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Constant expression evaluation: evaluate lvalues as lvalues, and rvalues as 

rvalues, as C++11 constant evaluation semantics require. DeclRefs referring to
references can now use the normal initialization-caching codepath, which
incidentally fixes a crash in cyclic initialization of references.

llvm-svn: 142844
This commit is contained in:
Richard Smith 2011-10-24 21:07:08 +00:00
parent a58fb48a55
commit cbb407268e
3 changed files with 242 additions and 162 deletions
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3
clang/include/clang/AST/Expr.h
View File

@ -465,7 +465,8 @@ public:
/// 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.
/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
/// will be applied.
bool Evaluate(EvalResult &Result, const ASTContext &Ctx) const;
/// EvaluateAsBooleanCondition - Return true if this is a constant

398
clang/lib/AST/ExprConstant.cpp
View File

@ -151,7 +151,7 @@ static bool IsGlobalLValue(const Expr* E) {
return true;
}
static bool EvalPointerValueAsBool(LValue& Value, bool& Result) {
static bool EvalPointerValueAsBool(const LValue &Value, bool &Result) {
const Expr* Base = Value.Base;
// A null base expression indicates a null pointer. These are always
@ -183,40 +183,44 @@ static bool EvalPointerValueAsBool(LValue& Value, bool& Result) {
return true;
}
static bool HandleConversionToBool(const Expr* E, bool& Result,
EvalInfo &Info) {
if (E->getType()->isIntegralOrEnumerationType()) {
APSInt IntResult;
if (!EvaluateInteger(E, IntResult, Info))
return false;
Result = IntResult != 0;
static bool HandleConversionToBool(const APValue &Val, bool &Result) {
switch (Val.getKind()) {
case APValue::Uninitialized:
return false;
case APValue::Int:
Result = Val.getInt().getBoolValue();
return true;
} else if (E->getType()->isRealFloatingType()) {
APFloat FloatResult(0.0);
if (!EvaluateFloat(E, FloatResult, Info))
return false;
Result = !FloatResult.isZero();
case APValue::Float:
Result = !Val.getFloat().isZero();
return true;
} else if (E->getType()->hasPointerRepresentation()) {
LValue PointerResult;
if (!EvaluatePointer(E, PointerResult, Info))
return false;
return EvalPointerValueAsBool(PointerResult, Result);
} else if (E->getType()->isAnyComplexType()) {
ComplexValue 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();
case APValue::ComplexInt:
Result = Val.getComplexIntReal().getBoolValue() ||
Val.getComplexIntImag().getBoolValue();
return true;
case APValue::ComplexFloat:
Result = !Val.getComplexFloatReal().isZero() ||
!Val.getComplexFloatImag().isZero();
return true;
case APValue::LValue:
{
LValue PointerResult;
PointerResult.setFrom(Val);
return EvalPointerValueAsBool(PointerResult, Result);
}
return true;
case APValue::Vector:
return false;
}
return false;
llvm_unreachable("unknown APValue kind");
}
static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result,
EvalInfo &Info) {
assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition");
APValue Val;
if (!Evaluate(Val, Info, E))
return false;
return HandleConversionToBool(Val, Result);
}
static APSInt HandleFloatToIntCast(QualType DestType, QualType SrcType,
@ -278,10 +282,11 @@ static APValue *EvaluateVarDeclInit(EvalInfo &Info, const VarDecl *VD) {
VD->setEvaluatingValue();
// FIXME: If the initializer isn't a constant expression, propagate up any
// diagnostic explaining why not.
Expr::EvalResult EResult;
if (Init->Evaluate(EResult, Info.Ctx) && !EResult.HasSideEffects)
EvalInfo InitInfo(Info.Ctx, EResult);
// FIXME: The caller will need to know whether the value was a constant
// expression. If not, we should propagate up a diagnostic.
if (Evaluate(EResult.Val, InitInfo, Init))
VD->setEvaluatedValue(EResult.Val);
else
VD->setEvaluatedValue(APValue());
@ -294,6 +299,52 @@ bool IsConstNonVolatile(QualType T) {
return Quals.hasConst() && !Quals.hasVolatile();
}
bool HandleLValueToRValueConversion(EvalInfo &Info, QualType Type,
const LValue &LValue, APValue &RValue) {
const Expr *Base = LValue.Base;
// FIXME: Indirection through a null pointer deserves a diagnostic.
if (!Base)
return false;
// FIXME: Support accessing subobjects of objects of literal types. A simple
// byte offset is insufficient for C++11 semantics: we need to know how the
// reference was formed (which union member was named, for instance).
// FIXME: Support subobjects of StringLiteral and PredefinedExpr.
if (!LValue.Offset.isZero())
return false;
if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Base)) {
// In C++, const, non-volatile integers initialized with ICEs are ICEs.
// In C, they can also be folded, although they are not ICEs.
// In C++0x, constexpr variables are constant expressions too.
// We allow folding any const variable of literal type initialized with
// a constant expression.
const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl());
if (VD && IsConstNonVolatile(VD->getType()) && Type->isLiteralType()) {
APValue *V = EvaluateVarDeclInit(Info, VD);
if (V && !V->isUninit()) {
RValue = *V;
return true;
}
}
return false;
}
// FIXME: C++11: Support MaterializeTemporaryExpr in LValueExprEvaluator and
// here.
// In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the
// initializer until now for such expressions. Such an expression can't be
// an ICE in C, so this only matters for fold.
if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) {
assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?");
return Evaluate(RValue, Info, CLE->getInitializer());
}
return false;
}
namespace {
class HasSideEffect
: public ConstStmtVisitor<HasSideEffect, bool> {
@ -454,7 +505,7 @@ public:
return DerivedError(E);
bool cond;
if (!HandleConversionToBool(E->getCond(), cond, Info))
if (!EvaluateAsBooleanCondition(E->getCond(), cond, Info))
return DerivedError(E);
return StmtVisitorTy::Visit(cond ? E->getTrueExpr() : E->getFalseExpr());
@ -462,10 +513,10 @@ public:
RetTy VisitConditionalOperator(const ConditionalOperator *E) {
bool BoolResult;
if (!HandleConversionToBool(E->getCond(), BoolResult, Info))
if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info))
return DerivedError(E);
Expr* EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr();
return StmtVisitorTy::Visit(EvalExpr);
}
@ -477,6 +528,9 @@ public:
return DerivedSuccess(*value, E);
}
RetTy VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return StmtVisitorTy::Visit(E->getInitializer());
}
RetTy VisitInitListExpr(const InitListExpr *E) {
if (Info.getLangOpts().CPlusPlus0x) {
if (E->getNumInits() == 0)
@ -493,6 +547,28 @@ public:
return DerivedValueInitialization(E);
}
RetTy VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
break;
case CK_NoOp:
return StmtVisitorTy::Visit(E->getSubExpr());
case CK_LValueToRValue: {
LValue LVal;
if (EvaluateLValue(E->getSubExpr(), LVal, Info)) {
APValue RVal;
if (HandleLValueToRValueConversion(Info, E->getType(), LVal, RVal))
return DerivedSuccess(RVal, E);
}
break;
}
}
return DerivedError(E);
}
/// Visit a value which is evaluated, but whose value is ignored.
void VisitIgnoredValue(const Expr *E) {
APValue Scratch;
@ -505,6 +581,10 @@ public:
//===----------------------------------------------------------------------===//
// LValue Evaluation
//
// This is used for evaluating lvalues (in C and C++), xvalues (in C++11),
// function designators (in C), decl references to void objects (in C), and
// temporaries (if building with -Wno-address-of-temporary).
//===----------------------------------------------------------------------===//
namespace {
class LValueExprEvaluator
@ -542,13 +622,13 @@ public:
bool VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return false;
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_NoOp:
case CK_LValueBitCast:
return Visit(E->getSubExpr());
// FIXME: Support CK_DerivedToBase and friends.
// FIXME: Support CK_DerivedToBase and CK_UncheckedDerivedToBase.
// Reuse PointerExprEvaluator::VisitCastExpr for these.
}
}
@ -557,6 +637,11 @@ public:
};
} // end anonymous namespace
/// Evaluate an expression as an lvalue. This can be legitimately called on
/// expressions which are not glvalues, in a few cases:
/// * function designators in C,
/// * "extern void" objects,
/// * temporaries, if building with -Wno-address-of-temporary.
static bool EvaluateLValue(const Expr* E, LValue& Result, EvalInfo &Info) {
return LValueExprEvaluator(Info, Result).Visit(E);
}
@ -570,22 +655,24 @@ bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
// Reference parameters can refer to anything even if they have an
// "initializer" in the form of a default argument.
if (!isa<ParmVarDecl>(VD)) {
// FIXME: Check whether VD might be overridden!
// Check for recursive initializers of references.
if (PrevDecl == VD)
return Error(E);
PrevDecl = VD;
if (const Expr *Init = VD->getAnyInitializer())
return Visit(Init);
APValue *V = EvaluateVarDeclInit(Info, VD);
if (V && !V->isUninit()) {
assert(V->isLValue() && "reference init not glvalue");
Result.Base = V->getLValueBase();
Result.Offset = V->getLValueOffset();
return true;
}
}
}
return ExprEvaluatorBaseTy::VisitDeclRefExpr(E);
return Error(E);
}
bool
LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
assert(!Info.getLangOpts().CPlusPlus && "lvalue compound literal in c++?");
// Defer visiting the literal until the lvalue-to-rvalue conversion. We can
// only see this when folding in C, so there's no standard to follow here.
return Success(E);
}
@ -617,6 +704,10 @@ bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) {
}
bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) {
// FIXME: Deal with vectors as array subscript bases.
if (E->getBase()->getType()->isVectorType())
return false;
if (!EvaluatePointer(E->getBase(), Result, Info))
return false;
@ -684,7 +775,7 @@ public:
} // end anonymous namespace
static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info) {
assert(E->getType()->hasPointerRepresentation());
assert(E->isRValue() && E->getType()->hasPointerRepresentation());
return PointerExprEvaluator(Info, Result).Visit(E);
}
@ -740,7 +831,6 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
default:
break;
case CK_NoOp:
case CK_BitCast:
case CK_CPointerToObjCPointerCast:
case CK_BlockPointerToObjCPointerCast:
@ -810,7 +900,7 @@ bool PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
return EvaluateLValue(SubExpr, Result, Info);
}
return false;
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) {
@ -852,7 +942,6 @@ namespace {
bool VisitUnaryReal(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
bool VisitCastExpr(const CastExpr* E);
bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E);
bool VisitInitListExpr(const InitListExpr *E);
bool VisitUnaryImag(const UnaryOperator *E);
// FIXME: Missing: unary -, unary ~, binary add/sub/mul/div,
@ -864,8 +953,7 @@ namespace {
} // end anonymous namespace
static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) {
if (!E->getType()->isVectorType())
return false;
assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue");
return VectorExprEvaluator(Info, Result).Visit(E);
}
@ -927,19 +1015,11 @@ bool VectorExprEvaluator::VisitCastExpr(const CastExpr* E) {
}
return Success(Elts, E);
}
case CK_LValueToRValue:
case CK_NoOp:
return Visit(SE);
default:
return Error(E);
return ExprEvaluatorBaseTy::VisitCastExpr(E);
}
}
bool
VectorExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) {
return Visit(E->getInitializer());
}
bool
VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) {
const VectorType *VT = E->getType()->castAs<VectorType>();
@ -1022,6 +1102,10 @@ bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) {
//===----------------------------------------------------------------------===//
// Integer Evaluation
//
// As a GNU extension, we support casting pointers to sufficiently-wide integer
// types and back in constant folding. Integer values are thus represented
// either as an integer-valued APValue, or as an lvalue-valued APValue.
//===----------------------------------------------------------------------===//
namespace {
@ -1105,8 +1189,7 @@ public:
}
bool VisitMemberExpr(const MemberExpr *E) {
if (CheckReferencedDecl(E, E->getMemberDecl())) {
// Conservatively assume a MemberExpr will have side-effects
Info.EvalStatus.HasSideEffects = true;
VisitIgnoredValue(E->getBase());
return true;
}
@ -1161,14 +1244,20 @@ private:
};
} // end anonymous namespace
/// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and
/// produce either the integer value or a pointer.
///
/// GCC has a heinous extension which folds casts between pointer types and
/// pointer-sized integral types. We support this by allowing the evaluation of
/// an integer rvalue to produce a pointer (represented as an lvalue) instead.
/// Some simple arithmetic on such values is supported (they are treated much
/// like char*).
static bool EvaluateIntegerOrLValue(const Expr* E, APValue &Result, EvalInfo &Info) {
assert(E->getType()->isIntegralOrEnumerationType());
assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType());
return IntExprEvaluator(Info, Result).Visit(E);
}
static bool EvaluateInteger(const Expr* E, APSInt &Result, EvalInfo &Info) {
assert(E->getType()->isIntegralOrEnumerationType());
APValue Val;
if (!EvaluateIntegerOrLValue(E, Val, Info) || !Val.isInt())
return false;
@ -1197,18 +1286,6 @@ bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) {
return Success(Val, 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 (IsConstNonVolatile(E->getType())) {
if (const VarDecl *VD = dyn_cast<VarDecl>(D)) {
APValue *V = EvaluateVarDeclInit(Info, VD);
if (V && V->isInt())
return Success(V->getInt(), E);
}
}
// Otherwise, random variable references are not constants.
return false;
}
@ -1411,6 +1488,9 @@ bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) {
}
bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (E->isAssignmentOp())
return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
if (E->getOpcode() == BO_Comma) {
VisitIgnoredValue(E->getLHS());
return Visit(E->getRHS());
@ -1421,20 +1501,20 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
// necessarily integral
bool lhsResult, rhsResult;
if (HandleConversionToBool(E->getLHS(), lhsResult, Info)) {
if (EvaluateAsBooleanCondition(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() == BO_LOr))
return Success(lhsResult, E);
if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
if (EvaluateAsBooleanCondition(E->getRHS(), rhsResult, Info)) {
if (E->getOpcode() == BO_LOr)
return Success(lhsResult || rhsResult, E);
else
return Success(lhsResult && rhsResult, E);
}
} else {
if (HandleConversionToBool(E->getRHS(), rhsResult, Info)) {
if (EvaluateAsBooleanCondition(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() == BO_LOr) ||
@ -1590,58 +1670,60 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
}
// The LHS of a constant expr is always evaluated and needed.
if (!Visit(E->getLHS()))
APValue LHSVal;
if (!EvaluateIntegerOrLValue(E->getLHS(), LHSVal, Info))
return false; // error in subexpression.
APValue RHSVal;
if (!EvaluateIntegerOrLValue(E->getRHS(), RHSVal, Info))
if (!Visit(E->getRHS()))
return false;
APValue &RHSVal = Result;
// Handle cases like (unsigned long)&a + 4.
if (E->isAdditiveOp() && Result.isLValue() && RHSVal.isInt()) {
CharUnits Offset = Result.getLValueOffset();
if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) {
CharUnits Offset = LHSVal.getLValueOffset();
CharUnits AdditionalOffset = CharUnits::fromQuantity(
RHSVal.getInt().getZExtValue());
if (E->getOpcode() == BO_Add)
Offset += AdditionalOffset;
else
Offset -= AdditionalOffset;
Result = APValue(Result.getLValueBase(), Offset);
Result = APValue(LHSVal.getLValueBase(), Offset);
return true;
}
// Handle cases like 4 + (unsigned long)&a
if (E->getOpcode() == BO_Add &&
RHSVal.isLValue() && Result.isInt()) {
RHSVal.isLValue() && LHSVal.isInt()) {
CharUnits Offset = RHSVal.getLValueOffset();
Offset += CharUnits::fromQuantity(Result.getInt().getZExtValue());
Offset += CharUnits::fromQuantity(LHSVal.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())
if (!LHSVal.isInt() || !RHSVal.isInt())
return false;
APSInt& RHS = RHSVal.getInt();
APSInt &LHS = LHSVal.getInt();
APSInt &RHS = RHSVal.getInt();
switch (E->getOpcode()) {
default:
return Error(E->getOperatorLoc(), diag::note_invalid_subexpr_in_ice, E);
case BO_Mul: return Success(Result.getInt() * RHS, E);
case BO_Add: return Success(Result.getInt() + RHS, E);
case BO_Sub: return Success(Result.getInt() - RHS, E);
case BO_And: return Success(Result.getInt() & RHS, E);
case BO_Xor: return Success(Result.getInt() ^ RHS, E);
case BO_Or: return Success(Result.getInt() | RHS, E);
case BO_Mul: return Success(LHS * RHS, E);
case BO_Add: return Success(LHS + RHS, E);
case BO_Sub: return Success(LHS - RHS, E);
case BO_And: return Success(LHS & RHS, E);
case BO_Xor: return Success(LHS ^ RHS, E);
case BO_Or: return Success(LHS | RHS, E);
case BO_Div:
if (RHS == 0)
return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
return Success(Result.getInt() / RHS, E);
return Success(LHS / RHS, E);
case BO_Rem:
if (RHS == 0)
return Error(E->getOperatorLoc(), diag::note_expr_divide_by_zero, E);
return Success(Result.getInt() % RHS, E);
return Success(LHS % RHS, E);
case BO_Shl: {
// During constant-folding, a negative shift is an opposite shift.
if (RHS.isSigned() && RHS.isNegative()) {
@ -1651,8 +1733,8 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
shift_left:
unsigned SA
= (unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
return Success(Result.getInt() << SA, E);
= (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
return Success(LHS << SA, E);
}
case BO_Shr: {
// During constant-folding, a negative shift is an opposite shift.
@ -1663,16 +1745,16 @@ bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
shift_right:
unsigned SA =
(unsigned) RHS.getLimitedValue(Result.getInt().getBitWidth()-1);
return Success(Result.getInt() >> SA, E);
(unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1);
return Success(LHS >> SA, E);
}
case BO_LT: return Success(Result.getInt() < RHS, E);
case BO_GT: return Success(Result.getInt() > RHS, E);
case BO_LE: return Success(Result.getInt() <= RHS, E);
case BO_GE: return Success(Result.getInt() >= RHS, E);
case BO_EQ: return Success(Result.getInt() == RHS, E);
case BO_NE: return Success(Result.getInt() != RHS, E);
case BO_LT: return Success(LHS < RHS, E);
case BO_GT: return Success(LHS > RHS, E);
case BO_LE: return Success(LHS <= RHS, E);
case BO_GE: return Success(LHS >= RHS, E);
case BO_EQ: return Success(LHS == RHS, E);
case BO_NE: return Success(LHS != RHS, E);
}
}
@ -1833,7 +1915,7 @@ bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
if (E->getOpcode() == UO_LNot) {
// LNot's operand isn't necessarily an integer, so we handle it specially.
bool bres;
if (!HandleConversionToBool(E->getSubExpr(), bres, Info))
if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info))
return false;
return Success(!bres, E);
}
@ -1918,7 +2000,7 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
case CK_LValueToRValue:
case CK_NoOp:
return Visit(E->getSubExpr());
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_MemberPointerToBoolean:
case CK_PointerToBoolean:
@ -1927,7 +2009,7 @@ bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) {
case CK_FloatingComplexToBoolean:
case CK_IntegralComplexToBoolean: {
bool BoolResult;
if (!HandleConversionToBool(SubExpr, BoolResult, Info))
if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info))
return false;
return Success(BoolResult, E);
}
@ -2050,15 +2132,13 @@ public:
bool VisitUnaryReal(const UnaryOperator *E);
bool VisitUnaryImag(const UnaryOperator *E);
bool VisitDeclRefExpr(const DeclRefExpr *E);
// FIXME: Missing: array subscript of vector, member of vector,
// ImplicitValueInitExpr
};
} // end anonymous namespace
static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) {
assert(E->getType()->isRealFloatingType());
assert(E->isRValue() && E->getType()->isRealFloatingType());
return FloatExprEvaluator(Info, Result).Visit(E);
}
@ -2141,21 +2221,6 @@ bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) {
}
}
bool FloatExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) {
if (ExprEvaluatorBaseTy::VisitDeclRefExpr(E))
return true;
const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl());
if (VD && IsConstNonVolatile(VD->getType())) {
APValue *V = EvaluateVarDeclInit(Info, VD);
if (V && V->isFloat()) {
Result = V->getFloat();
return true;
}
}
return false;
}
bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) {
if (E->getSubExpr()->getType()->isAnyComplexType()) {
ComplexValue CV;
@ -2245,11 +2310,7 @@ bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) {
switch (E->getCastKind()) {
default:
return false;
case CK_LValueToRValue:
case CK_NoOp:
return Visit(SubExpr);
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_IntegralToFloating: {
APSInt IntResult;
@ -2317,7 +2378,7 @@ public:
static bool EvaluateComplex(const Expr *E, ComplexValue &Result,
EvalInfo &Info) {
assert(E->getType()->isAnyComplexType());
assert(E->isRValue() && E->getType()->isAnyComplexType());
return ComplexExprEvaluator(Info, Result).Visit(E);
}
@ -2390,7 +2451,7 @@ bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) {
case CK_LValueToRValue:
case CK_NoOp:
return Visit(E->getSubExpr());
return ExprEvaluatorBaseTy::VisitCastExpr(E);
case CK_Dependent:
case CK_GetObjCProperty:
@ -2634,27 +2695,28 @@ bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) {
//===----------------------------------------------------------------------===//
static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
if (E->getType()->isVectorType()) {
// In C, function designators are not lvalues, but we evaluate them as if they
// are.
if (E->isGLValue() || E->getType()->isFunctionType()) {
LValue LV;
if (!EvaluateLValue(E, LV, Info))
return false;
LV.moveInto(Result);
} else if (E->getType()->isVectorType()) {
if (!EvaluateVector(E, Result, Info))
return false;
} else if (E->getType()->isIntegralOrEnumerationType()) {
if (!IntExprEvaluator(Info, Result).Visit(E))
return false;
if (Result.isLValue() &&
!IsGlobalLValue(Result.getLValueBase()))
return false;
} else if (E->getType()->hasPointerRepresentation()) {
LValue LV;
if (!EvaluatePointer(E, LV, Info))
return false;
if (!IsGlobalLValue(LV.Base))
return false;
LV.moveInto(Result);
} else if (E->getType()->isRealFloatingType()) {
llvm::APFloat F(0.0);
if (!EvaluateFloat(E, F, Info))
return false;
Result = APValue(F);
} else if (E->getType()->isAnyComplexType()) {
ComplexValue C;
@ -2670,25 +2732,43 @@ static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) {
/// 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.
/// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion
/// will be applied to the result.
bool Expr::Evaluate(EvalResult &Result, const ASTContext &Ctx) const {
EvalInfo Info(Ctx, Result);
return ::Evaluate(Result.Val, Info, this);
if (!::Evaluate(Result.Val, Info, this))
return false;
if (isGLValue()) {
LValue LV;
LV.setFrom(Result.Val);
return HandleLValueToRValueConversion(Info, getType(), LV, Result.Val);
} else if (Result.Val.isLValue()) {
// FIXME: We don't allow expressions to fold to references to locals. Code
// which calls Evaluate() isn't ready for that yet. For instance, we don't
// have any checking that the initializer of a pointer in C is an address
// constant.
if (!IsGlobalLValue(Result.Val.getLValueBase()))
return false;
}
return true;
}
bool Expr::EvaluateAsBooleanCondition(bool &Result,
const ASTContext &Ctx) const {
EvalStatus Scratch;
EvalInfo Info(Ctx, Scratch);
return HandleConversionToBool(this, Result, Info);
EvalResult Scratch;
return Evaluate(Scratch, Ctx) && HandleConversionToBool(Scratch.Val, Result);
}
bool Expr::EvaluateAsInt(APSInt &Result, const ASTContext &Ctx) const {
EvalStatus Scratch;
EvalInfo Info(Ctx, Scratch);
return EvaluateInteger(this, Result, Info) && !Scratch.HasSideEffects;
EvalResult ExprResult;
if (!Evaluate(ExprResult, Ctx) || ExprResult.HasSideEffects ||
!ExprResult.Val.isInt())
return false;
Result = ExprResult.Val.getInt();
return true;
}
bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx) const {
@ -3184,11 +3264,7 @@ bool Expr::isIntegerConstantExpr(llvm::APSInt &Result, ASTContext &Ctx,
if (Loc) *Loc = d.Loc;
return false;
}
EvalResult EvalResult;
if (!Evaluate(EvalResult, Ctx))
if (!EvaluateAsInt(Result, Ctx))
llvm_unreachable("ICE cannot be evaluated!");
assert(!EvalResult.HasSideEffects && "ICE with side effects!");
assert(EvalResult.Val.isInt() && "ICE that isn't integer!");
Result = EvalResult.Val.getInt();
return true;
}

3
clang/test/SemaCXX/i-c-e-cxx.cpp
View File

@ -66,3 +66,6 @@ const int nonconst = 1.0;
int arr[nonconst]; // expected-warning {{folded to constant array as an extension}}
const int castfloat = static_cast<int>(1.0);
int arr2[castfloat]; // ok
extern const int &Recurse1;
const int &Recurse2 = Recurse1, &Recurse1 = Recurse2;