1//===- Wasm.h - Wasm object file format -------------------------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file defines manifest constants for the wasm object file format.
11// See: https://github.com/WebAssembly/design/blob/master/BinaryEncoding.md
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef LLVM_BINARYFORMAT_WASM_H
16#define LLVM_BINARYFORMAT_WASM_H
17
18#include "llvm/ADT/ArrayRef.h"
19
20namespace llvm {
21namespace wasm {
22
23// Object file magic string.
24const char WasmMagic[] = {'\0', 'a', 's', 'm'};
25// Wasm binary format version
26const uint32_t WasmVersion = 0x1;
27// Wasm uses a 64k page size
28const uint32_t WasmPageSize = 65536;
29
30struct WasmObjectHeader {
31  StringRef Magic;
32  uint32_t Version;
33};
34
35struct WasmSignature {
36  std::vector<int32_t> ParamTypes;
37  int32_t ReturnType;
38};
39
40struct WasmExport {
41  StringRef Name;
42  uint32_t Kind;
43  uint32_t Index;
44};
45
46struct WasmLimits {
47  uint32_t Flags;
48  uint32_t Initial;
49  uint32_t Maximum;
50};
51
52struct WasmTable {
53  int32_t ElemType;
54  WasmLimits Limits;
55};
56
57struct WasmInitExpr {
58  uint8_t Opcode;
59  union {
60    int32_t Int32;
61    int64_t Int64;
62    int32_t Float32;
63    int64_t Float64;
64    uint32_t Global;
65  } Value;
66};
67
68struct WasmGlobal {
69  int32_t Type;
70  bool Mutable;
71  WasmInitExpr InitExpr;
72};
73
74struct WasmImport {
75  StringRef Module;
76  StringRef Field;
77  uint32_t Kind;
78  union {
79    uint32_t SigIndex;
80    WasmGlobal Global;
81    WasmTable Table;
82    WasmLimits Memory;
83  };
84};
85
86struct WasmLocalDecl {
87  int32_t Type;
88  uint32_t Count;
89};
90
91struct WasmFunction {
92  std::vector<WasmLocalDecl> Locals;
93  ArrayRef<uint8_t> Body;
94};
95
96struct WasmDataSegment {
97  uint32_t Index;
98  WasmInitExpr Offset;
99  ArrayRef<uint8_t> Content;
100};
101
102struct WasmElemSegment {
103  uint32_t TableIndex;
104  WasmInitExpr Offset;
105  std::vector<uint32_t> Functions;
106};
107
108struct WasmRelocation {
109  uint32_t Type;   // The type of the relocation.
110  int32_t Index;   // Index into function to global index space.
111  uint64_t Offset; // Offset from the start of the section.
112  int64_t Addend;  // A value to add to the symbol.
113};
114
115enum : unsigned {
116  WASM_SEC_CUSTOM = 0,   // Custom / User-defined section
117  WASM_SEC_TYPE = 1,     // Function signature declarations
118  WASM_SEC_IMPORT = 2,   // Import declarations
119  WASM_SEC_FUNCTION = 3, // Function declarations
120  WASM_SEC_TABLE = 4,    // Indirect function table and other tables
121  WASM_SEC_MEMORY = 5,   // Memory attributes
122  WASM_SEC_GLOBAL = 6,   // Global declarations
123  WASM_SEC_EXPORT = 7,   // Exports
124  WASM_SEC_START = 8,    // Start function declaration
125  WASM_SEC_ELEM = 9,     // Elements section
126  WASM_SEC_CODE = 10,    // Function bodies (code)
127  WASM_SEC_DATA = 11     // Data segments
128};
129
130// Type immediate encodings used in various contexts.
131enum {
132  WASM_TYPE_I32 = -0x01,
133  WASM_TYPE_I64 = -0x02,
134  WASM_TYPE_F32 = -0x03,
135  WASM_TYPE_F64 = -0x04,
136  WASM_TYPE_ANYFUNC = -0x10,
137  WASM_TYPE_FUNC = -0x20,
138  WASM_TYPE_NORESULT = -0x40, // for blocks with no result values
139};
140
141// Kinds of externals (for imports and exports).
142enum : unsigned {
143  WASM_EXTERNAL_FUNCTION = 0x0,
144  WASM_EXTERNAL_TABLE = 0x1,
145  WASM_EXTERNAL_MEMORY = 0x2,
146  WASM_EXTERNAL_GLOBAL = 0x3,
147};
148
149// Opcodes used in initializer expressions.
150enum : unsigned {
151  WASM_OPCODE_END = 0x0b,
152  WASM_OPCODE_GET_GLOBAL = 0x23,
153  WASM_OPCODE_I32_CONST = 0x41,
154  WASM_OPCODE_I64_CONST = 0x42,
155  WASM_OPCODE_F32_CONST = 0x43,
156  WASM_OPCODE_F64_CONST = 0x44,
157};
158
159enum : unsigned {
160  WASM_NAMES_FUNCTION = 0x1,
161  WASM_NAMES_LOCAL = 0x2,
162};
163
164enum : unsigned {
165  WASM_LIMITS_FLAG_HAS_MAX = 0x1,
166};
167
168// Subset of types that a value can have
169enum class ValType {
170  I32 = WASM_TYPE_I32,
171  I64 = WASM_TYPE_I64,
172  F32 = WASM_TYPE_F32,
173  F64 = WASM_TYPE_F64,
174};
175
176// Linking metadata kinds.
177enum : unsigned {
178  WASM_STACK_POINTER = 0x1,
179};
180
181#define WASM_RELOC(name, value) name = value,
182
183enum : unsigned {
184#include "WasmRelocs/WebAssembly.def"
185};
186
187#undef WASM_RELOC
188
189struct Global {
190  ValType Type;
191  bool Mutable;
192
193  // The initial value for this global is either the value of an imported
194  // global, in which case InitialModule and InitialName specify the global
195  // import, or a value, in which case InitialModule is empty and InitialValue
196  // holds the value.
197  StringRef InitialModule;
198  StringRef InitialName;
199  uint64_t InitialValue;
200};
201
202} // end namespace wasm
203} // end namespace llvm
204
205#endif
206