ThinLTO/ModuleLinker: add a flag to not always pull-in linkonce when performing importing

Summary:
The function importer already decided what symbols need to be pulled
in. Also these magically added ones will not be in the export list
for the source module, which can confuse the internalizer for
instance.

Reviewers: tejohnson, rafael

Subscribers: joker.eph, llvm-commits

Differential Revision: http://reviews.llvm.org/D19096

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266948

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/tools/llvm-link/llvm-link.cpp b/llvm/tools/llvm-link/llvm-link.cpp
index 73ac8727e71..0e720bd06ea 100644
--- a/llvm/tools/llvm-link/llvm-link.cpp
+++ b/llvm/tools/llvm-link/llvm-link.cpp
@@ -276,8 +276,10 @@ static bool importFunctions(const char *argv0, LLVMContext &Context,
     if (renameModuleForThinLTO(*SrcModule, *Index, &GlobalsToImport))
       return true;
 
-    if (L.linkInModule(std::move(SrcModule), Linker::Flags::None,
-                       &GlobalsToImport))
+    // Instruct the linker to not automatically import linkonce defintion.
+    unsigned Flags = Linker::Flags::DontForceLinkLinkonceODR;
+
+    if (L.linkInModule(std::move(SrcModule), Flags, &GlobalsToImport))
       return false;
   }