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Add support for aggressive load-use-store folding. This takes care of the
vast majority of code size regressions introduced by pre-alloc-splitting. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63274 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -37,8 +37,9 @@
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using namespace llvm;
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static cl::opt<int> PreSplitLimit("pre-split-limit", cl::init(-1), cl::Hidden);
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static cl::opt<int> DeadSplitLimit("dead-split-limit", cl::init(-1), cl::Hidden);
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STATISTIC(NumTotalSplits, "Number of intervals split");
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STATISTIC(NumSplits, "Number of intervals split");
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STATISTIC(NumRemats, "Number of intervals split by rematerialization");
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STATISTIC(NumFolds, "Number of intervals split with spill folding");
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STATISTIC(NumRenumbers, "Number of intervals renumbered into new registers");
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@ -77,8 +78,6 @@ namespace {
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// Def2SpillMap - A map from a def instruction index to spill index.
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DenseMap<unsigned, unsigned> Def2SpillMap;
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unsigned NumSplits;
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public:
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static char ID;
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@ -162,8 +161,8 @@ namespace {
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void RenumberValno(VNInfo* VN);
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void ReconstructLiveInterval(LiveInterval* LI);
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bool removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split);
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unsigned getNumberOfSpills(SmallPtrSet<MachineInstr*, 4>& MIs,
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unsigned Reg, int FrameIndex);
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unsigned getNumberOfNonSpills(SmallPtrSet<MachineInstr*, 4>& MIs,
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unsigned Reg, int FrameIndex, bool& TwoAddr);
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VNInfo* PerformPHIConstruction(MachineBasicBlock::iterator use,
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MachineBasicBlock* MBB,
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LiveInterval* LI,
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@ -789,6 +788,10 @@ void PreAllocSplitting::RenumberValno(VNInfo* VN) {
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MO.setReg(NewVReg);
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}
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// The renumbered vreg shares a stack slot with the old register.
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if (IntervalSSMap.count(CurrLI->reg))
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IntervalSSMap[NewVReg] = IntervalSSMap[CurrLI->reg];
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NumRenumbers++;
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}
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@ -1042,19 +1045,24 @@ PreAllocSplitting::SplitRegLiveIntervals(const TargetRegisterClass **RCs,
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return Change;
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}
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unsigned PreAllocSplitting::getNumberOfSpills(
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unsigned PreAllocSplitting::getNumberOfNonSpills(
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SmallPtrSet<MachineInstr*, 4>& MIs,
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unsigned Reg, int FrameIndex) {
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unsigned Spills = 0;
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unsigned Reg, int FrameIndex,
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bool& FeedsTwoAddr) {
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unsigned NonSpills = 0;
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for (SmallPtrSet<MachineInstr*, 4>::iterator UI = MIs.begin(), UE = MIs.end();
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UI != UI; ++UI) {
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UI != UE; ++UI) {
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int StoreFrameIndex;
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unsigned StoreVReg = TII->isStoreToStackSlot(*UI, StoreFrameIndex);
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if (StoreVReg == Reg && StoreFrameIndex == FrameIndex)
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Spills++;
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if (StoreVReg != Reg || StoreFrameIndex != FrameIndex)
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NonSpills++;
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int DefIdx = (*UI)->findRegisterDefOperandIdx(Reg);
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if (DefIdx != -1 && (*UI)->isRegReDefinedByTwoAddr(DefIdx))
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FeedsTwoAddr = true;
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}
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return Spills;
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return NonSpills;
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}
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/// removeDeadSpills - After doing splitting, filter through all intervals we've
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@ -1077,6 +1085,10 @@ bool PreAllocSplitting::removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split) {
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for (LiveInterval::vni_iterator VI = (*LI)->vni_begin(),
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VE = (*LI)->vni_end(); VI != VE; ++VI) {
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if (DeadSplitLimit != -1 && (int)NumDeadSpills == DeadSplitLimit)
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return changed;
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VNInfo* CurrVN = *VI;
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if (CurrVN->hasPHIKill) continue;
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@ -1096,9 +1108,67 @@ bool PreAllocSplitting::removeDeadSpills(SmallPtrSet<LiveInterval*, 8>& split) {
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continue;
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}
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unsigned SpillCount = getNumberOfSpills(VNUseCount[CurrVN],
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(*LI)->reg, FrameIndex);
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if (SpillCount != VNUseCount[CurrVN].size()) continue;
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bool FeedsTwoAddr = false;
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unsigned NonSpillCount = getNumberOfNonSpills(VNUseCount[CurrVN],
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(*LI)->reg, FrameIndex,
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FeedsTwoAddr);
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if (NonSpillCount == 1 && !FeedsTwoAddr) {
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SmallPtrSet<MachineInstr*, 4>::iterator UI = VNUseCount[CurrVN].begin();
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int StoreFrameIndex;
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unsigned StoreVReg = TII->isStoreToStackSlot(*UI, StoreFrameIndex);
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while (UI != VNUseCount[CurrVN].end() &&
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(StoreVReg == (*LI)->reg && StoreFrameIndex == FrameIndex)) {
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++UI;
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if (UI != VNUseCount[CurrVN].end())
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StoreVReg = TII->isStoreToStackSlot(*UI, StoreFrameIndex);
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}
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if (UI == VNUseCount[CurrVN].end()) continue;
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MachineInstr* use = *UI;
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int OpIdx = use->findRegisterUseOperandIdx((*LI)->reg, false);
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if (OpIdx == -1) continue;
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SmallVector<unsigned, 1> Ops;
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Ops.push_back(OpIdx);
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if (!TII->canFoldMemoryOperand(use, Ops)) continue;
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MachineInstr* NewMI =
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TII->foldMemoryOperand(*use->getParent()->getParent(),
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use, Ops, FrameIndex);
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if (!NewMI) continue;
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LIs->RemoveMachineInstrFromMaps(DefMI);
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LIs->ReplaceMachineInstrInMaps(use, NewMI);
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(*LI)->removeValNo(CurrVN);
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DefMI->eraseFromParent();
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MachineBasicBlock* MBB = use->getParent();
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NewMI = MBB->insert(MBB->erase(use), NewMI);
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VNUseCount[CurrVN].erase(use);
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for (SmallPtrSet<MachineInstr*, 4>::iterator II =
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VNUseCount[CurrVN].begin(), IE = VNUseCount[CurrVN].end();
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II != IE; ++II) {
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LIs->RemoveMachineInstrFromMaps(*II);
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(*II)->eraseFromParent();
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}
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for (DenseMap<VNInfo*, SmallPtrSet<MachineInstr*, 4> >::iterator
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VI = VNUseCount.begin(), VE = VNUseCount.end(); VI != VE; ++VI)
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if (VI->second.erase(use))
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VI->second.insert(NewMI);
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NumDeadSpills++;
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changed = true;
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continue;
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}
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if (NonSpillCount) continue;
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for (SmallPtrSet<MachineInstr*, 4>::iterator UI =
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VNUseCount[CurrVN].begin(), UE = VNUseCount[CurrVN].end();
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@ -1193,7 +1263,6 @@ bool PreAllocSplitting::runOnMachineFunction(MachineFunction &MF) {
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LSs = &getAnalysis<LiveStacks>();
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bool MadeChange = false;
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NumSplits = 0;
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// Make sure blocks are numbered in order.
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MF.RenumberBlocks();
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@ -1220,9 +1289,6 @@ bool PreAllocSplitting::runOnMachineFunction(MachineFunction &MF) {
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}
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MadeChange |= removeDeadSpills(Split);
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if (NumSplits)
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NumTotalSplits += NumSplits;
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return MadeChange;
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}
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