xref: /llvm-project/llvm/lib/Object/WasmObjectFile.cpp (revision ef8c9135efcb3847fc0e5bbdb55eae18751090df)
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)) << ", Flags=0x"
43       << Twine::utohexstr(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.Minimum = 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::WasmTableType readTableType(WasmObjectFile::ReadContext &Ctx) {
218   wasm::WasmTableType TableType;
219   TableType.ElemType = readUint8(Ctx);
220   TableType.Limits = readLimits(Ctx);
221   return TableType;
222 }
223 
224 static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
225                          WasmSectionOrderChecker &Checker) {
226   Section.Offset = Ctx.Ptr - Ctx.Start;
227   Section.Type = readUint8(Ctx);
228   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
229   uint32_t Size = readVaruint32(Ctx);
230   if (Size == 0)
231     return make_error<StringError>("zero length section",
232                                    object_error::parse_failed);
233   if (Ctx.Ptr + Size > Ctx.End)
234     return make_error<StringError>("section too large",
235                                    object_error::parse_failed);
236   if (Section.Type == wasm::WASM_SEC_CUSTOM) {
237     WasmObjectFile::ReadContext SectionCtx;
238     SectionCtx.Start = Ctx.Ptr;
239     SectionCtx.Ptr = Ctx.Ptr;
240     SectionCtx.End = Ctx.Ptr + Size;
241 
242     Section.Name = readString(SectionCtx);
243 
244     uint32_t SectionNameSize = SectionCtx.Ptr - SectionCtx.Start;
245     Ctx.Ptr += SectionNameSize;
246     Size -= SectionNameSize;
247   }
248 
249   if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
250     return make_error<StringError>("out of order section type: " +
251                                        llvm::to_string(Section.Type),
252                                    object_error::parse_failed);
253   }
254 
255   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
256   Ctx.Ptr += Size;
257   return Error::success();
258 }
259 
260 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
261     : ObjectFile(Binary::ID_Wasm, Buffer) {
262   ErrorAsOutParameter ErrAsOutParam(&Err);
263   Header.Magic = getData().substr(0, 4);
264   if (Header.Magic != StringRef("\0asm", 4)) {
265     Err = make_error<StringError>("invalid magic number",
266                                   object_error::parse_failed);
267     return;
268   }
269 
270   ReadContext Ctx;
271   Ctx.Start = getData().bytes_begin();
272   Ctx.Ptr = Ctx.Start + 4;
273   Ctx.End = Ctx.Start + getData().size();
274 
275   if (Ctx.Ptr + 4 > Ctx.End) {
276     Err = make_error<StringError>("missing version number",
277                                   object_error::parse_failed);
278     return;
279   }
280 
281   Header.Version = readUint32(Ctx);
282   if (Header.Version != wasm::WasmVersion) {
283     Err = make_error<StringError>("invalid version number: " +
284                                       Twine(Header.Version),
285                                   object_error::parse_failed);
286     return;
287   }
288 
289   WasmSectionOrderChecker Checker;
290   while (Ctx.Ptr < Ctx.End) {
291     WasmSection Sec;
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_TAG:
320     return parseTagSection(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   // Legacy "dylink" section support.
343   // See parseDylink0Section for the current "dylink.0" section parsing.
344   HasDylinkSection = true;
345   DylinkInfo.MemorySize = readVaruint32(Ctx);
346   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
347   DylinkInfo.TableSize = readVaruint32(Ctx);
348   DylinkInfo.TableAlignment = readVaruint32(Ctx);
349   uint32_t Count = readVaruint32(Ctx);
350   while (Count--) {
351     DylinkInfo.Needed.push_back(readString(Ctx));
352   }
353 
354   if (Ctx.Ptr != Ctx.End)
355     return make_error<GenericBinaryError>("dylink section ended prematurely",
356                                           object_error::parse_failed);
357   return Error::success();
358 }
359 
360 Error WasmObjectFile::parseDylink0Section(ReadContext &Ctx) {
361   // See
362   // https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
363   HasDylinkSection = true;
364 
365   const uint8_t *OrigEnd = Ctx.End;
366   while (Ctx.Ptr < OrigEnd) {
367     Ctx.End = OrigEnd;
368     uint8_t Type = readUint8(Ctx);
369     uint32_t Size = readVaruint32(Ctx);
370     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
371                       << "\n");
372     Ctx.End = Ctx.Ptr + Size;
373     uint32_t Count;
374     switch (Type) {
375     case wasm::WASM_DYLINK_MEM_INFO:
376       DylinkInfo.MemorySize = readVaruint32(Ctx);
377       DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
378       DylinkInfo.TableSize = readVaruint32(Ctx);
379       DylinkInfo.TableAlignment = readVaruint32(Ctx);
380       break;
381     case wasm::WASM_DYLINK_NEEDED:
382       Count = readVaruint32(Ctx);
383       while (Count--) {
384         DylinkInfo.Needed.push_back(readString(Ctx));
385       }
386       break;
387     case wasm::WASM_DYLINK_EXPORT_INFO: {
388       uint32_t Count = readVaruint32(Ctx);
389       while (Count--) {
390         DylinkInfo.ExportInfo.push_back({readString(Ctx), readVaruint32(Ctx)});
391       }
392       break;
393     }
394     default:
395       return make_error<GenericBinaryError>("unknown dylink.0 sub-section",
396                                             object_error::parse_failed);
397       Ctx.Ptr += Size;
398       break;
399     }
400     if (Ctx.Ptr != Ctx.End) {
401       return make_error<GenericBinaryError>(
402           "dylink.0 sub-section ended prematurely", object_error::parse_failed);
403     }
404   }
405 
406   if (Ctx.Ptr != Ctx.End)
407     return make_error<GenericBinaryError>("dylink.0 section ended prematurely",
408                                           object_error::parse_failed);
409   return Error::success();
410 }
411 
412 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
413   llvm::DenseSet<uint64_t> SeenFunctions;
414   llvm::DenseSet<uint64_t> SeenGlobals;
415   llvm::DenseSet<uint64_t> SeenSegments;
416   if (FunctionTypes.size() && !SeenCodeSection) {
417     return make_error<GenericBinaryError>("names must come after code section",
418                                           object_error::parse_failed);
419   }
420 
421   while (Ctx.Ptr < Ctx.End) {
422     uint8_t Type = readUint8(Ctx);
423     uint32_t Size = readVaruint32(Ctx);
424     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
425     switch (Type) {
426     case wasm::WASM_NAMES_FUNCTION:
427     case wasm::WASM_NAMES_GLOBAL:
428     case wasm::WASM_NAMES_DATA_SEGMENT: {
429       uint32_t Count = readVaruint32(Ctx);
430       while (Count--) {
431         uint32_t Index = readVaruint32(Ctx);
432         StringRef Name = readString(Ctx);
433         wasm::NameType nameType = wasm::NameType::FUNCTION;
434         if (Type == wasm::WASM_NAMES_FUNCTION) {
435           if (!SeenFunctions.insert(Index).second)
436             return make_error<GenericBinaryError>(
437                 "function named more than once", object_error::parse_failed);
438           if (!isValidFunctionIndex(Index) || Name.empty())
439             return make_error<GenericBinaryError>("invalid name entry",
440                                                   object_error::parse_failed);
441 
442           if (isDefinedFunctionIndex(Index))
443             getDefinedFunction(Index).DebugName = Name;
444         } else if (Type == wasm::WASM_NAMES_GLOBAL) {
445           nameType = wasm::NameType::GLOBAL;
446           if (!SeenGlobals.insert(Index).second)
447             return make_error<GenericBinaryError>("global named more than once",
448                                                   object_error::parse_failed);
449           if (!isValidGlobalIndex(Index) || Name.empty())
450             return make_error<GenericBinaryError>("invalid name entry",
451                                                   object_error::parse_failed);
452         } else {
453           nameType = wasm::NameType::DATA_SEGMENT;
454           if (!SeenSegments.insert(Index).second)
455             return make_error<GenericBinaryError>(
456                 "segment named more than once", object_error::parse_failed);
457           if (Index > DataSegments.size())
458             return make_error<GenericBinaryError>("invalid named data segment",
459                                                   object_error::parse_failed);
460         }
461         DebugNames.push_back(wasm::WasmDebugName{nameType, Index, Name});
462       }
463       break;
464     }
465     // Ignore local names for now
466     case wasm::WASM_NAMES_LOCAL:
467     default:
468       Ctx.Ptr += Size;
469       break;
470     }
471     if (Ctx.Ptr != SubSectionEnd)
472       return make_error<GenericBinaryError>(
473           "name sub-section ended prematurely", object_error::parse_failed);
474   }
475 
476   if (Ctx.Ptr != Ctx.End)
477     return make_error<GenericBinaryError>("name section ended prematurely",
478                                           object_error::parse_failed);
479   return Error::success();
480 }
481 
482 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
483   HasLinkingSection = true;
484   if (FunctionTypes.size() && !SeenCodeSection) {
485     return make_error<GenericBinaryError>(
486         "linking data must come after code section",
487         object_error::parse_failed);
488   }
489 
490   LinkingData.Version = readVaruint32(Ctx);
491   if (LinkingData.Version != wasm::WasmMetadataVersion) {
492     return make_error<GenericBinaryError>(
493         "unexpected metadata version: " + Twine(LinkingData.Version) +
494             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
495         object_error::parse_failed);
496   }
497 
498   const uint8_t *OrigEnd = Ctx.End;
499   while (Ctx.Ptr < OrigEnd) {
500     Ctx.End = OrigEnd;
501     uint8_t Type = readUint8(Ctx);
502     uint32_t Size = readVaruint32(Ctx);
503     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
504                       << "\n");
505     Ctx.End = Ctx.Ptr + Size;
506     switch (Type) {
507     case wasm::WASM_SYMBOL_TABLE:
508       if (Error Err = parseLinkingSectionSymtab(Ctx))
509         return Err;
510       break;
511     case wasm::WASM_SEGMENT_INFO: {
512       uint32_t Count = readVaruint32(Ctx);
513       if (Count > DataSegments.size())
514         return make_error<GenericBinaryError>("too many segment names",
515                                               object_error::parse_failed);
516       for (uint32_t I = 0; I < Count; I++) {
517         DataSegments[I].Data.Name = readString(Ctx);
518         DataSegments[I].Data.Alignment = readVaruint32(Ctx);
519         DataSegments[I].Data.LinkingFlags = readVaruint32(Ctx);
520       }
521       break;
522     }
523     case wasm::WASM_INIT_FUNCS: {
524       uint32_t Count = readVaruint32(Ctx);
525       LinkingData.InitFunctions.reserve(Count);
526       for (uint32_t I = 0; I < Count; I++) {
527         wasm::WasmInitFunc Init;
528         Init.Priority = readVaruint32(Ctx);
529         Init.Symbol = readVaruint32(Ctx);
530         if (!isValidFunctionSymbol(Init.Symbol))
531           return make_error<GenericBinaryError>("invalid function symbol: " +
532                                                     Twine(Init.Symbol),
533                                                 object_error::parse_failed);
534         LinkingData.InitFunctions.emplace_back(Init);
535       }
536       break;
537     }
538     case wasm::WASM_COMDAT_INFO:
539       if (Error Err = parseLinkingSectionComdat(Ctx))
540         return Err;
541       break;
542     default:
543       Ctx.Ptr += Size;
544       break;
545     }
546     if (Ctx.Ptr != Ctx.End)
547       return make_error<GenericBinaryError>(
548           "linking sub-section ended prematurely", object_error::parse_failed);
549   }
550   if (Ctx.Ptr != OrigEnd)
551     return make_error<GenericBinaryError>("linking section ended prematurely",
552                                           object_error::parse_failed);
553   return Error::success();
554 }
555 
556 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
557   uint32_t Count = readVaruint32(Ctx);
558   LinkingData.SymbolTable.reserve(Count);
559   Symbols.reserve(Count);
560   StringSet<> SymbolNames;
561 
562   std::vector<wasm::WasmImport *> ImportedGlobals;
563   std::vector<wasm::WasmImport *> ImportedFunctions;
564   std::vector<wasm::WasmImport *> ImportedTags;
565   std::vector<wasm::WasmImport *> ImportedTables;
566   ImportedGlobals.reserve(Imports.size());
567   ImportedFunctions.reserve(Imports.size());
568   ImportedTags.reserve(Imports.size());
569   ImportedTables.reserve(Imports.size());
570   for (auto &I : Imports) {
571     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
572       ImportedFunctions.emplace_back(&I);
573     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
574       ImportedGlobals.emplace_back(&I);
575     else if (I.Kind == wasm::WASM_EXTERNAL_TAG)
576       ImportedTags.emplace_back(&I);
577     else if (I.Kind == wasm::WASM_EXTERNAL_TABLE)
578       ImportedTables.emplace_back(&I);
579   }
580 
581   while (Count--) {
582     wasm::WasmSymbolInfo Info;
583     const wasm::WasmSignature *Signature = nullptr;
584     const wasm::WasmGlobalType *GlobalType = nullptr;
585     const wasm::WasmTableType *TableType = nullptr;
586     const wasm::WasmTagType *TagType = nullptr;
587 
588     Info.Kind = readUint8(Ctx);
589     Info.Flags = readVaruint32(Ctx);
590     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
591 
592     switch (Info.Kind) {
593     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
594       Info.ElementIndex = readVaruint32(Ctx);
595       if (!isValidFunctionIndex(Info.ElementIndex) ||
596           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
597         return make_error<GenericBinaryError>("invalid function symbol index",
598                                               object_error::parse_failed);
599       if (IsDefined) {
600         Info.Name = readString(Ctx);
601         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
602         Signature = &Signatures[FunctionTypes[FuncIndex]];
603         wasm::WasmFunction &Function = Functions[FuncIndex];
604         if (Function.SymbolName.empty())
605           Function.SymbolName = Info.Name;
606       } else {
607         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
608         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
609           Info.Name = readString(Ctx);
610           Info.ImportName = Import.Field;
611         } else {
612           Info.Name = Import.Field;
613         }
614         Signature = &Signatures[Import.SigIndex];
615         if (!Import.Module.empty()) {
616           Info.ImportModule = Import.Module;
617         }
618       }
619       break;
620 
621     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
622       Info.ElementIndex = readVaruint32(Ctx);
623       if (!isValidGlobalIndex(Info.ElementIndex) ||
624           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
625         return make_error<GenericBinaryError>("invalid global symbol index",
626                                               object_error::parse_failed);
627       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
628                             wasm::WASM_SYMBOL_BINDING_WEAK)
629         return make_error<GenericBinaryError>("undefined weak global symbol",
630                                               object_error::parse_failed);
631       if (IsDefined) {
632         Info.Name = readString(Ctx);
633         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
634         wasm::WasmGlobal &Global = Globals[GlobalIndex];
635         GlobalType = &Global.Type;
636         if (Global.SymbolName.empty())
637           Global.SymbolName = Info.Name;
638       } else {
639         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
640         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
641           Info.Name = readString(Ctx);
642           Info.ImportName = Import.Field;
643         } else {
644           Info.Name = Import.Field;
645         }
646         GlobalType = &Import.Global;
647         if (!Import.Module.empty()) {
648           Info.ImportModule = Import.Module;
649         }
650       }
651       break;
652 
653     case wasm::WASM_SYMBOL_TYPE_TABLE:
654       Info.ElementIndex = readVaruint32(Ctx);
655       if (!isValidTableNumber(Info.ElementIndex) ||
656           IsDefined != isDefinedTableNumber(Info.ElementIndex))
657         return make_error<GenericBinaryError>("invalid table symbol index",
658                                               object_error::parse_failed);
659       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
660                             wasm::WASM_SYMBOL_BINDING_WEAK)
661         return make_error<GenericBinaryError>("undefined weak table symbol",
662                                               object_error::parse_failed);
663       if (IsDefined) {
664         Info.Name = readString(Ctx);
665         unsigned TableNumber = Info.ElementIndex - NumImportedTables;
666         wasm::WasmTable &Table = Tables[TableNumber];
667         TableType = &Table.Type;
668         if (Table.SymbolName.empty())
669           Table.SymbolName = Info.Name;
670       } else {
671         wasm::WasmImport &Import = *ImportedTables[Info.ElementIndex];
672         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
673           Info.Name = readString(Ctx);
674           Info.ImportName = Import.Field;
675         } else {
676           Info.Name = Import.Field;
677         }
678         TableType = &Import.Table;
679         if (!Import.Module.empty()) {
680           Info.ImportModule = Import.Module;
681         }
682       }
683       break;
684 
685     case wasm::WASM_SYMBOL_TYPE_DATA:
686       Info.Name = readString(Ctx);
687       if (IsDefined) {
688         auto Index = readVaruint32(Ctx);
689         if (Index >= DataSegments.size())
690           return make_error<GenericBinaryError>("invalid data symbol index",
691                                                 object_error::parse_failed);
692         auto Offset = readVaruint64(Ctx);
693         auto Size = readVaruint64(Ctx);
694         size_t SegmentSize = DataSegments[Index].Data.Content.size();
695         if (Offset > SegmentSize)
696           return make_error<GenericBinaryError>(
697               "invalid data symbol offset: `" + Info.Name + "` (offset: " +
698                   Twine(Offset) + " segment size: " + Twine(SegmentSize) + ")",
699               object_error::parse_failed);
700         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
701       }
702       break;
703 
704     case wasm::WASM_SYMBOL_TYPE_SECTION: {
705       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
706           wasm::WASM_SYMBOL_BINDING_LOCAL)
707         return make_error<GenericBinaryError>(
708             "section symbols must have local binding",
709             object_error::parse_failed);
710       Info.ElementIndex = readVaruint32(Ctx);
711       // Use somewhat unique section name as symbol name.
712       StringRef SectionName = Sections[Info.ElementIndex].Name;
713       Info.Name = SectionName;
714       break;
715     }
716 
717     case wasm::WASM_SYMBOL_TYPE_TAG: {
718       Info.ElementIndex = readVaruint32(Ctx);
719       if (!isValidTagIndex(Info.ElementIndex) ||
720           IsDefined != isDefinedTagIndex(Info.ElementIndex))
721         return make_error<GenericBinaryError>("invalid tag symbol index",
722                                               object_error::parse_failed);
723       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
724                             wasm::WASM_SYMBOL_BINDING_WEAK)
725         return make_error<GenericBinaryError>("undefined weak global symbol",
726                                               object_error::parse_failed);
727       if (IsDefined) {
728         Info.Name = readString(Ctx);
729         unsigned TagIndex = Info.ElementIndex - NumImportedTags;
730         wasm::WasmTag &Tag = Tags[TagIndex];
731         Signature = &Signatures[Tag.Type.SigIndex];
732         TagType = &Tag.Type;
733         if (Tag.SymbolName.empty())
734           Tag.SymbolName = Info.Name;
735 
736       } else {
737         wasm::WasmImport &Import = *ImportedTags[Info.ElementIndex];
738         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
739           Info.Name = readString(Ctx);
740           Info.ImportName = Import.Field;
741         } else {
742           Info.Name = Import.Field;
743         }
744         TagType = &Import.Tag;
745         Signature = &Signatures[TagType->SigIndex];
746         if (!Import.Module.empty()) {
747           Info.ImportModule = Import.Module;
748         }
749       }
750       break;
751     }
752 
753     default:
754       return make_error<GenericBinaryError>("invalid symbol type: " +
755                                                 Twine(unsigned(Info.Kind)),
756                                             object_error::parse_failed);
757     }
758 
759     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
760             wasm::WASM_SYMBOL_BINDING_LOCAL &&
761         !SymbolNames.insert(Info.Name).second)
762       return make_error<GenericBinaryError>("duplicate symbol name " +
763                                                 Twine(Info.Name),
764                                             object_error::parse_failed);
765     LinkingData.SymbolTable.emplace_back(Info);
766     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, TableType,
767                          TagType, Signature);
768     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
769   }
770 
771   return Error::success();
772 }
773 
774 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
775   uint32_t ComdatCount = readVaruint32(Ctx);
776   StringSet<> ComdatSet;
777   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
778     StringRef Name = readString(Ctx);
779     if (Name.empty() || !ComdatSet.insert(Name).second)
780       return make_error<GenericBinaryError>("bad/duplicate COMDAT name " +
781                                                 Twine(Name),
782                                             object_error::parse_failed);
783     LinkingData.Comdats.emplace_back(Name);
784     uint32_t Flags = readVaruint32(Ctx);
785     if (Flags != 0)
786       return make_error<GenericBinaryError>("unsupported COMDAT flags",
787                                             object_error::parse_failed);
788 
789     uint32_t EntryCount = readVaruint32(Ctx);
790     while (EntryCount--) {
791       unsigned Kind = readVaruint32(Ctx);
792       unsigned Index = readVaruint32(Ctx);
793       switch (Kind) {
794       default:
795         return make_error<GenericBinaryError>("invalid COMDAT entry type",
796                                               object_error::parse_failed);
797       case wasm::WASM_COMDAT_DATA:
798         if (Index >= DataSegments.size())
799           return make_error<GenericBinaryError>(
800               "COMDAT data index out of range", object_error::parse_failed);
801         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
802           return make_error<GenericBinaryError>("data segment in two COMDATs",
803                                                 object_error::parse_failed);
804         DataSegments[Index].Data.Comdat = ComdatIndex;
805         break;
806       case wasm::WASM_COMDAT_FUNCTION:
807         if (!isDefinedFunctionIndex(Index))
808           return make_error<GenericBinaryError>(
809               "COMDAT function index out of range", object_error::parse_failed);
810         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
811           return make_error<GenericBinaryError>("function in two COMDATs",
812                                                 object_error::parse_failed);
813         getDefinedFunction(Index).Comdat = ComdatIndex;
814         break;
815       case wasm::WASM_COMDAT_SECTION:
816         if (Index >= Sections.size())
817           return make_error<GenericBinaryError>(
818               "COMDAT section index out of range", object_error::parse_failed);
819         if (Sections[Index].Type != wasm::WASM_SEC_CUSTOM)
820           return make_error<GenericBinaryError>(
821               "non-custom section in a COMDAT", object_error::parse_failed);
822         Sections[Index].Comdat = ComdatIndex;
823         break;
824       }
825     }
826   }
827   return Error::success();
828 }
829 
830 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
831   llvm::SmallSet<StringRef, 3> FieldsSeen;
832   uint32_t Fields = readVaruint32(Ctx);
833   for (size_t I = 0; I < Fields; ++I) {
834     StringRef FieldName = readString(Ctx);
835     if (!FieldsSeen.insert(FieldName).second)
836       return make_error<GenericBinaryError>(
837           "producers section does not have unique fields",
838           object_error::parse_failed);
839     std::vector<std::pair<std::string, std::string>> *ProducerVec = nullptr;
840     if (FieldName == "language") {
841       ProducerVec = &ProducerInfo.Languages;
842     } else if (FieldName == "processed-by") {
843       ProducerVec = &ProducerInfo.Tools;
844     } else if (FieldName == "sdk") {
845       ProducerVec = &ProducerInfo.SDKs;
846     } else {
847       return make_error<GenericBinaryError>(
848           "producers section field is not named one of language, processed-by, "
849           "or sdk",
850           object_error::parse_failed);
851     }
852     uint32_t ValueCount = readVaruint32(Ctx);
853     llvm::SmallSet<StringRef, 8> ProducersSeen;
854     for (size_t J = 0; J < ValueCount; ++J) {
855       StringRef Name = readString(Ctx);
856       StringRef Version = readString(Ctx);
857       if (!ProducersSeen.insert(Name).second) {
858         return make_error<GenericBinaryError>(
859             "producers section contains repeated producer",
860             object_error::parse_failed);
861       }
862       ProducerVec->emplace_back(std::string(Name), std::string(Version));
863     }
864   }
865   if (Ctx.Ptr != Ctx.End)
866     return make_error<GenericBinaryError>("producers section ended prematurely",
867                                           object_error::parse_failed);
868   return Error::success();
869 }
870 
871 Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
872   llvm::SmallSet<std::string, 8> FeaturesSeen;
873   uint32_t FeatureCount = readVaruint32(Ctx);
874   for (size_t I = 0; I < FeatureCount; ++I) {
875     wasm::WasmFeatureEntry Feature;
876     Feature.Prefix = readUint8(Ctx);
877     switch (Feature.Prefix) {
878     case wasm::WASM_FEATURE_PREFIX_USED:
879     case wasm::WASM_FEATURE_PREFIX_REQUIRED:
880     case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
881       break;
882     default:
883       return make_error<GenericBinaryError>("unknown feature policy prefix",
884                                             object_error::parse_failed);
885     }
886     Feature.Name = std::string(readString(Ctx));
887     if (!FeaturesSeen.insert(Feature.Name).second)
888       return make_error<GenericBinaryError>(
889           "target features section contains repeated feature \"" +
890               Feature.Name + "\"",
891           object_error::parse_failed);
892     TargetFeatures.push_back(Feature);
893   }
894   if (Ctx.Ptr != Ctx.End)
895     return make_error<GenericBinaryError>(
896         "target features section ended prematurely",
897         object_error::parse_failed);
898   return Error::success();
899 }
900 
901 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
902   uint32_t SectionIndex = readVaruint32(Ctx);
903   if (SectionIndex >= Sections.size())
904     return make_error<GenericBinaryError>("invalid section index",
905                                           object_error::parse_failed);
906   WasmSection &Section = Sections[SectionIndex];
907   uint32_t RelocCount = readVaruint32(Ctx);
908   uint32_t EndOffset = Section.Content.size();
909   uint32_t PreviousOffset = 0;
910   while (RelocCount--) {
911     wasm::WasmRelocation Reloc = {};
912     uint32_t type = readVaruint32(Ctx);
913     Reloc.Type = type;
914     Reloc.Offset = readVaruint32(Ctx);
915     if (Reloc.Offset < PreviousOffset)
916       return make_error<GenericBinaryError>("relocations not in offset order",
917                                             object_error::parse_failed);
918     PreviousOffset = Reloc.Offset;
919     Reloc.Index = readVaruint32(Ctx);
920     switch (type) {
921     case wasm::R_WASM_FUNCTION_INDEX_LEB:
922     case wasm::R_WASM_TABLE_INDEX_SLEB:
923     case wasm::R_WASM_TABLE_INDEX_SLEB64:
924     case wasm::R_WASM_TABLE_INDEX_I32:
925     case wasm::R_WASM_TABLE_INDEX_I64:
926     case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
927     case wasm::R_WASM_TABLE_INDEX_REL_SLEB64:
928       if (!isValidFunctionSymbol(Reloc.Index))
929         return make_error<GenericBinaryError>(
930             "invalid relocation function index", object_error::parse_failed);
931       break;
932     case wasm::R_WASM_TABLE_NUMBER_LEB:
933       if (!isValidTableSymbol(Reloc.Index))
934         return make_error<GenericBinaryError>("invalid relocation table index",
935                                               object_error::parse_failed);
936       break;
937     case wasm::R_WASM_TYPE_INDEX_LEB:
938       if (Reloc.Index >= Signatures.size())
939         return make_error<GenericBinaryError>("invalid relocation type index",
940                                               object_error::parse_failed);
941       break;
942     case wasm::R_WASM_GLOBAL_INDEX_LEB:
943       // R_WASM_GLOBAL_INDEX_LEB are can be used against function and data
944       // symbols to refer to their GOT entries.
945       if (!isValidGlobalSymbol(Reloc.Index) &&
946           !isValidDataSymbol(Reloc.Index) &&
947           !isValidFunctionSymbol(Reloc.Index))
948         return make_error<GenericBinaryError>("invalid relocation global index",
949                                               object_error::parse_failed);
950       break;
951     case wasm::R_WASM_GLOBAL_INDEX_I32:
952       if (!isValidGlobalSymbol(Reloc.Index))
953         return make_error<GenericBinaryError>("invalid relocation global index",
954                                               object_error::parse_failed);
955       break;
956     case wasm::R_WASM_TAG_INDEX_LEB:
957       if (!isValidTagSymbol(Reloc.Index))
958         return make_error<GenericBinaryError>("invalid relocation tag index",
959                                               object_error::parse_failed);
960       break;
961     case wasm::R_WASM_MEMORY_ADDR_LEB:
962     case wasm::R_WASM_MEMORY_ADDR_SLEB:
963     case wasm::R_WASM_MEMORY_ADDR_I32:
964     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
965     case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
966     case wasm::R_WASM_MEMORY_ADDR_LOCREL_I32:
967       if (!isValidDataSymbol(Reloc.Index))
968         return make_error<GenericBinaryError>("invalid relocation data index",
969                                               object_error::parse_failed);
970       Reloc.Addend = readVarint32(Ctx);
971       break;
972     case wasm::R_WASM_MEMORY_ADDR_LEB64:
973     case wasm::R_WASM_MEMORY_ADDR_SLEB64:
974     case wasm::R_WASM_MEMORY_ADDR_I64:
975     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
976     case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB64:
977       if (!isValidDataSymbol(Reloc.Index))
978         return make_error<GenericBinaryError>("invalid relocation data index",
979                                               object_error::parse_failed);
980       Reloc.Addend = readVarint64(Ctx);
981       break;
982     case wasm::R_WASM_FUNCTION_OFFSET_I32:
983       if (!isValidFunctionSymbol(Reloc.Index))
984         return make_error<GenericBinaryError>(
985             "invalid relocation function index", object_error::parse_failed);
986       Reloc.Addend = readVarint32(Ctx);
987       break;
988     case wasm::R_WASM_FUNCTION_OFFSET_I64:
989       if (!isValidFunctionSymbol(Reloc.Index))
990         return make_error<GenericBinaryError>(
991             "invalid relocation function index", object_error::parse_failed);
992       Reloc.Addend = readVarint64(Ctx);
993       break;
994     case wasm::R_WASM_SECTION_OFFSET_I32:
995       if (!isValidSectionSymbol(Reloc.Index))
996         return make_error<GenericBinaryError>(
997             "invalid relocation section index", object_error::parse_failed);
998       Reloc.Addend = readVarint32(Ctx);
999       break;
1000     default:
1001       return make_error<GenericBinaryError>("invalid relocation type: " +
1002                                                 Twine(type),
1003                                             object_error::parse_failed);
1004     }
1005 
1006     // Relocations must fit inside the section, and must appear in order.  They
1007     // also shouldn't overlap a function/element boundary, but we don't bother
1008     // to check that.
1009     uint64_t Size = 5;
1010     if (Reloc.Type == wasm::R_WASM_MEMORY_ADDR_LEB64 ||
1011         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_SLEB64 ||
1012         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_REL_SLEB64)
1013       Size = 10;
1014     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I32 ||
1015         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I32 ||
1016         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_LOCREL_I32 ||
1017         Reloc.Type == wasm::R_WASM_SECTION_OFFSET_I32 ||
1018         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
1019         Reloc.Type == wasm::R_WASM_GLOBAL_INDEX_I32)
1020       Size = 4;
1021     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I64 ||
1022         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64 ||
1023         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I64)
1024       Size = 8;
1025     if (Reloc.Offset + Size > EndOffset)
1026       return make_error<GenericBinaryError>("invalid relocation offset",
1027                                             object_error::parse_failed);
1028 
1029     Section.Relocations.push_back(Reloc);
1030   }
1031   if (Ctx.Ptr != Ctx.End)
1032     return make_error<GenericBinaryError>("reloc section ended prematurely",
1033                                           object_error::parse_failed);
1034   return Error::success();
1035 }
1036 
1037 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
1038   if (Sec.Name == "dylink") {
1039     if (Error Err = parseDylinkSection(Ctx))
1040       return Err;
1041   } else if (Sec.Name == "dylink.0") {
1042     if (Error Err = parseDylink0Section(Ctx))
1043       return Err;
1044   } else if (Sec.Name == "name") {
1045     if (Error Err = parseNameSection(Ctx))
1046       return Err;
1047   } else if (Sec.Name == "linking") {
1048     if (Error Err = parseLinkingSection(Ctx))
1049       return Err;
1050   } else if (Sec.Name == "producers") {
1051     if (Error Err = parseProducersSection(Ctx))
1052       return Err;
1053   } else if (Sec.Name == "target_features") {
1054     if (Error Err = parseTargetFeaturesSection(Ctx))
1055       return Err;
1056   } else if (Sec.Name.startswith("reloc.")) {
1057     if (Error Err = parseRelocSection(Sec.Name, Ctx))
1058       return Err;
1059   }
1060   return Error::success();
1061 }
1062 
1063 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
1064   uint32_t Count = readVaruint32(Ctx);
1065   Signatures.reserve(Count);
1066   while (Count--) {
1067     wasm::WasmSignature Sig;
1068     uint8_t Form = readUint8(Ctx);
1069     if (Form != wasm::WASM_TYPE_FUNC) {
1070       return make_error<GenericBinaryError>("invalid signature type",
1071                                             object_error::parse_failed);
1072     }
1073     uint32_t ParamCount = readVaruint32(Ctx);
1074     Sig.Params.reserve(ParamCount);
1075     while (ParamCount--) {
1076       uint32_t ParamType = readUint8(Ctx);
1077       Sig.Params.push_back(wasm::ValType(ParamType));
1078     }
1079     uint32_t ReturnCount = readVaruint32(Ctx);
1080     while (ReturnCount--) {
1081       uint32_t ReturnType = readUint8(Ctx);
1082       Sig.Returns.push_back(wasm::ValType(ReturnType));
1083     }
1084     Signatures.push_back(std::move(Sig));
1085   }
1086   if (Ctx.Ptr != Ctx.End)
1087     return make_error<GenericBinaryError>("type section ended prematurely",
1088                                           object_error::parse_failed);
1089   return Error::success();
1090 }
1091 
1092 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
1093   uint32_t Count = readVaruint32(Ctx);
1094   Imports.reserve(Count);
1095   for (uint32_t I = 0; I < Count; I++) {
1096     wasm::WasmImport Im;
1097     Im.Module = readString(Ctx);
1098     Im.Field = readString(Ctx);
1099     Im.Kind = readUint8(Ctx);
1100     switch (Im.Kind) {
1101     case wasm::WASM_EXTERNAL_FUNCTION:
1102       NumImportedFunctions++;
1103       Im.SigIndex = readVaruint32(Ctx);
1104       break;
1105     case wasm::WASM_EXTERNAL_GLOBAL:
1106       NumImportedGlobals++;
1107       Im.Global.Type = readUint8(Ctx);
1108       Im.Global.Mutable = readVaruint1(Ctx);
1109       break;
1110     case wasm::WASM_EXTERNAL_MEMORY:
1111       Im.Memory = readLimits(Ctx);
1112       if (Im.Memory.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1113         HasMemory64 = true;
1114       break;
1115     case wasm::WASM_EXTERNAL_TABLE: {
1116       Im.Table = readTableType(Ctx);
1117       NumImportedTables++;
1118       auto ElemType = Im.Table.ElemType;
1119       if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1120           ElemType != wasm::WASM_TYPE_EXTERNREF)
1121         return make_error<GenericBinaryError>("invalid table element type",
1122                                               object_error::parse_failed);
1123       break;
1124     }
1125     case wasm::WASM_EXTERNAL_TAG:
1126       NumImportedTags++;
1127       Im.Tag.Attribute = readUint8(Ctx);
1128       Im.Tag.SigIndex = readVarint32(Ctx);
1129       break;
1130     default:
1131       return make_error<GenericBinaryError>("unexpected import kind",
1132                                             object_error::parse_failed);
1133     }
1134     Imports.push_back(Im);
1135   }
1136   if (Ctx.Ptr != Ctx.End)
1137     return make_error<GenericBinaryError>("import section ended prematurely",
1138                                           object_error::parse_failed);
1139   return Error::success();
1140 }
1141 
1142 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
1143   uint32_t Count = readVaruint32(Ctx);
1144   FunctionTypes.reserve(Count);
1145   Functions.resize(Count);
1146   uint32_t NumTypes = Signatures.size();
1147   while (Count--) {
1148     uint32_t Type = readVaruint32(Ctx);
1149     if (Type >= NumTypes)
1150       return make_error<GenericBinaryError>("invalid function type",
1151                                             object_error::parse_failed);
1152     FunctionTypes.push_back(Type);
1153   }
1154   if (Ctx.Ptr != Ctx.End)
1155     return make_error<GenericBinaryError>("function section ended prematurely",
1156                                           object_error::parse_failed);
1157   return Error::success();
1158 }
1159 
1160 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
1161   TableSection = Sections.size();
1162   uint32_t Count = readVaruint32(Ctx);
1163   Tables.reserve(Count);
1164   while (Count--) {
1165     wasm::WasmTable T;
1166     T.Type = readTableType(Ctx);
1167     T.Index = NumImportedTables + Tables.size();
1168     Tables.push_back(T);
1169     auto ElemType = Tables.back().Type.ElemType;
1170     if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1171         ElemType != wasm::WASM_TYPE_EXTERNREF) {
1172       return make_error<GenericBinaryError>("invalid table element type",
1173                                             object_error::parse_failed);
1174     }
1175   }
1176   if (Ctx.Ptr != Ctx.End)
1177     return make_error<GenericBinaryError>("table section ended prematurely",
1178                                           object_error::parse_failed);
1179   return Error::success();
1180 }
1181 
1182 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
1183   uint32_t Count = readVaruint32(Ctx);
1184   Memories.reserve(Count);
1185   while (Count--) {
1186     auto Limits = readLimits(Ctx);
1187     if (Limits.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1188       HasMemory64 = true;
1189     Memories.push_back(Limits);
1190   }
1191   if (Ctx.Ptr != Ctx.End)
1192     return make_error<GenericBinaryError>("memory section ended prematurely",
1193                                           object_error::parse_failed);
1194   return Error::success();
1195 }
1196 
1197 Error WasmObjectFile::parseTagSection(ReadContext &Ctx) {
1198   TagSection = Sections.size();
1199   uint32_t Count = readVaruint32(Ctx);
1200   Tags.reserve(Count);
1201   while (Count--) {
1202     wasm::WasmTag Tag;
1203     Tag.Index = NumImportedTags + Tags.size();
1204     Tag.Type.Attribute = readUint8(Ctx);
1205     Tag.Type.SigIndex = readVaruint32(Ctx);
1206     Tags.push_back(Tag);
1207   }
1208 
1209   if (Ctx.Ptr != Ctx.End)
1210     return make_error<GenericBinaryError>("tag section ended prematurely",
1211                                           object_error::parse_failed);
1212   return Error::success();
1213 }
1214 
1215 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
1216   GlobalSection = Sections.size();
1217   uint32_t Count = readVaruint32(Ctx);
1218   Globals.reserve(Count);
1219   while (Count--) {
1220     wasm::WasmGlobal Global;
1221     Global.Index = NumImportedGlobals + Globals.size();
1222     Global.Type.Type = readUint8(Ctx);
1223     Global.Type.Mutable = readVaruint1(Ctx);
1224     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
1225       return Err;
1226     Globals.push_back(Global);
1227   }
1228   if (Ctx.Ptr != Ctx.End)
1229     return make_error<GenericBinaryError>("global section ended prematurely",
1230                                           object_error::parse_failed);
1231   return Error::success();
1232 }
1233 
1234 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
1235   uint32_t Count = readVaruint32(Ctx);
1236   Exports.reserve(Count);
1237   for (uint32_t I = 0; I < Count; I++) {
1238     wasm::WasmExport Ex;
1239     Ex.Name = readString(Ctx);
1240     Ex.Kind = readUint8(Ctx);
1241     Ex.Index = readVaruint32(Ctx);
1242     switch (Ex.Kind) {
1243     case wasm::WASM_EXTERNAL_FUNCTION:
1244 
1245       if (!isDefinedFunctionIndex(Ex.Index))
1246         return make_error<GenericBinaryError>("invalid function export",
1247                                               object_error::parse_failed);
1248       getDefinedFunction(Ex.Index).ExportName = Ex.Name;
1249       break;
1250     case wasm::WASM_EXTERNAL_GLOBAL:
1251       if (!isValidGlobalIndex(Ex.Index))
1252         return make_error<GenericBinaryError>("invalid global export",
1253                                               object_error::parse_failed);
1254       break;
1255     case wasm::WASM_EXTERNAL_TAG:
1256       if (!isValidTagIndex(Ex.Index))
1257         return make_error<GenericBinaryError>("invalid tag export",
1258                                               object_error::parse_failed);
1259       break;
1260     case wasm::WASM_EXTERNAL_MEMORY:
1261     case wasm::WASM_EXTERNAL_TABLE:
1262       break;
1263     default:
1264       return make_error<GenericBinaryError>("unexpected export kind",
1265                                             object_error::parse_failed);
1266     }
1267     Exports.push_back(Ex);
1268   }
1269   if (Ctx.Ptr != Ctx.End)
1270     return make_error<GenericBinaryError>("export section ended prematurely",
1271                                           object_error::parse_failed);
1272   return Error::success();
1273 }
1274 
1275 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
1276   return Index < NumImportedFunctions + FunctionTypes.size();
1277 }
1278 
1279 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
1280   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
1281 }
1282 
1283 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
1284   return Index < NumImportedGlobals + Globals.size();
1285 }
1286 
1287 bool WasmObjectFile::isValidTableNumber(uint32_t Index) const {
1288   return Index < NumImportedTables + Tables.size();
1289 }
1290 
1291 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
1292   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
1293 }
1294 
1295 bool WasmObjectFile::isDefinedTableNumber(uint32_t Index) const {
1296   return Index >= NumImportedTables && isValidTableNumber(Index);
1297 }
1298 
1299 bool WasmObjectFile::isValidTagIndex(uint32_t Index) const {
1300   return Index < NumImportedTags + Tags.size();
1301 }
1302 
1303 bool WasmObjectFile::isDefinedTagIndex(uint32_t Index) const {
1304   return Index >= NumImportedTags && isValidTagIndex(Index);
1305 }
1306 
1307 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1308   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1309 }
1310 
1311 bool WasmObjectFile::isValidTableSymbol(uint32_t Index) const {
1312   return Index < Symbols.size() && Symbols[Index].isTypeTable();
1313 }
1314 
1315 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1316   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1317 }
1318 
1319 bool WasmObjectFile::isValidTagSymbol(uint32_t Index) const {
1320   return Index < Symbols.size() && Symbols[Index].isTypeTag();
1321 }
1322 
1323 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1324   return Index < Symbols.size() && Symbols[Index].isTypeData();
1325 }
1326 
1327 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1328   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1329 }
1330 
1331 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1332   assert(isDefinedFunctionIndex(Index));
1333   return Functions[Index - NumImportedFunctions];
1334 }
1335 
1336 const wasm::WasmFunction &
1337 WasmObjectFile::getDefinedFunction(uint32_t Index) const {
1338   assert(isDefinedFunctionIndex(Index));
1339   return Functions[Index - NumImportedFunctions];
1340 }
1341 
1342 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1343   assert(isDefinedGlobalIndex(Index));
1344   return Globals[Index - NumImportedGlobals];
1345 }
1346 
1347 wasm::WasmTag &WasmObjectFile::getDefinedTag(uint32_t Index) {
1348   assert(isDefinedTagIndex(Index));
1349   return Tags[Index - NumImportedTags];
1350 }
1351 
1352 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1353   StartFunction = readVaruint32(Ctx);
1354   if (!isValidFunctionIndex(StartFunction))
1355     return make_error<GenericBinaryError>("invalid start function",
1356                                           object_error::parse_failed);
1357   return Error::success();
1358 }
1359 
1360 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1361   SeenCodeSection = true;
1362   CodeSection = Sections.size();
1363   uint32_t FunctionCount = readVaruint32(Ctx);
1364   if (FunctionCount != FunctionTypes.size()) {
1365     return make_error<GenericBinaryError>("invalid function count",
1366                                           object_error::parse_failed);
1367   }
1368 
1369   for (uint32_t i = 0; i < FunctionCount; i++) {
1370     wasm::WasmFunction& Function = Functions[i];
1371     const uint8_t *FunctionStart = Ctx.Ptr;
1372     uint32_t Size = readVaruint32(Ctx);
1373     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1374 
1375     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1376     Function.Index = NumImportedFunctions + i;
1377     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1378     Function.Size = FunctionEnd - FunctionStart;
1379 
1380     uint32_t NumLocalDecls = readVaruint32(Ctx);
1381     Function.Locals.reserve(NumLocalDecls);
1382     while (NumLocalDecls--) {
1383       wasm::WasmLocalDecl Decl;
1384       Decl.Count = readVaruint32(Ctx);
1385       Decl.Type = readUint8(Ctx);
1386       Function.Locals.push_back(Decl);
1387     }
1388 
1389     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1390     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1391     // This will be set later when reading in the linking metadata section.
1392     Function.Comdat = UINT32_MAX;
1393     Ctx.Ptr += BodySize;
1394     assert(Ctx.Ptr == FunctionEnd);
1395   }
1396   if (Ctx.Ptr != Ctx.End)
1397     return make_error<GenericBinaryError>("code section ended prematurely",
1398                                           object_error::parse_failed);
1399   return Error::success();
1400 }
1401 
1402 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1403   uint32_t Count = readVaruint32(Ctx);
1404   ElemSegments.reserve(Count);
1405   while (Count--) {
1406     wasm::WasmElemSegment Segment;
1407     Segment.Flags = readVaruint32(Ctx);
1408 
1409     uint32_t SupportedFlags = wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER |
1410                               wasm::WASM_ELEM_SEGMENT_IS_PASSIVE |
1411                               wasm::WASM_ELEM_SEGMENT_HAS_INIT_EXPRS;
1412     if (Segment.Flags & ~SupportedFlags)
1413       return make_error<GenericBinaryError>(
1414           "Unsupported flags for element segment", object_error::parse_failed);
1415 
1416     if (Segment.Flags & wasm::WASM_ELEM_SEGMENT_HAS_TABLE_NUMBER)
1417       Segment.TableNumber = readVaruint32(Ctx);
1418     else
1419       Segment.TableNumber = 0;
1420     if (!isValidTableNumber(Segment.TableNumber))
1421       return make_error<GenericBinaryError>("invalid TableNumber",
1422                                             object_error::parse_failed);
1423 
1424     if (Segment.Flags & wasm::WASM_ELEM_SEGMENT_IS_PASSIVE) {
1425       Segment.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1426       Segment.Offset.Value.Int32 = 0;
1427     } else {
1428       if (Error Err = readInitExpr(Segment.Offset, Ctx))
1429         return Err;
1430     }
1431 
1432     if (Segment.Flags & wasm::WASM_ELEM_SEGMENT_MASK_HAS_ELEM_KIND) {
1433       Segment.ElemKind = readUint8(Ctx);
1434       if (Segment.Flags & wasm::WASM_ELEM_SEGMENT_HAS_INIT_EXPRS) {
1435         if (Segment.ElemKind != uint8_t(wasm::ValType::FUNCREF) &&
1436             Segment.ElemKind != uint8_t(wasm::ValType::EXTERNREF)) {
1437           return make_error<GenericBinaryError>("invalid reference type",
1438                                                 object_error::parse_failed);
1439         }
1440       } else {
1441         if (Segment.ElemKind != 0)
1442           return make_error<GenericBinaryError>("invalid elemtype",
1443                                                 object_error::parse_failed);
1444         Segment.ElemKind = uint8_t(wasm::ValType::FUNCREF);
1445       }
1446     } else {
1447       Segment.ElemKind = uint8_t(wasm::ValType::FUNCREF);
1448     }
1449 
1450     if (Segment.Flags & wasm::WASM_ELEM_SEGMENT_HAS_INIT_EXPRS)
1451       return make_error<GenericBinaryError>(
1452           "elem segment init expressions not yet implemented",
1453           object_error::parse_failed);
1454 
1455     uint32_t NumElems = readVaruint32(Ctx);
1456     while (NumElems--) {
1457       Segment.Functions.push_back(readVaruint32(Ctx));
1458     }
1459     ElemSegments.push_back(Segment);
1460   }
1461   if (Ctx.Ptr != Ctx.End)
1462     return make_error<GenericBinaryError>("elem section ended prematurely",
1463                                           object_error::parse_failed);
1464   return Error::success();
1465 }
1466 
1467 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1468   DataSection = Sections.size();
1469   uint32_t Count = readVaruint32(Ctx);
1470   if (DataCount && Count != DataCount.getValue())
1471     return make_error<GenericBinaryError>(
1472         "number of data segments does not match DataCount section");
1473   DataSegments.reserve(Count);
1474   while (Count--) {
1475     WasmSegment Segment;
1476     Segment.Data.InitFlags = readVaruint32(Ctx);
1477     Segment.Data.MemoryIndex =
1478         (Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
1479             ? readVaruint32(Ctx)
1480             : 0;
1481     if ((Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
1482       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1483         return Err;
1484     } else {
1485       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1486       Segment.Data.Offset.Value.Int32 = 0;
1487     }
1488     uint32_t Size = readVaruint32(Ctx);
1489     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1490       return make_error<GenericBinaryError>("invalid segment size",
1491                                             object_error::parse_failed);
1492     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1493     // The rest of these Data fields are set later, when reading in the linking
1494     // metadata section.
1495     Segment.Data.Alignment = 0;
1496     Segment.Data.LinkingFlags = 0;
1497     Segment.Data.Comdat = UINT32_MAX;
1498     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1499     Ctx.Ptr += Size;
1500     DataSegments.push_back(Segment);
1501   }
1502   if (Ctx.Ptr != Ctx.End)
1503     return make_error<GenericBinaryError>("data section ended prematurely",
1504                                           object_error::parse_failed);
1505   return Error::success();
1506 }
1507 
1508 Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
1509   DataCount = readVaruint32(Ctx);
1510   return Error::success();
1511 }
1512 
1513 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1514   return Header;
1515 }
1516 
1517 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.b++; }
1518 
1519 Expected<uint32_t> WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1520   uint32_t Result = SymbolRef::SF_None;
1521   const WasmSymbol &Sym = getWasmSymbol(Symb);
1522 
1523   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1524   if (Sym.isBindingWeak())
1525     Result |= SymbolRef::SF_Weak;
1526   if (!Sym.isBindingLocal())
1527     Result |= SymbolRef::SF_Global;
1528   if (Sym.isHidden())
1529     Result |= SymbolRef::SF_Hidden;
1530   if (!Sym.isDefined())
1531     Result |= SymbolRef::SF_Undefined;
1532   if (Sym.isTypeFunction())
1533     Result |= SymbolRef::SF_Executable;
1534   return Result;
1535 }
1536 
1537 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1538   DataRefImpl Ref;
1539   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1540   Ref.d.b = 0; // Symbol index
1541   return BasicSymbolRef(Ref, this);
1542 }
1543 
1544 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1545   DataRefImpl Ref;
1546   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1547   Ref.d.b = Symbols.size(); // Symbol index
1548   return BasicSymbolRef(Ref, this);
1549 }
1550 
1551 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1552   return Symbols[Symb.d.b];
1553 }
1554 
1555 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1556   return getWasmSymbol(Symb.getRawDataRefImpl());
1557 }
1558 
1559 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1560   return getWasmSymbol(Symb).Info.Name;
1561 }
1562 
1563 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1564   auto &Sym = getWasmSymbol(Symb);
1565   if (Sym.Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION &&
1566       isDefinedFunctionIndex(Sym.Info.ElementIndex))
1567     return getDefinedFunction(Sym.Info.ElementIndex).CodeSectionOffset;
1568   else
1569     return getSymbolValue(Symb);
1570 }
1571 
1572 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1573   switch (Sym.Info.Kind) {
1574   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1575   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1576   case wasm::WASM_SYMBOL_TYPE_TAG:
1577   case wasm::WASM_SYMBOL_TYPE_TABLE:
1578     return Sym.Info.ElementIndex;
1579   case wasm::WASM_SYMBOL_TYPE_DATA: {
1580     // The value of a data symbol is the segment offset, plus the symbol
1581     // offset within the segment.
1582     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1583     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1584     if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST) {
1585       return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1586     } else if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I64_CONST) {
1587       return Segment.Offset.Value.Int64 + Sym.Info.DataRef.Offset;
1588     } else {
1589       llvm_unreachable("unknown init expr opcode");
1590     }
1591   }
1592   case wasm::WASM_SYMBOL_TYPE_SECTION:
1593     return 0;
1594   }
1595   llvm_unreachable("invalid symbol type");
1596 }
1597 
1598 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1599   return getWasmSymbolValue(getWasmSymbol(Symb));
1600 }
1601 
1602 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1603   llvm_unreachable("not yet implemented");
1604   return 0;
1605 }
1606 
1607 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1608   llvm_unreachable("not yet implemented");
1609   return 0;
1610 }
1611 
1612 Expected<SymbolRef::Type>
1613 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1614   const WasmSymbol &Sym = getWasmSymbol(Symb);
1615 
1616   switch (Sym.Info.Kind) {
1617   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1618     return SymbolRef::ST_Function;
1619   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1620     return SymbolRef::ST_Other;
1621   case wasm::WASM_SYMBOL_TYPE_DATA:
1622     return SymbolRef::ST_Data;
1623   case wasm::WASM_SYMBOL_TYPE_SECTION:
1624     return SymbolRef::ST_Debug;
1625   case wasm::WASM_SYMBOL_TYPE_TAG:
1626     return SymbolRef::ST_Other;
1627   case wasm::WASM_SYMBOL_TYPE_TABLE:
1628     return SymbolRef::ST_Other;
1629   }
1630 
1631   llvm_unreachable("unknown WasmSymbol::SymbolType");
1632   return SymbolRef::ST_Other;
1633 }
1634 
1635 Expected<section_iterator>
1636 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1637   const WasmSymbol &Sym = getWasmSymbol(Symb);
1638   if (Sym.isUndefined())
1639     return section_end();
1640 
1641   DataRefImpl Ref;
1642   Ref.d.a = getSymbolSectionIdImpl(Sym);
1643   return section_iterator(SectionRef(Ref, this));
1644 }
1645 
1646 uint32_t WasmObjectFile::getSymbolSectionId(SymbolRef Symb) const {
1647   const WasmSymbol &Sym = getWasmSymbol(Symb);
1648   return getSymbolSectionIdImpl(Sym);
1649 }
1650 
1651 uint32_t WasmObjectFile::getSymbolSectionIdImpl(const WasmSymbol &Sym) const {
1652   switch (Sym.Info.Kind) {
1653   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1654     return CodeSection;
1655   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1656     return GlobalSection;
1657   case wasm::WASM_SYMBOL_TYPE_DATA:
1658     return DataSection;
1659   case wasm::WASM_SYMBOL_TYPE_SECTION:
1660     return Sym.Info.ElementIndex;
1661   case wasm::WASM_SYMBOL_TYPE_TAG:
1662     return TagSection;
1663   case wasm::WASM_SYMBOL_TYPE_TABLE:
1664     return TableSection;
1665   default:
1666     llvm_unreachable("unknown WasmSymbol::SymbolType");
1667   }
1668 }
1669 
1670 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1671 
1672 Expected<StringRef> WasmObjectFile::getSectionName(DataRefImpl Sec) const {
1673   const WasmSection &S = Sections[Sec.d.a];
1674 #define ECase(X)                                                               \
1675   case wasm::WASM_SEC_##X:                                                     \
1676     return #X;
1677   switch (S.Type) {
1678     ECase(TYPE);
1679     ECase(IMPORT);
1680     ECase(FUNCTION);
1681     ECase(TABLE);
1682     ECase(MEMORY);
1683     ECase(GLOBAL);
1684     ECase(TAG);
1685     ECase(EXPORT);
1686     ECase(START);
1687     ECase(ELEM);
1688     ECase(CODE);
1689     ECase(DATA);
1690     ECase(DATACOUNT);
1691   case wasm::WASM_SEC_CUSTOM:
1692     return S.Name;
1693   default:
1694     return createStringError(object_error::invalid_section_index, "");
1695   }
1696 #undef ECase
1697 }
1698 
1699 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1700 
1701 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1702   return Sec.d.a;
1703 }
1704 
1705 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1706   const WasmSection &S = Sections[Sec.d.a];
1707   return S.Content.size();
1708 }
1709 
1710 Expected<ArrayRef<uint8_t>>
1711 WasmObjectFile::getSectionContents(DataRefImpl Sec) const {
1712   const WasmSection &S = Sections[Sec.d.a];
1713   // This will never fail since wasm sections can never be empty (user-sections
1714   // must have a name and non-user sections each have a defined structure).
1715   return S.Content;
1716 }
1717 
1718 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1719   return 1;
1720 }
1721 
1722 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1723   return false;
1724 }
1725 
1726 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1727   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1728 }
1729 
1730 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1731   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1732 }
1733 
1734 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1735 
1736 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1737 
1738 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1739   DataRefImpl RelocRef;
1740   RelocRef.d.a = Ref.d.a;
1741   RelocRef.d.b = 0;
1742   return relocation_iterator(RelocationRef(RelocRef, this));
1743 }
1744 
1745 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1746   const WasmSection &Sec = getWasmSection(Ref);
1747   DataRefImpl RelocRef;
1748   RelocRef.d.a = Ref.d.a;
1749   RelocRef.d.b = Sec.Relocations.size();
1750   return relocation_iterator(RelocationRef(RelocRef, this));
1751 }
1752 
1753 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1754 
1755 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1756   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1757   return Rel.Offset;
1758 }
1759 
1760 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1761   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1762   if (Rel.Type == wasm::R_WASM_TYPE_INDEX_LEB)
1763     return symbol_end();
1764   DataRefImpl Sym;
1765   Sym.d.a = 1;
1766   Sym.d.b = Rel.Index;
1767   return symbol_iterator(SymbolRef(Sym, this));
1768 }
1769 
1770 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1771   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1772   return Rel.Type;
1773 }
1774 
1775 void WasmObjectFile::getRelocationTypeName(
1776     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1777   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1778   StringRef Res = "Unknown";
1779 
1780 #define WASM_RELOC(name, value)                                                \
1781   case wasm::name:                                                             \
1782     Res = #name;                                                               \
1783     break;
1784 
1785   switch (Rel.Type) {
1786 #include "llvm/BinaryFormat/WasmRelocs.def"
1787   }
1788 
1789 #undef WASM_RELOC
1790 
1791   Result.append(Res.begin(), Res.end());
1792 }
1793 
1794 section_iterator WasmObjectFile::section_begin() const {
1795   DataRefImpl Ref;
1796   Ref.d.a = 0;
1797   return section_iterator(SectionRef(Ref, this));
1798 }
1799 
1800 section_iterator WasmObjectFile::section_end() const {
1801   DataRefImpl Ref;
1802   Ref.d.a = Sections.size();
1803   return section_iterator(SectionRef(Ref, this));
1804 }
1805 
1806 uint8_t WasmObjectFile::getBytesInAddress() const {
1807   return HasMemory64 ? 8 : 4;
1808 }
1809 
1810 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1811 
1812 Triple::ArchType WasmObjectFile::getArch() const {
1813   return HasMemory64 ? Triple::wasm64 : Triple::wasm32;
1814 }
1815 
1816 SubtargetFeatures WasmObjectFile::getFeatures() const {
1817   return SubtargetFeatures();
1818 }
1819 
1820 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1821 
1822 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1823 
1824 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1825   assert(Ref.d.a < Sections.size());
1826   return Sections[Ref.d.a];
1827 }
1828 
1829 const WasmSection &
1830 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1831   return getWasmSection(Section.getRawDataRefImpl());
1832 }
1833 
1834 const wasm::WasmRelocation &
1835 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1836   return getWasmRelocation(Ref.getRawDataRefImpl());
1837 }
1838 
1839 const wasm::WasmRelocation &
1840 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1841   assert(Ref.d.a < Sections.size());
1842   const WasmSection &Sec = Sections[Ref.d.a];
1843   assert(Ref.d.b < Sec.Relocations.size());
1844   return Sec.Relocations[Ref.d.b];
1845 }
1846 
1847 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1848                                              StringRef CustomSectionName) {
1849   switch (ID) {
1850   case wasm::WASM_SEC_CUSTOM:
1851     return StringSwitch<unsigned>(CustomSectionName)
1852         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1853         .Case("dylink.0", WASM_SEC_ORDER_DYLINK)
1854         .Case("linking", WASM_SEC_ORDER_LINKING)
1855         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1856         .Case("name", WASM_SEC_ORDER_NAME)
1857         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1858         .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
1859         .Default(WASM_SEC_ORDER_NONE);
1860   case wasm::WASM_SEC_TYPE:
1861     return WASM_SEC_ORDER_TYPE;
1862   case wasm::WASM_SEC_IMPORT:
1863     return WASM_SEC_ORDER_IMPORT;
1864   case wasm::WASM_SEC_FUNCTION:
1865     return WASM_SEC_ORDER_FUNCTION;
1866   case wasm::WASM_SEC_TABLE:
1867     return WASM_SEC_ORDER_TABLE;
1868   case wasm::WASM_SEC_MEMORY:
1869     return WASM_SEC_ORDER_MEMORY;
1870   case wasm::WASM_SEC_GLOBAL:
1871     return WASM_SEC_ORDER_GLOBAL;
1872   case wasm::WASM_SEC_EXPORT:
1873     return WASM_SEC_ORDER_EXPORT;
1874   case wasm::WASM_SEC_START:
1875     return WASM_SEC_ORDER_START;
1876   case wasm::WASM_SEC_ELEM:
1877     return WASM_SEC_ORDER_ELEM;
1878   case wasm::WASM_SEC_CODE:
1879     return WASM_SEC_ORDER_CODE;
1880   case wasm::WASM_SEC_DATA:
1881     return WASM_SEC_ORDER_DATA;
1882   case wasm::WASM_SEC_DATACOUNT:
1883     return WASM_SEC_ORDER_DATACOUNT;
1884   case wasm::WASM_SEC_TAG:
1885     return WASM_SEC_ORDER_TAG;
1886   default:
1887     return WASM_SEC_ORDER_NONE;
1888   }
1889 }
1890 
1891 // Represents the edges in a directed graph where any node B reachable from node
1892 // A is not allowed to appear before A in the section ordering, but may appear
1893 // afterward.
1894 int WasmSectionOrderChecker::DisallowedPredecessors
1895     [WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
1896         // WASM_SEC_ORDER_NONE
1897         {},
1898         // WASM_SEC_ORDER_TYPE
1899         {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT},
1900         // WASM_SEC_ORDER_IMPORT
1901         {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION},
1902         // WASM_SEC_ORDER_FUNCTION
1903         {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE},
1904         // WASM_SEC_ORDER_TABLE
1905         {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY},
1906         // WASM_SEC_ORDER_MEMORY
1907         {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_TAG},
1908         // WASM_SEC_ORDER_TAG
1909         {WASM_SEC_ORDER_TAG, WASM_SEC_ORDER_GLOBAL},
1910         // WASM_SEC_ORDER_GLOBAL
1911         {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EXPORT},
1912         // WASM_SEC_ORDER_EXPORT
1913         {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START},
1914         // WASM_SEC_ORDER_START
1915         {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM},
1916         // WASM_SEC_ORDER_ELEM
1917         {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT},
1918         // WASM_SEC_ORDER_DATACOUNT
1919         {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE},
1920         // WASM_SEC_ORDER_CODE
1921         {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA},
1922         // WASM_SEC_ORDER_DATA
1923         {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING},
1924 
1925         // Custom Sections
1926         // WASM_SEC_ORDER_DYLINK
1927         {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE},
1928         // WASM_SEC_ORDER_LINKING
1929         {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME},
1930         // WASM_SEC_ORDER_RELOC (can be repeated)
1931         {},
1932         // WASM_SEC_ORDER_NAME
1933         {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS},
1934         // WASM_SEC_ORDER_PRODUCERS
1935         {WASM_SEC_ORDER_PRODUCERS, WASM_SEC_ORDER_TARGET_FEATURES},
1936         // WASM_SEC_ORDER_TARGET_FEATURES
1937         {WASM_SEC_ORDER_TARGET_FEATURES}};
1938 
1939 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1940                                                   StringRef CustomSectionName) {
1941   int Order = getSectionOrder(ID, CustomSectionName);
1942   if (Order == WASM_SEC_ORDER_NONE)
1943     return true;
1944 
1945   // Disallowed predecessors we need to check for
1946   SmallVector<int, WASM_NUM_SEC_ORDERS> WorkList;
1947 
1948   // Keep track of completed checks to avoid repeating work
1949   bool Checked[WASM_NUM_SEC_ORDERS] = {};
1950 
1951   int Curr = Order;
1952   while (true) {
1953     // Add new disallowed predecessors to work list
1954     for (size_t I = 0;; ++I) {
1955       int Next = DisallowedPredecessors[Curr][I];
1956       if (Next == WASM_SEC_ORDER_NONE)
1957         break;
1958       if (Checked[Next])
1959         continue;
1960       WorkList.push_back(Next);
1961       Checked[Next] = true;
1962     }
1963 
1964     if (WorkList.empty())
1965       break;
1966 
1967     // Consider next disallowed predecessor
1968     Curr = WorkList.pop_back_val();
1969     if (Seen[Curr])
1970       return false;
1971   }
1972 
1973   // Have not seen any disallowed predecessors
1974   Seen[Order] = true;
1975   return true;
1976 }
1977