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Do not emit thunks with available_externally linkage in comdats

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Functions with available_externally linkage will not be emitted to object
files (they will just be undefined symbols), so it does not make sense to
put them in comdats.

Creates a second overload of maybeSetTrivialComdat that uses the GlobalObject
instead of the Decl, and uses that in several places that had the faulty
logic.

Differential Revision: http://reviews.llvm.org/D9580

llvm-svn: 236879
This commit is contained in:
Derek Schuff
2015-05-08 16:47:21 +00:00
parent 049887b252
commit 2312bd3811
7 changed files with 47 additions and 28 deletions
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23
clang/lib/CodeGen/CodeGenModule.cpp
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@@ -1298,8 +1298,7 @@ llvm::Constant *CodeGenModule::GetAddrOfUuidDescriptor(
auto *GV = new llvm::GlobalVariable(
getModule(), Init->getType(),
/*isConstant=*/true, llvm::GlobalValue::LinkOnceODRLinkage, Init, Name);
if (supportsCOMDAT())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
maybeSetTrivialComdat(*GV);
return GV;
}
@@ -1850,9 +1849,7 @@ CodeGenModule::CreateOrReplaceCXXRuntimeVariable(StringRef Name,
OldGV->eraseFromParent();
}
if (supportsCOMDAT() && GV->isWeakForLinker() &&
!GV->hasAvailableExternallyLinkage())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
maybeSetTrivialComdat(*GV);
return GV;
}
@@ -1985,6 +1982,14 @@ void CodeGenModule::maybeSetTrivialComdat(const Decl &D,
GO.setComdat(TheModule.getOrInsertComdat(GO.getName()));
}
void CodeGenModule::maybeSetTrivialComdat(llvm::GlobalObject &GO) {
if (!supportsCOMDAT())
return;
if (GO.isWeakForLinker() && !GO.hasAvailableExternallyLinkage()) {
GO.setComdat(getModule().getOrInsertComdat(GO.getName()));
}
}
void CodeGenModule::EmitGlobalVarDefinition(const VarDecl *D) {
llvm::Constant *Init = nullptr;
QualType ASTTy = D->getType();
@@ -2924,10 +2929,7 @@ GenerateStringLiteral(llvm::Constant *C, llvm::GlobalValue::LinkageTypes LT,
nullptr, llvm::GlobalVariable::NotThreadLocal, AddrSpace);
GV->setAlignment(Alignment);
GV->setUnnamedAddr(true);
if (GV->isWeakForLinker()) {
assert(CGM.supportsCOMDAT() && "Only COFF uses weak string literals");
GV->setComdat(M.getOrInsertComdat(GV->getName()));
}
CGM.maybeSetTrivialComdat(*GV);
return GV;
}
@@ -3109,8 +3111,7 @@ llvm::Constant *CodeGenModule::GetAddrOfGlobalTemporary(
setGlobalVisibility(GV, VD);
GV->setAlignment(
getContext().getTypeAlignInChars(MaterializedType).getQuantity());
if (supportsCOMDAT() && GV->isWeakForLinker())
GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
maybeSetTrivialComdat(*GV);
if (VD->getTLSKind())
setTLSMode(GV, *VD);
Slot = GV;