//=== lib/CodeGen/GlobalISel/MipsPreLegalizerCombiner.cpp --------------===//

//

// 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 pass does combining of machine instructions at the generic MI level,

// before the legalizer.

//

//===----------------------------------------------------------------------===//

#include "MipsLegalizerInfo.h"

#include "MipsTargetMachine.h"

#include "llvm/CodeGen/GlobalISel/Combiner.h"

#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"

#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"

#include "llvm/CodeGen/GlobalISel/GISelKnownBits.h"

#include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"

#include "llvm/CodeGen/MachineFunctionPass.h"

#include "llvm/CodeGen/TargetPassConfig.h"

#include "llvm/InitializePasses.h"

#define DEBUG_TYPE "mips-prelegalizer-combiner"

using namespace llvm;

namespace {

struct MipsPreLegalizerCombinerInfo : public CombinerInfo {

public:

  MipsPreLegalizerCombinerInfo()

      : CombinerInfo(/*AllowIllegalOps*/ true, /*ShouldLegalizeIllegal*/ false,

                     /*LegalizerInfo*/ nullptr, /*EnableOpt*/ false,

                     /*EnableOptSize*/ false, /*EnableMinSize*/ false) {}

};

class MipsPreLegalizerCombinerImpl : public Combiner {

protected:

  const MipsSubtarget &STI;

  // TODO: Make CombinerHelper methods const.

  mutable CombinerHelper Helper;

public:

  MipsPreLegalizerCombinerImpl(MachineFunction &MF, CombinerInfo &CInfo,

                               const TargetPassConfig *TPC, GISelKnownBits &KB,

                               GISelCSEInfo *CSEInfo, const MipsSubtarget &STI,

                               MachineDominatorTree *MDT,

                               const LegalizerInfo *LI)

      : Combiner(MF, CInfo, TPC, &KB, CSEInfo), STI(STI),

        Helper(Observer, B, /*IsPreLegalize*/ true, &KB, MDT, LI) {}

  static const char *getName() { return "MipsPreLegalizerCombiner"; }

  void setupGeneratedPerFunctionState(MachineFunction &MF) override {

    // TODO: TableGen-erate this class' impl.

  }

  bool tryCombineAll(MachineInstr &MI) const override {

    switch (MI.getOpcode()) {

    default:

      return false;

    case TargetOpcode::G_MEMCPY_INLINE:

      return Helper.tryEmitMemcpyInline(MI);

    case TargetOpcode::G_LOAD:

    case TargetOpcode::G_SEXTLOAD:

    case TargetOpcode::G_ZEXTLOAD: {

      // Don't attempt to combine non power of 2 loads or unaligned loads when

      // subtarget doesn't support them.

      auto MMO = *MI.memoperands_begin();

      const MipsSubtarget &STI = MI.getMF()->getSubtarget<MipsSubtarget>();

      if (!isPowerOf2_64(MMO->getSize()))

        return false;

      bool isUnaligned = MMO->getAlign() < MMO->getSize();

      if (!STI.systemSupportsUnalignedAccess() && isUnaligned)

        return false;

      return Helper.tryCombineExtendingLoads(MI);

    }

    }

    return false;

  }

};

// Pass boilerplate

// ================

class MipsPreLegalizerCombiner : public MachineFunctionPass {

public:

  static char ID;

  MipsPreLegalizerCombiner();

  StringRef getPassName() const override { return "MipsPreLegalizerCombiner"; }

  bool runOnMachineFunction(MachineFunction &MF) override;

  void getAnalysisUsage(AnalysisUsage &AU) const override;

};

} // end anonymous namespace

void MipsPreLegalizerCombiner::getAnalysisUsage(AnalysisUsage &AU) const {

  AU.addRequired<TargetPassConfig>();

  AU.addRequired<GISelKnownBitsAnalysis>();

  AU.addPreserved<GISelKnownBitsAnalysis>();

  AU.setPreservesCFG();

  getSelectionDAGFallbackAnalysisUsage(AU);

  MachineFunctionPass::getAnalysisUsage(AU);

}

MipsPreLegalizerCombiner::MipsPreLegalizerCombiner() : MachineFunctionPass(ID) {

  initializeMipsPreLegalizerCombinerPass(*PassRegistry::getPassRegistry());

}

bool MipsPreLegalizerCombiner::runOnMachineFunction(MachineFunction &MF) {

  if (MF.getProperties().hasProperty(

          MachineFunctionProperties::Property::FailedISel))

    return false;

  auto *TPC = &getAnalysis<TargetPassConfig>();

  const MipsSubtarget &ST = MF.getSubtarget<MipsSubtarget>();

  const MipsLegalizerInfo *LI =

      static_cast<const MipsLegalizerInfo *>(ST.getLegalizerInfo());

  GISelKnownBits *KB = &getAnalysis<GISelKnownBitsAnalysis>().get(MF);

  MipsPreLegalizerCombinerInfo PCInfo;

  MipsPreLegalizerCombinerImpl Impl(MF, PCInfo, TPC, *KB, /*CSEInfo*/ nullptr,

                                    ST, /*MDT*/ nullptr, LI);

  return Impl.combineMachineInstrs();

}

char MipsPreLegalizerCombiner::ID = 0;

INITIALIZE_PASS_BEGIN(MipsPreLegalizerCombiner, DEBUG_TYPE,

                      "Combine Mips machine instrs before legalization", false,

                      false)

INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)

INITIALIZE_PASS_DEPENDENCY(GISelKnownBitsAnalysis)

INITIALIZE_PASS_END(MipsPreLegalizerCombiner, DEBUG_TYPE,

                    "Combine Mips machine instrs before legalization", false,

                    false)

namespace llvm {

FunctionPass *createMipsPreLegalizeCombiner() {

  return new MipsPreLegalizerCombiner();

}

} // end namespace llvm