1 //===- Wasm.h - Wasm object file format -------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file defines manifest constants for the wasm object file format. 10 // See: https://github.com/WebAssembly/design/blob/main/BinaryEncoding.md 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_BINARYFORMAT_WASM_H 15 #define LLVM_BINARYFORMAT_WASM_H 16 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/ADT/SmallVector.h" 19 #include "llvm/ADT/StringRef.h" 20 #include <optional> 21 22 namespace llvm { 23 namespace wasm { 24 25 // Object file magic string. 26 const char WasmMagic[] = {'\0', 'a', 's', 'm'}; 27 // Wasm binary format version 28 const uint32_t WasmVersion = 0x1; 29 // Wasm linking metadata version 30 const uint32_t WasmMetadataVersion = 0x2; 31 // Wasm uses a 64k page size 32 const uint32_t WasmPageSize = 65536; 33 34 struct WasmObjectHeader { 35 StringRef Magic; 36 uint32_t Version; 37 }; 38 39 struct WasmDylinkImportInfo { 40 StringRef Module; 41 StringRef Field; 42 uint32_t Flags; 43 }; 44 45 struct WasmDylinkExportInfo { 46 StringRef Name; 47 uint32_t Flags; 48 }; 49 50 struct WasmDylinkInfo { 51 uint32_t MemorySize; // Memory size in bytes 52 uint32_t MemoryAlignment; // P2 alignment of memory 53 uint32_t TableSize; // Table size in elements 54 uint32_t TableAlignment; // P2 alignment of table 55 std::vector<StringRef> Needed; // Shared library dependencies 56 std::vector<WasmDylinkImportInfo> ImportInfo; 57 std::vector<WasmDylinkExportInfo> ExportInfo; 58 }; 59 60 struct WasmProducerInfo { 61 std::vector<std::pair<std::string, std::string>> Languages; 62 std::vector<std::pair<std::string, std::string>> Tools; 63 std::vector<std::pair<std::string, std::string>> SDKs; 64 }; 65 66 struct WasmFeatureEntry { 67 uint8_t Prefix; 68 std::string Name; 69 }; 70 71 struct WasmExport { 72 StringRef Name; 73 uint8_t Kind; 74 uint32_t Index; 75 }; 76 77 struct WasmLimits { 78 uint8_t Flags; 79 uint64_t Minimum; 80 uint64_t Maximum; 81 }; 82 83 struct WasmTableType { 84 uint8_t ElemType; 85 WasmLimits Limits; 86 }; 87 88 struct WasmTable { 89 uint32_t Index; 90 WasmTableType Type; 91 StringRef SymbolName; // from the "linking" section 92 }; 93 94 struct WasmInitExprMVP { 95 uint8_t Opcode; 96 union { 97 int32_t Int32; 98 int64_t Int64; 99 uint32_t Float32; 100 uint64_t Float64; 101 uint32_t Global; 102 } Value; 103 }; 104 105 struct WasmInitExpr { 106 uint8_t Extended; // Set to non-zero if extended const is used (i.e. more than 107 // one instruction) 108 WasmInitExprMVP Inst; 109 ArrayRef<uint8_t> Body; 110 }; 111 112 struct WasmGlobalType { 113 uint8_t Type; 114 bool Mutable; 115 }; 116 117 struct WasmGlobal { 118 uint32_t Index; 119 WasmGlobalType Type; 120 WasmInitExpr InitExpr; 121 StringRef SymbolName; // from the "linking" section 122 }; 123 124 struct WasmTag { 125 uint32_t Index; 126 uint32_t SigIndex; 127 StringRef SymbolName; // from the "linking" section 128 }; 129 130 struct WasmImport { 131 StringRef Module; 132 StringRef Field; 133 uint8_t Kind; 134 union { 135 uint32_t SigIndex; 136 WasmGlobalType Global; 137 WasmTableType Table; 138 WasmLimits Memory; 139 }; 140 }; 141 142 struct WasmLocalDecl { 143 uint8_t Type; 144 uint32_t Count; 145 }; 146 147 struct WasmFunction { 148 uint32_t Index; 149 uint32_t SigIndex; 150 std::vector<WasmLocalDecl> Locals; 151 ArrayRef<uint8_t> Body; 152 uint32_t CodeSectionOffset; 153 uint32_t Size; 154 uint32_t CodeOffset; // start of Locals and Body 155 std::optional<StringRef> ExportName; // from the "export" section 156 StringRef SymbolName; // from the "linking" section 157 StringRef DebugName; // from the "name" section 158 uint32_t Comdat; // from the "comdat info" section 159 }; 160 161 struct WasmDataSegment { 162 uint32_t InitFlags; 163 // Present if InitFlags & WASM_DATA_SEGMENT_HAS_MEMINDEX. 164 uint32_t MemoryIndex; 165 // Present if InitFlags & WASM_DATA_SEGMENT_IS_PASSIVE == 0. 166 WasmInitExpr Offset; 167 168 ArrayRef<uint8_t> Content; 169 StringRef Name; // from the "segment info" section 170 uint32_t Alignment; 171 uint32_t LinkingFlags; 172 uint32_t Comdat; // from the "comdat info" section 173 }; 174 175 struct WasmElemSegment { 176 uint32_t Flags; 177 uint32_t TableNumber; 178 uint8_t ElemKind; 179 WasmInitExpr Offset; 180 std::vector<uint32_t> Functions; 181 }; 182 183 // Represents the location of a Wasm data symbol within a WasmDataSegment, as 184 // the index of the segment, and the offset and size within the segment. 185 struct WasmDataReference { 186 uint32_t Segment; 187 uint64_t Offset; 188 uint64_t Size; 189 }; 190 191 struct WasmRelocation { 192 uint8_t Type; // The type of the relocation. 193 uint32_t Index; // Index into either symbol or type index space. 194 uint64_t Offset; // Offset from the start of the section. 195 int64_t Addend; // A value to add to the symbol. 196 }; 197 198 struct WasmInitFunc { 199 uint32_t Priority; 200 uint32_t Symbol; 201 }; 202 203 struct WasmSymbolInfo { 204 StringRef Name; 205 uint8_t Kind; 206 uint32_t Flags; 207 // For undefined symbols the module of the import 208 std::optional<StringRef> ImportModule; 209 // For undefined symbols the name of the import 210 std::optional<StringRef> ImportName; 211 // For symbols to be exported from the final module 212 std::optional<StringRef> ExportName; 213 union { 214 // For function, table, or global symbols, the index in function, table, or 215 // global index space. 216 uint32_t ElementIndex; 217 // For a data symbols, the address of the data relative to segment. 218 WasmDataReference DataRef; 219 }; 220 }; 221 222 enum class NameType { 223 FUNCTION, 224 GLOBAL, 225 DATA_SEGMENT, 226 }; 227 228 struct WasmDebugName { 229 NameType Type; 230 uint32_t Index; 231 StringRef Name; 232 }; 233 234 struct WasmLinkingData { 235 uint32_t Version; 236 std::vector<WasmInitFunc> InitFunctions; 237 std::vector<StringRef> Comdats; 238 std::vector<WasmSymbolInfo> SymbolTable; 239 }; 240 241 enum : unsigned { 242 WASM_SEC_CUSTOM = 0, // Custom / User-defined section 243 WASM_SEC_TYPE = 1, // Function signature declarations 244 WASM_SEC_IMPORT = 2, // Import declarations 245 WASM_SEC_FUNCTION = 3, // Function declarations 246 WASM_SEC_TABLE = 4, // Indirect function table and other tables 247 WASM_SEC_MEMORY = 5, // Memory attributes 248 WASM_SEC_GLOBAL = 6, // Global declarations 249 WASM_SEC_EXPORT = 7, // Exports 250 WASM_SEC_START = 8, // Start function declaration 251 WASM_SEC_ELEM = 9, // Elements section 252 WASM_SEC_CODE = 10, // Function bodies (code) 253 WASM_SEC_DATA = 11, // Data segments 254 WASM_SEC_DATACOUNT = 12, // Data segment count 255 WASM_SEC_TAG = 13, // Tag declarations 256 WASM_SEC_LAST_KNOWN = WASM_SEC_TAG, 257 }; 258 259 // Type immediate encodings used in various contexts. 260 enum : unsigned { 261 WASM_TYPE_I32 = 0x7F, 262 WASM_TYPE_I64 = 0x7E, 263 WASM_TYPE_F32 = 0x7D, 264 WASM_TYPE_F64 = 0x7C, 265 WASM_TYPE_V128 = 0x7B, 266 WASM_TYPE_FUNCREF = 0x70, 267 WASM_TYPE_EXTERNREF = 0x6F, 268 WASM_TYPE_FUNC = 0x60, 269 WASM_TYPE_NORESULT = 0x40, // for blocks with no result values 270 }; 271 272 // Kinds of externals (for imports and exports). 273 enum : unsigned { 274 WASM_EXTERNAL_FUNCTION = 0x0, 275 WASM_EXTERNAL_TABLE = 0x1, 276 WASM_EXTERNAL_MEMORY = 0x2, 277 WASM_EXTERNAL_GLOBAL = 0x3, 278 WASM_EXTERNAL_TAG = 0x4, 279 }; 280 281 // Opcodes used in initializer expressions. 282 enum : unsigned { 283 WASM_OPCODE_END = 0x0b, 284 WASM_OPCODE_CALL = 0x10, 285 WASM_OPCODE_LOCAL_GET = 0x20, 286 WASM_OPCODE_LOCAL_SET = 0x21, 287 WASM_OPCODE_LOCAL_TEE = 0x22, 288 WASM_OPCODE_GLOBAL_GET = 0x23, 289 WASM_OPCODE_GLOBAL_SET = 0x24, 290 WASM_OPCODE_I32_STORE = 0x36, 291 WASM_OPCODE_I64_STORE = 0x37, 292 WASM_OPCODE_I32_CONST = 0x41, 293 WASM_OPCODE_I64_CONST = 0x42, 294 WASM_OPCODE_F32_CONST = 0x43, 295 WASM_OPCODE_F64_CONST = 0x44, 296 WASM_OPCODE_I32_ADD = 0x6a, 297 WASM_OPCODE_I32_SUB = 0x6b, 298 WASM_OPCODE_I32_MUL = 0x6c, 299 WASM_OPCODE_I64_ADD = 0x7c, 300 WASM_OPCODE_I64_SUB = 0x7d, 301 WASM_OPCODE_I64_MUL = 0x7e, 302 WASM_OPCODE_REF_NULL = 0xd0, 303 }; 304 305 // Opcodes used in synthetic functions. 306 enum : unsigned { 307 WASM_OPCODE_BLOCK = 0x02, 308 WASM_OPCODE_BR = 0x0c, 309 WASM_OPCODE_BR_TABLE = 0x0e, 310 WASM_OPCODE_RETURN = 0x0f, 311 WASM_OPCODE_DROP = 0x1a, 312 WASM_OPCODE_MISC_PREFIX = 0xfc, 313 WASM_OPCODE_MEMORY_INIT = 0x08, 314 WASM_OPCODE_MEMORY_FILL = 0x0b, 315 WASM_OPCODE_DATA_DROP = 0x09, 316 WASM_OPCODE_ATOMICS_PREFIX = 0xfe, 317 WASM_OPCODE_ATOMIC_NOTIFY = 0x00, 318 WASM_OPCODE_I32_ATOMIC_WAIT = 0x01, 319 WASM_OPCODE_I32_ATOMIC_STORE = 0x17, 320 WASM_OPCODE_I32_RMW_CMPXCHG = 0x48, 321 }; 322 323 enum : unsigned { 324 WASM_LIMITS_FLAG_NONE = 0x0, 325 WASM_LIMITS_FLAG_HAS_MAX = 0x1, 326 WASM_LIMITS_FLAG_IS_SHARED = 0x2, 327 WASM_LIMITS_FLAG_IS_64 = 0x4, 328 }; 329 330 enum : unsigned { 331 WASM_DATA_SEGMENT_IS_PASSIVE = 0x01, 332 WASM_DATA_SEGMENT_HAS_MEMINDEX = 0x02, 333 }; 334 335 enum : unsigned { 336 WASM_ELEM_SEGMENT_IS_PASSIVE = 0x01, 337 WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER = 0x02, 338 WASM_ELEM_SEGMENT_HAS_INIT_EXPRS = 0x04, 339 }; 340 const unsigned WASM_ELEM_SEGMENT_MASK_HAS_ELEM_KIND = 0x3; 341 342 // Feature policy prefixes used in the custom "target_features" section 343 enum : uint8_t { 344 WASM_FEATURE_PREFIX_USED = '+', 345 WASM_FEATURE_PREFIX_REQUIRED = '=', 346 WASM_FEATURE_PREFIX_DISALLOWED = '-', 347 }; 348 349 // Kind codes used in the custom "name" section 350 enum : unsigned { 351 WASM_NAMES_FUNCTION = 1, 352 WASM_NAMES_LOCAL = 2, 353 WASM_NAMES_GLOBAL = 7, 354 WASM_NAMES_DATA_SEGMENT = 9, 355 }; 356 357 // Kind codes used in the custom "linking" section 358 enum : unsigned { 359 WASM_SEGMENT_INFO = 0x5, 360 WASM_INIT_FUNCS = 0x6, 361 WASM_COMDAT_INFO = 0x7, 362 WASM_SYMBOL_TABLE = 0x8, 363 }; 364 365 // Kind codes used in the custom "dylink" section 366 enum : unsigned { 367 WASM_DYLINK_MEM_INFO = 0x1, 368 WASM_DYLINK_NEEDED = 0x2, 369 WASM_DYLINK_EXPORT_INFO = 0x3, 370 WASM_DYLINK_IMPORT_INFO = 0x4, 371 }; 372 373 // Kind codes used in the custom "linking" section in the WASM_COMDAT_INFO 374 enum : unsigned { 375 WASM_COMDAT_DATA = 0x0, 376 WASM_COMDAT_FUNCTION = 0x1, 377 // GLOBAL, TAG, and TABLE are in here but LLVM doesn't use them yet. 378 WASM_COMDAT_SECTION = 0x5, 379 }; 380 381 // Kind codes used in the custom "linking" section in the WASM_SYMBOL_TABLE 382 enum WasmSymbolType : unsigned { 383 WASM_SYMBOL_TYPE_FUNCTION = 0x0, 384 WASM_SYMBOL_TYPE_DATA = 0x1, 385 WASM_SYMBOL_TYPE_GLOBAL = 0x2, 386 WASM_SYMBOL_TYPE_SECTION = 0x3, 387 WASM_SYMBOL_TYPE_TAG = 0x4, 388 WASM_SYMBOL_TYPE_TABLE = 0x5, 389 }; 390 391 enum WasmSegmentFlag : unsigned { 392 WASM_SEG_FLAG_STRINGS = 0x1, 393 WASM_SEG_FLAG_TLS = 0x2, 394 }; 395 396 // Kinds of tag attributes. 397 enum WasmTagAttribute : uint8_t { 398 WASM_TAG_ATTRIBUTE_EXCEPTION = 0x0, 399 }; 400 401 const unsigned WASM_SYMBOL_BINDING_MASK = 0x3; 402 const unsigned WASM_SYMBOL_VISIBILITY_MASK = 0xc; 403 404 const unsigned WASM_SYMBOL_BINDING_GLOBAL = 0x0; 405 const unsigned WASM_SYMBOL_BINDING_WEAK = 0x1; 406 const unsigned WASM_SYMBOL_BINDING_LOCAL = 0x2; 407 const unsigned WASM_SYMBOL_VISIBILITY_DEFAULT = 0x0; 408 const unsigned WASM_SYMBOL_VISIBILITY_HIDDEN = 0x4; 409 const unsigned WASM_SYMBOL_UNDEFINED = 0x10; 410 const unsigned WASM_SYMBOL_EXPORTED = 0x20; 411 const unsigned WASM_SYMBOL_EXPLICIT_NAME = 0x40; 412 const unsigned WASM_SYMBOL_NO_STRIP = 0x80; 413 const unsigned WASM_SYMBOL_TLS = 0x100; 414 415 #define WASM_RELOC(name, value) name = value, 416 417 enum : unsigned { 418 #include "WasmRelocs.def" 419 }; 420 421 #undef WASM_RELOC 422 423 // Subset of types that a value can have 424 enum class ValType { 425 I32 = WASM_TYPE_I32, 426 I64 = WASM_TYPE_I64, 427 F32 = WASM_TYPE_F32, 428 F64 = WASM_TYPE_F64, 429 V128 = WASM_TYPE_V128, 430 FUNCREF = WASM_TYPE_FUNCREF, 431 EXTERNREF = WASM_TYPE_EXTERNREF, 432 }; 433 434 struct WasmSignature { 435 SmallVector<ValType, 1> Returns; 436 SmallVector<ValType, 4> Params; 437 // Support empty and tombstone instances, needed by DenseMap. 438 enum { Plain, Empty, Tombstone } State = Plain; 439 440 WasmSignature(SmallVector<ValType, 1> &&InReturns, 441 SmallVector<ValType, 4> &&InParams) 442 : Returns(InReturns), Params(InParams) {} 443 WasmSignature() = default; 444 }; 445 446 // Useful comparison operators 447 inline bool operator==(const WasmSignature &LHS, const WasmSignature &RHS) { 448 return LHS.State == RHS.State && LHS.Returns == RHS.Returns && 449 LHS.Params == RHS.Params; 450 } 451 452 inline bool operator!=(const WasmSignature &LHS, const WasmSignature &RHS) { 453 return !(LHS == RHS); 454 } 455 456 inline bool operator==(const WasmGlobalType &LHS, const WasmGlobalType &RHS) { 457 return LHS.Type == RHS.Type && LHS.Mutable == RHS.Mutable; 458 } 459 460 inline bool operator!=(const WasmGlobalType &LHS, const WasmGlobalType &RHS) { 461 return !(LHS == RHS); 462 } 463 464 inline bool operator==(const WasmLimits &LHS, const WasmLimits &RHS) { 465 return LHS.Flags == RHS.Flags && LHS.Minimum == RHS.Minimum && 466 (LHS.Flags & WASM_LIMITS_FLAG_HAS_MAX ? LHS.Maximum == RHS.Maximum 467 : true); 468 } 469 470 inline bool operator==(const WasmTableType &LHS, const WasmTableType &RHS) { 471 return LHS.ElemType == RHS.ElemType && LHS.Limits == RHS.Limits; 472 } 473 474 llvm::StringRef toString(WasmSymbolType type); 475 llvm::StringRef relocTypetoString(uint32_t type); 476 llvm::StringRef sectionTypeToString(uint32_t type); 477 bool relocTypeHasAddend(uint32_t type); 478 479 } // end namespace wasm 480 } // end namespace llvm 481 482 #endif 483