+/// instructionChanged - When the address of an instruction changes, this
+/// method should be called so that live variables can update its internal
+/// data structures. This removes the records for OldMI, transfering them to
+/// the records for NewMI.
+void LiveVariables::instructionChanged(MachineInstr *OldMI,
+ MachineInstr *NewMI) {
+ // If the instruction defines any virtual registers, update the VarInfo for
+ // the instruction.
+ for (unsigned i = 0, e = OldMI->getNumOperands(); i != e; ++i) {
+ MachineOperand &MO = OldMI->getOperand(i);
+ if (MO.isRegister() && MO.isDef() && MO.getReg() &&
+ MRegisterInfo::isVirtualRegister(MO.getReg())) {
+ unsigned Reg = MO.getReg();
+ VarInfo &VI = getVarInfo(Reg);
+ if (VI.DefInst == OldMI)
+ VI.DefInst = NewMI;
+ }
+ }
+
+ // Move the killed information over...
+ killed_iterator I, E;
+ tie(I, E) = killed_range(OldMI);
+ std::vector<unsigned> Regs;
+ for (killed_iterator A = I; A != E; ++A)
+ Regs.push_back(A->second);
+ RegistersKilled.erase(I, E);
+
+ for (unsigned i = 0, e = Regs.size(); i != e; ++i)
+ RegistersKilled.insert(std::make_pair(NewMI, Regs[i]));
+ Regs.clear();
+
+ // Move the dead information over...
+ tie(I, E) = dead_range(OldMI);
+ for (killed_iterator A = I; A != E; ++A)
+ Regs.push_back(A->second);
+ RegistersDead.erase(I, E);
+
+ for (unsigned i = 0, e = Regs.size(); i != e; ++i)
+ RegistersDead.insert(std::make_pair(NewMI, Regs[i]));
+}