BackendUtil: Pass through -mdisable-tail-calls

The frontend option -fno-optimize-sibling-calls resolves to -cc1's
-mdisable-tail-calls, which is passed to the TargetMachine in the
backend.  PassManagerBuilder was adding the -tailcallelim pass anyway.

Use a new DisableTailCalls option in PassManagerBuilder to disable tail
calls harder.

Requires the matching commit in LLVM that adds DisableTailCalls.

<rdar://problem/16050591>

llvm-svn: 206543

1 files changed, 1 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index b75c62a4223..2c388ef58e9 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -247,6 +247,7 @@ void EmitAssemblyHelper::CreatePasses() {
   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
 
+  PMBuilder.DisableTailCalls = CodeGenOpts.DisableTailCalls;
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;