lib/Target/X86/GISel/X86PostLegalizerCombiner.cpp

//===--------------- X86PostLegalizerCombiner.cpp ---------------*- 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
/// Post-legalization combines on generic MachineInstrs.
///
/// The combines here must preserve instruction legality.
///
/// Lowering combines (e.g. pseudo matching) should be handled by
/// X86PostLegalizerLowering.
///
/// Combines which don't rely on instruction legality should go in the
/// X86PreLegalizerCombiner.
///
//===----------------------------------------------------------------------===//
#include "X86.h"
#include "X86TargetMachine.h"
#include "llvm/CodeGen/GlobalISel/CSEInfo.h"
#include "llvm/CodeGen/GlobalISel/Combiner.h"
#include "llvm/CodeGen/GlobalISel/CombinerHelper.h"
#include "llvm/CodeGen/GlobalISel/CombinerInfo.h"
#include "llvm/CodeGen/GlobalISel/GIMatchTableExecutorImpl.h"
#include "llvm/CodeGen/GlobalISel/GISelChangeObserver.h"
#include "llvm/CodeGen/GlobalISel/GISelValueTracking.h"
#include "llvm/CodeGen/GlobalISel/MIPatternMatch.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/TargetPassConfig.h"

#define GET_GICOMBINER_DEPS
#include "X86GenPostLegalizeGICombiner.inc"
#undef GET_GICOMBINER_DEPS

#define DEBUG_TYPE "X86-postlegalizer-combiner"

using namespace llvm;
using namespace MIPatternMatch;

namespace {

CombinerInfo createCombinerInfo(bool OptEnabled, const Function &F) {
  CombinerInfo CInfo(/*AllowIllegalOps=*/true,
                     /*ShouldLegalizeIllegal=*/false,
                     /*LInfo=*/nullptr, /*OptEnabled=*/OptEnabled,
                     /*OptSize=*/F.hasOptSize(), /*MinSize=*/F.hasMinSize());
  // Disable fixed-point iteration to reduce compile-time
  CInfo.MaxIterations = 1;
  CInfo.ObserverLvl = CombinerInfo::ObserverLevel::SinglePass;
  // Legalizer performs DCE, so a full DCE pass is unnecessary.
  CInfo.EnableFullDCE = false;
  return CInfo;
}

#define GET_GICOMBINER_TYPES
#include "X86GenPostLegalizeGICombiner.inc"
#undef GET_GICOMBINER_TYPES

class X86PostLegalizerCombinerImpl : public Combiner {
protected:
  const CombinerHelper Helper;
  const X86PostLegalizerCombinerImplRuleConfig &RuleConfig;
  const X86Subtarget &STI;

public:
  X86PostLegalizerCombinerImpl(
      MachineFunction &MF, CombinerInfo &CInfo, GISelValueTracking &VT,
      GISelCSEInfo *CSEInfo,
      const X86PostLegalizerCombinerImplRuleConfig &RuleConfig,
      MachineDominatorTree *MDT);

  static const char *getName() { return "X86PostLegalizerCombiner"; }

  bool tryCombineAll(MachineInstr &I) const override;
  bool tryCombineAllImpl(MachineInstr &I) const;

private:
#define GET_GICOMBINER_CLASS_MEMBERS
#include "X86GenPostLegalizeGICombiner.inc"
#undef GET_GICOMBINER_CLASS_MEMBERS
};

#define GET_GICOMBINER_IMPL
#include "X86GenPostLegalizeGICombiner.inc"
#undef GET_GICOMBINER_IMPL

X86PostLegalizerCombinerImpl::X86PostLegalizerCombinerImpl(
    MachineFunction &MF, CombinerInfo &CInfo, GISelValueTracking &VT,
    GISelCSEInfo *CSEInfo,
    const X86PostLegalizerCombinerImplRuleConfig &RuleConfig,
    MachineDominatorTree *MDT)
    : Combiner(MF, CInfo, &VT, CSEInfo),
      Helper(Observer, B, /*IsPreLegalize=*/false, &VT, MDT,
             MF.getSubtarget<X86Subtarget>().getLegalizerInfo()),
      RuleConfig(RuleConfig), STI(MF.getSubtarget<X86Subtarget>()),
#define GET_GICOMBINER_CONSTRUCTOR_INITS
#include "X86GenPostLegalizeGICombiner.inc"
#undef GET_GICOMBINER_CONSTRUCTOR_INITS
{
}

bool X86PostLegalizerCombinerImpl::tryCombineAll(MachineInstr &MI) const {
  return tryCombineAllImpl(MI);
}

class X86PostLegalizerCombinerLegacy : public MachineFunctionPass {
public:
  static char ID;

  X86PostLegalizerCombinerLegacy();

  StringRef getPassName() const override {
    return "X86PostLegalizerCombinerLegacy";
  }

  bool runOnMachineFunction(MachineFunction &MF) override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;

private:
  X86PostLegalizerCombinerImplRuleConfig RuleConfig;
};
} // end anonymous namespace

void X86PostLegalizerCombinerLegacy::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.addRequired<TargetPassConfig>();
  AU.setPreservesCFG();
  getSelectionDAGFallbackAnalysisUsage(AU);
  AU.addRequired<GISelValueTrackingAnalysisLegacy>();
  AU.addPreserved<GISelValueTrackingAnalysisLegacy>();
  // This is only added when processing level is not OptNone.
  AU.addRequired<MachineDominatorTreeWrapperPass>();
  AU.addRequired<GISelCSEAnalysisWrapperPass>();
  AU.addPreserved<GISelCSEAnalysisWrapperPass>();

  MachineFunctionPass::getAnalysisUsage(AU);
}

X86PostLegalizerCombinerLegacy::X86PostLegalizerCombinerLegacy()
    : MachineFunctionPass(ID) {
  if (!RuleConfig.parseCommandLineOption())
    reportFatalInternalError("Invalid rule identifier");
}

bool X86PostLegalizerCombinerLegacy::runOnMachineFunction(MachineFunction &MF) {
  if (MF.getProperties().hasFailedISel())
    return false;
  assert(MF.getProperties().hasLegalized() && "Expected a legalized function?");
  auto *TPC = &getAnalysis<TargetPassConfig>();
  const Function &F = MF.getFunction();

  GISelValueTracking *VT =
      &getAnalysis<GISelValueTrackingAnalysisLegacy>().get(MF);
  MachineDominatorTree *MDT =
      &getAnalysis<MachineDominatorTreeWrapperPass>().getDomTree();
  GISelCSEAnalysisWrapper &Wrapper =
      getAnalysis<GISelCSEAnalysisWrapperPass>().getCSEWrapper();
  auto *CSEInfo = &Wrapper.get(TPC->getCSEConfig());

  CombinerInfo CInfo = createCombinerInfo(!skipFunction(F), F);

  X86PostLegalizerCombinerImpl Impl(MF, CInfo, *VT, CSEInfo, RuleConfig, MDT);
  return Impl.combineMachineInstrs();
}

char X86PostLegalizerCombinerLegacy::ID = 0;
INITIALIZE_PASS_BEGIN(X86PostLegalizerCombinerLegacy, DEBUG_TYPE,
                      "Combine X86 MachineInstrs after legalization", false,
                      false)
INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
INITIALIZE_PASS_DEPENDENCY(GISelValueTrackingAnalysisLegacy)
INITIALIZE_PASS_END(X86PostLegalizerCombinerLegacy, DEBUG_TYPE,
                    "Combine X86 MachineInstrs after legalization", false,
                    false)

namespace llvm {

PreservedAnalyses
X86PostLegalizerCombinerPass::run(MachineFunction &MF,
                                  MachineFunctionAnalysisManager &MFAM) {
  if (MF.getProperties().hasFailedISel())
    return PreservedAnalyses::all();
  assert(MF.getProperties().hasLegalized() && "Expected a legalized function.");
  const Function &F = MF.getFunction();

  GISelValueTracking VT = MFAM.getResult<GISelValueTrackingAnalysis>(MF);
  MachineDominatorTree &MDT = MFAM.getResult<MachineDominatorTreeAnalysis>(MF);
  auto &CSEInfo = MFAM.getResult<GISelCSEAnalysis>(MF);

  CombinerInfo CInfo = createCombinerInfo(true, F);

  X86PostLegalizerCombinerImplRuleConfig RuleConfig;
  if (!RuleConfig.parseCommandLineOption())
    reportFatalInternalError("Invalid rule identifier");

  X86PostLegalizerCombinerImpl Impl(MF, CInfo, VT, CSEInfo.get(), RuleConfig,
                                    &MDT);
  if (!Impl.combineMachineInstrs())
    return PreservedAnalyses::all();

  PreservedAnalyses PA = getMachineFunctionPassPreservedAnalyses();
  PA.preserveSet<CFGAnalyses>();
  PA.preserve<GISelCSEAnalysis>();
  PA.preserve<GISelValueTrackingAnalysis>();
  return PA;
}

FunctionPass *createX86PostLegalizerCombinerLegacy() {
  return new X86PostLegalizerCombinerLegacy();
}
} // end namespace llvm