1 //===- WasmObjectFile.cpp - Wasm object file implementation ---------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "llvm/ADT/ArrayRef.h"
10 #include "llvm/ADT/DenseSet.h"
11 #include "llvm/ADT/STLExtras.h"
12 #include "llvm/ADT/SmallSet.h"
13 #include "llvm/ADT/StringRef.h"
14 #include "llvm/ADT/StringSet.h"
15 #include "llvm/ADT/StringSwitch.h"
16 #include "llvm/ADT/Triple.h"
17 #include "llvm/BinaryFormat/Wasm.h"
18 #include "llvm/MC/SubtargetFeature.h"
19 #include "llvm/Object/Binary.h"
20 #include "llvm/Object/Error.h"
21 #include "llvm/Object/ObjectFile.h"
22 #include "llvm/Object/SymbolicFile.h"
23 #include "llvm/Object/Wasm.h"
24 #include "llvm/Support/Endian.h"
25 #include "llvm/Support/Error.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/LEB128.h"
28 #include "llvm/Support/ScopedPrinter.h"
29 #include <algorithm>
30 #include <cassert>
31 #include <cstdint>
32 #include <cstring>
33 #include <system_error>
34 
35 #define DEBUG_TYPE "wasm-object"
36 
37 using namespace llvm;
38 using namespace object;
39 
40 void WasmSymbol::print(raw_ostream &Out) const {
41   Out << "Name=" << Info.Name
42       << ", Kind=" << toString(wasm::WasmSymbolType(Info.Kind))
43       << ", Flags=" << Info.Flags;
44   if (!isTypeData()) {
45     Out << ", ElemIndex=" << Info.ElementIndex;
46   } else if (isDefined()) {
47     Out << ", Segment=" << Info.DataRef.Segment;
48     Out << ", Offset=" << Info.DataRef.Offset;
49     Out << ", Size=" << Info.DataRef.Size;
50   }
51 }
52 
53 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
54 LLVM_DUMP_METHOD void WasmSymbol::dump() const { print(dbgs()); }
55 #endif
56 
57 Expected<std::unique_ptr<WasmObjectFile>>
58 ObjectFile::createWasmObjectFile(MemoryBufferRef Buffer) {
59   Error Err = Error::success();
60   auto ObjectFile = std::make_unique<WasmObjectFile>(Buffer, Err);
61   if (Err)
62     return std::move(Err);
63 
64   return std::move(ObjectFile);
65 }
66 
67 #define VARINT7_MAX ((1 << 7) - 1)
68 #define VARINT7_MIN (-(1 << 7))
69 #define VARUINT7_MAX (1 << 7)
70 #define VARUINT1_MAX (1)
71 
72 static uint8_t readUint8(WasmObjectFile::ReadContext &Ctx) {
73   if (Ctx.Ptr == Ctx.End)
74     report_fatal_error("EOF while reading uint8");
75   return *Ctx.Ptr++;
76 }
77 
78 static uint32_t readUint32(WasmObjectFile::ReadContext &Ctx) {
79   if (Ctx.Ptr + 4 > Ctx.End)
80     report_fatal_error("EOF while reading uint32");
81   uint32_t Result = support::endian::read32le(Ctx.Ptr);
82   Ctx.Ptr += 4;
83   return Result;
84 }
85 
86 static int32_t readFloat32(WasmObjectFile::ReadContext &Ctx) {
87   if (Ctx.Ptr + 4 > Ctx.End)
88     report_fatal_error("EOF while reading float64");
89   int32_t Result = 0;
90   memcpy(&Result, Ctx.Ptr, sizeof(Result));
91   Ctx.Ptr += sizeof(Result);
92   return Result;
93 }
94 
95 static int64_t readFloat64(WasmObjectFile::ReadContext &Ctx) {
96   if (Ctx.Ptr + 8 > Ctx.End)
97     report_fatal_error("EOF while reading float64");
98   int64_t Result = 0;
99   memcpy(&Result, Ctx.Ptr, sizeof(Result));
100   Ctx.Ptr += sizeof(Result);
101   return Result;
102 }
103 
104 static uint64_t readULEB128(WasmObjectFile::ReadContext &Ctx) {
105   unsigned Count;
106   const char *Error = nullptr;
107   uint64_t Result = decodeULEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
108   if (Error)
109     report_fatal_error(Error);
110   Ctx.Ptr += Count;
111   return Result;
112 }
113 
114 static StringRef readString(WasmObjectFile::ReadContext &Ctx) {
115   uint32_t StringLen = readULEB128(Ctx);
116   if (Ctx.Ptr + StringLen > Ctx.End)
117     report_fatal_error("EOF while reading string");
118   StringRef Return =
119       StringRef(reinterpret_cast<const char *>(Ctx.Ptr), StringLen);
120   Ctx.Ptr += StringLen;
121   return Return;
122 }
123 
124 static int64_t readLEB128(WasmObjectFile::ReadContext &Ctx) {
125   unsigned Count;
126   const char *Error = nullptr;
127   uint64_t Result = decodeSLEB128(Ctx.Ptr, &Count, Ctx.End, &Error);
128   if (Error)
129     report_fatal_error(Error);
130   Ctx.Ptr += Count;
131   return Result;
132 }
133 
134 static uint8_t readVaruint1(WasmObjectFile::ReadContext &Ctx) {
135   int64_t Result = readLEB128(Ctx);
136   if (Result > VARUINT1_MAX || Result < 0)
137     report_fatal_error("LEB is outside Varuint1 range");
138   return Result;
139 }
140 
141 static int32_t readVarint32(WasmObjectFile::ReadContext &Ctx) {
142   int64_t Result = readLEB128(Ctx);
143   if (Result > INT32_MAX || Result < INT32_MIN)
144     report_fatal_error("LEB is outside Varint32 range");
145   return Result;
146 }
147 
148 static uint32_t readVaruint32(WasmObjectFile::ReadContext &Ctx) {
149   uint64_t Result = readULEB128(Ctx);
150   if (Result > UINT32_MAX)
151     report_fatal_error("LEB is outside Varuint32 range");
152   return Result;
153 }
154 
155 static int64_t readVarint64(WasmObjectFile::ReadContext &Ctx) {
156   return readLEB128(Ctx);
157 }
158 
159 static uint64_t readVaruint64(WasmObjectFile::ReadContext &Ctx) {
160   return readULEB128(Ctx);
161 }
162 
163 static uint8_t readOpcode(WasmObjectFile::ReadContext &Ctx) {
164   return readUint8(Ctx);
165 }
166 
167 static Error readInitExpr(wasm::WasmInitExpr &Expr,
168                           WasmObjectFile::ReadContext &Ctx) {
169   Expr.Opcode = readOpcode(Ctx);
170 
171   switch (Expr.Opcode) {
172   case wasm::WASM_OPCODE_I32_CONST:
173     Expr.Value.Int32 = readVarint32(Ctx);
174     break;
175   case wasm::WASM_OPCODE_I64_CONST:
176     Expr.Value.Int64 = readVarint64(Ctx);
177     break;
178   case wasm::WASM_OPCODE_F32_CONST:
179     Expr.Value.Float32 = readFloat32(Ctx);
180     break;
181   case wasm::WASM_OPCODE_F64_CONST:
182     Expr.Value.Float64 = readFloat64(Ctx);
183     break;
184   case wasm::WASM_OPCODE_GLOBAL_GET:
185     Expr.Value.Global = readULEB128(Ctx);
186     break;
187   case wasm::WASM_OPCODE_REF_NULL: {
188     wasm::ValType Ty = static_cast<wasm::ValType>(readULEB128(Ctx));
189     if (Ty != wasm::ValType::EXTERNREF) {
190       return make_error<GenericBinaryError>("Invalid type for ref.null",
191                                             object_error::parse_failed);
192     }
193     break;
194   }
195   default:
196     return make_error<GenericBinaryError>("Invalid opcode in init_expr",
197                                           object_error::parse_failed);
198   }
199 
200   uint8_t EndOpcode = readOpcode(Ctx);
201   if (EndOpcode != wasm::WASM_OPCODE_END) {
202     return make_error<GenericBinaryError>("Invalid init_expr",
203                                           object_error::parse_failed);
204   }
205   return Error::success();
206 }
207 
208 static wasm::WasmLimits readLimits(WasmObjectFile::ReadContext &Ctx) {
209   wasm::WasmLimits Result;
210   Result.Flags = readVaruint32(Ctx);
211   Result.Initial = readVaruint64(Ctx);
212   if (Result.Flags & wasm::WASM_LIMITS_FLAG_HAS_MAX)
213     Result.Maximum = readVaruint64(Ctx);
214   return Result;
215 }
216 
217 static wasm::WasmTableType readTableType(WasmObjectFile::ReadContext &Ctx) {
218   wasm::WasmTableType TableType;
219   TableType.ElemType = readUint8(Ctx);
220   TableType.Limits = readLimits(Ctx);
221   return TableType;
222 }
223 
224 static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
225                          WasmSectionOrderChecker &Checker) {
226   Section.Offset = Ctx.Ptr - Ctx.Start;
227   Section.Type = readUint8(Ctx);
228   LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
229   uint32_t Size = readVaruint32(Ctx);
230   if (Size == 0)
231     return make_error<StringError>("Zero length section",
232                                    object_error::parse_failed);
233   if (Ctx.Ptr + Size > Ctx.End)
234     return make_error<StringError>("Section too large",
235                                    object_error::parse_failed);
236   if (Section.Type == wasm::WASM_SEC_CUSTOM) {
237     WasmObjectFile::ReadContext SectionCtx;
238     SectionCtx.Start = Ctx.Ptr;
239     SectionCtx.Ptr = Ctx.Ptr;
240     SectionCtx.End = Ctx.Ptr + Size;
241 
242     Section.Name = readString(SectionCtx);
243 
244     uint32_t SectionNameSize = SectionCtx.Ptr - SectionCtx.Start;
245     Ctx.Ptr += SectionNameSize;
246     Size -= SectionNameSize;
247   }
248 
249   if (!Checker.isValidSectionOrder(Section.Type, Section.Name)) {
250     return make_error<StringError>("Out of order section type: " +
251                                        llvm::to_string(Section.Type),
252                                    object_error::parse_failed);
253   }
254 
255   Section.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
256   Ctx.Ptr += Size;
257   return Error::success();
258 }
259 
260 WasmObjectFile::WasmObjectFile(MemoryBufferRef Buffer, Error &Err)
261     : ObjectFile(Binary::ID_Wasm, Buffer) {
262   ErrorAsOutParameter ErrAsOutParam(&Err);
263   Header.Magic = getData().substr(0, 4);
264   if (Header.Magic != StringRef("\0asm", 4)) {
265     Err =
266         make_error<StringError>("Bad magic number", object_error::parse_failed);
267     return;
268   }
269 
270   ReadContext Ctx;
271   Ctx.Start = getData().bytes_begin();
272   Ctx.Ptr = Ctx.Start + 4;
273   Ctx.End = Ctx.Start + getData().size();
274 
275   if (Ctx.Ptr + 4 > Ctx.End) {
276     Err = make_error<StringError>("Missing version number",
277                                   object_error::parse_failed);
278     return;
279   }
280 
281   Header.Version = readUint32(Ctx);
282   if (Header.Version != wasm::WasmVersion) {
283     Err = make_error<StringError>("Bad version number",
284                                   object_error::parse_failed);
285     return;
286   }
287 
288   WasmSection Sec;
289   WasmSectionOrderChecker Checker;
290   while (Ctx.Ptr < Ctx.End) {
291     if ((Err = readSection(Sec, Ctx, Checker)))
292       return;
293     if ((Err = parseSection(Sec)))
294       return;
295 
296     Sections.push_back(Sec);
297   }
298 }
299 
300 Error WasmObjectFile::parseSection(WasmSection &Sec) {
301   ReadContext Ctx;
302   Ctx.Start = Sec.Content.data();
303   Ctx.End = Ctx.Start + Sec.Content.size();
304   Ctx.Ptr = Ctx.Start;
305   switch (Sec.Type) {
306   case wasm::WASM_SEC_CUSTOM:
307     return parseCustomSection(Sec, Ctx);
308   case wasm::WASM_SEC_TYPE:
309     return parseTypeSection(Ctx);
310   case wasm::WASM_SEC_IMPORT:
311     return parseImportSection(Ctx);
312   case wasm::WASM_SEC_FUNCTION:
313     return parseFunctionSection(Ctx);
314   case wasm::WASM_SEC_TABLE:
315     return parseTableSection(Ctx);
316   case wasm::WASM_SEC_MEMORY:
317     return parseMemorySection(Ctx);
318   case wasm::WASM_SEC_EVENT:
319     return parseEventSection(Ctx);
320   case wasm::WASM_SEC_GLOBAL:
321     return parseGlobalSection(Ctx);
322   case wasm::WASM_SEC_EXPORT:
323     return parseExportSection(Ctx);
324   case wasm::WASM_SEC_START:
325     return parseStartSection(Ctx);
326   case wasm::WASM_SEC_ELEM:
327     return parseElemSection(Ctx);
328   case wasm::WASM_SEC_CODE:
329     return parseCodeSection(Ctx);
330   case wasm::WASM_SEC_DATA:
331     return parseDataSection(Ctx);
332   case wasm::WASM_SEC_DATACOUNT:
333     return parseDataCountSection(Ctx);
334   default:
335     return make_error<GenericBinaryError>(
336         "Invalid section type: " + Twine(Sec.Type), object_error::parse_failed);
337   }
338 }
339 
340 Error WasmObjectFile::parseDylinkSection(ReadContext &Ctx) {
341   // See https://github.com/WebAssembly/tool-conventions/blob/master/DynamicLinking.md
342   HasDylinkSection = true;
343   DylinkInfo.MemorySize = readVaruint32(Ctx);
344   DylinkInfo.MemoryAlignment = readVaruint32(Ctx);
345   DylinkInfo.TableSize = readVaruint32(Ctx);
346   DylinkInfo.TableAlignment = readVaruint32(Ctx);
347   uint32_t Count = readVaruint32(Ctx);
348   while (Count--) {
349     DylinkInfo.Needed.push_back(readString(Ctx));
350   }
351   if (Ctx.Ptr != Ctx.End)
352     return make_error<GenericBinaryError>("dylink section ended prematurely",
353                                           object_error::parse_failed);
354   return Error::success();
355 }
356 
357 Error WasmObjectFile::parseNameSection(ReadContext &Ctx) {
358   llvm::DenseSet<uint64_t> SeenFunctions;
359   llvm::DenseSet<uint64_t> SeenGlobals;
360   llvm::DenseSet<uint64_t> SeenSegments;
361   if (FunctionTypes.size() && !SeenCodeSection) {
362     return make_error<GenericBinaryError>("Names must come after code section",
363                                           object_error::parse_failed);
364   }
365 
366   while (Ctx.Ptr < Ctx.End) {
367     uint8_t Type = readUint8(Ctx);
368     uint32_t Size = readVaruint32(Ctx);
369     const uint8_t *SubSectionEnd = Ctx.Ptr + Size;
370     switch (Type) {
371     case wasm::WASM_NAMES_FUNCTION:
372     case wasm::WASM_NAMES_GLOBAL:
373     case wasm::WASM_NAMES_DATA_SEGMENT: {
374       uint32_t Count = readVaruint32(Ctx);
375       while (Count--) {
376         uint32_t Index = readVaruint32(Ctx);
377         StringRef Name = readString(Ctx);
378         wasm::NameType nameType = wasm::NameType::FUNCTION;
379         if (Type == wasm::WASM_NAMES_FUNCTION) {
380           if (!SeenFunctions.insert(Index).second)
381             return make_error<GenericBinaryError>(
382                 "Function named more than once", object_error::parse_failed);
383           if (!isValidFunctionIndex(Index) || Name.empty())
384             return make_error<GenericBinaryError>("Invalid name entry",
385                                                   object_error::parse_failed);
386 
387           if (isDefinedFunctionIndex(Index))
388             getDefinedFunction(Index).DebugName = Name;
389         } else if (Type == wasm::WASM_NAMES_GLOBAL) {
390           nameType = wasm::NameType::GLOBAL;
391           if (!SeenGlobals.insert(Index).second)
392             return make_error<GenericBinaryError>("Global named more than once",
393                                                   object_error::parse_failed);
394           if (!isValidGlobalIndex(Index) || Name.empty())
395             return make_error<GenericBinaryError>("Invalid name entry",
396                                                   object_error::parse_failed);
397         } else {
398           nameType = wasm::NameType::DATA_SEGMENT;
399           if (!SeenSegments.insert(Index).second)
400             return make_error<GenericBinaryError>(
401                 "Segment named more than once", object_error::parse_failed);
402           if (Index > DataSegments.size())
403             return make_error<GenericBinaryError>("Invalid named data segment",
404                                                   object_error::parse_failed);
405         }
406         DebugNames.push_back(wasm::WasmDebugName{nameType, Index, Name});
407       }
408       break;
409     }
410     // Ignore local names for now
411     case wasm::WASM_NAMES_LOCAL:
412     default:
413       Ctx.Ptr += Size;
414       break;
415     }
416     if (Ctx.Ptr != SubSectionEnd)
417       return make_error<GenericBinaryError>(
418           "Name sub-section ended prematurely", object_error::parse_failed);
419   }
420 
421   if (Ctx.Ptr != Ctx.End)
422     return make_error<GenericBinaryError>("Name section ended prematurely",
423                                           object_error::parse_failed);
424   return Error::success();
425 }
426 
427 Error WasmObjectFile::parseLinkingSection(ReadContext &Ctx) {
428   HasLinkingSection = true;
429   if (FunctionTypes.size() && !SeenCodeSection) {
430     return make_error<GenericBinaryError>(
431         "Linking data must come after code section",
432         object_error::parse_failed);
433   }
434 
435   LinkingData.Version = readVaruint32(Ctx);
436   if (LinkingData.Version != wasm::WasmMetadataVersion) {
437     return make_error<GenericBinaryError>(
438         "Unexpected metadata version: " + Twine(LinkingData.Version) +
439             " (Expected: " + Twine(wasm::WasmMetadataVersion) + ")",
440         object_error::parse_failed);
441   }
442 
443   const uint8_t *OrigEnd = Ctx.End;
444   while (Ctx.Ptr < OrigEnd) {
445     Ctx.End = OrigEnd;
446     uint8_t Type = readUint8(Ctx);
447     uint32_t Size = readVaruint32(Ctx);
448     LLVM_DEBUG(dbgs() << "readSubsection type=" << int(Type) << " size=" << Size
449                       << "\n");
450     Ctx.End = Ctx.Ptr + Size;
451     switch (Type) {
452     case wasm::WASM_SYMBOL_TABLE:
453       if (Error Err = parseLinkingSectionSymtab(Ctx))
454         return Err;
455       break;
456     case wasm::WASM_SEGMENT_INFO: {
457       uint32_t Count = readVaruint32(Ctx);
458       if (Count > DataSegments.size())
459         return make_error<GenericBinaryError>("Too many segment names",
460                                               object_error::parse_failed);
461       for (uint32_t I = 0; I < Count; I++) {
462         DataSegments[I].Data.Name = readString(Ctx);
463         DataSegments[I].Data.Alignment = readVaruint32(Ctx);
464         DataSegments[I].Data.LinkerFlags = readVaruint32(Ctx);
465       }
466       break;
467     }
468     case wasm::WASM_INIT_FUNCS: {
469       uint32_t Count = readVaruint32(Ctx);
470       LinkingData.InitFunctions.reserve(Count);
471       for (uint32_t I = 0; I < Count; I++) {
472         wasm::WasmInitFunc Init;
473         Init.Priority = readVaruint32(Ctx);
474         Init.Symbol = readVaruint32(Ctx);
475         if (!isValidFunctionSymbol(Init.Symbol))
476           return make_error<GenericBinaryError>("Invalid function symbol: " +
477                                                     Twine(Init.Symbol),
478                                                 object_error::parse_failed);
479         LinkingData.InitFunctions.emplace_back(Init);
480       }
481       break;
482     }
483     case wasm::WASM_COMDAT_INFO:
484       if (Error Err = parseLinkingSectionComdat(Ctx))
485         return Err;
486       break;
487     default:
488       Ctx.Ptr += Size;
489       break;
490     }
491     if (Ctx.Ptr != Ctx.End)
492       return make_error<GenericBinaryError>(
493           "Linking sub-section ended prematurely", object_error::parse_failed);
494   }
495   if (Ctx.Ptr != OrigEnd)
496     return make_error<GenericBinaryError>("Linking section ended prematurely",
497                                           object_error::parse_failed);
498   return Error::success();
499 }
500 
501 Error WasmObjectFile::parseLinkingSectionSymtab(ReadContext &Ctx) {
502   uint32_t Count = readVaruint32(Ctx);
503   LinkingData.SymbolTable.reserve(Count);
504   Symbols.reserve(Count);
505   StringSet<> SymbolNames;
506 
507   std::vector<wasm::WasmImport *> ImportedGlobals;
508   std::vector<wasm::WasmImport *> ImportedFunctions;
509   std::vector<wasm::WasmImport *> ImportedEvents;
510   std::vector<wasm::WasmImport *> ImportedTables;
511   ImportedGlobals.reserve(Imports.size());
512   ImportedFunctions.reserve(Imports.size());
513   ImportedEvents.reserve(Imports.size());
514   ImportedTables.reserve(Imports.size());
515   for (auto &I : Imports) {
516     if (I.Kind == wasm::WASM_EXTERNAL_FUNCTION)
517       ImportedFunctions.emplace_back(&I);
518     else if (I.Kind == wasm::WASM_EXTERNAL_GLOBAL)
519       ImportedGlobals.emplace_back(&I);
520     else if (I.Kind == wasm::WASM_EXTERNAL_EVENT)
521       ImportedEvents.emplace_back(&I);
522     else if (I.Kind == wasm::WASM_EXTERNAL_TABLE)
523       ImportedTables.emplace_back(&I);
524   }
525 
526   while (Count--) {
527     wasm::WasmSymbolInfo Info;
528     const wasm::WasmSignature *Signature = nullptr;
529     const wasm::WasmGlobalType *GlobalType = nullptr;
530     const wasm::WasmTableType *TableType = nullptr;
531     const wasm::WasmEventType *EventType = nullptr;
532 
533     Info.Kind = readUint8(Ctx);
534     Info.Flags = readVaruint32(Ctx);
535     bool IsDefined = (Info.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0;
536 
537     switch (Info.Kind) {
538     case wasm::WASM_SYMBOL_TYPE_FUNCTION:
539       Info.ElementIndex = readVaruint32(Ctx);
540       if (!isValidFunctionIndex(Info.ElementIndex) ||
541           IsDefined != isDefinedFunctionIndex(Info.ElementIndex))
542         return make_error<GenericBinaryError>("invalid function symbol index",
543                                               object_error::parse_failed);
544       if (IsDefined) {
545         Info.Name = readString(Ctx);
546         unsigned FuncIndex = Info.ElementIndex - NumImportedFunctions;
547         Signature = &Signatures[FunctionTypes[FuncIndex]];
548         wasm::WasmFunction &Function = Functions[FuncIndex];
549         if (Function.SymbolName.empty())
550           Function.SymbolName = Info.Name;
551       } else {
552         wasm::WasmImport &Import = *ImportedFunctions[Info.ElementIndex];
553         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
554           Info.Name = readString(Ctx);
555           Info.ImportName = Import.Field;
556         } else {
557           Info.Name = Import.Field;
558         }
559         Signature = &Signatures[Import.SigIndex];
560         if (!Import.Module.empty()) {
561           Info.ImportModule = Import.Module;
562         }
563       }
564       break;
565 
566     case wasm::WASM_SYMBOL_TYPE_GLOBAL:
567       Info.ElementIndex = readVaruint32(Ctx);
568       if (!isValidGlobalIndex(Info.ElementIndex) ||
569           IsDefined != isDefinedGlobalIndex(Info.ElementIndex))
570         return make_error<GenericBinaryError>("invalid global symbol index",
571                                               object_error::parse_failed);
572       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
573                             wasm::WASM_SYMBOL_BINDING_WEAK)
574         return make_error<GenericBinaryError>("undefined weak global symbol",
575                                               object_error::parse_failed);
576       if (IsDefined) {
577         Info.Name = readString(Ctx);
578         unsigned GlobalIndex = Info.ElementIndex - NumImportedGlobals;
579         wasm::WasmGlobal &Global = Globals[GlobalIndex];
580         GlobalType = &Global.Type;
581         if (Global.SymbolName.empty())
582           Global.SymbolName = Info.Name;
583       } else {
584         wasm::WasmImport &Import = *ImportedGlobals[Info.ElementIndex];
585         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
586           Info.Name = readString(Ctx);
587           Info.ImportName = Import.Field;
588         } else {
589           Info.Name = Import.Field;
590         }
591         GlobalType = &Import.Global;
592         if (!Import.Module.empty()) {
593           Info.ImportModule = Import.Module;
594         }
595       }
596       break;
597 
598     case wasm::WASM_SYMBOL_TYPE_TABLE:
599       Info.ElementIndex = readVaruint32(Ctx);
600       if (!isValidTableIndex(Info.ElementIndex) ||
601           IsDefined != isDefinedTableIndex(Info.ElementIndex))
602         return make_error<GenericBinaryError>("invalid table symbol index",
603                                               object_error::parse_failed);
604       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
605                             wasm::WASM_SYMBOL_BINDING_WEAK)
606         return make_error<GenericBinaryError>("undefined weak table symbol",
607                                               object_error::parse_failed);
608       if (IsDefined) {
609         Info.Name = readString(Ctx);
610         unsigned TableIndex = Info.ElementIndex - NumImportedTables;
611         wasm::WasmTable &Table = Tables[TableIndex];
612         TableType = &Table.Type;
613         if (Table.SymbolName.empty())
614           Table.SymbolName = Info.Name;
615       } else {
616         wasm::WasmImport &Import = *ImportedTables[Info.ElementIndex];
617         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
618           Info.Name = readString(Ctx);
619           Info.ImportName = Import.Field;
620         } else {
621           Info.Name = Import.Field;
622         }
623         TableType = &Import.Table;
624         if (!Import.Module.empty()) {
625           Info.ImportModule = Import.Module;
626         }
627       }
628       break;
629 
630     case wasm::WASM_SYMBOL_TYPE_DATA:
631       Info.Name = readString(Ctx);
632       if (IsDefined) {
633         auto Index = readVaruint32(Ctx);
634         if (Index >= DataSegments.size())
635           return make_error<GenericBinaryError>("invalid data symbol index",
636                                                 object_error::parse_failed);
637         auto Offset = readVaruint64(Ctx);
638         auto Size = readVaruint64(Ctx);
639         if (Offset + Size > DataSegments[Index].Data.Content.size())
640           return make_error<GenericBinaryError>("invalid data symbol offset",
641                                                 object_error::parse_failed);
642         Info.DataRef = wasm::WasmDataReference{Index, Offset, Size};
643       }
644       break;
645 
646     case wasm::WASM_SYMBOL_TYPE_SECTION: {
647       if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
648           wasm::WASM_SYMBOL_BINDING_LOCAL)
649         return make_error<GenericBinaryError>(
650             "Section symbols must have local binding",
651             object_error::parse_failed);
652       Info.ElementIndex = readVaruint32(Ctx);
653       // Use somewhat unique section name as symbol name.
654       StringRef SectionName = Sections[Info.ElementIndex].Name;
655       Info.Name = SectionName;
656       break;
657     }
658 
659     case wasm::WASM_SYMBOL_TYPE_EVENT: {
660       Info.ElementIndex = readVaruint32(Ctx);
661       if (!isValidEventIndex(Info.ElementIndex) ||
662           IsDefined != isDefinedEventIndex(Info.ElementIndex))
663         return make_error<GenericBinaryError>("invalid event symbol index",
664                                               object_error::parse_failed);
665       if (!IsDefined && (Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) ==
666                             wasm::WASM_SYMBOL_BINDING_WEAK)
667         return make_error<GenericBinaryError>("undefined weak global symbol",
668                                               object_error::parse_failed);
669       if (IsDefined) {
670         Info.Name = readString(Ctx);
671         unsigned EventIndex = Info.ElementIndex - NumImportedEvents;
672         wasm::WasmEvent &Event = Events[EventIndex];
673         Signature = &Signatures[Event.Type.SigIndex];
674         EventType = &Event.Type;
675         if (Event.SymbolName.empty())
676           Event.SymbolName = Info.Name;
677 
678       } else {
679         wasm::WasmImport &Import = *ImportedEvents[Info.ElementIndex];
680         if ((Info.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0) {
681           Info.Name = readString(Ctx);
682           Info.ImportName = Import.Field;
683         } else {
684           Info.Name = Import.Field;
685         }
686         EventType = &Import.Event;
687         Signature = &Signatures[EventType->SigIndex];
688         if (!Import.Module.empty()) {
689           Info.ImportModule = Import.Module;
690         }
691       }
692       break;
693     }
694 
695     default:
696       return make_error<GenericBinaryError>("Invalid symbol type",
697                                             object_error::parse_failed);
698     }
699 
700     if ((Info.Flags & wasm::WASM_SYMBOL_BINDING_MASK) !=
701             wasm::WASM_SYMBOL_BINDING_LOCAL &&
702         !SymbolNames.insert(Info.Name).second)
703       return make_error<GenericBinaryError>("Duplicate symbol name " +
704                                                 Twine(Info.Name),
705                                             object_error::parse_failed);
706     LinkingData.SymbolTable.emplace_back(Info);
707     Symbols.emplace_back(LinkingData.SymbolTable.back(), GlobalType, TableType,
708                          EventType, Signature);
709     LLVM_DEBUG(dbgs() << "Adding symbol: " << Symbols.back() << "\n");
710   }
711 
712   return Error::success();
713 }
714 
715 Error WasmObjectFile::parseLinkingSectionComdat(ReadContext &Ctx) {
716   uint32_t ComdatCount = readVaruint32(Ctx);
717   StringSet<> ComdatSet;
718   for (unsigned ComdatIndex = 0; ComdatIndex < ComdatCount; ++ComdatIndex) {
719     StringRef Name = readString(Ctx);
720     if (Name.empty() || !ComdatSet.insert(Name).second)
721       return make_error<GenericBinaryError>("Bad/duplicate COMDAT name " +
722                                                 Twine(Name),
723                                             object_error::parse_failed);
724     LinkingData.Comdats.emplace_back(Name);
725     uint32_t Flags = readVaruint32(Ctx);
726     if (Flags != 0)
727       return make_error<GenericBinaryError>("Unsupported COMDAT flags",
728                                             object_error::parse_failed);
729 
730     uint32_t EntryCount = readVaruint32(Ctx);
731     while (EntryCount--) {
732       unsigned Kind = readVaruint32(Ctx);
733       unsigned Index = readVaruint32(Ctx);
734       switch (Kind) {
735       default:
736         return make_error<GenericBinaryError>("Invalid COMDAT entry type",
737                                               object_error::parse_failed);
738       case wasm::WASM_COMDAT_DATA:
739         if (Index >= DataSegments.size())
740           return make_error<GenericBinaryError>(
741               "COMDAT data index out of range", object_error::parse_failed);
742         if (DataSegments[Index].Data.Comdat != UINT32_MAX)
743           return make_error<GenericBinaryError>("Data segment in two COMDATs",
744                                                 object_error::parse_failed);
745         DataSegments[Index].Data.Comdat = ComdatIndex;
746         break;
747       case wasm::WASM_COMDAT_FUNCTION:
748         if (!isDefinedFunctionIndex(Index))
749           return make_error<GenericBinaryError>(
750               "COMDAT function index out of range", object_error::parse_failed);
751         if (getDefinedFunction(Index).Comdat != UINT32_MAX)
752           return make_error<GenericBinaryError>("Function in two COMDATs",
753                                                 object_error::parse_failed);
754         getDefinedFunction(Index).Comdat = ComdatIndex;
755         break;
756       case wasm::WASM_COMDAT_SECTION:
757         if (Index >= Sections.size())
758           return make_error<GenericBinaryError>(
759               "COMDAT section index out of range", object_error::parse_failed);
760         if (Sections[Index].Type != wasm::WASM_SEC_CUSTOM)
761           return make_error<GenericBinaryError>(
762               "Non-custom section in a COMDAT", object_error::parse_failed);
763         Sections[Index].Comdat = ComdatIndex;
764         break;
765       }
766     }
767   }
768   return Error::success();
769 }
770 
771 Error WasmObjectFile::parseProducersSection(ReadContext &Ctx) {
772   llvm::SmallSet<StringRef, 3> FieldsSeen;
773   uint32_t Fields = readVaruint32(Ctx);
774   for (size_t I = 0; I < Fields; ++I) {
775     StringRef FieldName = readString(Ctx);
776     if (!FieldsSeen.insert(FieldName).second)
777       return make_error<GenericBinaryError>(
778           "Producers section does not have unique fields",
779           object_error::parse_failed);
780     std::vector<std::pair<std::string, std::string>> *ProducerVec = nullptr;
781     if (FieldName == "language") {
782       ProducerVec = &ProducerInfo.Languages;
783     } else if (FieldName == "processed-by") {
784       ProducerVec = &ProducerInfo.Tools;
785     } else if (FieldName == "sdk") {
786       ProducerVec = &ProducerInfo.SDKs;
787     } else {
788       return make_error<GenericBinaryError>(
789           "Producers section field is not named one of language, processed-by, "
790           "or sdk",
791           object_error::parse_failed);
792     }
793     uint32_t ValueCount = readVaruint32(Ctx);
794     llvm::SmallSet<StringRef, 8> ProducersSeen;
795     for (size_t J = 0; J < ValueCount; ++J) {
796       StringRef Name = readString(Ctx);
797       StringRef Version = readString(Ctx);
798       if (!ProducersSeen.insert(Name).second) {
799         return make_error<GenericBinaryError>(
800             "Producers section contains repeated producer",
801             object_error::parse_failed);
802       }
803       ProducerVec->emplace_back(std::string(Name), std::string(Version));
804     }
805   }
806   if (Ctx.Ptr != Ctx.End)
807     return make_error<GenericBinaryError>("Producers section ended prematurely",
808                                           object_error::parse_failed);
809   return Error::success();
810 }
811 
812 Error WasmObjectFile::parseTargetFeaturesSection(ReadContext &Ctx) {
813   llvm::SmallSet<std::string, 8> FeaturesSeen;
814   uint32_t FeatureCount = readVaruint32(Ctx);
815   for (size_t I = 0; I < FeatureCount; ++I) {
816     wasm::WasmFeatureEntry Feature;
817     Feature.Prefix = readUint8(Ctx);
818     switch (Feature.Prefix) {
819     case wasm::WASM_FEATURE_PREFIX_USED:
820     case wasm::WASM_FEATURE_PREFIX_REQUIRED:
821     case wasm::WASM_FEATURE_PREFIX_DISALLOWED:
822       break;
823     default:
824       return make_error<GenericBinaryError>("Unknown feature policy prefix",
825                                             object_error::parse_failed);
826     }
827     Feature.Name = std::string(readString(Ctx));
828     if (!FeaturesSeen.insert(Feature.Name).second)
829       return make_error<GenericBinaryError>(
830           "Target features section contains repeated feature \"" +
831               Feature.Name + "\"",
832           object_error::parse_failed);
833     TargetFeatures.push_back(Feature);
834   }
835   if (Ctx.Ptr != Ctx.End)
836     return make_error<GenericBinaryError>(
837         "Target features section ended prematurely",
838         object_error::parse_failed);
839   return Error::success();
840 }
841 
842 Error WasmObjectFile::parseRelocSection(StringRef Name, ReadContext &Ctx) {
843   uint32_t SectionIndex = readVaruint32(Ctx);
844   if (SectionIndex >= Sections.size())
845     return make_error<GenericBinaryError>("Invalid section index",
846                                           object_error::parse_failed);
847   WasmSection &Section = Sections[SectionIndex];
848   uint32_t RelocCount = readVaruint32(Ctx);
849   uint32_t EndOffset = Section.Content.size();
850   uint32_t PreviousOffset = 0;
851   while (RelocCount--) {
852     wasm::WasmRelocation Reloc = {};
853     Reloc.Type = readVaruint32(Ctx);
854     Reloc.Offset = readVaruint32(Ctx);
855     if (Reloc.Offset < PreviousOffset)
856       return make_error<GenericBinaryError>("Relocations not in offset order",
857                                             object_error::parse_failed);
858     PreviousOffset = Reloc.Offset;
859     Reloc.Index = readVaruint32(Ctx);
860     switch (Reloc.Type) {
861     case wasm::R_WASM_FUNCTION_INDEX_LEB:
862     case wasm::R_WASM_TABLE_INDEX_SLEB:
863     case wasm::R_WASM_TABLE_INDEX_SLEB64:
864     case wasm::R_WASM_TABLE_INDEX_I32:
865     case wasm::R_WASM_TABLE_INDEX_I64:
866     case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
867       if (!isValidFunctionSymbol(Reloc.Index))
868         return make_error<GenericBinaryError>("Bad relocation function index",
869                                               object_error::parse_failed);
870       break;
871     case wasm::R_WASM_TABLE_NUMBER_LEB:
872       if (!isValidTableSymbol(Reloc.Index))
873         return make_error<GenericBinaryError>("Bad relocation table index",
874                                               object_error::parse_failed);
875       break;
876     case wasm::R_WASM_TYPE_INDEX_LEB:
877       if (Reloc.Index >= Signatures.size())
878         return make_error<GenericBinaryError>("Bad relocation type index",
879                                               object_error::parse_failed);
880       break;
881     case wasm::R_WASM_GLOBAL_INDEX_LEB:
882       // R_WASM_GLOBAL_INDEX_LEB are can be used against function and data
883       // symbols to refer to their GOT entries.
884       if (!isValidGlobalSymbol(Reloc.Index) &&
885           !isValidDataSymbol(Reloc.Index) &&
886           !isValidFunctionSymbol(Reloc.Index))
887         return make_error<GenericBinaryError>("Bad relocation global index",
888                                               object_error::parse_failed);
889       break;
890     case wasm::R_WASM_GLOBAL_INDEX_I32:
891       if (!isValidGlobalSymbol(Reloc.Index))
892         return make_error<GenericBinaryError>("Bad relocation global index",
893                                               object_error::parse_failed);
894       break;
895     case wasm::R_WASM_EVENT_INDEX_LEB:
896       if (!isValidEventSymbol(Reloc.Index))
897         return make_error<GenericBinaryError>("Bad relocation event index",
898                                               object_error::parse_failed);
899       break;
900     case wasm::R_WASM_MEMORY_ADDR_LEB:
901     case wasm::R_WASM_MEMORY_ADDR_SLEB:
902     case wasm::R_WASM_MEMORY_ADDR_I32:
903     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
904     case wasm::R_WASM_MEMORY_ADDR_TLS_SLEB:
905       if (!isValidDataSymbol(Reloc.Index))
906         return make_error<GenericBinaryError>("Bad relocation data index",
907                                               object_error::parse_failed);
908       Reloc.Addend = readVarint32(Ctx);
909       break;
910     case wasm::R_WASM_MEMORY_ADDR_LEB64:
911     case wasm::R_WASM_MEMORY_ADDR_SLEB64:
912     case wasm::R_WASM_MEMORY_ADDR_I64:
913     case wasm::R_WASM_MEMORY_ADDR_REL_SLEB64:
914       if (!isValidDataSymbol(Reloc.Index))
915         return make_error<GenericBinaryError>("Bad relocation data index",
916                                               object_error::parse_failed);
917       Reloc.Addend = readVarint64(Ctx);
918       break;
919     case wasm::R_WASM_FUNCTION_OFFSET_I32:
920       if (!isValidFunctionSymbol(Reloc.Index))
921         return make_error<GenericBinaryError>("Bad relocation function index",
922                                               object_error::parse_failed);
923       Reloc.Addend = readVarint32(Ctx);
924       break;
925     case wasm::R_WASM_FUNCTION_OFFSET_I64:
926       if (!isValidFunctionSymbol(Reloc.Index))
927         return make_error<GenericBinaryError>("Bad relocation function index",
928                                               object_error::parse_failed);
929       Reloc.Addend = readVarint64(Ctx);
930       break;
931     case wasm::R_WASM_SECTION_OFFSET_I32:
932       if (!isValidSectionSymbol(Reloc.Index))
933         return make_error<GenericBinaryError>("Bad relocation section index",
934                                               object_error::parse_failed);
935       Reloc.Addend = readVarint32(Ctx);
936       break;
937     default:
938       return make_error<GenericBinaryError>("Bad relocation type: " +
939                                                 Twine(Reloc.Type),
940                                             object_error::parse_failed);
941     }
942 
943     // Relocations must fit inside the section, and must appear in order.  They
944     // also shouldn't overlap a function/element boundary, but we don't bother
945     // to check that.
946     uint64_t Size = 5;
947     if (Reloc.Type == wasm::R_WASM_MEMORY_ADDR_LEB64 ||
948         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_SLEB64 ||
949         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_REL_SLEB64)
950       Size = 10;
951     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I32 ||
952         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I32 ||
953         Reloc.Type == wasm::R_WASM_SECTION_OFFSET_I32 ||
954         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
955         Reloc.Type == wasm::R_WASM_GLOBAL_INDEX_I32)
956       Size = 4;
957     if (Reloc.Type == wasm::R_WASM_TABLE_INDEX_I64 ||
958         Reloc.Type == wasm::R_WASM_MEMORY_ADDR_I64 ||
959         Reloc.Type == wasm::R_WASM_FUNCTION_OFFSET_I64)
960       Size = 8;
961     if (Reloc.Offset + Size > EndOffset)
962       return make_error<GenericBinaryError>("Bad relocation offset",
963                                             object_error::parse_failed);
964 
965     Section.Relocations.push_back(Reloc);
966   }
967   if (Ctx.Ptr != Ctx.End)
968     return make_error<GenericBinaryError>("Reloc section ended prematurely",
969                                           object_error::parse_failed);
970   return Error::success();
971 }
972 
973 Error WasmObjectFile::parseCustomSection(WasmSection &Sec, ReadContext &Ctx) {
974   if (Sec.Name == "dylink") {
975     if (Error Err = parseDylinkSection(Ctx))
976       return Err;
977   } else if (Sec.Name == "name") {
978     if (Error Err = parseNameSection(Ctx))
979       return Err;
980   } else if (Sec.Name == "linking") {
981     if (Error Err = parseLinkingSection(Ctx))
982       return Err;
983   } else if (Sec.Name == "producers") {
984     if (Error Err = parseProducersSection(Ctx))
985       return Err;
986   } else if (Sec.Name == "target_features") {
987     if (Error Err = parseTargetFeaturesSection(Ctx))
988       return Err;
989   } else if (Sec.Name.startswith("reloc.")) {
990     if (Error Err = parseRelocSection(Sec.Name, Ctx))
991       return Err;
992   }
993   return Error::success();
994 }
995 
996 Error WasmObjectFile::parseTypeSection(ReadContext &Ctx) {
997   uint32_t Count = readVaruint32(Ctx);
998   Signatures.reserve(Count);
999   while (Count--) {
1000     wasm::WasmSignature Sig;
1001     uint8_t Form = readUint8(Ctx);
1002     if (Form != wasm::WASM_TYPE_FUNC) {
1003       return make_error<GenericBinaryError>("Invalid signature type",
1004                                             object_error::parse_failed);
1005     }
1006     uint32_t ParamCount = readVaruint32(Ctx);
1007     Sig.Params.reserve(ParamCount);
1008     while (ParamCount--) {
1009       uint32_t ParamType = readUint8(Ctx);
1010       Sig.Params.push_back(wasm::ValType(ParamType));
1011     }
1012     uint32_t ReturnCount = readVaruint32(Ctx);
1013     while (ReturnCount--) {
1014       uint32_t ReturnType = readUint8(Ctx);
1015       Sig.Returns.push_back(wasm::ValType(ReturnType));
1016     }
1017     Signatures.push_back(std::move(Sig));
1018   }
1019   if (Ctx.Ptr != Ctx.End)
1020     return make_error<GenericBinaryError>("Type section ended prematurely",
1021                                           object_error::parse_failed);
1022   return Error::success();
1023 }
1024 
1025 Error WasmObjectFile::parseImportSection(ReadContext &Ctx) {
1026   uint32_t Count = readVaruint32(Ctx);
1027   Imports.reserve(Count);
1028   for (uint32_t I = 0; I < Count; I++) {
1029     wasm::WasmImport Im;
1030     Im.Module = readString(Ctx);
1031     Im.Field = readString(Ctx);
1032     Im.Kind = readUint8(Ctx);
1033     switch (Im.Kind) {
1034     case wasm::WASM_EXTERNAL_FUNCTION:
1035       NumImportedFunctions++;
1036       Im.SigIndex = readVaruint32(Ctx);
1037       break;
1038     case wasm::WASM_EXTERNAL_GLOBAL:
1039       NumImportedGlobals++;
1040       Im.Global.Type = readUint8(Ctx);
1041       Im.Global.Mutable = readVaruint1(Ctx);
1042       break;
1043     case wasm::WASM_EXTERNAL_MEMORY:
1044       Im.Memory = readLimits(Ctx);
1045       if (Im.Memory.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1046         HasMemory64 = true;
1047       break;
1048     case wasm::WASM_EXTERNAL_TABLE: {
1049       Im.Table = readTableType(Ctx);
1050       NumImportedTables++;
1051       auto ElemType = Im.Table.ElemType;
1052       if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1053           ElemType != wasm::WASM_TYPE_EXTERNREF)
1054         return make_error<GenericBinaryError>("Invalid table element type",
1055                                               object_error::parse_failed);
1056       break;
1057     }
1058     case wasm::WASM_EXTERNAL_EVENT:
1059       NumImportedEvents++;
1060       Im.Event.Attribute = readVarint32(Ctx);
1061       Im.Event.SigIndex = readVarint32(Ctx);
1062       break;
1063     default:
1064       return make_error<GenericBinaryError>("Unexpected import kind",
1065                                             object_error::parse_failed);
1066     }
1067     Imports.push_back(Im);
1068   }
1069   if (Ctx.Ptr != Ctx.End)
1070     return make_error<GenericBinaryError>("Import section ended prematurely",
1071                                           object_error::parse_failed);
1072   return Error::success();
1073 }
1074 
1075 Error WasmObjectFile::parseFunctionSection(ReadContext &Ctx) {
1076   uint32_t Count = readVaruint32(Ctx);
1077   FunctionTypes.reserve(Count);
1078   Functions.resize(Count);
1079   uint32_t NumTypes = Signatures.size();
1080   while (Count--) {
1081     uint32_t Type = readVaruint32(Ctx);
1082     if (Type >= NumTypes)
1083       return make_error<GenericBinaryError>("Invalid function type",
1084                                             object_error::parse_failed);
1085     FunctionTypes.push_back(Type);
1086   }
1087   if (Ctx.Ptr != Ctx.End)
1088     return make_error<GenericBinaryError>("Function section ended prematurely",
1089                                           object_error::parse_failed);
1090   return Error::success();
1091 }
1092 
1093 Error WasmObjectFile::parseTableSection(ReadContext &Ctx) {
1094   TableSection = Sections.size();
1095   uint32_t Count = readVaruint32(Ctx);
1096   Tables.reserve(Count);
1097   while (Count--) {
1098     wasm::WasmTable T;
1099     T.Type = readTableType(Ctx);
1100     T.Index = NumImportedTables + Tables.size();
1101     Tables.push_back(T);
1102     auto ElemType = Tables.back().Type.ElemType;
1103     if (ElemType != wasm::WASM_TYPE_FUNCREF &&
1104         ElemType != wasm::WASM_TYPE_EXTERNREF) {
1105       return make_error<GenericBinaryError>("Invalid table element type",
1106                                             object_error::parse_failed);
1107     }
1108   }
1109   if (Ctx.Ptr != Ctx.End)
1110     return make_error<GenericBinaryError>("Table section ended prematurely",
1111                                           object_error::parse_failed);
1112   return Error::success();
1113 }
1114 
1115 Error WasmObjectFile::parseMemorySection(ReadContext &Ctx) {
1116   uint32_t Count = readVaruint32(Ctx);
1117   Memories.reserve(Count);
1118   while (Count--) {
1119     auto Limits = readLimits(Ctx);
1120     if (Limits.Flags & wasm::WASM_LIMITS_FLAG_IS_64)
1121       HasMemory64 = true;
1122     Memories.push_back(Limits);
1123   }
1124   if (Ctx.Ptr != Ctx.End)
1125     return make_error<GenericBinaryError>("Memory section ended prematurely",
1126                                           object_error::parse_failed);
1127   return Error::success();
1128 }
1129 
1130 Error WasmObjectFile::parseEventSection(ReadContext &Ctx) {
1131   EventSection = Sections.size();
1132   uint32_t Count = readVarint32(Ctx);
1133   Events.reserve(Count);
1134   while (Count--) {
1135     wasm::WasmEvent Event;
1136     Event.Index = NumImportedEvents + Events.size();
1137     Event.Type.Attribute = readVaruint32(Ctx);
1138     Event.Type.SigIndex = readVarint32(Ctx);
1139     Events.push_back(Event);
1140   }
1141 
1142   if (Ctx.Ptr != Ctx.End)
1143     return make_error<GenericBinaryError>("Event section ended prematurely",
1144                                           object_error::parse_failed);
1145   return Error::success();
1146 }
1147 
1148 Error WasmObjectFile::parseGlobalSection(ReadContext &Ctx) {
1149   GlobalSection = Sections.size();
1150   uint32_t Count = readVaruint32(Ctx);
1151   Globals.reserve(Count);
1152   while (Count--) {
1153     wasm::WasmGlobal Global;
1154     Global.Index = NumImportedGlobals + Globals.size();
1155     Global.Type.Type = readUint8(Ctx);
1156     Global.Type.Mutable = readVaruint1(Ctx);
1157     if (Error Err = readInitExpr(Global.InitExpr, Ctx))
1158       return Err;
1159     Globals.push_back(Global);
1160   }
1161   if (Ctx.Ptr != Ctx.End)
1162     return make_error<GenericBinaryError>("Global section ended prematurely",
1163                                           object_error::parse_failed);
1164   return Error::success();
1165 }
1166 
1167 Error WasmObjectFile::parseExportSection(ReadContext &Ctx) {
1168   uint32_t Count = readVaruint32(Ctx);
1169   Exports.reserve(Count);
1170   for (uint32_t I = 0; I < Count; I++) {
1171     wasm::WasmExport Ex;
1172     Ex.Name = readString(Ctx);
1173     Ex.Kind = readUint8(Ctx);
1174     Ex.Index = readVaruint32(Ctx);
1175     switch (Ex.Kind) {
1176     case wasm::WASM_EXTERNAL_FUNCTION:
1177 
1178       if (!isDefinedFunctionIndex(Ex.Index))
1179         return make_error<GenericBinaryError>("Invalid function export",
1180                                               object_error::parse_failed);
1181       getDefinedFunction(Ex.Index).ExportName = Ex.Name;
1182       break;
1183     case wasm::WASM_EXTERNAL_GLOBAL:
1184       if (!isValidGlobalIndex(Ex.Index))
1185         return make_error<GenericBinaryError>("Invalid global export",
1186                                               object_error::parse_failed);
1187       break;
1188     case wasm::WASM_EXTERNAL_EVENT:
1189       if (!isValidEventIndex(Ex.Index))
1190         return make_error<GenericBinaryError>("Invalid event export",
1191                                               object_error::parse_failed);
1192       break;
1193     case wasm::WASM_EXTERNAL_MEMORY:
1194     case wasm::WASM_EXTERNAL_TABLE:
1195       break;
1196     default:
1197       return make_error<GenericBinaryError>("Unexpected export kind",
1198                                             object_error::parse_failed);
1199     }
1200     Exports.push_back(Ex);
1201   }
1202   if (Ctx.Ptr != Ctx.End)
1203     return make_error<GenericBinaryError>("Export section ended prematurely",
1204                                           object_error::parse_failed);
1205   return Error::success();
1206 }
1207 
1208 bool WasmObjectFile::isValidFunctionIndex(uint32_t Index) const {
1209   return Index < NumImportedFunctions + FunctionTypes.size();
1210 }
1211 
1212 bool WasmObjectFile::isDefinedFunctionIndex(uint32_t Index) const {
1213   return Index >= NumImportedFunctions && isValidFunctionIndex(Index);
1214 }
1215 
1216 bool WasmObjectFile::isValidGlobalIndex(uint32_t Index) const {
1217   return Index < NumImportedGlobals + Globals.size();
1218 }
1219 
1220 bool WasmObjectFile::isValidTableIndex(uint32_t Index) const {
1221   return Index < NumImportedTables + Tables.size();
1222 }
1223 
1224 bool WasmObjectFile::isDefinedGlobalIndex(uint32_t Index) const {
1225   return Index >= NumImportedGlobals && isValidGlobalIndex(Index);
1226 }
1227 
1228 bool WasmObjectFile::isDefinedTableIndex(uint32_t Index) const {
1229   return Index >= NumImportedTables && isValidTableIndex(Index);
1230 }
1231 
1232 bool WasmObjectFile::isValidEventIndex(uint32_t Index) const {
1233   return Index < NumImportedEvents + Events.size();
1234 }
1235 
1236 bool WasmObjectFile::isDefinedEventIndex(uint32_t Index) const {
1237   return Index >= NumImportedEvents && isValidEventIndex(Index);
1238 }
1239 
1240 bool WasmObjectFile::isValidFunctionSymbol(uint32_t Index) const {
1241   return Index < Symbols.size() && Symbols[Index].isTypeFunction();
1242 }
1243 
1244 bool WasmObjectFile::isValidTableSymbol(uint32_t Index) const {
1245   return Index < Symbols.size() && Symbols[Index].isTypeTable();
1246 }
1247 
1248 bool WasmObjectFile::isValidGlobalSymbol(uint32_t Index) const {
1249   return Index < Symbols.size() && Symbols[Index].isTypeGlobal();
1250 }
1251 
1252 bool WasmObjectFile::isValidEventSymbol(uint32_t Index) const {
1253   return Index < Symbols.size() && Symbols[Index].isTypeEvent();
1254 }
1255 
1256 bool WasmObjectFile::isValidDataSymbol(uint32_t Index) const {
1257   return Index < Symbols.size() && Symbols[Index].isTypeData();
1258 }
1259 
1260 bool WasmObjectFile::isValidSectionSymbol(uint32_t Index) const {
1261   return Index < Symbols.size() && Symbols[Index].isTypeSection();
1262 }
1263 
1264 wasm::WasmFunction &WasmObjectFile::getDefinedFunction(uint32_t Index) {
1265   assert(isDefinedFunctionIndex(Index));
1266   return Functions[Index - NumImportedFunctions];
1267 }
1268 
1269 const wasm::WasmFunction &
1270 WasmObjectFile::getDefinedFunction(uint32_t Index) const {
1271   assert(isDefinedFunctionIndex(Index));
1272   return Functions[Index - NumImportedFunctions];
1273 }
1274 
1275 wasm::WasmGlobal &WasmObjectFile::getDefinedGlobal(uint32_t Index) {
1276   assert(isDefinedGlobalIndex(Index));
1277   return Globals[Index - NumImportedGlobals];
1278 }
1279 
1280 wasm::WasmEvent &WasmObjectFile::getDefinedEvent(uint32_t Index) {
1281   assert(isDefinedEventIndex(Index));
1282   return Events[Index - NumImportedEvents];
1283 }
1284 
1285 Error WasmObjectFile::parseStartSection(ReadContext &Ctx) {
1286   StartFunction = readVaruint32(Ctx);
1287   if (!isValidFunctionIndex(StartFunction))
1288     return make_error<GenericBinaryError>("Invalid start function",
1289                                           object_error::parse_failed);
1290   return Error::success();
1291 }
1292 
1293 Error WasmObjectFile::parseCodeSection(ReadContext &Ctx) {
1294   SeenCodeSection = true;
1295   CodeSection = Sections.size();
1296   uint32_t FunctionCount = readVaruint32(Ctx);
1297   if (FunctionCount != FunctionTypes.size()) {
1298     return make_error<GenericBinaryError>("Invalid function count",
1299                                           object_error::parse_failed);
1300   }
1301 
1302   for (uint32_t i = 0; i < FunctionCount; i++) {
1303     wasm::WasmFunction& Function = Functions[i];
1304     const uint8_t *FunctionStart = Ctx.Ptr;
1305     uint32_t Size = readVaruint32(Ctx);
1306     const uint8_t *FunctionEnd = Ctx.Ptr + Size;
1307 
1308     Function.CodeOffset = Ctx.Ptr - FunctionStart;
1309     Function.Index = NumImportedFunctions + i;
1310     Function.CodeSectionOffset = FunctionStart - Ctx.Start;
1311     Function.Size = FunctionEnd - FunctionStart;
1312 
1313     uint32_t NumLocalDecls = readVaruint32(Ctx);
1314     Function.Locals.reserve(NumLocalDecls);
1315     while (NumLocalDecls--) {
1316       wasm::WasmLocalDecl Decl;
1317       Decl.Count = readVaruint32(Ctx);
1318       Decl.Type = readUint8(Ctx);
1319       Function.Locals.push_back(Decl);
1320     }
1321 
1322     uint32_t BodySize = FunctionEnd - Ctx.Ptr;
1323     Function.Body = ArrayRef<uint8_t>(Ctx.Ptr, BodySize);
1324     // This will be set later when reading in the linking metadata section.
1325     Function.Comdat = UINT32_MAX;
1326     Ctx.Ptr += BodySize;
1327     assert(Ctx.Ptr == FunctionEnd);
1328   }
1329   if (Ctx.Ptr != Ctx.End)
1330     return make_error<GenericBinaryError>("Code section ended prematurely",
1331                                           object_error::parse_failed);
1332   return Error::success();
1333 }
1334 
1335 Error WasmObjectFile::parseElemSection(ReadContext &Ctx) {
1336   uint32_t Count = readVaruint32(Ctx);
1337   ElemSegments.reserve(Count);
1338   while (Count--) {
1339     wasm::WasmElemSegment Segment;
1340     Segment.TableIndex = readVaruint32(Ctx);
1341     if (Segment.TableIndex != 0) {
1342       return make_error<GenericBinaryError>("Invalid TableIndex",
1343                                             object_error::parse_failed);
1344     }
1345     if (Error Err = readInitExpr(Segment.Offset, Ctx))
1346       return Err;
1347     uint32_t NumElems = readVaruint32(Ctx);
1348     while (NumElems--) {
1349       Segment.Functions.push_back(readVaruint32(Ctx));
1350     }
1351     ElemSegments.push_back(Segment);
1352   }
1353   if (Ctx.Ptr != Ctx.End)
1354     return make_error<GenericBinaryError>("Elem section ended prematurely",
1355                                           object_error::parse_failed);
1356   return Error::success();
1357 }
1358 
1359 Error WasmObjectFile::parseDataSection(ReadContext &Ctx) {
1360   DataSection = Sections.size();
1361   uint32_t Count = readVaruint32(Ctx);
1362   if (DataCount && Count != DataCount.getValue())
1363     return make_error<GenericBinaryError>(
1364         "Number of data segments does not match DataCount section");
1365   DataSegments.reserve(Count);
1366   while (Count--) {
1367     WasmSegment Segment;
1368     Segment.Data.InitFlags = readVaruint32(Ctx);
1369     Segment.Data.MemoryIndex =
1370         (Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_HAS_MEMINDEX)
1371             ? readVaruint32(Ctx)
1372             : 0;
1373     if ((Segment.Data.InitFlags & wasm::WASM_DATA_SEGMENT_IS_PASSIVE) == 0) {
1374       if (Error Err = readInitExpr(Segment.Data.Offset, Ctx))
1375         return Err;
1376     } else {
1377       Segment.Data.Offset.Opcode = wasm::WASM_OPCODE_I32_CONST;
1378       Segment.Data.Offset.Value.Int32 = 0;
1379     }
1380     uint32_t Size = readVaruint32(Ctx);
1381     if (Size > (size_t)(Ctx.End - Ctx.Ptr))
1382       return make_error<GenericBinaryError>("Invalid segment size",
1383                                             object_error::parse_failed);
1384     Segment.Data.Content = ArrayRef<uint8_t>(Ctx.Ptr, Size);
1385     // The rest of these Data fields are set later, when reading in the linking
1386     // metadata section.
1387     Segment.Data.Alignment = 0;
1388     Segment.Data.LinkerFlags = 0;
1389     Segment.Data.Comdat = UINT32_MAX;
1390     Segment.SectionOffset = Ctx.Ptr - Ctx.Start;
1391     Ctx.Ptr += Size;
1392     DataSegments.push_back(Segment);
1393   }
1394   if (Ctx.Ptr != Ctx.End)
1395     return make_error<GenericBinaryError>("Data section ended prematurely",
1396                                           object_error::parse_failed);
1397   return Error::success();
1398 }
1399 
1400 Error WasmObjectFile::parseDataCountSection(ReadContext &Ctx) {
1401   DataCount = readVaruint32(Ctx);
1402   return Error::success();
1403 }
1404 
1405 const wasm::WasmObjectHeader &WasmObjectFile::getHeader() const {
1406   return Header;
1407 }
1408 
1409 void WasmObjectFile::moveSymbolNext(DataRefImpl &Symb) const { Symb.d.b++; }
1410 
1411 Expected<uint32_t> WasmObjectFile::getSymbolFlags(DataRefImpl Symb) const {
1412   uint32_t Result = SymbolRef::SF_None;
1413   const WasmSymbol &Sym = getWasmSymbol(Symb);
1414 
1415   LLVM_DEBUG(dbgs() << "getSymbolFlags: ptr=" << &Sym << " " << Sym << "\n");
1416   if (Sym.isBindingWeak())
1417     Result |= SymbolRef::SF_Weak;
1418   if (!Sym.isBindingLocal())
1419     Result |= SymbolRef::SF_Global;
1420   if (Sym.isHidden())
1421     Result |= SymbolRef::SF_Hidden;
1422   if (!Sym.isDefined())
1423     Result |= SymbolRef::SF_Undefined;
1424   if (Sym.isTypeFunction())
1425     Result |= SymbolRef::SF_Executable;
1426   return Result;
1427 }
1428 
1429 basic_symbol_iterator WasmObjectFile::symbol_begin() const {
1430   DataRefImpl Ref;
1431   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1432   Ref.d.b = 0; // Symbol index
1433   return BasicSymbolRef(Ref, this);
1434 }
1435 
1436 basic_symbol_iterator WasmObjectFile::symbol_end() const {
1437   DataRefImpl Ref;
1438   Ref.d.a = 1; // Arbitrary non-zero value so that Ref.p is non-null
1439   Ref.d.b = Symbols.size(); // Symbol index
1440   return BasicSymbolRef(Ref, this);
1441 }
1442 
1443 const WasmSymbol &WasmObjectFile::getWasmSymbol(const DataRefImpl &Symb) const {
1444   return Symbols[Symb.d.b];
1445 }
1446 
1447 const WasmSymbol &WasmObjectFile::getWasmSymbol(const SymbolRef &Symb) const {
1448   return getWasmSymbol(Symb.getRawDataRefImpl());
1449 }
1450 
1451 Expected<StringRef> WasmObjectFile::getSymbolName(DataRefImpl Symb) const {
1452   return getWasmSymbol(Symb).Info.Name;
1453 }
1454 
1455 Expected<uint64_t> WasmObjectFile::getSymbolAddress(DataRefImpl Symb) const {
1456   auto &Sym = getWasmSymbol(Symb);
1457   if (Sym.Info.Kind == wasm::WASM_SYMBOL_TYPE_FUNCTION &&
1458       isDefinedFunctionIndex(Sym.Info.ElementIndex))
1459     return getDefinedFunction(Sym.Info.ElementIndex).CodeSectionOffset;
1460   else
1461     return getSymbolValue(Symb);
1462 }
1463 
1464 uint64_t WasmObjectFile::getWasmSymbolValue(const WasmSymbol &Sym) const {
1465   switch (Sym.Info.Kind) {
1466   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1467   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1468   case wasm::WASM_SYMBOL_TYPE_EVENT:
1469   case wasm::WASM_SYMBOL_TYPE_TABLE:
1470     return Sym.Info.ElementIndex;
1471   case wasm::WASM_SYMBOL_TYPE_DATA: {
1472     // The value of a data symbol is the segment offset, plus the symbol
1473     // offset within the segment.
1474     uint32_t SegmentIndex = Sym.Info.DataRef.Segment;
1475     const wasm::WasmDataSegment &Segment = DataSegments[SegmentIndex].Data;
1476     if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I32_CONST) {
1477       return Segment.Offset.Value.Int32 + Sym.Info.DataRef.Offset;
1478     } else if (Segment.Offset.Opcode == wasm::WASM_OPCODE_I64_CONST) {
1479       return Segment.Offset.Value.Int64 + Sym.Info.DataRef.Offset;
1480     } else {
1481       llvm_unreachable("unknown init expr opcode");
1482     }
1483   }
1484   case wasm::WASM_SYMBOL_TYPE_SECTION:
1485     return 0;
1486   }
1487   llvm_unreachable("invalid symbol type");
1488 }
1489 
1490 uint64_t WasmObjectFile::getSymbolValueImpl(DataRefImpl Symb) const {
1491   return getWasmSymbolValue(getWasmSymbol(Symb));
1492 }
1493 
1494 uint32_t WasmObjectFile::getSymbolAlignment(DataRefImpl Symb) const {
1495   llvm_unreachable("not yet implemented");
1496   return 0;
1497 }
1498 
1499 uint64_t WasmObjectFile::getCommonSymbolSizeImpl(DataRefImpl Symb) const {
1500   llvm_unreachable("not yet implemented");
1501   return 0;
1502 }
1503 
1504 Expected<SymbolRef::Type>
1505 WasmObjectFile::getSymbolType(DataRefImpl Symb) const {
1506   const WasmSymbol &Sym = getWasmSymbol(Symb);
1507 
1508   switch (Sym.Info.Kind) {
1509   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1510     return SymbolRef::ST_Function;
1511   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1512     return SymbolRef::ST_Other;
1513   case wasm::WASM_SYMBOL_TYPE_DATA:
1514     return SymbolRef::ST_Data;
1515   case wasm::WASM_SYMBOL_TYPE_SECTION:
1516     return SymbolRef::ST_Debug;
1517   case wasm::WASM_SYMBOL_TYPE_EVENT:
1518     return SymbolRef::ST_Other;
1519   case wasm::WASM_SYMBOL_TYPE_TABLE:
1520     return SymbolRef::ST_Other;
1521   }
1522 
1523   llvm_unreachable("Unknown WasmSymbol::SymbolType");
1524   return SymbolRef::ST_Other;
1525 }
1526 
1527 Expected<section_iterator>
1528 WasmObjectFile::getSymbolSection(DataRefImpl Symb) const {
1529   const WasmSymbol &Sym = getWasmSymbol(Symb);
1530   if (Sym.isUndefined())
1531     return section_end();
1532 
1533   DataRefImpl Ref;
1534   Ref.d.a = getSymbolSectionIdImpl(Sym);
1535   return section_iterator(SectionRef(Ref, this));
1536 }
1537 
1538 uint32_t WasmObjectFile::getSymbolSectionId(SymbolRef Symb) const {
1539   const WasmSymbol &Sym = getWasmSymbol(Symb);
1540   return getSymbolSectionIdImpl(Sym);
1541 }
1542 
1543 uint32_t WasmObjectFile::getSymbolSectionIdImpl(const WasmSymbol &Sym) const {
1544   switch (Sym.Info.Kind) {
1545   case wasm::WASM_SYMBOL_TYPE_FUNCTION:
1546     return CodeSection;
1547   case wasm::WASM_SYMBOL_TYPE_GLOBAL:
1548     return GlobalSection;
1549   case wasm::WASM_SYMBOL_TYPE_DATA:
1550     return DataSection;
1551   case wasm::WASM_SYMBOL_TYPE_SECTION:
1552     return Sym.Info.ElementIndex;
1553   case wasm::WASM_SYMBOL_TYPE_EVENT:
1554     return EventSection;
1555   case wasm::WASM_SYMBOL_TYPE_TABLE:
1556     return TableSection;
1557   default:
1558     llvm_unreachable("Unknown WasmSymbol::SymbolType");
1559   }
1560 }
1561 
1562 void WasmObjectFile::moveSectionNext(DataRefImpl &Sec) const { Sec.d.a++; }
1563 
1564 Expected<StringRef> WasmObjectFile::getSectionName(DataRefImpl Sec) const {
1565   const WasmSection &S = Sections[Sec.d.a];
1566 #define ECase(X)                                                               \
1567   case wasm::WASM_SEC_##X:                                                     \
1568     return #X;
1569   switch (S.Type) {
1570     ECase(TYPE);
1571     ECase(IMPORT);
1572     ECase(FUNCTION);
1573     ECase(TABLE);
1574     ECase(MEMORY);
1575     ECase(GLOBAL);
1576     ECase(EVENT);
1577     ECase(EXPORT);
1578     ECase(START);
1579     ECase(ELEM);
1580     ECase(CODE);
1581     ECase(DATA);
1582     ECase(DATACOUNT);
1583   case wasm::WASM_SEC_CUSTOM:
1584     return S.Name;
1585   default:
1586     return createStringError(object_error::invalid_section_index, "");
1587   }
1588 #undef ECase
1589 }
1590 
1591 uint64_t WasmObjectFile::getSectionAddress(DataRefImpl Sec) const { return 0; }
1592 
1593 uint64_t WasmObjectFile::getSectionIndex(DataRefImpl Sec) const {
1594   return Sec.d.a;
1595 }
1596 
1597 uint64_t WasmObjectFile::getSectionSize(DataRefImpl Sec) const {
1598   const WasmSection &S = Sections[Sec.d.a];
1599   return S.Content.size();
1600 }
1601 
1602 Expected<ArrayRef<uint8_t>>
1603 WasmObjectFile::getSectionContents(DataRefImpl Sec) const {
1604   const WasmSection &S = Sections[Sec.d.a];
1605   // This will never fail since wasm sections can never be empty (user-sections
1606   // must have a name and non-user sections each have a defined structure).
1607   return S.Content;
1608 }
1609 
1610 uint64_t WasmObjectFile::getSectionAlignment(DataRefImpl Sec) const {
1611   return 1;
1612 }
1613 
1614 bool WasmObjectFile::isSectionCompressed(DataRefImpl Sec) const {
1615   return false;
1616 }
1617 
1618 bool WasmObjectFile::isSectionText(DataRefImpl Sec) const {
1619   return getWasmSection(Sec).Type == wasm::WASM_SEC_CODE;
1620 }
1621 
1622 bool WasmObjectFile::isSectionData(DataRefImpl Sec) const {
1623   return getWasmSection(Sec).Type == wasm::WASM_SEC_DATA;
1624 }
1625 
1626 bool WasmObjectFile::isSectionBSS(DataRefImpl Sec) const { return false; }
1627 
1628 bool WasmObjectFile::isSectionVirtual(DataRefImpl Sec) const { return false; }
1629 
1630 relocation_iterator WasmObjectFile::section_rel_begin(DataRefImpl Ref) const {
1631   DataRefImpl RelocRef;
1632   RelocRef.d.a = Ref.d.a;
1633   RelocRef.d.b = 0;
1634   return relocation_iterator(RelocationRef(RelocRef, this));
1635 }
1636 
1637 relocation_iterator WasmObjectFile::section_rel_end(DataRefImpl Ref) const {
1638   const WasmSection &Sec = getWasmSection(Ref);
1639   DataRefImpl RelocRef;
1640   RelocRef.d.a = Ref.d.a;
1641   RelocRef.d.b = Sec.Relocations.size();
1642   return relocation_iterator(RelocationRef(RelocRef, this));
1643 }
1644 
1645 void WasmObjectFile::moveRelocationNext(DataRefImpl &Rel) const { Rel.d.b++; }
1646 
1647 uint64_t WasmObjectFile::getRelocationOffset(DataRefImpl Ref) const {
1648   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1649   return Rel.Offset;
1650 }
1651 
1652 symbol_iterator WasmObjectFile::getRelocationSymbol(DataRefImpl Ref) const {
1653   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1654   if (Rel.Type == wasm::R_WASM_TYPE_INDEX_LEB)
1655     return symbol_end();
1656   DataRefImpl Sym;
1657   Sym.d.a = 1;
1658   Sym.d.b = Rel.Index;
1659   return symbol_iterator(SymbolRef(Sym, this));
1660 }
1661 
1662 uint64_t WasmObjectFile::getRelocationType(DataRefImpl Ref) const {
1663   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1664   return Rel.Type;
1665 }
1666 
1667 void WasmObjectFile::getRelocationTypeName(
1668     DataRefImpl Ref, SmallVectorImpl<char> &Result) const {
1669   const wasm::WasmRelocation &Rel = getWasmRelocation(Ref);
1670   StringRef Res = "Unknown";
1671 
1672 #define WASM_RELOC(name, value)                                                \
1673   case wasm::name:                                                             \
1674     Res = #name;                                                               \
1675     break;
1676 
1677   switch (Rel.Type) {
1678 #include "llvm/BinaryFormat/WasmRelocs.def"
1679   }
1680 
1681 #undef WASM_RELOC
1682 
1683   Result.append(Res.begin(), Res.end());
1684 }
1685 
1686 section_iterator WasmObjectFile::section_begin() const {
1687   DataRefImpl Ref;
1688   Ref.d.a = 0;
1689   return section_iterator(SectionRef(Ref, this));
1690 }
1691 
1692 section_iterator WasmObjectFile::section_end() const {
1693   DataRefImpl Ref;
1694   Ref.d.a = Sections.size();
1695   return section_iterator(SectionRef(Ref, this));
1696 }
1697 
1698 uint8_t WasmObjectFile::getBytesInAddress() const {
1699   return HasMemory64 ? 8 : 4;
1700 }
1701 
1702 StringRef WasmObjectFile::getFileFormatName() const { return "WASM"; }
1703 
1704 Triple::ArchType WasmObjectFile::getArch() const {
1705   return HasMemory64 ? Triple::wasm64 : Triple::wasm32;
1706 }
1707 
1708 SubtargetFeatures WasmObjectFile::getFeatures() const {
1709   return SubtargetFeatures();
1710 }
1711 
1712 bool WasmObjectFile::isRelocatableObject() const { return HasLinkingSection; }
1713 
1714 bool WasmObjectFile::isSharedObject() const { return HasDylinkSection; }
1715 
1716 const WasmSection &WasmObjectFile::getWasmSection(DataRefImpl Ref) const {
1717   assert(Ref.d.a < Sections.size());
1718   return Sections[Ref.d.a];
1719 }
1720 
1721 const WasmSection &
1722 WasmObjectFile::getWasmSection(const SectionRef &Section) const {
1723   return getWasmSection(Section.getRawDataRefImpl());
1724 }
1725 
1726 const wasm::WasmRelocation &
1727 WasmObjectFile::getWasmRelocation(const RelocationRef &Ref) const {
1728   return getWasmRelocation(Ref.getRawDataRefImpl());
1729 }
1730 
1731 const wasm::WasmRelocation &
1732 WasmObjectFile::getWasmRelocation(DataRefImpl Ref) const {
1733   assert(Ref.d.a < Sections.size());
1734   const WasmSection &Sec = Sections[Ref.d.a];
1735   assert(Ref.d.b < Sec.Relocations.size());
1736   return Sec.Relocations[Ref.d.b];
1737 }
1738 
1739 int WasmSectionOrderChecker::getSectionOrder(unsigned ID,
1740                                              StringRef CustomSectionName) {
1741   switch (ID) {
1742   case wasm::WASM_SEC_CUSTOM:
1743     return StringSwitch<unsigned>(CustomSectionName)
1744         .Case("dylink", WASM_SEC_ORDER_DYLINK)
1745         .Case("linking", WASM_SEC_ORDER_LINKING)
1746         .StartsWith("reloc.", WASM_SEC_ORDER_RELOC)
1747         .Case("name", WASM_SEC_ORDER_NAME)
1748         .Case("producers", WASM_SEC_ORDER_PRODUCERS)
1749         .Case("target_features", WASM_SEC_ORDER_TARGET_FEATURES)
1750         .Default(WASM_SEC_ORDER_NONE);
1751   case wasm::WASM_SEC_TYPE:
1752     return WASM_SEC_ORDER_TYPE;
1753   case wasm::WASM_SEC_IMPORT:
1754     return WASM_SEC_ORDER_IMPORT;
1755   case wasm::WASM_SEC_FUNCTION:
1756     return WASM_SEC_ORDER_FUNCTION;
1757   case wasm::WASM_SEC_TABLE:
1758     return WASM_SEC_ORDER_TABLE;
1759   case wasm::WASM_SEC_MEMORY:
1760     return WASM_SEC_ORDER_MEMORY;
1761   case wasm::WASM_SEC_GLOBAL:
1762     return WASM_SEC_ORDER_GLOBAL;
1763   case wasm::WASM_SEC_EXPORT:
1764     return WASM_SEC_ORDER_EXPORT;
1765   case wasm::WASM_SEC_START:
1766     return WASM_SEC_ORDER_START;
1767   case wasm::WASM_SEC_ELEM:
1768     return WASM_SEC_ORDER_ELEM;
1769   case wasm::WASM_SEC_CODE:
1770     return WASM_SEC_ORDER_CODE;
1771   case wasm::WASM_SEC_DATA:
1772     return WASM_SEC_ORDER_DATA;
1773   case wasm::WASM_SEC_DATACOUNT:
1774     return WASM_SEC_ORDER_DATACOUNT;
1775   case wasm::WASM_SEC_EVENT:
1776     return WASM_SEC_ORDER_EVENT;
1777   default:
1778     return WASM_SEC_ORDER_NONE;
1779   }
1780 }
1781 
1782 // Represents the edges in a directed graph where any node B reachable from node
1783 // A is not allowed to appear before A in the section ordering, but may appear
1784 // afterward.
1785 int WasmSectionOrderChecker::DisallowedPredecessors
1786     [WASM_NUM_SEC_ORDERS][WASM_NUM_SEC_ORDERS] = {
1787         // WASM_SEC_ORDER_NONE
1788         {},
1789         // WASM_SEC_ORDER_TYPE
1790         {WASM_SEC_ORDER_TYPE, WASM_SEC_ORDER_IMPORT},
1791         // WASM_SEC_ORDER_IMPORT
1792         {WASM_SEC_ORDER_IMPORT, WASM_SEC_ORDER_FUNCTION},
1793         // WASM_SEC_ORDER_FUNCTION
1794         {WASM_SEC_ORDER_FUNCTION, WASM_SEC_ORDER_TABLE},
1795         // WASM_SEC_ORDER_TABLE
1796         {WASM_SEC_ORDER_TABLE, WASM_SEC_ORDER_MEMORY},
1797         // WASM_SEC_ORDER_MEMORY
1798         {WASM_SEC_ORDER_MEMORY, WASM_SEC_ORDER_EVENT},
1799         // WASM_SEC_ORDER_EVENT
1800         {WASM_SEC_ORDER_EVENT, WASM_SEC_ORDER_GLOBAL},
1801         // WASM_SEC_ORDER_GLOBAL
1802         {WASM_SEC_ORDER_GLOBAL, WASM_SEC_ORDER_EXPORT},
1803         // WASM_SEC_ORDER_EXPORT
1804         {WASM_SEC_ORDER_EXPORT, WASM_SEC_ORDER_START},
1805         // WASM_SEC_ORDER_START
1806         {WASM_SEC_ORDER_START, WASM_SEC_ORDER_ELEM},
1807         // WASM_SEC_ORDER_ELEM
1808         {WASM_SEC_ORDER_ELEM, WASM_SEC_ORDER_DATACOUNT},
1809         // WASM_SEC_ORDER_DATACOUNT
1810         {WASM_SEC_ORDER_DATACOUNT, WASM_SEC_ORDER_CODE},
1811         // WASM_SEC_ORDER_CODE
1812         {WASM_SEC_ORDER_CODE, WASM_SEC_ORDER_DATA},
1813         // WASM_SEC_ORDER_DATA
1814         {WASM_SEC_ORDER_DATA, WASM_SEC_ORDER_LINKING},
1815 
1816         // Custom Sections
1817         // WASM_SEC_ORDER_DYLINK
1818         {WASM_SEC_ORDER_DYLINK, WASM_SEC_ORDER_TYPE},
1819         // WASM_SEC_ORDER_LINKING
1820         {WASM_SEC_ORDER_LINKING, WASM_SEC_ORDER_RELOC, WASM_SEC_ORDER_NAME},
1821         // WASM_SEC_ORDER_RELOC (can be repeated)
1822         {},
1823         // WASM_SEC_ORDER_NAME
1824         {WASM_SEC_ORDER_NAME, WASM_SEC_ORDER_PRODUCERS},
1825         // WASM_SEC_ORDER_PRODUCERS
1826         {WASM_SEC_ORDER_PRODUCERS, WASM_SEC_ORDER_TARGET_FEATURES},
1827         // WASM_SEC_ORDER_TARGET_FEATURES
1828         {WASM_SEC_ORDER_TARGET_FEATURES}};
1829 
1830 bool WasmSectionOrderChecker::isValidSectionOrder(unsigned ID,
1831                                                   StringRef CustomSectionName) {
1832   int Order = getSectionOrder(ID, CustomSectionName);
1833   if (Order == WASM_SEC_ORDER_NONE)
1834     return true;
1835 
1836   // Disallowed predecessors we need to check for
1837   SmallVector<int, WASM_NUM_SEC_ORDERS> WorkList;
1838 
1839   // Keep track of completed checks to avoid repeating work
1840   bool Checked[WASM_NUM_SEC_ORDERS] = {};
1841 
1842   int Curr = Order;
1843   while (true) {
1844     // Add new disallowed predecessors to work list
1845     for (size_t I = 0;; ++I) {
1846       int Next = DisallowedPredecessors[Curr][I];
1847       if (Next == WASM_SEC_ORDER_NONE)
1848         break;
1849       if (Checked[Next])
1850         continue;
1851       WorkList.push_back(Next);
1852       Checked[Next] = true;
1853     }
1854 
1855     if (WorkList.empty())
1856       break;
1857 
1858     // Consider next disallowed predecessor
1859     Curr = WorkList.pop_back_val();
1860     if (Seen[Curr])
1861       return false;
1862   }
1863 
1864   // Have not seen any disallowed predecessors
1865   Seen[Order] = true;
1866   return true;
1867 }
1868