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 
207   const uint8_t *Eof = getPtr(getData().size());
208   const uint8_t *Ptr = getPtr(4);
209 
210   if (Ptr + 4 > Eof) {
211     Err = make_error<StringError>("Missing version number",
212                                   object_error::parse_failed);
213     return;
214   }
215 
216   Header.Version = readUint32(Ptr);
217   if (Header.Version != wasm::WasmVersion) {
218     Err = make_error<StringError>("Bad version number",
219                                   object_error::parse_failed);
220     return;
221   }
222 
223   WasmSection Sec;
224   while (Ptr < Eof) {
225     if ((Err = readSection(Sec, Ptr, getPtr(0))))
226       return;
227     if ((Err = parseSection(Sec)))
228       return;
229 
230     Sections.push_back(Sec);
231   }
232 }
233 
234 Error WasmObjectFile::parseSection(WasmSection &Sec) {
235   const uint8_t* Start = Sec.Content.data();
236   const uint8_t* End = Start + Sec.Content.size();
237   switch (Sec.Type) {
238   case wasm::WASM_SEC_CUSTOM:
239     return parseCustomSection(Sec, Start, End);
240   case wasm::WASM_SEC_TYPE:
241     return parseTypeSection(Start, End);
242   case wasm::WASM_SEC_IMPORT:
243     return parseImportSection(Start, End);
244   case wasm::WASM_SEC_FUNCTION:
245     return parseFunctionSection(Start, End);
246   case wasm::WASM_SEC_TABLE:
247     return parseTableSection(Start, End);
248   case wasm::WASM_SEC_MEMORY:
249     return parseMemorySection(Start, End);
250   case wasm::WASM_SEC_GLOBAL:
251     return parseGlobalSection(Start, End);
252   case wasm::WASM_SEC_EXPORT:
253     return parseExportSection(Start, End);
254   case wasm::WASM_SEC_START:
255     return parseStartSection(Start, End);
256   case wasm::WASM_SEC_ELEM:
257     return parseElemSection(Start, End);
258   case wasm::WASM_SEC_CODE:
259     return parseCodeSection(Start, End);
260   case wasm::WASM_SEC_DATA:
261     return parseDataSection(Start, End);
262   default:
263     return make_error<GenericBinaryError>("Bad section type",
264                                           object_error::parse_failed);
265   }
266 }
267 
268 Error WasmObjectFile::parseNameSection(const uint8_t *Ptr, const uint8_t *End) {
269   while (Ptr < End) {
270     uint8_t Type = readVarint7(Ptr);
271     uint32_t Size = readVaruint32(Ptr);
272     const uint8_t *SubSectionEnd = Ptr + Size;
273     switch (Type) {
274     case wasm::WASM_NAMES_FUNCTION: {
275       uint32_t Count = readVaruint32(Ptr);
276       while (Count--) {
277         uint32_t Index = readVaruint32(Ptr);
278         StringRef Name = readString(Ptr);
279         if (!Name.empty())
280           Symbols.emplace_back(Name,
281                                WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME,
282                                Sections.size(), Index);
283       }
284       break;
285     }
286     // Ignore local names for now
287     case wasm::WASM_NAMES_LOCAL:
288     default:
289       Ptr += Size;
290       break;
291     }
292     if (Ptr != SubSectionEnd)
293       return make_error<GenericBinaryError>("Name sub-section ended prematurely",
294                                             object_error::parse_failed);
295   }
296 
297   if (Ptr != End)
298     return make_error<GenericBinaryError>("Name section ended prematurely",
299                                           object_error::parse_failed);
300   return Error::success();
301 }
302 
303 Error WasmObjectFile::parseLinkingSection(const uint8_t *Ptr,
304                                           const uint8_t *End) {
305   HasLinkingSection = true;
306   while (Ptr < End) {
307     uint8_t Type = readVarint7(Ptr);
308     uint32_t Size = readVaruint32(Ptr);
309     const uint8_t *SubSectionEnd = Ptr + Size;
310     switch (Type) {
311     case wasm::WASM_SYMBOL_INFO: {
312       uint32_t Count = readVaruint32(Ptr);
313       while (Count--) {
314         StringRef Symbol = readString(Ptr);
315         DEBUG(dbgs() << "reading syminfo: " << Symbol << "\n");
316         uint32_t Flags = readVaruint32(Ptr);
317         auto iter = SymbolMap.find(Symbol);
318         if (iter == SymbolMap.end()) {
319           return make_error<GenericBinaryError>(
320               "Invalid symbol name in linking section: " + Symbol,
321               object_error::parse_failed);
322         }
323         uint32_t SymIndex = iter->second;
324         assert(SymIndex < Symbols.size());
325         Symbols[SymIndex].Flags = Flags;
326         DEBUG(dbgs() << "Set symbol flags index:"
327                      << SymIndex << " name:"
328                      << Symbols[SymIndex].Name << " exptected:"
329                      << Symbol << " flags: " << Flags << "\n");
330       }
331       break;
332     }
333     case wasm::WASM_DATA_SIZE:
334       LinkingData.DataSize = readVaruint32(Ptr);
335       break;
336     case wasm::WASM_DATA_ALIGNMENT:
337       LinkingData.DataAlignment = readVaruint32(Ptr);
338       break;
339     case wasm::WASM_STACK_POINTER:
340     default:
341       Ptr += Size;
342       break;
343     }
344     if (Ptr != SubSectionEnd)
345       return make_error<GenericBinaryError>(
346           "Linking sub-section ended prematurely", object_error::parse_failed);
347   }
348   if (Ptr != End)
349     return make_error<GenericBinaryError>("Linking section ended prematurely",
350                                           object_error::parse_failed);
351   return Error::success();
352 }
353 
354 WasmSection* WasmObjectFile::findCustomSectionByName(StringRef Name) {
355   for (WasmSection& Section : Sections) {
356     if (Section.Type == wasm::WASM_SEC_CUSTOM && Section.Name == Name)
357       return &Section;
358   }
359   return nullptr;
360 }
361 
362 WasmSection* WasmObjectFile::findSectionByType(uint32_t Type) {
363   assert(Type != wasm::WASM_SEC_CUSTOM);
364   for (WasmSection& Section : Sections) {
365     if (Section.Type == Type)
366       return &Section;
367   }
368   return nullptr;
369 }
370 
371 Error WasmObjectFile::parseRelocSection(StringRef Name, const uint8_t *Ptr,
372                                         const uint8_t *End) {
373   uint8_t SectionCode = readVarint7(Ptr);
374   WasmSection* Section = nullptr;
375   if (SectionCode == wasm::WASM_SEC_CUSTOM) {
376     StringRef Name = readString(Ptr);
377     Section = findCustomSectionByName(Name);
378   } else {
379     Section = findSectionByType(SectionCode);
380   }
381   if (!Section)
382     return make_error<GenericBinaryError>("Invalid section code",
383                                           object_error::parse_failed);
384   uint32_t RelocCount = readVaruint32(Ptr);
385   while (RelocCount--) {
386     wasm::WasmRelocation Reloc;
387     memset(&Reloc, 0, sizeof(Reloc));
388     Reloc.Type = readVaruint32(Ptr);
389     Reloc.Offset = readVaruint32(Ptr);
390     Reloc.Index = readVaruint32(Ptr);
391     switch (Reloc.Type) {
392     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
393     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
394     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
395     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
396     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
397       break;
398     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
399     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
400     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
401       Reloc.Addend = readVarint32(Ptr);
402       break;
403     default:
404       return make_error<GenericBinaryError>("Bad relocation type: " +
405                                                 Twine(Reloc.Type),
406                                             object_error::parse_failed);
407     }
408     Section->Relocations.push_back(Reloc);
409   }
410   if (Ptr != End)
411     return make_error<GenericBinaryError>("Reloc section ended prematurely",
412                                           object_error::parse_failed);
413   return Error::success();
414 }
415 
416 Error WasmObjectFile::parseCustomSection(WasmSection &Sec,
417                                          const uint8_t *Ptr, const uint8_t *End) {
418   Sec.Name = readString(Ptr);
419   if (Sec.Name == "name") {
420     if (Error Err = parseNameSection(Ptr, End))
421       return Err;
422   } else if (Sec.Name == "linking") {
423     if (Error Err = parseLinkingSection(Ptr, End))
424       return Err;
425   } else if (Sec.Name.startswith("reloc.")) {
426     if (Error Err = parseRelocSection(Sec.Name, Ptr, End))
427       return Err;
428   }
429   return Error::success();
430 }
431 
432 Error WasmObjectFile::parseTypeSection(const uint8_t *Ptr, const uint8_t *End) {
433   uint32_t Count = readVaruint32(Ptr);
434   Signatures.reserve(Count);
435   while (Count--) {
436     wasm::WasmSignature Sig;
437     Sig.ReturnType = wasm::WASM_TYPE_NORESULT;
438     int8_t Form = readVarint7(Ptr);
439     if (Form != wasm::WASM_TYPE_FUNC) {
440       return make_error<GenericBinaryError>("Invalid signature type",
441                                             object_error::parse_failed);
442     }
443     uint32_t ParamCount = readVaruint32(Ptr);
444     Sig.ParamTypes.reserve(ParamCount);
445     while (ParamCount--) {
446       uint32_t ParamType = readVarint7(Ptr);
447       Sig.ParamTypes.push_back(ParamType);
448     }
449     uint32_t ReturnCount = readVaruint32(Ptr);
450     if (ReturnCount) {
451       if (ReturnCount != 1) {
452         return make_error<GenericBinaryError>(
453             "Multiple return types not supported", object_error::parse_failed);
454       }
455       Sig.ReturnType = readVarint7(Ptr);
456     }
457     Signatures.push_back(Sig);
458   }
459   if (Ptr != End)
460     return make_error<GenericBinaryError>("Type section ended prematurely",
461                                           object_error::parse_failed);
462   return Error::success();
463 }
464 
465 Error WasmObjectFile::parseImportSection(const uint8_t *Ptr, const uint8_t *End) {
466   uint32_t Count = readVaruint32(Ptr);
467   Imports.reserve(Count);
468   for (uint32_t i = 0; i < Count; i++) {
469     wasm::WasmImport Im;
470     Im.Module = readString(Ptr);
471     Im.Field = readString(Ptr);
472     Im.Kind = readUint8(Ptr);
473     switch (Im.Kind) {
474     case wasm::WASM_EXTERNAL_FUNCTION:
475       NumImportedFunctions++;
476       Im.SigIndex = readVaruint32(Ptr);
477       SymbolMap.try_emplace(Im.Field, Symbols.size());
478       Symbols.emplace_back(Im.Field, WasmSymbol::SymbolType::FUNCTION_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_GLOBAL:
484       NumImportedGlobals++;
485       Im.Global.Type = readVarint7(Ptr);
486       Im.Global.Mutable = readVaruint1(Ptr);
487       SymbolMap.try_emplace(Im.Field, Symbols.size());
488       Symbols.emplace_back(Im.Field, WasmSymbol::SymbolType::GLOBAL_IMPORT,
489                            Sections.size(), i);
490       DEBUG(dbgs() << "Adding import: " << Symbols.back()
491                    << " sym index:" << Symbols.size() << "\n");
492       break;
493     case wasm::WASM_EXTERNAL_MEMORY:
494       Im.Memory = readLimits(Ptr);
495       break;
496     case wasm::WASM_EXTERNAL_TABLE:
497       Im.Table = readTable(Ptr);
498       if (Im.Table.ElemType != wasm::WASM_TYPE_ANYFUNC) {
499         return make_error<GenericBinaryError>("Invalid table element type",
500                                               object_error::parse_failed);
501       }
502       break;
503     default:
504       return make_error<GenericBinaryError>(
505           "Unexpected import kind", object_error::parse_failed);
506     }
507     Imports.push_back(Im);
508   }
509   if (Ptr != End)
510     return make_error<GenericBinaryError>("Import section ended prematurely",
511                                           object_error::parse_failed);
512   return Error::success();
513 }
514 
515 Error WasmObjectFile::parseFunctionSection(const uint8_t *Ptr, const uint8_t *End) {
516   uint32_t Count = readVaruint32(Ptr);
517   FunctionTypes.reserve(Count);
518   while (Count--) {
519     FunctionTypes.push_back(readVaruint32(Ptr));
520   }
521   if (Ptr != End)
522     return make_error<GenericBinaryError>("Function section ended prematurely",
523                                           object_error::parse_failed);
524   return Error::success();
525 }
526 
527 Error WasmObjectFile::parseTableSection(const uint8_t *Ptr, const uint8_t *End) {
528   uint32_t Count = readVaruint32(Ptr);
529   Tables.reserve(Count);
530   while (Count--) {
531     Tables.push_back(readTable(Ptr));
532     if (Tables.back().ElemType != wasm::WASM_TYPE_ANYFUNC) {
533       return make_error<GenericBinaryError>("Invalid table element type",
534                                             object_error::parse_failed);
535     }
536   }
537   if (Ptr != End)
538     return make_error<GenericBinaryError>("Table section ended prematurely",
539                                           object_error::parse_failed);
540   return Error::success();
541 }
542 
543 Error WasmObjectFile::parseMemorySection(const uint8_t *Ptr, const uint8_t *End) {
544   uint32_t Count = readVaruint32(Ptr);
545   Memories.reserve(Count);
546   while (Count--) {
547     Memories.push_back(readLimits(Ptr));
548   }
549   if (Ptr != End)
550     return make_error<GenericBinaryError>("Memory section ended prematurely",
551                                           object_error::parse_failed);
552   return Error::success();
553 }
554 
555 Error WasmObjectFile::parseGlobalSection(const uint8_t *Ptr, const uint8_t *End) {
556   uint32_t Count = readVaruint32(Ptr);
557   Globals.reserve(Count);
558   while (Count--) {
559     wasm::WasmGlobal Global;
560     Global.Type = readVarint7(Ptr);
561     Global.Mutable = readVaruint1(Ptr);
562     if (Error Err = readInitExpr(Global.InitExpr, Ptr))
563       return Err;
564     Globals.push_back(Global);
565   }
566   if (Ptr != End)
567     return make_error<GenericBinaryError>("Global section ended prematurely",
568                                           object_error::parse_failed);
569   return Error::success();
570 }
571 
572 Error WasmObjectFile::parseExportSection(const uint8_t *Ptr, const uint8_t *End) {
573   uint32_t Count = readVaruint32(Ptr);
574   Exports.reserve(Count);
575   for (uint32_t i = 0; i < Count; i++) {
576     wasm::WasmExport Ex;
577     Ex.Name = readString(Ptr);
578     Ex.Kind = readUint8(Ptr);
579     Ex.Index = readVaruint32(Ptr);
580     WasmSymbol::SymbolType ExportType;
581     bool MakeSymbol = false;
582     switch (Ex.Kind) {
583     case wasm::WASM_EXTERNAL_FUNCTION:
584       ExportType = WasmSymbol::SymbolType::FUNCTION_EXPORT;
585       if (Ex.Index >= FunctionTypes.size() + NumImportedFunctions)
586         return make_error<GenericBinaryError>("Invalid function export",
587                                               object_error::parse_failed);
588       MakeSymbol = true;
589       break;
590     case wasm::WASM_EXTERNAL_GLOBAL:
591       ExportType = WasmSymbol::SymbolType::GLOBAL_EXPORT;
592       if (Ex.Index >= Globals.size() + NumImportedGlobals)
593         return make_error<GenericBinaryError>("Invalid global export",
594                                               object_error::parse_failed);
595       MakeSymbol = true;
596       break;
597     case wasm::WASM_EXTERNAL_MEMORY:
598     case wasm::WASM_EXTERNAL_TABLE:
599       break;
600     default:
601       return make_error<GenericBinaryError>(
602           "Unexpected export kind", object_error::parse_failed);
603     }
604     if (MakeSymbol) {
605       auto Pair = SymbolMap.try_emplace(Ex.Name, Symbols.size());
606       if (Pair.second) {
607         Symbols.emplace_back(Ex.Name, ExportType,
608                              Sections.size(), i);
609         DEBUG(dbgs() << "Adding export: " << Symbols.back()
610                      << " sym index:" << Symbols.size() << "\n");
611       } else {
612         uint32_t SymIndex = Pair.first->second;
613         Symbols[SymIndex] = WasmSymbol(Ex.Name, ExportType, Sections.size(), i);
614         DEBUG(dbgs() << "Replacing existing symbol:  " << Symbols[SymIndex]
615                      << " sym index:" << SymIndex << "\n");
616       }
617     }
618     Exports.push_back(Ex);
619   }
620   if (Ptr != End)
621     return make_error<GenericBinaryError>("Export section ended prematurely",
622                                           object_error::parse_failed);
623   return Error::success();
624 }
625 
626 Error WasmObjectFile::parseStartSection(const uint8_t *Ptr, const uint8_t *End) {
627   StartFunction = readVaruint32(Ptr);
628   if (StartFunction >= FunctionTypes.size())
629     return make_error<GenericBinaryError>("Invalid start function",
630                                           object_error::parse_failed);
631   return Error::success();
632 }
633 
634 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
635   uint32_t FunctionCount = readVaruint32(Ptr);
636   if (FunctionCount != FunctionTypes.size()) {
637     return make_error<GenericBinaryError>("Invalid function count",
638                                           object_error::parse_failed);
639   }
640 
641   CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
642 
643   while (FunctionCount--) {
644     wasm::WasmFunction Function;
645     uint32_t FunctionSize = readVaruint32(Ptr);
646     const uint8_t *FunctionEnd = Ptr + FunctionSize;
647 
648     uint32_t NumLocalDecls = readVaruint32(Ptr);
649     Function.Locals.reserve(NumLocalDecls);
650     while (NumLocalDecls--) {
651       wasm::WasmLocalDecl Decl;
652       Decl.Count = readVaruint32(Ptr);
653       Decl.Type = readVarint7(Ptr);
654       Function.Locals.push_back(Decl);
655     }
656 
657     uint32_t BodySize = FunctionEnd - Ptr;
658     Function.Body = ArrayRef<uint8_t>(Ptr, BodySize);
659     Ptr += BodySize;
660     assert(Ptr == FunctionEnd);
661     Functions.push_back(Function);
662   }
663   if (Ptr != End)
664     return make_error<GenericBinaryError>("Code section ended prematurely",
665                                           object_error::parse_failed);
666   return Error::success();
667 }
668 
669 Error WasmObjectFile::parseElemSection(const uint8_t *Ptr, const uint8_t *End) {
670   uint32_t Count = readVaruint32(Ptr);
671   ElemSegments.reserve(Count);
672   while (Count--) {
673     wasm::WasmElemSegment Segment;
674     Segment.TableIndex = readVaruint32(Ptr);
675     if (Segment.TableIndex != 0) {
676       return make_error<GenericBinaryError>("Invalid TableIndex",
677                                             object_error::parse_failed);
678     }
679     if (Error Err = readInitExpr(Segment.Offset, Ptr))
680       return Err;
681     uint32_t NumElems = readVaruint32(Ptr);
682     while (NumElems--) {
683       Segment.Functions.push_back(readVaruint32(Ptr));
684     }
685     ElemSegments.push_back(Segment);
686   }
687   if (Ptr != End)
688     return make_error<GenericBinaryError>("Elem section ended prematurely",
689                                           object_error::parse_failed);
690   return Error::success();
691 }
692 
693 Error WasmObjectFile::parseDataSection(const uint8_t *Ptr, const uint8_t *End) {
694   const uint8_t *Start = Ptr;
695   uint32_t Count = readVaruint32(Ptr);
696   DataSegments.reserve(Count);
697   while (Count--) {
698     WasmSegment Segment;
699     Segment.Data.MemoryIndex = readVaruint32(Ptr);
700     if (Error Err = readInitExpr(Segment.Data.Offset, Ptr))
701       return Err;
702     uint32_t Size = readVaruint32(Ptr);
703     Segment.Data.Content = ArrayRef<uint8_t>(Ptr, Size);
704     Segment.SectionOffset = Ptr - Start;
705     Ptr += Size;
706     DataSegments.push_back(Segment);
707   }
708   if (Ptr != End)
709     return make_error<GenericBinaryError>("Data section ended prematurely",
710                                           object_error::parse_failed);
711   return Error::success();
712 }
713 
714 const uint8_t *WasmObjectFile::getPtr(size_t Offset) const {
715   return reinterpret_cast<const uint8_t *>(getData().substr(Offset, 1).data());
716 }
717 
718 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
719   return Header;
720 }
721 
722 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.a++; }
723 
724 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
725   uint32_t Result = SymbolRef::SF_None;
726   const WasmSymbol &Sym = getWasmSymbol(Symb);
727 
728   DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
729   if (Sym.Flags & wasm::WASM_SYMBOL_FLAG_WEAK)
730     Result |= SymbolRef::SF_Weak;
731 
732   switch (Sym.Type) {
733   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
734     Result |= SymbolRef::SF_Undefined | SymbolRef::SF_Executable;
735     break;
736   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
737     Result |= SymbolRef::SF_Global | SymbolRef::SF_Executable;
738     break;
739   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
740     Result |= SymbolRef::SF_Executable;
741     Result |= SymbolRef::SF_FormatSpecific;
742     break;
743   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
744     Result |= SymbolRef::SF_Undefined;
745     break;
746   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
747     Result |= SymbolRef::SF_Global;
748     break;
749   }
750 
751   return Result;
752 }
753 
754 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
755   DataRefImpl Ref;
756   Ref.d.a = 0;
757   return BasicSymbolRef(Ref, this);
758 }
759 
760 basic_symbol_iterator WasmObjectFile::symbol_end() const {
761   DataRefImpl Ref;
762   Ref.d.a = Symbols.size();
763   return BasicSymbolRef(Ref, this);
764 }
765 
766 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
767   return Symbols[Symb.d.a];
768 }
769 
770 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
771   return getWasmSymbol(Symb.getRawDataRefImpl());
772 }
773 
774 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
775   return getWasmSymbol(Symb).Name;
776 }
777 
778 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
779   return getSymbolValue(Symb);
780 }
781 
782 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
783   const WasmSymbol& Sym = getWasmSymbol(Symb);
784   switch (Sym.Type) {
785   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
786   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
787     return 0;
788   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
789     return Exports[Sym.ElementIndex].Index;
790   case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
791     uint32_t GlobalIndex = Exports[Sym.ElementIndex].Index - NumImportedGlobals;
792     assert(GlobalIndex < Globals.size());
793     const wasm::WasmGlobal& Global = Globals[GlobalIndex];
794     return Global.InitExpr.Value.Int32;
795   }
796   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
797     return Sym.ElementIndex;
798   }
799   llvm_unreachable("invalid symbol type");
800 }
801 
802 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
803   llvm_unreachable("not yet implemented");
804   return 0;
805 }
806 
807 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
808   llvm_unreachable("not yet implemented");
809   return 0;
810 }
811 
812 Expected<SymbolRef::Type>
813 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
814   const WasmSymbol &Sym = getWasmSymbol(Symb);
815 
816   switch (Sym.Type) {
817   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
818   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
819   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
820     return SymbolRef::ST_Function;
821   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
822   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
823     return SymbolRef::ST_Data;
824   }
825 
826   llvm_unreachable("Unknown WasmSymbol::SymbolType");
827   return SymbolRef::ST_Other;
828 }
829 
830 Expected<section_iterator>
831 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
832   DataRefImpl Ref;
833   Ref.d.a = getWasmSymbol(Symb).Section;
834   return section_iterator(SectionRef(Ref, this));
835 }
836 
837 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
838 
839 std::error_code WasmObjectFile::getSectionName(DataRefImpl Sec,
840                                                StringRef &Res) const {
841   const WasmSection &S = Sections[Sec.d.a];
842 #define ECase(X)                                                               \
843   case wasm::WASM_SEC_##X:                                                     \
844     Res = #X;                                                                  \
845     break
846   switch (S.Type) {
847     ECase(TYPE);
848     ECase(IMPORT);
849     ECase(FUNCTION);
850     ECase(TABLE);
851     ECase(MEMORY);
852     ECase(GLOBAL);
853     ECase(EXPORT);
854     ECase(START);
855     ECase(ELEM);
856     ECase(CODE);
857     ECase(DATA);
858   case wasm::WASM_SEC_CUSTOM:
859     Res = S.Name;
860     break;
861   default:
862     return object_error::invalid_section_index;
863   }
864 #undef ECase
865   return std::error_code();
866 }
867 
868 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
869 
870 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
871   return Sec.d.a;
872 }
873 
874 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
875   const WasmSection &S = Sections[Sec.d.a];
876   return S.Content.size();
877 }
878 
879 std::error_code WasmObjectFile::getSectionContents(DataRefImpl Sec,
880                                                    StringRef &Res) const {
881   const WasmSection &S = Sections[Sec.d.a];
882   // This will never fail since wasm sections can never be empty (user-sections
883   // must have a name and non-user sections each have a defined structure).
884   Res = StringRef(reinterpret_cast<const char *>(S.Content.data()),
885                   S.Content.size());
886   return std::error_code();
887 }
888 
889 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
890   return 1;
891 }
892 
893 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
894   return false;
895 }
896 
897 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
898   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
899 }
900 
901 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
902   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
903 }
904 
905 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
906 
907 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
908 
909 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
910 
911 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
912   DataRefImpl RelocRef;
913   RelocRef.d.a = Ref.d.a;
914   RelocRef.d.b = 0;
915   return relocation_iterator(RelocationRef(RelocRef, this));
916 }
917 
918 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
919   const WasmSection &Sec = getWasmSection(Ref);
920   DataRefImpl RelocRef;
921   RelocRef.d.a = Ref.d.a;
922   RelocRef.d.b = Sec.Relocations.size();
923   return relocation_iterator(RelocationRef(RelocRef, this));
924 }
925 
926 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const {
927   Rel.d.b++;
928 }
929 
930 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
931   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
932   return Rel.Offset;
933 }
934 
935 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
936   llvm_unreachable("not yet implemented");
937   SymbolRef Ref;
938   return symbol_iterator(Ref);
939 }
940 
941 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
942   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
943   return Rel.Type;
944 }
945 
946 void WasmObjectFile::getRelocationTypeName(
947     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
948   const wasm::WasmRelocation& Rel = getWasmRelocation(Ref);
949   StringRef Res = "Unknown";
950 
951 #define WASM_RELOC(name, value)  \
952   case wasm::name:              \
953     Res = #name;               \
954     break;
955 
956   switch (Rel.Type) {
957 #include "llvm/BinaryFormat/WasmRelocs/WebAssembly.def"
958   }
959 
960 #undef WASM_RELOC
961 
962   Result.append(Res.begin(), Res.end());
963 }
964 
965 section_iterator WasmObjectFile::section_begin() const {
966   DataRefImpl Ref;
967   Ref.d.a = 0;
968   return section_iterator(SectionRef(Ref, this));
969 }
970 
971 section_iterator WasmObjectFile::section_end() const {
972   DataRefImpl Ref;
973   Ref.d.a = Sections.size();
974   return section_iterator(SectionRef(Ref, this));
975 }
976 
977 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
978 
979 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
980 
981 unsigned WasmObjectFile::getArch() const { return Triple::wasm32; }
982 
983 SubtargetFeatures WasmObjectFile::getFeatures() const {
984   return SubtargetFeatures();
985 }
986 
987 bool WasmObjectFile::isRelocatableObject() const {
988   return HasLinkingSection;
989 }
990 
991 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
992   assert(Ref.d.a < Sections.size());
993   return Sections[Ref.d.a];
994 }
995 
996 const WasmSection &
997 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
998   return getWasmSection(Section.getRawDataRefImpl());
999 }
1000 
1001 const wasm::WasmRelocation &
1002 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1003   return getWasmRelocation(Ref.getRawDataRefImpl());
1004 }
1005 
1006 const wasm::WasmRelocation &
1007 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1008   assert(Ref.d.a < Sections.size());
1009   const WasmSection& Sec = Sections[Ref.d.a];
1010   assert(Ref.d.b < Sec.Relocations.size());
1011   return Sec.Relocations[Ref.d.b];
1012 }
1013