MachineBasicBlock::iterator P = MBB->begin();
while (P != MBB->end() && P->getOpcode() == TargetInstrInfo::PHI) {
unsigned DestReg = P->getOperand(0).getReg();
-
// Don't both doing PHI elimination for dead PHI's.
if (P->registerDefIsDead(DestReg)) {
ProcessedNames.insert(SrcReg);
continue;
}
+
+ // We don't need to insert copies for implicit_defs.
+ MachineInstr* DefMI = MRI.getVRegDef(SrcReg);
+ if (DefMI->getOpcode() == TargetInstrInfo::IMPLICIT_DEF)
+ ProcessedNames.insert(SrcReg);
// Check for trivial interferences via liveness information, allowing us
// to avoid extra work later. Any registers that interfere cannot both