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