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Fix SimplifyLibcalls and ValueTracking to check mayBeOverridden

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before performing optimizations based on constant string values.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79384 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2009-08-19 00:11:12 +00:00
parent 2c9489d6e9
commit 107f41fad5
3 changed files with 30 additions and 2 deletions
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3
lib/Analysis/ValueTracking.cpp
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@ -1061,7 +1061,8 @@ bool llvm::GetConstantStringInfo(Value *V, std::string &Str, uint64_t Offset,
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
GlobalVariable* GV = dyn_cast<GlobalVariable>(V);
if (!GV || !GV->isConstant() || !GV->hasInitializer())
if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
GV->mayBeOverridden())
return false;
Constant *GlobalInit = GV->getInitializer();

3
lib/Transforms/Scalar/SimplifyLibCalls.cpp
View File

@ -438,7 +438,8 @@ static uint64_t GetStringLengthH(Value *V, SmallPtrSet<PHINode*, 32> &PHIs) {
// variable that is a constant and is initialized. The referenced constant
// initializer is the array that we'll use for optimization.
GlobalVariable* GV = dyn_cast<GlobalVariable>(GEP->getOperand(0));
if (!GV || !GV->isConstant() || !GV->hasInitializer())
if (!GV || !GV->isConstant() || !GV->hasInitializer() ||
GV->mayBeOverridden())
return 0;
Constant *GlobalInit = GV->getInitializer();

26
test/Transforms/SimplifyLibCalls/weak-symbols.ll Normal file
View File

@ -0,0 +1,26 @@
; RUN: llvm-as < %s | opt -simplify-libcalls | llvm-dis | FileCheck %s
; PR4738
; SimplifyLibcalls shouldn't assume anything about weak symbols.
@real_init = weak_odr constant [2 x i8] c"y\00"
@fake_init = weak constant [2 x i8] c"y\00"
@.str = private constant [2 x i8] c"y\00"
; CHECK: define i32 @foo
; CHECK: call i32 @strcmp
define i32 @foo() nounwind {
entry:
%t0 = call i32 @strcmp(i8* getelementptr inbounds ([2 x i8]* @fake_init, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8]* @.str, i64 0, i64 0)) nounwind readonly
ret i32 %t0
}
; CHECK: define i32 @bar
; CHECK: ret i32 0
define i32 @bar() nounwind {
entry:
%t0 = call i32 @strcmp(i8* getelementptr inbounds ([2 x i8]* @real_init, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8]* @.str, i64 0, i64 0)) nounwind readonly
ret i32 %t0
}
declare i32 @strcmp(i8*, i8*) nounwind readonly