[NVPTX] Move NVPTXPeephole after NVPTXPrologEpilogPass

Summary:
Offset of frame index is calculated by NVPTXPrologEpilogPass. Before
that the correct offset of stack objects cannot be obtained, which
leads to wrong offset if there are more than 2 frame objects. This patch
move NVPTXPeephole after NVPTXPrologEpilogPass. Because the frame index
is already replaced by %VRFrame in NVPTXPrologEpilogPass, we check
VRFrame register instead, and try to remove the VRFrame if there
is no usage after NVPTXPeephole pass.

Patched by Xuetian Weng. 

Test Plan:
Strengthened test/CodeGen/NVPTX/local-stack-frame.ll to check the
offset calculation based on SP and SPL.

Reviewers: jholewinski, jingyue

Reviewed By: jingyue

Subscribers: jholewinski, llvm-commits

Differential Revision: http://reviews.llvm.org/D10853

llvm-svn: 241185

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/Target/NVPTX/NVPTXTargetMachine.cpp b/llvm/lib/Target/NVPTX/NVPTXTargetMachine.cpp
index dc3e34f9647..9d9072efc38 100644
--- a/llvm/lib/Target/NVPTX/NVPTXTargetMachine.cpp
+++ b/llvm/lib/Target/NVPTX/NVPTXTargetMachine.cpp
@@ -205,13 +205,15 @@ bool NVPTXPassConfig::addInstSelector() {
   if (!ST.hasImageHandles())
     addPass(createNVPTXReplaceImageHandlesPass());
 
-  addPass(createNVPTXPeephole());
-
   return false;
 }
 
 void NVPTXPassConfig::addPostRegAlloc() {
   addPass(createNVPTXPrologEpilogPass(), false);
+  // NVPTXPrologEpilogPass calculates frame object offset and replace frame
+  // index with VRFrame register. NVPTXPeephole need to be run after that and
+  // will replace VRFrame with VRFrameLocal when possible.
+  addPass(createNVPTXPeephole());
 }
 
 FunctionPass *NVPTXPassConfig::createTargetRegisterAllocator(bool) {