RISCVPreLegalizerCombiner.cpp

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//=== RISCVPreLegalizerCombiner.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 "RISCV.h"
#include "RISCVSubtarget.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/GISelValueTracking.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionAnalysisManager.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachinePassManager.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/Analysis.h"
#include "llvm/Support/ErrorHandling.h"
 
#define GET_GICOMBINER_DEPS
#include "RISCVGenPreLegalizeGICombiner.inc"
#undef GET_GICOMBINER_DEPS
 
#define DEBUG_TYPE "riscv-prelegalizer-combiner"
 
using namespace llvm;
 
namespace {
 
#define GET_GICOMBINER_TYPES
#include "RISCVGenPreLegalizeGICombiner.inc"
#undef GET_GICOMBINER_TYPES
 
class RISCVPreLegalizerCombinerImpl : public Combiner {
protected:
  const CombinerHelper Helper;
  const RISCVPreLegalizerCombinerImplRuleConfig &RuleConfig;
  const RISCVSubtarget &STI;
 
public:
  RISCVPreLegalizerCombinerImpl(
      MachineFunction &MF, CombinerInfo &CInfo, GISelValueTracking &VT,
      GISelCSEInfo *CSEInfo,
      const RISCVPreLegalizerCombinerImplRuleConfig &RuleConfig,
      const RISCVSubtarget &STI, MachineDominatorTree *MDT,
      const LegalizerInfo *LI);
 
  static const char *getName() { return "RISCV00PreLegalizerCombiner"; }
 
  bool tryCombineAll(MachineInstr &I) const override;
 
private:
#define GET_GICOMBINER_CLASS_MEMBERS
#include "RISCVGenPreLegalizeGICombiner.inc"
#undef GET_GICOMBINER_CLASS_MEMBERS
};
 
#define GET_GICOMBINER_IMPL
#include "RISCVGenPreLegalizeGICombiner.inc"
#undef GET_GICOMBINER_IMPL
 
RISCVPreLegalizerCombinerImpl::RISCVPreLegalizerCombinerImpl(
    MachineFunction &MF, CombinerInfo &CInfo, GISelValueTracking &VT,
    GISelCSEInfo *CSEInfo,
    const RISCVPreLegalizerCombinerImplRuleConfig &RuleConfig,
    const RISCVSubtarget &STI, MachineDominatorTree *MDT,
    const LegalizerInfo *LI)
    : Combiner(MF, CInfo, &VT, CSEInfo),
      Helper(Observer, B, /*IsPreLegalize*/ true, &VT, MDT, LI),
      RuleConfig(RuleConfig), STI(STI),
#define GET_GICOMBINER_CONSTRUCTOR_INITS
#include "RISCVGenPreLegalizeGICombiner.inc"
#undef GET_GICOMBINER_CONSTRUCTOR_INITS
{
}
 
// Pass boilerplate
// ================
 
class RISCVPreLegalizerCombinerLegacy : public MachineFunctionPass {
public:
  static char ID;
 
  RISCVPreLegalizerCombinerLegacy();
 
  StringRef getPassName() const override { return "RISCVPreLegalizerCombiner"; }
 
  bool runOnMachineFunction(MachineFunction &MF) override;
 
  void getAnalysisUsage(AnalysisUsage &AU) const override;
};
} // end anonymous namespace
 
void RISCVPreLegalizerCombinerLegacy::getAnalysisUsage(
    AnalysisUsage &AU) const {
  AU.addRequired<TargetPassConfig>();
  AU.setPreservesCFG();
  getSelectionDAGFallbackAnalysisUsage(AU);
  AU.addRequired<GISelValueTrackingAnalysisLegacy>();
  AU.addPreserved<GISelValueTrackingAnalysisLegacy>();
  AU.addRequired<MachineDominatorTreeWrapperPass>();
  AU.addRequired<GISelCSEAnalysisWrapperPass>();
  AU.addPreserved<GISelCSEAnalysisWrapperPass>();
  MachineFunctionPass::getAnalysisUsage(AU);
}
 
RISCVPreLegalizerCombinerLegacy::RISCVPreLegalizerCombinerLegacy()
    : MachineFunctionPass(ID) {}
 
static bool
runVPreLegalizerCombiner(MachineFunction &MF, function_ref<bool()> ShouldSkip,
                         function_ref<GISelCSEInfo *()> GetCSEInfo,
                         function_ref<GISelValueTracking *()> GetVT,
                         function_ref<MachineDominatorTree *()> GetMDT) {
  if (MF.getProperties().hasFailedISel())
    return false;
  RISCVPreLegalizerCombinerImplRuleConfig RuleConfig;
  if (!RuleConfig.parseCommandLineOption())
    reportFatalUsageError("Invalid rule identifier");
 
  GISelCSEInfo *CSEInfo = GetCSEInfo();
 
  const RISCVSubtarget &ST = MF.getSubtarget<RISCVSubtarget>();
  const auto *LI = ST.getLegalizerInfo();
 
  const Function &F = MF.getFunction();
  bool EnableOpt =
      MF.getTarget().getOptLevel() != CodeGenOptLevel::None && !ShouldSkip();
  GISelValueTracking *VT = GetVT();
  MachineDominatorTree *MDT = GetMDT();
  CombinerInfo CInfo(/*AllowIllegalOps*/ true, /*ShouldLegalizeIllegal*/ false,
                     /*LegalizerInfo*/ nullptr, EnableOpt, F.hasOptSize(),
                     F.hasMinSize());
  // Disable fixed-point iteration to reduce compile-time
  CInfo.MaxIterations = 1;
  CInfo.ObserverLvl = CombinerInfo::ObserverLevel::SinglePass;
  // This is the first Combiner, so the input IR might contain dead
  // instructions.
  CInfo.EnableFullDCE = true;
  RISCVPreLegalizerCombinerImpl Impl(MF, CInfo, *VT, CSEInfo, RuleConfig, ST,
                                     MDT, LI);
  return Impl.combineMachineInstrs();
}
 
char RISCVPreLegalizerCombinerLegacy::ID = 0;
INITIALIZE_PASS_BEGIN(RISCVPreLegalizerCombinerLegacy, DEBUG_TYPE,
                      "Combine RISC-V machine instrs before legalization",
                      false, false)
INITIALIZE_PASS_DEPENDENCY(TargetPassConfig)
INITIALIZE_PASS_DEPENDENCY(GISelValueTrackingAnalysisLegacy)
INITIALIZE_PASS_DEPENDENCY(GISelCSEAnalysisWrapperPass)
INITIALIZE_PASS_END(RISCVPreLegalizerCombinerLegacy, DEBUG_TYPE,
                    "Combine RISC-V machine instrs before legalization", false,
                    false)
 
FunctionPass *llvm::createRISCVPreLegalizerCombinerLegacyPass() {
  return new RISCVPreLegalizerCombinerLegacy();
}
 
bool RISCVPreLegalizerCombinerLegacy::runOnMachineFunction(
    MachineFunction &MF) {
  return runVPreLegalizerCombiner(
      MF, [&]() { return skipFunction(MF.getFunction()); },
      [&]() {
        TargetPassConfig &TPC = getAnalysis<TargetPassConfig>();
        GISelCSEAnalysisWrapper &Wrapper =
            getAnalysis<GISelCSEAnalysisWrapperPass>().getCSEWrapper();
        return &Wrapper.get(TPC.getCSEConfig());
      },
      [&]() {
        return &getAnalysis<GISelValueTrackingAnalysisLegacy>().get(MF);
      },
      [&]() {
        return &getAnalysis<MachineDominatorTreeWrapperPass>().getDomTree();
      });
}
 
PreservedAnalyses
RISCVPreLegalizerCombinerPass::run(MachineFunction &MF,
                                   MachineFunctionAnalysisManager &MFAM) {
  bool Changed = runVPreLegalizerCombiner(
      MF,
      [&]() {
        return MF.getFunction().hasOptNone() ||
               shouldSkipOptimizationForOptBisect(MF.getFunction());
      },
      [&]() { return MFAM.getResult<GISelCSEAnalysis>(MF).get(); },
      [&]() { return &MFAM.getResult<GISelValueTrackingAnalysis>(MF); },
      [&]() { return &MFAM.getResult<MachineDominatorTreeAnalysis>(MF); });
  if (!Changed)
    return PreservedAnalyses::all();
  return getMachineFunctionPassPreservedAnalyses()
      .preserveSet<CFGAnalyses>()
      .preserve<GISelCSEAnalysis>()
      .preserve<GISelValueTrackingAnalysis>();
}