diff options
Diffstat (limited to 'contrib/llvm/lib/CodeGen/MachineScheduler.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/MachineScheduler.cpp | 1456 |
1 files changed, 958 insertions, 498 deletions
diff --git a/contrib/llvm/lib/CodeGen/MachineScheduler.cpp b/contrib/llvm/lib/CodeGen/MachineScheduler.cpp index fff6b2b..e71c4df 100644 --- a/contrib/llvm/lib/CodeGen/MachineScheduler.cpp +++ b/contrib/llvm/lib/CodeGen/MachineScheduler.cpp @@ -21,6 +21,7 @@ #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" @@ -30,6 +31,7 @@ #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; @@ -51,10 +53,11 @@ static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden, static bool ViewMISchedDAGs = false; #endif // NDEBUG -// FIXME: remove this flag after initial testing. It should always be a good -// thing. -static cl::opt<bool> EnableCopyConstrain("misched-vcopy", cl::Hidden, - cl::desc("Constrain vreg copies."), cl::init(true)); +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)); @@ -69,6 +72,10 @@ static cl::opt<bool> VerifyScheduling("verify-misched", cl::Hidden, // DAG subtrees must have at least this many nodes. static const unsigned MinSubtreeSize = 8; +// Pin the vtables to this file. +void MachineSchedStrategy::anchor() {} +void ScheduleDAGMutation::anchor() {} + //===----------------------------------------------------------------------===// // Machine Instruction Scheduling Pass and Registry //===----------------------------------------------------------------------===// @@ -98,6 +105,9 @@ public: virtual void print(raw_ostream &O, const Module* = 0) const; static char ID; // Class identification, replacement for typeinfo + +protected: + ScheduleDAGInstrs *createMachineScheduler(); }; } // namespace @@ -152,12 +162,13 @@ DefaultSchedRegistry("default", "Use the target's default scheduler choice.", /// Forward declare the standard machine scheduler. This will be used as the /// default scheduler if the target does not set a default. -static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C); +static ScheduleDAGInstrs *createGenericSched(MachineSchedContext *C); /// Decrement this iterator until reaching the top or a non-debug instr. -static MachineBasicBlock::iterator -priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) { +static MachineBasicBlock::const_iterator +priorNonDebug(MachineBasicBlock::const_iterator I, + MachineBasicBlock::const_iterator Beg) { assert(I != Beg && "reached the top of the region, cannot decrement"); while (--I != Beg) { if (!I->isDebugValue()) @@ -166,10 +177,19 @@ priorNonDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator Beg) { return I; } +/// Non-const version. +static MachineBasicBlock::iterator +priorNonDebug(MachineBasicBlock::iterator I, + MachineBasicBlock::const_iterator Beg) { + return const_cast<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::iterator -nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) { +static MachineBasicBlock::const_iterator +nextIfDebug(MachineBasicBlock::const_iterator I, + MachineBasicBlock::const_iterator End) { for(; I != End; ++I) { if (!I->isDebugValue()) break; @@ -177,6 +197,34 @@ nextIfDebug(MachineBasicBlock::iterator I, MachineBasicBlock::iterator End) { return I; } +/// Non-const version. +static MachineBasicBlock::iterator +nextIfDebug(MachineBasicBlock::iterator I, + MachineBasicBlock::const_iterator End) { + // Cast the return value to nonconst MachineInstr, then cast to an + // instr_iterator, which does not check for null, finally return a + // bundle_iterator. + return MachineBasicBlock::instr_iterator( + const_cast<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 createGenericSched(this); +} + /// Top-level MachineScheduler pass driver. /// /// Visit blocks in function order. Divide each block into scheduling regions @@ -207,23 +255,14 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { const TargetInstrInfo *TII = MF->getTarget().getInstrInfo(); if (VerifyScheduling) { - DEBUG(LIS->print(dbgs())); + DEBUG(LIS->dump()); MF->verify(this, "Before machine scheduling."); } RegClassInfo->runOnMachineFunction(*MF); - // Select the scheduler, or set the default. - MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt; - if (Ctor == useDefaultMachineSched) { - // Get the default scheduler set by the target. - Ctor = MachineSchedRegistry::getDefault(); - if (!Ctor) { - Ctor = createConvergingSched; - MachineSchedRegistry::setDefault(Ctor); - } - } - // Instantiate the selected scheduler. - OwningPtr<ScheduleDAGInstrs> Scheduler(Ctor(this)); + // Instantiate the selected scheduler for this target, function, and + // optimization level. + OwningPtr<ScheduleDAGInstrs> Scheduler(createMachineScheduler()); // Visit all machine basic blocks. // @@ -258,14 +297,15 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { // 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) { + for(;I != MBB->begin(); --I, --RemainingInstrs, ++NumRegionInstrs) { if (TII->isSchedulingBoundary(llvm::prior(I), MBB, *MF)) break; } // Notify the scheduler of the region, even if we may skip scheduling // it. Perhaps it still needs to be bundled. - Scheduler->enterRegion(MBB, I, RegionEnd, RemainingInstrs); + Scheduler->enterRegion(MBB, I, RegionEnd, NumRegionInstrs); // Skip empty scheduling regions (0 or 1 schedulable instructions). if (I == RegionEnd || I == llvm::prior(RegionEnd)) { @@ -280,7 +320,8 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { << "\n From: " << *I << " To: "; if (RegionEnd != MBB->end()) dbgs() << *RegionEnd; else dbgs() << "End"; - dbgs() << " Remaining: " << RemainingInstrs << "\n"); + dbgs() << " RegionInstrs: " << NumRegionInstrs + << " Remaining: " << RemainingInstrs << "\n"); // Schedule a region: possibly reorder instructions. // This invalidates 'RegionEnd' and 'I'. @@ -297,7 +338,7 @@ bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { Scheduler->finishBlock(); } Scheduler->finalizeSchedule(); - DEBUG(LIS->print(dbgs())); + DEBUG(LIS->dump()); if (VerifyScheduling) MF->verify(this, "After machine scheduling."); return true; @@ -309,7 +350,7 @@ void MachineScheduler::print(raw_ostream &O, const Module* m) const { #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void ReadyQueue::dump() { - dbgs() << " " << Name << ": "; + dbgs() << Name << ": "; for (unsigned i = 0, e = Queue.size(); i < e; ++i) dbgs() << Queue[i]->NodeNum << " "; dbgs() << "\n"; @@ -449,13 +490,19 @@ bool ScheduleDAGMI::checkSchedLimit() { void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb, MachineBasicBlock::iterator begin, MachineBasicBlock::iterator end, - unsigned endcount) + unsigned regioninstrs) { - ScheduleDAGInstrs::enterRegion(bb, begin, end, endcount); + ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs); // For convenience remember the end of the liveness region. LiveRegionEnd = (RegionEnd == bb->end()) ? RegionEnd : llvm::next(RegionEnd); + + SUPressureDiffs.clear(); + + SchedImpl->initPolicy(begin, end, regioninstrs); + + ShouldTrackPressure = SchedImpl->shouldTrackPressure(); } // Setup the register pressure trackers for the top scheduled top and bottom @@ -467,7 +514,7 @@ void ScheduleDAGMI::initRegPressure() { // Close the RPTracker to finalize live ins. RPTracker.closeRegion(); - DEBUG(RPTracker.getPressure().dump(TRI)); + DEBUG(RPTracker.dump()); // Initialize the live ins and live outs. TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs); @@ -479,9 +526,23 @@ void ScheduleDAGMI::initRegPressure() { 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) - BotRPTracker.recede(); + if (LiveRegionEnd != RegionEnd) { + SmallVector<unsigned, 8> LiveUses; + BotRPTracker.recede(&LiveUses); + updatePressureDiffs(LiveUses); + } assert(BotRPTracker.getPos() == RegionEnd && "Can't find the region bottom"); @@ -491,38 +552,88 @@ void ScheduleDAGMI::initRegPressure() { const std::vector<unsigned> &RegionPressure = RPTracker.getPressure().MaxSetPressure; for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) { - unsigned Limit = TRI->getRegPressureSetLimit(i); - DEBUG(dbgs() << TRI->getRegPressureSetName(i) - << "Limit " << Limit - << " Actual " << RegionPressure[i] << "\n"); - if (RegionPressure[i] > Limit) - RegionCriticalPSets.push_back(PressureElement(i, 0)); + 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].PSetID) << " "; + RegionCriticalPSets[i].getPSet()) << " "; dbgs() << "\n"); } -// FIXME: When the pressure tracker deals in pressure differences then we won't -// iterate over all RegionCriticalPSets[i]. void ScheduleDAGMI:: -updateScheduledPressure(const std::vector<unsigned> &NewMaxPressure) { - for (unsigned i = 0, e = RegionCriticalPSets.size(); i < e; ++i) { - unsigned ID = RegionCriticalPSets[i].PSetID; - int &MaxUnits = RegionCriticalPSets[i].UnitIncrease; - if ((int)NewMaxPressure[ID] > MaxUnits) - MaxUnits = NewMaxPressure[ID]; +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] << " > " << Limit << "(+ " + << BotRPTracker.getLiveThru()[ID] << " livethru)\n"); + } } - DEBUG( - for (unsigned i = 0, e = NewMaxPressure.size(); i < e; ++i) { - unsigned Limit = TRI->getRegPressureSetLimit(i); - if (NewMaxPressure[i] > Limit ) { - dbgs() << " " << TRI->getRegPressureSetName(i) << ": " - << NewMaxPressure[i] << " > " << Limit << "\n"; +} + +/// Update the PressureDiff array for liveness after scheduling this +/// instruction. +void ScheduleDAGMI::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 @@ -580,15 +691,23 @@ void ScheduleDAGMI::schedule() { /// Build the DAG and setup three register pressure trackers. void ScheduleDAGMI::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); + 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); + buildSchedGraph(AA, &RPTracker, &SUPressureDiffs); // Initialize top/bottom trackers after computing region pressure. initRegPressure(); @@ -631,6 +750,91 @@ void ScheduleDAGMI::findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots, ExitSU.biasCriticalPath(); } +/// Compute the max cyclic critical path through the DAG. The scheduling DAG +/// only provides the critical path for single block loops. To handle loops that +/// span blocks, we could use the vreg path latencies provided by +/// MachineTraceMetrics instead. However, MachineTraceMetrics is not currently +/// available for use in the scheduler. +/// +/// The cyclic path estimation identifies a def-use pair that crosses the back +/// edge and considers the depth and height of the nodes. For example, consider +/// the following instruction sequence where each instruction has unit latency +/// and defines an epomymous virtual register: +/// +/// a->b(a,c)->c(b)->d(c)->exit +/// +/// The cyclic critical path is a two cycles: b->c->b +/// The acyclic critical path is four cycles: a->b->c->d->exit +/// LiveOutHeight = height(c) = len(c->d->exit) = 2 +/// LiveOutDepth = depth(c) + 1 = len(a->b->c) + 1 = 3 +/// LiveInHeight = height(b) + 1 = len(b->c->d->exit) + 1 = 4 +/// LiveInDepth = depth(b) = len(a->b) = 1 +/// +/// LiveOutDepth - LiveInDepth = 3 - 1 = 2 +/// LiveInHeight - LiveOutHeight = 4 - 2 = 2 +/// CyclicCriticalPath = min(2, 2) = 2 +unsigned ScheduleDAGMI::computeCyclicCriticalPath() { + // This only applies to single block loop. + if (!BB->isSuccessor(BB)) + return 0; + + unsigned MaxCyclicLatency = 0; + // Visit each live out vreg def to find def/use pairs that cross iterations. + ArrayRef<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; +} + /// Identify DAG roots and setup scheduler queues. void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots, ArrayRef<SUnit*> BotRoots) { @@ -658,11 +862,13 @@ void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots, SchedImpl->registerRoots(); // Advance past initial DebugValues. - assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); CurrentTop = nextIfDebug(RegionBegin, RegionEnd); - TopRPTracker.setPos(CurrentTop); - CurrentBottom = RegionEnd; + + if (ShouldTrackPressure) { + assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); + TopRPTracker.setPos(CurrentTop); + } } /// Move an instruction and update register pressure. @@ -679,10 +885,12 @@ void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) { TopRPTracker.setPos(MI); } - // Update top scheduled pressure. - TopRPTracker.advance(); - assert(TopRPTracker.getPos() == CurrentTop && "out of sync"); - updateScheduledPressure(TopRPTracker.getPressure().MaxSetPressure); + 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"); @@ -698,10 +906,14 @@ void ScheduleDAGMI::scheduleMI(SUnit *SU, bool IsTopNode) { moveInstruction(MI, CurrentBottom); CurrentBottom = MI; } - // Update bottom scheduled pressure. - BotRPTracker.recede(); - assert(BotRPTracker.getPos() == CurrentBottom && "out of sync"); - updateScheduledPressure(BotRPTracker.getPressure().MaxSetPressure); + 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); + } } } @@ -1019,6 +1231,12 @@ void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMI *DAG) { GlobalSegment->start)) { return; } + // If the prior global segment may be defined by the same two-address + // instruction that also defines LocalLI, then can't make a hole here. + if (SlotIndex::isSameInstr(llvm::prior(GlobalSegment)->start, + LocalLI->beginIndex())) { + return; + } // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise // it would be a disconnected component in the live range. assert(llvm::prior(GlobalSegment)->start < LocalLI->beginIndex() && @@ -1101,24 +1319,23 @@ void CopyConstrain::apply(ScheduleDAGMI *DAG) { } //===----------------------------------------------------------------------===// -// ConvergingScheduler - Implementation of the standard MachineSchedStrategy. +// GenericScheduler - Implementation of the generic MachineSchedStrategy. //===----------------------------------------------------------------------===// namespace { -/// ConvergingScheduler shrinks the unscheduled zone using heuristics to balance +/// GenericScheduler shrinks the unscheduled zone using heuristics to balance /// the schedule. -class ConvergingScheduler : public MachineSchedStrategy { +class GenericScheduler : public MachineSchedStrategy { public: /// Represent the type of SchedCandidate found within a single queue. /// pickNodeBidirectional depends on these listed by decreasing priority. enum CandReason { - NoCand, PhysRegCopy, SingleExcess, SingleCritical, Cluster, Weak, + NoCand, PhysRegCopy, RegExcess, RegCritical, Cluster, Weak, RegMax, ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce, - TopDepthReduce, TopPathReduce, SingleMax, MultiPressure, NextDefUse, - NodeOrder}; + TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder}; #ifndef NDEBUG - static const char *getReasonStr(ConvergingScheduler::CandReason Reason); + static const char *getReasonStr(GenericScheduler::CandReason Reason); #endif /// Policy for scheduling the next instruction in the candidate's zone. @@ -1149,7 +1366,7 @@ public: } }; - /// Store the state used by ConvergingScheduler heuristics, required for the + /// Store the state used by GenericScheduler heuristics, required for the /// lifetime of one invocation of pickNode(). struct SchedCandidate { CandPolicy Policy; @@ -1160,6 +1377,9 @@ public: // The reason for this candidate. CandReason Reason; + // Set of reasons that apply to multiple candidates. + uint32_t RepeatReasonSet; + // Register pressure values for the best candidate. RegPressureDelta RPDelta; @@ -1167,7 +1387,7 @@ public: SchedResourceDelta ResDelta; SchedCandidate(const CandPolicy &policy) - : Policy(policy), SU(NULL), Reason(NoCand) {} + : Policy(policy), SU(NULL), Reason(NoCand), RepeatReasonSet(0) {} bool isValid() const { return SU; } @@ -1180,6 +1400,9 @@ public: ResDelta = Best.ResDelta; } + bool isRepeat(CandReason R) { return RepeatReasonSet & (1 << R); } + void setRepeat(CandReason R) { RepeatReasonSet |= (1 << R); } + void initResourceDelta(const ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel); }; @@ -1188,33 +1411,27 @@ public: struct SchedRemainder { // Critical path through the DAG in expected latency. unsigned CriticalPath; + unsigned CyclicCritPath; + + // Scaled count of micro-ops left to schedule. + unsigned RemIssueCount; + + bool IsAcyclicLatencyLimited; // Unscheduled resources SmallVector<unsigned, 16> RemainingCounts; - // Critical resource for the unscheduled zone. - unsigned CritResIdx; - // Number of micro-ops left to schedule. - unsigned RemainingMicroOps; void reset() { CriticalPath = 0; + CyclicCritPath = 0; + RemIssueCount = 0; + IsAcyclicLatencyLimited = false; 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 @@ -1235,8 +1452,13 @@ 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; - unsigned IssueCount; + + /// Micro-ops issued in the current cycle + unsigned CurrMOps; /// MinReadyCycle - Cycle of the soonest available instruction. unsigned MinReadyCycle; @@ -1244,52 +1466,71 @@ public: // The expected latency of the critical path in this scheduled zone. unsigned ExpectedLatency; - // Resources used in the scheduled zone beyond this boundary. - SmallVector<unsigned, 16> ResourceCounts; + // The latency of dependence chains leading into this zone. + // For each node scheduled bottom-up: DLat = max DLat, N.Depth. + // For each cycle scheduled: DLat -= 1. + unsigned DependentLatency; + + /// Count the scheduled (issued) micro-ops that can be retired by + /// time=CurrCycle assuming the first scheduled instr is retired at time=0. + unsigned RetiredMOps; + + // Count scheduled resources that have been executed. Resources are + // considered executed if they become ready in the time that it takes to + // saturate any resource including the one in question. Counts are scaled + // for direct comparison with other resources. Counts can be compared with + // MOps * getMicroOpFactor and Latency * getLatencyFactor. + SmallVector<unsigned, 16> 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 min operand latency. - unsigned MaxMinLatency; + // Remember the greatest operand latency as an upper bound on the number of + // times we should retry the pending queue because of a hazard. + unsigned MaxObservedLatency; #endif void reset() { // A new HazardRec is created for each DAG and owned by SchedBoundary. - delete HazardRec; - + // Destroying and reconstructing it is very expensive though. So keep + // invalid, placeholder HazardRecs. + if (HazardRec && HazardRec->isEnabled()) { + delete HazardRec; + HazardRec = 0; + } Available.clear(); Pending.clear(); CheckPending = false; NextSUs.clear(); - HazardRec = 0; CurrCycle = 0; - IssueCount = 0; + CurrMOps = 0; MinReadyCycle = UINT_MAX; ExpectedLatency = 0; - ResourceCounts.resize(1); - assert(!ResourceCounts[0] && "nonzero count for bad resource"); - CritResIdx = 0; + DependentLatency = 0; + RetiredMOps = 0; + MaxExecutedResCount = 0; + ZoneCritResIdx = 0; IsResourceLimited = false; - ExpectedCount = 0; #ifndef NDEBUG - MaxMinLatency = 0; + 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 /// PendingFlag set. SchedBoundary(unsigned ID, const Twine &Name): DAG(0), SchedModel(0), Rem(0), Available(ID, Name+".A"), - Pending(ID << ConvergingScheduler::LogMaxQID, Name+".P"), + Pending(ID << GenericScheduler::LogMaxQID, Name+".P"), HazardRec(0) { reset(); } @@ -1300,28 +1541,63 @@ public: SchedRemainder *rem); bool isTop() const { - return Available.getID() == ConvergingScheduler::TopQID; + return Available.getID() == GenericScheduler::TopQID; + } + +#ifndef NDEBUG + const char *getResourceName(unsigned PIdx) { + if (!PIdx) + return "MOps"; + return SchedModel->getProcResource(PIdx)->Name; + } +#endif + + /// Get the number of latency cycles "covered" by the scheduled + /// instructions. This is the larger of the critical path within the zone + /// and the number of cycles required to issue the instructions. + unsigned getScheduledLatency() const { + return std::max(ExpectedLatency, CurrCycle); } unsigned getUnscheduledLatency(SUnit *SU) const { - 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<SUnit*> 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); @@ -1330,9 +1606,14 @@ public: void removeReady(SUnit *SU); SUnit *pickOnlyChoice(); + +#ifndef NDEBUG + void dumpScheduledState(); +#endif }; private: + const MachineSchedContext *Context; ScheduleDAGMI *DAG; const TargetSchedModel *SchedModel; const TargetRegisterInfo *TRI; @@ -1342,6 +1623,7 @@ private: SchedBoundary Top; SchedBoundary Bot; + MachineSchedPolicy RegionPolicy; public: /// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both) enum { @@ -1350,8 +1632,15 @@ public: LogMaxQID = 2 }; - ConvergingScheduler(): - DAG(0), SchedModel(0), TRI(0), Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {} + GenericScheduler(const MachineSchedContext *C): + Context(C), DAG(0), SchedModel(0), TRI(0), + Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {} + + virtual void initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs); + + bool shouldTrackPressure() const { return RegionPolicy.ShouldTrackPressure; } virtual void initialize(ScheduleDAGMI *dag); @@ -1366,14 +1655,7 @@ 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 checkAcyclicLatency(); void tryCandidate(SchedCandidate &Cand, SchedCandidate &TryCand, @@ -1395,7 +1677,7 @@ protected: }; } // namespace -void ConvergingScheduler::SchedRemainder:: +void GenericScheduler::SchedRemainder:: init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { reset(); if (!SchedModel->hasInstrSchedModel()) @@ -1404,7 +1686,8 @@ init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { for (std::vector<SUnit>::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) { @@ -1413,26 +1696,61 @@ 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; - } - } } -void ConvergingScheduler::SchedBoundary:: +void GenericScheduler::SchedBoundary:: init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) { reset(); DAG = dag; SchedModel = smodel; Rem = rem; if (SchedModel->hasInstrSchedModel()) - ResourceCounts.resize(SchedModel->getNumProcResourceKinds()); + ExecutedResCounts.resize(SchedModel->getNumProcResourceKinds()); +} + +/// Initialize the per-region scheduling policy. +void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin, + MachineBasicBlock::iterator End, + unsigned NumRegionInstrs) { + const TargetMachine &TM = Context->MF->getTarget(); + + // 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. + unsigned NIntRegs = Context->RegClassInfo->getNumAllocatableRegs( + TM.getTargetLowering()->getRegClassFor(MVT::i32)); + + 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. + const TargetSubtargetInfo &ST = TM.getSubtarget<TargetSubtargetInfo>(); + ST.overrideSchedPolicy(RegionPolicy, Begin, End, NumRegionInstrs); + + // After subtarget overrides, apply command line options. + if (!EnableRegPressure) + RegionPolicy.ShouldTrackPressure = false; + + // Check -misched-topdown/bottomup can force or unforce scheduling direction. + // e.g. -misched-bottomup=false allows scheduling in both directions. + assert((!ForceTopDown || !ForceBottomUp) && + "-misched-topdown incompatible with -misched-bottomup"); + if (ForceBottomUp.getNumOccurrences() > 0) { + RegionPolicy.OnlyBottomUp = ForceBottomUp; + if (RegionPolicy.OnlyBottomUp) + RegionPolicy.OnlyTopDown = false; + } + if (ForceTopDown.getNumOccurrences() > 0) { + RegionPolicy.OnlyTopDown = ForceTopDown; + if (RegionPolicy.OnlyTopDown) + RegionPolicy.OnlyBottomUp = false; + } } -void ConvergingScheduler::initialize(ScheduleDAGMI *dag) { +void GenericScheduler::initialize(ScheduleDAGMI *dag) { DAG = dag; SchedModel = DAG->getSchedModel(); TRI = DAG->TRI; @@ -1447,31 +1765,36 @@ void ConvergingScheduler::initialize(ScheduleDAGMI *dag) { // are disabled, then these HazardRecs will be disabled. const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); const TargetMachine &TM = DAG->MF.getTarget(); - Top.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); - Bot.HazardRec = TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); - - assert((!ForceTopDown || !ForceBottomUp) && - "-misched-topdown incompatible with -misched-bottomup"); + if (!Top.HazardRec) { + Top.HazardRec = + TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); + } + if (!Bot.HazardRec) { + Bot.HazardRec = + TM.getInstrInfo()->CreateTargetMIHazardRecognizer(Itin, DAG); + } } -void ConvergingScheduler::releaseTopNode(SUnit *SU) { +void GenericScheduler::releaseTopNode(SUnit *SU) { if (SU->isScheduled) return; for (SUnit::pred_iterator I = SU->Preds.begin(), E = SU->Preds.end(); I != E; ++I) { + if (I->isWeak()) + continue; unsigned PredReadyCycle = I->getSUnit()->TopReadyCycle; - unsigned MinLatency = I->getMinLatency(); + unsigned Latency = I->getLatency(); #ifndef NDEBUG - Top.MaxMinLatency = std::max(MinLatency, Top.MaxMinLatency); + Top.MaxObservedLatency = std::max(Latency, Top.MaxObservedLatency); #endif - if (SU->TopReadyCycle < PredReadyCycle + MinLatency) - SU->TopReadyCycle = PredReadyCycle + MinLatency; + if (SU->TopReadyCycle < PredReadyCycle + Latency) + SU->TopReadyCycle = PredReadyCycle + Latency; } Top.releaseNode(SU, SU->TopReadyCycle); } -void ConvergingScheduler::releaseBottomNode(SUnit *SU) { +void GenericScheduler::releaseBottomNode(SUnit *SU) { if (SU->isScheduled) return; @@ -1482,18 +1805,56 @@ void ConvergingScheduler::releaseBottomNode(SUnit *SU) { if (I->isWeak()) continue; unsigned SuccReadyCycle = I->getSUnit()->BotReadyCycle; - unsigned MinLatency = I->getMinLatency(); + unsigned Latency = I->getLatency(); #ifndef NDEBUG - Bot.MaxMinLatency = std::max(MinLatency, Bot.MaxMinLatency); + Bot.MaxObservedLatency = std::max(Latency, Bot.MaxObservedLatency); #endif - if (SU->BotReadyCycle < SuccReadyCycle + MinLatency) - SU->BotReadyCycle = SuccReadyCycle + MinLatency; + if (SU->BotReadyCycle < SuccReadyCycle + Latency) + SU->BotReadyCycle = SuccReadyCycle + Latency; } Bot.releaseNode(SU, SU->BotReadyCycle); } -void ConvergingScheduler::registerRoots() { +/// 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) { @@ -1501,6 +1862,11 @@ void ConvergingScheduler::registerRoots() { Rem.CriticalPath = (*I)->getDepth(); } DEBUG(dbgs() << "Critical Path: " << Rem.CriticalPath << '\n'); + + if (EnableCyclicPath) { + Rem.CyclicCritPath = DAG->computeCyclicCriticalPath(); + checkAcyclicLatency(); + } } /// Does this SU have a hazard within the current instruction group. @@ -1516,12 +1882,12 @@ void ConvergingScheduler::registerRoots() { /// can dispatch per cycle. /// /// TODO: Also check whether the SU must start a new group. -bool ConvergingScheduler::SchedBoundary::checkHazard(SUnit *SU) { +bool GenericScheduler::SchedBoundary::checkHazard(SUnit *SU) { if (HazardRec->isEnabled()) return HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard; unsigned uops = SchedModel->getNumMicroOps(SU->getInstr()); - if ((IssueCount > 0) && (IssueCount + uops > SchedModel->getIssueWidth())) { + if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) { DEBUG(dbgs() << " SU(" << SU->NodeNum << ") uops=" << SchedModel->getNumMicroOps(SU->getInstr()) << '\n'); return true; @@ -1529,45 +1895,125 @@ 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) { - // 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. +// Find the unscheduled node in ReadySUs with the highest latency. +unsigned GenericScheduler::SchedBoundary:: +findMaxLatency(ArrayRef<SUnit*> ReadySUs) { + SUnit *LateSU = 0; unsigned RemLatency = 0; - for (ReadyQueue::iterator I = Available.begin(), E = Available.end(); + for (ArrayRef<SUnit*>::iterator I = ReadySUs.begin(), E = ReadySUs.end(); I != E; ++I) { unsigned L = getUnscheduledLatency(*I); - DEBUG(dbgs() << " " << Available.getName() - << " RemLatency SU(" << (*I)->NodeNum << ") " << L << '\n'); - if (L > RemLatency) + if (L > RemLatency) { 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 + SchedModel->getILPWindow(); - DEBUG(dbgs() << " " << Available.getName() - << " ExpectedLatency " << ExpectedLatency - << " CP Limit " << CriticalPathLimit << '\n'); - if (RemLatency + ExpectedLatency >= CriticalPathLimit - && RemLatency > Rem->getMaxRemainingCount(SchedModel)) { - Policy.ReduceLatency = true; - DEBUG(dbgs() << " Increase ILP: " << Available.getName() << '\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 GenericScheduler::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) + << " " << getResourceName(OtherCritIdx) << "\n"); } + return OtherCritCount; } -void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU, - unsigned ReadyCycle) { +/// Set the CandPolicy for this zone given the current resources and latencies +/// inside and outside the zone. +void GenericScheduler::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())); + + // 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 (ZoneCritResIdx == OtherCritIdx) + return; + DEBUG( + if (IsResourceLimited) { + dbgs() << " " << Available.getName() << " ResourceLimited: " + << getResourceName(ZoneCritResIdx) << "\n"; + } + if (OtherResLimited) + dbgs() << " RemainingLimit: " << getResourceName(OtherCritIdx) << "\n"; + if (!IsResourceLimited && !OtherResLimited) + dbgs() << " Latency limited both directions.\n"); + + if (IsResourceLimited && !Policy.ReduceResIdx) + Policy.ReduceResIdx = ZoneCritResIdx; + + if (OtherResLimited) + Policy.DemandResIdx = OtherCritIdx; +} + +void GenericScheduler::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); @@ -1577,16 +2023,21 @@ void ConvergingScheduler::SchedBoundary::releaseNode(SUnit *SU, } /// Move the boundary of scheduled code by one cycle. -void ConvergingScheduler::SchedBoundary::bumpCycle() { - unsigned Width = SchedModel->getIssueWidth(); - IssueCount = (IssueCount <= Width) ? 0 : IssueCount - Width; - - unsigned NextCycle = CurrCycle + 1; - assert(MinReadyCycle < UINT_MAX && "MinReadyCycle uninitialized"); - if (MinReadyCycle > NextCycle) { - IssueCount = 0; - NextCycle = MinReadyCycle; - } +void GenericScheduler::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. @@ -1602,38 +2053,54 @@ 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() << "Cycle: " << CurrCycle << ' ' << Available.getName() << '\n'); +} - DEBUG(dbgs() << " " << Available.getName() - << " Cycle: " << CurrCycle << '\n'); +void GenericScheduler::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 GenericScheduler::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; + // 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->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. -void ConvergingScheduler::SchedBoundary::bumpNode(SUnit *SU) { +void GenericScheduler::SchedBoundary::bumpNode(SUnit *SU) { // Update the reservation table. if (HazardRec->isEnabled()) { if (!isTop() && SU->isCall) { @@ -1643,51 +2110,108 @@ 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; } } - if (isTop()) { - if (SU->getDepth() > ExpectedLatency) - ExpectedLatency = SU->getDepth(); + // 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"); } - else { - if (SU->getHeight() > ExpectedLatency) - ExpectedLatency = SU->getHeight(); + if (SU->getHeight() > BotLatency) { + BotLatency = SU->getHeight(); + DEBUG(dbgs() << " " << Available.getName() + << " BotLatency SU(" << SU->NodeNum << ") " << BotLatency << "c\n"); } - - IsResourceLimited = getCriticalCount() > std::max(ExpectedLatency, CurrCycle); - - // Check the instruction group dispatch limit. - // TODO: Check if this SU must end a dispatch group. - IssueCount += 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 (IssueCount >= SchedModel->getIssueWidth()) { - DEBUG(dbgs() << " *** Max instrs at cycle " << CurrCycle << '\n'); - bumpCycle(); + // 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 /// visible to heuristics. -void ConvergingScheduler::SchedBoundary::releasePending() { +void GenericScheduler::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; @@ -1695,7 +2219,7 @@ void ConvergingScheduler::SchedBoundary::releasePending() { if (ReadyCycle < MinReadyCycle) MinReadyCycle = ReadyCycle; - if (ReadyCycle > CurrCycle) + if (!IsBuffered && ReadyCycle > CurrCycle) continue; if (checkHazard(SU)) @@ -1710,7 +2234,7 @@ void ConvergingScheduler::SchedBoundary::releasePending() { } /// Remove SU from the ready set for this boundary. -void ConvergingScheduler::SchedBoundary::removeReady(SUnit *SU) { +void GenericScheduler::SchedBoundary::removeReady(SUnit *SU) { if (Available.isInQueue(SU)) Available.remove(Available.find(SU)); else { @@ -1722,11 +2246,11 @@ void ConvergingScheduler::SchedBoundary::removeReady(SUnit *SU) { /// If this queue only has one ready candidate, return it. As a side effect, /// defer any nodes that now hit a hazard, and advance the cycle until at least /// one node is ready. If multiple instructions are ready, return NULL. -SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() { +SUnit *GenericScheduler::SchedBoundary::pickOnlyChoice() { if (CheckPending) releasePending(); - if (IssueCount > 0) { + if (CurrMOps > 0) { // Defer any ready instrs that now have a hazard. for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) { if (checkHazard(*I)) { @@ -1738,9 +2262,9 @@ SUnit *ConvergingScheduler::SchedBoundary::pickOnlyChoice() { } } for (unsigned i = 0; Available.empty(); ++i) { - assert(i <= (HazardRec->getMaxLookAhead() + MaxMinLatency) && + assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedLatency) && "permanent hazard"); (void)i; - bumpCycle(); + bumpCycle(CurrCycle + 1); releasePending(); } if (Available.size() == 1) @@ -1748,106 +2272,33 @@ 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'); - } -} - -/// 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; +#ifndef NDEBUG +// This is useful information to dump after bumpNode. +// Note that the Queue contents are more useful before pickNodeFromQueue. +void GenericScheduler::SchedBoundary::dumpScheduledState() { + unsigned ResFactor; + unsigned ResCount; + if (ZoneCritResIdx) { + ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx); + ResCount = getResourceCount(ZoneCritResIdx); } - // 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); + 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 << " " << getResourceName(ZoneCritResIdx) + << "\n ExpectedLatency: " << ExpectedLatency << "c\n" + << (IsResourceLimited ? " - Resource" : " - Latency") + << " limited.\n"; } +#endif -void ConvergingScheduler::SchedCandidate:: +void GenericScheduler::SchedCandidate:: initResourceDelta(const ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { if (!Policy.ReduceResIdx && !Policy.DemandResIdx) @@ -1864,11 +2315,12 @@ initResourceDelta(const ScheduleDAGMI *DAG, } } + /// Return true if this heuristic determines order. static bool tryLess(int TryVal, int CandVal, - ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::CandReason Reason) { + GenericScheduler::SchedCandidate &TryCand, + GenericScheduler::SchedCandidate &Cand, + GenericScheduler::CandReason Reason) { if (TryVal < CandVal) { TryCand.Reason = Reason; return true; @@ -1878,13 +2330,14 @@ static bool tryLess(int TryVal, int CandVal, Cand.Reason = Reason; return true; } + Cand.setRepeat(Reason); return false; } static bool tryGreater(int TryVal, int CandVal, - ConvergingScheduler::SchedCandidate &TryCand, - ConvergingScheduler::SchedCandidate &Cand, - ConvergingScheduler::CandReason Reason) { + GenericScheduler::SchedCandidate &TryCand, + GenericScheduler::SchedCandidate &Cand, + GenericScheduler::CandReason Reason) { if (TryVal > CandVal) { TryCand.Reason = Reason; return true; @@ -1894,9 +2347,34 @@ static bool tryGreater(int TryVal, int CandVal, Cand.Reason = Reason; return true; } + Cand.setRepeat(Reason); return false; } +static bool tryPressure(const PressureChange &TryP, + const PressureChange &CandP, + GenericScheduler::SchedCandidate &TryCand, + GenericScheduler::SchedCandidate &Cand, + GenericScheduler::CandReason Reason) { + int TryRank = TryP.getPSetOrMax(); + int CandRank = CandP.getPSetOrMax(); + // If both candidates affect the same set, go with the smallest increase. + if (TryRank == CandRank) { + return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand, + Reason); + } + // If one candidate decreases and the other increases, go with it. + // Invalid candidates have UnitInc==0. + if (tryLess(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand, + Reason)) { + return true; + } + // If 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; } @@ -1929,6 +2407,32 @@ static int biasPhysRegCopy(const SUnit *SU, bool isTop) { return 0; } +static bool tryLatency(GenericScheduler::SchedCandidate &TryCand, + GenericScheduler::SchedCandidate &Cand, + GenericScheduler::SchedBoundary &Zone) { + if (Zone.isTop()) { + if (Cand.SU->getDepth() > Zone.getScheduledLatency()) { + if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), + TryCand, Cand, GenericScheduler::TopDepthReduce)) + return true; + } + if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), + TryCand, Cand, GenericScheduler::TopPathReduce)) + return true; + } + else { + if (Cand.SU->getHeight() > Zone.getScheduledLatency()) { + if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), + TryCand, Cand, GenericScheduler::BotHeightReduce)) + return true; + } + if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(), + TryCand, Cand, GenericScheduler::BotPathReduce)) + return true; + } + return false; +} + /// Apply a set of heursitics to a new candidate. Heuristics are currently /// hierarchical. This may be more efficient than a graduated cost model because /// we don't need to evaluate all aspects of the model for each node in the @@ -1940,16 +2444,44 @@ static int biasPhysRegCopy(const SUnit *SU, bool isTop) { /// \param Zone describes the scheduled zone that we are extending. /// \param RPTracker describes reg pressure within the scheduled zone. /// \param TempTracker is a scratch pressure tracker to reuse in queries. -void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, +void GenericScheduler::tryCandidate(SchedCandidate &Cand, SchedCandidate &TryCand, SchedBoundary &Zone, const RegPressureTracker &RPTracker, RegPressureTracker &TempTracker) { - // Always initialize TryCand's RPDelta. - TempTracker.getMaxPressureDelta(TryCand.SU->getInstr(), TryCand.RPDelta, - DAG->getRegionCriticalPSets(), - DAG->getRegPressure().MaxSetPressure); + 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()) { @@ -1962,20 +2494,25 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, TryCand, Cand, PhysRegCopy)) return; - // Avoid exceeding the target's limit. - if (tryLess(TryCand.RPDelta.Excess.UnitIncrease, - Cand.RPDelta.Excess.UnitIncrease, TryCand, Cand, SingleExcess)) + // Avoid exceeding the target's limit. If signed PSetID is negative, it is + // invalid; convert it to INT_MAX to give it lowest priority. + if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess, + Cand.RPDelta.Excess, + TryCand, Cand, RegExcess)) return; - if (Cand.Reason == SingleExcess) - Cand.Reason = MultiPressure; // Avoid increasing the max critical pressure in the scheduled region. - if (tryLess(TryCand.RPDelta.CriticalMax.UnitIncrease, - Cand.RPDelta.CriticalMax.UnitIncrease, - TryCand, Cand, SingleCritical)) + 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.CurrMOps + && tryLatency(TryCand, Cand, Zone)) return; - if (Cand.Reason == SingleCritical) - Cand.Reason = MultiPressure; // Keep clustered nodes together to encourage downstream peephole // optimizations which may reduce resource requirements. @@ -1990,17 +2527,17 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, return; // Weak edges are for clustering and other constraints. - // - // Deferring TryCand here does not change Cand's reason. This is good in the - // sense that a bad candidate shouldn't affect a previous candidate's - // goodness, but bad in that it is assymetric and depends on queue order. - CandReason OrigReason = Cand.Reason; if (tryLess(getWeakLeft(TryCand.SU, Zone.isTop()), getWeakLeft(Cand.SU, Zone.isTop()), TryCand, Cand, Weak)) { - Cand.Reason = OrigReason; 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, @@ -2012,41 +2549,15 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, return; // Avoid serializing long latency dependence chains. - if (Cand.Policy.ReduceLatency) { - if (Zone.isTop()) { - if (Cand.SU->getDepth() * SchedModel->getLatencyFactor() - > Zone.ExpectedCount) { - if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), - TryCand, Cand, TopDepthReduce)) - return; - } - if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), - TryCand, Cand, TopPathReduce)) - return; - } - else { - if (Cand.SU->getHeight() * SchedModel->getLatencyFactor() - > Zone.ExpectedCount) { - if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), - TryCand, Cand, BotHeightReduce)) - return; - } - if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(), - TryCand, Cand, BotPathReduce)) - return; - } - } - - // Avoid increasing the max pressure of the entire region. - if (tryLess(TryCand.RPDelta.CurrentMax.UnitIncrease, - Cand.RPDelta.CurrentMax.UnitIncrease, TryCand, Cand, SingleMax)) + // For acyclic path limited loops, latency was already checked above. + if (Cand.Policy.ReduceLatency && !Rem.IsAcyclicLatencyLimited + && tryLatency(TryCand, Cand, Zone)) { return; - if (Cand.Reason == SingleMax) - 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; @@ -2058,49 +2569,17 @@ void ConvergingScheduler::tryCandidate(SchedCandidate &Cand, } } -/// pickNodeFromQueue helper that returns true if the LHS reg pressure effect is -/// more desirable than RHS from scheduling standpoint. -static bool compareRPDelta(const RegPressureDelta &LHS, - const RegPressureDelta &RHS) { - // Compare each component of pressure in decreasing order of importance - // without checking if any are valid. Invalid PressureElements are assumed to - // have UnitIncrease==0, so are neutral. - - // Avoid increasing the max critical pressure in the scheduled region. - if (LHS.Excess.UnitIncrease != RHS.Excess.UnitIncrease) { - DEBUG(dbgs() << " RP excess top - bot: " - << (LHS.Excess.UnitIncrease - RHS.Excess.UnitIncrease) << '\n'); - return LHS.Excess.UnitIncrease < RHS.Excess.UnitIncrease; - } - // Avoid increasing the max critical pressure in the scheduled region. - if (LHS.CriticalMax.UnitIncrease != RHS.CriticalMax.UnitIncrease) { - DEBUG(dbgs() << " RP critical top - bot: " - << (LHS.CriticalMax.UnitIncrease - RHS.CriticalMax.UnitIncrease) - << '\n'); - return LHS.CriticalMax.UnitIncrease < RHS.CriticalMax.UnitIncrease; - } - // Avoid increasing the max pressure of the entire region. - if (LHS.CurrentMax.UnitIncrease != RHS.CurrentMax.UnitIncrease) { - DEBUG(dbgs() << " RP current top - bot: " - << (LHS.CurrentMax.UnitIncrease - RHS.CurrentMax.UnitIncrease) - << '\n'); - return LHS.CurrentMax.UnitIncrease < RHS.CurrentMax.UnitIncrease; - } - return false; -} - #ifndef NDEBUG -const char *ConvergingScheduler::getReasonStr( - ConvergingScheduler::CandReason Reason) { +const char *GenericScheduler::getReasonStr( + GenericScheduler::CandReason Reason) { switch (Reason) { case NoCand: return "NOCAND "; case PhysRegCopy: return "PREG-COPY"; - case SingleExcess: return "REG-EXCESS"; - case SingleCritical: return "REG-CRIT "; + case RegExcess: return "REG-EXCESS"; + case RegCritical: return "REG-CRIT "; case Cluster: return "CLUSTER "; case Weak: return "WEAK "; - case SingleMax: return "REG-MAX "; - case MultiPressure: return "REG-MULTI "; + case RegMax: return "REG-MAX "; case ResourceReduce: return "RES-REDUCE"; case ResourceDemand: return "RES-DEMAND"; case TopDepthReduce: return "TOP-DEPTH "; @@ -2113,20 +2592,20 @@ const char *ConvergingScheduler::getReasonStr( llvm_unreachable("Unknown reason!"); } -void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) { - PressureElement P; +void GenericScheduler::traceCandidate(const SchedCandidate &Cand) { + PressureChange P; unsigned ResIdx = 0; unsigned Latency = 0; switch (Cand.Reason) { default: break; - case SingleExcess: + case RegExcess: P = Cand.RPDelta.Excess; break; - case SingleCritical: + case RegCritical: P = Cand.RPDelta.CriticalMax; break; - case SingleMax: + case RegMax: P = Cand.RPDelta.CurrentMax; break; case ResourceReduce: @@ -2150,8 +2629,8 @@ void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) { } dbgs() << " SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason); if (P.isValid()) - dbgs() << " " << TRI->getRegPressureSetName(P.PSetID) - << ":" << P.UnitIncrease << " "; + dbgs() << " " << TRI->getRegPressureSetName(P.getPSet()) + << ":" << P.getUnitInc() << " "; else dbgs() << " "; if (ResIdx) @@ -2166,12 +2645,12 @@ void ConvergingScheduler::traceCandidate(const SchedCandidate &Cand) { } #endif -/// Pick the best candidate from the top queue. +/// Pick the best candidate from the queue. /// /// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during /// DAG building. To adjust for the current scheduling location we need to /// maintain the number of vreg uses remaining to be top-scheduled. -void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone, +void GenericScheduler::pickNodeFromQueue(SchedBoundary &Zone, const RegPressureTracker &RPTracker, SchedCandidate &Cand) { ReadyQueue &Q = Zone.Available; @@ -2196,30 +2675,31 @@ void ConvergingScheduler::pickNodeFromQueue(SchedBoundary &Zone, } } -static void tracePick(const ConvergingScheduler::SchedCandidate &Cand, +static void tracePick(const GenericScheduler::SchedCandidate &Cand, bool IsTop) { DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ") - << ConvergingScheduler::getReasonStr(Cand.Reason) << '\n'); + << GenericScheduler::getReasonStr(Cand.Reason) << '\n'); } /// Pick the best candidate node from either the top or bottom queue. -SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { +SUnit *GenericScheduler::pickNodeBidirectional(bool &IsTopNode) { // Schedule as far as possible in the direction of no choice. This is most // efficient, but also provides the best heuristics for CriticalPSets. if (SUnit *SU = Bot.pickOnlyChoice()) { 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); @@ -2232,7 +2712,10 @@ SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { // 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 == SingleExcess || BotCand.Reason == SingleCritical) { + if ((BotCand.Reason == RegExcess && !BotCand.isRepeat(RegExcess)) + || (BotCand.Reason == RegCritical + && !BotCand.isRepeat(RegCritical))) + { IsTopNode = false; tracePick(BotCand, IsTopNode); return BotCand.SU; @@ -2241,37 +2724,20 @@ SUnit *ConvergingScheduler::pickNodeBidirectional(bool &IsTopNode) { pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand); assert(TopCand.Reason != NoCand && "failed to find the first candidate"); - // If either Q has a single candidate that minimizes pressure above the - // original region's pressure pick it. - if (TopCand.Reason <= SingleMax || BotCand.Reason <= SingleMax) { - if (TopCand.Reason < BotCand.Reason) { - IsTopNode = true; - tracePick(TopCand, IsTopNode); - return TopCand.SU; - } - IsTopNode = false; - tracePick(BotCand, IsTopNode); - return BotCand.SU; - } - // Check for a salient pressure difference and pick the best from either side. - if (compareRPDelta(TopCand.RPDelta, BotCand.RPDelta)) { - IsTopNode = true; - tracePick(TopCand, IsTopNode); - return TopCand.SU; - } - // Otherwise prefer the bottom candidate, in node order if all else failed. + // 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 *ConvergingScheduler::pickNode(bool &IsTopNode) { +SUnit *GenericScheduler::pickNode(bool &IsTopNode) { if (DAG->top() == DAG->bottom()) { assert(Top.Available.empty() && Top.Pending.empty() && Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage"); @@ -2279,24 +2745,26 @@ SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) { } SUnit *SU; do { - if (ForceTopDown) { + if (RegionPolicy.OnlyTopDown) { SU = Top.pickOnlyChoice(); if (!SU) { CandPolicy NoPolicy; SchedCandidate TopCand(NoPolicy); pickNodeFromQueue(Top, DAG->getTopRPTracker(), TopCand); - assert(TopCand.Reason != NoCand && "failed to find the first candidate"); + assert(TopCand.Reason != NoCand && "failed to find a candidate"); + tracePick(TopCand, true); SU = TopCand.SU; } IsTopNode = true; } - else if (ForceBottomUp) { + else if (RegionPolicy.OnlyBottomUp) { SU = Bot.pickOnlyChoice(); if (!SU) { CandPolicy NoPolicy; SchedCandidate BotCand(NoPolicy); pickNodeFromQueue(Bot, DAG->getBotRPTracker(), BotCand); - assert(BotCand.Reason != NoCand && "failed to find the first candidate"); + assert(BotCand.Reason != NoCand && "failed to find a candidate"); + tracePick(BotCand, false); SU = BotCand.SU; } IsTopNode = false; @@ -2315,7 +2783,7 @@ SUnit *ConvergingScheduler::pickNode(bool &IsTopNode) { return SU; } -void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { +void GenericScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { MachineBasicBlock::iterator InsertPos = SU->getInstr(); if (!isTop) @@ -2346,15 +2814,15 @@ void ConvergingScheduler::reschedulePhysRegCopies(SUnit *SU, bool isTop) { /// /// FIXME: Eventually, we may bundle physreg copies rather than rescheduling /// them here. See comments in biasPhysRegCopy. -void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) { +void GenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { if (IsTopNode) { - SU->TopReadyCycle = 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); @@ -2363,26 +2831,23 @@ void ConvergingScheduler::schedNode(SUnit *SU, bool IsTopNode) { /// Create the standard converging machine scheduler. This will be used as the /// default scheduler if the target does not set a default. -static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C) { - assert((!ForceTopDown || !ForceBottomUp) && - "-misched-topdown incompatible with -misched-bottomup"); - ScheduleDAGMI *DAG = new ScheduleDAGMI(C, new ConvergingScheduler()); +static ScheduleDAGInstrs *createGenericSched(MachineSchedContext *C) { + ScheduleDAGMI *DAG = new ScheduleDAGMI(C, new 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. - if (EnableCopyConstrain) - DAG->addMutation(new CopyConstrain(DAG->TII, DAG->TRI)); - if (EnableLoadCluster) + DAG->addMutation(new CopyConstrain(DAG->TII, DAG->TRI)); + if (EnableLoadCluster && DAG->TII->enableClusterLoads()) DAG->addMutation(new LoadClusterMutation(DAG->TII, DAG->TRI)); if (EnableMacroFusion) DAG->addMutation(new MacroFusion(DAG->TII)); return DAG; } static MachineSchedRegistry -ConvergingSchedRegistry("converge", "Standard converging scheduler.", - createConvergingSched); +GenericSchedRegistry("converge", "Standard converging scheduler.", + createGenericSched); //===----------------------------------------------------------------------===// // ILP Scheduler. Currently for experimental analysis of heuristics. @@ -2424,15 +2889,6 @@ struct ILPOrder { /// \brief Schedule based on the ILP metric. class ILPScheduler : public MachineSchedStrategy { - /// In case all subtrees are eventually connected to a common root through - /// data dependence (e.g. reduction), place an upper limit on their size. - /// - /// FIXME: A subtree limit is generally good, but in the situation commented - /// above, where multiple similar subtrees feed a common root, we should - /// only split at a point where the resulting subtrees will be balanced. - /// (a motivating test case must be found). - static const unsigned SubtreeLimit = 16; - ScheduleDAGMI *DAG; ILPOrder Cmp; @@ -2616,7 +3072,7 @@ struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits { } static bool isNodeHidden(const SUnit *Node) { - return (Node->NumPreds > 10 || Node->NumSuccs > 10); + return (Node->Preds.size() > 10 || Node->Succs.size() > 10); } static bool hasNodeAddressLabel(const SUnit *Node, @@ -2639,7 +3095,11 @@ struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits { static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) { std::string Str; raw_string_ostream SS(Str); - SS << "SU(" << SU->NodeNum << ')'; + const SchedDFSResult *DFS = + static_cast<const ScheduleDAGMI*>(G)->getDFSResult(); + SS << "SU:" << SU->NodeNum; + if (DFS) + SS << " I:" << DFS->getNumInstrs(SU); return SS.str(); } static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) { |
