diff options
Diffstat (limited to 'contrib/llvm/lib/CodeGen/MachineScheduler.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/MachineScheduler.cpp | 3323 |
1 files changed, 3323 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/MachineScheduler.cpp b/contrib/llvm/lib/CodeGen/MachineScheduler.cpp new file mode 100644 index 000000000000..a48e54caf3fe --- /dev/null +++ b/contrib/llvm/lib/CodeGen/MachineScheduler.cpp @@ -0,0 +1,3323 @@ +//===- MachineScheduler.cpp - Machine Instruction Scheduler ---------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// MachineScheduler schedules machine instructions after phi elimination. It +// preserves LiveIntervals so it can be invoked before register allocation. +// +//===----------------------------------------------------------------------===// + +#include "llvm/CodeGen/MachineScheduler.h" +#include "llvm/ADT/PriorityQueue.h" +#include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/MachineDominators.h" +#include "llvm/CodeGen/MachineLoopInfo.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/Passes.h" +#include "llvm/CodeGen/RegisterClassInfo.h" +#include "llvm/CodeGen/ScheduleDFS.h" +#include "llvm/CodeGen/ScheduleHazardRecognizer.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorHandling.h" +#include "llvm/Support/GraphWriter.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetInstrInfo.h" +#include <queue> + +using namespace llvm; + +#define DEBUG_TYPE "misched" + +namespace llvm { +cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden, + cl::desc("Force top-down list scheduling")); +cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden, + cl::desc("Force bottom-up list scheduling")); +cl::opt<bool> +DumpCriticalPathLength("misched-dcpl", cl::Hidden, + cl::desc("Print critical path length to stdout")); +} + +#ifndef NDEBUG +static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden, + cl::desc("Pop up a window to show MISched dags after they are processed")); + +static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden, + cl::desc("Stop scheduling after N instructions"), cl::init(~0U)); + +static cl::opt<std::string> SchedOnlyFunc("misched-only-func", cl::Hidden, + cl::desc("Only schedule this function")); +static cl::opt<unsigned> SchedOnlyBlock("misched-only-block", cl::Hidden, + cl::desc("Only schedule this MBB#")); +#else +static bool ViewMISchedDAGs = false; +#endif // NDEBUG + +static cl::opt<bool> EnableRegPressure("misched-regpressure", cl::Hidden, + cl::desc("Enable register pressure scheduling."), cl::init(true)); + +static cl::opt<bool> EnableCyclicPath("misched-cyclicpath", cl::Hidden, + cl::desc("Enable cyclic critical path analysis."), cl::init(true)); + +static cl::opt<bool> EnableLoadCluster("misched-cluster", cl::Hidden, + cl::desc("Enable load clustering."), cl::init(true)); + +// Experimental heuristics +static cl::opt<bool> EnableMacroFusion("misched-fusion", cl::Hidden, + cl::desc("Enable scheduling for macro fusion."), cl::init(true)); + +static cl::opt<bool> VerifyScheduling("verify-misched", cl::Hidden, + cl::desc("Verify machine instrs before and after machine scheduling")); + +// 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(nullptr), MLI(nullptr), MDT(nullptr), PassConfig(nullptr), AA(nullptr), LIS(nullptr) { + RegClassInfo = new RegisterClassInfo(); +} + +MachineSchedContext::~MachineSchedContext() { + delete RegClassInfo; +} + +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 MachineSchedulerBase { +public: + MachineScheduler(); + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + bool runOnMachineFunction(MachineFunction&) override; + + static char ID; // Class identification, replacement for typeinfo + +protected: + ScheduleDAGInstrs *createMachineScheduler(); +}; + +/// PostMachineScheduler runs after shortly before code emission. +class PostMachineScheduler : public MachineSchedulerBase { +public: + PostMachineScheduler(); + + void getAnalysisUsage(AnalysisUsage &AU) const override; + + bool runOnMachineFunction(MachineFunction&) override; + + static char ID; // Class identification, replacement for typeinfo + +protected: + ScheduleDAGInstrs *createPostMachineScheduler(); +}; +} // namespace + +char MachineScheduler::ID = 0; + +char &llvm::MachineSchedulerID = MachineScheduler::ID; + +INITIALIZE_PASS_BEGIN(MachineScheduler, "machine-scheduler", + "Machine Instruction Scheduler", false, false) +INITIALIZE_AG_DEPENDENCY(AliasAnalysis) +INITIALIZE_PASS_DEPENDENCY(SlotIndexes) +INITIALIZE_PASS_DEPENDENCY(LiveIntervals) +INITIALIZE_PASS_END(MachineScheduler, "machine-scheduler", + "Machine Instruction Scheduler", false, false) + +MachineScheduler::MachineScheduler() +: MachineSchedulerBase(ID) { + initializeMachineSchedulerPass(*PassRegistry::getPassRegistry()); +} + +void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesCFG(); + AU.addRequiredID(MachineDominatorsID); + AU.addRequired<MachineLoopInfo>(); + AU.addRequired<AliasAnalysis>(); + AU.addRequired<TargetPassConfig>(); + AU.addRequired<SlotIndexes>(); + AU.addPreserved<SlotIndexes>(); + AU.addRequired<LiveIntervals>(); + AU.addPreserved<LiveIntervals>(); + 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<MachineLoopInfo>(); + AU.addRequired<TargetPassConfig>(); + 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 nullptr; +} + +/// MachineSchedOpt allows command line selection of the scheduler. +static cl::opt<MachineSchedRegistry::ScheduleDAGCtor, false, + RegisterPassParser<MachineSchedRegistry> > +MachineSchedOpt("misched", + cl::init(&useDefaultMachineSched), cl::Hidden, + cl::desc("Machine instruction scheduler to use")); + +static MachineSchedRegistry +DefaultSchedRegistry("default", "Use the target's default scheduler choice.", + useDefaultMachineSched); + +static cl::opt<bool> EnableMachineSched( + "enable-misched", + cl::desc("Enable the machine instruction scheduling pass."), cl::init(true), + cl::Hidden); + +/// Forward declare the standard machine scheduler. This will be used as the +/// default scheduler if the target does not set a default. +static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C); +static ScheduleDAGInstrs *createGenericSchedPostRA(MachineSchedContext *C); + +/// Decrement this iterator until reaching the top or a non-debug instr. +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()) + break; + } + return I; +} + +/// Non-const version. +static MachineBasicBlock::iterator +priorNonDebug(MachineBasicBlock::iterator I, + MachineBasicBlock::const_iterator Beg) { + return const_cast<MachineInstr*>( + &*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::const_iterator +nextIfDebug(MachineBasicBlock::const_iterator I, + MachineBasicBlock::const_iterator End) { + for(; I != End; ++I) { + if (!I->isDebugValue()) + break; + } + 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<MachineInstr*>( + &*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 +/// and visit them bottom-up. Visiting regions bottom-up is not required, but is +/// consistent with the DAG builder, which traverses the interior of the +/// scheduling regions bottom-up. +/// +/// This design avoids exposing scheduling boundaries to the DAG builder, +/// simplifying the DAG builder's support for "special" target instructions. +/// At the same time the design allows target schedulers to operate across +/// scheduling boundaries, for example to bundle the boudary instructions +/// without reordering them. This creates complexity, because the target +/// scheduler must update the RegionBegin and RegionEnd positions cached by +/// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler +/// design would be to split blocks at scheduling boundaries, but LLVM has a +/// general bias against block splitting purely for implementation simplicity. +bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { + if (EnableMachineSched.getNumOccurrences()) { + if (!EnableMachineSched) + return false; + } else if (!mf.getSubtarget().enableMachineScheduler()) + return false; + + DEBUG(dbgs() << "Before MISsched:\n"; mf.print(dbgs())); + + // Initialize the context of the pass. + MF = &mf; + MLI = &getAnalysis<MachineLoopInfo>(); + MDT = &getAnalysis<MachineDominatorTree>(); + PassConfig = &getAnalysis<TargetPassConfig>(); + AA = &getAnalysis<AliasAnalysis>(); + + LIS = &getAnalysis<LiveIntervals>(); + + if (VerifyScheduling) { + DEBUG(LIS->dump()); + MF->verify(this, "Before machine scheduling."); + } + RegClassInfo->runOnMachineFunction(*MF); + + // Instantiate the selected scheduler for this target, function, and + // optimization level. + std::unique_ptr<ScheduleDAGInstrs> 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; + + if (!mf.getSubtarget().enablePostRAScheduler()) { + DEBUG(dbgs() << "Subtarget disables post-MI-sched.\n"); + return false; + } + DEBUG(dbgs() << "Before post-MI-sched:\n"; mf.print(dbgs())); + + // Initialize the context of the pass. + MF = &mf; + PassConfig = &getAnalysis<TargetPassConfig>(); + + if (VerifyScheduling) + MF->verify(this, "Before post machine scheduling."); + + // Instantiate the selected scheduler for this target, function, and + // optimization level. + std::unique_ptr<ScheduleDAGInstrs> 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->getSubtarget().getInstrInfo(); + bool IsPostRA = Scheduler.isPostRA(); + + // Visit all machine basic blocks. + // + // TODO: Visit blocks in global postorder or postorder within the bottom-up + // loop tree. Then we can optionally compute global RegPressure. + for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end(); + MBB != MBBEnd; ++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 + // boundary at the bottom of the region. The DAG does not include RegionEnd, + // but the region does (i.e. the next RegionEnd is above the previous + // RegionBegin). If the current block has no terminator then RegionEnd == + // MBB->end() for the bottom region. + // + // 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. + // + // 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()) { + + // Avoid decrementing RegionEnd for blocks with no terminator. + if (RegionEnd != MBB->end() || + isSchedBoundary(std::prev(RegionEnd), MBB, MF, TII, IsPostRA)) { + --RegionEnd; + // Count the boundary instruction. + --RemainingInstrs; + } + + // The next region starts above the previous region. Look backward in the + // instruction stream until we find the nearest boundary. + unsigned NumRegionInstrs = 0; + MachineBasicBlock::iterator I = RegionEnd; + for(;I != MBB->begin(); --I, --RemainingInstrs) { + if (isSchedBoundary(std::prev(I), MBB, MF, TII, IsPostRA)) + break; + if (!I->isDebugValue()) + ++NumRegionInstrs; + } + // 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); + + // Skip empty scheduling regions (0 or 1 schedulable instructions). + if (I == RegionEnd || I == std::prev(RegionEnd)) { + // Close the current region. Bundle the terminator if needed. + // This invalidates 'RegionEnd' and 'I'. + Scheduler.exitRegion(); + continue; + } + DEBUG(dbgs() << "********** " << ((Scheduler.isPostRA()) ? "PostRA " : "") + << "MI Scheduling **********\n"); + DEBUG(dbgs() << MF->getName() + << ":BB#" << MBB->getNumber() << " " << MBB->getName() + << "\n From: " << *I << " To: "; + if (RegionEnd != MBB->end()) dbgs() << *RegionEnd; + else dbgs() << "End"; + dbgs() << " RegionInstrs: " << NumRegionInstrs + << " Remaining: " << RemainingInstrs << "\n"); + if (DumpCriticalPathLength) { + errs() << MF->getName(); + errs() << ":BB# " << MBB->getNumber(); + errs() << " " << MBB->getName() << " \n"; + } + + // Schedule a region: possibly reorder instructions. + // This invalidates 'RegionEnd' and 'I'. + Scheduler.schedule(); + + // Close the current region. + Scheduler.exitRegion(); + + // Scheduling has invalidated the current iterator 'I'. Ask the + // scheduler for the top of it's scheduled region. + RegionEnd = Scheduler.begin(); + } + assert(RemainingInstrs == 0 && "Instruction count mismatch!"); + 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(); +} + +void MachineSchedulerBase::print(raw_ostream &O, const Module* m) const { + // unimplemented +} + +LLVM_DUMP_METHOD +void ReadyQueue::dump() { + dbgs() << Name << ": "; + for (unsigned i = 0, e = Queue.size(); i < e; ++i) + dbgs() << Queue[i]->NodeNum << " "; + dbgs() << "\n"; +} + +//===----------------------------------------------------------------------===// +// 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() { +} + +bool ScheduleDAGMI::canAddEdge(SUnit *SuccSU, SUnit *PredSU) { + return SuccSU == &ExitSU || !Topo.IsReachable(PredSU, SuccSU); +} + +bool ScheduleDAGMI::addEdge(SUnit *SuccSU, const SDep &PredDep) { + if (SuccSU != &ExitSU) { + // Do not use WillCreateCycle, it assumes SD scheduling. + // If Pred is reachable from Succ, then the edge creates a cycle. + if (Topo.IsReachable(PredDep.getSUnit(), SuccSU)) + return false; + Topo.AddPred(SuccSU, PredDep.getSUnit()); + } + SuccSU->addPred(PredDep, /*Required=*/!PredDep.isArtificial()); + // Return true regardless of whether a new edge needed to be inserted. + return true; +} + +/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When +/// NumPredsLeft reaches zero, release the successor node. +/// +/// FIXME: Adjust SuccSU height based on MinLatency. +void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) { + SUnit *SuccSU = SuccEdge->getSUnit(); + + if (SuccEdge->isWeak()) { + --SuccSU->WeakPredsLeft; + if (SuccEdge->isCluster()) + NextClusterSucc = SuccSU; + return; + } +#ifndef NDEBUG + if (SuccSU->NumPredsLeft == 0) { + dbgs() << "*** Scheduling failed! ***\n"; + SuccSU->dump(this); + dbgs() << " has been released too many times!\n"; + llvm_unreachable(nullptr); + } +#endif + // SU->TopReadyCycle was set to CurrCycle when it was scheduled. However, + // CurrCycle may have advanced since then. + if (SuccSU->TopReadyCycle < SU->TopReadyCycle + SuccEdge->getLatency()) + SuccSU->TopReadyCycle = SU->TopReadyCycle + SuccEdge->getLatency(); + + --SuccSU->NumPredsLeft; + if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU) + SchedImpl->releaseTopNode(SuccSU); +} + +/// releaseSuccessors - Call releaseSucc on each of SU's successors. +void ScheduleDAGMI::releaseSuccessors(SUnit *SU) { + for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); + I != E; ++I) { + releaseSucc(SU, &*I); + } +} + +/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. When +/// NumSuccsLeft reaches zero, release the predecessor node. +/// +/// FIXME: Adjust PredSU height based on MinLatency. +void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) { + SUnit *PredSU = PredEdge->getSUnit(); + + if (PredEdge->isWeak()) { + --PredSU->WeakSuccsLeft; + if (PredEdge->isCluster()) + NextClusterPred = PredSU; + return; + } +#ifndef NDEBUG + if (PredSU->NumSuccsLeft == 0) { + dbgs() << "*** Scheduling failed! ***\n"; + PredSU->dump(this); + dbgs() << " has been released too many times!\n"; + llvm_unreachable(nullptr); + } +#endif + // SU->BotReadyCycle was set to CurrCycle when it was scheduled. However, + // CurrCycle may have advanced since then. + if (PredSU->BotReadyCycle < SU->BotReadyCycle + PredEdge->getLatency()) + PredSU->BotReadyCycle = SU->BotReadyCycle + PredEdge->getLatency(); + + --PredSU->NumSuccsLeft; + if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU) + SchedImpl->releaseBottomNode(PredSU); +} + +/// releasePredecessors - Call releasePred on each of SU's predecessors. +void ScheduleDAGMI::releasePredecessors(SUnit *SU) { + for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); + I != E; ++I) { + releasePred(SU, &*I); + } +} + +/// 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) { + // Advance RegionBegin if the first instruction moves down. + if (&*RegionBegin == MI) + ++RegionBegin; + + // Update the instruction stream. + BB->splice(InsertPos, BB, MI); + + // Update LiveIntervals + if (LIS) + LIS->handleMove(MI, /*UpdateFlags=*/true); + + // Recede RegionBegin if an instruction moves above the first. + if (RegionBegin == InsertPos) + RegionBegin = MI; +} + +bool ScheduleDAGMI::checkSchedLimit() { +#ifndef NDEBUG + if (NumInstrsScheduled == MISchedCutoff && MISchedCutoff != ~0U) { + CurrentTop = CurrentBottom; + return false; + } + ++NumInstrsScheduled; +#endif + return true; +} + +/// 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() { + // Build the DAG. + buildSchedGraph(AA); + + Topo.InitDAGTopologicalSorting(); + + postprocessDAG(); + + SmallVector<SUnit*, 8> TopRoots, BotRoots; + findRootsAndBiasEdges(TopRoots, BotRoots); + + // Initialize the strategy before modifying the DAG. + // This may initialize a DFSResult to be used for queue priority. + SchedImpl->initialize(this); + + DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su) + SUnits[su].dumpAll(this)); + if (ViewMISchedDAGs) viewGraph(); + + // Initialize ready queues now that the DAG and priority data are finalized. + initQueues(TopRoots, BotRoots); + + bool IsTopNode = false; + while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) { + assert(!SU->isScheduled && "Node already scheduled"); + if (!checkSchedLimit()) + break; + + 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; + } + } + // Notify the scheduling strategy before updating the DAG. + // This sets the scheduled node's ReadyCycle to CurrCycle. When updateQueues + // runs, it can then use the accurate ReadyCycle time to determine whether + // newly released nodes can move to the readyQ. + SchedImpl->schedNode(SU, IsTopNode); + + updateQueues(SU, IsTopNode); + } + assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); + + placeDebugValues(); + + DEBUG({ + unsigned BBNum = begin()->getParent()->getNumber(); + dbgs() << "*** Final schedule for BB#" << BBNum << " ***\n"; + dumpSchedule(); + dbgs() << '\n'; + }); +} + +/// Apply each ScheduleDAGMutation step in order. +void ScheduleDAGMI::postprocessDAG() { + for (unsigned i = 0, e = Mutations.size(); i < e; ++i) { + Mutations[i]->apply(this); + } +} + +void ScheduleDAGMI:: +findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots, + SmallVectorImpl<SUnit*> &BotRoots) { + for (std::vector<SUnit>::iterator + I = SUnits.begin(), E = SUnits.end(); I != E; ++I) { + SUnit *SU = &(*I); + assert(!SU->isBoundaryNode() && "Boundary node should not be in SUnits"); + + // Order predecessors so DFSResult follows the critical path. + SU->biasCriticalPath(); + + // A SUnit is ready to top schedule if it has no predecessors. + if (!I->NumPredsLeft) + TopRoots.push_back(SU); + // A SUnit is ready to bottom schedule if it has no successors. + if (!I->NumSuccsLeft) + BotRoots.push_back(SU); + } + ExitSU.biasCriticalPath(); +} + +/// Identify DAG roots and setup scheduler queues. +void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots, + ArrayRef<SUnit*> BotRoots) { + NextClusterSucc = nullptr; + NextClusterPred = nullptr; + + // Release all DAG roots for scheduling, not including EntrySU/ExitSU. + // + // Nodes with unreleased weak edges can still be roots. + // Release top roots in forward order. + for (SmallVectorImpl<SUnit*>::const_iterator + I = TopRoots.begin(), E = TopRoots.end(); I != E; ++I) { + SchedImpl->releaseTopNode(*I); + } + // Release bottom roots in reverse order so the higher priority nodes appear + // first. This is more natural and slightly more efficient. + for (SmallVectorImpl<SUnit*>::const_reverse_iterator + I = BotRoots.rbegin(), E = BotRoots.rend(); I != E; ++I) { + SchedImpl->releaseBottomNode(*I); + } + + releaseSuccessors(&EntrySU); + releasePredecessors(&ExitSU); + + SchedImpl->registerRoots(); + + // Advance past initial DebugValues. + CurrentTop = nextIfDebug(RegionBegin, RegionEnd); + CurrentBottom = RegionEnd; +} + +/// Update scheduler queues after scheduling an instruction. +void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) { + // Release dependent instructions for scheduling. + if (IsTopNode) + releaseSuccessors(SU); + else + releasePredecessors(SU); + + SU->isScheduled = true; +} + +/// Reinsert any remaining debug_values, just like the PostRA scheduler. +void ScheduleDAGMI::placeDebugValues() { + // If first instruction was a DBG_VALUE then put it back. + if (FirstDbgValue) { + BB->splice(RegionBegin, BB, FirstDbgValue); + RegionBegin = FirstDbgValue; + } + + for (std::vector<std::pair<MachineInstr *, MachineInstr *> >::iterator + DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) { + std::pair<MachineInstr *, MachineInstr *> P = *std::prev(DI); + MachineInstr *DbgValue = P.first; + MachineBasicBlock::iterator OrigPrevMI = P.second; + if (&*RegionBegin == DbgValue) + ++RegionBegin; + BB->splice(++OrigPrevMI, BB, DbgValue); + if (OrigPrevMI == std::prev(RegionEnd)) + RegionEnd = DbgValue; + } + DbgValues.clear(); + FirstDbgValue = nullptr; +} + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +void ScheduleDAGMI::dumpSchedule() const { + for (MachineBasicBlock::iterator MI = begin(), ME = end(); MI != ME; ++MI) { + if (SUnit *SU = getSUnit(&(*MI))) + SU->dump(this); + else + dbgs() << "Missing SUnit\n"; + } +} +#endif + +//===----------------------------------------------------------------------===// +// ScheduleDAGMILive - Base class for MachineInstr scheduling with LiveIntervals +// preservation. +//===----------------------------------------------------------------------===// + +ScheduleDAGMILive::~ScheduleDAGMILive() { + delete DFSResult; +} + +/// 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); + + // For convenience remember the end of the liveness region. + LiveRegionEnd = (RegionEnd == bb->end()) ? RegionEnd : std::next(RegionEnd); + + SUPressureDiffs.clear(); + + ShouldTrackPressure = SchedImpl->shouldTrackPressure(); +} + +// 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<unsigned, 8> LiveUses; + BotRPTracker.recede(&LiveUses); + updatePressureDiffs(LiveUses); + } + + 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<unsigned> &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"); +} + +void ScheduleDAGMILive:: +updateScheduledPressure(const SUnit *SU, + const std::vector<unsigned> &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] + << ((NewMaxPressure[ID] > Limit) ? " > " : " <= ") << Limit + << "(+ " << BotRPTracker.getLiveThru()[ID] << " livethru)\n"); + } + } +} + +/// Update the PressureDiff array for liveness after scheduling this +/// instruction. +void ScheduleDAGMILive::updatePressureDiffs(ArrayRef<unsigned> 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; + + // 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); + } + } + } +} + +/// 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(); + + Topo.InitDAGTopologicalSorting(); + + postprocessDAG(); + + SmallVector<SUnit*, 8> TopRoots, BotRoots; + findRootsAndBiasEdges(TopRoots, BotRoots); + + // Initialize the strategy before modifying the DAG. + // This may initialize a DFSResult to be used for queue priority. + SchedImpl->initialize(this); + + DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su) + SUnits[su].dumpAll(this)); + if (ViewMISchedDAGs) viewGraph(); + + // Initialize ready queues now that the DAG and priority data are finalized. + initQueues(TopRoots, BotRoots); + + if (ShouldTrackPressure) { + assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); + TopRPTracker.setPos(CurrentTop); + } + + bool IsTopNode = false; + while (SUnit *SU = SchedImpl->pickNode(IsTopNode)) { + assert(!SU->isScheduled && "Node already scheduled"); + if (!checkSchedLimit()) + break; + + scheduleMI(SU, IsTopNode); + + 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); + + updateQueues(SU, IsTopNode); + } + assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); + + placeDebugValues(); + + DEBUG({ + unsigned BBNum = begin()->getParent()->getNumber(); + dbgs() << "*** Final schedule for BB#" << BBNum << " ***\n"; + dumpSchedule(); + dbgs() << '\n'; + }); +} + +/// Build the DAG and setup three register pressure trackers. +void ScheduleDAGMILive::buildDAGWithRegPressure() { + if (!ShouldTrackPressure) { + RPTracker.reset(); + RegionCriticalPSets.clear(); + buildSchedGraph(AA); + return; + } + + // 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(); +} + +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()); +} + +/// 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<unsigned> LiveOuts = RPTracker.getPressure().LiveOutRegs; + for (ArrayRef<unsigned>::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<unsigned, 8> 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<SUnit*> Loads, ScheduleDAGMI *DAG); +}; +} // anonymous + +void LoadClusterMutation::clusterNeighboringLoads(ArrayRef<SUnit*> Loads, + ScheduleDAGMI *DAG) { + SmallVector<LoadClusterMutation::LoadInfo,32> LoadRecords; + for (unsigned Idx = 0, End = Loads.size(); Idx != End; ++Idx) { + SUnit *SU = Loads[Idx]; + unsigned BaseReg; + unsigned Offset; + if (TII->getMemOpBaseRegImmOfs(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<unsigned, unsigned> StoreChainIDs; + // Map each store chain to a set of dependent loads. + SmallVector<SmallVector<SUnit*,4>, 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<DenseMap<unsigned, unsigned>::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. + // If both the copy's source and dest are local live intervals, then we + // should treat the dest as the global for the purpose of adding + // constraints. This adds edges from source's other uses to the copy. + unsigned LocalReg = SrcReg; + unsigned GlobalReg = DstReg; + LiveInterval *LocalLI = &LIS->getInterval(LocalReg); + if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) { + LocalReg = DstReg; + GlobalReg = SrcReg; + 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<SUnit*,8> 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<SUnit*,8> 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<SUnit*>::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<SUnit*>::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<ScheduleDAGMILive*>(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). + MaxObservedStall = 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<SUnit>::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) { + unsigned NRCycle = getNextResourceCycle(PI->ProcResourceIdx, PI->Cycles); + if (NRCycle > CurrCycle) { +#ifndef NDEBUG + MaxObservedStall = std::max(PI->Cycles, MaxObservedStall); +#endif + DEBUG(dbgs() << " SU(" << SU->NodeNum << ") " + << SchedModel->getResourceName(PI->ProcResourceIdx) + << "=" << NRCycle << "c\n"); + return true; + } + } + } + return false; +} + +// Find the unscheduled node in ReadySUs with the highest latency. +unsigned SchedBoundary:: +findMaxLatency(ArrayRef<SUnit*> ReadySUs) { + SUnit *LateSU = nullptr; + unsigned RemLatency = 0; + for (ArrayRef<SUnit*>::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) { + assert(SU->getInstr() && "Scheduled SUnit must have instr"); + +#ifndef NDEBUG + // ReadyCycle was been bumped up to the CurrCycle when this node was + // scheduled, but CurrCycle may have been eagerly advanced immediately after + // scheduling, so may now be greater than ReadyCycle. + if (ReadyCycle > CurrCycle) + MaxObservedStall = std::max(ReadyCycle - CurrCycle, MaxObservedStall); +#endif + + 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; + + releaseNode(SU, SU->TopReadyCycle); +} + +void SchedBoundary::releaseBottomNode(SUnit *SU) { + if (SU->isScheduled) + return; + + 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) { + if (isTop()) { + ReservedCycles[PIdx] = + std::max(getNextResourceCycle(PIdx, 0), NextCycle + PI->Cycles); + } + else + ReservedCycles[PIdx] = NextCycle; + } + } + } + } + // 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) { +// FIXME: Re-enable assert once PR20057 is resolved. +// assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedStall) && +// "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 + +//===----------------------------------------------------------------------===// +// GenericScheduler - Generic implementation of MachineSchedStrategy. +//===----------------------------------------------------------------------===// + +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; + } +} + +/// 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 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 + // outside this zone are resource or latency limited. + // + // The "dependent" latency is updated incrementally during scheduling as the + // max height/depth of scheduled nodes minus the cycles since it was + // scheduled: + // DLat = max (N.depth - (CurrCycle - N.ReadyCycle) for N in Zone + // + // The "independent" latency is the max ready queue depth: + // ILat = max N.depth for N in Available|Pending + // + // RemainingLatency is the greater of independent and dependent latency. + 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 = 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; + } + // 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 (CurrZone.getZoneCritResIdx() == OtherCritIdx) + return; + + DEBUG( + if (CurrZone.isResourceLimited()) { + dbgs() << " " << CurrZone.Available.getName() << " ResourceLimited: " + << SchedModel->getResourceName(CurrZone.getZoneCritResIdx()) + << "\n"; + } + if (OtherResLimited) + dbgs() << " RemainingLimit: " + << SchedModel->getResourceName(OtherCritIdx) << "\n"; + if (!CurrZone.isResourceLimited() && !OtherResLimited) + dbgs() << " Latency limited both directions.\n"); + + if (CurrZone.isResourceLimited() && !Policy.ReduceResIdx) + Policy.ReduceResIdx = CurrZone.getZoneCritResIdx(); + + if (OtherResLimited) + Policy.DemandResIdx = OtherCritIdx; +} + +#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!"); +} + +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; + } + 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 + +/// 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; + } + if (TryVal > CandVal) { + if (Cand.Reason > Reason) + Cand.Reason = Reason; + return true; + } + Cand.setRepeat(Reason); + return false; +} + +static bool tryGreater(int TryVal, int CandVal, + GenericSchedulerBase::SchedCandidate &TryCand, + GenericSchedulerBase::SchedCandidate &Cand, + GenericSchedulerBase::CandReason Reason) { + if (TryVal > CandVal) { + TryCand.Reason = Reason; + return true; + } + if (TryVal < CandVal) { + if (Cand.Reason > Reason) + Cand.Reason = Reason; + return true; + } + Cand.setRepeat(Reason); + return false; +} + +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; + } + if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), + TryCand, Cand, GenericSchedulerBase::TopPathReduce)) + return true; + } + else { + 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; + } + return false; +} + +static void tracePick(const GenericSchedulerBase::SchedCandidate &Cand, + bool IsTop) { + DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ") + << GenericSchedulerBase::getReasonStr(Cand.Reason) << '\n'); +} + +void GenericScheduler::initialize(ScheduleDAGMI *dag) { + assert(dag->hasVRegLiveness() && + "(PreRA)GenericScheduler needs vreg liveness"); + DAG = static_cast<ScheduleDAGMILive*>(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(); + if (!Top.HazardRec) { + Top.HazardRec = + DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( + Itin, DAG); + } + if (!Bot.HazardRec) { + Bot.HazardRec = + DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( + Itin, DAG); + } +} + +/// Initialize the per-region scheduling policy. +void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs) { + const MachineFunction &MF = *Begin->getParent()->getParent(); + const TargetLowering *TLI = MF.getSubtarget().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 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. + MF.getSubtarget().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; + } + if (ForceTopDown.getNumOccurrences() > 0) { + RegionPolicy.OnlyTopDown = ForceTopDown; + if (RegionPolicy.OnlyTopDown) + RegionPolicy.OnlyBottomUp = false; + } +} + +/// 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; + + // 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(); + + // Some roots may not feed into ExitSU. Check all of them in case. + for (std::vector<SUnit*>::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(GS-RR ): " << Rem.CriticalPath << '\n'); + if (DumpCriticalPathLength) { + errs() << "Critical Path(GS-RR ): " << Rem.CriticalPath << " \n"; + } + + if (EnableCyclicPath) { + Rem.CyclicCritPath = DAG->computeCyclicCriticalPath(); + checkAcyclicLatency(); + } +} + +static bool tryPressure(const PressureChange &TryP, + const PressureChange &CandP, + 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 (tryGreater(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand, + Reason)) { + return true; + } + // If the candidates are decreasing pressure, reverse priority. + if (TryP.getUnitInc() < 0) + std::swap(TryRank, CandRank); + return tryGreater(TryRank, CandRank, TryCand, Cand, Reason); +} + +static unsigned getWeakLeft(const SUnit *SU, bool isTop) { + return (isTop) ? SU->WeakPredsLeft : SU->WeakSuccsLeft; +} + +/// Minimize physical register live ranges. Regalloc wants them adjacent to +/// their physreg def/use. +/// +/// FIXME: This is an unnecessary check on the critical path. Most are root/leaf +/// copies which can be prescheduled. The rest (e.g. x86 MUL) could be bundled +/// with the operation that produces or consumes the physreg. We'll do this when +/// regalloc has support for parallel copies. +static int biasPhysRegCopy(const SUnit *SU, bool isTop) { + const MachineInstr *MI = SU->getInstr(); + if (!MI->isCopy()) + return 0; + + unsigned ScheduledOper = isTop ? 1 : 0; + unsigned UnscheduledOper = isTop ? 0 : 1; + // If we have already scheduled the physreg produce/consumer, immediately + // schedule the copy. + if (TargetRegisterInfo::isPhysicalRegister( + MI->getOperand(ScheduledOper).getReg())) + return 1; + // If the physreg is at the boundary, defer it. Otherwise schedule it + // immediately to free the dependent. We can hoist the copy later. + bool AtBoundary = isTop ? !SU->NumSuccsLeft : !SU->NumPredsLeft; + if (TargetRegisterInfo::isPhysicalRegister( + MI->getOperand(UnscheduledOper).getReg())) + return AtBoundary ? -1 : 1; + return 0; +} + +/// 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 +/// queue. But it's really done to make the heuristics easier to debug and +/// statistically analyze. +/// +/// \param Cand provides the policy and current best candidate. +/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized. +/// \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 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(), + TryCand.RPDelta, + DAG->getRegionCriticalPSets(), + DAG->getRegPressure().MaxSetPressure); + } + else { + 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()) { + TryCand.Reason = NodeOrder; + return; + } + + if (tryGreater(biasPhysRegCopy(TryCand.SU, Zone.isTop()), + biasPhysRegCopy(Cand.SU, Zone.isTop()), + TryCand, Cand, PhysRegCopy)) + return; + + // Avoid exceeding the target's limit. + 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. + // 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; + + // 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 + // optimizations which may reduce resource requirements. + // + // This is a best effort to set things up for a post-RA pass. Optimizations + // like generating loads of multiple registers should ideally be done within + // the scheduler pass by combining the loads during DAG postprocessing. + const SUnit *NextClusterSU = + Zone.isTop() ? DAG->getNextClusterSucc() : DAG->getNextClusterPred(); + if (tryGreater(TryCand.SU == NextClusterSU, Cand.SU == NextClusterSU, + TryCand, Cand, Cluster)) + return; + + // Weak edges are for clustering and other constraints. + if (tryLess(getWeakLeft(TryCand.SU, Zone.isTop()), + getWeakLeft(Cand.SU, Zone.isTop()), + TryCand, Cand, Weak)) { + return; + } + // Avoid increasing the max pressure of the entire region. + if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CurrentMax, + Cand.RPDelta.CurrentMax, + TryCand, Cand, RegMax)) + return; + + // Avoid critical resource consumption and balance the schedule. + TryCand.initResourceDelta(DAG, SchedModel); + 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. + // For acyclic path limited loops, latency was already checked above. + if (Cand.Policy.ReduceLatency && !Rem.IsAcyclicLatencyLimited + && tryLatency(TryCand, Cand, Zone)) { + return; + } + + // 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.isNextSU(TryCand.SU), Zone.isNextSU(Cand.SU), + TryCand, Cand, NextDefUse)) + return; + + // Fall through to original instruction order. + if ((Zone.isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum) + || (!Zone.isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) { + TryCand.Reason = NodeOrder; + } +} + +/// 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 GenericScheduler::pickNodeFromQueue(SchedBoundary &Zone, + const RegPressureTracker &RPTracker, + SchedCandidate &Cand) { + ReadyQueue &Q = Zone.Available; + + DEBUG(Q.dump()); + + // getMaxPressureDelta temporarily modifies the tracker. + RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker); + + for (ReadyQueue::iterator I = Q.begin(), E = Q.end(); I != E; ++I) { + + SchedCandidate TryCand(Cand.Policy); + TryCand.SU = *I; + tryCandidate(Cand, TryCand, Zone, RPTracker, TempTracker); + if (TryCand.Reason != NoCand) { + // Initialize resource delta if needed in case future heuristics query it. + if (TryCand.ResDelta == SchedResourceDelta()) + TryCand.initResourceDelta(DAG, SchedModel); + Cand.setBest(TryCand); + DEBUG(traceCandidate(Cand)); + } + } +} + +/// Pick the best candidate node from either the top or bottom queue. +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()) { + IsTopNode = false; + DEBUG(dbgs() << "Pick Bot NOCAND\n"); + return SU; + } + if (SUnit *SU = Top.pickOnlyChoice()) { + IsTopNode = true; + DEBUG(dbgs() << "Pick Top NOCAND\n"); + return SU; + } + CandPolicy NoPolicy; + SchedCandidate BotCand(NoPolicy); + SchedCandidate TopCand(NoPolicy); + // 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); + assert(BotCand.Reason != NoCand && "failed to find the first candidate"); + + // If either Q has a single candidate that provides the least increase in + // Excess pressure, we can immediately schedule from that Q. + // + // RegionCriticalPSets summarizes the pressure within the scheduled region and + // affects picking from either Q. If scheduling in one direction must + // increase pressure for one of the excess PSets, then schedule in that + // direction first to provide more freedom in the other direction. + if ((BotCand.Reason == RegExcess && !BotCand.isRepeat(RegExcess)) + || (BotCand.Reason == RegCritical + && !BotCand.isRepeat(RegCritical))) + { + IsTopNode = false; + tracePick(BotCand, IsTopNode); + return BotCand.SU; + } + // Check if the top Q has a better candidate. + pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand); + assert(TopCand.Reason != NoCand && "failed to find the first candidate"); + + // Choose the queue with the most important (lowest enum) reason. + if (TopCand.Reason < BotCand.Reason) { + IsTopNode = true; + tracePick(TopCand, IsTopNode); + return TopCand.SU; + } + // Otherwise prefer the bottom candidate, in node order if all else failed. + IsTopNode = false; + tracePick(BotCand, IsTopNode); + return BotCand.SU; +} + +/// Pick the best node to balance the schedule. Implements MachineSchedStrategy. +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 nullptr; + } + SUnit *SU; + do { + 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 a candidate"); + tracePick(TopCand, true); + SU = TopCand.SU; + } + IsTopNode = true; + } + 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 a candidate"); + tracePick(BotCand, false); + SU = BotCand.SU; + } + IsTopNode = false; + } + else { + SU = pickNodeBidirectional(IsTopNode); + } + } while (SU->isScheduled); + + if (SU->isTopReady()) + Top.removeReady(SU); + if (SU->isBottomReady()) + Bot.removeReady(SU); + + DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " << *SU->getInstr()); + return SU; +} + +void GenericScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { + + MachineBasicBlock::iterator InsertPos = SU->getInstr(); + if (!isTop) + ++InsertPos; + SmallVectorImpl<SDep> &Deps = isTop ? SU->Preds : SU->Succs; + + // Find already scheduled copies with a single physreg dependence and move + // them just above the scheduled instruction. + for (SmallVectorImpl<SDep>::iterator I = Deps.begin(), E = Deps.end(); + I != E; ++I) { + if (I->getKind() != SDep::Data || !TRI->isPhysicalRegister(I->getReg())) + continue; + SUnit *DepSU = I->getSUnit(); + if (isTop ? DepSU->Succs.size() > 1 : DepSU->Preds.size() > 1) + continue; + MachineInstr *Copy = DepSU->getInstr(); + if (!Copy->isCopy()) + continue; + DEBUG(dbgs() << " Rescheduling physreg copy "; + I->getSUnit()->dump(DAG)); + DAG->moveInstruction(Copy, InsertPos); + } +} + +/// Update the scheduler's state after scheduling a node. This is the same node +/// 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 GenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { + if (IsTopNode) { + 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.getCurrCycle()); + Bot.bumpNode(SU); + if (SU->hasPhysRegDefs) + reschedulePhysRegCopies(SU, false); + } +} + +/// Create the standard converging machine scheduler. This will be used as the +/// default scheduler if the target does not set a default. +static ScheduleDAGInstrs *createGenericSchedLive(MachineSchedContext *C) { + ScheduleDAGMILive *DAG = new ScheduleDAGMILive(C, make_unique<GenericScheduler>(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(make_unique<CopyConstrain>(DAG->TII, DAG->TRI)); + if (EnableLoadCluster && DAG->TII->enableClusterLoads()) + DAG->addMutation(make_unique<LoadClusterMutation>(DAG->TII, DAG->TRI)); + if (EnableMacroFusion) + DAG->addMutation(make_unique<MacroFusion>(DAG->TII)); + return DAG; +} + +static MachineSchedRegistry +GenericSchedRegistry("converge", "Standard converging scheduler.", + createGenericSchedLive); + +//===----------------------------------------------------------------------===// +// PostGenericScheduler - Generic PostRA implementation of MachineSchedStrategy. +//===----------------------------------------------------------------------===// + +void PostGenericScheduler::initialize(ScheduleDAGMI *Dag) { + 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(); + if (!Top.HazardRec) { + Top.HazardRec = + DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( + Itin, DAG); + } +} + + +void PostGenericScheduler::registerRoots() { + Rem.CriticalPath = DAG->ExitSU.getDepth(); + + // Some roots may not feed into ExitSU. Check all of them in case. + for (SmallVectorImpl<SUnit*>::const_iterator + I = BotRoots.begin(), E = BotRoots.end(); I != E; ++I) { + if ((*I)->getDepth() > Rem.CriticalPath) + Rem.CriticalPath = (*I)->getDepth(); + } + DEBUG(dbgs() << "Critical Path: (PGS-RR) " << Rem.CriticalPath << '\n'); + if (DumpCriticalPathLength) { + errs() << "Critical Path(PGS-RR ): " << 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<PostGenericScheduler>(C), /*IsPostRA=*/true); +} + +//===----------------------------------------------------------------------===// +// ILP Scheduler. Currently for experimental analysis of heuristics. +//===----------------------------------------------------------------------===// + +namespace { +/// \brief Order nodes by the ILP metric. +struct ILPOrder { + const SchedDFSResult *DFSResult; + const BitVector *ScheduledTrees; + bool MaximizeILP; + + ILPOrder(bool MaxILP) + : DFSResult(nullptr), ScheduledTrees(nullptr), MaximizeILP(MaxILP) {} + + /// \brief Apply a less-than relation on node priority. + /// + /// (Return true if A comes after B in the Q.) + bool operator()(const SUnit *A, const SUnit *B) const { + unsigned SchedTreeA = DFSResult->getSubtreeID(A); + unsigned SchedTreeB = DFSResult->getSubtreeID(B); + if (SchedTreeA != SchedTreeB) { + // Unscheduled trees have lower priority. + if (ScheduledTrees->test(SchedTreeA) != ScheduledTrees->test(SchedTreeB)) + return ScheduledTrees->test(SchedTreeB); + + // Trees with shallower connections have have lower priority. + if (DFSResult->getSubtreeLevel(SchedTreeA) + != DFSResult->getSubtreeLevel(SchedTreeB)) { + return DFSResult->getSubtreeLevel(SchedTreeA) + < DFSResult->getSubtreeLevel(SchedTreeB); + } + } + if (MaximizeILP) + return DFSResult->getILP(A) < DFSResult->getILP(B); + else + return DFSResult->getILP(A) > DFSResult->getILP(B); + } +}; + +/// \brief Schedule based on the ILP metric. +class ILPScheduler : public MachineSchedStrategy { + ScheduleDAGMILive *DAG; + ILPOrder Cmp; + + std::vector<SUnit*> ReadyQ; +public: + ILPScheduler(bool MaximizeILP): DAG(nullptr), Cmp(MaximizeILP) {} + + void initialize(ScheduleDAGMI *dag) override { + assert(dag->hasVRegLiveness() && "ILPScheduler needs vreg liveness"); + DAG = static_cast<ScheduleDAGMILive*>(dag); + DAG->computeDFSResult(); + Cmp.DFSResult = DAG->getDFSResult(); + Cmp.ScheduledTrees = &DAG->getScheduledTrees(); + ReadyQ.clear(); + } + + void registerRoots() override { + // Restore the heap in ReadyQ with the updated DFS results. + std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); + } + + /// Implement MachineSchedStrategy interface. + /// ----------------------------------------- + + /// Callback to select the highest priority node from the ready Q. + 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(); + IsTopNode = false; + DEBUG(dbgs() << "Pick node " << "SU(" << SU->NodeNum << ") " + << " ILP: " << DAG->getDFSResult()->getILP(SU) + << " Tree: " << DAG->getDFSResult()->getSubtreeID(SU) << " @" + << DAG->getDFSResult()->getSubtreeLevel( + DAG->getDFSResult()->getSubtreeID(SU)) << '\n' + << "Scheduling " << *SU->getInstr()); + return SU; + } + + /// \brief Scheduler callback to notify that a new subtree is scheduled. + 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. + void schedNode(SUnit *SU, bool IsTopNode) override { + assert(!IsTopNode && "SchedDFSResult needs bottom-up"); + } + + void releaseTopNode(SUnit *) override { /*only called for top roots*/ } + + void releaseBottomNode(SUnit *SU) override { + ReadyQ.push_back(SU); + std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); + } +}; +} // namespace + +static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) { + return new ScheduleDAGMILive(C, make_unique<ILPScheduler>(true)); +} +static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) { + return new ScheduleDAGMILive(C, make_unique<ILPScheduler>(false)); +} +static MachineSchedRegistry ILPMaxRegistry( + "ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler); +static MachineSchedRegistry ILPMinRegistry( + "ilpmin", "Schedule bottom-up for min ILP", createILPMinScheduler); + +//===----------------------------------------------------------------------===// +// Machine Instruction Shuffler for Correctness Testing +//===----------------------------------------------------------------------===// + +#ifndef NDEBUG +namespace { +/// Apply a less-than relation on the node order, which corresponds to the +/// instruction order prior to scheduling. IsReverse implements greater-than. +template<bool IsReverse> +struct SUnitOrder { + bool operator()(SUnit *A, SUnit *B) const { + if (IsReverse) + return A->NodeNum > B->NodeNum; + else + return A->NodeNum < B->NodeNum; + } +}; + +/// Reorder instructions as much as possible. +class InstructionShuffler : public MachineSchedStrategy { + bool IsAlternating; + bool IsTopDown; + + // Using a less-than relation (SUnitOrder<false>) for the TopQ priority + // gives nodes with a higher number higher priority causing the latest + // instructions to be scheduled first. + PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<false> > + TopQ; + // When scheduling bottom-up, use greater-than as the queue priority. + PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<true> > + BottomQ; +public: + InstructionShuffler(bool alternate, bool topdown) + : IsAlternating(alternate), IsTopDown(topdown) {} + + void initialize(ScheduleDAGMI*) override { + TopQ.clear(); + BottomQ.clear(); + } + + /// Implement MachineSchedStrategy interface. + /// ----------------------------------------- + + SUnit *pickNode(bool &IsTopNode) override { + SUnit *SU; + if (IsTopDown) { + do { + if (TopQ.empty()) return nullptr; + SU = TopQ.top(); + TopQ.pop(); + } while (SU->isScheduled); + IsTopNode = true; + } + else { + do { + if (BottomQ.empty()) return nullptr; + SU = BottomQ.top(); + BottomQ.pop(); + } while (SU->isScheduled); + IsTopNode = false; + } + if (IsAlternating) + IsTopDown = !IsTopDown; + return SU; + } + + void schedNode(SUnit *SU, bool IsTopNode) override {} + + void releaseTopNode(SUnit *SU) override { + TopQ.push(SU); + } + void releaseBottomNode(SUnit *SU) override { + BottomQ.push(SU); + } +}; +} // namespace + +static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) { + bool Alternate = !ForceTopDown && !ForceBottomUp; + bool TopDown = !ForceBottomUp; + assert((TopDown || !ForceTopDown) && + "-misched-topdown incompatible with -misched-bottomup"); + return new ScheduleDAGMILive(C, make_unique<InstructionShuffler>(Alternate, TopDown)); +} +static MachineSchedRegistry ShufflerRegistry( + "shuffle", "Shuffle machine instructions alternating directions", + createInstructionShuffler); +#endif // !NDEBUG + +//===----------------------------------------------------------------------===// +// GraphWriter support for ScheduleDAGMILive. +//===----------------------------------------------------------------------===// + +#ifndef NDEBUG +namespace llvm { + +template<> struct GraphTraits< + ScheduleDAGMI*> : public GraphTraits<ScheduleDAG*> {}; + +template<> +struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits { + + DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {} + + static std::string getGraphName(const ScheduleDAG *G) { + return G->MF.getName(); + } + + static bool renderGraphFromBottomUp() { + return true; + } + + static bool isNodeHidden(const SUnit *Node) { + return (Node->Preds.size() > 10 || Node->Succs.size() > 10); + } + + static bool hasNodeAddressLabel(const SUnit *Node, + const ScheduleDAG *Graph) { + return false; + } + + /// If you want to override the dot attributes printed for a particular + /// edge, override this method. + static std::string getEdgeAttributes(const SUnit *Node, + SUnitIterator EI, + const ScheduleDAG *Graph) { + if (EI.isArtificialDep()) + return "color=cyan,style=dashed"; + if (EI.isCtrlDep()) + return "color=blue,style=dashed"; + return ""; + } + + static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) { + std::string Str; + raw_string_ostream SS(Str); + const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G); + const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? + static_cast<const ScheduleDAGMILive*>(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 *G) { + std::string Str("shape=Mrecord"); + const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G); + const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? + static_cast<const ScheduleDAGMILive*>(G)->getDFSResult() : nullptr; + if (DFS) { + Str += ",style=filled,fillcolor=\"#"; + Str += DOT::getColorString(DFS->getSubtreeID(N)); + Str += '"'; + } + return Str; + } +}; +} // namespace llvm +#endif // NDEBUG + +/// viewGraph - Pop up a ghostview window with the reachable parts of the DAG +/// rendered using 'dot'. +/// +void ScheduleDAGMI::viewGraph(const Twine &Name, const Twine &Title) { +#ifndef NDEBUG + ViewGraph(this, Name, false, Title); +#else + errs() << "ScheduleDAGMI::viewGraph is only available in debug builds on " + << "systems with Graphviz or gv!\n"; +#endif // NDEBUG +} + +/// Out-of-line implementation with no arguments is handy for gdb. +void ScheduleDAGMI::viewGraph() { + viewGraph(getDAGName(), "Scheduling-Units Graph for " + getDAGName()); +} |