//===- lib/Codegen/MachineRegionInfo.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
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/MachineRegionInfo.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/RegionInfoImpl.h"
#include "llvm/CodeGen/MachinePostDominators.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"

#define DEBUG_TYPE "machine-region-info"

using namespace llvm;

STATISTIC(numMachineRegions,       "The # of machine regions");
STATISTIC(numMachineSimpleRegions, "The # of simple machine regions");

namespace llvm {

template class LLVM_EXPORT_TEMPLATE RegionBase<RegionTraits<MachineFunction>>;
template class LLVM_EXPORT_TEMPLATE
    RegionNodeBase<RegionTraits<MachineFunction>>;
template class LLVM_EXPORT_TEMPLATE
    RegionInfoBase<RegionTraits<MachineFunction>>;

} // end namespace llvm

//===----------------------------------------------------------------------===//
// RegionTraits<MachineFunction> implementation
//

void RegionTraits<MachineFunction>::updateStatistics(MachineRegion *R) {
  ++numMachineRegions;

  // TODO: Slow. Should only be enabled if -stats is used.
  if (R->isSimple())
    ++numMachineSimpleRegions;
}

//===----------------------------------------------------------------------===//
// MachineRegion implementation

MachineRegion::MachineRegion(MachineBasicBlock *Entry, MachineBasicBlock *Exit,
                             MachineRegionInfo* RI,
                             MachineDominatorTree *DT, MachineRegion *Parent) :
  RegionBase<RegionTraits<MachineFunction>>(Entry, Exit, RI, DT, Parent) {}

MachineRegion::~MachineRegion() = default;

//===----------------------------------------------------------------------===//
// MachineRegionInfo implementation

MachineRegionInfo::MachineRegionInfo() = default;

MachineRegionInfo::~MachineRegionInfo() = default;

void MachineRegionInfo::recalculate(MachineFunction &F,
                                    MachineDominatorTree *DT_,
                                    MachinePostDominatorTree *PDT_,
                                    MachineDominanceFrontier *DF_) {
  DT = DT_;
  PDT = PDT_;
  DF = DF_;

  MachineBasicBlock *Entry = GraphTraits<MachineFunction*>::getEntryNode(&F);

  TopLevelRegion = new MachineRegion(Entry, nullptr, this, DT, nullptr);
  RegionTraits<MachineFunction>::updateStatistics(TopLevelRegion);
  calculate(F);
}

bool MachineRegionInfo::invalidate(
    MachineFunction &F, const PreservedAnalyses &PA,
    MachineFunctionAnalysisManager::Invalidator &) {
  // Check whether the analysis, all analyses on functions, or the function's
  // CFG has been preserved.
  auto PAC = PA.getChecker<MachineRegionInfoAnalysis>();
  return !(PAC.preserved() ||
           PAC.preservedSet<AllAnalysesOn<MachineFunction>>() ||
           PAC.preservedSet<CFGAnalyses>());
}

//===----------------------------------------------------------------------===//
// MachineRegionAnalysis implementation
//
AnalysisKey MachineRegionInfoAnalysis::Key;
MachineRegionInfo
MachineRegionInfoAnalysis::run(MachineFunction &MF,
                               MachineFunctionAnalysisManager &MFAM) {
  MachineRegionInfo MRI;
  MRI.recalculate(MF, &MFAM.getResult<MachineDominatorTreeAnalysis>(MF),
                  &MFAM.getResult<MachinePostDominatorTreeAnalysis>(MF),
                  &MFAM.getResult<MachineDominanceFrontierAnalysis>(MF));
  return MRI;
}

PreservedAnalyses
MachineRegionInfoPrinterPass::run(MachineFunction &MF,
                                  MachineFunctionAnalysisManager &MFAM) {
  MachineRegionInfo &MRI = MFAM.getResult<MachineRegionInfoAnalysis>(MF);
  MRI.print(OS);
  return PreservedAnalyses::all();
}

//===----------------------------------------------------------------------===//
// MachineRegionInfoPass implementation
//

MachineRegionInfoPass::MachineRegionInfoPass() : MachineFunctionPass(ID) {}

MachineRegionInfoPass::~MachineRegionInfoPass() = default;

bool MachineRegionInfoPass::runOnMachineFunction(MachineFunction &F) {
  releaseMemory();

  auto DT = &getAnalysis<MachineDominatorTreeWrapperPass>().getDomTree();
  auto PDT =
      &getAnalysis<MachinePostDominatorTreeWrapperPass>().getPostDomTree();
  auto DF = &getAnalysis<MachineDominanceFrontierWrapperPass>().getMDF();

  RI.recalculate(F, DT, PDT, DF);

  LLVM_DEBUG(RI.dump());

  return false;
}

void MachineRegionInfoPass::releaseMemory() {
  RI.releaseMemory();
}

void MachineRegionInfoPass::verifyAnalysis() const {
  // Only do verification when user wants to.
  if (MachineRegionInfo::VerifyRegionInfo)
    RI.verifyAnalysis();
}

void MachineRegionInfoPass::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.setPreservesAll();
  AU.addRequired<MachineDominatorTreeWrapperPass>();
  AU.addRequired<MachinePostDominatorTreeWrapperPass>();
  AU.addRequired<MachineDominanceFrontierWrapperPass>();
  MachineFunctionPass::getAnalysisUsage(AU);
}

void MachineRegionInfoPass::print(raw_ostream &OS, const Module *) const {
  RI.print(OS);
}

#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
LLVM_DUMP_METHOD void MachineRegionInfoPass::dump() const {
  RI.dump();
}
#endif

char MachineRegionInfoPass::ID = 0;
char &llvm::MachineRegionInfoPassID = MachineRegionInfoPass::ID;

INITIALIZE_PASS_BEGIN(MachineRegionInfoPass, DEBUG_TYPE,
                      "Detect single entry single exit regions", true, true)
INITIALIZE_PASS_DEPENDENCY(MachineDominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MachinePostDominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MachineDominanceFrontierWrapperPass)
INITIALIZE_PASS_END(MachineRegionInfoPass, DEBUG_TYPE,
                    "Detect single entry single exit regions", true, true)

// Create methods available outside of this file, to use them
// "include/llvm/LinkAllPasses.h". Otherwise the pass would be deleted by
// the link time optimization.

namespace llvm {

FunctionPass *createMachineRegionInfoPass() {
  return new MachineRegionInfoPass();
}

} // end namespace llvm