1 files changed, 129 insertions, 0 deletions
diff --git a/lib/Target/Hexagon/HexagonOptimizeSZExtends.cpp b/lib/Target/Hexagon/HexagonOptimizeSZExtends.cpp
new file mode 100644
index 0000000000..1229aca58e
--- /dev/null
+++ b/lib/Target/Hexagon/HexagonOptimizeSZExtends.cpp
@@ -0,0 +1,129 @@
+//===-- HexagonOptimizeSZExtends.cpp - Identify and remove sign and -------===//
+//===--                                zero extends.                -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Constants.h"
+#include "llvm/PassSupport.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineLoopInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/CodeGen/MachineFunctionAnalysis.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include <algorithm>
+#include "Hexagon.h"
+#include "HexagonTargetMachine.h"
+
+using namespace llvm;
+
+namespace {
+  struct HexagonOptimizeSZExtends : public MachineFunctionPass {
+
+  public:
+    static char ID;
+    HexagonOptimizeSZExtends() : MachineFunctionPass(ID) {}
+
+    bool runOnMachineFunction(MachineFunction &MF);
+
+    const char *getPassName() const {
+      return "Hexagon remove redundant zero and size extends";
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.addRequired<MachineFunctionAnalysis>();
+      AU.addPreserved<MachineFunctionAnalysis>();
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+
+  private:
+  };
+}
+
+char HexagonOptimizeSZExtends::ID = 0;
+
+// This is a brain dead pass to get rid of redundant sign extends for the
+// following case:
+//
+// Transform the following pattern
+// %vreg170<def> = SXTW %vreg166
+// ...
+// %vreg176<def> = COPY %vreg170:subreg_loreg
+//
+// Into
+// %vreg176<def> = COPY vreg166
+
+bool HexagonOptimizeSZExtends::runOnMachineFunction(MachineFunction &MF) {
+  DenseMap<unsigned, unsigned> SExtMap;
+
+  // Loop over all of the basic blocks
+  for (MachineFunction::iterator MBBb = MF.begin(), MBBe = MF.end();
+       MBBb != MBBe; ++MBBb) {
+    MachineBasicBlock* MBB = MBBb;
+    SExtMap.clear();
+
+    // Traverse the basic block.
+    for (MachineBasicBlock::iterator MII = MBB->begin(); MII != MBB->end();
+         ++MII) {
+      MachineInstr *MI = MII;
+      // Look for sign extends:
+      //   %vreg170<def> = SXTW %vreg166
+      if (MI->getOpcode() == Hexagon::SXTW) {
+        assert (MI->getNumOperands() == 2);
+        MachineOperand &Dst = MI->getOperand(0);
+        MachineOperand &Src  = MI->getOperand(1);
+        unsigned DstReg = Dst.getReg();
+        unsigned SrcReg = Src.getReg();
+        // Just handle virtual registers.
+        if (TargetRegisterInfo::isVirtualRegister(DstReg) &&
+            TargetRegisterInfo::isVirtualRegister(SrcReg)) {
+          // Map the following:
+          //  %vreg170<def> = SXTW %vreg166
+          //  SExtMap[170] = vreg166
+          SExtMap[DstReg] = SrcReg;
+        }
+      }
+      // Look for copy:
+      //   %vreg176<def> = COPY %vreg170:subreg_loreg
+      if (MI->isCopy()) {
+        assert (MI->getNumOperands() == 2);
+        MachineOperand &Dst = MI->getOperand(0);
+        MachineOperand &Src  = MI->getOperand(1);
+
+        // Make sure we are copying the lower 32 bits.
+        if (Src.getSubReg() != Hexagon::subreg_loreg)
+          continue;
+
+        unsigned DstReg = Dst.getReg();
+        unsigned SrcReg = Src.getReg();
+        if (TargetRegisterInfo::isVirtualRegister(DstReg) &&
+            TargetRegisterInfo::isVirtualRegister(SrcReg)) {
+          // Try to find in the map.
+          if (unsigned SextSrc = SExtMap.lookup(SrcReg)) {
+            // Change the 1st operand.
+            MI->RemoveOperand(1);
+            MI->addOperand(MachineOperand::CreateReg(SextSrc, false));
+          }
+        }
+      }
+    }
+  }
+  return true;
+}
+
+FunctionPass *llvm::createHexagonOptimizeSZExtends() {
+  return new HexagonOptimizeSZExtends();
+}