1 //===- WasmObjectFile.cpp - Wasm object file implementation ---------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "llvm/ADT/ArrayRef.h"
11 #include "llvm/ADT/DenseSet.h"
12 #include "llvm/ADT/STLExtras.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/ADT/StringSet.h"
15 #include "llvm/ADT/Triple.h"
16 #include "llvm/BinaryFormat/Wasm.h"
17 #include "llvm/MC/SubtargetFeature.h"
18 #include "llvm/Object/Binary.h"
19 #include "llvm/Object/Error.h"
20 #include "llvm/Object/ObjectFile.h"
21 #include "llvm/Object/SymbolicFile.h"
22 #include "llvm/Object/Wasm.h"
23 #include "llvm/Support/Endian.h"
24 #include "llvm/Support/Error.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/LEB128.h"
27 #include "llvm/Support/ScopedPrinter.h"
28 #include <algorithm>
29 #include <cassert>
30 #include <cstdint>
31 #include <cstring>
32 #include <system_error>
33 
34 #define DEBUG_TYPE "wasm-object"
35 
36 using namespace llvm;
37 using namespace object;
38 
39 void WasmSymbol::print(raw_ostream &Out) const {
40   Out << "Name=" << Info.Name
41       << ", Kind=" << toString(wasm::WasmSymbolType(Info.Kind))
42       << ", Flags=" << Info.Flags;
43   if (!isTypeData()) {
44     Out << ", ElemIndex=" << Info.ElementIndex;
45   } else if (isDefined()) {
46     Out << ", Segment=" << Info.DataRef.Segment;
47     Out << ", Offset=" << Info.DataRef.Offset;
48     Out << ", Size=" << Info.DataRef.Size;
49   }
50 }
51 
52 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
53 LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
54 #endif
55 
56 Expected<std::unique_ptr<WasmObjectFile>>
57 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
58   Error Err = Error::success();
59   auto ObjectFile = llvm::make_unique<WasmObjectFile>(Buffer, Err);
60   if (Err)
61     return std::move(Err);
62 
63   return std::move(ObjectFile);
64 }
65 
66 #define VARINT7_MAX ((1 << 7) - 1)
67 #define VARINT7_MIN (-(1 << 7))
68 #define VARUINT7_MAX (1 << 7)
69 #define VARUINT1_MAX (1)
70 
71 static uint8_t readUint8(WasmObjectFile::ReadContext &Ctx) {
72   if (Ctx.Ptr == Ctx.End)
73     report_fatal_error("EOF while reading uint8");
74   return *Ctx.Ptr++;
75 }
76 
77 static uint32_t readUint32(WasmObjectFile::ReadContext &Ctx) {
78   if (Ctx.Ptr + 4 > Ctx.End)
79     report_fatal_error("EOF while reading uint32");
80   uint32_t Result = support::endian::read32le(Ctx.Ptr);
81   Ctx.Ptr += 4;
82   return Result;
83 }
84 
85 static int32_t readFloat32(WasmObjectFile::ReadContext &Ctx) {
86   if (Ctx.Ptr + 4 > Ctx.End)
87     report_fatal_error("EOF while reading float64");
88   int32_t Result = 0;
89   memcpy(&Result, Ctx.Ptr, sizeof(Result));
90   Ctx.Ptr += sizeof(Result);
91   return Result;
92 }
93 
94 static int64_t readFloat64(WasmObjectFile::ReadContext &Ctx) {
95   if (Ctx.Ptr + 8 > Ctx.End)
96     report_fatal_error("EOF while reading float64");
97   int64_t Result = 0;
98   memcpy(&Result, Ctx.Ptr, sizeof(Result));
99   Ctx.Ptr += sizeof(Result);
100   return Result;
101 }
102 
103 static uint64_t readULEB128(WasmObjectFile::ReadContext &Ctx) {
104   unsigned Count;
105   const char *Error = nullptr;
106   uint64_t Result = decodeULEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
107   if (Error)
108     report_fatal_error(Error);
109   Ctx.Ptr += Count;
110   return Result;
111 }
112 
113 static StringRef readString(WasmObjectFile::ReadContext &Ctx) {
114   uint32_t StringLen = readULEB128(Ctx);
115   if (Ctx.Ptr + StringLen > Ctx.End)
116     report_fatal_error("EOF while reading string");
117   StringRef Return =
118       StringRef(reinterpret_cast<const char *>(Ctx.Ptr), StringLen);
119   Ctx.Ptr += StringLen;
120   return Return;
121 }
122 
123 static int64_t readLEB128(WasmObjectFile::ReadContext &Ctx) {
124   unsigned Count;
125   const char *Error = nullptr;
126   uint64_t Result = decodeSLEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
127   if (Error)
128     report_fatal_error(Error);
129   Ctx.Ptr += Count;
130   return Result;
131 }
132 
133 static uint8_t readVaruint1(WasmObjectFile::ReadContext &Ctx) {
134   int64_t result = readLEB128(Ctx);
135   if (result > VARUINT1_MAX || result < 0)
136     report_fatal_error("LEB is outside Varuint1 range");
137   return result;
138 }
139 
140 static int32_t readVarint32(WasmObjectFile::ReadContext &Ctx) {
141   int64_t result = readLEB128(Ctx);
142   if (result > INT32_MAX || result < INT32_MIN)
143     report_fatal_error("LEB is outside Varint32 range");
144   return result;
145 }
146 
147 static uint32_t readVaruint32(WasmObjectFile::ReadContext &Ctx) {
148   uint64_t result = readULEB128(Ctx);
149   if (result > UINT32_MAX)
150     report_fatal_error("LEB is outside Varuint32 range");
151   return result;
152 }
153 
154 static int64_t readVarint64(WasmObjectFile::ReadContext &Ctx) {
155   return readLEB128(Ctx);
156 }
157 
158 static uint8_t readOpcode(WasmObjectFile::ReadContext &Ctx) {
159   return readUint8(Ctx);
160 }
161 
162 static Error readInitExpr(wasm::WasmInitExpr &Expr,
163                           WasmObjectFile::ReadContext &Ctx) {
164   Expr.Opcode = readOpcode(Ctx);
165 
166   switch (Expr.Opcode) {
167   case wasm::WASM_OPCODE_I32_CONST:
168     Expr.Value.Int32 = readVarint32(Ctx);
169     break;
170   case wasm::WASM_OPCODE_I64_CONST:
171     Expr.Value.Int64 = readVarint64(Ctx);
172     break;
173   case wasm::WASM_OPCODE_F32_CONST:
174     Expr.Value.Float32 = readFloat32(Ctx);
175     break;
176   case wasm::WASM_OPCODE_F64_CONST:
177     Expr.Value.Float64 = readFloat64(Ctx);
178     break;
179   case wasm::WASM_OPCODE_GLOBAL_GET:
180     Expr.Value.Global = readULEB128(Ctx);
181     break;
182   default:
183     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
184                                           object_error::parse_failed);
185   }
186 
187   uint8_t EndOpcode = readOpcode(Ctx);
188   if (EndOpcode != wasm::WASM_OPCODE_END) {
189     return make_error<GenericBinaryError>("Invalid init_expr",
190                                           object_error::parse_failed);
191   }
192   return Error::success();
193 }
194 
195 static wasm::WasmLimits readLimits(WasmObjectFile::ReadContext &Ctx) {
196   wasm::WasmLimits Result;
197   Result.Flags = readVaruint32(Ctx);
198   Result.Initial = readVaruint32(Ctx);
199   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
200     Result.Maximum = readVaruint32(Ctx);
201   return Result;
202 }
203 
204 static wasm::WasmTable readTable(WasmObjectFile::ReadContext &Ctx) {
205   wasm::WasmTable Table;
206   Table.ElemType = readUint8(Ctx);
207   Table.Limits = readLimits(Ctx);
208   return Table;
209 }
210 
211 static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
212                          WasmSectionOrderChecker &Checker) {
213   Section.Offset = Ctx.Ptr - Ctx.Start;
214   Section.Type = readUint8(Ctx);
215   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
216   uint32_t Size = readVaruint32(Ctx);
217   if (Size == 0)
218     return make_error<StringError>("Zero length section",
219                                    object_error::parse_failed);
220   if (Ctx.Ptr + Size > Ctx.End)
221     return make_error<StringError>("Section too large",
222                                    object_error::parse_failed);
223   if (Section.Type == wasm::WASM_SEC_CUSTOM) {
224     WasmObjectFile::ReadContext SectionCtx;
225     SectionCtx.Start = Ctx.Ptr;
226     SectionCtx.Ptr = Ctx.Ptr;
227     SectionCtx.End = Ctx.Ptr + Size;
228 
229     Section.Name = readString(SectionCtx);
230 
231     uint32_t SectionNameSize = SectionCtx.Ptr - SectionCtx.Start;
232     Ctx.Ptr += SectionNameSize;
233     Size -= SectionNameSize;
234   }
235 
236   if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
237     return make_error<StringError>("Out of order section type: " +
238                                        llvm::to_string(Section.Type),
239                                    object_error::parse_failed);
240   }
241 
242   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
243   Ctx.Ptr += Size;
244   return Error::success();
245 }
246 
247 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
248     : ObjectFile(Binary::ID_Wasm, Buffer) {
249   ErrorAsOutParameter ErrAsOutParam(&Err);
250   Header.Magic = getData().substr(0, 4);
251   if (Header.Magic != StringRef("\0asm", 4)) {
252     Err =
253         make_error<StringError>("Bad magic number", object_error::parse_failed);
254     return;
255   }
256 
257   ReadContext Ctx;
258   Ctx.Start = getPtr(0);
259   Ctx.Ptr = Ctx.Start + 4;
260   Ctx.End = Ctx.Start + getData().size();
261 
262   if (Ctx.Ptr + 4 > Ctx.End) {
263     Err = make_error<StringError>("Missing version number",
264                                   object_error::parse_failed);
265     return;
266   }
267 
268   Header.Version = readUint32(Ctx);
269   if (Header.Version != wasm::WasmVersion) {
270     Err = make_error<StringError>("Bad version number",
271                                   object_error::parse_failed);
272     return;
273   }
274 
275   WasmSection Sec;
276   WasmSectionOrderChecker Checker;
277   while (Ctx.Ptr < Ctx.End) {
278     if ((Err = readSection(Sec, Ctx, Checker)))
279       return;
280     if ((Err = parseSection(Sec)))
281       return;
282 
283     Sections.push_back(Sec);
284   }
285 }
286 
287 Error WasmObjectFile::parseSection(WasmSection &Sec) {
288   ReadContext Ctx;
289   Ctx.Start = Sec.Content.data();
290   Ctx.End = Ctx.Start + Sec.Content.size();
291   Ctx.Ptr = Ctx.Start;
292   switch (Sec.Type) {
293   case wasm::WASM_SEC_CUSTOM:
294     return parseCustomSection(Sec, Ctx);
295   case wasm::WASM_SEC_TYPE:
296     return parseTypeSection(Ctx);
297   case wasm::WASM_SEC_IMPORT:
298     return parseImportSection(Ctx);
299   case wasm::WASM_SEC_FUNCTION:
300     return parseFunctionSection(Ctx);
301   case wasm::WASM_SEC_TABLE:
302     return parseTableSection(Ctx);
303   case wasm::WASM_SEC_MEMORY:
304     return parseMemorySection(Ctx);
305   case wasm::WASM_SEC_GLOBAL:
306     return parseGlobalSection(Ctx);
307   case wasm::WASM_SEC_EVENT:
308     return parseEventSection(Ctx);
309   case wasm::WASM_SEC_EXPORT:
310     return parseExportSection(Ctx);
311   case wasm::WASM_SEC_START:
312     return parseStartSection(Ctx);
313   case wasm::WASM_SEC_ELEM:
314     return parseElemSection(Ctx);
315   case wasm::WASM_SEC_CODE:
316     return parseCodeSection(Ctx);
317   case wasm::WASM_SEC_DATA:
318     return parseDataSection(Ctx);
319   default:
320     return make_error<GenericBinaryError>("Bad section type",
321                                           object_error::parse_failed);
322   }
323 }
324 
325 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
326   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
327   DylinkInfo.MemorySize = readVaruint32(Ctx);
328   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
329   DylinkInfo.TableSize = readVaruint32(Ctx);
330   DylinkInfo.TableAlignment = readVaruint32(Ctx);
331   uint32_t Count = readVaruint32(Ctx);
332   while (Count--) {
333     DylinkInfo.Needed.push_back(readString(Ctx));
334   }
335   if (Ctx.Ptr != Ctx.End)
336     return make_error<GenericBinaryError>("dylink section ended prematurely",
337                                           object_error::parse_failed);
338   return Error::success();
339 }
340 
341 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
342   llvm::DenseSet<uint64_t> Seen;
343   if (Functions.size() != FunctionTypes.size()) {
344     return make_error<GenericBinaryError>("Names must come after code section",
345                                           object_error::parse_failed);
346   }
347 
348   while (Ctx.Ptr < Ctx.End) {
349     uint8_t Type = readUint8(Ctx);
350     uint32_t Size = readVaruint32(Ctx);
351     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
352     switch (Type) {
353     case wasm::WASM_NAMES_FUNCTION: {
354       uint32_t Count = readVaruint32(Ctx);
355       while (Count--) {
356         uint32_t Index = readVaruint32(Ctx);
357         if (!Seen.insert(Index).second)
358           return make_error<GenericBinaryError>("Function named more than once",
359                                                 object_error::parse_failed);
360         StringRef Name = readString(Ctx);
361         if (!isValidFunctionIndex(Index) || Name.empty())
362           return make_error<GenericBinaryError>("Invalid name entry",
363                                                 object_error::parse_failed);
364         DebugNames.push_back(wasm::WasmFunctionName{Index, Name});
365         if (isDefinedFunctionIndex(Index))
366           getDefinedFunction(Index).DebugName = Name;
367       }
368       break;
369     }
370     // Ignore local names for now
371     case wasm::WASM_NAMES_LOCAL:
372     default:
373       Ctx.Ptr += Size;
374       break;
375     }
376     if (Ctx.Ptr != SubSectionEnd)
377       return make_error<GenericBinaryError>(
378           "Name sub-section ended prematurely", object_error::parse_failed);
379   }
380 
381   if (Ctx.Ptr != Ctx.End)
382     return make_error<GenericBinaryError>("Name section ended prematurely",
383                                           object_error::parse_failed);
384   return Error::success();
385 }
386 
387 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
388   HasLinkingSection = true;
389   if (Functions.size() != FunctionTypes.size()) {
390     return make_error<GenericBinaryError>(
391         "Linking data must come after code section",
392         object_error::parse_failed);
393   }
394 
395   LinkingData.Version = readVaruint32(Ctx);
396   if (LinkingData.Version != wasm::WasmMetadataVersion) {
397     return make_error<GenericBinaryError>(
398         "Unexpected metadata version: " + Twine(LinkingData.Version) +
399             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
400         object_error::parse_failed);
401   }
402 
403   const uint8_t *OrigEnd = Ctx.End;
404   while (Ctx.Ptr < OrigEnd) {
405     Ctx.End = OrigEnd;
406     uint8_t Type = readUint8(Ctx);
407     uint32_t Size = readVaruint32(Ctx);
408     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
409                       << "\n");
410     Ctx.End = Ctx.Ptr + Size;
411     switch (Type) {
412     case wasm::WASM_SYMBOL_TABLE:
413       if (Error Err = parseLinkingSectionSymtab(Ctx))
414         return Err;
415       break;
416     case wasm::WASM_SEGMENT_INFO: {
417       uint32_t Count = readVaruint32(Ctx);
418       if (Count > DataSegments.size())
419         return make_error<GenericBinaryError>("Too many segment names",
420                                               object_error::parse_failed);
421       for (uint32_t i = 0; i < Count; i++) {
422         DataSegments[i].Data.Name = readString(Ctx);
423         DataSegments[i].Data.Alignment = readVaruint32(Ctx);
424         DataSegments[i].Data.Flags = readVaruint32(Ctx);
425       }
426       break;
427     }
428     case wasm::WASM_INIT_FUNCS: {
429       uint32_t Count = readVaruint32(Ctx);
430       LinkingData.InitFunctions.reserve(Count);
431       for (uint32_t i = 0; i < Count; i++) {
432         wasm::WasmInitFunc Init;
433         Init.Priority = readVaruint32(Ctx);
434         Init.Symbol = readVaruint32(Ctx);
435         if (!isValidFunctionSymbol(Init.Symbol))
436           return make_error<GenericBinaryError>("Invalid function symbol: " +
437                                                     Twine(Init.Symbol),
438                                                 object_error::parse_failed);
439         LinkingData.InitFunctions.emplace_back(Init);
440       }
441       break;
442     }
443     case wasm::WASM_COMDAT_INFO:
444       if (Error Err = parseLinkingSectionComdat(Ctx))
445         return Err;
446       break;
447     default:
448       Ctx.Ptr += Size;
449       break;
450     }
451     if (Ctx.Ptr != Ctx.End)
452       return make_error<GenericBinaryError>(
453           "Linking sub-section ended prematurely", object_error::parse_failed);
454   }
455   if (Ctx.Ptr != OrigEnd)
456     return make_error<GenericBinaryError>("Linking section ended prematurely",
457                                           object_error::parse_failed);
458   return Error::success();
459 }
460 
461 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
462   uint32_t Count = readVaruint32(Ctx);
463   LinkingData.SymbolTable.reserve(Count);
464   Symbols.reserve(Count);
465   StringSet<> SymbolNames;
466 
467   std::vector<wasm::WasmImport *> ImportedGlobals;
468   std::vector<wasm::WasmImport *> ImportedFunctions;
469   std::vector<wasm::WasmImport *> ImportedEvents;
470   ImportedGlobals.reserve(Imports.size());
471   ImportedFunctions.reserve(Imports.size());
472   ImportedEvents.reserve(Imports.size());
473   for (auto &I : Imports) {
474     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
475       ImportedFunctions.emplace_back(&I);
476     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
477       ImportedGlobals.emplace_back(&I);
478     else if (I.Kind == wasm::WASM_EXTERNAL_EVENT)
479       ImportedEvents.emplace_back(&I);
480   }
481 
482   while (Count--) {
483     wasm::WasmSymbolInfo Info;
484     const wasm::WasmSignature *Signature = nullptr;
485     const wasm::WasmGlobalType *GlobalType = nullptr;
486     const wasm::WasmEventType *EventType = nullptr;
487 
488     Info.Kind = readUint8(Ctx);
489     Info.Flags = readVaruint32(Ctx);
490     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
491 
492     switch (Info.Kind) {
493     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
494       Info.ElementIndex = readVaruint32(Ctx);
495       if (!isValidFunctionIndex(Info.ElementIndex) ||
496           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
497         return make_error<GenericBinaryError>("invalid function symbol index",
498                                               object_error::parse_failed);
499       if (IsDefined) {
500         Info.Name = readString(Ctx);
501         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
502         Signature = &Signatures[FunctionTypes[FuncIndex]];
503         wasm::WasmFunction &Function = Functions[FuncIndex];
504         if (Function.SymbolName.empty())
505           Function.SymbolName = Info.Name;
506       } else {
507         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
508         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
509           Info.Name = readString(Ctx);
510         else
511           Info.Name = Import.Field;
512         Signature = &Signatures[Import.SigIndex];
513         Info.ImportName = Import.Field;
514         Info.ImportModule = Import.Module;
515       }
516       break;
517 
518     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
519       Info.ElementIndex = readVaruint32(Ctx);
520       if (!isValidGlobalIndex(Info.ElementIndex) ||
521           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
522         return make_error<GenericBinaryError>("invalid global symbol index",
523                                               object_error::parse_failed);
524       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
525                             wasm::WASM_SYMBOL_BINDING_WEAK)
526         return make_error<GenericBinaryError>("undefined weak global symbol",
527                                               object_error::parse_failed);
528       if (IsDefined) {
529         Info.Name = readString(Ctx);
530         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
531         wasm::WasmGlobal &Global = Globals[GlobalIndex];
532         GlobalType = &Global.Type;
533         if (Global.SymbolName.empty())
534           Global.SymbolName = Info.Name;
535       } else {
536         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
537         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
538           Info.Name = readString(Ctx);
539         else
540           Info.Name = Import.Field;
541         GlobalType = &Import.Global;
542         Info.ImportName = Import.Field;
543         Info.ImportModule = Import.Module;
544       }
545       break;
546 
547     case wasm::WASM_SYMBOL_TYPE_DATA:
548       Info.Name = readString(Ctx);
549       if (IsDefined) {
550         uint32_t Index = readVaruint32(Ctx);
551         if (Index >= DataSegments.size())
552           return make_error<GenericBinaryError>("invalid data symbol index",
553                                                 object_error::parse_failed);
554         uint32_t Offset = readVaruint32(Ctx);
555         uint32_t Size = readVaruint32(Ctx);
556         if (Offset + Size > DataSegments[Index].Data.Content.size())
557           return make_error<GenericBinaryError>("invalid data symbol offset",
558                                                 object_error::parse_failed);
559         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
560       }
561       break;
562 
563     case wasm::WASM_SYMBOL_TYPE_SECTION: {
564       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
565           wasm::WASM_SYMBOL_BINDING_LOCAL)
566         return make_error<GenericBinaryError>(
567             "Section symbols must have local binding",
568             object_error::parse_failed);
569       Info.ElementIndex = readVaruint32(Ctx);
570       // Use somewhat unique section name as symbol name.
571       StringRef SectionName = Sections[Info.ElementIndex].Name;
572       Info.Name = SectionName;
573       break;
574     }
575 
576     case wasm::WASM_SYMBOL_TYPE_EVENT: {
577       Info.ElementIndex = readVaruint32(Ctx);
578       if (!isValidEventIndex(Info.ElementIndex) ||
579           IsDefined != isDefinedEventIndex(Info.ElementIndex))
580         return make_error<GenericBinaryError>("invalid event symbol index",
581                                               object_error::parse_failed);
582       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
583                             wasm::WASM_SYMBOL_BINDING_WEAK)
584         return make_error<GenericBinaryError>("undefined weak global symbol",
585                                               object_error::parse_failed);
586       if (IsDefined) {
587         Info.Name = readString(Ctx);
588         unsigned EventIndex = Info.ElementIndex - NumImportedEvents;
589         wasm::WasmEvent &Event = Events[EventIndex];
590         Signature = &Signatures[Event.Type.SigIndex];
591         EventType = &Event.Type;
592         if (Event.SymbolName.empty())
593           Event.SymbolName = Info.Name;
594 
595       } else {
596         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
597         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
598           Info.Name = readString(Ctx);
599         else
600           Info.Name = Import.Field;
601         EventType = &Import.Event;
602         Signature = &Signatures[EventType->SigIndex];
603         Info.ImportName = Import.Field;
604         Info.ImportModule = Import.Module;
605       }
606       break;
607     }
608 
609     default:
610       return make_error<GenericBinaryError>("Invalid symbol type",
611                                             object_error::parse_failed);
612     }
613 
614     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
615             wasm::WASM_SYMBOL_BINDING_LOCAL &&
616         !SymbolNames.insert(Info.Name).second)
617       return make_error<GenericBinaryError>("Duplicate symbol name " +
618                                                 Twine(Info.Name),
619                                             object_error::parse_failed);
620     LinkingData.SymbolTable.emplace_back(Info);
621     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, EventType,
622                          Signature);
623     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
624   }
625 
626   return Error::success();
627 }
628 
629 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
630   uint32_t ComdatCount = readVaruint32(Ctx);
631   StringSet<> ComdatSet;
632   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
633     StringRef Name = readString(Ctx);
634     if (Name.empty() || !ComdatSet.insert(Name).second)
635       return make_error<GenericBinaryError>("Bad/duplicate COMDAT name " +
636                                                 Twine(Name),
637                                             object_error::parse_failed);
638     LinkingData.Comdats.emplace_back(Name);
639     uint32_t Flags = readVaruint32(Ctx);
640     if (Flags != 0)
641       return make_error<GenericBinaryError>("Unsupported COMDAT flags",
642                                             object_error::parse_failed);
643 
644     uint32_t EntryCount = readVaruint32(Ctx);
645     while (EntryCount--) {
646       unsigned Kind = readVaruint32(Ctx);
647       unsigned Index = readVaruint32(Ctx);
648       switch (Kind) {
649       default:
650         return make_error<GenericBinaryError>("Invalid COMDAT entry type",
651                                               object_error::parse_failed);
652       case wasm::WASM_COMDAT_DATA:
653         if (Index >= DataSegments.size())
654           return make_error<GenericBinaryError>(
655               "COMDAT data index out of range", object_error::parse_failed);
656         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
657           return make_error<GenericBinaryError>("Data segment in two COMDATs",
658                                                 object_error::parse_failed);
659         DataSegments[Index].Data.Comdat = ComdatIndex;
660         break;
661       case wasm::WASM_COMDAT_FUNCTION:
662         if (!isDefinedFunctionIndex(Index))
663           return make_error<GenericBinaryError>(
664               "COMDAT function index out of range", object_error::parse_failed);
665         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
666           return make_error<GenericBinaryError>("Function in two COMDATs",
667                                                 object_error::parse_failed);
668         getDefinedFunction(Index).Comdat = ComdatIndex;
669         break;
670       }
671     }
672   }
673   return Error::success();
674 }
675 
676 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
677   uint32_t SectionIndex = readVaruint32(Ctx);
678   if (SectionIndex >= Sections.size())
679     return make_error<GenericBinaryError>("Invalid section index",
680                                           object_error::parse_failed);
681   WasmSection &Section = Sections[SectionIndex];
682   uint32_t RelocCount = readVaruint32(Ctx);
683   uint32_t EndOffset = Section.Content.size();
684   uint32_t PreviousOffset = 0;
685   while (RelocCount--) {
686     wasm::WasmRelocation Reloc = {};
687     Reloc.Type = readVaruint32(Ctx);
688     Reloc.Offset = readVaruint32(Ctx);
689     if (Reloc.Offset < PreviousOffset)
690       return make_error<GenericBinaryError>("Relocations not in offset order",
691                                             object_error::parse_failed);
692     PreviousOffset = Reloc.Offset;
693     Reloc.Index = readVaruint32(Ctx);
694     switch (Reloc.Type) {
695     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
696     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
697     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
698       if (!isValidFunctionSymbol(Reloc.Index))
699         return make_error<GenericBinaryError>("Bad relocation function index",
700                                               object_error::parse_failed);
701       break;
702     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
703       if (Reloc.Index >= Signatures.size())
704         return make_error<GenericBinaryError>("Bad relocation type index",
705                                               object_error::parse_failed);
706       break;
707     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
708       if (!isValidGlobalSymbol(Reloc.Index))
709         return make_error<GenericBinaryError>("Bad relocation global index",
710                                               object_error::parse_failed);
711       break;
712     case wasm::R_WEBASSEMBLY_EVENT_INDEX_LEB:
713       if (!isValidEventSymbol(Reloc.Index))
714         return make_error<GenericBinaryError>("Bad relocation event index",
715                                               object_error::parse_failed);
716       break;
717     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
718     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
719     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
720       if (!isValidDataSymbol(Reloc.Index))
721         return make_error<GenericBinaryError>("Bad relocation data index",
722                                               object_error::parse_failed);
723       Reloc.Addend = readVarint32(Ctx);
724       break;
725     case wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32:
726       if (!isValidFunctionSymbol(Reloc.Index))
727         return make_error<GenericBinaryError>("Bad relocation function index",
728                                               object_error::parse_failed);
729       Reloc.Addend = readVarint32(Ctx);
730       break;
731     case wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32:
732       if (!isValidSectionSymbol(Reloc.Index))
733         return make_error<GenericBinaryError>("Bad relocation section index",
734                                               object_error::parse_failed);
735       Reloc.Addend = readVarint32(Ctx);
736       break;
737     default:
738       return make_error<GenericBinaryError>("Bad relocation type: " +
739                                                 Twine(Reloc.Type),
740                                             object_error::parse_failed);
741     }
742 
743     // Relocations must fit inside the section, and must appear in order.  They
744     // also shouldn't overlap a function/element boundary, but we don't bother
745     // to check that.
746     uint64_t Size = 5;
747     if (Reloc.Type == wasm::R_WEBASSEMBLY_TABLE_INDEX_I32 ||
748         Reloc.Type == wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32 ||
749         Reloc.Type == wasm::R_WEBASSEMBLY_SECTION_OFFSET_I32 ||
750         Reloc.Type == wasm::R_WEBASSEMBLY_FUNCTION_OFFSET_I32)
751       Size = 4;
752     if (Reloc.Offset + Size > EndOffset)
753       return make_error<GenericBinaryError>("Bad relocation offset",
754                                             object_error::parse_failed);
755 
756     Section.Relocations.push_back(Reloc);
757   }
758   if (Ctx.Ptr != Ctx.End)
759     return make_error<GenericBinaryError>("Reloc section ended prematurely",
760                                           object_error::parse_failed);
761   return Error::success();
762 }
763 
764 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
765   if (Sec.Name == "dylink") {
766     if (Error Err = parseDylinkSection(Ctx))
767       return Err;
768   } else if (Sec.Name == "name") {
769     if (Error Err = parseNameSection(Ctx))
770       return Err;
771   } else if (Sec.Name == "linking") {
772     if (Error Err = parseLinkingSection(Ctx))
773       return Err;
774   } else if (Sec.Name.startswith("reloc.")) {
775     if (Error Err = parseRelocSection(Sec.Name, Ctx))
776       return Err;
777   }
778   return Error::success();
779 }
780 
781 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
782   uint32_t Count = readVaruint32(Ctx);
783   Signatures.reserve(Count);
784   while (Count--) {
785     wasm::WasmSignature Sig;
786     uint8_t Form = readUint8(Ctx);
787     if (Form != wasm::WASM_TYPE_FUNC) {
788       return make_error<GenericBinaryError>("Invalid signature type",
789                                             object_error::parse_failed);
790     }
791     uint32_t ParamCount = readVaruint32(Ctx);
792     Sig.Params.reserve(ParamCount);
793     while (ParamCount--) {
794       uint32_t ParamType = readUint8(Ctx);
795       Sig.Params.push_back(wasm::ValType(ParamType));
796     }
797     uint32_t ReturnCount = readVaruint32(Ctx);
798     if (ReturnCount) {
799       if (ReturnCount != 1) {
800         return make_error<GenericBinaryError>(
801             "Multiple return types not supported", object_error::parse_failed);
802       }
803       Sig.Returns.push_back(wasm::ValType(readUint8(Ctx)));
804     }
805     Signatures.push_back(std::move(Sig));
806   }
807   if (Ctx.Ptr != Ctx.End)
808     return make_error<GenericBinaryError>("Type section ended prematurely",
809                                           object_error::parse_failed);
810   return Error::success();
811 }
812 
813 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
814   uint32_t Count = readVaruint32(Ctx);
815   Imports.reserve(Count);
816   for (uint32_t i = 0; i < Count; i++) {
817     wasm::WasmImport Im;
818     Im.Module = readString(Ctx);
819     Im.Field = readString(Ctx);
820     Im.Kind = readUint8(Ctx);
821     switch (Im.Kind) {
822     case wasm::WASM_EXTERNAL_FUNCTION:
823       NumImportedFunctions++;
824       Im.SigIndex = readVaruint32(Ctx);
825       break;
826     case wasm::WASM_EXTERNAL_GLOBAL:
827       NumImportedGlobals++;
828       Im.Global.Type = readUint8(Ctx);
829       Im.Global.Mutable = readVaruint1(Ctx);
830       break;
831     case wasm::WASM_EXTERNAL_MEMORY:
832       Im.Memory = readLimits(Ctx);
833       break;
834     case wasm::WASM_EXTERNAL_TABLE:
835       Im.Table = readTable(Ctx);
836       if (Im.Table.ElemType != wasm::WASM_TYPE_FUNCREF)
837         return make_error<GenericBinaryError>("Invalid table element type",
838                                               object_error::parse_failed);
839       break;
840     case wasm::WASM_EXTERNAL_EVENT:
841       NumImportedEvents++;
842       Im.Event.Attribute = readVarint32(Ctx);
843       Im.Event.SigIndex = readVarint32(Ctx);
844       break;
845     default:
846       return make_error<GenericBinaryError>("Unexpected import kind",
847                                             object_error::parse_failed);
848     }
849     Imports.push_back(Im);
850   }
851   if (Ctx.Ptr != Ctx.End)
852     return make_error<GenericBinaryError>("Import section ended prematurely",
853                                           object_error::parse_failed);
854   return Error::success();
855 }
856 
857 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
858   uint32_t Count = readVaruint32(Ctx);
859   FunctionTypes.reserve(Count);
860   uint32_t NumTypes = Signatures.size();
861   while (Count--) {
862     uint32_t Type = readVaruint32(Ctx);
863     if (Type >= NumTypes)
864       return make_error<GenericBinaryError>("Invalid function type",
865                                             object_error::parse_failed);
866     FunctionTypes.push_back(Type);
867   }
868   if (Ctx.Ptr != Ctx.End)
869     return make_error<GenericBinaryError>("Function section ended prematurely",
870                                           object_error::parse_failed);
871   return Error::success();
872 }
873 
874 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
875   uint32_t Count = readVaruint32(Ctx);
876   Tables.reserve(Count);
877   while (Count--) {
878     Tables.push_back(readTable(Ctx));
879     if (Tables.back().ElemType != wasm::WASM_TYPE_FUNCREF) {
880       return make_error<GenericBinaryError>("Invalid table element type",
881                                             object_error::parse_failed);
882     }
883   }
884   if (Ctx.Ptr != Ctx.End)
885     return make_error<GenericBinaryError>("Table section ended prematurely",
886                                           object_error::parse_failed);
887   return Error::success();
888 }
889 
890 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
891   uint32_t Count = readVaruint32(Ctx);
892   Memories.reserve(Count);
893   while (Count--) {
894     Memories.push_back(readLimits(Ctx));
895   }
896   if (Ctx.Ptr != Ctx.End)
897     return make_error<GenericBinaryError>("Memory section ended prematurely",
898                                           object_error::parse_failed);
899   return Error::success();
900 }
901 
902 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
903   GlobalSection = Sections.size();
904   uint32_t Count = readVaruint32(Ctx);
905   Globals.reserve(Count);
906   while (Count--) {
907     wasm::WasmGlobal Global;
908     Global.Index = NumImportedGlobals + Globals.size();
909     Global.Type.Type = readUint8(Ctx);
910     Global.Type.Mutable = readVaruint1(Ctx);
911     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
912       return Err;
913     Globals.push_back(Global);
914   }
915   if (Ctx.Ptr != Ctx.End)
916     return make_error<GenericBinaryError>("Global section ended prematurely",
917                                           object_error::parse_failed);
918   return Error::success();
919 }
920 
921 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
922   EventSection = Sections.size();
923   uint32_t Count = readVarint32(Ctx);
924   Events.reserve(Count);
925   while (Count--) {
926     wasm::WasmEvent Event;
927     Event.Index = NumImportedEvents + Events.size();
928     Event.Type.Attribute = readVaruint32(Ctx);
929     Event.Type.SigIndex = readVarint32(Ctx);
930     Events.push_back(Event);
931   }
932 
933   if (Ctx.Ptr != Ctx.End)
934     return make_error<GenericBinaryError>("Event section ended prematurely",
935                                           object_error::parse_failed);
936   return Error::success();
937 }
938 
939 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
940   uint32_t Count = readVaruint32(Ctx);
941   Exports.reserve(Count);
942   for (uint32_t i = 0; i < Count; i++) {
943     wasm::WasmExport Ex;
944     Ex.Name = readString(Ctx);
945     Ex.Kind = readUint8(Ctx);
946     Ex.Index = readVaruint32(Ctx);
947     switch (Ex.Kind) {
948     case wasm::WASM_EXTERNAL_FUNCTION:
949       if (!isValidFunctionIndex(Ex.Index))
950         return make_error<GenericBinaryError>("Invalid function export",
951                                               object_error::parse_failed);
952       break;
953     case wasm::WASM_EXTERNAL_GLOBAL:
954       if (!isValidGlobalIndex(Ex.Index))
955         return make_error<GenericBinaryError>("Invalid global export",
956                                               object_error::parse_failed);
957       break;
958     case wasm::WASM_EXTERNAL_EVENT:
959       if (!isValidEventIndex(Ex.Index))
960         return make_error<GenericBinaryError>("Invalid event export",
961                                               object_error::parse_failed);
962       break;
963     case wasm::WASM_EXTERNAL_MEMORY:
964     case wasm::WASM_EXTERNAL_TABLE:
965       break;
966     default:
967       return make_error<GenericBinaryError>("Unexpected export kind",
968                                             object_error::parse_failed);
969     }
970     Exports.push_back(Ex);
971   }
972   if (Ctx.Ptr != Ctx.End)
973     return make_error<GenericBinaryError>("Export section ended prematurely",
974                                           object_error::parse_failed);
975   return Error::success();
976 }
977 
978 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
979   return Index < NumImportedFunctions + FunctionTypes.size();
980 }
981 
982 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
983   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
984 }
985 
986 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
987   return Index < NumImportedGlobals + Globals.size();
988 }
989 
990 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
991   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
992 }
993 
994 bool WasmObjectFile::isValidEventIndex(uint32_t Index) const {
995   return Index < NumImportedEvents + Events.size();
996 }
997 
998 bool WasmObjectFile::isDefinedEventIndex(uint32_t Index) const {
999   return Index >= NumImportedEvents && isValidEventIndex(Index);
1000 }
1001 
1002 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1003   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1004 }
1005 
1006 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1007   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1008 }
1009 
1010 bool WasmObjectFile::isValidEventSymbol(uint32_t Index) const {
1011   return Index < Symbols.size() && Symbols[Index].isTypeEvent();
1012 }
1013 
1014 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1015   return Index < Symbols.size() && Symbols[Index].isTypeData();
1016 }
1017 
1018 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1019   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1020 }
1021 
1022 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1023   assert(isDefinedFunctionIndex(Index));
1024   return Functions[Index - NumImportedFunctions];
1025 }
1026 
1027 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1028   assert(isDefinedGlobalIndex(Index));
1029   return Globals[Index - NumImportedGlobals];
1030 }
1031 
1032 wasm::WasmEvent &WasmObjectFile::getDefinedEvent(uint32_t Index) {
1033   assert(isDefinedEventIndex(Index));
1034   return Events[Index - NumImportedEvents];
1035 }
1036 
1037 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1038   StartFunction = readVaruint32(Ctx);
1039   if (!isValidFunctionIndex(StartFunction))
1040     return make_error<GenericBinaryError>("Invalid start function",
1041                                           object_error::parse_failed);
1042   return Error::success();
1043 }
1044 
1045 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1046   CodeSection = Sections.size();
1047   uint32_t FunctionCount = readVaruint32(Ctx);
1048   if (FunctionCount != FunctionTypes.size()) {
1049     return make_error<GenericBinaryError>("Invalid function count",
1050                                           object_error::parse_failed);
1051   }
1052 
1053   while (FunctionCount--) {
1054     wasm::WasmFunction Function;
1055     const uint8_t *FunctionStart = Ctx.Ptr;
1056     uint32_t Size = readVaruint32(Ctx);
1057     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1058 
1059     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1060     Function.Index = NumImportedFunctions + Functions.size();
1061     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1062     Function.Size = FunctionEnd - FunctionStart;
1063 
1064     uint32_t NumLocalDecls = readVaruint32(Ctx);
1065     Function.Locals.reserve(NumLocalDecls);
1066     while (NumLocalDecls--) {
1067       wasm::WasmLocalDecl Decl;
1068       Decl.Count = readVaruint32(Ctx);
1069       Decl.Type = readUint8(Ctx);
1070       Function.Locals.push_back(Decl);
1071     }
1072 
1073     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1074     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1075     // This will be set later when reading in the linking metadata section.
1076     Function.Comdat = UINT32_MAX;
1077     Ctx.Ptr += BodySize;
1078     assert(Ctx.Ptr == FunctionEnd);
1079     Functions.push_back(Function);
1080   }
1081   if (Ctx.Ptr != Ctx.End)
1082     return make_error<GenericBinaryError>("Code section ended prematurely",
1083                                           object_error::parse_failed);
1084   return Error::success();
1085 }
1086 
1087 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1088   uint32_t Count = readVaruint32(Ctx);
1089   ElemSegments.reserve(Count);
1090   while (Count--) {
1091     wasm::WasmElemSegment Segment;
1092     Segment.TableIndex = readVaruint32(Ctx);
1093     if (Segment.TableIndex != 0) {
1094       return make_error<GenericBinaryError>("Invalid TableIndex",
1095                                             object_error::parse_failed);
1096     }
1097     if (Error Err = readInitExpr(Segment.Offset, Ctx))
1098       return Err;
1099     uint32_t NumElems = readVaruint32(Ctx);
1100     while (NumElems--) {
1101       Segment.Functions.push_back(readVaruint32(Ctx));
1102     }
1103     ElemSegments.push_back(Segment);
1104   }
1105   if (Ctx.Ptr != Ctx.End)
1106     return make_error<GenericBinaryError>("Elem section ended prematurely",
1107                                           object_error::parse_failed);
1108   return Error::success();
1109 }
1110 
1111 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1112   DataSection = Sections.size();
1113   uint32_t Count = readVaruint32(Ctx);
1114   DataSegments.reserve(Count);
1115   while (Count--) {
1116     WasmSegment Segment;
1117     Segment.Data.MemoryIndex = readVaruint32(Ctx);
1118     if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1119       return Err;
1120     uint32_t Size = readVaruint32(Ctx);
1121     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1122       return make_error<GenericBinaryError>("Invalid segment size",
1123                                             object_error::parse_failed);
1124     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1125     // The rest of these Data fields are set later, when reading in the linking
1126     // metadata section.
1127     Segment.Data.Alignment = 0;
1128     Segment.Data.Flags = 0;
1129     Segment.Data.Comdat = UINT32_MAX;
1130     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1131     Ctx.Ptr += Size;
1132     DataSegments.push_back(Segment);
1133   }
1134   if (Ctx.Ptr != Ctx.End)
1135     return make_error<GenericBinaryError>("Data section ended prematurely",
1136                                           object_error::parse_failed);
1137   return Error::success();
1138 }
1139 
1140 const uint8_t *WasmObjectFile::getPtr(size_t Offset) const {
1141   return reinterpret_cast<const uint8_t *>(getData().data() + Offset);
1142 }
1143 
1144 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1145   return Header;
1146 }
1147 
1148 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.a++; }
1149 
1150 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1151   uint32_t Result = SymbolRef::SF_None;
1152   const WasmSymbol &Sym = getWasmSymbol(Symb);
1153 
1154   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1155   if (Sym.isBindingWeak())
1156     Result |= SymbolRef::SF_Weak;
1157   if (!Sym.isBindingLocal())
1158     Result |= SymbolRef::SF_Global;
1159   if (Sym.isHidden())
1160     Result |= SymbolRef::SF_Hidden;
1161   if (!Sym.isDefined())
1162     Result |= SymbolRef::SF_Undefined;
1163   if (Sym.isTypeFunction())
1164     Result |= SymbolRef::SF_Executable;
1165   return Result;
1166 }
1167 
1168 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1169   DataRefImpl Ref;
1170   Ref.d.a = 0;
1171   return BasicSymbolRef(Ref, this);
1172 }
1173 
1174 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1175   DataRefImpl Ref;
1176   Ref.d.a = Symbols.size();
1177   return BasicSymbolRef(Ref, this);
1178 }
1179 
1180 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1181   return Symbols[Symb.d.a];
1182 }
1183 
1184 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1185   return getWasmSymbol(Symb.getRawDataRefImpl());
1186 }
1187 
1188 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1189   return getWasmSymbol(Symb).Info.Name;
1190 }
1191 
1192 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1193   return getSymbolValue(Symb);
1194 }
1195 
1196 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1197   switch (Sym.Info.Kind) {
1198   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1199   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1200   case wasm::WASM_SYMBOL_TYPE_EVENT:
1201     return Sym.Info.ElementIndex;
1202   case wasm::WASM_SYMBOL_TYPE_DATA: {
1203     // The value of a data symbol is the segment offset, plus the symbol
1204     // offset within the segment.
1205     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1206     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1207     assert(Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST);
1208     return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1209   }
1210   case wasm::WASM_SYMBOL_TYPE_SECTION:
1211     return 0;
1212   }
1213   llvm_unreachable("invalid symbol type");
1214 }
1215 
1216 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1217   return getWasmSymbolValue(getWasmSymbol(Symb));
1218 }
1219 
1220 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1221   llvm_unreachable("not yet implemented");
1222   return 0;
1223 }
1224 
1225 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1226   llvm_unreachable("not yet implemented");
1227   return 0;
1228 }
1229 
1230 Expected<SymbolRef::Type>
1231 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1232   const WasmSymbol &Sym = getWasmSymbol(Symb);
1233 
1234   switch (Sym.Info.Kind) {
1235   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1236     return SymbolRef::ST_Function;
1237   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1238     return SymbolRef::ST_Other;
1239   case wasm::WASM_SYMBOL_TYPE_DATA:
1240     return SymbolRef::ST_Data;
1241   case wasm::WASM_SYMBOL_TYPE_SECTION:
1242     return SymbolRef::ST_Debug;
1243   case wasm::WASM_SYMBOL_TYPE_EVENT:
1244     return SymbolRef::ST_Other;
1245   }
1246 
1247   llvm_unreachable("Unknown WasmSymbol::SymbolType");
1248   return SymbolRef::ST_Other;
1249 }
1250 
1251 Expected<section_iterator>
1252 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1253   const WasmSymbol &Sym = getWasmSymbol(Symb);
1254   if (Sym.isUndefined())
1255     return section_end();
1256 
1257   DataRefImpl Ref;
1258   switch (Sym.Info.Kind) {
1259   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1260     Ref.d.a = CodeSection;
1261     break;
1262   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1263     Ref.d.a = GlobalSection;
1264     break;
1265   case wasm::WASM_SYMBOL_TYPE_DATA:
1266     Ref.d.a = DataSection;
1267     break;
1268   case wasm::WASM_SYMBOL_TYPE_SECTION:
1269     Ref.d.a = Sym.Info.ElementIndex;
1270     break;
1271   case wasm::WASM_SYMBOL_TYPE_EVENT:
1272     Ref.d.a = EventSection;
1273     break;
1274   default:
1275     llvm_unreachable("Unknown WasmSymbol::SymbolType");
1276   }
1277   return section_iterator(SectionRef(Ref, this));
1278 }
1279 
1280 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1281 
1282 std::error_code WasmObjectFile::getSectionName(DataRefImpl Sec,
1283                                                StringRef &Res) const {
1284   const WasmSection &S = Sections[Sec.d.a];
1285 #define ECase(X)                                                               \
1286   case wasm::WASM_SEC_##X:                                                     \
1287     Res = #X;                                                                  \
1288     break
1289   switch (S.Type) {
1290     ECase(TYPE);
1291     ECase(IMPORT);
1292     ECase(FUNCTION);
1293     ECase(TABLE);
1294     ECase(MEMORY);
1295     ECase(GLOBAL);
1296     ECase(EVENT);
1297     ECase(EXPORT);
1298     ECase(START);
1299     ECase(ELEM);
1300     ECase(CODE);
1301     ECase(DATA);
1302   case wasm::WASM_SEC_CUSTOM:
1303     Res = S.Name;
1304     break;
1305   default:
1306     return object_error::invalid_section_index;
1307   }
1308 #undef ECase
1309   return std::error_code();
1310 }
1311 
1312 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1313 
1314 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1315   return Sec.d.a;
1316 }
1317 
1318 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1319   const WasmSection &S = Sections[Sec.d.a];
1320   return S.Content.size();
1321 }
1322 
1323 std::error_code WasmObjectFile::getSectionContents(DataRefImpl Sec,
1324                                                    StringRef &Res) const {
1325   const WasmSection &S = Sections[Sec.d.a];
1326   // This will never fail since wasm sections can never be empty (user-sections
1327   // must have a name and non-user sections each have a defined structure).
1328   Res = StringRef(reinterpret_cast<const char *>(S.Content.data()),
1329                   S.Content.size());
1330   return std::error_code();
1331 }
1332 
1333 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1334   return 1;
1335 }
1336 
1337 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1338   return false;
1339 }
1340 
1341 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1342   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1343 }
1344 
1345 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1346   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1347 }
1348 
1349 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1350 
1351 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1352 
1353 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
1354 
1355 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1356   DataRefImpl RelocRef;
1357   RelocRef.d.a = Ref.d.a;
1358   RelocRef.d.b = 0;
1359   return relocation_iterator(RelocationRef(RelocRef, this));
1360 }
1361 
1362 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1363   const WasmSection &Sec = getWasmSection(Ref);
1364   DataRefImpl RelocRef;
1365   RelocRef.d.a = Ref.d.a;
1366   RelocRef.d.b = Sec.Relocations.size();
1367   return relocation_iterator(RelocationRef(RelocRef, this));
1368 }
1369 
1370 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1371 
1372 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1373   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1374   return Rel.Offset;
1375 }
1376 
1377 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1378   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1379   if (Rel.Type == wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB)
1380     return symbol_end();
1381   DataRefImpl Sym;
1382   Sym.d.a = Rel.Index;
1383   Sym.d.b = 0;
1384   return symbol_iterator(SymbolRef(Sym, this));
1385 }
1386 
1387 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1388   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1389   return Rel.Type;
1390 }
1391 
1392 void WasmObjectFile::getRelocationTypeName(
1393     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1394   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1395   StringRef Res = "Unknown";
1396 
1397 #define WASM_RELOC(name, value)                                                \
1398   case wasm::name:                                                             \
1399     Res = #name;                                                               \
1400     break;
1401 
1402   switch (Rel.Type) {
1403 #include "llvm/BinaryFormat/WasmRelocs.def"
1404   }
1405 
1406 #undef WASM_RELOC
1407 
1408   Result.append(Res.begin(), Res.end());
1409 }
1410 
1411 section_iterator WasmObjectFile::section_begin() const {
1412   DataRefImpl Ref;
1413   Ref.d.a = 0;
1414   return section_iterator(SectionRef(Ref, this));
1415 }
1416 
1417 section_iterator WasmObjectFile::section_end() const {
1418   DataRefImpl Ref;
1419   Ref.d.a = Sections.size();
1420   return section_iterator(SectionRef(Ref, this));
1421 }
1422 
1423 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
1424 
1425 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1426 
1427 Triple::ArchType WasmObjectFile::getArch() const { return Triple::wasm32; }
1428 
1429 SubtargetFeatures WasmObjectFile::getFeatures() const {
1430   return SubtargetFeatures();
1431 }
1432 
1433 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1434 
1435 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1436 
1437 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1438   assert(Ref.d.a < Sections.size());
1439   return Sections[Ref.d.a];
1440 }
1441 
1442 const WasmSection &
1443 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1444   return getWasmSection(Section.getRawDataRefImpl());
1445 }
1446 
1447 const wasm::WasmRelocation &
1448 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1449   return getWasmRelocation(Ref.getRawDataRefImpl());
1450 }
1451 
1452 const wasm::WasmRelocation &
1453 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1454   assert(Ref.d.a < Sections.size());
1455   const WasmSection &Sec = Sections[Ref.d.a];
1456   assert(Ref.d.b < Sec.Relocations.size());
1457   return Sec.Relocations[Ref.d.b];
1458 }
1459 
1460 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1461                                              StringRef CustomSectionName) {
1462   switch (ID) {
1463   case wasm::WASM_SEC_CUSTOM:
1464     return StringSwitch<unsigned>(CustomSectionName)
1465         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1466         .Case("linking", WASM_SEC_ORDER_LINKING)
1467         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1468         .Case("name", WASM_SEC_ORDER_NAME)
1469         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1470         .Default(-1);
1471   case wasm::WASM_SEC_TYPE:
1472     return WASM_SEC_ORDER_TYPE;
1473   case wasm::WASM_SEC_IMPORT:
1474     return WASM_SEC_ORDER_IMPORT;
1475   case wasm::WASM_SEC_FUNCTION:
1476     return WASM_SEC_ORDER_FUNCTION;
1477   case wasm::WASM_SEC_TABLE:
1478     return WASM_SEC_ORDER_TABLE;
1479   case wasm::WASM_SEC_MEMORY:
1480     return WASM_SEC_ORDER_MEMORY;
1481   case wasm::WASM_SEC_GLOBAL:
1482     return WASM_SEC_ORDER_GLOBAL;
1483   case wasm::WASM_SEC_EXPORT:
1484     return WASM_SEC_ORDER_EXPORT;
1485   case wasm::WASM_SEC_START:
1486     return WASM_SEC_ORDER_START;
1487   case wasm::WASM_SEC_ELEM:
1488     return WASM_SEC_ORDER_ELEM;
1489   case wasm::WASM_SEC_CODE:
1490     return WASM_SEC_ORDER_CODE;
1491   case wasm::WASM_SEC_DATA:
1492     return WASM_SEC_ORDER_DATA;
1493   case wasm::WASM_SEC_DATACOUNT:
1494     return WASM_SEC_ORDER_DATACOUNT;
1495   case wasm::WASM_SEC_EVENT:
1496     return WASM_SEC_ORDER_EVENT;
1497   default:
1498     llvm_unreachable("invalid section");
1499   }
1500 }
1501 
1502 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1503                                                   StringRef CustomSectionName) {
1504   int Order = getSectionOrder(ID, CustomSectionName);
1505   if (Order == -1) // Skip unknown sections
1506     return true;
1507   // There can be multiple "reloc." sections. Otherwise there shouldn't be any
1508   // duplicate section orders.
1509   bool IsValid = (LastOrder == Order && Order == WASM_SEC_ORDER_RELOC) ||
1510                  LastOrder < Order;
1511   LastOrder = Order;
1512   return IsValid;
1513 }
1514