From fa989e7d432d170b3f92cbd87e2610b03babaea7 Mon Sep 17 00:00:00 2001 From: Andrew Trick Date: Sat, 15 Jun 2013 05:39:19 +0000 Subject: MI-Sched: heuristics using the new latency and machine model. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@184038 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/MachineScheduler.cpp | 564 +++++++++++++++++++++++---------------- 1 file changed, 330 insertions(+), 234 deletions(-) diff --git a/lib/CodeGen/MachineScheduler.cpp b/lib/CodeGen/MachineScheduler.cpp index c87a1be720..3f68caf228 100644 --- a/lib/CodeGen/MachineScheduler.cpp +++ b/lib/CodeGen/MachineScheduler.cpp @@ -1097,7 +1097,7 @@ void CopyConstrain::apply(ScheduleDAGMI *DAG) { } //===----------------------------------------------------------------------===// -// ConvergingScheduler - Implementation of the standard MachineSchedStrategy. +// ConvergingScheduler - Implementation of the generic MachineSchedStrategy. //===----------------------------------------------------------------------===// namespace { @@ -1185,32 +1185,21 @@ public: // Critical path through the DAG in expected latency. unsigned CriticalPath; + // Scaled count of micro-ops left to schedule. + unsigned RemIssueCount; + // Unscheduled resources SmallVector RemainingCounts; - // Critical resource for the unscheduled zone. - unsigned CritResIdx; - // Number of micro-ops left to schedule. - unsigned RemainingMicroOps; void reset() { CriticalPath = 0; + RemIssueCount = 0; RemainingCounts.clear(); - CritResIdx = 0; - RemainingMicroOps = 0; } SchedRemainder() { reset(); } void init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel); - - unsigned getMaxRemainingCount(const TargetSchedModel *SchedModel) const { - if (!SchedModel->hasInstrSchedModel()) - return 0; - - return std::max( - RemainingMicroOps * SchedModel->getMicroOpFactor(), - RemainingCounts[CritResIdx]); - } }; /// Each Scheduling boundary is associated with ready queues. It tracks the @@ -1231,7 +1220,12 @@ public: ScheduleHazardRecognizer *HazardRec; + /// Number of cycles it takes to issue the instructions scheduled in this + /// zone. It is defined as: scheduled-micro-ops / issue-width + stalls. + /// See getStalls(). unsigned CurrCycle; + + /// Micro-ops issued in the current cycle unsigned CurrMOps; /// MinReadyCycle - Cycle of the soonest available instruction. @@ -1241,21 +1235,30 @@ public: unsigned ExpectedLatency; // The latency of dependence chains leading into this zone. - // For each node scheduled: DLat = max DLat, N.Depth. + // For each node scheduled top-down: DLat = max DLat, N.Depth. // For each cycle scheduled: DLat -= 1. unsigned DependentLatency; - // Resources used in the scheduled zone beyond this boundary. - SmallVector ResourceCounts; + /// Count the scheduled (issued) micro-ops that can be retired by + /// time=CurrCycle assuming the first scheduled instr is retired at time=0. + unsigned RetiredMOps; + + // Count scheduled resources that have been executed. Resources are + // considered executed if they become ready in the time that it takes to + // saturate any resource including the one in question. Counts are scaled + // for direct comparison with other resources. Counts ca be compared with + // MOps * getMicroOpFactor and Latency * getLatencyFactor. + SmallVector ExecutedResCounts; + + /// Cache the max count for a single resource. + unsigned MaxExecutedResCount; // Cache the critical resources ID in this scheduled zone. - unsigned CritResIdx; + unsigned ZoneCritResIdx; // Is the scheduled region resource limited vs. latency limited. bool IsResourceLimited; - unsigned ExpectedCount; - #ifndef NDEBUG // Remember the greatest operand latency as an upper bound on the number of // times we should retry the pending queue because of a hazard. @@ -1276,16 +1279,16 @@ public: MinReadyCycle = UINT_MAX; ExpectedLatency = 0; DependentLatency = 0; - ResourceCounts.resize(1); - assert(!ResourceCounts[0] && "nonzero count for bad resource"); - CritResIdx = 0; + RetiredMOps = 0; + MaxExecutedResCount = 0; + ZoneCritResIdx = 0; IsResourceLimited = false; - ExpectedCount = 0; #ifndef NDEBUG MaxObservedLatency = 0; #endif // Reserve a zero-count for invalid CritResIdx. - ResourceCounts.resize(1); + ExecutedResCounts.resize(1); + assert(!ExecutedResCounts[0] && "nonzero count for bad resource"); } /// Pending queues extend the ready queues with the same ID and the @@ -1306,25 +1309,58 @@ public: return Available.getID() == ConvergingScheduler::TopQID; } + const char *getResourceName(unsigned PIdx) { + if (!PIdx) + return "MOps"; + return SchedModel->getProcResource(PIdx)->Name; + } + + /// Get the number of latency cycles "covered" by the scheduled + /// instructions. This is the larger of the critical path within the zone + /// and the number of cycles required to issue the instructions. + unsigned getScheduledLatency() const { + return std::max(ExpectedLatency, CurrCycle); + } + unsigned getUnscheduledLatency(SUnit *SU) const { - if (isTop()) - return SU->getHeight(); - return SU->getDepth() + SU->Latency; + return isTop() ? SU->getHeight() : SU->getDepth(); + } + + unsigned getResourceCount(unsigned ResIdx) const { + return ExecutedResCounts[ResIdx]; } + /// Get the scaled count of scheduled micro-ops and resources, including + /// executed resources. unsigned getCriticalCount() const { - return ResourceCounts[CritResIdx]; + if (!ZoneCritResIdx) + return RetiredMOps * SchedModel->getMicroOpFactor(); + return getResourceCount(ZoneCritResIdx); + } + + /// Get a scaled count for the minimum execution time of the scheduled + /// micro-ops that are ready to execute by getExecutedCount. Notice the + /// feedback loop. + unsigned getExecutedCount() const { + return std::max(CurrCycle * SchedModel->getLatencyFactor(), + MaxExecutedResCount); } bool checkHazard(SUnit *SU); - void setLatencyPolicy(CandPolicy &Policy); + unsigned findMaxLatency(ArrayRef ReadySUs); + + unsigned getOtherResourceCount(unsigned &OtherCritIdx); + + void setPolicy(CandPolicy &Policy, SchedBoundary &OtherZone); void releaseNode(SUnit *SU, unsigned ReadyCycle); - void bumpCycle(); + void bumpCycle(unsigned NextCycle); - void countResource(unsigned PIdx, unsigned Cycles); + void incExecutedResources(unsigned PIdx, unsigned Count); + + unsigned countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle); void bumpNode(SUnit *SU); @@ -1333,6 +1369,8 @@ public: void removeReady(SUnit *SU); SUnit *pickOnlyChoice(); + + void dumpScheduledState(); }; private: @@ -1369,15 +1407,6 @@ public: virtual void registerRoots(); protected: - void balanceZones( - ConvergingScheduler::SchedBoundary &CriticalZone, - ConvergingScheduler::SchedCandidate &CriticalCand, - ConvergingScheduler::SchedBoundary &OppositeZone, - ConvergingScheduler::SchedCandidate &OppositeCand); - - void checkResourceLimits(ConvergingScheduler::SchedCandidate &TopCand, - ConvergingScheduler::SchedCandidate &BotCand); - void tryCandidate(SchedCandidate &Cand, SchedCandidate &TryCand, SchedBoundary &Zone, @@ -1407,7 +1436,8 @@ init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { for (std::vector::iterator I = DAG->SUnits.begin(), E = DAG->SUnits.end(); I != E; ++I) { const MCSchedClassDesc *SC = DAG->getSchedClass(&*I); - RemainingMicroOps += SchedModel->getNumMicroOps(I->getInstr(), SC); + RemIssueCount += SchedModel->getNumMicroOps(I->getInstr(), SC) + * SchedModel->getMicroOpFactor(); for (TargetSchedModel::ProcResIter PI = SchedModel->getWriteProcResBegin(SC), PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { @@ -1416,17 +1446,6 @@ init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { RemainingCounts[PIdx] += (Factor * PI->Cycles); } } - for (unsigned PIdx = 0, PEnd = SchedModel->getNumProcResourceKinds(); - PIdx != PEnd; ++PIdx) { - if ((int)(RemainingCounts[PIdx] - RemainingCounts[CritResIdx]) - >= (int)SchedModel->getLatencyFactor()) { - CritResIdx = PIdx; - } - } - DEBUG(dbgs() << "Critical Resource: " - << SchedModel->getProcResource(CritResIdx)->Name - << ": " << RemainingCounts[CritResIdx] - << " / " << SchedModel->getLatencyFactor() << '\n'); } void ConvergingScheduler::SchedBoundary:: @@ -1436,7 +1455,7 @@ init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) { SchedModel = smodel; Rem = rem; if (SchedModel->hasInstrSchedModel()) - ResourceCounts.resize(SchedModel->getNumProcResourceKinds()); + ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds()); } void ConvergingScheduler::initialize(ScheduleDAGMI *dag) { @@ -1538,50 +1557,125 @@ bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) { return false; } -/// Compute the remaining latency to determine whether ILP should be increased. -void ConvergingScheduler::SchedBoundary::setLatencyPolicy(CandPolicy &Policy) { - DEBUG(dbgs() << " " << Available.getName() - << " DependentLatency " << DependentLatency << '\n'); - - // FIXME: compile time. In all, we visit four queues here one we should only - // need to visit the one that was last popped if we cache the result. - unsigned RemLatency = DependentLatency; - for (ReadyQueue::iterator I = Available.begin(), E = Available.end(); +// Find the unscheduled node in ReadySUs with the highest latency. +unsigned ConvergingScheduler::SchedBoundary:: +findMaxLatency(ArrayRef ReadySUs) { + SUnit *LateSU = 0; + unsigned RemLatency = 0; + for (ArrayRef::iterator I = ReadySUs.begin(), E = ReadySUs.end(); I != E; ++I) { unsigned L = getUnscheduledLatency(*I); if (L > RemLatency) { - DEBUG(dbgs() << " " << Available.getName() - << " RemLatency SU(" << (*I)->NodeNum << ") " << L << '\n'); RemLatency = L; + LateSU = *I; } } - for (ReadyQueue::iterator I = Pending.begin(), E = Pending.end(); - I != E; ++I) { - unsigned L = getUnscheduledLatency(*I); - if (L > RemLatency) - RemLatency = L; + if (LateSU) { + DEBUG(dbgs() << Available.getName() << " RemLatency SU(" + << LateSU->NodeNum << ") " << RemLatency << "c\n"); } - unsigned CriticalPathLimit = Rem->CriticalPath; - DEBUG(dbgs() << " " << Available.getName() - << " ExpectedLatency " << ExpectedLatency - << " CP Limit " << CriticalPathLimit << '\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 ConvergingScheduler::SchedBoundary:: +getOtherResourceCount(unsigned &OtherCritIdx) { + if (!SchedModel->hasInstrSchedModel()) + return 0; + + unsigned OtherCritCount = Rem->RemIssueCount + + (RetiredMOps * SchedModel->getMicroOpFactor()); + DEBUG(dbgs() << " " << Available.getName() << " + Remain MOps: " + << OtherCritCount / SchedModel->getMicroOpFactor() << '\n'); + OtherCritIdx = 0; + for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds(); + PIdx != PEnd; ++PIdx) { + unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx]; + if (OtherCount > OtherCritCount) { + OtherCritCount = OtherCount; + OtherCritIdx = PIdx; + } + } + if (OtherCritIdx) { + DEBUG(dbgs() << " " << Available.getName() << " + Remain CritRes: " + << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx) + << " " << getResourceName(OtherCritIdx) << "\n"); + } + return OtherCritCount; +} + +/// Set the CandPolicy for this zone given the current resources and latencies +/// inside and outside the zone. +void ConvergingScheduler::SchedBoundary::setPolicy(CandPolicy &Policy, + SchedBoundary &OtherZone) { + // Now that potential stalls have been considered, apply preemptive heuristics + // based on the the total latency and resources inside and outside this + // zone. + + // 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 = DependentLatency; + RemLatency = std::max(RemLatency, findMaxLatency(Available.elements())); + RemLatency = std::max(RemLatency, findMaxLatency(Pending.elements())); - if (RemLatency + std::max(ExpectedLatency, CurrCycle) >= CriticalPathLimit - && RemLatency > Rem->getMaxRemainingCount(SchedModel)) { - Policy.ReduceLatency = true; - DEBUG(dbgs() << " Increase ILP: " << Available.getName() << '\n'); + // Compute the critical resource outside the zone. + unsigned OtherCritIdx; + unsigned OtherCount = OtherZone.getOtherResourceCount(OtherCritIdx); + + bool OtherResLimited = false; + if (SchedModel->hasInstrSchedModel()) { + unsigned LFactor = SchedModel->getLatencyFactor(); + OtherResLimited = (int)(OtherCount - (RemLatency * LFactor)) > (int)LFactor; } + if (!OtherResLimited && (RemLatency + CurrCycle > Rem->CriticalPath)) { + Policy.ReduceLatency |= true; + DEBUG(dbgs() << " " << Available.getName() << " RemainingLatency " + << RemLatency << " + " << CurrCycle << "c > CritPath " + << Rem->CriticalPath << "\n"); + } + // If the same resource is limiting inside and outside the zone, do nothing. + if (IsResourceLimited && OtherResLimited && (ZoneCritResIdx == OtherCritIdx)) + return; + + DEBUG( + if (IsResourceLimited) { + dbgs() << " " << Available.getName() << " ResourceLimited: " + << getResourceName(ZoneCritResIdx) << "\n"; + } + if (OtherResLimited) + dbgs() << " RemainingLimit: " << getResourceName(OtherCritIdx); + if (!IsResourceLimited && !OtherResLimited) + dbgs() << " Latency limited both directions.\n"); + + if (IsResourceLimited && !Policy.ReduceResIdx) + Policy.ReduceResIdx = ZoneCritResIdx; + + if (OtherResLimited) + Policy.DemandResIdx = OtherCritIdx; } void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle) { - if (ReadyCycle < MinReadyCycle) MinReadyCycle = ReadyCycle; // Check for interlocks first. For the purpose of other heuristics, an // instruction that cannot issue appears as if it's not in the ReadyQueue. - if (ReadyCycle > CurrCycle || checkHazard(SU)) + bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; + if ((!IsBuffered && ReadyCycle > CurrCycle) || checkHazard(SU)) Pending.push(SU); else Available.push(SU); @@ -1591,16 +1685,17 @@ void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU, } /// Move the boundary of scheduled code by one cycle. -void ConvergingScheduler::SchedBoundary::bumpCycle() { - unsigned Width = SchedModel->getIssueWidth(); - CurrMOps = (CurrMOps <= Width) ? 0 : CurrMOps - Width; - - unsigned NextCycle = CurrCycle + 1; - assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized"); - if (MinReadyCycle > NextCycle) { - CurrMOps = 0; - NextCycle = MinReadyCycle; +void ConvergingScheduler::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 @@ -1620,34 +1715,52 @@ void ConvergingScheduler::SchedBoundary::bumpCycle() { } } CheckPending = true; - IsResourceLimited = getCriticalCount() > std::max(ExpectedLatency, CurrCycle); + unsigned LFactor = SchedModel->getLatencyFactor(); + IsResourceLimited = + (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) + > (int)LFactor; - DEBUG(dbgs() << " " << Available.getName() - << " Cycle: " << CurrCycle << '\n'); + DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n'); +} + +void ConvergingScheduler::SchedBoundary::incExecutedResources(unsigned PIdx, + unsigned Count) { + ExecutedResCounts[PIdx] += Count; + if (ExecutedResCounts[PIdx] > MaxExecutedResCount) + MaxExecutedResCount = ExecutedResCounts[PIdx]; } /// Add the given processor resource to this scheduled zone. -void ConvergingScheduler::SchedBoundary::countResource(unsigned PIdx, - unsigned Cycles) { +/// +/// \param Cycles indicates the number of consecutive (non-pipelined) cycles +/// during which this resource is consumed. +/// +/// \return the next cycle at which the instruction may execute without +/// oversubscribing resources. +unsigned ConvergingScheduler::SchedBoundary:: +countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle) { unsigned Factor = SchedModel->getResourceFactor(PIdx); - DEBUG(dbgs() << " " << SchedModel->getProcResource(PIdx)->Name - << " +(" << Cycles << "x" << Factor - << ") / " << SchedModel->getLatencyFactor() << '\n'); - unsigned Count = Factor * Cycles; - ResourceCounts[PIdx] += Count; + DEBUG(dbgs() << " " << getResourceName(PIdx) + << " +" << Cycles << "x" << Factor << "u\n"); + + // Update Executed resources counts. + incExecutedResources(PIdx, Count); assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted"); Rem->RemainingCounts[PIdx] -= Count; // Check if this resource exceeds the current critical resource by a full // cycle. If so, it becomes the critical resource. - if ((int)(ResourceCounts[PIdx] - ResourceCounts[CritResIdx]) - >= (int)SchedModel->getLatencyFactor()) { - CritResIdx = PIdx; + if (ZoneCritResIdx != PIdx + && ((int)(getResourceCount(PIdx) - getCriticalCount()) + >= (int)SchedModel->getLatencyFactor())) { + ZoneCritResIdx = PIdx; DEBUG(dbgs() << " *** Critical resource " - << SchedModel->getProcResource(PIdx)->Name << " x" - << ResourceCounts[PIdx] << '\n'); + << getResourceName(PIdx) << ": " + << getResourceCount(PIdx) / SchedModel->getLatencyFactor() << "c\n"); } + // TODO: We don't yet model reserved resources. It's not hard though. + return CurrCycle; } /// Move the boundary of scheduled code by one SUnit. @@ -1661,38 +1774,96 @@ void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) { } HazardRec->EmitInstruction(SU); } + const MCSchedClassDesc *SC = DAG->getSchedClass(SU); + unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr()); + CurrMOps += IncMOps; + // checkHazard prevents scheduling multiple instructions per cycle that exceed + // issue width. However, we commonly reach the maximum. In this case + // opportunistically bump the cycle to avoid uselessly checking everything in + // the readyQ. Furthermore, a single instruction may produce more than one + // cycle's worth of micro-ops. + // + // TODO: Also check if this SU must end a dispatch group. + unsigned NextCycle = CurrCycle; + if (CurrMOps >= SchedModel->getIssueWidth()) { + ++NextCycle; + DEBUG(dbgs() << " *** Max MOps " << CurrMOps + << " at cycle " << CurrCycle << '\n'); + } + unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); + DEBUG(dbgs() << " Ready @" << ReadyCycle << "c\n"); + + switch (SchedModel->getMicroOpBufferSize()) { + case 0: + assert(ReadyCycle <= CurrCycle && "Broken PendingQueue"); + break; + case 1: + if (ReadyCycle > NextCycle) { + NextCycle = ReadyCycle; + DEBUG(dbgs() << " *** Stall until: " << ReadyCycle << "\n"); + } + break; + default: + // We don't currently model the OOO reorder buffer, so consider all + // scheduled MOps to be "retired". + break; + } + RetiredMOps += IncMOps; + // Update resource counts and critical resource. if (SchedModel->hasInstrSchedModel()) { - const MCSchedClassDesc *SC = DAG->getSchedClass(SU); - Rem->RemainingMicroOps -= SchedModel->getNumMicroOps(SU->getInstr(), SC); + 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) { - countResource(PI->ProcResourceIdx, PI->Cycles); + unsigned RCycle = + countResource(PI->ProcResourceIdx, PI->Cycles, ReadyCycle); + if (RCycle > NextCycle) + NextCycle = RCycle; } } + // Update ExpectedLatency and DependentLatency. unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency; unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency; - if (SU->getDepth() > TopLatency) + if (SU->getDepth() > TopLatency) { TopLatency = SU->getDepth(); - if (SU->getHeight() > BotLatency) + DEBUG(dbgs() << " " << Available.getName() + << " TopLatency SU(" << SU->NodeNum << ") " << TopLatency << "c\n"); + } + if (SU->getHeight() > BotLatency) { BotLatency = SU->getHeight(); - - IsResourceLimited = getCriticalCount() > std::max(ExpectedLatency, CurrCycle); - - // Check the instruction group dispatch limit. - // TODO: Check if this SU must end a dispatch group. - CurrMOps += SchedModel->getNumMicroOps(SU->getInstr()); - - // checkHazard prevents scheduling multiple instructions per cycle that exceed - // issue width. However, we commonly reach the maximum. In this case - // opportunistically bump the cycle to avoid uselessly checking everything in - // the readyQ. Furthermore, a single instruction may produce more than one - // cycle's worth of micro-ops. - if (CurrMOps >= SchedModel->getIssueWidth()) { - DEBUG(dbgs() << " *** Max instrs at cycle " << CurrCycle << '\n'); - bumpCycle(); + 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 occured, bumpCycle does this. + unsigned LFactor = SchedModel->getLatencyFactor(); + IsResourceLimited = + (int)(getCriticalCount() - (getScheduledLatency() * LFactor)) + > (int)LFactor; + } + DEBUG(dumpScheduledState()); } /// Release pending ready nodes in to the available queue. This makes them @@ -1704,6 +1875,7 @@ void ConvergingScheduler::SchedBoundary::releasePending() { // 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; @@ -1711,7 +1883,7 @@ void ConvergingScheduler::SchedBoundary::releasePending() { if (ReadyCycle < MinReadyCycle) MinReadyCycle = ReadyCycle; - if (ReadyCycle > CurrCycle) + if (!IsBuffered && ReadyCycle > CurrCycle) continue; if (checkHazard(SU)) @@ -1756,7 +1928,7 @@ SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() { for (unsigned i = 0; Available.empty(); ++i) { assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) && "permanent hazard"); (void)i; - bumpCycle(); + bumpCycle(CurrCycle + 1); releasePending(); } if (Available.size() == 1) @@ -1764,103 +1936,28 @@ SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() { return NULL; } -/// Record the candidate policy for opposite zones with different critical -/// resources. -/// -/// If the CriticalZone is latency limited, don't force a policy for the -/// candidates here. Instead, setLatencyPolicy sets ReduceLatency if needed. -void ConvergingScheduler::balanceZones( - ConvergingScheduler::SchedBoundary &CriticalZone, - ConvergingScheduler::SchedCandidate &CriticalCand, - ConvergingScheduler::SchedBoundary &OppositeZone, - ConvergingScheduler::SchedCandidate &OppositeCand) { - - if (!CriticalZone.IsResourceLimited) - return; - assert(SchedModel->hasInstrSchedModel() && "required schedmodel"); - - SchedRemainder *Rem = CriticalZone.Rem; - - // If the critical zone is overconsuming a resource relative to the - // remainder, try to reduce it. - unsigned RemainingCritCount = - Rem->RemainingCounts[CriticalZone.CritResIdx]; - if ((int)(Rem->getMaxRemainingCount(SchedModel) - RemainingCritCount) - > (int)SchedModel->getLatencyFactor()) { - CriticalCand.Policy.ReduceResIdx = CriticalZone.CritResIdx; - DEBUG(dbgs() << " Balance " << CriticalZone.Available.getName() - << " reduce " - << SchedModel->getProcResource(CriticalZone.CritResIdx)->Name - << '\n'); - } - // If the other zone is underconsuming a resource relative to the full zone, - // try to increase it. - unsigned OppositeCount = - OppositeZone.ResourceCounts[CriticalZone.CritResIdx]; - if ((int)(OppositeZone.ExpectedCount - OppositeCount) - > (int)SchedModel->getLatencyFactor()) { - OppositeCand.Policy.DemandResIdx = CriticalZone.CritResIdx; - DEBUG(dbgs() << " Balance " << OppositeZone.Available.getName() - << " demand " - << SchedModel->getProcResource(OppositeZone.CritResIdx)->Name - << '\n'); +// This is useful information to dump after bumpNode. +// Note that the Queue contents are more useful before pickNodeFromQueue. +void ConvergingScheduler::SchedBoundary::dumpScheduledState() { + unsigned ResFactor; + unsigned ResCount; + if (ZoneCritResIdx) { + ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx); + ResCount = getResourceCount(ZoneCritResIdx); } -} - -/// Determine if the scheduled zones exceed resource limits or critical path and -/// set each candidate's ReduceHeight policy accordingly. -void ConvergingScheduler::checkResourceLimits( - ConvergingScheduler::SchedCandidate &TopCand, - ConvergingScheduler::SchedCandidate &BotCand) { - - // Set ReduceLatency to true if needed. - Bot.setLatencyPolicy(BotCand.Policy); - Top.setLatencyPolicy(TopCand.Policy); - - // Handle resource-limited regions. - if (Top.IsResourceLimited && Bot.IsResourceLimited - && Top.CritResIdx == Bot.CritResIdx) { - // If the scheduled critical resource in both zones is no longer the - // critical remaining resource, attempt to reduce resource height both ways. - if (Top.CritResIdx != Rem.CritResIdx) { - TopCand.Policy.ReduceResIdx = Top.CritResIdx; - BotCand.Policy.ReduceResIdx = Bot.CritResIdx; - DEBUG(dbgs() << " Reduce scheduled " - << SchedModel->getProcResource(Top.CritResIdx)->Name << '\n'); - } - return; - } - // Handle latency-limited regions. - if (!Top.IsResourceLimited && !Bot.IsResourceLimited) { - // If the total scheduled expected latency exceeds the region's critical - // path then reduce latency both ways. - // - // Just because a zone is not resource limited does not mean it is latency - // limited. Unbuffered resource, such as max micro-ops may cause CurrCycle - // to exceed expected latency. - if ((Top.ExpectedLatency + Bot.ExpectedLatency >= Rem.CriticalPath) - && (Rem.CriticalPath > Top.CurrCycle + Bot.CurrCycle)) { - TopCand.Policy.ReduceLatency = true; - BotCand.Policy.ReduceLatency = true; - DEBUG(dbgs() << " Reduce scheduled latency " << Top.ExpectedLatency - << " + " << Bot.ExpectedLatency << '\n'); - } - return; + else { + ResFactor = SchedModel->getMicroOpFactor(); + ResCount = RetiredMOps * SchedModel->getMicroOpFactor(); } - // The critical resource is different in each zone, so request balancing. - - // Compute the cost of each zone. - Top.ExpectedCount = std::max(Top.ExpectedLatency, Top.CurrCycle); - Top.ExpectedCount = std::max( - Top.getCriticalCount(), - Top.ExpectedCount * SchedModel->getLatencyFactor()); - Bot.ExpectedCount = std::max(Bot.ExpectedLatency, Bot.CurrCycle); - Bot.ExpectedCount = std::max( - Bot.getCriticalCount(), - Bot.ExpectedCount * SchedModel->getLatencyFactor()); - - balanceZones(Top, TopCand, Bot, BotCand); - balanceZones(Bot, BotCand, Top, TopCand); + unsigned LFactor = SchedModel->getLatencyFactor(); + dbgs() << Available.getName() << " @" << CurrCycle << "c\n" + << " Retired: " << RetiredMOps; + dbgs() << "\n Executed: " << getExecutedCount() / LFactor << "c"; + dbgs() << "\n Critical: " << ResCount / LFactor << "c, " + << ResCount / ResFactor << " " << getResourceName(ZoneCritResIdx) + << "\n ExpectedLatency: " << ExpectedLatency << "c\n" + << (IsResourceLimited ? " - Resource" : " - Latency") + << " limited.\n"; } void ConvergingScheduler::SchedCandidate:: @@ -2030,8 +2127,7 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, // Avoid serializing long latency dependence chains. if (Cand.Policy.ReduceLatency) { if (Zone.isTop()) { - if (Cand.SU->getDepth() * SchedModel->getLatencyFactor() - > Zone.ExpectedCount) { + if (Cand.SU->getDepth() > Zone.getScheduledLatency()) { if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), TryCand, Cand, TopDepthReduce)) return; @@ -2041,8 +2137,7 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, return; } else { - if (Cand.SU->getHeight() * SchedModel->getLatencyFactor() - > Zone.ExpectedCount) { + if (Cand.SU->getHeight() > Zone.getScheduledLatency()) { if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), TryCand, Cand, BotHeightReduce)) return; @@ -2061,8 +2156,8 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, Cand.Reason = MultiPressure; // Prefer immediate defs/users of the last scheduled instruction. This is a - // nice pressure avoidance strategy that also conserves the processor's - // register renaming resources and keeps the machine code readable. + // local pressure avoidance strategy that also makes the machine code + // readable. if (tryGreater(Zone.NextSUs.count(TryCand.SU), Zone.NextSUs.count(Cand.SU), TryCand, Cand, NextDefUse)) return; @@ -2224,18 +2319,19 @@ SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { // efficient, but also provides the best heuristics for CriticalPSets. if (SUnit *SU = Bot.pickOnlyChoice()) { IsTopNode = false; - DEBUG(dbgs() << "Pick Top NOCAND\n"); + DEBUG(dbgs() << "Pick Bot NOCAND\n"); return SU; } if (SUnit *SU = Top.pickOnlyChoice()) { IsTopNode = true; - DEBUG(dbgs() << "Pick Bot NOCAND\n"); + DEBUG(dbgs() << "Pick Top NOCAND\n"); return SU; } CandPolicy NoPolicy; SchedCandidate BotCand(NoPolicy); SchedCandidate TopCand(NoPolicy); - checkResourceLimits(TopCand, BotCand); + Bot.setPolicy(BotCand.Policy, Top); + Top.setPolicy(TopCand.Policy, Bot); // Prefer bottom scheduling when heuristics are silent. pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand); @@ -2364,13 +2460,13 @@ void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { /// them here. See comments in biasPhysRegCopy. void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) { if (IsTopNode) { - SU->TopReadyCycle = Top.CurrCycle; + SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.CurrCycle); Top.bumpNode(SU); if (SU->hasPhysRegUses) reschedulePhysRegCopies(SU, true); } else { - SU->BotReadyCycle = Bot.CurrCycle; + SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.CurrCycle); Bot.bumpNode(SU); if (SU->hasPhysRegDefs) reschedulePhysRegCopies(SU, false); -- cgit v1.2.3