// 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/compact_ids_pass.h"

#include <cassert>

#include <unordered_map>

#include "source/opt/ir_context.h"

namespace spvtools {

namespace opt {

namespace {

// Returns the remapped id of |id| from |result_id_mapping|. If the remapped

// id does not exist, adds a new one to |result_id_mapping| and returns it.

uint32_t GetRemappedId(

    std::unordered_map<uint32_t, uint32_t>* result_id_mapping, uint32_t id) {

  auto it = result_id_mapping->find(id);

  if (it == result_id_mapping->end()) {

    const uint32_t new_id =

        static_cast<uint32_t>(result_id_mapping->size()) + 1;

    const auto insertion_result = result_id_mapping->emplace(id, new_id);

    it = insertion_result.first;

    assert(insertion_result.second);

  }

  return it->second;

}

}  // namespace

Pass::Status CompactIdsPass::Process() {

  bool modified = false;

  std::unordered_map<uint32_t, uint32_t> result_id_mapping;

  // Disable automatic DebugInfo analysis for the life of the CompactIds pass.

  // The DebugInfo manager requires the SPIR-V to be valid to run, but this is

  // not true at all times in CompactIds as it remaps all ids.

  context()->InvalidateAnalyses(IRContext::kAnalysisDebugInfo);

  context()->module()->ForEachInst(

      [&result_id_mapping, &modified](Instruction* inst) {

        auto operand = inst->begin();

        while (operand != inst->end()) {

          const auto type = operand->type;

          if (spvIsIdType(type)) {

            assert(operand->words.size() == 1);

            uint32_t& id = operand->words[0];

            uint32_t new_id = GetRemappedId(&result_id_mapping, id);

            if (id != new_id) {

              modified = true;

              id = new_id;

              // Update data cached in the instruction object.

              if (type == SPV_OPERAND_TYPE_RESULT_ID) {

                inst->SetResultId(id);

              } else if (type == SPV_OPERAND_TYPE_TYPE_ID) {

                inst->SetResultType(id);

              }

            }

          }

          ++operand;

        }

        uint32_t scope_id = inst->GetDebugScope().GetLexicalScope();

        if (scope_id != kNoDebugScope) {

          uint32_t new_id = GetRemappedId(&result_id_mapping, scope_id);

          if (scope_id != new_id) {

            inst->UpdateLexicalScope(new_id);

            modified = true;

          }

        }

        uint32_t inlinedat_id = inst->GetDebugInlinedAt();

        if (inlinedat_id != kNoInlinedAt) {

          uint32_t new_id = GetRemappedId(&result_id_mapping, inlinedat_id);

          if (inlinedat_id != new_id) {

            inst->UpdateDebugInlinedAt(new_id);

            modified = true;

          }

        }

      },

      true);

  if (context()->module()->id_bound() != result_id_mapping.size() + 1) {

    modified = true;

    context()->module()->SetIdBound(

        static_cast<uint32_t>(result_id_mapping.size() + 1));

    // There are ids in the feature manager that could now be invalid

    context()->ResetFeatureManager();

  }

  return modified ? Status::SuccessWithChange : Status::SuccessWithoutChange;

}

}  // namespace opt

}  // namespace spvtools