//===- MachinePostDominators.cpp -Machine Post Dominator Calculation ------===//

//

// 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 file implements simple dominator construction algorithms for finding

// post dominators on machine functions.

//

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

#include "llvm/CodeGen/MachinePostDominators.h"

#include "llvm/InitializePasses.h"

using namespace llvm;

namespace llvm {

template class DominatorTreeBase<MachineBasicBlock, true>; // PostDomTreeBase

extern bool VerifyMachineDomInfo;

} // namespace llvm

char MachinePostDominatorTree::ID = 0;

//declare initializeMachinePostDominatorTreePass

INITIALIZE_PASS(MachinePostDominatorTree, "machinepostdomtree",

                "MachinePostDominator Tree Construction", true, true)

MachinePostDominatorTree::MachinePostDominatorTree()

    : MachineFunctionPass(ID), PDT(nullptr) {

  initializeMachinePostDominatorTreePass(*PassRegistry::getPassRegistry());

}

FunctionPass *MachinePostDominatorTree::createMachinePostDominatorTreePass() {

  return new MachinePostDominatorTree();

}

bool MachinePostDominatorTree::runOnMachineFunction(MachineFunction &F) {

  PDT = std::make_unique<PostDomTreeT>();

  PDT->recalculate(F);

  return false;

}

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

  AU.setPreservesAll();

  MachineFunctionPass::getAnalysisUsage(AU);

}

MachineBasicBlock *MachinePostDominatorTree::findNearestCommonDominator(

    ArrayRef<MachineBasicBlock *> Blocks) const {

  assert(!Blocks.empty());

  MachineBasicBlock *NCD = Blocks.front();

  for (MachineBasicBlock *BB : Blocks.drop_front()) {

    NCD = PDT->findNearestCommonDominator(NCD, BB);

    // Stop when the root is reached.

    if (PDT->isVirtualRoot(PDT->getNode(NCD)))

      return nullptr;

  }

  return NCD;

}

void MachinePostDominatorTree::verifyAnalysis() const {

  if (PDT && VerifyMachineDomInfo)

    if (!PDT->verify(PostDomTreeT::VerificationLevel::Basic)) {

      errs() << "MachinePostDominatorTree verification failed\n";

      abort();

    }

}

void MachinePostDominatorTree::print(llvm::raw_ostream &OS,

                                     const Module *M) const {

  PDT->print(OS);

}