Replacing HexagonOptimizeSZExtends with HexagonPeephole.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150603 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 292 insertions, 0 deletions

diff --git a/lib/Target/Hexagon/HexagonPeephole.cpp b/lib/Target/Hexagon/HexagonPeephole.cpp
new file mode 100644
index 0000000000..2dda8fa16d
--- /dev/null
+++ b/lib/Target/Hexagon/HexagonPeephole.cpp
@@ -0,0 +1,292 @@
+//===-- HexagonPeephole.cpp - Hexagon Peephole Optimiztions ---------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+// This peephole pass optimizes in the following cases.
+// 1. Optimizes 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
+//
+//  2. Optimizes redundant negation of predicates.
+//     %vreg15<def> = CMPGTrr %vreg6, %vreg2
+//     ...
+//     %vreg16<def> = NOT_p %vreg15<kill>
+//     ...
+//     JMP_c %vreg16<kill>, <BB#1>, %PC<imp-def,dead>
+//
+//     Into
+//     %vreg15<def> = CMPGTrr %vreg6, %vreg2;
+//     ...
+//     JMP_cNot %vreg15<kill>, <BB#1>, %PC<imp-def,dead>;
+//
+// Note: The peephole pass makes the instrucstions like
+// %vreg170<def> = SXTW %vreg166 or %vreg16<def> = NOT_p %vreg15<kill>
+// redundant and relies on some form of dead removal instrucions, like
+// DCE or DIE to actually eliminate them.
+
+
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "hexagon-peephole"
+#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/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include <algorithm>
+#include "Hexagon.h"
+#include "HexagonTargetMachine.h"
+
+#include "llvm/Support/CommandLine.h"
+
+using namespace llvm;
+
+cl::opt<int> DebugHexagonPeephole("debug-hexagon-peephole",
+    cl::Hidden, cl::desc(""));
+
+static cl::opt<bool> DisableHexagonPeephole("disable-hexagon-peephole",
+    cl::Hidden, cl::ZeroOrMore, cl::init(false),
+    cl::desc("Disable Peephole Optimization"));
+
+static cl::opt<int>
+DbgPNPCount("pnp-count", cl::init(-1), cl::Hidden,
+  cl::desc("Maximum number of P=NOT(P) to be optimized"));
+
+static cl::opt<bool> DisablePNotP("disable-hexagon-pnotp",
+    cl::Hidden, cl::ZeroOrMore, cl::init(false),
+    cl::desc("Disable Optimization of PNotP"));
+
+static cl::opt<bool> DisableOptSZExt("disable-hexagon-optszext",
+    cl::Hidden, cl::ZeroOrMore, cl::init(false),
+    cl::desc("Disable Optimization of Sign/Zero Extends"));
+
+namespace {
+  struct HexagonPeephole : public MachineFunctionPass {
+    const HexagonInstrInfo    *QII;
+    const HexagonRegisterInfo *QRI;
+    const MachineRegisterInfo *MRI;
+
+  public:
+    static char ID;
+    HexagonPeephole() : MachineFunctionPass(ID) { }
+
+    bool runOnMachineFunction(MachineFunction &MF);
+
+    const char *getPassName() const {
+      return "Hexagon optimize redundant zero and size extends";
+    }
+
+    void getAnalysisUsage(AnalysisUsage &AU) const {
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+
+  private:
+    void ChangeOpInto(MachineOperand &Dst, MachineOperand &Src);
+  };
+}
+
+char HexagonPeephole::ID = 0;
+
+bool HexagonPeephole::runOnMachineFunction(MachineFunction &MF) {
+
+  QII = static_cast<const HexagonInstrInfo *>(MF.getTarget().
+                                        getInstrInfo());
+  QRI = static_cast<const HexagonRegisterInfo *>(MF.getTarget().
+                                       getRegisterInfo());
+  MRI = &MF.getRegInfo();
+
+  DenseMap<unsigned, unsigned> PeepholeMap;
+
+  if (DisableHexagonPeephole) return false;
+
+  // Loop over all of the basic blocks.
+  for (MachineFunction::iterator MBBb = MF.begin(), MBBe = MF.end();
+       MBBb != MBBe; ++MBBb) {
+    MachineBasicBlock* MBB = MBBb;
+    PeepholeMap.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 (!DisableOptSZExt && 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
+          // PeepholeMap[170] = vreg166
+          PeepholeMap[DstReg] = SrcReg;
+        }
+      }
+
+      // Look for P=NOT(P).
+      if (!DisablePNotP &&
+          (MI->getOpcode() == Hexagon::NOT_p)) {
+        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> = NOT_xx %vreg166
+          // PeepholeMap[170] = vreg166
+          PeepholeMap[DstReg] = SrcReg;
+        }
+      }
+
+      // Look for copy:
+      // %vreg176<def> = COPY %vreg170:subreg_loreg
+      if (!DisableOptSZExt && 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 PeepholeSrc = PeepholeMap.lookup(SrcReg)) {
+            // Change the 1st operand.
+            MI->RemoveOperand(1);
+            MI->addOperand(MachineOperand::CreateReg(PeepholeSrc, false));
+          }
+        }
+      }
+
+      // Look for Predicated instructions.
+      if (!DisablePNotP) {
+        bool Done = false;
+        if (QII->isPredicated(MI)) {
+          MachineOperand &Op0 = MI->getOperand(0);
+          unsigned Reg0 = Op0.getReg();
+          const TargetRegisterClass *RC0 = MRI->getRegClass(Reg0);
+          if (RC0->getID() == Hexagon::PredRegsRegClassID) {
+            // Handle instructions that have a prediate register in op0
+            // (most cases of predicable instructions).
+            if (TargetRegisterInfo::isVirtualRegister(Reg0)) {
+              // Try to find in the map.
+              if (unsigned PeepholeSrc = PeepholeMap.lookup(Reg0)) {
+                // Change the 1st operand and, flip the opcode.
+                MI->getOperand(0).setReg(PeepholeSrc);
+                int NewOp = QII->getInvertedPredicatedOpcode(MI->getOpcode());
+                MI->setDesc(QII->get(NewOp));
+                Done = true;
+              }
+            }
+          }
+        }
+
+        if (!Done) {
+          // Handle special instructions.
+          unsigned Op = MI->getOpcode();
+          unsigned NewOp = 0;
+          unsigned PR = 1, S1 = 2, S2 = 3;   // Operand indices.
+
+          switch (Op) {
+            case Hexagon::TFR_condset_rr:
+            case Hexagon::TFR_condset_ii:
+            case Hexagon::MUX_ii:
+            case Hexagon::MUX_rr:
+              NewOp = Op;
+              break;
+            case Hexagon::TFR_condset_ri:
+              NewOp = Hexagon::TFR_condset_ir;
+              break;
+            case Hexagon::TFR_condset_ir:
+              NewOp = Hexagon::TFR_condset_ri;
+              break;
+            case Hexagon::MUX_ri:
+              NewOp = Hexagon::MUX_ir;
+              break;
+            case Hexagon::MUX_ir:
+              NewOp = Hexagon::MUX_ri;
+              break;
+          }
+          if (NewOp) {
+            unsigned PSrc = MI->getOperand(PR).getReg();
+            if (unsigned POrig = PeepholeMap.lookup(PSrc)) {
+              MI->getOperand(PR).setReg(POrig);
+              MI->setDesc(QII->get(NewOp));
+              // Swap operands S1 and S2.
+              MachineOperand Op1 = MI->getOperand(S1);
+              MachineOperand Op2 = MI->getOperand(S2);
+              ChangeOpInto(MI->getOperand(S1), Op2);
+              ChangeOpInto(MI->getOperand(S2), Op1);
+            }
+          } // if (NewOp)
+        } // if (!Done)
+
+      } // if (!DisablePNotP)
+
+    } // Instruction
+  } // Basic Block
+  return true;
+}
+
+void HexagonPeephole::ChangeOpInto(MachineOperand &Dst, MachineOperand &Src) {
+  assert (&Dst != &Src && "Cannot duplicate into itself");
+  switch (Dst.getType()) {
+    case MachineOperand::MO_Register:
+      if (Src.isReg()) {
+        Dst.setReg(Src.getReg());
+      } else if (Src.isImm()) {
+        Dst.ChangeToImmediate(Src.getImm());
+      } else {
+        llvm_unreachable("Unexpected src operand type");
+      }
+      break;
+
+    case MachineOperand::MO_Immediate:
+      if (Src.isImm()) {
+        Dst.setImm(Src.getImm());
+      } else if (Src.isReg()) {
+        Dst.ChangeToRegister(Src.getReg(), Src.isDef(), Src.isImplicit(),
+                             Src.isKill(), Src.isDead(), Src.isUndef(),
+                             Src.isDebug());
+      } else {
+        llvm_unreachable("Unexpected src operand type");
+      }
+      break;
+
+    default:
+      llvm_unreachable("Unexpected dst operand type");
+      break;
+  }
+}
+
+FunctionPass *llvm::createHexagonPeephole() {
+  return new HexagonPeephole();
+}