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 | //===-- GCNSchedStrategy.h - GCN Scheduler Strategy -*- 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
//
//===----------------------------------------------------------------------===//
//
/// \file
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_LIB_TARGET_AMDGPU_GCNSCHEDSTRATEGY_H
#define LLVM_LIB_TARGET_AMDGPU_GCNSCHEDSTRATEGY_H
#include "GCNRegPressure.h"
#include "llvm/CodeGen/MachineScheduler.h"
namespace llvm {
class SIMachineFunctionInfo;
class SIRegisterInfo;
class GCNSubtarget;
/// This is a minimal scheduler strategy.  The main difference between this
/// and the GenericScheduler is that GCNSchedStrategy uses different
/// heuristics to determine excess/critical pressure sets.  Its goal is to
/// maximize kernel occupancy (i.e. maximum number of waves per simd).
class GCNMaxOccupancySchedStrategy : public GenericScheduler {
  friend class GCNScheduleDAGMILive;
  SUnit *pickNodeBidirectional(bool &IsTopNode);
  void pickNodeFromQueue(SchedBoundary &Zone, const CandPolicy &ZonePolicy,
                         const RegPressureTracker &RPTracker,
                         SchedCandidate &Cand);
  void initCandidate(SchedCandidate &Cand, SUnit *SU,
                     bool AtTop, const RegPressureTracker &RPTracker,
                     const SIRegisterInfo *SRI,
                     unsigned SGPRPressure, unsigned VGPRPressure);
  unsigned SGPRExcessLimit;
  unsigned VGPRExcessLimit;
  unsigned SGPRCriticalLimit;
  unsigned VGPRCriticalLimit;
  unsigned TargetOccupancy;
  MachineFunction *MF;
public:
  GCNMaxOccupancySchedStrategy(const MachineSchedContext *C);
  SUnit *pickNode(bool &IsTopNode) override;
  void initialize(ScheduleDAGMI *DAG) override;
  void setTargetOccupancy(unsigned Occ) { TargetOccupancy = Occ; }
};
class GCNScheduleDAGMILive : public ScheduleDAGMILive {
  const GCNSubtarget &ST;
  SIMachineFunctionInfo &MFI;
  // Occupancy target at the beginning of function scheduling cycle.
  unsigned StartingOccupancy;
  // Minimal real occupancy recorder for the function.
  unsigned MinOccupancy;
  // Scheduling stage number.
  unsigned Stage;
  // Current region index.
  size_t RegionIdx;
  // Vecor of regions recorder for later rescheduling
  SmallVector<std::pair<MachineBasicBlock::iterator,
                        MachineBasicBlock::iterator>, 32> Regions;
  // Region live-in cache.
  SmallVector<GCNRPTracker::LiveRegSet, 32> LiveIns;
  // Region pressure cache.
  SmallVector<GCNRegPressure, 32> Pressure;
  // Temporary basic block live-in cache.
  DenseMap<const MachineBasicBlock*, GCNRPTracker::LiveRegSet> MBBLiveIns;
  // Return current region pressure.
  GCNRegPressure getRealRegPressure() const;
  // Compute and cache live-ins and pressure for all regions in block.
  void computeBlockPressure(const MachineBasicBlock *MBB);
public:
  GCNScheduleDAGMILive(MachineSchedContext *C,
                       std::unique_ptr<MachineSchedStrategy> S);
  void schedule() override;
  void finalizeSchedule() override;
};
} // End namespace llvm
#endif // GCNSCHEDSTRATEGY_H
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