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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_SUPPORT_WASM_H
16 : #define LLVM_SUPPORT_WASM_H
17 :
18 : #include "llvm/ADT/ArrayRef.h"
19 :
20 : namespace llvm {
21 : namespace wasm {
22 :
23 : // Object file magic string.
24 : const char WasmMagic[] = {'\0', 'a', 's', 'm'};
25 : // Wasm binary format version
26 : const uint32_t WasmVersion = 0x1;
27 : // Wasm uses a 64k page size
28 : const uint32_t WasmPageSize = 65536;
29 :
30 54 : struct WasmObjectHeader {
31 : StringRef Magic;
32 : uint32_t Version;
33 : };
34 :
35 175 : struct WasmSignature {
36 : std::vector<int32_t> ParamTypes;
37 : int32_t ReturnType;
38 : };
39 :
40 36 : struct WasmExport {
41 : StringRef Name;
42 : uint32_t Kind;
43 : uint32_t Index;
44 : };
45 :
46 : struct WasmLimits {
47 : uint32_t Flags;
48 : uint32_t Initial;
49 : uint32_t Maximum;
50 : };
51 :
52 : struct WasmTable {
53 : int32_t ElemType;
54 : WasmLimits Limits;
55 : };
56 :
57 : struct 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 :
68 : struct WasmGlobal {
69 : int32_t Type;
70 : bool Mutable;
71 : WasmInitExpr InitExpr;
72 : };
73 :
74 63 : struct 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 :
86 : struct WasmLocalDecl {
87 : int32_t Type;
88 : uint32_t Count;
89 : };
90 :
91 132 : struct WasmFunction {
92 : std::vector<WasmLocalDecl> Locals;
93 : ArrayRef<uint8_t> Body;
94 : };
95 :
96 2 : struct WasmDataSegment {
97 : uint32_t Index;
98 : WasmInitExpr Offset;
99 : ArrayRef<uint8_t> Content;
100 : };
101 :
102 70 : struct WasmElemSegment {
103 : uint32_t TableIndex;
104 : WasmInitExpr Offset;
105 : std::vector<uint32_t> Functions;
106 : };
107 :
108 : struct 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 :
115 : enum : 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.
131 : enum {
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).
142 : enum : 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.
150 : enum : 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 :
159 : enum : unsigned {
160 : WASM_NAMES_FUNCTION = 0x1,
161 : WASM_NAMES_LOCAL = 0x2,
162 : };
163 :
164 : enum : unsigned {
165 : WASM_LIMITS_FLAG_HAS_MAX = 0x1,
166 : };
167 :
168 : // Subset of types that a value can have
169 : enum 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.
177 : enum : unsigned {
178 : WASM_STACK_POINTER = 0x1,
179 : };
180 :
181 : #define WASM_RELOC(name, value) name = value,
182 :
183 : enum : unsigned {
184 : #include "WasmRelocs/WebAssembly.def"
185 : };
186 :
187 : #undef WASM_RELOC
188 :
189 : struct 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
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