+ DEBUG(dbgs() << "DeadMachineInstructionElim: DELETING: " << *MI);
+ // It is possible that some DBG_VALUE instructions refer to this
+ // instruction. Examine each def operand for such references;
+ // if found, mark the DBG_VALUE as undef (but don't delete it).
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || !MO.isDef())
+ continue;
+ unsigned Reg = MO.getReg();
+ if (!TargetRegisterInfo::isVirtualRegister(Reg))
+ continue;
+ MachineRegisterInfo::use_iterator nextI;
+ for (MachineRegisterInfo::use_iterator I = MRI->use_begin(Reg),
+ E = MRI->use_end(); I!=E; I=nextI) {
+ nextI = llvm::next(I); // I is invalidated by the setReg
+ MachineOperand& Use = I.getOperand();
+ MachineInstr *UseMI = Use.getParent();
+ if (UseMI==MI)
+ continue;
+ assert(Use.isDebug());
+ UseMI->getOperand(0).setReg(0U);
+ }
+ }