+static bool isUndefCopy(MachineInstr *MI, unsigned Reg,
+ const TargetInstrInfo *tii_,
+ SmallSet<unsigned, 8> &ImpDefRegs) {
+ if (MI->isCopy()) {
+ MachineOperand &MO0 = MI->getOperand(0);
+ MachineOperand &MO1 = MI->getOperand(1);
+ if (MO1.getReg() != Reg)
+ return false;
+ if (!MO0.getSubReg() || ImpDefRegs.count(MO0.getReg()))
+ return true;
+ return false;
+ }
+
+ unsigned SrcReg, DstReg, SrcSubReg, DstSubReg;
+ if (tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubReg, DstSubReg)) {
+ if (Reg != SrcReg)
+ return false;
+ if (DstSubReg == 0 || ImpDefRegs.count(DstReg))
+ return true;
+ }
+ return false;
+}
+