xref: /third_party/node/deps/v8/src/codegen/code-desc.h (revision 1cb0ef41) 
1// Copyright 2019 the V8 project authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef V8_CODEGEN_CODE_DESC_H_
6#define V8_CODEGEN_CODE_DESC_H_
7
8#include "src/common/globals.h"
9
10namespace v8 {
11namespace internal {
12
13// A CodeDesc describes a buffer holding instructions and relocation
14// information. The instructions start at the beginning of the buffer
15// and grow forward, the relocation information starts at the end of
16// the buffer and grows backward. Inlined metadata sections may exist
17// at the end of the instructions.
18//
19//  |<--------------- buffer_size ----------------------------------->|
20//  |<---------------- instr_size ------------->|      |<-reloc_size->|
21//  |--------------+----------------------------+------+--------------|
22//  | instructions |         data               | free |  reloc info  |
23//  +--------------+----------------------------+------+--------------+
24
25// TODO(jgruber): Add a single chokepoint for specifying the instruction area
26// layout (i.e. the order of inlined metadata fields).
27// TODO(jgruber): Systematically maintain inlined metadata offsets and sizes
28// to simplify CodeDesc initialization.
29
30class CodeDesc {
31 public:
32  static void Initialize(CodeDesc* desc, Assembler* assembler,
33                         int safepoint_table_offset, int handler_table_offset,
34                         int constant_pool_offset, int code_comments_offset,
35                         int reloc_info_offset);
36
37#ifdef DEBUG
38  static void Verify(const CodeDesc* desc);
39#else
40  inline static void Verify(const CodeDesc* desc) {}
41#endif
42
43 public:
44  byte* buffer = nullptr;
45  int buffer_size = 0;
46
47  // The instruction area contains executable code plus inlined metadata.
48
49  int instr_size = 0;
50
51  // Metadata packed into the instructions area.
52
53  int safepoint_table_offset = 0;
54  int safepoint_table_size = 0;
55
56  int handler_table_offset = 0;
57  int handler_table_size = 0;
58
59  int constant_pool_offset = 0;
60  int constant_pool_size = 0;
61
62  int code_comments_offset = 0;
63  int code_comments_size = 0;
64
65  // TODO(jgruber,v8:11036): Remove these functions once CodeDesc fields have
66  // been made consistent with Code layout.
67  int body_size() const { return instr_size + unwinding_info_size; }
68  int instruction_size() const { return safepoint_table_offset; }
69  int metadata_size() const { return body_size() - instruction_size(); }
70  int safepoint_table_offset_relative() const {
71    return safepoint_table_offset - instruction_size();
72  }
73  int handler_table_offset_relative() const {
74    return handler_table_offset - instruction_size();
75  }
76  int constant_pool_offset_relative() const {
77    return constant_pool_offset - instruction_size();
78  }
79  int code_comments_offset_relative() const {
80    return code_comments_offset - instruction_size();
81  }
82
83  // Relocation info is located at the end of the buffer and not part of the
84  // instructions area.
85
86  int reloc_offset = 0;
87  int reloc_size = 0;
88
89  // Unwinding information.
90
91  byte* unwinding_info = nullptr;
92  int unwinding_info_size = 0;
93  int unwinding_info_offset_relative() const {
94    // TODO(jgruber,v8:11036): Remove this function once unwinding_info setup
95    // is more consistent with other metadata tables.
96    return code_comments_offset_relative() + code_comments_size;
97  }
98
99  Assembler* origin = nullptr;
100};
101
102}  // namespace internal
103}  // namespace v8
104
105#endif  // V8_CODEGEN_CODE_DESC_H_
106