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, const uint8_t *Eof) {
182   Section.Offset = Ptr - Start;
183   Section.Type = readVaruint7(Ptr);
184   uint32_t Size = readVaruint32(Ptr);
185   if (Size == 0)
186     return make_error<StringError>("Zero length section",
187                                    object_error::parse_failed);
188   if (Ptr + Size > Eof)
189     return make_error<StringError>("Section too large",
190                                    object_error::parse_failed);
191   Section.Content = ArrayRef<uint8_t>(Ptr, Size);
192   Ptr += Size;
193   return Error::success();
194 }
195 
196 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
197     : ObjectFile(Binary::ID_Wasm, Buffer) {
198   LinkingData.DataSize = 0;
199 
200   ErrorAsOutParameter ErrAsOutParam(&Err);
201   Header.Magic = getData().substr(0, 4);
202   if (Header.Magic != StringRef("\0asm", 4)) {
203     Err = make_error<StringError>("Bad magic number",
204                                   object_error::parse_failed);
205     return;
206   }
207 
208   const uint8_t *Eof = getPtr(getData().size());
209   const uint8_t *Ptr = getPtr(4);
210 
211   if (Ptr + 4 > Eof) {
212     Err = make_error<StringError>("Missing version number",
213                                   object_error::parse_failed);
214     return;
215   }
216 
217   Header.Version = readUint32(Ptr);
218   if (Header.Version != wasm::WasmVersion) {
219     Err = make_error<StringError>("Bad version number",
220                                   object_error::parse_failed);
221     return;
222   }
223 
224   WasmSection Sec;
225   while (Ptr < Eof) {
226     if ((Err = readSection(Sec, Ptr, getPtr(0), Eof)))
227       return;
228     if ((Err = parseSection(Sec)))
229       return;
230 
231     Sections.push_back(Sec);
232   }
233 }
234 
235 Error WasmObjectFile::parseSection(WasmSection &Sec) {
236   const uint8_t* Start = Sec.Content.data();
237   const uint8_t* End = Start + Sec.Content.size();
238   switch (Sec.Type) {
239   case wasm::WASM_SEC_CUSTOM:
240     return parseCustomSection(Sec, Start, End);
241   case wasm::WASM_SEC_TYPE:
242     return parseTypeSection(Start, End);
243   case wasm::WASM_SEC_IMPORT:
244     return parseImportSection(Start, End);
245   case wasm::WASM_SEC_FUNCTION:
246     return parseFunctionSection(Start, End);
247   case wasm::WASM_SEC_TABLE:
248     return parseTableSection(Start, End);
249   case wasm::WASM_SEC_MEMORY:
250     return parseMemorySection(Start, End);
251   case wasm::WASM_SEC_GLOBAL:
252     return parseGlobalSection(Start, End);
253   case wasm::WASM_SEC_EXPORT:
254     return parseExportSection(Start, End);
255   case wasm::WASM_SEC_START:
256     return parseStartSection(Start, End);
257   case wasm::WASM_SEC_ELEM:
258     return parseElemSection(Start, End);
259   case wasm::WASM_SEC_CODE:
260     return parseCodeSection(Start, End);
261   case wasm::WASM_SEC_DATA:
262     return parseDataSection(Start, End);
263   default:
264     return make_error<GenericBinaryError>("Bad section type",
265                                           object_error::parse_failed);
266   }
267 }
268 
269 Error WasmObjectFile::parseNameSection(const uint8_t *Ptr, const uint8_t *End) {
270   while (Ptr < End) {
271     uint8_t Type = readVarint7(Ptr);
272     uint32_t Size = readVaruint32(Ptr);
273     const uint8_t *SubSectionEnd = Ptr + Size;
274     switch (Type) {
275     case wasm::WASM_NAMES_FUNCTION: {
276       uint32_t Count = readVaruint32(Ptr);
277       while (Count--) {
278         uint32_t Index = readVaruint32(Ptr);
279         StringRef Name = readString(Ptr);
280         if (!Name.empty())
281           Symbols.emplace_back(Name,
282                                WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME,
283                                Sections.size(), Index);
284       }
285       break;
286     }
287     // Ignore local names for now
288     case wasm::WASM_NAMES_LOCAL:
289     default:
290       Ptr += Size;
291       break;
292     }
293     if (Ptr != SubSectionEnd)
294       return make_error<GenericBinaryError>("Name sub-section ended prematurely",
295                                             object_error::parse_failed);
296   }
297 
298   if (Ptr != End)
299     return make_error<GenericBinaryError>("Name section ended prematurely",
300                                           object_error::parse_failed);
301   return Error::success();
302 }
303 
304 void WasmObjectFile::populateSymbolTable() {
305   // Add imports to symbol table
306   size_t ImportIndex = 0;
307   size_t GlobalIndex = 0;
308   size_t FunctionIndex = 0;
309   for (const wasm::WasmImport& Import : Imports) {
310     switch (Import.Kind) {
311     case wasm::WASM_EXTERNAL_GLOBAL:
312       assert(Import.Global.Type == wasm::WASM_TYPE_I32);
313       SymbolMap.try_emplace(Import.Field, Symbols.size());
314       Symbols.emplace_back(Import.Field, WasmSymbol::SymbolType::GLOBAL_IMPORT,
315                            ImportSection, GlobalIndex++, ImportIndex);
316       DEBUG(dbgs() << "Adding import: " << Symbols.back()
317                    << " sym index:" << Symbols.size() << "\n");
318       break;
319     case wasm::WASM_EXTERNAL_FUNCTION:
320       SymbolMap.try_emplace(Import.Field, Symbols.size());
321       Symbols.emplace_back(Import.Field,
322                            WasmSymbol::SymbolType::FUNCTION_IMPORT,
323                            ImportSection, FunctionIndex++, ImportIndex);
324       DEBUG(dbgs() << "Adding import: " << Symbols.back()
325                    << " sym index:" << Symbols.size() << "\n");
326       break;
327     default:
328       break;
329     }
330     ImportIndex++;
331   }
332 
333   // Add exports to symbol table
334   for (const wasm::WasmExport& Export : Exports) {
335     if (Export.Kind == wasm::WASM_EXTERNAL_FUNCTION ||
336         Export.Kind == wasm::WASM_EXTERNAL_GLOBAL) {
337       WasmSymbol::SymbolType ExportType =
338           Export.Kind == wasm::WASM_EXTERNAL_FUNCTION
339               ? WasmSymbol::SymbolType::FUNCTION_EXPORT
340               : WasmSymbol::SymbolType::GLOBAL_EXPORT;
341       SymbolMap.try_emplace(Export.Name, Symbols.size());
342       Symbols.emplace_back(Export.Name, ExportType,
343                            ExportSection, Export.Index);
344       DEBUG(dbgs() << "Adding export: " << Symbols.back()
345                    << " sym index:" << Symbols.size() << "\n");
346     }
347   }
348 }
349 
350 Error WasmObjectFile::parseLinkingSection(const uint8_t *Ptr,
351                                           const uint8_t *End) {
352   HasLinkingSection = true;
353 
354   // Only populate the symbol table with imports and exports if the object
355   // has a linking section (i.e. its a relocatable object file). Otherwise
356   // the global might not represent symbols at all.
357   populateSymbolTable();
358 
359   while (Ptr < End) {
360     uint8_t Type = readVarint7(Ptr);
361     uint32_t Size = readVaruint32(Ptr);
362     const uint8_t *SubSectionEnd = Ptr + Size;
363     switch (Type) {
364     case wasm::WASM_SYMBOL_INFO: {
365       uint32_t Count = readVaruint32(Ptr);
366       while (Count--) {
367         StringRef Symbol = readString(Ptr);
368         DEBUG(dbgs() << "reading syminfo: " << Symbol << "\n");
369         uint32_t Flags = readVaruint32(Ptr);
370         auto iter = SymbolMap.find(Symbol);
371         if (iter == SymbolMap.end()) {
372           return make_error<GenericBinaryError>(
373               "Invalid symbol name in linking section: " + Symbol,
374               object_error::parse_failed);
375         }
376         uint32_t SymIndex = iter->second;
377         assert(SymIndex < Symbols.size());
378         Symbols[SymIndex].Flags = Flags;
379         DEBUG(dbgs() << "Set symbol flags index:"
380                      << SymIndex << " name:"
381                      << Symbols[SymIndex].Name << " expected:"
382                      << Symbol << " flags: " << Flags << "\n");
383       }
384       break;
385     }
386     case wasm::WASM_DATA_SIZE:
387       LinkingData.DataSize = readVaruint32(Ptr);
388       break;
389     case wasm::WASM_SEGMENT_INFO: {
390       uint32_t Count = readVaruint32(Ptr);
391       if (Count > DataSegments.size())
392         return make_error<GenericBinaryError>("Too many segment names",
393                                               object_error::parse_failed);
394       for (uint32_t i = 0; i < Count; i++) {
395         DataSegments[i].Data.Name = readString(Ptr);
396         DataSegments[i].Data.Alignment = readVaruint32(Ptr);
397         DataSegments[i].Data.Flags = readVaruint32(Ptr);
398       }
399       break;
400     }
401     default:
402       Ptr += Size;
403       break;
404     }
405     if (Ptr != SubSectionEnd)
406       return make_error<GenericBinaryError>(
407           "Linking sub-section ended prematurely", object_error::parse_failed);
408   }
409   if (Ptr != End)
410     return make_error<GenericBinaryError>("Linking section ended prematurely",
411                                           object_error::parse_failed);
412   return Error::success();
413 }
414 
415 WasmSection* WasmObjectFile::findCustomSectionByName(StringRef Name) {
416   for (WasmSection& Section : Sections) {
417     if (Section.Type == wasm::WASM_SEC_CUSTOM && Section.Name == Name)
418       return &Section;
419   }
420   return nullptr;
421 }
422 
423 WasmSection* WasmObjectFile::findSectionByType(uint32_t Type) {
424   assert(Type != wasm::WASM_SEC_CUSTOM);
425   for (WasmSection& Section : Sections) {
426     if (Section.Type == Type)
427       return &Section;
428   }
429   return nullptr;
430 }
431 
432 Error WasmObjectFile::parseRelocSection(StringRef Name, const uint8_t *Ptr,
433                                         const uint8_t *End) {
434   uint8_t SectionCode = readVarint7(Ptr);
435   WasmSection* Section = nullptr;
436   if (SectionCode == wasm::WASM_SEC_CUSTOM) {
437     StringRef Name = readString(Ptr);
438     Section = findCustomSectionByName(Name);
439   } else {
440     Section = findSectionByType(SectionCode);
441   }
442   if (!Section)
443     return make_error<GenericBinaryError>("Invalid section code",
444                                           object_error::parse_failed);
445   uint32_t RelocCount = readVaruint32(Ptr);
446   while (RelocCount--) {
447     wasm::WasmRelocation Reloc;
448     memset(&Reloc, 0, sizeof(Reloc));
449     Reloc.Type = readVaruint32(Ptr);
450     Reloc.Offset = readVaruint32(Ptr);
451     Reloc.Index = readVaruint32(Ptr);
452     switch (Reloc.Type) {
453     case wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB:
454     case wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB:
455     case wasm::R_WEBASSEMBLY_TABLE_INDEX_I32:
456     case wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB:
457     case wasm::R_WEBASSEMBLY_GLOBAL_INDEX_LEB:
458       break;
459     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_LEB:
460     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_SLEB:
461     case wasm::R_WEBASSEMBLY_MEMORY_ADDR_I32:
462       Reloc.Addend = readVarint32(Ptr);
463       break;
464     default:
465       return make_error<GenericBinaryError>("Bad relocation type: " +
466                                                 Twine(Reloc.Type),
467                                             object_error::parse_failed);
468     }
469     Section->Relocations.push_back(Reloc);
470   }
471   if (Ptr != End)
472     return make_error<GenericBinaryError>("Reloc section ended prematurely",
473                                           object_error::parse_failed);
474   return Error::success();
475 }
476 
477 Error WasmObjectFile::parseCustomSection(WasmSection &Sec,
478                                          const uint8_t *Ptr, const uint8_t *End) {
479   Sec.Name = readString(Ptr);
480   if (Sec.Name == "name") {
481     if (Error Err = parseNameSection(Ptr, End))
482       return Err;
483   } else if (Sec.Name == "linking") {
484     if (Error Err = parseLinkingSection(Ptr, End))
485       return Err;
486   } else if (Sec.Name.startswith("reloc.")) {
487     if (Error Err = parseRelocSection(Sec.Name, Ptr, End))
488       return Err;
489   }
490   return Error::success();
491 }
492 
493 Error WasmObjectFile::parseTypeSection(const uint8_t *Ptr, const uint8_t *End) {
494   uint32_t Count = readVaruint32(Ptr);
495   Signatures.reserve(Count);
496   while (Count--) {
497     wasm::WasmSignature Sig;
498     Sig.ReturnType = wasm::WASM_TYPE_NORESULT;
499     int8_t Form = readVarint7(Ptr);
500     if (Form != wasm::WASM_TYPE_FUNC) {
501       return make_error<GenericBinaryError>("Invalid signature type",
502                                             object_error::parse_failed);
503     }
504     uint32_t ParamCount = readVaruint32(Ptr);
505     Sig.ParamTypes.reserve(ParamCount);
506     while (ParamCount--) {
507       uint32_t ParamType = readVarint7(Ptr);
508       Sig.ParamTypes.push_back(ParamType);
509     }
510     uint32_t ReturnCount = readVaruint32(Ptr);
511     if (ReturnCount) {
512       if (ReturnCount != 1) {
513         return make_error<GenericBinaryError>(
514             "Multiple return types not supported", object_error::parse_failed);
515       }
516       Sig.ReturnType = readVarint7(Ptr);
517     }
518     Signatures.push_back(Sig);
519   }
520   if (Ptr != End)
521     return make_error<GenericBinaryError>("Type section ended prematurely",
522                                           object_error::parse_failed);
523   return Error::success();
524 }
525 
526 Error WasmObjectFile::parseImportSection(const uint8_t *Ptr, const uint8_t *End) {
527   ImportSection = Sections.size();
528   uint32_t Count = readVaruint32(Ptr);
529   Imports.reserve(Count);
530   for (uint32_t i = 0; i < Count; i++) {
531     wasm::WasmImport Im;
532     Im.Module = readString(Ptr);
533     Im.Field = readString(Ptr);
534     Im.Kind = readUint8(Ptr);
535     switch (Im.Kind) {
536     case wasm::WASM_EXTERNAL_FUNCTION:
537       NumImportedFunctions++;
538       Im.SigIndex = readVaruint32(Ptr);
539       break;
540     case wasm::WASM_EXTERNAL_GLOBAL:
541       NumImportedGlobals++;
542       Im.Global.Type = readVarint7(Ptr);
543       Im.Global.Mutable = readVaruint1(Ptr);
544       break;
545     case wasm::WASM_EXTERNAL_MEMORY:
546       Im.Memory = readLimits(Ptr);
547       break;
548     case wasm::WASM_EXTERNAL_TABLE:
549       Im.Table = readTable(Ptr);
550       if (Im.Table.ElemType != wasm::WASM_TYPE_ANYFUNC)
551         return make_error<GenericBinaryError>("Invalid table element type",
552                                               object_error::parse_failed);
553       break;
554     default:
555       return make_error<GenericBinaryError>(
556           "Unexpected import kind", object_error::parse_failed);
557     }
558     Imports.push_back(Im);
559   }
560   if (Ptr != End)
561     return make_error<GenericBinaryError>("Import section ended prematurely",
562                                           object_error::parse_failed);
563   return Error::success();
564 }
565 
566 Error WasmObjectFile::parseFunctionSection(const uint8_t *Ptr, const uint8_t *End) {
567   uint32_t Count = readVaruint32(Ptr);
568   FunctionTypes.reserve(Count);
569   while (Count--) {
570     FunctionTypes.push_back(readVaruint32(Ptr));
571   }
572   if (Ptr != End)
573     return make_error<GenericBinaryError>("Function section ended prematurely",
574                                           object_error::parse_failed);
575   return Error::success();
576 }
577 
578 Error WasmObjectFile::parseTableSection(const uint8_t *Ptr, const uint8_t *End) {
579   uint32_t Count = readVaruint32(Ptr);
580   Tables.reserve(Count);
581   while (Count--) {
582     Tables.push_back(readTable(Ptr));
583     if (Tables.back().ElemType != wasm::WASM_TYPE_ANYFUNC) {
584       return make_error<GenericBinaryError>("Invalid table element type",
585                                             object_error::parse_failed);
586     }
587   }
588   if (Ptr != End)
589     return make_error<GenericBinaryError>("Table section ended prematurely",
590                                           object_error::parse_failed);
591   return Error::success();
592 }
593 
594 Error WasmObjectFile::parseMemorySection(const uint8_t *Ptr, const uint8_t *End) {
595   uint32_t Count = readVaruint32(Ptr);
596   Memories.reserve(Count);
597   while (Count--) {
598     Memories.push_back(readLimits(Ptr));
599   }
600   if (Ptr != End)
601     return make_error<GenericBinaryError>("Memory section ended prematurely",
602                                           object_error::parse_failed);
603   return Error::success();
604 }
605 
606 Error WasmObjectFile::parseGlobalSection(const uint8_t *Ptr, const uint8_t *End) {
607   uint32_t Count = readVaruint32(Ptr);
608   Globals.reserve(Count);
609   while (Count--) {
610     wasm::WasmGlobal Global;
611     Global.Type = readVarint7(Ptr);
612     Global.Mutable = readVaruint1(Ptr);
613     if (Error Err = readInitExpr(Global.InitExpr, Ptr))
614       return Err;
615     Globals.push_back(Global);
616   }
617   if (Ptr != End)
618     return make_error<GenericBinaryError>("Global section ended prematurely",
619                                           object_error::parse_failed);
620   return Error::success();
621 }
622 
623 Error WasmObjectFile::parseExportSection(const uint8_t *Ptr, const uint8_t *End) {
624   ExportSection = Sections.size();
625   uint32_t Count = readVaruint32(Ptr);
626   Exports.reserve(Count);
627   for (uint32_t i = 0; i < Count; i++) {
628     wasm::WasmExport Ex;
629     Ex.Name = readString(Ptr);
630     Ex.Kind = readUint8(Ptr);
631     Ex.Index = readVaruint32(Ptr);
632     switch (Ex.Kind) {
633     case wasm::WASM_EXTERNAL_FUNCTION:
634       if (Ex.Index >= FunctionTypes.size() + NumImportedFunctions)
635         return make_error<GenericBinaryError>("Invalid function export",
636                                               object_error::parse_failed);
637       break;
638     case wasm::WASM_EXTERNAL_GLOBAL: {
639       if (Ex.Index >= Globals.size() + NumImportedGlobals)
640         return make_error<GenericBinaryError>("Invalid global export",
641                                               object_error::parse_failed);
642       break;
643     }
644     case wasm::WASM_EXTERNAL_MEMORY:
645     case wasm::WASM_EXTERNAL_TABLE:
646       break;
647     default:
648       return make_error<GenericBinaryError>(
649           "Unexpected export kind", object_error::parse_failed);
650     }
651     Exports.push_back(Ex);
652   }
653   if (Ptr != End)
654     return make_error<GenericBinaryError>("Export section ended prematurely",
655                                           object_error::parse_failed);
656   return Error::success();
657 }
658 
659 Error WasmObjectFile::parseStartSection(const uint8_t *Ptr, const uint8_t *End) {
660   StartFunction = readVaruint32(Ptr);
661   if (StartFunction >= FunctionTypes.size())
662     return make_error<GenericBinaryError>("Invalid start function",
663                                           object_error::parse_failed);
664   return Error::success();
665 }
666 
667 Error WasmObjectFile::parseCodeSection(const uint8_t *Ptr, const uint8_t *End) {
668   uint32_t FunctionCount = readVaruint32(Ptr);
669   if (FunctionCount != FunctionTypes.size()) {
670     return make_error<GenericBinaryError>("Invalid function count",
671                                           object_error::parse_failed);
672   }
673 
674   CodeSection = ArrayRef<uint8_t>(Ptr, End - Ptr);
675 
676   while (FunctionCount--) {
677     wasm::WasmFunction Function;
678     uint32_t FunctionSize = readVaruint32(Ptr);
679     const uint8_t *FunctionEnd = Ptr + FunctionSize;
680 
681     uint32_t NumLocalDecls = readVaruint32(Ptr);
682     Function.Locals.reserve(NumLocalDecls);
683     while (NumLocalDecls--) {
684       wasm::WasmLocalDecl Decl;
685       Decl.Count = readVaruint32(Ptr);
686       Decl.Type = readVarint7(Ptr);
687       Function.Locals.push_back(Decl);
688     }
689 
690     uint32_t BodySize = FunctionEnd - Ptr;
691     Function.Body = ArrayRef<uint8_t>(Ptr, BodySize);
692     Ptr += BodySize;
693     assert(Ptr == FunctionEnd);
694     Functions.push_back(Function);
695   }
696   if (Ptr != End)
697     return make_error<GenericBinaryError>("Code section ended prematurely",
698                                           object_error::parse_failed);
699   return Error::success();
700 }
701 
702 Error WasmObjectFile::parseElemSection(const uint8_t *Ptr, const uint8_t *End) {
703   uint32_t Count = readVaruint32(Ptr);
704   ElemSegments.reserve(Count);
705   while (Count--) {
706     wasm::WasmElemSegment Segment;
707     Segment.TableIndex = readVaruint32(Ptr);
708     if (Segment.TableIndex != 0) {
709       return make_error<GenericBinaryError>("Invalid TableIndex",
710                                             object_error::parse_failed);
711     }
712     if (Error Err = readInitExpr(Segment.Offset, Ptr))
713       return Err;
714     uint32_t NumElems = readVaruint32(Ptr);
715     while (NumElems--) {
716       Segment.Functions.push_back(readVaruint32(Ptr));
717     }
718     ElemSegments.push_back(Segment);
719   }
720   if (Ptr != End)
721     return make_error<GenericBinaryError>("Elem section ended prematurely",
722                                           object_error::parse_failed);
723   return Error::success();
724 }
725 
726 Error WasmObjectFile::parseDataSection(const uint8_t *Ptr, const uint8_t *End) {
727   const uint8_t *Start = Ptr;
728   uint32_t Count = readVaruint32(Ptr);
729   DataSegments.reserve(Count);
730   while (Count--) {
731     WasmSegment Segment;
732     Segment.Data.MemoryIndex = readVaruint32(Ptr);
733     if (Error Err = readInitExpr(Segment.Data.Offset, Ptr))
734       return Err;
735     uint32_t Size = readVaruint32(Ptr);
736     Segment.Data.Content = ArrayRef<uint8_t>(Ptr, Size);
737     Segment.Data.Alignment = 0;
738     Segment.Data.Flags = 0;
739     Segment.SectionOffset = Ptr - Start;
740     Ptr += Size;
741     DataSegments.push_back(Segment);
742   }
743   if (Ptr != End)
744     return make_error<GenericBinaryError>("Data section ended prematurely",
745                                           object_error::parse_failed);
746   return Error::success();
747 }
748 
749 const uint8_t *WasmObjectFile::getPtr(size_t Offset) const {
750   return reinterpret_cast<const uint8_t *>(getData().substr(Offset, 1).data());
751 }
752 
753 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
754   return Header;
755 }
756 
757 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.a++; }
758 
759 uint32_t WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
760   uint32_t Result = SymbolRef::SF_None;
761   const WasmSymbol &Sym = getWasmSymbol(Symb);
762 
763   DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
764   if (Sym.isWeak())
765     Result |= SymbolRef::SF_Weak;
766   if (!Sym.isLocal())
767     Result |= SymbolRef::SF_Global;
768   if (Sym.isHidden())
769     Result |= SymbolRef::SF_Hidden;
770 
771   switch (Sym.Type) {
772   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
773     Result |= SymbolRef::SF_Undefined | SymbolRef::SF_Executable;
774     break;
775   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
776     Result |= SymbolRef::SF_Executable;
777     break;
778   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
779     Result |= SymbolRef::SF_Executable;
780     Result |= SymbolRef::SF_FormatSpecific;
781     break;
782   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
783     Result |= SymbolRef::SF_Undefined;
784     break;
785   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
786     break;
787   }
788 
789   return Result;
790 }
791 
792 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
793   DataRefImpl Ref;
794   Ref.d.a = 0;
795   return BasicSymbolRef(Ref, this);
796 }
797 
798 basic_symbol_iterator WasmObjectFile::symbol_end() const {
799   DataRefImpl Ref;
800   Ref.d.a = Symbols.size();
801   return BasicSymbolRef(Ref, this);
802 }
803 
804 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
805   return Symbols[Symb.d.a];
806 }
807 
808 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
809   return getWasmSymbol(Symb.getRawDataRefImpl());
810 }
811 
812 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
813   return getWasmSymbol(Symb).Name;
814 }
815 
816 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
817   return getSymbolValue(Symb);
818 }
819 
820 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol& Sym) const {
821   switch (Sym.Type) {
822   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
823   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
824   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
825   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
826     return Sym.ElementIndex;
827   case WasmSymbol::SymbolType::GLOBAL_EXPORT: {
828     uint32_t GlobalIndex = Sym.ElementIndex - NumImportedGlobals;
829     assert(GlobalIndex < Globals.size());
830     const wasm::WasmGlobal& Global = Globals[GlobalIndex];
831     // WasmSymbols correspond only to I32_CONST globals
832     assert(Global.InitExpr.Opcode == wasm::WASM_OPCODE_I32_CONST);
833     return Global.InitExpr.Value.Int32;
834   }
835   }
836   llvm_unreachable("invalid symbol type");
837 }
838 
839 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
840   return getWasmSymbolValue(getWasmSymbol(Symb));
841 }
842 
843 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
844   llvm_unreachable("not yet implemented");
845   return 0;
846 }
847 
848 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
849   llvm_unreachable("not yet implemented");
850   return 0;
851 }
852 
853 Expected<SymbolRef::Type>
854 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
855   const WasmSymbol &Sym = getWasmSymbol(Symb);
856 
857   switch (Sym.Type) {
858   case WasmSymbol::SymbolType::FUNCTION_IMPORT:
859   case WasmSymbol::SymbolType::FUNCTION_EXPORT:
860   case WasmSymbol::SymbolType::DEBUG_FUNCTION_NAME:
861     return SymbolRef::ST_Function;
862   case WasmSymbol::SymbolType::GLOBAL_IMPORT:
863   case WasmSymbol::SymbolType::GLOBAL_EXPORT:
864     return SymbolRef::ST_Data;
865   }
866 
867   llvm_unreachable("Unknown WasmSymbol::SymbolType");
868   return SymbolRef::ST_Other;
869 }
870 
871 Expected<section_iterator>
872 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
873   DataRefImpl Ref;
874   Ref.d.a = getWasmSymbol(Symb).Section;
875   return section_iterator(SectionRef(Ref, this));
876 }
877 
878 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
879 
880 std::error_code WasmObjectFile::getSectionName(DataRefImpl Sec,
881                                                StringRef &Res) const {
882   const WasmSection &S = Sections[Sec.d.a];
883 #define ECase(X)                                                               \
884   case wasm::WASM_SEC_##X:                                                     \
885     Res = #X;                                                                  \
886     break
887   switch (S.Type) {
888     ECase(TYPE);
889     ECase(IMPORT);
890     ECase(FUNCTION);
891     ECase(TABLE);
892     ECase(MEMORY);
893     ECase(GLOBAL);
894     ECase(EXPORT);
895     ECase(START);
896     ECase(ELEM);
897     ECase(CODE);
898     ECase(DATA);
899   case wasm::WASM_SEC_CUSTOM:
900     Res = S.Name;
901     break;
902   default:
903     return object_error::invalid_section_index;
904   }
905 #undef ECase
906   return std::error_code();
907 }
908 
909 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
910 
911 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
912   return Sec.d.a;
913 }
914 
915 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
916   const WasmSection &S = Sections[Sec.d.a];
917   return S.Content.size();
918 }
919 
920 std::error_code WasmObjectFile::getSectionContents(DataRefImpl Sec,
921                                                    StringRef &Res) const {
922   const WasmSection &S = Sections[Sec.d.a];
923   // This will never fail since wasm sections can never be empty (user-sections
924   // must have a name and non-user sections each have a defined structure).
925   Res = StringRef(reinterpret_cast<const char *>(S.Content.data()),
926                   S.Content.size());
927   return std::error_code();
928 }
929 
930 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
931   return 1;
932 }
933 
934 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
935   return false;
936 }
937 
938 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
939   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
940 }
941 
942 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
943   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
944 }
945 
946 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
947 
948 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
949 
950 bool WasmObjectFile::isSectionBitcode(DataRefImpl Sec) const { return false; }
951 
952 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
953   DataRefImpl RelocRef;
954   RelocRef.d.a = Ref.d.a;
955   RelocRef.d.b = 0;
956   return relocation_iterator(RelocationRef(RelocRef, this));
957 }
958 
959 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
960   const WasmSection &Sec = getWasmSection(Ref);
961   DataRefImpl RelocRef;
962   RelocRef.d.a = Ref.d.a;
963   RelocRef.d.b = Sec.Relocations.size();
964   return relocation_iterator(RelocationRef(RelocRef, this));
965 }
966 
967 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const {
968   Rel.d.b++;
969 }
970 
971 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
972   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
973   return Rel.Offset;
974 }
975 
976 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Rel) const {
977   llvm_unreachable("not yet implemented");
978   SymbolRef Ref;
979   return symbol_iterator(Ref);
980 }
981 
982 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
983   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
984   return Rel.Type;
985 }
986 
987 void WasmObjectFile::getRelocationTypeName(
988     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
989   const wasm::WasmRelocation& Rel = getWasmRelocation(Ref);
990   StringRef Res = "Unknown";
991 
992 #define WASM_RELOC(name, value)  \
993   case wasm::name:              \
994     Res = #name;               \
995     break;
996 
997   switch (Rel.Type) {
998 #include "llvm/BinaryFormat/WasmRelocs/WebAssembly.def"
999   }
1000 
1001 #undef WASM_RELOC
1002 
1003   Result.append(Res.begin(), Res.end());
1004 }
1005 
1006 section_iterator WasmObjectFile::section_begin() const {
1007   DataRefImpl Ref;
1008   Ref.d.a = 0;
1009   return section_iterator(SectionRef(Ref, this));
1010 }
1011 
1012 section_iterator WasmObjectFile::section_end() const {
1013   DataRefImpl Ref;
1014   Ref.d.a = Sections.size();
1015   return section_iterator(SectionRef(Ref, this));
1016 }
1017 
1018 uint8_t WasmObjectFile::getBytesInAddress() const { return 4; }
1019 
1020 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1021 
1022 unsigned WasmObjectFile::getArch() const { return Triple::wasm32; }
1023 
1024 SubtargetFeatures WasmObjectFile::getFeatures() const {
1025   return SubtargetFeatures();
1026 }
1027 
1028 bool WasmObjectFile::isRelocatableObject() const {
1029   return HasLinkingSection;
1030 }
1031 
1032 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1033   assert(Ref.d.a < Sections.size());
1034   return Sections[Ref.d.a];
1035 }
1036 
1037 const WasmSection &
1038 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1039   return getWasmSection(Section.getRawDataRefImpl());
1040 }
1041 
1042 const wasm::WasmRelocation &
1043 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1044   return getWasmRelocation(Ref.getRawDataRefImpl());
1045 }
1046 
1047 const wasm::WasmRelocation &
1048 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1049   assert(Ref.d.a < Sections.size());
1050   const WasmSection& Sec = Sections[Ref.d.a];
1051   assert(Ref.d.b < Sec.Relocations.size());
1052   return Sec.Relocations[Ref.d.b];
1053 }
1054