From 4b9d964925d3b8c798185c8f66c22d3f11e40537 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Fri, 24 Oct 2014 22:05:27 +0000
Subject: CodeGen: Don't form weak dllexport aliases

The MS linker cannot do anything interesting with these, it doesn't make
sense to emit them.

This fixes PR21373.

Differential Revision: http://reviews.llvm.org/D5986

llvm-svn: 220595
---
 clang/lib/CodeGen/CGCXX.cpp | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'clang/lib/CodeGen/CGCXX.cpp')

diff --git a/clang/lib/CodeGen/CGCXX.cpp b/clang/lib/CodeGen/CGCXX.cpp
index 93e17601cc6..a590afae0b3 100644
--- a/clang/lib/CodeGen/CGCXX.cpp
+++ b/clang/lib/CodeGen/CGCXX.cpp
@@ -119,6 +119,11 @@ bool CodeGenModule::TryEmitDefinitionAsAlias(GlobalDecl AliasDecl,
   if (!llvm::GlobalAlias::isValidLinkage(Linkage))
     return true;
 
+  // Don't create a weak alias for a dllexport'd symbol.
+  if (AliasDecl.getDecl()->hasAttr<DLLExportAttr>() &&
+      llvm::GlobalValue::isWeakForLinker(Linkage))
+    return true;
+
   llvm::GlobalValue::LinkageTypes TargetLinkage =
       getFunctionLinkage(TargetDecl);
 
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