--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/Target/NVPTX/NVPTXPeephole.cpp	Tue Oct 13 17:48:58 2015 +0900
@@ -0,0 +1,154 @@
+//===-- NVPTXPeephole.cpp - NVPTX Peephole Optimiztions -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// In NVPTX, NVPTXFrameLowering will emit following instruction at the beginning
+// of a MachineFunction.
+//
+//   mov %SPL, %depot
+//   cvta.local %SP, %SPL
+//
+// Because Frame Index is a generic address and alloca can only return generic
+// pointer, without this pass the instructions producing alloca'ed address will
+// be based on %SP. NVPTXLowerAlloca tends to help replace store and load on
+// this address with their .local versions, but this may introduce a lot of
+// cvta.to.local instructions. Performance can be improved if we avoid casting
+// address back and forth and directly calculate local address based on %SPL.
+// This peephole pass optimizes these cases, for example
+//
+// It will transform the following pattern
+//    %vreg0<def> = LEA_ADDRi64 %VRFrame, 4
+//    %vreg1<def> = cvta_to_local_yes_64 %vreg0
+//
+// into
+//    %vreg1<def> = LEA_ADDRi64 %VRFrameLocal, 4
+//
+// %VRFrameLocal is the virtual register name of %SPL
+//
+//===----------------------------------------------------------------------===//
+
+#include "NVPTX.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "nvptx-peephole"
+
+namespace llvm {
+void initializeNVPTXPeepholePass(PassRegistry &);
+}
+
+namespace {
+struct NVPTXPeephole : public MachineFunctionPass {
+ public:
+  static char ID;
+  NVPTXPeephole() : MachineFunctionPass(ID) {
+    initializeNVPTXPeepholePass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override;
+
+  const char *getPassName() const override {
+    return "NVPTX optimize redundant cvta.to.local instruction";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+};
+}
+
+char NVPTXPeephole::ID = 0;
+
+INITIALIZE_PASS(NVPTXPeephole, "nvptx-peephole", "NVPTX Peephole", false, false)
+
+static bool isCVTAToLocalCombinationCandidate(MachineInstr &Root) {
+  auto &MBB = *Root.getParent();
+  auto &MF = *MBB.getParent();
+  // Check current instruction is cvta.to.local
+  if (Root.getOpcode() != NVPTX::cvta_to_local_yes_64 &&
+      Root.getOpcode() != NVPTX::cvta_to_local_yes)
+    return false;
+
+  auto &Op = Root.getOperand(1);
+  const auto &MRI = MF.getRegInfo();
+  MachineInstr *GenericAddrDef = nullptr;
+  if (Op.isReg() && TargetRegisterInfo::isVirtualRegister(Op.getReg())) {
+    GenericAddrDef = MRI.getUniqueVRegDef(Op.getReg());
+  }
+
+  // Check the register operand is uniquely defined by LEA_ADDRi instruction
+  if (!GenericAddrDef || GenericAddrDef->getParent() != &MBB ||
+      (GenericAddrDef->getOpcode() != NVPTX::LEA_ADDRi64 &&
+       GenericAddrDef->getOpcode() != NVPTX::LEA_ADDRi)) {
+    return false;
+  }
+
+  // Check the LEA_ADDRi operand is Frame index
+  auto &BaseAddrOp = GenericAddrDef->getOperand(1);
+  if (BaseAddrOp.isReg() && BaseAddrOp.getReg() == NVPTX::VRFrame) {
+    return true;
+  }
+
+  return false;
+}
+
+static void CombineCVTAToLocal(MachineInstr &Root) {
+  auto &MBB = *Root.getParent();
+  auto &MF = *MBB.getParent();
+  const auto &MRI = MF.getRegInfo();
+  const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
+  auto &Prev = *MRI.getUniqueVRegDef(Root.getOperand(1).getReg());
+
+  MachineInstrBuilder MIB =
+      BuildMI(MF, Root.getDebugLoc(), TII->get(Prev.getOpcode()),
+              Root.getOperand(0).getReg())
+          .addReg(NVPTX::VRFrameLocal)
+          .addOperand(Prev.getOperand(2));
+
+  MBB.insert((MachineBasicBlock::iterator)&Root, MIB);
+
+  // Check if MRI has only one non dbg use, which is Root
+  if (MRI.hasOneNonDBGUse(Prev.getOperand(0).getReg())) {
+    Prev.eraseFromParentAndMarkDBGValuesForRemoval();
+  }
+  Root.eraseFromParentAndMarkDBGValuesForRemoval();
+}
+
+bool NVPTXPeephole::runOnMachineFunction(MachineFunction &MF) {
+  bool Changed = false;
+  // Loop over all of the basic blocks.
+  for (auto &MBB : MF) {
+    // Traverse the basic block.
+    auto BlockIter = MBB.begin();
+
+    while (BlockIter != MBB.end()) {
+      auto &MI = *BlockIter++;
+      if (isCVTAToLocalCombinationCandidate(MI)) {
+        CombineCVTAToLocal(MI);
+        Changed = true;
+      }
+    }  // Instruction
+  }    // Basic Block
+
+  // Remove unnecessary %VRFrame = cvta.local %VRFrameLocal
+  const auto &MRI = MF.getRegInfo();
+  if (MRI.use_empty(NVPTX::VRFrame)) {
+    if (auto MI = MRI.getUniqueVRegDef(NVPTX::VRFrame)) {
+      MI->eraseFromParentAndMarkDBGValuesForRemoval();
+    }
+  }
+
+  return Changed;
+}
+
+MachineFunctionPass *llvm::createNVPTXPeephole() { return new NVPTXPeephole(); }