llvm/llvm/lib/Target/SystemZ/SystemZHazardRecognizer.cpp

//=-- SystemZHazardRecognizer.h - SystemZ Hazard Recognizer -----*- 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
//
//===----------------------------------------------------------------------===//
//
// This file defines a hazard recognizer for the SystemZ scheduler.
//
// This class is used by the SystemZ scheduling strategy to maintain
// the state during scheduling, and provide cost functions for
// scheduling candidates. This includes:
//
// * Decoder grouping. A decoder group can maximally hold 3 uops, and
// instructions that always begin a new group should be scheduled when
// the current decoder group is empty.
// * Processor resources usage. It is beneficial to balance the use of
// resources.
//
// A goal is to consider all instructions, also those outside of any
// scheduling region. Such instructions are "advanced" past and include
// single instructions before a scheduling region, branches etc.
//
// A block that has only one predecessor continues scheduling with the state
// of it (which may be updated by emitting branches).
//
// ===---------------------------------------------------------------------===//

#include "SystemZHazardRecognizer.h"
#include "llvm/ADT/Statistic.h"

usingnamespacellvm;

#define DEBUG_TYPE …

// This is the limit of processor resource usage at which the
// scheduler should try to look for other instructions (not using the
// critical resource).
static cl::opt<int> ProcResCostLim("procres-cost-lim", cl::Hidden,
                                   cl::desc("The OOO window for processor "
                                            "resources during scheduling."),
                                   cl::init(8));

unsigned SystemZHazardRecognizer::
getNumDecoderSlots(SUnit *SU) const { … }

unsigned SystemZHazardRecognizer::getCurrCycleIdx(SUnit *SU) const { … }

ScheduleHazardRecognizer::HazardType SystemZHazardRecognizer::
getHazardType(SUnit *SU, int Stalls) { … }

void SystemZHazardRecognizer::Reset() { … }

bool
SystemZHazardRecognizer::fitsIntoCurrentGroup(SUnit *SU) const { … }

bool SystemZHazardRecognizer::has4RegOps(const MachineInstr *MI) const { … }

void SystemZHazardRecognizer::nextGroup() { … }

#ifndef NDEBUG // Debug output
void SystemZHazardRecognizer::dumpSU(SUnit *SU, raw_ostream &OS) const {
  OS << "SU(" << SU->NodeNum << "):";
  OS << TII->getName(SU->getInstr()->getOpcode());

  const MCSchedClassDesc *SC = getSchedClass(SU);
  if (!SC->isValid())
    return;

  for (TargetSchedModel::ProcResIter
         PI = SchedModel->getWriteProcResBegin(SC),
         PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
    const MCProcResourceDesc &PRD =
      *SchedModel->getProcResource(PI->ProcResourceIdx);
    std::string FU(PRD.Name);
    // trim e.g. Z13_FXaUnit -> FXa
    FU = FU.substr(FU.find('_') + 1);
    size_t Pos = FU.find("Unit");
    if (Pos != std::string::npos)
      FU.resize(Pos);
    if (FU == "LS") // LSUnit -> LSU
      FU = "LSU";
    OS << "/" << FU;

    if (PI->ReleaseAtCycle> 1)
      OS << "(" << PI->ReleaseAtCycle << "cyc)";
  }

  if (SC->NumMicroOps > 1)
    OS << "/" << SC->NumMicroOps << "uops";
  if (SC->BeginGroup && SC->EndGroup)
    OS << "/GroupsAlone";
  else if (SC->BeginGroup)
    OS << "/BeginsGroup";
  else if (SC->EndGroup)
    OS << "/EndsGroup";
  if (SU->isUnbuffered)
    OS << "/Unbuffered";
  if (has4RegOps(SU->getInstr()))
    OS << "/4RegOps";
}

void SystemZHazardRecognizer::dumpCurrGroup(std::string Msg) const {
  dbgs() << "++ " << Msg;
  dbgs() << ": ";

  if (CurGroupDbg.empty())
    dbgs() << " <empty>\n";
  else {
    dbgs() << "{ " << CurGroupDbg << " }";
    dbgs() << " (" << CurrGroupSize << " decoder slot"
           << (CurrGroupSize > 1 ? "s":"")
           << (CurrGroupHas4RegOps ? ", 4RegOps" : "")
           << ")\n";
  }
}

void SystemZHazardRecognizer::dumpProcResourceCounters() const {
  bool any = false;

  for (unsigned i = 0; i < SchedModel->getNumProcResourceKinds(); ++i)
    if (ProcResourceCounters[i] > 0) {
      any = true;
      break;
    }

  if (!any)
    return;

  dbgs() << "++ | Resource counters: ";
  for (unsigned i = 0; i < SchedModel->getNumProcResourceKinds(); ++i)
    if (ProcResourceCounters[i] > 0)
      dbgs() << SchedModel->getProcResource(i)->Name
             << ":" << ProcResourceCounters[i] << " ";
  dbgs() << "\n";

  if (CriticalResourceIdx != UINT_MAX)
    dbgs() << "++ | Critical resource: "
           << SchedModel->getProcResource(CriticalResourceIdx)->Name
           << "\n";
}

void SystemZHazardRecognizer::dumpState() const {
  dumpCurrGroup("| Current decoder group");
  dbgs() << "++ | Current cycle index: "
         << getCurrCycleIdx() << "\n";
  dumpProcResourceCounters();
  if (LastFPdOpCycleIdx != UINT_MAX)
    dbgs() << "++ | Last FPd cycle index: " << LastFPdOpCycleIdx << "\n";
}

#endif //NDEBUG

void SystemZHazardRecognizer::clearProcResCounters() { … }

static inline bool isBranchRetTrap(MachineInstr *MI) { … }

// Update state with SU as the next scheduled unit.
void SystemZHazardRecognizer::
EmitInstruction(SUnit *SU) { … }

int SystemZHazardRecognizer::groupingCost(SUnit *SU) const { … }

bool SystemZHazardRecognizer::isFPdOpPreferred_distance(SUnit *SU) const { … }

int SystemZHazardRecognizer::
resourcesCost(SUnit *SU) { … }

void SystemZHazardRecognizer::emitInstruction(MachineInstr *MI,
                                              bool TakenBranch) { … }

void SystemZHazardRecognizer::
copyState(SystemZHazardRecognizer *Incoming) { … }