code-comments.cc

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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#include <cstring>
#include <iomanip>
 
#include "src/codegen/assembler-inl.h"
#include "src/codegen/code-comments.h"
 
namespace v8 {
namespace internal {
 
namespace {
static constexpr uint8_t kOffsetToFirstCommentEntry = kUInt32Size;
static constexpr uint8_t kOffsetToPCOffset = 0;
static constexpr uint8_t kOffsetToCommentSize = kOffsetToPCOffset + kUInt32Size;
static constexpr uint8_t kOffsetToCommentString =
    kOffsetToCommentSize + kUInt32Size;
}  // namespace
 
uint32_t CodeCommentEntry::comment_length() const {
  return static_cast<uint32_t>(comment.size() + 1);
}
 
uint32_t CodeCommentEntry::size() const {
  return kOffsetToCommentString + comment_length();
}
 
CodeCommentsIterator::CodeCommentsIterator(Address code_comments_start,
                                           uint32_t code_comments_size)
    : code_comments_start_(code_comments_start),
      code_comments_size_(code_comments_size),
      current_entry_(code_comments_start + kOffsetToFirstCommentEntry) {
  DCHECK_NE(kNullAddress, code_comments_start);
  DCHECK_IMPLIES(code_comments_size,
                 code_comments_size ==
                     base::ReadUnalignedValue<uint32_t>(code_comments_start_));
}
 
uint32_t CodeCommentsIterator::size() const { return code_comments_size_; }
 
const char* CodeCommentsIterator::GetComment() const {
  const char* comment_string =
      reinterpret_cast<const char*>(current_entry_ + kOffsetToCommentString);
  CHECK_EQ(GetCommentSize(), strlen(comment_string) + 1);
  return comment_string;
}
 
uint32_t CodeCommentsIterator::GetCommentSize() const {
  return ReadUnalignedValue<uint32_t>(current_entry_ + kOffsetToCommentSize);
}
 
uint32_t CodeCommentsIterator::GetPCOffset() const {
  return ReadUnalignedValue<uint32_t>(current_entry_ + kOffsetToPCOffset);
}
 
void CodeCommentsIterator::Next() {
  current_entry_ += kOffsetToCommentString + GetCommentSize();
}
 
bool CodeCommentsIterator::HasCurrent() const {
  return current_entry_ < code_comments_start_ + size();
}
 
void CodeCommentsWriter::Emit(Assembler* assm) {
  assm->dd(section_size());
  for (auto i = comments_.begin(); i != comments_.end(); ++i) {
    assm->dd(i->pc_offset);
    assm->dd(i->comment_length());
    for (char c : i->comment) {
      EnsureSpace ensure_space(assm);
      assm->db(c);
    }
    assm->db('\0');
  }
}
 
void CodeCommentsWriter::Add(uint32_t pc_offset, std::string comment) {
  CodeCommentEntry entry = {pc_offset, std::move(comment)};
  byte_count_ += entry.size();
  comments_.push_back(std::move(entry));
}
 
size_t CodeCommentsWriter::entry_count() const { return comments_.size(); }
uint32_t CodeCommentsWriter::section_size() const {
  return kOffsetToFirstCommentEntry + static_cast<uint32_t>(byte_count_);
}
 
}  // namespace internal
}  // namespace v8