[PowerPC] Use a small cleanup pass to remove VSX self copies

As explained in r204976, because of how the allocation of VSX registers
interacts with the call-lowering code, we sometimes end up generating self VSX
copies. Specifically, things like this:
  %VSL2<def> = COPY %F2, %VSL2<imp-use,kill>
(where %F2 is really a sub-register of %VSL2, and so this copy is a nop)

This adds a small cleanup pass to remove these prior to post-RA scheduling.

llvm-svn: 204980

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index cb869bd..e7438f3 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -182,6 +182,9 @@ bool PPCPassConfig::addPreRegAlloc() {
 }
 
 bool PPCPassConfig::addPreSched2() {
+  if (getPPCSubtarget().hasVSX())
+    addPass(createPPCVSXCopyCleanupPass());
+
   if (getOptLevel() != CodeGenOpt::None)
     addPass(&IfConverterID);