Add a new -fmerge-functions -cc1 flag that enables function merging.

llvm-svn: 220543
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 4f1f52f..ecabb08 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -247,6 +247,7 @@
   PMBuilder.DisableTailCalls = CodeGenOpts.DisableTailCalls;
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
+  PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,