VirtRegMap.cpp

        int StackSlot = VRM.getStackSlot(VirtReg);
        const TargetRegisterClass *RC =
          MBB.getParent()->getSSARegMap()->getRegClass(VirtReg);

        // If this def is part of a two-address operand, make sure to execute
        // the store from the correct physical register.
        unsigned PhysReg;
        int TiedOp = MI.getInstrDescriptor()->findTiedToSrcOperand(i);
        if (TiedOp != -1)
          PhysReg = MI.getOperand(TiedOp).getReg();
        else {
          PhysReg = VRM.getPhys(VirtReg);
          if (ReusedOperands.isClobbered(PhysReg)) {
            // Another def has taken the assigned physreg. It must have been a
            // use&def which got it due to reuse. Undo the reuse!
            PhysReg = ReusedOperands.GetRegForReload(PhysReg, &MI, 
                                                     Spills, MaybeDeadStores);
          }
        }

        PhysRegsUsed[PhysReg] = true;
        ReusedOperands.markClobbered(PhysReg);
        MRI->storeRegToStackSlot(MBB, next(MII), PhysReg, StackSlot, RC);
        DOUT << "Store:\t" << *next(MII);
        MI.getOperand(i).setReg(PhysReg);

        // If there is a dead store to this stack slot, nuke it now.
        MachineInstr *&LastStore = MaybeDeadStores[StackSlot];
        if (LastStore) {
          DOUT << "Removed dead store:\t" << *LastStore;
          ++NumDSE;
          MBB.erase(LastStore);
          VRM.RemoveFromFoldedVirtMap(LastStore);
        }
        LastStore = next(MII);

        // If the stack slot value was previously available in some other
        // register, change it now.  Otherwise, make the register available,
        // in PhysReg.
        Spills.ModifyStackSlot(StackSlot);
        Spills.ClobberPhysReg(PhysReg);
        Spills.addAvailable(StackSlot, LastStore, PhysReg);
        ++NumStores;

        // Check to see if this is a noop copy.  If so, eliminate the
        // instruction before considering the dest reg to be changed.
        {
          unsigned Src, Dst;
          if (TII->isMoveInstr(MI, Src, Dst) && Src == Dst) {
            ++NumDCE;
            DOUT << "Removing now-noop copy: " << MI;
            MBB.erase(&MI);
            VRM.RemoveFromFoldedVirtMap(&MI);
            goto ProcessNextInst;
          }
        }        
      }
    }
  ProcessNextInst:
    MII = NextMII;
  }
}



llvm::Spiller* llvm::createSpiller() {
  switch (SpillerOpt) {
  default: assert(0 && "Unreachable!");
  case local:
    return new LocalSpiller();
  case simple:
    return new SimpleSpiller();
  }
}