// The instruction to be updated is either Sub or MI.
Sub = IsCmpZero ? MI : Sub;
- // Move Movr0Inst to the place right before Sub.
+ // Move Movr0Inst to the appropriate place before Sub.
if (Movr0Inst) {
- Sub->getParent()->remove(Movr0Inst);
- Sub->getParent()->insert(MachineBasicBlock::iterator(Sub), Movr0Inst);
+ // Look backwards until we find a def that doesn't use the current EFLAGS.
+ Def = Sub;
+ MachineBasicBlock::reverse_iterator
+ InsertI = MachineBasicBlock::reverse_iterator(++Def),
+ InsertE = Sub->getParent()->rend();
+ for (; InsertI != InsertE; ++InsertI) {
+ MachineInstr *Instr = &*InsertI;
+ if (!Instr->readsRegister(X86::EFLAGS, TRI) &&
+ Instr->modifiesRegister(X86::EFLAGS, TRI)) {
+ Sub->getParent()->remove(Movr0Inst);
+ Instr->getParent()->insert(MachineBasicBlock::iterator(Instr),
+ Movr0Inst);
+ break;
+ }
+ }
+ if (InsertI == InsertE)
+ return false;
}
// Make sure Sub instruction defines EFLAGS and mark the def live.