ThinLTO: linkonce compile-time optimization, do not bother when there is only one input file

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266281

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

@@ -173,6 +173,10 @@ static void ResolveODR(GlobalValue &GV, const ModuleSummaryIndex &Index,
 /// one copy.
 static void ResolveODR(Module &TheModule,
                              const ModuleSummaryIndex &Index) {
+  if (Index.modulePaths().size() == 1)
+    // Nothing to do if we don't have multiple modules
+    return;
+
   // We won't optimize the globals that are referenced by an alias for now
   // Ideally we should turn the alias into a global and duplicate the definition
   // when needed.