source/opt/process_lines_pass.cpp

// Copyright (c) 2018 The Khronos Group Inc.
// Copyright (c) 2018 Valve Corporation
// Copyright (c) 2018 LunarG 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/process_lines_pass.h"

#include <set>
#include <unordered_set>
#include <vector>

namespace {

// Input Operand Indices
static const int kSpvLineFileInIdx = 0;
static const int kSpvLineLineInIdx = 1;
static const int kSpvLineColInIdx = 2;

}  // anonymous namespace

namespace spvtools {
namespace opt {

Pass::Status ProcessLinesPass::Process() {
  bool modified = ProcessLines();
  return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
}

bool ProcessLinesPass::ProcessLines() {
  bool modified = false;
  uint32_t file_id = 0;
  uint32_t line = 0;
  uint32_t col = 0;
  // Process types, globals, constants
  for (Instruction& inst : get_module()->types_values())
    modified |= line_process_func_(&inst, &file_id, &line, &col);
  // Process functions
  for (Function& function : *get_module()) {
    modified |= line_process_func_(&function.DefInst(), &file_id, &line, &col);
    function.ForEachParam(
        [this, &modified, &file_id, &line, &col](Instruction* param) {
          modified |= line_process_func_(param, &file_id, &line, &col);
        });
    for (BasicBlock& block : function) {
      modified |=
          line_process_func_(block.GetLabelInst(), &file_id, &line, &col);
      for (Instruction& inst : block) {
        modified |= line_process_func_(&inst, &file_id, &line, &col);
        // Don't process terminal instruction if preceeded by merge
        if (inst.opcode() == SpvOpSelectionMerge ||
            inst.opcode() == SpvOpLoopMerge)
          break;
      }
      // Nullify line info after each block.
      file_id = 0;
    }
    modified |= line_process_func_(function.EndInst(), &file_id, &line, &col);
  }
  return modified;
}

bool ProcessLinesPass::PropagateLine(Instruction* inst, uint32_t* file_id,
                                     uint32_t* line, uint32_t* col) {
  bool modified = false;
  // only the last debug instruction needs to be considered
  auto line_itr = inst->dbg_line_insts().rbegin();
  // if no line instructions, propagate previous info
  if (line_itr == inst->dbg_line_insts().rend()) {
    // if no current line info, add OpNoLine, else OpLine
    if (*file_id == 0)
      inst->dbg_line_insts().push_back(Instruction(context(), SpvOpNoLine));
    else
      inst->dbg_line_insts().push_back(Instruction(
          context(), SpvOpLine, 0, 0,
          {{spv_operand_type_t::SPV_OPERAND_TYPE_ID, {*file_id}},
           {spv_operand_type_t::SPV_OPERAND_TYPE_LITERAL_INTEGER, {*line}},
           {spv_operand_type_t::SPV_OPERAND_TYPE_LITERAL_INTEGER, {*col}}}));
    modified = true;
  } else {
    // else pre-existing line instruction, so update source line info
    if (line_itr->opcode() == SpvOpNoLine) {
      *file_id = 0;
    } else {
      assert(line_itr->opcode() == SpvOpLine && "unexpected debug inst");
      *file_id = line_itr->GetSingleWordInOperand(kSpvLineFileInIdx);
      *line = line_itr->GetSingleWordInOperand(kSpvLineLineInIdx);
      *col = line_itr->GetSingleWordInOperand(kSpvLineColInIdx);
    }
  }
  return modified;
}

bool ProcessLinesPass::EliminateDeadLines(Instruction* inst, uint32_t* file_id,
                                          uint32_t* line, uint32_t* col) {
  // If no debug line instructions, return without modifying lines
  if (inst->dbg_line_insts().empty()) return false;
  // Only the last debug instruction needs to be considered; delete all others
  bool modified = inst->dbg_line_insts().size() > 1;
  Instruction last_inst = inst->dbg_line_insts().back();
  inst->dbg_line_insts().clear();
  // If last line is OpNoLine
  if (last_inst.opcode() == SpvOpNoLine) {
    // If no propagated line info, throw away redundant OpNoLine
    if (*file_id == 0) {
      modified = true;
      // Else replace OpNoLine and propagate no line info
    } else {
      inst->dbg_line_insts().push_back(last_inst);
      *file_id = 0;
    }
  } else {
    // Else last line is OpLine
    assert(last_inst.opcode() == SpvOpLine && "unexpected debug inst");
    // If propagated info matches last line, throw away last line
    if (*file_id == last_inst.GetSingleWordInOperand(kSpvLineFileInIdx) &&
        *line == last_inst.GetSingleWordInOperand(kSpvLineLineInIdx) &&
        *col == last_inst.GetSingleWordInOperand(kSpvLineColInIdx)) {
      modified = true;
    } else {
      // Else replace last line and propagate line info
      *file_id = last_inst.GetSingleWordInOperand(kSpvLineFileInIdx);
      *line = last_inst.GetSingleWordInOperand(kSpvLineLineInIdx);
      *col = last_inst.GetSingleWordInOperand(kSpvLineColInIdx);
      inst->dbg_line_insts().push_back(last_inst);
    }
  }
  return modified;
}

ProcessLinesPass::ProcessLinesPass(uint32_t func_id) {
  if (func_id == kLinesPropagateLines) {
    line_process_func_ = [this](Instruction* inst, uint32_t* file_id,
                                uint32_t* line, uint32_t* col) {
      return PropagateLine(inst, file_id, line, col);
    };
  } else {
    assert(func_id == kLinesEliminateDeadLines && "unknown Lines param");
    line_process_func_ = [this](Instruction* inst, uint32_t* file_id,
                                uint32_t* line, uint32_t* col) {
      return EliminateDeadLines(inst, file_id, line, col);
    };
  }
}

}  // namespace opt
}  // namespace spvtools