-
-private:
-
- MachineRegisterInfo *mri;
- const TargetInstrInfo *tii;
- const TargetRegisterInfo *tri;
- DenseSet<LiveInterval*> alreadySplit;
-
- bool worthTryingToSplit(LiveInterval *li) const {
- return (!alreadySplit.count(li) && li->getNumValNums() > 1);
- }
-
- /// Try to break a LiveInterval into its component values.
- std::vector<LiveInterval*> tryVNISplit(LiveInterval *li,
- SlotIndex *earliestStart) {
-
- DEBUG(dbgs() << "Trying VNI split of %reg" << *li << "\n");
-
- std::vector<LiveInterval*> added;
- SmallVector<VNInfo*, 4> vnis;
-
- std::copy(li->vni_begin(), li->vni_end(), std::back_inserter(vnis));
-
- for (SmallVectorImpl<VNInfo*>::iterator vniItr = vnis.begin(),
- vniEnd = vnis.end(); vniItr != vniEnd; ++vniItr) {
- VNInfo *vni = *vniItr;
-
- // Skip unused VNIs, or VNIs with no kills.
- if (vni->isUnused() || vni->kills.empty())
- continue;
-
- DEBUG(dbgs() << " Extracted Val #" << vni->id << " as ");
- LiveInterval *splitInterval = extractVNI(li, vni);
-
- if (splitInterval != 0) {
- DEBUG(dbgs() << *splitInterval << "\n");
- added.push_back(splitInterval);
- alreadySplit.insert(splitInterval);
- if (earliestStart != 0) {
- if (splitInterval->beginIndex() < *earliestStart)
- *earliestStart = splitInterval->beginIndex();
- }
- } else {
- DEBUG(dbgs() << "0\n");
- }
- }
-
- DEBUG(dbgs() << "Original LI: " << *li << "\n");
-
- // If there original interval still contains some live ranges
- // add it to added and alreadySplit.
- if (!li->empty()) {
- added.push_back(li);
- alreadySplit.insert(li);
- if (earliestStart != 0) {
- if (li->beginIndex() < *earliestStart)
- *earliestStart = li->beginIndex();
- }
- }
-
- return added;
- }
-
- /// Extract the given value number from the interval.
- LiveInterval* extractVNI(LiveInterval *li, VNInfo *vni) const {
- assert(vni->isDefAccurate() || vni->isPHIDef());
- assert(!vni->kills.empty());
-
- // Create a new vreg and live interval, copy VNI kills & ranges over.
- const TargetRegisterClass *trc = mri->getRegClass(li->reg);
- unsigned newVReg = mri->createVirtualRegister(trc);
- vrm->grow();
- LiveInterval *newLI = &lis->getOrCreateInterval(newVReg);
- VNInfo *newVNI = newLI->createValueCopy(vni, lis->getVNInfoAllocator());
-
- // Start by copying all live ranges in the VN to the new interval.
- for (LiveInterval::iterator rItr = li->begin(), rEnd = li->end();
- rItr != rEnd; ++rItr) {
- if (rItr->valno == vni) {
- newLI->addRange(LiveRange(rItr->start, rItr->end, newVNI));
- }
- }
-
- // Erase the old VNI & ranges.
- li->removeValNo(vni);
-
- // Collect all current uses of the register belonging to the given VNI.
- // We'll use this to rename the register after we've dealt with the def.
- std::set<MachineInstr*> uses;
- for (MachineRegisterInfo::use_iterator
- useItr = mri->use_begin(li->reg), useEnd = mri->use_end();
- useItr != useEnd; ++useItr) {
- uses.insert(&*useItr);
- }
-
- // Process the def instruction for this VNI.
- if (newVNI->isPHIDef()) {
- // Insert a copy at the start of the MBB. The range proceeding the
- // copy will be attached to the original LiveInterval.
- MachineBasicBlock *defMBB = lis->getMBBFromIndex(newVNI->def);
- tii->copyRegToReg(*defMBB, defMBB->begin(), newVReg, li->reg, trc, trc);
- MachineInstr *copyMI = defMBB->begin();
- copyMI->addRegisterKilled(li->reg, tri);
- SlotIndex copyIdx = lis->InsertMachineInstrInMaps(copyMI);
- VNInfo *phiDefVNI = li->getNextValue(lis->getMBBStartIdx(defMBB),
- 0, false, lis->getVNInfoAllocator());
- phiDefVNI->setIsPHIDef(true);
- phiDefVNI->addKill(copyIdx.getDefIndex());
- li->addRange(LiveRange(phiDefVNI->def, copyIdx.getDefIndex(), phiDefVNI));
- LiveRange *oldPHIDefRange =
- newLI->getLiveRangeContaining(lis->getMBBStartIdx(defMBB));
-
- // If the old phi def starts in the middle of the range chop it up.
- if (oldPHIDefRange->start < lis->getMBBStartIdx(defMBB)) {
- LiveRange oldPHIDefRange2(copyIdx.getDefIndex(), oldPHIDefRange->end,
- oldPHIDefRange->valno);
- oldPHIDefRange->end = lis->getMBBStartIdx(defMBB);
- newLI->addRange(oldPHIDefRange2);
- } else if (oldPHIDefRange->start == lis->getMBBStartIdx(defMBB)) {
- // Otherwise if it's at the start of the range just trim it.
- oldPHIDefRange->start = copyIdx.getDefIndex();
- } else {
- assert(false && "PHI def range doesn't cover PHI def?");
- }
-
- newVNI->def = copyIdx.getDefIndex();
- newVNI->setCopy(copyMI);
- newVNI->setIsPHIDef(false); // not a PHI def anymore.
- newVNI->setIsDefAccurate(true);
- } else {
- // non-PHI def. Rename the def. If it's two-addr that means renaming the use
- // and inserting a new copy too.
- MachineInstr *defInst = lis->getInstructionFromIndex(newVNI->def);
- // We'll rename this now, so we can remove it from uses.
- uses.erase(defInst);
- unsigned defOpIdx = defInst->findRegisterDefOperandIdx(li->reg);
- bool isTwoAddr = defInst->isRegTiedToUseOperand(defOpIdx),
- twoAddrUseIsUndef = false;
-
- for (unsigned i = 0; i < defInst->getNumOperands(); ++i) {
- MachineOperand &mo = defInst->getOperand(i);
- if (mo.isReg() && (mo.isDef() || isTwoAddr) && (mo.getReg()==li->reg)) {
- mo.setReg(newVReg);
- if (isTwoAddr && mo.isUse() && mo.isUndef())
- twoAddrUseIsUndef = true;
- }
- }
-
- SlotIndex defIdx = lis->getInstructionIndex(defInst);
- newVNI->def = defIdx.getDefIndex();
-
- if (isTwoAddr && !twoAddrUseIsUndef) {
- MachineBasicBlock *defMBB = defInst->getParent();
- tii->copyRegToReg(*defMBB, defInst, newVReg, li->reg, trc, trc);
- MachineInstr *copyMI = prior(MachineBasicBlock::iterator(defInst));
- SlotIndex copyIdx = lis->InsertMachineInstrInMaps(copyMI);
- copyMI->addRegisterKilled(li->reg, tri);
- LiveRange *origUseRange =
- li->getLiveRangeContaining(newVNI->def.getUseIndex());
- VNInfo *origUseVNI = origUseRange->valno;
- origUseRange->end = copyIdx.getDefIndex();
- bool updatedKills = false;
- for (unsigned k = 0; k < origUseVNI->kills.size(); ++k) {
- if (origUseVNI->kills[k] == defIdx.getDefIndex()) {
- origUseVNI->kills[k] = copyIdx.getDefIndex();
- updatedKills = true;
- break;
- }
- }
- assert(updatedKills && "Failed to update VNI kill list.");
- VNInfo *copyVNI = newLI->getNextValue(copyIdx.getDefIndex(), copyMI,
- true, lis->getVNInfoAllocator());
- copyVNI->addKill(defIdx.getDefIndex());
- LiveRange copyRange(copyIdx.getDefIndex(),defIdx.getDefIndex(),copyVNI);
- newLI->addRange(copyRange);
- }
- }
-
- for (std::set<MachineInstr*>::iterator
- usesItr = uses.begin(), usesEnd = uses.end();
- usesItr != usesEnd; ++usesItr) {
- MachineInstr *useInst = *usesItr;
- SlotIndex useIdx = lis->getInstructionIndex(useInst);
- LiveRange *useRange =
- newLI->getLiveRangeContaining(useIdx.getUseIndex());
-
- // If this use doesn't belong to the new interval skip it.
- if (useRange == 0)
- continue;
-
- // This use doesn't belong to the VNI, skip it.
- if (useRange->valno != newVNI)
- continue;
-
- // Check if this instr is two address.
- unsigned useOpIdx = useInst->findRegisterUseOperandIdx(li->reg);
- bool isTwoAddress = useInst->isRegTiedToDefOperand(useOpIdx);
-
- // Rename uses (and defs for two-address instrs).
- for (unsigned i = 0; i < useInst->getNumOperands(); ++i) {
- MachineOperand &mo = useInst->getOperand(i);
- if (mo.isReg() && (mo.isUse() || isTwoAddress) &&
- (mo.getReg() == li->reg)) {
- mo.setReg(newVReg);
- }
- }
-
- // If this is a two address instruction we've got some extra work to do.
- if (isTwoAddress) {
- // We modified the def operand, so we need to copy back to the original
- // reg.
- MachineBasicBlock *useMBB = useInst->getParent();
- MachineBasicBlock::iterator useItr(useInst);
- tii->copyRegToReg(*useMBB, next(useItr), li->reg, newVReg, trc, trc);
- MachineInstr *copyMI = next(useItr);
- copyMI->addRegisterKilled(newVReg, tri);
- SlotIndex copyIdx = lis->InsertMachineInstrInMaps(copyMI);
-
- // Change the old two-address defined range & vni to start at
- // (and be defined by) the copy.
- LiveRange *origDefRange =
- li->getLiveRangeContaining(useIdx.getDefIndex());
- origDefRange->start = copyIdx.getDefIndex();
- origDefRange->valno->def = copyIdx.getDefIndex();
- origDefRange->valno->setCopy(copyMI);
-
- // Insert a new range & vni for the two-address-to-copy value. This
- // will be attached to the new live interval.
- VNInfo *copyVNI =
- newLI->getNextValue(useIdx.getDefIndex(), 0, true,
- lis->getVNInfoAllocator());
- copyVNI->addKill(copyIdx.getDefIndex());
- LiveRange copyRange(useIdx.getDefIndex(),copyIdx.getDefIndex(),copyVNI);
- newLI->addRange(copyRange);
- }
- }
-
- // Iterate over any PHI kills - we'll need to insert new copies for them.
- for (VNInfo::KillSet::iterator
- killItr = newVNI->kills.begin(), killEnd = newVNI->kills.end();
- killItr != killEnd; ++killItr) {
- SlotIndex killIdx(*killItr);
- if (killItr->isPHI()) {
- MachineBasicBlock *killMBB = lis->getMBBFromIndex(killIdx);
- LiveRange *oldKillRange =
- newLI->getLiveRangeContaining(killIdx);
-
- assert(oldKillRange != 0 && "No kill range?");
-
- tii->copyRegToReg(*killMBB, killMBB->getFirstTerminator(),
- li->reg, newVReg, trc, trc);
- MachineInstr *copyMI = prior(killMBB->getFirstTerminator());
- copyMI->addRegisterKilled(newVReg, tri);
- SlotIndex copyIdx = lis->InsertMachineInstrInMaps(copyMI);
-
- // Save the current end. We may need it to add a new range if the
- // current range runs of the end of the MBB.
- SlotIndex newKillRangeEnd = oldKillRange->end;
- oldKillRange->end = copyIdx.getDefIndex();
-
- if (newKillRangeEnd != lis->getMBBEndIdx(killMBB)) {
- assert(newKillRangeEnd > lis->getMBBEndIdx(killMBB) &&
- "PHI kill range doesn't reach kill-block end. Not sane.");
- newLI->addRange(LiveRange(lis->getMBBEndIdx(killMBB),
- newKillRangeEnd, newVNI));
- }
-
- *killItr = oldKillRange->end;
- VNInfo *newKillVNI = li->getNextValue(copyIdx.getDefIndex(),
- copyMI, true,
- lis->getVNInfoAllocator());
- newKillVNI->addKill(lis->getMBBTerminatorGap(killMBB));
- newKillVNI->setHasPHIKill(true);
- li->addRange(LiveRange(copyIdx.getDefIndex(),
- lis->getMBBEndIdx(killMBB),
- newKillVNI));
- }
-
- }
-
- newVNI->setHasPHIKill(false);
-
- return newLI;
- }
-