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thirdparty/capstone/suite/synctools/tablegen/include/llvm/CodeGen/VLIWMachineScheduler.h

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+//===- VLIWMachineScheduler.h - VLIW-Focused Scheduling Pass ----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//                                                                            //
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_VLIWMACHINESCHEDULER_H
+#define LLVM_CODEGEN_VLIWMACHINESCHEDULER_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/CodeGen/MachineScheduler.h"
+#include "llvm/CodeGen/TargetSchedule.h"
+#include <limits>
+#include <memory>
+#include <utility>
+
+namespace llvm {
+
+class DFAPacketizer;
+class RegisterClassInfo;
+class ScheduleHazardRecognizer;
+class SUnit;
+class TargetInstrInfo;
+class TargetSubtargetInfo;
+
+class VLIWResourceModel {
+protected:
+  const TargetInstrInfo *TII;
+
+  /// ResourcesModel - Represents VLIW state.
+  /// Not limited to VLIW targets per se, but assumes definition of resource
+  /// model by a target.
+  DFAPacketizer *ResourcesModel;
+
+  const TargetSchedModel *SchedModel;
+
+  /// Local packet/bundle model. Purely
+  /// internal to the MI scheduler at the time.
+  SmallVector<SUnit *> Packet;
+
+  /// Total packets created.
+  unsigned TotalPackets = 0;
+
+public:
+  VLIWResourceModel(const TargetSubtargetInfo &STI, const TargetSchedModel *SM);
+
+  virtual ~VLIWResourceModel();
+
+  virtual void reset();
+
+  virtual bool hasDependence(const SUnit *SUd, const SUnit *SUu);
+  virtual bool isResourceAvailable(SUnit *SU, bool IsTop);
+  virtual bool reserveResources(SUnit *SU, bool IsTop);
+  unsigned getTotalPackets() const { return TotalPackets; }
+  size_t getPacketInstCount() const { return Packet.size(); }
+  bool isInPacket(SUnit *SU) const { return is_contained(Packet, SU); }
+
+protected:
+  virtual DFAPacketizer *createPacketizer(const TargetSubtargetInfo &STI) const;
+};
+
+/// Extend the standard ScheduleDAGMILive to provide more context and override
+/// the top-level schedule() driver.
+class VLIWMachineScheduler : public ScheduleDAGMILive {
+public:
+  VLIWMachineScheduler(MachineSchedContext *C,
+                       std::unique_ptr<MachineSchedStrategy> S)
+      : ScheduleDAGMILive(C, std::move(S)) {}
+
+  /// Schedule - This is called back from ScheduleDAGInstrs::Run() when it's
+  /// time to do some work.
+  void schedule() override;
+
+  RegisterClassInfo *getRegClassInfo() { return RegClassInfo; }
+  int getBBSize() { return BB->size(); }
+};
+
+//===----------------------------------------------------------------------===//
+// ConvergingVLIWScheduler - Implementation of a VLIW-aware
+// MachineSchedStrategy.
+//===----------------------------------------------------------------------===//
+
+class ConvergingVLIWScheduler : public MachineSchedStrategy {
+protected:
+  /// Store the state used by ConvergingVLIWScheduler heuristics, required
+  ///  for the lifetime of one invocation of pickNode().
+  struct SchedCandidate {
+    // The best SUnit candidate.
+    SUnit *SU = nullptr;
+
+    // Register pressure values for the best candidate.
+    RegPressureDelta RPDelta;
+
+    // Best scheduling cost.
+    int SCost = 0;
+
+    SchedCandidate() = default;
+  };
+  /// Represent the type of SchedCandidate found within a single queue.
+  enum CandResult {
+    NoCand,
+    NodeOrder,
+    SingleExcess,
+    SingleCritical,
+    SingleMax,
+    MultiPressure,
+    BestCost,
+    Weak
+  };
+
+  // Constants used to denote relative importance of
+  // heuristic components for cost computation.
+  static constexpr unsigned PriorityOne = 200;
+  static constexpr unsigned PriorityTwo = 50;
+  static constexpr unsigned PriorityThree = 75;
+  static constexpr unsigned ScaleTwo = 10;
+
+  /// Each Scheduling boundary is associated with ready queues. It tracks the
+  /// current cycle in whichever direction at has moved, and maintains the state
+  /// of "hazards" and other interlocks at the current cycle.
+  struct VLIWSchedBoundary {
+    VLIWMachineScheduler *DAG = nullptr;
+    const TargetSchedModel *SchedModel = nullptr;
+
+    ReadyQueue Available;
+    ReadyQueue Pending;
+    bool CheckPending = false;
+
+    ScheduleHazardRecognizer *HazardRec = nullptr;
+    VLIWResourceModel *ResourceModel = nullptr;
+
+    unsigned CurrCycle = 0;
+    unsigned IssueCount = 0;
+    unsigned CriticalPathLength = 0;
+
+    /// MinReadyCycle - Cycle of the soonest available instruction.
+    unsigned MinReadyCycle = std::numeric_limits<unsigned>::max();
+
+    // Remember the greatest min operand latency.
+    unsigned MaxMinLatency = 0;
+
+    /// Pending queues extend the ready queues with the same ID and the
+    /// PendingFlag set.
+    VLIWSchedBoundary(unsigned ID, const Twine &Name)
+        : Available(ID, Name + ".A"),
+          Pending(ID << ConvergingVLIWScheduler::LogMaxQID, Name + ".P") {}
+
+    ~VLIWSchedBoundary();
+
+    void init(VLIWMachineScheduler *dag, const TargetSchedModel *smodel) {
+      DAG = dag;
+      SchedModel = smodel;
+      CurrCycle = 0;
+      IssueCount = 0;
+      // Initialize the critical path length limit, which used by the scheduling
+      // cost model to determine the value for scheduling an instruction. We use
+      // a slightly different heuristic for small and large functions. For small
+      // functions, it's important to use the height/depth of the instruction.
+      // For large functions, prioritizing by height or depth increases spills.
+      CriticalPathLength = DAG->getBBSize() / SchedModel->getIssueWidth();
+      if (DAG->getBBSize() < 50)
+        // We divide by two as a cheap and simple heuristic to reduce the
+        // critical path length, which increases the priority of using the graph
+        // height/depth in the scheduler's cost computation.
+        CriticalPathLength >>= 1;
+      else {
+        // For large basic blocks, we prefer a larger critical path length to
+        // decrease the priority of using the graph height/depth.
+        unsigned MaxPath = 0;
+        for (auto &SU : DAG->SUnits)
+          MaxPath = std::max(MaxPath, isTop() ? SU.getHeight() : SU.getDepth());
+        CriticalPathLength = std::max(CriticalPathLength, MaxPath) + 1;
+      }
+    }
+
+    bool isTop() const {
+      return Available.getID() == ConvergingVLIWScheduler::TopQID;
+    }
+
+    bool checkHazard(SUnit *SU);
+
+    void releaseNode(SUnit *SU, unsigned ReadyCycle);
+
+    void bumpCycle();
+
+    void bumpNode(SUnit *SU);
+
+    void releasePending();
+
+    void removeReady(SUnit *SU);
+
+    SUnit *pickOnlyChoice();
+
+    bool isLatencyBound(SUnit *SU) {
+      if (CurrCycle >= CriticalPathLength)
+        return true;
+      unsigned PathLength = isTop() ? SU->getHeight() : SU->getDepth();
+      return CriticalPathLength - CurrCycle <= PathLength;
+    }
+  };
+
+  VLIWMachineScheduler *DAG = nullptr;
+  const TargetSchedModel *SchedModel = nullptr;
+
+  // State of the top and bottom scheduled instruction boundaries.
+  VLIWSchedBoundary Top;
+  VLIWSchedBoundary Bot;
+
+  /// List of pressure sets that have a high pressure level in the region.
+  SmallVector<bool> HighPressureSets;
+
+public:
+  /// SUnit::NodeQueueId: 0 (none), 1 (top), 2 (bot), 3 (both)
+  enum { TopQID = 1, BotQID = 2, LogMaxQID = 2 };
+
+  ConvergingVLIWScheduler() : Top(TopQID, "TopQ"), Bot(BotQID, "BotQ") {}
+  virtual ~ConvergingVLIWScheduler() = default;
+
+  void initialize(ScheduleDAGMI *dag) override;
+
+  SUnit *pickNode(bool &IsTopNode) override;
+
+  void schedNode(SUnit *SU, bool IsTopNode) override;
+
+  void releaseTopNode(SUnit *SU) override;
+
+  void releaseBottomNode(SUnit *SU) override;
+
+  unsigned reportPackets() {
+    return Top.ResourceModel->getTotalPackets() +
+           Bot.ResourceModel->getTotalPackets();
+  }
+
+protected:
+  virtual VLIWResourceModel *
+  createVLIWResourceModel(const TargetSubtargetInfo &STI,
+                          const TargetSchedModel *SchedModel) const;
+
+  SUnit *pickNodeBidrectional(bool &IsTopNode);
+
+  int pressureChange(const SUnit *SU, bool isBotUp);
+
+  virtual int SchedulingCost(ReadyQueue &Q, SUnit *SU,
+                             SchedCandidate &Candidate, RegPressureDelta &Delta,
+                             bool verbose);
+
+  CandResult pickNodeFromQueue(VLIWSchedBoundary &Zone,
+                               const RegPressureTracker &RPTracker,
+                               SchedCandidate &Candidate);
+#ifndef NDEBUG
+  void traceCandidate(const char *Label, const ReadyQueue &Q, SUnit *SU,
+                      int Cost, PressureChange P = PressureChange());
+
+  void readyQueueVerboseDump(const RegPressureTracker &RPTracker,
+                             SchedCandidate &Candidate, ReadyQueue &Q);
+#endif
+};
+
+ScheduleDAGMILive *createVLIWSched(MachineSchedContext *C);
+
+} // end namespace llvm
+
+#endif // LLVM_CODEGEN_VLIWMACHINESCHEDULER_H