#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
+#include <set>
using namespace llvm;
namespace {
- enum SpillerName { trivial, standard };
+ enum SpillerName { trivial, standard, splitting };
}
static cl::opt<SpillerName>
spillerOpt("spiller",
cl::desc("Spiller to use: (default: standard)"),
cl::Prefix,
- cl::values(clEnumVal(trivial, "trivial spiller"),
- clEnumVal(standard, "default spiller"),
+ cl::values(clEnumVal(trivial, "trivial spiller"),
+ clEnumVal(standard, "default spiller"),
+ clEnumVal(splitting, "splitting spiller"),
clEnumValEnd),
cl::init(standard));
+// Spiller virtual destructor implementation.
Spiller::~Spiller() {}
namespace {
/// immediately before each use, and stores after each def. No folding or
/// remat is attempted.
std::vector<LiveInterval*> trivialSpillEverywhere(LiveInterval *li) {
- DEBUG(errs() << "Spilling everywhere " << *li << "\n");
+ DEBUG(dbgs() << "Spilling everywhere " << *li << "\n");
assert(li->weight != HUGE_VALF &&
"Attempting to spill already spilled value.");
assert(!li->isStackSlot() &&
"Trying to spill a stack slot.");
- DEBUG(errs() << "Trivial spill everywhere of reg" << li->reg << "\n");
+ DEBUG(dbgs() << "Trivial spill everywhere of reg" << li->reg << "\n");
std::vector<LiveInterval*> added;
// Grab the use/def instr.
MachineInstr *mi = &*regItr;
- DEBUG(errs() << " Processing " << *mi);
+ DEBUG(dbgs() << " Processing " << *mi);
// Step regItr to the next use/def instr.
do {
// Insert store if necessary.
if (hasDef) {
- tii->storeRegToStackSlot(*mi->getParent(), next(miItr), newVReg, true,
+ tii->storeRegToStackSlot(*mi->getParent(), llvm::next(miItr), newVReg, true,
ss, trc);
- MachineInstr *storeInstr(next(miItr));
+ MachineInstr *storeInstr(llvm::next(miItr));
SlotIndex storeIndex =
lis->InsertMachineInstrInMaps(storeInstr).getDefIndex();
SlotIndex beginIndex = storeIndex.getPrevIndex();
: SpillerBase(mf, lis, vrm) {}
std::vector<LiveInterval*> spill(LiveInterval *li,
- SmallVectorImpl<LiveInterval*> &spillIs) {
+ SmallVectorImpl<LiveInterval*> &spillIs,
+ SlotIndex*) {
// Ignore spillIs - we don't use it.
return trivialSpillEverywhere(li);
}
/// Falls back on LiveIntervals::addIntervalsForSpills.
class StandardSpiller : public Spiller {
-private:
+protected:
LiveIntervals *lis;
const MachineLoopInfo *loopInfo;
VirtRegMap *vrm;
public:
- StandardSpiller(MachineFunction *mf, LiveIntervals *lis,
- const MachineLoopInfo *loopInfo, VirtRegMap *vrm)
+ StandardSpiller(LiveIntervals *lis, const MachineLoopInfo *loopInfo,
+ VirtRegMap *vrm)
: lis(lis), loopInfo(loopInfo), vrm(vrm) {}
/// Falls back on LiveIntervals::addIntervalsForSpills.
std::vector<LiveInterval*> spill(LiveInterval *li,
- SmallVectorImpl<LiveInterval*> &spillIs) {
+ SmallVectorImpl<LiveInterval*> &spillIs,
+ SlotIndex*) {
return lis->addIntervalsForSpills(*li, spillIs, loopInfo, *vrm);
}
};
+/// When a call to spill is placed this spiller will first try to break the
+/// interval up into its component values (one new interval per value).
+/// If this fails, or if a call is placed to spill a previously split interval
+/// then the spiller falls back on the standard spilling mechanism.
+class SplittingSpiller : public StandardSpiller {
+public:
+ SplittingSpiller(MachineFunction *mf, LiveIntervals *lis,
+ const MachineLoopInfo *loopInfo, VirtRegMap *vrm)
+ : StandardSpiller(lis, loopInfo, vrm) {
+
+ mri = &mf->getRegInfo();
+ tii = mf->getTarget().getInstrInfo();
+ tri = mf->getTarget().getRegisterInfo();
+ }
+
+ std::vector<LiveInterval*> spill(LiveInterval *li,
+ SmallVectorImpl<LiveInterval*> &spillIs,
+ SlotIndex *earliestStart) {
+
+ if (worthTryingToSplit(li)) {
+ return tryVNISplit(li, earliestStart);
+ }
+ // else
+ return StandardSpiller::spill(li, spillIs, earliestStart);
+ }
+
+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;
+ }
+
+};
+
}
llvm::Spiller* llvm::createSpiller(MachineFunction *mf, LiveIntervals *lis,
VirtRegMap *vrm) {
switch (spillerOpt) {
case trivial: return new TrivialSpiller(mf, lis, vrm); break;
- case standard: return new StandardSpiller(mf, lis, loopInfo, vrm); break;
+ case standard: return new StandardSpiller(lis, loopInfo, vrm); break;
+ case splitting: return new SplittingSpiller(mf, lis, loopInfo, vrm); break;
default: llvm_unreachable("Unreachable!"); break;
}
}
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