make alias definition logic more similar to functions/globals.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67481 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index f5ce056..21f6790 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -343,8 +343,8 @@
const char *AliaseeName = AA->getAliasee().c_str();
AliaseeName = getContext().Idents.get(AliaseeName).getName();
-
-
+ // Create a reference to the named value. This ensures that it is emitted
+ // if a deferred decl.
llvm::Constant *Aliasee;
if (isa<llvm::FunctionType>(DeclTy))
Aliasee = GetOrCreateLLVMFunction(AliaseeName, DeclTy, 0);
@@ -352,24 +352,41 @@
Aliasee = GetOrCreateLLVMGlobal(AliaseeName,
llvm::PointerType::getUnqual(DeclTy), 0);
- const char *MangledName = getMangledName(D);
+ // Create the new alias itself, but don't set a name yet.
llvm::GlobalValue *GA =
new llvm::GlobalAlias(Aliasee->getType(),
llvm::Function::ExternalLinkage,
- MangledName, Aliasee, &getModule());
+ "", Aliasee, &getModule());
+ // See if there is already something with the alias' name in the module.
+ const char *MangledName = getMangledName(D);
llvm::GlobalValue *&Entry = GlobalDeclMap[MangledName];
- if (Entry) {
- // If we created a dummy function for this then replace it.
- GA->takeName(Entry);
-
- llvm::Value *Casted =
- llvm::ConstantExpr::getBitCast(GA, Entry->getType());
- Entry->replaceAllUsesWith(Casted);
- Entry->eraseFromParent();
-
- Entry = GA;
+
+ if (Entry && !Entry->isDeclaration()) {
+ // If there is a definition in the module, then it wins over the alias.
+ // This is dubious, but allow it to be safe. Just ignore the alias.
+ delete GA;
+ continue;
}
+
+ if (Entry) {
+ // If there is a declaration in the module, then we had an extern followed
+ // by the alias, as in:
+ // extern int test6();
+ // ...
+ // int test6() __attribute__((alias("test7")));
+ //
+ // Remove it and replace uses of it with the alias.
+
+ Entry->replaceAllUsesWith(llvm::ConstantExpr::getBitCast(GA,
+ Entry->getType()));
+ // FIXME: What if it was attribute used? Dangling pointer from LLVMUsed.
+ Entry->eraseFromParent();
+ }
+
+ // Now we know that there is no conflict, set the name.
+ Entry = GA;
+ GA->setName(MangledName);
// Alias should never be internal or inline.
SetGlobalValueAttributes(D, false, false, GA, true);