Teach clang to use the ThinLTO pipeline

Summary: Use the new pipeline implemented in D17115

Reviewers: tejohnson

Subscribers: joker.eph, cfe-commits

Differential Revision: http://reviews.llvm.org/D17272

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@261045 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/BackendUtil.cpp

@@ -324,6 +324,7 @@ void EmitAssemblyHelper::CreatePasses(FunctionInfoIndex *FunctionIndex) {
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
+  PMBuilder.PrepareForThinLTO = CodeGenOpts.EmitFunctionSummary;
   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
@@ -333,7 +334,7 @@ void EmitAssemblyHelper::CreatePasses(FunctionInfoIndex *FunctionIndex) {
   // pipeline and pass down the in-memory function index.
   if (FunctionIndex) {
     PMBuilder.FunctionIndex = FunctionIndex;
-    PMBuilder.populateLTOPassManager(*MPM);
+    PMBuilder.populateThinLTOPassManager(*MPM);
     return;
   }