// Copyright (c) 2016 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/strip_debug_info_pass.h"

#include "source/opt/ir_context.h"

#include "source/util/string_utils.h"

namespace spvtools {

namespace opt {

Pass::Status StripDebugInfoPass::Process() {

  bool uses_non_semantic_info = false;

  for (auto& inst : context()->module()->extensions()) {

    const std::string ext_name = inst.GetInOperand(0).AsString();

    if (ext_name == "SPV_KHR_non_semantic_info") {

      uses_non_semantic_info = true;

    }

  }

  std::vector<Instruction*> to_kill;

  // if we use non-semantic info, it may reference OpString. Do a more

  // expensive pass checking the uses of the OpString to see if any are

  // OpExtInst on a non-semantic instruction set. If we're not using the

  // extension then we can do a simpler pass and kill all debug1 instructions

  if (uses_non_semantic_info) {

    for (auto& inst : context()->module()->debugs1()) {

      switch (inst.opcode()) {

        case spv::Op::OpString: {

          analysis::DefUseManager* def_use = context()->get_def_use_mgr();

          // see if this string is used anywhere by a non-semantic instruction

          bool no_nonsemantic_use =

              def_use->WhileEachUser(&inst, [def_use](Instruction* use) {

                if (spvIsExtendedInstruction(use->opcode())) {

                  auto ext_inst_set =

                      def_use->GetDef(use->GetSingleWordInOperand(0u));

                  const std::string extension_name =

                      ext_inst_set->GetInOperand(0).AsString();

                  if (spvtools::utils::starts_with(extension_name,

                                                   "NonSemantic.")) {

                    // found a non-semantic use, return false as we cannot

                    // remove this OpString

                    return false;

                  }

                }

                // other instructions can't be a non-semantic use

                return true;

              });

          if (no_nonsemantic_use) to_kill.push_back(&inst);

          break;

        }

        default:

          to_kill.push_back(&inst);

          break;

      }

    }

  } else {

    for (auto& dbg : context()->debugs1()) to_kill.push_back(&dbg);

  }

  for (auto& dbg : context()->debugs2()) to_kill.push_back(&dbg);

  for (auto& dbg : context()->debugs3()) to_kill.push_back(&dbg);

  for (auto& dbg : context()->ext_inst_debuginfo()) to_kill.push_back(&dbg);

  // OpName must come first, since they may refer to other debug instructions.

  // If they are after the instructions that refer to, then they will be killed

  // when that instruction is killed, which will lead to a double kill.

  std::sort(to_kill.begin(), to_kill.end(),

            [](Instruction* lhs, Instruction* rhs) -> bool {

              if (lhs->opcode() == spv::Op::OpName &&

                  rhs->opcode() != spv::Op::OpName)

                return true;

              return false;

            });

  bool modified = !to_kill.empty();

  for (auto* inst : to_kill) context()->KillInst(inst);

  // clear OpLine information

  context()->module()->ForEachInst([&modified](Instruction* inst) {

    modified |= !inst->dbg_line_insts().empty();

    inst->dbg_line_insts().clear();

  });

  if (!get_module()->trailing_dbg_line_info().empty()) {

    modified = true;

    get_module()->trailing_dbg_line_info().clear();

  }

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

}

}  // namespace opt

}  // namespace spvtools