[CodeGenModule] Set dso_local for Mach-O GlobalValue

* static relocation model: always
* other relocation models: if isStrongDefinitionForLinker

This will make LLVM IR emitted for COFF/Mach-O and executable ELF similar.

1 files changed, 10 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 6d14298..bf0a38b 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -946,14 +946,20 @@ static bool shouldAssumeDSOLocal(const CodeGenModule &CGM,
   if (TT.isOSBinFormatCOFF() || (TT.isOSWindows() && TT.isOSBinFormatMachO()))
     return true;
 
+  const auto &CGOpts = CGM.getCodeGenOpts();
+  llvm::Reloc::Model RM = CGOpts.RelocationModel;
+  const auto &LOpts = CGM.getLangOpts();
+
+  if (TT.isOSBinFormatMachO()) {
+    if (RM == llvm::Reloc::Static)
+      return true;
+    return GV->isStrongDefinitionForLinker();
+  }
+
   // Only handle COFF and ELF for now.
   if (!TT.isOSBinFormatELF())
     return false;
 
-  // If this is not an executable, don't assume anything is local.
-  const auto &CGOpts = CGM.getCodeGenOpts();
-  llvm::Reloc::Model RM = CGOpts.RelocationModel;
-  const auto &LOpts = CGM.getLangOpts();
   if (RM != llvm::Reloc::Static && !LOpts.PIE) {
     // On ELF, if -fno-semantic-interposition is specified, we can set dso_local
     // if using a local alias is preferable (can avoid GOT indirection).