Revert "Always_inline codegen rewrite" and 2 follow-ups.

Revert "Update cxx-irgen.cpp test to allow signext in alwaysinline functions."
Revert "[CodeGen] Remove wrapper-free always_inline functions from COMDATs"
Revert "Always_inline codegen rewrite."

Reason for revert: PR24793.

llvm-svn: 247620

1 files changed, 8 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp
index 592b74f1909..ea32e382705 100644
--- a/clang/lib/CodeGen/CGCXX.cpp
+++ b/clang/lib/CodeGen/CGCXX.cpp
@@ -109,9 +109,6 @@ bool CodeGenModule::TryEmitBaseDestructorAsAlias(const CXXDestructorDecl *D) {
       D->getType()->getAs<FunctionType>()->getCallConv())
     return true;
 
-  if (BaseD->hasAttr<AlwaysInlineAttr>())
-    return true;
-
   return TryEmitDefinitionAsAlias(GlobalDecl(D, Dtor_Base),
                                   GlobalDecl(BaseD, Dtor_Base),
                                   false);
@@ -164,7 +161,14 @@ bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl,
 
   // Instead of creating as alias to a linkonce_odr, replace all of the uses
   // of the aliasee.
-  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage)) {
+  if (llvm::GlobalValue::isDiscardableIfUnused(Linkage) &&
+     (TargetLinkage != llvm::GlobalValue::AvailableExternallyLinkage ||
+      !TargetDecl.getDecl()->hasAttr<AlwaysInlineAttr>())) {
+    // FIXME: An extern template instantiation 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;
   }