//
//===----------------------------------------------------------------------===//
//
-// This file provides a MachineSchedRegistry for registering alternative machine
-// schedulers. A Target may provide an alternative scheduler implementation by
+// This file provides an interface for customizing the standard MachineScheduler
+// pass. Note that the entire pass may be replaced as follows:
+//
+// <Target>TargetMachine::createPassConfig(PassManagerBase &PM) {
+// PM.substitutePass(&MachineSchedulerID, &CustomSchedulerPassID);
+// ...}
+//
+// The MachineScheduler pass is only responsible for choosing the regions to be
+// scheduled. Targets can override the DAG builder and scheduler without
+// replacing the pass as follows:
+//
+// ScheduleDAGInstrs *<Target>PassConfig::
+// createMachineScheduler(MachineSchedContext *C) {
+// return new CustomMachineScheduler(C);
+// }
+//
+// The default scheduler, ScheduleDAGMILive, builds the DAG and drives list
+// scheduling while updating the instruction stream, register pressure, and live
+// intervals. Most targets don't need to override the DAG builder and list
+// schedulier, but subtargets that require custom scheduling heuristics may
+// plugin an alternate MachineSchedStrategy. The strategy is responsible for
+// selecting the highest priority node from the list:
+//
+// ScheduleDAGInstrs *<Target>PassConfig::
+// createMachineScheduler(MachineSchedContext *C) {
+// return new ScheduleDAGMI(C, CustomStrategy(C));
+// }
+//
+// The DAG builder can also be customized in a sense by adding DAG mutations
+// that will run after DAG building and before list scheduling. DAG mutations
+// can adjust dependencies based on target-specific knowledge or add weak edges
+// to aid heuristics:
+//
+// ScheduleDAGInstrs *<Target>PassConfig::
+// createMachineScheduler(MachineSchedContext *C) {
+// ScheduleDAGMI *DAG = new ScheduleDAGMI(C, CustomStrategy(C));
+// DAG->addMutation(new CustomDependencies(DAG->TII, DAG->TRI));
+// return DAG;
+// }
+//
+// A target that supports alternative schedulers can use the
+// MachineSchedRegistry to allow command line selection. This can be done by
// implementing the following boilerplate:
//
// static ScheduleDAGInstrs *createCustomMachineSched(MachineSchedContext *C) {
// SchedCustomRegistry("custom", "Run my target's custom scheduler",
// createCustomMachineSched);
//
-// Inside <Target>PassConfig:
-// enablePass(&MachineSchedulerID);
-// MachineSchedRegistry::setDefault(createCustomMachineSched);
+//
+// Finally, subtargets that don't need to implement custom heuristics but would
+// like to configure the GenericScheduler's policy for a given scheduler region,
+// including scheduling direction and register pressure tracking policy, can do
+// this:
+//
+// void <SubTarget>Subtarget::
+// overrideSchedPolicy(MachineSchedPolicy &Policy,
+// MachineInstr *begin,
+// MachineInstr *end,
+// unsigned NumRegionInstrs) const {
+// Policy.<Flag> = true;
+// }
//
//===----------------------------------------------------------------------===//
-#ifndef MACHINESCHEDULER_H
-#define MACHINESCHEDULER_H
+#ifndef LLVM_CODEGEN_MACHINESCHEDULER_H
+#define LLVM_CODEGEN_MACHINESCHEDULER_H
#include "llvm/CodeGen/MachinePassRegistry.h"
#include "llvm/CodeGen/RegisterPressure.h"
#include "llvm/CodeGen/ScheduleDAGInstrs.h"
-#include "llvm/Target/TargetInstrInfo.h"
+
+#include <memory>
namespace llvm {
class MachineLoopInfo;
class RegisterClassInfo;
class ScheduleDAGInstrs;
+class SchedDFSResult;
+class ScheduleHazardRecognizer;
/// MachineSchedContext provides enough context from the MachineScheduler pass
/// for the target to instantiate a scheduler.
static MachineSchedRegistry *getList() {
return (MachineSchedRegistry *)Registry.getList();
}
- static ScheduleDAGCtor getDefault() {
- return (ScheduleDAGCtor)Registry.getDefault();
- }
- static void setDefault(ScheduleDAGCtor C) {
- Registry.setDefault((MachinePassCtor)C);
- }
- static void setDefault(StringRef Name) {
- Registry.setDefault(Name);
- }
static void setListener(MachinePassRegistryListener *L) {
Registry.setListener(L);
}
class ScheduleDAGMI;
+/// Define a generic scheduling policy for targets that don't provide their own
+/// MachineSchedStrategy. This can be overriden for each scheduling region
+/// before building the DAG.
+struct MachineSchedPolicy {
+ // Allow the scheduler to disable register pressure tracking.
+ bool ShouldTrackPressure;
+
+ // Allow the scheduler to force top-down or bottom-up scheduling. If neither
+ // is true, the scheduler runs in both directions and converges.
+ bool OnlyTopDown;
+ bool OnlyBottomUp;
+
+ MachineSchedPolicy(): ShouldTrackPressure(false), OnlyTopDown(false),
+ OnlyBottomUp(false) {}
+};
+
/// MachineSchedStrategy - Interface to the scheduling algorithm used by
/// ScheduleDAGMI.
+///
+/// Initialization sequence:
+/// initPolicy -> shouldTrackPressure -> initialize(DAG) -> registerRoots
class MachineSchedStrategy {
+ virtual void anchor();
public:
virtual ~MachineSchedStrategy() {}
+ /// Optionally override the per-region scheduling policy.
+ virtual void initPolicy(MachineBasicBlock::iterator Begin,
+ MachineBasicBlock::iterator End,
+ unsigned NumRegionInstrs) {}
+
+ /// Check if pressure tracking is needed before building the DAG and
+ /// initializing this strategy. Called after initPolicy.
+ virtual bool shouldTrackPressure() const { return true; }
+
/// Initialize the strategy after building the DAG for a new region.
virtual void initialize(ScheduleDAGMI *DAG) = 0;
/// be scheduled at the bottom.
virtual SUnit *pickNode(bool &IsTopNode) = 0;
+ /// \brief Scheduler callback to notify that a new subtree is scheduled.
+ virtual void scheduleTree(unsigned SubtreeID) {}
+
/// Notify MachineSchedStrategy that ScheduleDAGMI has scheduled an
/// instruction and updated scheduled/remaining flags in the DAG nodes.
virtual void schedNode(SUnit *SU, bool IsTopNode) = 0;
virtual void releaseBottomNode(SUnit *SU) = 0;
};
+/// Mutate the DAG as a postpass after normal DAG building.
+class ScheduleDAGMutation {
+ virtual void anchor();
+public:
+ virtual ~ScheduleDAGMutation() {}
+
+ virtual void apply(ScheduleDAGMI *DAG) = 0;
+};
+
+/// ScheduleDAGMI is an implementation of ScheduleDAGInstrs that simply
+/// schedules machine instructions according to the given MachineSchedStrategy
+/// without much extra book-keeping. This is the common functionality between
+/// PreRA and PostRA MachineScheduler.
+class ScheduleDAGMI : public ScheduleDAGInstrs {
+protected:
+ AliasAnalysis *AA;
+ std::unique_ptr<MachineSchedStrategy> SchedImpl;
+
+ /// Topo - A topological ordering for SUnits which permits fast IsReachable
+ /// and similar queries.
+ ScheduleDAGTopologicalSort Topo;
+
+ /// Ordered list of DAG postprocessing steps.
+ std::vector<std::unique_ptr<ScheduleDAGMutation>> Mutations;
+
+ /// The top of the unscheduled zone.
+ MachineBasicBlock::iterator CurrentTop;
+
+ /// The bottom of the unscheduled zone.
+ MachineBasicBlock::iterator CurrentBottom;
+
+ /// Record the next node in a scheduled cluster.
+ const SUnit *NextClusterPred;
+ const SUnit *NextClusterSucc;
+
+#ifndef NDEBUG
+ /// The number of instructions scheduled so far. Used to cut off the
+ /// scheduler at the point determined by misched-cutoff.
+ unsigned NumInstrsScheduled;
+#endif
+public:
+ ScheduleDAGMI(MachineSchedContext *C, std::unique_ptr<MachineSchedStrategy> S,
+ bool IsPostRA)
+ : ScheduleDAGInstrs(*C->MF, C->MLI, IsPostRA,
+ /*RemoveKillFlags=*/IsPostRA, C->LIS),
+ AA(C->AA), SchedImpl(std::move(S)), Topo(SUnits, &ExitSU), CurrentTop(),
+ CurrentBottom(), NextClusterPred(nullptr), NextClusterSucc(nullptr) {
+#ifndef NDEBUG
+ NumInstrsScheduled = 0;
+#endif
+ }
+
+ // Provide a vtable anchor
+ ~ScheduleDAGMI() override;
+
+ /// Return true if this DAG supports VReg liveness and RegPressure.
+ virtual bool hasVRegLiveness() const { return false; }
+
+ /// Add a postprocessing step to the DAG builder.
+ /// Mutations are applied in the order that they are added after normal DAG
+ /// building and before MachineSchedStrategy initialization.
+ ///
+ /// ScheduleDAGMI takes ownership of the Mutation object.
+ void addMutation(std::unique_ptr<ScheduleDAGMutation> Mutation) {
+ Mutations.push_back(std::move(Mutation));
+ }
+
+ /// \brief True if an edge can be added from PredSU to SuccSU without creating
+ /// a cycle.
+ bool canAddEdge(SUnit *SuccSU, SUnit *PredSU);
+
+ /// \brief Add a DAG edge to the given SU with the given predecessor
+ /// dependence data.
+ ///
+ /// \returns true if the edge may be added without creating a cycle OR if an
+ /// equivalent edge already existed (false indicates failure).
+ bool addEdge(SUnit *SuccSU, const SDep &PredDep);
+
+ MachineBasicBlock::iterator top() const { return CurrentTop; }
+ MachineBasicBlock::iterator bottom() const { return CurrentBottom; }
+
+ /// Implement the ScheduleDAGInstrs interface for handling the next scheduling
+ /// region. This covers all instructions in a block, while schedule() may only
+ /// cover a subset.
+ void enterRegion(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator begin,
+ MachineBasicBlock::iterator end,
+ unsigned regioninstrs) override;
+
+ /// Implement ScheduleDAGInstrs interface for scheduling a sequence of
+ /// reorderable instructions.
+ void schedule() override;
+
+ /// Change the position of an instruction within the basic block and update
+ /// live ranges and region boundary iterators.
+ void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
+
+ const SUnit *getNextClusterPred() const { return NextClusterPred; }
+
+ const SUnit *getNextClusterSucc() const { return NextClusterSucc; }
+
+ void viewGraph(const Twine &Name, const Twine &Title) override;
+ void viewGraph() override;
+
+protected:
+ // Top-Level entry points for the schedule() driver...
+
+ /// Apply each ScheduleDAGMutation step in order. This allows different
+ /// instances of ScheduleDAGMI to perform custom DAG postprocessing.
+ void postprocessDAG();
+
+ /// Release ExitSU predecessors and setup scheduler queues.
+ void initQueues(ArrayRef<SUnit*> TopRoots, ArrayRef<SUnit*> BotRoots);
+
+ /// Update scheduler DAG and queues after scheduling an instruction.
+ void updateQueues(SUnit *SU, bool IsTopNode);
+
+ /// Reinsert debug_values recorded in ScheduleDAGInstrs::DbgValues.
+ void placeDebugValues();
+
+ /// \brief dump the scheduled Sequence.
+ void dumpSchedule() const;
+
+ // Lesser helpers...
+ bool checkSchedLimit();
+
+ void findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots,
+ SmallVectorImpl<SUnit*> &BotRoots);
+
+ void releaseSucc(SUnit *SU, SDep *SuccEdge);
+ void releaseSuccessors(SUnit *SU);
+ void releasePred(SUnit *SU, SDep *PredEdge);
+ void releasePredecessors(SUnit *SU);
+};
+
+/// ScheduleDAGMILive is an implementation of ScheduleDAGInstrs that schedules
+/// machine instructions while updating LiveIntervals and tracking regpressure.
+class ScheduleDAGMILive : public ScheduleDAGMI {
+protected:
+ RegisterClassInfo *RegClassInfo;
+
+ /// Information about DAG subtrees. If DFSResult is NULL, then SchedulerTrees
+ /// will be empty.
+ SchedDFSResult *DFSResult;
+ BitVector ScheduledTrees;
+
+ MachineBasicBlock::iterator LiveRegionEnd;
+
+ // Map each SU to its summary of pressure changes. This array is updated for
+ // liveness during bottom-up scheduling. Top-down scheduling may proceed but
+ // has no affect on the pressure diffs.
+ PressureDiffs SUPressureDiffs;
+
+ /// Register pressure in this region computed by initRegPressure.
+ bool ShouldTrackPressure;
+ IntervalPressure RegPressure;
+ RegPressureTracker RPTracker;
+
+ /// List of pressure sets that exceed the target's pressure limit before
+ /// scheduling, listed in increasing set ID order. Each pressure set is paired
+ /// with its max pressure in the currently scheduled regions.
+ std::vector<PressureChange> RegionCriticalPSets;
+
+ /// The top of the unscheduled zone.
+ IntervalPressure TopPressure;
+ RegPressureTracker TopRPTracker;
+
+ /// The bottom of the unscheduled zone.
+ IntervalPressure BotPressure;
+ RegPressureTracker BotRPTracker;
+
+public:
+ ScheduleDAGMILive(MachineSchedContext *C,
+ std::unique_ptr<MachineSchedStrategy> S)
+ : ScheduleDAGMI(C, std::move(S), /*IsPostRA=*/false),
+ RegClassInfo(C->RegClassInfo), DFSResult(nullptr),
+ ShouldTrackPressure(false), RPTracker(RegPressure),
+ TopRPTracker(TopPressure), BotRPTracker(BotPressure) {}
+
+ virtual ~ScheduleDAGMILive();
+
+ /// Return true if this DAG supports VReg liveness and RegPressure.
+ bool hasVRegLiveness() const override { return true; }
+
+ /// \brief Return true if register pressure tracking is enabled.
+ bool isTrackingPressure() const { return ShouldTrackPressure; }
+
+ /// Get current register pressure for the top scheduled instructions.
+ const IntervalPressure &getTopPressure() const { return TopPressure; }
+ const RegPressureTracker &getTopRPTracker() const { return TopRPTracker; }
+
+ /// Get current register pressure for the bottom scheduled instructions.
+ const IntervalPressure &getBotPressure() const { return BotPressure; }
+ const RegPressureTracker &getBotRPTracker() const { return BotRPTracker; }
+
+ /// Get register pressure for the entire scheduling region before scheduling.
+ const IntervalPressure &getRegPressure() const { return RegPressure; }
+
+ const std::vector<PressureChange> &getRegionCriticalPSets() const {
+ return RegionCriticalPSets;
+ }
+
+ PressureDiff &getPressureDiff(const SUnit *SU) {
+ return SUPressureDiffs[SU->NodeNum];
+ }
+
+ /// Compute a DFSResult after DAG building is complete, and before any
+ /// queue comparisons.
+ void computeDFSResult();
+
+ /// Return a non-null DFS result if the scheduling strategy initialized it.
+ const SchedDFSResult *getDFSResult() const { return DFSResult; }
+
+ BitVector &getScheduledTrees() { return ScheduledTrees; }
+
+ /// Implement the ScheduleDAGInstrs interface for handling the next scheduling
+ /// region. This covers all instructions in a block, while schedule() may only
+ /// cover a subset.
+ void enterRegion(MachineBasicBlock *bb,
+ MachineBasicBlock::iterator begin,
+ MachineBasicBlock::iterator end,
+ unsigned regioninstrs) override;
+
+ /// Implement ScheduleDAGInstrs interface for scheduling a sequence of
+ /// reorderable instructions.
+ void schedule() override;
+
+ /// Compute the cyclic critical path through the DAG.
+ unsigned computeCyclicCriticalPath();
+
+protected:
+ // Top-Level entry points for the schedule() driver...
+
+ /// Call ScheduleDAGInstrs::buildSchedGraph with register pressure tracking
+ /// enabled. This sets up three trackers. RPTracker will cover the entire DAG
+ /// region, TopTracker and BottomTracker will be initialized to the top and
+ /// bottom of the DAG region without covereing any unscheduled instruction.
+ void buildDAGWithRegPressure();
+
+ /// Move an instruction and update register pressure.
+ void scheduleMI(SUnit *SU, bool IsTopNode);
+
+ // Lesser helpers...
+
+ void initRegPressure();
+
+ void updatePressureDiffs(ArrayRef<unsigned> LiveUses);
+
+ void updateScheduledPressure(const SUnit *SU,
+ const std::vector<unsigned> &NewMaxPressure);
+};
+
+//===----------------------------------------------------------------------===//
+///
+/// Helpers for implementing custom MachineSchedStrategy classes. These take
+/// care of the book-keeping associated with list scheduling heuristics.
+///
+//===----------------------------------------------------------------------===//
+
/// ReadyQueue encapsulates vector of "ready" SUnits with basic convenience
/// methods for pushing and removing nodes. ReadyQueue's are uniquely identified
/// by an ID. SUnit::NodeQueueId is a mask of the ReadyQueues the SUnit is in.
bool empty() const { return Queue.empty(); }
+ void clear() { Queue.clear(); }
+
unsigned size() const { return Queue.size(); }
typedef std::vector<SUnit*>::iterator iterator;
iterator end() { return Queue.end(); }
+ ArrayRef<SUnit*> elements() { return Queue; }
+
iterator find(SUnit *SU) {
return std::find(Queue.begin(), Queue.end(), SU);
}
SU->NodeQueueId |= ID;
}
- void remove(iterator I) {
+ iterator remove(iterator I) {
(*I)->NodeQueueId &= ~ID;
*I = Queue.back();
+ unsigned idx = I - Queue.begin();
Queue.pop_back();
+ return Queue.begin() + idx;
}
-#ifndef NDEBUG
void dump();
-#endif
};
-/// Mutate the DAG as a postpass after normal DAG building.
-class ScheduleDAGMutation {
-public:
- virtual ~ScheduleDAGMutation() {}
+/// Summarize the unscheduled region.
+struct SchedRemainder {
+ // Critical path through the DAG in expected latency.
+ unsigned CriticalPath;
+ unsigned CyclicCritPath;
- virtual void apply(ScheduleDAGMI *DAG) = 0;
+ // Scaled count of micro-ops left to schedule.
+ unsigned RemIssueCount;
+
+ bool IsAcyclicLatencyLimited;
+
+ // Unscheduled resources
+ SmallVector<unsigned, 16> RemainingCounts;
+
+ void reset() {
+ CriticalPath = 0;
+ CyclicCritPath = 0;
+ RemIssueCount = 0;
+ IsAcyclicLatencyLimited = false;
+ RemainingCounts.clear();
+ }
+
+ SchedRemainder() { reset(); }
+
+ void init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel);
};
-/// ScheduleDAGMI is an implementation of ScheduleDAGInstrs that schedules
-/// machine instructions while updating LiveIntervals and tracking regpressure.
-class ScheduleDAGMI : public ScheduleDAGInstrs {
-protected:
- AliasAnalysis *AA;
- RegisterClassInfo *RegClassInfo;
- MachineSchedStrategy *SchedImpl;
+/// Each Scheduling boundary is associated with ready queues. It tracks the
+/// current cycle in the direction of movement, and maintains the state
+/// of "hazards" and other interlocks at the current cycle.
+class SchedBoundary {
+public:
+ /// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both)
+ enum {
+ TopQID = 1,
+ BotQID = 2,
+ LogMaxQID = 2
+ };
- /// Ordered list of DAG postprocessing steps.
- std::vector<ScheduleDAGMutation*> Mutations;
+ ScheduleDAGMI *DAG;
+ const TargetSchedModel *SchedModel;
+ SchedRemainder *Rem;
- MachineBasicBlock::iterator LiveRegionEnd;
+ ReadyQueue Available;
+ ReadyQueue Pending;
- /// Register pressure in this region computed by buildSchedGraph.
- IntervalPressure RegPressure;
- RegPressureTracker RPTracker;
+ ScheduleHazardRecognizer *HazardRec;
- /// List of pressure sets that exceed the target's pressure limit before
- /// scheduling, listed in increasing set ID order. Each pressure set is paired
- /// with its max pressure in the currently scheduled regions.
- std::vector<PressureElement> RegionCriticalPSets;
+private:
+ /// True if the pending Q should be checked/updated before scheduling another
+ /// instruction.
+ bool CheckPending;
- /// The top of the unscheduled zone.
- MachineBasicBlock::iterator CurrentTop;
- IntervalPressure TopPressure;
- RegPressureTracker TopRPTracker;
+ // For heuristics, keep a list of the nodes that immediately depend on the
+ // most recently scheduled node.
+ SmallPtrSet<const SUnit*, 8> NextSUs;
- /// The bottom of the unscheduled zone.
- MachineBasicBlock::iterator CurrentBottom;
- IntervalPressure BotPressure;
- RegPressureTracker BotRPTracker;
+ /// Number of cycles it takes to issue the instructions scheduled in this
+ /// zone. It is defined as: scheduled-micro-ops / issue-width + stalls.
+ /// See getStalls().
+ unsigned CurrCycle;
+
+ /// Micro-ops issued in the current cycle
+ unsigned CurrMOps;
+
+ /// MinReadyCycle - Cycle of the soonest available instruction.
+ unsigned MinReadyCycle;
+
+ // The expected latency of the critical path in this scheduled zone.
+ unsigned ExpectedLatency;
+
+ // 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 ZoneCritResIdx;
+
+ // Is the scheduled region resource limited vs. latency limited.
+ bool IsResourceLimited;
+
+ // Record the highest cycle at which each resource has been reserved by a
+ // scheduled instruction.
+ SmallVector<unsigned, 16> ReservedCycles;
#ifndef NDEBUG
- /// The number of instructions scheduled so far. Used to cut off the
- /// scheduler at the point determined by misched-cutoff.
- unsigned NumInstrsScheduled;
+ // Remember the greatest possible stall as an upper bound on the number of
+ // times we should retry the pending queue because of a hazard.
+ unsigned MaxObservedStall;
#endif
public:
- ScheduleDAGMI(MachineSchedContext *C, MachineSchedStrategy *S):
- ScheduleDAGInstrs(*C->MF, *C->MLI, *C->MDT, /*IsPostRA=*/false, C->LIS),
- AA(C->AA), RegClassInfo(C->RegClassInfo), SchedImpl(S),
- RPTracker(RegPressure), CurrentTop(), TopRPTracker(TopPressure),
- CurrentBottom(), BotRPTracker(BotPressure) {
-#ifndef NDEBUG
- NumInstrsScheduled = 0;
-#endif
+ /// Pending queues extend the ready queues with the same ID and the
+ /// PendingFlag set.
+ SchedBoundary(unsigned ID, const Twine &Name):
+ DAG(nullptr), SchedModel(nullptr), Rem(nullptr), Available(ID, Name+".A"),
+ Pending(ID << LogMaxQID, Name+".P"),
+ HazardRec(nullptr) {
+ reset();
}
- virtual ~ScheduleDAGMI() {
- delete SchedImpl;
+ ~SchedBoundary();
+
+ void reset();
+
+ void init(ScheduleDAGMI *dag, const TargetSchedModel *smodel,
+ SchedRemainder *rem);
+
+ bool isTop() const {
+ return Available.getID() == TopQID;
}
- /// Add a postprocessing step to the DAG builder.
- /// Mutations are applied in the order that they are added after normal DAG
- /// building and before MachineSchedStrategy initialization.
- void addMutation(ScheduleDAGMutation *Mutation) {
- Mutations.push_back(Mutation);
+ /// Number of cycles to issue the instructions scheduled in this zone.
+ unsigned getCurrCycle() const { return CurrCycle; }
+
+ /// Micro-ops issued in the current cycle
+ unsigned getCurrMOps() const { return CurrMOps; }
+
+ /// Return true if the given SU is used by the most recently scheduled
+ /// instruction.
+ bool isNextSU(const SUnit *SU) const { return NextSUs.count(SU); }
+
+ // The latency of dependence chains leading into this zone.
+ unsigned getDependentLatency() const { return DependentLatency; }
+
+ /// 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);
}
- MachineBasicBlock::iterator top() const { return CurrentTop; }
- MachineBasicBlock::iterator bottom() const { return CurrentBottom; }
+ unsigned getUnscheduledLatency(SUnit *SU) const {
+ return isTop() ? SU->getHeight() : SU->getDepth();
+ }
- /// Implement the ScheduleDAGInstrs interface for handling the next scheduling
- /// region. This covers all instructions in a block, while schedule() may only
- /// cover a subset.
- void enterRegion(MachineBasicBlock *bb,
- MachineBasicBlock::iterator begin,
- MachineBasicBlock::iterator end,
- unsigned endcount);
+ unsigned getResourceCount(unsigned ResIdx) const {
+ return ExecutedResCounts[ResIdx];
+ }
+ /// Get the scaled count of scheduled micro-ops and resources, including
+ /// executed resources.
+ unsigned getCriticalCount() const {
+ if (!ZoneCritResIdx)
+ return RetiredMOps * SchedModel->getMicroOpFactor();
+ return getResourceCount(ZoneCritResIdx);
+ }
- /// Implement ScheduleDAGInstrs interface for scheduling a sequence of
- /// reorderable instructions.
- virtual void schedule();
+ /// 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);
+ }
- /// Get current register pressure for the top scheduled instructions.
- const IntervalPressure &getTopPressure() const { return TopPressure; }
- const RegPressureTracker &getTopRPTracker() const { return TopRPTracker; }
+ unsigned getZoneCritResIdx() const { return ZoneCritResIdx; }
- /// Get current register pressure for the bottom scheduled instructions.
- const IntervalPressure &getBotPressure() const { return BotPressure; }
- const RegPressureTracker &getBotRPTracker() const { return BotRPTracker; }
+ // Is the scheduled region resource limited vs. latency limited.
+ bool isResourceLimited() const { return IsResourceLimited; }
- /// Get register pressure for the entire scheduling region before scheduling.
- const IntervalPressure &getRegPressure() const { return RegPressure; }
+ /// Get the difference between the given SUnit's ready time and the current
+ /// cycle.
+ unsigned getLatencyStallCycles(SUnit *SU);
- const std::vector<PressureElement> &getRegionCriticalPSets() const {
- return RegionCriticalPSets;
+ unsigned getNextResourceCycle(unsigned PIdx, unsigned Cycles);
+
+ bool checkHazard(SUnit *SU);
+
+ unsigned findMaxLatency(ArrayRef<SUnit*> ReadySUs);
+
+ unsigned getOtherResourceCount(unsigned &OtherCritIdx);
+
+ void releaseNode(SUnit *SU, unsigned ReadyCycle);
+
+ void releaseTopNode(SUnit *SU);
+
+ void releaseBottomNode(SUnit *SU);
+
+ void bumpCycle(unsigned NextCycle);
+
+ void incExecutedResources(unsigned PIdx, unsigned Count);
+
+ unsigned countResource(unsigned PIdx, unsigned Cycles, unsigned ReadyCycle);
+
+ void bumpNode(SUnit *SU);
+
+ void releasePending();
+
+ void removeReady(SUnit *SU);
+
+ /// Call this before applying any other heuristics to the Available queue.
+ /// Updates the Available/Pending Q's if necessary and returns the single
+ /// available instruction, or NULL if there are multiple candidates.
+ SUnit *pickOnlyChoice();
+
+#ifndef NDEBUG
+ void dumpScheduledState();
+#endif
+};
+
+/// Base class for GenericScheduler. This class maintains information about
+/// scheduling candidates based on TargetSchedModel making it easy to implement
+/// heuristics for either preRA or postRA scheduling.
+class GenericSchedulerBase : 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, RegExcess, RegCritical, Stall, Cluster, Weak, RegMax,
+ ResourceReduce, ResourceDemand, BotHeightReduce, BotPathReduce,
+ TopDepthReduce, TopPathReduce, NextDefUse, NodeOrder};
+
+#ifndef NDEBUG
+ static const char *getReasonStr(GenericSchedulerBase::CandReason Reason);
+#endif
+
+ /// Policy for scheduling the next instruction in the candidate's zone.
+ struct CandPolicy {
+ bool ReduceLatency;
+ unsigned ReduceResIdx;
+ unsigned DemandResIdx;
+
+ CandPolicy(): ReduceLatency(false), ReduceResIdx(0), DemandResIdx(0) {}
+ };
+
+ /// Status of an instruction's critical resource consumption.
+ struct SchedResourceDelta {
+ // Count critical resources in the scheduled region required by SU.
+ unsigned CritResources;
+
+ // Count critical resources from another region consumed by SU.
+ unsigned DemandedResources;
+
+ SchedResourceDelta(): CritResources(0), DemandedResources(0) {}
+
+ bool operator==(const SchedResourceDelta &RHS) const {
+ return CritResources == RHS.CritResources
+ && DemandedResources == RHS.DemandedResources;
+ }
+ bool operator!=(const SchedResourceDelta &RHS) const {
+ return !operator==(RHS);
+ }
+ };
+
+ /// Store the state used by GenericScheduler heuristics, required for the
+ /// lifetime of one invocation of pickNode().
+ struct SchedCandidate {
+ CandPolicy Policy;
+
+ // The best SUnit candidate.
+ SUnit *SU;
+
+ // 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;
+
+ // Critical resource consumption of the best candidate.
+ SchedResourceDelta ResDelta;
+
+ SchedCandidate(const CandPolicy &policy)
+ : Policy(policy), SU(nullptr), Reason(NoCand), RepeatReasonSet(0) {}
+
+ bool isValid() const { return SU; }
+
+ // Copy the status of another candidate without changing policy.
+ void setBest(SchedCandidate &Best) {
+ assert(Best.Reason != NoCand && "uninitialized Sched candidate");
+ SU = Best.SU;
+ Reason = Best.Reason;
+ RPDelta = Best.RPDelta;
+ 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);
+ };
+
+protected:
+ const MachineSchedContext *Context;
+ const TargetSchedModel *SchedModel;
+ const TargetRegisterInfo *TRI;
+
+ SchedRemainder Rem;
+protected:
+ GenericSchedulerBase(const MachineSchedContext *C):
+ Context(C), SchedModel(nullptr), TRI(nullptr) {}
+
+ void setPolicy(CandPolicy &Policy, bool IsPostRA, SchedBoundary &CurrZone,
+ SchedBoundary *OtherZone);
+
+#ifndef NDEBUG
+ void traceCandidate(const SchedCandidate &Cand);
+#endif
+};
+
+/// GenericScheduler shrinks the unscheduled zone using heuristics to balance
+/// the schedule.
+class GenericScheduler : public GenericSchedulerBase {
+ ScheduleDAGMILive *DAG;
+
+ // State of the top and bottom scheduled instruction boundaries.
+ SchedBoundary Top;
+ SchedBoundary Bot;
+
+ MachineSchedPolicy RegionPolicy;
+public:
+ GenericScheduler(const MachineSchedContext *C):
+ GenericSchedulerBase(C), DAG(nullptr), Top(SchedBoundary::TopQID, "TopQ"),
+ Bot(SchedBoundary::BotQID, "BotQ") {}
+
+ void initPolicy(MachineBasicBlock::iterator Begin,
+ MachineBasicBlock::iterator End,
+ unsigned NumRegionInstrs) override;
+
+ bool shouldTrackPressure() const override {
+ return RegionPolicy.ShouldTrackPressure;
+ }
+
+ void initialize(ScheduleDAGMI *dag) override;
+
+ SUnit *pickNode(bool &IsTopNode) override;
+
+ void schedNode(SUnit *SU, bool IsTopNode) override;
+
+ void releaseTopNode(SUnit *SU) override {
+ Top.releaseTopNode(SU);
+ }
+
+ void releaseBottomNode(SUnit *SU) override {
+ Bot.releaseBottomNode(SU);
}
+ void registerRoots() override;
+
protected:
- // Top-Level entry points for the schedule() driver...
+ void checkAcyclicLatency();
- /// Call ScheduleDAGInstrs::buildSchedGraph with register pressure tracking
- /// enabled. This sets up three trackers. RPTracker will cover the entire DAG
- /// region, TopTracker and BottomTracker will be initialized to the top and
- /// bottom of the DAG region without covereing any unscheduled instruction.
- void buildDAGWithRegPressure();
+ void tryCandidate(SchedCandidate &Cand,
+ SchedCandidate &TryCand,
+ SchedBoundary &Zone,
+ const RegPressureTracker &RPTracker,
+ RegPressureTracker &TempTracker);
- /// Apply each ScheduleDAGMutation step in order. This allows different
- /// instances of ScheduleDAGMI to perform custom DAG postprocessing.
- void postprocessDAG();
+ SUnit *pickNodeBidirectional(bool &IsTopNode);
- /// Identify DAG roots and setup scheduler queues.
- void initQueues();
+ void pickNodeFromQueue(SchedBoundary &Zone,
+ const RegPressureTracker &RPTracker,
+ SchedCandidate &Candidate);
- /// Move an instruction and update register pressure.
- void scheduleMI(SUnit *SU, bool IsTopNode);
+ void reschedulePhysRegCopies(SUnit *SU, bool isTop);
+};
- /// Update scheduler DAG and queues after scheduling an instruction.
- void updateQueues(SUnit *SU, bool IsTopNode);
+/// PostGenericScheduler - Interface to the scheduling algorithm used by
+/// ScheduleDAGMI.
+///
+/// Callbacks from ScheduleDAGMI:
+/// initPolicy -> initialize(DAG) -> registerRoots -> pickNode ...
+class PostGenericScheduler : public GenericSchedulerBase {
+ ScheduleDAGMI *DAG;
+ SchedBoundary Top;
+ SmallVector<SUnit*, 8> BotRoots;
+public:
+ PostGenericScheduler(const MachineSchedContext *C):
+ GenericSchedulerBase(C), Top(SchedBoundary::TopQID, "TopQ") {}
- /// Reinsert debug_values recorded in ScheduleDAGInstrs::DbgValues.
- void placeDebugValues();
+ virtual ~PostGenericScheduler() {}
- // Lesser helpers...
+ void initPolicy(MachineBasicBlock::iterator Begin,
+ MachineBasicBlock::iterator End,
+ unsigned NumRegionInstrs) override {
+ /* no configurable policy */
+ };
- void initRegPressure();
+ /// PostRA scheduling does not track pressure.
+ bool shouldTrackPressure() const override { return false; }
- void updateScheduledPressure(std::vector<unsigned> NewMaxPressure);
+ void initialize(ScheduleDAGMI *Dag) override;
- void moveInstruction(MachineInstr *MI, MachineBasicBlock::iterator InsertPos);
- bool checkSchedLimit();
+ void registerRoots() override;
- void releaseRoots();
+ SUnit *pickNode(bool &IsTopNode) override;
- void releaseSucc(SUnit *SU, SDep *SuccEdge);
- void releaseSuccessors(SUnit *SU);
- void releasePred(SUnit *SU, SDep *PredEdge);
- void releasePredecessors(SUnit *SU);
+ void scheduleTree(unsigned SubtreeID) override {
+ llvm_unreachable("PostRA scheduler does not support subtree analysis.");
+ }
+
+ void schedNode(SUnit *SU, bool IsTopNode) override;
+
+ void releaseTopNode(SUnit *SU) override {
+ Top.releaseTopNode(SU);
+ }
+
+ // Only called for roots.
+ void releaseBottomNode(SUnit *SU) override {
+ BotRoots.push_back(SU);
+ }
+
+protected:
+ void tryCandidate(SchedCandidate &Cand, SchedCandidate &TryCand);
+
+ void pickNodeFromQueue(SchedCandidate &Cand);
};
} // namespace llvm
projects / oota-llvm.git / blobdiff