lib/Object/WasmObjectFile.cpp

   1 //===- WasmObjectFile.cpp - Wasm object file implementation ---------------===//
   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 #include "llvm/ADT/ArrayRef.h"
  11 #include "llvm/ADT/STLExtras.h"
  12 #include "llvm/ADT/StringRef.h"
  13 #include "llvm/ADT/Triple.h"
  14 #include "llvm/BinaryFormat/Wasm.h"
  15 #include "llvm/MC/SubtargetFeature.h"
  16 #include "llvm/Object/Binary.h"
  17 #include "llvm/Object/Error.h"
  18 #include "llvm/Object/ObjectFile.h"
  19 #include "llvm/Object/SymbolicFile.h"
  20 #include "llvm/Object/Wasm.h"
  21 #include "llvm/Support/Endian.h"
  22 #include "llvm/Support/Error.h"
  23 #include "llvm/Support/ErrorHandling.h"
  24 #include "llvm/Support/LEB128.h"
  25 #include <algorithm>
  26 #include <cassert>
  27 #include <cstdint>
  28 #include <cstring>
  29 #include <system_error>
  30
  31 #define DEBUG_TYPE "wasm-object"
  32
  33 using namespace llvm;
  34 using namespace object;
  35
  36 Expected<std::unique_ptr<WasmObjectFile>>
  37 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
  38   Error Err = Error::success();
  39   auto ObjectFile = llvm::make_unique<WasmObjectFile>(Buffer, Err);
  40   if (Err)
  41     return std::move(Err);
  42
  43   return std::move(ObjectFile);
  44 }
  45
  46 #define VARINT7_MAX ((1<<7)-1)
  47 #define VARINT7_MIN (-(1<<7))
  48 #define VARUINT7_MAX (1<<7)
  49 #define VARUINT1_MAX (1)
  50
  51 static uint8_t readUint8(const uint8_t *&Ptr) { return *Ptr++; }
  52
  53 static uint32_t readUint32(const uint8_t *&Ptr) {
  54   uint32_t Result = support::endian::read32le(Ptr);
  55   Ptr += sizeof(Result);
  56   return Result;
  57 }
  58
  59 static int32_t readFloat32(const uint8_t *&Ptr) {
  60   int32_t Result = 0;
  61   memcpy(&Result, Ptr, sizeof(Result));
  62   Ptr += sizeof(Result);
  63   return Result;
  64 }
  65
  66 static int64_t readFloat64(const uint8_t *&Ptr) {
  67   int64_t Result = 0;
  68   memcpy(&Result, Ptr, sizeof(Result));
  69   Ptr += sizeof(Result);
  70   return Result;
  71 }
  72
  73 static uint64_t readULEB128(const uint8_t *&Ptr) {
  74   unsigned Count;
  75   uint64_t Result = decodeULEB128(Ptr, &Count);
  76   Ptr += Count;
  77   return Result;
  78 }
  79
  80 static StringRef readString(const uint8_t *&Ptr) {
  81   uint32_t StringLen = readULEB128(Ptr);
  82   StringRef Return = StringRef(reinterpret_cast<const char *>(Ptr), StringLen);
  83   Ptr += StringLen;
  84   return Return;
  85 }
  86
  87 static int64_t readLEB128(const uint8_t *&Ptr) {
  88   unsigned Count;
  89   uint64_t Result = decodeSLEB128(Ptr, &Count);
  90   Ptr += Count;
  91   return Result;
  92 }
  93
  94 static uint8_t readVaruint1(const uint8_t *&Ptr) {
  95   int64_t result = readLEB128(Ptr);
  96   assert(result <= VARUINT1_MAX && result >= 0);
  97   return result;
  98 }
  99
 100 static int8_t readVarint7(const uint8_t *&Ptr) {
 101   int64_t result = readLEB128(Ptr);
 102   assert(result <= VARINT7_MAX && result >= VARINT7_MIN);
 103   return result;
 104 }
 105
 106 static uint8_t readVaruint7(const uint8_t *&Ptr) {
 107   uint64_t result = readULEB128(Ptr);
 108   assert(result <= VARUINT7_MAX);
 109   return result;
 110 }
 111
 112 static int32_t readVarint32(const uint8_t *&Ptr) {
 113   int64_t result = readLEB128(Ptr);
 114   assert(result <= INT32_MAX && result >= INT32_MIN);
 115   return result;
 116 }
 117
 118 static uint32_t readVaruint32(const uint8_t *&Ptr) {
 119   uint64_t result = readULEB128(Ptr);
 120   assert(result <= UINT32_MAX);
 121   return result;
 122 }
 123
 124 static int64_t readVarint64(const uint8_t *&Ptr) {
 125   return readLEB128(Ptr);
 126 }
 127
 128 static uint8_t readOpcode(const uint8_t *&Ptr) {
 129   return readUint8(Ptr);
 130 }
 131
 132 static Error readInitExpr(wasm::WasmInitExpr &Expr, const uint8_t *&Ptr) {
 133   Expr.Opcode = readOpcode(Ptr);
 134
 135   switch (Expr.Opcode) {
 136   case wasm::WASM_OPCODE_I32_CONST:
 137     Expr.Value.Int32 = readVarint32(Ptr);
 138     break;
 139   case wasm::WASM_OPCODE_I64_CONST:
 140     Expr.Value.Int64 = readVarint64(Ptr);
 141     break;
 142   case wasm::WASM_OPCODE_F32_CONST:
 143     Expr.Value.Float32 = readFloat32(Ptr);
 144     break;
 145   case wasm::WASM_OPCODE_F64_CONST:
 146     Expr.Value.Float64 = readFloat64(Ptr);
 147     break;
 148   case wasm::WASM_OPCODE_GET_GLOBAL:
 149     Expr.Value.Global = readULEB128(Ptr);
 150     break;
 151   default:
 152     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
 153                                           object_error::parse_failed);
 154   }
 155
 156   uint8_t EndOpcode = readOpcode(Ptr);
 157   if (EndOpcode != wasm::WASM_OPCODE_END) {
 158     return make_error<GenericBinaryError>("Invalid init_expr",
 159                                           object_error::parse_failed);
 160   }
 161   return Error::success();
 162 }
 163
 164 static wasm::WasmLimits readLimits(const uint8_t *&Ptr) {
 165   wasm::WasmLimits Result;
 166   Result.Flags = readVaruint1(Ptr);
 167   Result.Initial = readVaruint32(Ptr);
 168   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
 169     Result.Maximum = readVaruint32(Ptr);
 170   return Result;
 171 }
 172
 173 static wasm::WasmTable readTable(const uint8_t *&Ptr) {
 174   wasm::WasmTable Table;
 175   Table.ElemType = readVarint7(Ptr);
 176   Table.Limits = readLimits(Ptr);
 177   return Table;
 178 }
 179
 180 static Error readSection(WasmSection &Section, const uint8_t *&Ptr,
 181                          const uint8_t *Start, const uint8_t *Eof) {
 182   Section.Offset = Ptr - Start;
 183   Section.Type = readVaruint7(Ptr);
 184   uint32_t Size = readVaruint32(Ptr);
 185   if (Size == 0)
 186     return make_error<StringError>("Zero length section",
 187                                    object_error::parse_failed);
 188   if (Ptr + Size > Eof)
 189     return make_error<StringError>("Section too large",
 190                                    object_error::parse_failed);
 191   Section.Content = ArrayRef<uint8_t>(Ptr, Size);
 192   Ptr += Size;
 193   return Error::success();
 194 }
 195
 196 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
 197     : ObjectFile(Binary::ID_Wasm, Buffer) {
 198   LinkingData.DataSize = 0;
 199
 200   ErrorAsOutParameter ErrAsOutParam(&Err);
 201   Header.Magic = getData().substr(0, 4);
 202   if (Header.Magic != StringRef("\0asm", 4)) {
 203     Err = make_error<StringError>("Bad magic number",
 204                                   object_error::parse_failed);
 205     return;
 206   }
 207
 208   const uint8_t *Eof = getPtr(getData().size());
 209   const uint8_t *Ptr = getPtr(4);
 210
 211   if (Ptr + 4 > Eof) {
 212     Err = make_error<StringError>("Missing version number",
 213                                   object_error::parse_failed);
 214     return;
 215   }
 216
 217   Header.Version = readUint32(Ptr);
 218   if (Header.Version != wasm::WasmVersion) {
 219     Err = make_error<StringError>("Bad version number",
 220                                   object_error::parse_failed);
 221     return;
 222   }
 223
 224   WasmSection Sec;
 225   while (Ptr < Eof) {
 226     if ((Err = readSection(Sec, Ptr, getPtr(0), Eof)))
 227       return;
 228     if ((Err = parseSection(Sec)))
 229       return;
 230
 231     Sections.push_back(Sec);
 232   }
 233 }
 234
 235 Error WasmObjectFile::parseSection(WasmSection &Sec) {
 236   const uint8_t* Start = Sec.Content.data();
 237   const uint8_t* End = Start + Sec.Content.size();
 238   switch (Sec.Type) {
 239   case wasm::WASM_SEC_CUSTOM:
 240     return parseCustomSection(Sec, Start, End);
 241   case wasm::WASM_SEC_TYPE:
 242     return parseTypeSection(Start, End);
 243   case wasm::WASM_SEC_IMPORT:
 244     return parseImportSection(Start, End);
 245   case wasm::WASM_SEC_FUNCTION:
 246     return parseFunctionSection(Start, End);
 247   case wasm::WASM_SEC_TABLE:
 248     return parseTableSection(Start, End);
 249   case wasm::WASM_SEC_MEMORY:
 250     return parseMemorySection(Start, End);
 251   case wasm::WASM_SEC_GLOBAL:
 252     return parseGlobalSection(Start, End);
 253   case wasm::WASM_SEC_EXPORT:
 254     return parseExportSection(Start, End);
 255   case wasm::WASM_SEC_START:
 256     return parseStartSection(Start, End);
 257   case wasm::WASM_SEC_ELEM:
 258     return parseElemSection(Start, End);
 259   case wasm::WASM_SEC_CODE:
 260     return parseCodeSection(Start, End);
 261   case wasm::WASM_SEC_DATA:
 262     return parseDataSection(Start, End);
 263   default:
 264     return make_error<GenericBinaryError>("Bad section type",
 265                                           object_error::parse_failed);
 266   }
 267 }
 268
 269 Error WasmObjectFile::parseNameSection(const uint8_t *Ptr, const uint8_t *End) {
 270   while (Ptr < End) {
 271     uint8_t Type = readVarint7(Ptr);
 272     uint32_t Size = readVaruint32(Ptr);
 273     const uint8_t *SubSectionEnd = Ptr + Size;
 274     switch (Type) {
 275     case wasm::WASM_NAMES_FUNCTION: {
 276       uint32_t Count = readVaruint32(Ptr);
 277       while (Count--) {
 278         uint32_t Index = readVaruint32(Ptr);
 279         StringRef Name = readString(Ptr);
 280         if (!Name.empty())
 281           Symbols.emplace_back(Name,
 282                                WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME,
 283                                Sections.size(), Index);
 284       }
 285       break;
 286     }
 287     // Ignore local names for now
 288     case wasm::WASM_NAMES_LOCAL:
 289     default:
 290       Ptr += Size;
 291       break;
 292     }
 293     if (Ptr != SubSectionEnd)
 294       return make_error<GenericBinaryError>("Name sub-section ended prematurely",
 295                                             object_error::parse_failed);
 296   }
 297
 298   if (Ptr != End)
 299     return make_error<GenericBinaryError>("Name section ended prematurely",
 300                                           object_error::parse_failed);
 301   return Error::success();
 302 }
 303
 304 void WasmObjectFile::populateSymbolTable() {
 305   // Add imports to symbol table
 306   size_t ImportIndex = 0;
 307   size_t GlobalIndex = 0;
 308   size_t FunctionIndex = 0;
 309   for (const wasm::WasmImport& Import : Imports) {
 310     switch (Import.Kind) {
 311     case wasm::WASM_EXTERNAL_GLOBAL:
 312       assert(Import.Global.Type == wasm::WASM_TYPE_I32);
 313       SymbolMap.try_emplace(Import.Field, Symbols.size());
 314       Symbols.emplace_back(Import.Field, WasmSymbol::SymbolType::GLOBAL_IMPORT,
 315                            ImportSection, GlobalIndex++, ImportIndex);
 316       DEBUG(dbgs() << "Adding import: " << Symbols.back()
 317                    << " sym index:" << Symbols.size() << "\n");
 318       break;
 319     case wasm::WASM_EXTERNAL_FUNCTION:
 320       SymbolMap.try_emplace(Import.Field, Symbols.size());
 321       Symbols.emplace_back(Import.Field,
 322                            WasmSymbol::SymbolType::FUNCTION_IMPORT,
 323                            ImportSection, FunctionIndex++, ImportIndex);
 324       DEBUG(dbgs() << "Adding import: " << Symbols.back()
 325                    << " sym index:" << Symbols.size() << "\n");
 326       break;
 327     default:
 328       break;
 329     }
 330     ImportIndex++;
 331   }
 332
 333   // Add exports to symbol table
 334   for (const wasm::WasmExport& Export : Exports) {
 335     if (Export.Kind == wasm::WASM_EXTERNAL_FUNCTION ||
 336         Export.Kind == wasm::WASM_EXTERNAL_GLOBAL) {
 337       WasmSymbol::SymbolType ExportType =
 338           Export.Kind == wasm::WASM_EXTERNAL_FUNCTION
 339               ? WasmSymbol::SymbolType::FUNCTION_EXPORT
 340               : WasmSymbol::SymbolType::GLOBAL_EXPORT;
 341       SymbolMap.try_emplace(Export.Name, Symbols.size());
 342       Symbols.emplace_back(Export.Name, ExportType,
 343                            ExportSection, Export.Index);
 344       DEBUG(dbgs() << "Adding export: " << Symbols.back()
 345                    << " sym index:" << Symbols.size() << "\n");
 346     }
 347   }
 348 }
 349
 350 Error WasmObjectFile::parseLinkingSection(const uint8_t *Ptr,
 351                                           const uint8_t *End) {
 352   HasLinkingSection = true;
 353
 354   // Only populate the symbol table with imports and exports if the object
 355   // has a linking section (i.e. its a relocatable object file). Otherwise
 356   // the global might not represent symbols at all.
 357   populateSymbolTable();
 358
 359   while (Ptr < End) {
 360     uint8_t Type = readVarint7(Ptr);
 361     uint32_t Size = readVaruint32(Ptr);
 362     const uint8_t *SubSectionEnd = Ptr + Size;
 363     switch (Type) {
 364     case wasm::WASM_SYMBOL_INFO: {
 365       uint32_t Count = readVaruint32(Ptr);
 366       while (Count--) {
 367         StringRef Symbol = readString(Ptr);
 368         DEBUG(dbgs() << "reading syminfo: " << Symbol << "\n");
 369         uint32_t Flags = readVaruint32(Ptr);
 370         auto iter = SymbolMap.find(Symbol);
 371         if (iter == SymbolMap.end()) {
 372           return make_error<GenericBinaryError>(
 373               "Invalid symbol name in linking section: " + Symbol,
 374               object_error::parse_failed);
 375         }
 376         uint32_t SymIndex = iter->second;
 377         assert(SymIndex < Symbols.size());
 378         Symbols[SymIndex].Flags = Flags;
 379         DEBUG(dbgs() << "Set symbol flags index:"
 380                      << SymIndex << " name:"
 381                      << Symbols[SymIndex].Name << " expected:"
 382                      << Symbol << " flags: " << Flags << "\n");
 383       }
 384       break;
 385     }
 386     case wasm::WASM_DATA_SIZE:
 387       LinkingData.DataSize = readVaruint32(Ptr);
 388       break;
 389     case wasm::WASM_SEGMENT_INFO: {
 390       uint32_t Count = readVaruint32(Ptr);
 391       if (Count > DataSegments.size())
 392         return make_error<GenericBinaryError>("Too many segment names",
 393                                               object_error::parse_failed);
 394       for (uint32_t i = 0; i < Count; i++) {
 395         DataSegments[i].Data.Name = readString(Ptr);
 396         DataSegments[i].Data.Alignment = readVaruint32(Ptr);
 397         DataSegments[i].Data.Flags = readVaruint32(Ptr);
 398       }
 399       break;
 400     }
 401     case wasm::WASM_INIT_FUNCS: {
 402       uint32_t Count = readVaruint32(Ptr);
 403       LinkingData.InitFunctions.reserve(Count);
 404       for (uint32_t i = 0; i < Count; i++) {
 405         wasm::WasmInitFunc Init;
 406         Init.Priority = readVaruint32(Ptr);
 407         Init.FunctionIndex = readVaruint32(Ptr);
 408         if (!isValidFunctionIndex(Init.FunctionIndex))
 409           return make_error<GenericBinaryError>("Invalid function index: " +
 410                                                     Twine(Init.FunctionIndex),
 411                                                 object_error::parse_failed);
 412         LinkingData.InitFunctions.emplace_back(Init);
 413       }
 414       break;
 415     }
 416     default:
 417       Ptr += Size;
 418       break;
 419     }
 420     if (Ptr != SubSectionEnd)
 421       return make_error<GenericBinaryError>(
 422           "Linking sub-section ended prematurely", object_error::parse_failed);
 423   }
 424   if (Ptr != End)
 425     return make_error<GenericBinaryError>("Linking section ended prematurely",
 426                                           object_error::parse_failed);
 427   return Error::success();
 428 }
 429
 430 WasmSection* WasmObjectFile::findCustomSectionByName(StringRef Name) {
 431   for (WasmSection& Section : Sections) {
 432     if (Section.Type == wasm::WASM_SEC_CUSTOM && Section.Name == Name)
 433       return &Section;
 434   }
 435   return nullptr;
 436 }
 437
 438 WasmSection* WasmObjectFile::findSectionByType(uint32_t Type) {
 439   assert(Type != wasm::WASM_SEC_CUSTOM);
 440   for (WasmSection& Section : Sections) {
 441     if (Section.Type == Type)
 442       return &Section;
 443   }
 444   return nullptr;
 445 }
 446
 447 Error WasmObjectFile::parseRelocSection(StringRef Name, const uint8_t *Ptr,
 448                                         const uint8_t *End) {
 449   uint8_t SectionCode = readVarint7(Ptr);
 450   WasmSection* Section = nullptr;
 451   if (SectionCode == wasm::WASM_SEC_CUSTOM) {
 452     StringRef Name = readString(Ptr);
 453     Section = findCustomSectionByName(Name);
 454   } else {
 455     Section = findSectionByType(SectionCode);
 456   }
 457   if (!Section)
 458     return make_error<GenericBinaryError>("Invalid section code",
 459                                           object_error::parse_failed);
 460   uint32_t RelocCount = readVaruint32(Ptr);
 461   while (RelocCount--) {
 462     wasm::WasmRelocation Reloc;
 463     memset(&Reloc, 0, sizeof(Reloc));
 464     Reloc.Type = readVaruint32(Ptr);
 465     Reloc.Offset = readVaruint32(Ptr);
 466     Reloc.Index = readVaruint32(Ptr);
 467     switch (Reloc.Type) {
 468     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
 469     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
 470     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
 471     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
 472     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
 473       break;
 474     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
 475     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
 476     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
 477       Reloc.Addend = readVarint32(Ptr);
 478       break;
 479     default:
 480       return make_error<GenericBinaryError>("Bad relocation type: " +
 481                                                 Twine(Reloc.Type),
 482                                             object_error::parse_failed);
 483     }
 484     Section->Relocations.push_back(Reloc);
 485   }
 486   if (Ptr != End)
 487     return make_error<GenericBinaryError>("Reloc section ended prematurely",
 488                                           object_error::parse_failed);
 489   return Error::success();
 490 }
 491
 492 Error WasmObjectFile::parseCustomSection(WasmSection &Sec,
 493                                          const uint8_t *Ptr, const uint8_t *End) {
 494   Sec.Name = readString(Ptr);
 495   if (Sec.Name == "name") {
 496     if (Error Err = parseNameSection(Ptr, End))
 497       return Err;
 498   } else if (Sec.Name == "linking") {
 499     if (Error Err = parseLinkingSection(Ptr, End))
 500       return Err;
 501   } else if (Sec.Name.startswith("reloc.")) {
 502     if (Error Err = parseRelocSection(Sec.Name, Ptr, End))
 503       return Err;
 504   }
 505   return Error::success();
 506 }
 507
 508 Error WasmObjectFile::parseTypeSection(const uint8_t *Ptr, const uint8_t *End) {
 509   uint32_t Count = readVaruint32(Ptr);
 510   Signatures.reserve(Count);
 511   while (Count--) {
 512     wasm::WasmSignature Sig;
 513     Sig.ReturnType = wasm::WASM_TYPE_NORESULT;
 514     int8_t Form = readVarint7(Ptr);
 515     if (Form != wasm::WASM_TYPE_FUNC) {
 516       return make_error<GenericBinaryError>("Invalid signature type",
 517                                             object_error::parse_failed);
 518     }
 519     uint32_t ParamCount = readVaruint32(Ptr);
 520     Sig.ParamTypes.reserve(ParamCount);
 521     while (ParamCount--) {
 522       uint32_t ParamType = readVarint7(Ptr);
 523       Sig.ParamTypes.push_back(ParamType);
 524     }
 525     uint32_t ReturnCount = readVaruint32(Ptr);
 526     if (ReturnCount) {
 527       if (ReturnCount != 1) {
 528         return make_error<GenericBinaryError>(
 529             "Multiple return types not supported", object_error::parse_failed);
 530       }
 531       Sig.ReturnType = readVarint7(Ptr);
 532     }
 533     Signatures.push_back(Sig);
 534   }
 535   if (Ptr != End)
 536     return make_error<GenericBinaryError>("Type section ended prematurely",
 537                                           object_error::parse_failed);
 538   return Error::success();
 539 }
 540
 541 Error WasmObjectFile::parseImportSection(const uint8_t *Ptr, const uint8_t *End) {
 542   ImportSection = Sections.size();
 543   uint32_t Count = readVaruint32(Ptr);
 544   Imports.reserve(Count);
 545   for (uint32_t i = 0; i < Count; i++) {
 546     wasm::WasmImport Im;
 547     Im.Module = readString(Ptr);
 548     Im.Field = readString(Ptr);
 549     Im.Kind = readUint8(Ptr);
 550     switch (Im.Kind) {
 551     case wasm::WASM_EXTERNAL_FUNCTION:
 552       NumImportedFunctions++;
 553       Im.SigIndex = readVaruint32(Ptr);
 554       break;
 555     case wasm::WASM_EXTERNAL_GLOBAL:
 556       NumImportedGlobals++;
 557       Im.Global.Type = readVarint7(Ptr);
 558       Im.Global.Mutable = readVaruint1(Ptr);
 559       break;
 560     case wasm::WASM_EXTERNAL_MEMORY:
 561       Im.Memory = readLimits(Ptr);
 562       break;
 563     case wasm::WASM_EXTERNAL_TABLE:
 564       Im.Table = readTable(Ptr);
 565       if (Im.Table.ElemType != wasm::WASM_TYPE_ANYFUNC)
 566         return make_error<GenericBinaryError>("Invalid table element type",
 567                                               object_error::parse_failed);
 568       break;
 569     default:
 570       return make_error<GenericBinaryError>(
 571           "Unexpected import kind", object_error::parse_failed);
 572     }
 573     Imports.push_back(Im);
 574   }
 575   if (Ptr != End)
 576     return make_error<GenericBinaryError>("Import section ended prematurely",
 577                                           object_error::parse_failed);
 578   return Error::success();
 579 }
 580
 581 Error WasmObjectFile::parseFunctionSection(const uint8_t *Ptr, const uint8_t *End) {
 582   uint32_t Count = readVaruint32(Ptr);
 583   FunctionTypes.reserve(Count);
 584   while (Count--) {
 585     FunctionTypes.push_back(readVaruint32(Ptr));
 586   }
 587   if (Ptr != End)
 588     return make_error<GenericBinaryError>("Function section ended prematurely",
 589                                           object_error::parse_failed);
 590   return Error::success();
 591 }
 592
 593 Error WasmObjectFile::parseTableSection(const uint8_t *Ptr, const uint8_t *End) {
 594   uint32_t Count = readVaruint32(Ptr);
 595   Tables.reserve(Count);
 596   while (Count--) {
 597     Tables.push_back(readTable(Ptr));
 598     if (Tables.back().ElemType != wasm::WASM_TYPE_ANYFUNC) {
 599       return make_error<GenericBinaryError>("Invalid table element type",
 600                                             object_error::parse_failed);
 601     }
 602   }
 603   if (Ptr != End)
 604     return make_error<GenericBinaryError>("Table section ended prematurely",
 605                                           object_error::parse_failed);
 606   return Error::success();
 607 }
 608
 609 Error WasmObjectFile::parseMemorySection(const uint8_t *Ptr, const uint8_t *End) {
 610   uint32_t Count = readVaruint32(Ptr);
 611   Memories.reserve(Count);
 612   while (Count--) {
 613     Memories.push_back(readLimits(Ptr));
 614   }
 615   if (Ptr != End)
 616     return make_error<GenericBinaryError>("Memory section ended prematurely",
 617                                           object_error::parse_failed);
 618   return Error::success();
 619 }
 620
 621 Error WasmObjectFile::parseGlobalSection(const uint8_t *Ptr, const uint8_t *End) {
 622   uint32_t Count = readVaruint32(Ptr);
 623   Globals.reserve(Count);
 624   while (Count--) {
 625     wasm::WasmGlobal Global;
 626     Global.Type = readVarint7(Ptr);
 627     Global.Mutable = readVaruint1(Ptr);
 628     if (Error Err = readInitExpr(Global.InitExpr, Ptr))
 629       return Err;
 630     Globals.push_back(Global);
 631   }
 632   if (Ptr != End)
 633     return make_error<GenericBinaryError>("Global section ended prematurely",
 634                                           object_error::parse_failed);
 635   return Error::success();
 636 }
 637
 638 Error WasmObjectFile::parseExportSection(const uint8_t *Ptr, const uint8_t *End) {
 639   ExportSection = Sections.size();
 640   uint32_t Count = readVaruint32(Ptr);
 641   Exports.reserve(Count);
 642   for (uint32_t i = 0; i < Count; i++) {
 643     wasm::WasmExport Ex;
 644     Ex.Name = readString(Ptr);
 645     Ex.Kind = readUint8(Ptr);
 646     Ex.Index = readVaruint32(Ptr);
 647     switch (Ex.Kind) {
 648     case wasm::WASM_EXTERNAL_FUNCTION:
 649       if (Ex.Index >= FunctionTypes.size() + NumImportedFunctions)
 650         return make_error<GenericBinaryError>("Invalid function export",
 651                                               object_error::parse_failed);
 652       break;
 653     case wasm::WASM_EXTERNAL_GLOBAL: {
 654       if (Ex.Index >= Globals.size() + NumImportedGlobals)
 655         return make_error<GenericBinaryError>("Invalid global export",
 656                                               object_error::parse_failed);
 657       break;
 658     }
 659     case wasm::WASM_EXTERNAL_MEMORY:
 660     case wasm::WASM_EXTERNAL_TABLE:
 661       break;
 662     default:
 663       return make_error<GenericBinaryError>(
 664           "Unexpected export kind", object_error::parse_failed);
 665     }
 666     Exports.push_back(Ex);
 667   }
 668   if (Ptr != End)
 669     return make_error<GenericBinaryError>("Export section ended prematurely",
 670                                           object_error::parse_failed);
 671   return Error::success();
 672 }
 673
 674 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
 675   return Index < FunctionTypes.size() + NumImportedFunctions;
 676 }
 677
 678 Error WasmObjectFile::parseStartSection(const uint8_t *Ptr, const uint8_t *End) {
 679   StartFunction = readVaruint32(Ptr);
 680   if (!isValidFunctionIndex(StartFunction))
 681     return make_error<GenericBinaryError>("Invalid start function",
 682                                           object_error::parse_failed);
 683   return Error::success();
 684 }
 685
 686 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
 687   uint32_t FunctionCount = readVaruint32(Ptr);
 688   if (FunctionCount != FunctionTypes.size()) {
 689     return make_error<GenericBinaryError>("Invalid function count",
 690                                           object_error::parse_failed);
 691   }
 692
 693   CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
 694
 695   while (FunctionCount--) {
 696     wasm::WasmFunction Function;
 697     uint32_t FunctionSize = readVaruint32(Ptr);
 698     const uint8_t *FunctionEnd = Ptr + FunctionSize;
 699
 700     uint32_t NumLocalDecls = readVaruint32(Ptr);
 701     Function.Locals.reserve(NumLocalDecls);
 702     while (NumLocalDecls--) {
 703       wasm::WasmLocalDecl Decl;
 704       Decl.Count = readVaruint32(Ptr);
 705       Decl.Type = readVarint7(Ptr);
 706       Function.Locals.push_back(Decl);
 707     }
 708
 709     uint32_t BodySize = FunctionEnd - Ptr;
 710     Function.Body = ArrayRef<uint8_t>(Ptr, BodySize);
 711     Ptr += BodySize;
 712     assert(Ptr == FunctionEnd);
 713     Functions.push_back(Function);
 714   }
 715   if (Ptr != End)
 716     return make_error<GenericBinaryError>("Code section ended prematurely",
 717                                           object_error::parse_failed);
 718   return Error::success();
 719 }
 720
 721 Error WasmObjectFile::parseElemSection(const uint8_t *Ptr, const uint8_t *End) {
 722   uint32_t Count = readVaruint32(Ptr);
 723   ElemSegments.reserve(Count);
 724   while (Count--) {
 725     wasm::WasmElemSegment Segment;
 726     Segment.TableIndex = readVaruint32(Ptr);
 727     if (Segment.TableIndex != 0) {
 728       return make_error<GenericBinaryError>("Invalid TableIndex",
 729                                             object_error::parse_failed);
 730     }
 731     if (Error Err = readInitExpr(Segment.Offset, Ptr))
 732       return Err;
 733     uint32_t NumElems = readVaruint32(Ptr);
 734     while (NumElems--) {
 735       Segment.Functions.push_back(readVaruint32(Ptr));
 736     }
 737     ElemSegments.push_back(Segment);
 738   }
 739   if (Ptr != End)
 740     return make_error<GenericBinaryError>("Elem section ended prematurely",
 741                                           object_error::parse_failed);
 742   return Error::success();
 743 }
 744
 745 Error WasmObjectFile::parseDataSection(const uint8_t *Ptr, const uint8_t *End) {
 746   const uint8_t *Start = Ptr;
 747   uint32_t Count = readVaruint32(Ptr);
 748   DataSegments.reserve(Count);
 749   while (Count--) {
 750     WasmSegment Segment;
 751     Segment.Data.MemoryIndex = readVaruint32(Ptr);
 752     if (Error Err = readInitExpr(Segment.Data.Offset, Ptr))
 753       return Err;
 754     uint32_t Size = readVaruint32(Ptr);
 755     Segment.Data.Content = ArrayRef<uint8_t>(Ptr, Size);
 756     Segment.Data.Alignment = 0;
 757     Segment.Data.Flags = 0;
 758     Segment.SectionOffset = Ptr - Start;
 759     Ptr += Size;
 760     DataSegments.push_back(Segment);
 761   }
 762   if (Ptr != End)
 763     return make_error<GenericBinaryError>("Data section ended prematurely",
 764                                           object_error::parse_failed);
 765   return Error::success();
 766 }
 767
 768 const uint8_t *WasmObjectFile::getPtr(size_t Offset) const {
 769   return reinterpret_cast<const uint8_t *>(getData().substr(Offset, 1).data());
 770 }
 771
 772 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
 773   return Header;
 774 }
 775
 776 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.a++; }
 777
 778 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
 779   uint32_t Result = SymbolRef::SF_None;
 780   const WasmSymbol &Sym = getWasmSymbol(Symb);
 781
 782   DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
 783   if (Sym.isWeak())
 784     Result |= SymbolRef::SF_Weak;
 785   if (!Sym.isLocal())
 786     Result |= SymbolRef::SF_Global;
 787   if (Sym.isHidden())
 788     Result |= SymbolRef::SF_Hidden;
 789
 790   switch (Sym.Type) {
 791   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
 792     Result |= SymbolRef::SF_Undefined | SymbolRef::SF_Executable;
 793     break;
 794   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
 795     Result |= SymbolRef::SF_Executable;
 796     break;
 797   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
 798     Result |= SymbolRef::SF_Executable;
 799     Result |= SymbolRef::SF_FormatSpecific;
 800     break;
 801   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
 802     Result |= SymbolRef::SF_Undefined;
 803     break;
 804   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
 805     break;
 806   }
 807
 808   return Result;
 809 }
 810
 811 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
 812   DataRefImpl Ref;
 813   Ref.d.a = 0;
 814   return BasicSymbolRef(Ref, this);
 815 }
 816
 817 basic_symbol_iterator WasmObjectFile::symbol_end() const {
 818   DataRefImpl Ref;
 819   Ref.d.a = Symbols.size();
 820   return BasicSymbolRef(Ref, this);
 821 }
 822
 823 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
 824   return Symbols[Symb.d.a];
 825 }
 826
 827 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
 828   return getWasmSymbol(Symb.getRawDataRefImpl());
 829 }
 830
 831 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
 832   return getWasmSymbol(Symb).Name;
 833 }
 834
 835 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
 836   return getSymbolValue(Symb);
 837 }
 838
 839 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol& Sym) const {
 840   switch (Sym.Type) {
 841   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
 842   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
 843   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
 844   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
 845     return Sym.ElementIndex;
 846   case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
 847     uint32_t GlobalIndex = Sym.ElementIndex - NumImportedGlobals;
 848     assert(GlobalIndex < Globals.size());
 849     const wasm::WasmGlobal& Global = Globals[GlobalIndex];
 850     // WasmSymbols correspond only to I32_CONST globals
 851     assert(Global.InitExpr.Opcode == wasm::WASM_OPCODE_I32_CONST);
 852     return Global.InitExpr.Value.Int32;
 853   }
 854   }
 855   llvm_unreachable("invalid symbol type");
 856 }
 857
 858 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
 859   return getWasmSymbolValue(getWasmSymbol(Symb));
 860 }
 861
 862 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
 863   llvm_unreachable("not yet implemented");
 864   return 0;
 865 }
 866
 867 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
 868   llvm_unreachable("not yet implemented");
 869   return 0;
 870 }
 871
 872 Expected<SymbolRef::Type>
 873 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
 874   const WasmSymbol &Sym = getWasmSymbol(Symb);
 875
 876   switch (Sym.Type) {
 877   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
 878   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
 879   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
 880     return SymbolRef::ST_Function;
 881   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
 882   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
 883     return SymbolRef::ST_Data;
 884   }
 885
 886   llvm_unreachable("Unknown WasmSymbol::SymbolType");
 887   return SymbolRef::ST_Other;
 888 }
 889
 890 Expected<section_iterator>
 891 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
 892   DataRefImpl Ref;
 893   Ref.d.a = getWasmSymbol(Symb).Section;
 894   return section_iterator(SectionRef(Ref, this));
 895 }
 896
 897 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
 898
 899 std::error_code WasmObjectFile::getSectionName(DataRefImpl Sec,
 900                                                StringRef &Res) const {
 901   const WasmSection &S = Sections[Sec.d.a];
 902 #define ECase(X)                                                               \
 903   case wasm::WASM_SEC_##X:                                                     \
 904     Res = #X;                                                                  \
 905     break
 906   switch (S.Type) {
 907     ECase(TYPE);
 908     ECase(IMPORT);
 909     ECase(FUNCTION);
 910     ECase(TABLE);
 911     ECase(MEMORY);
 912     ECase(GLOBAL);
 913     ECase(EXPORT);
 914     ECase(START);
 915     ECase(ELEM);
 916     ECase(CODE);
 917     ECase(DATA);
 918   case wasm::WASM_SEC_CUSTOM:
 919     Res = S.Name;
 920     break;
 921   default:
 922     return object_error::invalid_section_index;
 923   }
 924 #undef ECase
 925   return std::error_code();
 926 }
 927
 928 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
 929
 930 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
 931   return Sec.d.a;
 932 }
 933
 934 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
 935   const WasmSection &S = Sections[Sec.d.a];
 936   return S.Content.size();
 937 }
 938
 939 std::error_code WasmObjectFile::getSectionContents(DataRefImpl Sec,
 940                                                    StringRef &Res) const {
 941   const WasmSection &S = Sections[Sec.d.a];
 942   // This will never fail since wasm sections can never be empty (user-sections
 943   // must have a name and non-user sections each have a defined structure).
 944   Res = StringRef(reinterpret_cast<const char *>(S.Content.data()),
 945                   S.Content.size());
 946   return std::error_code();
 947 }
 948
 949 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
 950   return 1;
 951 }
 952
 953 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
 954   return false;
 955 }
 956
 957 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
 958   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
 959 }
 960
 961 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
 962   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
 963 }
 964
 965 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
 966
 967 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
 968
 969 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
 970
 971 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
 972   DataRefImpl RelocRef;
 973   RelocRef.d.a = Ref.d.a;
 974   RelocRef.d.b = 0;
 975   return relocation_iterator(RelocationRef(RelocRef, this));
 976 }
 977
 978 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
 979   const WasmSection &Sec = getWasmSection(Ref);
 980   DataRefImpl RelocRef;
 981   RelocRef.d.a = Ref.d.a;
 982   RelocRef.d.b = Sec.Relocations.size();
 983   return relocation_iterator(RelocationRef(RelocRef, this));
 984 }
 985
 986 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const {
 987   Rel.d.b++;
 988 }
 989
 990 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
 991   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
 992   return Rel.Offset;
 993 }
 994
 995 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
 996   llvm_unreachable("not yet implemented");
 997   SymbolRef Ref;
 998   return symbol_iterator(Ref);
 999 }
1000
1001 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1002   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1003   return Rel.Type;
1004 }
1005
1006 void WasmObjectFile::getRelocationTypeName(
1007     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1008   const wasm::WasmRelocation& Rel = getWasmRelocation(Ref);
1009   StringRef Res = "Unknown";
1010
1011 #define WASM_RELOC(name, value)  \
1012   case wasm::name:              \
1013     Res = #name;               \
1014     break;
1015
1016   switch (Rel.Type) {
1017 #include "llvm/BinaryFormat/WasmRelocs/WebAssembly.def"
1018   }
1019
1020 #undef WASM_RELOC
1021
1022   Result.append(Res.begin(), Res.end());
1023 }
1024
1025 section_iterator WasmObjectFile::section_begin() const {
1026   DataRefImpl Ref;
1027   Ref.d.a = 0;
1028   return section_iterator(SectionRef(Ref, this));
1029 }
1030
1031 section_iterator WasmObjectFile::section_end() const {
1032   DataRefImpl Ref;
1033   Ref.d.a = Sections.size();
1034   return section_iterator(SectionRef(Ref, this));
1035 }
1036
1037 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
1038
1039 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1040
1041 unsigned WasmObjectFile::getArch() const { return Triple::wasm32; }
1042
1043 SubtargetFeatures WasmObjectFile::getFeatures() const {
1044   return SubtargetFeatures();
1045 }
1046
1047 bool WasmObjectFile::isRelocatableObject() const {
1048   return HasLinkingSection;
1049 }
1050
1051 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1052   assert(Ref.d.a < Sections.size());
1053   return Sections[Ref.d.a];
1054 }
1055
1056 const WasmSection &
1057 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1058   return getWasmSection(Section.getRawDataRefImpl());
1059 }
1060
1061 const wasm::WasmRelocation &
1062 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1063   return getWasmRelocation(Ref.getRawDataRefImpl());
1064 }
1065
1066 const wasm::WasmRelocation &
1067 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1068   assert(Ref.d.a < Sections.size());
1069   const WasmSection& Sec = Sections[Ref.d.a];
1070   assert(Ref.d.b < Sec.Relocations.size());
1071   return Sec.Relocations[Ref.d.b];
1072 }