LLVM  4.0.0
Public Member Functions | Protected Member Functions | Protected Attributes | List of all members
llvm::GenericScheduler Class Reference

GenericScheduler shrinks the unscheduled zone using heuristics to balance the schedule. More...

#include <MachineScheduler.h>

Inheritance diagram for llvm::GenericScheduler:
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Collaboration diagram for llvm::GenericScheduler:
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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...
 
void dumpPolicy () override
 
bool shouldTrackPressure () const override
 Check if pressure tracking is needed before building the DAG and initializing this strategy. More...
 
bool shouldTrackLaneMasks () const override
 Returns true if lanemasks should be tracked. More...
 
void initialize (ScheduleDAGMI *dag) override
 Initialize the strategy after building the DAG for a new region. More...
 
SUnitpickNode (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 ()=default
 
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 initCandidate (SchedCandidate &Cand, SUnit *SU, bool AtTop, const RegPressureTracker &RPTracker, RegPressureTracker &TempTracker)
 
void tryCandidate (SchedCandidate &Cand, SchedCandidate &TryCand, SchedBoundary *Zone)
 Apply a set of heursitics to a new candidate. More...
 
SUnitpickNodeBidirectional (bool &IsTopNode)
 Pick the best candidate node from either the top or bottom queue. More...
 
void pickNodeFromQueue (SchedBoundary &Zone, const CandPolicy &ZonePolicy, 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)
 

Protected Attributes

ScheduleDAGMILiveDAG
 
MachineSchedPolicy RegionPolicy
 
SchedBoundary Top
 
SchedBoundary Bot
 
SchedCandidate TopCand
 Candidate last picked from Top boundary. More...
 
SchedCandidate BotCand
 Candidate last picked from Bot boundary. More...
 
- Protected Attributes inherited from llvm::GenericSchedulerBase
const MachineSchedContextContext
 
const TargetSchedModelSchedModel
 
const TargetRegisterInfoTRI
 
SchedRemainder Rem
 

Additional Inherited Members

- Public Types inherited from llvm::GenericSchedulerBase
enum  CandReason : uint8_t {
  NoCand, Only1, 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)
 

Detailed Description

GenericScheduler shrinks the unscheduled zone using heuristics to balance the schedule.

Definition at line 887 of file MachineScheduler.h.

Constructor & Destructor Documentation

llvm::GenericScheduler::GenericScheduler ( const MachineSchedContext C)
inline

Definition at line 889 of file MachineScheduler.h.

Member Function Documentation

void GenericScheduler::checkAcyclicLatency ( )
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 2685 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.

void GenericScheduler::dumpPolicy ( )
overridevirtual

Reimplemented from llvm::MachineSchedStrategy.

Definition at line 2668 of file MachineScheduler.cpp.

References llvm::dbgs().

void GenericScheduler::initCandidate ( SchedCandidate Cand,
SUnit SU,
bool  AtTop,
const RegPressureTracker RPTracker,
RegPressureTracker TempTracker 
)
protected
void GenericScheduler::initialize ( ScheduleDAGMI DAG)
overridevirtual
void GenericScheduler::initPolicy ( MachineBasicBlock::iterator  Begin,
MachineBasicBlock::iterator  End,
unsigned  NumRegionInstrs 
)
overridevirtual
SUnit * GenericScheduler::pickNode ( bool IsTopNode)
overridevirtual
SUnit * GenericScheduler::pickNodeBidirectional ( bool IsTopNode)
protected
void GenericScheduler::pickNodeFromQueue ( SchedBoundary Zone,
const CandPolicy ZonePolicy,
const RegPressureTracker RPTracker,
SchedCandidate Candidate 
)
protected
void GenericScheduler::registerRoots ( )
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 2713 of file MachineScheduler.cpp.

References llvm::SchedRemainder::CriticalPath, llvm::SchedRemainder::CyclicCritPath, llvm::dbgs(), DEBUG, llvm::DumpCriticalPathLength, E, EnableCyclicPath, llvm::errs(), llvm::ScheduleDAG::ExitSU, llvm::SUnit::getDepth(), I, and llvm::GenericSchedulerBase::Rem.

void llvm::GenericScheduler::releaseBottomNode ( SUnit SU)
inlineoverridevirtual

When all successor dependencies have been resolved, free this node for bottom-up scheduling.

Implements llvm::MachineSchedStrategy.

Definition at line 921 of file MachineScheduler.h.

References Bot, BotCand, llvm::SUnit::BotReadyCycle, llvm::SUnit::isScheduled, llvm::SchedBoundary::releaseNode(), and llvm::GenericSchedulerBase::SchedCandidate::SU.

void llvm::GenericScheduler::releaseTopNode ( SUnit SU)
inlineoverridevirtual

When all predecessor dependencies have been resolved, free this node for top-down scheduling.

Implements llvm::MachineSchedStrategy.

Definition at line 913 of file MachineScheduler.h.

References llvm::SUnit::isScheduled, llvm::SchedBoundary::releaseNode(), llvm::GenericSchedulerBase::SchedCandidate::SU, Top, TopCand, and llvm::SUnit::TopReadyCycle.

void GenericScheduler::reschedulePhysRegCopies ( SUnit SU,
bool  isTop 
)
protected
void GenericScheduler::schedNode ( SUnit SU,
bool  IsTopNode 
)
overridevirtual

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 3140 of file MachineScheduler.cpp.

References llvm::SUnit::BotReadyCycle, llvm::SUnit::hasPhysRegDefs, llvm::SUnit::hasPhysRegUses, and llvm::SUnit::TopReadyCycle.

bool llvm::GenericScheduler::shouldTrackLaneMasks ( ) const
inlineoverridevirtual

Returns true if lanemasks should be tracked.

LaneMask tracking is necessary to reorder independent subregister defs for the same vreg. This has to be enabled in combination with shouldTrackPressure().

Reimplemented from llvm::MachineSchedStrategy.

Definition at line 903 of file MachineScheduler.h.

References RegionPolicy, and llvm::MachineSchedPolicy::ShouldTrackLaneMasks.

bool llvm::GenericScheduler::shouldTrackPressure ( ) const
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 899 of file MachineScheduler.h.

References RegionPolicy, and llvm::MachineSchedPolicy::ShouldTrackPressure.

void GenericScheduler::tryCandidate ( SchedCandidate Cand,
SchedCandidate TryCand,
SchedBoundary Zone 
)
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.

Parameters
Candprovides the policy and current best candidate.
TryCandrefers to the next SUnit candidate, otherwise uninitialized.
Zonedescribes the scheduled zone that we are extending, or nullptr

Definition at line 2851 of file MachineScheduler.cpp.

References llvm::GenericSchedulerBase::SchedCandidate::AtTop, biasPhysRegCopy(), llvm::GenericSchedulerBase::Cluster, llvm::RegPressureDelta::CriticalMax, llvm::GenericSchedulerBase::SchedResourceDelta::CritResources, llvm::RegPressureDelta::CurrentMax, llvm::GenericSchedulerBase::SchedResourceDelta::DemandedResources, llvm::RegPressureDelta::Excess, llvm::SchedBoundary::getCurrMOps(), llvm::SchedBoundary::getLatencyStallCycles(), llvm::ScheduleDAGMI::getNextClusterPred(), llvm::ScheduleDAGMI::getNextClusterSucc(), getWeakLeft(), llvm::GenericSchedulerBase::SchedCandidate::initResourceDelta(), llvm::SchedRemainder::IsAcyclicLatencyLimited, llvm::SchedBoundary::isTop(), llvm::GenericSchedulerBase::SchedCandidate::isValid(), llvm::ScheduleDAG::MF, llvm::SUnit::NodeNum, llvm::GenericSchedulerBase::NodeOrder, llvm::GenericSchedulerBase::PhysRegCopy, llvm::GenericSchedulerBase::SchedCandidate::Policy, llvm::GenericSchedulerBase::SchedCandidate::Reason, llvm::GenericSchedulerBase::CandPolicy::ReduceLatency, 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(), and llvm::GenericSchedulerBase::Weak.

Member Data Documentation

SchedBoundary llvm::GenericScheduler::Bot
protected
SchedCandidate llvm::GenericScheduler::BotCand
protected

Candidate last picked from Bot boundary.

Definition at line 943 of file MachineScheduler.h.

Referenced by llvm::GCNMaxOccupancySchedStrategy::pickNode(), and releaseBottomNode().

ScheduleDAGMILive* llvm::GenericScheduler::DAG
protected

Definition at line 932 of file MachineScheduler.h.

Referenced by llvm::GCNMaxOccupancySchedStrategy::pickNode().

MachineSchedPolicy llvm::GenericScheduler::RegionPolicy
protected
SchedBoundary llvm::GenericScheduler::Top
protected
SchedCandidate llvm::GenericScheduler::TopCand
protected

Candidate last picked from Top boundary.

Definition at line 941 of file MachineScheduler.h.

Referenced by llvm::GCNMaxOccupancySchedStrategy::pickNode(), and releaseTopNode().


The documentation for this class was generated from the following files: