lib/Object/WasmObjectFile.cpp

   1 //===- WasmObjectFile.cpp - Wasm object file implementation ---------------===//
   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 #include "llvm/ADT/ArrayRef.h"
  10 #include "llvm/ADT/DenseSet.h"
  11 #include "llvm/ADT/STLExtras.h"
  12 #include "llvm/ADT/SmallSet.h"
  13 #include "llvm/ADT/StringRef.h"
  14 #include "llvm/ADT/StringSet.h"
  15 #include "llvm/ADT/Triple.h"
  16 #include "llvm/BinaryFormat/Wasm.h"
  17 #include "llvm/MC/SubtargetFeature.h"
  18 #include "llvm/Object/Binary.h"
  19 #include "llvm/Object/Error.h"
  20 #include "llvm/Object/ObjectFile.h"
  21 #include "llvm/Object/SymbolicFile.h"
  22 #include "llvm/Object/Wasm.h"
  23 #include "llvm/Support/Endian.h"
  24 #include "llvm/Support/Error.h"
  25 #include "llvm/Support/ErrorHandling.h"
  26 #include "llvm/Support/LEB128.h"
  27 #include "llvm/Support/ScopedPrinter.h"
  28 #include <algorithm>
  29 #include <cassert>
  30 #include <cstdint>
  31 #include <cstring>
  32 #include <system_error>
  33
  34 #define DEBUG_TYPE "wasm-object"
  35
  36 using namespace llvm;
  37 using namespace object;
  38
  39 void WasmSymbol::print(raw_ostream &Out) const {
  40   Out << "Name=" << Info.Name
  41       << ", Kind=" << toString(wasm::WasmSymbolType(Info.Kind))
  42       << ", Flags=" << Info.Flags;
  43   if (!isTypeData()) {
  44     Out << ", ElemIndex=" << Info.ElementIndex;
  45   } else if (isDefined()) {
  46     Out << ", Segment=" << Info.DataRef.Segment;
  47     Out << ", Offset=" << Info.DataRef.Offset;
  48     Out << ", Size=" << Info.DataRef.Size;
  49   }
  50 }
  51
  52 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
  53 LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
  54 #endif
  55
  56 Expected<std::unique_ptr<WasmObjectFile>>
  57 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
  58   Error Err = Error::success();
  59   auto ObjectFile = std::make_unique<WasmObjectFile>(Buffer, Err);
  60   if (Err)
  61     return std::move(Err);
  62
  63   return std::move(ObjectFile);
  64 }
  65
  66 #define VARINT7_MAX ((1 << 7) - 1)
  67 #define VARINT7_MIN (-(1 << 7))
  68 #define VARUINT7_MAX (1 << 7)
  69 #define VARUINT1_MAX (1)
  70
  71 static uint8_t readUint8(WasmObjectFile::ReadContext &Ctx) {
  72   if (Ctx.Ptr == Ctx.End)
  73     report_fatal_error("EOF while reading uint8");
  74   return *Ctx.Ptr++;
  75 }
  76
  77 static uint32_t readUint32(WasmObjectFile::ReadContext &Ctx) {
  78   if (Ctx.Ptr + 4 > Ctx.End)
  79     report_fatal_error("EOF while reading uint32");
  80   uint32_t Result = support::endian::read32le(Ctx.Ptr);
  81   Ctx.Ptr += 4;
  82   return Result;
  83 }
  84
  85 static int32_t readFloat32(WasmObjectFile::ReadContext &Ctx) {
  86   if (Ctx.Ptr + 4 > Ctx.End)
  87     report_fatal_error("EOF while reading float64");
  88   int32_t Result = 0;
  89   memcpy(&Result, Ctx.Ptr, sizeof(Result));
  90   Ctx.Ptr += sizeof(Result);
  91   return Result;
  92 }
  93
  94 static int64_t readFloat64(WasmObjectFile::ReadContext &Ctx) {
  95   if (Ctx.Ptr + 8 > Ctx.End)
  96     report_fatal_error("EOF while reading float64");
  97   int64_t Result = 0;
  98   memcpy(&Result, Ctx.Ptr, sizeof(Result));
  99   Ctx.Ptr += sizeof(Result);
 100   return Result;
 101 }
 102
 103 static uint64_t readULEB128(WasmObjectFile::ReadContext &Ctx) {
 104   unsigned Count;
 105   const char *Error = nullptr;
 106   uint64_t Result = decodeULEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
 107   if (Error)
 108     report_fatal_error(Error);
 109   Ctx.Ptr += Count;
 110   return Result;
 111 }
 112
 113 static StringRef readString(WasmObjectFile::ReadContext &Ctx) {
 114   uint32_t StringLen = readULEB128(Ctx);
 115   if (Ctx.Ptr + StringLen > Ctx.End)
 116     report_fatal_error("EOF while reading string");
 117   StringRef Return =
 118       StringRef(reinterpret_cast<const char *>(Ctx.Ptr), StringLen);
 119   Ctx.Ptr += StringLen;
 120   return Return;
 121 }
 122
 123 static int64_t readLEB128(WasmObjectFile::ReadContext &Ctx) {
 124   unsigned Count;
 125   const char *Error = nullptr;
 126   uint64_t Result = decodeSLEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
 127   if (Error)
 128     report_fatal_error(Error);
 129   Ctx.Ptr += Count;
 130   return Result;
 131 }
 132
 133 static uint8_t readVaruint1(WasmObjectFile::ReadContext &Ctx) {
 134   int64_t Result = readLEB128(Ctx);
 135   if (Result > VARUINT1_MAX || Result < 0)
 136     report_fatal_error("LEB is outside Varuint1 range");
 137   return Result;
 138 }
 139
 140 static int32_t readVarint32(WasmObjectFile::ReadContext &Ctx) {
 141   int64_t Result = readLEB128(Ctx);
 142   if (Result > INT32_MAX || Result < INT32_MIN)
 143     report_fatal_error("LEB is outside Varint32 range");
 144   return Result;
 145 }
 146
 147 static uint32_t readVaruint32(WasmObjectFile::ReadContext &Ctx) {
 148   uint64_t Result = readULEB128(Ctx);
 149   if (Result > UINT32_MAX)
 150     report_fatal_error("LEB is outside Varuint32 range");
 151   return Result;
 152 }
 153
 154 static int64_t readVarint64(WasmObjectFile::ReadContext &Ctx) {
 155   return readLEB128(Ctx);
 156 }
 157
 158 static uint8_t readOpcode(WasmObjectFile::ReadContext &Ctx) {
 159   return readUint8(Ctx);
 160 }
 161
 162 static Error readInitExpr(wasm::WasmInitExpr &Expr,
 163                           WasmObjectFile::ReadContext &Ctx) {
 164   Expr.Opcode = readOpcode(Ctx);
 165
 166   switch (Expr.Opcode) {
 167   case wasm::WASM_OPCODE_I32_CONST:
 168     Expr.Value.Int32 = readVarint32(Ctx);
 169     break;
 170   case wasm::WASM_OPCODE_I64_CONST:
 171     Expr.Value.Int64 = readVarint64(Ctx);
 172     break;
 173   case wasm::WASM_OPCODE_F32_CONST:
 174     Expr.Value.Float32 = readFloat32(Ctx);
 175     break;
 176   case wasm::WASM_OPCODE_F64_CONST:
 177     Expr.Value.Float64 = readFloat64(Ctx);
 178     break;
 179   case wasm::WASM_OPCODE_GLOBAL_GET:
 180     Expr.Value.Global = readULEB128(Ctx);
 181     break;
 182   default:
 183     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
 184                                           object_error::parse_failed);
 185   }
 186
 187   uint8_t EndOpcode = readOpcode(Ctx);
 188   if (EndOpcode != wasm::WASM_OPCODE_END) {
 189     return make_error<GenericBinaryError>("Invalid init_expr",
 190                                           object_error::parse_failed);
 191   }
 192   return Error::success();
 193 }
 194
 195 static wasm::WasmLimits readLimits(WasmObjectFile::ReadContext &Ctx) {
 196   wasm::WasmLimits Result;
 197   Result.Flags = readVaruint32(Ctx);
 198   Result.Initial = readVaruint32(Ctx);
 199   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
 200     Result.Maximum = readVaruint32(Ctx);
 201   return Result;
 202 }
 203
 204 static wasm::WasmTable readTable(WasmObjectFile::ReadContext &Ctx) {
 205   wasm::WasmTable Table;
 206   Table.ElemType = readUint8(Ctx);
 207   Table.Limits = readLimits(Ctx);
 208   return Table;
 209 }
 210
 211 static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
 212                          WasmSectionOrderChecker &Checker) {
 213   Section.Offset = Ctx.Ptr - Ctx.Start;
 214   Section.Type = readUint8(Ctx);
 215   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
 216   uint32_t Size = readVaruint32(Ctx);
 217   if (Size == 0)
 218     return make_error<StringError>("Zero length section",
 219                                    object_error::parse_failed);
 220   if (Ctx.Ptr + Size > Ctx.End)
 221     return make_error<StringError>("Section too large",
 222                                    object_error::parse_failed);
 223   if (Section.Type == wasm::WASM_SEC_CUSTOM) {
 224     WasmObjectFile::ReadContext SectionCtx;
 225     SectionCtx.Start = Ctx.Ptr;
 226     SectionCtx.Ptr = Ctx.Ptr;
 227     SectionCtx.End = Ctx.Ptr + Size;
 228
 229     Section.Name = readString(SectionCtx);
 230
 231     uint32_t SectionNameSize = SectionCtx.Ptr - SectionCtx.Start;
 232     Ctx.Ptr += SectionNameSize;
 233     Size -= SectionNameSize;
 234   }
 235
 236   if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
 237     return make_error<StringError>("Out of order section type: " +
 238                                        llvm::to_string(Section.Type),
 239                                    object_error::parse_failed);
 240   }
 241
 242   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
 243   Ctx.Ptr += Size;
 244   return Error::success();
 245 }
 246
 247 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
 248     : ObjectFile(Binary::ID_Wasm, Buffer) {
 249   ErrorAsOutParameter ErrAsOutParam(&Err);
 250   Header.Magic = getData().substr(0, 4);
 251   if (Header.Magic != StringRef("\0asm", 4)) {
 252     Err =
 253         make_error<StringError>("Bad magic number", object_error::parse_failed);
 254     return;
 255   }
 256
 257   ReadContext Ctx;
 258   Ctx.Start = getData().bytes_begin();
 259   Ctx.Ptr = Ctx.Start + 4;
 260   Ctx.End = Ctx.Start + getData().size();
 261
 262   if (Ctx.Ptr + 4 > Ctx.End) {
 263     Err = make_error<StringError>("Missing version number",
 264                                   object_error::parse_failed);
 265     return;
 266   }
 267
 268   Header.Version = readUint32(Ctx);
 269   if (Header.Version != wasm::WasmVersion) {
 270     Err = make_error<StringError>("Bad version number",
 271                                   object_error::parse_failed);
 272     return;
 273   }
 274
 275   WasmSection Sec;
 276   WasmSectionOrderChecker Checker;
 277   while (Ctx.Ptr < Ctx.End) {
 278     if ((Err = readSection(Sec, Ctx, Checker)))
 279       return;
 280     if ((Err = parseSection(Sec)))
 281       return;
 282
 283     Sections.push_back(Sec);
 284   }
 285 }
 286
 287 Error WasmObjectFile::parseSection(WasmSection &Sec) {
 288   ReadContext Ctx;
 289   Ctx.Start = Sec.Content.data();
 290   Ctx.End = Ctx.Start + Sec.Content.size();
 291   Ctx.Ptr = Ctx.Start;
 292   switch (Sec.Type) {
 293   case wasm::WASM_SEC_CUSTOM:
 294     return parseCustomSection(Sec, Ctx);
 295   case wasm::WASM_SEC_TYPE:
 296     return parseTypeSection(Ctx);
 297   case wasm::WASM_SEC_IMPORT:
 298     return parseImportSection(Ctx);
 299   case wasm::WASM_SEC_FUNCTION:
 300     return parseFunctionSection(Ctx);
 301   case wasm::WASM_SEC_TABLE:
 302     return parseTableSection(Ctx);
 303   case wasm::WASM_SEC_MEMORY:
 304     return parseMemorySection(Ctx);
 305   case wasm::WASM_SEC_GLOBAL:
 306     return parseGlobalSection(Ctx);
 307   case wasm::WASM_SEC_EVENT:
 308     return parseEventSection(Ctx);
 309   case wasm::WASM_SEC_EXPORT:
 310     return parseExportSection(Ctx);
 311   case wasm::WASM_SEC_START:
 312     return parseStartSection(Ctx);
 313   case wasm::WASM_SEC_ELEM:
 314     return parseElemSection(Ctx);
 315   case wasm::WASM_SEC_CODE:
 316     return parseCodeSection(Ctx);
 317   case wasm::WASM_SEC_DATA:
 318     return parseDataSection(Ctx);
 319   case wasm::WASM_SEC_DATACOUNT:
 320     return parseDataCountSection(Ctx);
 321   default:
 322     return make_error<GenericBinaryError>(
 323         "Invalid section type: " + Twine(Sec.Type), object_error::parse_failed);
 324   }
 325 }
 326
 327 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
 328   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
 329   HasDylinkSection = true;
 330   DylinkInfo.MemorySize = readVaruint32(Ctx);
 331   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
 332   DylinkInfo.TableSize = readVaruint32(Ctx);
 333   DylinkInfo.TableAlignment = readVaruint32(Ctx);
 334   uint32_t Count = readVaruint32(Ctx);
 335   while (Count--) {
 336     DylinkInfo.Needed.push_back(readString(Ctx));
 337   }
 338   if (Ctx.Ptr != Ctx.End)
 339     return make_error<GenericBinaryError>("dylink section ended prematurely",
 340                                           object_error::parse_failed);
 341   return Error::success();
 342 }
 343
 344 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
 345   llvm::DenseSet<uint64_t> Seen;
 346   if (Functions.size() != FunctionTypes.size()) {
 347     return make_error<GenericBinaryError>("Names must come after code section",
 348                                           object_error::parse_failed);
 349   }
 350
 351   while (Ctx.Ptr < Ctx.End) {
 352     uint8_t Type = readUint8(Ctx);
 353     uint32_t Size = readVaruint32(Ctx);
 354     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
 355     switch (Type) {
 356     case wasm::WASM_NAMES_FUNCTION: {
 357       uint32_t Count = readVaruint32(Ctx);
 358       while (Count--) {
 359         uint32_t Index = readVaruint32(Ctx);
 360         if (!Seen.insert(Index).second)
 361           return make_error<GenericBinaryError>("Function named more than once",
 362                                                 object_error::parse_failed);
 363         StringRef Name = readString(Ctx);
 364         if (!isValidFunctionIndex(Index) || Name.empty())
 365           return make_error<GenericBinaryError>("Invalid name entry",
 366                                                 object_error::parse_failed);
 367         DebugNames.push_back(wasm::WasmFunctionName{Index, Name});
 368         if (isDefinedFunctionIndex(Index))
 369           getDefinedFunction(Index).DebugName = Name;
 370       }
 371       break;
 372     }
 373     // Ignore local names for now
 374     case wasm::WASM_NAMES_LOCAL:
 375     default:
 376       Ctx.Ptr += Size;
 377       break;
 378     }
 379     if (Ctx.Ptr != SubSectionEnd)
 380       return make_error<GenericBinaryError>(
 381           "Name sub-section ended prematurely", object_error::parse_failed);
 382   }
 383
 384   if (Ctx.Ptr != Ctx.End)
 385     return make_error<GenericBinaryError>("Name section ended prematurely",
 386                                           object_error::parse_failed);
 387   return Error::success();
 388 }
 389
 390 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
 391   HasLinkingSection = true;
 392   if (Functions.size() != FunctionTypes.size()) {
 393     return make_error<GenericBinaryError>(
 394         "Linking data must come after code section",
 395         object_error::parse_failed);
 396   }
 397
 398   LinkingData.Version = readVaruint32(Ctx);
 399   if (LinkingData.Version != wasm::WasmMetadataVersion) {
 400     return make_error<GenericBinaryError>(
 401         "Unexpected metadata version: " + Twine(LinkingData.Version) +
 402             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
 403         object_error::parse_failed);
 404   }
 405
 406   const uint8_t *OrigEnd = Ctx.End;
 407   while (Ctx.Ptr < OrigEnd) {
 408     Ctx.End = OrigEnd;
 409     uint8_t Type = readUint8(Ctx);
 410     uint32_t Size = readVaruint32(Ctx);
 411     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
 412                       << "\n");
 413     Ctx.End = Ctx.Ptr + Size;
 414     switch (Type) {
 415     case wasm::WASM_SYMBOL_TABLE:
 416       if (Error Err = parseLinkingSectionSymtab(Ctx))
 417         return Err;
 418       break;
 419     case wasm::WASM_SEGMENT_INFO: {
 420       uint32_t Count = readVaruint32(Ctx);
 421       if (Count > DataSegments.size())
 422         return make_error<GenericBinaryError>("Too many segment names",
 423                                               object_error::parse_failed);
 424       for (uint32_t I = 0; I < Count; I++) {
 425         DataSegments[I].Data.Name = readString(Ctx);
 426         DataSegments[I].Data.Alignment = readVaruint32(Ctx);
 427         DataSegments[I].Data.LinkerFlags = readVaruint32(Ctx);
 428       }
 429       break;
 430     }
 431     case wasm::WASM_INIT_FUNCS: {
 432       uint32_t Count = readVaruint32(Ctx);
 433       LinkingData.InitFunctions.reserve(Count);
 434       for (uint32_t I = 0; I < Count; I++) {
 435         wasm::WasmInitFunc Init;
 436         Init.Priority = readVaruint32(Ctx);
 437         Init.Symbol = readVaruint32(Ctx);
 438         if (!isValidFunctionSymbol(Init.Symbol))
 439           return make_error<GenericBinaryError>("Invalid function symbol: " +
 440                                                     Twine(Init.Symbol),
 441                                                 object_error::parse_failed);
 442         LinkingData.InitFunctions.emplace_back(Init);
 443       }
 444       break;
 445     }
 446     case wasm::WASM_COMDAT_INFO:
 447       if (Error Err = parseLinkingSectionComdat(Ctx))
 448         return Err;
 449       break;
 450     default:
 451       Ctx.Ptr += Size;
 452       break;
 453     }
 454     if (Ctx.Ptr != Ctx.End)
 455       return make_error<GenericBinaryError>(
 456           "Linking sub-section ended prematurely", object_error::parse_failed);
 457   }
 458   if (Ctx.Ptr != OrigEnd)
 459     return make_error<GenericBinaryError>("Linking section ended prematurely",
 460                                           object_error::parse_failed);
 461   return Error::success();
 462 }
 463
 464 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
 465   uint32_t Count = readVaruint32(Ctx);
 466   LinkingData.SymbolTable.reserve(Count);
 467   Symbols.reserve(Count);
 468   StringSet<> SymbolNames;
 469
 470   std::vector<wasm::WasmImport *> ImportedGlobals;
 471   std::vector<wasm::WasmImport *> ImportedFunctions;
 472   std::vector<wasm::WasmImport *> ImportedEvents;
 473   ImportedGlobals.reserve(Imports.size());
 474   ImportedFunctions.reserve(Imports.size());
 475   ImportedEvents.reserve(Imports.size());
 476   for (auto &I : Imports) {
 477     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
 478       ImportedFunctions.emplace_back(&I);
 479     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
 480       ImportedGlobals.emplace_back(&I);
 481     else if (I.Kind == wasm::WASM_EXTERNAL_EVENT)
 482       ImportedEvents.emplace_back(&I);
 483   }
 484
 485   while (Count--) {
 486     wasm::WasmSymbolInfo Info;
 487     const wasm::WasmSignature *Signature = nullptr;
 488     const wasm::WasmGlobalType *GlobalType = nullptr;
 489     const wasm::WasmEventType *EventType = nullptr;
 490
 491     Info.Kind = readUint8(Ctx);
 492     Info.Flags = readVaruint32(Ctx);
 493     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
 494
 495     switch (Info.Kind) {
 496     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
 497       Info.ElementIndex = readVaruint32(Ctx);
 498       if (!isValidFunctionIndex(Info.ElementIndex) ||
 499           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
 500         return make_error<GenericBinaryError>("invalid function symbol index",
 501                                               object_error::parse_failed);
 502       if (IsDefined) {
 503         Info.Name = readString(Ctx);
 504         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
 505         Signature = &Signatures[FunctionTypes[FuncIndex]];
 506         wasm::WasmFunction &Function = Functions[FuncIndex];
 507         if (Function.SymbolName.empty())
 508           Function.SymbolName = Info.Name;
 509       } else {
 510         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
 511         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
 512           Info.Name = readString(Ctx);
 513         else
 514           Info.Name = Import.Field;
 515         Signature = &Signatures[Import.SigIndex];
 516         Info.ImportName = Import.Field;
 517         Info.ImportModule = Import.Module;
 518       }
 519       break;
 520
 521     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
 522       Info.ElementIndex = readVaruint32(Ctx);
 523       if (!isValidGlobalIndex(Info.ElementIndex) ||
 524           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
 525         return make_error<GenericBinaryError>("invalid global symbol index",
 526                                               object_error::parse_failed);
 527       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
 528                             wasm::WASM_SYMBOL_BINDING_WEAK)
 529         return make_error<GenericBinaryError>("undefined weak global symbol",
 530                                               object_error::parse_failed);
 531       if (IsDefined) {
 532         Info.Name = readString(Ctx);
 533         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
 534         wasm::WasmGlobal &Global = Globals[GlobalIndex];
 535         GlobalType = &Global.Type;
 536         if (Global.SymbolName.empty())
 537           Global.SymbolName = Info.Name;
 538       } else {
 539         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
 540         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
 541           Info.Name = readString(Ctx);
 542         else
 543           Info.Name = Import.Field;
 544         GlobalType = &Import.Global;
 545         Info.ImportName = Import.Field;
 546         Info.ImportModule = Import.Module;
 547       }
 548       break;
 549
 550     case wasm::WASM_SYMBOL_TYPE_DATA:
 551       Info.Name = readString(Ctx);
 552       if (IsDefined) {
 553         uint32_t Index = readVaruint32(Ctx);
 554         if (Index >= DataSegments.size())
 555           return make_error<GenericBinaryError>("invalid data symbol index",
 556                                                 object_error::parse_failed);
 557         uint32_t Offset = readVaruint32(Ctx);
 558         uint32_t Size = readVaruint32(Ctx);
 559         if (Offset + Size > DataSegments[Index].Data.Content.size())
 560           return make_error<GenericBinaryError>("invalid data symbol offset",
 561                                                 object_error::parse_failed);
 562         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
 563       }
 564       break;
 565
 566     case wasm::WASM_SYMBOL_TYPE_SECTION: {
 567       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
 568           wasm::WASM_SYMBOL_BINDING_LOCAL)
 569         return make_error<GenericBinaryError>(
 570             "Section symbols must have local binding",
 571             object_error::parse_failed);
 572       Info.ElementIndex = readVaruint32(Ctx);
 573       // Use somewhat unique section name as symbol name.
 574       StringRef SectionName = Sections[Info.ElementIndex].Name;
 575       Info.Name = SectionName;
 576       break;
 577     }
 578
 579     case wasm::WASM_SYMBOL_TYPE_EVENT: {
 580       Info.ElementIndex = readVaruint32(Ctx);
 581       if (!isValidEventIndex(Info.ElementIndex) ||
 582           IsDefined != isDefinedEventIndex(Info.ElementIndex))
 583         return make_error<GenericBinaryError>("invalid event symbol index",
 584                                               object_error::parse_failed);
 585       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
 586                             wasm::WASM_SYMBOL_BINDING_WEAK)
 587         return make_error<GenericBinaryError>("undefined weak global symbol",
 588                                               object_error::parse_failed);
 589       if (IsDefined) {
 590         Info.Name = readString(Ctx);
 591         unsigned EventIndex = Info.ElementIndex - NumImportedEvents;
 592         wasm::WasmEvent &Event = Events[EventIndex];
 593         Signature = &Signatures[Event.Type.SigIndex];
 594         EventType = &Event.Type;
 595         if (Event.SymbolName.empty())
 596           Event.SymbolName = Info.Name;
 597
 598       } else {
 599         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
 600         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
 601           Info.Name = readString(Ctx);
 602         else
 603           Info.Name = Import.Field;
 604         EventType = &Import.Event;
 605         Signature = &Signatures[EventType->SigIndex];
 606         Info.ImportName = Import.Field;
 607         Info.ImportModule = Import.Module;
 608       }
 609       break;
 610     }
 611
 612     default:
 613       return make_error<GenericBinaryError>("Invalid symbol type",
 614                                             object_error::parse_failed);
 615     }
 616
 617     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
 618             wasm::WASM_SYMBOL_BINDING_LOCAL &&
 619         !SymbolNames.insert(Info.Name).second)
 620       return make_error<GenericBinaryError>("Duplicate symbol name " +
 621                                                 Twine(Info.Name),
 622                                             object_error::parse_failed);
 623     LinkingData.SymbolTable.emplace_back(Info);
 624     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, EventType,
 625                          Signature);
 626     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
 627   }
 628
 629   return Error::success();
 630 }
 631
 632 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
 633   uint32_t ComdatCount = readVaruint32(Ctx);
 634   StringSet<> ComdatSet;
 635   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
 636     StringRef Name = readString(Ctx);
 637     if (Name.empty() || !ComdatSet.insert(Name).second)
 638       return make_error<GenericBinaryError>("Bad/duplicate COMDAT name " +
 639                                                 Twine(Name),
 640                                             object_error::parse_failed);
 641     LinkingData.Comdats.emplace_back(Name);
 642     uint32_t Flags = readVaruint32(Ctx);
 643     if (Flags != 0)
 644       return make_error<GenericBinaryError>("Unsupported COMDAT flags",
 645                                             object_error::parse_failed);
 646
 647     uint32_t EntryCount = readVaruint32(Ctx);
 648     while (EntryCount--) {
 649       unsigned Kind = readVaruint32(Ctx);
 650       unsigned Index = readVaruint32(Ctx);
 651       switch (Kind) {
 652       default:
 653         return make_error<GenericBinaryError>("Invalid COMDAT entry type",
 654                                               object_error::parse_failed);
 655       case wasm::WASM_COMDAT_DATA:
 656         if (Index >= DataSegments.size())
 657           return make_error<GenericBinaryError>(
 658               "COMDAT data index out of range", object_error::parse_failed);
 659         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
 660           return make_error<GenericBinaryError>("Data segment in two COMDATs",
 661                                                 object_error::parse_failed);
 662         DataSegments[Index].Data.Comdat = ComdatIndex;
 663         break;
 664       case wasm::WASM_COMDAT_FUNCTION:
 665         if (!isDefinedFunctionIndex(Index))
 666           return make_error<GenericBinaryError>(
 667               "COMDAT function index out of range", object_error::parse_failed);
 668         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
 669           return make_error<GenericBinaryError>("Function in two COMDATs",
 670                                                 object_error::parse_failed);
 671         getDefinedFunction(Index).Comdat = ComdatIndex;
 672         break;
 673       }
 674     }
 675   }
 676   return Error::success();
 677 }
 678
 679 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
 680   llvm::SmallSet<StringRef, 3> FieldsSeen;
 681   uint32_t Fields = readVaruint32(Ctx);
 682   for (size_t I = 0; I < Fields; ++I) {
 683     StringRef FieldName = readString(Ctx);
 684     if (!FieldsSeen.insert(FieldName).second)
 685       return make_error<GenericBinaryError>(
 686           "Producers section does not have unique fields",
 687           object_error::parse_failed);
 688     std::vector<std::pair<std::string, std::string>> *ProducerVec = nullptr;
 689     if (FieldName == "language") {
 690       ProducerVec = &ProducerInfo.Languages;
 691     } else if (FieldName == "processed-by") {
 692       ProducerVec = &ProducerInfo.Tools;
 693     } else if (FieldName == "sdk") {
 694       ProducerVec = &ProducerInfo.SDKs;
 695     } else {
 696       return make_error<GenericBinaryError>(
 697           "Producers section field is not named one of language, processed-by, "
 698           "or sdk",
 699           object_error::parse_failed);
 700     }
 701     uint32_t ValueCount = readVaruint32(Ctx);
 702     llvm::SmallSet<StringRef, 8> ProducersSeen;
 703     for (size_t J = 0; J < ValueCount; ++J) {
 704       StringRef Name = readString(Ctx);
 705       StringRef Version = readString(Ctx);
 706       if (!ProducersSeen.insert(Name).second) {
 707         return make_error<GenericBinaryError>(
 708             "Producers section contains repeated producer",
 709             object_error::parse_failed);
 710       }
 711       ProducerVec->emplace_back(Name, Version);
 712     }
 713   }
 714   if (Ctx.Ptr != Ctx.End)
 715     return make_error<GenericBinaryError>("Producers section ended prematurely",
 716                                           object_error::parse_failed);
 717   return Error::success();
 718 }
 719
 720 Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
 721   llvm::SmallSet<std::string, 8> FeaturesSeen;
 722   uint32_t FeatureCount = readVaruint32(Ctx);
 723   for (size_t I = 0; I < FeatureCount; ++I) {
 724     wasm::WasmFeatureEntry Feature;
 725     Feature.Prefix = readUint8(Ctx);
 726     switch (Feature.Prefix) {
 727     case wasm::WASM_FEATURE_PREFIX_USED:
 728     case wasm::WASM_FEATURE_PREFIX_REQUIRED:
 729     case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
 730       break;
 731     default:
 732       return make_error<GenericBinaryError>("Unknown feature policy prefix",
 733                                             object_error::parse_failed);
 734     }
 735     Feature.Name = readString(Ctx);
 736     if (!FeaturesSeen.insert(Feature.Name).second)
 737       return make_error<GenericBinaryError>(
 738           "Target features section contains repeated feature \"" +
 739               Feature.Name + "\"",
 740           object_error::parse_failed);
 741     TargetFeatures.push_back(Feature);
 742   }
 743   if (Ctx.Ptr != Ctx.End)
 744     return make_error<GenericBinaryError>(
 745         "Target features section ended prematurely",
 746         object_error::parse_failed);
 747   return Error::success();
 748 }
 749
 750 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
 751   uint32_t SectionIndex = readVaruint32(Ctx);
 752   if (SectionIndex >= Sections.size())
 753     return make_error<GenericBinaryError>("Invalid section index",
 754                                           object_error::parse_failed);
 755   WasmSection &Section = Sections[SectionIndex];
 756   uint32_t RelocCount = readVaruint32(Ctx);
 757   uint32_t EndOffset = Section.Content.size();
 758   uint32_t PreviousOffset = 0;
 759   while (RelocCount--) {
 760     wasm::WasmRelocation Reloc = {};
 761     Reloc.Type = readVaruint32(Ctx);
 762     Reloc.Offset = readVaruint32(Ctx);
 763     if (Reloc.Offset < PreviousOffset)
 764       return make_error<GenericBinaryError>("Relocations not in offset order",
 765                                             object_error::parse_failed);
 766     PreviousOffset = Reloc.Offset;
 767     Reloc.Index = readVaruint32(Ctx);
 768     switch (Reloc.Type) {
 769     case wasm::R_WASM_FUNCTION_INDEX_LEB:
 770     case wasm::R_WASM_TABLE_INDEX_SLEB:
 771     case wasm::R_WASM_TABLE_INDEX_I32:
 772     case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
 773       if (!isValidFunctionSymbol(Reloc.Index))
 774         return make_error<GenericBinaryError>("Bad relocation function index",
 775                                               object_error::parse_failed);
 776       break;
 777     case wasm::R_WASM_TYPE_INDEX_LEB:
 778       if (Reloc.Index >= Signatures.size())
 779         return make_error<GenericBinaryError>("Bad relocation type index",
 780                                               object_error::parse_failed);
 781       break;
 782     case wasm::R_WASM_GLOBAL_INDEX_LEB:
 783       // R_WASM_GLOBAL_INDEX_LEB are can be used against function and data
 784       // symbols to refer to their GOT entries.
 785       if (!isValidGlobalSymbol(Reloc.Index) &&
 786           !isValidDataSymbol(Reloc.Index) &&
 787           !isValidFunctionSymbol(Reloc.Index))
 788         return make_error<GenericBinaryError>("Bad relocation global index",
 789                                               object_error::parse_failed);
 790       break;
 791     case wasm::R_WASM_EVENT_INDEX_LEB:
 792       if (!isValidEventSymbol(Reloc.Index))
 793         return make_error<GenericBinaryError>("Bad relocation event index",
 794                                               object_error::parse_failed);
 795       break;
 796     case wasm::R_WASM_MEMORY_ADDR_LEB:
 797     case wasm::R_WASM_MEMORY_ADDR_SLEB:
 798     case wasm::R_WASM_MEMORY_ADDR_I32:
 799     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
 800       if (!isValidDataSymbol(Reloc.Index))
 801         return make_error<GenericBinaryError>("Bad relocation data index",
 802                                               object_error::parse_failed);
 803       Reloc.Addend = readVarint32(Ctx);
 804       break;
 805     case wasm::R_WASM_FUNCTION_OFFSET_I32:
 806       if (!isValidFunctionSymbol(Reloc.Index))
 807         return make_error<GenericBinaryError>("Bad relocation function index",
 808                                               object_error::parse_failed);
 809       Reloc.Addend = readVarint32(Ctx);
 810       break;
 811     case wasm::R_WASM_SECTION_OFFSET_I32:
 812       if (!isValidSectionSymbol(Reloc.Index))
 813         return make_error<GenericBinaryError>("Bad relocation section index",
 814                                               object_error::parse_failed);
 815       Reloc.Addend = readVarint32(Ctx);
 816       break;
 817     default:
 818       return make_error<GenericBinaryError>("Bad relocation type: " +
 819                                                 Twine(Reloc.Type),
 820                                             object_error::parse_failed);
 821     }
 822
 823     // Relocations must fit inside the section, and must appear in order.  They
 824     // also shouldn't overlap a function/element boundary, but we don't bother
 825     // to check that.
 826     uint64_t Size = 5;
 827     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I32 ||
 828         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I32 ||
 829         Reloc.Type == wasm::R_WASM_SECTION_OFFSET_I32 ||
 830         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I32)
 831       Size = 4;
 832     if (Reloc.Offset + Size > EndOffset)
 833       return make_error<GenericBinaryError>("Bad relocation offset",
 834                                             object_error::parse_failed);
 835
 836     Section.Relocations.push_back(Reloc);
 837   }
 838   if (Ctx.Ptr != Ctx.End)
 839     return make_error<GenericBinaryError>("Reloc section ended prematurely",
 840                                           object_error::parse_failed);
 841   return Error::success();
 842 }
 843
 844 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
 845   if (Sec.Name == "dylink") {
 846     if (Error Err = parseDylinkSection(Ctx))
 847       return Err;
 848   } else if (Sec.Name == "name") {
 849     if (Error Err = parseNameSection(Ctx))
 850       return Err;
 851   } else if (Sec.Name == "linking") {
 852     if (Error Err = parseLinkingSection(Ctx))
 853       return Err;
 854   } else if (Sec.Name == "producers") {
 855     if (Error Err = parseProducersSection(Ctx))
 856       return Err;
 857   } else if (Sec.Name == "target_features") {
 858     if (Error Err = parseTargetFeaturesSection(Ctx))
 859       return Err;
 860   } else if (Sec.Name.startswith("reloc.")) {
 861     if (Error Err = parseRelocSection(Sec.Name, Ctx))
 862       return Err;
 863   }
 864   return Error::success();
 865 }
 866
 867 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
 868   uint32_t Count = readVaruint32(Ctx);
 869   Signatures.reserve(Count);
 870   while (Count--) {
 871     wasm::WasmSignature Sig;
 872     uint8_t Form = readUint8(Ctx);
 873     if (Form != wasm::WASM_TYPE_FUNC) {
 874       return make_error<GenericBinaryError>("Invalid signature type",
 875                                             object_error::parse_failed);
 876     }
 877     uint32_t ParamCount = readVaruint32(Ctx);
 878     Sig.Params.reserve(ParamCount);
 879     while (ParamCount--) {
 880       uint32_t ParamType = readUint8(Ctx);
 881       Sig.Params.push_back(wasm::ValType(ParamType));
 882     }
 883     uint32_t ReturnCount = readVaruint32(Ctx);
 884     if (ReturnCount) {
 885       if (ReturnCount != 1) {
 886         return make_error<GenericBinaryError>(
 887             "Multiple return types not supported", object_error::parse_failed);
 888       }
 889       Sig.Returns.push_back(wasm::ValType(readUint8(Ctx)));
 890     }
 891     Signatures.push_back(std::move(Sig));
 892   }
 893   if (Ctx.Ptr != Ctx.End)
 894     return make_error<GenericBinaryError>("Type section ended prematurely",
 895                                           object_error::parse_failed);
 896   return Error::success();
 897 }
 898
 899 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
 900   uint32_t Count = readVaruint32(Ctx);
 901   Imports.reserve(Count);
 902   for (uint32_t I = 0; I < Count; I++) {
 903     wasm::WasmImport Im;
 904     Im.Module = readString(Ctx);
 905     Im.Field = readString(Ctx);
 906     Im.Kind = readUint8(Ctx);
 907     switch (Im.Kind) {
 908     case wasm::WASM_EXTERNAL_FUNCTION:
 909       NumImportedFunctions++;
 910       Im.SigIndex = readVaruint32(Ctx);
 911       break;
 912     case wasm::WASM_EXTERNAL_GLOBAL:
 913       NumImportedGlobals++;
 914       Im.Global.Type = readUint8(Ctx);
 915       Im.Global.Mutable = readVaruint1(Ctx);
 916       break;
 917     case wasm::WASM_EXTERNAL_MEMORY:
 918       Im.Memory = readLimits(Ctx);
 919       break;
 920     case wasm::WASM_EXTERNAL_TABLE:
 921       Im.Table = readTable(Ctx);
 922       if (Im.Table.ElemType != wasm::WASM_TYPE_FUNCREF)
 923         return make_error<GenericBinaryError>("Invalid table element type",
 924                                               object_error::parse_failed);
 925       break;
 926     case wasm::WASM_EXTERNAL_EVENT:
 927       NumImportedEvents++;
 928       Im.Event.Attribute = readVarint32(Ctx);
 929       Im.Event.SigIndex = readVarint32(Ctx);
 930       break;
 931     default:
 932       return make_error<GenericBinaryError>("Unexpected import kind",
 933                                             object_error::parse_failed);
 934     }
 935     Imports.push_back(Im);
 936   }
 937   if (Ctx.Ptr != Ctx.End)
 938     return make_error<GenericBinaryError>("Import section ended prematurely",
 939                                           object_error::parse_failed);
 940   return Error::success();
 941 }
 942
 943 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
 944   uint32_t Count = readVaruint32(Ctx);
 945   FunctionTypes.reserve(Count);
 946   uint32_t NumTypes = Signatures.size();
 947   while (Count--) {
 948     uint32_t Type = readVaruint32(Ctx);
 949     if (Type >= NumTypes)
 950       return make_error<GenericBinaryError>("Invalid function type",
 951                                             object_error::parse_failed);
 952     FunctionTypes.push_back(Type);
 953   }
 954   if (Ctx.Ptr != Ctx.End)
 955     return make_error<GenericBinaryError>("Function section ended prematurely",
 956                                           object_error::parse_failed);
 957   return Error::success();
 958 }
 959
 960 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
 961   uint32_t Count = readVaruint32(Ctx);
 962   Tables.reserve(Count);
 963   while (Count--) {
 964     Tables.push_back(readTable(Ctx));
 965     if (Tables.back().ElemType != wasm::WASM_TYPE_FUNCREF) {
 966       return make_error<GenericBinaryError>("Invalid table element type",
 967                                             object_error::parse_failed);
 968     }
 969   }
 970   if (Ctx.Ptr != Ctx.End)
 971     return make_error<GenericBinaryError>("Table section ended prematurely",
 972                                           object_error::parse_failed);
 973   return Error::success();
 974 }
 975
 976 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
 977   uint32_t Count = readVaruint32(Ctx);
 978   Memories.reserve(Count);
 979   while (Count--) {
 980     Memories.push_back(readLimits(Ctx));
 981   }
 982   if (Ctx.Ptr != Ctx.End)
 983     return make_error<GenericBinaryError>("Memory section ended prematurely",
 984                                           object_error::parse_failed);
 985   return Error::success();
 986 }
 987
 988 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
 989   GlobalSection = Sections.size();
 990   uint32_t Count = readVaruint32(Ctx);
 991   Globals.reserve(Count);
 992   while (Count--) {
 993     wasm::WasmGlobal Global;
 994     Global.Index = NumImportedGlobals + Globals.size();
 995     Global.Type.Type = readUint8(Ctx);
 996     Global.Type.Mutable = readVaruint1(Ctx);
 997     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
 998       return Err;
 999     Globals.push_back(Global);
1000   }
1001   if (Ctx.Ptr != Ctx.End)
1002     return make_error<GenericBinaryError>("Global section ended prematurely",
1003                                           object_error::parse_failed);
1004   return Error::success();
1005 }
1006
1007 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
1008   EventSection = Sections.size();
1009   uint32_t Count = readVarint32(Ctx);
1010   Events.reserve(Count);
1011   while (Count--) {
1012     wasm::WasmEvent Event;
1013     Event.Index = NumImportedEvents + Events.size();
1014     Event.Type.Attribute = readVaruint32(Ctx);
1015     Event.Type.SigIndex = readVarint32(Ctx);
1016     Events.push_back(Event);
1017   }
1018
1019   if (Ctx.Ptr != Ctx.End)
1020     return make_error<GenericBinaryError>("Event section ended prematurely",
1021                                           object_error::parse_failed);
1022   return Error::success();
1023 }
1024
1025 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
1026   uint32_t Count = readVaruint32(Ctx);
1027   Exports.reserve(Count);
1028   for (uint32_t I = 0; I < Count; I++) {
1029     wasm::WasmExport Ex;
1030     Ex.Name = readString(Ctx);
1031     Ex.Kind = readUint8(Ctx);
1032     Ex.Index = readVaruint32(Ctx);
1033     switch (Ex.Kind) {
1034     case wasm::WASM_EXTERNAL_FUNCTION:
1035       if (!isValidFunctionIndex(Ex.Index))
1036         return make_error<GenericBinaryError>("Invalid function export",
1037                                               object_error::parse_failed);
1038       break;
1039     case wasm::WASM_EXTERNAL_GLOBAL:
1040       if (!isValidGlobalIndex(Ex.Index))
1041         return make_error<GenericBinaryError>("Invalid global export",
1042                                               object_error::parse_failed);
1043       break;
1044     case wasm::WASM_EXTERNAL_EVENT:
1045       if (!isValidEventIndex(Ex.Index))
1046         return make_error<GenericBinaryError>("Invalid event export",
1047                                               object_error::parse_failed);
1048       break;
1049     case wasm::WASM_EXTERNAL_MEMORY:
1050     case wasm::WASM_EXTERNAL_TABLE:
1051       break;
1052     default:
1053       return make_error<GenericBinaryError>("Unexpected export kind",
1054                                             object_error::parse_failed);
1055     }
1056     Exports.push_back(Ex);
1057   }
1058   if (Ctx.Ptr != Ctx.End)
1059     return make_error<GenericBinaryError>("Export section ended prematurely",
1060                                           object_error::parse_failed);
1061   return Error::success();
1062 }
1063
1064 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
1065   return Index < NumImportedFunctions + FunctionTypes.size();
1066 }
1067
1068 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
1069   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
1070 }
1071
1072 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
1073   return Index < NumImportedGlobals + Globals.size();
1074 }
1075
1076 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
1077   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
1078 }
1079
1080 bool WasmObjectFile::isValidEventIndex(uint32_t Index) const {
1081   return Index < NumImportedEvents + Events.size();
1082 }
1083
1084 bool WasmObjectFile::isDefinedEventIndex(uint32_t Index) const {
1085   return Index >= NumImportedEvents && isValidEventIndex(Index);
1086 }
1087
1088 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1089   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1090 }
1091
1092 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1093   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1094 }
1095
1096 bool WasmObjectFile::isValidEventSymbol(uint32_t Index) const {
1097   return Index < Symbols.size() && Symbols[Index].isTypeEvent();
1098 }
1099
1100 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1101   return Index < Symbols.size() && Symbols[Index].isTypeData();
1102 }
1103
1104 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1105   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1106 }
1107
1108 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1109   assert(isDefinedFunctionIndex(Index));
1110   return Functions[Index - NumImportedFunctions];
1111 }
1112
1113 const wasm::WasmFunction &
1114 WasmObjectFile::getDefinedFunction(uint32_t Index) const {
1115   assert(isDefinedFunctionIndex(Index));
1116   return Functions[Index - NumImportedFunctions];
1117 }
1118
1119 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1120   assert(isDefinedGlobalIndex(Index));
1121   return Globals[Index - NumImportedGlobals];
1122 }
1123
1124 wasm::WasmEvent &WasmObjectFile::getDefinedEvent(uint32_t Index) {
1125   assert(isDefinedEventIndex(Index));
1126   return Events[Index - NumImportedEvents];
1127 }
1128
1129 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1130   StartFunction = readVaruint32(Ctx);
1131   if (!isValidFunctionIndex(StartFunction))
1132     return make_error<GenericBinaryError>("Invalid start function",
1133                                           object_error::parse_failed);
1134   return Error::success();
1135 }
1136
1137 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1138   CodeSection = Sections.size();
1139   uint32_t FunctionCount = readVaruint32(Ctx);
1140   if (FunctionCount != FunctionTypes.size()) {
1141     return make_error<GenericBinaryError>("Invalid function count",
1142                                           object_error::parse_failed);
1143   }
1144
1145   while (FunctionCount--) {
1146     wasm::WasmFunction Function;
1147     const uint8_t *FunctionStart = Ctx.Ptr;
1148     uint32_t Size = readVaruint32(Ctx);
1149     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1150
1151     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1152     Function.Index = NumImportedFunctions + Functions.size();
1153     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1154     Function.Size = FunctionEnd - FunctionStart;
1155
1156     uint32_t NumLocalDecls = readVaruint32(Ctx);
1157     Function.Locals.reserve(NumLocalDecls);
1158     while (NumLocalDecls--) {
1159       wasm::WasmLocalDecl Decl;
1160       Decl.Count = readVaruint32(Ctx);
1161       Decl.Type = readUint8(Ctx);
1162       Function.Locals.push_back(Decl);
1163     }
1164
1165     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1166     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1167     // This will be set later when reading in the linking metadata section.
1168     Function.Comdat = UINT32_MAX;
1169     Ctx.Ptr += BodySize;
1170     assert(Ctx.Ptr == FunctionEnd);
1171     Functions.push_back(Function);
1172   }
1173   if (Ctx.Ptr != Ctx.End)
1174     return make_error<GenericBinaryError>("Code section ended prematurely",
1175                                           object_error::parse_failed);
1176   return Error::success();
1177 }
1178
1179 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1180   uint32_t Count = readVaruint32(Ctx);
1181   ElemSegments.reserve(Count);
1182   while (Count--) {
1183     wasm::WasmElemSegment Segment;
1184     Segment.TableIndex = readVaruint32(Ctx);
1185     if (Segment.TableIndex != 0) {
1186       return make_error<GenericBinaryError>("Invalid TableIndex",
1187                                             object_error::parse_failed);
1188     }
1189     if (Error Err = readInitExpr(Segment.Offset, Ctx))
1190       return Err;
1191     uint32_t NumElems = readVaruint32(Ctx);
1192     while (NumElems--) {
1193       Segment.Functions.push_back(readVaruint32(Ctx));
1194     }
1195     ElemSegments.push_back(Segment);
1196   }
1197   if (Ctx.Ptr != Ctx.End)
1198     return make_error<GenericBinaryError>("Elem section ended prematurely",
1199                                           object_error::parse_failed);
1200   return Error::success();
1201 }
1202
1203 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1204   DataSection = Sections.size();
1205   uint32_t Count = readVaruint32(Ctx);
1206   if (DataCount && Count != DataCount.getValue())
1207     return make_error<GenericBinaryError>(
1208         "Number of data segments does not match DataCount section");
1209   DataSegments.reserve(Count);
1210   while (Count--) {
1211     WasmSegment Segment;
1212     Segment.Data.InitFlags = readVaruint32(Ctx);
1213     Segment.Data.MemoryIndex = (Segment.Data.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
1214                                ? readVaruint32(Ctx) : 0;
1215     if ((Segment.Data.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
1216       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1217         return Err;
1218     } else {
1219       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1220       Segment.Data.Offset.Value.Int32 = 0;
1221     }
1222     uint32_t Size = readVaruint32(Ctx);
1223     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1224       return make_error<GenericBinaryError>("Invalid segment size",
1225                                             object_error::parse_failed);
1226     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1227     // The rest of these Data fields are set later, when reading in the linking
1228     // metadata section.
1229     Segment.Data.Alignment = 0;
1230     Segment.Data.LinkerFlags = 0;
1231     Segment.Data.Comdat = UINT32_MAX;
1232     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1233     Ctx.Ptr += Size;
1234     DataSegments.push_back(Segment);
1235   }
1236   if (Ctx.Ptr != Ctx.End)
1237     return make_error<GenericBinaryError>("Data section ended prematurely",
1238                                           object_error::parse_failed);
1239   return Error::success();
1240 }
1241
1242 Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
1243   DataCount = readVaruint32(Ctx);
1244   return Error::success();
1245 }
1246
1247 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1248   return Header;
1249 }
1250
1251 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.b++; }
1252
1253 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1254   uint32_t Result = SymbolRef::SF_None;
1255   const WasmSymbol &Sym = getWasmSymbol(Symb);
1256
1257   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1258   if (Sym.isBindingWeak())
1259     Result |= SymbolRef::SF_Weak;
1260   if (!Sym.isBindingLocal())
1261     Result |= SymbolRef::SF_Global;
1262   if (Sym.isHidden())
1263     Result |= SymbolRef::SF_Hidden;
1264   if (!Sym.isDefined())
1265     Result |= SymbolRef::SF_Undefined;
1266   if (Sym.isTypeFunction())
1267     Result |= SymbolRef::SF_Executable;
1268   return Result;
1269 }
1270
1271 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1272   DataRefImpl Ref;
1273   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1274   Ref.d.b = 0; // Symbol index
1275   return BasicSymbolRef(Ref, this);
1276 }
1277
1278 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1279   DataRefImpl Ref;
1280   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1281   Ref.d.b = Symbols.size(); // Symbol index
1282   return BasicSymbolRef(Ref, this);
1283 }
1284
1285 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1286   return Symbols[Symb.d.b];
1287 }
1288
1289 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1290   return getWasmSymbol(Symb.getRawDataRefImpl());
1291 }
1292
1293 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1294   return getWasmSymbol(Symb).Info.Name;
1295 }
1296
1297 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1298   auto &Sym = getWasmSymbol(Symb);
1299   if (Sym.Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION &&
1300       isDefinedFunctionIndex(Sym.Info.ElementIndex))
1301     return getDefinedFunction(Sym.Info.ElementIndex).CodeSectionOffset;
1302   else
1303     return getSymbolValue(Symb);
1304 }
1305
1306 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1307   switch (Sym.Info.Kind) {
1308   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1309   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1310   case wasm::WASM_SYMBOL_TYPE_EVENT:
1311     return Sym.Info.ElementIndex;
1312   case wasm::WASM_SYMBOL_TYPE_DATA: {
1313     // The value of a data symbol is the segment offset, plus the symbol
1314     // offset within the segment.
1315     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1316     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1317     assert(Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST);
1318     return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1319   }
1320   case wasm::WASM_SYMBOL_TYPE_SECTION:
1321     return 0;
1322   }
1323   llvm_unreachable("invalid symbol type");
1324 }
1325
1326 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1327   return getWasmSymbolValue(getWasmSymbol(Symb));
1328 }
1329
1330 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1331   llvm_unreachable("not yet implemented");
1332   return 0;
1333 }
1334
1335 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1336   llvm_unreachable("not yet implemented");
1337   return 0;
1338 }
1339
1340 Expected<SymbolRef::Type>
1341 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1342   const WasmSymbol &Sym = getWasmSymbol(Symb);
1343
1344   switch (Sym.Info.Kind) {
1345   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1346     return SymbolRef::ST_Function;
1347   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1348     return SymbolRef::ST_Other;
1349   case wasm::WASM_SYMBOL_TYPE_DATA:
1350     return SymbolRef::ST_Data;
1351   case wasm::WASM_SYMBOL_TYPE_SECTION:
1352     return SymbolRef::ST_Debug;
1353   case wasm::WASM_SYMBOL_TYPE_EVENT:
1354     return SymbolRef::ST_Other;
1355   }
1356
1357   llvm_unreachable("Unknown WasmSymbol::SymbolType");
1358   return SymbolRef::ST_Other;
1359 }
1360
1361 Expected<section_iterator>
1362 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1363   const WasmSymbol &Sym = getWasmSymbol(Symb);
1364   if (Sym.isUndefined())
1365     return section_end();
1366
1367   DataRefImpl Ref;
1368   switch (Sym.Info.Kind) {
1369   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1370     Ref.d.a = CodeSection;
1371     break;
1372   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1373     Ref.d.a = GlobalSection;
1374     break;
1375   case wasm::WASM_SYMBOL_TYPE_DATA:
1376     Ref.d.a = DataSection;
1377     break;
1378   case wasm::WASM_SYMBOL_TYPE_SECTION:
1379     Ref.d.a = Sym.Info.ElementIndex;
1380     break;
1381   case wasm::WASM_SYMBOL_TYPE_EVENT:
1382     Ref.d.a = EventSection;
1383     break;
1384   default:
1385     llvm_unreachable("Unknown WasmSymbol::SymbolType");
1386   }
1387   return section_iterator(SectionRef(Ref, this));
1388 }
1389
1390 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1391
1392 Expected<StringRef> WasmObjectFile::getSectionName(DataRefImpl Sec) const {
1393   const WasmSection &S = Sections[Sec.d.a];
1394 #define ECase(X)                                                               \
1395   case wasm::WASM_SEC_##X:                                                     \
1396     return #X;
1397   switch (S.Type) {
1398     ECase(TYPE);
1399     ECase(IMPORT);
1400     ECase(FUNCTION);
1401     ECase(TABLE);
1402     ECase(MEMORY);
1403     ECase(GLOBAL);
1404     ECase(EVENT);
1405     ECase(EXPORT);
1406     ECase(START);
1407     ECase(ELEM);
1408     ECase(CODE);
1409     ECase(DATA);
1410     ECase(DATACOUNT);
1411   case wasm::WASM_SEC_CUSTOM:
1412     return S.Name;
1413   default:
1414     return createStringError(object_error::invalid_section_index, "");
1415   }
1416 #undef ECase
1417 }
1418
1419 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1420
1421 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1422   return Sec.d.a;
1423 }
1424
1425 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1426   const WasmSection &S = Sections[Sec.d.a];
1427   return S.Content.size();
1428 }
1429
1430 Expected<ArrayRef<uint8_t>>
1431 WasmObjectFile::getSectionContents(DataRefImpl Sec) const {
1432   const WasmSection &S = Sections[Sec.d.a];
1433   // This will never fail since wasm sections can never be empty (user-sections
1434   // must have a name and non-user sections each have a defined structure).
1435   return S.Content;
1436 }
1437
1438 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1439   return 1;
1440 }
1441
1442 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1443   return false;
1444 }
1445
1446 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1447   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1448 }
1449
1450 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1451   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1452 }
1453
1454 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1455
1456 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1457
1458 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
1459
1460 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1461   DataRefImpl RelocRef;
1462   RelocRef.d.a = Ref.d.a;
1463   RelocRef.d.b = 0;
1464   return relocation_iterator(RelocationRef(RelocRef, this));
1465 }
1466
1467 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1468   const WasmSection &Sec = getWasmSection(Ref);
1469   DataRefImpl RelocRef;
1470   RelocRef.d.a = Ref.d.a;
1471   RelocRef.d.b = Sec.Relocations.size();
1472   return relocation_iterator(RelocationRef(RelocRef, this));
1473 }
1474
1475 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1476
1477 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1478   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1479   return Rel.Offset;
1480 }
1481
1482 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1483   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1484   if (Rel.Type == wasm::R_WASM_TYPE_INDEX_LEB)
1485     return symbol_end();
1486   DataRefImpl Sym;
1487   Sym.d.a = 1;
1488   Sym.d.b = Rel.Index;
1489   return symbol_iterator(SymbolRef(Sym, this));
1490 }
1491
1492 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1493   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1494   return Rel.Type;
1495 }
1496
1497 void WasmObjectFile::getRelocationTypeName(
1498     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1499   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1500   StringRef Res = "Unknown";
1501
1502 #define WASM_RELOC(name, value)                                                \
1503   case wasm::name:                                                             \
1504     Res = #name;                                                               \
1505     break;
1506
1507   switch (Rel.Type) {
1508 #include "llvm/BinaryFormat/WasmRelocs.def"
1509   }
1510
1511 #undef WASM_RELOC
1512
1513   Result.append(Res.begin(), Res.end());
1514 }
1515
1516 section_iterator WasmObjectFile::section_begin() const {
1517   DataRefImpl Ref;
1518   Ref.d.a = 0;
1519   return section_iterator(SectionRef(Ref, this));
1520 }
1521
1522 section_iterator WasmObjectFile::section_end() const {
1523   DataRefImpl Ref;
1524   Ref.d.a = Sections.size();
1525   return section_iterator(SectionRef(Ref, this));
1526 }
1527
1528 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
1529
1530 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1531
1532 Triple::ArchType WasmObjectFile::getArch() const { return Triple::wasm32; }
1533
1534 SubtargetFeatures WasmObjectFile::getFeatures() const {
1535   return SubtargetFeatures();
1536 }
1537
1538 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1539
1540 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1541
1542 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1543   assert(Ref.d.a < Sections.size());
1544   return Sections[Ref.d.a];
1545 }
1546
1547 const WasmSection &
1548 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1549   return getWasmSection(Section.getRawDataRefImpl());
1550 }
1551
1552 const wasm::WasmRelocation &
1553 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1554   return getWasmRelocation(Ref.getRawDataRefImpl());
1555 }
1556
1557 const wasm::WasmRelocation &
1558 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1559   assert(Ref.d.a < Sections.size());
1560   const WasmSection &Sec = Sections[Ref.d.a];
1561   assert(Ref.d.b < Sec.Relocations.size());
1562   return Sec.Relocations[Ref.d.b];
1563 }
1564
1565 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1566                                              StringRef CustomSectionName) {
1567   switch (ID) {
1568   case wasm::WASM_SEC_CUSTOM:
1569     return StringSwitch<unsigned>(CustomSectionName)
1570         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1571         .Case("linking", WASM_SEC_ORDER_LINKING)
1572         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1573         .Case("name", WASM_SEC_ORDER_NAME)
1574         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1575         .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
1576         .Default(WASM_SEC_ORDER_NONE);
1577   case wasm::WASM_SEC_TYPE:
1578     return WASM_SEC_ORDER_TYPE;
1579   case wasm::WASM_SEC_IMPORT:
1580     return WASM_SEC_ORDER_IMPORT;
1581   case wasm::WASM_SEC_FUNCTION:
1582     return WASM_SEC_ORDER_FUNCTION;
1583   case wasm::WASM_SEC_TABLE:
1584     return WASM_SEC_ORDER_TABLE;
1585   case wasm::WASM_SEC_MEMORY:
1586     return WASM_SEC_ORDER_MEMORY;
1587   case wasm::WASM_SEC_GLOBAL:
1588     return WASM_SEC_ORDER_GLOBAL;
1589   case wasm::WASM_SEC_EXPORT:
1590     return WASM_SEC_ORDER_EXPORT;
1591   case wasm::WASM_SEC_START:
1592     return WASM_SEC_ORDER_START;
1593   case wasm::WASM_SEC_ELEM:
1594     return WASM_SEC_ORDER_ELEM;
1595   case wasm::WASM_SEC_CODE:
1596     return WASM_SEC_ORDER_CODE;
1597   case wasm::WASM_SEC_DATA:
1598     return WASM_SEC_ORDER_DATA;
1599   case wasm::WASM_SEC_DATACOUNT:
1600     return WASM_SEC_ORDER_DATACOUNT;
1601   case wasm::WASM_SEC_EVENT:
1602     return WASM_SEC_ORDER_EVENT;
1603   default:
1604     return WASM_SEC_ORDER_NONE;
1605   }
1606 }
1607
1608 // Represents the edges in a directed graph where any node B reachable from node
1609 // A is not allowed to appear before A in the section ordering, but may appear
1610 // afterward.
1611 int WasmSectionOrderChecker::DisallowedPredecessors[WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
1612   {}, // WASM_SEC_ORDER_NONE
1613   {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT}, // WASM_SEC_ORDER_TYPE,
1614   {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION}, // WASM_SEC_ORDER_IMPORT,
1615   {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE}, // WASM_SEC_ORDER_FUNCTION,
1616   {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY}, // WASM_SEC_ORDER_TABLE,
1617   {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_GLOBAL}, // WASM_SEC_ORDER_MEMORY,
1618   {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EVENT}, // WASM_SEC_ORDER_GLOBAL,
1619   {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_EXPORT}, // WASM_SEC_ORDER_EVENT,
1620   {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START}, // WASM_SEC_ORDER_EXPORT,
1621   {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM}, // WASM_SEC_ORDER_START,
1622   {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT}, // WASM_SEC_ORDER_ELEM,
1623   {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE}, // WASM_SEC_ORDER_DATACOUNT,
1624   {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA}, // WASM_SEC_ORDER_CODE,
1625   {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING}, // WASM_SEC_ORDER_DATA,
1626
1627   // Custom Sections
1628   {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE}, // WASM_SEC_ORDER_DYLINK,
1629   {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME}, // WASM_SEC_ORDER_LINKING,
1630   {}, // WASM_SEC_ORDER_RELOC (can be repeated),
1631   {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS}, // WASM_SEC_ORDER_NAME,
1632   {WASM_SEC_ORDER_PRODUCERS, WASM_SEC_ORDER_TARGET_FEATURES}, // WASM_SEC_ORDER_PRODUCERS,
1633   {WASM_SEC_ORDER_TARGET_FEATURES}  // WASM_SEC_ORDER_TARGET_FEATURES
1634 };
1635
1636 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1637                                                   StringRef CustomSectionName) {
1638   int Order = getSectionOrder(ID, CustomSectionName);
1639   if (Order == WASM_SEC_ORDER_NONE)
1640     return true;
1641
1642   // Disallowed predecessors we need to check for
1643   SmallVector<int, WASM_NUM_SEC_ORDERS> WorkList;
1644
1645   // Keep track of completed checks to avoid repeating work
1646   bool Checked[WASM_NUM_SEC_ORDERS] = {};
1647
1648   int Curr = Order;
1649   while (true) {
1650     // Add new disallowed predecessors to work list
1651     for (size_t I = 0;; ++I) {
1652       int Next = DisallowedPredecessors[Curr][I];
1653       if (Next == WASM_SEC_ORDER_NONE)
1654         break;
1655       if (Checked[Next])
1656         continue;
1657       WorkList.push_back(Next);
1658       Checked[Next] = true;
1659     }
1660
1661     if (WorkList.empty())
1662       break;
1663
1664     // Consider next disallowed predecessor
1665     Curr = WorkList.pop_back_val();
1666     if (Seen[Curr])
1667       return false;
1668   }
1669
1670   // Have not seen any disallowed predecessors
1671   Seen[Order] = true;
1672   return true;
1673 }