llvm/llvm/lib/CodeGen/MacroFusion.cpp

//===- MacroFusion.cpp - Macro Fusion -------------------------------------===//
//
// 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 This file contains the implementation of the DAG scheduling mutation
/// to pair instructions back to back.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MacroFusion.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CodeGen/ScheduleDAGInstrs.h"
#include "llvm/CodeGen/ScheduleDAGMutation.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"

#define DEBUG_TYPE …

STATISTIC(NumFused, "Number of instr pairs fused");

usingnamespacellvm;

static cl::opt<bool> EnableMacroFusion("misched-fusion", cl::Hidden,
  cl::desc("Enable scheduling for macro fusion."), cl::init(true));

static bool isHazard(const SDep &Dep) { … }

static SUnit *getPredClusterSU(const SUnit &SU) { … }

bool llvm::hasLessThanNumFused(const SUnit &SU, unsigned FuseLimit) { … }

bool llvm::fuseInstructionPair(ScheduleDAGInstrs &DAG, SUnit &FirstSU,
                               SUnit &SecondSU) { … }

namespace {

/// Post-process the DAG to create cluster edges between instrs that may
/// be fused by the processor into a single operation.
class MacroFusion : public ScheduleDAGMutation { … };

} // end anonymous namespace

bool MacroFusion::shouldScheduleAdjacent(const TargetInstrInfo &TII,
                                         const TargetSubtargetInfo &STI,
                                         const MachineInstr *FirstMI,
                                         const MachineInstr &SecondMI) { … }

void MacroFusion::apply(ScheduleDAGInstrs *DAG) { … }

/// Implement the fusion of instr pairs in the scheduling DAG,
/// anchored at the instr in AnchorSU..
bool MacroFusion::scheduleAdjacentImpl(ScheduleDAGInstrs &DAG, SUnit &AnchorSU) { … }

std::unique_ptr<ScheduleDAGMutation>
llvm::createMacroFusionDAGMutation(ArrayRef<MacroFusionPredTy> Predicates,
                                   bool BranchOnly) { … }