[Hexagon] Use MachineInstrBuilder instead of changing instruction in place

llvm-svn: 305953

Author: Krzysztof Parzyszek

llvm/lib/Target/Hexagon/HexagonPeephole.cpp

@@ -100,9 +100,6 @@ namespace {
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       MachineFunctionPass::getAnalysisUsage(AU);
     }
-
-  private:
-    void ChangeOpInto(MachineOperand &Dst, MachineOperand &Src);
   };
 }
 
@@ -132,7 +129,9 @@ bool HexagonPeephole::runOnMachineFunction(MachineFunction &MF) {
     PeepholeDoubleRegsMap.clear();
 
     // Traverse the basic block.
-    for (MachineInstr &MI : *MBB) {
+    for (auto I = MBB->begin(), E = MBB->end(), NextI = I; I != E; I = NextI) {
+      NextI = std::next(I);
+      MachineInstr &MI = *I;
       // Look for sign extends:
       // %vreg170<def> = SXTW %vreg166
       if (!DisableOptSZExt && MI.getOpcode() == Hexagon::A2_sxtw) {
@@ -280,14 +279,13 @@ bool HexagonPeephole::runOnMachineFunction(MachineFunction &MF) {
           if (NewOp) {
             unsigned PSrc = MI.getOperand(PR).getReg();
             if (unsigned POrig = PeepholeMap.lookup(PSrc)) {
-              MI.getOperand(PR).setReg(POrig);
+              BuildMI(*MBB, MI.getIterator(), MI.getDebugLoc(),
+                      QII->get(NewOp), MI.getOperand(0).getReg())
+                .addReg(POrig)
+                .add(MI.getOperand(S2))
+                .add(MI.getOperand(S1));
               MRI->clearKillFlags(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);
+              MI.eraseFromParent();
             }
           } // if (NewOp)
         } // if (!Done)
@@ -299,40 +297,6 @@ bool HexagonPeephole::runOnMachineFunction(MachineFunction &MF) {
   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());
-        Dst.setSubReg(Src.getSubReg());
-        MRI->clearKillFlags(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(),
-                             false, Src.isDead(), Src.isUndef(),
-                             Src.isDebug());
-        Dst.setSubReg(Src.getSubReg());
-      } else {
-        llvm_unreachable("Unexpected src operand type");
-      }
-      break;
-
-    default:
-      llvm_unreachable("Unexpected dst operand type");
-      break;
-  }
-}
-
 FunctionPass *llvm::createHexagonPeephole() {
   return new HexagonPeephole();
 }