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Fix PointerExprEvaluator::VisitCastExpr so it doesn't misfold C++ casts which 

it doesn't know how to fold, like derived-to-base casts.

llvm-svn: 92173
This commit is contained in:
Eli Friedman 2009-12-27 05:43:15 +00:00
parent af76ad73ed
commit 847a2bce04
2 changed files with 53 additions and 25 deletions
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67
clang/lib/AST/ExprConstant.cpp
View File

@ -222,7 +222,6 @@ public:
APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
APValue VisitDeclRefExpr(DeclRefExpr *E);
APValue VisitBlockExpr(BlockExpr *E);
APValue VisitPredefinedExpr(PredefinedExpr *E) { return APValue(E, 0); }
APValue VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
APValue VisitMemberExpr(MemberExpr *E);
@ -270,13 +269,6 @@ APValue LValueExprEvaluator::VisitDeclRefExpr(DeclRefExpr *E) {
return APValue();
}
APValue LValueExprEvaluator::VisitBlockExpr(BlockExpr *E) {
if (E->hasBlockDeclRefExprs())
return APValue();
return APValue(E, 0);
}
APValue LValueExprEvaluator::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
if (!Info.AnyLValue && !E->isFileScope())
return APValue();
@ -366,7 +358,7 @@ public:
APValue VisitParenExpr(ParenExpr *E) { return Visit(E->getSubExpr()); }
APValue VisitBinaryOperator(const BinaryOperator *E);
APValue VisitCastExpr(const CastExpr* E);
APValue VisitCastExpr(CastExpr* E);
APValue VisitUnaryExtension(const UnaryOperator *E)
{ return Visit(E->getSubExpr()); }
APValue VisitUnaryAddrOf(const UnaryOperator *E);
@ -443,23 +435,49 @@ APValue PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {
}
APValue PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
const Expr* SubExpr = E->getSubExpr();
APValue PointerExprEvaluator::VisitCastExpr(CastExpr* E) {
Expr* SubExpr = E->getSubExpr();
// Check for pointer->pointer cast
if (SubExpr->getType()->isPointerType() ||
SubExpr->getType()->isObjCObjectPointerType() ||
SubExpr->getType()->isNullPtrType()) {
APValue Result;
if (EvaluatePointer(SubExpr, Result, Info))
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, Result.getInt().getZExtValue());
}
// Cast is of an lvalue, no need to change value.
return Result;
return APValue();
}
break;
}
if (SubExpr->getType()->isIntegralType()) {
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))
return APValue();
break;
if (Result.isInt()) {
Result.getInt().extOrTrunc((unsigned)Info.Ctx.getTypeSize(E->getType()));
@ -469,14 +487,13 @@ APValue PointerExprEvaluator::VisitCastExpr(const CastExpr* E) {
// Cast is of an lvalue, no need to change value.
return Result;
}
if (SubExpr->getType()->isFunctionType() ||
SubExpr->getType()->isBlockPointerType() ||
SubExpr->getType()->isArrayType()) {
case CastExpr::CK_ArrayToPointerDecay:
case CastExpr::CK_FunctionToPointerDecay: {
APValue Result;
if (EvaluateLValue(SubExpr, Result, Info))
return Result;
return APValue();
break;
}
}
return APValue();

11
clang/test/CodeGenCXX/const-base-cast.cpp Normal file
View File

@ -0,0 +1,11 @@
// RUN: clang -cc1 -O1 -emit-llvm %s -o - | FileCheck %s
// Check that the following construct, which is similar to one which occurs
// in Firefox, is not misfolded (folding it correctly would be a bonus, but
// that doesn't work at the moment, hence the -O1 in the runline).
struct A { char x; };
struct B { char y; };
struct C : A,B {};
unsigned char x = ((char*)(B*)(C*)0x1000) - (char*)0x1000;
// CHECK: @x = global i8 1