+ // If the instruction and target operand are commutable, commute the
+ // instruction and try again.
+ if (AllowCommute) {
+ unsigned OriginalOpIdx = i, CommuteOpIdx1, CommuteOpIdx2;
+ if (findCommutedOpIndices(MI, CommuteOpIdx1, CommuteOpIdx2)) {
+ bool HasDef = MI->getDesc().getNumDefs();
+ unsigned Reg0 = HasDef ? MI->getOperand(0).getReg() : 0;
+ unsigned Reg1 = MI->getOperand(CommuteOpIdx1).getReg();
+ unsigned Reg2 = MI->getOperand(CommuteOpIdx2).getReg();
+ bool Tied0 =
+ 0 == MI->getDesc().getOperandConstraint(CommuteOpIdx1, MCOI::TIED_TO);
+ bool Tied1 =
+ 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 && Tied0) ||
+ (HasDef && Reg0 == Reg2 && Tied1))
+ return nullptr;
+
+ if ((CommuteOpIdx1 == OriginalOpIdx) ||
+ (CommuteOpIdx2 == OriginalOpIdx)) {
+ MachineInstr *CommutedMI = commuteInstruction(MI, false);
+ 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.
+ unsigned CommuteOp =
+ (CommuteOpIdx1 == OriginalOpIdx ? CommuteOpIdx2 : CommuteOpIdx1);
+ NewMI = foldMemoryOperandImpl(MF, MI, CommuteOp, MOs, Size, Align,
+ /*AllowCommute=*/false);
+ if (NewMI)
+ return NewMI;
+
+ // Folding failed again - undo the commute before returning.
+ MachineInstr *UncommutedMI = commuteInstruction(MI, false);
+ 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.
+ return nullptr;
+ }
+ }
+ }
+