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LLVM
3.7.0
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GenericScheduler shrinks the unscheduled zone using heuristics to balance the schedule. More...
#include <MachineScheduler.h>
Public Member Functions | |
| GenericScheduler (const MachineSchedContext *C) | |
| void | initPolicy (MachineBasicBlock::iterator Begin, MachineBasicBlock::iterator End, unsigned NumRegionInstrs) override |
| Initialize the per-region scheduling policy. More... | |
| bool | shouldTrackPressure () const override |
| Check if pressure tracking is needed before building the DAG and initializing this strategy. More... | |
| void | initialize (ScheduleDAGMI *dag) override |
| Initialize the strategy after building the DAG for a new region. More... | |
| SUnit * | pickNode (bool &IsTopNode) override |
| Pick the best node to balance the schedule. Implements MachineSchedStrategy. More... | |
| void | schedNode (SUnit *SU, bool IsTopNode) override |
| Update the scheduler's state after scheduling a node. More... | |
| void | releaseTopNode (SUnit *SU) override |
| When all predecessor dependencies have been resolved, free this node for top-down scheduling. More... | |
| void | releaseBottomNode (SUnit *SU) override |
| When all successor dependencies have been resolved, free this node for bottom-up scheduling. More... | |
| void | registerRoots () override |
| Notify this strategy that all roots have been released (including those that depend on EntrySU or ExitSU). More... | |
Public Member Functions inherited from llvm::MachineSchedStrategy | |
| virtual | ~MachineSchedStrategy () |
| virtual void | scheduleTree (unsigned SubtreeID) |
| Scheduler callback to notify that a new subtree is scheduled. More... | |
Protected Member Functions | |
| void | checkAcyclicLatency () |
| Set IsAcyclicLatencyLimited if the acyclic path is longer than the cyclic critical path by more cycles than it takes to drain the instruction buffer. More... | |
| void | tryCandidate (SchedCandidate &Cand, SchedCandidate &TryCand, SchedBoundary &Zone, const RegPressureTracker &RPTracker, RegPressureTracker &TempTracker) |
| Apply a set of heursitics to a new candidate. More... | |
| SUnit * | pickNodeBidirectional (bool &IsTopNode) |
| Pick the best candidate node from either the top or bottom queue. More... | |
| void | pickNodeFromQueue (SchedBoundary &Zone, const RegPressureTracker &RPTracker, SchedCandidate &Candidate) |
| Pick the best candidate from the queue. More... | |
| void | reschedulePhysRegCopies (SUnit *SU, bool isTop) |
Protected Member Functions inherited from llvm::GenericSchedulerBase | |
| GenericSchedulerBase (const MachineSchedContext *C) | |
| void | setPolicy (CandPolicy &Policy, bool IsPostRA, SchedBoundary &CurrZone, SchedBoundary *OtherZone) |
| Set the CandPolicy given a scheduling zone given the current resources and latencies inside and outside the zone. More... | |
| void | traceCandidate (const SchedCandidate &Cand) |
Additional Inherited Members | |
Public Types inherited from llvm::GenericSchedulerBase | |
| enum | CandReason { NoCand, PhysRegCopy, RegExcess, RegCritical, Stall, Cluster, Weak, RegMax, ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce, TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder } |
| Represent the type of SchedCandidate found within a single queue. More... | |
Static Public Member Functions inherited from llvm::GenericSchedulerBase | |
| static const char * | getReasonStr (GenericSchedulerBase::CandReason Reason) |
Protected Attributes inherited from llvm::GenericSchedulerBase | |
| const MachineSchedContext * | Context |
| const TargetSchedModel * | SchedModel |
| const TargetRegisterInfo * | TRI |
| SchedRemainder | Rem |
GenericScheduler shrinks the unscheduled zone using heuristics to balance the schedule.
Definition at line 844 of file MachineScheduler.h.
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inline |
Definition at line 853 of file MachineScheduler.h.
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protected |
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.
Definition at line 2450 of file MachineScheduler.cpp.
References llvm::SchedRemainder::CriticalPath, llvm::SchedRemainder::CyclicCritPath, llvm::dbgs(), DEBUG, llvm::TargetSchedModel::getLatencyFactor(), llvm::TargetSchedModel::getMicroOpBufferSize(), llvm::TargetSchedModel::getMicroOpFactor(), llvm::SchedRemainder::IsAcyclicLatencyLimited, llvm::GenericSchedulerBase::Rem, llvm::SchedRemainder::RemIssueCount, and llvm::GenericSchedulerBase::SchedModel.
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overridevirtual |
Initialize the strategy after building the DAG for a new region.
Implements llvm::MachineSchedStrategy.
Definition at line 2365 of file MachineScheduler.cpp.
References llvm::TargetSchedModel::getInstrItineraries(), llvm::ScheduleDAGMI::hasVRegLiveness(), llvm::SchedRemainder::init(), llvm::GenericSchedulerBase::Rem, llvm::GenericSchedulerBase::SchedModel, and llvm::GenericSchedulerBase::TRI.
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overridevirtual |
Initialize the per-region scheduling policy.
Reimplemented from llvm::MachineSchedStrategy.
Definition at line 2394 of file MachineScheduler.cpp.
References llvm::GenericSchedulerBase::Context, EnableRegPressure, llvm::ForceBottomUp, llvm::ForceTopDown, llvm::RegisterClassInfo::getNumAllocatableRegs(), llvm::TargetLoweringBase::getRegClassFor(), llvm::MachineFunction::getSubtarget(), llvm::TargetSubtargetInfo::getTargetLowering(), llvm::MVT::i1, llvm::MVT::i32, llvm::TargetLoweringBase::isTypeLegal(), llvm::TargetSubtargetInfo::overrideSchedPolicy(), and llvm::MachineSchedContext::RegClassInfo.
Pick the best node to balance the schedule. Implements MachineSchedStrategy.
Implements llvm::MachineSchedStrategy.
Definition at line 2784 of file MachineScheduler.cpp.
References llvm::ScheduleDAGMI::bottom(), llvm::dbgs(), DEBUG, llvm::SUnit::getInstr(), llvm::SUnit::isBottomReady(), llvm::SUnit::isScheduled, llvm::SUnit::isTopReady(), llvm::GenericSchedulerBase::NoCand, llvm::SUnit::NodeNum, llvm::GenericSchedulerBase::SchedCandidate::Reason, llvm::GenericSchedulerBase::SchedCandidate::SU, llvm::ScheduleDAGMI::top(), and tracePick().
Pick the best candidate node from either the top or bottom queue.
Definition at line 2725 of file MachineScheduler.cpp.
References llvm::dbgs(), DEBUG, llvm::GenericSchedulerBase::SchedCandidate::isRepeat(), llvm::GenericSchedulerBase::NoCand, llvm::GenericSchedulerBase::SchedCandidate::Policy, llvm::GenericSchedulerBase::SchedCandidate::Reason, llvm::GenericSchedulerBase::RegCritical, llvm::GenericSchedulerBase::RegExcess, llvm::GenericSchedulerBase::setPolicy(), llvm::GenericSchedulerBase::SchedCandidate::SU, and tracePick().
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protected |
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.
Definition at line 2699 of file MachineScheduler.cpp.
References llvm::SchedBoundary::Available, llvm::ReadyQueue::begin(), DEBUG, llvm::ReadyQueue::dump(), llvm::ReadyQueue::end(), I, llvm::GenericSchedulerBase::SchedCandidate::initResourceDelta(), llvm::GenericSchedulerBase::NoCand, llvm::GenericSchedulerBase::SchedCandidate::Policy, llvm::GenericSchedulerBase::SchedCandidate::Reason, llvm::GenericSchedulerBase::SchedCandidate::ResDelta, llvm::GenericSchedulerBase::SchedModel, llvm::GenericSchedulerBase::SchedCandidate::setBest(), llvm::GenericSchedulerBase::SchedCandidate::SU, and llvm::GenericSchedulerBase::traceCandidate().
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overridevirtual |
Notify this strategy that all roots have been released (including those that depend on EntrySU or ExitSU).
Reimplemented from llvm::MachineSchedStrategy.
Definition at line 2478 of file MachineScheduler.cpp.
References llvm::SchedRemainder::CriticalPath, llvm::SchedRemainder::CyclicCritPath, llvm::dbgs(), DEBUG, llvm::DumpCriticalPathLength, EnableCyclicPath, llvm::errs(), llvm::ScheduleDAG::ExitSU, llvm::SUnit::getDepth(), I, and llvm::GenericSchedulerBase::Rem.
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inlineoverridevirtual |
When all successor dependencies have been resolved, free this node for bottom-up scheduling.
Implements llvm::MachineSchedStrategy.
Definition at line 875 of file MachineScheduler.h.
References llvm::SchedBoundary::releaseBottomNode().
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inlineoverridevirtual |
When all predecessor dependencies have been resolved, free this node for top-down scheduling.
Implements llvm::MachineSchedStrategy.
Definition at line 871 of file MachineScheduler.h.
References llvm::SchedBoundary::releaseTopNode().
Definition at line 2830 of file MachineScheduler.cpp.
References llvm::SmallVectorTemplateCommon< T >::begin(), llvm::SDep::Data, llvm::dbgs(), DEBUG, llvm::SmallVectorTemplateCommon< T >::end(), llvm::SUnit::getInstr(), I, llvm::MachineInstr::isCopy(), llvm::TargetRegisterInfo::isPhysicalRegister(), llvm::ScheduleDAGMI::moveInstruction(), llvm::SUnit::Preds, llvm::SUnit::Succs, and llvm::GenericSchedulerBase::TRI.
Update the scheduler's state after scheduling a node.
This is the same node that was just returned by pickNode(). However, ScheduleDAGMILive needs to update it's state based on the current cycle before MachineSchedStrategy does.
FIXME: Eventually, we may bundle physreg copies rather than rescheduling them here. See comments in biasPhysRegCopy.
Implements llvm::MachineSchedStrategy.
Definition at line 2862 of file MachineScheduler.cpp.
References llvm::SUnit::BotReadyCycle, llvm::SUnit::hasPhysRegDefs, llvm::SUnit::hasPhysRegUses, and llvm::SUnit::TopReadyCycle.
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inlineoverridevirtual |
Check if pressure tracking is needed before building the DAG and initializing this strategy.
Called after initPolicy.
Reimplemented from llvm::MachineSchedStrategy.
Definition at line 861 of file MachineScheduler.h.
References llvm::MachineSchedPolicy::ShouldTrackPressure.
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protected |
Apply a set of heursitics to a new candidate.
Heuristics are currently hierarchical. This may be more efficient than a graduated cost model because we don't need to evaluate all aspects of the model for each node in the queue. But it's really done to make the heuristics easier to debug and statistically analyze.
| Cand | provides the policy and current best candidate. |
| TryCand | refers to the next SUnit candidate, otherwise uninitialized. |
| Zone | describes the scheduled zone that we are extending. |
| RPTracker | describes reg pressure within the scheduled zone. |
| TempTracker | is a scratch pressure tracker to reuse in queries. |
Definition at line 2565 of file MachineScheduler.cpp.
References biasPhysRegCopy(), llvm::GenericSchedulerBase::Cluster, llvm::RegPressureDelta::CriticalMax, llvm::GenericSchedulerBase::SchedResourceDelta::CritResources, llvm::RegPressureDelta::CurrentMax, llvm::dbgs(), DEBUG, llvm::GenericSchedulerBase::SchedResourceDelta::DemandedResources, llvm::RegPressureDelta::Excess, llvm::SchedBoundary::getCurrMOps(), llvm::SUnit::getInstr(), llvm::SchedBoundary::getLatencyStallCycles(), llvm::RegPressureTracker::getMaxDownwardPressureDelta(), llvm::RegPressureTracker::getMaxUpwardPressureDelta(), llvm::ScheduleDAGMI::getNextClusterPred(), llvm::ScheduleDAGMI::getNextClusterSucc(), llvm::PressureChange::getPSet(), llvm::TargetRegisterInfo::getRegPressureSetName(), llvm::PressureChange::getUnitInc(), llvm::RegPressureTracker::getUpwardPressureDelta(), getWeakLeft(), llvm::GenericSchedulerBase::SchedCandidate::initResourceDelta(), llvm::SchedRemainder::IsAcyclicLatencyLimited, llvm::SchedBoundary::isNextSU(), llvm::SchedBoundary::isTop(), llvm::PressureChange::isValid(), llvm::GenericSchedulerBase::SchedCandidate::isValid(), llvm::GenericSchedulerBase::NextDefUse, llvm::SUnit::NodeNum, llvm::GenericSchedulerBase::NodeOrder, llvm::GenericSchedulerBase::PhysRegCopy, llvm::GenericSchedulerBase::SchedCandidate::Reason, llvm::GenericSchedulerBase::RegCritical, llvm::GenericSchedulerBase::RegExcess, llvm::GenericSchedulerBase::RegMax, llvm::GenericSchedulerBase::Rem, llvm::GenericSchedulerBase::SchedCandidate::ResDelta, llvm::GenericSchedulerBase::ResourceDemand, llvm::GenericSchedulerBase::ResourceReduce, llvm::GenericSchedulerBase::SchedCandidate::RPDelta, llvm::GenericSchedulerBase::SchedModel, llvm::GenericSchedulerBase::Stall, llvm::GenericSchedulerBase::SchedCandidate::SU, llvm::GenericSchedulerBase::TRI, tryGreater(), tryLatency(), tryLess(), tryPressure(), VerifyScheduling, and llvm::GenericSchedulerBase::Weak.
1.8.6