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Re-fix the issue Bill fixed in r147899 in a slightly different way, which doesn't abuse the semantics of linker_private. We don't really want to merge any string constant with a weak_odr global. 

llvm-svn: 147971
This commit is contained in:
Eli Friedman 2012-01-11 22:06:46 +00:00
parent 9ac4562bea
commit b31c627be1
2 changed files with 7 additions and 15 deletions
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10
llvm/include/llvm/GlobalValue.h
View File

@ -192,14 +192,6 @@ public:
Linkage == LinkerPrivateWeakDefAutoLinkage;
}
/// mayBeRemovedByLinker - Whether the definition of this global may be
/// removed at link time.
static bool mayBeRemovedByLinker(LinkageTypes Linkage) {
return isLinkerPrivateLinkage(Linkage) ||
isLinkerPrivateWeakLinkage(Linkage) ||
isLinkerPrivateWeakDefAutoLinkage(Linkage);
}
bool hasExternalLinkage() const { return isExternalLinkage(Linkage); }
bool hasAvailableExternallyLinkage() const {
return isAvailableExternallyLinkage(Linkage);
@ -233,8 +225,6 @@ public:
bool isWeakForLinker() const { return isWeakForLinker(Linkage); }
bool mayBeRemovedByLinker() const { return mayBeRemovedByLinker(Linkage); }
/// copyAttributesFrom - copy all additional attributes (those not needed to
/// create a GlobalValue) from the GlobalValue Src to this one.
virtual void copyAttributesFrom(const GlobalValue *Src);

12
llvm/lib/Transforms/IPO/ConstantMerge.cpp
View File

@ -140,8 +140,11 @@ bool ConstantMerge::runOnModule(Module &M) {
UsedGlobals.count(GV))
continue;
// Ignore any constants which may be removed by the linker.
if (GV->mayBeRemovedByLinker())
// This transformation is legal for weak ODR globals in the sense it
// doesn't change semantics, but we really don't want to perform it
// anyway; it's likely to pessimize code generation, and some tools
// (like the Darwin linker in cases involving CFString) don't expect it.
if (GV->isWeakForLinker())
continue;
Constant *Init = GV->getInitializer();
@ -172,9 +175,8 @@ bool ConstantMerge::runOnModule(Module &M) {
UsedGlobals.count(GV))
continue;
// We can only replace constants with local linkage and which aren't
// removed by the linker.
if (!GV->hasLocalLinkage() || GV->mayBeRemovedByLinker())
// We can only replace constant with local linkage.
if (!GV->hasLocalLinkage())
continue;
Constant *Init = GV->getInitializer();