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/STLExtras.h"
12 #include "llvm/ADT/StringRef.h"
13 #include "llvm/ADT/Triple.h"
14 #include "llvm/BinaryFormat/Wasm.h"
15 #include "llvm/MC/SubtargetFeature.h"
16 #include "llvm/Object/Binary.h"
17 #include "llvm/Object/Error.h"
18 #include "llvm/Object/ObjectFile.h"
19 #include "llvm/Object/SymbolicFile.h"
20 #include "llvm/Object/Wasm.h"
21 #include "llvm/Support/Endian.h"
22 #include "llvm/Support/Error.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/LEB128.h"
25 #include <algorithm>
26 #include <cassert>
27 #include <cstdint>
28 #include <cstring>
29 #include <system_error>
30 
31 #define DEBUG_TYPE "wasm-object"
32 
33 using namespace llvm;
34 using namespace object;
35 
36 Expected<std::unique_ptr<WasmObjectFile>>
37 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
38   Error Err = Error::success();
39   auto ObjectFile = llvm::make_unique<WasmObjectFile>(Buffer, Err);
40   if (Err)
41     return std::move(Err);
42 
43   return std::move(ObjectFile);
44 }
45 
46 #define VARINT7_MAX ((1<<7)-1)
47 #define VARINT7_MIN (-(1<<7))
48 #define VARUINT7_MAX (1<<7)
49 #define VARUINT1_MAX (1)
50 
51 static uint8_t readUint8(const uint8_t *&Ptr) { return *Ptr++; }
52 
53 static uint32_t readUint32(const uint8_t *&Ptr) {
54   uint32_t Result = support::endian::read32le(Ptr);
55   Ptr += sizeof(Result);
56   return Result;
57 }
58 
59 static int32_t readFloat32(const uint8_t *&Ptr) {
60   int32_t Result = 0;
61   memcpy(&Result, Ptr, sizeof(Result));
62   Ptr += sizeof(Result);
63   return Result;
64 }
65 
66 static int64_t readFloat64(const uint8_t *&Ptr) {
67   int64_t Result = 0;
68   memcpy(&Result, Ptr, sizeof(Result));
69   Ptr += sizeof(Result);
70   return Result;
71 }
72 
73 static uint64_t readULEB128(const uint8_t *&Ptr) {
74   unsigned Count;
75   uint64_t Result = decodeULEB128(Ptr, &Count);
76   Ptr += Count;
77   return Result;
78 }
79 
80 static StringRef readString(const uint8_t *&Ptr) {
81   uint32_t StringLen = readULEB128(Ptr);
82   StringRef Return = StringRef(reinterpret_cast<const char *>(Ptr), StringLen);
83   Ptr += StringLen;
84   return Return;
85 }
86 
87 static int64_t readLEB128(const uint8_t *&Ptr) {
88   unsigned Count;
89   uint64_t Result = decodeSLEB128(Ptr, &Count);
90   Ptr += Count;
91   return Result;
92 }
93 
94 static uint8_t readVaruint1(const uint8_t *&Ptr) {
95   int64_t result = readLEB128(Ptr);
96   assert(result <= VARUINT1_MAX && result >= 0);
97   return result;
98 }
99 
100 static int8_t readVarint7(const uint8_t *&Ptr) {
101   int64_t result = readLEB128(Ptr);
102   assert(result <= VARINT7_MAX && result >= VARINT7_MIN);
103   return result;
104 }
105 
106 static uint8_t readVaruint7(const uint8_t *&Ptr) {
107   uint64_t result = readULEB128(Ptr);
108   assert(result <= VARUINT7_MAX);
109   return result;
110 }
111 
112 static int32_t readVarint32(const uint8_t *&Ptr) {
113   int64_t result = readLEB128(Ptr);
114   assert(result <= INT32_MAX && result >= INT32_MIN);
115   return result;
116 }
117 
118 static uint32_t readVaruint32(const uint8_t *&Ptr) {
119   uint64_t result = readULEB128(Ptr);
120   assert(result <= UINT32_MAX);
121   return result;
122 }
123 
124 static int64_t readVarint64(const uint8_t *&Ptr) {
125   return readLEB128(Ptr);
126 }
127 
128 static uint8_t readOpcode(const uint8_t *&Ptr) {
129   return readUint8(Ptr);
130 }
131 
132 static Error readInitExpr(wasm::WasmInitExpr &Expr, const uint8_t *&Ptr) {
133   Expr.Opcode = readOpcode(Ptr);
134 
135   switch (Expr.Opcode) {
136   case wasm::WASM_OPCODE_I32_CONST:
137     Expr.Value.Int32 = readVarint32(Ptr);
138     break;
139   case wasm::WASM_OPCODE_I64_CONST:
140     Expr.Value.Int64 = readVarint64(Ptr);
141     break;
142   case wasm::WASM_OPCODE_F32_CONST:
143     Expr.Value.Float32 = readFloat32(Ptr);
144     break;
145   case wasm::WASM_OPCODE_F64_CONST:
146     Expr.Value.Float64 = readFloat64(Ptr);
147     break;
148   case wasm::WASM_OPCODE_GET_GLOBAL:
149     Expr.Value.Global = readULEB128(Ptr);
150     break;
151   default:
152     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
153                                           object_error::parse_failed);
154   }
155 
156   uint8_t EndOpcode = readOpcode(Ptr);
157   if (EndOpcode != wasm::WASM_OPCODE_END) {
158     return make_error<GenericBinaryError>("Invalid init_expr",
159                                           object_error::parse_failed);
160   }
161   return Error::success();
162 }
163 
164 static wasm::WasmLimits readLimits(const uint8_t *&Ptr) {
165   wasm::WasmLimits Result;
166   Result.Flags = readVaruint1(Ptr);
167   Result.Initial = readVaruint32(Ptr);
168   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
169     Result.Maximum = readVaruint32(Ptr);
170   return Result;
171 }
172 
173 static wasm::WasmTable readTable(const uint8_t *&Ptr) {
174   wasm::WasmTable Table;
175   Table.ElemType = readVarint7(Ptr);
176   Table.Limits = readLimits(Ptr);
177   return Table;
178 }
179 
180 static Error readSection(WasmSection &Section, const uint8_t *&Ptr,
181                          const uint8_t *Start) {
182   // TODO(sbc): Avoid reading past EOF in the case of malformed files.
183   Section.Offset = Ptr - Start;
184   Section.Type = readVaruint7(Ptr);
185   uint32_t Size = readVaruint32(Ptr);
186   if (Size == 0)
187     return make_error<StringError>("Zero length section",
188                                    object_error::parse_failed);
189   Section.Content = ArrayRef<uint8_t>(Ptr, Size);
190   Ptr += Size;
191   return Error::success();
192 }
193 
194 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
195     : ObjectFile(Binary::ID_Wasm, Buffer) {
196   LinkingData.DataAlignment = 0;
197   LinkingData.DataSize = 0;
198 
199   ErrorAsOutParameter ErrAsOutParam(&Err);
200   Header.Magic = getData().substr(0, 4);
201   if (Header.Magic != StringRef("\0asm", 4)) {
202     Err = make_error<StringError>("Bad magic number",
203                                   object_error::parse_failed);
204     return;
205   }
206   const uint8_t *Ptr = getPtr(4);
207   Header.Version = readUint32(Ptr);
208   if (Header.Version != wasm::WasmVersion) {
209     Err = make_error<StringError>("Bad version number",
210                                   object_error::parse_failed);
211     return;
212   }
213 
214   const uint8_t *Eof = getPtr(getData().size());
215   WasmSection Sec;
216   while (Ptr < Eof) {
217     if ((Err = readSection(Sec, Ptr, getPtr(0))))
218       return;
219     if ((Err = parseSection(Sec)))
220       return;
221 
222     Sections.push_back(Sec);
223   }
224 }
225 
226 Error WasmObjectFile::parseSection(WasmSection &Sec) {
227   const uint8_t* Start = Sec.Content.data();
228   const uint8_t* End = Start + Sec.Content.size();
229   switch (Sec.Type) {
230   case wasm::WASM_SEC_CUSTOM:
231     return parseCustomSection(Sec, Start, End);
232   case wasm::WASM_SEC_TYPE:
233     return parseTypeSection(Start, End);
234   case wasm::WASM_SEC_IMPORT:
235     return parseImportSection(Start, End);
236   case wasm::WASM_SEC_FUNCTION:
237     return parseFunctionSection(Start, End);
238   case wasm::WASM_SEC_TABLE:
239     return parseTableSection(Start, End);
240   case wasm::WASM_SEC_MEMORY:
241     return parseMemorySection(Start, End);
242   case wasm::WASM_SEC_GLOBAL:
243     return parseGlobalSection(Start, End);
244   case wasm::WASM_SEC_EXPORT:
245     return parseExportSection(Start, End);
246   case wasm::WASM_SEC_START:
247     return parseStartSection(Start, End);
248   case wasm::WASM_SEC_ELEM:
249     return parseElemSection(Start, End);
250   case wasm::WASM_SEC_CODE:
251     return parseCodeSection(Start, End);
252   case wasm::WASM_SEC_DATA:
253     return parseDataSection(Start, End);
254   default:
255     return make_error<GenericBinaryError>("Bad section type",
256                                           object_error::parse_failed);
257   }
258 }
259 
260 Error WasmObjectFile::parseNameSection(const uint8_t *Ptr, const uint8_t *End) {
261   while (Ptr < End) {
262     uint8_t Type = readVarint7(Ptr);
263     uint32_t Size = readVaruint32(Ptr);
264     const uint8_t *SubSectionEnd = Ptr + Size;
265     switch (Type) {
266     case wasm::WASM_NAMES_FUNCTION: {
267       uint32_t Count = readVaruint32(Ptr);
268       while (Count--) {
269         uint32_t Index = readVaruint32(Ptr);
270         StringRef Name = readString(Ptr);
271         if (!Name.empty())
272           Symbols.emplace_back(Name,
273                                WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME,
274                                Sections.size(), Index);
275       }
276       break;
277     }
278     // Ignore local names for now
279     case wasm::WASM_NAMES_LOCAL:
280     default:
281       Ptr += Size;
282       break;
283     }
284     if (Ptr != SubSectionEnd)
285       return make_error<GenericBinaryError>("Name sub-section ended prematurely",
286                                             object_error::parse_failed);
287   }
288 
289   if (Ptr != End)
290     return make_error<GenericBinaryError>("Name section ended prematurely",
291                                           object_error::parse_failed);
292   return Error::success();
293 }
294 
295 Error WasmObjectFile::parseLinkingSection(const uint8_t *Ptr,
296                                           const uint8_t *End) {
297   HasLinkingSection = true;
298   while (Ptr < End) {
299     uint8_t Type = readVarint7(Ptr);
300     uint32_t Size = readVaruint32(Ptr);
301     const uint8_t *SubSectionEnd = Ptr + Size;
302     switch (Type) {
303     case wasm::WASM_SYMBOL_INFO: {
304       uint32_t Count = readVaruint32(Ptr);
305       while (Count--) {
306         StringRef Symbol = readString(Ptr);
307         DEBUG(dbgs() << "reading syminfo: " << Symbol << "\n");
308         uint32_t Flags = readVaruint32(Ptr);
309         auto iter = SymbolMap.find(Symbol);
310         if (iter == SymbolMap.end()) {
311           return make_error<GenericBinaryError>(
312               "Invalid symbol name in linking section: " + Symbol,
313               object_error::parse_failed);
314         }
315         uint32_t SymIndex = iter->second;
316         assert(SymIndex < Symbols.size());
317         Symbols[SymIndex].Flags = Flags;
318         DEBUG(dbgs() << "Set symbol flags index:"
319                      << SymIndex << " name:"
320                      << Symbols[SymIndex].Name << " exptected:"
321                      << Symbol << " flags: " << Flags << "\n");
322       }
323       break;
324     }
325     case wasm::WASM_DATA_SIZE:
326       LinkingData.DataSize = readVaruint32(Ptr);
327       break;
328     case wasm::WASM_DATA_ALIGNMENT:
329       LinkingData.DataAlignment = readVaruint32(Ptr);
330       break;
331     case wasm::WASM_STACK_POINTER:
332     default:
333       Ptr += Size;
334       break;
335     }
336     if (Ptr != SubSectionEnd)
337       return make_error<GenericBinaryError>(
338           "Linking sub-section ended prematurely", object_error::parse_failed);
339   }
340   if (Ptr != End)
341     return make_error<GenericBinaryError>("Linking section ended prematurely",
342                                           object_error::parse_failed);
343   return Error::success();
344 }
345 
346 WasmSection* WasmObjectFile::findCustomSectionByName(StringRef Name) {
347   for (WasmSection& Section : Sections) {
348     if (Section.Type == wasm::WASM_SEC_CUSTOM && Section.Name == Name)
349       return &Section;
350   }
351   return nullptr;
352 }
353 
354 WasmSection* WasmObjectFile::findSectionByType(uint32_t Type) {
355   assert(Type != wasm::WASM_SEC_CUSTOM);
356   for (WasmSection& Section : Sections) {
357     if (Section.Type == Type)
358       return &Section;
359   }
360   return nullptr;
361 }
362 
363 Error WasmObjectFile::parseRelocSection(StringRef Name, const uint8_t *Ptr,
364                                         const uint8_t *End) {
365   uint8_t SectionCode = readVarint7(Ptr);
366   WasmSection* Section = nullptr;
367   if (SectionCode == wasm::WASM_SEC_CUSTOM) {
368     StringRef Name = readString(Ptr);
369     Section = findCustomSectionByName(Name);
370   } else {
371     Section = findSectionByType(SectionCode);
372   }
373   if (!Section)
374     return make_error<GenericBinaryError>("Invalid section code",
375                                           object_error::parse_failed);
376   uint32_t RelocCount = readVaruint32(Ptr);
377   while (RelocCount--) {
378     wasm::WasmRelocation Reloc;
379     memset(&Reloc, 0, sizeof(Reloc));
380     Reloc.Type = readVaruint32(Ptr);
381     Reloc.Offset = readVaruint32(Ptr);
382     Reloc.Index = readVaruint32(Ptr);
383     switch (Reloc.Type) {
384     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
385     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
386     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
387     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
388     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
389       break;
390     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB:
391     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB:
392     case wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32:
393       Reloc.Addend = readVarint32(Ptr);
394       break;
395     default:
396       return make_error<GenericBinaryError>("Bad relocation type: " +
397                                                 Twine(Reloc.Type),
398                                             object_error::parse_failed);
399     }
400     Section->Relocations.push_back(Reloc);
401   }
402   if (Ptr != End)
403     return make_error<GenericBinaryError>("Reloc section ended prematurely",
404                                           object_error::parse_failed);
405   return Error::success();
406 }
407 
408 Error WasmObjectFile::parseCustomSection(WasmSection &Sec,
409                                          const uint8_t *Ptr, const uint8_t *End) {
410   Sec.Name = readString(Ptr);
411   if (Sec.Name == "name") {
412     if (Error Err = parseNameSection(Ptr, End))
413       return Err;
414   } else if (Sec.Name == "linking") {
415     if (Error Err = parseLinkingSection(Ptr, End))
416       return Err;
417   } else if (Sec.Name.startswith("reloc.")) {
418     if (Error Err = parseRelocSection(Sec.Name, Ptr, End))
419       return Err;
420   }
421   return Error::success();
422 }
423 
424 Error WasmObjectFile::parseTypeSection(const uint8_t *Ptr, const uint8_t *End) {
425   uint32_t Count = readVaruint32(Ptr);
426   Signatures.reserve(Count);
427   while (Count--) {
428     wasm::WasmSignature Sig;
429     Sig.ReturnType = wasm::WASM_TYPE_NORESULT;
430     int8_t Form = readVarint7(Ptr);
431     if (Form != wasm::WASM_TYPE_FUNC) {
432       return make_error<GenericBinaryError>("Invalid signature type",
433                                             object_error::parse_failed);
434     }
435     uint32_t ParamCount = readVaruint32(Ptr);
436     Sig.ParamTypes.reserve(ParamCount);
437     while (ParamCount--) {
438       uint32_t ParamType = readVarint7(Ptr);
439       Sig.ParamTypes.push_back(ParamType);
440     }
441     uint32_t ReturnCount = readVaruint32(Ptr);
442     if (ReturnCount) {
443       if (ReturnCount != 1) {
444         return make_error<GenericBinaryError>(
445             "Multiple return types not supported", object_error::parse_failed);
446       }
447       Sig.ReturnType = readVarint7(Ptr);
448     }
449     Signatures.push_back(Sig);
450   }
451   if (Ptr != End)
452     return make_error<GenericBinaryError>("Type section ended prematurely",
453                                           object_error::parse_failed);
454   return Error::success();
455 }
456 
457 Error WasmObjectFile::parseImportSection(const uint8_t *Ptr, const uint8_t *End) {
458   uint32_t Count = readVaruint32(Ptr);
459   Imports.reserve(Count);
460   for (uint32_t i = 0; i < Count; i++) {
461     wasm::WasmImport Im;
462     Im.Module = readString(Ptr);
463     Im.Field = readString(Ptr);
464     Im.Kind = readUint8(Ptr);
465     switch (Im.Kind) {
466     case wasm::WASM_EXTERNAL_FUNCTION:
467       Im.SigIndex = readVaruint32(Ptr);
468       SymbolMap.try_emplace(Im.Field, Symbols.size());
469       Symbols.emplace_back(Im.Field, WasmSymbol::SymbolType::FUNCTION_IMPORT,
470                            Sections.size(), i);
471       DEBUG(dbgs() << "Adding import: " << Symbols.back()
472                    << " sym index:" << Symbols.size() << "\n");
473       break;
474     case wasm::WASM_EXTERNAL_GLOBAL:
475       Im.Global.Type = readVarint7(Ptr);
476       Im.Global.Mutable = readVaruint1(Ptr);
477       SymbolMap.try_emplace(Im.Field, Symbols.size());
478       Symbols.emplace_back(Im.Field, WasmSymbol::SymbolType::GLOBAL_IMPORT,
479                            Sections.size(), i);
480       DEBUG(dbgs() << "Adding import: " << Symbols.back()
481                    << " sym index:" << Symbols.size() << "\n");
482       break;
483     case wasm::WASM_EXTERNAL_MEMORY:
484       Im.Memory = readLimits(Ptr);
485       break;
486     case wasm::WASM_EXTERNAL_TABLE:
487       Im.Table = readTable(Ptr);
488       if (Im.Table.ElemType != wasm::WASM_TYPE_ANYFUNC) {
489         return make_error<GenericBinaryError>("Invalid table element type",
490                                               object_error::parse_failed);
491       }
492       break;
493     default:
494       return make_error<GenericBinaryError>(
495           "Unexpected import kind", object_error::parse_failed);
496     }
497     Imports.push_back(Im);
498   }
499   if (Ptr != End)
500     return make_error<GenericBinaryError>("Import section ended prematurely",
501                                           object_error::parse_failed);
502   return Error::success();
503 }
504 
505 Error WasmObjectFile::parseFunctionSection(const uint8_t *Ptr, const uint8_t *End) {
506   uint32_t Count = readVaruint32(Ptr);
507   FunctionTypes.reserve(Count);
508   while (Count--) {
509     FunctionTypes.push_back(readVaruint32(Ptr));
510   }
511   if (Ptr != End)
512     return make_error<GenericBinaryError>("Function section ended prematurely",
513                                           object_error::parse_failed);
514   return Error::success();
515 }
516 
517 Error WasmObjectFile::parseTableSection(const uint8_t *Ptr, const uint8_t *End) {
518   uint32_t Count = readVaruint32(Ptr);
519   Tables.reserve(Count);
520   while (Count--) {
521     Tables.push_back(readTable(Ptr));
522     if (Tables.back().ElemType != wasm::WASM_TYPE_ANYFUNC) {
523       return make_error<GenericBinaryError>("Invalid table element type",
524                                             object_error::parse_failed);
525     }
526   }
527   if (Ptr != End)
528     return make_error<GenericBinaryError>("Table section ended prematurely",
529                                           object_error::parse_failed);
530   return Error::success();
531 }
532 
533 Error WasmObjectFile::parseMemorySection(const uint8_t *Ptr, const uint8_t *End) {
534   uint32_t Count = readVaruint32(Ptr);
535   Memories.reserve(Count);
536   while (Count--) {
537     Memories.push_back(readLimits(Ptr));
538   }
539   if (Ptr != End)
540     return make_error<GenericBinaryError>("Memory section ended prematurely",
541                                           object_error::parse_failed);
542   return Error::success();
543 }
544 
545 Error WasmObjectFile::parseGlobalSection(const uint8_t *Ptr, const uint8_t *End) {
546   uint32_t Count = readVaruint32(Ptr);
547   Globals.reserve(Count);
548   while (Count--) {
549     wasm::WasmGlobal Global;
550     Global.Type = readVarint7(Ptr);
551     Global.Mutable = readVaruint1(Ptr);
552     if (Error Err = readInitExpr(Global.InitExpr, Ptr))
553       return Err;
554     Globals.push_back(Global);
555   }
556   if (Ptr != End)
557     return make_error<GenericBinaryError>("Global section ended prematurely",
558                                           object_error::parse_failed);
559   return Error::success();
560 }
561 
562 Error WasmObjectFile::parseExportSection(const uint8_t *Ptr, const uint8_t *End) {
563   uint32_t Count = readVaruint32(Ptr);
564   Exports.reserve(Count);
565   for (uint32_t i = 0; i < Count; i++) {
566     wasm::WasmExport Ex;
567     Ex.Name = readString(Ptr);
568     Ex.Kind = readUint8(Ptr);
569     Ex.Index = readVaruint32(Ptr);
570     switch (Ex.Kind) {
571     case wasm::WASM_EXTERNAL_FUNCTION:
572       SymbolMap.try_emplace(Ex.Name, Symbols.size());
573       Symbols.emplace_back(Ex.Name, WasmSymbol::SymbolType::FUNCTION_EXPORT,
574                            Sections.size(), i);
575       DEBUG(dbgs() << "Adding export: " << Symbols.back()
576                    << " sym index:" << Symbols.size() << "\n");
577       break;
578     case wasm::WASM_EXTERNAL_GLOBAL:
579       SymbolMap.try_emplace(Ex.Name, Symbols.size());
580       Symbols.emplace_back(Ex.Name, WasmSymbol::SymbolType::GLOBAL_EXPORT,
581                            Sections.size(), i);
582       DEBUG(dbgs() << "Adding export: " << Symbols.back()
583                    << " sym index:" << Symbols.size() << "\n");
584       break;
585     case wasm::WASM_EXTERNAL_MEMORY:
586     case wasm::WASM_EXTERNAL_TABLE:
587       break;
588     default:
589       return make_error<GenericBinaryError>(
590           "Unexpected export kind", object_error::parse_failed);
591     }
592     Exports.push_back(Ex);
593   }
594   if (Ptr != End)
595     return make_error<GenericBinaryError>("Export section ended prematurely",
596                                           object_error::parse_failed);
597   return Error::success();
598 }
599 
600 Error WasmObjectFile::parseStartSection(const uint8_t *Ptr, const uint8_t *End) {
601   StartFunction = readVaruint32(Ptr);
602   if (StartFunction >= FunctionTypes.size())
603     return make_error<GenericBinaryError>("Invalid start function",
604                                           object_error::parse_failed);
605   return Error::success();
606 }
607 
608 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
609   uint32_t FunctionCount = readVaruint32(Ptr);
610   if (FunctionCount != FunctionTypes.size()) {
611     return make_error<GenericBinaryError>("Invalid function count",
612                                           object_error::parse_failed);
613   }
614 
615   CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
616 
617   while (FunctionCount--) {
618     wasm::WasmFunction Function;
619     uint32_t FunctionSize = readVaruint32(Ptr);
620     const uint8_t *FunctionEnd = Ptr + FunctionSize;
621 
622     uint32_t NumLocalDecls = readVaruint32(Ptr);
623     Function.Locals.reserve(NumLocalDecls);
624     while (NumLocalDecls--) {
625       wasm::WasmLocalDecl Decl;
626       Decl.Count = readVaruint32(Ptr);
627       Decl.Type = readVarint7(Ptr);
628       Function.Locals.push_back(Decl);
629     }
630 
631     uint32_t BodySize = FunctionEnd - Ptr;
632     Function.Body = ArrayRef<uint8_t>(Ptr, BodySize);
633     Ptr += BodySize;
634     assert(Ptr == FunctionEnd);
635     Functions.push_back(Function);
636   }
637   if (Ptr != End)
638     return make_error<GenericBinaryError>("Code section ended prematurely",
639                                           object_error::parse_failed);
640   return Error::success();
641 }
642 
643 Error WasmObjectFile::parseElemSection(const uint8_t *Ptr, const uint8_t *End) {
644   uint32_t Count = readVaruint32(Ptr);
645   ElemSegments.reserve(Count);
646   while (Count--) {
647     wasm::WasmElemSegment Segment;
648     Segment.TableIndex = readVaruint32(Ptr);
649     if (Segment.TableIndex != 0) {
650       return make_error<GenericBinaryError>("Invalid TableIndex",
651                                             object_error::parse_failed);
652     }
653     if (Error Err = readInitExpr(Segment.Offset, Ptr))
654       return Err;
655     uint32_t NumElems = readVaruint32(Ptr);
656     while (NumElems--) {
657       Segment.Functions.push_back(readVaruint32(Ptr));
658     }
659     ElemSegments.push_back(Segment);
660   }
661   if (Ptr != End)
662     return make_error<GenericBinaryError>("Elem section ended prematurely",
663                                           object_error::parse_failed);
664   return Error::success();
665 }
666 
667 Error WasmObjectFile::parseDataSection(const uint8_t *Ptr, const uint8_t *End) {
668   uint32_t Count = readVaruint32(Ptr);
669   DataSegments.reserve(Count);
670   while (Count--) {
671     wasm::WasmDataSegment Segment;
672     Segment.Index = readVaruint32(Ptr);
673     if (Error Err = readInitExpr(Segment.Offset, Ptr))
674       return Err;
675     uint32_t Size = readVaruint32(Ptr);
676     Segment.Content = ArrayRef<uint8_t>(Ptr, Size);
677     Ptr += Size;
678     DataSegments.push_back(Segment);
679   }
680   if (Ptr != End)
681     return make_error<GenericBinaryError>("Data section ended prematurely",
682                                           object_error::parse_failed);
683   return Error::success();
684 }
685 
686 const uint8_t *WasmObjectFile::getPtr(size_t Offset) const {
687   return reinterpret_cast<const uint8_t *>(getData().substr(Offset, 1).data());
688 }
689 
690 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
691   return Header;
692 }
693 
694 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.a++; }
695 
696 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
697   uint32_t Result = SymbolRef::SF_None;
698   const WasmSymbol &Sym = getWasmSymbol(Symb);
699 
700   DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
701   if (Sym.Flags & wasm::WASM_SYMBOL_FLAG_WEAK)
702     Result |= SymbolRef::SF_Weak;
703 
704   switch (Sym.Type) {
705   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
706     Result |= SymbolRef::SF_Undefined | SymbolRef::SF_Executable;
707     break;
708   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
709     Result |= SymbolRef::SF_Global | SymbolRef::SF_Executable;
710     break;
711   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
712     Result |= SymbolRef::SF_Executable;
713     Result |= SymbolRef::SF_FormatSpecific;
714     break;
715   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
716     Result |= SymbolRef::SF_Undefined;
717     break;
718   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
719     Result |= SymbolRef::SF_Global;
720     break;
721   }
722 
723   return Result;
724 }
725 
726 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
727   DataRefImpl Ref;
728   Ref.d.a = 0;
729   return BasicSymbolRef(Ref, this);
730 }
731 
732 basic_symbol_iterator WasmObjectFile::symbol_end() const {
733   DataRefImpl Ref;
734   Ref.d.a = Symbols.size();
735   return BasicSymbolRef(Ref, this);
736 }
737 
738 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
739   return Symbols[Symb.d.a];
740 }
741 
742 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
743   return getWasmSymbol(Symb.getRawDataRefImpl());
744 }
745 
746 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
747   return getWasmSymbol(Symb).Name;
748 }
749 
750 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
751   return getSymbolValue(Symb);
752 }
753 
754 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
755   const WasmSymbol& Sym = getWasmSymbol(Symb);
756   switch (Sym.Type) {
757   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
758   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
759     return 0;
760   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
761   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
762     return Exports[Sym.ElementIndex].Index;
763   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
764     return Sym.ElementIndex;
765   }
766   llvm_unreachable("invalid symbol type");
767 }
768 
769 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
770   llvm_unreachable("not yet implemented");
771   return 0;
772 }
773 
774 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
775   llvm_unreachable("not yet implemented");
776   return 0;
777 }
778 
779 Expected<SymbolRef::Type>
780 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
781   const WasmSymbol &Sym = getWasmSymbol(Symb);
782 
783   switch (Sym.Type) {
784   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
785   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
786   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
787     return SymbolRef::ST_Function;
788   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
789   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
790     return SymbolRef::ST_Data;
791   }
792 
793   llvm_unreachable("Unknown WasmSymbol::SymbolType");
794   return SymbolRef::ST_Other;
795 }
796 
797 Expected<section_iterator>
798 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
799   DataRefImpl Ref;
800   Ref.d.a = getWasmSymbol(Symb).Section;
801   return section_iterator(SectionRef(Ref, this));
802 }
803 
804 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
805 
806 std::error_code WasmObjectFile::getSectionName(DataRefImpl Sec,
807                                                StringRef &Res) const {
808   const WasmSection &S = Sections[Sec.d.a];
809 #define ECase(X)                                                               \
810   case wasm::WASM_SEC_##X:                                                     \
811     Res = #X;                                                                  \
812     break
813   switch (S.Type) {
814     ECase(TYPE);
815     ECase(IMPORT);
816     ECase(FUNCTION);
817     ECase(TABLE);
818     ECase(MEMORY);
819     ECase(GLOBAL);
820     ECase(EXPORT);
821     ECase(START);
822     ECase(ELEM);
823     ECase(CODE);
824     ECase(DATA);
825   case wasm::WASM_SEC_CUSTOM:
826     Res = S.Name;
827     break;
828   default:
829     return object_error::invalid_section_index;
830   }
831 #undef ECase
832   return std::error_code();
833 }
834 
835 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
836 
837 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
838   return Sec.d.a;
839 }
840 
841 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
842   const WasmSection &S = Sections[Sec.d.a];
843   return S.Content.size();
844 }
845 
846 std::error_code WasmObjectFile::getSectionContents(DataRefImpl Sec,
847                                                    StringRef &Res) const {
848   const WasmSection &S = Sections[Sec.d.a];
849   // This will never fail since wasm sections can never be empty (user-sections
850   // must have a name and non-user sections each have a defined structure).
851   Res = StringRef(reinterpret_cast<const char *>(S.Content.data()),
852                   S.Content.size());
853   return std::error_code();
854 }
855 
856 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
857   return 1;
858 }
859 
860 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
861   return false;
862 }
863 
864 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
865   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
866 }
867 
868 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
869   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
870 }
871 
872 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
873 
874 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
875 
876 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
877 
878 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
879   DataRefImpl RelocRef;
880   RelocRef.d.a = Ref.d.a;
881   RelocRef.d.b = 0;
882   return relocation_iterator(RelocationRef(RelocRef, this));
883 }
884 
885 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
886   const WasmSection &Sec = getWasmSection(Ref);
887   DataRefImpl RelocRef;
888   RelocRef.d.a = Ref.d.a;
889   RelocRef.d.b = Sec.Relocations.size();
890   return relocation_iterator(RelocationRef(RelocRef, this));
891 }
892 
893 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const {
894   Rel.d.b++;
895 }
896 
897 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
898   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
899   return Rel.Offset;
900 }
901 
902 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
903   llvm_unreachable("not yet implemented");
904   SymbolRef Ref;
905   return symbol_iterator(Ref);
906 }
907 
908 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
909   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
910   return Rel.Type;
911 }
912 
913 void WasmObjectFile::getRelocationTypeName(
914     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
915   const wasm::WasmRelocation& Rel = getWasmRelocation(Ref);
916   StringRef Res = "Unknown";
917 
918 #define WASM_RELOC(name, value)  \
919   case wasm::name:              \
920     Res = #name;               \
921     break;
922 
923   switch (Rel.Type) {
924 #include "llvm/BinaryFormat/WasmRelocs/WebAssembly.def"
925   }
926 
927 #undef WASM_RELOC
928 
929   Result.append(Res.begin(), Res.end());
930 }
931 
932 section_iterator WasmObjectFile::section_begin() const {
933   DataRefImpl Ref;
934   Ref.d.a = 0;
935   return section_iterator(SectionRef(Ref, this));
936 }
937 
938 section_iterator WasmObjectFile::section_end() const {
939   DataRefImpl Ref;
940   Ref.d.a = Sections.size();
941   return section_iterator(SectionRef(Ref, this));
942 }
943 
944 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
945 
946 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
947 
948 unsigned WasmObjectFile::getArch() const { return Triple::wasm32; }
949 
950 SubtargetFeatures WasmObjectFile::getFeatures() const {
951   return SubtargetFeatures();
952 }
953 
954 bool WasmObjectFile::isRelocatableObject() const {
955   return HasLinkingSection;
956 }
957 
958 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
959   assert(Ref.d.a < Sections.size());
960   return Sections[Ref.d.a];
961 }
962 
963 const WasmSection &
964 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
965   return getWasmSection(Section.getRawDataRefImpl());
966 }
967 
968 const wasm::WasmRelocation &
969 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
970   return getWasmRelocation(Ref.getRawDataRefImpl());
971 }
972 
973 const wasm::WasmRelocation &
974 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
975   assert(Ref.d.a < Sections.size());
976   const WasmSection& Sec = Sections[Ref.d.a];
977   assert(Ref.d.b < Sec.Relocations.size());
978   return Sec.Relocations[Ref.d.b];
979 }
980