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Evaluate: Fix a subtle bug in the pointer evaluator in which we would do an 

expression computation in the wrong bit-width, and end up generating a totally
bogus array reference (_g0+8589934546).
 - This showed up on Prolangs/cdecl.

llvm-svn: 99042
This commit is contained in:
Daniel Dunbar 2010-03-20 05:53:45 +00:00
parent e46b52a35f
commit 4c43e31d21
2 changed files with 25 additions and 10 deletions
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27
clang/lib/AST/ExprConstant.cpp
View File

@ -406,27 +406,34 @@ APValue PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) {
if (!EvaluatePointer(PExp, ResultLValue, Info))
return APValue();
llvm::APSInt AdditionalOffset(32);
llvm::APSInt AdditionalOffset;
if (!EvaluateInteger(IExp, AdditionalOffset, Info))
return APValue();
QualType PointeeType = PExp->getType()->getAs<PointerType>()->getPointeeType();
CharUnits SizeOfPointee;
// Compute the new offset in the appropriate width.
QualType PointeeType =
PExp->getType()->getAs<PointerType>()->getPointeeType();
llvm::APSInt SizeOfPointee(AdditionalOffset);
// Explicitly handle GNU void* and function pointer arithmetic extensions.
if (PointeeType->isVoidType() || PointeeType->isFunctionType())
SizeOfPointee = CharUnits::One();
SizeOfPointee = 1;
else
SizeOfPointee = Info.Ctx.getTypeSizeInChars(PointeeType);
CharUnits Offset = ResultLValue.getLValueOffset();
SizeOfPointee = Info.Ctx.getTypeSizeInChars(PointeeType).getQuantity();
llvm::APSInt Offset(AdditionalOffset);
Offset = ResultLValue.getLValueOffset().getQuantity();
if (E->getOpcode() == BinaryOperator::Add)
Offset += AdditionalOffset.getLimitedValue() * SizeOfPointee;
Offset += AdditionalOffset * SizeOfPointee;
else
Offset -= AdditionalOffset.getLimitedValue() * SizeOfPointee;
Offset -= AdditionalOffset * SizeOfPointee;
return APValue(ResultLValue.getLValueBase(), Offset);
// Sign extend prior to converting back to a char unit.
if (Offset.getBitWidth() < 64)
Offset.extend(64);
return APValue(ResultLValue.getLValueBase(),
CharUnits::fromQuantity(Offset.getLimitedValue()));
}
APValue PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) {

8
clang/test/CodeGen/const-arithmetic.c Normal file
View File

@ -0,0 +1,8 @@
// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s | FileCheck %s
// CHECK: @g1 = global [2 x i8*] [i8* getelementptr (i8* getelementptr inbounds ([0 x %struct.anon]* @g0, i32 0, i32 0, i32 0), i64 -2), i8* getelementptr (i8* getelementptr inbounds ([0 x %struct.anon]* @g0, i32 0, i32 0, i32 0), i64 -46)], align 8 ; <[2 x i8*]*> [#uses=0]
// CHECK: @g2 = global [2 x i8*] [i8* getelementptr (i8* getelementptr inbounds ([0 x %struct.anon]* @g0, i32 0, i32 0, i32 0), i64 -2), i8* getelementptr (i8* getelementptr inbounds ([0 x %struct.anon]* @g0, i32 0, i32 0, i32 0), i64 -46)], align 8 ; <[2 x i8*]*> [#uses=0]
extern struct { unsigned char a, b; } g0[];
void *g1[] = {g0 + -1, g0 + -23 };
void *g2[] = {g0 - 1, g0 - 23 };