// Copyright (c) 2017 Google Inc.

//

// Licensed under the Apache License, Version 2.0 (the "License");

// you may not use this file except in compliance with the License.

// You may obtain a copy of the License at

//

//     http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software

// distributed under the License is distributed on an "AS IS" BASIS,

// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

// See the License for the specific language governing permissions and

// limitations under the License.

#include "source/opt/eliminate_dead_functions_pass.h"

#include "source/opt/eliminate_dead_functions_util.h"

#include <unordered_set>

#include "source/opt/ir_context.h"

namespace spvtools {

namespace opt {

Pass::Status EliminateDeadFunctionsPass::Process() {

  // Identify live functions first.  Those that are not live

  // are dead.

  std::unordered_set<const Function*> live_function_set;

  ProcessFunction mark_live = [&live_function_set](Function* fp) {

    live_function_set.insert(fp);

    return false;

  };

  context()->ProcessReachableCallTree(mark_live);

  bool modified = false;

  for (auto funcIter = get_module()->begin();

       funcIter != get_module()->end();) {

    if (live_function_set.count(&*funcIter) == 0) {

      modified = true;

      funcIter =

          eliminatedeadfunctionsutil::EliminateFunction(context(), &funcIter);

    } else {

      ++funcIter;

    }

  }

  return modified ? Pass::Status::SuccessWithChange

                  : Pass::Status::SuccessWithoutChange;

}

}  // namespace opt

}  // namespace spvtools