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llvm / clang / refs/heads/release_27 / . / lib / AST / ExprConstant.cpp
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//===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Expr constant evaluator.
//
//===----------------------------------------------------------------------===//
#include "clang/AST/APValue.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CharUnits.h"
#include "clang/AST/RecordLayout.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/AST/ASTDiagnostic.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/TargetInfo.h"
#include "llvm/ADT/SmallString.h"
#include <cstring>
using namespace clang;
using llvm::APSInt;
using llvm::APFloat;
/// EvalInfo - This is a private struct used by the evaluator to capture
/// information about a subexpression as it is folded. It retains information
/// about the AST context, but also maintains information about the folded
/// expression.
///
/// If an expression could be evaluated, it is still possible it is not a C
/// "integer constant expression" or constant expression. If not, this struct
/// captures information about how and why not.
///
/// One bit of information passed *into* the request for constant folding
/// indicates whether the subexpression is "evaluated" or not according to C
/// rules. For example, the RHS of (0 && foo()) is not evaluated. We can
/// evaluate the expression regardless of what the RHS is, but C only allows
/// certain things in certain situations.
struct EvalInfo {
ASTContext &Ctx;
/// EvalResult - Contains information about the evaluation.
Expr::EvalResult &EvalResult;
/// AnyLValue - Stack based LValue results are not discarded.
bool AnyLValue;
EvalInfo(ASTContext &ctx, Expr::EvalResult& evalresult,
bool anylvalue = false)
: Ctx(ctx), EvalResult(evalresult), AnyLValue(anylvalue) {}
};
static bool EvaluateLValue(const Expr *E, APValue &Result, EvalInfo &Info);
static bool EvaluatePointer(const Expr *E, APValue &Result, EvalInfo &Info);
static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info);
static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result,
EvalInfo &Info);
static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info);
static bool EvaluateComplex(const Expr *E, APValue &Result, EvalInfo &Info);
//===----------------------------------------------------------------------===//
// Misc utilities
//===----------------------------------------------------------------------===//
static bool EvalPointerValueAsBool(APValue& Value, bool& Result) {
// FIXME: Is this accurate for all kinds of bases? If not, what would
// the check look like?
Result = Value.getLValueBase() || !Value.getLValueOffset().isZero();
return true;
}
static bool HandleConversionToBool(const Expr* E, bool& Result,
EvalInfo &Info) {
if (E->getType()->isIntegralType()) {
APSInt IntResult;
if (!EvaluateInteger(E, IntResult, Info))
return false;
Result = IntResult != 0;
return true;
} else if (E->getType()->isRealFloatingType()) {
APFloat FloatResult(0.0);
if (!EvaluateFloat(E, FloatResult, Info))
return false;
Result = !FloatResult.isZero();
return true;
} else if (E->getType()->hasPointerRepresentation()) {
APValue PointerResult;
if (!EvaluatePointer(E, PointerResult, Info))
return false;
return EvalPointerValueAsBool(PointerResult, Result);
} else if (E->getType()->isAnyComplexType()) {
APValue ComplexResult;
if (!EvaluateComplex(E, ComplexResult, Info))
return false;
if (ComplexResult.isComplexFloat()) {
Result = !ComplexResult.getComplexFloatReal().isZero() ||
!ComplexResult.getComplexFloatImag().isZero();
} else {
Result = ComplexResult.getComplexIntReal().getBoolValue() ||
ComplexResult.getComplexIntImag().getBoolValue();
}
return true;
}
return false;
}
static APSInt HandleFloatToIntCast(QualType DestType, QualType SrcType,
APFloat &Value, ASTContext &Ctx) {
unsigned DestWidth = Ctx.getIntWidth(DestType);
// Determine whether we are converting to unsigned or signed.
bool DestSigned = DestType->isSignedIntegerType();
// FIXME: Warning for overflow.
uint64_t Space[4];
bool ignored;
(void)Value.convertToInteger(Space, DestWidth, DestSigned,
llvm::APFloat::rmTowardZero, &ignored);
return APSInt(llvm::APInt(DestWidth, 4, Space), !DestSigned);
}
static APFloat HandleFloatToFloatCast(QualType DestType, QualType SrcType,
APFloat &Value, ASTContext &Ctx) {
bool ignored;
APFloat Result = Value;
Result.convert(Ctx.getFloatTypeSemantics(DestType),
APFloat::rmNearestTiesToEven, &ignored);
return Result;
}
static APSInt HandleIntToIntCast(QualType DestType, QualType SrcType,
APSInt &Value, ASTContext &Ctx) {
unsigned DestWidth = Ctx.getIntWidth(DestType);
APSInt Result = Value;
// Figure out if this is a truncate, extend or noop cast.
// If the input is signed, do a sign extend, noop, or truncate.
Result.extOrTrunc(DestWidth);
Result.setIsUnsigned(DestType->isUnsignedIntegerType());
return Result;
}
static APFloat HandleIntToFloatCast(QualType DestType, QualType SrcType,
APSInt &Value, ASTContext &Ctx) {
APFloat Result(Ctx.getFloatTypeSemantics(DestType), 1);
Result.convertFromAPInt(Value, Value.isSigned(),
APFloat::rmNearestTiesToEven);
return Result;
}
namespace {
class HasSideEffect
: public StmtVisitor<HasSideEffect, bool> {
EvalInfo &Info;
public:
HasSideEffect(EvalInfo &info) : Info(info) {}
// Unhandled nodes conservatively default to having side effects.
bool VisitStmt(Stmt *S) {
return true;
}
bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
bool VisitDeclRefExpr(DeclRefExpr *E) {
if (Info.Ctx.getCanonicalType(E->getType()).isVolatileQualified())
return true;
return false;
}
// We don't want to evaluate BlockExprs multiple times, as they generate
// a ton of code.
bool VisitBlockExpr(BlockExpr *E) { return true; }
bool VisitPredefinedExpr(PredefinedExpr *E) { return false; }
bool VisitCompoundLiteralExpr(CompoundLiteralExpr *E)
{ return Visit(E->getInitializer()); }
bool VisitMemberExpr(MemberExpr *E) { return Visit(E->getBase()); }
bool VisitIntegerLiteral(IntegerLiteral *E) { return false; }
bool VisitFloatingLiteral(FloatingLiteral *E) { return false; }
bool VisitStringLiteral(StringLiteral *E) { return false; }
bool VisitCharacterLiteral(CharacterLiteral *E) { return false; }
bool VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E) { return false; }
bool VisitArraySubscriptExpr(ArraySubscriptExpr *E)
{ return Visit(E->getLHS()) || Visit(E->getRHS()); }
bool VisitChooseExpr(ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
bool VisitCastExpr(CastExpr *E) { return Visit(E->getSubExpr()); }
bool VisitBinAssign(BinaryOperator *E) { return true; }
bool VisitCompoundAssignOperator(BinaryOperator *E) { return true; }
bool VisitBinaryOperator(BinaryOperator *E)
{ return Visit(E->getLHS()) || Visit(E->getRHS()); }
bool VisitUnaryPreInc(UnaryOperator *E) { return true; }
bool VisitUnaryPostInc(UnaryOperator *E) { return true; }
bool VisitUnaryPreDec(UnaryOperator *E) { return true; }
bool VisitUnaryPostDec(UnaryOperator *E) { return true; }
bool VisitUnaryDeref(UnaryOperator *E) {
if (Info.Ctx.getCanonicalType(E->getType()).isVolatileQualified())
return true;
return Visit(E->getSubExpr());
}
bool VisitUnaryOperator(UnaryOperator *E) { return Visit(E->getSubExpr()); }
};
} // end anonymous namespace
//===----------------------------------------------------------------------===//
// LValue Evaluation
//===----------------------------------------------------------------------===//
namespace {
class LValueExprEvaluator
: public StmtVisitor<LValueExprEvaluator, APValue> {
EvalInfo &Info;
public:
LValueExprEvaluator(EvalInfo &info) : Info(info) {}
APValue VisitStmt(Stmt *S) {
return APValue();
}
APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
APValue VisitDeclRefExpr(DeclRefExpr *E);
APValue VisitPredefinedExpr(PredefinedExpr *E) { return APValue(E); }
APValue VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
APValue VisitMemberExpr(MemberExpr *E);
APValue VisitStringLiteral(StringLiteral *E) { return APValue(E); }
APValue VisitObjCEncodeExpr(ObjCEncodeExpr *E) { return APValue(E); }
APValue VisitArraySubscriptExpr(ArraySubscriptExpr *E);
APValue VisitUnaryDeref(UnaryOperator *E);
APValue VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitChooseExpr(const ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
APValue VisitCastExpr(CastExpr *E) {
switch (E->getCastKind()) {
default:
return APValue();
case CastExpr::CK_NoOp:
return Visit(E->getSubExpr());
}
}
// FIXME: Missing: __real__, __imag__
};
} // end anonymous namespace
static bool EvaluateLValue(const Expr* E, APValue& Result, EvalInfo &Info) {
Result = LValueExprEvaluator(Info).Visit(const_cast<Expr*>(E));
return Result.isLValue();
}
APValue LValueExprEvaluator::VisitDeclRefExpr(DeclRefExpr *E) {
if (isa<FunctionDecl>(E->getDecl())) {
return APValue(E);
} else if (VarDecl* VD = dyn_cast<VarDecl>(E->getDecl())) {
if (!Info.AnyLValue && !VD->hasGlobalStorage())
return APValue();
if (!VD->getType()->isReferenceType())
return APValue(E);
// FIXME: Check whether VD might be overridden!
if (const Expr *Init = VD->getAnyInitializer())
return Visit(const_cast<Expr *>(Init));
}
return APValue();
}
APValue LValueExprEvaluator::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
if (!Info.AnyLValue && !E->isFileScope())
return APValue();
return APValue(E);
}
APValue LValueExprEvaluator::VisitMemberExpr(MemberExpr *E) {
APValue result;
QualType Ty;
if (E->isArrow()) {
if (!EvaluatePointer(E->getBase(), result, Info))
return APValue();
Ty = E->getBase()->getType()->getAs<PointerType>()->getPointeeType();
} else {
result = Visit(E->getBase());
if (result.isUninit())
return APValue();
Ty = E->getBase()->getType();
}
RecordDecl *RD = Ty->getAs<RecordType>()->getDecl();
const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD);
FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl());
if (!FD) // FIXME: deal with other kinds of member expressions
return APValue();
if (FD->getType()->isReferenceType())
return APValue();
// FIXME: This is linear time.
unsigned i = 0;
for (RecordDecl::field_iterator Field = RD->field_begin(),
FieldEnd = RD->field_end();
Field != FieldEnd; (void)++Field, ++i) {
if (*Field == FD)
break;
}
result.setLValue(result.getLValueBase(),
result.getLValueOffset() +
CharUnits::fromQuantity(RL.getFieldOffset(i) / 8));
return result;
}
APValue LValueExprEvaluator::VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
APValue Result;
if (!EvaluatePointer(E->getBase(), Result, Info))
return APValue();
APSInt Index;
if (!EvaluateInteger(E->getIdx(), Index, Info))
return APValue();
CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(E->getType());
CharUnits Offset = Index.getSExtValue() * ElementSize;
Result.setLValue(Result.getLValueBase(),
Result.getLValueOffset() + Offset);
return Result;
}
APValue LValueExprEvaluator::VisitUnaryDeref(UnaryOperator *E) {
APValue Result;
if (!EvaluatePointer(E->getSubExpr(), Result, Info))
return APValue();
return Result;
}
//===----------------------------------------------------------------------===//
// Pointer Evaluation
//===----------------------------------------------------------------------===//
namespace {
class PointerExprEvaluator
: public StmtVisitor<PointerExprEvaluator, APValue> {
EvalInfo &Info;
public:
PointerExprEvaluator(EvalInfo &info) : Info(info) {}
APValue VisitStmt(Stmt *S) {
return APValue();
}
APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
APValue VisitBinaryOperator(const BinaryOperator *E);
APValue VisitCastExpr(CastExpr* E);
APValue VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitUnaryAddrOf(const UnaryOperator *E);
APValue VisitObjCStringLiteral(ObjCStringLiteral *E)
{ return APValue(E); }
APValue VisitAddrLabelExpr(AddrLabelExpr *E)
{ return APValue(E); }
APValue VisitCallExpr(CallExpr *E);
APValue VisitBlockExpr(BlockExpr *E) {
if (!E->hasBlockDeclRefExprs())
return APValue(E);
return APValue();
}
APValue VisitImplicitValueInitExpr(ImplicitValueInitExpr *E)
{ return APValue((Expr*)0); }
APValue VisitConditionalOperator(ConditionalOperator *E);
APValue VisitChooseExpr(ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
APValue VisitCXXNullPtrLiteralExpr(CXXNullPtrLiteralExpr *E)
{ return APValue((Expr*)0); }
// FIXME: Missing: @protocol, @selector
};
} // end anonymous namespace
static bool EvaluatePointer(const Expr* E, APValue& Result, EvalInfo &Info) {
if (!E->getType()->hasPointerRepresentation())
return false;
Result = PointerExprEvaluator(Info).Visit(const_cast<Expr*>(E));
return Result.isLValue();
}
APValue PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() != BinaryOperator::Add &&
E->getOpcode() != BinaryOperator::Sub)
return APValue();
const Expr *PExp = E->getLHS();
const Expr *IExp = E->getRHS();
if (IExp->getType()->isPointerType())
std::swap(PExp, IExp);
APValue ResultLValue;
if (!EvaluatePointer(PExp, ResultLValue, Info))
return APValue();
llvm::APSInt AdditionalOffset(32);
if (!EvaluateInteger(IExp, AdditionalOffset, Info))
return APValue();
QualType PointeeType = PExp->getType()->getAs<PointerType>()->getPointeeType();
CharUnits SizeOfPointee;
// Explicitly handle GNU void* and function pointer arithmetic extensions.
if (PointeeType->isVoidType() || PointeeType->isFunctionType())
SizeOfPointee = CharUnits::One();
else
SizeOfPointee = Info.Ctx.getTypeSizeInChars(PointeeType);
CharUnits Offset = ResultLValue.getLValueOffset();
if (E->getOpcode() == BinaryOperator::Add)
Offset += AdditionalOffset.getLimitedValue() * SizeOfPointee;
else
Offset -= AdditionalOffset.getLimitedValue() * SizeOfPointee;
return APValue(ResultLValue.getLValueBase(), Offset);
}
APValue PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
APValue result;
if (EvaluateLValue(E->getSubExpr(), result, Info))
return result;
return APValue();
}
APValue PointerExprEvaluator::VisitCastExpr(CastExpr* E) {
Expr* SubExpr = E->getSubExpr();
switch (E->getCastKind()) {
default:
break;
case CastExpr::CK_Unknown: {
// FIXME: The handling for CK_Unknown is ugly/shouldn't be necessary!
// Check for pointer->pointer cast
if (SubExpr->getType()->isPointerType() ||
SubExpr->getType()->isObjCObjectPointerType() ||
SubExpr->getType()->isNullPtrType() ||
SubExpr->getType()->isBlockPointerType())
return Visit(SubExpr);
if (SubExpr->getType()->isIntegralType()) {
APValue Result;
if (!EvaluateIntegerOrLValue(SubExpr, Result, Info))
break;
if (Result.isInt()) {
Result.getInt().extOrTrunc((unsigned)Info.Ctx.getTypeSize(E->getType()));
return APValue(0,
CharUnits::fromQuantity(Result.getInt().getZExtValue()));
}
// Cast is of an lvalue, no need to change value.
return Result;
}
break;
}
case CastExpr::CK_NoOp:
case CastExpr::CK_BitCast:
case CastExpr::CK_AnyPointerToObjCPointerCast:
case CastExpr::CK_AnyPointerToBlockPointerCast:
return Visit(SubExpr);
case CastExpr::CK_IntegralToPointer: {
APValue Result;
if (!EvaluateIntegerOrLValue(SubExpr, Result, Info))
break;
if (Result.isInt()) {
Result.getInt().extOrTrunc((unsigned)Info.Ctx.getTypeSize(E->getType()));
return APValue(0,
CharUnits::fromQuantity(Result.getInt().getZExtValue()));
}
// Cast is of an lvalue, no need to change value.
return Result;
}
case CastExpr::CK_ArrayToPointerDecay:
case CastExpr::CK_FunctionToPointerDecay: {
APValue Result;
if (EvaluateLValue(SubExpr, Result, Info))
return Result;
break;
}
}
return APValue();
}
APValue PointerExprEvaluator::VisitCallExpr(CallExpr *E) {
if (E->isBuiltinCall(Info.Ctx) ==
Builtin::BI__builtin___CFStringMakeConstantString ||
E->isBuiltinCall(Info.Ctx) ==
Builtin::BI__builtin___NSStringMakeConstantString)
return APValue(E);
return APValue();
}
APValue PointerExprEvaluator::VisitConditionalOperator(ConditionalOperator *E) {
bool BoolResult;
if (!HandleConversionToBool(E->getCond(), BoolResult, Info))
return APValue();
Expr* EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
APValue Result;
if (EvaluatePointer(EvalExpr, Result, Info))
return Result;
return APValue();
}
//===----------------------------------------------------------------------===//
// Vector Evaluation
//===----------------------------------------------------------------------===//
namespace {
class VectorExprEvaluator
: public StmtVisitor<VectorExprEvaluator, APValue> {
EvalInfo &Info;
APValue GetZeroVector(QualType VecType);
public:
VectorExprEvaluator(EvalInfo &info) : Info(info) {}
APValue VisitStmt(Stmt *S) {
return APValue();
}
APValue VisitParenExpr(ParenExpr *E)
{ return Visit(E->getSubExpr()); }
APValue VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitUnaryPlus(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitUnaryReal(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E)
{ return GetZeroVector(E->getType()); }
APValue VisitCastExpr(const CastExpr* E);
APValue VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
APValue VisitInitListExpr(const InitListExpr *E);
APValue VisitConditionalOperator(const ConditionalOperator *E);
APValue VisitChooseExpr(const ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
APValue VisitUnaryImag(const UnaryOperator *E);
// FIXME: Missing: unary -, unary ~, binary add/sub/mul/div,
// binary comparisons, binary and/or/xor,
// shufflevector, ExtVectorElementExpr
// (Note that these require implementing conversions
// between vector types.)
};
} // end anonymous namespace
static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
if (!E->getType()->isVectorType())
return false;
Result = VectorExprEvaluator(Info).Visit(const_cast<Expr*>(E));
return !Result.isUninit();
}
APValue VectorExprEvaluator::VisitCastExpr(const CastExpr* E) {
const VectorType *VTy = E->getType()->getAs<VectorType>();
QualType EltTy = VTy->getElementType();
unsigned NElts = VTy->getNumElements();
unsigned EltWidth = Info.Ctx.getTypeSize(EltTy);
const Expr* SE = E->getSubExpr();
QualType SETy = SE->getType();
APValue Result = APValue();
// Check for vector->vector bitcast and scalar->vector splat.
if (SETy->isVectorType()) {
return this->Visit(const_cast<Expr*>(SE));
} else if (SETy->isIntegerType()) {
APSInt IntResult;
if (!EvaluateInteger(SE, IntResult, Info))
return APValue();
Result = APValue(IntResult);
} else if (SETy->isRealFloatingType()) {
APFloat F(0.0);
if (!EvaluateFloat(SE, F, Info))
return APValue();
Result = APValue(F);
} else
return APValue();
// For casts of a scalar to ExtVector, convert the scalar to the element type
// and splat it to all elements.
if (E->getType()->isExtVectorType()) {
if (EltTy->isIntegerType() && Result.isInt())
Result = APValue(HandleIntToIntCast(EltTy, SETy, Result.getInt(),
Info.Ctx));
else if (EltTy->isIntegerType())
Result = APValue(HandleFloatToIntCast(EltTy, SETy, Result.getFloat(),
Info.Ctx));
else if (EltTy->isRealFloatingType() && Result.isInt())
Result = APValue(HandleIntToFloatCast(EltTy, SETy, Result.getInt(),
Info.Ctx));
else if (EltTy->isRealFloatingType())
Result = APValue(HandleFloatToFloatCast(EltTy, SETy, Result.getFloat(),
Info.Ctx));
else
return APValue();
// Splat and create vector APValue.
llvm::SmallVector<APValue, 4> Elts(NElts, Result);
return APValue(&Elts[0], Elts.size());
}
// For casts of a scalar to regular gcc-style vector type, bitcast the scalar
// to the vector. To construct the APValue vector initializer, bitcast the
// initializing value to an APInt, and shift out the bits pertaining to each
// element.
APSInt Init;
Init = Result.isInt() ? Result.getInt() : Result.getFloat().bitcastToAPInt();
llvm::SmallVector<APValue, 4> Elts;
for (unsigned i = 0; i != NElts; ++i) {
APSInt Tmp = Init;
Tmp.extOrTrunc(EltWidth);
if (EltTy->isIntegerType())
Elts.push_back(APValue(Tmp));
else if (EltTy->isRealFloatingType())
Elts.push_back(APValue(APFloat(Tmp)));
else
return APValue();
Init >>= EltWidth;
}
return APValue(&Elts[0], Elts.size());
}
APValue
VectorExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return this->Visit(const_cast<Expr*>(E->getInitializer()));
}
APValue
VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
const VectorType *VT = E->getType()->getAs<VectorType>();
unsigned NumInits = E->getNumInits();
unsigned NumElements = VT->getNumElements();
QualType EltTy = VT->getElementType();
llvm::SmallVector<APValue, 4> Elements;
for (unsigned i = 0; i < NumElements; i++) {
if (EltTy->isIntegerType()) {
llvm::APSInt sInt(32);
if (i < NumInits) {
if (!EvaluateInteger(E->getInit(i), sInt, Info))
return APValue();
} else {
sInt = Info.Ctx.MakeIntValue(0, EltTy);
}
Elements.push_back(APValue(sInt));
} else {
llvm::APFloat f(0.0);
if (i < NumInits) {
if (!EvaluateFloat(E->getInit(i), f, Info))
return APValue();
} else {
f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy));
}
Elements.push_back(APValue(f));
}
}
return APValue(&Elements[0], Elements.size());
}
APValue
VectorExprEvaluator::GetZeroVector(QualType T) {
const VectorType *VT = T->getAs<VectorType>();
QualType EltTy = VT->getElementType();
APValue ZeroElement;
if (EltTy->isIntegerType())
ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy));
else
ZeroElement =
APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)));
llvm::SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement);
return APValue(&Elements[0], Elements.size());
}
APValue VectorExprEvaluator::VisitConditionalOperator(const ConditionalOperator *E) {
bool BoolResult;
if (!HandleConversionToBool(E->getCond(), BoolResult, Info))
return APValue();
Expr* EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
APValue Result;
if (EvaluateVector(EvalExpr, Result, Info))
return Result;
return APValue();
}
APValue VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (!E->getSubExpr()->isEvaluatable(Info.Ctx))
Info.EvalResult.HasSideEffects = true;
return GetZeroVector(E->getType());
}
//===----------------------------------------------------------------------===//
// Integer Evaluation
//===----------------------------------------------------------------------===//
namespace {
class IntExprEvaluator
: public StmtVisitor<IntExprEvaluator, bool> {
EvalInfo &Info;
APValue &Result;
public:
IntExprEvaluator(EvalInfo &info, APValue &result)
: Info(info), Result(result) {}
bool Success(const llvm::APSInt &SI, const Expr *E) {
assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
assert(SI.isSigned() == E->getType()->isSignedIntegerType() &&
"Invalid evaluation result.");
assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(SI);
return true;
}
bool Success(const llvm::APInt &I, const Expr *E) {
assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) &&
"Invalid evaluation result.");
Result = APValue(APSInt(I));
Result.getInt().setIsUnsigned(E->getType()->isUnsignedIntegerType());
return true;
}
bool Success(uint64_t Value, const Expr *E) {
assert(E->getType()->isIntegralType() && "Invalid evaluation result.");
Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType()));
return true;
}
bool Error(SourceLocation L, diag::kind D, const Expr *E) {
// Take the first error.
if (Info.EvalResult.Diag == 0) {
Info.EvalResult.DiagLoc = L;
Info.EvalResult.Diag = D;
Info.EvalResult.DiagExpr = E;
}
return false;
}
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
bool VisitStmt(Stmt *) {
assert(0 && "This should be called on integers, stmts are not integers");
return false;
}
bool VisitExpr(Expr *E) {
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
}
bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
bool VisitIntegerLiteral(const IntegerLiteral *E) {
return Success(E->getValue(), E);
}
bool VisitCharacterLiteral(const CharacterLiteral *E) {
return Success(E->getValue(), E);
}
bool VisitTypesCompatibleExpr(const TypesCompatibleExpr *E) {
// Per gcc docs "this built-in function ignores top level
// qualifiers". We need to use the canonical version to properly
// be able to strip CRV qualifiers from the type.
QualType T0 = Info.Ctx.getCanonicalType(E->getArgType1());
QualType T1 = Info.Ctx.getCanonicalType(E->getArgType2());
return Success(Info.Ctx.typesAreCompatible(T0.getUnqualifiedType(),
T1.getUnqualifiedType()),
E);
}
bool CheckReferencedDecl(const Expr *E, const Decl *D);
bool VisitDeclRefExpr(const DeclRefExpr *E) {
return CheckReferencedDecl(E, E->getDecl());
}
bool VisitMemberExpr(const MemberExpr *E) {
if (CheckReferencedDecl(E, E->getMemberDecl())) {
// Conservatively assume a MemberExpr will have side-effects
Info.EvalResult.HasSideEffects = true;
return true;
}
return false;
}
bool VisitCallExpr(CallExpr *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitConditionalOperator(const ConditionalOperator *E);
bool VisitCastExpr(CastExpr* E);
bool VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E);
bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) {
return Success(E->getValue(), E);
}
bool VisitGNUNullExpr(const GNUNullExpr *E) {
return Success(0, E);
}
bool VisitCXXZeroInitValueExpr(const CXXZeroInitValueExpr *E) {
return Success(0, E);
}
bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) {
return Success(0, E);
}
bool VisitUnaryTypeTraitExpr(const UnaryTypeTraitExpr *E) {
return Success(E->EvaluateTrait(Info.Ctx), E);
}
bool VisitChooseExpr(const ChooseExpr *E) {
return Visit(E->getChosenSubExpr(Info.Ctx));
}
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
private:
CharUnits GetAlignOfExpr(const Expr *E);
CharUnits GetAlignOfType(QualType T);
// FIXME: Missing: array subscript of vector, member of vector
};
} // end anonymous namespace
static bool EvaluateIntegerOrLValue(const Expr* E, APValue &Result, EvalInfo &Info) {
if (!E->getType()->isIntegralType())
return false;
return IntExprEvaluator(Info, Result).Visit(const_cast<Expr*>(E));
}
static bool EvaluateInteger(const Expr* E, APSInt &Result, EvalInfo &Info) {
APValue Val;
if (!EvaluateIntegerOrLValue(E, Val, Info) || !Val.isInt())
return false;
Result = Val.getInt();
return true;
}
bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
// Enums are integer constant exprs.
if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D))
return Success(ECD->getInitVal(), E);
// In C++, const, non-volatile integers initialized with ICEs are ICEs.
// In C, they can also be folded, although they are not ICEs.
if (Info.Ctx.getCanonicalType(E->getType()).getCVRQualifiers()
== Qualifiers::Const) {
if (isa<ParmVarDecl>(D))
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
if (const Expr *Init = VD->getAnyInitializer()) {
if (APValue *V = VD->getEvaluatedValue()) {
if (V->isInt())
return Success(V->getInt(), E);
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
}
if (VD->isEvaluatingValue())
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
VD->setEvaluatingValue();
if (Visit(const_cast<Expr*>(Init))) {
// Cache the evaluated value in the variable declaration.
VD->setEvaluatedValue(Result);
return true;
}
VD->setEvaluatedValue(APValue());
return false;
}
}
}
// Otherwise, random variable references are not constants.
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
}
/// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way
/// as GCC.
static int EvaluateBuiltinClassifyType(const CallExpr *E) {
// The following enum mimics the values returned by GCC.
// FIXME: Does GCC differ between lvalue and rvalue references here?
enum gcc_type_class {
no_type_class = -1,
void_type_class, integer_type_class, char_type_class,
enumeral_type_class, boolean_type_class,
pointer_type_class, reference_type_class, offset_type_class,
real_type_class, complex_type_class,
function_type_class, method_type_class,
record_type_class, union_type_class,
array_type_class, string_type_class,
lang_type_class
};
// If no argument was supplied, default to "no_type_class". This isn't
// ideal, however it is what gcc does.
if (E->getNumArgs() == 0)
return no_type_class;
QualType ArgTy = E->getArg(0)->getType();
if (ArgTy->isVoidType())
return void_type_class;
else if (ArgTy->isEnumeralType())
return enumeral_type_class;
else if (ArgTy->isBooleanType())
return boolean_type_class;
else if (ArgTy->isCharType())
return string_type_class; // gcc doesn't appear to use char_type_class
else if (ArgTy->isIntegerType())
return integer_type_class;
else if (ArgTy->isPointerType())
return pointer_type_class;
else if (ArgTy->isReferenceType())
return reference_type_class;
else if (ArgTy->isRealType())
return real_type_class;
else if (ArgTy->isComplexType())
return complex_type_class;
else if (ArgTy->isFunctionType())
return function_type_class;
else if (ArgTy->isStructureType())
return record_type_class;
else if (ArgTy->isUnionType())
return union_type_class;
else if (ArgTy->isArrayType())
return array_type_class;
else if (ArgTy->isUnionType())
return union_type_class;
else // FIXME: offset_type_class, method_type_class, & lang_type_class?
assert(0 && "CallExpr::isBuiltinClassifyType(): unimplemented type");
return -1;
}
bool IntExprEvaluator::VisitCallExpr(CallExpr *E) {
switch (E->isBuiltinCall(Info.Ctx)) {
default:
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
case Builtin::BI__builtin_object_size: {
const Expr *Arg = E->getArg(0)->IgnoreParens();
Expr::EvalResult Base;
// TODO: Perhaps we should let LLVM lower this?
if (Arg->EvaluateAsAny(Base, Info.Ctx)
&& Base.Val.getKind() == APValue::LValue
&& !Base.HasSideEffects)
if (const Expr *LVBase = Base.Val.getLValueBase())
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(LVBase)) {
if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl())) {
if (!VD->getType()->isIncompleteType()
&& VD->getType()->isObjectType()
&& !VD->getType()->isVariablyModifiedType()
&& !VD->getType()->isDependentType()) {
CharUnits Size = Info.Ctx.getTypeSizeInChars(VD->getType());
CharUnits Offset = Base.Val.getLValueOffset();
if (!Offset.isNegative() && Offset <= Size)
Size -= Offset;
else
Size = CharUnits::Zero();
return Success(Size.getQuantity(), E);
}
}
}
// If evaluating the argument has side-effects we can't determine
// the size of the object and lower it to unknown now.
if (E->getArg(0)->HasSideEffects(Info.Ctx)) {
if (E->getArg(1)->EvaluateAsInt(Info.Ctx).getZExtValue() <= 1)
return Success(-1ULL, E);
return Success(0, E);
}
return Error(E->getLocStart(), diag::note_invalid_subexpr_in_ice, E);
}
case Builtin::BI__builtin_classify_type:
return Success(EvaluateBuiltinClassifyType(E), E);
case Builtin::BI__builtin_constant_p:
// __builtin_constant_p always has one operand: it returns true if that
// operand can be folded, false otherwise.
return Success(E->getArg(0)->isEvaluatable(Info.Ctx), E);
case Builtin::BI__builtin_eh_return_data_regno: {
int Operand = E->getArg(0)->EvaluateAsInt(Info.Ctx).getZExtValue();
Operand = Info.Ctx.Target.getEHDataRegisterNumber(Operand);
return Success(Operand, E);
}
case Builtin::BI__builtin_expect:
return Visit(E->getArg(0));
}
}
bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() == BinaryOperator::Comma) {
if (!Visit(E->getRHS()))
return false;
// If we can't evaluate the LHS, it might have side effects;
// conservatively mark it.
if (!E->getLHS()->isEvaluatable(Info.Ctx))
Info.EvalResult.HasSideEffects = true;
return true;
}
if (E->isLogicalOp()) {
// These need to be handled specially because the operands aren't
// necessarily integral
bool lhsResult, rhsResult;
if (HandleConversionToBool(E->getLHS(), lhsResult, Info)) {
// 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 (lhsResult == (E->getOpcode() == BinaryOperator::LOr))
return Success(lhsResult, E);
if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
if (E->getOpcode() == BinaryOperator::LOr)
return Success(lhsResult || rhsResult, E);
else
return Success(lhsResult && rhsResult, E);
}
} else {
if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
// We can't evaluate the LHS; however, sometimes the result
// is determined by the RHS: X && 0 -> 0, X || 1 -> 1.
if (rhsResult == (E->getOpcode() == BinaryOperator::LOr) ||
!rhsResult == (E->getOpcode() == BinaryOperator::LAnd)) {
// Since we weren't able to evaluate the left hand side, it
// must have had side effects.
Info.EvalResult.HasSideEffects = true;
return Success(rhsResult, E);
}
}
}
return false;
}
QualType LHSTy = E->getLHS()->getType();
QualType RHSTy = E->getRHS()->getType();
if (LHSTy->isAnyComplexType()) {
assert(RHSTy->isAnyComplexType() && "Invalid comparison");
APValue LHS, RHS;
if (!EvaluateComplex(E->getLHS(), LHS, Info))
return false;
if (!EvaluateComplex(E->getRHS(), RHS, Info))
return false;
if (LHS.isComplexFloat()) {
APFloat::cmpResult CR_r =
LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal());
APFloat::cmpResult CR_i =
LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag());
if (E->getOpcode() == BinaryOperator::EQ)
return Success((CR_r == APFloat::cmpEqual &&
CR_i == APFloat::cmpEqual), E);
else {
assert(E->getOpcode() == BinaryOperator::NE &&
"Invalid complex comparison.");
return Success(((CR_r == APFloat::cmpGreaterThan ||
CR_r == APFloat::cmpLessThan) &&
(CR_i == APFloat::cmpGreaterThan ||
CR_i == APFloat::cmpLessThan)), E);
}
} else {
if (E->getOpcode() == BinaryOperator::EQ)
return Success((LHS.getComplexIntReal() == RHS.getComplexIntReal() &&
LHS.getComplexIntImag() == RHS.getComplexIntImag()), E);
else {
assert(E->getOpcode() == BinaryOperator::NE &&
"Invalid compex comparison.");
return Success((LHS.getComplexIntReal() != RHS.getComplexIntReal() ||
LHS.getComplexIntImag() != RHS.getComplexIntImag()), E);
}
}
}
if (LHSTy->isRealFloatingType() &&
RHSTy->isRealFloatingType()) {
APFloat RHS(0.0), LHS(0.0);
if (!EvaluateFloat(E->getRHS(), RHS, Info))
return false;
if (!EvaluateFloat(E->getLHS(), LHS, Info))
return false;
APFloat::cmpResult CR = LHS.compare(RHS);
switch (E->getOpcode()) {
default:
assert(0 && "Invalid binary operator!");
case BinaryOperator::LT:
return Success(CR == APFloat::cmpLessThan, E);
case BinaryOperator::GT:
return Success(CR == APFloat::cmpGreaterThan, E);
case BinaryOperator::LE:
return Success(CR == APFloat::cmpLessThan || CR == APFloat::cmpEqual, E);
case BinaryOperator::GE:
return Success(CR == APFloat::cmpGreaterThan || CR == APFloat::cmpEqual,
E);
case BinaryOperator::EQ:
return Success(CR == APFloat::cmpEqual, E);
case BinaryOperator::NE:
return Success(CR == APFloat::cmpGreaterThan
|| CR == APFloat::cmpLessThan, E);
}
}
if (LHSTy->isPointerType() && RHSTy->isPointerType()) {
if (E->getOpcode() == BinaryOperator::Sub || E->isEqualityOp()) {
APValue LHSValue;
if (!EvaluatePointer(E->getLHS(), LHSValue, Info))
return false;
APValue RHSValue;
if (!EvaluatePointer(E->getRHS(), RHSValue, Info))
return false;
// Reject any bases from the normal codepath; we special-case comparisons
// to null.
if (LHSValue.getLValueBase()) {
if (!E->isEqualityOp())
return false;
if (RHSValue.getLValueBase() || !RHSValue.getLValueOffset().isZero())
return false;
bool bres;
if (!EvalPointerValueAsBool(LHSValue, bres))
return false;
return Success(bres ^ (E->getOpcode() == BinaryOperator::EQ), E);
} else if (RHSValue.getLValueBase()) {
if (!E->isEqualityOp())
return false;
if (LHSValue.getLValueBase() || !LHSValue.getLValueOffset().isZero())
return false;
bool bres;
if (!EvalPointerValueAsBool(RHSValue, bres))
return false;
return Success(bres ^ (E->getOpcode() == BinaryOperator::EQ), E);
}
if (E->getOpcode() == BinaryOperator::Sub) {
const QualType Type = E->getLHS()->getType();
const QualType ElementType = Type->getAs<PointerType>()->getPointeeType();
CharUnits ElementSize = CharUnits::One();
if (!ElementType->isVoidType() && !ElementType->isFunctionType())
ElementSize = Info.Ctx.getTypeSizeInChars(ElementType);
CharUnits Diff = LHSValue.getLValueOffset() -
RHSValue.getLValueOffset();
return Success(Diff / ElementSize, E);
}
bool Result;
if (E->getOpcode() == BinaryOperator::EQ) {
Result = LHSValue.getLValueOffset() == RHSValue.getLValueOffset();
} else {
Result = LHSValue.getLValueOffset() != RHSValue.getLValueOffset();
}
return Success(Result, E);
}
}
if (!LHSTy->isIntegralType() ||
!RHSTy->isIntegralType()) {
// We can't continue from here for non-integral types, and they
// could potentially confuse the following operations.
return false;
}
// The LHS of a constant expr is always evaluated and needed.
if (!Visit(E->getLHS()))
return false; // error in subexpression.
APValue RHSVal;
if (!EvaluateIntegerOrLValue(E->getRHS(), RHSVal, Info))
return false;
// Handle cases like (unsigned long)&a + 4.
if (E->isAdditiveOp() && Result.isLValue() && RHSVal.isInt()) {
CharUnits Offset = Result.getLValueOffset();
CharUnits AdditionalOffset = CharUnits::fromQuantity(
RHSVal.getInt().getZExtValue());
if (E->getOpcode() == BinaryOperator::Add)
Offset += AdditionalOffset;
else
Offset -= AdditionalOffset;
Result = APValue(Result.getLValueBase(), Offset);
return true;
}
// Handle cases like 4 + (unsigned long)&a
if (E->getOpcode() == BinaryOperator::Add &&
RHSVal.isLValue() && Result.isInt()) {
CharUnits Offset = RHSVal.getLValueOffset();
Offset += CharUnits::fromQuantity(Result.getInt().getZExtValue());
Result = APValue(RHSVal.getLValueBase(), Offset);
return true;
}
// All the following cases expect both operands to be an integer
if (!Result.isInt() || !RHSVal.isInt())
return false;
APSInt& RHS = RHSVal.getInt();
switch (E->getOpcode()) {
default:
return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
case BinaryOperator::Mul: return Success(Result.getInt() * RHS, E);
case BinaryOperator::Add: return Success(Result.getInt() + RHS, E);
case BinaryOperator::Sub: return Success(Result.getInt() - RHS, E);
case BinaryOperator::And: return Success(Result.getInt() & RHS, E);
case BinaryOperator::Xor: return Success(Result.getInt() ^ RHS, E);
case BinaryOperator::Or: return Success(Result.getInt() | RHS, E);
case BinaryOperator::Div:
if (RHS == 0)
return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
return Success(Result.getInt() / RHS, E);
case BinaryOperator::Rem:
if (RHS == 0)
return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
return Success(Result.getInt() % RHS, E);
case BinaryOperator::Shl: {
// FIXME: Warn about out of range shift amounts!
unsigned SA =
(unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
return Success(Result.getInt() << SA, E);
}
case BinaryOperator::Shr: {
unsigned SA =
(unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
return Success(Result.getInt() >> SA, E);
}
case BinaryOperator::LT: return Success(Result.getInt() < RHS, E);
case BinaryOperator::GT: return Success(Result.getInt() > RHS, E);
case BinaryOperator::LE: return Success(Result.getInt() <= RHS, E);
case BinaryOperator::GE: return Success(Result.getInt() >= RHS, E);
case BinaryOperator::EQ: return Success(Result.getInt() == RHS, E);
case BinaryOperator::NE: return Success(Result.getInt() != RHS, E);
}
}
bool IntExprEvaluator::VisitConditionalOperator(const ConditionalOperator *E) {
bool Cond;
if (!HandleConversionToBool(E->getCond(), Cond, Info))
return false;
return Visit(Cond ? E->getTrueExpr() : E->getFalseExpr());
}
CharUnits IntExprEvaluator::GetAlignOfType(QualType T) {
// C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
// the result is the size of the referenced type."
// C++ [expr.alignof]p3: "When alignof is applied to a reference type, the
// result shall be the alignment of the referenced type."
if (const ReferenceType *Ref = T->getAs<ReferenceType>())
T = Ref->getPointeeType();
// Get information about the alignment.
unsigned CharSize = Info.Ctx.Target.getCharWidth();
// __alignof is defined to return the preferred alignment.
return CharUnits::fromQuantity(
Info.Ctx.getPreferredTypeAlign(T.getTypePtr()) / CharSize);
}
CharUnits IntExprEvaluator::GetAlignOfExpr(const Expr *E) {
E = E->IgnoreParens();
// alignof decl is always accepted, even if it doesn't make sense: we default
// to 1 in those cases.
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
return Info.Ctx.getDeclAlign(DRE->getDecl(),
/*RefAsPointee*/true);
if (const MemberExpr *ME = dyn_cast<MemberExpr>(E))
return Info.Ctx.getDeclAlign(ME->getMemberDecl(),
/*RefAsPointee*/true);
return GetAlignOfType(E->getType());
}
/// VisitSizeAlignOfExpr - Evaluate a sizeof or alignof with a result as the
/// expression's type.
bool IntExprEvaluator::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr *E) {
// Handle alignof separately.
if (!E->isSizeOf()) {
if (E->isArgumentType())
return Success(GetAlignOfType(E->getArgumentType()).getQuantity(), E);
else
return Success(GetAlignOfExpr(E->getArgumentExpr()).getQuantity(), E);
}
QualType SrcTy = E->getTypeOfArgument();
// C++ [expr.sizeof]p2: "When applied to a reference or a reference type,
// the result is the size of the referenced type."
// C++ [expr.alignof]p3: "When alignof is applied to a reference type, the
// result shall be the alignment of the referenced type."
if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>())
SrcTy = Ref->getPointeeType();
// sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc
// extension.
if (SrcTy->isVoidType() || SrcTy->isFunctionType())
return Success(1, E);
// sizeof(vla) is not a constantexpr: C99 6.5.3.4p2.
if (!SrcTy->isConstantSizeType())
return false;
// Get information about the size.
return Success(Info.Ctx.getTypeSizeInChars(SrcTy).getQuantity(), E);
}
bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
// Special case unary operators that do not need their subexpression
// evaluated. offsetof/sizeof/alignof are all special.
if (E->isOffsetOfOp()) {
// The AST for offsetof is defined in such a way that we can just
// directly Evaluate it as an l-value.
APValue LV;
if (!EvaluateLValue(E->getSubExpr(), LV, Info))
return false;
if (LV.getLValueBase())
return false;
return Success(LV.getLValueOffset().getQuantity(), E);
}
if (E->getOpcode() == UnaryOperator::LNot) {
// LNot's operand isn't necessarily an integer, so we handle it specially.
bool bres;
if (!HandleConversionToBool(E->getSubExpr(), bres, Info))
return false;
return Success(!bres, E);
}
// Only handle integral operations...
if (!E->getSubExpr()->getType()->isIntegralType())
return false;
// Get the operand value into 'Result'.
if (!Visit(E->getSubExpr()))
return false;
switch (E->getOpcode()) {
default:
// Address, indirect, pre/post inc/dec, etc are not valid constant exprs.
// See C99 6.6p3.
return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
case UnaryOperator::Extension:
// FIXME: Should extension allow i-c-e extension expressions in its scope?
// If so, we could clear the diagnostic ID.
return true;
case UnaryOperator::Plus:
// The result is always just the subexpr.
return true;
case UnaryOperator::Minus:
if (!Result.isInt()) return false;
return Success(-Result.getInt(), E);
case UnaryOperator::Not:
if (!Result.isInt()) return false;
return Success(~Result.getInt(), E);
}
}
/// HandleCast - This is used to evaluate implicit or explicit casts where the
/// result type is integer.
bool IntExprEvaluator::VisitCastExpr(CastExpr *E) {
Expr *SubExpr = E->getSubExpr();
QualType DestType = E->getType();
QualType SrcType = SubExpr->getType();
if (DestType->isBooleanType()) {
bool BoolResult;
if (!HandleConversionToBool(SubExpr, BoolResult, Info))
return false;
return Success(BoolResult, E);
}
// Handle simple integer->integer casts.
if (SrcType->isIntegralType()) {
if (!Visit(SubExpr))
return false;
if (!Result.isInt()) {
// Only allow casts of lvalues if they are lossless.
return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType);
}
return Success(HandleIntToIntCast(DestType, SrcType,
Result.getInt(), Info.Ctx), E);
}
// FIXME: Clean this up!
if (SrcType->isPointerType()) {
APValue LV;
if (!EvaluatePointer(SubExpr, LV, Info))
return false;
if (LV.getLValueBase()) {
// Only allow based lvalue casts if they are lossless.
if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType))
return false;
Result = LV;
return true;
}
APSInt AsInt = Info.Ctx.MakeIntValue(LV.getLValueOffset().getQuantity(),
SrcType);
return Success(HandleIntToIntCast(DestType, SrcType, AsInt, Info.Ctx), E);
}
if (SrcType->isArrayType() || SrcType->isFunctionType()) {
// This handles double-conversion cases, where there's both
// an l-value promotion and an implicit conversion to int.
APValue LV;
if (!EvaluateLValue(SubExpr, LV, Info))
return false;
if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(Info.Ctx.VoidPtrTy))
return false;
Result = LV;
return true;
}
if (SrcType->isAnyComplexType()) {
APValue C;
if (!EvaluateComplex(SubExpr, C, Info))
return false;
if (C.isComplexFloat())
return Success(HandleFloatToIntCast(DestType, SrcType,
C.getComplexFloatReal(), Info.Ctx),
E);
else
return Success(HandleIntToIntCast(DestType, SrcType,
C.getComplexIntReal(), Info.Ctx), E);
}
// FIXME: Handle vectors
if (!SrcType->isRealFloatingType())
return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
APFloat F(0.0);
if (!EvaluateFloat(SubExpr, F, Info))
return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
return Success(HandleFloatToIntCast(DestType, SrcType, F, Info.Ctx), E);
}
bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
APValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info) || !LV.isComplexInt())
return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
return Success(LV.getComplexIntReal(), E);
}
return Visit(E->getSubExpr());
}
bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isComplexIntegerType()) {
APValue LV;
if (!EvaluateComplex(E->getSubExpr(), LV, Info) || !LV.isComplexInt())
return Error(E->getExprLoc(), diag::note_invalid_subexpr_in_ice, E);
return Success(LV.getComplexIntImag(), E);
}
if (!E->getSubExpr()->isEvaluatable(Info.Ctx))
Info.EvalResult.HasSideEffects = true;
return Success(0, E);
}
//===----------------------------------------------------------------------===//
// Float Evaluation
//===----------------------------------------------------------------------===//
namespace {
class FloatExprEvaluator
: public StmtVisitor<FloatExprEvaluator, bool> {
EvalInfo &Info;
APFloat &Result;
public:
FloatExprEvaluator(EvalInfo &info, APFloat &result)
: Info(info), Result(result) {}
bool VisitStmt(Stmt *S) {
return false;
}
bool VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
bool VisitCallExpr(const CallExpr *E);
bool VisitUnaryOperator(const UnaryOperator *E);
bool VisitBinaryOperator(const BinaryOperator *E);
bool VisitFloatingLiteral(const FloatingLiteral *E);
bool VisitCastExpr(CastExpr *E);
bool VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E);
bool VisitConditionalOperator(ConditionalOperator *E);
bool VisitChooseExpr(const ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
bool VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
// FIXME: Missing: __real__/__imag__, array subscript of vector,
// member of vector, ImplicitValueInitExpr
};
} // end anonymous namespace
static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
return FloatExprEvaluator(Info, Result).Visit(const_cast<Expr*>(E));
}
static bool TryEvaluateBuiltinNaN(ASTContext &Context,
QualType ResultTy,
const Expr *Arg,
bool SNaN,
llvm::APFloat &Result) {
const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts());
if (!S) return false;
const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy);
llvm::APInt fill;
// Treat empty strings as if they were zero.
if (S->getString().empty())
fill = llvm::APInt(32, 0);
else if (S->getString().getAsInteger(0, fill))
return false;
if (SNaN)
Result = llvm::APFloat::getSNaN(Sem, false, &fill);
else
Result = llvm::APFloat::getQNaN(Sem, false, &fill);
return true;
}
bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
switch (E->isBuiltinCall(Info.Ctx)) {
default: return false;
case Builtin::BI__builtin_huge_val:
case Builtin::BI__builtin_huge_valf:
case Builtin::BI__builtin_huge_vall:
case Builtin::BI__builtin_inf:
case Builtin::BI__builtin_inff:
case Builtin::BI__builtin_infl: {
const llvm::fltSemantics &Sem =
Info.Ctx.getFloatTypeSemantics(E->getType());
Result = llvm::APFloat::getInf(Sem);
return true;
}
case Builtin::BI__builtin_nans:
case Builtin::BI__builtin_nansf:
case Builtin::BI__builtin_nansl:
return TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
true, Result);
case Builtin::BI__builtin_nan:
case Builtin::BI__builtin_nanf:
case Builtin::BI__builtin_nanl:
// If this is __builtin_nan() turn this into a nan, otherwise we
// can't constant fold it.
return TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0),
false, Result);
case Builtin::BI__builtin_fabs:
case Builtin::BI__builtin_fabsf:
case Builtin::BI__builtin_fabsl:
if (!EvaluateFloat(E->getArg(0), Result, Info))
return false;
if (Result.isNegative())
Result.changeSign();
return true;
case Builtin::BI__builtin_copysign:
case Builtin::BI__builtin_copysignf:
case Builtin::BI__builtin_copysignl: {
APFloat RHS(0.);
if (!EvaluateFloat(E->getArg(0), Result, Info) ||
!EvaluateFloat(E->getArg(1), RHS, Info))
return false;
Result.copySign(RHS);
return true;
}
}
}
bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
if (E->getOpcode() == UnaryOperator::Deref)
return false;
if (!EvaluateFloat(E->getSubExpr(), Result, Info))
return false;
switch (E->getOpcode()) {
default: return false;
case UnaryOperator::Plus:
return true;
case UnaryOperator::Minus:
Result.changeSign();
return true;
}
}
bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->getOpcode() == BinaryOperator::Comma) {
if (!EvaluateFloat(E->getRHS(), Result, Info))
return false;
// If we can't evaluate the LHS, it might have side effects;
// conservatively mark it.
if (!E->getLHS()->isEvaluatable(Info.Ctx))
Info.EvalResult.HasSideEffects = true;
return true;
}
// FIXME: Diagnostics? I really don't understand how the warnings
// and errors are supposed to work.
APFloat RHS(0.0);
if (!EvaluateFloat(E->getLHS(), Result, Info))
return false;
if (!EvaluateFloat(E->getRHS(), RHS, Info))
return false;
switch (E->getOpcode()) {
default: return false;
case BinaryOperator::Mul:
Result.multiply(RHS, APFloat::rmNearestTiesToEven);
return true;
case BinaryOperator::Add:
Result.add(RHS, APFloat::rmNearestTiesToEven);
return true;
case BinaryOperator::Sub:
Result.subtract(RHS, APFloat::rmNearestTiesToEven);
return true;
case BinaryOperator::Div:
Result.divide(RHS, APFloat::rmNearestTiesToEven);
return true;
}
}
bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) {
Result = E->getValue();
return true;
}
bool FloatExprEvaluator::VisitCastExpr(CastExpr *E) {
Expr* SubExpr = E->getSubExpr();
if (SubExpr->getType()->isIntegralType()) {
APSInt IntResult;
if (!EvaluateInteger(SubExpr, IntResult, Info))
return false;
Result = HandleIntToFloatCast(E->getType(), SubExpr->getType(),
IntResult, Info.Ctx);
return true;
}
if (SubExpr->getType()->isRealFloatingType()) {
if (!Visit(SubExpr))
return false;
Result = HandleFloatToFloatCast(E->getType(), SubExpr->getType(),
Result, Info.Ctx);
return true;
}
// FIXME: Handle complex types
return false;
}
bool FloatExprEvaluator::VisitCXXZeroInitValueExpr(CXXZeroInitValueExpr *E) {
Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType()));
return true;
}
bool FloatExprEvaluator::VisitConditionalOperator(ConditionalOperator *E) {
bool Cond;
if (!HandleConversionToBool(E->getCond(), Cond, Info))
return false;
return Visit(Cond ? E->getTrueExpr() : E->getFalseExpr());
}
//===----------------------------------------------------------------------===//
// Complex Evaluation (for float and integer)
//===----------------------------------------------------------------------===//
namespace {
class ComplexExprEvaluator
: public StmtVisitor<ComplexExprEvaluator, APValue> {
EvalInfo &Info;
public:
ComplexExprEvaluator(EvalInfo &info) : Info(info) {}
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
APValue VisitStmt(Stmt *S) {
return APValue();
}
APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
APValue VisitImaginaryLiteral(ImaginaryLiteral *E) {
Expr* SubExpr = E->getSubExpr();
if (SubExpr->getType()->isRealFloatingType()) {
APFloat Result(0.0);
if (!EvaluateFloat(SubExpr, Result, Info))
return APValue();
return APValue(APFloat(Result.getSemantics(), APFloat::fcZero, false),
Result);
} else {
assert(SubExpr->getType()->isIntegerType() &&
"Unexpected imaginary literal.");
llvm::APSInt Result;
if (!EvaluateInteger(SubExpr, Result, Info))
return APValue();
llvm::APSInt Zero(Result.getBitWidth(), !Result.isSigned());
Zero = 0;
return APValue(Zero, Result);
}
}
APValue VisitCastExpr(CastExpr *E) {
Expr* SubExpr = E->getSubExpr();
QualType EltType = E->getType()->getAs<ComplexType>()->getElementType();
QualType SubType = SubExpr->getType();
if (SubType->isRealFloatingType()) {
APFloat Result(0.0);
if (!EvaluateFloat(SubExpr, Result, Info))
return APValue();
if (EltType->isRealFloatingType()) {
Result = HandleFloatToFloatCast(EltType, SubType, Result, Info.Ctx);
return APValue(Result,
APFloat(Result.getSemantics(), APFloat::fcZero, false));
} else {
llvm::APSInt IResult;
IResult = HandleFloatToIntCast(EltType, SubType, Result, Info.Ctx);
llvm::APSInt Zero(IResult.getBitWidth(), !IResult.isSigned());
Zero = 0;
return APValue(IResult, Zero);
}
} else if (SubType->isIntegerType()) {
APSInt Result;
if (!EvaluateInteger(SubExpr, Result, Info))
return APValue();
if (EltType->isRealFloatingType()) {
APFloat FResult =
HandleIntToFloatCast(EltType, SubType, Result, Info.Ctx);
return APValue(FResult,
APFloat(FResult.getSemantics(), APFloat::fcZero, false));
} else {
Result = HandleIntToIntCast(EltType, SubType, Result, Info.Ctx);
llvm::APSInt Zero(Result.getBitWidth(), !Result.isSigned());
Zero = 0;
return APValue(Result, Zero);
}
} else if (const ComplexType *CT = SubType->getAs<ComplexType>()) {
APValue Src;
if (!EvaluateComplex(SubExpr, Src, Info))
return APValue();
QualType SrcType = CT->getElementType();
if (Src.isComplexFloat()) {
if (EltType->isRealFloatingType()) {
return APValue(HandleFloatToFloatCast(EltType, SrcType,
Src.getComplexFloatReal(),
Info.Ctx),
HandleFloatToFloatCast(EltType, SrcType,
Src.getComplexFloatImag(),
Info.Ctx));
} else {
return APValue(HandleFloatToIntCast(EltType, SrcType,
Src.getComplexFloatReal(),
Info.Ctx),
HandleFloatToIntCast(EltType, SrcType,
Src.getComplexFloatImag(),
Info.Ctx));
}
} else {
assert(Src.isComplexInt() && "Invalid evaluate result.");
if (EltType->isRealFloatingType()) {
return APValue(HandleIntToFloatCast(EltType, SrcType,
Src.getComplexIntReal(),
Info.Ctx),
HandleIntToFloatCast(EltType, SrcType,
Src.getComplexIntImag(),
Info.Ctx));
} else {
return APValue(HandleIntToIntCast(EltType, SrcType,
Src.getComplexIntReal(),
Info.Ctx),
HandleIntToIntCast(EltType, SrcType,
Src.getComplexIntImag(),
Info.Ctx));
}
}
}
// FIXME: Handle more casts.
return APValue();
}
APValue VisitBinaryOperator(const BinaryOperator *E);
APValue VisitChooseExpr(const ChooseExpr *E)
{ return Visit(E->getChosenSubExpr(Info.Ctx)); }
APValue VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
// FIXME Missing: unary +/-/~, binary div, ImplicitValueInitExpr,
// conditional ?:, comma
};
} // end anonymous namespace
static bool EvaluateComplex(const Expr *E, APValue &Result, EvalInfo &Info) {
Result = ComplexExprEvaluator(Info).Visit(const_cast<Expr*>(E));
assert((!Result.isComplexFloat() ||
(&Result.getComplexFloatReal().getSemantics() ==
&Result.getComplexFloatImag().getSemantics())) &&
"Invalid complex evaluation.");
return Result.isComplexFloat() || Result.isComplexInt();
}
APValue ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
APValue Result, RHS;
if (!EvaluateComplex(E->getLHS(), Result, Info))
return APValue();
if (!EvaluateComplex(E->getRHS(), RHS, Info))
return APValue();
assert(Result.isComplexFloat() == RHS.isComplexFloat() &&
"Invalid operands to binary operator.");
switch (E->getOpcode()) {
default: return APValue();
case BinaryOperator::Add:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().add(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
Result.getComplexFloatImag().add(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
} else {
Result.getComplexIntReal() += RHS.getComplexIntReal();
Result.getComplexIntImag() += RHS.getComplexIntImag();
}
break;
case BinaryOperator::Sub:
if (Result.isComplexFloat()) {
Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(),
APFloat::rmNearestTiesToEven);
Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(),
APFloat::rmNearestTiesToEven);
} else {
Result.getComplexIntReal() -= RHS.getComplexIntReal();
Result.getComplexIntImag() -= RHS.getComplexIntImag();
}
break;
case BinaryOperator::Mul:
if (Result.isComplexFloat()) {
APValue LHS = Result;
APFloat &LHS_r = LHS.getComplexFloatReal();
APFloat &LHS_i = LHS.getComplexFloatImag();
APFloat &RHS_r = RHS.getComplexFloatReal();
APFloat &RHS_i = RHS.getComplexFloatImag();
APFloat Tmp = LHS_r;
Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven);
Result.getComplexFloatReal() = Tmp;
Tmp = LHS_i;
Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven);
Result.getComplexFloatReal().subtract(Tmp, APFloat::rmNearestTiesToEven);
Tmp = LHS_r;
Tmp.multiply(RHS_i, APFloat::rmNearestTiesToEven);
Result.getComplexFloatImag() = Tmp;
Tmp = LHS_i;
Tmp.multiply(RHS_r, APFloat::rmNearestTiesToEven);
Result.getComplexFloatImag().add(Tmp, APFloat::rmNearestTiesToEven);
} else {
APValue LHS = Result;
Result.getComplexIntReal() =
(LHS.getComplexIntReal() * RHS.getComplexIntReal() -
LHS.getComplexIntImag() * RHS.getComplexIntImag());
Result.getComplexIntImag() =
(LHS.getComplexIntReal() * RHS.getComplexIntImag() +
LHS.getComplexIntImag() * RHS.getComplexIntReal());
}
break;
}
return Result;
}
//===----------------------------------------------------------------------===//
// Top level Expr::Evaluate method.
//===----------------------------------------------------------------------===//
/// Evaluate - Return true if this is a constant which we can fold using
/// any crazy technique (that has nothing to do with language standards) that
/// we want to. If this function returns true, it returns the folded constant
/// in Result.
bool Expr::Evaluate(EvalResult &Result, ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result);
if (getType()->isVectorType()) {
if (!EvaluateVector(this, Result.Val, Info))
return false;
} else if (getType()->isIntegerType()) {
if (!IntExprEvaluator(Info, Result.Val).Visit(const_cast<Expr*>(this)))
return false;
} else if (getType()->hasPointerRepresentation()) {
if (!EvaluatePointer(this, Result.Val, Info))
return false;
} else if (getType()->isRealFloatingType()) {
llvm::APFloat f(0.0);
if (!EvaluateFloat(this, f, Info))
return false;
Result.Val = APValue(f);
} else if (getType()->isAnyComplexType()) {
if (!EvaluateComplex(this, Result.Val, Info))
return false;
} else
return false;
return true;
}
bool Expr::EvaluateAsAny(EvalResult &Result, ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result, true);
if (getType()->isVectorType()) {
if (!EvaluateVector(this, Result.Val, Info))
return false;
} else if (getType()->isIntegerType()) {
if (!IntExprEvaluator(Info, Result.Val).Visit(const_cast<Expr*>(this)))
return false;
} else if (getType()->hasPointerRepresentation()) {
if (!EvaluatePointer(this, Result.Val, Info))
return false;
} else if (getType()->isRealFloatingType()) {
llvm::APFloat f(0.0);
if (!EvaluateFloat(this, f, Info))
return false;
Result.Val = APValue(f);
} else if (getType()->isAnyComplexType()) {
if (!EvaluateComplex(this, Result.Val, Info))
return false;
} else
return false;
return true;
}
bool Expr::EvaluateAsBooleanCondition(bool &Result, ASTContext &Ctx) const {
EvalResult Scratch;
EvalInfo Info(Ctx, Scratch);
return HandleConversionToBool(this, Result, Info);
}
bool Expr::EvaluateAsLValue(EvalResult &Result, ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result);
return EvaluateLValue(this, Result.Val, Info) && !Result.HasSideEffects;
}
bool Expr::EvaluateAsAnyLValue(EvalResult &Result, ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result, true);
return EvaluateLValue(this, Result.Val, Info) && !Result.HasSideEffects;
}
/// isEvaluatable - Call Evaluate to see if this expression can be constant
/// folded, but discard the result.
bool Expr::isEvaluatable(ASTContext &Ctx) const {
EvalResult Result;
return Evaluate(Result, Ctx) && !Result.HasSideEffects;
}
bool Expr::HasSideEffects(ASTContext &Ctx) const {
Expr::EvalResult Result;
EvalInfo Info(Ctx, Result);
return HasSideEffect(Info).Visit(const_cast<Expr*>(this));
}
APSInt Expr::EvaluateAsInt(ASTContext &Ctx) const {
EvalResult EvalResult;
bool Result = Evaluate(EvalResult, Ctx);
Result = Result;
assert(Result && "Could not evaluate expression");
assert(EvalResult.Val.isInt() && "Expression did not evaluate to integer");
return EvalResult.Val.getInt();
}