X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FMachineScheduler.cpp;h=23847d6a75f5fd8d36fa9b1ba650635888ce739b;hb=b1a3b17e7896f8f5a3fa840b0caa0edfa7eae877;hp=ffab5f4e66d3fb96d080fa63da6ea0764d7d9308;hpb=4c60b8a78d811a5b16ae45f6957933fb479bab58;p=oota-llvm.git diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp index ffab5f4e66d..23847d6a75f 100644 --- a/lib/CodeGen/MachineScheduler.cpp +++ b/lib/CodeGen/MachineScheduler.cpp @@ -12,10 +12,7 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "misched" - #include "llvm/CodeGen/MachineScheduler.h" -#include "llvm/ADT/OwningPtr.h" #include "llvm/ADT/PriorityQueue.h" #include "llvm/Analysis/AliasAnalysis.h" #include "llvm/CodeGen/LiveIntervalAnalysis.h" @@ -36,6 +33,8 @@ using namespace llvm; +#define DEBUG_TYPE "misched" + namespace llvm { cl::opt ForceTopDown("misched-topdown", cl::Hidden, cl::desc("Force top-down list scheduling")); @@ -49,12 +48,20 @@ static cl::opt ViewMISchedDAGs("view-misched-dags", cl::Hidden, static cl::opt MISchedCutoff("misched-cutoff", cl::Hidden, cl::desc("Stop scheduling after N instructions"), cl::init(~0U)); + +static cl::opt SchedOnlyFunc("misched-only-func", cl::Hidden, + cl::desc("Only schedule this function")); +static cl::opt SchedOnlyBlock("misched-only-block", cl::Hidden, + cl::desc("Only schedule this MBB#")); #else static bool ViewMISchedDAGs = false; #endif // NDEBUG +static cl::opt EnableRegPressure("misched-regpressure", cl::Hidden, + cl::desc("Enable register pressure scheduling."), cl::init(true)); + static cl::opt EnableCyclicPath("misched-cyclicpath", cl::Hidden, - cl::desc("Enable cyclic critical path analysis."), cl::init(false)); + cl::desc("Enable cyclic critical path analysis."), cl::init(true)); static cl::opt EnableLoadCluster("misched-cluster", cl::Hidden, cl::desc("Enable load clustering."), cl::init(true)); @@ -69,12 +76,16 @@ static cl::opt VerifyScheduling("verify-misched", cl::Hidden, // DAG subtrees must have at least this many nodes. static const unsigned MinSubtreeSize = 8; +// Pin the vtables to this file. +void MachineSchedStrategy::anchor() {} +void ScheduleDAGMutation::anchor() {} + //===----------------------------------------------------------------------===// // Machine Instruction Scheduling Pass and Registry //===----------------------------------------------------------------------===// MachineSchedContext::MachineSchedContext(): - MF(0), MLI(0), MDT(0), PassConfig(0), AA(0), LIS(0) { + MF(nullptr), MLI(nullptr), MDT(nullptr), PassConfig(nullptr), AA(nullptr), LIS(nullptr) { RegClassInfo = new RegisterClassInfo(); } @@ -83,21 +94,46 @@ MachineSchedContext::~MachineSchedContext() { } namespace { +/// Base class for a machine scheduler class that can run at any point. +class MachineSchedulerBase : public MachineSchedContext, + public MachineFunctionPass { +public: + MachineSchedulerBase(char &ID): MachineFunctionPass(ID) {} + + void print(raw_ostream &O, const Module* = nullptr) const override; + +protected: + void scheduleRegions(ScheduleDAGInstrs &Scheduler); +}; + /// MachineScheduler runs after coalescing and before register allocation. -class MachineScheduler : public MachineSchedContext, - public MachineFunctionPass { +class MachineScheduler : public MachineSchedulerBase { public: MachineScheduler(); - virtual void getAnalysisUsage(AnalysisUsage &AU) const; + void getAnalysisUsage(AnalysisUsage &AU) const override; + + bool runOnMachineFunction(MachineFunction&) override; + + static char ID; // Class identification, replacement for typeinfo + +protected: + ScheduleDAGInstrs *createMachineScheduler(); +}; - virtual void releaseMemory() {} +/// PostMachineScheduler runs after shortly before code emission. +class PostMachineScheduler : public MachineSchedulerBase { +public: + PostMachineScheduler(); - virtual bool runOnMachineFunction(MachineFunction&); + void getAnalysisUsage(AnalysisUsage &AU) const override; - virtual void print(raw_ostream &O, const Module* = 0) const; + bool runOnMachineFunction(MachineFunction&) override; static char ID; // Class identification, replacement for typeinfo + +protected: + ScheduleDAGInstrs *createPostMachineScheduler(); }; } // namespace @@ -114,7 +150,7 @@ INITIALIZE_PASS_END(MachineScheduler, "misched", "Machine Instruction Scheduler", false, false) MachineScheduler::MachineScheduler() -: MachineFunctionPass(ID) { +: MachineSchedulerBase(ID) { initializeMachineSchedulerPass(*PassRegistry::getPassRegistry()); } @@ -131,12 +167,32 @@ void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const { MachineFunctionPass::getAnalysisUsage(AU); } +char PostMachineScheduler::ID = 0; + +char &llvm::PostMachineSchedulerID = PostMachineScheduler::ID; + +INITIALIZE_PASS(PostMachineScheduler, "postmisched", + "PostRA Machine Instruction Scheduler", false, false) + +PostMachineScheduler::PostMachineScheduler() +: MachineSchedulerBase(ID) { + initializePostMachineSchedulerPass(*PassRegistry::getPassRegistry()); +} + +void PostMachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesCFG(); + AU.addRequiredID(MachineDominatorsID); + AU.addRequired(); + AU.addRequired(); + MachineFunctionPass::getAnalysisUsage(AU); +} + MachinePassRegistry MachineSchedRegistry::Registry; /// A dummy default scheduler factory indicates whether the scheduler /// is overridden on the command line. static ScheduleDAGInstrs *useDefaultMachineSched(MachineSchedContext *C) { - return 0; + return nullptr; } /// MachineSchedOpt allows command line selection of the scheduler. @@ -152,12 +208,13 @@ DefaultSchedRegistry("default", "Use the target's default scheduler choice.", /// Forward declare the standard machine scheduler. This will be used as the /// default scheduler if the target does not set a default. -static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C); - +static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C); +static ScheduleDAGInstrs *createGenericSchedPostRA(MachineSchedContext *C); /// Decrement this iterator until reaching the top or a non-debug instr. -static MachineBasicBlock::iterator -priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) { +static MachineBasicBlock::const_iterator +priorNonDebug(MachineBasicBlock::const_iterator I, + MachineBasicBlock::const_iterator Beg) { assert(I != Beg && "reached the top of the region, cannot decrement"); while (--I != Beg) { if (!I->isDebugValue()) @@ -166,10 +223,19 @@ priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) { return I; } +/// Non-const version. +static MachineBasicBlock::iterator +priorNonDebug(MachineBasicBlock::iterator I, + MachineBasicBlock::const_iterator Beg) { + return const_cast( + &*priorNonDebug(MachineBasicBlock::const_iterator(I), Beg)); +} + /// If this iterator is a debug value, increment until reaching the End or a /// non-debug instruction. -static MachineBasicBlock::iterator -nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) { +static MachineBasicBlock::const_iterator +nextIfDebug(MachineBasicBlock::const_iterator I, + MachineBasicBlock::const_iterator End) { for(; I != End; ++I) { if (!I->isDebugValue()) break; @@ -177,6 +243,47 @@ nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) { return I; } +/// Non-const version. +static MachineBasicBlock::iterator +nextIfDebug(MachineBasicBlock::iterator I, + MachineBasicBlock::const_iterator End) { + // Cast the return value to nonconst MachineInstr, then cast to an + // instr_iterator, which does not check for null, finally return a + // bundle_iterator. + return MachineBasicBlock::instr_iterator( + const_cast( + &*nextIfDebug(MachineBasicBlock::const_iterator(I), End))); +} + +/// Instantiate a ScheduleDAGInstrs that will be owned by the caller. +ScheduleDAGInstrs *MachineScheduler::createMachineScheduler() { + // Select the scheduler, or set the default. + MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt; + if (Ctor != useDefaultMachineSched) + return Ctor(this); + + // Get the default scheduler set by the target for this function. + ScheduleDAGInstrs *Scheduler = PassConfig->createMachineScheduler(this); + if (Scheduler) + return Scheduler; + + // Default to GenericScheduler. + return createGenericSchedLive(this); +} + +/// Instantiate a ScheduleDAGInstrs for PostRA scheduling that will be owned by +/// the caller. We don't have a command line option to override the postRA +/// scheduler. The Target must configure it. +ScheduleDAGInstrs *PostMachineScheduler::createPostMachineScheduler() { + // Get the postRA scheduler set by the target for this function. + ScheduleDAGInstrs *Scheduler = PassConfig->createPostMachineScheduler(this); + if (Scheduler) + return Scheduler; + + // Default to GenericScheduler. + return createGenericSchedPostRA(this); +} + /// Top-level MachineScheduler pass driver. /// /// Visit blocks in function order. Divide each block into scheduling regions @@ -204,7 +311,6 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { AA = &getAnalysis(); LIS = &getAnalysis(); - const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); if (VerifyScheduling) { DEBUG(LIS->dump()); @@ -212,18 +318,62 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { } RegClassInfo->runOnMachineFunction(*MF); - // Select the scheduler, or set the default. - MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt; - if (Ctor == useDefaultMachineSched) { - // Get the default scheduler set by the target. - Ctor = MachineSchedRegistry::getDefault(); - if (!Ctor) { - Ctor = createConvergingSched; - MachineSchedRegistry::setDefault(Ctor); - } - } - // Instantiate the selected scheduler. - OwningPtr Scheduler(Ctor(this)); + // Instantiate the selected scheduler for this target, function, and + // optimization level. + std::unique_ptr Scheduler(createMachineScheduler()); + scheduleRegions(*Scheduler); + + DEBUG(LIS->dump()); + if (VerifyScheduling) + MF->verify(this, "After machine scheduling."); + return true; +} + +bool PostMachineScheduler::runOnMachineFunction(MachineFunction &mf) { + if (skipOptnoneFunction(*mf.getFunction())) + return false; + + DEBUG(dbgs() << "Before post-MI-sched:\n"; mf.print(dbgs())); + + // Initialize the context of the pass. + MF = &mf; + PassConfig = &getAnalysis(); + + if (VerifyScheduling) + MF->verify(this, "Before post machine scheduling."); + + // Instantiate the selected scheduler for this target, function, and + // optimization level. + std::unique_ptr Scheduler(createPostMachineScheduler()); + scheduleRegions(*Scheduler); + + if (VerifyScheduling) + MF->verify(this, "After post machine scheduling."); + return true; +} + +/// Return true of the given instruction should not be included in a scheduling +/// region. +/// +/// MachineScheduler does not currently support scheduling across calls. To +/// handle calls, the DAG builder needs to be modified to create register +/// anti/output dependencies on the registers clobbered by the call's regmask +/// operand. In PreRA scheduling, the stack pointer adjustment already prevents +/// scheduling across calls. In PostRA scheduling, we need the isCall to enforce +/// the boundary, but there would be no benefit to postRA scheduling across +/// calls this late anyway. +static bool isSchedBoundary(MachineBasicBlock::iterator MI, + MachineBasicBlock *MBB, + MachineFunction *MF, + const TargetInstrInfo *TII, + bool IsPostRA) { + return MI->isCall() || TII->isSchedulingBoundary(MI, MBB, *MF); +} + +/// Main driver for both MachineScheduler and PostMachineScheduler. +void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler) { + const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); + bool IsPostRA = Scheduler.isPostRA(); // Visit all machine basic blocks. // @@ -232,7 +382,15 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end(); MBB != MBBEnd; ++MBB) { - Scheduler->startBlock(MBB); + Scheduler.startBlock(MBB); + +#ifndef NDEBUG + if (SchedOnlyFunc.getNumOccurrences() && SchedOnlyFunc != MF->getName()) + continue; + if (SchedOnlyBlock.getNumOccurrences() + && (int)SchedOnlyBlock != MBB->getNumber()) + continue; +#endif // Break the block into scheduling regions [I, RegionEnd), and schedule each // region as soon as it is discovered. RegionEnd points the scheduling @@ -244,13 +402,16 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { // The Scheduler may insert instructions during either schedule() or // exitRegion(), even for empty regions. So the local iterators 'I' and // 'RegionEnd' are invalid across these calls. - unsigned RemainingInstrs = MBB->size(); + // + // MBB::size() uses instr_iterator to count. Here we need a bundle to count + // as a single instruction. + unsigned RemainingInstrs = std::distance(MBB->begin(), MBB->end()); for(MachineBasicBlock::iterator RegionEnd = MBB->end(); - RegionEnd != MBB->begin(); RegionEnd = Scheduler->begin()) { + RegionEnd != MBB->begin(); RegionEnd = Scheduler.begin()) { // Avoid decrementing RegionEnd for blocks with no terminator. - if (RegionEnd != MBB->end() - || TII->isSchedulingBoundary(llvm::prior(RegionEnd), MBB, *MF)) { + if (RegionEnd != MBB->end() || + isSchedBoundary(std::prev(RegionEnd), MBB, MF, TII, IsPostRA)) { --RegionEnd; // Count the boundary instruction. --RemainingInstrs; @@ -261,21 +422,22 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { unsigned NumRegionInstrs = 0; MachineBasicBlock::iterator I = RegionEnd; for(;I != MBB->begin(); --I, --RemainingInstrs, ++NumRegionInstrs) { - if (TII->isSchedulingBoundary(llvm::prior(I), MBB, *MF)) + if (isSchedBoundary(std::prev(I), MBB, MF, TII, IsPostRA)) break; } // Notify the scheduler of the region, even if we may skip scheduling // it. Perhaps it still needs to be bundled. - Scheduler->enterRegion(MBB, I, RegionEnd, NumRegionInstrs); + Scheduler.enterRegion(MBB, I, RegionEnd, NumRegionInstrs); // Skip empty scheduling regions (0 or 1 schedulable instructions). - if (I == RegionEnd || I == llvm::prior(RegionEnd)) { + if (I == RegionEnd || I == std::prev(RegionEnd)) { // Close the current region. Bundle the terminator if needed. // This invalidates 'RegionEnd' and 'I'. - Scheduler->exitRegion(); + Scheduler.exitRegion(); continue; } - DEBUG(dbgs() << "********** MI Scheduling **********\n"); + DEBUG(dbgs() << "********** " << ((Scheduler.isPostRA()) ? "PostRA " : "") + << "MI Scheduling **********\n"); DEBUG(dbgs() << MF->getName() << ":BB#" << MBB->getNumber() << " " << MBB->getName() << "\n From: " << *I << " To: "; @@ -286,26 +448,27 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { // Schedule a region: possibly reorder instructions. // This invalidates 'RegionEnd' and 'I'. - Scheduler->schedule(); + Scheduler.schedule(); // Close the current region. - Scheduler->exitRegion(); + Scheduler.exitRegion(); // Scheduling has invalidated the current iterator 'I'. Ask the // scheduler for the top of it's scheduled region. - RegionEnd = Scheduler->begin(); + RegionEnd = Scheduler.begin(); } assert(RemainingInstrs == 0 && "Instruction count mismatch!"); - Scheduler->finishBlock(); + Scheduler.finishBlock(); + if (Scheduler.isPostRA()) { + // FIXME: Ideally, no further passes should rely on kill flags. However, + // thumb2 size reduction is currently an exception. + Scheduler.fixupKills(MBB); + } } - Scheduler->finalizeSchedule(); - DEBUG(LIS->dump()); - if (VerifyScheduling) - MF->verify(this, "After machine scheduling."); - return true; + Scheduler.finalizeSchedule(); } -void MachineScheduler::print(raw_ostream &O, const Module* m) const { +void MachineSchedulerBase::print(raw_ostream &O, const Module* m) const { // unimplemented } @@ -319,14 +482,13 @@ void ReadyQueue::dump() { #endif //===----------------------------------------------------------------------===// -// ScheduleDAGMI - Base class for MachineInstr scheduling with LiveIntervals -// preservation. -//===----------------------------------------------------------------------===// +// ScheduleDAGMI - Basic machine instruction scheduling. This is +// independent of PreRA/PostRA scheduling and involves no extra book-keeping for +// virtual registers. +// ===----------------------------------------------------------------------===/ +// Provide a vtable anchor. ScheduleDAGMI::~ScheduleDAGMI() { - delete DFSResult; - DeleteContainerPointers(Mutations); - delete SchedImpl; } bool ScheduleDAGMI::canAddEdge(SUnit *SuccSU, SUnit *PredSU) { @@ -364,7 +526,7 @@ void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) { dbgs() << "*** Scheduling failed! ***\n"; SuccSU->dump(this); dbgs() << " has been released too many times!\n"; - llvm_unreachable(0); + llvm_unreachable(nullptr); } #endif --SuccSU->NumPredsLeft; @@ -398,7 +560,7 @@ void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) { dbgs() << "*** Scheduling failed! ***\n"; PredSU->dump(this); dbgs() << " has been released too many times!\n"; - llvm_unreachable(0); + llvm_unreachable(nullptr); } #endif --PredSU->NumSuccsLeft; @@ -414,10 +576,24 @@ void ScheduleDAGMI::releasePredecessors(SUnit *SU) { } } +/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after +/// crossing a scheduling boundary. [begin, end) includes all instructions in +/// the region, including the boundary itself and single-instruction regions +/// that don't get scheduled. +void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb, + MachineBasicBlock::iterator begin, + MachineBasicBlock::iterator end, + unsigned regioninstrs) +{ + ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs); + + SchedImpl->initPolicy(begin, end, regioninstrs); +} + /// This is normally called from the main scheduler loop but may also be invoked /// by the scheduling strategy to perform additional code motion. -void ScheduleDAGMI::moveInstruction(MachineInstr *MI, - MachineBasicBlock::iterator InsertPos) { +void ScheduleDAGMI::moveInstruction( + MachineInstr *MI, MachineBasicBlock::iterator InsertPos) { // Advance RegionBegin if the first instruction moves down. if (&*RegionBegin == MI) ++RegionBegin; @@ -426,7 +602,8 @@ void ScheduleDAGMI::moveInstruction(MachineInstr *MI, BB->splice(InsertPos, BB, MI); // Update LiveIntervals - LIS->handleMove(MI, /*UpdateFlags=*/true); + if (LIS) + LIS->handleMove(MI, /*UpdateFlags=*/true); // Recede RegionBegin if an instruction moves above the first. if (RegionBegin == InsertPos) @@ -444,109 +621,13 @@ bool ScheduleDAGMI::checkSchedLimit() { return true; } -/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after -/// crossing a scheduling boundary. [begin, end) includes all instructions in -/// the region, including the boundary itself and single-instruction regions -/// that don't get scheduled. -void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb, - MachineBasicBlock::iterator begin, - MachineBasicBlock::iterator end, - unsigned regioninstrs) -{ - ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs); - - // For convenience remember the end of the liveness region. - LiveRegionEnd = - (RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd); -} - -// Setup the register pressure trackers for the top scheduled top and bottom -// scheduled regions. -void ScheduleDAGMI::initRegPressure() { - TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin); - BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd); - - // Close the RPTracker to finalize live ins. - RPTracker.closeRegion(); - - DEBUG(RPTracker.dump()); - - // Initialize the live ins and live outs. - TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs); - BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs); - - // Close one end of the tracker so we can call - // getMaxUpward/DownwardPressureDelta before advancing across any - // instructions. This converts currently live regs into live ins/outs. - TopRPTracker.closeTop(); - BotRPTracker.closeBottom(); - - BotRPTracker.initLiveThru(RPTracker); - if (!BotRPTracker.getLiveThru().empty()) { - TopRPTracker.initLiveThru(BotRPTracker.getLiveThru()); - DEBUG(dbgs() << "Live Thru: "; - dumpRegSetPressure(BotRPTracker.getLiveThru(), TRI)); - }; - - // Account for liveness generated by the region boundary. - if (LiveRegionEnd != RegionEnd) - BotRPTracker.recede(); - - assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom"); - - // Cache the list of excess pressure sets in this region. This will also track - // the max pressure in the scheduled code for these sets. - RegionCriticalPSets.clear(); - const std::vector &RegionPressure = - RPTracker.getPressure().MaxSetPressure; - for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) { - unsigned Limit = RegClassInfo->getRegPressureSetLimit(i); - if (RegionPressure[i] > Limit) { - DEBUG(dbgs() << TRI->getRegPressureSetName(i) - << " Limit " << Limit - << " Actual " << RegionPressure[i] << "\n"); - RegionCriticalPSets.push_back(PressureChange(i)); - } - } - DEBUG(dbgs() << "Excess PSets: "; - for (unsigned i = 0, e = RegionCriticalPSets.size(); i != e; ++i) - dbgs() << TRI->getRegPressureSetName( - RegionCriticalPSets[i].getPSet()) << " "; - dbgs() << "\n"); -} - -// FIXME: When the pressure tracker deals in pressure differences then we won't -// iterate over all RegionCriticalPSets[i]. -void ScheduleDAGMI:: -updateScheduledPressure(const std::vector &NewMaxPressure) { - for (unsigned i = 0, e = RegionCriticalPSets.size(); i < e; ++i) { - unsigned ID = RegionCriticalPSets[i].getPSet(); - if ((int)NewMaxPressure[ID] > RegionCriticalPSets[i].getUnitInc() - && NewMaxPressure[ID] <= INT16_MAX) - RegionCriticalPSets[i].setUnitInc(NewMaxPressure[ID]); - } - DEBUG( - for (unsigned i = 0, e = NewMaxPressure.size(); i < e; ++i) { - unsigned Limit = RegClassInfo->getRegPressureSetLimit(i); - if (NewMaxPressure[i] > Limit ) { - dbgs() << " " << TRI->getRegPressureSetName(i) << ": " - << NewMaxPressure[i] << " > " << Limit << "\n"; - } - }); -} - -/// schedule - Called back from MachineScheduler::runOnMachineFunction -/// after setting up the current scheduling region. [RegionBegin, RegionEnd) -/// only includes instructions that have DAG nodes, not scheduling boundaries. -/// -/// This is a skeletal driver, with all the functionality pushed into helpers, -/// so that it can be easilly extended by experimental schedulers. Generally, -/// implementing MachineSchedStrategy should be sufficient to implement a new -/// scheduling algorithm. However, if a scheduler further subclasses -/// ScheduleDAGMI then it will want to override this virtual method in order to -/// update any specialized state. +/// Per-region scheduling driver, called back from +/// MachineScheduler::runOnMachineFunction. This is a simplified driver that +/// does not consider liveness or register pressure. It is useful for PostRA +/// scheduling and potentially other custom schedulers. void ScheduleDAGMI::schedule() { - buildDAGWithRegPressure(); + // Build the DAG. + buildSchedGraph(AA); Topo.InitDAGTopologicalSorting(); @@ -572,9 +653,31 @@ void ScheduleDAGMI::schedule() { if (!checkSchedLimit()) break; - scheduleMI(SU, IsTopNode); - + MachineInstr *MI = SU->getInstr(); + if (IsTopNode) { + assert(SU->isTopReady() && "node still has unscheduled dependencies"); + if (&*CurrentTop == MI) + CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom); + else + moveInstruction(MI, CurrentTop); + } + else { + assert(SU->isBottomReady() && "node still has unscheduled dependencies"); + MachineBasicBlock::iterator priorII = + priorNonDebug(CurrentBottom, CurrentTop); + if (&*priorII == MI) + CurrentBottom = priorII; + else { + if (&*CurrentTop == MI) + CurrentTop = nextIfDebug(++CurrentTop, priorII); + moveInstruction(MI, CurrentBottom); + CurrentBottom = MI; + } + } updateQueues(SU, IsTopNode); + + // Notify the scheduling strategy after updating the DAG. + SchedImpl->schedNode(SU, IsTopNode); } assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); @@ -588,23 +691,6 @@ void ScheduleDAGMI::schedule() { }); } -/// Build the DAG and setup three register pressure trackers. -void ScheduleDAGMI::buildDAGWithRegPressure() { - // Initialize the register pressure tracker used by buildSchedGraph. - RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd, - /*TrackUntiedDefs=*/true); - - // Account for liveness generate by the region boundary. - if (LiveRegionEnd != RegionEnd) - RPTracker.recede(); - - // Build the DAG, and compute current register pressure. - buildSchedGraph(AA, &RPTracker, &SUPressureDiffs); - - // Initialize top/bottom trackers after computing region pressure. - initRegPressure(); -} - /// Apply each ScheduleDAGMutation step in order. void ScheduleDAGMI::postprocessDAG() { for (unsigned i = 0, e = Mutations.size(); i < e; ++i) { @@ -612,18 +698,9 @@ void ScheduleDAGMI::postprocessDAG() { } } -void ScheduleDAGMI::computeDFSResult() { - if (!DFSResult) - DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize); - DFSResult->clear(); - ScheduledTrees.clear(); - DFSResult->resize(SUnits.size()); - DFSResult->compute(SUnits); - ScheduledTrees.resize(DFSResult->getNumSubtrees()); -} - -void ScheduleDAGMI::findRootsAndBiasEdges(SmallVectorImpl &TopRoots, - SmallVectorImpl &BotRoots) { +void ScheduleDAGMI:: +findRootsAndBiasEdges(SmallVectorImpl &TopRoots, + SmallVectorImpl &BotRoots) { for (std::vector::iterator I = SUnits.begin(), E = SUnits.end(); I != E; ++I) { SUnit *SU = &(*I); @@ -642,95 +719,11 @@ void ScheduleDAGMI::findRootsAndBiasEdges(SmallVectorImpl &TopRoots, ExitSU.biasCriticalPath(); } -/// Compute the max cyclic critical path through the DAG. The scheduling DAG -/// only provides the critical path for single block loops. To handle loops that -/// span blocks, we could use the vreg path latencies provided by -/// MachineTraceMetrics instead. However, MachineTraceMetrics is not currently -/// available for use in the scheduler. -/// -/// The cyclic path estimation identifies a def-use pair that crosses the back -/// edge and considers the depth and height of the nodes. For example, consider -/// the following instruction sequence where each instruction has unit latency -/// and defines an epomymous virtual register: -/// -/// a->b(a,c)->c(b)->d(c)->exit -/// -/// The cyclic critical path is a two cycles: b->c->b -/// The acyclic critical path is four cycles: a->b->c->d->exit -/// LiveOutHeight = height(c) = len(c->d->exit) = 2 -/// LiveOutDepth = depth(c) + 1 = len(a->b->c) + 1 = 3 -/// LiveInHeight = height(b) + 1 = len(b->c->d->exit) + 1 = 4 -/// LiveInDepth = depth(b) = len(a->b) = 1 -/// -/// LiveOutDepth - LiveInDepth = 3 - 1 = 2 -/// LiveInHeight - LiveOutHeight = 4 - 2 = 2 -/// CyclicCriticalPath = min(2, 2) = 2 -unsigned ScheduleDAGMI::computeCyclicCriticalPath() { - // This only applies to single block loop. - if (!BB->isSuccessor(BB)) - return 0; - - unsigned MaxCyclicLatency = 0; - // Visit each live out vreg def to find def/use pairs that cross iterations. - ArrayRef LiveOuts = RPTracker.getPressure().LiveOutRegs; - for (ArrayRef::iterator RI = LiveOuts.begin(), RE = LiveOuts.end(); - RI != RE; ++RI) { - unsigned Reg = *RI; - if (!TRI->isVirtualRegister(Reg)) - continue; - const LiveInterval &LI = LIS->getInterval(Reg); - const VNInfo *DefVNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB)); - if (!DefVNI) - continue; - - MachineInstr *DefMI = LIS->getInstructionFromIndex(DefVNI->def); - const SUnit *DefSU = getSUnit(DefMI); - if (!DefSU) - continue; - - unsigned LiveOutHeight = DefSU->getHeight(); - unsigned LiveOutDepth = DefSU->getDepth() + DefSU->Latency; - // Visit all local users of the vreg def. - for (VReg2UseMap::iterator - UI = VRegUses.find(Reg); UI != VRegUses.end(); ++UI) { - if (UI->SU == &ExitSU) - continue; - - // Only consider uses of the phi. - LiveRangeQuery LRQ(LI, LIS->getInstructionIndex(UI->SU->getInstr())); - if (!LRQ.valueIn()->isPHIDef()) - continue; - - // Assume that a path spanning two iterations is a cycle, which could - // overestimate in strange cases. This allows cyclic latency to be - // estimated as the minimum slack of the vreg's depth or height. - unsigned CyclicLatency = 0; - if (LiveOutDepth > UI->SU->getDepth()) - CyclicLatency = LiveOutDepth - UI->SU->getDepth(); - - unsigned LiveInHeight = UI->SU->getHeight() + DefSU->Latency; - if (LiveInHeight > LiveOutHeight) { - if (LiveInHeight - LiveOutHeight < CyclicLatency) - CyclicLatency = LiveInHeight - LiveOutHeight; - } - else - CyclicLatency = 0; - - DEBUG(dbgs() << "Cyclic Path: SU(" << DefSU->NodeNum << ") -> SU(" - << UI->SU->NodeNum << ") = " << CyclicLatency << "c\n"); - if (CyclicLatency > MaxCyclicLatency) - MaxCyclicLatency = CyclicLatency; - } - } - DEBUG(dbgs() << "Cyclic Critical Path: " << MaxCyclicLatency << "c\n"); - return MaxCyclicLatency; -} - -/// Identify DAG roots and setup scheduler queues. -void ScheduleDAGMI::initQueues(ArrayRef TopRoots, - ArrayRef BotRoots) { - NextClusterSucc = NULL; - NextClusterPred = NULL; +/// Identify DAG roots and setup scheduler queues. +void ScheduleDAGMI::initQueues(ArrayRef TopRoots, + ArrayRef BotRoots) { + NextClusterSucc = nullptr; + NextClusterPred = nullptr; // Release all DAG roots for scheduling, not including EntrySU/ExitSU. // @@ -753,53 +746,10 @@ void ScheduleDAGMI::initQueues(ArrayRef TopRoots, SchedImpl->registerRoots(); // Advance past initial DebugValues. - assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); CurrentTop = nextIfDebug(RegionBegin, RegionEnd); - TopRPTracker.setPos(CurrentTop); - CurrentBottom = RegionEnd; } -/// Move an instruction and update register pressure. -void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) { - // Move the instruction to its new location in the instruction stream. - MachineInstr *MI = SU->getInstr(); - - if (IsTopNode) { - assert(SU->isTopReady() && "node still has unscheduled dependencies"); - if (&*CurrentTop == MI) - CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom); - else { - moveInstruction(MI, CurrentTop); - TopRPTracker.setPos(MI); - } - - // Update top scheduled pressure. - TopRPTracker.advance(); - assert(TopRPTracker.getPos() == CurrentTop && "out of sync"); - updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure); - } - else { - assert(SU->isBottomReady() && "node still has unscheduled dependencies"); - MachineBasicBlock::iterator priorII = - priorNonDebug(CurrentBottom, CurrentTop); - if (&*priorII == MI) - CurrentBottom = priorII; - else { - if (&*CurrentTop == MI) { - CurrentTop = nextIfDebug(++CurrentTop, priorII); - TopRPTracker.setPos(CurrentTop); - } - moveInstruction(MI, CurrentBottom); - CurrentBottom = MI; - } - // Update bottom scheduled pressure. - BotRPTracker.recede(); - assert(BotRPTracker.getPos() == CurrentBottom && "out of sync"); - updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure); - } -} - /// Update scheduler queues after scheduling an instruction. void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) { // Release dependent instructions for scheduling. @@ -809,18 +759,6 @@ void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) { releasePredecessors(SU); SU->isScheduled = true; - - if (DFSResult) { - unsigned SubtreeID = DFSResult->getSubtreeID(SU); - if (!ScheduledTrees.test(SubtreeID)) { - ScheduledTrees.set(SubtreeID); - DFSResult->scheduleTree(SubtreeID); - SchedImpl->scheduleTree(SubtreeID); - } - } - - // Notify the scheduling strategy after updating the DAG. - SchedImpl->schedNode(SU, IsTopNode); } /// Reinsert any remaining debug_values, just like the PostRA scheduler. @@ -833,17 +771,17 @@ void ScheduleDAGMI::placeDebugValues() { for (std::vector >::iterator DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) { - std::pair P = *prior(DI); + std::pair P = *std::prev(DI); MachineInstr *DbgValue = P.first; MachineBasicBlock::iterator OrigPrevMI = P.second; if (&*RegionBegin == DbgValue) ++RegionBegin; BB->splice(++OrigPrevMI, BB, DbgValue); - if (OrigPrevMI == llvm::prior(RegionEnd)) + if (OrigPrevMI == std::prev(RegionEnd)) RegionEnd = DbgValue; } DbgValues.clear(); - FirstDbgValue = NULL; + FirstDbgValue = nullptr; } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) @@ -858,367 +796,1315 @@ void ScheduleDAGMI::dumpSchedule() const { #endif //===----------------------------------------------------------------------===// -// LoadClusterMutation - DAG post-processing to cluster loads. +// ScheduleDAGMILive - Base class for MachineInstr scheduling with LiveIntervals +// preservation. //===----------------------------------------------------------------------===// -namespace { -/// \brief Post-process the DAG to create cluster edges between neighboring -/// loads. -class LoadClusterMutation : public ScheduleDAGMutation { - struct LoadInfo { - SUnit *SU; - unsigned BaseReg; - unsigned Offset; - LoadInfo(SUnit *su, unsigned reg, unsigned ofs) - : SU(su), BaseReg(reg), Offset(ofs) {} - }; - static bool LoadInfoLess(const LoadClusterMutation::LoadInfo &LHS, - const LoadClusterMutation::LoadInfo &RHS); +ScheduleDAGMILive::~ScheduleDAGMILive() { + delete DFSResult; +} - const TargetInstrInfo *TII; - const TargetRegisterInfo *TRI; -public: - LoadClusterMutation(const TargetInstrInfo *tii, - const TargetRegisterInfo *tri) - : TII(tii), TRI(tri) {} +/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after +/// crossing a scheduling boundary. [begin, end) includes all instructions in +/// the region, including the boundary itself and single-instruction regions +/// that don't get scheduled. +void ScheduleDAGMILive::enterRegion(MachineBasicBlock *bb, + MachineBasicBlock::iterator begin, + MachineBasicBlock::iterator end, + unsigned regioninstrs) +{ + // ScheduleDAGMI initializes SchedImpl's per-region policy. + ScheduleDAGMI::enterRegion(bb, begin, end, regioninstrs); - virtual void apply(ScheduleDAGMI *DAG); -protected: - void clusterNeighboringLoads(ArrayRef Loads, ScheduleDAGMI *DAG); -}; -} // anonymous + // For convenience remember the end of the liveness region. + LiveRegionEnd = (RegionEnd == bb->end()) ? RegionEnd : std::next(RegionEnd); -bool LoadClusterMutation::LoadInfoLess( - const LoadClusterMutation::LoadInfo &LHS, - const LoadClusterMutation::LoadInfo &RHS) { - if (LHS.BaseReg != RHS.BaseReg) - return LHS.BaseReg < RHS.BaseReg; - return LHS.Offset < RHS.Offset; + SUPressureDiffs.clear(); + + ShouldTrackPressure = SchedImpl->shouldTrackPressure(); } -void LoadClusterMutation::clusterNeighboringLoads(ArrayRef Loads, - ScheduleDAGMI *DAG) { - SmallVector LoadRecords; - for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) { - SUnit *SU = Loads[Idx]; - unsigned BaseReg; - unsigned Offset; - if (TII->getLdStBaseRegImmOfs(SU->getInstr(), BaseReg, Offset, TRI)) - LoadRecords.push_back(LoadInfo(SU, BaseReg, Offset)); +// Setup the register pressure trackers for the top scheduled top and bottom +// scheduled regions. +void ScheduleDAGMILive::initRegPressure() { + TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin); + BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd); + + // Close the RPTracker to finalize live ins. + RPTracker.closeRegion(); + + DEBUG(RPTracker.dump()); + + // Initialize the live ins and live outs. + TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs); + BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs); + + // Close one end of the tracker so we can call + // getMaxUpward/DownwardPressureDelta before advancing across any + // instructions. This converts currently live regs into live ins/outs. + TopRPTracker.closeTop(); + BotRPTracker.closeBottom(); + + BotRPTracker.initLiveThru(RPTracker); + if (!BotRPTracker.getLiveThru().empty()) { + TopRPTracker.initLiveThru(BotRPTracker.getLiveThru()); + DEBUG(dbgs() << "Live Thru: "; + dumpRegSetPressure(BotRPTracker.getLiveThru(), TRI)); + }; + + // For each live out vreg reduce the pressure change associated with other + // uses of the same vreg below the live-out reaching def. + updatePressureDiffs(RPTracker.getPressure().LiveOutRegs); + + // Account for liveness generated by the region boundary. + if (LiveRegionEnd != RegionEnd) { + SmallVector LiveUses; + BotRPTracker.recede(&LiveUses); + updatePressureDiffs(LiveUses); } - if (LoadRecords.size() < 2) - return; - std::sort(LoadRecords.begin(), LoadRecords.end(), LoadInfoLess); - unsigned ClusterLength = 1; - for (unsigned Idx = 0, End = LoadRecords.size(); Idx < (End - 1); ++Idx) { - if (LoadRecords[Idx].BaseReg != LoadRecords[Idx+1].BaseReg) { - ClusterLength = 1; - continue; - } - SUnit *SUa = LoadRecords[Idx].SU; - SUnit *SUb = LoadRecords[Idx+1].SU; - if (TII->shouldClusterLoads(SUa->getInstr(), SUb->getInstr(), ClusterLength) - && DAG->addEdge(SUb, SDep(SUa, SDep::Cluster))) { + assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom"); - DEBUG(dbgs() << "Cluster loads SU(" << SUa->NodeNum << ") - SU(" - << SUb->NodeNum << ")\n"); - // Copy successor edges from SUa to SUb. Interleaving computation - // dependent on SUa can prevent load combining due to register reuse. - // Predecessor edges do not need to be copied from SUb to SUa since nearby - // loads should have effectively the same inputs. - for (SUnit::const_succ_iterator - SI = SUa->Succs.begin(), SE = SUa->Succs.end(); SI != SE; ++SI) { - if (SI->getSUnit() == SUb) - continue; - DEBUG(dbgs() << " Copy Succ SU(" << SI->getSUnit()->NodeNum << ")\n"); - DAG->addEdge(SI->getSUnit(), SDep(SUb, SDep::Artificial)); - } - ++ClusterLength; + // Cache the list of excess pressure sets in this region. This will also track + // the max pressure in the scheduled code for these sets. + RegionCriticalPSets.clear(); + const std::vector &RegionPressure = + RPTracker.getPressure().MaxSetPressure; + for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) { + unsigned Limit = RegClassInfo->getRegPressureSetLimit(i); + if (RegionPressure[i] > Limit) { + DEBUG(dbgs() << TRI->getRegPressureSetName(i) + << " Limit " << Limit + << " Actual " << RegionPressure[i] << "\n"); + RegionCriticalPSets.push_back(PressureChange(i)); } - else - ClusterLength = 1; } + DEBUG(dbgs() << "Excess PSets: "; + for (unsigned i = 0, e = RegionCriticalPSets.size(); i != e; ++i) + dbgs() << TRI->getRegPressureSetName( + RegionCriticalPSets[i].getPSet()) << " "; + dbgs() << "\n"); } -/// \brief Callback from DAG postProcessing to create cluster edges for loads. -void LoadClusterMutation::apply(ScheduleDAGMI *DAG) { - // Map DAG NodeNum to store chain ID. - DenseMap StoreChainIDs; - // Map each store chain to a set of dependent loads. - SmallVector, 32> StoreChainDependents; - for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) { - SUnit *SU = &DAG->SUnits[Idx]; - if (!SU->getInstr()->mayLoad()) +void ScheduleDAGMILive:: +updateScheduledPressure(const SUnit *SU, + const std::vector &NewMaxPressure) { + const PressureDiff &PDiff = getPressureDiff(SU); + unsigned CritIdx = 0, CritEnd = RegionCriticalPSets.size(); + for (PressureDiff::const_iterator I = PDiff.begin(), E = PDiff.end(); + I != E; ++I) { + if (!I->isValid()) + break; + unsigned ID = I->getPSet(); + while (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() < ID) + ++CritIdx; + if (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() == ID) { + if ((int)NewMaxPressure[ID] > RegionCriticalPSets[CritIdx].getUnitInc() + && NewMaxPressure[ID] <= INT16_MAX) + RegionCriticalPSets[CritIdx].setUnitInc(NewMaxPressure[ID]); + } + unsigned Limit = RegClassInfo->getRegPressureSetLimit(ID); + if (NewMaxPressure[ID] >= Limit - 2) { + DEBUG(dbgs() << " " << TRI->getRegPressureSetName(ID) << ": " + << NewMaxPressure[ID] << " > " << Limit << "(+ " + << BotRPTracker.getLiveThru()[ID] << " livethru)\n"); + } + } +} + +/// Update the PressureDiff array for liveness after scheduling this +/// instruction. +void ScheduleDAGMILive::updatePressureDiffs(ArrayRef LiveUses) { + for (unsigned LUIdx = 0, LUEnd = LiveUses.size(); LUIdx != LUEnd; ++LUIdx) { + /// FIXME: Currently assuming single-use physregs. + unsigned Reg = LiveUses[LUIdx]; + DEBUG(dbgs() << " LiveReg: " << PrintVRegOrUnit(Reg, TRI) << "\n"); + if (!TRI->isVirtualRegister(Reg)) continue; - unsigned ChainPredID = DAG->SUnits.size(); - for (SUnit::const_pred_iterator - PI = SU->Preds.begin(), PE = SU->Preds.end(); PI != PE; ++PI) { - if (PI->isCtrl()) { - ChainPredID = PI->getSUnit()->NodeNum; - break; + + // This may be called before CurrentBottom has been initialized. However, + // BotRPTracker must have a valid position. We want the value live into the + // instruction or live out of the block, so ask for the previous + // instruction's live-out. + const LiveInterval &LI = LIS->getInterval(Reg); + VNInfo *VNI; + MachineBasicBlock::const_iterator I = + nextIfDebug(BotRPTracker.getPos(), BB->end()); + if (I == BB->end()) + VNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB)); + else { + LiveQueryResult LRQ = LI.Query(LIS->getInstructionIndex(I)); + VNI = LRQ.valueIn(); + } + // RegisterPressureTracker guarantees that readsReg is true for LiveUses. + assert(VNI && "No live value at use."); + for (VReg2UseMap::iterator + UI = VRegUses.find(Reg); UI != VRegUses.end(); ++UI) { + SUnit *SU = UI->SU; + DEBUG(dbgs() << " UpdateRegP: SU(" << SU->NodeNum << ") " + << *SU->getInstr()); + // If this use comes before the reaching def, it cannot be a last use, so + // descrease its pressure change. + if (!SU->isScheduled && SU != &ExitSU) { + LiveQueryResult LRQ + = LI.Query(LIS->getInstructionIndex(SU->getInstr())); + if (LRQ.valueIn() == VNI) + getPressureDiff(SU).addPressureChange(Reg, true, &MRI); } } - // Check if this chain-like pred has been seen - // before. ChainPredID==MaxNodeID for loads at the top of the schedule. - unsigned NumChains = StoreChainDependents.size(); - std::pair::iterator, bool> Result = - StoreChainIDs.insert(std::make_pair(ChainPredID, NumChains)); - if (Result.second) - StoreChainDependents.resize(NumChains + 1); - StoreChainDependents[Result.first->second].push_back(SU); } - // Iterate over the store chains. - for (unsigned Idx = 0, End = StoreChainDependents.size(); Idx != End; ++Idx) - clusterNeighboringLoads(StoreChainDependents[Idx], DAG); } -//===----------------------------------------------------------------------===// -// MacroFusion - DAG post-processing to encourage fusion of macro ops. -//===----------------------------------------------------------------------===// - -namespace { -/// \brief Post-process the DAG to create cluster edges between instructions -/// that may be fused by the processor into a single operation. -class MacroFusion : public ScheduleDAGMutation { - const TargetInstrInfo *TII; -public: - MacroFusion(const TargetInstrInfo *tii): TII(tii) {} - - virtual void apply(ScheduleDAGMI *DAG); -}; -} // anonymous +/// schedule - Called back from MachineScheduler::runOnMachineFunction +/// after setting up the current scheduling region. [RegionBegin, RegionEnd) +/// only includes instructions that have DAG nodes, not scheduling boundaries. +/// +/// This is a skeletal driver, with all the functionality pushed into helpers, +/// so that it can be easilly extended by experimental schedulers. Generally, +/// implementing MachineSchedStrategy should be sufficient to implement a new +/// scheduling algorithm. However, if a scheduler further subclasses +/// ScheduleDAGMILive then it will want to override this virtual method in order +/// to update any specialized state. +void ScheduleDAGMILive::schedule() { + buildDAGWithRegPressure(); -/// \brief Callback from DAG postProcessing to create cluster edges to encourage -/// fused operations. -void MacroFusion::apply(ScheduleDAGMI *DAG) { - // For now, assume targets can only fuse with the branch. - MachineInstr *Branch = DAG->ExitSU.getInstr(); - if (!Branch) - return; + Topo.InitDAGTopologicalSorting(); - for (unsigned Idx = DAG->SUnits.size(); Idx > 0;) { - SUnit *SU = &DAG->SUnits[--Idx]; - if (!TII->shouldScheduleAdjacent(SU->getInstr(), Branch)) - continue; + postprocessDAG(); - // Create a single weak edge from SU to ExitSU. The only effect is to cause - // bottom-up scheduling to heavily prioritize the clustered SU. There is no - // need to copy predecessor edges from ExitSU to SU, since top-down - // scheduling cannot prioritize ExitSU anyway. To defer top-down scheduling - // of SU, we could create an artificial edge from the deepest root, but it - // hasn't been needed yet. - bool Success = DAG->addEdge(&DAG->ExitSU, SDep(SU, SDep::Cluster)); - (void)Success; - assert(Success && "No DAG nodes should be reachable from ExitSU"); + SmallVector TopRoots, BotRoots; + findRootsAndBiasEdges(TopRoots, BotRoots); - DEBUG(dbgs() << "Macro Fuse SU(" << SU->NodeNum << ")\n"); - break; - } -} + // Initialize the strategy before modifying the DAG. + // This may initialize a DFSResult to be used for queue priority. + SchedImpl->initialize(this); -//===----------------------------------------------------------------------===// -// CopyConstrain - DAG post-processing to encourage copy elimination. -//===----------------------------------------------------------------------===// + DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su) + SUnits[su].dumpAll(this)); + if (ViewMISchedDAGs) viewGraph(); -namespace { -/// \brief Post-process the DAG to create weak edges from all uses of a copy to -/// the one use that defines the copy's source vreg, most likely an induction -/// variable increment. -class CopyConstrain : public ScheduleDAGMutation { - // Transient state. - SlotIndex RegionBeginIdx; - // RegionEndIdx is the slot index of the last non-debug instruction in the - // scheduling region. So we may have RegionBeginIdx == RegionEndIdx. - SlotIndex RegionEndIdx; -public: - CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {} + // Initialize ready queues now that the DAG and priority data are finalized. + initQueues(TopRoots, BotRoots); - virtual void apply(ScheduleDAGMI *DAG); + if (ShouldTrackPressure) { + assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); + TopRPTracker.setPos(CurrentTop); + } -protected: - void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG); -}; -} // anonymous + bool IsTopNode = false; + while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) { + assert(!SU->isScheduled && "Node already scheduled"); + if (!checkSchedLimit()) + break; -/// constrainLocalCopy handles two possibilities: -/// 1) Local src: -/// I0: = dst -/// I1: src = ... -/// I2: = dst -/// I3: dst = src (copy) -/// (create pred->succ edges I0->I1, I2->I1) -/// -/// 2) Local copy: -/// I0: dst = src (copy) -/// I1: = dst -/// I2: src = ... -/// I3: = dst -/// (create pred->succ edges I1->I2, I3->I2) -/// -/// Although the MachineScheduler is currently constrained to single blocks, -/// this algorithm should handle extended blocks. An EBB is a set of -/// contiguously numbered blocks such that the previous block in the EBB is -/// always the single predecessor. -void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG) { - LiveIntervals *LIS = DAG->getLIS(); - MachineInstr *Copy = CopySU->getInstr(); + scheduleMI(SU, IsTopNode); - // Check for pure vreg copies. - unsigned SrcReg = Copy->getOperand(1).getReg(); - if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) - return; + updateQueues(SU, IsTopNode); - unsigned DstReg = Copy->getOperand(0).getReg(); - if (!TargetRegisterInfo::isVirtualRegister(DstReg)) - return; + if (DFSResult) { + unsigned SubtreeID = DFSResult->getSubtreeID(SU); + if (!ScheduledTrees.test(SubtreeID)) { + ScheduledTrees.set(SubtreeID); + DFSResult->scheduleTree(SubtreeID); + SchedImpl->scheduleTree(SubtreeID); + } + } - // Check if either the dest or source is local. If it's live across a back - // edge, it's not local. Note that if both vregs are live across the back - // edge, we cannot successfully contrain the copy without cyclic scheduling. - unsigned LocalReg = DstReg; - unsigned GlobalReg = SrcReg; - LiveInterval *LocalLI = &LIS->getInterval(LocalReg); - if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) { - LocalReg = SrcReg; - GlobalReg = DstReg; - LocalLI = &LIS->getInterval(LocalReg); - if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) - return; + // Notify the scheduling strategy after updating the DAG. + SchedImpl->schedNode(SU, IsTopNode); } - LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg); + assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); - // Find the global segment after the start of the local LI. - LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex()); - // If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a - // local live range. We could create edges from other global uses to the local - // start, but the coalescer should have already eliminated these cases, so - // don't bother dealing with it. - if (GlobalSegment == GlobalLI->end()) - return; + placeDebugValues(); - // If GlobalSegment is killed at the LocalLI->start, the call to find() - // returned the next global segment. But if GlobalSegment overlaps with - // LocalLI->start, then advance to the next segement. If a hole in GlobalLI - // exists in LocalLI's vicinity, GlobalSegment will be the end of the hole. - if (GlobalSegment->contains(LocalLI->beginIndex())) - ++GlobalSegment; + DEBUG({ + unsigned BBNum = begin()->getParent()->getNumber(); + dbgs() << "*** Final schedule for BB#" << BBNum << " ***\n"; + dumpSchedule(); + dbgs() << '\n'; + }); +} - if (GlobalSegment == GlobalLI->end()) +/// Build the DAG and setup three register pressure trackers. +void ScheduleDAGMILive::buildDAGWithRegPressure() { + if (!ShouldTrackPressure) { + RPTracker.reset(); + RegionCriticalPSets.clear(); + buildSchedGraph(AA); return; - - // Check if GlobalLI contains a hole in the vicinity of LocalLI. - if (GlobalSegment != GlobalLI->begin()) { - // Two address defs have no hole. - if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->end, - GlobalSegment->start)) { - return; - } - // If the prior global segment may be defined by the same two-address - // instruction that also defines LocalLI, then can't make a hole here. - if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->start, - LocalLI->beginIndex())) { - return; - } - // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise - // it would be a disconnected component in the live range. - assert(llvm::prior(GlobalSegment)->start < LocalLI->beginIndex() && - "Disconnected LRG within the scheduling region."); } - MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start); - if (!GlobalDef) - return; - SUnit *GlobalSU = DAG->getSUnit(GlobalDef); - if (!GlobalSU) - return; + // Initialize the register pressure tracker used by buildSchedGraph. + RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd, + /*TrackUntiedDefs=*/true); - // GlobalDef is the bottom of the GlobalLI hole. Open the hole by - // constraining the uses of the last local def to precede GlobalDef. - SmallVector LocalUses; - const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex()); - MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def); - SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef); - for (SUnit::const_succ_iterator - I = LastLocalSU->Succs.begin(), E = LastLocalSU->Succs.end(); - I != E; ++I) { - if (I->getKind() != SDep::Data || I->getReg() != LocalReg) - continue; - if (I->getSUnit() == GlobalSU) - continue; - if (!DAG->canAddEdge(GlobalSU, I->getSUnit())) - return; - LocalUses.push_back(I->getSUnit()); - } - // Open the top of the GlobalLI hole by constraining any earlier global uses - // to precede the start of LocalLI. - SmallVector GlobalUses; - MachineInstr *FirstLocalDef = - LIS->getInstructionFromIndex(LocalLI->beginIndex()); - SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef); - for (SUnit::const_pred_iterator - I = GlobalSU->Preds.begin(), E = GlobalSU->Preds.end(); I != E; ++I) { - if (I->getKind() != SDep::Anti || I->getReg() != GlobalReg) - continue; - if (I->getSUnit() == FirstLocalSU) - continue; - if (!DAG->canAddEdge(FirstLocalSU, I->getSUnit())) - return; - GlobalUses.push_back(I->getSUnit()); - } - DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n"); - // Add the weak edges. - for (SmallVectorImpl::const_iterator - I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) { - DEBUG(dbgs() << " Local use SU(" << (*I)->NodeNum << ") -> SU(" - << GlobalSU->NodeNum << ")\n"); - DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak)); - } - for (SmallVectorImpl::const_iterator - I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) { - DEBUG(dbgs() << " Global use SU(" << (*I)->NodeNum << ") -> SU(" - << FirstLocalSU->NodeNum << ")\n"); - DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak)); - } -} + // Account for liveness generate by the region boundary. + if (LiveRegionEnd != RegionEnd) + RPTracker.recede(); -/// \brief Callback from DAG postProcessing to create weak edges to encourage -/// copy elimination. -void CopyConstrain::apply(ScheduleDAGMI *DAG) { - MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end()); - if (FirstPos == DAG->end()) - return; - RegionBeginIdx = DAG->getLIS()->getInstructionIndex(&*FirstPos); - RegionEndIdx = DAG->getLIS()->getInstructionIndex( - &*priorNonDebug(DAG->end(), DAG->begin())); + // Build the DAG, and compute current register pressure. + buildSchedGraph(AA, &RPTracker, &SUPressureDiffs); - for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) { - SUnit *SU = &DAG->SUnits[Idx]; - if (!SU->getInstr()->isCopy()) - continue; + // Initialize top/bottom trackers after computing region pressure. + initRegPressure(); +} + +void ScheduleDAGMILive::computeDFSResult() { + if (!DFSResult) + DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize); + DFSResult->clear(); + ScheduledTrees.clear(); + DFSResult->resize(SUnits.size()); + DFSResult->compute(SUnits); + ScheduledTrees.resize(DFSResult->getNumSubtrees()); +} - constrainLocalCopy(SU, DAG); +/// Compute the max cyclic critical path through the DAG. The scheduling DAG +/// only provides the critical path for single block loops. To handle loops that +/// span blocks, we could use the vreg path latencies provided by +/// MachineTraceMetrics instead. However, MachineTraceMetrics is not currently +/// available for use in the scheduler. +/// +/// The cyclic path estimation identifies a def-use pair that crosses the back +/// edge and considers the depth and height of the nodes. For example, consider +/// the following instruction sequence where each instruction has unit latency +/// and defines an epomymous virtual register: +/// +/// a->b(a,c)->c(b)->d(c)->exit +/// +/// The cyclic critical path is a two cycles: b->c->b +/// The acyclic critical path is four cycles: a->b->c->d->exit +/// LiveOutHeight = height(c) = len(c->d->exit) = 2 +/// LiveOutDepth = depth(c) + 1 = len(a->b->c) + 1 = 3 +/// LiveInHeight = height(b) + 1 = len(b->c->d->exit) + 1 = 4 +/// LiveInDepth = depth(b) = len(a->b) = 1 +/// +/// LiveOutDepth - LiveInDepth = 3 - 1 = 2 +/// LiveInHeight - LiveOutHeight = 4 - 2 = 2 +/// CyclicCriticalPath = min(2, 2) = 2 +/// +/// This could be relevant to PostRA scheduling, but is currently implemented +/// assuming LiveIntervals. +unsigned ScheduleDAGMILive::computeCyclicCriticalPath() { + // This only applies to single block loop. + if (!BB->isSuccessor(BB)) + return 0; + + unsigned MaxCyclicLatency = 0; + // Visit each live out vreg def to find def/use pairs that cross iterations. + ArrayRef LiveOuts = RPTracker.getPressure().LiveOutRegs; + for (ArrayRef::iterator RI = LiveOuts.begin(), RE = LiveOuts.end(); + RI != RE; ++RI) { + unsigned Reg = *RI; + if (!TRI->isVirtualRegister(Reg)) + continue; + const LiveInterval &LI = LIS->getInterval(Reg); + const VNInfo *DefVNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB)); + if (!DefVNI) + continue; + + MachineInstr *DefMI = LIS->getInstructionFromIndex(DefVNI->def); + const SUnit *DefSU = getSUnit(DefMI); + if (!DefSU) + continue; + + unsigned LiveOutHeight = DefSU->getHeight(); + unsigned LiveOutDepth = DefSU->getDepth() + DefSU->Latency; + // Visit all local users of the vreg def. + for (VReg2UseMap::iterator + UI = VRegUses.find(Reg); UI != VRegUses.end(); ++UI) { + if (UI->SU == &ExitSU) + continue; + + // Only consider uses of the phi. + LiveQueryResult LRQ = + LI.Query(LIS->getInstructionIndex(UI->SU->getInstr())); + if (!LRQ.valueIn()->isPHIDef()) + continue; + + // Assume that a path spanning two iterations is a cycle, which could + // overestimate in strange cases. This allows cyclic latency to be + // estimated as the minimum slack of the vreg's depth or height. + unsigned CyclicLatency = 0; + if (LiveOutDepth > UI->SU->getDepth()) + CyclicLatency = LiveOutDepth - UI->SU->getDepth(); + + unsigned LiveInHeight = UI->SU->getHeight() + DefSU->Latency; + if (LiveInHeight > LiveOutHeight) { + if (LiveInHeight - LiveOutHeight < CyclicLatency) + CyclicLatency = LiveInHeight - LiveOutHeight; + } + else + CyclicLatency = 0; + + DEBUG(dbgs() << "Cyclic Path: SU(" << DefSU->NodeNum << ") -> SU(" + << UI->SU->NodeNum << ") = " << CyclicLatency << "c\n"); + if (CyclicLatency > MaxCyclicLatency) + MaxCyclicLatency = CyclicLatency; + } + } + DEBUG(dbgs() << "Cyclic Critical Path: " << MaxCyclicLatency << "c\n"); + return MaxCyclicLatency; +} + +/// Move an instruction and update register pressure. +void ScheduleDAGMILive::scheduleMI(SUnit *SU, bool IsTopNode) { + // Move the instruction to its new location in the instruction stream. + MachineInstr *MI = SU->getInstr(); + + if (IsTopNode) { + assert(SU->isTopReady() && "node still has unscheduled dependencies"); + if (&*CurrentTop == MI) + CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom); + else { + moveInstruction(MI, CurrentTop); + TopRPTracker.setPos(MI); + } + + if (ShouldTrackPressure) { + // Update top scheduled pressure. + TopRPTracker.advance(); + assert(TopRPTracker.getPos() == CurrentTop && "out of sync"); + updateScheduledPressure(SU, TopRPTracker.getPressure().MaxSetPressure); + } + } + else { + assert(SU->isBottomReady() && "node still has unscheduled dependencies"); + MachineBasicBlock::iterator priorII = + priorNonDebug(CurrentBottom, CurrentTop); + if (&*priorII == MI) + CurrentBottom = priorII; + else { + if (&*CurrentTop == MI) { + CurrentTop = nextIfDebug(++CurrentTop, priorII); + TopRPTracker.setPos(CurrentTop); + } + moveInstruction(MI, CurrentBottom); + CurrentBottom = MI; + } + if (ShouldTrackPressure) { + // Update bottom scheduled pressure. + SmallVector LiveUses; + BotRPTracker.recede(&LiveUses); + assert(BotRPTracker.getPos() == CurrentBottom && "out of sync"); + updateScheduledPressure(SU, BotRPTracker.getPressure().MaxSetPressure); + updatePressureDiffs(LiveUses); + } + } +} + +//===----------------------------------------------------------------------===// +// LoadClusterMutation - DAG post-processing to cluster loads. +//===----------------------------------------------------------------------===// + +namespace { +/// \brief Post-process the DAG to create cluster edges between neighboring +/// loads. +class LoadClusterMutation : public ScheduleDAGMutation { + struct LoadInfo { + SUnit *SU; + unsigned BaseReg; + unsigned Offset; + LoadInfo(SUnit *su, unsigned reg, unsigned ofs) + : SU(su), BaseReg(reg), Offset(ofs) {} + + bool operator<(const LoadInfo &RHS) const { + return std::tie(BaseReg, Offset) < std::tie(RHS.BaseReg, RHS.Offset); + } + }; + + const TargetInstrInfo *TII; + const TargetRegisterInfo *TRI; +public: + LoadClusterMutation(const TargetInstrInfo *tii, + const TargetRegisterInfo *tri) + : TII(tii), TRI(tri) {} + + void apply(ScheduleDAGMI *DAG) override; +protected: + void clusterNeighboringLoads(ArrayRef Loads, ScheduleDAGMI *DAG); +}; +} // anonymous + +void LoadClusterMutation::clusterNeighboringLoads(ArrayRef Loads, + ScheduleDAGMI *DAG) { + SmallVector LoadRecords; + for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) { + SUnit *SU = Loads[Idx]; + unsigned BaseReg; + unsigned Offset; + if (TII->getLdStBaseRegImmOfs(SU->getInstr(), BaseReg, Offset, TRI)) + LoadRecords.push_back(LoadInfo(SU, BaseReg, Offset)); + } + if (LoadRecords.size() < 2) + return; + std::sort(LoadRecords.begin(), LoadRecords.end()); + unsigned ClusterLength = 1; + for (unsigned Idx = 0, End = LoadRecords.size(); Idx < (End - 1); ++Idx) { + if (LoadRecords[Idx].BaseReg != LoadRecords[Idx+1].BaseReg) { + ClusterLength = 1; + continue; + } + + SUnit *SUa = LoadRecords[Idx].SU; + SUnit *SUb = LoadRecords[Idx+1].SU; + if (TII->shouldClusterLoads(SUa->getInstr(), SUb->getInstr(), ClusterLength) + && DAG->addEdge(SUb, SDep(SUa, SDep::Cluster))) { + + DEBUG(dbgs() << "Cluster loads SU(" << SUa->NodeNum << ") - SU(" + << SUb->NodeNum << ")\n"); + // Copy successor edges from SUa to SUb. Interleaving computation + // dependent on SUa can prevent load combining due to register reuse. + // Predecessor edges do not need to be copied from SUb to SUa since nearby + // loads should have effectively the same inputs. + for (SUnit::const_succ_iterator + SI = SUa->Succs.begin(), SE = SUa->Succs.end(); SI != SE; ++SI) { + if (SI->getSUnit() == SUb) + continue; + DEBUG(dbgs() << " Copy Succ SU(" << SI->getSUnit()->NodeNum << ")\n"); + DAG->addEdge(SI->getSUnit(), SDep(SUb, SDep::Artificial)); + } + ++ClusterLength; + } + else + ClusterLength = 1; + } +} + +/// \brief Callback from DAG postProcessing to create cluster edges for loads. +void LoadClusterMutation::apply(ScheduleDAGMI *DAG) { + // Map DAG NodeNum to store chain ID. + DenseMap StoreChainIDs; + // Map each store chain to a set of dependent loads. + SmallVector, 32> StoreChainDependents; + for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) { + SUnit *SU = &DAG->SUnits[Idx]; + if (!SU->getInstr()->mayLoad()) + continue; + unsigned ChainPredID = DAG->SUnits.size(); + for (SUnit::const_pred_iterator + PI = SU->Preds.begin(), PE = SU->Preds.end(); PI != PE; ++PI) { + if (PI->isCtrl()) { + ChainPredID = PI->getSUnit()->NodeNum; + break; + } + } + // Check if this chain-like pred has been seen + // before. ChainPredID==MaxNodeID for loads at the top of the schedule. + unsigned NumChains = StoreChainDependents.size(); + std::pair::iterator, bool> Result = + StoreChainIDs.insert(std::make_pair(ChainPredID, NumChains)); + if (Result.second) + StoreChainDependents.resize(NumChains + 1); + StoreChainDependents[Result.first->second].push_back(SU); + } + // Iterate over the store chains. + for (unsigned Idx = 0, End = StoreChainDependents.size(); Idx != End; ++Idx) + clusterNeighboringLoads(StoreChainDependents[Idx], DAG); +} + +//===----------------------------------------------------------------------===// +// MacroFusion - DAG post-processing to encourage fusion of macro ops. +//===----------------------------------------------------------------------===// + +namespace { +/// \brief Post-process the DAG to create cluster edges between instructions +/// that may be fused by the processor into a single operation. +class MacroFusion : public ScheduleDAGMutation { + const TargetInstrInfo *TII; +public: + MacroFusion(const TargetInstrInfo *tii): TII(tii) {} + + void apply(ScheduleDAGMI *DAG) override; +}; +} // anonymous + +/// \brief Callback from DAG postProcessing to create cluster edges to encourage +/// fused operations. +void MacroFusion::apply(ScheduleDAGMI *DAG) { + // For now, assume targets can only fuse with the branch. + MachineInstr *Branch = DAG->ExitSU.getInstr(); + if (!Branch) + return; + + for (unsigned Idx = DAG->SUnits.size(); Idx > 0;) { + SUnit *SU = &DAG->SUnits[--Idx]; + if (!TII->shouldScheduleAdjacent(SU->getInstr(), Branch)) + continue; + + // Create a single weak edge from SU to ExitSU. The only effect is to cause + // bottom-up scheduling to heavily prioritize the clustered SU. There is no + // need to copy predecessor edges from ExitSU to SU, since top-down + // scheduling cannot prioritize ExitSU anyway. To defer top-down scheduling + // of SU, we could create an artificial edge from the deepest root, but it + // hasn't been needed yet. + bool Success = DAG->addEdge(&DAG->ExitSU, SDep(SU, SDep::Cluster)); + (void)Success; + assert(Success && "No DAG nodes should be reachable from ExitSU"); + + DEBUG(dbgs() << "Macro Fuse SU(" << SU->NodeNum << ")\n"); + break; + } +} + +//===----------------------------------------------------------------------===// +// CopyConstrain - DAG post-processing to encourage copy elimination. +//===----------------------------------------------------------------------===// + +namespace { +/// \brief Post-process the DAG to create weak edges from all uses of a copy to +/// the one use that defines the copy's source vreg, most likely an induction +/// variable increment. +class CopyConstrain : public ScheduleDAGMutation { + // Transient state. + SlotIndex RegionBeginIdx; + // RegionEndIdx is the slot index of the last non-debug instruction in the + // scheduling region. So we may have RegionBeginIdx == RegionEndIdx. + SlotIndex RegionEndIdx; +public: + CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {} + + void apply(ScheduleDAGMI *DAG) override; + +protected: + void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG); +}; +} // anonymous + +/// constrainLocalCopy handles two possibilities: +/// 1) Local src: +/// I0: = dst +/// I1: src = ... +/// I2: = dst +/// I3: dst = src (copy) +/// (create pred->succ edges I0->I1, I2->I1) +/// +/// 2) Local copy: +/// I0: dst = src (copy) +/// I1: = dst +/// I2: src = ... +/// I3: = dst +/// (create pred->succ edges I1->I2, I3->I2) +/// +/// Although the MachineScheduler is currently constrained to single blocks, +/// this algorithm should handle extended blocks. An EBB is a set of +/// contiguously numbered blocks such that the previous block in the EBB is +/// always the single predecessor. +void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG) { + LiveIntervals *LIS = DAG->getLIS(); + MachineInstr *Copy = CopySU->getInstr(); + + // Check for pure vreg copies. + unsigned SrcReg = Copy->getOperand(1).getReg(); + if (!TargetRegisterInfo::isVirtualRegister(SrcReg)) + return; + + unsigned DstReg = Copy->getOperand(0).getReg(); + if (!TargetRegisterInfo::isVirtualRegister(DstReg)) + return; + + // Check if either the dest or source is local. If it's live across a back + // edge, it's not local. Note that if both vregs are live across the back + // edge, we cannot successfully contrain the copy without cyclic scheduling. + unsigned LocalReg = DstReg; + unsigned GlobalReg = SrcReg; + LiveInterval *LocalLI = &LIS->getInterval(LocalReg); + if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) { + LocalReg = SrcReg; + GlobalReg = DstReg; + LocalLI = &LIS->getInterval(LocalReg); + if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) + return; + } + LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg); + + // Find the global segment after the start of the local LI. + LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex()); + // If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a + // local live range. We could create edges from other global uses to the local + // start, but the coalescer should have already eliminated these cases, so + // don't bother dealing with it. + if (GlobalSegment == GlobalLI->end()) + return; + + // If GlobalSegment is killed at the LocalLI->start, the call to find() + // returned the next global segment. But if GlobalSegment overlaps with + // LocalLI->start, then advance to the next segement. If a hole in GlobalLI + // exists in LocalLI's vicinity, GlobalSegment will be the end of the hole. + if (GlobalSegment->contains(LocalLI->beginIndex())) + ++GlobalSegment; + + if (GlobalSegment == GlobalLI->end()) + return; + + // Check if GlobalLI contains a hole in the vicinity of LocalLI. + if (GlobalSegment != GlobalLI->begin()) { + // Two address defs have no hole. + if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->end, + GlobalSegment->start)) { + return; + } + // If the prior global segment may be defined by the same two-address + // instruction that also defines LocalLI, then can't make a hole here. + if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->start, + LocalLI->beginIndex())) { + return; + } + // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise + // it would be a disconnected component in the live range. + assert(std::prev(GlobalSegment)->start < LocalLI->beginIndex() && + "Disconnected LRG within the scheduling region."); + } + MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start); + if (!GlobalDef) + return; + + SUnit *GlobalSU = DAG->getSUnit(GlobalDef); + if (!GlobalSU) + return; + + // GlobalDef is the bottom of the GlobalLI hole. Open the hole by + // constraining the uses of the last local def to precede GlobalDef. + SmallVector LocalUses; + const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex()); + MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def); + SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef); + for (SUnit::const_succ_iterator + I = LastLocalSU->Succs.begin(), E = LastLocalSU->Succs.end(); + I != E; ++I) { + if (I->getKind() != SDep::Data || I->getReg() != LocalReg) + continue; + if (I->getSUnit() == GlobalSU) + continue; + if (!DAG->canAddEdge(GlobalSU, I->getSUnit())) + return; + LocalUses.push_back(I->getSUnit()); + } + // Open the top of the GlobalLI hole by constraining any earlier global uses + // to precede the start of LocalLI. + SmallVector GlobalUses; + MachineInstr *FirstLocalDef = + LIS->getInstructionFromIndex(LocalLI->beginIndex()); + SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef); + for (SUnit::const_pred_iterator + I = GlobalSU->Preds.begin(), E = GlobalSU->Preds.end(); I != E; ++I) { + if (I->getKind() != SDep::Anti || I->getReg() != GlobalReg) + continue; + if (I->getSUnit() == FirstLocalSU) + continue; + if (!DAG->canAddEdge(FirstLocalSU, I->getSUnit())) + return; + GlobalUses.push_back(I->getSUnit()); + } + DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n"); + // Add the weak edges. + for (SmallVectorImpl::const_iterator + I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) { + DEBUG(dbgs() << " Local use SU(" << (*I)->NodeNum << ") -> SU(" + << GlobalSU->NodeNum << ")\n"); + DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak)); + } + for (SmallVectorImpl::const_iterator + I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) { + DEBUG(dbgs() << " Global use SU(" << (*I)->NodeNum << ") -> SU(" + << FirstLocalSU->NodeNum << ")\n"); + DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak)); + } +} + +/// \brief Callback from DAG postProcessing to create weak edges to encourage +/// copy elimination. +void CopyConstrain::apply(ScheduleDAGMI *DAG) { + assert(DAG->hasVRegLiveness() && "Expect VRegs with LiveIntervals"); + + MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end()); + if (FirstPos == DAG->end()) + return; + RegionBeginIdx = DAG->getLIS()->getInstructionIndex(&*FirstPos); + RegionEndIdx = DAG->getLIS()->getInstructionIndex( + &*priorNonDebug(DAG->end(), DAG->begin())); + + for (unsigned Idx = 0, End = DAG->SUnits.size(); Idx != End; ++Idx) { + SUnit *SU = &DAG->SUnits[Idx]; + if (!SU->getInstr()->isCopy()) + continue; + + constrainLocalCopy(SU, static_cast(DAG)); + } +} + +//===----------------------------------------------------------------------===// +// MachineSchedStrategy helpers used by GenericScheduler, GenericPostScheduler +// and possibly other custom schedulers. +//===----------------------------------------------------------------------===// + +static const unsigned InvalidCycle = ~0U; + +SchedBoundary::~SchedBoundary() { delete HazardRec; } + +void SchedBoundary::reset() { + // A new HazardRec is created for each DAG and owned by SchedBoundary. + // Destroying and reconstructing it is very expensive though. So keep + // invalid, placeholder HazardRecs. + if (HazardRec && HazardRec->isEnabled()) { + delete HazardRec; + HazardRec = nullptr; + } + Available.clear(); + Pending.clear(); + CheckPending = false; + NextSUs.clear(); + CurrCycle = 0; + CurrMOps = 0; + MinReadyCycle = UINT_MAX; + ExpectedLatency = 0; + DependentLatency = 0; + RetiredMOps = 0; + MaxExecutedResCount = 0; + ZoneCritResIdx = 0; + IsResourceLimited = false; + ReservedCycles.clear(); +#ifndef NDEBUG + // Track the maximum number of stall cycles that could arise either from the + // latency of a DAG edge or the number of cycles that a processor resource is + // reserved (SchedBoundary::ReservedCycles). + MaxObservedLatency = 0; +#endif + // Reserve a zero-count for invalid CritResIdx. + ExecutedResCounts.resize(1); + assert(!ExecutedResCounts[0] && "nonzero count for bad resource"); +} + +void SchedRemainder:: +init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { + reset(); + if (!SchedModel->hasInstrSchedModel()) + return; + RemainingCounts.resize(SchedModel->getNumProcResourceKinds()); + for (std::vector::iterator + I = DAG->SUnits.begin(), E = DAG->SUnits.end(); I != E; ++I) { + const MCSchedClassDesc *SC = DAG->getSchedClass(&*I); + RemIssueCount += SchedModel->getNumMicroOps(I->getInstr(), SC) + * SchedModel->getMicroOpFactor(); + for (TargetSchedModel::ProcResIter + PI = SchedModel->getWriteProcResBegin(SC), + PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { + unsigned PIdx = PI->ProcResourceIdx; + unsigned Factor = SchedModel->getResourceFactor(PIdx); + RemainingCounts[PIdx] += (Factor * PI->Cycles); + } + } +} + +void SchedBoundary:: +init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) { + reset(); + DAG = dag; + SchedModel = smodel; + Rem = rem; + if (SchedModel->hasInstrSchedModel()) { + ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds()); + ReservedCycles.resize(SchedModel->getNumProcResourceKinds(), InvalidCycle); + } +} + +/// Compute the stall cycles based on this SUnit's ready time. Heuristics treat +/// these "soft stalls" differently than the hard stall cycles based on CPU +/// resources and computed by checkHazard(). A fully in-order model +/// (MicroOpBufferSize==0) will not make use of this since instructions are not +/// available for scheduling until they are ready. However, a weaker in-order +/// model may use this for heuristics. For example, if a processor has in-order +/// behavior when reading certain resources, this may come into play. +unsigned SchedBoundary::getLatencyStallCycles(SUnit *SU) { + if (!SU->isUnbuffered) + return 0; + + unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); + if (ReadyCycle > CurrCycle) + return ReadyCycle - CurrCycle; + return 0; +} + +/// Compute the next cycle at which the given processor resource can be +/// scheduled. +unsigned SchedBoundary:: +getNextResourceCycle(unsigned PIdx, unsigned Cycles) { + unsigned NextUnreserved = ReservedCycles[PIdx]; + // If this resource has never been used, always return cycle zero. + if (NextUnreserved == InvalidCycle) + return 0; + // For bottom-up scheduling add the cycles needed for the current operation. + if (!isTop()) + NextUnreserved += Cycles; + return NextUnreserved; +} + +/// Does this SU have a hazard within the current instruction group. +/// +/// The scheduler supports two modes of hazard recognition. The first is the +/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that +/// supports highly complicated in-order reservation tables +/// (ScoreboardHazardRecognizer) and arbitraty target-specific logic. +/// +/// The second is a streamlined mechanism that checks for hazards based on +/// simple counters that the scheduler itself maintains. It explicitly checks +/// for instruction dispatch limitations, including the number of micro-ops that +/// can dispatch per cycle. +/// +/// TODO: Also check whether the SU must start a new group. +bool SchedBoundary::checkHazard(SUnit *SU) { + if (HazardRec->isEnabled() + && HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard) { + return true; + } + unsigned uops = SchedModel->getNumMicroOps(SU->getInstr()); + if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) { + DEBUG(dbgs() << " SU(" << SU->NodeNum << ") uops=" + << SchedModel->getNumMicroOps(SU->getInstr()) << '\n'); + return true; + } + if (SchedModel->hasInstrSchedModel() && SU->hasReservedResource) { + const MCSchedClassDesc *SC = DAG->getSchedClass(SU); + for (TargetSchedModel::ProcResIter + PI = SchedModel->getWriteProcResBegin(SC), + PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { + if (getNextResourceCycle(PI->ProcResourceIdx, PI->Cycles) > CurrCycle) + return true; + } + } + return false; +} + +// Find the unscheduled node in ReadySUs with the highest latency. +unsigned SchedBoundary:: +findMaxLatency(ArrayRef ReadySUs) { + SUnit *LateSU = nullptr; + unsigned RemLatency = 0; + for (ArrayRef::iterator I = ReadySUs.begin(), E = ReadySUs.end(); + I != E; ++I) { + unsigned L = getUnscheduledLatency(*I); + if (L > RemLatency) { + RemLatency = L; + LateSU = *I; + } + } + if (LateSU) { + DEBUG(dbgs() << Available.getName() << " RemLatency SU(" + << LateSU->NodeNum << ") " << RemLatency << "c\n"); + } + return RemLatency; +} + +// Count resources in this zone and the remaining unscheduled +// instruction. Return the max count, scaled. Set OtherCritIdx to the critical +// resource index, or zero if the zone is issue limited. +unsigned SchedBoundary:: +getOtherResourceCount(unsigned &OtherCritIdx) { + OtherCritIdx = 0; + if (!SchedModel->hasInstrSchedModel()) + return 0; + + unsigned OtherCritCount = Rem->RemIssueCount + + (RetiredMOps * SchedModel->getMicroOpFactor()); + DEBUG(dbgs() << " " << Available.getName() << " + Remain MOps: " + << OtherCritCount / SchedModel->getMicroOpFactor() << '\n'); + for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds(); + PIdx != PEnd; ++PIdx) { + unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx]; + if (OtherCount > OtherCritCount) { + OtherCritCount = OtherCount; + OtherCritIdx = PIdx; + } + } + if (OtherCritIdx) { + DEBUG(dbgs() << " " << Available.getName() << " + Remain CritRes: " + << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx) + << " " << SchedModel->getResourceName(OtherCritIdx) << "\n"); + } + return OtherCritCount; +} + +void SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle) { + if (ReadyCycle < MinReadyCycle) + MinReadyCycle = ReadyCycle; + + // Check for interlocks first. For the purpose of other heuristics, an + // instruction that cannot issue appears as if it's not in the ReadyQueue. + bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; + if ((!IsBuffered && ReadyCycle > CurrCycle) || checkHazard(SU)) + Pending.push(SU); + else + Available.push(SU); + + // Record this node as an immediate dependent of the scheduled node. + NextSUs.insert(SU); +} + +void SchedBoundary::releaseTopNode(SUnit *SU) { + if (SU->isScheduled) + return; + + for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); + I != E; ++I) { + if (I->isWeak()) + continue; + unsigned PredReadyCycle = I->getSUnit()->TopReadyCycle; + unsigned Latency = I->getLatency(); +#ifndef NDEBUG + MaxObservedLatency = std::max(Latency, MaxObservedLatency); +#endif + if (SU->TopReadyCycle < PredReadyCycle + Latency) + SU->TopReadyCycle = PredReadyCycle + Latency; + } + releaseNode(SU, SU->TopReadyCycle); +} + +void SchedBoundary::releaseBottomNode(SUnit *SU) { + if (SU->isScheduled) + return; + + assert(SU->getInstr() && "Scheduled SUnit must have instr"); + + for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); + I != E; ++I) { + if (I->isWeak()) + continue; + unsigned SuccReadyCycle = I->getSUnit()->BotReadyCycle; + unsigned Latency = I->getLatency(); +#ifndef NDEBUG + MaxObservedLatency = std::max(Latency, MaxObservedLatency); +#endif + if (SU->BotReadyCycle < SuccReadyCycle + Latency) + SU->BotReadyCycle = SuccReadyCycle + Latency; + } + releaseNode(SU, SU->BotReadyCycle); +} + +/// Move the boundary of scheduled code by one cycle. +void SchedBoundary::bumpCycle(unsigned NextCycle) { + if (SchedModel->getMicroOpBufferSize() == 0) { + assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized"); + if (MinReadyCycle > NextCycle) + NextCycle = MinReadyCycle; + } + // Update the current micro-ops, which will issue in the next cycle. + unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle); + CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps; + + // Decrement DependentLatency based on the next cycle. + if ((NextCycle - CurrCycle) > DependentLatency) + DependentLatency = 0; + else + DependentLatency -= (NextCycle - CurrCycle); + + if (!HazardRec->isEnabled()) { + // Bypass HazardRec virtual calls. + CurrCycle = NextCycle; + } + else { + // Bypass getHazardType calls in case of long latency. + for (; CurrCycle != NextCycle; ++CurrCycle) { + if (isTop()) + HazardRec->AdvanceCycle(); + else + HazardRec->RecedeCycle(); + } + } + CheckPending = true; + unsigned LFactor = SchedModel->getLatencyFactor(); + IsResourceLimited = + (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) + > (int)LFactor; + + DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n'); +} + +void SchedBoundary::incExecutedResources(unsigned PIdx, unsigned Count) { + ExecutedResCounts[PIdx] += Count; + if (ExecutedResCounts[PIdx] > MaxExecutedResCount) + MaxExecutedResCount = ExecutedResCounts[PIdx]; +} + +/// Add the given processor resource to this scheduled zone. +/// +/// \param Cycles indicates the number of consecutive (non-pipelined) cycles +/// during which this resource is consumed. +/// +/// \return the next cycle at which the instruction may execute without +/// oversubscribing resources. +unsigned SchedBoundary:: +countResource(unsigned PIdx, unsigned Cycles, unsigned NextCycle) { + unsigned Factor = SchedModel->getResourceFactor(PIdx); + unsigned Count = Factor * Cycles; + DEBUG(dbgs() << " " << SchedModel->getResourceName(PIdx) + << " +" << Cycles << "x" << Factor << "u\n"); + + // Update Executed resources counts. + incExecutedResources(PIdx, Count); + assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted"); + Rem->RemainingCounts[PIdx] -= Count; + + // Check if this resource exceeds the current critical resource. If so, it + // becomes the critical resource. + if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) { + ZoneCritResIdx = PIdx; + DEBUG(dbgs() << " *** Critical resource " + << SchedModel->getResourceName(PIdx) << ": " + << getResourceCount(PIdx) / SchedModel->getLatencyFactor() << "c\n"); + } + // For reserved resources, record the highest cycle using the resource. + unsigned NextAvailable = getNextResourceCycle(PIdx, Cycles); + if (NextAvailable > CurrCycle) { + DEBUG(dbgs() << " Resource conflict: " + << SchedModel->getProcResource(PIdx)->Name << " reserved until @" + << NextAvailable << "\n"); + } + return NextAvailable; +} + +/// Move the boundary of scheduled code by one SUnit. +void SchedBoundary::bumpNode(SUnit *SU) { + // Update the reservation table. + if (HazardRec->isEnabled()) { + if (!isTop() && SU->isCall) { + // Calls are scheduled with their preceding instructions. For bottom-up + // scheduling, clear the pipeline state before emitting. + HazardRec->Reset(); + } + HazardRec->EmitInstruction(SU); + } + // checkHazard should prevent scheduling multiple instructions per cycle that + // exceed the issue width. + const MCSchedClassDesc *SC = DAG->getSchedClass(SU); + unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr()); + assert( + (CurrMOps == 0 || (CurrMOps + IncMOps) <= SchedModel->getIssueWidth()) && + "Cannot schedule this instruction's MicroOps in the current cycle."); + + unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); + DEBUG(dbgs() << " Ready @" << ReadyCycle << "c\n"); + + unsigned NextCycle = CurrCycle; + switch (SchedModel->getMicroOpBufferSize()) { + case 0: + assert(ReadyCycle <= CurrCycle && "Broken PendingQueue"); + break; + case 1: + if (ReadyCycle > NextCycle) { + NextCycle = ReadyCycle; + DEBUG(dbgs() << " *** Stall until: " << ReadyCycle << "\n"); + } + break; + default: + // We don't currently model the OOO reorder buffer, so consider all + // scheduled MOps to be "retired". We do loosely model in-order resource + // latency. If this instruction uses an in-order resource, account for any + // likely stall cycles. + if (SU->isUnbuffered && ReadyCycle > NextCycle) + NextCycle = ReadyCycle; + break; + } + RetiredMOps += IncMOps; + + // Update resource counts and critical resource. + if (SchedModel->hasInstrSchedModel()) { + unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor(); + assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted"); + Rem->RemIssueCount -= DecRemIssue; + if (ZoneCritResIdx) { + // Scale scheduled micro-ops for comparing with the critical resource. + unsigned ScaledMOps = + RetiredMOps * SchedModel->getMicroOpFactor(); + + // If scaled micro-ops are now more than the previous critical resource by + // a full cycle, then micro-ops issue becomes critical. + if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx)) + >= (int)SchedModel->getLatencyFactor()) { + ZoneCritResIdx = 0; + DEBUG(dbgs() << " *** Critical resource NumMicroOps: " + << ScaledMOps / SchedModel->getLatencyFactor() << "c\n"); + } + } + for (TargetSchedModel::ProcResIter + PI = SchedModel->getWriteProcResBegin(SC), + PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { + unsigned RCycle = + countResource(PI->ProcResourceIdx, PI->Cycles, NextCycle); + if (RCycle > NextCycle) + NextCycle = RCycle; + } + if (SU->hasReservedResource) { + // For reserved resources, record the highest cycle using the resource. + // For top-down scheduling, this is the cycle in which we schedule this + // instruction plus the number of cycles the operations reserves the + // resource. For bottom-up is it simply the instruction's cycle. + for (TargetSchedModel::ProcResIter + PI = SchedModel->getWriteProcResBegin(SC), + PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { + unsigned PIdx = PI->ProcResourceIdx; + if (SchedModel->getProcResource(PIdx)->BufferSize == 0) { + ReservedCycles[PIdx] = isTop() ? NextCycle + PI->Cycles : NextCycle; +#ifndef NDEBUG + MaxObservedLatency = std::max(PI->Cycles, MaxObservedLatency); +#endif + } + } + } + } + // Update ExpectedLatency and DependentLatency. + unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency; + unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency; + if (SU->getDepth() > TopLatency) { + TopLatency = SU->getDepth(); + DEBUG(dbgs() << " " << Available.getName() + << " TopLatency SU(" << SU->NodeNum << ") " << TopLatency << "c\n"); + } + if (SU->getHeight() > BotLatency) { + BotLatency = SU->getHeight(); + DEBUG(dbgs() << " " << Available.getName() + << " BotLatency SU(" << SU->NodeNum << ") " << BotLatency << "c\n"); + } + // If we stall for any reason, bump the cycle. + if (NextCycle > CurrCycle) { + bumpCycle(NextCycle); + } + else { + // After updating ZoneCritResIdx and ExpectedLatency, check if we're + // resource limited. If a stall occurred, bumpCycle does this. + unsigned LFactor = SchedModel->getLatencyFactor(); + IsResourceLimited = + (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) + > (int)LFactor; + } + // Update CurrMOps after calling bumpCycle to handle stalls, since bumpCycle + // resets CurrMOps. Loop to handle instructions with more MOps than issue in + // one cycle. Since we commonly reach the max MOps here, opportunistically + // bump the cycle to avoid uselessly checking everything in the readyQ. + CurrMOps += IncMOps; + while (CurrMOps >= SchedModel->getIssueWidth()) { + DEBUG(dbgs() << " *** Max MOps " << CurrMOps + << " at cycle " << CurrCycle << '\n'); + bumpCycle(++NextCycle); + } + DEBUG(dumpScheduledState()); +} + +/// Release pending ready nodes in to the available queue. This makes them +/// visible to heuristics. +void SchedBoundary::releasePending() { + // If the available queue is empty, it is safe to reset MinReadyCycle. + if (Available.empty()) + MinReadyCycle = UINT_MAX; + + // Check to see if any of the pending instructions are ready to issue. If + // so, add them to the available queue. + bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; + for (unsigned i = 0, e = Pending.size(); i != e; ++i) { + SUnit *SU = *(Pending.begin()+i); + unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle; + + if (ReadyCycle < MinReadyCycle) + MinReadyCycle = ReadyCycle; + + if (!IsBuffered && ReadyCycle > CurrCycle) + continue; + + if (checkHazard(SU)) + continue; + + Available.push(SU); + Pending.remove(Pending.begin()+i); + --i; --e; + } + DEBUG(if (!Pending.empty()) Pending.dump()); + CheckPending = false; +} + +/// Remove SU from the ready set for this boundary. +void SchedBoundary::removeReady(SUnit *SU) { + if (Available.isInQueue(SU)) + Available.remove(Available.find(SU)); + else { + assert(Pending.isInQueue(SU) && "bad ready count"); + Pending.remove(Pending.find(SU)); + } +} + +/// If this queue only has one ready candidate, return it. As a side effect, +/// defer any nodes that now hit a hazard, and advance the cycle until at least +/// one node is ready. If multiple instructions are ready, return NULL. +SUnit *SchedBoundary::pickOnlyChoice() { + if (CheckPending) + releasePending(); + + if (CurrMOps > 0) { + // Defer any ready instrs that now have a hazard. + for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) { + if (checkHazard(*I)) { + Pending.push(*I); + I = Available.remove(I); + continue; + } + ++I; + } + } + for (unsigned i = 0; Available.empty(); ++i) { + assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) && + "permanent hazard"); (void)i; + bumpCycle(CurrCycle + 1); + releasePending(); + } + if (Available.size() == 1) + return *Available.begin(); + return nullptr; +} + +#ifndef NDEBUG +// This is useful information to dump after bumpNode. +// Note that the Queue contents are more useful before pickNodeFromQueue. +void SchedBoundary::dumpScheduledState() { + unsigned ResFactor; + unsigned ResCount; + if (ZoneCritResIdx) { + ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx); + ResCount = getResourceCount(ZoneCritResIdx); + } + else { + ResFactor = SchedModel->getMicroOpFactor(); + ResCount = RetiredMOps * SchedModel->getMicroOpFactor(); } + unsigned LFactor = SchedModel->getLatencyFactor(); + dbgs() << Available.getName() << " @" << CurrCycle << "c\n" + << " Retired: " << RetiredMOps; + dbgs() << "\n Executed: " << getExecutedCount() / LFactor << "c"; + dbgs() << "\n Critical: " << ResCount / LFactor << "c, " + << ResCount / ResFactor << " " + << SchedModel->getResourceName(ZoneCritResIdx) + << "\n ExpectedLatency: " << ExpectedLatency << "c\n" + << (IsResourceLimited ? " - Resource" : " - Latency") + << " limited.\n"; } +#endif //===----------------------------------------------------------------------===// -// ConvergingScheduler - Implementation of the generic MachineSchedStrategy. +// GenericScheduler - Generic implementation of MachineSchedStrategy. //===----------------------------------------------------------------------===// namespace { -/// ConvergingScheduler shrinks the unscheduled zone using heuristics to balance -/// the schedule. -class ConvergingScheduler : public MachineSchedStrategy { +/// Base class for GenericScheduler. This class maintains information about +/// scheduling candidates based on TargetSchedModel making it easy to implement +/// heuristics for either preRA or postRA scheduling. +class GenericSchedulerBase : public MachineSchedStrategy { public: /// Represent the type of SchedCandidate found within a single queue. /// pickNodeBidirectional depends on these listed by decreasing priority. enum CandReason { - NoCand, PhysRegCopy, RegExcess, RegCritical, Cluster, Weak, RegMax, + NoCand, PhysRegCopy, RegExcess, RegCritical, Stall, Cluster, Weak, RegMax, ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce, TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder}; #ifndef NDEBUG - static const char *getReasonStr(ConvergingScheduler::CandReason Reason); + static const char *getReasonStr(GenericSchedulerBase::CandReason Reason); #endif /// Policy for scheduling the next instruction in the candidate's zone. @@ -1249,7 +2135,7 @@ public: } }; - /// Store the state used by ConvergingScheduler heuristics, required for the + /// Store the state used by GenericScheduler heuristics, required for the /// lifetime of one invocation of pickNode(). struct SchedCandidate { CandPolicy Policy; @@ -1270,7 +2156,7 @@ public: SchedResourceDelta ResDelta; SchedCandidate(const CandPolicy &policy) - : Policy(policy), SU(NULL), Reason(NoCand), RepeatReasonSet(0) {} + : Policy(policy), SU(nullptr), Reason(NoCand), RepeatReasonSet(0) {} bool isValid() const { return SU; } @@ -1287,496 +2173,54 @@ public: void setRepeat(CandReason R) { RepeatReasonSet |= (1 << R); } void initResourceDelta(const ScheduleDAGMI *DAG, - const TargetSchedModel *SchedModel); - }; - - /// Summarize the unscheduled region. - struct SchedRemainder { - // Critical path through the DAG in expected latency. - unsigned CriticalPath; - unsigned CyclicCritPath; - - // Scaled count of micro-ops left to schedule. - unsigned RemIssueCount; - - bool IsAcyclicLatencyLimited; - - // Unscheduled resources - SmallVector RemainingCounts; - - void reset() { - CriticalPath = 0; - CyclicCritPath = 0; - RemIssueCount = 0; - IsAcyclicLatencyLimited = false; - RemainingCounts.clear(); - } - - SchedRemainder() { reset(); } - - void init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel); - }; - - /// Each Scheduling boundary is associated with ready queues. It tracks the - /// current cycle in the direction of movement, and maintains the state - /// of "hazards" and other interlocks at the current cycle. - struct SchedBoundary { - ScheduleDAGMI *DAG; - const TargetSchedModel *SchedModel; - SchedRemainder *Rem; - - ReadyQueue Available; - ReadyQueue Pending; - bool CheckPending; - - // For heuristics, keep a list of the nodes that immediately depend on the - // most recently scheduled node. - SmallPtrSet NextSUs; - - ScheduleHazardRecognizer *HazardRec; - - /// Number of cycles it takes to issue the instructions scheduled in this - /// zone. It is defined as: scheduled-micro-ops / issue-width + stalls. - /// See getStalls(). - unsigned CurrCycle; - - /// Micro-ops issued in the current cycle - unsigned CurrMOps; - - /// MinReadyCycle - Cycle of the soonest available instruction. - unsigned MinReadyCycle; - - // The expected latency of the critical path in this scheduled zone. - unsigned ExpectedLatency; - - // The latency of dependence chains leading into this zone. - // For each node scheduled bottom-up: DLat = max DLat, N.Depth. - // For each cycle scheduled: DLat -= 1. - unsigned DependentLatency; - - /// Count the scheduled (issued) micro-ops that can be retired by - /// time=CurrCycle assuming the first scheduled instr is retired at time=0. - unsigned RetiredMOps; - - // Count scheduled resources that have been executed. Resources are - // considered executed if they become ready in the time that it takes to - // saturate any resource including the one in question. Counts are scaled - // for direct comparison with other resources. Counts can be compared with - // MOps * getMicroOpFactor and Latency * getLatencyFactor. - SmallVector ExecutedResCounts; - - /// Cache the max count for a single resource. - unsigned MaxExecutedResCount; - - // Cache the critical resources ID in this scheduled zone. - unsigned ZoneCritResIdx; - - // Is the scheduled region resource limited vs. latency limited. - bool IsResourceLimited; - -#ifndef NDEBUG - // Remember the greatest operand latency as an upper bound on the number of - // times we should retry the pending queue because of a hazard. - unsigned MaxObservedLatency; -#endif - - void reset() { - // A new HazardRec is created for each DAG and owned by SchedBoundary. - delete HazardRec; - - Available.clear(); - Pending.clear(); - CheckPending = false; - NextSUs.clear(); - HazardRec = 0; - CurrCycle = 0; - CurrMOps = 0; - MinReadyCycle = UINT_MAX; - ExpectedLatency = 0; - DependentLatency = 0; - RetiredMOps = 0; - MaxExecutedResCount = 0; - ZoneCritResIdx = 0; - IsResourceLimited = false; -#ifndef NDEBUG - MaxObservedLatency = 0; -#endif - // Reserve a zero-count for invalid CritResIdx. - ExecutedResCounts.resize(1); - assert(!ExecutedResCounts[0] && "nonzero count for bad resource"); - } - - /// Pending queues extend the ready queues with the same ID and the - /// PendingFlag set. - SchedBoundary(unsigned ID, const Twine &Name): - DAG(0), SchedModel(0), Rem(0), Available(ID, Name+".A"), - Pending(ID << ConvergingScheduler::LogMaxQID, Name+".P"), - HazardRec(0) { - reset(); - } - - ~SchedBoundary() { delete HazardRec; } - - void init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, - SchedRemainder *rem); - - bool isTop() const { - return Available.getID() == ConvergingScheduler::TopQID; - } - -#ifndef NDEBUG - const char *getResourceName(unsigned PIdx) { - if (!PIdx) - return "MOps"; - return SchedModel->getProcResource(PIdx)->Name; - } -#endif - - /// Get the number of latency cycles "covered" by the scheduled - /// instructions. This is the larger of the critical path within the zone - /// and the number of cycles required to issue the instructions. - unsigned getScheduledLatency() const { - return std::max(ExpectedLatency, CurrCycle); - } - - unsigned getUnscheduledLatency(SUnit *SU) const { - return isTop() ? SU->getHeight() : SU->getDepth(); - } - - unsigned getResourceCount(unsigned ResIdx) const { - return ExecutedResCounts[ResIdx]; - } - - /// Get the scaled count of scheduled micro-ops and resources, including - /// executed resources. - unsigned getCriticalCount() const { - if (!ZoneCritResIdx) - return RetiredMOps * SchedModel->getMicroOpFactor(); - return getResourceCount(ZoneCritResIdx); - } - - /// Get a scaled count for the minimum execution time of the scheduled - /// micro-ops that are ready to execute by getExecutedCount. Notice the - /// feedback loop. - unsigned getExecutedCount() const { - return std::max(CurrCycle * SchedModel->getLatencyFactor(), - MaxExecutedResCount); - } - - bool checkHazard(SUnit *SU); - - unsigned findMaxLatency(ArrayRef ReadySUs); - - unsigned getOtherResourceCount(unsigned &OtherCritIdx); - - void setPolicy(CandPolicy &Policy, SchedBoundary &OtherZone); - - void releaseNode(SUnit *SU, unsigned ReadyCycle); - - void bumpCycle(unsigned NextCycle); - - void incExecutedResources(unsigned PIdx, unsigned Count); - - unsigned countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle); - - void bumpNode(SUnit *SU); - - void releasePending(); - - void removeReady(SUnit *SU); - - SUnit *pickOnlyChoice(); - -#ifndef NDEBUG - void dumpScheduledState(); -#endif - }; - -private: - ScheduleDAGMI *DAG; - const TargetSchedModel *SchedModel; - const TargetRegisterInfo *TRI; - - // State of the top and bottom scheduled instruction boundaries. - SchedRemainder Rem; - SchedBoundary Top; - SchedBoundary Bot; - -public: - /// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both) - enum { - TopQID = 1, - BotQID = 2, - LogMaxQID = 2 - }; - - ConvergingScheduler(): - DAG(0), SchedModel(0), TRI(0), Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {} - - virtual void initialize(ScheduleDAGMI *dag); - - virtual SUnit *pickNode(bool &IsTopNode); - - virtual void schedNode(SUnit *SU, bool IsTopNode); - - virtual void releaseTopNode(SUnit *SU); - - virtual void releaseBottomNode(SUnit *SU); - - virtual void registerRoots(); - -protected: - void checkAcyclicLatency(); - - void tryCandidate(SchedCandidate &Cand, - SchedCandidate &TryCand, - SchedBoundary &Zone, - const RegPressureTracker &RPTracker, - RegPressureTracker &TempTracker); - - SUnit *pickNodeBidirectional(bool &IsTopNode); - - void pickNodeFromQueue(SchedBoundary &Zone, - const RegPressureTracker &RPTracker, - SchedCandidate &Candidate); - - void reschedulePhysRegCopies(SUnit *SU, bool isTop); - -#ifndef NDEBUG - void traceCandidate(const SchedCandidate &Cand); -#endif -}; -} // namespace - -void ConvergingScheduler::SchedRemainder:: -init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { - reset(); - if (!SchedModel->hasInstrSchedModel()) - return; - RemainingCounts.resize(SchedModel->getNumProcResourceKinds()); - for (std::vector::iterator - I = DAG->SUnits.begin(), E = DAG->SUnits.end(); I != E; ++I) { - const MCSchedClassDesc *SC = DAG->getSchedClass(&*I); - RemIssueCount += SchedModel->getNumMicroOps(I->getInstr(), SC) - * SchedModel->getMicroOpFactor(); - for (TargetSchedModel::ProcResIter - PI = SchedModel->getWriteProcResBegin(SC), - PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { - unsigned PIdx = PI->ProcResourceIdx; - unsigned Factor = SchedModel->getResourceFactor(PIdx); - RemainingCounts[PIdx] += (Factor * PI->Cycles); - } - } -} - -void ConvergingScheduler::SchedBoundary:: -init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) { - reset(); - DAG = dag; - SchedModel = smodel; - Rem = rem; - if (SchedModel->hasInstrSchedModel()) - ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds()); -} - -void ConvergingScheduler::initialize(ScheduleDAGMI *dag) { - DAG = dag; - SchedModel = DAG->getSchedModel(); - TRI = DAG->TRI; - - Rem.init(DAG, SchedModel); - Top.init(DAG, SchedModel, &Rem); - Bot.init(DAG, SchedModel, &Rem); - - // Initialize resource counts. - - // Initialize the HazardRecognizers. If itineraries don't exist, are empty, or - // are disabled, then these HazardRecs will be disabled. - const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); - const TargetMachine &TM = DAG->MF.getTarget(); - Top.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); - Bot.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); - - assert((!ForceTopDown || !ForceBottomUp) && - "-misched-topdown incompatible with -misched-bottomup"); -} - -void ConvergingScheduler::releaseTopNode(SUnit *SU) { - if (SU->isScheduled) - return; - - for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); - I != E; ++I) { - if (I->isWeak()) - continue; - unsigned PredReadyCycle = I->getSUnit()->TopReadyCycle; - unsigned Latency = I->getLatency(); -#ifndef NDEBUG - Top.MaxObservedLatency = std::max(Latency, Top.MaxObservedLatency); -#endif - if (SU->TopReadyCycle < PredReadyCycle + Latency) - SU->TopReadyCycle = PredReadyCycle + Latency; - } - Top.releaseNode(SU, SU->TopReadyCycle); -} - -void ConvergingScheduler::releaseBottomNode(SUnit *SU) { - if (SU->isScheduled) - return; - - assert(SU->getInstr() && "Scheduled SUnit must have instr"); - - for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); - I != E; ++I) { - if (I->isWeak()) - continue; - unsigned SuccReadyCycle = I->getSUnit()->BotReadyCycle; - unsigned Latency = I->getLatency(); -#ifndef NDEBUG - Bot.MaxObservedLatency = std::max(Latency, Bot.MaxObservedLatency); -#endif - if (SU->BotReadyCycle < SuccReadyCycle + Latency) - SU->BotReadyCycle = SuccReadyCycle + Latency; - } - Bot.releaseNode(SU, SU->BotReadyCycle); -} - -/// Set IsAcyclicLatencyLimited if the acyclic path is longer than the cyclic -/// critical path by more cycles than it takes to drain the instruction buffer. -/// We estimate an upper bounds on in-flight instructions as: -/// -/// CyclesPerIteration = max( CyclicPath, Loop-Resource-Height ) -/// InFlightIterations = AcyclicPath / CyclesPerIteration -/// InFlightResources = InFlightIterations * LoopResources -/// -/// TODO: Check execution resources in addition to IssueCount. -void ConvergingScheduler::checkAcyclicLatency() { - if (Rem.CyclicCritPath == 0 || Rem.CyclicCritPath >= Rem.CriticalPath) - return; - - // Scaled number of cycles per loop iteration. - unsigned IterCount = - std::max(Rem.CyclicCritPath * SchedModel->getLatencyFactor(), - Rem.RemIssueCount); - // Scaled acyclic critical path. - unsigned AcyclicCount = Rem.CriticalPath * SchedModel->getLatencyFactor(); - // InFlightCount = (AcyclicPath / IterCycles) * InstrPerLoop - unsigned InFlightCount = - (AcyclicCount * Rem.RemIssueCount + IterCount-1) / IterCount; - unsigned BufferLimit = - SchedModel->getMicroOpBufferSize() * SchedModel->getMicroOpFactor(); - - Rem.IsAcyclicLatencyLimited = InFlightCount > BufferLimit; - - DEBUG(dbgs() << "IssueCycles=" - << Rem.RemIssueCount / SchedModel->getLatencyFactor() << "c " - << "IterCycles=" << IterCount / SchedModel->getLatencyFactor() - << "c NumIters=" << (AcyclicCount + IterCount-1) / IterCount - << " InFlight=" << InFlightCount / SchedModel->getMicroOpFactor() - << "m BufferLim=" << SchedModel->getMicroOpBufferSize() << "m\n"; - if (Rem.IsAcyclicLatencyLimited) - dbgs() << " ACYCLIC LATENCY LIMIT\n"); -} - -void ConvergingScheduler::registerRoots() { - Rem.CriticalPath = DAG->ExitSU.getDepth(); - - // Some roots may not feed into ExitSU. Check all of them in case. - for (std::vector::const_iterator - I = Bot.Available.begin(), E = Bot.Available.end(); I != E; ++I) { - if ((*I)->getDepth() > Rem.CriticalPath) - Rem.CriticalPath = (*I)->getDepth(); - } - DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n'); - - if (EnableCyclicPath) { - Rem.CyclicCritPath = DAG->computeCyclicCriticalPath(); - checkAcyclicLatency(); - } -} + const TargetSchedModel *SchedModel); + }; -/// Does this SU have a hazard within the current instruction group. -/// -/// The scheduler supports two modes of hazard recognition. The first is the -/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that -/// supports highly complicated in-order reservation tables -/// (ScoreboardHazardRecognizer) and arbitraty target-specific logic. -/// -/// The second is a streamlined mechanism that checks for hazards based on -/// simple counters that the scheduler itself maintains. It explicitly checks -/// for instruction dispatch limitations, including the number of micro-ops that -/// can dispatch per cycle. -/// -/// TODO: Also check whether the SU must start a new group. -bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) { - if (HazardRec->isEnabled()) - return HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard; +protected: + const MachineSchedContext *Context; + const TargetSchedModel *SchedModel; + const TargetRegisterInfo *TRI; - unsigned uops = SchedModel->getNumMicroOps(SU->getInstr()); - if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) { - DEBUG(dbgs() << " SU(" << SU->NodeNum << ") uops=" - << SchedModel->getNumMicroOps(SU->getInstr()) << '\n'); - return true; - } - return false; -} + SchedRemainder Rem; +protected: + GenericSchedulerBase(const MachineSchedContext *C): + Context(C), SchedModel(nullptr), TRI(nullptr) {} -// Find the unscheduled node in ReadySUs with the highest latency. -unsigned ConvergingScheduler::SchedBoundary:: -findMaxLatency(ArrayRef ReadySUs) { - SUnit *LateSU = 0; - unsigned RemLatency = 0; - for (ArrayRef::iterator I = ReadySUs.begin(), E = ReadySUs.end(); - I != E; ++I) { - unsigned L = getUnscheduledLatency(*I); - if (L > RemLatency) { - RemLatency = L; - LateSU = *I; - } - } - if (LateSU) { - DEBUG(dbgs() << Available.getName() << " RemLatency SU(" - << LateSU->NodeNum << ") " << RemLatency << "c\n"); - } - return RemLatency; -} + void setPolicy(CandPolicy &Policy, bool IsPostRA, SchedBoundary &CurrZone, + SchedBoundary *OtherZone); -// Count resources in this zone and the remaining unscheduled -// instruction. Return the max count, scaled. Set OtherCritIdx to the critical -// resource index, or zero if the zone is issue limited. -unsigned ConvergingScheduler::SchedBoundary:: -getOtherResourceCount(unsigned &OtherCritIdx) { - OtherCritIdx = 0; - if (!SchedModel->hasInstrSchedModel()) - return 0; +#ifndef NDEBUG + void traceCandidate(const SchedCandidate &Cand); +#endif +}; +} // namespace - unsigned OtherCritCount = Rem->RemIssueCount - + (RetiredMOps * SchedModel->getMicroOpFactor()); - DEBUG(dbgs() << " " << Available.getName() << " + Remain MOps: " - << OtherCritCount / SchedModel->getMicroOpFactor() << '\n'); - for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds(); - PIdx != PEnd; ++PIdx) { - unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx]; - if (OtherCount > OtherCritCount) { - OtherCritCount = OtherCount; - OtherCritIdx = PIdx; - } - } - if (OtherCritIdx) { - DEBUG(dbgs() << " " << Available.getName() << " + Remain CritRes: " - << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx) - << " " << getResourceName(OtherCritIdx) << "\n"); +void GenericSchedulerBase::SchedCandidate:: +initResourceDelta(const ScheduleDAGMI *DAG, + const TargetSchedModel *SchedModel) { + if (!Policy.ReduceResIdx && !Policy.DemandResIdx) + return; + + const MCSchedClassDesc *SC = DAG->getSchedClass(SU); + for (TargetSchedModel::ProcResIter + PI = SchedModel->getWriteProcResBegin(SC), + PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { + if (PI->ProcResourceIdx == Policy.ReduceResIdx) + ResDelta.CritResources += PI->Cycles; + if (PI->ProcResourceIdx == Policy.DemandResIdx) + ResDelta.DemandedResources += PI->Cycles; } - return OtherCritCount; } -/// Set the CandPolicy for this zone given the current resources and latencies -/// inside and outside the zone. -void ConvergingScheduler::SchedBoundary::setPolicy(CandPolicy &Policy, - SchedBoundary &OtherZone) { - // Now that potential stalls have been considered, apply preemptive heuristics - // based on the the total latency and resources inside and outside this - // zone. +/// Set the CandPolicy given a scheduling zone given the current resources and +/// latencies inside and outside the zone. +void GenericSchedulerBase::setPolicy(CandPolicy &Policy, + bool IsPostRA, + SchedBoundary &CurrZone, + SchedBoundary *OtherZone) { + // Apply preemptive heuristics based on the the total latency and resources + // inside and outside this zone. Potential stalls should be considered before + // following this policy. // Compute remaining latency. We need this both to determine whether the // overall schedule has become latency-limited and whether the instructions @@ -1791,412 +2235,407 @@ void ConvergingScheduler::SchedBoundary::setPolicy(CandPolicy &Policy, // ILat = max N.depth for N in Available|Pending // // RemainingLatency is the greater of independent and dependent latency. - unsigned RemLatency = DependentLatency; - RemLatency = std::max(RemLatency, findMaxLatency(Available.elements())); - RemLatency = std::max(RemLatency, findMaxLatency(Pending.elements())); + unsigned RemLatency = CurrZone.getDependentLatency(); + RemLatency = std::max(RemLatency, + CurrZone.findMaxLatency(CurrZone.Available.elements())); + RemLatency = std::max(RemLatency, + CurrZone.findMaxLatency(CurrZone.Pending.elements())); // Compute the critical resource outside the zone. - unsigned OtherCritIdx; - unsigned OtherCount = OtherZone.getOtherResourceCount(OtherCritIdx); + unsigned OtherCritIdx = 0; + unsigned OtherCount = + OtherZone ? OtherZone->getOtherResourceCount(OtherCritIdx) : 0; bool OtherResLimited = false; if (SchedModel->hasInstrSchedModel()) { unsigned LFactor = SchedModel->getLatencyFactor(); OtherResLimited = (int)(OtherCount - (RemLatency * LFactor)) > (int)LFactor; } - if (!OtherResLimited && (RemLatency + CurrCycle > Rem->CriticalPath)) { - Policy.ReduceLatency |= true; - DEBUG(dbgs() << " " << Available.getName() << " RemainingLatency " - << RemLatency << " + " << CurrCycle << "c > CritPath " - << Rem->CriticalPath << "\n"); + // Schedule aggressively for latency in PostRA mode. We don't check for + // acyclic latency during PostRA, and highly out-of-order processors will + // skip PostRA scheduling. + if (!OtherResLimited) { + if (IsPostRA || (RemLatency + CurrZone.getCurrCycle() > Rem.CriticalPath)) { + Policy.ReduceLatency |= true; + DEBUG(dbgs() << " " << CurrZone.Available.getName() + << " RemainingLatency " << RemLatency << " + " + << CurrZone.getCurrCycle() << "c > CritPath " + << Rem.CriticalPath << "\n"); + } } // If the same resource is limiting inside and outside the zone, do nothing. - if (ZoneCritResIdx == OtherCritIdx) + if (CurrZone.getZoneCritResIdx() == OtherCritIdx) return; DEBUG( - if (IsResourceLimited) { - dbgs() << " " << Available.getName() << " ResourceLimited: " - << getResourceName(ZoneCritResIdx) << "\n"; + if (CurrZone.isResourceLimited()) { + dbgs() << " " << CurrZone.Available.getName() << " ResourceLimited: " + << SchedModel->getResourceName(CurrZone.getZoneCritResIdx()) + << "\n"; } if (OtherResLimited) - dbgs() << " RemainingLimit: " << getResourceName(OtherCritIdx) << "\n"; - if (!IsResourceLimited && !OtherResLimited) + dbgs() << " RemainingLimit: " + << SchedModel->getResourceName(OtherCritIdx) << "\n"; + if (!CurrZone.isResourceLimited() && !OtherResLimited) dbgs() << " Latency limited both directions.\n"); - if (IsResourceLimited && !Policy.ReduceResIdx) - Policy.ReduceResIdx = ZoneCritResIdx; + if (CurrZone.isResourceLimited() && !Policy.ReduceResIdx) + Policy.ReduceResIdx = CurrZone.getZoneCritResIdx(); if (OtherResLimited) Policy.DemandResIdx = OtherCritIdx; } -void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU, - unsigned ReadyCycle) { - if (ReadyCycle < MinReadyCycle) - MinReadyCycle = ReadyCycle; - - // Check for interlocks first. For the purpose of other heuristics, an - // instruction that cannot issue appears as if it's not in the ReadyQueue. - bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; - if ((!IsBuffered && ReadyCycle > CurrCycle) || checkHazard(SU)) - Pending.push(SU); - else - Available.push(SU); - - // Record this node as an immediate dependent of the scheduled node. - NextSUs.insert(SU); +#ifndef NDEBUG +const char *GenericSchedulerBase::getReasonStr( + GenericSchedulerBase::CandReason Reason) { + switch (Reason) { + case NoCand: return "NOCAND "; + case PhysRegCopy: return "PREG-COPY"; + case RegExcess: return "REG-EXCESS"; + case RegCritical: return "REG-CRIT "; + case Stall: return "STALL "; + case Cluster: return "CLUSTER "; + case Weak: return "WEAK "; + case RegMax: return "REG-MAX "; + case ResourceReduce: return "RES-REDUCE"; + case ResourceDemand: return "RES-DEMAND"; + case TopDepthReduce: return "TOP-DEPTH "; + case TopPathReduce: return "TOP-PATH "; + case BotHeightReduce:return "BOT-HEIGHT"; + case BotPathReduce: return "BOT-PATH "; + case NextDefUse: return "DEF-USE "; + case NodeOrder: return "ORDER "; + }; + llvm_unreachable("Unknown reason!"); } -/// Move the boundary of scheduled code by one cycle. -void ConvergingScheduler::SchedBoundary::bumpCycle(unsigned NextCycle) { - if (SchedModel->getMicroOpBufferSize() == 0) { - assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized"); - if (MinReadyCycle > NextCycle) - NextCycle = MinReadyCycle; +void GenericSchedulerBase::traceCandidate(const SchedCandidate &Cand) { + PressureChange P; + unsigned ResIdx = 0; + unsigned Latency = 0; + switch (Cand.Reason) { + default: + break; + case RegExcess: + P = Cand.RPDelta.Excess; + break; + case RegCritical: + P = Cand.RPDelta.CriticalMax; + break; + case RegMax: + P = Cand.RPDelta.CurrentMax; + break; + case ResourceReduce: + ResIdx = Cand.Policy.ReduceResIdx; + break; + case ResourceDemand: + ResIdx = Cand.Policy.DemandResIdx; + break; + case TopDepthReduce: + Latency = Cand.SU->getDepth(); + break; + case TopPathReduce: + Latency = Cand.SU->getHeight(); + break; + case BotHeightReduce: + Latency = Cand.SU->getHeight(); + break; + case BotPathReduce: + Latency = Cand.SU->getDepth(); + break; } - // Update the current micro-ops, which will issue in the next cycle. - unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle); - CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps; - - // Decrement DependentLatency based on the next cycle. - if ((NextCycle - CurrCycle) > DependentLatency) - DependentLatency = 0; + dbgs() << " SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason); + if (P.isValid()) + dbgs() << " " << TRI->getRegPressureSetName(P.getPSet()) + << ":" << P.getUnitInc() << " "; else - DependentLatency -= (NextCycle - CurrCycle); - - if (!HazardRec->isEnabled()) { - // Bypass HazardRec virtual calls. - CurrCycle = NextCycle; - } - else { - // Bypass getHazardType calls in case of long latency. - for (; CurrCycle != NextCycle; ++CurrCycle) { - if (isTop()) - HazardRec->AdvanceCycle(); - else - HazardRec->RecedeCycle(); - } - } - CheckPending = true; - unsigned LFactor = SchedModel->getLatencyFactor(); - IsResourceLimited = - (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) - > (int)LFactor; - - DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n'); -} - -void ConvergingScheduler::SchedBoundary::incExecutedResources(unsigned PIdx, - unsigned Count) { - ExecutedResCounts[PIdx] += Count; - if (ExecutedResCounts[PIdx] > MaxExecutedResCount) - MaxExecutedResCount = ExecutedResCounts[PIdx]; -} - -/// Add the given processor resource to this scheduled zone. -/// -/// \param Cycles indicates the number of consecutive (non-pipelined) cycles -/// during which this resource is consumed. -/// -/// \return the next cycle at which the instruction may execute without -/// oversubscribing resources. -unsigned ConvergingScheduler::SchedBoundary:: -countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle) { - unsigned Factor = SchedModel->getResourceFactor(PIdx); - unsigned Count = Factor * Cycles; - DEBUG(dbgs() << " " << getResourceName(PIdx) - << " +" << Cycles << "x" << Factor << "u\n"); - - // Update Executed resources counts. - incExecutedResources(PIdx, Count); - assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted"); - Rem->RemainingCounts[PIdx] -= Count; - - // Check if this resource exceeds the current critical resource. If so, it - // becomes the critical resource. - if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) { - ZoneCritResIdx = PIdx; - DEBUG(dbgs() << " *** Critical resource " - << getResourceName(PIdx) << ": " - << getResourceCount(PIdx) / SchedModel->getLatencyFactor() << "c\n"); - } - // TODO: We don't yet model reserved resources. It's not hard though. - return CurrCycle; + dbgs() << " "; + if (ResIdx) + dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " "; + else + dbgs() << " "; + if (Latency) + dbgs() << " " << Latency << " cycles "; + else + dbgs() << " "; + dbgs() << '\n'; } +#endif -/// Move the boundary of scheduled code by one SUnit. -void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) { - // Update the reservation table. - if (HazardRec->isEnabled()) { - if (!isTop() && SU->isCall) { - // Calls are scheduled with their preceding instructions. For bottom-up - // scheduling, clear the pipeline state before emitting. - HazardRec->Reset(); - } - HazardRec->EmitInstruction(SU); +/// Return true if this heuristic determines order. +static bool tryLess(int TryVal, int CandVal, + GenericSchedulerBase::SchedCandidate &TryCand, + GenericSchedulerBase::SchedCandidate &Cand, + GenericSchedulerBase::CandReason Reason) { + if (TryVal < CandVal) { + TryCand.Reason = Reason; + return true; } - const MCSchedClassDesc *SC = DAG->getSchedClass(SU); - unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr()); - CurrMOps += IncMOps; - // checkHazard prevents scheduling multiple instructions per cycle that exceed - // issue width. However, we commonly reach the maximum. In this case - // opportunistically bump the cycle to avoid uselessly checking everything in - // the readyQ. Furthermore, a single instruction may produce more than one - // cycle's worth of micro-ops. - // - // TODO: Also check if this SU must end a dispatch group. - unsigned NextCycle = CurrCycle; - if (CurrMOps >= SchedModel->getIssueWidth()) { - ++NextCycle; - DEBUG(dbgs() << " *** Max MOps " << CurrMOps - << " at cycle " << CurrCycle << '\n'); + if (TryVal > CandVal) { + if (Cand.Reason > Reason) + Cand.Reason = Reason; + return true; } - unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); - DEBUG(dbgs() << " Ready @" << ReadyCycle << "c\n"); + Cand.setRepeat(Reason); + return false; +} - switch (SchedModel->getMicroOpBufferSize()) { - case 0: - assert(ReadyCycle <= CurrCycle && "Broken PendingQueue"); - break; - case 1: - if (ReadyCycle > NextCycle) { - NextCycle = ReadyCycle; - DEBUG(dbgs() << " *** Stall until: " << ReadyCycle << "\n"); - } - break; - default: - // We don't currently model the OOO reorder buffer, so consider all - // scheduled MOps to be "retired". - break; +static bool tryGreater(int TryVal, int CandVal, + GenericSchedulerBase::SchedCandidate &TryCand, + GenericSchedulerBase::SchedCandidate &Cand, + GenericSchedulerBase::CandReason Reason) { + if (TryVal > CandVal) { + TryCand.Reason = Reason; + return true; } - RetiredMOps += IncMOps; - - // Update resource counts and critical resource. - if (SchedModel->hasInstrSchedModel()) { - unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor(); - assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted"); - Rem->RemIssueCount -= DecRemIssue; - if (ZoneCritResIdx) { - // Scale scheduled micro-ops for comparing with the critical resource. - unsigned ScaledMOps = - RetiredMOps * SchedModel->getMicroOpFactor(); + if (TryVal < CandVal) { + if (Cand.Reason > Reason) + Cand.Reason = Reason; + return true; + } + Cand.setRepeat(Reason); + return false; +} - // If scaled micro-ops are now more than the previous critical resource by - // a full cycle, then micro-ops issue becomes critical. - if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx)) - >= (int)SchedModel->getLatencyFactor()) { - ZoneCritResIdx = 0; - DEBUG(dbgs() << " *** Critical resource NumMicroOps: " - << ScaledMOps / SchedModel->getLatencyFactor() << "c\n"); - } - } - for (TargetSchedModel::ProcResIter - PI = SchedModel->getWriteProcResBegin(SC), - PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { - unsigned RCycle = - countResource(PI->ProcResourceIdx, PI->Cycles, ReadyCycle); - if (RCycle > NextCycle) - NextCycle = RCycle; +static bool tryLatency(GenericSchedulerBase::SchedCandidate &TryCand, + GenericSchedulerBase::SchedCandidate &Cand, + SchedBoundary &Zone) { + if (Zone.isTop()) { + if (Cand.SU->getDepth() > Zone.getScheduledLatency()) { + if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), + TryCand, Cand, GenericSchedulerBase::TopDepthReduce)) + return true; } - } - // Update ExpectedLatency and DependentLatency. - unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency; - unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency; - if (SU->getDepth() > TopLatency) { - TopLatency = SU->getDepth(); - DEBUG(dbgs() << " " << Available.getName() - << " TopLatency SU(" << SU->NodeNum << ") " << TopLatency << "c\n"); - } - if (SU->getHeight() > BotLatency) { - BotLatency = SU->getHeight(); - DEBUG(dbgs() << " " << Available.getName() - << " BotLatency SU(" << SU->NodeNum << ") " << BotLatency << "c\n"); - } - // If we stall for any reason, bump the cycle. - if (NextCycle > CurrCycle) { - bumpCycle(NextCycle); + if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), + TryCand, Cand, GenericSchedulerBase::TopPathReduce)) + return true; } else { - // After updating ZoneCritResIdx and ExpectedLatency, check if we're - // resource limited. If a stall occured, bumpCycle does this. - unsigned LFactor = SchedModel->getLatencyFactor(); - IsResourceLimited = - (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) - > (int)LFactor; + if (Cand.SU->getHeight() > Zone.getScheduledLatency()) { + if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), + TryCand, Cand, GenericSchedulerBase::BotHeightReduce)) + return true; + } + if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(), + TryCand, Cand, GenericSchedulerBase::BotPathReduce)) + return true; } - DEBUG(dumpScheduledState()); + return false; } -/// Release pending ready nodes in to the available queue. This makes them -/// visible to heuristics. -void ConvergingScheduler::SchedBoundary::releasePending() { - // If the available queue is empty, it is safe to reset MinReadyCycle. - if (Available.empty()) - MinReadyCycle = UINT_MAX; +static void tracePick(const GenericSchedulerBase::SchedCandidate &Cand, + bool IsTop) { + DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ") + << GenericSchedulerBase::getReasonStr(Cand.Reason) << '\n'); +} - // Check to see if any of the pending instructions are ready to issue. If - // so, add them to the available queue. - bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; - for (unsigned i = 0, e = Pending.size(); i != e; ++i) { - SUnit *SU = *(Pending.begin()+i); - unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle; +namespace { +/// GenericScheduler shrinks the unscheduled zone using heuristics to balance +/// the schedule. +class GenericScheduler : public GenericSchedulerBase { + ScheduleDAGMILive *DAG; - if (ReadyCycle < MinReadyCycle) - MinReadyCycle = ReadyCycle; + // State of the top and bottom scheduled instruction boundaries. + SchedBoundary Top; + SchedBoundary Bot; - if (!IsBuffered && ReadyCycle > CurrCycle) - continue; + MachineSchedPolicy RegionPolicy; +public: + GenericScheduler(const MachineSchedContext *C): + GenericSchedulerBase(C), DAG(nullptr), Top(SchedBoundary::TopQID, "TopQ"), + Bot(SchedBoundary::BotQID, "BotQ") {} - if (checkHazard(SU)) - continue; + void initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs) override; - Available.push(SU); - Pending.remove(Pending.begin()+i); - --i; --e; + bool shouldTrackPressure() const override { + return RegionPolicy.ShouldTrackPressure; } - DEBUG(if (!Pending.empty()) Pending.dump()); - CheckPending = false; -} -/// Remove SU from the ready set for this boundary. -void ConvergingScheduler::SchedBoundary::removeReady(SUnit *SU) { - if (Available.isInQueue(SU)) - Available.remove(Available.find(SU)); - else { - assert(Pending.isInQueue(SU) && "bad ready count"); - Pending.remove(Pending.find(SU)); + void initialize(ScheduleDAGMI *dag) override; + + SUnit *pickNode(bool &IsTopNode) override; + + void schedNode(SUnit *SU, bool IsTopNode) override; + + void releaseTopNode(SUnit *SU) override { + Top.releaseTopNode(SU); } -} -/// If this queue only has one ready candidate, return it. As a side effect, -/// defer any nodes that now hit a hazard, and advance the cycle until at least -/// one node is ready. If multiple instructions are ready, return NULL. -SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() { - if (CheckPending) - releasePending(); + void releaseBottomNode(SUnit *SU) override { + Bot.releaseBottomNode(SU); + } - if (CurrMOps > 0) { - // Defer any ready instrs that now have a hazard. - for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) { - if (checkHazard(*I)) { - Pending.push(*I); - I = Available.remove(I); - continue; - } - ++I; + void registerRoots() override; + +protected: + void checkAcyclicLatency(); + + void tryCandidate(SchedCandidate &Cand, + SchedCandidate &TryCand, + SchedBoundary &Zone, + const RegPressureTracker &RPTracker, + RegPressureTracker &TempTracker); + + SUnit *pickNodeBidirectional(bool &IsTopNode); + + void pickNodeFromQueue(SchedBoundary &Zone, + const RegPressureTracker &RPTracker, + SchedCandidate &Candidate); + + void reschedulePhysRegCopies(SUnit *SU, bool isTop); +}; +} // namespace + +void GenericScheduler::initialize(ScheduleDAGMI *dag) { + assert(dag->hasVRegLiveness() && + "(PreRA)GenericScheduler needs vreg liveness"); + DAG = static_cast(dag); + SchedModel = DAG->getSchedModel(); + TRI = DAG->TRI; + + Rem.init(DAG, SchedModel); + Top.init(DAG, SchedModel, &Rem); + Bot.init(DAG, SchedModel, &Rem); + + // Initialize resource counts. + + // Initialize the HazardRecognizers. If itineraries don't exist, are empty, or + // are disabled, then these HazardRecs will be disabled. + const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); + const TargetMachine &TM = DAG->MF.getTarget(); + if (!Top.HazardRec) { + Top.HazardRec = + TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); + } + if (!Bot.HazardRec) { + Bot.HazardRec = + TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); + } +} + +/// Initialize the per-region scheduling policy. +void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs) { + const TargetMachine &TM = Context->MF->getTarget(); + const TargetLowering *TLI = TM.getTargetLowering(); + + // Avoid setting up the register pressure tracker for small regions to save + // compile time. As a rough heuristic, only track pressure when the number of + // schedulable instructions exceeds half the integer register file. + RegionPolicy.ShouldTrackPressure = true; + for (unsigned VT = MVT::i32; VT > (unsigned)MVT::i1; --VT) { + MVT::SimpleValueType LegalIntVT = (MVT::SimpleValueType)VT; + if (TLI->isTypeLegal(LegalIntVT)) { + unsigned NIntRegs = Context->RegClassInfo->getNumAllocatableRegs( + TLI->getRegClassFor(LegalIntVT)); + RegionPolicy.ShouldTrackPressure = NumRegionInstrs > (NIntRegs / 2); } } - for (unsigned i = 0; Available.empty(); ++i) { - assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) && - "permanent hazard"); (void)i; - bumpCycle(CurrCycle + 1); - releasePending(); - } - if (Available.size() == 1) - return *Available.begin(); - return NULL; -} -#ifndef NDEBUG -// This is useful information to dump after bumpNode. -// Note that the Queue contents are more useful before pickNodeFromQueue. -void ConvergingScheduler::SchedBoundary::dumpScheduledState() { - unsigned ResFactor; - unsigned ResCount; - if (ZoneCritResIdx) { - ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx); - ResCount = getResourceCount(ZoneCritResIdx); + // For generic targets, we default to bottom-up, because it's simpler and more + // compile-time optimizations have been implemented in that direction. + RegionPolicy.OnlyBottomUp = true; + + // Allow the subtarget to override default policy. + const TargetSubtargetInfo &ST = TM.getSubtarget(); + ST.overrideSchedPolicy(RegionPolicy, Begin, End, NumRegionInstrs); + + // After subtarget overrides, apply command line options. + if (!EnableRegPressure) + RegionPolicy.ShouldTrackPressure = false; + + // Check -misched-topdown/bottomup can force or unforce scheduling direction. + // e.g. -misched-bottomup=false allows scheduling in both directions. + assert((!ForceTopDown || !ForceBottomUp) && + "-misched-topdown incompatible with -misched-bottomup"); + if (ForceBottomUp.getNumOccurrences() > 0) { + RegionPolicy.OnlyBottomUp = ForceBottomUp; + if (RegionPolicy.OnlyBottomUp) + RegionPolicy.OnlyTopDown = false; } - else { - ResFactor = SchedModel->getMicroOpFactor(); - ResCount = RetiredMOps * SchedModel->getMicroOpFactor(); + if (ForceTopDown.getNumOccurrences() > 0) { + RegionPolicy.OnlyTopDown = ForceTopDown; + if (RegionPolicy.OnlyTopDown) + RegionPolicy.OnlyBottomUp = false; } - unsigned LFactor = SchedModel->getLatencyFactor(); - dbgs() << Available.getName() << " @" << CurrCycle << "c\n" - << " Retired: " << RetiredMOps; - dbgs() << "\n Executed: " << getExecutedCount() / LFactor << "c"; - dbgs() << "\n Critical: " << ResCount / LFactor << "c, " - << ResCount / ResFactor << " " << getResourceName(ZoneCritResIdx) - << "\n ExpectedLatency: " << ExpectedLatency << "c\n" - << (IsResourceLimited ? " - Resource" : " - Latency") - << " limited.\n"; } -#endif -void ConvergingScheduler::SchedCandidate:: -initResourceDelta(const ScheduleDAGMI *DAG, - const TargetSchedModel *SchedModel) { - if (!Policy.ReduceResIdx && !Policy.DemandResIdx) +/// Set IsAcyclicLatencyLimited if the acyclic path is longer than the cyclic +/// critical path by more cycles than it takes to drain the instruction buffer. +/// We estimate an upper bounds on in-flight instructions as: +/// +/// CyclesPerIteration = max( CyclicPath, Loop-Resource-Height ) +/// InFlightIterations = AcyclicPath / CyclesPerIteration +/// InFlightResources = InFlightIterations * LoopResources +/// +/// TODO: Check execution resources in addition to IssueCount. +void GenericScheduler::checkAcyclicLatency() { + if (Rem.CyclicCritPath == 0 || Rem.CyclicCritPath >= Rem.CriticalPath) return; - const MCSchedClassDesc *SC = DAG->getSchedClass(SU); - for (TargetSchedModel::ProcResIter - PI = SchedModel->getWriteProcResBegin(SC), - PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { - if (PI->ProcResourceIdx == Policy.ReduceResIdx) - ResDelta.CritResources += PI->Cycles; - if (PI->ProcResourceIdx == Policy.DemandResIdx) - ResDelta.DemandedResources += PI->Cycles; - } + // Scaled number of cycles per loop iteration. + unsigned IterCount = + std::max(Rem.CyclicCritPath * SchedModel->getLatencyFactor(), + Rem.RemIssueCount); + // Scaled acyclic critical path. + unsigned AcyclicCount = Rem.CriticalPath * SchedModel->getLatencyFactor(); + // InFlightCount = (AcyclicPath / IterCycles) * InstrPerLoop + unsigned InFlightCount = + (AcyclicCount * Rem.RemIssueCount + IterCount-1) / IterCount; + unsigned BufferLimit = + SchedModel->getMicroOpBufferSize() * SchedModel->getMicroOpFactor(); + + Rem.IsAcyclicLatencyLimited = InFlightCount > BufferLimit; + + DEBUG(dbgs() << "IssueCycles=" + << Rem.RemIssueCount / SchedModel->getLatencyFactor() << "c " + << "IterCycles=" << IterCount / SchedModel->getLatencyFactor() + << "c NumIters=" << (AcyclicCount + IterCount-1) / IterCount + << " InFlight=" << InFlightCount / SchedModel->getMicroOpFactor() + << "m BufferLim=" << SchedModel->getMicroOpBufferSize() << "m\n"; + if (Rem.IsAcyclicLatencyLimited) + dbgs() << " ACYCLIC LATENCY LIMIT\n"); } +void GenericScheduler::registerRoots() { + Rem.CriticalPath = DAG->ExitSU.getDepth(); -/// Return true if this heuristic determines order. -static bool tryLess(int TryVal, int CandVal, - ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::CandReason Reason) { - if (TryVal < CandVal) { - TryCand.Reason = Reason; - return true; - } - if (TryVal > CandVal) { - if (Cand.Reason > Reason) - Cand.Reason = Reason; - return true; + // Some roots may not feed into ExitSU. Check all of them in case. + for (std::vector::const_iterator + I = Bot.Available.begin(), E = Bot.Available.end(); I != E; ++I) { + if ((*I)->getDepth() > Rem.CriticalPath) + Rem.CriticalPath = (*I)->getDepth(); } - Cand.setRepeat(Reason); - return false; -} + DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n'); -static bool tryGreater(int TryVal, int CandVal, - ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::CandReason Reason) { - if (TryVal > CandVal) { - TryCand.Reason = Reason; - return true; - } - if (TryVal < CandVal) { - if (Cand.Reason > Reason) - Cand.Reason = Reason; - return true; + if (EnableCyclicPath) { + Rem.CyclicCritPath = DAG->computeCyclicCriticalPath(); + checkAcyclicLatency(); } - Cand.setRepeat(Reason); - return false; } static bool tryPressure(const PressureChange &TryP, const PressureChange &CandP, - ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::CandReason Reason) { - if (TryP.isValid() && CandP.isValid()) { - // If both candidates affect the same set, go with the smallest increase. - if (TryP.getPSet() == CandP.getPSet()) { - return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand, - Reason); - } - // If one candidate decreases and the other increases, go with it. - if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand, - Reason)) { - return true; - } + GenericSchedulerBase::SchedCandidate &TryCand, + GenericSchedulerBase::SchedCandidate &Cand, + GenericSchedulerBase::CandReason Reason) { + int TryRank = TryP.getPSetOrMax(); + int CandRank = CandP.getPSetOrMax(); + // If both candidates affect the same set, go with the smallest increase. + if (TryRank == CandRank) { + return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand, + Reason); + } + // If one candidate decreases and the other increases, go with it. + // Invalid candidates have UnitInc==0. + if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand, + Reason)) { + return true; } - // If TryP has lower Rank, it has a higher priority. - int TryRank = TryP.getRank(); - int CandRank = CandP.getRank(); // If the candidates are decreasing pressure, reverse priority. if (TryP.getUnitInc() < 0) std::swap(TryRank, CandRank); @@ -2235,32 +2674,6 @@ static int biasPhysRegCopy(const SUnit *SU, bool isTop) { return 0; } -static bool tryLatency(ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::SchedBoundary &Zone) { - if (Zone.isTop()) { - if (Cand.SU->getDepth() > Zone.getScheduledLatency()) { - if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), - TryCand, Cand, ConvergingScheduler::TopDepthReduce)) - return true; - } - if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), - TryCand, Cand, ConvergingScheduler::TopPathReduce)) - return true; - } - else { - if (Cand.SU->getHeight() > Zone.getScheduledLatency()) { - if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), - TryCand, Cand, ConvergingScheduler::BotHeightReduce)) - return true; - } - if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(), - TryCand, Cand, ConvergingScheduler::BotPathReduce)) - return true; - } - return false; -} - /// Apply a set of heursitics to a new candidate. Heuristics are currently /// hierarchical. This may be more efficient than a graduated cost model because /// we don't need to evaluate all aspects of the model for each node in the @@ -2272,38 +2685,44 @@ static bool tryLatency(ConvergingScheduler::SchedCandidate &TryCand, /// \param Zone describes the scheduled zone that we are extending. /// \param RPTracker describes reg pressure within the scheduled zone. /// \param TempTracker is a scratch pressure tracker to reuse in queries. -void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, - SchedCandidate &TryCand, - SchedBoundary &Zone, - const RegPressureTracker &RPTracker, - RegPressureTracker &TempTracker) { - - // Always initialize TryCand's RPDelta. - if (Zone.isTop()) { - TempTracker.getMaxDownwardPressureDelta( - TryCand.SU->getInstr(), - TryCand.RPDelta, - DAG->getRegionCriticalPSets(), - DAG->getRegPressure().MaxSetPressure); - } - else { - if (VerifyScheduling) { - TempTracker.getMaxUpwardPressureDelta( +void GenericScheduler::tryCandidate(SchedCandidate &Cand, + SchedCandidate &TryCand, + SchedBoundary &Zone, + const RegPressureTracker &RPTracker, + RegPressureTracker &TempTracker) { + + if (DAG->isTrackingPressure()) { + // Always initialize TryCand's RPDelta. + if (Zone.isTop()) { + TempTracker.getMaxDownwardPressureDelta( TryCand.SU->getInstr(), - &DAG->getPressureDiff(TryCand.SU), TryCand.RPDelta, DAG->getRegionCriticalPSets(), DAG->getRegPressure().MaxSetPressure); } else { - RPTracker.getUpwardPressureDelta( - TryCand.SU->getInstr(), - DAG->getPressureDiff(TryCand.SU), - TryCand.RPDelta, - DAG->getRegionCriticalPSets(), - DAG->getRegPressure().MaxSetPressure); + if (VerifyScheduling) { + TempTracker.getMaxUpwardPressureDelta( + TryCand.SU->getInstr(), + &DAG->getPressureDiff(TryCand.SU), + TryCand.RPDelta, + DAG->getRegionCriticalPSets(), + DAG->getRegPressure().MaxSetPressure); + } + else { + RPTracker.getUpwardPressureDelta( + TryCand.SU->getInstr(), + DAG->getPressureDiff(TryCand.SU), + TryCand.RPDelta, + DAG->getRegionCriticalPSets(), + DAG->getRegPressure().MaxSetPressure); + } } } + DEBUG(if (TryCand.RPDelta.Excess.isValid()) + dbgs() << " SU(" << TryCand.SU->NodeNum << ") " + << TRI->getRegPressureSetName(TryCand.RPDelta.Excess.getPSet()) + << ":" << TryCand.RPDelta.Excess.getUnitInc() << "\n"); // Initialize the candidate if needed. if (!Cand.isValid()) { @@ -2318,17 +2737,27 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, // Avoid exceeding the target's limit. If signed PSetID is negative, it is // invalid; convert it to INT_MAX to give it lowest priority. - if (tryPressure(TryCand.RPDelta.Excess, Cand.RPDelta.Excess, TryCand, Cand, - RegExcess)) + if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess, + Cand.RPDelta.Excess, + TryCand, Cand, RegExcess)) + return; + + // Avoid increasing the max critical pressure in the scheduled region. + if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CriticalMax, + Cand.RPDelta.CriticalMax, + TryCand, Cand, RegCritical)) return; // For loops that are acyclic path limited, aggressively schedule for latency. - if (Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, Zone)) + // This can result in very long dependence chains scheduled in sequence, so + // once every cycle (when CurrMOps == 0), switch to normal heuristics. + if (Rem.IsAcyclicLatencyLimited && !Zone.getCurrMOps() + && tryLatency(TryCand, Cand, Zone)) return; - // Avoid increasing the max critical pressure in the scheduled region. - if (tryPressure(TryCand.RPDelta.CriticalMax, Cand.RPDelta.CriticalMax, - TryCand, Cand, RegCritical)) + // Prioritize instructions that read unbuffered resources by stall cycles. + if (tryLess(Zone.getLatencyStallCycles(TryCand.SU), + Zone.getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall)) return; // Keep clustered nodes together to encourage downstream peephole @@ -2350,8 +2779,9 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, return; } // Avoid increasing the max pressure of the entire region. - if (tryPressure(TryCand.RPDelta.CurrentMax, Cand.RPDelta.CurrentMax, - TryCand, Cand, RegMax)) + if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CurrentMax, + Cand.RPDelta.CurrentMax, + TryCand, Cand, RegMax)) return; // Avoid critical resource consumption and balance the schedule. @@ -2374,7 +2804,7 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, // Prefer immediate defs/users of the last scheduled instruction. This is a // local pressure avoidance strategy that also makes the machine code // readable. - if (tryGreater(Zone.NextSUs.count(TryCand.SU), Zone.NextSUs.count(Cand.SU), + if (tryGreater(Zone.isNextSU(TryCand.SU), Zone.isNextSU(Cand.SU), TryCand, Cand, NextDefUse)) return; @@ -2385,90 +2815,14 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, } } -#ifndef NDEBUG -const char *ConvergingScheduler::getReasonStr( - ConvergingScheduler::CandReason Reason) { - switch (Reason) { - case NoCand: return "NOCAND "; - case PhysRegCopy: return "PREG-COPY"; - case RegExcess: return "REG-EXCESS"; - case RegCritical: return "REG-CRIT "; - case Cluster: return "CLUSTER "; - case Weak: return "WEAK "; - case RegMax: return "REG-MAX "; - case ResourceReduce: return "RES-REDUCE"; - case ResourceDemand: return "RES-DEMAND"; - case TopDepthReduce: return "TOP-DEPTH "; - case TopPathReduce: return "TOP-PATH "; - case BotHeightReduce:return "BOT-HEIGHT"; - case BotPathReduce: return "BOT-PATH "; - case NextDefUse: return "DEF-USE "; - case NodeOrder: return "ORDER "; - }; - llvm_unreachable("Unknown reason!"); -} - -void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) { - PressureChange P; - unsigned ResIdx = 0; - unsigned Latency = 0; - switch (Cand.Reason) { - default: - break; - case RegExcess: - P = Cand.RPDelta.Excess; - break; - case RegCritical: - P = Cand.RPDelta.CriticalMax; - break; - case RegMax: - P = Cand.RPDelta.CurrentMax; - break; - case ResourceReduce: - ResIdx = Cand.Policy.ReduceResIdx; - break; - case ResourceDemand: - ResIdx = Cand.Policy.DemandResIdx; - break; - case TopDepthReduce: - Latency = Cand.SU->getDepth(); - break; - case TopPathReduce: - Latency = Cand.SU->getHeight(); - break; - case BotHeightReduce: - Latency = Cand.SU->getHeight(); - break; - case BotPathReduce: - Latency = Cand.SU->getDepth(); - break; - } - dbgs() << " SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason); - if (P.isValid()) - dbgs() << " " << TRI->getRegPressureSetName(P.getPSet()) - << ":" << P.getUnitInc() << " "; - else - dbgs() << " "; - if (ResIdx) - dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " "; - else - dbgs() << " "; - if (Latency) - dbgs() << " " << Latency << " cycles "; - else - dbgs() << " "; - dbgs() << '\n'; -} -#endif - -/// Pick the best candidate from the top queue. +/// Pick the best candidate from the queue. /// /// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during /// DAG building. To adjust for the current scheduling location we need to /// maintain the number of vreg uses remaining to be top-scheduled. -void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone, - const RegPressureTracker &RPTracker, - SchedCandidate &Cand) { +void GenericScheduler::pickNodeFromQueue(SchedBoundary &Zone, + const RegPressureTracker &RPTracker, + SchedCandidate &Cand) { ReadyQueue &Q = Zone.Available; DEBUG(Q.dump()); @@ -2491,14 +2845,8 @@ void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone, } } -static void tracePick(const ConvergingScheduler::SchedCandidate &Cand, - bool IsTop) { - DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ") - << ConvergingScheduler::getReasonStr(Cand.Reason) << '\n'); -} - /// Pick the best candidate node from either the top or bottom queue. -SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { +SUnit *GenericScheduler::pickNodeBidirectional(bool &IsTopNode) { // Schedule as far as possible in the direction of no choice. This is most // efficient, but also provides the best heuristics for CriticalPSets. if (SUnit *SU = Bot.pickOnlyChoice()) { @@ -2514,8 +2862,12 @@ SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { CandPolicy NoPolicy; SchedCandidate BotCand(NoPolicy); SchedCandidate TopCand(NoPolicy); - Bot.setPolicy(BotCand.Policy, Top); - Top.setPolicy(TopCand.Policy, Bot); + // Set the bottom-up policy based on the state of the current bottom zone and + // the instructions outside the zone, including the top zone. + setPolicy(BotCand.Policy, /*IsPostRA=*/false, Bot, &Top); + // Set the top-down policy based on the state of the current top zone and + // the instructions outside the zone, including the bottom zone. + setPolicy(TopCand.Policy, /*IsPostRA=*/false, Top, &Bot); // Prefer bottom scheduling when heuristics are silent. pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand); @@ -2553,32 +2905,34 @@ SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { } /// Pick the best node to balance the schedule. Implements MachineSchedStrategy. -SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) { +SUnit *GenericScheduler::pickNode(bool &IsTopNode) { if (DAG->top() == DAG->bottom()) { assert(Top.Available.empty() && Top.Pending.empty() && Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage"); - return NULL; + return nullptr; } SUnit *SU; do { - if (ForceTopDown) { + if (RegionPolicy.OnlyTopDown) { SU = Top.pickOnlyChoice(); if (!SU) { CandPolicy NoPolicy; SchedCandidate TopCand(NoPolicy); pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand); - assert(TopCand.Reason != NoCand && "failed to find the first candidate"); + assert(TopCand.Reason != NoCand && "failed to find a candidate"); + tracePick(TopCand, true); SU = TopCand.SU; } IsTopNode = true; } - else if (ForceBottomUp) { + else if (RegionPolicy.OnlyBottomUp) { SU = Bot.pickOnlyChoice(); if (!SU) { CandPolicy NoPolicy; SchedCandidate BotCand(NoPolicy); pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand); - assert(BotCand.Reason != NoCand && "failed to find the first candidate"); + assert(BotCand.Reason != NoCand && "failed to find a candidate"); + tracePick(BotCand, false); SU = BotCand.SU; } IsTopNode = false; @@ -2597,7 +2951,7 @@ SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) { return SU; } -void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { +void GenericScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { MachineBasicBlock::iterator InsertPos = SU->getInstr(); if (!isTop) @@ -2623,20 +2977,21 @@ void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { } /// Update the scheduler's state after scheduling a node. This is the same node -/// that was just returned by pickNode(). However, ScheduleDAGMI needs to update -/// it's state based on the current cycle before MachineSchedStrategy does. +/// that was just returned by pickNode(). However, ScheduleDAGMILive needs to +/// update it's state based on the current cycle before MachineSchedStrategy +/// does. /// /// FIXME: Eventually, we may bundle physreg copies rather than rescheduling /// them here. See comments in biasPhysRegCopy. -void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) { +void GenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { if (IsTopNode) { - SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.CurrCycle); + SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle()); Top.bumpNode(SU); if (SU->hasPhysRegUses) reschedulePhysRegCopies(SU, true); } else { - SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.CurrCycle); + SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.getCurrCycle()); Bot.bumpNode(SU); if (SU->hasPhysRegDefs) reschedulePhysRegCopies(SU, false); @@ -2645,25 +3000,205 @@ void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) { /// Create the standard converging machine scheduler. This will be used as the /// default scheduler if the target does not set a default. -static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C) { - assert((!ForceTopDown || !ForceBottomUp) && - "-misched-topdown incompatible with -misched-bottomup"); - ScheduleDAGMI *DAG = new ScheduleDAGMI(C, new ConvergingScheduler()); +static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C) { + ScheduleDAGMILive *DAG = new ScheduleDAGMILive(C, make_unique(C)); // Register DAG post-processors. // // FIXME: extend the mutation API to allow earlier mutations to instantiate // data and pass it to later mutations. Have a single mutation that gathers // the interesting nodes in one pass. - DAG->addMutation(new CopyConstrain(DAG->TII, DAG->TRI)); - if (EnableLoadCluster) - DAG->addMutation(new LoadClusterMutation(DAG->TII, DAG->TRI)); + DAG->addMutation(make_unique(DAG->TII, DAG->TRI)); + if (EnableLoadCluster && DAG->TII->enableClusterLoads()) + DAG->addMutation(make_unique(DAG->TII, DAG->TRI)); if (EnableMacroFusion) - DAG->addMutation(new MacroFusion(DAG->TII)); + DAG->addMutation(make_unique(DAG->TII)); return DAG; } + static MachineSchedRegistry -ConvergingSchedRegistry("converge", "Standard converging scheduler.", - createConvergingSched); +GenericSchedRegistry("converge", "Standard converging scheduler.", + createGenericSchedLive); + +//===----------------------------------------------------------------------===// +// PostGenericScheduler - Generic PostRA implementation of MachineSchedStrategy. +//===----------------------------------------------------------------------===// + +namespace { +/// PostGenericScheduler - Interface to the scheduling algorithm used by +/// ScheduleDAGMI. +/// +/// Callbacks from ScheduleDAGMI: +/// initPolicy -> initialize(DAG) -> registerRoots -> pickNode ... +class PostGenericScheduler : public GenericSchedulerBase { + ScheduleDAGMI *DAG; + SchedBoundary Top; + SmallVector BotRoots; +public: + PostGenericScheduler(const MachineSchedContext *C): + GenericSchedulerBase(C), Top(SchedBoundary::TopQID, "TopQ") {} + + virtual ~PostGenericScheduler() {} + + void initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs) override { + /* no configurable policy */ + }; + + /// PostRA scheduling does not track pressure. + bool shouldTrackPressure() const override { return false; } + + void initialize(ScheduleDAGMI *Dag) override { + DAG = Dag; + SchedModel = DAG->getSchedModel(); + TRI = DAG->TRI; + + Rem.init(DAG, SchedModel); + Top.init(DAG, SchedModel, &Rem); + BotRoots.clear(); + + // Initialize the HazardRecognizers. If itineraries don't exist, are empty, + // or are disabled, then these HazardRecs will be disabled. + const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); + const TargetMachine &TM = DAG->MF.getTarget(); + if (!Top.HazardRec) { + Top.HazardRec = + TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); + } + } + + void registerRoots() override; + + SUnit *pickNode(bool &IsTopNode) override; + + void scheduleTree(unsigned SubtreeID) override { + llvm_unreachable("PostRA scheduler does not support subtree analysis."); + } + + void schedNode(SUnit *SU, bool IsTopNode) override; + + void releaseTopNode(SUnit *SU) override { + Top.releaseTopNode(SU); + } + + // Only called for roots. + void releaseBottomNode(SUnit *SU) override { + BotRoots.push_back(SU); + } + +protected: + void tryCandidate(SchedCandidate &Cand, SchedCandidate &TryCand); + + void pickNodeFromQueue(SchedCandidate &Cand); +}; +} // namespace + +void PostGenericScheduler::registerRoots() { + Rem.CriticalPath = DAG->ExitSU.getDepth(); + + // Some roots may not feed into ExitSU. Check all of them in case. + for (SmallVectorImpl::const_iterator + I = BotRoots.begin(), E = BotRoots.end(); I != E; ++I) { + if ((*I)->getDepth() > Rem.CriticalPath) + Rem.CriticalPath = (*I)->getDepth(); + } + DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n'); +} + +/// Apply a set of heursitics to a new candidate for PostRA scheduling. +/// +/// \param Cand provides the policy and current best candidate. +/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized. +void PostGenericScheduler::tryCandidate(SchedCandidate &Cand, + SchedCandidate &TryCand) { + + // Initialize the candidate if needed. + if (!Cand.isValid()) { + TryCand.Reason = NodeOrder; + return; + } + + // Prioritize instructions that read unbuffered resources by stall cycles. + if (tryLess(Top.getLatencyStallCycles(TryCand.SU), + Top.getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall)) + return; + + // Avoid critical resource consumption and balance the schedule. + if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources, + TryCand, Cand, ResourceReduce)) + return; + if (tryGreater(TryCand.ResDelta.DemandedResources, + Cand.ResDelta.DemandedResources, + TryCand, Cand, ResourceDemand)) + return; + + // Avoid serializing long latency dependence chains. + if (Cand.Policy.ReduceLatency && tryLatency(TryCand, Cand, Top)) { + return; + } + + // Fall through to original instruction order. + if (TryCand.SU->NodeNum < Cand.SU->NodeNum) + TryCand.Reason = NodeOrder; +} + +void PostGenericScheduler::pickNodeFromQueue(SchedCandidate &Cand) { + ReadyQueue &Q = Top.Available; + + DEBUG(Q.dump()); + + for (ReadyQueue::iterator I = Q.begin(), E = Q.end(); I != E; ++I) { + SchedCandidate TryCand(Cand.Policy); + TryCand.SU = *I; + TryCand.initResourceDelta(DAG, SchedModel); + tryCandidate(Cand, TryCand); + if (TryCand.Reason != NoCand) { + Cand.setBest(TryCand); + DEBUG(traceCandidate(Cand)); + } + } +} + +/// Pick the next node to schedule. +SUnit *PostGenericScheduler::pickNode(bool &IsTopNode) { + if (DAG->top() == DAG->bottom()) { + assert(Top.Available.empty() && Top.Pending.empty() && "ReadyQ garbage"); + return nullptr; + } + SUnit *SU; + do { + SU = Top.pickOnlyChoice(); + if (!SU) { + CandPolicy NoPolicy; + SchedCandidate TopCand(NoPolicy); + // Set the top-down policy based on the state of the current top zone and + // the instructions outside the zone, including the bottom zone. + setPolicy(TopCand.Policy, /*IsPostRA=*/true, Top, nullptr); + pickNodeFromQueue(TopCand); + assert(TopCand.Reason != NoCand && "failed to find a candidate"); + tracePick(TopCand, true); + SU = TopCand.SU; + } + } while (SU->isScheduled); + + IsTopNode = true; + Top.removeReady(SU); + + DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " << *SU->getInstr()); + return SU; +} + +/// Called after ScheduleDAGMI has scheduled an instruction and updated +/// scheduled/remaining flags in the DAG nodes. +void PostGenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { + SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle()); + Top.bumpNode(SU); +} + +/// Create a generic scheduler with no vreg liveness or DAG mutation passes. +static ScheduleDAGInstrs *createGenericSchedPostRA(MachineSchedContext *C) { + return new ScheduleDAGMI(C, make_unique(C), /*IsPostRA=*/true); +} //===----------------------------------------------------------------------===// // ILP Scheduler. Currently for experimental analysis of heuristics. @@ -2676,7 +3211,8 @@ struct ILPOrder { const BitVector *ScheduledTrees; bool MaximizeILP; - ILPOrder(bool MaxILP): DFSResult(0), ScheduledTrees(0), MaximizeILP(MaxILP) {} + ILPOrder(bool MaxILP) + : DFSResult(nullptr), ScheduledTrees(nullptr), MaximizeILP(MaxILP) {} /// \brief Apply a less-than relation on node priority. /// @@ -2705,31 +3241,23 @@ struct ILPOrder { /// \brief Schedule based on the ILP metric. class ILPScheduler : public MachineSchedStrategy { - /// In case all subtrees are eventually connected to a common root through - /// data dependence (e.g. reduction), place an upper limit on their size. - /// - /// FIXME: A subtree limit is generally good, but in the situation commented - /// above, where multiple similar subtrees feed a common root, we should - /// only split at a point where the resulting subtrees will be balanced. - /// (a motivating test case must be found). - static const unsigned SubtreeLimit = 16; - - ScheduleDAGMI *DAG; + ScheduleDAGMILive *DAG; ILPOrder Cmp; std::vector ReadyQ; public: - ILPScheduler(bool MaximizeILP): DAG(0), Cmp(MaximizeILP) {} + ILPScheduler(bool MaximizeILP): DAG(nullptr), Cmp(MaximizeILP) {} - virtual void initialize(ScheduleDAGMI *dag) { - DAG = dag; + void initialize(ScheduleDAGMI *dag) override { + assert(dag->hasVRegLiveness() && "ILPScheduler needs vreg liveness"); + DAG = static_cast(dag); DAG->computeDFSResult(); Cmp.DFSResult = DAG->getDFSResult(); Cmp.ScheduledTrees = &DAG->getScheduledTrees(); ReadyQ.clear(); } - virtual void registerRoots() { + void registerRoots() override { // Restore the heap in ReadyQ with the updated DFS results. std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); } @@ -2738,8 +3266,8 @@ public: /// ----------------------------------------- /// Callback to select the highest priority node from the ready Q. - virtual SUnit *pickNode(bool &IsTopNode) { - if (ReadyQ.empty()) return NULL; + SUnit *pickNode(bool &IsTopNode) override { + if (ReadyQ.empty()) return nullptr; std::pop_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); SUnit *SU = ReadyQ.back(); ReadyQ.pop_back(); @@ -2754,19 +3282,19 @@ public: } /// \brief Scheduler callback to notify that a new subtree is scheduled. - virtual void scheduleTree(unsigned SubtreeID) { + void scheduleTree(unsigned SubtreeID) override { std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); } /// Callback after a node is scheduled. Mark a newly scheduled tree, notify /// DFSResults, and resort the priority Q. - virtual void schedNode(SUnit *SU, bool IsTopNode) { + void schedNode(SUnit *SU, bool IsTopNode) override { assert(!IsTopNode && "SchedDFSResult needs bottom-up"); } - virtual void releaseTopNode(SUnit *) { /*only called for top roots*/ } + void releaseTopNode(SUnit *) override { /*only called for top roots*/ } - virtual void releaseBottomNode(SUnit *SU) { + void releaseBottomNode(SUnit *SU) override { ReadyQ.push_back(SU); std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); } @@ -2774,10 +3302,10 @@ public: } // namespace static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) { - return new ScheduleDAGMI(C, new ILPScheduler(true)); + return new ScheduleDAGMILive(C, make_unique(true)); } static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) { - return new ScheduleDAGMI(C, new ILPScheduler(false)); + return new ScheduleDAGMILive(C, make_unique(false)); } static MachineSchedRegistry ILPMaxRegistry( "ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler); @@ -2819,7 +3347,7 @@ public: InstructionShuffler(bool alternate, bool topdown) : IsAlternating(alternate), IsTopDown(topdown) {} - virtual void initialize(ScheduleDAGMI *) { + void initialize(ScheduleDAGMI*) override { TopQ.clear(); BottomQ.clear(); } @@ -2827,11 +3355,11 @@ public: /// Implement MachineSchedStrategy interface. /// ----------------------------------------- - virtual SUnit *pickNode(bool &IsTopNode) { + SUnit *pickNode(bool &IsTopNode) override { SUnit *SU; if (IsTopDown) { do { - if (TopQ.empty()) return NULL; + if (TopQ.empty()) return nullptr; SU = TopQ.top(); TopQ.pop(); } while (SU->isScheduled); @@ -2839,7 +3367,7 @@ public: } else { do { - if (BottomQ.empty()) return NULL; + if (BottomQ.empty()) return nullptr; SU = BottomQ.top(); BottomQ.pop(); } while (SU->isScheduled); @@ -2850,12 +3378,12 @@ public: return SU; } - virtual void schedNode(SUnit *SU, bool IsTopNode) {} + void schedNode(SUnit *SU, bool IsTopNode) override {} - virtual void releaseTopNode(SUnit *SU) { + void releaseTopNode(SUnit *SU) override { TopQ.push(SU); } - virtual void releaseBottomNode(SUnit *SU) { + void releaseBottomNode(SUnit *SU) override { BottomQ.push(SU); } }; @@ -2866,7 +3394,7 @@ static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) { bool TopDown = !ForceBottomUp; assert((TopDown || !ForceTopDown) && "-misched-topdown incompatible with -misched-bottomup"); - return new ScheduleDAGMI(C, new InstructionShuffler(Alternate, TopDown)); + return new ScheduleDAGMILive(C, make_unique(Alternate, TopDown)); } static MachineSchedRegistry ShufflerRegistry( "shuffle", "Shuffle machine instructions alternating directions", @@ -2874,7 +3402,7 @@ static MachineSchedRegistry ShufflerRegistry( #endif // !NDEBUG //===----------------------------------------------------------------------===// -// GraphWriter support for ScheduleDAGMI. +// GraphWriter support for ScheduleDAGMILive. //===----------------------------------------------------------------------===// #ifndef NDEBUG @@ -2897,7 +3425,7 @@ struct DOTGraphTraits : public DefaultDOTGraphTraits { } static bool isNodeHidden(const SUnit *Node) { - return (Node->NumPreds > 10 || Node->NumSuccs > 10); + return (Node->Preds.size() > 10 || Node->Succs.size() > 10); } static bool hasNodeAddressLabel(const SUnit *Node, @@ -2920,18 +3448,23 @@ struct DOTGraphTraits : public DefaultDOTGraphTraits { static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) { std::string Str; raw_string_ostream SS(Str); - SS << "SU(" << SU->NodeNum << ')'; + const ScheduleDAGMI *DAG = static_cast(G); + const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? + static_cast(G)->getDFSResult() : nullptr; + SS << "SU:" << SU->NodeNum; + if (DFS) + SS << " I:" << DFS->getNumInstrs(SU); return SS.str(); } static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) { return G->getGraphNodeLabel(SU); } - static std::string getNodeAttributes(const SUnit *N, - const ScheduleDAG *Graph) { + static std::string getNodeAttributes(const SUnit *N, const ScheduleDAG *G) { std::string Str("shape=Mrecord"); - const SchedDFSResult *DFS = - static_cast(Graph)->getDFSResult(); + const ScheduleDAGMI *DAG = static_cast(G); + const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? + static_cast(G)->getDFSResult() : nullptr; if (DFS) { Str += ",style=filled,fillcolor=\"#"; Str += DOT::getColorString(DFS->getSubtreeID(N));