Revert D135427 "[LTO] Make local linkage GlobalValue in non-prevailing COMDAT available_externally"

This reverts commit 8ef3fd8d59ba0100bc6e83350ab1e978536aa531.

I mentioned that GlobalAlias was not handled. It turns out GlobalAlias has to be handled in the same patch (as opposed to in a follow-up),
as otherwise clang codegen of C5/D5 constructor/destructor would regress (https://reviews.llvm.org/D135427#3869003).

1 files changed, 5 insertions, 5 deletions

diff --git a/llvm/lib/LTO/LTO.cpp b/llvm/lib/LTO/LTO.cpp
index dc28b68..286d3ca 100644
--- a/llvm/lib/LTO/LTO.cpp
+++ b/llvm/lib/LTO/LTO.cpp
@@ -712,11 +712,11 @@ handleNonPrevailingComdat(GlobalValue &GV,
   if (!NonPrevailingComdats.count(C))
     return;
 
-  // Additionally need to drop all global values from the comdat to
-  // available_externally, to satisfy the COMDAT requirement that all members
-  // are discarded as a unit. The non-local linkage global values avoid
-  // duplicate definition linker errors.
-  GV.setLinkage(GlobalValue::AvailableExternallyLinkage);
+  // Additionally need to drop externally visible global values from the comdat
+  // to available_externally, so that there aren't multiply defined linker
+  // errors.
+  if (!GV.hasLocalLinkage())
+    GV.setLinkage(GlobalValue::AvailableExternallyLinkage);
 
   if (auto GO = dyn_cast<GlobalObject>(&GV))
     GO->setComdat(nullptr);