-unsigned RegScavenger::FindUnusedReg(const TargetRegisterClass *RegClass,
- bool ExCalleeSaved) const {
- // Mask off the registers which are not in the TargetRegisterClass.
- BitVector RegsAvailableCopy(NumPhysRegs, false);
- CreateRegClassMask(RegClass, RegsAvailableCopy);
- RegsAvailableCopy &= RegsAvailable;
-
- // If looking for a non-callee-saved register, mask off all the callee-saved
- // registers.
- if (ExCalleeSaved)
- RegsAvailableCopy &= ~CalleeSavedRegs;
-
- // Returns the first unused (bit is set) register, or 0 is none is found.
- int Reg = RegsAvailableCopy.find_first();
- return (Reg == -1) ? 0 : Reg;
-}
-
-/// findFirstUse - Calculate the distance to the first use of the
-/// specified register.
-MachineInstr*
-RegScavenger::findFirstUse(MachineBasicBlock *MBB,
- MachineBasicBlock::iterator I, unsigned Reg,
- unsigned &Dist) {
- MachineInstr *UseMI = 0;
- Dist = ~0U;
- for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(Reg),
- RE = MRI->reg_end(); RI != RE; ++RI) {
- MachineInstr *UDMI = &*RI;
- if (UDMI->getParent() != MBB)
- continue;
- DenseMap<MachineInstr*, unsigned>::iterator DI = DistanceMap.find(UDMI);
- if (DI == DistanceMap.end()) {
- // If it's not in map, it's below current MI, let's initialize the
- // map.
- I = next(I);
- unsigned Dist = CurrDist + 1;
- while (I != MBB->end()) {
- DistanceMap.insert(std::make_pair(I, Dist++));
- I = next(I);
+/// findSurvivorReg - Return the candidate register that is unused for the
+/// longest after MBBI. UseMI is set to the instruction where the search
+/// stopped.
+///
+/// No more than InstrLimit instructions are inspected.
+///
+unsigned RegScavenger::findSurvivorReg(MachineBasicBlock::iterator StartMI,
+ BitVector &Candidates,
+ unsigned InstrLimit,
+ MachineBasicBlock::iterator &UseMI) {
+ int Survivor = Candidates.find_first();
+ assert(Survivor > 0 && "No candidates for scavenging");
+
+ MachineBasicBlock::iterator ME = MBB->getFirstTerminator();
+ assert(StartMI != ME && "MI already at terminator");
+ MachineBasicBlock::iterator RestorePointMI = StartMI;
+ MachineBasicBlock::iterator MI = StartMI;
+
+ bool inVirtLiveRange = false;
+ for (++MI; InstrLimit > 0 && MI != ME; ++MI, --InstrLimit) {
+ bool isVirtKillInsn = false;
+ bool isVirtDefInsn = false;
+ // Remove any candidates touched by instruction.
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &MO = MI->getOperand(i);
+ if (!MO.isReg() || MO.isUndef() || !MO.getReg())
+ continue;
+ if (TargetRegisterInfo::isVirtualRegister(MO.getReg())) {
+ if (MO.isDef())
+ isVirtDefInsn = true;
+ else if (MO.isKill())
+ isVirtKillInsn = true;
+ continue;