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/StringSwitch.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/BinaryFormat/Wasm.h"
18 #include "llvm/MC/SubtargetFeature.h"
19 #include "llvm/Object/Binary.h"
20 #include "llvm/Object/Error.h"
21 #include "llvm/Object/ObjectFile.h"
22 #include "llvm/Object/SymbolicFile.h"
23 #include "llvm/Object/Wasm.h"
24 #include "llvm/Support/Endian.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/LEB128.h"
28 #include "llvm/Support/ScopedPrinter.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cstdint>
32 #include <cstring>
33 #include <system_error>
34 
35 #define DEBUG_TYPE "wasm-object"
36 
37 using namespace llvm;
38 using namespace object;
39 
40 void WasmSymbol::print(raw_ostream &Out) const {
41   Out << "Name=" << Info.Name
42       << ", Kind=" << toString(wasm::WasmSymbolType(Info.Kind))
43       << ", Flags=" << Info.Flags;
44   if (!isTypeData()) {
45     Out << ", ElemIndex=" << Info.ElementIndex;
46   } else if (isDefined()) {
47     Out << ", Segment=" << Info.DataRef.Segment;
48     Out << ", Offset=" << Info.DataRef.Offset;
49     Out << ", Size=" << Info.DataRef.Size;
50   }
51 }
52 
53 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
54 LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
55 #endif
56 
57 Expected<std::unique_ptr<WasmObjectFile>>
58 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
59   Error Err = Error::success();
60   auto ObjectFile = std::make_unique<WasmObjectFile>(Buffer, Err);
61   if (Err)
62     return std::move(Err);
63 
64   return std::move(ObjectFile);
65 }
66 
67 #define VARINT7_MAX ((1 << 7) - 1)
68 #define VARINT7_MIN (-(1 << 7))
69 #define VARUINT7_MAX (1 << 7)
70 #define VARUINT1_MAX (1)
71 
72 static uint8_t readUint8(WasmObjectFile::ReadContext &Ctx) {
73   if (Ctx.Ptr == Ctx.End)
74     report_fatal_error("EOF while reading uint8");
75   return *Ctx.Ptr++;
76 }
77 
78 static uint32_t readUint32(WasmObjectFile::ReadContext &Ctx) {
79   if (Ctx.Ptr + 4 > Ctx.End)
80     report_fatal_error("EOF while reading uint32");
81   uint32_t Result = support::endian::read32le(Ctx.Ptr);
82   Ctx.Ptr += 4;
83   return Result;
84 }
85 
86 static int32_t readFloat32(WasmObjectFile::ReadContext &Ctx) {
87   if (Ctx.Ptr + 4 > Ctx.End)
88     report_fatal_error("EOF while reading float64");
89   int32_t Result = 0;
90   memcpy(&Result, Ctx.Ptr, sizeof(Result));
91   Ctx.Ptr += sizeof(Result);
92   return Result;
93 }
94 
95 static int64_t readFloat64(WasmObjectFile::ReadContext &Ctx) {
96   if (Ctx.Ptr + 8 > Ctx.End)
97     report_fatal_error("EOF while reading float64");
98   int64_t Result = 0;
99   memcpy(&Result, Ctx.Ptr, sizeof(Result));
100   Ctx.Ptr += sizeof(Result);
101   return Result;
102 }
103 
104 static uint64_t readULEB128(WasmObjectFile::ReadContext &Ctx) {
105   unsigned Count;
106   const char *Error = nullptr;
107   uint64_t Result = decodeULEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
108   if (Error)
109     report_fatal_error(Error);
110   Ctx.Ptr += Count;
111   return Result;
112 }
113 
114 static StringRef readString(WasmObjectFile::ReadContext &Ctx) {
115   uint32_t StringLen = readULEB128(Ctx);
116   if (Ctx.Ptr + StringLen > Ctx.End)
117     report_fatal_error("EOF while reading string");
118   StringRef Return =
119       StringRef(reinterpret_cast<const char *>(Ctx.Ptr), StringLen);
120   Ctx.Ptr += StringLen;
121   return Return;
122 }
123 
124 static int64_t readLEB128(WasmObjectFile::ReadContext &Ctx) {
125   unsigned Count;
126   const char *Error = nullptr;
127   uint64_t Result = decodeSLEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
128   if (Error)
129     report_fatal_error(Error);
130   Ctx.Ptr += Count;
131   return Result;
132 }
133 
134 static uint8_t readVaruint1(WasmObjectFile::ReadContext &Ctx) {
135   int64_t Result = readLEB128(Ctx);
136   if (Result > VARUINT1_MAX || Result < 0)
137     report_fatal_error("LEB is outside Varuint1 range");
138   return Result;
139 }
140 
141 static int32_t readVarint32(WasmObjectFile::ReadContext &Ctx) {
142   int64_t Result = readLEB128(Ctx);
143   if (Result > INT32_MAX || Result < INT32_MIN)
144     report_fatal_error("LEB is outside Varint32 range");
145   return Result;
146 }
147 
148 static uint32_t readVaruint32(WasmObjectFile::ReadContext &Ctx) {
149   uint64_t Result = readULEB128(Ctx);
150   if (Result > UINT32_MAX)
151     report_fatal_error("LEB is outside Varuint32 range");
152   return Result;
153 }
154 
155 static int64_t readVarint64(WasmObjectFile::ReadContext &Ctx) {
156   return readLEB128(Ctx);
157 }
158 
159 static uint64_t readVaruint64(WasmObjectFile::ReadContext &Ctx) {
160   return readULEB128(Ctx);
161 }
162 
163 static uint8_t readOpcode(WasmObjectFile::ReadContext &Ctx) {
164   return readUint8(Ctx);
165 }
166 
167 static Error readInitExpr(wasm::WasmInitExpr &Expr,
168                           WasmObjectFile::ReadContext &Ctx) {
169   Expr.Opcode = readOpcode(Ctx);
170 
171   switch (Expr.Opcode) {
172   case wasm::WASM_OPCODE_I32_CONST:
173     Expr.Value.Int32 = readVarint32(Ctx);
174     break;
175   case wasm::WASM_OPCODE_I64_CONST:
176     Expr.Value.Int64 = readVarint64(Ctx);
177     break;
178   case wasm::WASM_OPCODE_F32_CONST:
179     Expr.Value.Float32 = readFloat32(Ctx);
180     break;
181   case wasm::WASM_OPCODE_F64_CONST:
182     Expr.Value.Float64 = readFloat64(Ctx);
183     break;
184   case wasm::WASM_OPCODE_GLOBAL_GET:
185     Expr.Value.Global = readULEB128(Ctx);
186     break;
187   case wasm::WASM_OPCODE_REF_NULL: {
188     wasm::ValType Ty = static_cast<wasm::ValType>(readULEB128(Ctx));
189     if (Ty != wasm::ValType::EXTERNREF) {
190       return make_error<GenericBinaryError>("Invalid type for ref.null",
191                                             object_error::parse_failed);
192     }
193     break;
194   }
195   default:
196     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
197                                           object_error::parse_failed);
198   }
199 
200   uint8_t EndOpcode = readOpcode(Ctx);
201   if (EndOpcode != wasm::WASM_OPCODE_END) {
202     return make_error<GenericBinaryError>("Invalid init_expr",
203                                           object_error::parse_failed);
204   }
205   return Error::success();
206 }
207 
208 static wasm::WasmLimits readLimits(WasmObjectFile::ReadContext &Ctx) {
209   wasm::WasmLimits Result;
210   Result.Flags = readVaruint32(Ctx);
211   Result.Initial = readVaruint64(Ctx);
212   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
213     Result.Maximum = readVaruint64(Ctx);
214   return Result;
215 }
216 
217 static wasm::WasmTable readTable(WasmObjectFile::ReadContext &Ctx) {
218   wasm::WasmTable Table;
219   Table.ElemType = readUint8(Ctx);
220   Table.Limits = readLimits(Ctx);
221   // The caller needs to set Table.Index field for Table
222   return Table;
223 }
224 
225 static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
226                          WasmSectionOrderChecker &Checker) {
227   Section.Offset = Ctx.Ptr - Ctx.Start;
228   Section.Type = readUint8(Ctx);
229   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
230   uint32_t Size = readVaruint32(Ctx);
231   if (Size == 0)
232     return make_error<StringError>("Zero length section",
233                                    object_error::parse_failed);
234   if (Ctx.Ptr + Size > Ctx.End)
235     return make_error<StringError>("Section too large",
236                                    object_error::parse_failed);
237   if (Section.Type == wasm::WASM_SEC_CUSTOM) {
238     WasmObjectFile::ReadContext SectionCtx;
239     SectionCtx.Start = Ctx.Ptr;
240     SectionCtx.Ptr = Ctx.Ptr;
241     SectionCtx.End = Ctx.Ptr + Size;
242 
243     Section.Name = readString(SectionCtx);
244 
245     uint32_t SectionNameSize = SectionCtx.Ptr - SectionCtx.Start;
246     Ctx.Ptr += SectionNameSize;
247     Size -= SectionNameSize;
248   }
249 
250   if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
251     return make_error<StringError>("Out of order section type: " +
252                                        llvm::to_string(Section.Type),
253                                    object_error::parse_failed);
254   }
255 
256   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
257   Ctx.Ptr += Size;
258   return Error::success();
259 }
260 
261 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
262     : ObjectFile(Binary::ID_Wasm, Buffer) {
263   ErrorAsOutParameter ErrAsOutParam(&Err);
264   Header.Magic = getData().substr(0, 4);
265   if (Header.Magic != StringRef("\0asm", 4)) {
266     Err =
267         make_error<StringError>("Bad magic number", object_error::parse_failed);
268     return;
269   }
270 
271   ReadContext Ctx;
272   Ctx.Start = getData().bytes_begin();
273   Ctx.Ptr = Ctx.Start + 4;
274   Ctx.End = Ctx.Start + getData().size();
275 
276   if (Ctx.Ptr + 4 > Ctx.End) {
277     Err = make_error<StringError>("Missing version number",
278                                   object_error::parse_failed);
279     return;
280   }
281 
282   Header.Version = readUint32(Ctx);
283   if (Header.Version != wasm::WasmVersion) {
284     Err = make_error<StringError>("Bad version number",
285                                   object_error::parse_failed);
286     return;
287   }
288 
289   WasmSection Sec;
290   WasmSectionOrderChecker Checker;
291   while (Ctx.Ptr < Ctx.End) {
292     if ((Err = readSection(Sec, Ctx, Checker)))
293       return;
294     if ((Err = parseSection(Sec)))
295       return;
296 
297     Sections.push_back(Sec);
298   }
299 }
300 
301 Error WasmObjectFile::parseSection(WasmSection &Sec) {
302   ReadContext Ctx;
303   Ctx.Start = Sec.Content.data();
304   Ctx.End = Ctx.Start + Sec.Content.size();
305   Ctx.Ptr = Ctx.Start;
306   switch (Sec.Type) {
307   case wasm::WASM_SEC_CUSTOM:
308     return parseCustomSection(Sec, Ctx);
309   case wasm::WASM_SEC_TYPE:
310     return parseTypeSection(Ctx);
311   case wasm::WASM_SEC_IMPORT:
312     return parseImportSection(Ctx);
313   case wasm::WASM_SEC_FUNCTION:
314     return parseFunctionSection(Ctx);
315   case wasm::WASM_SEC_TABLE:
316     return parseTableSection(Ctx);
317   case wasm::WASM_SEC_MEMORY:
318     return parseMemorySection(Ctx);
319   case wasm::WASM_SEC_EVENT:
320     return parseEventSection(Ctx);
321   case wasm::WASM_SEC_GLOBAL:
322     return parseGlobalSection(Ctx);
323   case wasm::WASM_SEC_EXPORT:
324     return parseExportSection(Ctx);
325   case wasm::WASM_SEC_START:
326     return parseStartSection(Ctx);
327   case wasm::WASM_SEC_ELEM:
328     return parseElemSection(Ctx);
329   case wasm::WASM_SEC_CODE:
330     return parseCodeSection(Ctx);
331   case wasm::WASM_SEC_DATA:
332     return parseDataSection(Ctx);
333   case wasm::WASM_SEC_DATACOUNT:
334     return parseDataCountSection(Ctx);
335   default:
336     return make_error<GenericBinaryError>(
337         "Invalid section type: " + Twine(Sec.Type), object_error::parse_failed);
338   }
339 }
340 
341 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
342   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
343   HasDylinkSection = true;
344   DylinkInfo.MemorySize = readVaruint32(Ctx);
345   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
346   DylinkInfo.TableSize = readVaruint32(Ctx);
347   DylinkInfo.TableAlignment = readVaruint32(Ctx);
348   uint32_t Count = readVaruint32(Ctx);
349   while (Count--) {
350     DylinkInfo.Needed.push_back(readString(Ctx));
351   }
352   if (Ctx.Ptr != Ctx.End)
353     return make_error<GenericBinaryError>("dylink section ended prematurely",
354                                           object_error::parse_failed);
355   return Error::success();
356 }
357 
358 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
359   llvm::DenseSet<uint64_t> Seen;
360   if (FunctionTypes.size() && !SeenCodeSection) {
361     return make_error<GenericBinaryError>("Names must come after code section",
362                                           object_error::parse_failed);
363   }
364 
365   while (Ctx.Ptr < Ctx.End) {
366     uint8_t Type = readUint8(Ctx);
367     uint32_t Size = readVaruint32(Ctx);
368     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
369     switch (Type) {
370     case wasm::WASM_NAMES_FUNCTION: {
371       uint32_t Count = readVaruint32(Ctx);
372       while (Count--) {
373         uint32_t Index = readVaruint32(Ctx);
374         if (!Seen.insert(Index).second)
375           return make_error<GenericBinaryError>("Function named more than once",
376                                                 object_error::parse_failed);
377         StringRef Name = readString(Ctx);
378         if (!isValidFunctionIndex(Index) || Name.empty())
379           return make_error<GenericBinaryError>("Invalid name entry",
380                                                 object_error::parse_failed);
381         DebugNames.push_back(wasm::WasmFunctionName{Index, Name});
382         if (isDefinedFunctionIndex(Index))
383           getDefinedFunction(Index).DebugName = Name;
384       }
385       break;
386     }
387     // Ignore local names for now
388     case wasm::WASM_NAMES_LOCAL:
389     default:
390       Ctx.Ptr += Size;
391       break;
392     }
393     if (Ctx.Ptr != SubSectionEnd)
394       return make_error<GenericBinaryError>(
395           "Name sub-section ended prematurely", object_error::parse_failed);
396   }
397 
398   if (Ctx.Ptr != Ctx.End)
399     return make_error<GenericBinaryError>("Name section ended prematurely",
400                                           object_error::parse_failed);
401   return Error::success();
402 }
403 
404 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
405   HasLinkingSection = true;
406   if (FunctionTypes.size() && !SeenCodeSection) {
407     return make_error<GenericBinaryError>(
408         "Linking data must come after code section",
409         object_error::parse_failed);
410   }
411 
412   LinkingData.Version = readVaruint32(Ctx);
413   if (LinkingData.Version != wasm::WasmMetadataVersion) {
414     return make_error<GenericBinaryError>(
415         "Unexpected metadata version: " + Twine(LinkingData.Version) +
416             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
417         object_error::parse_failed);
418   }
419 
420   const uint8_t *OrigEnd = Ctx.End;
421   while (Ctx.Ptr < OrigEnd) {
422     Ctx.End = OrigEnd;
423     uint8_t Type = readUint8(Ctx);
424     uint32_t Size = readVaruint32(Ctx);
425     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
426                       << "\n");
427     Ctx.End = Ctx.Ptr + Size;
428     switch (Type) {
429     case wasm::WASM_SYMBOL_TABLE:
430       if (Error Err = parseLinkingSectionSymtab(Ctx))
431         return Err;
432       break;
433     case wasm::WASM_SEGMENT_INFO: {
434       uint32_t Count = readVaruint32(Ctx);
435       if (Count > DataSegments.size())
436         return make_error<GenericBinaryError>("Too many segment names",
437                                               object_error::parse_failed);
438       for (uint32_t I = 0; I < Count; I++) {
439         DataSegments[I].Data.Name = readString(Ctx);
440         DataSegments[I].Data.Alignment = readVaruint32(Ctx);
441         DataSegments[I].Data.LinkerFlags = readVaruint32(Ctx);
442       }
443       break;
444     }
445     case wasm::WASM_INIT_FUNCS: {
446       uint32_t Count = readVaruint32(Ctx);
447       LinkingData.InitFunctions.reserve(Count);
448       for (uint32_t I = 0; I < Count; I++) {
449         wasm::WasmInitFunc Init;
450         Init.Priority = readVaruint32(Ctx);
451         Init.Symbol = readVaruint32(Ctx);
452         if (!isValidFunctionSymbol(Init.Symbol))
453           return make_error<GenericBinaryError>("Invalid function symbol: " +
454                                                     Twine(Init.Symbol),
455                                                 object_error::parse_failed);
456         LinkingData.InitFunctions.emplace_back(Init);
457       }
458       break;
459     }
460     case wasm::WASM_COMDAT_INFO:
461       if (Error Err = parseLinkingSectionComdat(Ctx))
462         return Err;
463       break;
464     default:
465       Ctx.Ptr += Size;
466       break;
467     }
468     if (Ctx.Ptr != Ctx.End)
469       return make_error<GenericBinaryError>(
470           "Linking sub-section ended prematurely", object_error::parse_failed);
471   }
472   if (Ctx.Ptr != OrigEnd)
473     return make_error<GenericBinaryError>("Linking section ended prematurely",
474                                           object_error::parse_failed);
475   return Error::success();
476 }
477 
478 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
479   uint32_t Count = readVaruint32(Ctx);
480   LinkingData.SymbolTable.reserve(Count);
481   Symbols.reserve(Count);
482   StringSet<> SymbolNames;
483 
484   std::vector<wasm::WasmImport *> ImportedGlobals;
485   std::vector<wasm::WasmImport *> ImportedFunctions;
486   std::vector<wasm::WasmImport *> ImportedEvents;
487   ImportedGlobals.reserve(Imports.size());
488   ImportedFunctions.reserve(Imports.size());
489   ImportedEvents.reserve(Imports.size());
490   for (auto &I : Imports) {
491     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
492       ImportedFunctions.emplace_back(&I);
493     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
494       ImportedGlobals.emplace_back(&I);
495     else if (I.Kind == wasm::WASM_EXTERNAL_EVENT)
496       ImportedEvents.emplace_back(&I);
497   }
498 
499   while (Count--) {
500     wasm::WasmSymbolInfo Info;
501     const wasm::WasmSignature *Signature = nullptr;
502     const wasm::WasmGlobalType *GlobalType = nullptr;
503     uint8_t TableType = 0;
504     const wasm::WasmEventType *EventType = nullptr;
505 
506     Info.Kind = readUint8(Ctx);
507     Info.Flags = readVaruint32(Ctx);
508     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
509 
510     switch (Info.Kind) {
511     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
512       Info.ElementIndex = readVaruint32(Ctx);
513       if (!isValidFunctionIndex(Info.ElementIndex) ||
514           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
515         return make_error<GenericBinaryError>("invalid function symbol index",
516                                               object_error::parse_failed);
517       if (IsDefined) {
518         Info.Name = readString(Ctx);
519         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
520         Signature = &Signatures[FunctionTypes[FuncIndex]];
521         wasm::WasmFunction &Function = Functions[FuncIndex];
522         if (Function.SymbolName.empty())
523           Function.SymbolName = Info.Name;
524       } else {
525         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
526         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
527           Info.Name = readString(Ctx);
528           Info.ImportName = Import.Field;
529         } else {
530           Info.Name = Import.Field;
531         }
532         Signature = &Signatures[Import.SigIndex];
533         if (!Import.Module.empty()) {
534           Info.ImportModule = Import.Module;
535         }
536       }
537       break;
538 
539     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
540       Info.ElementIndex = readVaruint32(Ctx);
541       if (!isValidGlobalIndex(Info.ElementIndex) ||
542           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
543         return make_error<GenericBinaryError>("invalid global symbol index",
544                                               object_error::parse_failed);
545       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
546                             wasm::WASM_SYMBOL_BINDING_WEAK)
547         return make_error<GenericBinaryError>("undefined weak global symbol",
548                                               object_error::parse_failed);
549       if (IsDefined) {
550         Info.Name = readString(Ctx);
551         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
552         wasm::WasmGlobal &Global = Globals[GlobalIndex];
553         GlobalType = &Global.Type;
554         if (Global.SymbolName.empty())
555           Global.SymbolName = Info.Name;
556       } else {
557         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
558         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
559           Info.Name = readString(Ctx);
560           Info.ImportName = Import.Field;
561         } else {
562           Info.Name = Import.Field;
563         }
564         GlobalType = &Import.Global;
565         Info.ImportName = Import.Field;
566         if (!Import.Module.empty()) {
567           Info.ImportModule = Import.Module;
568         }
569       }
570       break;
571 
572     case wasm::WASM_SYMBOL_TYPE_TABLE:
573       Info.ElementIndex = readVaruint32(Ctx);
574       if (!isValidTableIndex(Info.ElementIndex) ||
575           IsDefined != isDefinedTableIndex(Info.ElementIndex))
576         return make_error<GenericBinaryError>("invalid table symbol index",
577                                               object_error::parse_failed);
578       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
579                             wasm::WASM_SYMBOL_BINDING_WEAK)
580         return make_error<GenericBinaryError>("undefined weak table symbol",
581                                               object_error::parse_failed);
582       if (IsDefined) {
583         Info.Name = readString(Ctx);
584         unsigned TableIndex = Info.ElementIndex - NumImportedTables;
585         wasm::WasmTable &Table = Tables[TableIndex];
586         TableType = Table.ElemType;
587       } else {
588         return make_error<GenericBinaryError>("undefined table symbol",
589                                               object_error::parse_failed);
590       }
591       break;
592 
593     case wasm::WASM_SYMBOL_TYPE_DATA:
594       Info.Name = readString(Ctx);
595       if (IsDefined) {
596         auto Index = readVaruint32(Ctx);
597         if (Index >= DataSegments.size())
598           return make_error<GenericBinaryError>("invalid data symbol index",
599                                                 object_error::parse_failed);
600         auto Offset = readVaruint64(Ctx);
601         auto Size = readVaruint64(Ctx);
602         if (Offset + Size > DataSegments[Index].Data.Content.size())
603           return make_error<GenericBinaryError>("invalid data symbol offset",
604                                                 object_error::parse_failed);
605         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
606       }
607       break;
608 
609     case wasm::WASM_SYMBOL_TYPE_SECTION: {
610       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
611           wasm::WASM_SYMBOL_BINDING_LOCAL)
612         return make_error<GenericBinaryError>(
613             "Section symbols must have local binding",
614             object_error::parse_failed);
615       Info.ElementIndex = readVaruint32(Ctx);
616       // Use somewhat unique section name as symbol name.
617       StringRef SectionName = Sections[Info.ElementIndex].Name;
618       Info.Name = SectionName;
619       break;
620     }
621 
622     case wasm::WASM_SYMBOL_TYPE_EVENT: {
623       Info.ElementIndex = readVaruint32(Ctx);
624       if (!isValidEventIndex(Info.ElementIndex) ||
625           IsDefined != isDefinedEventIndex(Info.ElementIndex))
626         return make_error<GenericBinaryError>("invalid event symbol index",
627                                               object_error::parse_failed);
628       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
629                             wasm::WASM_SYMBOL_BINDING_WEAK)
630         return make_error<GenericBinaryError>("undefined weak global symbol",
631                                               object_error::parse_failed);
632       if (IsDefined) {
633         Info.Name = readString(Ctx);
634         unsigned EventIndex = Info.ElementIndex - NumImportedEvents;
635         wasm::WasmEvent &Event = Events[EventIndex];
636         Signature = &Signatures[Event.Type.SigIndex];
637         EventType = &Event.Type;
638         if (Event.SymbolName.empty())
639           Event.SymbolName = Info.Name;
640 
641       } else {
642         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
643         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
644           Info.Name = readString(Ctx);
645           Info.ImportName = Import.Field;
646         } else {
647           Info.Name = Import.Field;
648         }
649         EventType = &Import.Event;
650         Signature = &Signatures[EventType->SigIndex];
651         if (!Import.Module.empty()) {
652           Info.ImportModule = Import.Module;
653         }
654       }
655       break;
656     }
657 
658     default:
659       return make_error<GenericBinaryError>("Invalid symbol type",
660                                             object_error::parse_failed);
661     }
662 
663     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
664             wasm::WASM_SYMBOL_BINDING_LOCAL &&
665         !SymbolNames.insert(Info.Name).second)
666       return make_error<GenericBinaryError>("Duplicate symbol name " +
667                                                 Twine(Info.Name),
668                                             object_error::parse_failed);
669     LinkingData.SymbolTable.emplace_back(Info);
670     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, TableType,
671                          EventType, Signature);
672     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
673   }
674 
675   return Error::success();
676 }
677 
678 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
679   uint32_t ComdatCount = readVaruint32(Ctx);
680   StringSet<> ComdatSet;
681   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
682     StringRef Name = readString(Ctx);
683     if (Name.empty() || !ComdatSet.insert(Name).second)
684       return make_error<GenericBinaryError>("Bad/duplicate COMDAT name " +
685                                                 Twine(Name),
686                                             object_error::parse_failed);
687     LinkingData.Comdats.emplace_back(Name);
688     uint32_t Flags = readVaruint32(Ctx);
689     if (Flags != 0)
690       return make_error<GenericBinaryError>("Unsupported COMDAT flags",
691                                             object_error::parse_failed);
692 
693     uint32_t EntryCount = readVaruint32(Ctx);
694     while (EntryCount--) {
695       unsigned Kind = readVaruint32(Ctx);
696       unsigned Index = readVaruint32(Ctx);
697       switch (Kind) {
698       default:
699         return make_error<GenericBinaryError>("Invalid COMDAT entry type",
700                                               object_error::parse_failed);
701       case wasm::WASM_COMDAT_DATA:
702         if (Index >= DataSegments.size())
703           return make_error<GenericBinaryError>(
704               "COMDAT data index out of range", object_error::parse_failed);
705         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
706           return make_error<GenericBinaryError>("Data segment in two COMDATs",
707                                                 object_error::parse_failed);
708         DataSegments[Index].Data.Comdat = ComdatIndex;
709         break;
710       case wasm::WASM_COMDAT_FUNCTION:
711         if (!isDefinedFunctionIndex(Index))
712           return make_error<GenericBinaryError>(
713               "COMDAT function index out of range", object_error::parse_failed);
714         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
715           return make_error<GenericBinaryError>("Function in two COMDATs",
716                                                 object_error::parse_failed);
717         getDefinedFunction(Index).Comdat = ComdatIndex;
718         break;
719       }
720     }
721   }
722   return Error::success();
723 }
724 
725 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
726   llvm::SmallSet<StringRef, 3> FieldsSeen;
727   uint32_t Fields = readVaruint32(Ctx);
728   for (size_t I = 0; I < Fields; ++I) {
729     StringRef FieldName = readString(Ctx);
730     if (!FieldsSeen.insert(FieldName).second)
731       return make_error<GenericBinaryError>(
732           "Producers section does not have unique fields",
733           object_error::parse_failed);
734     std::vector<std::pair<std::string, std::string>> *ProducerVec = nullptr;
735     if (FieldName == "language") {
736       ProducerVec = &ProducerInfo.Languages;
737     } else if (FieldName == "processed-by") {
738       ProducerVec = &ProducerInfo.Tools;
739     } else if (FieldName == "sdk") {
740       ProducerVec = &ProducerInfo.SDKs;
741     } else {
742       return make_error<GenericBinaryError>(
743           "Producers section field is not named one of language, processed-by, "
744           "or sdk",
745           object_error::parse_failed);
746     }
747     uint32_t ValueCount = readVaruint32(Ctx);
748     llvm::SmallSet<StringRef, 8> ProducersSeen;
749     for (size_t J = 0; J < ValueCount; ++J) {
750       StringRef Name = readString(Ctx);
751       StringRef Version = readString(Ctx);
752       if (!ProducersSeen.insert(Name).second) {
753         return make_error<GenericBinaryError>(
754             "Producers section contains repeated producer",
755             object_error::parse_failed);
756       }
757       ProducerVec->emplace_back(std::string(Name), std::string(Version));
758     }
759   }
760   if (Ctx.Ptr != Ctx.End)
761     return make_error<GenericBinaryError>("Producers section ended prematurely",
762                                           object_error::parse_failed);
763   return Error::success();
764 }
765 
766 Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
767   llvm::SmallSet<std::string, 8> FeaturesSeen;
768   uint32_t FeatureCount = readVaruint32(Ctx);
769   for (size_t I = 0; I < FeatureCount; ++I) {
770     wasm::WasmFeatureEntry Feature;
771     Feature.Prefix = readUint8(Ctx);
772     switch (Feature.Prefix) {
773     case wasm::WASM_FEATURE_PREFIX_USED:
774     case wasm::WASM_FEATURE_PREFIX_REQUIRED:
775     case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
776       break;
777     default:
778       return make_error<GenericBinaryError>("Unknown feature policy prefix",
779                                             object_error::parse_failed);
780     }
781     Feature.Name = std::string(readString(Ctx));
782     if (!FeaturesSeen.insert(Feature.Name).second)
783       return make_error<GenericBinaryError>(
784           "Target features section contains repeated feature \"" +
785               Feature.Name + "\"",
786           object_error::parse_failed);
787     TargetFeatures.push_back(Feature);
788   }
789   if (Ctx.Ptr != Ctx.End)
790     return make_error<GenericBinaryError>(
791         "Target features section ended prematurely",
792         object_error::parse_failed);
793   return Error::success();
794 }
795 
796 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
797   uint32_t SectionIndex = readVaruint32(Ctx);
798   if (SectionIndex >= Sections.size())
799     return make_error<GenericBinaryError>("Invalid section index",
800                                           object_error::parse_failed);
801   WasmSection &Section = Sections[SectionIndex];
802   uint32_t RelocCount = readVaruint32(Ctx);
803   uint32_t EndOffset = Section.Content.size();
804   uint32_t PreviousOffset = 0;
805   while (RelocCount--) {
806     wasm::WasmRelocation Reloc = {};
807     Reloc.Type = readVaruint32(Ctx);
808     Reloc.Offset = readVaruint32(Ctx);
809     if (Reloc.Offset < PreviousOffset)
810       return make_error<GenericBinaryError>("Relocations not in offset order",
811                                             object_error::parse_failed);
812     PreviousOffset = Reloc.Offset;
813     Reloc.Index = readVaruint32(Ctx);
814     switch (Reloc.Type) {
815     case wasm::R_WASM_FUNCTION_INDEX_LEB:
816     case wasm::R_WASM_TABLE_INDEX_SLEB:
817     case wasm::R_WASM_TABLE_INDEX_SLEB64:
818     case wasm::R_WASM_TABLE_INDEX_I32:
819     case wasm::R_WASM_TABLE_INDEX_I64:
820     case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
821       if (!isValidFunctionSymbol(Reloc.Index))
822         return make_error<GenericBinaryError>("Bad relocation function index",
823                                               object_error::parse_failed);
824       break;
825     case wasm::R_WASM_TABLE_NUMBER_LEB:
826       if (!isValidTableSymbol(Reloc.Index))
827         return make_error<GenericBinaryError>("Bad relocation table index",
828                                               object_error::parse_failed);
829       break;
830     case wasm::R_WASM_TYPE_INDEX_LEB:
831       if (Reloc.Index >= Signatures.size())
832         return make_error<GenericBinaryError>("Bad relocation type index",
833                                               object_error::parse_failed);
834       break;
835     case wasm::R_WASM_GLOBAL_INDEX_LEB:
836       // R_WASM_GLOBAL_INDEX_LEB are can be used against function and data
837       // symbols to refer to their GOT entries.
838       if (!isValidGlobalSymbol(Reloc.Index) &&
839           !isValidDataSymbol(Reloc.Index) &&
840           !isValidFunctionSymbol(Reloc.Index))
841         return make_error<GenericBinaryError>("Bad relocation global index",
842                                               object_error::parse_failed);
843       break;
844     case wasm::R_WASM_GLOBAL_INDEX_I32:
845       if (!isValidGlobalSymbol(Reloc.Index))
846         return make_error<GenericBinaryError>("Bad relocation global index",
847                                               object_error::parse_failed);
848       break;
849     case wasm::R_WASM_EVENT_INDEX_LEB:
850       if (!isValidEventSymbol(Reloc.Index))
851         return make_error<GenericBinaryError>("Bad relocation event index",
852                                               object_error::parse_failed);
853       break;
854     case wasm::R_WASM_MEMORY_ADDR_LEB:
855     case wasm::R_WASM_MEMORY_ADDR_SLEB:
856     case wasm::R_WASM_MEMORY_ADDR_I32:
857     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
858     case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
859       if (!isValidDataSymbol(Reloc.Index))
860         return make_error<GenericBinaryError>("Bad relocation data index",
861                                               object_error::parse_failed);
862       Reloc.Addend = readVarint32(Ctx);
863       break;
864     case wasm::R_WASM_MEMORY_ADDR_LEB64:
865     case wasm::R_WASM_MEMORY_ADDR_SLEB64:
866     case wasm::R_WASM_MEMORY_ADDR_I64:
867     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
868       if (!isValidDataSymbol(Reloc.Index))
869         return make_error<GenericBinaryError>("Bad relocation data index",
870                                               object_error::parse_failed);
871       Reloc.Addend = readVarint64(Ctx);
872       break;
873     case wasm::R_WASM_FUNCTION_OFFSET_I32:
874       if (!isValidFunctionSymbol(Reloc.Index))
875         return make_error<GenericBinaryError>("Bad relocation function index",
876                                               object_error::parse_failed);
877       Reloc.Addend = readVarint32(Ctx);
878       break;
879     case wasm::R_WASM_FUNCTION_OFFSET_I64:
880       if (!isValidFunctionSymbol(Reloc.Index))
881         return make_error<GenericBinaryError>("Bad relocation function index",
882                                               object_error::parse_failed);
883       Reloc.Addend = readVarint64(Ctx);
884       break;
885     case wasm::R_WASM_SECTION_OFFSET_I32:
886       if (!isValidSectionSymbol(Reloc.Index))
887         return make_error<GenericBinaryError>("Bad relocation section index",
888                                               object_error::parse_failed);
889       Reloc.Addend = readVarint32(Ctx);
890       break;
891     default:
892       return make_error<GenericBinaryError>("Bad relocation type: " +
893                                                 Twine(Reloc.Type),
894                                             object_error::parse_failed);
895     }
896 
897     // Relocations must fit inside the section, and must appear in order.  They
898     // also shouldn't overlap a function/element boundary, but we don't bother
899     // to check that.
900     uint64_t Size = 5;
901     if (Reloc.Type == wasm::R_WASM_MEMORY_ADDR_LEB64 ||
902         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_SLEB64 ||
903         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_REL_SLEB64)
904       Size = 10;
905     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I32 ||
906         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I32 ||
907         Reloc.Type == wasm::R_WASM_SECTION_OFFSET_I32 ||
908         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
909         Reloc.Type == wasm::R_WASM_GLOBAL_INDEX_I32)
910       Size = 4;
911     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I64 ||
912         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64 ||
913         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I64)
914       Size = 8;
915     if (Reloc.Offset + Size > EndOffset)
916       return make_error<GenericBinaryError>("Bad relocation offset",
917                                             object_error::parse_failed);
918 
919     Section.Relocations.push_back(Reloc);
920   }
921   if (Ctx.Ptr != Ctx.End)
922     return make_error<GenericBinaryError>("Reloc section ended prematurely",
923                                           object_error::parse_failed);
924   return Error::success();
925 }
926 
927 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
928   if (Sec.Name == "dylink") {
929     if (Error Err = parseDylinkSection(Ctx))
930       return Err;
931   } else if (Sec.Name == "name") {
932     if (Error Err = parseNameSection(Ctx))
933       return Err;
934   } else if (Sec.Name == "linking") {
935     if (Error Err = parseLinkingSection(Ctx))
936       return Err;
937   } else if (Sec.Name == "producers") {
938     if (Error Err = parseProducersSection(Ctx))
939       return Err;
940   } else if (Sec.Name == "target_features") {
941     if (Error Err = parseTargetFeaturesSection(Ctx))
942       return Err;
943   } else if (Sec.Name.startswith("reloc.")) {
944     if (Error Err = parseRelocSection(Sec.Name, Ctx))
945       return Err;
946   }
947   return Error::success();
948 }
949 
950 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
951   uint32_t Count = readVaruint32(Ctx);
952   Signatures.reserve(Count);
953   while (Count--) {
954     wasm::WasmSignature Sig;
955     uint8_t Form = readUint8(Ctx);
956     if (Form != wasm::WASM_TYPE_FUNC) {
957       return make_error<GenericBinaryError>("Invalid signature type",
958                                             object_error::parse_failed);
959     }
960     uint32_t ParamCount = readVaruint32(Ctx);
961     Sig.Params.reserve(ParamCount);
962     while (ParamCount--) {
963       uint32_t ParamType = readUint8(Ctx);
964       Sig.Params.push_back(wasm::ValType(ParamType));
965     }
966     uint32_t ReturnCount = readVaruint32(Ctx);
967     while (ReturnCount--) {
968       uint32_t ReturnType = readUint8(Ctx);
969       Sig.Returns.push_back(wasm::ValType(ReturnType));
970     }
971     Signatures.push_back(std::move(Sig));
972   }
973   if (Ctx.Ptr != Ctx.End)
974     return make_error<GenericBinaryError>("Type section ended prematurely",
975                                           object_error::parse_failed);
976   return Error::success();
977 }
978 
979 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
980   uint32_t Count = readVaruint32(Ctx);
981   Imports.reserve(Count);
982   for (uint32_t I = 0; I < Count; I++) {
983     wasm::WasmImport Im;
984     Im.Module = readString(Ctx);
985     Im.Field = readString(Ctx);
986     Im.Kind = readUint8(Ctx);
987     switch (Im.Kind) {
988     case wasm::WASM_EXTERNAL_FUNCTION:
989       NumImportedFunctions++;
990       Im.SigIndex = readVaruint32(Ctx);
991       break;
992     case wasm::WASM_EXTERNAL_GLOBAL:
993       NumImportedGlobals++;
994       Im.Global.Type = readUint8(Ctx);
995       Im.Global.Mutable = readVaruint1(Ctx);
996       break;
997     case wasm::WASM_EXTERNAL_MEMORY:
998       Im.Memory = readLimits(Ctx);
999       if (Im.Memory.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1000         HasMemory64 = true;
1001       break;
1002     case wasm::WASM_EXTERNAL_TABLE: {
1003       Im.Table = readTable(Ctx);
1004       Im.Table.Index = NumImportedTables + Tables.size();
1005       NumImportedTables++;
1006       auto ElemType = Im.Table.ElemType;
1007       if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1008           ElemType != wasm::WASM_TYPE_EXTERNREF)
1009         return make_error<GenericBinaryError>("Invalid table element type",
1010                                               object_error::parse_failed);
1011       break;
1012     }
1013     case wasm::WASM_EXTERNAL_EVENT:
1014       NumImportedEvents++;
1015       Im.Event.Attribute = readVarint32(Ctx);
1016       Im.Event.SigIndex = readVarint32(Ctx);
1017       break;
1018     default:
1019       return make_error<GenericBinaryError>("Unexpected import kind",
1020                                             object_error::parse_failed);
1021     }
1022     Imports.push_back(Im);
1023   }
1024   if (Ctx.Ptr != Ctx.End)
1025     return make_error<GenericBinaryError>("Import section ended prematurely",
1026                                           object_error::parse_failed);
1027   return Error::success();
1028 }
1029 
1030 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
1031   uint32_t Count = readVaruint32(Ctx);
1032   FunctionTypes.reserve(Count);
1033   Functions.resize(Count);
1034   uint32_t NumTypes = Signatures.size();
1035   while (Count--) {
1036     uint32_t Type = readVaruint32(Ctx);
1037     if (Type >= NumTypes)
1038       return make_error<GenericBinaryError>("Invalid function type",
1039                                             object_error::parse_failed);
1040     FunctionTypes.push_back(Type);
1041   }
1042   if (Ctx.Ptr != Ctx.End)
1043     return make_error<GenericBinaryError>("Function section ended prematurely",
1044                                           object_error::parse_failed);
1045   return Error::success();
1046 }
1047 
1048 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
1049   uint32_t Count = readVaruint32(Ctx);
1050   Tables.reserve(Count);
1051   while (Count--) {
1052     wasm::WasmTable T = readTable(Ctx);
1053     T.Index = NumImportedTables + Tables.size();
1054     Tables.push_back(T);
1055     auto ElemType = Tables.back().ElemType;
1056     if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1057         ElemType != wasm::WASM_TYPE_EXTERNREF) {
1058       return make_error<GenericBinaryError>("Invalid table element type",
1059                                             object_error::parse_failed);
1060     }
1061   }
1062   if (Ctx.Ptr != Ctx.End)
1063     return make_error<GenericBinaryError>("Table section ended prematurely",
1064                                           object_error::parse_failed);
1065   return Error::success();
1066 }
1067 
1068 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
1069   uint32_t Count = readVaruint32(Ctx);
1070   Memories.reserve(Count);
1071   while (Count--) {
1072     auto Limits = readLimits(Ctx);
1073     if (Limits.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1074       HasMemory64 = true;
1075     Memories.push_back(Limits);
1076   }
1077   if (Ctx.Ptr != Ctx.End)
1078     return make_error<GenericBinaryError>("Memory section ended prematurely",
1079                                           object_error::parse_failed);
1080   return Error::success();
1081 }
1082 
1083 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
1084   EventSection = Sections.size();
1085   uint32_t Count = readVarint32(Ctx);
1086   Events.reserve(Count);
1087   while (Count--) {
1088     wasm::WasmEvent Event;
1089     Event.Index = NumImportedEvents + Events.size();
1090     Event.Type.Attribute = readVaruint32(Ctx);
1091     Event.Type.SigIndex = readVarint32(Ctx);
1092     Events.push_back(Event);
1093   }
1094 
1095   if (Ctx.Ptr != Ctx.End)
1096     return make_error<GenericBinaryError>("Event section ended prematurely",
1097                                           object_error::parse_failed);
1098   return Error::success();
1099 }
1100 
1101 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
1102   GlobalSection = Sections.size();
1103   uint32_t Count = readVaruint32(Ctx);
1104   Globals.reserve(Count);
1105   while (Count--) {
1106     wasm::WasmGlobal Global;
1107     Global.Index = NumImportedGlobals + Globals.size();
1108     Global.Type.Type = readUint8(Ctx);
1109     Global.Type.Mutable = readVaruint1(Ctx);
1110     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
1111       return Err;
1112     Globals.push_back(Global);
1113   }
1114   if (Ctx.Ptr != Ctx.End)
1115     return make_error<GenericBinaryError>("Global section ended prematurely",
1116                                           object_error::parse_failed);
1117   return Error::success();
1118 }
1119 
1120 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
1121   uint32_t Count = readVaruint32(Ctx);
1122   Exports.reserve(Count);
1123   for (uint32_t I = 0; I < Count; I++) {
1124     wasm::WasmExport Ex;
1125     Ex.Name = readString(Ctx);
1126     Ex.Kind = readUint8(Ctx);
1127     Ex.Index = readVaruint32(Ctx);
1128     switch (Ex.Kind) {
1129     case wasm::WASM_EXTERNAL_FUNCTION:
1130 
1131       if (!isDefinedFunctionIndex(Ex.Index))
1132         return make_error<GenericBinaryError>("Invalid function export",
1133                                               object_error::parse_failed);
1134       getDefinedFunction(Ex.Index).ExportName = Ex.Name;
1135       break;
1136     case wasm::WASM_EXTERNAL_GLOBAL:
1137       if (!isValidGlobalIndex(Ex.Index))
1138         return make_error<GenericBinaryError>("Invalid global export",
1139                                               object_error::parse_failed);
1140       break;
1141     case wasm::WASM_EXTERNAL_EVENT:
1142       if (!isValidEventIndex(Ex.Index))
1143         return make_error<GenericBinaryError>("Invalid event export",
1144                                               object_error::parse_failed);
1145       break;
1146     case wasm::WASM_EXTERNAL_MEMORY:
1147     case wasm::WASM_EXTERNAL_TABLE:
1148       break;
1149     default:
1150       return make_error<GenericBinaryError>("Unexpected export kind",
1151                                             object_error::parse_failed);
1152     }
1153     Exports.push_back(Ex);
1154   }
1155   if (Ctx.Ptr != Ctx.End)
1156     return make_error<GenericBinaryError>("Export section ended prematurely",
1157                                           object_error::parse_failed);
1158   return Error::success();
1159 }
1160 
1161 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
1162   return Index < NumImportedFunctions + FunctionTypes.size();
1163 }
1164 
1165 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
1166   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
1167 }
1168 
1169 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
1170   return Index < NumImportedGlobals + Globals.size();
1171 }
1172 
1173 bool WasmObjectFile::isValidTableIndex(uint32_t Index) const {
1174   return Index < NumImportedTables + Tables.size();
1175 }
1176 
1177 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
1178   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
1179 }
1180 
1181 bool WasmObjectFile::isDefinedTableIndex(uint32_t Index) const {
1182   return Index >= NumImportedTables && isValidTableIndex(Index);
1183 }
1184 
1185 bool WasmObjectFile::isValidEventIndex(uint32_t Index) const {
1186   return Index < NumImportedEvents + Events.size();
1187 }
1188 
1189 bool WasmObjectFile::isDefinedEventIndex(uint32_t Index) const {
1190   return Index >= NumImportedEvents && isValidEventIndex(Index);
1191 }
1192 
1193 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1194   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1195 }
1196 
1197 bool WasmObjectFile::isValidTableSymbol(uint32_t Index) const {
1198   return Index < Symbols.size() && Symbols[Index].isTypeTable();
1199 }
1200 
1201 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1202   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1203 }
1204 
1205 bool WasmObjectFile::isValidEventSymbol(uint32_t Index) const {
1206   return Index < Symbols.size() && Symbols[Index].isTypeEvent();
1207 }
1208 
1209 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1210   return Index < Symbols.size() && Symbols[Index].isTypeData();
1211 }
1212 
1213 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1214   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1215 }
1216 
1217 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1218   assert(isDefinedFunctionIndex(Index));
1219   return Functions[Index - NumImportedFunctions];
1220 }
1221 
1222 const wasm::WasmFunction &
1223 WasmObjectFile::getDefinedFunction(uint32_t Index) const {
1224   assert(isDefinedFunctionIndex(Index));
1225   return Functions[Index - NumImportedFunctions];
1226 }
1227 
1228 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1229   assert(isDefinedGlobalIndex(Index));
1230   return Globals[Index - NumImportedGlobals];
1231 }
1232 
1233 wasm::WasmEvent &WasmObjectFile::getDefinedEvent(uint32_t Index) {
1234   assert(isDefinedEventIndex(Index));
1235   return Events[Index - NumImportedEvents];
1236 }
1237 
1238 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1239   StartFunction = readVaruint32(Ctx);
1240   if (!isValidFunctionIndex(StartFunction))
1241     return make_error<GenericBinaryError>("Invalid start function",
1242                                           object_error::parse_failed);
1243   return Error::success();
1244 }
1245 
1246 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1247   SeenCodeSection = true;
1248   CodeSection = Sections.size();
1249   uint32_t FunctionCount = readVaruint32(Ctx);
1250   if (FunctionCount != FunctionTypes.size()) {
1251     return make_error<GenericBinaryError>("Invalid function count",
1252                                           object_error::parse_failed);
1253   }
1254 
1255   for (uint32_t i = 0; i < FunctionCount; i++) {
1256     wasm::WasmFunction& Function = Functions[i];
1257     const uint8_t *FunctionStart = Ctx.Ptr;
1258     uint32_t Size = readVaruint32(Ctx);
1259     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1260 
1261     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1262     Function.Index = NumImportedFunctions + i;
1263     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1264     Function.Size = FunctionEnd - FunctionStart;
1265 
1266     uint32_t NumLocalDecls = readVaruint32(Ctx);
1267     Function.Locals.reserve(NumLocalDecls);
1268     while (NumLocalDecls--) {
1269       wasm::WasmLocalDecl Decl;
1270       Decl.Count = readVaruint32(Ctx);
1271       Decl.Type = readUint8(Ctx);
1272       Function.Locals.push_back(Decl);
1273     }
1274 
1275     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1276     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1277     // This will be set later when reading in the linking metadata section.
1278     Function.Comdat = UINT32_MAX;
1279     Ctx.Ptr += BodySize;
1280     assert(Ctx.Ptr == FunctionEnd);
1281   }
1282   if (Ctx.Ptr != Ctx.End)
1283     return make_error<GenericBinaryError>("Code section ended prematurely",
1284                                           object_error::parse_failed);
1285   return Error::success();
1286 }
1287 
1288 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1289   uint32_t Count = readVaruint32(Ctx);
1290   ElemSegments.reserve(Count);
1291   while (Count--) {
1292     wasm::WasmElemSegment Segment;
1293     Segment.TableIndex = readVaruint32(Ctx);
1294     if (Segment.TableIndex != 0) {
1295       return make_error<GenericBinaryError>("Invalid TableIndex",
1296                                             object_error::parse_failed);
1297     }
1298     if (Error Err = readInitExpr(Segment.Offset, Ctx))
1299       return Err;
1300     uint32_t NumElems = readVaruint32(Ctx);
1301     while (NumElems--) {
1302       Segment.Functions.push_back(readVaruint32(Ctx));
1303     }
1304     ElemSegments.push_back(Segment);
1305   }
1306   if (Ctx.Ptr != Ctx.End)
1307     return make_error<GenericBinaryError>("Elem section ended prematurely",
1308                                           object_error::parse_failed);
1309   return Error::success();
1310 }
1311 
1312 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1313   DataSection = Sections.size();
1314   uint32_t Count = readVaruint32(Ctx);
1315   if (DataCount && Count != DataCount.getValue())
1316     return make_error<GenericBinaryError>(
1317         "Number of data segments does not match DataCount section");
1318   DataSegments.reserve(Count);
1319   while (Count--) {
1320     WasmSegment Segment;
1321     Segment.Data.InitFlags = readVaruint32(Ctx);
1322     Segment.Data.MemoryIndex = (Segment.Data.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
1323                                ? readVaruint32(Ctx) : 0;
1324     if ((Segment.Data.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
1325       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1326         return Err;
1327     } else {
1328       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1329       Segment.Data.Offset.Value.Int32 = 0;
1330     }
1331     uint32_t Size = readVaruint32(Ctx);
1332     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1333       return make_error<GenericBinaryError>("Invalid segment size",
1334                                             object_error::parse_failed);
1335     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1336     // The rest of these Data fields are set later, when reading in the linking
1337     // metadata section.
1338     Segment.Data.Alignment = 0;
1339     Segment.Data.LinkerFlags = 0;
1340     Segment.Data.Comdat = UINT32_MAX;
1341     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1342     Ctx.Ptr += Size;
1343     DataSegments.push_back(Segment);
1344   }
1345   if (Ctx.Ptr != Ctx.End)
1346     return make_error<GenericBinaryError>("Data section ended prematurely",
1347                                           object_error::parse_failed);
1348   return Error::success();
1349 }
1350 
1351 Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
1352   DataCount = readVaruint32(Ctx);
1353   return Error::success();
1354 }
1355 
1356 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1357   return Header;
1358 }
1359 
1360 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.b++; }
1361 
1362 Expected<uint32_t> WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1363   uint32_t Result = SymbolRef::SF_None;
1364   const WasmSymbol &Sym = getWasmSymbol(Symb);
1365 
1366   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1367   if (Sym.isBindingWeak())
1368     Result |= SymbolRef::SF_Weak;
1369   if (!Sym.isBindingLocal())
1370     Result |= SymbolRef::SF_Global;
1371   if (Sym.isHidden())
1372     Result |= SymbolRef::SF_Hidden;
1373   if (!Sym.isDefined())
1374     Result |= SymbolRef::SF_Undefined;
1375   if (Sym.isTypeFunction())
1376     Result |= SymbolRef::SF_Executable;
1377   return Result;
1378 }
1379 
1380 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1381   DataRefImpl Ref;
1382   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1383   Ref.d.b = 0; // Symbol index
1384   return BasicSymbolRef(Ref, this);
1385 }
1386 
1387 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1388   DataRefImpl Ref;
1389   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1390   Ref.d.b = Symbols.size(); // Symbol index
1391   return BasicSymbolRef(Ref, this);
1392 }
1393 
1394 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1395   return Symbols[Symb.d.b];
1396 }
1397 
1398 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1399   return getWasmSymbol(Symb.getRawDataRefImpl());
1400 }
1401 
1402 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1403   return getWasmSymbol(Symb).Info.Name;
1404 }
1405 
1406 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1407   auto &Sym = getWasmSymbol(Symb);
1408   if (Sym.Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION &&
1409       isDefinedFunctionIndex(Sym.Info.ElementIndex))
1410     return getDefinedFunction(Sym.Info.ElementIndex).CodeSectionOffset;
1411   else
1412     return getSymbolValue(Symb);
1413 }
1414 
1415 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1416   switch (Sym.Info.Kind) {
1417   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1418   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1419   case wasm::WASM_SYMBOL_TYPE_EVENT:
1420     return Sym.Info.ElementIndex;
1421   case wasm::WASM_SYMBOL_TYPE_DATA: {
1422     // The value of a data symbol is the segment offset, plus the symbol
1423     // offset within the segment.
1424     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1425     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1426     if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST) {
1427       return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1428     } else if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I64_CONST) {
1429       return Segment.Offset.Value.Int64 + Sym.Info.DataRef.Offset;
1430     } else {
1431       llvm_unreachable("unknown init expr opcode");
1432     }
1433   }
1434   case wasm::WASM_SYMBOL_TYPE_SECTION:
1435     return 0;
1436   }
1437   llvm_unreachable("invalid symbol type");
1438 }
1439 
1440 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1441   return getWasmSymbolValue(getWasmSymbol(Symb));
1442 }
1443 
1444 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1445   llvm_unreachable("not yet implemented");
1446   return 0;
1447 }
1448 
1449 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1450   llvm_unreachable("not yet implemented");
1451   return 0;
1452 }
1453 
1454 Expected<SymbolRef::Type>
1455 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1456   const WasmSymbol &Sym = getWasmSymbol(Symb);
1457 
1458   switch (Sym.Info.Kind) {
1459   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1460     return SymbolRef::ST_Function;
1461   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1462     return SymbolRef::ST_Other;
1463   case wasm::WASM_SYMBOL_TYPE_DATA:
1464     return SymbolRef::ST_Data;
1465   case wasm::WASM_SYMBOL_TYPE_SECTION:
1466     return SymbolRef::ST_Debug;
1467   case wasm::WASM_SYMBOL_TYPE_EVENT:
1468     return SymbolRef::ST_Other;
1469   }
1470 
1471   llvm_unreachable("Unknown WasmSymbol::SymbolType");
1472   return SymbolRef::ST_Other;
1473 }
1474 
1475 Expected<section_iterator>
1476 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1477   const WasmSymbol &Sym = getWasmSymbol(Symb);
1478   if (Sym.isUndefined())
1479     return section_end();
1480 
1481   DataRefImpl Ref;
1482   Ref.d.a = getSymbolSectionIdImpl(Sym);
1483   return section_iterator(SectionRef(Ref, this));
1484 }
1485 
1486 uint32_t WasmObjectFile::getSymbolSectionId(SymbolRef Symb) const {
1487   const WasmSymbol &Sym = getWasmSymbol(Symb);
1488   return getSymbolSectionIdImpl(Sym);
1489 }
1490 
1491 uint32_t WasmObjectFile::getSymbolSectionIdImpl(const WasmSymbol &Sym) const {
1492   switch (Sym.Info.Kind) {
1493   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1494     return CodeSection;
1495   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1496     return GlobalSection;
1497   case wasm::WASM_SYMBOL_TYPE_DATA:
1498     return DataSection;
1499   case wasm::WASM_SYMBOL_TYPE_SECTION:
1500     return Sym.Info.ElementIndex;
1501   case wasm::WASM_SYMBOL_TYPE_EVENT:
1502     return EventSection;
1503   default:
1504     llvm_unreachable("Unknown WasmSymbol::SymbolType");
1505   }
1506 }
1507 
1508 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1509 
1510 Expected<StringRef> WasmObjectFile::getSectionName(DataRefImpl Sec) const {
1511   const WasmSection &S = Sections[Sec.d.a];
1512 #define ECase(X)                                                               \
1513   case wasm::WASM_SEC_##X:                                                     \
1514     return #X;
1515   switch (S.Type) {
1516     ECase(TYPE);
1517     ECase(IMPORT);
1518     ECase(FUNCTION);
1519     ECase(TABLE);
1520     ECase(MEMORY);
1521     ECase(GLOBAL);
1522     ECase(EVENT);
1523     ECase(EXPORT);
1524     ECase(START);
1525     ECase(ELEM);
1526     ECase(CODE);
1527     ECase(DATA);
1528     ECase(DATACOUNT);
1529   case wasm::WASM_SEC_CUSTOM:
1530     return S.Name;
1531   default:
1532     return createStringError(object_error::invalid_section_index, "");
1533   }
1534 #undef ECase
1535 }
1536 
1537 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1538 
1539 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1540   return Sec.d.a;
1541 }
1542 
1543 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1544   const WasmSection &S = Sections[Sec.d.a];
1545   return S.Content.size();
1546 }
1547 
1548 Expected<ArrayRef<uint8_t>>
1549 WasmObjectFile::getSectionContents(DataRefImpl Sec) const {
1550   const WasmSection &S = Sections[Sec.d.a];
1551   // This will never fail since wasm sections can never be empty (user-sections
1552   // must have a name and non-user sections each have a defined structure).
1553   return S.Content;
1554 }
1555 
1556 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1557   return 1;
1558 }
1559 
1560 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1561   return false;
1562 }
1563 
1564 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1565   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1566 }
1567 
1568 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1569   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1570 }
1571 
1572 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1573 
1574 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1575 
1576 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1577   DataRefImpl RelocRef;
1578   RelocRef.d.a = Ref.d.a;
1579   RelocRef.d.b = 0;
1580   return relocation_iterator(RelocationRef(RelocRef, this));
1581 }
1582 
1583 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1584   const WasmSection &Sec = getWasmSection(Ref);
1585   DataRefImpl RelocRef;
1586   RelocRef.d.a = Ref.d.a;
1587   RelocRef.d.b = Sec.Relocations.size();
1588   return relocation_iterator(RelocationRef(RelocRef, this));
1589 }
1590 
1591 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1592 
1593 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1594   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1595   return Rel.Offset;
1596 }
1597 
1598 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1599   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1600   if (Rel.Type == wasm::R_WASM_TYPE_INDEX_LEB)
1601     return symbol_end();
1602   DataRefImpl Sym;
1603   Sym.d.a = 1;
1604   Sym.d.b = Rel.Index;
1605   return symbol_iterator(SymbolRef(Sym, this));
1606 }
1607 
1608 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1609   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1610   return Rel.Type;
1611 }
1612 
1613 void WasmObjectFile::getRelocationTypeName(
1614     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1615   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1616   StringRef Res = "Unknown";
1617 
1618 #define WASM_RELOC(name, value)                                                \
1619   case wasm::name:                                                             \
1620     Res = #name;                                                               \
1621     break;
1622 
1623   switch (Rel.Type) {
1624 #include "llvm/BinaryFormat/WasmRelocs.def"
1625   }
1626 
1627 #undef WASM_RELOC
1628 
1629   Result.append(Res.begin(), Res.end());
1630 }
1631 
1632 section_iterator WasmObjectFile::section_begin() const {
1633   DataRefImpl Ref;
1634   Ref.d.a = 0;
1635   return section_iterator(SectionRef(Ref, this));
1636 }
1637 
1638 section_iterator WasmObjectFile::section_end() const {
1639   DataRefImpl Ref;
1640   Ref.d.a = Sections.size();
1641   return section_iterator(SectionRef(Ref, this));
1642 }
1643 
1644 uint8_t WasmObjectFile::getBytesInAddress() const {
1645   return HasMemory64 ? 8 : 4;
1646 }
1647 
1648 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1649 
1650 Triple::ArchType WasmObjectFile::getArch() const {
1651   return HasMemory64 ? Triple::wasm64 : Triple::wasm32;
1652 }
1653 
1654 SubtargetFeatures WasmObjectFile::getFeatures() const {
1655   return SubtargetFeatures();
1656 }
1657 
1658 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1659 
1660 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1661 
1662 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1663   assert(Ref.d.a < Sections.size());
1664   return Sections[Ref.d.a];
1665 }
1666 
1667 const WasmSection &
1668 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1669   return getWasmSection(Section.getRawDataRefImpl());
1670 }
1671 
1672 const wasm::WasmRelocation &
1673 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1674   return getWasmRelocation(Ref.getRawDataRefImpl());
1675 }
1676 
1677 const wasm::WasmRelocation &
1678 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1679   assert(Ref.d.a < Sections.size());
1680   const WasmSection &Sec = Sections[Ref.d.a];
1681   assert(Ref.d.b < Sec.Relocations.size());
1682   return Sec.Relocations[Ref.d.b];
1683 }
1684 
1685 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1686                                              StringRef CustomSectionName) {
1687   switch (ID) {
1688   case wasm::WASM_SEC_CUSTOM:
1689     return StringSwitch<unsigned>(CustomSectionName)
1690         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1691         .Case("linking", WASM_SEC_ORDER_LINKING)
1692         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1693         .Case("name", WASM_SEC_ORDER_NAME)
1694         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1695         .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
1696         .Default(WASM_SEC_ORDER_NONE);
1697   case wasm::WASM_SEC_TYPE:
1698     return WASM_SEC_ORDER_TYPE;
1699   case wasm::WASM_SEC_IMPORT:
1700     return WASM_SEC_ORDER_IMPORT;
1701   case wasm::WASM_SEC_FUNCTION:
1702     return WASM_SEC_ORDER_FUNCTION;
1703   case wasm::WASM_SEC_TABLE:
1704     return WASM_SEC_ORDER_TABLE;
1705   case wasm::WASM_SEC_MEMORY:
1706     return WASM_SEC_ORDER_MEMORY;
1707   case wasm::WASM_SEC_GLOBAL:
1708     return WASM_SEC_ORDER_GLOBAL;
1709   case wasm::WASM_SEC_EXPORT:
1710     return WASM_SEC_ORDER_EXPORT;
1711   case wasm::WASM_SEC_START:
1712     return WASM_SEC_ORDER_START;
1713   case wasm::WASM_SEC_ELEM:
1714     return WASM_SEC_ORDER_ELEM;
1715   case wasm::WASM_SEC_CODE:
1716     return WASM_SEC_ORDER_CODE;
1717   case wasm::WASM_SEC_DATA:
1718     return WASM_SEC_ORDER_DATA;
1719   case wasm::WASM_SEC_DATACOUNT:
1720     return WASM_SEC_ORDER_DATACOUNT;
1721   case wasm::WASM_SEC_EVENT:
1722     return WASM_SEC_ORDER_EVENT;
1723   default:
1724     return WASM_SEC_ORDER_NONE;
1725   }
1726 }
1727 
1728 // Represents the edges in a directed graph where any node B reachable from node
1729 // A is not allowed to appear before A in the section ordering, but may appear
1730 // afterward.
1731 int WasmSectionOrderChecker::DisallowedPredecessors
1732     [WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
1733         // WASM_SEC_ORDER_NONE
1734         {},
1735         // WASM_SEC_ORDER_TYPE
1736         {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT},
1737         // WASM_SEC_ORDER_IMPORT
1738         {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION},
1739         // WASM_SEC_ORDER_FUNCTION
1740         {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE},
1741         // WASM_SEC_ORDER_TABLE
1742         {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY},
1743         // WASM_SEC_ORDER_MEMORY
1744         {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_EVENT},
1745         // WASM_SEC_ORDER_EVENT
1746         {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_GLOBAL},
1747         // WASM_SEC_ORDER_GLOBAL
1748         {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EXPORT},
1749         // WASM_SEC_ORDER_EXPORT
1750         {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START},
1751         // WASM_SEC_ORDER_START
1752         {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM},
1753         // WASM_SEC_ORDER_ELEM
1754         {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT},
1755         // WASM_SEC_ORDER_DATACOUNT
1756         {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE},
1757         // WASM_SEC_ORDER_CODE
1758         {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA},
1759         // WASM_SEC_ORDER_DATA
1760         {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING},
1761 
1762         // Custom Sections
1763         // WASM_SEC_ORDER_DYLINK
1764         {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE},
1765         // WASM_SEC_ORDER_LINKING
1766         {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME},
1767         // WASM_SEC_ORDER_RELOC (can be repeated)
1768         {},
1769         // WASM_SEC_ORDER_NAME
1770         {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS},
1771         // WASM_SEC_ORDER_PRODUCERS
1772         {WASM_SEC_ORDER_PRODUCERS, WASM_SEC_ORDER_TARGET_FEATURES},
1773         // WASM_SEC_ORDER_TARGET_FEATURES
1774         {WASM_SEC_ORDER_TARGET_FEATURES}};
1775 
1776 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1777                                                   StringRef CustomSectionName) {
1778   int Order = getSectionOrder(ID, CustomSectionName);
1779   if (Order == WASM_SEC_ORDER_NONE)
1780     return true;
1781 
1782   // Disallowed predecessors we need to check for
1783   SmallVector<int, WASM_NUM_SEC_ORDERS> WorkList;
1784 
1785   // Keep track of completed checks to avoid repeating work
1786   bool Checked[WASM_NUM_SEC_ORDERS] = {};
1787 
1788   int Curr = Order;
1789   while (true) {
1790     // Add new disallowed predecessors to work list
1791     for (size_t I = 0;; ++I) {
1792       int Next = DisallowedPredecessors[Curr][I];
1793       if (Next == WASM_SEC_ORDER_NONE)
1794         break;
1795       if (Checked[Next])
1796         continue;
1797       WorkList.push_back(Next);
1798       Checked[Next] = true;
1799     }
1800 
1801     if (WorkList.empty())
1802       break;
1803 
1804     // Consider next disallowed predecessor
1805     Curr = WorkList.pop_back_val();
1806     if (Seen[Curr])
1807       return false;
1808   }
1809 
1810   // Have not seen any disallowed predecessors
1811   Seen[Order] = true;
1812   return true;
1813 }
1814