Adjust r194296 to not apply the alias replacement for externally

available always-inline functions. This breaks libc++'s locale
implementation. Code generation for this case should be fixed, but this
is a stop gap fix for clang 3.4.

llvm-svn: 195501

1 files changed, 8 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp
index 22baa654084..cfb2d6291b8 100644
--- a/clang/lib/CodeGen/CGCXX.cpp
+++ b/clang/lib/CodeGen/CGCXX.cpp
@@ -140,7 +140,14 @@ bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl,
 
   // Instead of creating as alias to a linkonce_odr, replace all of the uses
   // of the aliassee.
-  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage)) {
+  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) &&
+     (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage ||
+      !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) {
+    // FIXME: An extern template instanciation will create functions with
+    // linkage "AvailableExternally". In libc++, some classes also define
+    // members with attribute "AlwaysInline" and expect no reference to
+    // be generated. It is desirable to reenable this optimisation after
+    // corresponding LLVM changes.
     Replacements[MangledName] = Aliasee;
     return false;
   }