X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FPostRASchedulerList.cpp;h=b95e7c3042ed0dfa8fe4b2092aafbe19f5196a06;hb=b586add5e0562ed969c821d0126a22639a267d69;hp=706f5f2df0b0e4eaf71161e276300ba0c9c28e9c;hpb=c83da2f9e389332b9cf8eae9d823f745be5624b8;p=oota-llvm.git diff --git a/lib/CodeGen/PostRASchedulerList.cpp b/lib/CodeGen/PostRASchedulerList.cpp index 706f5f2df0b..b95e7c3042e 100644 --- a/lib/CodeGen/PostRASchedulerList.cpp +++ b/lib/CodeGen/PostRASchedulerList.cpp @@ -18,52 +18,52 @@ // //===----------------------------------------------------------------------===// -#define DEBUG_TYPE "post-RA-sched" -#include "ExactHazardRecognizer.h" -#include "SimpleHazardRecognizer.h" -#include "ScheduleDAGInstrs.h" #include "llvm/CodeGen/Passes.h" +#include "AggressiveAntiDepBreaker.h" +#include "AntiDepBreaker.h" +#include "CriticalAntiDepBreaker.h" +#include "llvm/ADT/BitVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/Analysis/AliasAnalysis.h" #include "llvm/CodeGen/LatencyPriorityQueue.h" -#include "llvm/CodeGen/SchedulerRegistry.h" #include "llvm/CodeGen/MachineDominators.h" #include "llvm/CodeGen/MachineFrameInfo.h" #include "llvm/CodeGen/MachineFunctionPass.h" #include "llvm/CodeGen/MachineLoopInfo.h" #include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/CodeGen/RegisterClassInfo.h" +#include "llvm/CodeGen/ScheduleDAGInstrs.h" #include "llvm/CodeGen/ScheduleHazardRecognizer.h" -#include "llvm/Analysis/AliasAnalysis.h" -#include "llvm/Target/TargetLowering.h" -#include "llvm/Target/TargetMachine.h" -#include "llvm/Target/TargetInstrInfo.h" -#include "llvm/Target/TargetRegisterInfo.h" -#include "llvm/Target/TargetSubtarget.h" -#include "llvm/Support/Compiler.h" +#include "llvm/CodeGen/SchedulerRegistry.h" +#include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/raw_ostream.h" -#include "llvm/ADT/Statistic.h" -#include -#include +#include "llvm/Target/TargetInstrInfo.h" +#include "llvm/Target/TargetLowering.h" +#include "llvm/Target/TargetMachine.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include "llvm/Target/TargetSubtargetInfo.h" using namespace llvm; +#define DEBUG_TYPE "post-RA-sched" + STATISTIC(NumNoops, "Number of noops inserted"); STATISTIC(NumStalls, "Number of pipeline stalls"); +STATISTIC(NumFixedAnti, "Number of fixed anti-dependencies"); // Post-RA scheduling is enabled with -// TargetSubtarget.enablePostRAScheduler(). This flag can be used to +// TargetSubtargetInfo.enablePostRAScheduler(). This flag can be used to // override the target. static cl::opt EnablePostRAScheduler("post-RA-scheduler", cl::desc("Enable scheduling after register allocation"), cl::init(false), cl::Hidden); -static cl::opt +static cl::opt EnableAntiDepBreaking("break-anti-dependencies", - cl::desc("Break post-RA scheduling anti-dependencies"), - cl::init(true), cl::Hidden); -static cl::opt -EnablePostRAHazardAvoidance("avoid-hazards", - cl::desc("Enable exact hazard avoidance"), - cl::init(true), cl::Hidden); + cl::desc("Break post-RA scheduling anti-dependencies: " + "\"critical\", \"all\", or \"none\""), + cl::init("none"), cl::Hidden); // If DebugDiv > 0 then only schedule MBB with (ID % DebugDiv) == DebugMod static cl::opt @@ -75,17 +75,21 @@ DebugMod("postra-sched-debugmod", cl::desc("Debug control MBBs that are scheduled"), cl::init(0), cl::Hidden); +AntiDepBreaker::~AntiDepBreaker() { } + namespace { - class VISIBILITY_HIDDEN PostRAScheduler : public MachineFunctionPass { - AliasAnalysis *AA; + class PostRAScheduler : public MachineFunctionPass { + const TargetInstrInfo *TII; + RegisterClassInfo RegClassInfo; public: static char ID; - PostRAScheduler() : MachineFunctionPass(&ID) {} + PostRAScheduler() : MachineFunctionPass(ID) {} - void getAnalysisUsage(AnalysisUsage &AU) const { + void getAnalysisUsage(AnalysisUsage &AU) const override { AU.setPreservesCFG(); AU.addRequired(); + AU.addRequired(); AU.addRequired(); AU.addPreserved(); AU.addRequired(); @@ -93,165 +97,213 @@ namespace { MachineFunctionPass::getAnalysisUsage(AU); } - const char *getPassName() const { - return "Post RA top-down list latency scheduler"; - } - - bool runOnMachineFunction(MachineFunction &Fn); + bool runOnMachineFunction(MachineFunction &Fn) override; + + bool enablePostRAScheduler( + const TargetSubtargetInfo &ST, CodeGenOpt::Level OptLevel, + TargetSubtargetInfo::AntiDepBreakMode &Mode, + TargetSubtargetInfo::RegClassVector &CriticalPathRCs) const; }; char PostRAScheduler::ID = 0; - class VISIBILITY_HIDDEN SchedulePostRATDList : public ScheduleDAGInstrs { + class SchedulePostRATDList : public ScheduleDAGInstrs { /// AvailableQueue - The priority queue to use for the available SUnits. /// LatencyPriorityQueue AvailableQueue; - + /// PendingQueue - This contains all of the instructions whose operands have /// been issued, but their results are not ready yet (due to the latency of /// the operation). Once the operands becomes available, the instruction is /// added to the AvailableQueue. std::vector PendingQueue; - /// Topo - A topological ordering for SUnits. - ScheduleDAGTopologicalSort Topo; - - /// AllocatableSet - The set of allocatable registers. - /// We'll be ignoring anti-dependencies on non-allocatable registers, - /// because they may not be safe to break. - const BitVector AllocatableSet; - /// HazardRec - The hazard recognizer to use. ScheduleHazardRecognizer *HazardRec; + /// AntiDepBreak - Anti-dependence breaking object, or NULL if none + AntiDepBreaker *AntiDepBreak; + /// AA - AliasAnalysis for making memory reference queries. AliasAnalysis *AA; - /// Classes - For live regs that are only used in one register class in a - /// live range, the register class. If the register is not live, the - /// corresponding value is null. If the register is live but used in - /// multiple register classes, the corresponding value is -1 casted to a - /// pointer. - const TargetRegisterClass * - Classes[TargetRegisterInfo::FirstVirtualRegister]; - - /// RegRegs - Map registers to all their references within a live range. - std::multimap RegRefs; + /// The schedule. Null SUnit*'s represent noop instructions. + std::vector Sequence; - /// KillIndices - The index of the most recent kill (proceding bottom-up), - /// or ~0u if the register is not live. - unsigned KillIndices[TargetRegisterInfo::FirstVirtualRegister]; - - /// DefIndices - The index of the most recent complete def (proceding bottom - /// up), or ~0u if the register is live. - unsigned DefIndices[TargetRegisterInfo::FirstVirtualRegister]; - - /// KeepRegs - A set of registers which are live and cannot be changed to - /// break anti-dependencies. - SmallSet KeepRegs; + /// The index in BB of RegionEnd. + /// + /// This is the instruction number from the top of the current block, not + /// the SlotIndex. It is only used by the AntiDepBreaker. + unsigned EndIndex; public: - SchedulePostRATDList(MachineFunction &MF, - const MachineLoopInfo &MLI, - const MachineDominatorTree &MDT, - ScheduleHazardRecognizer *HR, - AliasAnalysis *aa) - : ScheduleDAGInstrs(MF, MLI, MDT), Topo(SUnits), - AllocatableSet(TRI->getAllocatableSet(MF)), - HazardRec(HR), AA(aa) {} - - ~SchedulePostRATDList() { - delete HazardRec; - } + SchedulePostRATDList( + MachineFunction &MF, MachineLoopInfo &MLI, AliasAnalysis *AA, + const RegisterClassInfo &, + TargetSubtargetInfo::AntiDepBreakMode AntiDepMode, + SmallVectorImpl &CriticalPathRCs); + + ~SchedulePostRATDList(); - /// StartBlock - Initialize register live-range state for scheduling in + /// startBlock - Initialize register live-range state for scheduling in /// this block. /// - void StartBlock(MachineBasicBlock *BB); + void startBlock(MachineBasicBlock *BB) override; + + // Set the index of RegionEnd within the current BB. + void setEndIndex(unsigned EndIdx) { EndIndex = EndIdx; } + + /// Initialize the scheduler state for the next scheduling region. + void enterRegion(MachineBasicBlock *bb, + MachineBasicBlock::iterator begin, + MachineBasicBlock::iterator end, + unsigned regioninstrs) override; + + /// Notify that the scheduler has finished scheduling the current region. + void exitRegion() override; /// Schedule - Schedule the instruction range using list scheduling. /// - void Schedule(); - - /// FixupKills - Fix register kill flags that have been made - /// invalid due to scheduling - /// - void FixupKills(MachineBasicBlock *MBB); + void schedule() override; + + void EmitSchedule(); /// Observe - Update liveness information to account for the current /// instruction, which will not be scheduled. /// void Observe(MachineInstr *MI, unsigned Count); - /// FinishBlock - Clean up register live-range state. + /// finishBlock - Clean up register live-range state. /// - void FinishBlock(); + void finishBlock() override; private: - void PrescanInstruction(MachineInstr *MI); - void ScanInstruction(MachineInstr *MI, unsigned Count); void ReleaseSucc(SUnit *SU, SDep *SuccEdge); void ReleaseSuccessors(SUnit *SU); void ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle); void ListScheduleTopDown(); - bool BreakAntiDependencies(); - unsigned findSuitableFreeRegister(unsigned AntiDepReg, - unsigned LastNewReg, - const TargetRegisterClass *); - void StartBlockForKills(MachineBasicBlock *BB); - - // ToggleKillFlag - Toggle a register operand kill flag. Other - // adjustments may be made to the instruction if necessary. Return - // true if the operand has been deleted, false if not. - bool ToggleKillFlag(MachineInstr *MI, MachineOperand &MO); + + void dumpSchedule() const; + void emitNoop(unsigned CurCycle); }; } -/// isSchedulingBoundary - Test if the given instruction should be -/// considered a scheduling boundary. This primarily includes labels -/// and terminators. -/// -static bool isSchedulingBoundary(const MachineInstr *MI, - const MachineFunction &MF) { - // Terminators and labels can't be scheduled around. - if (MI->getDesc().isTerminator() || MI->isLabel()) - return true; - - // Don't attempt to schedule around any instruction that modifies - // a stack-oriented pointer, as it's unlikely to be profitable. This - // saves compile time, because it doesn't require every single - // stack slot reference to depend on the instruction that does the - // modification. - const TargetLowering &TLI = *MF.getTarget().getTargetLowering(); - if (MI->modifiesRegister(TLI.getStackPointerRegisterToSaveRestore())) - return true; - - return false; +char &llvm::PostRASchedulerID = PostRAScheduler::ID; + +INITIALIZE_PASS(PostRAScheduler, "post-RA-sched", + "Post RA top-down list latency scheduler", false, false) + +SchedulePostRATDList::SchedulePostRATDList( + MachineFunction &MF, MachineLoopInfo &MLI, AliasAnalysis *AA, + const RegisterClassInfo &RCI, + TargetSubtargetInfo::AntiDepBreakMode AntiDepMode, + SmallVectorImpl &CriticalPathRCs) + : ScheduleDAGInstrs(MF, &MLI, /*IsPostRA=*/true), AA(AA), EndIndex(0) { + + const TargetMachine &TM = MF.getTarget(); + const InstrItineraryData *InstrItins = + TM.getSubtargetImpl()->getInstrItineraryData(); + HazardRec = + TM.getSubtargetImpl()->getInstrInfo()->CreateTargetPostRAHazardRecognizer( + InstrItins, this); + + assert((AntiDepMode == TargetSubtargetInfo::ANTIDEP_NONE || + MRI.tracksLiveness()) && + "Live-ins must be accurate for anti-dependency breaking"); + AntiDepBreak = + ((AntiDepMode == TargetSubtargetInfo::ANTIDEP_ALL) ? + (AntiDepBreaker *)new AggressiveAntiDepBreaker(MF, RCI, CriticalPathRCs) : + ((AntiDepMode == TargetSubtargetInfo::ANTIDEP_CRITICAL) ? + (AntiDepBreaker *)new CriticalAntiDepBreaker(MF, RCI) : nullptr)); +} + +SchedulePostRATDList::~SchedulePostRATDList() { + delete HazardRec; + delete AntiDepBreak; +} + +/// Initialize state associated with the next scheduling region. +void SchedulePostRATDList::enterRegion(MachineBasicBlock *bb, + MachineBasicBlock::iterator begin, + MachineBasicBlock::iterator end, + unsigned regioninstrs) { + ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs); + Sequence.clear(); +} + +/// Print the schedule before exiting the region. +void SchedulePostRATDList::exitRegion() { + DEBUG({ + dbgs() << "*** Final schedule ***\n"; + dumpSchedule(); + dbgs() << '\n'; + }); + ScheduleDAGInstrs::exitRegion(); +} + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +/// dumpSchedule - dump the scheduled Sequence. +void SchedulePostRATDList::dumpSchedule() const { + for (unsigned i = 0, e = Sequence.size(); i != e; i++) { + if (SUnit *SU = Sequence[i]) + SU->dump(this); + else + dbgs() << "**** NOOP ****\n"; + } +} +#endif + +bool PostRAScheduler::enablePostRAScheduler( + const TargetSubtargetInfo &ST, + CodeGenOpt::Level OptLevel, + TargetSubtargetInfo::AntiDepBreakMode &Mode, + TargetSubtargetInfo::RegClassVector &CriticalPathRCs) const { + Mode = ST.getAntiDepBreakMode(); + ST.getCriticalPathRCs(CriticalPathRCs); + return ST.enablePostMachineScheduler() && + OptLevel >= ST.getOptLevelToEnablePostRAScheduler(); } bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) { - AA = &getAnalysis(); + if (skipOptnoneFunction(*Fn.getFunction())) + return false; + + TII = Fn.getSubtarget().getInstrInfo(); + MachineLoopInfo &MLI = getAnalysis(); + AliasAnalysis *AA = &getAnalysis(); + TargetPassConfig *PassConfig = &getAnalysis(); + + RegClassInfo.runOnMachineFunction(Fn); // Check for explicit enable/disable of post-ra scheduling. + TargetSubtargetInfo::AntiDepBreakMode AntiDepMode = + TargetSubtargetInfo::ANTIDEP_NONE; + SmallVector CriticalPathRCs; if (EnablePostRAScheduler.getPosition() > 0) { if (!EnablePostRAScheduler) return false; } else { // Check that post-RA scheduling is enabled for this target. - const TargetSubtarget &ST = Fn.getTarget().getSubtarget(); - if (!ST.enablePostRAScheduler()) + // This may upgrade the AntiDepMode. + const TargetSubtargetInfo &ST = + Fn.getTarget().getSubtarget(); + if (!enablePostRAScheduler(ST, PassConfig->getOptLevel(), + AntiDepMode, CriticalPathRCs)) return false; } - DEBUG(errs() << "PostRAScheduler\n"); + // Check for antidep breaking override... + if (EnableAntiDepBreaking.getPosition() > 0) { + AntiDepMode = (EnableAntiDepBreaking == "all") + ? TargetSubtargetInfo::ANTIDEP_ALL + : ((EnableAntiDepBreaking == "critical") + ? TargetSubtargetInfo::ANTIDEP_CRITICAL + : TargetSubtargetInfo::ANTIDEP_NONE); + } - const MachineLoopInfo &MLI = getAnalysis(); - const MachineDominatorTree &MDT = getAnalysis(); - const InstrItineraryData &InstrItins = Fn.getTarget().getInstrItineraryData(); - ScheduleHazardRecognizer *HR = EnablePostRAHazardAvoidance ? - (ScheduleHazardRecognizer *)new ExactHazardRecognizer(InstrItins) : - (ScheduleHazardRecognizer *)new SimpleHazardRecognizer(); + DEBUG(dbgs() << "PostRAScheduler\n"); - SchedulePostRATDList Scheduler(Fn, MLI, MDT, HR, AA); + SchedulePostRATDList Scheduler(Fn, MLI, AA, RegClassInfo, AntiDepMode, + CriticalPathRCs); // Loop over all of the basic blocks for (MachineFunction::iterator MBB = Fn.begin(), MBBe = Fn.end(); @@ -262,157 +314,101 @@ bool PostRAScheduler::runOnMachineFunction(MachineFunction &Fn) { static int bbcnt = 0; if (bbcnt++ % DebugDiv != DebugMod) continue; - errs() << "*** DEBUG scheduling " << Fn.getFunction()->getNameStr() << - ":MBB ID#" << MBB->getNumber() << " ***\n"; + dbgs() << "*** DEBUG scheduling " << Fn.getName() + << ":BB#" << MBB->getNumber() << " ***\n"; } #endif // Initialize register live-range state for scheduling in this block. - Scheduler.StartBlock(MBB); + Scheduler.startBlock(MBB); // Schedule each sequence of instructions not interrupted by a label // or anything else that effectively needs to shut down scheduling. MachineBasicBlock::iterator Current = MBB->end(); unsigned Count = MBB->size(), CurrentCount = Count; for (MachineBasicBlock::iterator I = Current; I != MBB->begin(); ) { - MachineInstr *MI = prior(I); - if (isSchedulingBoundary(MI, Fn)) { - Scheduler.Run(MBB, I, Current, CurrentCount); - Scheduler.EmitSchedule(0); + MachineInstr *MI = std::prev(I); + --Count; + // Calls are not scheduling boundaries before register allocation, but + // post-ra we don't gain anything by scheduling across calls since we + // don't need to worry about register pressure. + if (MI->isCall() || TII->isSchedulingBoundary(MI, MBB, Fn)) { + Scheduler.enterRegion(MBB, I, Current, CurrentCount - Count); + Scheduler.setEndIndex(CurrentCount); + Scheduler.schedule(); + Scheduler.exitRegion(); + Scheduler.EmitSchedule(); Current = MI; - CurrentCount = Count - 1; + CurrentCount = Count; Scheduler.Observe(MI, CurrentCount); } I = MI; - --Count; + if (MI->isBundle()) + Count -= MI->getBundleSize(); } assert(Count == 0 && "Instruction count mismatch!"); assert((MBB->begin() == Current || CurrentCount != 0) && "Instruction count mismatch!"); - Scheduler.Run(MBB, MBB->begin(), Current, CurrentCount); - Scheduler.EmitSchedule(0); + Scheduler.enterRegion(MBB, MBB->begin(), Current, CurrentCount); + Scheduler.setEndIndex(CurrentCount); + Scheduler.schedule(); + Scheduler.exitRegion(); + Scheduler.EmitSchedule(); // Clean up register live-range state. - Scheduler.FinishBlock(); + Scheduler.finishBlock(); // Update register kills - Scheduler.FixupKills(MBB); + Scheduler.fixupKills(MBB); } return true; } - + /// StartBlock - Initialize register live-range state for scheduling in /// this block. /// -void SchedulePostRATDList::StartBlock(MachineBasicBlock *BB) { +void SchedulePostRATDList::startBlock(MachineBasicBlock *BB) { // Call the superclass. - ScheduleDAGInstrs::StartBlock(BB); + ScheduleDAGInstrs::startBlock(BB); - // Reset the hazard recognizer. + // Reset the hazard recognizer and anti-dep breaker. HazardRec->Reset(); - - // Clear out the register class data. - std::fill(Classes, array_endof(Classes), - static_cast(0)); - - // Initialize the indices to indicate that no registers are live. - std::fill(KillIndices, array_endof(KillIndices), ~0u); - std::fill(DefIndices, array_endof(DefIndices), BB->size()); - - // Clear "do not change" set. - KeepRegs.clear(); - - bool IsReturnBlock = (!BB->empty() && BB->back().getDesc().isReturn()); - - // Determine the live-out physregs for this block. - if (IsReturnBlock) { - // In a return block, examine the function live-out regs. - for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), - E = MRI.liveout_end(); I != E; ++I) { - unsigned Reg = *I; - Classes[Reg] = reinterpret_cast(-1); - KillIndices[Reg] = BB->size(); - DefIndices[Reg] = ~0u; - // Repeat, for all aliases. - for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { - unsigned AliasReg = *Alias; - Classes[AliasReg] = reinterpret_cast(-1); - KillIndices[AliasReg] = BB->size(); - DefIndices[AliasReg] = ~0u; - } - } - } else { - // In a non-return block, examine the live-in regs of all successors. - for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), - SE = BB->succ_end(); SI != SE; ++SI) - for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), - E = (*SI)->livein_end(); I != E; ++I) { - unsigned Reg = *I; - Classes[Reg] = reinterpret_cast(-1); - KillIndices[Reg] = BB->size(); - DefIndices[Reg] = ~0u; - // Repeat, for all aliases. - for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { - unsigned AliasReg = *Alias; - Classes[AliasReg] = reinterpret_cast(-1); - KillIndices[AliasReg] = BB->size(); - DefIndices[AliasReg] = ~0u; - } - } - } - - // Mark live-out callee-saved registers. In a return block this is - // all callee-saved registers. In non-return this is any - // callee-saved register that is not saved in the prolog. - const MachineFrameInfo *MFI = MF.getFrameInfo(); - BitVector Pristine = MFI->getPristineRegs(BB); - for (const unsigned *I = TRI->getCalleeSavedRegs(); *I; ++I) { - unsigned Reg = *I; - if (!IsReturnBlock && !Pristine.test(Reg)) continue; - Classes[Reg] = reinterpret_cast(-1); - KillIndices[Reg] = BB->size(); - DefIndices[Reg] = ~0u; - // Repeat, for all aliases. - for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { - unsigned AliasReg = *Alias; - Classes[AliasReg] = reinterpret_cast(-1); - KillIndices[AliasReg] = BB->size(); - DefIndices[AliasReg] = ~0u; - } - } + if (AntiDepBreak) + AntiDepBreak->StartBlock(BB); } /// Schedule - Schedule the instruction range using list scheduling. /// -void SchedulePostRATDList::Schedule() { - DEBUG(errs() << "********** List Scheduling **********\n"); - +void SchedulePostRATDList::schedule() { // Build the scheduling graph. - BuildSchedGraph(AA); + buildSchedGraph(AA); - if (EnableAntiDepBreaking) { - if (BreakAntiDependencies()) { + if (AntiDepBreak) { + unsigned Broken = + AntiDepBreak->BreakAntiDependencies(SUnits, RegionBegin, RegionEnd, + EndIndex, DbgValues); + + if (Broken != 0) { // We made changes. Update the dependency graph. // Theoretically we could update the graph in place: // When a live range is changed to use a different register, remove // the def's anti-dependence *and* output-dependence edges due to // that register, and add new anti-dependence and output-dependence // edges based on the next live range of the register. - SUnits.clear(); - EntrySU = SUnit(); - ExitSU = SUnit(); - BuildSchedGraph(AA); + ScheduleDAG::clearDAG(); + buildSchedGraph(AA); + + NumFixedAnti += Broken; } } + DEBUG(dbgs() << "********** List Scheduling **********\n"); DEBUG(for (unsigned su = 0, e = SUnits.size(); su != e; ++su) SUnits[su].dumpAll(this)); AvailableQueue.initNodes(SUnits); - ListScheduleTopDown(); - AvailableQueue.releaseState(); } @@ -420,605 +416,18 @@ void SchedulePostRATDList::Schedule() { /// instruction, which will not be scheduled. /// void SchedulePostRATDList::Observe(MachineInstr *MI, unsigned Count) { - assert(Count < InsertPosIndex && "Instruction index out of expected range!"); - - // Any register which was defined within the previous scheduling region - // may have been rescheduled and its lifetime may overlap with registers - // in ways not reflected in our current liveness state. For each such - // register, adjust the liveness state to be conservatively correct. - for (unsigned Reg = 0; Reg != TargetRegisterInfo::FirstVirtualRegister; ++Reg) - if (DefIndices[Reg] < InsertPosIndex && DefIndices[Reg] >= Count) { - assert(KillIndices[Reg] == ~0u && "Clobbered register is live!"); - // Mark this register to be non-renamable. - Classes[Reg] = reinterpret_cast(-1); - // Move the def index to the end of the previous region, to reflect - // that the def could theoretically have been scheduled at the end. - DefIndices[Reg] = InsertPosIndex; - } - - PrescanInstruction(MI); - ScanInstruction(MI, Count); + if (AntiDepBreak) + AntiDepBreak->Observe(MI, Count, EndIndex); } /// FinishBlock - Clean up register live-range state. /// -void SchedulePostRATDList::FinishBlock() { - RegRefs.clear(); +void SchedulePostRATDList::finishBlock() { + if (AntiDepBreak) + AntiDepBreak->FinishBlock(); // Call the superclass. - ScheduleDAGInstrs::FinishBlock(); -} - -/// CriticalPathStep - Return the next SUnit after SU on the bottom-up -/// critical path. -static SDep *CriticalPathStep(SUnit *SU) { - SDep *Next = 0; - unsigned NextDepth = 0; - // Find the predecessor edge with the greatest depth. - for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end(); - P != PE; ++P) { - SUnit *PredSU = P->getSUnit(); - unsigned PredLatency = P->getLatency(); - unsigned PredTotalLatency = PredSU->getDepth() + PredLatency; - // In the case of a latency tie, prefer an anti-dependency edge over - // other types of edges. - if (NextDepth < PredTotalLatency || - (NextDepth == PredTotalLatency && P->getKind() == SDep::Anti)) { - NextDepth = PredTotalLatency; - Next = &*P; - } - } - return Next; -} - -void SchedulePostRATDList::PrescanInstruction(MachineInstr *MI) { - // Scan the register operands for this instruction and update - // Classes and RegRefs. - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) continue; - const TargetRegisterClass *NewRC = 0; - - if (i < MI->getDesc().getNumOperands()) - NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI); - - // For now, only allow the register to be changed if its register - // class is consistent across all uses. - if (!Classes[Reg] && NewRC) - Classes[Reg] = NewRC; - else if (!NewRC || Classes[Reg] != NewRC) - Classes[Reg] = reinterpret_cast(-1); - - // Now check for aliases. - for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { - // If an alias of the reg is used during the live range, give up. - // Note that this allows us to skip checking if AntiDepReg - // overlaps with any of the aliases, among other things. - unsigned AliasReg = *Alias; - if (Classes[AliasReg]) { - Classes[AliasReg] = reinterpret_cast(-1); - Classes[Reg] = reinterpret_cast(-1); - } - } - - // If we're still willing to consider this register, note the reference. - if (Classes[Reg] != reinterpret_cast(-1)) - RegRefs.insert(std::make_pair(Reg, &MO)); - - // It's not safe to change register allocation for source operands of - // that have special allocation requirements. - if (MO.isUse() && MI->getDesc().hasExtraSrcRegAllocReq()) { - if (KeepRegs.insert(Reg)) { - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) - KeepRegs.insert(*Subreg); - } - } - } -} - -void SchedulePostRATDList::ScanInstruction(MachineInstr *MI, - unsigned Count) { - // Update liveness. - // Proceding upwards, registers that are defed but not used in this - // instruction are now dead. - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) continue; - if (!MO.isDef()) continue; - // Ignore two-addr defs. - if (MI->isRegTiedToUseOperand(i)) continue; - - DefIndices[Reg] = Count; - KillIndices[Reg] = ~0u; - assert(((KillIndices[Reg] == ~0u) != - (DefIndices[Reg] == ~0u)) && - "Kill and Def maps aren't consistent for Reg!"); - KeepRegs.erase(Reg); - Classes[Reg] = 0; - RegRefs.erase(Reg); - // Repeat, for all subregs. - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - unsigned SubregReg = *Subreg; - DefIndices[SubregReg] = Count; - KillIndices[SubregReg] = ~0u; - KeepRegs.erase(SubregReg); - Classes[SubregReg] = 0; - RegRefs.erase(SubregReg); - } - // Conservatively mark super-registers as unusable. - for (const unsigned *Super = TRI->getSuperRegisters(Reg); - *Super; ++Super) { - unsigned SuperReg = *Super; - Classes[SuperReg] = reinterpret_cast(-1); - } - } - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) continue; - if (!MO.isUse()) continue; - - const TargetRegisterClass *NewRC = 0; - if (i < MI->getDesc().getNumOperands()) - NewRC = MI->getDesc().OpInfo[i].getRegClass(TRI); - - // For now, only allow the register to be changed if its register - // class is consistent across all uses. - if (!Classes[Reg] && NewRC) - Classes[Reg] = NewRC; - else if (!NewRC || Classes[Reg] != NewRC) - Classes[Reg] = reinterpret_cast(-1); - - RegRefs.insert(std::make_pair(Reg, &MO)); - - // It wasn't previously live but now it is, this is a kill. - if (KillIndices[Reg] == ~0u) { - KillIndices[Reg] = Count; - DefIndices[Reg] = ~0u; - assert(((KillIndices[Reg] == ~0u) != - (DefIndices[Reg] == ~0u)) && - "Kill and Def maps aren't consistent for Reg!"); - } - // Repeat, for all aliases. - for (const unsigned *Alias = TRI->getAliasSet(Reg); *Alias; ++Alias) { - unsigned AliasReg = *Alias; - if (KillIndices[AliasReg] == ~0u) { - KillIndices[AliasReg] = Count; - DefIndices[AliasReg] = ~0u; - } - } - } -} - -unsigned -SchedulePostRATDList::findSuitableFreeRegister(unsigned AntiDepReg, - unsigned LastNewReg, - const TargetRegisterClass *RC) { - for (TargetRegisterClass::iterator R = RC->allocation_order_begin(MF), - RE = RC->allocation_order_end(MF); R != RE; ++R) { - unsigned NewReg = *R; - // Don't replace a register with itself. - if (NewReg == AntiDepReg) continue; - // Don't replace a register with one that was recently used to repair - // an anti-dependence with this AntiDepReg, because that would - // re-introduce that anti-dependence. - if (NewReg == LastNewReg) continue; - // If NewReg is dead and NewReg's most recent def is not before - // AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg. - assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u)) && - "Kill and Def maps aren't consistent for AntiDepReg!"); - assert(((KillIndices[NewReg] == ~0u) != (DefIndices[NewReg] == ~0u)) && - "Kill and Def maps aren't consistent for NewReg!"); - if (KillIndices[NewReg] != ~0u || - Classes[NewReg] == reinterpret_cast(-1) || - KillIndices[AntiDepReg] > DefIndices[NewReg]) - continue; - return NewReg; - } - - // No registers are free and available! - return 0; -} - -/// BreakAntiDependencies - Identifiy anti-dependencies along the critical path -/// of the ScheduleDAG and break them by renaming registers. -/// -bool SchedulePostRATDList::BreakAntiDependencies() { - // The code below assumes that there is at least one instruction, - // so just duck out immediately if the block is empty. - if (SUnits.empty()) return false; - - // Find the node at the bottom of the critical path. - SUnit *Max = 0; - for (unsigned i = 0, e = SUnits.size(); i != e; ++i) { - SUnit *SU = &SUnits[i]; - if (!Max || SU->getDepth() + SU->Latency > Max->getDepth() + Max->Latency) - Max = SU; - } - -#ifndef NDEBUG - { - DEBUG(errs() << "Critical path has total latency " - << (Max->getDepth() + Max->Latency) << "\n"); - DEBUG(errs() << "Available regs:"); - for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) { - if (KillIndices[Reg] == ~0u) - DEBUG(errs() << " " << TRI->getName(Reg)); - } - DEBUG(errs() << '\n'); - } -#endif - - // Track progress along the critical path through the SUnit graph as we walk - // the instructions. - SUnit *CriticalPathSU = Max; - MachineInstr *CriticalPathMI = CriticalPathSU->getInstr(); - - // Consider this pattern: - // A = ... - // ... = A - // A = ... - // ... = A - // A = ... - // ... = A - // A = ... - // ... = A - // There are three anti-dependencies here, and without special care, - // we'd break all of them using the same register: - // A = ... - // ... = A - // B = ... - // ... = B - // B = ... - // ... = B - // B = ... - // ... = B - // because at each anti-dependence, B is the first register that - // isn't A which is free. This re-introduces anti-dependencies - // at all but one of the original anti-dependencies that we were - // trying to break. To avoid this, keep track of the most recent - // register that each register was replaced with, avoid - // using it to repair an anti-dependence on the same register. - // This lets us produce this: - // A = ... - // ... = A - // B = ... - // ... = B - // C = ... - // ... = C - // B = ... - // ... = B - // This still has an anti-dependence on B, but at least it isn't on the - // original critical path. - // - // TODO: If we tracked more than one register here, we could potentially - // fix that remaining critical edge too. This is a little more involved, - // because unlike the most recent register, less recent registers should - // still be considered, though only if no other registers are available. - unsigned LastNewReg[TargetRegisterInfo::FirstVirtualRegister] = {}; - - // Attempt to break anti-dependence edges on the critical path. Walk the - // instructions from the bottom up, tracking information about liveness - // as we go to help determine which registers are available. - bool Changed = false; - unsigned Count = InsertPosIndex - 1; - for (MachineBasicBlock::iterator I = InsertPos, E = Begin; - I != E; --Count) { - MachineInstr *MI = --I; - - // Check if this instruction has a dependence on the critical path that - // is an anti-dependence that we may be able to break. If it is, set - // AntiDepReg to the non-zero register associated with the anti-dependence. - // - // We limit our attention to the critical path as a heuristic to avoid - // breaking anti-dependence edges that aren't going to significantly - // impact the overall schedule. There are a limited number of registers - // and we want to save them for the important edges. - // - // TODO: Instructions with multiple defs could have multiple - // anti-dependencies. The current code here only knows how to break one - // edge per instruction. Note that we'd have to be able to break all of - // the anti-dependencies in an instruction in order to be effective. - unsigned AntiDepReg = 0; - if (MI == CriticalPathMI) { - if (SDep *Edge = CriticalPathStep(CriticalPathSU)) { - SUnit *NextSU = Edge->getSUnit(); - - // Only consider anti-dependence edges. - if (Edge->getKind() == SDep::Anti) { - AntiDepReg = Edge->getReg(); - assert(AntiDepReg != 0 && "Anti-dependence on reg0?"); - if (!AllocatableSet.test(AntiDepReg)) - // Don't break anti-dependencies on non-allocatable registers. - AntiDepReg = 0; - else if (KeepRegs.count(AntiDepReg)) - // Don't break anti-dependencies if an use down below requires - // this exact register. - AntiDepReg = 0; - else { - // If the SUnit has other dependencies on the SUnit that it - // anti-depends on, don't bother breaking the anti-dependency - // since those edges would prevent such units from being - // scheduled past each other regardless. - // - // Also, if there are dependencies on other SUnits with the - // same register as the anti-dependency, don't attempt to - // break it. - for (SUnit::pred_iterator P = CriticalPathSU->Preds.begin(), - PE = CriticalPathSU->Preds.end(); P != PE; ++P) - if (P->getSUnit() == NextSU ? - (P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) : - (P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) { - AntiDepReg = 0; - break; - } - } - } - CriticalPathSU = NextSU; - CriticalPathMI = CriticalPathSU->getInstr(); - } else { - // We've reached the end of the critical path. - CriticalPathSU = 0; - CriticalPathMI = 0; - } - } - - PrescanInstruction(MI); - - if (MI->getDesc().hasExtraDefRegAllocReq()) - // If this instruction's defs have special allocation requirement, don't - // break this anti-dependency. - AntiDepReg = 0; - else if (AntiDepReg) { - // If this instruction has a use of AntiDepReg, breaking it - // is invalid. - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) continue; - if (MO.isUse() && AntiDepReg == Reg) { - AntiDepReg = 0; - break; - } - } - } - - // Determine AntiDepReg's register class, if it is live and is - // consistently used within a single class. - const TargetRegisterClass *RC = AntiDepReg != 0 ? Classes[AntiDepReg] : 0; - assert((AntiDepReg == 0 || RC != NULL) && - "Register should be live if it's causing an anti-dependence!"); - if (RC == reinterpret_cast(-1)) - AntiDepReg = 0; - - // Look for a suitable register to use to break the anti-depenence. - // - // TODO: Instead of picking the first free register, consider which might - // be the best. - if (AntiDepReg != 0) { - if (unsigned NewReg = findSuitableFreeRegister(AntiDepReg, - LastNewReg[AntiDepReg], - RC)) { - DEBUG(errs() << "Breaking anti-dependence edge on " - << TRI->getName(AntiDepReg) - << " with " << RegRefs.count(AntiDepReg) << " references" - << " using " << TRI->getName(NewReg) << "!\n"); - - // Update the references to the old register to refer to the new - // register. - std::pair::iterator, - std::multimap::iterator> - Range = RegRefs.equal_range(AntiDepReg); - for (std::multimap::iterator - Q = Range.first, QE = Range.second; Q != QE; ++Q) - Q->second->setReg(NewReg); - - // We just went back in time and modified history; the - // liveness information for the anti-depenence reg is now - // inconsistent. Set the state as if it were dead. - Classes[NewReg] = Classes[AntiDepReg]; - DefIndices[NewReg] = DefIndices[AntiDepReg]; - KillIndices[NewReg] = KillIndices[AntiDepReg]; - assert(((KillIndices[NewReg] == ~0u) != - (DefIndices[NewReg] == ~0u)) && - "Kill and Def maps aren't consistent for NewReg!"); - - Classes[AntiDepReg] = 0; - DefIndices[AntiDepReg] = KillIndices[AntiDepReg]; - KillIndices[AntiDepReg] = ~0u; - assert(((KillIndices[AntiDepReg] == ~0u) != - (DefIndices[AntiDepReg] == ~0u)) && - "Kill and Def maps aren't consistent for AntiDepReg!"); - - RegRefs.erase(AntiDepReg); - Changed = true; - LastNewReg[AntiDepReg] = NewReg; - } - } - - ScanInstruction(MI, Count); - } - - return Changed; -} - -/// StartBlockForKills - Initialize register live-range state for updating kills -/// -void SchedulePostRATDList::StartBlockForKills(MachineBasicBlock *BB) { - // Initialize the indices to indicate that no registers are live. - std::fill(KillIndices, array_endof(KillIndices), ~0u); - - // Determine the live-out physregs for this block. - if (!BB->empty() && BB->back().getDesc().isReturn()) { - // In a return block, examine the function live-out regs. - for (MachineRegisterInfo::liveout_iterator I = MRI.liveout_begin(), - E = MRI.liveout_end(); I != E; ++I) { - unsigned Reg = *I; - KillIndices[Reg] = BB->size(); - // Repeat, for all subregs. - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - KillIndices[*Subreg] = BB->size(); - } - } - } - else { - // In a non-return block, examine the live-in regs of all successors. - for (MachineBasicBlock::succ_iterator SI = BB->succ_begin(), - SE = BB->succ_end(); SI != SE; ++SI) { - for (MachineBasicBlock::livein_iterator I = (*SI)->livein_begin(), - E = (*SI)->livein_end(); I != E; ++I) { - unsigned Reg = *I; - KillIndices[Reg] = BB->size(); - // Repeat, for all subregs. - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - KillIndices[*Subreg] = BB->size(); - } - } - } - } -} - -bool SchedulePostRATDList::ToggleKillFlag(MachineInstr *MI, - MachineOperand &MO) { - // Setting kill flag... - if (!MO.isKill()) { - MO.setIsKill(true); - return false; - } - - // If MO itself is live, clear the kill flag... - if (KillIndices[MO.getReg()] != ~0u) { - MO.setIsKill(false); - return false; - } - - // If any subreg of MO is live, then create an imp-def for that - // subreg and keep MO marked as killed. - MO.setIsKill(false); - bool AllDead = true; - const unsigned SuperReg = MO.getReg(); - for (const unsigned *Subreg = TRI->getSubRegisters(SuperReg); - *Subreg; ++Subreg) { - if (KillIndices[*Subreg] != ~0u) { - MI->addOperand(MachineOperand::CreateReg(*Subreg, - true /*IsDef*/, - true /*IsImp*/, - false /*IsKill*/, - false /*IsDead*/)); - AllDead = false; - } - } - - if(AllDead) - MO.setIsKill(true); - return false; -} - -/// FixupKills - Fix the register kill flags, they may have been made -/// incorrect by instruction reordering. -/// -void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) { - DEBUG(errs() << "Fixup kills for BB ID#" << MBB->getNumber() << '\n'); - - std::set killedRegs; - BitVector ReservedRegs = TRI->getReservedRegs(MF); - - StartBlockForKills(MBB); - - // Examine block from end to start... - unsigned Count = MBB->size(); - for (MachineBasicBlock::iterator I = MBB->end(), E = MBB->begin(); - I != E; --Count) { - MachineInstr *MI = --I; - - // Update liveness. Registers that are defed but not used in this - // instruction are now dead. Mark register and all subregs as they - // are completely defined. - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg()) continue; - unsigned Reg = MO.getReg(); - if (Reg == 0) continue; - if (!MO.isDef()) continue; - // Ignore two-addr defs. - if (MI->isRegTiedToUseOperand(i)) continue; - - KillIndices[Reg] = ~0u; - - // Repeat for all subregs. - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - KillIndices[*Subreg] = ~0u; - } - } - - // Examine all used registers and set/clear kill flag. When a - // register is used multiple times we only set the kill flag on - // the first use. - killedRegs.clear(); - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg() || !MO.isUse()) continue; - unsigned Reg = MO.getReg(); - if ((Reg == 0) || ReservedRegs.test(Reg)) continue; - - bool kill = false; - if (killedRegs.find(Reg) == killedRegs.end()) { - kill = true; - // A register is not killed if any subregs are live... - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - if (KillIndices[*Subreg] != ~0u) { - kill = false; - break; - } - } - - // If subreg is not live, then register is killed if it became - // live in this instruction - if (kill) - kill = (KillIndices[Reg] == ~0u); - } - - if (MO.isKill() != kill) { - bool removed = ToggleKillFlag(MI, MO); - if (removed) { - DEBUG(errs() << "Fixed in "); - } else { - DEBUG(errs() << "Fixed " << MO << " in "); - } - DEBUG(MI->dump()); - } - - killedRegs.insert(Reg); - } - - // Mark any used register (that is not using undef) and subregs as - // now live... - for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) { - MachineOperand &MO = MI->getOperand(i); - if (!MO.isReg() || !MO.isUse() || MO.isUndef()) continue; - unsigned Reg = MO.getReg(); - if ((Reg == 0) || ReservedRegs.test(Reg)) continue; - - KillIndices[Reg] = Count; - - for (const unsigned *Subreg = TRI->getSubRegisters(Reg); - *Subreg; ++Subreg) { - KillIndices[*Subreg] = Count; - } - } - } + ScheduleDAGInstrs::finishBlock(); } //===----------------------------------------------------------------------===// @@ -1026,25 +435,35 @@ void SchedulePostRATDList::FixupKills(MachineBasicBlock *MBB) { //===----------------------------------------------------------------------===// /// ReleaseSucc - Decrement the NumPredsLeft count of a successor. Add it to -/// the PendingQueue if the count reaches zero. Also update its cycle bound. +/// the PendingQueue if the count reaches zero. void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) { SUnit *SuccSU = SuccEdge->getSUnit(); + if (SuccEdge->isWeak()) { + --SuccSU->WeakPredsLeft; + return; + } #ifndef NDEBUG if (SuccSU->NumPredsLeft == 0) { - errs() << "*** Scheduling failed! ***\n"; + dbgs() << "*** Scheduling failed! ***\n"; SuccSU->dump(this); - errs() << " has been released too many times!\n"; - llvm_unreachable(0); + dbgs() << " has been released too many times!\n"; + llvm_unreachable(nullptr); } #endif --SuccSU->NumPredsLeft; - // Compute how many cycles it will be before this actually becomes - // available. This is the max of the start time of all predecessors plus - // their latencies. - SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency()); - + // Standard scheduler algorithms will recompute the depth of the successor + // here as such: + // SuccSU->setDepthToAtLeast(SU->getDepth() + SuccEdge->getLatency()); + // + // However, we lazily compute node depth instead. Note that + // ScheduleNodeTopDown has already updated the depth of this node which causes + // all descendents to be marked dirty. Setting the successor depth explicitly + // here would cause depth to be recomputed for all its ancestors. If the + // successor is not yet ready (because of a transitively redundant edge) then + // this causes depth computation to be quadratic in the size of the DAG. + // If all the node's predecessors are scheduled, this node is ready // to be scheduled. Ignore the special ExitSU node. if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU) @@ -1054,24 +473,34 @@ void SchedulePostRATDList::ReleaseSucc(SUnit *SU, SDep *SuccEdge) { /// ReleaseSuccessors - Call ReleaseSucc on each of SU's successors. void SchedulePostRATDList::ReleaseSuccessors(SUnit *SU) { for (SUnit::succ_iterator I = SU->Succs.begin(), E = SU->Succs.end(); - I != E; ++I) + I != E; ++I) { ReleaseSucc(SU, &*I); + } } /// ScheduleNodeTopDown - Add the node to the schedule. Decrement the pending /// count of its successors. If a successor pending count is zero, add it to /// the Available queue. void SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) { - DEBUG(errs() << "*** Scheduling [" << CurCycle << "]: "); + DEBUG(dbgs() << "*** Scheduling [" << CurCycle << "]: "); DEBUG(SU->dump(this)); - + Sequence.push_back(SU); - assert(CurCycle >= SU->getDepth() && "Node scheduled above its depth!"); + assert(CurCycle >= SU->getDepth() && + "Node scheduled above its depth!"); SU->setDepthToAtLeast(CurCycle); ReleaseSuccessors(SU); SU->isScheduled = true; - AvailableQueue.ScheduledNode(SU); + AvailableQueue.scheduledNode(SU); +} + +/// emitNoop - Add a noop to the current instruction sequence. +void SchedulePostRATDList::emitNoop(unsigned CurCycle) { + DEBUG(dbgs() << "*** Emitting noop in cycle " << CurCycle << '\n'); + HazardRec->EmitNoop(); + Sequence.push_back(nullptr); // NULL here means noop + ++NumNoops; } /// ListScheduleTopDown - The main loop of list scheduling for top-down @@ -1079,13 +508,19 @@ void SchedulePostRATDList::ScheduleNodeTopDown(SUnit *SU, unsigned CurCycle) { void SchedulePostRATDList::ListScheduleTopDown() { unsigned CurCycle = 0; + // We're scheduling top-down but we're visiting the regions in + // bottom-up order, so we don't know the hazards at the start of a + // region. So assume no hazards (this should usually be ok as most + // blocks are a single region). + HazardRec->Reset(); + // Release any successors of the special Entry node. ReleaseSuccessors(&EntrySU); - // All leaves to Available queue. + // Add all leaves to Available queue. for (unsigned i = 0, e = SUnits.size(); i != e; ++i) { // It is available if it has no predecessors. - if (SUnits[i].Preds.empty()) { + if (!SUnits[i].NumPredsLeft && !SUnits[i].isAvailable) { AvailableQueue.push(&SUnits[i]); SUnits[i].isAvailable = true; } @@ -1114,25 +549,29 @@ void SchedulePostRATDList::ListScheduleTopDown() { MinDepth = PendingQueue[i]->getDepth(); } - DEBUG(errs() << "\n*** Examining Available\n"; - LatencyPriorityQueue q = AvailableQueue; - while (!q.empty()) { - SUnit *su = q.pop(); - errs() << "Height " << su->getHeight() << ": "; - su->dump(this); - }); - - SUnit *FoundSUnit = 0; + DEBUG(dbgs() << "\n*** Examining Available\n"; AvailableQueue.dump(this)); + SUnit *FoundSUnit = nullptr, *NotPreferredSUnit = nullptr; bool HasNoopHazards = false; while (!AvailableQueue.empty()) { SUnit *CurSUnit = AvailableQueue.pop(); ScheduleHazardRecognizer::HazardType HT = - HazardRec->getHazardType(CurSUnit); + HazardRec->getHazardType(CurSUnit, 0/*no stalls*/); if (HT == ScheduleHazardRecognizer::NoHazard) { - FoundSUnit = CurSUnit; - break; + if (HazardRec->ShouldPreferAnother(CurSUnit)) { + if (!NotPreferredSUnit) { + // If this is the first non-preferred node for this cycle, then + // record it and continue searching for a preferred node. If this + // is not the first non-preferred node, then treat it as though + // there had been a hazard. + NotPreferredSUnit = CurSUnit; + continue; + } + } else { + FoundSUnit = CurSUnit; + break; + } } // Remember if this is a noop hazard. @@ -1141,44 +580,58 @@ void SchedulePostRATDList::ListScheduleTopDown() { NotReady.push_back(CurSUnit); } + // If we have a non-preferred node, push it back onto the available list. + // If we did not find a preferred node, then schedule this first + // non-preferred node. + if (NotPreferredSUnit) { + if (!FoundSUnit) { + DEBUG(dbgs() << "*** Will schedule a non-preferred instruction...\n"); + FoundSUnit = NotPreferredSUnit; + } else { + AvailableQueue.push(NotPreferredSUnit); + } + + NotPreferredSUnit = nullptr; + } + // Add the nodes that aren't ready back onto the available list. if (!NotReady.empty()) { AvailableQueue.push_all(NotReady); NotReady.clear(); } - // If we found a node to schedule, do it now. + // If we found a node to schedule... if (FoundSUnit) { + // If we need to emit noops prior to this instruction, then do so. + unsigned NumPreNoops = HazardRec->PreEmitNoops(FoundSUnit); + for (unsigned i = 0; i != NumPreNoops; ++i) + emitNoop(CurCycle); + + // ... schedule the node... ScheduleNodeTopDown(FoundSUnit, CurCycle); HazardRec->EmitInstruction(FoundSUnit); CycleHasInsts = true; - - // If we are using the target-specific hazards, then don't - // advance the cycle time just because we schedule a node. If - // the target allows it we can schedule multiple nodes in the - // same cycle. - if (!EnablePostRAHazardAvoidance) { - if (FoundSUnit->Latency) // Don't increment CurCycle for pseudo-ops! - ++CurCycle; + if (HazardRec->atIssueLimit()) { + DEBUG(dbgs() << "*** Max instructions per cycle " << CurCycle << '\n'); + HazardRec->AdvanceCycle(); + ++CurCycle; + CycleHasInsts = false; } } else { if (CycleHasInsts) { - DEBUG(errs() << "*** Finished cycle " << CurCycle << '\n'); + DEBUG(dbgs() << "*** Finished cycle " << CurCycle << '\n'); HazardRec->AdvanceCycle(); } else if (!HasNoopHazards) { // Otherwise, we have a pipeline stall, but no other problem, // just advance the current cycle and try again. - DEBUG(errs() << "*** Stall in cycle " << CurCycle << '\n'); + DEBUG(dbgs() << "*** Stall in cycle " << CurCycle << '\n'); HazardRec->AdvanceCycle(); ++NumStalls; } else { // Otherwise, we have no instructions to issue and we have instructions // that will fault if we don't do this right. This is the case for // processors without pipeline interlocks and other cases. - DEBUG(errs() << "*** Emitting noop in cycle " << CurCycle << '\n'); - HazardRec->EmitNoop(); - Sequence.push_back(0); // NULL here means noop - ++NumNoops; + emitNoop(CurCycle); } ++CurCycle; @@ -1187,14 +640,46 @@ void SchedulePostRATDList::ListScheduleTopDown() { } #ifndef NDEBUG - VerifySchedule(/*isBottomUp=*/false); -#endif + unsigned ScheduledNodes = VerifyScheduledDAG(/*isBottomUp=*/false); + unsigned Noops = 0; + for (unsigned i = 0, e = Sequence.size(); i != e; ++i) + if (!Sequence[i]) + ++Noops; + assert(Sequence.size() - Noops == ScheduledNodes && + "The number of nodes scheduled doesn't match the expected number!"); +#endif // NDEBUG } -//===----------------------------------------------------------------------===// -// Public Constructor Functions -//===----------------------------------------------------------------------===// +// EmitSchedule - Emit the machine code in scheduled order. +void SchedulePostRATDList::EmitSchedule() { + RegionBegin = RegionEnd; + + // If first instruction was a DBG_VALUE then put it back. + if (FirstDbgValue) + BB->splice(RegionEnd, BB, FirstDbgValue); + + // Then re-insert them according to the given schedule. + for (unsigned i = 0, e = Sequence.size(); i != e; i++) { + if (SUnit *SU = Sequence[i]) + BB->splice(RegionEnd, BB, SU->getInstr()); + else + // Null SUnit* is a noop. + TII->insertNoop(*BB, RegionEnd); + + // Update the Begin iterator, as the first instruction in the block + // may have been scheduled later. + if (i == 0) + RegionBegin = std::prev(RegionEnd); + } -FunctionPass *llvm::createPostRAScheduler() { - return new PostRAScheduler(); + // Reinsert any remaining debug_values. + for (std::vector >::iterator + DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) { + std::pair P = *std::prev(DI); + MachineInstr *DbgValue = P.first; + MachineBasicBlock::iterator OrigPrivMI = P.second; + BB->splice(++OrigPrivMI, BB, DbgValue); + } + DbgValues.clear(); + FirstDbgValue = nullptr; }