builtin-jump-table-info-x64.h

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// Copyright 2024 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.
 
#ifndef V8_CODEGEN_X64_BUILTIN_JUMP_TABLE_INFO_X64_H_
#define V8_CODEGEN_X64_BUILTIN_JUMP_TABLE_INFO_X64_H_
 
#include <vector>
 
#include "include/v8-internal.h"
#include "src/base/macros.h"
#include "src/common/globals.h"
 
namespace v8 {
namespace internal {
 
class Assembler;
 
// The builtin jump table info is a part of code metadata, used by the
// disassembler. The layout is:
//
// byte count       content
// ----------------------------------------------------------------
// [Inline array of BuiltinJumpTableInfoEntry in increasing pc_offset order]
// ┌ 4              pc_offset of entry as uint32_t
// └ 4              target of entry as int32_t
 
struct BuiltinJumpTableInfoEntry {
  constexpr BuiltinJumpTableInfoEntry(uint32_t pc_offset, int32_t target)
      : pc_offset(pc_offset), target(target) {}
  uint32_t pc_offset;
  int32_t target;
 
  static constexpr int kPCOffsetSize = kUInt32Size;
  static constexpr int kTargetSize = kInt32Size;
  static constexpr int kSize = kPCOffsetSize + kTargetSize;
};
static_assert(sizeof(BuiltinJumpTableInfoEntry) ==
              BuiltinJumpTableInfoEntry::kSize);
 
// Used during codegen.
class BuiltinJumpTableInfoWriter {
 public:
  V8_EXPORT_PRIVATE void Add(uint32_t pc_offset, int32_t target);
  void Emit(Assembler* assm);
 
  size_t entry_count() const;
  uint32_t size_in_bytes() const;
 
 private:
  std::vector<BuiltinJumpTableInfoEntry> entries_;
};
 
// Used during disassembly.
class V8_EXPORT_PRIVATE BuiltinJumpTableInfoIterator {
 public:
  BuiltinJumpTableInfoIterator(Address start, uint32_t size);
  uint32_t GetPCOffset() const;
  int32_t GetTarget() const;
  void Next();
  bool HasCurrent() const;
 
 private:
  const Address start_;
  const uint32_t size_;
  Address cursor_;
};
 
}  // namespace internal
}  // namespace v8
 
#endif  // V8_CODEGEN_X64_BUILTIN_JUMP_TABLE_INFO_X64_H_