X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FSplitKit.cpp;h=51dddabed2d9ea7bb1892d44283563ffda3bb27f;hb=54f1a90d457ca270ee9ae84f521fe016cb830ee4;hp=73788f6ba0c45cd0ae52ae0d112ca54beb89cdf3;hpb=fd5c51342a429ecab86a645282d0b36b216c0256;p=oota-llvm.git diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp index 73788f6ba0c..51dddabed2d 100644 --- a/lib/CodeGen/SplitKit.cpp +++ b/lib/CodeGen/SplitKit.cpp @@ -12,15 +12,15 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "regalloc" #include "SplitKit.h" -#include "LiveRangeEdit.h" -#include "VirtRegMap.h" #include "llvm/ADT/Statistic.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/LiveRangeEdit.h" #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/MachineInstrBuilder.h" +#include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/VirtRegMap.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" #include "llvm/Target/TargetInstrInfo.h" @@ -28,42 +28,45 @@ using namespace llvm; +#define DEBUG_TYPE "regalloc" + STATISTIC(NumFinished, "Number of splits finished"); STATISTIC(NumSimple, "Number of splits that were simple"); +STATISTIC(NumCopies, "Number of copies inserted for splitting"); +STATISTIC(NumRemats, "Number of rematerialized defs for splitting"); +STATISTIC(NumRepairs, "Number of invalid live ranges repaired"); //===----------------------------------------------------------------------===// // Split Analysis //===----------------------------------------------------------------------===// -SplitAnalysis::SplitAnalysis(const VirtRegMap &vrm, - const LiveIntervals &lis, +SplitAnalysis::SplitAnalysis(const VirtRegMap &vrm, const LiveIntervals &lis, const MachineLoopInfo &mli) - : MF(vrm.getMachineFunction()), - VRM(vrm), - LIS(lis), - Loops(mli), - TII(*MF.getTarget().getInstrInfo()), - CurLI(0), - LastSplitPoint(MF.getNumBlockIDs()) {} + : MF(vrm.getMachineFunction()), VRM(vrm), LIS(lis), Loops(mli), + TII(*MF.getSubtarget().getInstrInfo()), CurLI(nullptr), + LastSplitPoint(MF.getNumBlockIDs()) {} void SplitAnalysis::clear() { UseSlots.clear(); UseBlocks.clear(); ThroughBlocks.clear(); - CurLI = 0; + CurLI = nullptr; + DidRepairRange = false; } SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) { const MachineBasicBlock *MBB = MF.getBlockNumbered(Num); + // FIXME: Handle multiple EH pad successors. const MachineBasicBlock *LPad = MBB->getLandingPadSuccessor(); std::pair &LSP = LastSplitPoint[Num]; + SlotIndex MBBEnd = LIS.getMBBEndIdx(MBB); // Compute split points on the first call. The pair is independent of the // current live interval. if (!LSP.first.isValid()) { MachineBasicBlock::const_iterator FirstTerm = MBB->getFirstTerminator(); if (FirstTerm == MBB->end()) - LSP.first = LIS.getMBBEndIdx(MBB); + LSP.first = MBBEnd; else LSP.first = LIS.getInstructionIndex(FirstTerm); @@ -72,20 +75,44 @@ SlotIndex SplitAnalysis::computeLastSplitPoint(unsigned Num) { return LSP.first; // There may not be a call instruction (?) in which case we ignore LPad. LSP.second = LSP.first; - for (MachineBasicBlock::const_iterator I = FirstTerm, E = MBB->begin(); - I != E; --I) - if (I->getDesc().isCall()) { + for (MachineBasicBlock::const_iterator I = MBB->end(), E = MBB->begin(); + I != E;) { + --I; + if (I->isCall()) { LSP.second = LIS.getInstructionIndex(I); break; } + } } // If CurLI is live into a landing pad successor, move the last split point // back to the call that may throw. - if (LPad && LSP.second.isValid() && LIS.isLiveInToMBB(*CurLI, LPad)) - return LSP.second; - else + if (!LPad || !LSP.second || !LIS.isLiveInToMBB(*CurLI, LPad)) + return LSP.first; + + // Find the value leaving MBB. + const VNInfo *VNI = CurLI->getVNInfoBefore(MBBEnd); + if (!VNI) + return LSP.first; + + // If the value leaving MBB was defined after the call in MBB, it can't + // really be live-in to the landing pad. This can happen if the landing pad + // has a PHI, and this register is undef on the exceptional edge. + // + if (!SlotIndex::isEarlierInstr(VNI->def, LSP.second) && VNI->def < MBBEnd) return LSP.first; + + // Value is properly live-in to the landing pad. + // Only allow splits before the call. + return LSP.second; +} + +MachineBasicBlock::iterator +SplitAnalysis::getLastSplitPointIter(MachineBasicBlock *MBB) { + SlotIndex LSP = getLastSplitPoint(MBB->getNumber()); + if (LSP == LIS.getMBBEndIdx(MBB)) + return MBB->end(); + return LIS.getInstructionFromIndex(LSP); } /// analyzeUses - Count instructions, basic blocks, and loops using CurLI. @@ -94,18 +121,15 @@ void SplitAnalysis::analyzeUses() { // First get all the defs from the interval values. This provides the correct // slots for early clobbers. - for (LiveInterval::const_vni_iterator I = CurLI->vni_begin(), - E = CurLI->vni_end(); I != E; ++I) - if (!(*I)->isPHIDef() && !(*I)->isUnused()) - UseSlots.push_back((*I)->def); + for (const VNInfo *VNI : CurLI->valnos) + if (!VNI->isPHIDef() && !VNI->isUnused()) + UseSlots.push_back(VNI->def); // Get use slots form the use-def chain. const MachineRegisterInfo &MRI = MF.getRegInfo(); - for (MachineRegisterInfo::use_nodbg_iterator - I = MRI.use_nodbg_begin(CurLI->reg), E = MRI.use_nodbg_end(); I != E; - ++I) - if (!I.getOperand().isUndef()) - UseSlots.push_back(LIS.getInstructionIndex(&*I).getDefIndex()); + for (MachineOperand &MO : MRI.use_nodbg_operands(CurLI->reg)) + if (!MO.isUndef()) + UseSlots.push_back(LIS.getInstructionIndex(MO.getParent()).getRegSlot()); array_pod_sort(UseSlots.begin(), UseSlots.end()); @@ -118,7 +142,9 @@ void SplitAnalysis::analyzeUses() { // Compute per-live block info. if (!calcLiveBlockInfo()) { // FIXME: calcLiveBlockInfo found inconsistencies in the live range. - // I am looking at you, SimpleRegisterCoalescing! + // I am looking at you, RegisterCoalescer! + DidRepairRange = true; + ++NumRepairs; DEBUG(dbgs() << "*** Fixing inconsistent live interval! ***\n"); const_cast(LIS) .shrinkToUses(const_cast(CurLI)); @@ -139,7 +165,7 @@ void SplitAnalysis::analyzeUses() { /// where CurLI is live. bool SplitAnalysis::calcLiveBlockInfo() { ThroughBlocks.resize(MF.getNumBlockIDs()); - NumThroughBlocks = 0; + NumThroughBlocks = NumGapBlocks = 0; if (CurLI->empty()) return true; @@ -151,62 +177,81 @@ bool SplitAnalysis::calcLiveBlockInfo() { UseE = UseSlots.end(); // Loop over basic blocks where CurLI is live. - MachineFunction::iterator MFI = LIS.getMBBFromIndex(LVI->start); + MachineFunction::iterator MFI = + LIS.getMBBFromIndex(LVI->start)->getIterator(); for (;;) { BlockInfo BI; - BI.MBB = MFI; + BI.MBB = &*MFI; SlotIndex Start, Stop; - tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB); - - // LVI is the first live segment overlapping MBB. - BI.LiveIn = LVI->start <= Start; - if (!BI.LiveIn) - BI.Def = LVI->start; - - // Find the first and last uses in the block. - bool Uses = UseI != UseE && *UseI < Stop; - if (Uses) { - BI.FirstUse = *UseI; - assert(BI.FirstUse >= Start); + std::tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB); + + // If the block contains no uses, the range must be live through. At one + // point, RegisterCoalescer could create dangling ranges that ended + // mid-block. + if (UseI == UseE || *UseI >= Stop) { + ++NumThroughBlocks; + ThroughBlocks.set(BI.MBB->getNumber()); + // The range shouldn't end mid-block if there are no uses. This shouldn't + // happen. + if (LVI->end < Stop) + return false; + } else { + // This block has uses. Find the first and last uses in the block. + BI.FirstInstr = *UseI; + assert(BI.FirstInstr >= Start); do ++UseI; while (UseI != UseE && *UseI < Stop); - BI.LastUse = UseI[-1]; - assert(BI.LastUse < Stop); - } + BI.LastInstr = UseI[-1]; + assert(BI.LastInstr < Stop); - // Look for gaps in the live range. - bool hasGap = false; - BI.LiveOut = true; - while (LVI->end < Stop) { - SlotIndex LastStop = LVI->end; - if (++LVI == LVE || LVI->start >= Stop) { - BI.Kill = LastStop; - BI.LiveOut = false; - break; + // LVI is the first live segment overlapping MBB. + BI.LiveIn = LVI->start <= Start; + + // When not live in, the first use should be a def. + if (!BI.LiveIn) { + assert(LVI->start == LVI->valno->def && "Dangling Segment start"); + assert(LVI->start == BI.FirstInstr && "First instr should be a def"); + BI.FirstDef = BI.FirstInstr; } - if (LastStop < LVI->start) { - hasGap = true; - BI.Kill = LastStop; - BI.Def = LVI->start; + + // Look for gaps in the live range. + BI.LiveOut = true; + while (LVI->end < Stop) { + SlotIndex LastStop = LVI->end; + if (++LVI == LVE || LVI->start >= Stop) { + BI.LiveOut = false; + BI.LastInstr = LastStop; + break; + } + + if (LastStop < LVI->start) { + // There is a gap in the live range. Create duplicate entries for the + // live-in snippet and the live-out snippet. + ++NumGapBlocks; + + // Push the Live-in part. + BI.LiveOut = false; + UseBlocks.push_back(BI); + UseBlocks.back().LastInstr = LastStop; + + // Set up BI for the live-out part. + BI.LiveIn = false; + BI.LiveOut = true; + BI.FirstInstr = BI.FirstDef = LVI->start; + } + + // A Segment that starts in the middle of the block must be a def. + assert(LVI->start == LVI->valno->def && "Dangling Segment start"); + if (!BI.FirstDef) + BI.FirstDef = LVI->start; } - } - // Don't set LiveThrough when the block has a gap. - BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut; - if (Uses) UseBlocks.push_back(BI); - else { - ++NumThroughBlocks; - ThroughBlocks.set(BI.MBB->getNumber()); - } - // FIXME: This should never happen. The live range stops or starts without a - // corresponding use. An earlier pass did something wrong. - if (!BI.LiveThrough && !Uses) - return false; - // LVI is now at LVE or LVI->end >= Stop. - if (LVI == LVE) - break; + // LVI is now at LVE or LVI->end >= Stop. + if (LVI == LVE) + break; + } // Live segment ends exactly at Stop. Move to the next segment. if (LVI->end == Stop && ++LVI == LVE) @@ -216,11 +261,37 @@ bool SplitAnalysis::calcLiveBlockInfo() { if (LVI->start < Stop) ++MFI; else - MFI = LIS.getMBBFromIndex(LVI->start); + MFI = LIS.getMBBFromIndex(LVI->start)->getIterator(); } + + assert(getNumLiveBlocks() == countLiveBlocks(CurLI) && "Bad block count"); return true; } +unsigned SplitAnalysis::countLiveBlocks(const LiveInterval *cli) const { + if (cli->empty()) + return 0; + LiveInterval *li = const_cast(cli); + LiveInterval::iterator LVI = li->begin(); + LiveInterval::iterator LVE = li->end(); + unsigned Count = 0; + + // Loop over basic blocks where li is live. + MachineFunction::const_iterator MFI = + LIS.getMBBFromIndex(LVI->start)->getIterator(); + SlotIndex Stop = LIS.getMBBEndIdx(&*MFI); + for (;;) { + ++Count; + LVI = li->advanceTo(LVI, Stop); + if (LVI == LVE) + return Count; + do { + ++MFI; + Stop = LIS.getMBBEndIdx(&*MFI); + } while (Stop <= LVI->start); + } +} + bool SplitAnalysis::isOriginalEndpoint(SlotIndex Idx) const { unsigned OrigReg = VRM.getOriginal(CurLI->reg); const LiveInterval &Orig = LIS.getInterval(OrigReg); @@ -247,34 +318,35 @@ void SplitAnalysis::analyze(const LiveInterval *li) { //===----------------------------------------------------------------------===// /// Create a new SplitEditor for editing the LiveInterval analyzed by SA. -SplitEditor::SplitEditor(SplitAnalysis &sa, - LiveIntervals &lis, - VirtRegMap &vrm, - MachineDominatorTree &mdt) - : SA(sa), LIS(lis), VRM(vrm), - MRI(vrm.getMachineFunction().getRegInfo()), - MDT(mdt), - TII(*vrm.getMachineFunction().getTarget().getInstrInfo()), - TRI(*vrm.getMachineFunction().getTarget().getRegisterInfo()), - Edit(0), - OpenIdx(0), - RegAssign(Allocator) -{} - -void SplitEditor::reset(LiveRangeEdit &lre) { - Edit = &lre; +SplitEditor::SplitEditor(SplitAnalysis &sa, LiveIntervals &lis, VirtRegMap &vrm, + MachineDominatorTree &mdt, + MachineBlockFrequencyInfo &mbfi) + : SA(sa), LIS(lis), VRM(vrm), MRI(vrm.getMachineFunction().getRegInfo()), + MDT(mdt), TII(*vrm.getMachineFunction().getSubtarget().getInstrInfo()), + TRI(*vrm.getMachineFunction().getSubtarget().getRegisterInfo()), + MBFI(mbfi), Edit(nullptr), OpenIdx(0), SpillMode(SM_Partition), + RegAssign(Allocator) {} + +void SplitEditor::reset(LiveRangeEdit &LRE, ComplementSpillMode SM) { + Edit = &LRE; + SpillMode = SM; OpenIdx = 0; RegAssign.clear(); Values.clear(); - // We don't need to clear LiveOutCache, only LiveOutSeen entries are read. - LiveOutSeen.clear(); + // Reset the LiveRangeCalc instances needed for this spill mode. + LRCalc[0].reset(&VRM.getMachineFunction(), LIS.getSlotIndexes(), &MDT, + &LIS.getVNInfoAllocator()); + if (SpillMode) + LRCalc[1].reset(&VRM.getMachineFunction(), LIS.getSlotIndexes(), &MDT, + &LIS.getVNInfoAllocator()); // We don't need an AliasAnalysis since we will only be performing // cheap-as-a-copy remats anyway. - Edit->anyRematerializable(LIS, TII, 0); + Edit->anyRematerializable(nullptr); } +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void SplitEditor::dump() const { if (RegAssign.empty()) { dbgs() << " empty\n"; @@ -285,6 +357,7 @@ void SplitEditor::dump() const { dbgs() << " [" << I.start() << ';' << I.stop() << "):" << I.value(); dbgs() << '\n'; } +#endif VNInfo *SplitEditor::defValue(unsigned RegIdx, const VNInfo *ParentVNI, @@ -292,14 +365,15 @@ VNInfo *SplitEditor::defValue(unsigned RegIdx, assert(ParentVNI && "Mapping NULL value"); assert(Idx.isValid() && "Invalid SlotIndex"); assert(Edit->getParent().getVNInfoAt(Idx) == ParentVNI && "Bad Parent VNI"); - LiveInterval *LI = Edit->get(RegIdx); + LiveInterval *LI = &LIS.getInterval(Edit->get(RegIdx)); // Create a new value. - VNInfo *VNI = LI->getNextValue(Idx, 0, LIS.getVNInfoAllocator()); + VNInfo *VNI = LI->getNextValue(Idx, LIS.getVNInfoAllocator()); // Use insert for lookup, so we can add missing values with a second lookup. std::pair InsP = - Values.insert(std::make_pair(std::make_pair(RegIdx, ParentVNI->id), VNI)); + Values.insert(std::make_pair(std::make_pair(RegIdx, ParentVNI->id), + ValueForcePair(VNI, false))); // This was the first time (RegIdx, ParentVNI) was mapped. // Keep it as a simple def without any liveness. @@ -307,227 +381,39 @@ VNInfo *SplitEditor::defValue(unsigned RegIdx, return VNI; // If the previous value was a simple mapping, add liveness for it now. - if (VNInfo *OldVNI = InsP.first->second) { + if (VNInfo *OldVNI = InsP.first->second.getPointer()) { SlotIndex Def = OldVNI->def; - LI->addRange(LiveRange(Def, Def.getNextSlot(), OldVNI)); - // No longer a simple mapping. - InsP.first->second = 0; + LI->addSegment(LiveInterval::Segment(Def, Def.getDeadSlot(), OldVNI)); + // No longer a simple mapping. Switch to a complex, non-forced mapping. + InsP.first->second = ValueForcePair(); } // This is a complex mapping, add liveness for VNI SlotIndex Def = VNI->def; - LI->addRange(LiveRange(Def, Def.getNextSlot(), VNI)); + LI->addSegment(LiveInterval::Segment(Def, Def.getDeadSlot(), VNI)); return VNI; } -void SplitEditor::markComplexMapped(unsigned RegIdx, const VNInfo *ParentVNI) { +void SplitEditor::forceRecompute(unsigned RegIdx, const VNInfo *ParentVNI) { assert(ParentVNI && "Mapping NULL value"); - VNInfo *&VNI = Values[std::make_pair(RegIdx, ParentVNI->id)]; + ValueForcePair &VFP = Values[std::make_pair(RegIdx, ParentVNI->id)]; + VNInfo *VNI = VFP.getPointer(); - // ParentVNI was either unmapped or already complex mapped. Either way. - if (!VNI) + // ParentVNI was either unmapped or already complex mapped. Either way, just + // set the force bit. + if (!VNI) { + VFP.setInt(true); return; + } // This was previously a single mapping. Make sure the old def is represented // by a trivial live range. SlotIndex Def = VNI->def; - Edit->get(RegIdx)->addRange(LiveRange(Def, Def.getNextSlot(), VNI)); - VNI = 0; -} - -// extendRange - Extend the live range to reach Idx. -// Potentially create phi-def values. -void SplitEditor::extendRange(unsigned RegIdx, SlotIndex Idx) { - assert(Idx.isValid() && "Invalid SlotIndex"); - MachineBasicBlock *IdxMBB = LIS.getMBBFromIndex(Idx); - assert(IdxMBB && "No MBB at Idx"); - LiveInterval *LI = Edit->get(RegIdx); - - // Is there a def in the same MBB we can extend? - if (LI->extendInBlock(LIS.getMBBStartIdx(IdxMBB), Idx)) - return; - - // Now for the fun part. We know that ParentVNI potentially has multiple defs, - // and we may need to create even more phi-defs to preserve VNInfo SSA form. - // Perform a search for all predecessor blocks where we know the dominating - // VNInfo. Insert phi-def VNInfos along the path back to IdxMBB. - - // Initialize the live-out cache the first time it is needed. - if (LiveOutSeen.empty()) { - unsigned N = VRM.getMachineFunction().getNumBlockIDs(); - LiveOutSeen.resize(N); - LiveOutCache.resize(N); - } - - // Blocks where LI should be live-in. - SmallVector LiveIn; - LiveIn.push_back(MDT[IdxMBB]); - - // Remember if we have seen more than one value. - bool UniqueVNI = true; - VNInfo *IdxVNI = 0; - - // Using LiveOutCache as a visited set, perform a BFS for all reaching defs. - for (unsigned i = 0; i != LiveIn.size(); ++i) { - MachineBasicBlock *MBB = LiveIn[i]->getBlock(); - assert(!MBB->pred_empty() && "Value live-in to entry block?"); - for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), - PE = MBB->pred_end(); PI != PE; ++PI) { - MachineBasicBlock *Pred = *PI; - LiveOutPair &LOP = LiveOutCache[Pred]; - - // Is this a known live-out block? - if (LiveOutSeen.test(Pred->getNumber())) { - if (VNInfo *VNI = LOP.first) { - if (IdxVNI && IdxVNI != VNI) - UniqueVNI = false; - IdxVNI = VNI; - } - continue; - } - - // First time. LOP is garbage and must be cleared below. - LiveOutSeen.set(Pred->getNumber()); - - // Does Pred provide a live-out value? - SlotIndex Start, Last; - tie(Start, Last) = LIS.getSlotIndexes()->getMBBRange(Pred); - Last = Last.getPrevSlot(); - VNInfo *VNI = LI->extendInBlock(Start, Last); - LOP.first = VNI; - if (VNI) { - LOP.second = MDT[LIS.getMBBFromIndex(VNI->def)]; - if (IdxVNI && IdxVNI != VNI) - UniqueVNI = false; - IdxVNI = VNI; - continue; - } - LOP.second = 0; - - // No, we need a live-in value for Pred as well - if (Pred != IdxMBB) - LiveIn.push_back(MDT[Pred]); - else - UniqueVNI = false; // Loopback to IdxMBB, ask updateSSA() for help. - } - } - - // We may need to add phi-def values to preserve the SSA form. - if (UniqueVNI) { - LiveOutPair LOP(IdxVNI, MDT[LIS.getMBBFromIndex(IdxVNI->def)]); - // Update LiveOutCache, but skip IdxMBB at LiveIn[0]. - for (unsigned i = 1, e = LiveIn.size(); i != e; ++i) - LiveOutCache[LiveIn[i]->getBlock()] = LOP; - } else - IdxVNI = updateSSA(RegIdx, LiveIn, Idx, IdxMBB); - - // Since we went through the trouble of a full BFS visiting all reaching defs, - // the values in LiveIn are now accurate. No more phi-defs are needed - // for these blocks, so we can color the live ranges. - for (unsigned i = 0, e = LiveIn.size(); i != e; ++i) { - MachineBasicBlock *MBB = LiveIn[i]->getBlock(); - SlotIndex Start = LIS.getMBBStartIdx(MBB); - VNInfo *VNI = LiveOutCache[MBB].first; - - // Anything in LiveIn other than IdxMBB is live-through. - // In IdxMBB, we should stop at Idx unless the same value is live-out. - if (MBB == IdxMBB && IdxVNI != VNI) - LI->addRange(LiveRange(Start, Idx.getNextSlot(), IdxVNI)); - else - LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI)); - } -} - -VNInfo *SplitEditor::updateSSA(unsigned RegIdx, - SmallVectorImpl &LiveIn, - SlotIndex Idx, - const MachineBasicBlock *IdxMBB) { - // This is essentially the same iterative algorithm that SSAUpdater uses, - // except we already have a dominator tree, so we don't have to recompute it. - LiveInterval *LI = Edit->get(RegIdx); - VNInfo *IdxVNI = 0; - unsigned Changes; - do { - Changes = 0; - // Propagate live-out values down the dominator tree, inserting phi-defs - // when necessary. Since LiveIn was created by a BFS, going backwards makes - // it more likely for us to visit immediate dominators before their - // children. - for (unsigned i = LiveIn.size(); i; --i) { - MachineDomTreeNode *Node = LiveIn[i-1]; - MachineBasicBlock *MBB = Node->getBlock(); - MachineDomTreeNode *IDom = Node->getIDom(); - LiveOutPair IDomValue; - - // We need a live-in value to a block with no immediate dominator? - // This is probably an unreachable block that has survived somehow. - bool needPHI = !IDom || !LiveOutSeen.test(IDom->getBlock()->getNumber()); - - // IDom dominates all of our predecessors, but it may not be the immediate - // dominator. Check if any of them have live-out values that are properly - // dominated by IDom. If so, we need a phi-def here. - if (!needPHI) { - IDomValue = LiveOutCache[IDom->getBlock()]; - for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), - PE = MBB->pred_end(); PI != PE; ++PI) { - LiveOutPair Value = LiveOutCache[*PI]; - if (!Value.first || Value.first == IDomValue.first) - continue; - // This predecessor is carrying something other than IDomValue. - // It could be because IDomValue hasn't propagated yet, or it could be - // because MBB is in the dominance frontier of that value. - if (MDT.dominates(IDom, Value.second)) { - needPHI = true; - break; - } - } - } - - // Create a phi-def if required. - if (needPHI) { - ++Changes; - SlotIndex Start = LIS.getMBBStartIdx(MBB); - VNInfo *VNI = LI->getNextValue(Start, 0, LIS.getVNInfoAllocator()); - VNI->setIsPHIDef(true); - // We no longer need LI to be live-in. - LiveIn.erase(LiveIn.begin()+(i-1)); - // Blocks in LiveIn are either IdxMBB, or have a value live-through. - if (MBB == IdxMBB) - IdxVNI = VNI; - // Check if we need to update live-out info. - LiveOutPair &LOP = LiveOutCache[MBB]; - if (LOP.second == Node || !LiveOutSeen.test(MBB->getNumber())) { - // We already have a live-out defined in MBB, so this must be IdxMBB. - assert(MBB == IdxMBB && "Adding phi-def to known live-out"); - LI->addRange(LiveRange(Start, Idx.getNextSlot(), VNI)); - } else { - // This phi-def is also live-out, so color the whole block. - LI->addRange(LiveRange(Start, LIS.getMBBEndIdx(MBB), VNI)); - LOP = LiveOutPair(VNI, Node); - } - } else if (IDomValue.first) { - // No phi-def here. Remember incoming value for IdxMBB. - if (MBB == IdxMBB) { - IdxVNI = IDomValue.first; - // IdxMBB need not be live-out. - if (!LiveOutSeen.test(MBB->getNumber())) - continue; - } - assert(LiveOutSeen.test(MBB->getNumber()) && "Expected live-out block"); - // Propagate IDomValue if needed: - // MBB is live-out and doesn't define its own value. - LiveOutPair &LOP = LiveOutCache[MBB]; - if (LOP.second != Node && LOP.first != IDomValue.first) { - ++Changes; - LOP = IDomValue; - } - } - } - } while (Changes); - - assert(IdxVNI && "Didn't find value for Idx"); - return IdxVNI; + LiveInterval *LI = &LIS.getInterval(Edit->get(RegIdx)); + LI->addSegment(LiveInterval::Segment(Def, Def.getDeadSlot(), VNI)); + // Mark as complex mapped, forced. + VFP = ValueForcePair(nullptr, true); } VNInfo *SplitEditor::defFromParent(unsigned RegIdx, @@ -535,44 +421,48 @@ VNInfo *SplitEditor::defFromParent(unsigned RegIdx, SlotIndex UseIdx, MachineBasicBlock &MBB, MachineBasicBlock::iterator I) { - MachineInstr *CopyMI = 0; + MachineInstr *CopyMI = nullptr; SlotIndex Def; - LiveInterval *LI = Edit->get(RegIdx); + LiveInterval *LI = &LIS.getInterval(Edit->get(RegIdx)); + + // We may be trying to avoid interference that ends at a deleted instruction, + // so always begin RegIdx 0 early and all others late. + bool Late = RegIdx != 0; // Attempt cheap-as-a-copy rematerialization. LiveRangeEdit::Remat RM(ParentVNI); - if (Edit->canRematerializeAt(RM, UseIdx, true, LIS)) { - Def = Edit->rematerializeAt(MBB, I, LI->reg, RM, LIS, TII, TRI); + if (Edit->canRematerializeAt(RM, UseIdx, true)) { + Def = Edit->rematerializeAt(MBB, I, LI->reg, RM, TRI, Late); + ++NumRemats; } else { // Can't remat, just insert a copy from parent. CopyMI = BuildMI(MBB, I, DebugLoc(), TII.get(TargetOpcode::COPY), LI->reg) .addReg(Edit->getReg()); - Def = LIS.InsertMachineInstrInMaps(CopyMI).getDefIndex(); + Def = LIS.getSlotIndexes()->insertMachineInstrInMaps(CopyMI, Late) + .getRegSlot(); + ++NumCopies; } // Define the value in Reg. - VNInfo *VNI = defValue(RegIdx, ParentVNI, Def); - VNI->setCopy(CopyMI); - return VNI; + return defValue(RegIdx, ParentVNI, Def); } /// Create a new virtual register and live interval. unsigned SplitEditor::openIntv() { - assert(!OpenIdx && "Previous LI not closed before openIntv"); - // Create the complement as index 0. if (Edit->empty()) - Edit->create(LIS, VRM); + Edit->createEmptyInterval(); // Create the open interval. OpenIdx = Edit->size(); - Edit->create(LIS, VRM); + Edit->createEmptyInterval(); return OpenIdx; } void SplitEditor::selectIntv(unsigned Idx) { assert(Idx != 0 && "Cannot select the complement interval"); assert(Idx < Edit->size() && "Can only select previously opened interval"); + DEBUG(dbgs() << " selectIntv " << OpenIdx << " -> " << Idx << '\n'); OpenIdx = Idx; } @@ -593,6 +483,24 @@ SlotIndex SplitEditor::enterIntvBefore(SlotIndex Idx) { return VNI->def; } +SlotIndex SplitEditor::enterIntvAfter(SlotIndex Idx) { + assert(OpenIdx && "openIntv not called before enterIntvAfter"); + DEBUG(dbgs() << " enterIntvAfter " << Idx); + Idx = Idx.getBoundaryIndex(); + VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx); + if (!ParentVNI) { + DEBUG(dbgs() << ": not live\n"); + return Idx; + } + DEBUG(dbgs() << ": valno " << ParentVNI->id << '\n'); + MachineInstr *MI = LIS.getInstructionFromIndex(Idx); + assert(MI && "enterIntvAfter called with invalid index"); + + VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Idx, *MI->getParent(), + std::next(MachineBasicBlock::iterator(MI))); + return VNI->def; +} + SlotIndex SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) { assert(OpenIdx && "openIntv not called before enterIntvAtEnd"); SlotIndex End = LIS.getMBBEndIdx(&MBB); @@ -605,7 +513,7 @@ SlotIndex SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) { } DEBUG(dbgs() << ": valno " << ParentVNI->id); VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Last, MBB, - LIS.getLastSplitPoint(Edit->getParent(), &MBB)); + SA.getLastSplitPointIter(&MBB)); RegAssign.insert(VNI->def, End, OpenIdx); DEBUG(dump()); return VNI->def; @@ -628,18 +536,29 @@ SlotIndex SplitEditor::leaveIntvAfter(SlotIndex Idx) { DEBUG(dbgs() << " leaveIntvAfter " << Idx); // The interval must be live beyond the instruction at Idx. - Idx = Idx.getBoundaryIndex(); - VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx); + SlotIndex Boundary = Idx.getBoundaryIndex(); + VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Boundary); if (!ParentVNI) { DEBUG(dbgs() << ": not live\n"); - return Idx.getNextSlot(); + return Boundary.getNextSlot(); } DEBUG(dbgs() << ": valno " << ParentVNI->id << '\n'); - - MachineInstr *MI = LIS.getInstructionFromIndex(Idx); + MachineInstr *MI = LIS.getInstructionFromIndex(Boundary); assert(MI && "No instruction at index"); - VNInfo *VNI = defFromParent(0, ParentVNI, Idx, *MI->getParent(), - llvm::next(MachineBasicBlock::iterator(MI))); + + // In spill mode, make live ranges as short as possible by inserting the copy + // before MI. This is only possible if that instruction doesn't redefine the + // value. The inserted COPY is not a kill, and we don't need to recompute + // the source live range. The spiller also won't try to hoist this copy. + if (SpillMode && !SlotIndex::isSameInstr(ParentVNI->def, Idx) && + MI->readsVirtualRegister(Edit->getReg())) { + forceRecompute(0, ParentVNI); + defFromParent(0, ParentVNI, Idx, *MI->getParent(), MI); + return Idx; + } + + VNInfo *VNI = defFromParent(0, ParentVNI, Boundary, *MI->getParent(), + std::next(MachineBasicBlock::iterator(MI))); return VNI->def; } @@ -648,7 +567,7 @@ SlotIndex SplitEditor::leaveIntvBefore(SlotIndex Idx) { DEBUG(dbgs() << " leaveIntvBefore " << Idx); // The interval must be live into the instruction at Idx. - Idx = Idx.getBoundaryIndex(); + Idx = Idx.getBaseIndex(); VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx); if (!ParentVNI) { DEBUG(dbgs() << ": not live\n"); @@ -683,42 +602,232 @@ SlotIndex SplitEditor::leaveIntvAtTop(MachineBasicBlock &MBB) { void SplitEditor::overlapIntv(SlotIndex Start, SlotIndex End) { assert(OpenIdx && "openIntv not called before overlapIntv"); const VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Start); - assert(ParentVNI == Edit->getParent().getVNInfoAt(End.getPrevSlot()) && + assert(ParentVNI == Edit->getParent().getVNInfoBefore(End) && "Parent changes value in extended range"); assert(LIS.getMBBFromIndex(Start) == LIS.getMBBFromIndex(End) && "Range cannot span basic blocks"); - // The complement interval will be extended as needed by extendRange(). + // The complement interval will be extended as needed by LRCalc.extend(). if (ParentVNI) - markComplexMapped(0, ParentVNI); + forceRecompute(0, ParentVNI); DEBUG(dbgs() << " overlapIntv [" << Start << ';' << End << "):"); RegAssign.insert(Start, End, OpenIdx); DEBUG(dump()); } -/// closeIntv - Indicate that we are done editing the currently open -/// LiveInterval, and ranges can be trimmed. -void SplitEditor::closeIntv() { - assert(OpenIdx && "openIntv not called before closeIntv"); - OpenIdx = 0; +//===----------------------------------------------------------------------===// +// Spill modes +//===----------------------------------------------------------------------===// + +void SplitEditor::removeBackCopies(SmallVectorImpl &Copies) { + LiveInterval *LI = &LIS.getInterval(Edit->get(0)); + DEBUG(dbgs() << "Removing " << Copies.size() << " back-copies.\n"); + RegAssignMap::iterator AssignI; + AssignI.setMap(RegAssign); + + for (unsigned i = 0, e = Copies.size(); i != e; ++i) { + SlotIndex Def = Copies[i]->def; + MachineInstr *MI = LIS.getInstructionFromIndex(Def); + assert(MI && "No instruction for back-copy"); + + MachineBasicBlock *MBB = MI->getParent(); + MachineBasicBlock::iterator MBBI(MI); + bool AtBegin; + do AtBegin = MBBI == MBB->begin(); + while (!AtBegin && (--MBBI)->isDebugValue()); + + DEBUG(dbgs() << "Removing " << Def << '\t' << *MI); + LIS.removeVRegDefAt(*LI, Def); + LIS.RemoveMachineInstrFromMaps(MI); + MI->eraseFromParent(); + + // Adjust RegAssign if a register assignment is killed at Def. We want to + // avoid calculating the live range of the source register if possible. + AssignI.find(Def.getPrevSlot()); + if (!AssignI.valid() || AssignI.start() >= Def) + continue; + // If MI doesn't kill the assigned register, just leave it. + if (AssignI.stop() != Def) + continue; + unsigned RegIdx = AssignI.value(); + if (AtBegin || !MBBI->readsVirtualRegister(Edit->getReg())) { + DEBUG(dbgs() << " cannot find simple kill of RegIdx " << RegIdx << '\n'); + forceRecompute(RegIdx, Edit->getParent().getVNInfoAt(Def)); + } else { + SlotIndex Kill = LIS.getInstructionIndex(MBBI).getRegSlot(); + DEBUG(dbgs() << " move kill to " << Kill << '\t' << *MBBI); + AssignI.setStop(Kill); + } + } +} + +MachineBasicBlock* +SplitEditor::findShallowDominator(MachineBasicBlock *MBB, + MachineBasicBlock *DefMBB) { + if (MBB == DefMBB) + return MBB; + assert(MDT.dominates(DefMBB, MBB) && "MBB must be dominated by the def."); + + const MachineLoopInfo &Loops = SA.Loops; + const MachineLoop *DefLoop = Loops.getLoopFor(DefMBB); + MachineDomTreeNode *DefDomNode = MDT[DefMBB]; + + // Best candidate so far. + MachineBasicBlock *BestMBB = MBB; + unsigned BestDepth = UINT_MAX; + + for (;;) { + const MachineLoop *Loop = Loops.getLoopFor(MBB); + + // MBB isn't in a loop, it doesn't get any better. All dominators have a + // higher frequency by definition. + if (!Loop) { + DEBUG(dbgs() << "Def in BB#" << DefMBB->getNumber() << " dominates BB#" + << MBB->getNumber() << " at depth 0\n"); + return MBB; + } + + // We'll never be able to exit the DefLoop. + if (Loop == DefLoop) { + DEBUG(dbgs() << "Def in BB#" << DefMBB->getNumber() << " dominates BB#" + << MBB->getNumber() << " in the same loop\n"); + return MBB; + } + + // Least busy dominator seen so far. + unsigned Depth = Loop->getLoopDepth(); + if (Depth < BestDepth) { + BestMBB = MBB; + BestDepth = Depth; + DEBUG(dbgs() << "Def in BB#" << DefMBB->getNumber() << " dominates BB#" + << MBB->getNumber() << " at depth " << Depth << '\n'); + } + + // Leave loop by going to the immediate dominator of the loop header. + // This is a bigger stride than simply walking up the dominator tree. + MachineDomTreeNode *IDom = MDT[Loop->getHeader()]->getIDom(); + + // Too far up the dominator tree? + if (!IDom || !MDT.dominates(DefDomNode, IDom)) + return BestMBB; + + MBB = IDom->getBlock(); + } } -/// transferSimpleValues - Transfer all simply defined values to the new live -/// ranges. -/// Values that were rematerialized or that have multiple defs are left alone. -bool SplitEditor::transferSimpleValues() { +void SplitEditor::hoistCopiesForSize() { + // Get the complement interval, always RegIdx 0. + LiveInterval *LI = &LIS.getInterval(Edit->get(0)); + LiveInterval *Parent = &Edit->getParent(); + + // Track the nearest common dominator for all back-copies for each ParentVNI, + // indexed by ParentVNI->id. + typedef std::pair DomPair; + SmallVector NearestDom(Parent->getNumValNums()); + + // Find the nearest common dominator for parent values with multiple + // back-copies. If a single back-copy dominates, put it in DomPair.second. + for (VNInfo *VNI : LI->valnos) { + if (VNI->isUnused()) + continue; + VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(VNI->def); + assert(ParentVNI && "Parent not live at complement def"); + + // Don't hoist remats. The complement is probably going to disappear + // completely anyway. + if (Edit->didRematerialize(ParentVNI)) + continue; + + MachineBasicBlock *ValMBB = LIS.getMBBFromIndex(VNI->def); + DomPair &Dom = NearestDom[ParentVNI->id]; + + // Keep directly defined parent values. This is either a PHI or an + // instruction in the complement range. All other copies of ParentVNI + // should be eliminated. + if (VNI->def == ParentVNI->def) { + DEBUG(dbgs() << "Direct complement def at " << VNI->def << '\n'); + Dom = DomPair(ValMBB, VNI->def); + continue; + } + // Skip the singly mapped values. There is nothing to gain from hoisting a + // single back-copy. + if (Values.lookup(std::make_pair(0, ParentVNI->id)).getPointer()) { + DEBUG(dbgs() << "Single complement def at " << VNI->def << '\n'); + continue; + } + + if (!Dom.first) { + // First time we see ParentVNI. VNI dominates itself. + Dom = DomPair(ValMBB, VNI->def); + } else if (Dom.first == ValMBB) { + // Two defs in the same block. Pick the earlier def. + if (!Dom.second.isValid() || VNI->def < Dom.second) + Dom.second = VNI->def; + } else { + // Different basic blocks. Check if one dominates. + MachineBasicBlock *Near = + MDT.findNearestCommonDominator(Dom.first, ValMBB); + if (Near == ValMBB) + // Def ValMBB dominates. + Dom = DomPair(ValMBB, VNI->def); + else if (Near != Dom.first) + // None dominate. Hoist to common dominator, need new def. + Dom = DomPair(Near, SlotIndex()); + } + + DEBUG(dbgs() << "Multi-mapped complement " << VNI->id << '@' << VNI->def + << " for parent " << ParentVNI->id << '@' << ParentVNI->def + << " hoist to BB#" << Dom.first->getNumber() << ' ' + << Dom.second << '\n'); + } + + // Insert the hoisted copies. + for (unsigned i = 0, e = Parent->getNumValNums(); i != e; ++i) { + DomPair &Dom = NearestDom[i]; + if (!Dom.first || Dom.second.isValid()) + continue; + // This value needs a hoisted copy inserted at the end of Dom.first. + VNInfo *ParentVNI = Parent->getValNumInfo(i); + MachineBasicBlock *DefMBB = LIS.getMBBFromIndex(ParentVNI->def); + // Get a less loopy dominator than Dom.first. + Dom.first = findShallowDominator(Dom.first, DefMBB); + SlotIndex Last = LIS.getMBBEndIdx(Dom.first).getPrevSlot(); + Dom.second = + defFromParent(0, ParentVNI, Last, *Dom.first, + SA.getLastSplitPointIter(Dom.first))->def; + } + + // Remove redundant back-copies that are now known to be dominated by another + // def with the same value. + SmallVector BackCopies; + for (VNInfo *VNI : LI->valnos) { + if (VNI->isUnused()) + continue; + VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(VNI->def); + const DomPair &Dom = NearestDom[ParentVNI->id]; + if (!Dom.first || Dom.second == VNI->def) + continue; + BackCopies.push_back(VNI); + forceRecompute(0, ParentVNI); + } + removeBackCopies(BackCopies); +} + + +/// transferValues - Transfer all possible values to the new live ranges. +/// Values that were rematerialized are left alone, they need LRCalc.extend(). +bool SplitEditor::transferValues() { bool Skipped = false; RegAssignMap::const_iterator AssignI = RegAssign.begin(); - for (LiveInterval::const_iterator ParentI = Edit->getParent().begin(), - ParentE = Edit->getParent().end(); ParentI != ParentE; ++ParentI) { - DEBUG(dbgs() << " blit " << *ParentI << ':'); - VNInfo *ParentVNI = ParentI->valno; + for (const LiveRange::Segment &S : Edit->getParent()) { + DEBUG(dbgs() << " blit " << S << ':'); + VNInfo *ParentVNI = S.valno; // RegAssign has holes where RegIdx 0 should be used. - SlotIndex Start = ParentI->start; + SlotIndex Start = S.start; AssignI.advanceTo(Start); do { unsigned RegIdx; - SlotIndex End = ParentI->end; + SlotIndex End = S.end; if (!AssignI.valid()) { RegIdx = 0; } else if (AssignI.start() <= Start) { @@ -731,37 +840,108 @@ bool SplitEditor::transferSimpleValues() { RegIdx = 0; End = std::min(End, AssignI.start()); } + + // The interval [Start;End) is continuously mapped to RegIdx, ParentVNI. DEBUG(dbgs() << " [" << Start << ';' << End << ")=" << RegIdx); - if (VNInfo *VNI = Values.lookup(std::make_pair(RegIdx, ParentVNI->id))) { + LiveRange &LR = LIS.getInterval(Edit->get(RegIdx)); + + // Check for a simply defined value that can be blitted directly. + ValueForcePair VFP = Values.lookup(std::make_pair(RegIdx, ParentVNI->id)); + if (VNInfo *VNI = VFP.getPointer()) { DEBUG(dbgs() << ':' << VNI->id); - Edit->get(RegIdx)->addRange(LiveRange(Start, End, VNI)); - } else + LR.addSegment(LiveInterval::Segment(Start, End, VNI)); + Start = End; + continue; + } + + // Skip values with forced recomputation. + if (VFP.getInt()) { + DEBUG(dbgs() << "(recalc)"); Skipped = true; + Start = End; + continue; + } + + LiveRangeCalc &LRC = getLRCalc(RegIdx); + + // This value has multiple defs in RegIdx, but it wasn't rematerialized, + // so the live range is accurate. Add live-in blocks in [Start;End) to the + // LiveInBlocks. + MachineFunction::iterator MBB = LIS.getMBBFromIndex(Start)->getIterator(); + SlotIndex BlockStart, BlockEnd; + std::tie(BlockStart, BlockEnd) = LIS.getSlotIndexes()->getMBBRange(&*MBB); + + // The first block may be live-in, or it may have its own def. + if (Start != BlockStart) { + VNInfo *VNI = LR.extendInBlock(BlockStart, std::min(BlockEnd, End)); + assert(VNI && "Missing def for complex mapped value"); + DEBUG(dbgs() << ':' << VNI->id << "*BB#" << MBB->getNumber()); + // MBB has its own def. Is it also live-out? + if (BlockEnd <= End) + LRC.setLiveOutValue(&*MBB, VNI); + + // Skip to the next block for live-in. + ++MBB; + BlockStart = BlockEnd; + } + + // Handle the live-in blocks covered by [Start;End). + assert(Start <= BlockStart && "Expected live-in block"); + while (BlockStart < End) { + DEBUG(dbgs() << ">BB#" << MBB->getNumber()); + BlockEnd = LIS.getMBBEndIdx(&*MBB); + if (BlockStart == ParentVNI->def) { + // This block has the def of a parent PHI, so it isn't live-in. + assert(ParentVNI->isPHIDef() && "Non-phi defined at block start?"); + VNInfo *VNI = LR.extendInBlock(BlockStart, std::min(BlockEnd, End)); + assert(VNI && "Missing def for complex mapped parent PHI"); + if (End >= BlockEnd) + LRC.setLiveOutValue(&*MBB, VNI); // Live-out as well. + } else { + // This block needs a live-in value. The last block covered may not + // be live-out. + if (End < BlockEnd) + LRC.addLiveInBlock(LR, MDT[&*MBB], End); + else { + // Live-through, and we don't know the value. + LRC.addLiveInBlock(LR, MDT[&*MBB]); + LRC.setLiveOutValue(&*MBB, nullptr); + } + } + BlockStart = BlockEnd; + ++MBB; + } Start = End; - } while (Start != ParentI->end); + } while (Start != S.end); DEBUG(dbgs() << '\n'); } + + LRCalc[0].calculateValues(); + if (SpillMode) + LRCalc[1].calculateValues(); + return Skipped; } void SplitEditor::extendPHIKillRanges() { // Extend live ranges to be live-out for successor PHI values. - for (LiveInterval::const_vni_iterator I = Edit->getParent().vni_begin(), - E = Edit->getParent().vni_end(); I != E; ++I) { - const VNInfo *PHIVNI = *I; + for (const VNInfo *PHIVNI : Edit->getParent().valnos) { if (PHIVNI->isUnused() || !PHIVNI->isPHIDef()) continue; unsigned RegIdx = RegAssign.lookup(PHIVNI->def); + LiveRange &LR = LIS.getInterval(Edit->get(RegIdx)); + LiveRangeCalc &LRC = getLRCalc(RegIdx); MachineBasicBlock *MBB = LIS.getMBBFromIndex(PHIVNI->def); for (MachineBasicBlock::pred_iterator PI = MBB->pred_begin(), PE = MBB->pred_end(); PI != PE; ++PI) { - SlotIndex End = LIS.getMBBEndIdx(*PI).getPrevSlot(); + SlotIndex End = LIS.getMBBEndIdx(*PI); + SlotIndex LastUse = End.getPrevSlot(); // The predecessor may not have a live-out value. That is OK, like an // undef PHI operand. - if (Edit->getParent().liveAt(End)) { - assert(RegAssign.lookup(End) == RegIdx && + if (Edit->getParent().liveAt(LastUse)) { + assert(RegAssign.lookup(LastUse) == RegIdx && "Different register assignment in phi predecessor"); - extendRange(RegIdx, End); + LRC.extend(LR, End); } } } @@ -771,7 +951,7 @@ void SplitEditor::extendPHIKillRanges() { void SplitEditor::rewriteAssigned(bool ExtendRanges) { for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(Edit->getReg()), RE = MRI.reg_end(); RI != RE;) { - MachineOperand &MO = RI.getOperand(); + MachineOperand &MO = *RI; MachineInstr *MI = MO.getParent(); ++RI; // LiveDebugVariables should have handled all DBG_VALUE instructions. @@ -781,25 +961,22 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) { continue; } - // operands don't really read the register, so just assign them to - // the complement. - if (MO.isUse() && MO.isUndef()) { - MO.setReg(Edit->get(0)->reg); - continue; - } - + // operands don't really read the register, so it doesn't matter + // which register we choose. When the use operand is tied to a def, we must + // use the same register as the def, so just do that always. SlotIndex Idx = LIS.getInstructionIndex(MI); - if (MO.isDef()) - Idx = MO.isEarlyClobber() ? Idx.getUseIndex() : Idx.getDefIndex(); + if (MO.isDef() || MO.isUndef()) + Idx = Idx.getRegSlot(MO.isEarlyClobber()); // Rewrite to the mapped register at Idx. unsigned RegIdx = RegAssign.lookup(Idx); - MO.setReg(Edit->get(RegIdx)->reg); + LiveInterval *LI = &LIS.getInterval(Edit->get(RegIdx)); + MO.setReg(LI->reg); DEBUG(dbgs() << " rewr BB#" << MI->getParent()->getNumber() << '\t' << Idx << ':' << RegIdx << '\t' << *MI); // Extend liveness to Idx if the instruction reads reg. - if (!ExtendRanges) + if (!ExtendRanges || MO.isUndef()) continue; // Skip instructions that don't read Reg. @@ -812,22 +989,21 @@ void SplitEditor::rewriteAssigned(bool ExtendRanges) { if (!Edit->getParent().liveAt(Idx)) continue; } else - Idx = Idx.getUseIndex(); + Idx = Idx.getRegSlot(true); - extendRange(RegIdx, Idx); + getLRCalc(RegIdx).extend(*LI, Idx.getNextSlot()); } } void SplitEditor::deleteRematVictims() { SmallVector Dead; for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I){ - LiveInterval *LI = *I; - for (LiveInterval::const_iterator LII = LI->begin(), LIE = LI->end(); - LII != LIE; ++LII) { - // Dead defs end at the store slot. - if (LII->end != LII->valno->def.getNextSlot()) + LiveInterval *LI = &LIS.getInterval(*I); + for (const LiveRange::Segment &S : LI->segments) { + // Dead defs end at the dead slot. + if (S.end != S.valno->def.getDeadSlot()) continue; - MachineInstr *MI = LIS.getInstructionFromIndex(LII->valno->def); + MachineInstr *MI = LIS.getInstructionFromIndex(S.valno->def); assert(MI && "Missing instruction for dead def"); MI->addRegisterDead(LI->reg, &TRI); @@ -842,76 +1018,89 @@ void SplitEditor::deleteRematVictims() { if (Dead.empty()) return; - Edit->eliminateDeadDefs(Dead, LIS, VRM, TII); + Edit->eliminateDeadDefs(Dead); } -void SplitEditor::finish() { - assert(OpenIdx == 0 && "Previous LI not closed before rewrite"); +void SplitEditor::finish(SmallVectorImpl *LRMap) { ++NumFinished; // At this point, the live intervals in Edit contain VNInfos corresponding to // the inserted copies. // Add the original defs from the parent interval. - for (LiveInterval::const_vni_iterator I = Edit->getParent().vni_begin(), - E = Edit->getParent().vni_end(); I != E; ++I) { - const VNInfo *ParentVNI = *I; + for (const VNInfo *ParentVNI : Edit->getParent().valnos) { if (ParentVNI->isUnused()) continue; unsigned RegIdx = RegAssign.lookup(ParentVNI->def); - VNInfo *VNI = defValue(RegIdx, ParentVNI, ParentVNI->def); - VNI->setIsPHIDef(ParentVNI->isPHIDef()); - VNI->setCopy(ParentVNI->getCopy()); + defValue(RegIdx, ParentVNI, ParentVNI->def); - // Mark rematted values as complex everywhere to force liveness computation. + // Force rematted values to be recomputed everywhere. // The new live ranges may be truncated. if (Edit->didRematerialize(ParentVNI)) for (unsigned i = 0, e = Edit->size(); i != e; ++i) - markComplexMapped(i, ParentVNI); + forceRecompute(i, ParentVNI); } -#ifndef NDEBUG - // Every new interval must have a def by now, otherwise the split is bogus. - for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I) - assert((*I)->hasAtLeastOneValue() && "Split interval has no value"); -#endif + // Hoist back-copies to the complement interval when in spill mode. + switch (SpillMode) { + case SM_Partition: + // Leave all back-copies as is. + break; + case SM_Size: + hoistCopiesForSize(); + break; + case SM_Speed: + llvm_unreachable("Spill mode 'speed' not implemented yet"); + } - // Transfer the simply mapped values, check if any are complex. - bool Complex = transferSimpleValues(); - if (Complex) + // Transfer the simply mapped values, check if any are skipped. + bool Skipped = transferValues(); + if (Skipped) extendPHIKillRanges(); else ++NumSimple; // Rewrite virtual registers, possibly extending ranges. - rewriteAssigned(Complex); + rewriteAssigned(Skipped); // Delete defs that were rematted everywhere. - if (Complex) + if (Skipped) deleteRematVictims(); // Get rid of unused values and set phi-kill flags. - for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I) - (*I)->RenumberValues(LIS); + for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I) { + LiveInterval &LI = LIS.getInterval(*I); + LI.RenumberValues(); + } + + // Provide a reverse mapping from original indices to Edit ranges. + if (LRMap) { + LRMap->clear(); + for (unsigned i = 0, e = Edit->size(); i != e; ++i) + LRMap->push_back(i); + } // Now check if any registers were separated into multiple components. ConnectedVNInfoEqClasses ConEQ(LIS); for (unsigned i = 0, e = Edit->size(); i != e; ++i) { // Don't use iterators, they are invalidated by create() below. - LiveInterval *li = Edit->get(i); - unsigned NumComp = ConEQ.Classify(li); - if (NumComp <= 1) - continue; - DEBUG(dbgs() << " " << NumComp << " components: " << *li << '\n'); - SmallVector dups; - dups.push_back(li); - for (unsigned i = 1; i != NumComp; ++i) - dups.push_back(&Edit->create(LIS, VRM)); - ConEQ.Distribute(&dups[0], MRI); + unsigned VReg = Edit->get(i); + LiveInterval &LI = LIS.getInterval(VReg); + SmallVector SplitLIs; + LIS.splitSeparateComponents(LI, SplitLIs); + unsigned Original = VRM.getOriginal(VReg); + for (LiveInterval *SplitLI : SplitLIs) + VRM.setIsSplitFromReg(SplitLI->reg, Original); + + // The new intervals all map back to i. + if (LRMap) + LRMap->resize(Edit->size(), i); } // Calculate spill weight and allocation hints for new intervals. - Edit->calculateRegClassAndHint(VRM.getMachineFunction(), LIS, SA.Loops); + Edit->calculateRegClassAndHint(VRM.getMachineFunction(), SA.Loops, MBFI); + + assert(!LRMap || LRMap->size() == Edit->size()); } @@ -919,47 +1108,304 @@ void SplitEditor::finish() { // Single Block Splitting //===----------------------------------------------------------------------===// -/// getMultiUseBlocks - if CurLI has more than one use in a basic block, it -/// may be an advantage to split CurLI for the duration of the block. -bool SplitAnalysis::getMultiUseBlocks(BlockPtrSet &Blocks) { - // If CurLI is local to one block, there is no point to splitting it. - if (UseBlocks.size() <= 1) +bool SplitAnalysis::shouldSplitSingleBlock(const BlockInfo &BI, + bool SingleInstrs) const { + // Always split for multiple instructions. + if (!BI.isOneInstr()) + return true; + // Don't split for single instructions unless explicitly requested. + if (!SingleInstrs) return false; - // Add blocks with multiple uses. - for (unsigned i = 0, e = UseBlocks.size(); i != e; ++i) { - const BlockInfo &BI = UseBlocks[i]; - if (BI.FirstUse == BI.LastUse) - continue; - Blocks.insert(BI.MBB); - } - return !Blocks.empty(); + // Splitting a live-through range always makes progress. + if (BI.LiveIn && BI.LiveOut) + return true; + // No point in isolating a copy. It has no register class constraints. + if (LIS.getInstructionFromIndex(BI.FirstInstr)->isCopyLike()) + return false; + // Finally, don't isolate an end point that was created by earlier splits. + return isOriginalEndpoint(BI.FirstInstr); } void SplitEditor::splitSingleBlock(const SplitAnalysis::BlockInfo &BI) { openIntv(); SlotIndex LastSplitPoint = SA.getLastSplitPoint(BI.MBB->getNumber()); - SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstUse, + SlotIndex SegStart = enterIntvBefore(std::min(BI.FirstInstr, LastSplitPoint)); - if (!BI.LiveOut || BI.LastUse < LastSplitPoint) { - useIntv(SegStart, leaveIntvAfter(BI.LastUse)); + if (!BI.LiveOut || BI.LastInstr < LastSplitPoint) { + useIntv(SegStart, leaveIntvAfter(BI.LastInstr)); } else { // The last use is after the last valid split point. SlotIndex SegStop = leaveIntvBefore(LastSplitPoint); useIntv(SegStart, SegStop); - overlapIntv(SegStop, BI.LastUse); + overlapIntv(SegStop, BI.LastInstr); + } +} + + +//===----------------------------------------------------------------------===// +// Global Live Range Splitting Support +//===----------------------------------------------------------------------===// + +// These methods support a method of global live range splitting that uses a +// global algorithm to decide intervals for CFG edges. They will insert split +// points and color intervals in basic blocks while avoiding interference. +// +// Note that splitSingleBlock is also useful for blocks where both CFG edges +// are on the stack. + +void SplitEditor::splitLiveThroughBlock(unsigned MBBNum, + unsigned IntvIn, SlotIndex LeaveBefore, + unsigned IntvOut, SlotIndex EnterAfter){ + SlotIndex Start, Stop; + std::tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(MBBNum); + + DEBUG(dbgs() << "BB#" << MBBNum << " [" << Start << ';' << Stop + << ") intf " << LeaveBefore << '-' << EnterAfter + << ", live-through " << IntvIn << " -> " << IntvOut); + + assert((IntvIn || IntvOut) && "Use splitSingleBlock for isolated blocks"); + + assert((!LeaveBefore || LeaveBefore < Stop) && "Interference after block"); + assert((!IntvIn || !LeaveBefore || LeaveBefore > Start) && "Impossible intf"); + assert((!EnterAfter || EnterAfter >= Start) && "Interference before block"); + + MachineBasicBlock *MBB = VRM.getMachineFunction().getBlockNumbered(MBBNum); + + if (!IntvOut) { + DEBUG(dbgs() << ", spill on entry.\n"); + // + // <<<<<<<<< Possible LeaveBefore interference. + // |-----------| Live through. + // -____________ Spill on entry. + // + selectIntv(IntvIn); + SlotIndex Idx = leaveIntvAtTop(*MBB); + assert((!LeaveBefore || Idx <= LeaveBefore) && "Interference"); + (void)Idx; + return; + } + + if (!IntvIn) { + DEBUG(dbgs() << ", reload on exit.\n"); + // + // >>>>>>> Possible EnterAfter interference. + // |-----------| Live through. + // ___________-- Reload on exit. + // + selectIntv(IntvOut); + SlotIndex Idx = enterIntvAtEnd(*MBB); + assert((!EnterAfter || Idx >= EnterAfter) && "Interference"); + (void)Idx; + return; + } + + if (IntvIn == IntvOut && !LeaveBefore && !EnterAfter) { + DEBUG(dbgs() << ", straight through.\n"); + // + // |-----------| Live through. + // ------------- Straight through, same intv, no interference. + // + selectIntv(IntvOut); + useIntv(Start, Stop); + return; } - closeIntv(); + + // We cannot legally insert splits after LSP. + SlotIndex LSP = SA.getLastSplitPoint(MBBNum); + assert((!IntvOut || !EnterAfter || EnterAfter < LSP) && "Impossible intf"); + + if (IntvIn != IntvOut && (!LeaveBefore || !EnterAfter || + LeaveBefore.getBaseIndex() > EnterAfter.getBoundaryIndex())) { + DEBUG(dbgs() << ", switch avoiding interference.\n"); + // + // >>>> <<<< Non-overlapping EnterAfter/LeaveBefore interference. + // |-----------| Live through. + // ------======= Switch intervals between interference. + // + selectIntv(IntvOut); + SlotIndex Idx; + if (LeaveBefore && LeaveBefore < LSP) { + Idx = enterIntvBefore(LeaveBefore); + useIntv(Idx, Stop); + } else { + Idx = enterIntvAtEnd(*MBB); + } + selectIntv(IntvIn); + useIntv(Start, Idx); + assert((!LeaveBefore || Idx <= LeaveBefore) && "Interference"); + assert((!EnterAfter || Idx >= EnterAfter) && "Interference"); + return; + } + + DEBUG(dbgs() << ", create local intv for interference.\n"); + // + // >>><><><><<<< Overlapping EnterAfter/LeaveBefore interference. + // |-----------| Live through. + // ==---------== Switch intervals before/after interference. + // + assert(LeaveBefore <= EnterAfter && "Missed case"); + + selectIntv(IntvOut); + SlotIndex Idx = enterIntvAfter(EnterAfter); + useIntv(Idx, Stop); + assert((!EnterAfter || Idx >= EnterAfter) && "Interference"); + + selectIntv(IntvIn); + Idx = leaveIntvBefore(LeaveBefore); + useIntv(Start, Idx); + assert((!LeaveBefore || Idx <= LeaveBefore) && "Interference"); } -/// splitSingleBlocks - Split CurLI into a separate live interval inside each -/// basic block in Blocks. -void SplitEditor::splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks) { - DEBUG(dbgs() << " splitSingleBlocks for " << Blocks.size() << " blocks.\n"); - ArrayRef UseBlocks = SA.getUseBlocks(); - for (unsigned i = 0; i != UseBlocks.size(); ++i) { - const SplitAnalysis::BlockInfo &BI = UseBlocks[i]; - if (Blocks.count(BI.MBB)) - splitSingleBlock(BI); + +void SplitEditor::splitRegInBlock(const SplitAnalysis::BlockInfo &BI, + unsigned IntvIn, SlotIndex LeaveBefore) { + SlotIndex Start, Stop; + std::tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB); + + DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " [" << Start << ';' << Stop + << "), uses " << BI.FirstInstr << '-' << BI.LastInstr + << ", reg-in " << IntvIn << ", leave before " << LeaveBefore + << (BI.LiveOut ? ", stack-out" : ", killed in block")); + + assert(IntvIn && "Must have register in"); + assert(BI.LiveIn && "Must be live-in"); + assert((!LeaveBefore || LeaveBefore > Start) && "Bad interference"); + + if (!BI.LiveOut && (!LeaveBefore || LeaveBefore >= BI.LastInstr)) { + DEBUG(dbgs() << " before interference.\n"); + // + // <<< Interference after kill. + // |---o---x | Killed in block. + // ========= Use IntvIn everywhere. + // + selectIntv(IntvIn); + useIntv(Start, BI.LastInstr); + return; } - finish(); + + SlotIndex LSP = SA.getLastSplitPoint(BI.MBB->getNumber()); + + if (!LeaveBefore || LeaveBefore > BI.LastInstr.getBoundaryIndex()) { + // + // <<< Possible interference after last use. + // |---o---o---| Live-out on stack. + // =========____ Leave IntvIn after last use. + // + // < Interference after last use. + // |---o---o--o| Live-out on stack, late last use. + // ============ Copy to stack after LSP, overlap IntvIn. + // \_____ Stack interval is live-out. + // + if (BI.LastInstr < LSP) { + DEBUG(dbgs() << ", spill after last use before interference.\n"); + selectIntv(IntvIn); + SlotIndex Idx = leaveIntvAfter(BI.LastInstr); + useIntv(Start, Idx); + assert((!LeaveBefore || Idx <= LeaveBefore) && "Interference"); + } else { + DEBUG(dbgs() << ", spill before last split point.\n"); + selectIntv(IntvIn); + SlotIndex Idx = leaveIntvBefore(LSP); + overlapIntv(Idx, BI.LastInstr); + useIntv(Start, Idx); + assert((!LeaveBefore || Idx <= LeaveBefore) && "Interference"); + } + return; + } + + // The interference is overlapping somewhere we wanted to use IntvIn. That + // means we need to create a local interval that can be allocated a + // different register. + unsigned LocalIntv = openIntv(); + (void)LocalIntv; + DEBUG(dbgs() << ", creating local interval " << LocalIntv << ".\n"); + + if (!BI.LiveOut || BI.LastInstr < LSP) { + // + // <<<<<<< Interference overlapping uses. + // |---o---o---| Live-out on stack. + // =====----____ Leave IntvIn before interference, then spill. + // + SlotIndex To = leaveIntvAfter(BI.LastInstr); + SlotIndex From = enterIntvBefore(LeaveBefore); + useIntv(From, To); + selectIntv(IntvIn); + useIntv(Start, From); + assert((!LeaveBefore || From <= LeaveBefore) && "Interference"); + return; + } + + // <<<<<<< Interference overlapping uses. + // |---o---o--o| Live-out on stack, late last use. + // =====------- Copy to stack before LSP, overlap LocalIntv. + // \_____ Stack interval is live-out. + // + SlotIndex To = leaveIntvBefore(LSP); + overlapIntv(To, BI.LastInstr); + SlotIndex From = enterIntvBefore(std::min(To, LeaveBefore)); + useIntv(From, To); + selectIntv(IntvIn); + useIntv(Start, From); + assert((!LeaveBefore || From <= LeaveBefore) && "Interference"); +} + +void SplitEditor::splitRegOutBlock(const SplitAnalysis::BlockInfo &BI, + unsigned IntvOut, SlotIndex EnterAfter) { + SlotIndex Start, Stop; + std::tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB); + + DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " [" << Start << ';' << Stop + << "), uses " << BI.FirstInstr << '-' << BI.LastInstr + << ", reg-out " << IntvOut << ", enter after " << EnterAfter + << (BI.LiveIn ? ", stack-in" : ", defined in block")); + + SlotIndex LSP = SA.getLastSplitPoint(BI.MBB->getNumber()); + + assert(IntvOut && "Must have register out"); + assert(BI.LiveOut && "Must be live-out"); + assert((!EnterAfter || EnterAfter < LSP) && "Bad interference"); + + if (!BI.LiveIn && (!EnterAfter || EnterAfter <= BI.FirstInstr)) { + DEBUG(dbgs() << " after interference.\n"); + // + // >>>> Interference before def. + // | o---o---| Defined in block. + // ========= Use IntvOut everywhere. + // + selectIntv(IntvOut); + useIntv(BI.FirstInstr, Stop); + return; + } + + if (!EnterAfter || EnterAfter < BI.FirstInstr.getBaseIndex()) { + DEBUG(dbgs() << ", reload after interference.\n"); + // + // >>>> Interference before def. + // |---o---o---| Live-through, stack-in. + // ____========= Enter IntvOut before first use. + // + selectIntv(IntvOut); + SlotIndex Idx = enterIntvBefore(std::min(LSP, BI.FirstInstr)); + useIntv(Idx, Stop); + assert((!EnterAfter || Idx >= EnterAfter) && "Interference"); + return; + } + + // The interference is overlapping somewhere we wanted to use IntvOut. That + // means we need to create a local interval that can be allocated a + // different register. + DEBUG(dbgs() << ", interference overlaps uses.\n"); + // + // >>>>>>> Interference overlapping uses. + // |---o---o---| Live-through, stack-in. + // ____---====== Create local interval for interference range. + // + selectIntv(IntvOut); + SlotIndex Idx = enterIntvAfter(EnterAfter); + useIntv(Idx, Stop); + assert((!EnterAfter || Idx >= EnterAfter) && "Interference"); + + openIntv(); + SlotIndex From = enterIntvBefore(std::min(Idx, BI.FirstInstr)); + useIntv(From, Idx); }