)
AddEHEdge = true;
}
// If this is a call to a builtin function, it might not actually evaluate
// its arguments. Don't add them to the CFG if this is the case.
bool OmitArguments = false;
if (FunctionDecl *FD = C->getDirectCallee()) {
// TODO: Support construction contexts for variadic function arguments.
// These are a bit problematic and not very useful because passing
// C++ objects as C-style variadic arguments doesn't work in general
// (see [expr.call]).
if (!FD->isVariadic())
findConstructionContextsForArguments(C);
if (FD->isNoReturn() || C->isBuiltinAssumeFalse(*Context))
NoReturn = true;
if (FD->hasAttr<NoThrowAttr>())
AddEHEdge = false;
if (FD->getBuiltinID() == Builtin::BI__builtin_object_size ||
FD->getBuiltinID() == Builtin::BI__builtin_dynamic_object_size)
OmitArguments = true;
}
if (!CanThrow(C->getCallee(), *Context))
AddEHEdge = false;
if (OmitArguments) {
assert(!NoReturn && "noreturn calls with unevaluated args not implemented");
assert(!AddEHEdge && "EH calls with unevaluated args not implemented");
autoCreateBlock();
appendStmt(Block, C);
return Visit(C->getCallee());
}
if (!NoReturn && !AddEHEdge) {
autoCreateBlock();
appendCall(Block, C);
return VisitChildren(C);
}
if (Block) {
Succ = Block;
if (badCFG)
return nullptr;
}
if (NoReturn)
Block = createNoReturnBlock();
else
Block = createBlock();
appendCall(Block, C);
if (AddEHEdge) {
// Add exceptional edges.
if (TryTerminatedBlock)
addSuccessor(Block, TryTerminatedBlock);
else
addSuccessor(Block, &cfg->getExit());
}
return VisitChildren(C);
}
CFGBlock *CFGBuilder::VisitChooseExpr(ChooseExpr *C,
AddStmtChoice asc) {
CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
appendStmt(ConfluenceBlock, C);
if (badCFG)
return nullptr;
AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true);
Succ = ConfluenceBlock;
Block = nullptr;
CFGBlock *LHSBlock = Visit(C->getLHS(), alwaysAdd);
if (badCFG)
return nullptr;
Succ = ConfluenceBlock;
Block = nullptr;
CFGBlock *RHSBlock = Visit(C->getRHS(), alwaysAdd);
if (badCFG)
return nullptr;
Block = createBlock(false);
// See if this is a known constant.
const TryResult& KnownVal = tryEvaluateBool(C->getCond());
addSuccessor(Block, KnownVal.isFalse() ? nullptr : LHSBlock);
addSuccessor(Block, KnownVal.isTrue() ? nullptr : RHSBlock);
Block->setTerminator(C);
return addStmt(C->getCond());
}
CFGBlock *CFGBuilder::VisitCompoundStmt(CompoundStmt *C, bool ExternallyDestructed) {
LocalScope::const_iterator scopeBeginPos = ScopePos;
addLocalScopeForStmt(C);
if (!C->body_empty() && !isa<ReturnStmt>(*C->body_rbegin())) {
// If the body ends with a ReturnStmt, the dtors will be added in
// VisitReturnStmt.
addAutomaticObjHandling(ScopePos, scopeBeginPos, C);
}
CFGBlock *LastBlock = Block;
for (CompoundStmt::reverse_body_iterator I=C->body_rbegin(), E=C->body_rend();
I != E; ++I ) {
// If we hit a segment of code just containing ';' (NullStmts), we can
// get a null block back. In such cases, just use the LastBlock
CFGBlock *newBlock = Visit(*I, AddStmtChoice::AlwaysAdd,
ExternallyDestructed);
if (newBlock)
LastBlock = newBlock;
if (badCFG)
return nullptr;
ExternallyDestructed = false;
}
return LastBlock;
}
CFGBlock *CFGBuilder::VisitConditionalOperator(AbstractConditionalOperator *C,
AddStmtChoice asc) {
const BinaryConditionalOperator *BCO = dyn_cast<BinaryConditionalOperator>(C);
const OpaqueValueExpr *opaqueValue = (BCO ? BCO->getOpaqueValue() : nullptr);
// Create the confluence block that will "merge" the results of the ternary
// expression.
CFGBlock *ConfluenceBlock = Block ? Block : createBlock();
appendStmt(ConfluenceBlock, C);
if (badCFG)
return nullptr;
AddStmtChoice alwaysAdd = asc.withAlwaysAdd(true);
// Create a block for the LHS expression if there is an LHS expression. A
// GCC extension allows LHS to be NULL, causing the condition to be the
// value that is returned instead.
// e.g: x ?: y is shorthand for: x ? x : y;
Succ = ConfluenceBlock;
Block = nullptr;
CFGBlock *LHSBlock = nullptr;
const Expr *trueExpr = C->getTrueExpr();
if (trueExpr != opaqueValue) {
LHSBlock = Visit(C->getTrueExpr(), alwaysAdd);
if (badCFG)
return nullptr;
Block = nullptr;
}
else
LHSBlock = ConfluenceBlock;
// Create the block for the RHS expression.
Succ = ConfluenceBlock;
CFGBlock *RHSBlock = Visit(C->getFalseExpr(), alwaysAdd);
if (badCFG)
return nullptr;
// If the condition is a logical '&&' or '||', build a more accurate CFG.
if (BinaryOperator *Cond =
dyn_cast<BinaryOperator>(C->getCond()->IgnoreParens()))
if (Cond->isLogicalOp())
return VisitLogicalOperator(Cond, C, LHSBlock, RHSBlock).first;
// Create the block that will contain the condition.
Block = createBlock(false);
// See if this is a known constant.
const TryResult& KnownVal = tryEvaluateBool(C->getCond());
addSuccessor(Block, LHSBlock, !KnownVal.isFalse());
addSuccessor(Block, RHSBlock, !KnownVal.isTrue());
Block->setTerminator(C);
Expr *condExpr = C->getCond();
if (opaqueValue) {
// Run the condition expression if it's not trivially expressed in
// terms of the opaque value (or if there is no opaque value).
if (condExpr != opaqueValue)
addStmt(condExpr);
// Before that, run the common subexpression if there was one.
// At least one of this or the above will be run.
return addStmt(BCO->getCommon());
}
return addStmt(condExpr);
}
CFGBlock *CFGBuilder::VisitDeclStmt(DeclStmt *DS) {
// Check if the Decl is for an __label__. If so, elide it from the
// CFG entirely.
if (isa<LabelDecl>(*DS->decl_begin()))
return Block;
// This case also handles static_asserts.
if (DS->isSingleDecl())
return VisitDeclSubExpr(DS);
CFGBlock *B = nullptr;
// Build an individual DeclStmt for each decl.
for (DeclStmt::reverse_decl_iterator I = DS->decl_rbegin(),
E = DS->decl_rend();
I != E; ++I) {
// Allocate the DeclStmt using the BumpPtrAllocator. It will get
// automatically freed with the CFG.
DeclGroupRef DG(*I);
Decl *D = *I;
DeclStmt *DSNew = new (Context) DeclStmt(DG, D->getLocation(), GetEndLoc(D));
cfg->addSyntheticDeclStmt(DSNew, DS);
// Append the fake DeclStmt to block.
B = VisitDeclSubExpr(DSNew);
}
return B;
}
/// VisitDeclSubExpr - Utility method to add block-level expressions for
/// DeclStmts and initializers in them.
CFGBlock *CFGBuilder::VisitDeclSubExpr(DeclStmt *DS) {
assert(DS->isSingleDecl() && "Can handle single declarations only.");
VarDecl *VD = dyn_cast<VarDecl>(DS->getSingleDecl());
if (!VD) {
// Of everything that can be declared in a DeclStmt, only VarDecls impact
// runtime semantics.
return Block;
}
bool HasTemporaries = false;
// Guard static initializers under a branch.
CFGBlock *blockAfterStaticInit = nullptr;
if (BuildOpts.AddStaticInitBranches && VD->isStaticLocal()) {
// For static variables, we need to create a branch to track
// whether or not they are initialized.
if (Block) {
Succ = Block;
Block = nullptr;
if (badCFG)
return nullptr;
}
blockAfterStaticInit = Succ;
}
// Destructors of temporaries in initialization expression should be called
// after initialization finishes.
Expr *Init = VD->getInit();
if (Init) {
HasTemporaries = isa<ExprWithCleanups>(Init);
if (BuildOpts.AddTemporaryDtors && HasTemporaries) {
// Generate destructors for temporaries in initialization expression.
TempDtorContext Context;
VisitForTemporaryDtors(cast<ExprWithCleanups>(Init)->getSubExpr(),
/*ExternallyDestructed=*/true, Context);
}
}
autoCreateBlock();
appendStmt(Block, DS);
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), DS),
Init);
// Keep track of the last non-null block, as 'Block' can be nulled out
// if the initializer expression is something like a 'while' in a
// statement-expression.
CFGBlock *LastBlock = Block;
if (Init) {
if (HasTemporaries) {
// For expression with temporaries go directly to subexpression to omit
// generating destructors for the second time.
ExprWithCleanups *EC = cast<ExprWithCleanups>(Init);
if (CFGBlock *newBlock = Visit(EC->getSubExpr()))
LastBlock = newBlock;
}
else {
if (CFGBlock *newBlock = Visit(Init))
LastBlock = newBlock;
}
}
// If the type of VD is a VLA, then we must process its size expressions.
for (const VariableArrayType* VA = FindVA(VD->getType().getTypePtr());
VA != nullptr; VA = FindVA(VA->getElementType().getTypePtr())) {
if (CFGBlock *newBlock = addStmt(VA->getSizeExpr()))
LastBlock = newBlock;
}
maybeAddScopeBeginForVarDecl(Block, VD, DS);
// Remove variable from local scope.
if (ScopePos && VD == *ScopePos)
++ScopePos;
CFGBlock *B = LastBlock;
if (blockAfterStaticInit) {
Succ = B;
Block = createBlock(false);
Block->setTerminator(DS);
addSuccessor(Block, blockAfterStaticInit);
addSuccessor(Block, B);
B = Block;
}
return B;
}
CFGBlock *CFGBuilder::VisitIfStmt(IfStmt *I) {
// We may see an if statement in the middle of a basic block, or it may be the
// first statement we are processing. In either case, we create a new basic
// block. First, we create the blocks for the then...else statements, and
// then we create the block containing the if statement. If we were in the
// middle of a block, we stop processing that block. That block is then the
// implicit successor for the "then" and "else" clauses.
// Save local scope position because in case of condition variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scope for C++17 if init-stmt if one exists.
if (Stmt *Init = I->getInit())
addLocalScopeForStmt(Init);
// Create local scope for possible condition variable.
// Store scope position. Add implicit destructor.
if (VarDecl *VD = I->getConditionVariable())
addLocalScopeForVarDecl(VD);
addAutomaticObjHandling(ScopePos, save_scope_pos.get(), I);
// The block we were processing is now finished. Make it the successor
// block.
if (Block) {
Succ = Block;
if (badCFG)
return nullptr;
}
// Process the false branch.
CFGBlock *ElseBlock = Succ;
if (Stmt *Else = I->getElse()) {
SaveAndRestore<CFGBlock*> sv(Succ);
// NULL out Block so that the recursive call to Visit will
// create a new basic block.
Block = nullptr;
// If branch is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(Else))
addLocalScopeAndDtors(Else);
ElseBlock = addStmt(Else);
if (!ElseBlock) // Can occur when the Else body has all NullStmts.
ElseBlock = sv.get();
else if (Block) {
if (badCFG)
return nullptr;
}
}
// Process the true branch.
CFGBlock *ThenBlock;
{
Stmt *Then = I->getThen();
assert(Then);
SaveAndRestore<CFGBlock*> sv(Succ);
Block = nullptr;
// If branch is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(Then))
addLocalScopeAndDtors(Then);
ThenBlock = addStmt(Then);
if (!ThenBlock) {
// We can reach here if the "then" body has all NullStmts.
// Create an empty block so we can distinguish between true and false
// branches in path-sensitive analyses.
ThenBlock = createBlock(false);
addSuccessor(ThenBlock, sv.get());
} else if (Block) {
if (badCFG)
return nullptr;
}
}
// Specially handle "if (expr1 || ...)" and "if (expr1 && ...)" by
// having these handle the actual control-flow jump. Note that
// if we introduce a condition variable, e.g. "if (int x = exp1 || exp2)"
// we resort to the old control-flow behavior. This special handling
// removes infeasible paths from the control-flow graph by having the
// control-flow transfer of '&&' or '||' go directly into the then/else
// blocks directly.
BinaryOperator *Cond =
I->getConditionVariable()
? nullptr
: dyn_cast<BinaryOperator>(I->getCond()->IgnoreParens());
CFGBlock *LastBlock;
if (Cond && Cond->isLogicalOp())
LastBlock = VisitLogicalOperator(Cond, I, ThenBlock, ElseBlock).first;
else {
// Now create a new block containing the if statement.
Block = createBlock(false);
// Set the terminator of the new block to the If statement.
Block->setTerminator(I);
// See if this is a known constant.
const TryResult &KnownVal = tryEvaluateBool(I->getCond());
// Add the successors. If we know that specific branches are
// unreachable, inform addSuccessor() of that knowledge.
addSuccessor(Block, ThenBlock, /* IsReachable = */ !KnownVal.isFalse());
addSuccessor(Block, ElseBlock, /* IsReachable = */ !KnownVal.isTrue());
// Add the condition as the last statement in the new block. This may
// create new blocks as the condition may contain control-flow. Any newly
// created blocks will be pointed to be "Block".
LastBlock = addStmt(I->getCond());
// If the IfStmt contains a condition variable, add it and its
// initializer to the CFG.
if (const DeclStmt* DS = I->getConditionVariableDeclStmt()) {
autoCreateBlock();
LastBlock = addStmt(const_cast<DeclStmt *>(DS));
}
}
// Finally, if the IfStmt contains a C++17 init-stmt, add it to the CFG.
if (Stmt *Init = I->getInit()) {
autoCreateBlock();
LastBlock = addStmt(Init);
}
return LastBlock;
}
CFGBlock *CFGBuilder::VisitReturnStmt(Stmt *S) {
// If we were in the middle of a block we stop processing that block.
//
// NOTE: If a "return" or "co_return" appears in the middle of a block, this
// means that the code afterwards is DEAD (unreachable). We still keep
// a basic block for that code; a simple "mark-and-sweep" from the entry
// block will be able to report such dead blocks.
assert(isa<ReturnStmt>(S) || isa<CoreturnStmt>(S));
// Create the new block.
Block = createBlock(false);
addAutomaticObjHandling(ScopePos, LocalScope::const_iterator(), S);
if (auto *R = dyn_cast<ReturnStmt>(S))
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), R),
R->getRetValue());
// If the one of the destructors does not return, we already have the Exit
// block as a successor.
if (!Block->hasNoReturnElement())
addSuccessor(Block, &cfg->getExit());
// Add the return statement to the block.
appendStmt(Block, S);
// Visit children
if (ReturnStmt *RS = dyn_cast<ReturnStmt>(S)) {
if (Expr *O = RS->getRetValue())
return Visit(O, AddStmtChoice::AlwaysAdd, /*ExternallyDestructed=*/true);
return Block;
} else { // co_return
return VisitChildren(S);
}
}
CFGBlock *CFGBuilder::VisitSEHExceptStmt(SEHExceptStmt *ES) {
// SEHExceptStmt are treated like labels, so they are the first statement in a
// block.
// Save local scope position because in case of exception variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
addStmt(ES->getBlock());
CFGBlock *SEHExceptBlock = Block;
if (!SEHExceptBlock)
SEHExceptBlock = createBlock();
appendStmt(SEHExceptBlock, ES);
// Also add the SEHExceptBlock as a label, like with regular labels.
SEHExceptBlock->setLabel(ES);
// Bail out if the CFG is bad.
if (badCFG)
return nullptr;
// We set Block to NULL to allow lazy creation of a new block (if necessary).
Block = nullptr;
return SEHExceptBlock;
}
CFGBlock *CFGBuilder::VisitSEHFinallyStmt(SEHFinallyStmt *FS) {
return VisitCompoundStmt(FS->getBlock(), /*ExternallyDestructed=*/false);
}
CFGBlock *CFGBuilder::VisitSEHLeaveStmt(SEHLeaveStmt *LS) {
// "__leave" is a control-flow statement. Thus we stop processing the current
// block.
if (badCFG)
return nullptr;
// Now create a new block that ends with the __leave statement.
Block = createBlock(false);
Block->setTerminator(LS);
// If there is no target for the __leave, then we are looking at an incomplete
// AST. This means that the CFG cannot be constructed.
if (SEHLeaveJumpTarget.block) {
addAutomaticObjHandling(ScopePos, SEHLeaveJumpTarget.scopePosition, LS);
addSuccessor(Block, SEHLeaveJumpTarget.block);
} else
badCFG = true;
return Block;
}
CFGBlock *CFGBuilder::VisitSEHTryStmt(SEHTryStmt *Terminator) {
// "__try"/"__except"/"__finally" is a control-flow statement. Thus we stop
// processing the current block.
CFGBlock *SEHTrySuccessor = nullptr;
if (Block) {
if (badCFG)
return nullptr;
SEHTrySuccessor = Block;
} else SEHTrySuccessor = Succ;
// FIXME: Implement __finally support.
if (Terminator->getFinallyHandler())
return NYS();
CFGBlock *PrevSEHTryTerminatedBlock = TryTerminatedBlock;
// Create a new block that will contain the __try statement.
CFGBlock *NewTryTerminatedBlock = createBlock(false);
// Add the terminator in the __try block.
NewTryTerminatedBlock->setTerminator(Terminator);
if (SEHExceptStmt *Except = Terminator->getExceptHandler()) {
// The code after the try is the implicit successor if there's an __except.
Succ = SEHTrySuccessor;
Block = nullptr;
CFGBlock *ExceptBlock = VisitSEHExceptStmt(Except);
if (!ExceptBlock)
return nullptr;
// Add this block to the list of successors for the block with the try
// statement.
addSuccessor(NewTryTerminatedBlock, ExceptBlock);
}
if (PrevSEHTryTerminatedBlock)
addSuccessor(NewTryTerminatedBlock, PrevSEHTryTerminatedBlock);
else
addSuccessor(NewTryTerminatedBlock, &cfg->getExit());
// The code after the try is the implicit successor.
Succ = SEHTrySuccessor;
// Save the current "__try" context.
SaveAndRestore<CFGBlock *> save_try(TryTerminatedBlock,
NewTryTerminatedBlock);
cfg->addTryDispatchBlock(TryTerminatedBlock);
// Save the current value for the __leave target.
// All __leaves should go to the code following the __try
// (FIXME: or if the __try has a __finally, to the __finally.)
SaveAndRestore<JumpTarget> save_break(SEHLeaveJumpTarget);
SEHLeaveJumpTarget = JumpTarget(SEHTrySuccessor, ScopePos);
assert(Terminator->getTryBlock() && "__try must contain a non-NULL body");
Block = nullptr;
return addStmt(Terminator->getTryBlock());
}
CFGBlock *CFGBuilder::VisitLabelStmt(LabelStmt *L) {
// Get the block of the labeled statement. Add it to our map.
addStmt(L->getSubStmt());
CFGBlock *LabelBlock = Block;
if (!LabelBlock) // This can happen when the body is empty, i.e.
LabelBlock = createBlock(); // scopes that only contains NullStmts.
assert(LabelMap.find(L->getDecl()) == LabelMap.end() &&
"label already in map");
LabelMap[L->getDecl()] = JumpTarget(LabelBlock, ScopePos);
// Labels partition blocks, so this is the end of the basic block we were
// processing (L is the block's label). Because this is label (and we have
// already processed the substatement) there is no extra control-flow to worry
// about.
LabelBlock->setLabel(L);
if (badCFG)
return nullptr;
// We set Block to NULL to allow lazy creation of a new block (if necessary);
Block = nullptr;
// This block is now the implicit successor of other blocks.
Succ = LabelBlock;
return LabelBlock;
}
CFGBlock *CFGBuilder::VisitBlockExpr(BlockExpr *E, AddStmtChoice asc) {
CFGBlock *LastBlock = VisitNoRecurse(E, asc);
for (const BlockDecl::Capture &CI : E->getBlockDecl()->captures()) {
if (Expr *CopyExpr = CI.getCopyExpr()) {
CFGBlock *Tmp = Visit(CopyExpr);
if (Tmp)
LastBlock = Tmp;
}
}
return LastBlock;
}
CFGBlock *CFGBuilder::VisitLambdaExpr(LambdaExpr *E, AddStmtChoice asc) {
CFGBlock *LastBlock = VisitNoRecurse(E, asc);
for (LambdaExpr::capture_init_iterator it = E->capture_init_begin(),
et = E->capture_init_end(); it != et; ++it) {
if (Expr *Init = *it) {
CFGBlock *Tmp = Visit(Init);
if (Tmp)
LastBlock = Tmp;
}
}
return LastBlock;
}
CFGBlock *CFGBuilder::VisitGotoStmt(GotoStmt *G) {
// Goto is a control-flow statement. Thus we stop processing the current
// block and create a new one.
Block = createBlock(false);
Block->setTerminator(G);
// If we already know the mapping to the label block add the successor now.
LabelMapTy::iterator I = LabelMap.find(G->getLabel());
if (I == LabelMap.end())
// We will need to backpatch this block later.
BackpatchBlocks.push_back(JumpSource(Block, ScopePos));
else {
JumpTarget JT = I->second;
addAutomaticObjHandling(ScopePos, JT.scopePosition, G);
addSuccessor(Block, JT.block);
}
return Block;
}
CFGBlock *CFGBuilder::VisitGCCAsmStmt(GCCAsmStmt *G, AddStmtChoice asc) {
// Goto is a control-flow statement. Thus we stop processing the current
// block and create a new one.
if (!G->isAsmGoto())
return VisitStmt(G, asc);
if (Block) {
Succ = Block;
if (badCFG)
return nullptr;
}
Block = createBlock();
Block->setTerminator(G);
// We will backpatch this block later for all the labels.
BackpatchBlocks.push_back(JumpSource(Block, ScopePos));
// Save "Succ" in BackpatchBlocks. In the backpatch processing, "Succ" is
// used to avoid adding "Succ" again.
BackpatchBlocks.push_back(JumpSource(Succ, ScopePos));
return Block;
}
CFGBlock *CFGBuilder::VisitForStmt(ForStmt *F) {
CFGBlock *LoopSuccessor = nullptr;
// Save local scope position because in case of condition variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scope for init statement and possible condition variable.
// Add destructor for init statement and condition variable.
// Store scope position for continue statement.
if (Stmt *Init = F->getInit())
addLocalScopeForStmt(Init);
LocalScope::const_iterator LoopBeginScopePos = ScopePos;
if (VarDecl *VD = F->getConditionVariable())
addLocalScopeForVarDecl(VD);
LocalScope::const_iterator ContinueScopePos = ScopePos;
addAutomaticObjHandling(ScopePos, save_scope_pos.get(), F);
addLoopExit(F);
// "for" is a control-flow statement. Thus we stop processing the current
// block.
if (Block) {
if (badCFG)
return nullptr;
LoopSuccessor = Block;
} else
LoopSuccessor = Succ;
// Save the current value for the break targets.
// All breaks should go to the code following the loop.
SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
CFGBlock *BodyBlock = nullptr, *TransitionBlock = nullptr;
// Now create the loop body.
{
assert(F->getBody());
// Save the current values for Block, Succ, continue and break targets.
SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget);
// Create an empty block to represent the transition block for looping back
// to the head of the loop. If we have increment code, it will
// go in this block as well.
Block = Succ = TransitionBlock = createBlock(false);
TransitionBlock->setLoopTarget(F);
if (Stmt *I = F->getInc()) {
// Generate increment code in its own basic block. This is the target of
// continue statements.
Succ = addStmt(I);
}
// Finish up the increment (or empty) block if it hasn't been already.
if (Block) {
assert(Block == Succ);
if (badCFG)
return nullptr;
Block = nullptr;
}
// The starting block for the loop increment is the block that should
// represent the 'loop target' for looping back to the start of the loop.
ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos);
ContinueJumpTarget.block->setLoopTarget(F);
// Loop body should end with destructor of Condition variable (if any).
addAutomaticObjHandling(ScopePos, LoopBeginScopePos, F);
// If body is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(F->getBody()))
addLocalScopeAndDtors(F->getBody());
// Now populate the body block, and in the process create new blocks as we
// walk the body of the loop.
BodyBlock = addStmt(F->getBody());
if (!BodyBlock) {
// In the case of "for (...;...;...);" we can have a null BodyBlock.
// Use the continue jump target as the proxy for the body.
BodyBlock = ContinueJumpTarget.block;
}
else if (badCFG)
return nullptr;
}
// Because of short-circuit evaluation, the condition of the loop can span
// multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
// evaluate the condition.
CFGBlock *EntryConditionBlock = nullptr, *ExitConditionBlock = nullptr;
do {
Expr *C = F->getCond();
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Specially handle logical operators, which have a slightly
// more optimal CFG representation.
if (BinaryOperator *Cond =
dyn_cast_or_null<BinaryOperator>(C ? C->IgnoreParens() : nullptr))
if (Cond->isLogicalOp()) {
std::tie(EntryConditionBlock, ExitConditionBlock) =
VisitLogicalOperator(Cond, F, BodyBlock, LoopSuccessor);
break;
}
// The default case when not handling logical operators.
EntryConditionBlock = ExitConditionBlock = createBlock(false);
ExitConditionBlock->setTerminator(F);
// See if this is a known constant.
TryResult KnownVal(true);
if (C) {
// Now add the actual condition to the condition block.
// Because the condition itself may contain control-flow, new blocks may
// be created. Thus we update "Succ" after adding the condition.
Block = ExitConditionBlock;
EntryConditionBlock = addStmt(C);
// If this block contains a condition variable, add both the condition
// variable and initializer to the CFG.
if (VarDecl *VD = F->getConditionVariable()) {
if (Expr *Init = VD->getInit()) {
autoCreateBlock();
const DeclStmt *DS = F->getConditionVariableDeclStmt();
assert(DS->isSingleDecl());
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), DS),
Init);
appendStmt(Block, DS);
EntryConditionBlock = addStmt(Init);
assert(Block == EntryConditionBlock);
maybeAddScopeBeginForVarDecl(EntryConditionBlock, VD, C);
}
}
if (Block && badCFG)
return nullptr;
KnownVal = tryEvaluateBool(C);
}
// Add the loop body entry as a successor to the condition.
addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? nullptr : BodyBlock);
// Link up the condition block with the code that follows the loop. (the
// false branch).
addSuccessor(ExitConditionBlock,
KnownVal.isTrue() ? nullptr : LoopSuccessor);
} while (false);
// Link up the loop-back block to the entry condition block.
addSuccessor(TransitionBlock, EntryConditionBlock);
// The condition block is the implicit successor for any code above the loop.
Succ = EntryConditionBlock;
// If the loop contains initialization, create a new block for those
// statements. This block can also contain statements that precede the loop.
if (Stmt *I = F->getInit()) {
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
ScopePos = LoopBeginScopePos;
Block = createBlock();
return addStmt(I);
}
// There is no loop initialization. We are thus basically a while loop.
// NULL out Block to force lazy block construction.
Block = nullptr;
Succ = EntryConditionBlock;
return EntryConditionBlock;
}
CFGBlock *
CFGBuilder::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *MTE,
AddStmtChoice asc) {
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), MTE),
MTE->getSubExpr());
return VisitStmt(MTE, asc);
}
CFGBlock *CFGBuilder::VisitMemberExpr(MemberExpr *M, AddStmtChoice asc) {
if (asc.alwaysAdd(*this, M)) {
autoCreateBlock();
appendStmt(Block, M);
}
return Visit(M->getBase());
}
CFGBlock *CFGBuilder::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
// Objective-C fast enumeration 'for' statements:
// http://developer.apple.com/documentation/Cocoa/Conceptual/ObjectiveC
//
// for ( Type newVariable in collection_expression ) { statements }
//
// becomes:
//
// prologue:
// 1. collection_expression
// T. jump to loop_entry
// loop_entry:
// 1. side-effects of element expression
// 1. ObjCForCollectionStmt [performs binding to newVariable]
// T. ObjCForCollectionStmt TB, FB [jumps to TB if newVariable != nil]
// TB:
// statements
// T. jump to loop_entry
// FB:
// what comes after
//
// and
//
// Type existingItem;
// for ( existingItem in expression ) { statements }
//
// becomes:
//
// the same with newVariable replaced with existingItem; the binding works
// the same except that for one ObjCForCollectionStmt::getElement() returns
// a DeclStmt and the other returns a DeclRefExpr.
CFGBlock *LoopSuccessor = nullptr;
if (Block) {
if (badCFG)
return nullptr;
LoopSuccessor = Block;
Block = nullptr;
} else
LoopSuccessor = Succ;
// Build the condition blocks.
CFGBlock *ExitConditionBlock = createBlock(false);
// Set the terminator for the "exit" condition block.
ExitConditionBlock->setTerminator(S);
// The last statement in the block should be the ObjCForCollectionStmt, which
// performs the actual binding to 'element' and determines if there are any
// more items in the collection.
appendStmt(ExitConditionBlock, S);
Block = ExitConditionBlock;
// Walk the 'element' expression to see if there are any side-effects. We
// generate new blocks as necessary. We DON'T add the statement by default to
// the CFG unless it contains control-flow.
CFGBlock *EntryConditionBlock = Visit(S->getElement(),
AddStmtChoice::NotAlwaysAdd);
if (Block) {
if (badCFG)
return nullptr;
Block = nullptr;
}
// The condition block is the implicit successor for the loop body as well as
// any code above the loop.
Succ = EntryConditionBlock;
// Now create the true branch.
{
// Save the current values for Succ, continue and break targets.
SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
save_break(BreakJumpTarget);
// Add an intermediate block between the BodyBlock and the
// EntryConditionBlock to represent the "loop back" transition, for looping
// back to the head of the loop.
CFGBlock *LoopBackBlock = nullptr;
Succ = LoopBackBlock = createBlock();
LoopBackBlock->setLoopTarget(S);
BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
ContinueJumpTarget = JumpTarget(Succ, ScopePos);
CFGBlock *BodyBlock = addStmt(S->getBody());
if (!BodyBlock)
BodyBlock = ContinueJumpTarget.block; // can happen for "for (X in Y) ;"
else if (Block) {
if (badCFG)
return nullptr;
}
// This new body block is a successor to our "exit" condition block.
addSuccessor(ExitConditionBlock, BodyBlock);
}
// Link up the condition block with the code that follows the loop.
// (the false branch).
addSuccessor(ExitConditionBlock, LoopSuccessor);
// Now create a prologue block to contain the collection expression.
Block = createBlock();
return addStmt(S->getCollection());
}
CFGBlock *CFGBuilder::VisitObjCAutoreleasePoolStmt(ObjCAutoreleasePoolStmt *S) {
// Inline the body.
return addStmt(S->getSubStmt());
// TODO: consider adding cleanups for the end of @autoreleasepool scope.
}
CFGBlock *CFGBuilder::VisitObjCAtSynchronizedStmt(ObjCAtSynchronizedStmt *S) {
// FIXME: Add locking 'primitives' to CFG for @synchronized.
// Inline the body.
CFGBlock *SyncBlock = addStmt(S->getSynchBody());
// The sync body starts its own basic block. This makes it a little easier
// for diagnostic clients.
if (SyncBlock) {
if (badCFG)
return nullptr;
Block = nullptr;
Succ = SyncBlock;
}
// Add the @synchronized to the CFG.
autoCreateBlock();
appendStmt(Block, S);
// Inline the sync expression.
return addStmt(S->getSynchExpr());
}
CFGBlock *CFGBuilder::VisitObjCAtTryStmt(ObjCAtTryStmt *S) {
// FIXME
return NYS();
}
CFGBlock *CFGBuilder::VisitPseudoObjectExpr(PseudoObjectExpr *E) {
autoCreateBlock();
// Add the PseudoObject as the last thing.
appendStmt(Block, E);
CFGBlock *lastBlock = Block;
// Before that, evaluate all of the semantics in order. In
// CFG-land, that means appending them in reverse order.
for (unsigned i = E->getNumSemanticExprs(); i != 0; ) {
Expr *Semantic = E->getSemanticExpr(--i);
// If the semantic is an opaque value, we're being asked to bind
// it to its source expression.
if (OpaqueValueExpr *OVE = dyn_cast<OpaqueValueExpr>(Semantic))
Semantic = OVE->getSourceExpr();
if (CFGBlock *B = Visit(Semantic))
lastBlock = B;
}
return lastBlock;
}
CFGBlock *CFGBuilder::VisitWhileStmt(WhileStmt *W) {
CFGBlock *LoopSuccessor = nullptr;
// Save local scope position because in case of condition variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scope for possible condition variable.
// Store scope position for continue statement.
LocalScope::const_iterator LoopBeginScopePos = ScopePos;
if (VarDecl *VD = W->getConditionVariable()) {
addLocalScopeForVarDecl(VD);
addAutomaticObjHandling(ScopePos, LoopBeginScopePos, W);
}
addLoopExit(W);
// "while" is a control-flow statement. Thus we stop processing the current
// block.
if (Block) {
if (badCFG)
return nullptr;
LoopSuccessor = Block;
Block = nullptr;
} else {
LoopSuccessor = Succ;
}
CFGBlock *BodyBlock = nullptr, *TransitionBlock = nullptr;
// Process the loop body.
{
assert(W->getBody());
// Save the current values for Block, Succ, continue and break targets.
SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
save_break(BreakJumpTarget);
// Create an empty block to represent the transition block for looping back
// to the head of the loop.
Succ = TransitionBlock = createBlock(false);
TransitionBlock->setLoopTarget(W);
ContinueJumpTarget = JumpTarget(Succ, LoopBeginScopePos);
// All breaks should go to the code following the loop.
BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
// Loop body should end with destructor of Condition variable (if any).
addAutomaticObjHandling(ScopePos, LoopBeginScopePos, W);
// If body is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(W->getBody()))
addLocalScopeAndDtors(W->getBody());
// Create the body. The returned block is the entry to the loop body.
BodyBlock = addStmt(W->getBody());
if (!BodyBlock)
BodyBlock = ContinueJumpTarget.block; // can happen for "while(...) ;"
else if (Block && badCFG)
return nullptr;
}
// Because of short-circuit evaluation, the condition of the loop can span
// multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
// evaluate the condition.
CFGBlock *EntryConditionBlock = nullptr, *ExitConditionBlock = nullptr;
do {
Expr *C = W->getCond();
// Specially handle logical operators, which have a slightly
// more optimal CFG representation.
if (BinaryOperator *Cond = dyn_cast<BinaryOperator>(C->IgnoreParens()))
if (Cond->isLogicalOp()) {
std::tie(EntryConditionBlock, ExitConditionBlock) =
VisitLogicalOperator(Cond, W, BodyBlock, LoopSuccessor);
break;
}
// The default case when not handling logical operators.
ExitConditionBlock = createBlock(false);
ExitConditionBlock->setTerminator(W);
// Now add the actual condition to the condition block.
// Because the condition itself may contain control-flow, new blocks may
// be created. Thus we update "Succ" after adding the condition.
Block = ExitConditionBlock;
Block = EntryConditionBlock = addStmt(C);
// If this block contains a condition variable, add both the condition
// variable and initializer to the CFG.
if (VarDecl *VD = W->getConditionVariable()) {
if (Expr *Init = VD->getInit()) {
autoCreateBlock();
const DeclStmt *DS = W->getConditionVariableDeclStmt();
assert(DS->isSingleDecl());
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(),
const_cast<DeclStmt *>(DS)),
Init);
appendStmt(Block, DS);
EntryConditionBlock = addStmt(Init);
assert(Block == EntryConditionBlock);
maybeAddScopeBeginForVarDecl(EntryConditionBlock, VD, C);
}
}
if (Block && badCFG)
return nullptr;
// See if this is a known constant.
const TryResult& KnownVal = tryEvaluateBool(C);
// Add the loop body entry as a successor to the condition.
addSuccessor(ExitConditionBlock, KnownVal.isFalse() ? nullptr : BodyBlock);
// Link up the condition block with the code that follows the loop. (the
// false branch).
addSuccessor(ExitConditionBlock,
KnownVal.isTrue() ? nullptr : LoopSuccessor);
} while(false);
// Link up the loop-back block to the entry condition block.
addSuccessor(TransitionBlock, EntryConditionBlock);
// There can be no more statements in the condition block since we loop back
// to this block. NULL out Block to force lazy creation of another block.
Block = nullptr;
// Return the condition block, which is the dominating block for the loop.
Succ = EntryConditionBlock;
return EntryConditionBlock;
}
CFGBlock *CFGBuilder::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
// FIXME: For now we pretend that @catch and the code it contains does not
// exit.
return Block;
}
CFGBlock *CFGBuilder::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) {
// FIXME: This isn't complete. We basically treat @throw like a return
// statement.
// If we were in the middle of a block we stop processing that block.
if (badCFG)
return nullptr;
// Create the new block.
Block = createBlock(false);
// The Exit block is the only successor.
addSuccessor(Block, &cfg->getExit());
// Add the statement to the block. This may create new blocks if S contains
// control-flow (short-circuit operations).
return VisitStmt(S, AddStmtChoice::AlwaysAdd);
}
CFGBlock *CFGBuilder::VisitObjCMessageExpr(ObjCMessageExpr *ME,
AddStmtChoice asc) {
findConstructionContextsForArguments(ME);
autoCreateBlock();
appendObjCMessage(Block, ME);
return VisitChildren(ME);
}
CFGBlock *CFGBuilder::VisitCXXThrowExpr(CXXThrowExpr *T) {
// If we were in the middle of a block we stop processing that block.
if (badCFG)
return nullptr;
// Create the new block.
Block = createBlock(false);
if (TryTerminatedBlock)
// The current try statement is the only successor.
addSuccessor(Block, TryTerminatedBlock);
else
// otherwise the Exit block is the only successor.
addSuccessor(Block, &cfg->getExit());
// Add the statement to the block. This may create new blocks if S contains
// control-flow (short-circuit operations).
return VisitStmt(T, AddStmtChoice::AlwaysAdd);
}
CFGBlock *CFGBuilder::VisitDoStmt(DoStmt *D) {
CFGBlock *LoopSuccessor = nullptr;
addLoopExit(D);
// "do...while" is a control-flow statement. Thus we stop processing the
// current block.
if (Block) {
if (badCFG)
return nullptr;
LoopSuccessor = Block;
} else
LoopSuccessor = Succ;
// Because of short-circuit evaluation, the condition of the loop can span
// multiple basic blocks. Thus we need the "Entry" and "Exit" blocks that
// evaluate the condition.
CFGBlock *ExitConditionBlock = createBlock(false);
CFGBlock *EntryConditionBlock = ExitConditionBlock;
// Set the terminator for the "exit" condition block.
ExitConditionBlock->setTerminator(D);
// Now add the actual condition to the condition block. Because the condition
// itself may contain control-flow, new blocks may be created.
if (Stmt *C = D->getCond()) {
Block = ExitConditionBlock;
EntryConditionBlock = addStmt(C);
if (Block) {
if (badCFG)
return nullptr;
}
}
// The condition block is the implicit successor for the loop body.
Succ = EntryConditionBlock;
// See if this is a known constant.
const TryResult &KnownVal = tryEvaluateBool(D->getCond());
// Process the loop body.
CFGBlock *BodyBlock = nullptr;
{
assert(D->getBody());
// Save the current values for Block, Succ, and continue and break targets
SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget),
save_break(BreakJumpTarget);
// All continues within this loop should go to the condition block
ContinueJumpTarget = JumpTarget(EntryConditionBlock, ScopePos);
// All breaks should go to the code following the loop.
BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
// NULL out Block to force lazy instantiation of blocks for the body.
Block = nullptr;
// If body is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(D->getBody()))
addLocalScopeAndDtors(D->getBody());
// Create the body. The returned block is the entry to the loop body.
BodyBlock = addStmt(D->getBody());
if (!BodyBlock)
BodyBlock = EntryConditionBlock; // can happen for "do ; while(...)"
else if (Block) {
if (badCFG)
return nullptr;
}
// Add an intermediate block between the BodyBlock and the
// ExitConditionBlock to represent the "loop back" transition. Create an
// empty block to represent the transition block for looping back to the
// head of the loop.
// FIXME: Can we do this more efficiently without adding another block?
Block = nullptr;
Succ = BodyBlock;
CFGBlock *LoopBackBlock = createBlock();
LoopBackBlock->setLoopTarget(D);
if (!KnownVal.isFalse())
// Add the loop body entry as a successor to the condition.
addSuccessor(ExitConditionBlock, LoopBackBlock);
else
addSuccessor(ExitConditionBlock, nullptr);
}
// Link up the condition block with the code that follows the loop.
// (the false branch).
addSuccessor(ExitConditionBlock, KnownVal.isTrue() ? nullptr : LoopSuccessor);
// There can be no more statements in the body block(s) since we loop back to
// the body. NULL out Block to force lazy creation of another block.
Block = nullptr;
// Return the loop body, which is the dominating block for the loop.
Succ = BodyBlock;
return BodyBlock;
}
CFGBlock *CFGBuilder::VisitContinueStmt(ContinueStmt *C) {
// "continue" is a control-flow statement. Thus we stop processing the
// current block.
if (badCFG)
return nullptr;
// Now create a new block that ends with the continue statement.
Block = createBlock(false);
Block->setTerminator(C);
// If there is no target for the continue, then we are looking at an
// incomplete AST. This means the CFG cannot be constructed.
if (ContinueJumpTarget.block) {
addAutomaticObjHandling(ScopePos, ContinueJumpTarget.scopePosition, C);
addSuccessor(Block, ContinueJumpTarget.block);
} else
badCFG = true;
return Block;
}
CFGBlock *CFGBuilder::VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, E)) {
autoCreateBlock();
appendStmt(Block, E);
}
// VLA types have expressions that must be evaluated.
CFGBlock *lastBlock = Block;
if (E->isArgumentType()) {
for (const VariableArrayType *VA =FindVA(E->getArgumentType().getTypePtr());
VA != nullptr; VA = FindVA(VA->getElementType().getTypePtr()))
lastBlock = addStmt(VA->getSizeExpr());
}
return lastBlock;
}
/// VisitStmtExpr - Utility method to handle (nested) statement
/// expressions (a GCC extension).
CFGBlock *CFGBuilder::VisitStmtExpr(StmtExpr *SE, AddStmtChoice asc) {
if (asc.alwaysAdd(*this, SE)) {
autoCreateBlock();
appendStmt(Block, SE);
}
return VisitCompoundStmt(SE->getSubStmt(), /*ExternallyDestructed=*/true);
}
CFGBlock *CFGBuilder::VisitSwitchStmt(SwitchStmt *Terminator) {
// "switch" is a control-flow statement. Thus we stop processing the current
// block.
CFGBlock *SwitchSuccessor = nullptr;
// Save local scope position because in case of condition variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scope for C++17 switch init-stmt if one exists.
if (Stmt *Init = Terminator->getInit())
addLocalScopeForStmt(Init);
// Create local scope for possible condition variable.
// Store scope position. Add implicit destructor.
if (VarDecl *VD = Terminator->getConditionVariable())
addLocalScopeForVarDecl(VD);
addAutomaticObjHandling(ScopePos, save_scope_pos.get(), Terminator);
if (Block) {
if (badCFG)
return nullptr;
SwitchSuccessor = Block;
} else SwitchSuccessor = Succ;
// Save the current "switch" context.
SaveAndRestore<CFGBlock*> save_switch(SwitchTerminatedBlock),
save_default(DefaultCaseBlock);
SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
// Set the "default" case to be the block after the switch statement. If the
// switch statement contains a "default:", this value will be overwritten with
// the block for that code.
DefaultCaseBlock = SwitchSuccessor;
// Create a new block that will contain the switch statement.
SwitchTerminatedBlock = createBlock(false);
// Now process the switch body. The code after the switch is the implicit
// successor.
Succ = SwitchSuccessor;
BreakJumpTarget = JumpTarget(SwitchSuccessor, ScopePos);
// When visiting the body, the case statements should automatically get linked
// up to the switch. We also don't keep a pointer to the body, since all
// control-flow from the switch goes to case/default statements.
assert(Terminator->getBody() && "switch must contain a non-NULL body");
Block = nullptr;
// For pruning unreachable case statements, save the current state
// for tracking the condition value.
SaveAndRestore<bool> save_switchExclusivelyCovered(switchExclusivelyCovered,
false);
// Determine if the switch condition can be explicitly evaluated.
assert(Terminator->getCond() && "switch condition must be non-NULL");
Expr::EvalResult result;
bool b = tryEvaluate(Terminator->getCond(), result);
SaveAndRestore<Expr::EvalResult*> save_switchCond(switchCond,
b ? &result : nullptr);
// If body is not a compound statement create implicit scope
// and add destructors.
if (!isa<CompoundStmt>(Terminator->getBody()))
addLocalScopeAndDtors(Terminator->getBody());
addStmt(Terminator->getBody());
if (Block) {
if (badCFG)
return nullptr;
}
// If we have no "default:" case, the default transition is to the code
// following the switch body. Moreover, take into account if all the
// cases of a switch are covered (e.g., switching on an enum value).
//
// Note: We add a successor to a switch that is considered covered yet has no
// case statements if the enumeration has no enumerators.
bool SwitchAlwaysHasSuccessor = false;
SwitchAlwaysHasSuccessor |= switchExclusivelyCovered;
SwitchAlwaysHasSuccessor |= Terminator->isAllEnumCasesCovered() &&
Terminator->getSwitchCaseList();
addSuccessor(SwitchTerminatedBlock, DefaultCaseBlock,
!SwitchAlwaysHasSuccessor);
// Add the terminator and condition in the switch block.
SwitchTerminatedBlock->setTerminator(Terminator);
Block = SwitchTerminatedBlock;
CFGBlock *LastBlock = addStmt(Terminator->getCond());
// If the SwitchStmt contains a condition variable, add both the
// SwitchStmt and the condition variable initialization to the CFG.
if (VarDecl *VD = Terminator->getConditionVariable()) {
if (Expr *Init = VD->getInit()) {
autoCreateBlock();
appendStmt(Block, Terminator->getConditionVariableDeclStmt());
LastBlock = addStmt(Init);
maybeAddScopeBeginForVarDecl(LastBlock, VD, Init);
}
}
// Finally, if the SwitchStmt contains a C++17 init-stmt, add it to the CFG.
if (Stmt *Init = Terminator->getInit()) {
autoCreateBlock();
LastBlock = addStmt(Init);
}
return LastBlock;
}
static bool shouldAddCase(bool &switchExclusivelyCovered,
const Expr::EvalResult *switchCond,
const CaseStmt *CS,
ASTContext &Ctx) {
if (!switchCond)
return true;
bool addCase = false;
if (!switchExclusivelyCovered) {
if (switchCond->Val.isInt()) {
// Evaluate the LHS of the case value.
const llvm::APSInt &lhsInt = CS->getLHS()->EvaluateKnownConstInt(Ctx);
const llvm::APSInt &condInt = switchCond->Val.getInt();
if (condInt == lhsInt) {
addCase = true;
switchExclusivelyCovered = true;
}
else if (condInt > lhsInt) {
if (const Expr *RHS = CS->getRHS()) {
// Evaluate the RHS of the case value.
const llvm::APSInt &V2 = RHS->EvaluateKnownConstInt(Ctx);
if (V2 >= condInt) {
addCase = true;
switchExclusivelyCovered = true;
}
}
}
}
else
addCase = true;
}
return addCase;
}
CFGBlock *CFGBuilder::VisitCaseStmt(CaseStmt *CS) {
// CaseStmts are essentially labels, so they are the first statement in a
// block.
CFGBlock *TopBlock = nullptr, *LastBlock = nullptr;
if (Stmt *Sub = CS->getSubStmt()) {
// For deeply nested chains of CaseStmts, instead of doing a recursion
// (which can blow out the stack), manually unroll and create blocks
// along the way.
while (isa<CaseStmt>(Sub)) {
CFGBlock *currentBlock = createBlock(false);
currentBlock->setLabel(CS);
if (TopBlock)
addSuccessor(LastBlock, currentBlock);
else
TopBlock = currentBlock;
addSuccessor(SwitchTerminatedBlock,
shouldAddCase(switchExclusivelyCovered, switchCond,
CS, *Context)
? currentBlock : nullptr);
LastBlock = currentBlock;
CS = cast<CaseStmt>(Sub);
Sub = CS->getSubStmt();
}
addStmt(Sub);
}
CFGBlock *CaseBlock = Block;
if (!CaseBlock)
CaseBlock = createBlock();
// Cases statements partition blocks, so this is the top of the basic block we
// were processing (the "case XXX:" is the label).
CaseBlock->setLabel(CS);
if (badCFG)
return nullptr;
// Add this block to the list of successors for the block with the switch
// statement.
assert(SwitchTerminatedBlock);
addSuccessor(SwitchTerminatedBlock, CaseBlock,
shouldAddCase(switchExclusivelyCovered, switchCond,
CS, *Context));
// We set Block to NULL to allow lazy creation of a new block (if necessary)
Block = nullptr;
if (TopBlock) {
addSuccessor(LastBlock, CaseBlock);
Succ = TopBlock;
} else {
// This block is now the implicit successor of other blocks.
Succ = CaseBlock;
}
return Succ;
}
CFGBlock *CFGBuilder::VisitDefaultStmt(DefaultStmt *Terminator) {
if (Terminator->getSubStmt())
addStmt(Terminator->getSubStmt());
DefaultCaseBlock = Block;
if (!DefaultCaseBlock)
DefaultCaseBlock = createBlock();
// Default statements partition blocks, so this is the top of the basic block
// we were processing (the "default:" is the label).
DefaultCaseBlock->setLabel(Terminator);
if (badCFG)
return nullptr;
// Unlike case statements, we don't add the default block to the successors
// for the switch statement immediately. This is done when we finish
// processing the switch statement. This allows for the default case
// (including a fall-through to the code after the switch statement) to always
// be the last successor of a switch-terminated block.
// We set Block to NULL to allow lazy creation of a new block (if necessary)
Block = nullptr;
// This block is now the implicit successor of other blocks.
Succ = DefaultCaseBlock;
return DefaultCaseBlock;
}
CFGBlock *CFGBuilder::VisitCXXTryStmt(CXXTryStmt *Terminator) {
// "try"/"catch" is a control-flow statement. Thus we stop processing the
// current block.
CFGBlock *TrySuccessor = nullptr;
if (Block) {
if (badCFG)
return nullptr;
TrySuccessor = Block;
} else TrySuccessor = Succ;
CFGBlock *PrevTryTerminatedBlock = TryTerminatedBlock;
// Create a new block that will contain the try statement.
CFGBlock *NewTryTerminatedBlock = createBlock(false);
// Add the terminator in the try block.
NewTryTerminatedBlock->setTerminator(Terminator);
bool HasCatchAll = false;
for (unsigned h = 0; h <Terminator->getNumHandlers(); ++h) {
// The code after the try is the implicit successor.
Succ = TrySuccessor;
CXXCatchStmt *CS = Terminator->getHandler(h);
if (CS->getExceptionDecl() == nullptr) {
HasCatchAll = true;
}
Block = nullptr;
CFGBlock *CatchBlock = VisitCXXCatchStmt(CS);
if (!CatchBlock)
return nullptr;
// Add this block to the list of successors for the block with the try
// statement.
addSuccessor(NewTryTerminatedBlock, CatchBlock);
}
if (!HasCatchAll) {
if (PrevTryTerminatedBlock)
addSuccessor(NewTryTerminatedBlock, PrevTryTerminatedBlock);
else
addSuccessor(NewTryTerminatedBlock, &cfg->getExit());
}
// The code after the try is the implicit successor.
Succ = TrySuccessor;
// Save the current "try" context.
SaveAndRestore<CFGBlock*> save_try(TryTerminatedBlock, NewTryTerminatedBlock);
cfg->addTryDispatchBlock(TryTerminatedBlock);
assert(Terminator->getTryBlock() && "try must contain a non-NULL body");
Block = nullptr;
return addStmt(Terminator->getTryBlock());
}
CFGBlock *CFGBuilder::VisitCXXCatchStmt(CXXCatchStmt *CS) {
// CXXCatchStmt are treated like labels, so they are the first statement in a
// block.
// Save local scope position because in case of exception variable ScopePos
// won't be restored when traversing AST.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scope for possible exception variable.
// Store scope position. Add implicit destructor.
if (VarDecl *VD = CS->getExceptionDecl()) {
LocalScope::const_iterator BeginScopePos = ScopePos;
addLocalScopeForVarDecl(VD);
addAutomaticObjHandling(ScopePos, BeginScopePos, CS);
}
if (CS->getHandlerBlock())
addStmt(CS->getHandlerBlock());
CFGBlock *CatchBlock = Block;
if (!CatchBlock)
CatchBlock = createBlock();
// CXXCatchStmt is more than just a label. They have semantic meaning
// as well, as they implicitly "initialize" the catch variable. Add
// it to the CFG as a CFGElement so that the control-flow of these
// semantics gets captured.
appendStmt(CatchBlock, CS);
// Also add the CXXCatchStmt as a label, to mirror handling of regular
// labels.
CatchBlock->setLabel(CS);
// Bail out if the CFG is bad.
if (badCFG)
return nullptr;
// We set Block to NULL to allow lazy creation of a new block (if necessary)
Block = nullptr;
return CatchBlock;
}
CFGBlock *CFGBuilder::VisitCXXForRangeStmt(CXXForRangeStmt *S) {
// C++0x for-range statements are specified as [stmt.ranged]:
//
// {
// auto && __range = range-init;
// for ( auto __begin = begin-expr,
// __end = end-expr;
// __begin != __end;
// ++__begin ) {
// for-range-declaration = *__begin;
// statement
// }
// }
// Save local scope position before the addition of the implicit variables.
SaveAndRestore<LocalScope::const_iterator> save_scope_pos(ScopePos);
// Create local scopes and destructors for range, begin and end variables.
if (Stmt *Range = S->getRangeStmt())
addLocalScopeForStmt(Range);
if (Stmt *Begin = S->getBeginStmt())
addLocalScopeForStmt(Begin);
if (Stmt *End = S->getEndStmt())
addLocalScopeForStmt(End);
addAutomaticObjHandling(ScopePos, save_scope_pos.get(), S);
LocalScope::const_iterator ContinueScopePos = ScopePos;
// "for" is a control-flow statement. Thus we stop processing the current
// block.
CFGBlock *LoopSuccessor = nullptr;
if (Block) {
if (badCFG)
return nullptr;
LoopSuccessor = Block;
} else
LoopSuccessor = Succ;
// Save the current value for the break targets.
// All breaks should go to the code following the loop.
SaveAndRestore<JumpTarget> save_break(BreakJumpTarget);
BreakJumpTarget = JumpTarget(LoopSuccessor, ScopePos);
// The block for the __begin != __end expression.
CFGBlock *ConditionBlock = createBlock(false);
ConditionBlock->setTerminator(S);
// Now add the actual condition to the condition block.
if (Expr *C = S->getCond()) {
Block = ConditionBlock;
CFGBlock *BeginConditionBlock = addStmt(C);
if (badCFG)
return nullptr;
assert(BeginConditionBlock == ConditionBlock &&
"condition block in for-range was unexpectedly complex");
(void)BeginConditionBlock;
}
// The condition block is the implicit successor for the loop body as well as
// any code above the loop.
Succ = ConditionBlock;
// See if this is a known constant.
TryResult KnownVal(true);
if (S->getCond())
KnownVal = tryEvaluateBool(S->getCond());
// Now create the loop body.
{
assert(S->getBody());
// Save the current values for Block, Succ, and continue targets.
SaveAndRestore<CFGBlock*> save_Block(Block), save_Succ(Succ);
SaveAndRestore<JumpTarget> save_continue(ContinueJumpTarget);
// Generate increment code in its own basic block. This is the target of
// continue statements.
Block = nullptr;
Succ = addStmt(S->getInc());
if (badCFG)
return nullptr;
ContinueJumpTarget = JumpTarget(Succ, ContinueScopePos);
// The starting block for the loop increment is the block that should
// represent the 'loop target' for looping back to the start of the loop.
ContinueJumpTarget.block->setLoopTarget(S);
// Finish up the increment block and prepare to start the loop body.
assert(Block);
if (badCFG)
return nullptr;
Block = nullptr;
// Add implicit scope and dtors for loop variable.
addLocalScopeAndDtors(S->getLoopVarStmt());
// Populate a new block to contain the loop body and loop variable.
addStmt(S->getBody());
if (badCFG)
return nullptr;
CFGBlock *LoopVarStmtBlock = addStmt(S->getLoopVarStmt());
if (badCFG)
return nullptr;
// This new body block is a successor to our condition block.
addSuccessor(ConditionBlock,
KnownVal.isFalse() ? nullptr : LoopVarStmtBlock);
}
// Link up the condition block with the code that follows the loop (the
// false branch).
addSuccessor(ConditionBlock, KnownVal.isTrue() ? nullptr : LoopSuccessor);
// Add the initialization statements.
Block = createBlock();
addStmt(S->getBeginStmt());
addStmt(S->getEndStmt());
CFGBlock *Head = addStmt(S->getRangeStmt());
if (S->getInit())
Head = addStmt(S->getInit());
return Head;
}
CFGBlock *CFGBuilder::VisitExprWithCleanups(ExprWithCleanups *E,
AddStmtChoice asc, bool ExternallyDestructed) {
if (BuildOpts.AddTemporaryDtors) {
// If adding implicit destructors visit the full expression for adding
// destructors of temporaries.
TempDtorContext Context;
VisitForTemporaryDtors(E->getSubExpr(), ExternallyDestructed, Context);
// Full expression has to be added as CFGStmt so it will be sequenced
// before destructors of it's temporaries.
asc = asc.withAlwaysAdd(true);
}
return Visit(E->getSubExpr(), asc);
}
CFGBlock *CFGBuilder::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, E)) {
autoCreateBlock();
appendStmt(Block, E);
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), E),
E->getSubExpr());
// We do not want to propagate the AlwaysAdd property.
asc = asc.withAlwaysAdd(false);
}
return Visit(E->getSubExpr(), asc);
}
CFGBlock *CFGBuilder::VisitCXXConstructExpr(CXXConstructExpr *C,
AddStmtChoice asc) {
// If the constructor takes objects as arguments by value, we need to properly
// construct these objects. Construction contexts we find here aren't for the
// constructor C, they're for its arguments only.
findConstructionContextsForArguments(C);
autoCreateBlock();
appendConstructor(Block, C);
return VisitChildren(C);
}
CFGBlock *CFGBuilder::VisitCXXNewExpr(CXXNewExpr *NE,
AddStmtChoice asc) {
autoCreateBlock();
appendStmt(Block, NE);
findConstructionContexts(
ConstructionContextLayer::create(cfg->getBumpVectorContext(), NE),
const_cast<CXXConstructExpr *>(NE->getConstructExpr()));
if (NE->getInitializer())
Block = Visit(NE->getInitializer());
if (BuildOpts.AddCXXNewAllocator)
appendNewAllocator(Block, NE);
if (NE->isArray() && *NE->getArraySize())
Block = Visit(*NE->getArraySize());
for (CXXNewExpr::arg_iterator I = NE->placement_arg_begin(),
E = NE->placement_arg_end(); I != E; ++I)
Block = Visit(*I);
return Block;
}
CFGBlock *CFGBuilder::VisitCXXDeleteExpr(CXXDeleteExpr *DE,
AddStmtChoice asc) {
autoCreateBlock();
appendStmt(Block, DE);
QualType DTy = DE->getDestroyedType();
if (!DTy.isNull()) {
DTy = DTy.getNonReferenceType();
CXXRecordDecl *RD = Context->getBaseElementType(DTy)->getAsCXXRecordDecl();
if (RD) {
if (RD->isCompleteDefinition() && !RD->hasTrivialDestructor())
appendDeleteDtor(Block, RD, DE);
}
}
return VisitChildren(DE);
}
CFGBlock *CFGBuilder::VisitCXXFunctionalCastExpr(CXXFunctionalCastExpr *E,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, E)) {
autoCreateBlock();
appendStmt(Block, E);
// We do not want to propagate the AlwaysAdd property.
asc = asc.withAlwaysAdd(false);
}
return Visit(E->getSubExpr(), asc);
}
CFGBlock *CFGBuilder::VisitCXXTemporaryObjectExpr(CXXTemporaryObjectExpr *C,
AddStmtChoice asc) {
// If the constructor takes objects as arguments by value, we need to properly
// construct these objects. Construction contexts we find here aren't for the
// constructor C, they're for its arguments only.
findConstructionContextsForArguments(C);
autoCreateBlock();
appendConstructor(Block, C);
return VisitChildren(C);
}
CFGBlock *CFGBuilder::VisitImplicitCastExpr(ImplicitCastExpr *E,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, E)) {
autoCreateBlock();
appendStmt(Block, E);
}
if (E->getCastKind() == CK_IntegralToBoolean)
tryEvaluateBool(E->getSubExpr()->IgnoreParens());
return Visit(E->getSubExpr(), AddStmtChoice());
}
CFGBlock *CFGBuilder::VisitConstantExpr(ConstantExpr *E, AddStmtChoice asc) {
return Visit(E->getSubExpr(), AddStmtChoice());
}
CFGBlock *CFGBuilder::VisitIndirectGotoStmt(IndirectGotoStmt *I) {
// Lazily create the indirect-goto dispatch block if there isn't one already.
CFGBlock *IBlock = cfg->getIndirectGotoBlock();
if (!IBlock) {
IBlock = createBlock(false);
cfg->setIndirectGotoBlock(IBlock);
}
// IndirectGoto is a control-flow statement. Thus we stop processing the
// current block and create a new one.
if (badCFG)
return nullptr;
Block = createBlock(false);
Block->setTerminator(I);
addSuccessor(Block, IBlock);
return addStmt(I->getTarget());
}
CFGBlock *CFGBuilder::VisitForTemporaryDtors(Stmt *E, bool ExternallyDestructed,
TempDtorContext &Context) {
assert(BuildOpts.AddImplicitDtors && BuildOpts.AddTemporaryDtors);
tryAgain:
if (!E) {
badCFG = true;
return nullptr;
}
switch (E->getStmtClass()) {
default:
return VisitChildrenForTemporaryDtors(E, false, Context);
case Stmt::InitListExprClass:
return VisitChildrenForTemporaryDtors(E, ExternallyDestructed, Context);
case Stmt::BinaryOperatorClass:
return VisitBinaryOperatorForTemporaryDtors(cast<BinaryOperator>(E),
ExternallyDestructed,
Context);
case Stmt::CXXBindTemporaryExprClass:
return VisitCXXBindTemporaryExprForTemporaryDtors(
cast<CXXBindTemporaryExpr>(E), ExternallyDestructed, Context);
case Stmt::BinaryConditionalOperatorClass:
case Stmt::ConditionalOperatorClass:
return VisitConditionalOperatorForTemporaryDtors(
cast<AbstractConditionalOperator>(E), ExternallyDestructed, Context);
case Stmt::ImplicitCastExprClass:
// For implicit cast we want ExternallyDestructed to be passed further.
E = cast<CastExpr>(E)->getSubExpr();
goto tryAgain;
case Stmt::CXXFunctionalCastExprClass:
// For functional cast we want ExternallyDestructed to be passed further.
E = cast<CXXFunctionalCastExpr>(E)->getSubExpr();
goto tryAgain;
case Stmt::ConstantExprClass:
E = cast<ConstantExpr>(E)->getSubExpr();
goto tryAgain;
case Stmt::ParenExprClass:
E = cast<ParenExpr>(E)->getSubExpr();
goto tryAgain;
case Stmt::MaterializeTemporaryExprClass: {
const MaterializeTemporaryExpr* MTE = cast<MaterializeTemporaryExpr>(E);
ExternallyDestructed = (MTE->getStorageDuration() != SD_FullExpression);
SmallVector<const Expr *, 2> CommaLHSs;
SmallVector<SubobjectAdjustment, 2> Adjustments;
// Find the expression whose lifetime needs to be extended.
E = const_cast<Expr *>(
cast<MaterializeTemporaryExpr>(E)
->getSubExpr()
->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments));
// Visit the skipped comma operator left-hand sides for other temporaries.
for (const Expr *CommaLHS : CommaLHSs) {
VisitForTemporaryDtors(const_cast<Expr *>(CommaLHS),
/*ExternallyDestructed=*/false, Context);
}
goto tryAgain;
}
case Stmt::BlockExprClass:
// Don't recurse into blocks; their subexpressions don't get evaluated
// here.
return Block;
case Stmt::LambdaExprClass: {
// For lambda expressions, only recurse into the capture initializers,
// and not the body.
auto *LE = cast<LambdaExpr>(E);
CFGBlock *B = Block;
for (Expr *Init : LE->capture_inits()) {
if (Init) {
if (CFGBlock *R = VisitForTemporaryDtors(
Init, /*ExternallyDestructed=*/true, Context))
B = R;
}
}
return B;
}
case Stmt::StmtExprClass:
// Don't recurse into statement expressions; any cleanups inside them
// will be wrapped in their own ExprWithCleanups.
return Block;
case Stmt::CXXDefaultArgExprClass:
E = cast<CXXDefaultArgExpr>(E)->getExpr();
goto tryAgain;
case Stmt::CXXDefaultInitExprClass:
E = cast<CXXDefaultInitExpr>(E)->getExpr();
goto tryAgain;
}
}
CFGBlock *CFGBuilder::VisitChildrenForTemporaryDtors(Stmt *E,
bool ExternallyDestructed,
TempDtorContext &Context) {
if (isa<LambdaExpr>(E)) {
// Do not visit the children of lambdas; they have their own CFGs.
return Block;
}
// When visiting children for destructors we want to visit them in reverse
// order that they will appear in the CFG. Because the CFG is built
// bottom-up, this means we visit them in their natural order, which
// reverses them in the CFG.
CFGBlock *B = Block;
for (Stmt *Child : E->children())
if (Child)
if (CFGBlock *R = VisitForTemporaryDtors(Child, ExternallyDestructed, Context))
B = R;
return B;
}
CFGBlock *CFGBuilder::VisitBinaryOperatorForTemporaryDtors(
BinaryOperator *E, bool ExternallyDestructed, TempDtorContext &Context) {
if (E->isCommaOp()) {
// For comma operator LHS expression is visited
// before RHS expression. For destructors visit them in reverse order.
CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS(), ExternallyDestructed, Context);
CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS(), false, Context);
return LHSBlock ? LHSBlock : RHSBlock;
}
if (E->isLogicalOp()) {
VisitForTemporaryDtors(E->getLHS(), false, Context);
TryResult RHSExecuted = tryEvaluateBool(E->getLHS());
if (RHSExecuted.isKnown() && E->getOpcode() == BO_LOr)
RHSExecuted.negate();
// We do not know at CFG-construction time whether the right-hand-side was
// executed, thus we add a branch node that depends on the temporary
// constructor call.
TempDtorContext RHSContext(
bothKnownTrue(Context.KnownExecuted, RHSExecuted));
VisitForTemporaryDtors(E->getRHS(), false, RHSContext);
InsertTempDtorDecisionBlock(RHSContext);
return Block;
}
if (E->isAssignmentOp()) {
// For assignment operator (=) LHS expression is visited
// before RHS expression. For destructors visit them in reverse order.
CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS(), false, Context);
CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS(), false, Context);
return LHSBlock ? LHSBlock : RHSBlock;
}
// For any other binary operator RHS expression is visited before
// LHS expression (order of children). For destructors visit them in reverse
// order.
CFGBlock *LHSBlock = VisitForTemporaryDtors(E->getLHS(), false, Context);
CFGBlock *RHSBlock = VisitForTemporaryDtors(E->getRHS(), false, Context);
return RHSBlock ? RHSBlock : LHSBlock;
}
CFGBlock *CFGBuilder::VisitCXXBindTemporaryExprForTemporaryDtors(
CXXBindTemporaryExpr *E, bool ExternallyDestructed, TempDtorContext &Context) {
// First add destructors for temporaries in subexpression.
// Because VisitCXXBindTemporaryExpr calls setDestructed:
CFGBlock *B = VisitForTemporaryDtors(E->getSubExpr(), true, Context);
if (!ExternallyDestructed) {
// If lifetime of temporary is not prolonged (by assigning to constant
// reference) add destructor for it.
const CXXDestructorDecl *Dtor = E->getTemporary()->getDestructor();
if (Dtor->getParent()->isAnyDestructorNoReturn()) {
// If the destructor is marked as a no-return destructor, we need to
// create a new block for the destructor which does not have as a
// successor anything built thus far. Control won't flow out of this
// block.
if (B) Succ = B;
Block = createNoReturnBlock();
} else if (Context.needsTempDtorBranch()) {
// If we need to introduce a branch, we add a new block that we will hook
// up to a decision block later.
if (B) Succ = B;
Block = createBlock();
} else {
autoCreateBlock();
}
if (Context.needsTempDtorBranch()) {
Context.setDecisionPoint(Succ, E);
}
appendTemporaryDtor(Block, E);
B = Block;
}
return B;
}
void CFGBuilder::InsertTempDtorDecisionBlock(const TempDtorContext &Context,
CFGBlock *FalseSucc) {
if (!Context.TerminatorExpr) {
// If no temporary was found, we do not need to insert a decision point.
return;
}
assert(Context.TerminatorExpr);
CFGBlock *Decision = createBlock(false);
Decision->setTerminator(CFGTerminator(Context.TerminatorExpr,
CFGTerminator::TemporaryDtorsBranch));
addSuccessor(Decision, Block, !Context.KnownExecuted.isFalse());
addSuccessor(Decision, FalseSucc ? FalseSucc : Context.Succ,
!Context.KnownExecuted.isTrue());
Block = Decision;
}
CFGBlock *CFGBuilder::VisitConditionalOperatorForTemporaryDtors(
AbstractConditionalOperator *E, bool ExternallyDestructed,
TempDtorContext &Context) {
VisitForTemporaryDtors(E->getCond(), false, Context);
CFGBlock *ConditionBlock = Block;
CFGBlock *ConditionSucc = Succ;
TryResult ConditionVal = tryEvaluateBool(E->getCond());
TryResult NegatedVal = ConditionVal;
if (NegatedVal.isKnown()) NegatedVal.negate();
TempDtorContext TrueContext(
bothKnownTrue(Context.KnownExecuted, ConditionVal));
VisitForTemporaryDtors(E->getTrueExpr(), ExternallyDestructed, TrueContext);
CFGBlock *TrueBlock = Block;
Block = ConditionBlock;
Succ = ConditionSucc;
TempDtorContext FalseContext(
bothKnownTrue(Context.KnownExecuted, NegatedVal));
VisitForTemporaryDtors(E->getFalseExpr(), ExternallyDestructed, FalseContext);
if (TrueContext.TerminatorExpr && FalseContext.TerminatorExpr) {
InsertTempDtorDecisionBlock(FalseContext, TrueBlock);
} else if (TrueContext.TerminatorExpr) {
Block = TrueBlock;
InsertTempDtorDecisionBlock(TrueContext);
} else {
InsertTempDtorDecisionBlock(FalseContext);
}
return Block;
}
CFGBlock *CFGBuilder::VisitOMPExecutableDirective(OMPExecutableDirective *D,
AddStmtChoice asc) {
if (asc.alwaysAdd(*this, D)) {
autoCreateBlock();
appendStmt(Block, D);
}
// Iterate over all used expression in clauses.
CFGBlock *B = Block;
// Reverse the elements to process them in natural order. Iterators are not
// bidirectional, so we need to create temp vector.
SmallVector<Stmt *, 8> Used(
OMPExecutableDirective::used_clauses_children(D->clauses()));
for (Stmt *S : llvm::reverse(Used)) {
assert(S && "Expected non-null used-in-clause child.");
if (CFGBlock *R = Visit(S))
B = R;
}
// Visit associated structured block if any.
if (!D->isStandaloneDirective())
if (CapturedStmt *CS = D->getInnermostCapturedStmt()) {
Stmt *S = CS->getCapturedStmt();
if (!isa<CompoundStmt>(S))
addLocalScopeAndDtors(S);
if (CFGBlock *R = addStmt(S))
B = R;
}
return B;
}
/// createBlock - Constructs and adds a new CFGBlock to the CFG. The block has
/// no successors or predecessors. If this is the first block created in the
/// CFG, it is automatically set to be the Entry and Exit of the CFG.
CFGBlock *CFG::createBlock() {
bool first_block = begin() == end();
// Create the block.
CFGBlock *Mem = getAllocator().Allocate<CFGBlock>();
new (Mem) CFGBlock(NumBlockIDs++, BlkBVC, this);
Blocks.push_back(Mem, BlkBVC);
// If this is the first block, set it as the Entry and Exit.
if (first_block)
Entry = Exit = &back();
// Return the block.
return &back();
}
/// buildCFG - Constructs a CFG from an AST.
std::unique_ptr<CFG> CFG::buildCFG(const Decl *D, Stmt *Statement,
ASTContext *C, const BuildOptions &BO) {
CFGBuilder Builder(C, BO);
return Builder.buildCFG(D, Statement);
}
bool CFG::isLinear() const {
// Quick path: if we only have the ENTRY block, the EXIT block, and some code
// in between, then we have no room for control flow.
if (size() <= 3)
return true;
// Traverse the CFG until we find a branch.
// TODO: While this should still be very fast,
// maybe we should cache the answer.
llvm::SmallPtrSet<const CFGBlock *, 4> Visited;
const CFGBlock *B = Entry;
while (B != Exit) {
auto IteratorAndFlag = Visited.insert(B);
if (!IteratorAndFlag.second) {
// We looped back to a block that we've already visited. Not linear.
return false;
}
// Iterate over reachable successors.
const CFGBlock *FirstReachableB = nullptr;
for (const CFGBlock::AdjacentBlock &AB : B->succs()) {
if (!AB.isReachable())
continue;
if (FirstReachableB == nullptr) {
FirstReachableB = &*AB;
} else {
// We've encountered a branch. It's not a linear CFG.
return false;
}
}
if (!FirstReachableB) {
// We reached a dead end. EXIT is unreachable. This is linear enough.
return true;
}
// There's only one way to move forward. Proceed.
B = FirstReachableB;
}
// We reached EXIT and found no branches.
return true;
}
const CXXDestructorDecl *
CFGImplicitDtor::getDestructorDecl(ASTContext &astContext) const {
switch (getKind()) {
case CFGElement::Initializer:
case CFGElement::NewAllocator:
case CFGElement::LoopExit:
case CFGElement::LifetimeEnds:
case CFGElement::Statement:
case CFGElement::Constructor:
case CFGElement::CXXRecordTypedCall:
case CFGElement::ScopeBegin:
case CFGElement::ScopeEnd:
llvm_unreachable("getDestructorDecl should only be used with "
"ImplicitDtors");
case CFGElement::AutomaticObjectDtor: {
const VarDecl *var = castAs<CFGAutomaticObjDtor>().getVarDecl();
QualType ty = var->getType();
// FIXME: See CFGBuilder::addLocalScopeForVarDecl.
//
// Lifetime-extending constructs are handled here. This works for a single
// temporary in an initializer expression.
if (ty->isReferenceType()) {
if (const Expr *Init = var->getInit()) {
ty = getReferenceInitTemporaryType(Init);
}
}
while (const ArrayType *arrayType = astContext.getAsArrayType(ty)) {
ty = arrayType->getElementType();
}
// The situation when the type of the lifetime-extending reference
// does not correspond to the type of the object is supposed
// to be handled by now. In particular, 'ty' is now the unwrapped
// record type.
const CXXRecordDecl *classDecl = ty->getAsCXXRecordDecl();
assert(classDecl);
return classDecl->getDestructor();
}
case CFGElement::DeleteDtor: {
const CXXDeleteExpr *DE = castAs<CFGDeleteDtor>().getDeleteExpr();
QualType DTy = DE->getDestroyedType();
DTy = DTy.getNonReferenceType();
const CXXRecordDecl *classDecl =
astContext.getBaseElementType(DTy)->getAsCXXRecordDecl();
return classDecl->getDestructor();
}
case CFGElement::TemporaryDtor: {
const CXXBindTemporaryExpr *bindExpr =
castAs<CFGTemporaryDtor>().getBindTemporaryExpr();
const CXXTemporary *temp = bindExpr->getTemporary();
return temp->getDestructor();
}
case CFGElement::BaseDtor:
case CFGElement::MemberDtor:
// Not yet supported.
return nullptr;
}
llvm_unreachable("getKind() returned bogus value");
}
//===----------------------------------------------------------------------===//
// CFGBlock operations.
//===----------------------------------------------------------------------===//
CFGBlock::AdjacentBlock::AdjacentBlock(CFGBlock *B, bool IsReachable)
: ReachableBlock(IsReachable ? B : nullptr),
UnreachableBlock(!IsReachable ? B : nullptr,
B && IsReachable ? AB_Normal : AB_Unreachable) {}
CFGBlock::AdjacentBlock::AdjacentBlock(CFGBlock *B, CFGBlock *AlternateBlock)
: ReachableBlock(B),
UnreachableBlock(B == AlternateBlock ? nullptr : AlternateBlock,
B == AlternateBlock ? AB_Alternate : AB_Normal) {}
void CFGBlock::addSuccessor(AdjacentBlock Succ,
BumpVectorContext &C) {
if (CFGBlock *B = Succ.getReachableBlock())
B->Preds.push_back(AdjacentBlock(this, Succ.isReachable()), C);
if (CFGBlock *UnreachableB = Succ.getPossiblyUnreachableBlock())
UnreachableB->Preds.push_back(AdjacentBlock(this, false), C);
Succs.push_back(Succ, C);
}
bool CFGBlock::FilterEdge(const CFGBlock::FilterOptions &F,
const CFGBlock *From, const CFGBlock *To) {
if (F.IgnoreNullPredecessors && !From)
return true;
if (To && From && F.IgnoreDefaultsWithCoveredEnums) {
// If the 'To' has no label or is labeled but the label isn't a
// CaseStmt then filter this edge.
if (const SwitchStmt *S =
dyn_cast_or_null<SwitchStmt>(From->getTerminatorStmt())) {
if (S->isAllEnumCasesCovered()) {
const Stmt *L = To->getLabel();
if (!L || !isa<CaseStmt>(L))
return true;
}
}
}
return false;
}
//===----------------------------------------------------------------------===//
// CFG pretty printing
//===----------------------------------------------------------------------===//
namespace {
class StmtPrinterHelper : public PrinterHelper {
using StmtMapTy = llvm::DenseMap<const Stmt *, std::pair<unsigned, unsigned>>;
using DeclMapTy = llvm::DenseMap<const Decl *, std::pair<unsigned, unsigned>>;
StmtMapTy StmtMap;
DeclMapTy DeclMap;
signed currentBlock = 0;
unsigned currStmt = 0;
const LangOptions &LangOpts;
public:
StmtPrinterHelper(const CFG* cfg, const LangOptions &LO)
: LangOpts(LO) {
if (!cfg)
return;
for (CFG::const_iterator I = cfg->begin(), E = cfg->end(); I != E; ++I ) {
unsigned j = 1;
for (CFGBlock::const_iterator BI = (*I)->begin(), BEnd = (*I)->end() ;
BI != BEnd; ++BI, ++j ) {
if (Optional<CFGStmt> SE = BI->getAs<CFGStmt>()) {
const Stmt *stmt= SE->getStmt();
std::pair<unsigned, unsigned> P((*I)->getBlockID(), j);
StmtMap[stmt] = P;
switch (stmt->getStmtClass()) {
case Stmt::DeclStmtClass:
DeclMap[cast<DeclStmt>(stmt)->getSingleDecl()] = P;
break;
case Stmt::IfStmtClass: {
const VarDecl *var = cast<IfStmt>(stmt)->getConditionVariable();
if (var)
DeclMap[var] = P;
break;
}
case Stmt::ForStmtClass: {
const VarDecl *var = cast<ForStmt>(stmt)->getConditionVariable();
if (var)
DeclMap[var] = P;
break;
}
case Stmt::WhileStmtClass: {
const VarDecl *var =
cast<WhileStmt>(stmt)->getConditionVariable();
if (var)
DeclMap[var] = P;
break;
}
case Stmt::SwitchStmtClass: {
const VarDecl *var =
cast<SwitchStmt>(stmt)->getConditionVariable();
if (var)
DeclMap[var] = P;
break;
}
case Stmt::CXXCatchStmtClass: {
const VarDecl *var =
cast<CXXCatchStmt>(stmt)->getExceptionDecl();
if (var)
DeclMap[var] = P;
break;
}
default:
break;
}
}
}
}
}
~StmtPrinterHelper() override = default;
const LangOptions &getLangOpts() const { return LangOpts; }
void setBlockID(signed i) { currentBlock = i; }
void setStmtID(unsigned i) { currStmt = i; }
bool handledStmt(Stmt *S, raw_ostream &OS) override {
StmtMapTy::iterator I = StmtMap.find(S);
if (I == StmtMap.end())
return false;
if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock
&& I->second.second == currStmt) {
return false;
}
OS << "[B" << I->second.first << "." << I->second.second << "]";
return true;
}
bool handleDecl(const Decl *D, raw_ostream &OS) {
DeclMapTy::iterator I = DeclMap.find(D);
if (I == DeclMap.end())
return false;
if (currentBlock >= 0 && I->second.first == (unsigned) currentBlock
&& I->second.second == currStmt) {
return false;
}
OS << "[B" << I->second.first << "." << I->second.second << "]";
return true;
}
};
class CFGBlockTerminatorPrint
: public StmtVisitor<CFGBlockTerminatorPrint,void> {
raw_ostream &OS;
StmtPrinterHelper* Helper;
PrintingPolicy Policy;
public:
CFGBlockTerminatorPrint(raw_ostream &os, StmtPrinterHelper* helper,
const PrintingPolicy &Policy)
: OS(os), Helper(helper), Policy(Policy) {
this->Policy.IncludeNewlines = false;
}
void VisitIfStmt(IfStmt *I) {
OS << "if ";
if (Stmt *C = I->getCond())
C->printPretty(OS, Helper, Policy);
}
// Default case.
void VisitStmt(Stmt *Terminator) {
Terminator->printPretty(OS, Helper, Policy);
}
void VisitDeclStmt(DeclStmt *DS) {
VarDecl *VD = cast<VarDecl>(DS->getSingleDecl());
OS << "static init " << VD->getName();
}
void VisitForStmt(ForStmt *F) {
OS << "for (" ;
if (F->getInit())
OS << "...";
OS << "; ";
if (Stmt *C = F->getCond())
C->printPretty(OS, Helper, Policy);
OS << "; ";
if (F->getInc())
OS << "...";
OS << ")";
}
void VisitWhileStmt(WhileStmt *W) {
OS << "while " ;
if (Stmt *C = W->getCond())
C->printPretty(OS, Helper, Policy);
}
void VisitDoStmt(DoStmt *D) {
OS << "do ... while ";
if (Stmt *C = D->getCond())
C->printPretty(OS, Helper, Policy);
}
void VisitSwitchStmt(SwitchStmt *Terminator) {
OS << "switch ";
Terminator->getCond()->printPretty(OS, Helper, Policy);
}
void VisitCXXTryStmt(CXXTryStmt *CS) {
OS << "try ...";
}
void VisitSEHTryStmt(SEHTryStmt *CS) {
OS << "__try ...";
}
void VisitAbstractConditionalOperator(AbstractConditionalOperator* C) {
if (Stmt *Cond = C->getCond())
Cond->printPretty(OS, Helper, Policy);
OS << " ? ... : ...";
}
void VisitChooseExpr(ChooseExpr *C) {
OS << "__builtin_choose_expr( ";
if (Stmt *Cond = C->getCond())
Cond->printPretty(OS, Helper, Policy);
OS << " )";
}
void VisitIndirectGotoStmt(IndirectGotoStmt *I) {
OS << "goto *";
if (Stmt *T = I->getTarget())
T->printPretty(OS, Helper, Policy);
}
void VisitBinaryOperator(BinaryOperator* B) {
if (!B->isLogicalOp()) {
VisitExpr(B);
return;
}
if (B->getLHS())
B->getLHS()->printPretty(OS, Helper, Policy);
switch (B->getOpcode()) {
case BO_LOr:
OS << " || ...";
return;
case BO_LAnd:
OS << " && ...";
return;
default:
llvm_unreachable("Invalid logical operator.");
}
}
void VisitExpr(Expr *E) {
E->printPretty(OS, Helper, Policy);
}
public:
void print(CFGTerminator T) {
switch (T.getKind()) {
case CFGTerminator::StmtBranch:
Visit(T.getStmt());
break;
case CFGTerminator::TemporaryDtorsBranch:
OS << "(Temp Dtor) ";
Visit(T.getStmt());
break;
case CFGTerminator::VirtualBaseBranch:
OS << "(See if most derived ctor has already initialized vbases)";
break;
}
}
};
} // namespace
static void print_initializer(raw_ostream &OS, StmtPrinterHelper &Helper,
const CXXCtorInitializer *I) {
if (I->isBaseInitializer())
OS << I->getBaseClass()->getAsCXXRecordDecl()->getName();
else if (I->isDelegatingInitializer())
OS << I->getTypeSourceInfo()->getType()->getAsCXXRecordDecl()->getName();
else
OS << I->getAnyMember()->getName();
OS << "(";
if (Expr *IE = I->getInit())
IE->printPretty(OS, &Helper, PrintingPolicy(Helper.getLangOpts()));
OS << ")";
if (I->isBaseInitializer())
OS << " (Base initializer)";
else if (I->isDelegatingInitializer())
OS << " (Delegating initializer)";
else
OS << " (Member initializer)";
}
static void print_construction_context(raw_ostream &OS,
StmtPrinterHelper &Helper,
const ConstructionContext *CC) {
SmallVector<const Stmt *, 3> Stmts;
switch (CC->getKind()) {
case ConstructionContext::SimpleConstructorInitializerKind: {
OS << ", ";
const auto *SICC = cast<SimpleConstructorInitializerConstructionContext>(CC);
print_initializer(OS, Helper, SICC->getCXXCtorInitializer());
return;
}
case ConstructionContext::CXX17ElidedCopyConstructorInitializerKind: {
OS << ", ";
const auto *CICC =
cast<CXX17ElidedCopyConstructorInitializerConstructionContext>(CC);
print_initializer(OS, Helper, CICC->getCXXCtorInitializer());
Stmts.push_back(CICC->getCXXBindTemporaryExpr());
break;
}
case ConstructionContext::SimpleVariableKind: {
const auto *SDSCC = cast<SimpleVariableConstructionContext>(CC);
Stmts.push_back(SDSCC->getDeclStmt());
break;
}
case ConstructionContext::CXX17ElidedCopyVariableKind: {
const auto *CDSCC = cast<CXX17ElidedCopyVariableConstructionContext>(CC);
Stmts.push_back(CDSCC->getDeclStmt());
Stmts.push_back(CDSCC->getCXXBindTemporaryExpr());
break;
}
case ConstructionContext::NewAllocatedObjectKind: {
const auto *NECC = cast<NewAllocatedObjectConstructionContext>(CC);
Stmts.push_back(NECC->getCXXNewExpr());
break;
}
case ConstructionContext::SimpleReturnedValueKind: {
const auto *RSCC = cast<SimpleReturnedValueConstructionContext>(CC);
Stmts.push_back(RSCC->getReturnStmt());
break;
}
case ConstructionContext::CXX17ElidedCopyReturnedValueKind: {
const auto *RSCC =
cast<CXX17ElidedCopyReturnedValueConstructionContext>(CC);
Stmts.push_back(RSCC->getReturnStmt());
Stmts.push_back(RSCC->getCXXBindTemporaryExpr());
break;
}
case ConstructionContext::SimpleTemporaryObjectKind: {
const auto *TOCC = cast<SimpleTemporaryObjectConstructionContext>(CC);
Stmts.push_back(TOCC->getCXXBindTemporaryExpr());
Stmts.push_back(TOCC->getMaterializedTemporaryExpr());
break;
}
case ConstructionContext::ElidedTemporaryObjectKind: {
const auto *TOCC = cast<ElidedTemporaryObjectConstructionContext>(CC);
Stmts.push_back(TOCC->getCXXBindTemporaryExpr());
Stmts.push_back(TOCC->getMaterializedTemporaryExpr());
Stmts.push_back(TOCC->getConstructorAfterElision());
break;
}
case ConstructionContext::ArgumentKind: {
const auto *ACC = cast<ArgumentConstructionContext>(CC);
if (const Stmt *BTE = ACC->getCXXBindTemporaryExpr()) {
OS << ", ";
Helper.handledStmt(const_cast<Stmt *>(BTE), OS);
}
OS << ", ";
Helper.handledStmt(const_cast<Expr *>(ACC->getCallLikeExpr()), OS);
OS << "+" << ACC->getIndex();
return;
}
}
for (auto I: Stmts)
if (I) {
OS << ", ";
Helper.handledStmt(const_cast<Stmt *>(I), OS);
}
}
static void print_elem(raw_ostream &OS, StmtPrinterHelper &Helper,
const CFGElement &E);
void CFGElement::dumpToStream(llvm::raw_ostream &OS) const {
StmtPrinterHelper Helper(nullptr, {});
print_elem(OS, Helper, *this);
}
static void print_elem(raw_ostream &OS, StmtPrinterHelper &Helper,
const CFGElement &E) {
switch (E.getKind()) {
case CFGElement::Kind::Statement:
case CFGElement::Kind::CXXRecordTypedCall:
case CFGElement::Kind::Constructor: {
CFGStmt CS = E.castAs<CFGStmt>();
const Stmt *S = CS.getStmt();
assert(S != nullptr && "Expecting non-null Stmt");
// special printing for statement-expressions.
if (const StmtExpr *SE = dyn_cast<StmtExpr>(S)) {
const CompoundStmt *Sub = SE->getSubStmt();
auto Children = Sub->children();
if (Children.begin() != Children.end()) {
OS << "({ ... ; ";
Helper.handledStmt(*SE->getSubStmt()->body_rbegin(),OS);
OS << " })\n";
return;
}
}
// special printing for comma expressions.
if (const BinaryOperator* B = dyn_cast<BinaryOperator>(S)) {
if (B->getOpcode() == BO_Comma) {
OS << "... , ";
Helper.handledStmt(B->getRHS(),OS);
OS << '\n';
return;
}
}
S->printPretty(OS, &Helper, PrintingPolicy(Helper.getLangOpts()));
if (auto VTC = E.getAs<CFGCXXRecordTypedCall>()) {
if (isa<CXXOperatorCallExpr>(S))
OS << " (OperatorCall)";
OS << " (CXXRecordTypedCall";
print_construction_context(OS, Helper, VTC->getConstructionContext());
OS << ")";
} else if (isa<CXXOperatorCallExpr>(S)) {
OS << " (OperatorCall)";
} else if (isa<CXXBindTemporaryExpr>(S)) {
OS << " (BindTemporary)";
} else if (const CXXConstructExpr *CCE = dyn_cast<CXXConstructExpr>(S)) {
OS << " (CXXConstructExpr";
if (Optional<CFGConstructor> CE = E.getAs<CFGConstructor>()) {
print_construction_context(OS, Helper, CE->getConstructionContext());
}
OS << ", " << CCE->getType().getAsString() << ")";
} else if (const CastExpr *CE = dyn_cast<CastExpr>(S)) {
OS << " (" << CE->getStmtClassName() << ", "
<< CE->getCastKindName()
<< ", " << CE->getType().getAsString()
<< ")";
}
// Expressions need a newline.
if (isa<Expr>(S))
OS << '\n';
break;
}
case CFGElement::Kind::Initializer:
print_initializer(OS, Helper, E.castAs<CFGInitializer>().getInitializer());
OS << '\n';
break;
case CFGElement::Kind::AutomaticObjectDtor: {
CFGAutomaticObjDtor DE = E.castAs<CFGAutomaticObjDtor>();
const VarDecl *VD = DE.getVarDecl();
Helper.handleDecl(VD, OS);
QualType T = VD->getType();
if (T->isReferenceType())
T = getReferenceInitTemporaryType(VD->getInit(), nullptr);
OS << ".~";
T.getUnqualifiedType().print(OS, PrintingPolicy(Helper.getLangOpts()));
OS << "() (Implicit destructor)\n";
break;
}
case CFGElement::Kind::LifetimeEnds:
Helper.handleDecl(E.castAs<CFGLifetimeEnds>().getVarDecl(), OS);
OS << " (Lifetime ends)\n";
break;
case CFGElement::Kind::LoopExit:
OS << E.castAs<CFGLoopExit>().getLoopStmt()->getStmtClassName() << " (LoopExit)\n";
break;
case CFGElement::Kind::ScopeBegin:
OS << "CFGScopeBegin(";
if (const VarDecl *VD = E.castAs<CFGScopeBegin>().getVarDecl())
OS << VD->getQualifiedNameAsString();
OS << ")\n";
break;
case CFGElement::Kind::ScopeEnd:
OS << "CFGScopeEnd(";
if (const VarDecl *VD = E.castAs<CFGScopeEnd>().getVarDecl())
OS << VD->getQualifiedNameAsString();
OS << ")\n";
break;
case CFGElement::Kind::NewAllocator:
OS << "CFGNewAllocator(";
if (const CXXNewExpr *AllocExpr = E.castAs<CFGNewAllocator>().getAllocatorExpr())
AllocExpr->getType().print(OS, PrintingPolicy(Helper.getLangOpts()));
OS << ")\n";
break;
case CFGElement::Kind::DeleteDtor: {
CFGDeleteDtor DE = E.castAs<CFGDeleteDtor>();
const CXXRecordDecl *RD = DE.getCXXRecordDecl();
if (!RD)
return;
CXXDeleteExpr *DelExpr =
const_cast<CXXDeleteExpr*>(DE.getDeleteExpr());
Helper.handledStmt(cast<Stmt>(DelExpr->getArgument()), OS);
OS << "->~" << RD->getName().str() << "()";
OS << " (Implicit destructor)\n";
break;
}
case CFGElement::Kind::BaseDtor: {
const CXXBaseSpecifier *BS = E.castAs<CFGBaseDtor>().getBaseSpecifier();
OS << "~" << BS->getType()->getAsCXXRecordDecl()->getName() << "()";
OS << " (Base object destructor)\n";
break;
}
case CFGElement::Kind::MemberDtor: {
const FieldDecl *FD = E.castAs<CFGMemberDtor>().getFieldDecl();
const Type *T = FD->getType()->getBaseElementTypeUnsafe();
OS << "this->" << FD->getName();
OS << ".~" << T->getAsCXXRecordDecl()->getName() << "()";
OS << " (Member object destructor)\n";
break;
}
case CFGElement::Kind::TemporaryDtor: {
const CXXBindTemporaryExpr *BT = E.castAs<CFGTemporaryDtor>().getBindTemporaryExpr();
OS << "~";
BT->getType().print(OS, PrintingPolicy(Helper.getLangOpts()));
OS << "() (Temporary object destructor)\n";
break;
}
}
}
static void print_block(raw_ostream &OS, const CFG* cfg,
const CFGBlock &B,
StmtPrinterHelper &Helper, bool print_edges,
bool ShowColors) {
Helper.setBlockID(B.getBlockID());
// Print the header.
if (ShowColors)
OS.changeColor(raw_ostream::YELLOW, true);
OS << "\n [B" << B.getBlockID();
if (&B == &cfg->getEntry())
OS << " (ENTRY)]\n";
else if (&B == &cfg->getExit())
OS << " (EXIT)]\n";
else if (&B == cfg->getIndirectGotoBlock())
OS << " (INDIRECT GOTO DISPATCH)]\n";
else if (B.hasNoReturnElement())
OS << " (NORETURN)]\n";
else
OS << "]\n";
if (ShowColors)
OS.resetColor();
// Print the label of this block.
if (Stmt *Label = const_cast<Stmt*>(B.getLabel())) {
if (print_edges)
OS << " ";
if (LabelStmt *L = dyn_cast<LabelStmt>(Label))
OS << L->getName();
else if (CaseStmt *C = dyn_cast<CaseStmt>(Label)) {
OS << "case ";
if (C->getLHS())
C->getLHS()->printPretty(OS, &Helper,
PrintingPolicy(Helper.getLangOpts()));
if (C->getRHS()) {
OS << " ... ";
C->getRHS()->printPretty(OS, &Helper,
PrintingPolicy(Helper.getLangOpts()));
}
} else if (isa<DefaultStmt>(Label))
OS << "default";
else if (CXXCatchStmt *CS = dyn_cast<CXXCatchStmt>(Label)) {
OS << "catch (";
if (CS->getExceptionDecl())
CS->getExceptionDecl()->print(OS, PrintingPolicy(Helper.getLangOpts()),
0);
else
OS << "...";
OS << ")";
} else if (SEHExceptStmt *ES = dyn_cast<SEHExceptStmt>(Label)) {
OS << "__except (";
ES->getFilterExpr()->printPretty(OS, &Helper,
PrintingPolicy(Helper.getLangOpts()), 0);
OS << ")";
} else
llvm_unreachable("Invalid label statement in CFGBlock.");
OS << ":\n";
}
// Iterate through the statements in the block and print them.
unsigned j = 1;
for (CFGBlock::const_iterator I = B.begin(), E = B.end() ;
I != E ; ++I, ++j ) {
// Print the statement # in the basic block and the statement itself.
if (print_edges)
OS << " ";
OS << llvm::format("%3d", j) << ": ";
Helper.setStmtID(j);
print_elem(OS, Helper, *I);
}
// Print the terminator of this block.
if (B.getTerminator().isValid()) {
if (ShowColors)
OS.changeColor(raw_ostream::GREEN);
OS << " T: ";
Helper.setBlockID(-1);
PrintingPolicy PP(Helper.getLangOpts());
CFGBlockTerminatorPrint TPrinter(OS, &Helper, PP);
TPrinter.print(B.getTerminator());
OS << '\n';
if (ShowColors)
OS.resetColor();
}
if (print_edges) {
// Print the predecessors of this block.
if (!B.pred_empty()) {
const raw_ostream::Colors Color = raw_ostream::BLUE;
if (ShowColors)
OS.changeColor(Color);
OS << " Preds " ;
if (ShowColors)
OS.resetColor();
OS << '(' << B.pred_size() << "):";
unsigned i = 0;
if (ShowColors)
OS.changeColor(Color);
for (CFGBlock::const_pred_iterator I = B.pred_begin(), E = B.pred_end();
I != E; ++I, ++i) {
if (i % 10 == 8)
OS << "\n ";
CFGBlock *B = *I;
bool Reachable = true;
if (!B) {
Reachable = false;
B = I->getPossiblyUnreachableBlock();
}
OS << " B" << B->getBlockID();
if (!Reachable)
OS << "(Unreachable)";
}
if (ShowColors)
OS.resetColor();
OS << '\n';
}
// Print the successors of this block.
if (!B.succ_empty()) {
const raw_ostream::Colors Color = raw_ostream::MAGENTA;
if (ShowColors)
OS.changeColor(Color);
OS << " Succs ";
if (ShowColors)
OS.resetColor();
OS << '(' << B.succ_size() << "):";
unsigned i = 0;
if (ShowColors)
OS.changeColor(Color);
for (CFGBlock::const_succ_iterator I = B.succ_begin(), E = B.succ_end();
I != E; ++I, ++i) {
if (i % 10 == 8)
OS << "\n ";
CFGBlock *B = *I;
bool Reachable = true;
if (!B) {
Reachable = false;
B = I->getPossiblyUnreachableBlock();
}
if (B) {
OS << " B" << B->getBlockID();
if (!Reachable)
OS << "(Unreachable)";
}
else {
OS << " NULL";
}
}
if (ShowColors)
OS.resetColor();
OS << '\n';
}
}
}
/// dump - A simple pretty printer of a CFG that outputs to stderr.
void CFG::dump(const LangOptions &LO, bool ShowColors) const {
print(llvm::errs(), LO, ShowColors);
}
/// print - A simple pretty printer of a CFG that outputs to an ostream.
void CFG::print(raw_ostream &OS, const LangOptions &LO, bool ShowColors) const {
StmtPrinterHelper Helper(this, LO);
// Print the entry block.
print_block(OS, this, getEntry(), Helper, true, ShowColors);
// Iterate through the CFGBlocks and print them one by one.
for (const_iterator I = Blocks.begin(), E = Blocks.end() ; I != E ; ++I) {
// Skip the entry block, because we already printed it.
if (&(**I) == &getEntry() || &(**I) == &getExit())
continue;
print_block(OS, this, **I, Helper, true, ShowColors);
}
// Print the exit block.
print_block(OS, this, getExit(), Helper, true, ShowColors);
OS << '\n';
OS.flush();
}
size_t CFGBlock::getIndexInCFG() const {
return llvm::find(*getParent(), this) - getParent()->begin();
}
/// dump - A simply pretty printer of a CFGBlock that outputs to stderr.
void CFGBlock::dump(const CFG* cfg, const LangOptions &LO,
bool ShowColors) const {
print(llvm::errs(), cfg, LO, ShowColors);
}
LLVM_DUMP_METHOD void CFGBlock::dump() const {
dump(getParent(), LangOptions(), false);
}
/// print - A simple pretty printer of a CFGBlock that outputs to an ostream.
/// Generally this will only be called from CFG::print.
void CFGBlock::print(raw_ostream &OS, const CFG* cfg,
const LangOptions &LO, bool ShowColors) const {
StmtPrinterHelper Helper(cfg, LO);
print_block(OS, cfg, *this, Helper, true, ShowColors);
OS << '\n';
}
/// printTerminator - A simple pretty printer of the terminator of a CFGBlock.
void CFGBlock::printTerminator(raw_ostream &OS,
const LangOptions &LO) const {
CFGBlockTerminatorPrint TPrinter(OS, nullptr, PrintingPolicy(LO));
TPrinter.print(getTerminator());
}
/// printTerminatorJson - Pretty-prints the terminator in JSON format.
void CFGBlock::printTerminatorJson(raw_ostream &Out, const LangOptions &LO,
bool AddQuotes) const {
std::string Buf;
llvm::raw_string_ostream TempOut(Buf);
printTerminator(TempOut, LO);
Out << JsonFormat(TempOut.str(), AddQuotes);
}
// Returns true if by simply looking at the block, we can be sure that it
// results in a sink during analysis. This is useful to know when the analysis
// was interrupted, and we try to figure out if it would sink eventually.
// There may be many more reasons why a sink would appear during analysis
// (eg. checkers may generate sinks arbitrarily), but here we only consider
// sinks that would be obvious by looking at the CFG.
static bool isImmediateSinkBlock(const CFGBlock *Blk) {
if (Blk->hasNoReturnElement())
return true;
// FIXME: Throw-expressions are currently generating sinks during analysis:
// they're not supported yet, and also often used for actually terminating
// the program. So we should treat them as sinks in this analysis as well,
// at least for now, but once we have better support for exceptions,
// we'd need to carefully handle the case when the throw is being
// immediately caught.
if (std::any_of(Blk->begin(), Blk->end(), [](const CFGElement &Elm) {
if (Optional<CFGStmt> StmtElm = Elm.getAs<CFGStmt>())
if (isa<CXXThrowExpr>(StmtElm->getStmt()))
return true;
return false;
}))
return true;
return false;
}
bool CFGBlock::isInevitablySinking() const {
const CFG &Cfg = *getParent();
const CFGBlock *StartBlk = this;
if (isImmediateSinkBlock(StartBlk))
return true;
llvm::SmallVector<const CFGBlock *, 32> DFSWorkList;
llvm::SmallPtrSet<const CFGBlock *, 32> Visited;
DFSWorkList.push_back(StartBlk);
while (!DFSWorkList.empty()) {
const CFGBlock *Blk = DFSWorkList.back();
DFSWorkList.pop_back();
Visited.insert(Blk);
// If at least one path reaches the CFG exit, it means that control is
// returned to the caller. For now, say that we are not sure what
// happens next. If necessary, this can be improved to analyze
// the parent StackFrameContext's call site in a similar manner.
if (Blk == &Cfg.getExit())
return false;
for (const auto &Succ : Blk->succs()) {
if (const CFGBlock *SuccBlk = Succ.getReachableBlock()) {
if (!isImmediateSinkBlock(SuccBlk) && !Visited.count(SuccBlk)) {
// If the block has reachable child blocks that aren't no-return,
// add them to the worklist.
DFSWorkList.push_back(SuccBlk);
}
}
}
}
// Nothing reached the exit. It can only mean one thing: there's no return.
return true;
}
const Expr *CFGBlock::getLastCondition() const {
// If the terminator is a temporary dtor or a virtual base, etc, we can't
// retrieve a meaningful condition, bail out.
if (Terminator.getKind() != CFGTerminator::StmtBranch)
return nullptr;
// Also, if this method was called on a block that doesn't have 2 successors,
// this block doesn't have retrievable condition.
if (succ_size() < 2)
return nullptr;
// FIXME: Is there a better condition expression we can return in this case?
if (size() == 0)
return nullptr;
auto StmtElem = rbegin()->getAs<CFGStmt>();
if (!StmtElem)
return nullptr;
const Stmt *Cond = StmtElem->getStmt();
if (isa<ObjCForCollectionStmt>(Cond))
return nullptr;
// Only ObjCForCollectionStmt is known not to be a non-Expr terminator, hence
// the cast<>.
return cast<Expr>(Cond)->IgnoreParens();
}
Stmt *CFGBlock::getTerminatorCondition(bool StripParens) {
Stmt *Terminator = getTerminatorStmt();
if (!Terminator)
return nullptr;
Expr *E = nullptr;
switch (Terminator->getStmtClass()) {
default:
break;
case Stmt::CXXForRangeStmtClass:
E = cast<CXXForRangeStmt>(Terminator)->getCond();
break;
case Stmt::ForStmtClass:
E = cast<ForStmt>(Terminator)->getCond();
break;
case Stmt::WhileStmtClass:
E = cast<WhileStmt>(Terminator)->getCond();
break;
case Stmt::DoStmtClass:
E = cast<DoStmt>(Terminator)->getCond();
break;
case Stmt::IfStmtClass:
E = cast<IfStmt>(Terminator)->getCond();
break;
case Stmt::ChooseExprClass:
E = cast<ChooseExpr>(Terminator)->getCond();
break;
case Stmt::IndirectGotoStmtClass:
E = cast<IndirectGotoStmt>(Terminator)->getTarget();
break;
case Stmt::SwitchStmtClass:
E = cast<SwitchStmt>(Terminator)->getCond();
break;
case Stmt::BinaryConditionalOperatorClass:
E = cast<BinaryConditionalOperator>(Terminator)->getCond();
break;
case Stmt::ConditionalOperatorClass:
E = cast<ConditionalOperator>(Terminator)->getCond();
break;
case Stmt::BinaryOperatorClass: // '&&' and '||'
E = cast<BinaryOperator>(Terminator)->getLHS();
break;
case Stmt::ObjCForCollectionStmtClass:
return Terminator;
}
if (!StripParens)
return E;
return E ? E->IgnoreParens() : nullptr;
}
//===----------------------------------------------------------------------===//
// CFG Graphviz Visualization
//===----------------------------------------------------------------------===//
#ifndef NDEBUG
static StmtPrinterHelper* GraphHelper;
#endif
void CFG::viewCFG(const LangOptions &LO) const {
#ifndef NDEBUG
StmtPrinterHelper H(this, LO);
GraphHelper = &H;
llvm::ViewGraph(this,"CFG");
GraphHelper = nullptr;
#endif
}
namespace llvm {
template<>
struct DOTGraphTraits<const CFG*> : public DefaultDOTGraphTraits {
DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
static std::string getNodeLabel(const CFGBlock *Node, const CFG* Graph) {
#ifndef NDEBUG
std::string OutSStr;
llvm::raw_string_ostream Out(OutSStr);
print_block(Out,Graph, *Node, *GraphHelper, false, false);
std::string& OutStr = Out.str();
if (OutStr[0] == '\n') OutStr.erase(OutStr.begin());
// Process string output to make it nicer...
for (unsigned i = 0; i != OutStr.length(); ++i)
if (OutStr[i] == '\n') { // Left justify
OutStr[i] = '\\';
OutStr.insert(OutStr.begin()+i+1, 'l');
}
return OutStr;
#else
return {};
#endif
}
};
} // namespace llvm
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