Don't create a comdat group for a dropped def with initializer

Non-prevailing weak/linkonce odr symbols will be dropped by ThinLTO to
available_externally when possible. If they had an initializer in the
global_ctors list, a comdat group was being created. This code
already had logic to skip available_externally defs, but now the
EliminateAvailableExternally pass will drop these symbols to
declarations earlier. Change the check to skip all declarations for
linker (which includes available_externally along with declarations).

Reviewers: mehdi_amini

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D28737

llvm-svn: 292408

1 files changed, 5 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 9f6caa95a9e..821e336a823 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -1644,8 +1644,11 @@ void AsmPrinter::EmitXXStructorList(const DataLayout &DL, const Constant *List,
     const TargetLoweringObjectFile &Obj = getObjFileLowering();
     const MCSymbol *KeySym = nullptr;
     if (GlobalValue *GV = S.ComdatKey) {
-      if (GV->hasAvailableExternallyLinkage())
-        // If the associated variable is available_externally, some other TU
+      if (GV->isDeclarationForLinker())
+        // If the associated variable is not defined in this module
+        // (it might be available_externally, or have been an
+        // available_externally definition that was dropped by the
+        // EliminateAvailableExternally pass), some other TU
         // will provide its dynamic initializer.
         continue;