1 //===- WasmObjectFile.cpp - Wasm object file implementation ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/ADT/ArrayRef.h"
10 #include "llvm/ADT/DenseSet.h"
11 #include "llvm/ADT/STLExtras.h"
12 #include "llvm/ADT/SmallSet.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/ADT/StringSet.h"
15 #include "llvm/ADT/StringSwitch.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/BinaryFormat/Wasm.h"
18 #include "llvm/MC/SubtargetFeature.h"
19 #include "llvm/Object/Binary.h"
20 #include "llvm/Object/Error.h"
21 #include "llvm/Object/ObjectFile.h"
22 #include "llvm/Object/SymbolicFile.h"
23 #include "llvm/Object/Wasm.h"
24 #include "llvm/Support/Endian.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/LEB128.h"
28 #include "llvm/Support/ScopedPrinter.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cstdint>
32 #include <cstring>
33 #include <system_error>
34 
35 #define DEBUG_TYPE "wasm-object"
36 
37 using namespace llvm;
38 using namespace object;
39 
40 void WasmSymbol::print(raw_ostream &Out) const {
41   Out << "Name=" << Info.Name
42       << ", Kind=" << toString(wasm::WasmSymbolType(Info.Kind))
43       << ", Flags=" << Info.Flags;
44   if (!isTypeData()) {
45     Out << ", ElemIndex=" << Info.ElementIndex;
46   } else if (isDefined()) {
47     Out << ", Segment=" << Info.DataRef.Segment;
48     Out << ", Offset=" << Info.DataRef.Offset;
49     Out << ", Size=" << Info.DataRef.Size;
50   }
51 }
52 
53 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
54 LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
55 #endif
56 
57 Expected<std::unique_ptr<WasmObjectFile>>
58 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
59   Error Err = Error::success();
60   auto ObjectFile = std::make_unique<WasmObjectFile>(Buffer, Err);
61   if (Err)
62     return std::move(Err);
63 
64   return std::move(ObjectFile);
65 }
66 
67 #define VARINT7_MAX ((1 << 7) - 1)
68 #define VARINT7_MIN (-(1 << 7))
69 #define VARUINT7_MAX (1 << 7)
70 #define VARUINT1_MAX (1)
71 
72 static uint8_t readUint8(WasmObjectFile::ReadContext &Ctx) {
73   if (Ctx.Ptr == Ctx.End)
74     report_fatal_error("EOF while reading uint8");
75   return *Ctx.Ptr++;
76 }
77 
78 static uint32_t readUint32(WasmObjectFile::ReadContext &Ctx) {
79   if (Ctx.Ptr + 4 > Ctx.End)
80     report_fatal_error("EOF while reading uint32");
81   uint32_t Result = support::endian::read32le(Ctx.Ptr);
82   Ctx.Ptr += 4;
83   return Result;
84 }
85 
86 static int32_t readFloat32(WasmObjectFile::ReadContext &Ctx) {
87   if (Ctx.Ptr + 4 > Ctx.End)
88     report_fatal_error("EOF while reading float64");
89   int32_t Result = 0;
90   memcpy(&Result, Ctx.Ptr, sizeof(Result));
91   Ctx.Ptr += sizeof(Result);
92   return Result;
93 }
94 
95 static int64_t readFloat64(WasmObjectFile::ReadContext &Ctx) {
96   if (Ctx.Ptr + 8 > Ctx.End)
97     report_fatal_error("EOF while reading float64");
98   int64_t Result = 0;
99   memcpy(&Result, Ctx.Ptr, sizeof(Result));
100   Ctx.Ptr += sizeof(Result);
101   return Result;
102 }
103 
104 static uint64_t readULEB128(WasmObjectFile::ReadContext &Ctx) {
105   unsigned Count;
106   const char *Error = nullptr;
107   uint64_t Result = decodeULEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
108   if (Error)
109     report_fatal_error(Error);
110   Ctx.Ptr += Count;
111   return Result;
112 }
113 
114 static StringRef readString(WasmObjectFile::ReadContext &Ctx) {
115   uint32_t StringLen = readULEB128(Ctx);
116   if (Ctx.Ptr + StringLen > Ctx.End)
117     report_fatal_error("EOF while reading string");
118   StringRef Return =
119       StringRef(reinterpret_cast<const char *>(Ctx.Ptr), StringLen);
120   Ctx.Ptr += StringLen;
121   return Return;
122 }
123 
124 static int64_t readLEB128(WasmObjectFile::ReadContext &Ctx) {
125   unsigned Count;
126   const char *Error = nullptr;
127   uint64_t Result = decodeSLEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
128   if (Error)
129     report_fatal_error(Error);
130   Ctx.Ptr += Count;
131   return Result;
132 }
133 
134 static uint8_t readVaruint1(WasmObjectFile::ReadContext &Ctx) {
135   int64_t Result = readLEB128(Ctx);
136   if (Result > VARUINT1_MAX || Result < 0)
137     report_fatal_error("LEB is outside Varuint1 range");
138   return Result;
139 }
140 
141 static int32_t readVarint32(WasmObjectFile::ReadContext &Ctx) {
142   int64_t Result = readLEB128(Ctx);
143   if (Result > INT32_MAX || Result < INT32_MIN)
144     report_fatal_error("LEB is outside Varint32 range");
145   return Result;
146 }
147 
148 static uint32_t readVaruint32(WasmObjectFile::ReadContext &Ctx) {
149   uint64_t Result = readULEB128(Ctx);
150   if (Result > UINT32_MAX)
151     report_fatal_error("LEB is outside Varuint32 range");
152   return Result;
153 }
154 
155 static int64_t readVarint64(WasmObjectFile::ReadContext &Ctx) {
156   return readLEB128(Ctx);
157 }
158 
159 static uint64_t readVaruint64(WasmObjectFile::ReadContext &Ctx) {
160   return readULEB128(Ctx);
161 }
162 
163 static uint8_t readOpcode(WasmObjectFile::ReadContext &Ctx) {
164   return readUint8(Ctx);
165 }
166 
167 static Error readInitExpr(wasm::WasmInitExpr &Expr,
168                           WasmObjectFile::ReadContext &Ctx) {
169   Expr.Opcode = readOpcode(Ctx);
170 
171   switch (Expr.Opcode) {
172   case wasm::WASM_OPCODE_I32_CONST:
173     Expr.Value.Int32 = readVarint32(Ctx);
174     break;
175   case wasm::WASM_OPCODE_I64_CONST:
176     Expr.Value.Int64 = readVarint64(Ctx);
177     break;
178   case wasm::WASM_OPCODE_F32_CONST:
179     Expr.Value.Float32 = readFloat32(Ctx);
180     break;
181   case wasm::WASM_OPCODE_F64_CONST:
182     Expr.Value.Float64 = readFloat64(Ctx);
183     break;
184   case wasm::WASM_OPCODE_GLOBAL_GET:
185     Expr.Value.Global = readULEB128(Ctx);
186     break;
187   case wasm::WASM_OPCODE_REF_NULL: {
188     wasm::ValType Ty = static_cast<wasm::ValType>(readULEB128(Ctx));
189     if (Ty != wasm::ValType::EXTERNREF) {
190       return make_error<GenericBinaryError>("Invalid type for ref.null",
191                                             object_error::parse_failed);
192     }
193     break;
194   }
195   default:
196     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
197                                           object_error::parse_failed);
198   }
199 
200   uint8_t EndOpcode = readOpcode(Ctx);
201   if (EndOpcode != wasm::WASM_OPCODE_END) {
202     return make_error<GenericBinaryError>("Invalid init_expr",
203                                           object_error::parse_failed);
204   }
205   return Error::success();
206 }
207 
208 static wasm::WasmLimits readLimits(WasmObjectFile::ReadContext &Ctx) {
209   wasm::WasmLimits Result;
210   Result.Flags = readVaruint32(Ctx);
211   Result.Initial = readVaruint64(Ctx);
212   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
213     Result.Maximum = readVaruint64(Ctx);
214   return Result;
215 }
216 
217 static wasm::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 =
266         make_error<StringError>("Bad magic number", 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>("Bad version number",
284                                   object_error::parse_failed);
285     return;
286   }
287 
288   WasmSection Sec;
289   WasmSectionOrderChecker Checker;
290   while (Ctx.Ptr < Ctx.End) {
291     if ((Err = readSection(Sec, Ctx, Checker)))
292       return;
293     if ((Err = parseSection(Sec)))
294       return;
295 
296     Sections.push_back(Sec);
297   }
298 }
299 
300 Error WasmObjectFile::parseSection(WasmSection &Sec) {
301   ReadContext Ctx;
302   Ctx.Start = Sec.Content.data();
303   Ctx.End = Ctx.Start + Sec.Content.size();
304   Ctx.Ptr = Ctx.Start;
305   switch (Sec.Type) {
306   case wasm::WASM_SEC_CUSTOM:
307     return parseCustomSection(Sec, Ctx);
308   case wasm::WASM_SEC_TYPE:
309     return parseTypeSection(Ctx);
310   case wasm::WASM_SEC_IMPORT:
311     return parseImportSection(Ctx);
312   case wasm::WASM_SEC_FUNCTION:
313     return parseFunctionSection(Ctx);
314   case wasm::WASM_SEC_TABLE:
315     return parseTableSection(Ctx);
316   case wasm::WASM_SEC_MEMORY:
317     return parseMemorySection(Ctx);
318   case wasm::WASM_SEC_EVENT:
319     return parseEventSection(Ctx);
320   case wasm::WASM_SEC_GLOBAL:
321     return parseGlobalSection(Ctx);
322   case wasm::WASM_SEC_EXPORT:
323     return parseExportSection(Ctx);
324   case wasm::WASM_SEC_START:
325     return parseStartSection(Ctx);
326   case wasm::WASM_SEC_ELEM:
327     return parseElemSection(Ctx);
328   case wasm::WASM_SEC_CODE:
329     return parseCodeSection(Ctx);
330   case wasm::WASM_SEC_DATA:
331     return parseDataSection(Ctx);
332   case wasm::WASM_SEC_DATACOUNT:
333     return parseDataCountSection(Ctx);
334   default:
335     return make_error<GenericBinaryError>(
336         "Invalid section type: " + Twine(Sec.Type), object_error::parse_failed);
337   }
338 }
339 
340 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
341   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
342   HasDylinkSection = true;
343   DylinkInfo.MemorySize = readVaruint32(Ctx);
344   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
345   DylinkInfo.TableSize = readVaruint32(Ctx);
346   DylinkInfo.TableAlignment = readVaruint32(Ctx);
347   uint32_t Count = readVaruint32(Ctx);
348   while (Count--) {
349     DylinkInfo.Needed.push_back(readString(Ctx));
350   }
351   if (Ctx.Ptr != Ctx.End)
352     return make_error<GenericBinaryError>("dylink section ended prematurely",
353                                           object_error::parse_failed);
354   return Error::success();
355 }
356 
357 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
358   llvm::DenseSet<uint64_t> SeenFunctions;
359   llvm::DenseSet<uint64_t> SeenGlobals;
360   if (FunctionTypes.size() && !SeenCodeSection) {
361     return make_error<GenericBinaryError>("Names must come after code section",
362                                           object_error::parse_failed);
363   }
364 
365   while (Ctx.Ptr < Ctx.End) {
366     uint8_t Type = readUint8(Ctx);
367     uint32_t Size = readVaruint32(Ctx);
368     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
369     switch (Type) {
370     case wasm::WASM_NAMES_FUNCTION:
371     case wasm::WASM_NAMES_GLOBAL: {
372       uint32_t Count = readVaruint32(Ctx);
373       while (Count--) {
374         uint32_t Index = readVaruint32(Ctx);
375         StringRef Name = readString(Ctx);
376         if (Type == wasm::WASM_NAMES_FUNCTION) {
377           if (!SeenFunctions.insert(Index).second)
378             return make_error<GenericBinaryError>(
379                 "Function named more than once", object_error::parse_failed);
380           if (!isValidFunctionIndex(Index) || Name.empty())
381             return make_error<GenericBinaryError>("Invalid name entry",
382                                                   object_error::parse_failed);
383 
384           if (isDefinedFunctionIndex(Index))
385             getDefinedFunction(Index).DebugName = Name;
386         } else {
387           if (!SeenGlobals.insert(Index).second)
388             return make_error<GenericBinaryError>("Global named more than once",
389                                                   object_error::parse_failed);
390           if (!isValidGlobalIndex(Index) || Name.empty())
391             return make_error<GenericBinaryError>("Invalid name entry",
392                                                   object_error::parse_failed);
393         }
394         wasm::NameType T = Type == wasm::WASM_NAMES_FUNCTION
395                                ? wasm::NameType::FUNCTION
396                                : wasm::NameType::GLOBAL;
397         DebugNames.push_back(wasm::WasmDebugName{T, Index, Name});
398       }
399       break;
400     }
401     // Ignore local names for now
402     case wasm::WASM_NAMES_LOCAL:
403     default:
404       Ctx.Ptr += Size;
405       break;
406     }
407     if (Ctx.Ptr != SubSectionEnd)
408       return make_error<GenericBinaryError>(
409           "Name sub-section ended prematurely", object_error::parse_failed);
410   }
411 
412   if (Ctx.Ptr != Ctx.End)
413     return make_error<GenericBinaryError>("Name section ended prematurely",
414                                           object_error::parse_failed);
415   return Error::success();
416 }
417 
418 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
419   HasLinkingSection = true;
420   if (FunctionTypes.size() && !SeenCodeSection) {
421     return make_error<GenericBinaryError>(
422         "Linking data must come after code section",
423         object_error::parse_failed);
424   }
425 
426   LinkingData.Version = readVaruint32(Ctx);
427   if (LinkingData.Version != wasm::WasmMetadataVersion) {
428     return make_error<GenericBinaryError>(
429         "Unexpected metadata version: " + Twine(LinkingData.Version) +
430             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
431         object_error::parse_failed);
432   }
433 
434   const uint8_t *OrigEnd = Ctx.End;
435   while (Ctx.Ptr < OrigEnd) {
436     Ctx.End = OrigEnd;
437     uint8_t Type = readUint8(Ctx);
438     uint32_t Size = readVaruint32(Ctx);
439     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
440                       << "\n");
441     Ctx.End = Ctx.Ptr + Size;
442     switch (Type) {
443     case wasm::WASM_SYMBOL_TABLE:
444       if (Error Err = parseLinkingSectionSymtab(Ctx))
445         return Err;
446       break;
447     case wasm::WASM_SEGMENT_INFO: {
448       uint32_t Count = readVaruint32(Ctx);
449       if (Count > DataSegments.size())
450         return make_error<GenericBinaryError>("Too many segment names",
451                                               object_error::parse_failed);
452       for (uint32_t I = 0; I < Count; I++) {
453         DataSegments[I].Data.Name = readString(Ctx);
454         DataSegments[I].Data.Alignment = readVaruint32(Ctx);
455         DataSegments[I].Data.LinkerFlags = readVaruint32(Ctx);
456       }
457       break;
458     }
459     case wasm::WASM_INIT_FUNCS: {
460       uint32_t Count = readVaruint32(Ctx);
461       LinkingData.InitFunctions.reserve(Count);
462       for (uint32_t I = 0; I < Count; I++) {
463         wasm::WasmInitFunc Init;
464         Init.Priority = readVaruint32(Ctx);
465         Init.Symbol = readVaruint32(Ctx);
466         if (!isValidFunctionSymbol(Init.Symbol))
467           return make_error<GenericBinaryError>("Invalid function symbol: " +
468                                                     Twine(Init.Symbol),
469                                                 object_error::parse_failed);
470         LinkingData.InitFunctions.emplace_back(Init);
471       }
472       break;
473     }
474     case wasm::WASM_COMDAT_INFO:
475       if (Error Err = parseLinkingSectionComdat(Ctx))
476         return Err;
477       break;
478     default:
479       Ctx.Ptr += Size;
480       break;
481     }
482     if (Ctx.Ptr != Ctx.End)
483       return make_error<GenericBinaryError>(
484           "Linking sub-section ended prematurely", object_error::parse_failed);
485   }
486   if (Ctx.Ptr != OrigEnd)
487     return make_error<GenericBinaryError>("Linking section ended prematurely",
488                                           object_error::parse_failed);
489   return Error::success();
490 }
491 
492 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
493   uint32_t Count = readVaruint32(Ctx);
494   LinkingData.SymbolTable.reserve(Count);
495   Symbols.reserve(Count);
496   StringSet<> SymbolNames;
497 
498   std::vector<wasm::WasmImport *> ImportedGlobals;
499   std::vector<wasm::WasmImport *> ImportedFunctions;
500   std::vector<wasm::WasmImport *> ImportedEvents;
501   std::vector<wasm::WasmImport *> ImportedTables;
502   ImportedGlobals.reserve(Imports.size());
503   ImportedFunctions.reserve(Imports.size());
504   ImportedEvents.reserve(Imports.size());
505   ImportedTables.reserve(Imports.size());
506   for (auto &I : Imports) {
507     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
508       ImportedFunctions.emplace_back(&I);
509     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
510       ImportedGlobals.emplace_back(&I);
511     else if (I.Kind == wasm::WASM_EXTERNAL_EVENT)
512       ImportedEvents.emplace_back(&I);
513     else if (I.Kind == wasm::WASM_EXTERNAL_TABLE)
514       ImportedTables.emplace_back(&I);
515   }
516 
517   while (Count--) {
518     wasm::WasmSymbolInfo Info;
519     const wasm::WasmSignature *Signature = nullptr;
520     const wasm::WasmGlobalType *GlobalType = nullptr;
521     uint8_t TableType = 0;
522     const wasm::WasmEventType *EventType = nullptr;
523 
524     Info.Kind = readUint8(Ctx);
525     Info.Flags = readVaruint32(Ctx);
526     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
527 
528     switch (Info.Kind) {
529     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
530       Info.ElementIndex = readVaruint32(Ctx);
531       if (!isValidFunctionIndex(Info.ElementIndex) ||
532           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
533         return make_error<GenericBinaryError>("invalid function symbol index",
534                                               object_error::parse_failed);
535       if (IsDefined) {
536         Info.Name = readString(Ctx);
537         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
538         Signature = &Signatures[FunctionTypes[FuncIndex]];
539         wasm::WasmFunction &Function = Functions[FuncIndex];
540         if (Function.SymbolName.empty())
541           Function.SymbolName = Info.Name;
542       } else {
543         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
544         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
545           Info.Name = readString(Ctx);
546           Info.ImportName = Import.Field;
547         } else {
548           Info.Name = Import.Field;
549         }
550         Signature = &Signatures[Import.SigIndex];
551         if (!Import.Module.empty()) {
552           Info.ImportModule = Import.Module;
553         }
554       }
555       break;
556 
557     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
558       Info.ElementIndex = readVaruint32(Ctx);
559       if (!isValidGlobalIndex(Info.ElementIndex) ||
560           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
561         return make_error<GenericBinaryError>("invalid global symbol index",
562                                               object_error::parse_failed);
563       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
564                             wasm::WASM_SYMBOL_BINDING_WEAK)
565         return make_error<GenericBinaryError>("undefined weak global symbol",
566                                               object_error::parse_failed);
567       if (IsDefined) {
568         Info.Name = readString(Ctx);
569         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
570         wasm::WasmGlobal &Global = Globals[GlobalIndex];
571         GlobalType = &Global.Type;
572         if (Global.SymbolName.empty())
573           Global.SymbolName = Info.Name;
574       } else {
575         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
576         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
577           Info.Name = readString(Ctx);
578           Info.ImportName = Import.Field;
579         } else {
580           Info.Name = Import.Field;
581         }
582         GlobalType = &Import.Global;
583         if (!Import.Module.empty()) {
584           Info.ImportModule = Import.Module;
585         }
586       }
587       break;
588 
589     case wasm::WASM_SYMBOL_TYPE_TABLE:
590       Info.ElementIndex = readVaruint32(Ctx);
591       if (!isValidTableIndex(Info.ElementIndex) ||
592           IsDefined != isDefinedTableIndex(Info.ElementIndex))
593         return make_error<GenericBinaryError>("invalid table symbol index",
594                                               object_error::parse_failed);
595       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
596                             wasm::WASM_SYMBOL_BINDING_WEAK)
597         return make_error<GenericBinaryError>("undefined weak table symbol",
598                                               object_error::parse_failed);
599       if (IsDefined) {
600         Info.Name = readString(Ctx);
601         unsigned TableIndex = Info.ElementIndex - NumImportedTables;
602         wasm::WasmTable &Table = Tables[TableIndex];
603         TableType = Table.Type.ElemType;
604         if (Table.SymbolName.empty())
605           Table.SymbolName = Info.Name;
606       } else {
607         wasm::WasmImport &Import = *ImportedTables[Info.ElementIndex];
608         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
609           Info.Name = readString(Ctx);
610           Info.ImportName = Import.Field;
611         } else {
612           Info.Name = Import.Field;
613         }
614         TableType = Import.Table.ElemType;
615         // FIXME: Parse limits here too.
616         if (!Import.Module.empty()) {
617           Info.ImportModule = Import.Module;
618         }
619       }
620       break;
621 
622     case wasm::WASM_SYMBOL_TYPE_DATA:
623       Info.Name = readString(Ctx);
624       if (IsDefined) {
625         auto Index = readVaruint32(Ctx);
626         if (Index >= DataSegments.size())
627           return make_error<GenericBinaryError>("invalid data symbol index",
628                                                 object_error::parse_failed);
629         auto Offset = readVaruint64(Ctx);
630         auto Size = readVaruint64(Ctx);
631         if (Offset + Size > DataSegments[Index].Data.Content.size())
632           return make_error<GenericBinaryError>("invalid data symbol offset",
633                                                 object_error::parse_failed);
634         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
635       }
636       break;
637 
638     case wasm::WASM_SYMBOL_TYPE_SECTION: {
639       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
640           wasm::WASM_SYMBOL_BINDING_LOCAL)
641         return make_error<GenericBinaryError>(
642             "Section symbols must have local binding",
643             object_error::parse_failed);
644       Info.ElementIndex = readVaruint32(Ctx);
645       // Use somewhat unique section name as symbol name.
646       StringRef SectionName = Sections[Info.ElementIndex].Name;
647       Info.Name = SectionName;
648       break;
649     }
650 
651     case wasm::WASM_SYMBOL_TYPE_EVENT: {
652       Info.ElementIndex = readVaruint32(Ctx);
653       if (!isValidEventIndex(Info.ElementIndex) ||
654           IsDefined != isDefinedEventIndex(Info.ElementIndex))
655         return make_error<GenericBinaryError>("invalid event symbol index",
656                                               object_error::parse_failed);
657       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
658                             wasm::WASM_SYMBOL_BINDING_WEAK)
659         return make_error<GenericBinaryError>("undefined weak global symbol",
660                                               object_error::parse_failed);
661       if (IsDefined) {
662         Info.Name = readString(Ctx);
663         unsigned EventIndex = Info.ElementIndex - NumImportedEvents;
664         wasm::WasmEvent &Event = Events[EventIndex];
665         Signature = &Signatures[Event.Type.SigIndex];
666         EventType = &Event.Type;
667         if (Event.SymbolName.empty())
668           Event.SymbolName = Info.Name;
669 
670       } else {
671         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
672         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
673           Info.Name = readString(Ctx);
674           Info.ImportName = Import.Field;
675         } else {
676           Info.Name = Import.Field;
677         }
678         EventType = &Import.Event;
679         Signature = &Signatures[EventType->SigIndex];
680         if (!Import.Module.empty()) {
681           Info.ImportModule = Import.Module;
682         }
683       }
684       break;
685     }
686 
687     default:
688       return make_error<GenericBinaryError>("Invalid symbol type",
689                                             object_error::parse_failed);
690     }
691 
692     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
693             wasm::WASM_SYMBOL_BINDING_LOCAL &&
694         !SymbolNames.insert(Info.Name).second)
695       return make_error<GenericBinaryError>("Duplicate symbol name " +
696                                                 Twine(Info.Name),
697                                             object_error::parse_failed);
698     LinkingData.SymbolTable.emplace_back(Info);
699     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, TableType,
700                          EventType, Signature);
701     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
702   }
703 
704   return Error::success();
705 }
706 
707 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
708   uint32_t ComdatCount = readVaruint32(Ctx);
709   StringSet<> ComdatSet;
710   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
711     StringRef Name = readString(Ctx);
712     if (Name.empty() || !ComdatSet.insert(Name).second)
713       return make_error<GenericBinaryError>("Bad/duplicate COMDAT name " +
714                                                 Twine(Name),
715                                             object_error::parse_failed);
716     LinkingData.Comdats.emplace_back(Name);
717     uint32_t Flags = readVaruint32(Ctx);
718     if (Flags != 0)
719       return make_error<GenericBinaryError>("Unsupported COMDAT flags",
720                                             object_error::parse_failed);
721 
722     uint32_t EntryCount = readVaruint32(Ctx);
723     while (EntryCount--) {
724       unsigned Kind = readVaruint32(Ctx);
725       unsigned Index = readVaruint32(Ctx);
726       switch (Kind) {
727       default:
728         return make_error<GenericBinaryError>("Invalid COMDAT entry type",
729                                               object_error::parse_failed);
730       case wasm::WASM_COMDAT_DATA:
731         if (Index >= DataSegments.size())
732           return make_error<GenericBinaryError>(
733               "COMDAT data index out of range", object_error::parse_failed);
734         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
735           return make_error<GenericBinaryError>("Data segment in two COMDATs",
736                                                 object_error::parse_failed);
737         DataSegments[Index].Data.Comdat = ComdatIndex;
738         break;
739       case wasm::WASM_COMDAT_FUNCTION:
740         if (!isDefinedFunctionIndex(Index))
741           return make_error<GenericBinaryError>(
742               "COMDAT function index out of range", object_error::parse_failed);
743         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
744           return make_error<GenericBinaryError>("Function in two COMDATs",
745                                                 object_error::parse_failed);
746         getDefinedFunction(Index).Comdat = ComdatIndex;
747         break;
748       case wasm::WASM_COMDAT_SECTION:
749         if (Index >= Sections.size())
750           return make_error<GenericBinaryError>(
751               "COMDAT section index out of range", object_error::parse_failed);
752         if (Sections[Index].Type != wasm::WASM_SEC_CUSTOM)
753           return make_error<GenericBinaryError>(
754               "Non-custom section in a COMDAT", object_error::parse_failed);
755         Sections[Index].Comdat = ComdatIndex;
756         break;
757       }
758     }
759   }
760   return Error::success();
761 }
762 
763 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
764   llvm::SmallSet<StringRef, 3> FieldsSeen;
765   uint32_t Fields = readVaruint32(Ctx);
766   for (size_t I = 0; I < Fields; ++I) {
767     StringRef FieldName = readString(Ctx);
768     if (!FieldsSeen.insert(FieldName).second)
769       return make_error<GenericBinaryError>(
770           "Producers section does not have unique fields",
771           object_error::parse_failed);
772     std::vector<std::pair<std::string, std::string>> *ProducerVec = nullptr;
773     if (FieldName == "language") {
774       ProducerVec = &ProducerInfo.Languages;
775     } else if (FieldName == "processed-by") {
776       ProducerVec = &ProducerInfo.Tools;
777     } else if (FieldName == "sdk") {
778       ProducerVec = &ProducerInfo.SDKs;
779     } else {
780       return make_error<GenericBinaryError>(
781           "Producers section field is not named one of language, processed-by, "
782           "or sdk",
783           object_error::parse_failed);
784     }
785     uint32_t ValueCount = readVaruint32(Ctx);
786     llvm::SmallSet<StringRef, 8> ProducersSeen;
787     for (size_t J = 0; J < ValueCount; ++J) {
788       StringRef Name = readString(Ctx);
789       StringRef Version = readString(Ctx);
790       if (!ProducersSeen.insert(Name).second) {
791         return make_error<GenericBinaryError>(
792             "Producers section contains repeated producer",
793             object_error::parse_failed);
794       }
795       ProducerVec->emplace_back(std::string(Name), std::string(Version));
796     }
797   }
798   if (Ctx.Ptr != Ctx.End)
799     return make_error<GenericBinaryError>("Producers section ended prematurely",
800                                           object_error::parse_failed);
801   return Error::success();
802 }
803 
804 Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
805   llvm::SmallSet<std::string, 8> FeaturesSeen;
806   uint32_t FeatureCount = readVaruint32(Ctx);
807   for (size_t I = 0; I < FeatureCount; ++I) {
808     wasm::WasmFeatureEntry Feature;
809     Feature.Prefix = readUint8(Ctx);
810     switch (Feature.Prefix) {
811     case wasm::WASM_FEATURE_PREFIX_USED:
812     case wasm::WASM_FEATURE_PREFIX_REQUIRED:
813     case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
814       break;
815     default:
816       return make_error<GenericBinaryError>("Unknown feature policy prefix",
817                                             object_error::parse_failed);
818     }
819     Feature.Name = std::string(readString(Ctx));
820     if (!FeaturesSeen.insert(Feature.Name).second)
821       return make_error<GenericBinaryError>(
822           "Target features section contains repeated feature \"" +
823               Feature.Name + "\"",
824           object_error::parse_failed);
825     TargetFeatures.push_back(Feature);
826   }
827   if (Ctx.Ptr != Ctx.End)
828     return make_error<GenericBinaryError>(
829         "Target features section ended prematurely",
830         object_error::parse_failed);
831   return Error::success();
832 }
833 
834 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
835   uint32_t SectionIndex = readVaruint32(Ctx);
836   if (SectionIndex >= Sections.size())
837     return make_error<GenericBinaryError>("Invalid section index",
838                                           object_error::parse_failed);
839   WasmSection &Section = Sections[SectionIndex];
840   uint32_t RelocCount = readVaruint32(Ctx);
841   uint32_t EndOffset = Section.Content.size();
842   uint32_t PreviousOffset = 0;
843   while (RelocCount--) {
844     wasm::WasmRelocation Reloc = {};
845     Reloc.Type = readVaruint32(Ctx);
846     Reloc.Offset = readVaruint32(Ctx);
847     if (Reloc.Offset < PreviousOffset)
848       return make_error<GenericBinaryError>("Relocations not in offset order",
849                                             object_error::parse_failed);
850     PreviousOffset = Reloc.Offset;
851     Reloc.Index = readVaruint32(Ctx);
852     switch (Reloc.Type) {
853     case wasm::R_WASM_FUNCTION_INDEX_LEB:
854     case wasm::R_WASM_TABLE_INDEX_SLEB:
855     case wasm::R_WASM_TABLE_INDEX_SLEB64:
856     case wasm::R_WASM_TABLE_INDEX_I32:
857     case wasm::R_WASM_TABLE_INDEX_I64:
858     case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
859       if (!isValidFunctionSymbol(Reloc.Index))
860         return make_error<GenericBinaryError>("Bad relocation function index",
861                                               object_error::parse_failed);
862       break;
863     case wasm::R_WASM_TABLE_NUMBER_LEB:
864       if (!isValidTableSymbol(Reloc.Index))
865         return make_error<GenericBinaryError>("Bad relocation table index",
866                                               object_error::parse_failed);
867       break;
868     case wasm::R_WASM_TYPE_INDEX_LEB:
869       if (Reloc.Index >= Signatures.size())
870         return make_error<GenericBinaryError>("Bad relocation type index",
871                                               object_error::parse_failed);
872       break;
873     case wasm::R_WASM_GLOBAL_INDEX_LEB:
874       // R_WASM_GLOBAL_INDEX_LEB are can be used against function and data
875       // symbols to refer to their GOT entries.
876       if (!isValidGlobalSymbol(Reloc.Index) &&
877           !isValidDataSymbol(Reloc.Index) &&
878           !isValidFunctionSymbol(Reloc.Index))
879         return make_error<GenericBinaryError>("Bad relocation global index",
880                                               object_error::parse_failed);
881       break;
882     case wasm::R_WASM_GLOBAL_INDEX_I32:
883       if (!isValidGlobalSymbol(Reloc.Index))
884         return make_error<GenericBinaryError>("Bad relocation global index",
885                                               object_error::parse_failed);
886       break;
887     case wasm::R_WASM_EVENT_INDEX_LEB:
888       if (!isValidEventSymbol(Reloc.Index))
889         return make_error<GenericBinaryError>("Bad relocation event index",
890                                               object_error::parse_failed);
891       break;
892     case wasm::R_WASM_MEMORY_ADDR_LEB:
893     case wasm::R_WASM_MEMORY_ADDR_SLEB:
894     case wasm::R_WASM_MEMORY_ADDR_I32:
895     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
896     case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
897       if (!isValidDataSymbol(Reloc.Index))
898         return make_error<GenericBinaryError>("Bad relocation data index",
899                                               object_error::parse_failed);
900       Reloc.Addend = readVarint32(Ctx);
901       break;
902     case wasm::R_WASM_MEMORY_ADDR_LEB64:
903     case wasm::R_WASM_MEMORY_ADDR_SLEB64:
904     case wasm::R_WASM_MEMORY_ADDR_I64:
905     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
906       if (!isValidDataSymbol(Reloc.Index))
907         return make_error<GenericBinaryError>("Bad relocation data index",
908                                               object_error::parse_failed);
909       Reloc.Addend = readVarint64(Ctx);
910       break;
911     case wasm::R_WASM_FUNCTION_OFFSET_I32:
912       if (!isValidFunctionSymbol(Reloc.Index))
913         return make_error<GenericBinaryError>("Bad relocation function index",
914                                               object_error::parse_failed);
915       Reloc.Addend = readVarint32(Ctx);
916       break;
917     case wasm::R_WASM_FUNCTION_OFFSET_I64:
918       if (!isValidFunctionSymbol(Reloc.Index))
919         return make_error<GenericBinaryError>("Bad relocation function index",
920                                               object_error::parse_failed);
921       Reloc.Addend = readVarint64(Ctx);
922       break;
923     case wasm::R_WASM_SECTION_OFFSET_I32:
924       if (!isValidSectionSymbol(Reloc.Index))
925         return make_error<GenericBinaryError>("Bad relocation section index",
926                                               object_error::parse_failed);
927       Reloc.Addend = readVarint32(Ctx);
928       break;
929     default:
930       return make_error<GenericBinaryError>("Bad relocation type: " +
931                                                 Twine(Reloc.Type),
932                                             object_error::parse_failed);
933     }
934 
935     // Relocations must fit inside the section, and must appear in order.  They
936     // also shouldn't overlap a function/element boundary, but we don't bother
937     // to check that.
938     uint64_t Size = 5;
939     if (Reloc.Type == wasm::R_WASM_MEMORY_ADDR_LEB64 ||
940         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_SLEB64 ||
941         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_REL_SLEB64)
942       Size = 10;
943     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I32 ||
944         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I32 ||
945         Reloc.Type == wasm::R_WASM_SECTION_OFFSET_I32 ||
946         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
947         Reloc.Type == wasm::R_WASM_GLOBAL_INDEX_I32)
948       Size = 4;
949     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I64 ||
950         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64 ||
951         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I64)
952       Size = 8;
953     if (Reloc.Offset + Size > EndOffset)
954       return make_error<GenericBinaryError>("Bad relocation offset",
955                                             object_error::parse_failed);
956 
957     Section.Relocations.push_back(Reloc);
958   }
959   if (Ctx.Ptr != Ctx.End)
960     return make_error<GenericBinaryError>("Reloc section ended prematurely",
961                                           object_error::parse_failed);
962   return Error::success();
963 }
964 
965 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
966   if (Sec.Name == "dylink") {
967     if (Error Err = parseDylinkSection(Ctx))
968       return Err;
969   } else if (Sec.Name == "name") {
970     if (Error Err = parseNameSection(Ctx))
971       return Err;
972   } else if (Sec.Name == "linking") {
973     if (Error Err = parseLinkingSection(Ctx))
974       return Err;
975   } else if (Sec.Name == "producers") {
976     if (Error Err = parseProducersSection(Ctx))
977       return Err;
978   } else if (Sec.Name == "target_features") {
979     if (Error Err = parseTargetFeaturesSection(Ctx))
980       return Err;
981   } else if (Sec.Name.startswith("reloc.")) {
982     if (Error Err = parseRelocSection(Sec.Name, Ctx))
983       return Err;
984   }
985   return Error::success();
986 }
987 
988 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
989   uint32_t Count = readVaruint32(Ctx);
990   Signatures.reserve(Count);
991   while (Count--) {
992     wasm::WasmSignature Sig;
993     uint8_t Form = readUint8(Ctx);
994     if (Form != wasm::WASM_TYPE_FUNC) {
995       return make_error<GenericBinaryError>("Invalid signature type",
996                                             object_error::parse_failed);
997     }
998     uint32_t ParamCount = readVaruint32(Ctx);
999     Sig.Params.reserve(ParamCount);
1000     while (ParamCount--) {
1001       uint32_t ParamType = readUint8(Ctx);
1002       Sig.Params.push_back(wasm::ValType(ParamType));
1003     }
1004     uint32_t ReturnCount = readVaruint32(Ctx);
1005     while (ReturnCount--) {
1006       uint32_t ReturnType = readUint8(Ctx);
1007       Sig.Returns.push_back(wasm::ValType(ReturnType));
1008     }
1009     Signatures.push_back(std::move(Sig));
1010   }
1011   if (Ctx.Ptr != Ctx.End)
1012     return make_error<GenericBinaryError>("Type section ended prematurely",
1013                                           object_error::parse_failed);
1014   return Error::success();
1015 }
1016 
1017 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
1018   uint32_t Count = readVaruint32(Ctx);
1019   Imports.reserve(Count);
1020   for (uint32_t I = 0; I < Count; I++) {
1021     wasm::WasmImport Im;
1022     Im.Module = readString(Ctx);
1023     Im.Field = readString(Ctx);
1024     Im.Kind = readUint8(Ctx);
1025     switch (Im.Kind) {
1026     case wasm::WASM_EXTERNAL_FUNCTION:
1027       NumImportedFunctions++;
1028       Im.SigIndex = readVaruint32(Ctx);
1029       break;
1030     case wasm::WASM_EXTERNAL_GLOBAL:
1031       NumImportedGlobals++;
1032       Im.Global.Type = readUint8(Ctx);
1033       Im.Global.Mutable = readVaruint1(Ctx);
1034       break;
1035     case wasm::WASM_EXTERNAL_MEMORY:
1036       Im.Memory = readLimits(Ctx);
1037       if (Im.Memory.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1038         HasMemory64 = true;
1039       break;
1040     case wasm::WASM_EXTERNAL_TABLE: {
1041       Im.Table = readTableType(Ctx);
1042       NumImportedTables++;
1043       auto ElemType = Im.Table.ElemType;
1044       if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1045           ElemType != wasm::WASM_TYPE_EXTERNREF)
1046         return make_error<GenericBinaryError>("Invalid table element type",
1047                                               object_error::parse_failed);
1048       break;
1049     }
1050     case wasm::WASM_EXTERNAL_EVENT:
1051       NumImportedEvents++;
1052       Im.Event.Attribute = readVarint32(Ctx);
1053       Im.Event.SigIndex = readVarint32(Ctx);
1054       break;
1055     default:
1056       return make_error<GenericBinaryError>("Unexpected import kind",
1057                                             object_error::parse_failed);
1058     }
1059     Imports.push_back(Im);
1060   }
1061   if (Ctx.Ptr != Ctx.End)
1062     return make_error<GenericBinaryError>("Import section ended prematurely",
1063                                           object_error::parse_failed);
1064   return Error::success();
1065 }
1066 
1067 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
1068   uint32_t Count = readVaruint32(Ctx);
1069   FunctionTypes.reserve(Count);
1070   Functions.resize(Count);
1071   uint32_t NumTypes = Signatures.size();
1072   while (Count--) {
1073     uint32_t Type = readVaruint32(Ctx);
1074     if (Type >= NumTypes)
1075       return make_error<GenericBinaryError>("Invalid function type",
1076                                             object_error::parse_failed);
1077     FunctionTypes.push_back(Type);
1078   }
1079   if (Ctx.Ptr != Ctx.End)
1080     return make_error<GenericBinaryError>("Function section ended prematurely",
1081                                           object_error::parse_failed);
1082   return Error::success();
1083 }
1084 
1085 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
1086   TableSection = Sections.size();
1087   uint32_t Count = readVaruint32(Ctx);
1088   Tables.reserve(Count);
1089   while (Count--) {
1090     wasm::WasmTable T;
1091     T.Type = readTableType(Ctx);
1092     T.Index = NumImportedTables + Tables.size();
1093     Tables.push_back(T);
1094     auto ElemType = Tables.back().Type.ElemType;
1095     if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1096         ElemType != wasm::WASM_TYPE_EXTERNREF) {
1097       return make_error<GenericBinaryError>("Invalid table element type",
1098                                             object_error::parse_failed);
1099     }
1100   }
1101   if (Ctx.Ptr != Ctx.End)
1102     return make_error<GenericBinaryError>("Table section ended prematurely",
1103                                           object_error::parse_failed);
1104   return Error::success();
1105 }
1106 
1107 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
1108   uint32_t Count = readVaruint32(Ctx);
1109   Memories.reserve(Count);
1110   while (Count--) {
1111     auto Limits = readLimits(Ctx);
1112     if (Limits.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1113       HasMemory64 = true;
1114     Memories.push_back(Limits);
1115   }
1116   if (Ctx.Ptr != Ctx.End)
1117     return make_error<GenericBinaryError>("Memory section ended prematurely",
1118                                           object_error::parse_failed);
1119   return Error::success();
1120 }
1121 
1122 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
1123   EventSection = Sections.size();
1124   uint32_t Count = readVarint32(Ctx);
1125   Events.reserve(Count);
1126   while (Count--) {
1127     wasm::WasmEvent Event;
1128     Event.Index = NumImportedEvents + Events.size();
1129     Event.Type.Attribute = readVaruint32(Ctx);
1130     Event.Type.SigIndex = readVarint32(Ctx);
1131     Events.push_back(Event);
1132   }
1133 
1134   if (Ctx.Ptr != Ctx.End)
1135     return make_error<GenericBinaryError>("Event section ended prematurely",
1136                                           object_error::parse_failed);
1137   return Error::success();
1138 }
1139 
1140 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
1141   GlobalSection = Sections.size();
1142   uint32_t Count = readVaruint32(Ctx);
1143   Globals.reserve(Count);
1144   while (Count--) {
1145     wasm::WasmGlobal Global;
1146     Global.Index = NumImportedGlobals + Globals.size();
1147     Global.Type.Type = readUint8(Ctx);
1148     Global.Type.Mutable = readVaruint1(Ctx);
1149     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
1150       return Err;
1151     Globals.push_back(Global);
1152   }
1153   if (Ctx.Ptr != Ctx.End)
1154     return make_error<GenericBinaryError>("Global section ended prematurely",
1155                                           object_error::parse_failed);
1156   return Error::success();
1157 }
1158 
1159 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
1160   uint32_t Count = readVaruint32(Ctx);
1161   Exports.reserve(Count);
1162   for (uint32_t I = 0; I < Count; I++) {
1163     wasm::WasmExport Ex;
1164     Ex.Name = readString(Ctx);
1165     Ex.Kind = readUint8(Ctx);
1166     Ex.Index = readVaruint32(Ctx);
1167     switch (Ex.Kind) {
1168     case wasm::WASM_EXTERNAL_FUNCTION:
1169 
1170       if (!isDefinedFunctionIndex(Ex.Index))
1171         return make_error<GenericBinaryError>("Invalid function export",
1172                                               object_error::parse_failed);
1173       getDefinedFunction(Ex.Index).ExportName = Ex.Name;
1174       break;
1175     case wasm::WASM_EXTERNAL_GLOBAL:
1176       if (!isValidGlobalIndex(Ex.Index))
1177         return make_error<GenericBinaryError>("Invalid global export",
1178                                               object_error::parse_failed);
1179       break;
1180     case wasm::WASM_EXTERNAL_EVENT:
1181       if (!isValidEventIndex(Ex.Index))
1182         return make_error<GenericBinaryError>("Invalid event export",
1183                                               object_error::parse_failed);
1184       break;
1185     case wasm::WASM_EXTERNAL_MEMORY:
1186     case wasm::WASM_EXTERNAL_TABLE:
1187       break;
1188     default:
1189       return make_error<GenericBinaryError>("Unexpected export kind",
1190                                             object_error::parse_failed);
1191     }
1192     Exports.push_back(Ex);
1193   }
1194   if (Ctx.Ptr != Ctx.End)
1195     return make_error<GenericBinaryError>("Export section ended prematurely",
1196                                           object_error::parse_failed);
1197   return Error::success();
1198 }
1199 
1200 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
1201   return Index < NumImportedFunctions + FunctionTypes.size();
1202 }
1203 
1204 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
1205   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
1206 }
1207 
1208 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
1209   return Index < NumImportedGlobals + Globals.size();
1210 }
1211 
1212 bool WasmObjectFile::isValidTableIndex(uint32_t Index) const {
1213   return Index < NumImportedTables + Tables.size();
1214 }
1215 
1216 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
1217   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
1218 }
1219 
1220 bool WasmObjectFile::isDefinedTableIndex(uint32_t Index) const {
1221   return Index >= NumImportedTables && isValidTableIndex(Index);
1222 }
1223 
1224 bool WasmObjectFile::isValidEventIndex(uint32_t Index) const {
1225   return Index < NumImportedEvents + Events.size();
1226 }
1227 
1228 bool WasmObjectFile::isDefinedEventIndex(uint32_t Index) const {
1229   return Index >= NumImportedEvents && isValidEventIndex(Index);
1230 }
1231 
1232 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1233   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1234 }
1235 
1236 bool WasmObjectFile::isValidTableSymbol(uint32_t Index) const {
1237   return Index < Symbols.size() && Symbols[Index].isTypeTable();
1238 }
1239 
1240 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1241   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1242 }
1243 
1244 bool WasmObjectFile::isValidEventSymbol(uint32_t Index) const {
1245   return Index < Symbols.size() && Symbols[Index].isTypeEvent();
1246 }
1247 
1248 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1249   return Index < Symbols.size() && Symbols[Index].isTypeData();
1250 }
1251 
1252 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1253   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1254 }
1255 
1256 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1257   assert(isDefinedFunctionIndex(Index));
1258   return Functions[Index - NumImportedFunctions];
1259 }
1260 
1261 const wasm::WasmFunction &
1262 WasmObjectFile::getDefinedFunction(uint32_t Index) const {
1263   assert(isDefinedFunctionIndex(Index));
1264   return Functions[Index - NumImportedFunctions];
1265 }
1266 
1267 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1268   assert(isDefinedGlobalIndex(Index));
1269   return Globals[Index - NumImportedGlobals];
1270 }
1271 
1272 wasm::WasmEvent &WasmObjectFile::getDefinedEvent(uint32_t Index) {
1273   assert(isDefinedEventIndex(Index));
1274   return Events[Index - NumImportedEvents];
1275 }
1276 
1277 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1278   StartFunction = readVaruint32(Ctx);
1279   if (!isValidFunctionIndex(StartFunction))
1280     return make_error<GenericBinaryError>("Invalid start function",
1281                                           object_error::parse_failed);
1282   return Error::success();
1283 }
1284 
1285 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1286   SeenCodeSection = true;
1287   CodeSection = Sections.size();
1288   uint32_t FunctionCount = readVaruint32(Ctx);
1289   if (FunctionCount != FunctionTypes.size()) {
1290     return make_error<GenericBinaryError>("Invalid function count",
1291                                           object_error::parse_failed);
1292   }
1293 
1294   for (uint32_t i = 0; i < FunctionCount; i++) {
1295     wasm::WasmFunction& Function = Functions[i];
1296     const uint8_t *FunctionStart = Ctx.Ptr;
1297     uint32_t Size = readVaruint32(Ctx);
1298     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1299 
1300     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1301     Function.Index = NumImportedFunctions + i;
1302     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1303     Function.Size = FunctionEnd - FunctionStart;
1304 
1305     uint32_t NumLocalDecls = readVaruint32(Ctx);
1306     Function.Locals.reserve(NumLocalDecls);
1307     while (NumLocalDecls--) {
1308       wasm::WasmLocalDecl Decl;
1309       Decl.Count = readVaruint32(Ctx);
1310       Decl.Type = readUint8(Ctx);
1311       Function.Locals.push_back(Decl);
1312     }
1313 
1314     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1315     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1316     // This will be set later when reading in the linking metadata section.
1317     Function.Comdat = UINT32_MAX;
1318     Ctx.Ptr += BodySize;
1319     assert(Ctx.Ptr == FunctionEnd);
1320   }
1321   if (Ctx.Ptr != Ctx.End)
1322     return make_error<GenericBinaryError>("Code section ended prematurely",
1323                                           object_error::parse_failed);
1324   return Error::success();
1325 }
1326 
1327 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1328   uint32_t Count = readVaruint32(Ctx);
1329   ElemSegments.reserve(Count);
1330   while (Count--) {
1331     wasm::WasmElemSegment Segment;
1332     Segment.TableIndex = readVaruint32(Ctx);
1333     if (Segment.TableIndex != 0) {
1334       return make_error<GenericBinaryError>("Invalid TableIndex",
1335                                             object_error::parse_failed);
1336     }
1337     if (Error Err = readInitExpr(Segment.Offset, Ctx))
1338       return Err;
1339     uint32_t NumElems = readVaruint32(Ctx);
1340     while (NumElems--) {
1341       Segment.Functions.push_back(readVaruint32(Ctx));
1342     }
1343     ElemSegments.push_back(Segment);
1344   }
1345   if (Ctx.Ptr != Ctx.End)
1346     return make_error<GenericBinaryError>("Elem section ended prematurely",
1347                                           object_error::parse_failed);
1348   return Error::success();
1349 }
1350 
1351 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1352   DataSection = Sections.size();
1353   uint32_t Count = readVaruint32(Ctx);
1354   if (DataCount && Count != DataCount.getValue())
1355     return make_error<GenericBinaryError>(
1356         "Number of data segments does not match DataCount section");
1357   DataSegments.reserve(Count);
1358   while (Count--) {
1359     WasmSegment Segment;
1360     Segment.Data.InitFlags = readVaruint32(Ctx);
1361     Segment.Data.MemoryIndex = (Segment.Data.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
1362                                ? readVaruint32(Ctx) : 0;
1363     if ((Segment.Data.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
1364       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1365         return Err;
1366     } else {
1367       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1368       Segment.Data.Offset.Value.Int32 = 0;
1369     }
1370     uint32_t Size = readVaruint32(Ctx);
1371     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1372       return make_error<GenericBinaryError>("Invalid segment size",
1373                                             object_error::parse_failed);
1374     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1375     // The rest of these Data fields are set later, when reading in the linking
1376     // metadata section.
1377     Segment.Data.Alignment = 0;
1378     Segment.Data.LinkerFlags = 0;
1379     Segment.Data.Comdat = UINT32_MAX;
1380     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1381     Ctx.Ptr += Size;
1382     DataSegments.push_back(Segment);
1383   }
1384   if (Ctx.Ptr != Ctx.End)
1385     return make_error<GenericBinaryError>("Data section ended prematurely",
1386                                           object_error::parse_failed);
1387   return Error::success();
1388 }
1389 
1390 Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
1391   DataCount = readVaruint32(Ctx);
1392   return Error::success();
1393 }
1394 
1395 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1396   return Header;
1397 }
1398 
1399 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.b++; }
1400 
1401 Expected<uint32_t> WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1402   uint32_t Result = SymbolRef::SF_None;
1403   const WasmSymbol &Sym = getWasmSymbol(Symb);
1404 
1405   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1406   if (Sym.isBindingWeak())
1407     Result |= SymbolRef::SF_Weak;
1408   if (!Sym.isBindingLocal())
1409     Result |= SymbolRef::SF_Global;
1410   if (Sym.isHidden())
1411     Result |= SymbolRef::SF_Hidden;
1412   if (!Sym.isDefined())
1413     Result |= SymbolRef::SF_Undefined;
1414   if (Sym.isTypeFunction())
1415     Result |= SymbolRef::SF_Executable;
1416   return Result;
1417 }
1418 
1419 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1420   DataRefImpl Ref;
1421   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1422   Ref.d.b = 0; // Symbol index
1423   return BasicSymbolRef(Ref, this);
1424 }
1425 
1426 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1427   DataRefImpl Ref;
1428   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1429   Ref.d.b = Symbols.size(); // Symbol index
1430   return BasicSymbolRef(Ref, this);
1431 }
1432 
1433 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1434   return Symbols[Symb.d.b];
1435 }
1436 
1437 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1438   return getWasmSymbol(Symb.getRawDataRefImpl());
1439 }
1440 
1441 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1442   return getWasmSymbol(Symb).Info.Name;
1443 }
1444 
1445 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1446   auto &Sym = getWasmSymbol(Symb);
1447   if (Sym.Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION &&
1448       isDefinedFunctionIndex(Sym.Info.ElementIndex))
1449     return getDefinedFunction(Sym.Info.ElementIndex).CodeSectionOffset;
1450   else
1451     return getSymbolValue(Symb);
1452 }
1453 
1454 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1455   switch (Sym.Info.Kind) {
1456   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1457   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1458   case wasm::WASM_SYMBOL_TYPE_EVENT:
1459   case wasm::WASM_SYMBOL_TYPE_TABLE:
1460     return Sym.Info.ElementIndex;
1461   case wasm::WASM_SYMBOL_TYPE_DATA: {
1462     // The value of a data symbol is the segment offset, plus the symbol
1463     // offset within the segment.
1464     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1465     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1466     if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST) {
1467       return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1468     } else if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I64_CONST) {
1469       return Segment.Offset.Value.Int64 + Sym.Info.DataRef.Offset;
1470     } else {
1471       llvm_unreachable("unknown init expr opcode");
1472     }
1473   }
1474   case wasm::WASM_SYMBOL_TYPE_SECTION:
1475     return 0;
1476   }
1477   llvm_unreachable("invalid symbol type");
1478 }
1479 
1480 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1481   return getWasmSymbolValue(getWasmSymbol(Symb));
1482 }
1483 
1484 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1485   llvm_unreachable("not yet implemented");
1486   return 0;
1487 }
1488 
1489 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1490   llvm_unreachable("not yet implemented");
1491   return 0;
1492 }
1493 
1494 Expected<SymbolRef::Type>
1495 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1496   const WasmSymbol &Sym = getWasmSymbol(Symb);
1497 
1498   switch (Sym.Info.Kind) {
1499   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1500     return SymbolRef::ST_Function;
1501   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1502     return SymbolRef::ST_Other;
1503   case wasm::WASM_SYMBOL_TYPE_DATA:
1504     return SymbolRef::ST_Data;
1505   case wasm::WASM_SYMBOL_TYPE_SECTION:
1506     return SymbolRef::ST_Debug;
1507   case wasm::WASM_SYMBOL_TYPE_EVENT:
1508     return SymbolRef::ST_Other;
1509   case wasm::WASM_SYMBOL_TYPE_TABLE:
1510     return SymbolRef::ST_Other;
1511   }
1512 
1513   llvm_unreachable("Unknown WasmSymbol::SymbolType");
1514   return SymbolRef::ST_Other;
1515 }
1516 
1517 Expected<section_iterator>
1518 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1519   const WasmSymbol &Sym = getWasmSymbol(Symb);
1520   if (Sym.isUndefined())
1521     return section_end();
1522 
1523   DataRefImpl Ref;
1524   Ref.d.a = getSymbolSectionIdImpl(Sym);
1525   return section_iterator(SectionRef(Ref, this));
1526 }
1527 
1528 uint32_t WasmObjectFile::getSymbolSectionId(SymbolRef Symb) const {
1529   const WasmSymbol &Sym = getWasmSymbol(Symb);
1530   return getSymbolSectionIdImpl(Sym);
1531 }
1532 
1533 uint32_t WasmObjectFile::getSymbolSectionIdImpl(const WasmSymbol &Sym) const {
1534   switch (Sym.Info.Kind) {
1535   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1536     return CodeSection;
1537   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1538     return GlobalSection;
1539   case wasm::WASM_SYMBOL_TYPE_DATA:
1540     return DataSection;
1541   case wasm::WASM_SYMBOL_TYPE_SECTION:
1542     return Sym.Info.ElementIndex;
1543   case wasm::WASM_SYMBOL_TYPE_EVENT:
1544     return EventSection;
1545   case wasm::WASM_SYMBOL_TYPE_TABLE:
1546     return TableSection;
1547   default:
1548     llvm_unreachable("Unknown WasmSymbol::SymbolType");
1549   }
1550 }
1551 
1552 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1553 
1554 Expected<StringRef> WasmObjectFile::getSectionName(DataRefImpl Sec) const {
1555   const WasmSection &S = Sections[Sec.d.a];
1556 #define ECase(X)                                                               \
1557   case wasm::WASM_SEC_##X:                                                     \
1558     return #X;
1559   switch (S.Type) {
1560     ECase(TYPE);
1561     ECase(IMPORT);
1562     ECase(FUNCTION);
1563     ECase(TABLE);
1564     ECase(MEMORY);
1565     ECase(GLOBAL);
1566     ECase(EVENT);
1567     ECase(EXPORT);
1568     ECase(START);
1569     ECase(ELEM);
1570     ECase(CODE);
1571     ECase(DATA);
1572     ECase(DATACOUNT);
1573   case wasm::WASM_SEC_CUSTOM:
1574     return S.Name;
1575   default:
1576     return createStringError(object_error::invalid_section_index, "");
1577   }
1578 #undef ECase
1579 }
1580 
1581 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1582 
1583 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1584   return Sec.d.a;
1585 }
1586 
1587 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1588   const WasmSection &S = Sections[Sec.d.a];
1589   return S.Content.size();
1590 }
1591 
1592 Expected<ArrayRef<uint8_t>>
1593 WasmObjectFile::getSectionContents(DataRefImpl Sec) const {
1594   const WasmSection &S = Sections[Sec.d.a];
1595   // This will never fail since wasm sections can never be empty (user-sections
1596   // must have a name and non-user sections each have a defined structure).
1597   return S.Content;
1598 }
1599 
1600 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1601   return 1;
1602 }
1603 
1604 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1605   return false;
1606 }
1607 
1608 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1609   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1610 }
1611 
1612 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1613   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1614 }
1615 
1616 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1617 
1618 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1619 
1620 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1621   DataRefImpl RelocRef;
1622   RelocRef.d.a = Ref.d.a;
1623   RelocRef.d.b = 0;
1624   return relocation_iterator(RelocationRef(RelocRef, this));
1625 }
1626 
1627 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1628   const WasmSection &Sec = getWasmSection(Ref);
1629   DataRefImpl RelocRef;
1630   RelocRef.d.a = Ref.d.a;
1631   RelocRef.d.b = Sec.Relocations.size();
1632   return relocation_iterator(RelocationRef(RelocRef, this));
1633 }
1634 
1635 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1636 
1637 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1638   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1639   return Rel.Offset;
1640 }
1641 
1642 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1643   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1644   if (Rel.Type == wasm::R_WASM_TYPE_INDEX_LEB)
1645     return symbol_end();
1646   DataRefImpl Sym;
1647   Sym.d.a = 1;
1648   Sym.d.b = Rel.Index;
1649   return symbol_iterator(SymbolRef(Sym, this));
1650 }
1651 
1652 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1653   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1654   return Rel.Type;
1655 }
1656 
1657 void WasmObjectFile::getRelocationTypeName(
1658     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1659   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1660   StringRef Res = "Unknown";
1661 
1662 #define WASM_RELOC(name, value)                                                \
1663   case wasm::name:                                                             \
1664     Res = #name;                                                               \
1665     break;
1666 
1667   switch (Rel.Type) {
1668 #include "llvm/BinaryFormat/WasmRelocs.def"
1669   }
1670 
1671 #undef WASM_RELOC
1672 
1673   Result.append(Res.begin(), Res.end());
1674 }
1675 
1676 section_iterator WasmObjectFile::section_begin() const {
1677   DataRefImpl Ref;
1678   Ref.d.a = 0;
1679   return section_iterator(SectionRef(Ref, this));
1680 }
1681 
1682 section_iterator WasmObjectFile::section_end() const {
1683   DataRefImpl Ref;
1684   Ref.d.a = Sections.size();
1685   return section_iterator(SectionRef(Ref, this));
1686 }
1687 
1688 uint8_t WasmObjectFile::getBytesInAddress() const {
1689   return HasMemory64 ? 8 : 4;
1690 }
1691 
1692 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1693 
1694 Triple::ArchType WasmObjectFile::getArch() const {
1695   return HasMemory64 ? Triple::wasm64 : Triple::wasm32;
1696 }
1697 
1698 SubtargetFeatures WasmObjectFile::getFeatures() const {
1699   return SubtargetFeatures();
1700 }
1701 
1702 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1703 
1704 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1705 
1706 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1707   assert(Ref.d.a < Sections.size());
1708   return Sections[Ref.d.a];
1709 }
1710 
1711 const WasmSection &
1712 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1713   return getWasmSection(Section.getRawDataRefImpl());
1714 }
1715 
1716 const wasm::WasmRelocation &
1717 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1718   return getWasmRelocation(Ref.getRawDataRefImpl());
1719 }
1720 
1721 const wasm::WasmRelocation &
1722 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1723   assert(Ref.d.a < Sections.size());
1724   const WasmSection &Sec = Sections[Ref.d.a];
1725   assert(Ref.d.b < Sec.Relocations.size());
1726   return Sec.Relocations[Ref.d.b];
1727 }
1728 
1729 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1730                                              StringRef CustomSectionName) {
1731   switch (ID) {
1732   case wasm::WASM_SEC_CUSTOM:
1733     return StringSwitch<unsigned>(CustomSectionName)
1734         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1735         .Case("linking", WASM_SEC_ORDER_LINKING)
1736         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1737         .Case("name", WASM_SEC_ORDER_NAME)
1738         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1739         .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
1740         .Default(WASM_SEC_ORDER_NONE);
1741   case wasm::WASM_SEC_TYPE:
1742     return WASM_SEC_ORDER_TYPE;
1743   case wasm::WASM_SEC_IMPORT:
1744     return WASM_SEC_ORDER_IMPORT;
1745   case wasm::WASM_SEC_FUNCTION:
1746     return WASM_SEC_ORDER_FUNCTION;
1747   case wasm::WASM_SEC_TABLE:
1748     return WASM_SEC_ORDER_TABLE;
1749   case wasm::WASM_SEC_MEMORY:
1750     return WASM_SEC_ORDER_MEMORY;
1751   case wasm::WASM_SEC_GLOBAL:
1752     return WASM_SEC_ORDER_GLOBAL;
1753   case wasm::WASM_SEC_EXPORT:
1754     return WASM_SEC_ORDER_EXPORT;
1755   case wasm::WASM_SEC_START:
1756     return WASM_SEC_ORDER_START;
1757   case wasm::WASM_SEC_ELEM:
1758     return WASM_SEC_ORDER_ELEM;
1759   case wasm::WASM_SEC_CODE:
1760     return WASM_SEC_ORDER_CODE;
1761   case wasm::WASM_SEC_DATA:
1762     return WASM_SEC_ORDER_DATA;
1763   case wasm::WASM_SEC_DATACOUNT:
1764     return WASM_SEC_ORDER_DATACOUNT;
1765   case wasm::WASM_SEC_EVENT:
1766     return WASM_SEC_ORDER_EVENT;
1767   default:
1768     return WASM_SEC_ORDER_NONE;
1769   }
1770 }
1771 
1772 // Represents the edges in a directed graph where any node B reachable from node
1773 // A is not allowed to appear before A in the section ordering, but may appear
1774 // afterward.
1775 int WasmSectionOrderChecker::DisallowedPredecessors
1776     [WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
1777         // WASM_SEC_ORDER_NONE
1778         {},
1779         // WASM_SEC_ORDER_TYPE
1780         {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT},
1781         // WASM_SEC_ORDER_IMPORT
1782         {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION},
1783         // WASM_SEC_ORDER_FUNCTION
1784         {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE},
1785         // WASM_SEC_ORDER_TABLE
1786         {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY},
1787         // WASM_SEC_ORDER_MEMORY
1788         {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_EVENT},
1789         // WASM_SEC_ORDER_EVENT
1790         {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_GLOBAL},
1791         // WASM_SEC_ORDER_GLOBAL
1792         {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EXPORT},
1793         // WASM_SEC_ORDER_EXPORT
1794         {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START},
1795         // WASM_SEC_ORDER_START
1796         {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM},
1797         // WASM_SEC_ORDER_ELEM
1798         {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT},
1799         // WASM_SEC_ORDER_DATACOUNT
1800         {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE},
1801         // WASM_SEC_ORDER_CODE
1802         {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA},
1803         // WASM_SEC_ORDER_DATA
1804         {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING},
1805 
1806         // Custom Sections
1807         // WASM_SEC_ORDER_DYLINK
1808         {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE},
1809         // WASM_SEC_ORDER_LINKING
1810         {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME},
1811         // WASM_SEC_ORDER_RELOC (can be repeated)
1812         {},
1813         // WASM_SEC_ORDER_NAME
1814         {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS},
1815         // WASM_SEC_ORDER_PRODUCERS
1816         {WASM_SEC_ORDER_PRODUCERS, WASM_SEC_ORDER_TARGET_FEATURES},
1817         // WASM_SEC_ORDER_TARGET_FEATURES
1818         {WASM_SEC_ORDER_TARGET_FEATURES}};
1819 
1820 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1821                                                   StringRef CustomSectionName) {
1822   int Order = getSectionOrder(ID, CustomSectionName);
1823   if (Order == WASM_SEC_ORDER_NONE)
1824     return true;
1825 
1826   // Disallowed predecessors we need to check for
1827   SmallVector<int, WASM_NUM_SEC_ORDERS> WorkList;
1828 
1829   // Keep track of completed checks to avoid repeating work
1830   bool Checked[WASM_NUM_SEC_ORDERS] = {};
1831 
1832   int Curr = Order;
1833   while (true) {
1834     // Add new disallowed predecessors to work list
1835     for (size_t I = 0;; ++I) {
1836       int Next = DisallowedPredecessors[Curr][I];
1837       if (Next == WASM_SEC_ORDER_NONE)
1838         break;
1839       if (Checked[Next])
1840         continue;
1841       WorkList.push_back(Next);
1842       Checked[Next] = true;
1843     }
1844 
1845     if (WorkList.empty())
1846       break;
1847 
1848     // Consider next disallowed predecessor
1849     Curr = WorkList.pop_back_val();
1850     if (Seen[Curr])
1851       return false;
1852   }
1853 
1854   // Have not seen any disallowed predecessors
1855   Seen[Order] = true;
1856   return true;
1857 }
1858