[X86][NFC] Extract code for commute in foldMemoryOperandImpl into functions

To share code for folding broadcast in #79761

Author: KanRobert

llvm/lib/Target/X86/X86InstrInfo.cpp

@@ -7165,6 +7165,52 @@ static bool shouldPreventUndefRegUpdateMemFold(MachineFunction &MF,
   return VRegDef && VRegDef->isImplicitDef();
 }
 
+unsigned X86InstrInfo::commuteOperandsForFold(MachineInstr &MI,
+                                              unsigned Idx1) const {
+  unsigned Idx2 = CommuteAnyOperandIndex;
+  if (!findCommutedOpIndices(MI, Idx1, Idx2))
+    return Idx1;
+
+  bool HasDef = MI.getDesc().getNumDefs();
+  Register Reg0 = HasDef ? MI.getOperand(0).getReg() : Register();
+  Register Reg1 = MI.getOperand(Idx1).getReg();
+  Register Reg2 = MI.getOperand(Idx2).getReg();
+  bool Tied1 = 0 == MI.getDesc().getOperandConstraint(Idx1, MCOI::TIED_TO);
+  bool Tied2 = 0 == MI.getDesc().getOperandConstraint(Idx2, MCOI::TIED_TO);
+
+  // If either of the commutable operands are tied to the destination
+  // then we can not commute + fold.
+  if ((HasDef && Reg0 == Reg1 && Tied1) || (HasDef && Reg0 == Reg2 && Tied2))
+    return Idx1;
+
+  MachineInstr *CommutedMI = commuteInstruction(MI, false, Idx1, Idx2);
+  if (!CommutedMI) {
+    // Unable to commute.
+    return Idx1;
+  }
+  if (CommutedMI != &MI) {
+    // New instruction. We can't fold from this.
+    CommutedMI->eraseFromParent();
+    return Idx1;
+  }
+
+  return Idx2;
+}
+
+void X86InstrInfo::UndoCommuteForFold(MachineInstr &MI, unsigned Idx1,
+                                      unsigned Idx2) const {
+  // Folding failed again - undo the commute before returning.
+  MachineInstr *UncommutedMI = commuteInstruction(MI, false, Idx1, Idx2);
+  // New instruction. It doesn't need to be kept.
+  if (UncommutedMI && UncommutedMI != &MI)
+    UncommutedMI->eraseFromParent();
+}
+
+static void printFailMsgforFold(const MachineInstr &MI, unsigned Idx) {
+  if (PrintFailedFusing && !MI.isCopy())
+    dbgs() << "We failed to fuse operand " << Idx << " in " << MI;
+}
+
 MachineInstr *X86InstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr &MI, unsigned OpNum,
     ArrayRef<MachineOperand> MOs, MachineBasicBlock::iterator InsertPt,
@@ -7292,65 +7338,23 @@ MachineInstr *X86InstrInfo::foldMemoryOperandImpl(
     return NewMI;
   }
 
-  // If the instruction and target operand are commutable, commute the
-  // instruction and try again.
   if (AllowCommute) {
-    unsigned CommuteOpIdx1 = OpNum, CommuteOpIdx2 = CommuteAnyOperandIndex;
-    if (findCommutedOpIndices(MI, CommuteOpIdx1, CommuteOpIdx2)) {
-      bool HasDef = MI.getDesc().getNumDefs();
-      Register Reg0 = HasDef ? MI.getOperand(0).getReg() : Register();
-      Register Reg1 = MI.getOperand(CommuteOpIdx1).getReg();
-      Register Reg2 = MI.getOperand(CommuteOpIdx2).getReg();
-      bool Tied1 =
-          0 == MI.getDesc().getOperandConstraint(CommuteOpIdx1, MCOI::TIED_TO);
-      bool Tied2 =
-          0 == MI.getDesc().getOperandConstraint(CommuteOpIdx2, MCOI::TIED_TO);
-
-      // If either of the commutable operands are tied to the destination
-      // then we can not commute + fold.
-      if ((HasDef && Reg0 == Reg1 && Tied1) ||
-          (HasDef && Reg0 == Reg2 && Tied2))
-        return nullptr;
-
-      MachineInstr *CommutedMI =
-          commuteInstruction(MI, false, CommuteOpIdx1, CommuteOpIdx2);
-      if (!CommutedMI) {
-        // Unable to commute.
-        return nullptr;
-      }
-      if (CommutedMI != &MI) {
-        // New instruction. We can't fold from this.
-        CommutedMI->eraseFromParent();
-        return nullptr;
-      }
-
-      // Attempt to fold with the commuted version of the instruction.
-      NewMI = foldMemoryOperandImpl(MF, MI, CommuteOpIdx2, MOs, InsertPt, Size,
-                                    Alignment, /*AllowCommute=*/false);
-      if (NewMI)
-        return NewMI;
-
-      // Folding failed again - undo the commute before returning.
-      MachineInstr *UncommutedMI =
-          commuteInstruction(MI, false, CommuteOpIdx1, CommuteOpIdx2);
-      if (!UncommutedMI) {
-        // Unable to commute.
-        return nullptr;
-      }
-      if (UncommutedMI != &MI) {
-        // New instruction. It doesn't need to be kept.
-        UncommutedMI->eraseFromParent();
-        return nullptr;
-      }
-
-      // Return here to prevent duplicate fuse failure report.
+    // If the instruction and target operand are commutable, commute the
+    // instruction and try again.
+    unsigned CommuteOpIdx2 = commuteOperandsForFold(MI, OpNum);
+    if (CommuteOpIdx2 == OpNum) {
+      printFailMsgforFold(MI, OpNum);
       return nullptr;
     }
+    // Attempt to fold with the commuted version of the instruction.
+    NewMI = foldMemoryOperandImpl(MF, MI, CommuteOpIdx2, MOs, InsertPt, Size,
+                                  Alignment, /*AllowCommute=*/false);
+    if (NewMI)
+      return NewMI;
+    UndoCommuteForFold(MI, OpNum, CommuteOpIdx2);
   }
 
-  // No fusion
-  if (PrintFailedFusing && !MI.isCopy())
-    dbgs() << "We failed to fuse operand " << OpNum << " in " << MI;
+  printFailMsgforFold(MI, OpNum);
   return nullptr;
 }
 

llvm/lib/Target/X86/X86InstrInfo.h

@@ -685,8 +685,10 @@ class X86InstrInfo final : public X86GenInstrInfo {
                             Register SrcReg2, int64_t ImmMask, int64_t ImmValue,
                             const MachineInstr &OI, bool *IsSwapped,
                             int64_t *ImmDelta) const;
-};
 
+  unsigned commuteOperandsForFold(MachineInstr &MI, unsigned Idx1) const;
+  void UndoCommuteForFold(MachineInstr &MI, unsigned Idx1, unsigned Idx2) const;
+};
 } // namespace llvm
 
 #endif