LLVM  10.0.0svn
WasmObjectWriter.cpp
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1 //===- lib/MC/WasmObjectWriter.cpp - Wasm File Writer ---------------------===//
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 // This file implements Wasm object file writer information.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/ADT/STLExtras.h"
14 #include "llvm/ADT/SmallPtrSet.h"
15 #include "llvm/BinaryFormat/Wasm.h"
16 #include "llvm/Config/llvm-config.h"
17 #include "llvm/MC/MCAsmBackend.h"
18 #include "llvm/MC/MCAsmLayout.h"
19 #include "llvm/MC/MCAssembler.h"
20 #include "llvm/MC/MCContext.h"
21 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCObjectWriter.h"
24 #include "llvm/MC/MCSectionWasm.h"
25 #include "llvm/MC/MCSymbolWasm.h"
26 #include "llvm/MC/MCValue.h"
28 #include "llvm/Support/Casting.h"
29 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/LEB128.h"
33 #include <vector>
34 
35 using namespace llvm;
36 
37 #define DEBUG_TYPE "mc"
38 
39 namespace {
40 
41 // Went we ceate the indirect function table we start at 1, so that there is
42 // and emtpy slot at 0 and therefore calling a null function pointer will trap.
43 static const uint32_t InitialTableOffset = 1;
44 
45 // For patching purposes, we need to remember where each section starts, both
46 // for patching up the section size field, and for patching up references to
47 // locations within the section.
48 struct SectionBookkeeping {
49  // Where the size of the section is written.
50  uint64_t SizeOffset;
51  // Where the section header ends (without custom section name).
52  uint64_t PayloadOffset;
53  // Where the contents of the section starts.
54  uint64_t ContentsOffset;
56 };
57 
58 // The signature of a wasm function or event, in a struct capable of being used
59 // as a DenseMap key.
60 // TODO: Consider using wasm::WasmSignature directly instead.
61 struct WasmSignature {
62  // Support empty and tombstone instances, needed by DenseMap.
63  enum { Plain, Empty, Tombstone } State = Plain;
64 
65  // The return types of the function.
67 
68  // The parameter types of the function.
70 
71  bool operator==(const WasmSignature &Other) const {
72  return State == Other.State && Returns == Other.Returns &&
73  Params == Other.Params;
74  }
75 };
76 
77 // Traits for using WasmSignature in a DenseMap.
78 struct WasmSignatureDenseMapInfo {
79  static WasmSignature getEmptyKey() {
80  WasmSignature Sig;
81  Sig.State = WasmSignature::Empty;
82  return Sig;
83  }
84  static WasmSignature getTombstoneKey() {
85  WasmSignature Sig;
86  Sig.State = WasmSignature::Tombstone;
87  return Sig;
88  }
89  static unsigned getHashValue(const WasmSignature &Sig) {
90  uintptr_t Value = Sig.State;
91  for (wasm::ValType Ret : Sig.Returns)
93  for (wasm::ValType Param : Sig.Params)
95  return Value;
96  }
97  static bool isEqual(const WasmSignature &LHS, const WasmSignature &RHS) {
98  return LHS == RHS;
99  }
100 };
101 
102 // A wasm data segment. A wasm binary contains only a single data section
103 // but that can contain many segments, each with their own virtual location
104 // in memory. Each MCSection data created by llvm is modeled as its own
105 // wasm data segment.
106 struct WasmDataSegment {
108  StringRef Name;
109  uint32_t InitFlags;
111  uint32_t Alignment;
112  uint32_t LinkerFlags;
114 };
115 
116 // A wasm function to be written into the function section.
117 struct WasmFunction {
118  uint32_t SigIndex;
119  const MCSymbolWasm *Sym;
120 };
121 
122 // A wasm global to be written into the global section.
123 struct WasmGlobal {
125  uint64_t InitialValue;
126 };
127 
128 // Information about a single item which is part of a COMDAT. For each data
129 // segment or function which is in the COMDAT, there is a corresponding
130 // WasmComdatEntry.
131 struct WasmComdatEntry {
132  unsigned Kind;
133  uint32_t Index;
134 };
135 
136 // Information about a single relocation.
137 struct WasmRelocationEntry {
138  uint64_t Offset; // Where is the relocation.
139  const MCSymbolWasm *Symbol; // The symbol to relocate with.
140  int64_t Addend; // A value to add to the symbol.
141  unsigned Type; // The type of the relocation.
142  const MCSectionWasm *FixupSection; // The section the relocation is targeting.
143 
144  WasmRelocationEntry(uint64_t Offset, const MCSymbolWasm *Symbol,
145  int64_t Addend, unsigned Type,
146  const MCSectionWasm *FixupSection)
147  : Offset(Offset), Symbol(Symbol), Addend(Addend), Type(Type),
148  FixupSection(FixupSection) {}
149 
150  bool hasAddend() const { return wasm::relocTypeHasAddend(Type); }
151 
152  void print(raw_ostream &Out) const {
153  Out << wasm::relocTypetoString(Type) << " Off=" << Offset
154  << ", Sym=" << *Symbol << ", Addend=" << Addend
155  << ", FixupSection=" << FixupSection->getSectionName();
156  }
157 
158 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
159  LLVM_DUMP_METHOD void dump() const { print(dbgs()); }
160 #endif
161 };
162 
163 static const uint32_t InvalidIndex = -1;
164 
165 struct WasmCustomSection {
166 
167  StringRef Name;
169 
170  uint32_t OutputContentsOffset;
171  uint32_t OutputIndex;
172 
173  WasmCustomSection(StringRef Name, MCSectionWasm *Section)
174  : Name(Name), Section(Section), OutputContentsOffset(0),
175  OutputIndex(InvalidIndex) {}
176 };
177 
178 #if !defined(NDEBUG)
179 raw_ostream &operator<<(raw_ostream &OS, const WasmRelocationEntry &Rel) {
180  Rel.print(OS);
181  return OS;
182 }
183 #endif
184 
185 // Write X as an (unsigned) LEB value at offset Offset in Stream, padded
186 // to allow patching.
187 static void writePatchableLEB(raw_pwrite_stream &Stream, uint32_t X,
188  uint64_t Offset) {
189  uint8_t Buffer[5];
190  unsigned SizeLen = encodeULEB128(X, Buffer, 5);
191  assert(SizeLen == 5);
192  Stream.pwrite((char *)Buffer, SizeLen, Offset);
193 }
194 
195 // Write X as an signed LEB value at offset Offset in Stream, padded
196 // to allow patching.
197 static void writePatchableSLEB(raw_pwrite_stream &Stream, int32_t X,
198  uint64_t Offset) {
199  uint8_t Buffer[5];
200  unsigned SizeLen = encodeSLEB128(X, Buffer, 5);
201  assert(SizeLen == 5);
202  Stream.pwrite((char *)Buffer, SizeLen, Offset);
203 }
204 
205 // Write X as a plain integer value at offset Offset in Stream.
206 static void writeI32(raw_pwrite_stream &Stream, uint32_t X, uint64_t Offset) {
207  uint8_t Buffer[4];
208  support::endian::write32le(Buffer, X);
209  Stream.pwrite((char *)Buffer, sizeof(Buffer), Offset);
210 }
211 
212 class WasmObjectWriter : public MCObjectWriter {
214 
215  /// The target specific Wasm writer instance.
216  std::unique_ptr<MCWasmObjectTargetWriter> TargetObjectWriter;
217 
218  // Relocations for fixing up references in the code section.
219  std::vector<WasmRelocationEntry> CodeRelocations;
220  uint32_t CodeSectionIndex;
221 
222  // Relocations for fixing up references in the data section.
223  std::vector<WasmRelocationEntry> DataRelocations;
224  uint32_t DataSectionIndex;
225 
226  // Index values to use for fixing up call_indirect type indices.
227  // Maps function symbols to the index of the type of the function
229  // Maps function symbols to the table element index space. Used
230  // for TABLE_INDEX relocation types (i.e. address taken functions).
232  // Maps function/global symbols to the function/global/event/section index
233  // space.
236  // Maps data symbols to the Wasm segment and offset/size with the segment.
238 
239  // Stores output data (index, relocations, content offset) for custom
240  // section.
241  std::vector<WasmCustomSection> CustomSections;
242  std::unique_ptr<WasmCustomSection> ProducersSection;
243  std::unique_ptr<WasmCustomSection> TargetFeaturesSection;
244  // Relocations for fixing up references in the custom sections.
246  CustomSectionsRelocations;
247 
248  // Map from section to defining function symbol.
250 
253  SmallVector<WasmDataSegment, 4> DataSegments;
254  unsigned NumFunctionImports = 0;
255  unsigned NumGlobalImports = 0;
256  unsigned NumEventImports = 0;
257  uint32_t SectionCount = 0;
258 
259  // TargetObjectWriter wrappers.
260  bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
261 
262  void startSection(SectionBookkeeping &Section, unsigned SectionId);
263  void startCustomSection(SectionBookkeeping &Section, StringRef Name);
264  void endSection(SectionBookkeeping &Section);
265 
266 public:
267  WasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
268  raw_pwrite_stream &OS)
269  : W(OS, support::little), TargetObjectWriter(std::move(MOTW)) {}
270 
271 private:
272  void reset() override {
273  CodeRelocations.clear();
274  DataRelocations.clear();
275  TypeIndices.clear();
276  WasmIndices.clear();
277  GOTIndices.clear();
278  TableIndices.clear();
279  DataLocations.clear();
280  CustomSections.clear();
281  ProducersSection.reset();
282  TargetFeaturesSection.reset();
283  CustomSectionsRelocations.clear();
284  SignatureIndices.clear();
285  Signatures.clear();
286  DataSegments.clear();
287  SectionFunctions.clear();
288  NumFunctionImports = 0;
289  NumGlobalImports = 0;
291  }
292 
293  void writeHeader(const MCAssembler &Asm);
294 
295  void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
296  const MCFragment *Fragment, const MCFixup &Fixup,
297  MCValue Target, uint64_t &FixedValue) override;
298 
299  void executePostLayoutBinding(MCAssembler &Asm,
300  const MCAsmLayout &Layout) override;
301 
302  uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
303 
304  void writeString(const StringRef Str) {
305  encodeULEB128(Str.size(), W.OS);
306  W.OS << Str;
307  }
308 
309  void writeValueType(wasm::ValType Ty) { W.OS << static_cast<char>(Ty); }
310 
311  void writeTypeSection(ArrayRef<WasmSignature> Signatures);
312  void writeImportSection(ArrayRef<wasm::WasmImport> Imports, uint32_t DataSize,
313  uint32_t NumElements);
314  void writeFunctionSection(ArrayRef<WasmFunction> Functions);
315  void writeExportSection(ArrayRef<wasm::WasmExport> Exports);
316  void writeElemSection(ArrayRef<uint32_t> TableElems);
317  void writeDataCountSection();
318  void writeCodeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
319  ArrayRef<WasmFunction> Functions);
320  void writeDataSection();
321  void writeEventSection(ArrayRef<wasm::WasmEventType> Events);
322  void writeRelocSection(uint32_t SectionIndex, StringRef Name,
323  std::vector<WasmRelocationEntry> &Relocations);
324  void writeLinkingMetaDataSection(
325  ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
326  ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
327  const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats);
328  void writeCustomSection(WasmCustomSection &CustomSection,
329  const MCAssembler &Asm, const MCAsmLayout &Layout);
330  void writeCustomRelocSections();
331  void
332  updateCustomSectionRelocations(const SmallVector<WasmFunction, 4> &Functions,
333  const MCAsmLayout &Layout);
334 
335  uint32_t getProvisionalValue(const WasmRelocationEntry &RelEntry);
336  void applyRelocations(ArrayRef<WasmRelocationEntry> Relocations,
337  uint64_t ContentsOffset);
338 
339  uint32_t getRelocationIndexValue(const WasmRelocationEntry &RelEntry);
340  uint32_t getFunctionType(const MCSymbolWasm &Symbol);
341  uint32_t getEventType(const MCSymbolWasm &Symbol);
342  void registerFunctionType(const MCSymbolWasm &Symbol);
343  void registerEventType(const MCSymbolWasm &Symbol);
344 };
345 
346 } // end anonymous namespace
347 
348 // Write out a section header and a patchable section size field.
349 void WasmObjectWriter::startSection(SectionBookkeeping &Section,
350  unsigned SectionId) {
351  LLVM_DEBUG(dbgs() << "startSection " << SectionId << "\n");
352  W.OS << char(SectionId);
353 
354  Section.SizeOffset = W.OS.tell();
355 
356  // The section size. We don't know the size yet, so reserve enough space
357  // for any 32-bit value; we'll patch it later.
358  encodeULEB128(0, W.OS, 5);
359 
360  // The position where the section starts, for measuring its size.
361  Section.ContentsOffset = W.OS.tell();
362  Section.PayloadOffset = W.OS.tell();
363  Section.Index = SectionCount++;
364 }
365 
366 void WasmObjectWriter::startCustomSection(SectionBookkeeping &Section,
367  StringRef Name) {
368  LLVM_DEBUG(dbgs() << "startCustomSection " << Name << "\n");
369  startSection(Section, wasm::WASM_SEC_CUSTOM);
370 
371  // The position where the section header ends, for measuring its size.
372  Section.PayloadOffset = W.OS.tell();
373 
374  // Custom sections in wasm also have a string identifier.
375  writeString(Name);
376 
377  // The position where the custom section starts.
378  Section.ContentsOffset = W.OS.tell();
379 }
380 
381 // Now that the section is complete and we know how big it is, patch up the
382 // section size field at the start of the section.
383 void WasmObjectWriter::endSection(SectionBookkeeping &Section) {
384  uint64_t Size = W.OS.tell();
385  // /dev/null doesn't support seek/tell and can report offset of 0.
386  // Simply skip this patching in that case.
387  if (!Size)
388  return;
389 
390  Size -= Section.PayloadOffset;
391  if (uint32_t(Size) != Size)
392  report_fatal_error("section size does not fit in a uint32_t");
393 
394  LLVM_DEBUG(dbgs() << "endSection size=" << Size << "\n");
395 
396  // Write the final section size to the payload_len field, which follows
397  // the section id byte.
398  writePatchableLEB(static_cast<raw_pwrite_stream &>(W.OS), Size,
399  Section.SizeOffset);
400 }
401 
402 // Emit the Wasm header.
403 void WasmObjectWriter::writeHeader(const MCAssembler &Asm) {
404  W.OS.write(wasm::WasmMagic, sizeof(wasm::WasmMagic));
405  W.write<uint32_t>(wasm::WasmVersion);
406 }
407 
408 void WasmObjectWriter::executePostLayoutBinding(MCAssembler &Asm,
409  const MCAsmLayout &Layout) {
410  // Build a map of sections to the function that defines them, for use
411  // in recordRelocation.
412  for (const MCSymbol &S : Asm.symbols()) {
413  const auto &WS = static_cast<const MCSymbolWasm &>(S);
414  if (WS.isDefined() && WS.isFunction() && !WS.isVariable()) {
415  const auto &Sec = static_cast<const MCSectionWasm &>(S.getSection());
416  auto Pair = SectionFunctions.insert(std::make_pair(&Sec, &S));
417  if (!Pair.second)
418  report_fatal_error("section already has a defining function: " +
419  Sec.getSectionName());
420  }
421  }
422 }
423 
424 void WasmObjectWriter::recordRelocation(MCAssembler &Asm,
425  const MCAsmLayout &Layout,
426  const MCFragment *Fragment,
427  const MCFixup &Fixup, MCValue Target,
428  uint64_t &FixedValue) {
429  MCAsmBackend &Backend = Asm.getBackend();
430  bool IsPCRel = Backend.getFixupKindInfo(Fixup.getKind()).Flags &
432  const auto &FixupSection = cast<MCSectionWasm>(*Fragment->getParent());
433  uint64_t C = Target.getConstant();
434  uint64_t FixupOffset = Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
435  MCContext &Ctx = Asm.getContext();
436 
437  // The .init_array isn't translated as data, so don't do relocations in it.
438  if (FixupSection.getSectionName().startswith(".init_array"))
439  return;
440 
441  if (const MCSymbolRefExpr *RefB = Target.getSymB()) {
442  assert(RefB->getKind() == MCSymbolRefExpr::VK_None &&
443  "Should not have constructed this");
444 
445  // Let A, B and C being the components of Target and R be the location of
446  // the fixup. If the fixup is not pcrel, we want to compute (A - B + C).
447  // If it is pcrel, we want to compute (A - B + C - R).
448 
449  // In general, Wasm has no relocations for -B. It can only represent (A + C)
450  // or (A + C - R). If B = R + K and the relocation is not pcrel, we can
451  // replace B to implement it: (A - R - K + C)
452  if (IsPCRel) {
453  Ctx.reportError(
454  Fixup.getLoc(),
455  "No relocation available to represent this relative expression");
456  return;
457  }
458 
459  const auto &SymB = cast<MCSymbolWasm>(RefB->getSymbol());
460 
461  if (SymB.isUndefined()) {
462  Ctx.reportError(Fixup.getLoc(),
463  Twine("symbol '") + SymB.getName() +
464  "' can not be undefined in a subtraction expression");
465  return;
466  }
467 
468  assert(!SymB.isAbsolute() && "Should have been folded");
469  const MCSection &SecB = SymB.getSection();
470  if (&SecB != &FixupSection) {
471  Ctx.reportError(Fixup.getLoc(),
472  "Cannot represent a difference across sections");
473  return;
474  }
475 
476  uint64_t SymBOffset = Layout.getSymbolOffset(SymB);
477  uint64_t K = SymBOffset - FixupOffset;
478  IsPCRel = true;
479  C -= K;
480  }
481 
482  // We either rejected the fixup or folded B into C at this point.
483  const MCSymbolRefExpr *RefA = Target.getSymA();
484  const auto *SymA = RefA ? cast<MCSymbolWasm>(&RefA->getSymbol()) : nullptr;
485 
486  if (SymA && SymA->isVariable()) {
487  const MCExpr *Expr = SymA->getVariableValue();
488  const auto *Inner = cast<MCSymbolRefExpr>(Expr);
489  if (Inner->getKind() == MCSymbolRefExpr::VK_WEAKREF)
490  llvm_unreachable("weakref used in reloc not yet implemented");
491  }
492 
493  // Put any constant offset in an addend. Offsets can be negative, and
494  // LLVM expects wrapping, in contrast to wasm's immediates which can't
495  // be negative and don't wrap.
496  FixedValue = 0;
497 
498  unsigned Type = TargetObjectWriter->getRelocType(Target, Fixup);
499  assert(!IsPCRel);
500  assert(SymA);
501 
502  // Absolute offset within a section or a function.
503  // Currently only supported for for metadata sections.
504  // See: test/MC/WebAssembly/blockaddress.ll
505  if (Type == wasm::R_WASM_FUNCTION_OFFSET_I32 ||
506  Type == wasm::R_WASM_SECTION_OFFSET_I32) {
507  if (!FixupSection.getKind().isMetadata())
508  report_fatal_error("relocations for function or section offsets are "
509  "only supported in metadata sections");
510 
511  const MCSymbol *SectionSymbol = nullptr;
512  const MCSection &SecA = SymA->getSection();
513  if (SecA.getKind().isText())
514  SectionSymbol = SectionFunctions.find(&SecA)->second;
515  else
516  SectionSymbol = SecA.getBeginSymbol();
517  if (!SectionSymbol)
518  report_fatal_error("section symbol is required for relocation");
519 
520  C += Layout.getSymbolOffset(*SymA);
521  SymA = cast<MCSymbolWasm>(SectionSymbol);
522  }
523 
524  // Relocation other than R_WASM_TYPE_INDEX_LEB are required to be
525  // against a named symbol.
526  if (Type != wasm::R_WASM_TYPE_INDEX_LEB) {
527  if (SymA->getName().empty())
528  report_fatal_error("relocations against un-named temporaries are not yet "
529  "supported by wasm");
530 
531  SymA->setUsedInReloc();
532  }
533 
534  if (RefA->getKind() == MCSymbolRefExpr::VK_GOT)
535  SymA->setUsedInGOT();
536 
537  WasmRelocationEntry Rec(FixupOffset, SymA, C, Type, &FixupSection);
538  LLVM_DEBUG(dbgs() << "WasmReloc: " << Rec << "\n");
539 
540  if (FixupSection.isWasmData()) {
541  DataRelocations.push_back(Rec);
542  } else if (FixupSection.getKind().isText()) {
543  CodeRelocations.push_back(Rec);
544  } else if (FixupSection.getKind().isMetadata()) {
545  CustomSectionsRelocations[&FixupSection].push_back(Rec);
546  } else {
547  llvm_unreachable("unexpected section type");
548  }
549 }
550 
552  const MCSymbolWasm* Ret = &Symbol;
553  while (Ret->isVariable()) {
554  const MCExpr *Expr = Ret->getVariableValue();
555  auto *Inner = cast<MCSymbolRefExpr>(Expr);
556  Ret = cast<MCSymbolWasm>(&Inner->getSymbol());
557  }
558  return Ret;
559 }
560 
561 // Compute a value to write into the code at the location covered
562 // by RelEntry. This value isn't used by the static linker; it just serves
563 // to make the object format more readable and more likely to be directly
564 // useable.
565 uint32_t
566 WasmObjectWriter::getProvisionalValue(const WasmRelocationEntry &RelEntry) {
567  if (RelEntry.Type == wasm::R_WASM_GLOBAL_INDEX_LEB && !RelEntry.Symbol->isGlobal()) {
568  assert(GOTIndices.count(RelEntry.Symbol) > 0 && "symbol not found in GOT index space");
569  return GOTIndices[RelEntry.Symbol];
570  }
571 
572  switch (RelEntry.Type) {
573  case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
574  case wasm::R_WASM_TABLE_INDEX_SLEB:
575  case wasm::R_WASM_TABLE_INDEX_I32: {
576  // Provisional value is table address of the resolved symbol itself
577  const MCSymbolWasm *Sym = resolveSymbol(*RelEntry.Symbol);
578  assert(Sym->isFunction());
579  return TableIndices[Sym];
580  }
581  case wasm::R_WASM_TYPE_INDEX_LEB:
582  // Provisional value is same as the index
583  return getRelocationIndexValue(RelEntry);
584  case wasm::R_WASM_FUNCTION_INDEX_LEB:
585  case wasm::R_WASM_GLOBAL_INDEX_LEB:
586  case wasm::R_WASM_EVENT_INDEX_LEB:
587  // Provisional value is function/global/event Wasm index
588  assert(WasmIndices.count(RelEntry.Symbol) > 0 && "symbol not found in wasm index space");
589  return WasmIndices[RelEntry.Symbol];
590  case wasm::R_WASM_FUNCTION_OFFSET_I32:
591  case wasm::R_WASM_SECTION_OFFSET_I32: {
592  const auto &Section =
593  static_cast<const MCSectionWasm &>(RelEntry.Symbol->getSection());
594  return Section.getSectionOffset() + RelEntry.Addend;
595  }
596  case wasm::R_WASM_MEMORY_ADDR_LEB:
597  case wasm::R_WASM_MEMORY_ADDR_I32:
598  case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
599  case wasm::R_WASM_MEMORY_ADDR_SLEB: {
600  // Provisional value is address of the global
601  const MCSymbolWasm *Sym = resolveSymbol(*RelEntry.Symbol);
602  // For undefined symbols, use zero
603  if (!Sym->isDefined())
604  return 0;
605  const wasm::WasmDataReference &Ref = DataLocations[Sym];
606  const WasmDataSegment &Segment = DataSegments[Ref.Segment];
607  // Ignore overflow. LLVM allows address arithmetic to silently wrap.
608  return Segment.Offset + Ref.Offset + RelEntry.Addend;
609  }
610  default:
611  llvm_unreachable("invalid relocation type");
612  }
613 }
614 
615 static void addData(SmallVectorImpl<char> &DataBytes,
616  MCSectionWasm &DataSection) {
617  LLVM_DEBUG(errs() << "addData: " << DataSection.getSectionName() << "\n");
618 
619  DataBytes.resize(alignTo(DataBytes.size(), DataSection.getAlignment()));
620 
621  for (const MCFragment &Frag : DataSection) {
622  if (Frag.hasInstructions())
623  report_fatal_error("only data supported in data sections");
624 
625  if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
626  if (Align->getValueSize() != 1)
627  report_fatal_error("only byte values supported for alignment");
628  // If nops are requested, use zeros, as this is the data section.
629  uint8_t Value = Align->hasEmitNops() ? 0 : Align->getValue();
630  uint64_t Size =
631  std::min<uint64_t>(alignTo(DataBytes.size(), Align->getAlignment()),
632  DataBytes.size() + Align->getMaxBytesToEmit());
633  DataBytes.resize(Size, Value);
634  } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
635  int64_t NumValues;
636  if (!Fill->getNumValues().evaluateAsAbsolute(NumValues))
637  llvm_unreachable("The fill should be an assembler constant");
638  DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues,
639  Fill->getValue());
640  } else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) {
641  const SmallVectorImpl<char> &Contents = LEB->getContents();
642  DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
643  } else {
644  const auto &DataFrag = cast<MCDataFragment>(Frag);
645  const SmallVectorImpl<char> &Contents = DataFrag.getContents();
646  DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
647  }
648  }
649 
650  LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n");
651 }
652 
653 uint32_t
654 WasmObjectWriter::getRelocationIndexValue(const WasmRelocationEntry &RelEntry) {
655  if (RelEntry.Type == wasm::R_WASM_TYPE_INDEX_LEB) {
656  if (!TypeIndices.count(RelEntry.Symbol))
657  report_fatal_error("symbol not found in type index space: " +
658  RelEntry.Symbol->getName());
659  return TypeIndices[RelEntry.Symbol];
660  }
661 
662  return RelEntry.Symbol->getIndex();
663 }
664 
665 // Apply the portions of the relocation records that we can handle ourselves
666 // directly.
667 void WasmObjectWriter::applyRelocations(
668  ArrayRef<WasmRelocationEntry> Relocations, uint64_t ContentsOffset) {
669  auto &Stream = static_cast<raw_pwrite_stream &>(W.OS);
670  for (const WasmRelocationEntry &RelEntry : Relocations) {
671  uint64_t Offset = ContentsOffset +
672  RelEntry.FixupSection->getSectionOffset() +
673  RelEntry.Offset;
674 
675  LLVM_DEBUG(dbgs() << "applyRelocation: " << RelEntry << "\n");
676  uint32_t Value = getProvisionalValue(RelEntry);
677 
678  switch (RelEntry.Type) {
679  case wasm::R_WASM_FUNCTION_INDEX_LEB:
680  case wasm::R_WASM_TYPE_INDEX_LEB:
681  case wasm::R_WASM_GLOBAL_INDEX_LEB:
682  case wasm::R_WASM_MEMORY_ADDR_LEB:
683  case wasm::R_WASM_EVENT_INDEX_LEB:
684  writePatchableLEB(Stream, Value, Offset);
685  break;
686  case wasm::R_WASM_TABLE_INDEX_I32:
687  case wasm::R_WASM_MEMORY_ADDR_I32:
688  case wasm::R_WASM_FUNCTION_OFFSET_I32:
689  case wasm::R_WASM_SECTION_OFFSET_I32:
690  writeI32(Stream, Value, Offset);
691  break;
692  case wasm::R_WASM_TABLE_INDEX_SLEB:
693  case wasm::R_WASM_TABLE_INDEX_REL_SLEB:
694  case wasm::R_WASM_MEMORY_ADDR_SLEB:
695  case wasm::R_WASM_MEMORY_ADDR_REL_SLEB:
696  writePatchableSLEB(Stream, Value, Offset);
697  break;
698  default:
699  llvm_unreachable("invalid relocation type");
700  }
701  }
702 }
703 
704 void WasmObjectWriter::writeTypeSection(ArrayRef<WasmSignature> Signatures) {
705  if (Signatures.empty())
706  return;
707 
708  SectionBookkeeping Section;
709  startSection(Section, wasm::WASM_SEC_TYPE);
710 
711  encodeULEB128(Signatures.size(), W.OS);
712 
713  for (const WasmSignature &Sig : Signatures) {
714  W.OS << char(wasm::WASM_TYPE_FUNC);
715  encodeULEB128(Sig.Params.size(), W.OS);
716  for (wasm::ValType Ty : Sig.Params)
717  writeValueType(Ty);
718  encodeULEB128(Sig.Returns.size(), W.OS);
719  for (wasm::ValType Ty : Sig.Returns)
720  writeValueType(Ty);
721  }
722 
723  endSection(Section);
724 }
725 
726 void WasmObjectWriter::writeImportSection(ArrayRef<wasm::WasmImport> Imports,
727  uint32_t DataSize,
728  uint32_t NumElements) {
729  if (Imports.empty())
730  return;
731 
732  uint32_t NumPages = (DataSize + wasm::WasmPageSize - 1) / wasm::WasmPageSize;
733 
734  SectionBookkeeping Section;
735  startSection(Section, wasm::WASM_SEC_IMPORT);
736 
737  encodeULEB128(Imports.size(), W.OS);
738  for (const wasm::WasmImport &Import : Imports) {
739  writeString(Import.Module);
740  writeString(Import.Field);
741  W.OS << char(Import.Kind);
742 
743  switch (Import.Kind) {
745  encodeULEB128(Import.SigIndex, W.OS);
746  break;
748  W.OS << char(Import.Global.Type);
749  W.OS << char(Import.Global.Mutable ? 1 : 0);
750  break;
752  encodeULEB128(0, W.OS); // flags
753  encodeULEB128(NumPages, W.OS); // initial
754  break;
756  W.OS << char(Import.Table.ElemType);
757  encodeULEB128(0, W.OS); // flags
758  encodeULEB128(NumElements, W.OS); // initial
759  break;
761  encodeULEB128(Import.Event.Attribute, W.OS);
762  encodeULEB128(Import.Event.SigIndex, W.OS);
763  break;
764  default:
765  llvm_unreachable("unsupported import kind");
766  }
767  }
768 
769  endSection(Section);
770 }
771 
772 void WasmObjectWriter::writeFunctionSection(ArrayRef<WasmFunction> Functions) {
773  if (Functions.empty())
774  return;
775 
776  SectionBookkeeping Section;
777  startSection(Section, wasm::WASM_SEC_FUNCTION);
778 
779  encodeULEB128(Functions.size(), W.OS);
780  for (const WasmFunction &Func : Functions)
781  encodeULEB128(Func.SigIndex, W.OS);
782 
783  endSection(Section);
784 }
785 
786 void WasmObjectWriter::writeEventSection(ArrayRef<wasm::WasmEventType> Events) {
787  if (Events.empty())
788  return;
789 
790  SectionBookkeeping Section;
791  startSection(Section, wasm::WASM_SEC_EVENT);
792 
793  encodeULEB128(Events.size(), W.OS);
794  for (const wasm::WasmEventType &Event : Events) {
795  encodeULEB128(Event.Attribute, W.OS);
796  encodeULEB128(Event.SigIndex, W.OS);
797  }
798 
799  endSection(Section);
800 }
801 
802 void WasmObjectWriter::writeExportSection(ArrayRef<wasm::WasmExport> Exports) {
803  if (Exports.empty())
804  return;
805 
806  SectionBookkeeping Section;
807  startSection(Section, wasm::WASM_SEC_EXPORT);
808 
809  encodeULEB128(Exports.size(), W.OS);
810  for (const wasm::WasmExport &Export : Exports) {
811  writeString(Export.Name);
812  W.OS << char(Export.Kind);
813  encodeULEB128(Export.Index, W.OS);
814  }
815 
816  endSection(Section);
817 }
818 
819 void WasmObjectWriter::writeElemSection(ArrayRef<uint32_t> TableElems) {
820  if (TableElems.empty())
821  return;
822 
823  SectionBookkeeping Section;
824  startSection(Section, wasm::WASM_SEC_ELEM);
825 
826  encodeULEB128(1, W.OS); // number of "segments"
827  encodeULEB128(0, W.OS); // the table index
828 
829  // init expr for starting offset
831  encodeSLEB128(InitialTableOffset, W.OS);
833 
834  encodeULEB128(TableElems.size(), W.OS);
835  for (uint32_t Elem : TableElems)
836  encodeULEB128(Elem, W.OS);
837 
838  endSection(Section);
839 }
840 
841 void WasmObjectWriter::writeDataCountSection() {
842  if (DataSegments.empty())
843  return;
844 
845  SectionBookkeeping Section;
846  startSection(Section, wasm::WASM_SEC_DATACOUNT);
847  encodeULEB128(DataSegments.size(), W.OS);
848  endSection(Section);
849 }
850 
851 void WasmObjectWriter::writeCodeSection(const MCAssembler &Asm,
852  const MCAsmLayout &Layout,
853  ArrayRef<WasmFunction> Functions) {
854  if (Functions.empty())
855  return;
856 
857  SectionBookkeeping Section;
858  startSection(Section, wasm::WASM_SEC_CODE);
859  CodeSectionIndex = Section.Index;
860 
861  encodeULEB128(Functions.size(), W.OS);
862 
863  for (const WasmFunction &Func : Functions) {
864  auto &FuncSection = static_cast<MCSectionWasm &>(Func.Sym->getSection());
865 
866  int64_t Size = 0;
867  if (!Func.Sym->getSize()->evaluateAsAbsolute(Size, Layout))
868  report_fatal_error(".size expression must be evaluatable");
869 
870  encodeULEB128(Size, W.OS);
871  FuncSection.setSectionOffset(W.OS.tell() - Section.ContentsOffset);
872  Asm.writeSectionData(W.OS, &FuncSection, Layout);
873  }
874 
875  // Apply fixups.
876  applyRelocations(CodeRelocations, Section.ContentsOffset);
877 
878  endSection(Section);
879 }
880 
881 void WasmObjectWriter::writeDataSection() {
882  if (DataSegments.empty())
883  return;
884 
885  SectionBookkeeping Section;
886  startSection(Section, wasm::WASM_SEC_DATA);
887  DataSectionIndex = Section.Index;
888 
889  encodeULEB128(DataSegments.size(), W.OS); // count
890 
891  for (const WasmDataSegment &Segment : DataSegments) {
892  encodeULEB128(Segment.InitFlags, W.OS); // flags
893  if (Segment.InitFlags & wasm::WASM_SEGMENT_HAS_MEMINDEX)
894  encodeULEB128(0, W.OS); // memory index
895  if ((Segment.InitFlags & wasm::WASM_SEGMENT_IS_PASSIVE) == 0) {
897  encodeSLEB128(Segment.Offset, W.OS); // offset
899  }
900  encodeULEB128(Segment.Data.size(), W.OS); // size
901  Segment.Section->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
902  W.OS << Segment.Data; // data
903  }
904 
905  // Apply fixups.
906  applyRelocations(DataRelocations, Section.ContentsOffset);
907 
908  endSection(Section);
909 }
910 
911 void WasmObjectWriter::writeRelocSection(
912  uint32_t SectionIndex, StringRef Name,
913  std::vector<WasmRelocationEntry> &Relocs) {
914  // See: https://github.com/WebAssembly/tool-conventions/blob/master/Linking.md
915  // for descriptions of the reloc sections.
916 
917  if (Relocs.empty())
918  return;
919 
920  // First, ensure the relocations are sorted in offset order. In general they
921  // should already be sorted since `recordRelocation` is called in offset
922  // order, but for the code section we combine many MC sections into single
923  // wasm section, and this order is determined by the order of Asm.Symbols()
924  // not the sections order.
926  Relocs, [](const WasmRelocationEntry &A, const WasmRelocationEntry &B) {
927  return (A.Offset + A.FixupSection->getSectionOffset()) <
928  (B.Offset + B.FixupSection->getSectionOffset());
929  });
930 
931  SectionBookkeeping Section;
932  startCustomSection(Section, std::string("reloc.") + Name.str());
933 
934  encodeULEB128(SectionIndex, W.OS);
935  encodeULEB128(Relocs.size(), W.OS);
936  for (const WasmRelocationEntry &RelEntry : Relocs) {
937  uint64_t Offset =
938  RelEntry.Offset + RelEntry.FixupSection->getSectionOffset();
939  uint32_t Index = getRelocationIndexValue(RelEntry);
940 
941  W.OS << char(RelEntry.Type);
942  encodeULEB128(Offset, W.OS);
943  encodeULEB128(Index, W.OS);
944  if (RelEntry.hasAddend())
945  encodeSLEB128(RelEntry.Addend, W.OS);
946  }
947 
948  endSection(Section);
949 }
950 
951 void WasmObjectWriter::writeCustomRelocSections() {
952  for (const auto &Sec : CustomSections) {
953  auto &Relocations = CustomSectionsRelocations[Sec.Section];
954  writeRelocSection(Sec.OutputIndex, Sec.Name, Relocations);
955  }
956 }
957 
958 void WasmObjectWriter::writeLinkingMetaDataSection(
959  ArrayRef<wasm::WasmSymbolInfo> SymbolInfos,
960  ArrayRef<std::pair<uint16_t, uint32_t>> InitFuncs,
961  const std::map<StringRef, std::vector<WasmComdatEntry>> &Comdats) {
962  SectionBookkeeping Section;
963  startCustomSection(Section, "linking");
965 
966  SectionBookkeeping SubSection;
967  if (SymbolInfos.size() != 0) {
968  startSection(SubSection, wasm::WASM_SYMBOL_TABLE);
969  encodeULEB128(SymbolInfos.size(), W.OS);
970  for (const wasm::WasmSymbolInfo &Sym : SymbolInfos) {
971  encodeULEB128(Sym.Kind, W.OS);
972  encodeULEB128(Sym.Flags, W.OS);
973  switch (Sym.Kind) {
977  encodeULEB128(Sym.ElementIndex, W.OS);
978  if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0 ||
979  (Sym.Flags & wasm::WASM_SYMBOL_EXPLICIT_NAME) != 0)
980  writeString(Sym.Name);
981  break;
983  writeString(Sym.Name);
984  if ((Sym.Flags & wasm::WASM_SYMBOL_UNDEFINED) == 0) {
985  encodeULEB128(Sym.DataRef.Segment, W.OS);
986  encodeULEB128(Sym.DataRef.Offset, W.OS);
987  encodeULEB128(Sym.DataRef.Size, W.OS);
988  }
989  break;
991  const uint32_t SectionIndex =
992  CustomSections[Sym.ElementIndex].OutputIndex;
993  encodeULEB128(SectionIndex, W.OS);
994  break;
995  }
996  default:
997  llvm_unreachable("unexpected kind");
998  }
999  }
1000  endSection(SubSection);
1001  }
1002 
1003  if (DataSegments.size()) {
1004  startSection(SubSection, wasm::WASM_SEGMENT_INFO);
1005  encodeULEB128(DataSegments.size(), W.OS);
1006  for (const WasmDataSegment &Segment : DataSegments) {
1007  writeString(Segment.Name);
1008  encodeULEB128(Segment.Alignment, W.OS);
1009  encodeULEB128(Segment.LinkerFlags, W.OS);
1010  }
1011  endSection(SubSection);
1012  }
1013 
1014  if (!InitFuncs.empty()) {
1015  startSection(SubSection, wasm::WASM_INIT_FUNCS);
1016  encodeULEB128(InitFuncs.size(), W.OS);
1017  for (auto &StartFunc : InitFuncs) {
1018  encodeULEB128(StartFunc.first, W.OS); // priority
1019  encodeULEB128(StartFunc.second, W.OS); // function index
1020  }
1021  endSection(SubSection);
1022  }
1023 
1024  if (Comdats.size()) {
1025  startSection(SubSection, wasm::WASM_COMDAT_INFO);
1026  encodeULEB128(Comdats.size(), W.OS);
1027  for (const auto &C : Comdats) {
1028  writeString(C.first);
1029  encodeULEB128(0, W.OS); // flags for future use
1030  encodeULEB128(C.second.size(), W.OS);
1031  for (const WasmComdatEntry &Entry : C.second) {
1032  encodeULEB128(Entry.Kind, W.OS);
1033  encodeULEB128(Entry.Index, W.OS);
1034  }
1035  }
1036  endSection(SubSection);
1037  }
1038 
1039  endSection(Section);
1040 }
1041 
1042 void WasmObjectWriter::writeCustomSection(WasmCustomSection &CustomSection,
1043  const MCAssembler &Asm,
1044  const MCAsmLayout &Layout) {
1045  SectionBookkeeping Section;
1046  auto *Sec = CustomSection.Section;
1047  startCustomSection(Section, CustomSection.Name);
1048 
1049  Sec->setSectionOffset(W.OS.tell() - Section.ContentsOffset);
1050  Asm.writeSectionData(W.OS, Sec, Layout);
1051 
1052  CustomSection.OutputContentsOffset = Section.ContentsOffset;
1053  CustomSection.OutputIndex = Section.Index;
1054 
1055  endSection(Section);
1056 
1057  // Apply fixups.
1058  auto &Relocations = CustomSectionsRelocations[CustomSection.Section];
1059  applyRelocations(Relocations, CustomSection.OutputContentsOffset);
1060 }
1061 
1062 uint32_t WasmObjectWriter::getFunctionType(const MCSymbolWasm &Symbol) {
1063  assert(Symbol.isFunction());
1064  assert(TypeIndices.count(&Symbol));
1065  return TypeIndices[&Symbol];
1066 }
1067 
1068 uint32_t WasmObjectWriter::getEventType(const MCSymbolWasm &Symbol) {
1069  assert(Symbol.isEvent());
1070  assert(TypeIndices.count(&Symbol));
1071  return TypeIndices[&Symbol];
1072 }
1073 
1074 void WasmObjectWriter::registerFunctionType(const MCSymbolWasm &Symbol) {
1075  assert(Symbol.isFunction());
1076 
1077  WasmSignature S;
1078  const MCSymbolWasm *ResolvedSym = resolveSymbol(Symbol);
1079  if (auto *Sig = ResolvedSym->getSignature()) {
1080  S.Returns = Sig->Returns;
1081  S.Params = Sig->Params;
1082  }
1083 
1084  auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size()));
1085  if (Pair.second)
1086  Signatures.push_back(S);
1087  TypeIndices[&Symbol] = Pair.first->second;
1088 
1089  LLVM_DEBUG(dbgs() << "registerFunctionType: " << Symbol
1090  << " new:" << Pair.second << "\n");
1091  LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
1092 }
1093 
1094 void WasmObjectWriter::registerEventType(const MCSymbolWasm &Symbol) {
1095  assert(Symbol.isEvent());
1096 
1097  // TODO Currently we don't generate imported exceptions, but if we do, we
1098  // should have a way of infering types of imported exceptions.
1099  WasmSignature S;
1100  if (auto *Sig = Symbol.getSignature()) {
1101  S.Returns = Sig->Returns;
1102  S.Params = Sig->Params;
1103  }
1104 
1105  auto Pair = SignatureIndices.insert(std::make_pair(S, Signatures.size()));
1106  if (Pair.second)
1107  Signatures.push_back(S);
1108  TypeIndices[&Symbol] = Pair.first->second;
1109 
1110  LLVM_DEBUG(dbgs() << "registerEventType: " << Symbol << " new:" << Pair.second
1111  << "\n");
1112  LLVM_DEBUG(dbgs() << " -> type index: " << Pair.first->second << "\n");
1113 }
1114 
1115 static bool isInSymtab(const MCSymbolWasm &Sym) {
1116  if (Sym.isUsedInReloc())
1117  return true;
1118 
1119  if (Sym.isComdat() && !Sym.isDefined())
1120  return false;
1121 
1122  if (Sym.isTemporary() && Sym.getName().empty())
1123  return false;
1124 
1125  if (Sym.isTemporary() && Sym.isData() && !Sym.getSize())
1126  return false;
1127 
1128  if (Sym.isSection())
1129  return false;
1130 
1131  return true;
1132 }
1133 
1134 uint64_t WasmObjectWriter::writeObject(MCAssembler &Asm,
1135  const MCAsmLayout &Layout) {
1136  uint64_t StartOffset = W.OS.tell();
1137 
1138  LLVM_DEBUG(dbgs() << "WasmObjectWriter::writeObject\n");
1139 
1140  // Collect information from the available symbols.
1141  SmallVector<WasmFunction, 4> Functions;
1142  SmallVector<uint32_t, 4> TableElems;
1148  std::map<StringRef, std::vector<WasmComdatEntry>> Comdats;
1149  uint32_t DataSize = 0;
1150 
1151  // For now, always emit the memory import, since loads and stores are not
1152  // valid without it. In the future, we could perhaps be more clever and omit
1153  // it if there are no loads or stores.
1154  wasm::WasmImport MemImport;
1155  MemImport.Module = "env";
1156  MemImport.Field = "__linear_memory";
1157  MemImport.Kind = wasm::WASM_EXTERNAL_MEMORY;
1158  Imports.push_back(MemImport);
1159 
1160  // For now, always emit the table section, since indirect calls are not
1161  // valid without it. In the future, we could perhaps be more clever and omit
1162  // it if there are no indirect calls.
1163  wasm::WasmImport TableImport;
1164  TableImport.Module = "env";
1165  TableImport.Field = "__indirect_function_table";
1166  TableImport.Kind = wasm::WASM_EXTERNAL_TABLE;
1167  TableImport.Table.ElemType = wasm::WASM_TYPE_FUNCREF;
1168  Imports.push_back(TableImport);
1169 
1170  // Populate SignatureIndices, and Imports and WasmIndices for undefined
1171  // symbols. This must be done before populating WasmIndices for defined
1172  // symbols.
1173  for (const MCSymbol &S : Asm.symbols()) {
1174  const auto &WS = static_cast<const MCSymbolWasm &>(S);
1175 
1176  // Register types for all functions, including those with private linkage
1177  // (because wasm always needs a type signature).
1178  if (WS.isFunction())
1179  registerFunctionType(WS);
1180 
1181  if (WS.isEvent())
1182  registerEventType(WS);
1183 
1184  if (WS.isTemporary())
1185  continue;
1186 
1187  // If the symbol is not defined in this translation unit, import it.
1188  if (!WS.isDefined() && !WS.isComdat()) {
1189  if (WS.isFunction()) {
1191  Import.Module = WS.getImportModule();
1192  Import.Field = WS.getImportName();
1194  Import.SigIndex = getFunctionType(WS);
1195  Imports.push_back(Import);
1196  assert(WasmIndices.count(&WS) == 0);
1197  WasmIndices[&WS] = NumFunctionImports++;
1198  } else if (WS.isGlobal()) {
1199  if (WS.isWeak())
1200  report_fatal_error("undefined global symbol cannot be weak");
1201 
1203  Import.Field = WS.getImportName();
1205  Import.Module = WS.getImportModule();
1206  Import.Global = WS.getGlobalType();
1207  Imports.push_back(Import);
1208  assert(WasmIndices.count(&WS) == 0);
1209  WasmIndices[&WS] = NumGlobalImports++;
1210  } else if (WS.isEvent()) {
1211  if (WS.isWeak())
1212  report_fatal_error("undefined event symbol cannot be weak");
1213 
1215  Import.Module = WS.getImportModule();
1216  Import.Field = WS.getImportName();
1219  Import.Event.SigIndex = getEventType(WS);
1220  Imports.push_back(Import);
1221  assert(WasmIndices.count(&WS) == 0);
1222  WasmIndices[&WS] = NumEventImports++;
1223  }
1224  }
1225  }
1226 
1227  // Add imports for GOT globals
1228  for (const MCSymbol &S : Asm.symbols()) {
1229  const auto &WS = static_cast<const MCSymbolWasm &>(S);
1230  if (WS.isUsedInGOT()) {
1232  if (WS.isFunction())
1233  Import.Module = "GOT.func";
1234  else
1235  Import.Module = "GOT.mem";
1236  Import.Field = WS.getName();
1238  Import.Global = {wasm::WASM_TYPE_I32, true};
1239  Imports.push_back(Import);
1240  assert(GOTIndices.count(&WS) == 0);
1241  GOTIndices[&WS] = NumGlobalImports++;
1242  }
1243  }
1244 
1245  // Populate DataSegments and CustomSections, which must be done before
1246  // populating DataLocations.
1247  for (MCSection &Sec : Asm) {
1248  auto &Section = static_cast<MCSectionWasm &>(Sec);
1249  StringRef SectionName = Section.getSectionName();
1250 
1251  // .init_array sections are handled specially elsewhere.
1252  if (SectionName.startswith(".init_array"))
1253  continue;
1254 
1255  // Code is handled separately
1256  if (Section.getKind().isText())
1257  continue;
1258 
1259  if (Section.isWasmData()) {
1260  uint32_t SegmentIndex = DataSegments.size();
1261  DataSize = alignTo(DataSize, Section.getAlignment());
1262  DataSegments.emplace_back();
1263  WasmDataSegment &Segment = DataSegments.back();
1264  Segment.Name = SectionName;
1265  Segment.InitFlags =
1266  Section.getPassive() ? (uint32_t)wasm::WASM_SEGMENT_IS_PASSIVE : 0;
1267  Segment.Offset = DataSize;
1268  Segment.Section = &Section;
1269  addData(Segment.Data, Section);
1270  Segment.Alignment = Log2_32(Section.getAlignment());
1271  Segment.LinkerFlags = 0;
1272  DataSize += Segment.Data.size();
1273  Section.setSegmentIndex(SegmentIndex);
1274 
1275  if (const MCSymbolWasm *C = Section.getGroup()) {
1276  Comdats[C->getName()].emplace_back(
1277  WasmComdatEntry{wasm::WASM_COMDAT_DATA, SegmentIndex});
1278  }
1279  } else {
1280  // Create custom sections
1281  assert(Sec.getKind().isMetadata());
1282 
1283  StringRef Name = SectionName;
1284 
1285  // For user-defined custom sections, strip the prefix
1286  if (Name.startswith(".custom_section."))
1287  Name = Name.substr(strlen(".custom_section."));
1288 
1289  MCSymbol *Begin = Sec.getBeginSymbol();
1290  if (Begin) {
1291  WasmIndices[cast<MCSymbolWasm>(Begin)] = CustomSections.size();
1292  if (SectionName != Begin->getName())
1293  report_fatal_error("section name and begin symbol should match: " +
1294  Twine(SectionName));
1295  }
1296 
1297  // Separate out the producers and target features sections
1298  if (Name == "producers") {
1299  ProducersSection = std::make_unique<WasmCustomSection>(Name, &Section);
1300  continue;
1301  }
1302  if (Name == "target_features") {
1303  TargetFeaturesSection =
1304  std::make_unique<WasmCustomSection>(Name, &Section);
1305  continue;
1306  }
1307 
1308  CustomSections.emplace_back(Name, &Section);
1309  }
1310  }
1311 
1312  // Populate WasmIndices and DataLocations for defined symbols.
1313  for (const MCSymbol &S : Asm.symbols()) {
1314  // Ignore unnamed temporary symbols, which aren't ever exported, imported,
1315  // or used in relocations.
1316  if (S.isTemporary() && S.getName().empty())
1317  continue;
1318 
1319  const auto &WS = static_cast<const MCSymbolWasm &>(S);
1320  LLVM_DEBUG(
1321  dbgs() << "MCSymbol: " << toString(WS.getType()) << " '" << S << "'"
1322  << " isDefined=" << S.isDefined() << " isExternal="
1323  << S.isExternal() << " isTemporary=" << S.isTemporary()
1324  << " isWeak=" << WS.isWeak() << " isHidden=" << WS.isHidden()
1325  << " isVariable=" << WS.isVariable() << "\n");
1326 
1327  if (WS.isVariable())
1328  continue;
1329  if (WS.isComdat() && !WS.isDefined())
1330  continue;
1331 
1332  if (WS.isFunction()) {
1333  unsigned Index;
1334  if (WS.isDefined()) {
1335  if (WS.getOffset() != 0)
1337  "function sections must contain one function each");
1338 
1339  if (WS.getSize() == nullptr)
1341  "function symbols must have a size set with .size");
1342 
1343  // A definition. Write out the function body.
1344  Index = NumFunctionImports + Functions.size();
1345  WasmFunction Func;
1346  Func.SigIndex = getFunctionType(WS);
1347  Func.Sym = &WS;
1348  WasmIndices[&WS] = Index;
1349  Functions.push_back(Func);
1350 
1351  auto &Section = static_cast<MCSectionWasm &>(WS.getSection());
1352  if (const MCSymbolWasm *C = Section.getGroup()) {
1353  Comdats[C->getName()].emplace_back(
1354  WasmComdatEntry{wasm::WASM_COMDAT_FUNCTION, Index});
1355  }
1356  } else {
1357  // An import; the index was assigned above.
1358  Index = WasmIndices.find(&WS)->second;
1359  }
1360 
1361  LLVM_DEBUG(dbgs() << " -> function index: " << Index << "\n");
1362 
1363  } else if (WS.isData()) {
1364  if (!isInSymtab(WS))
1365  continue;
1366 
1367  if (!WS.isDefined()) {
1368  LLVM_DEBUG(dbgs() << " -> segment index: -1"
1369  << "\n");
1370  continue;
1371  }
1372 
1373  if (!WS.getSize())
1374  report_fatal_error("data symbols must have a size set with .size: " +
1375  WS.getName());
1376 
1377  int64_t Size = 0;
1378  if (!WS.getSize()->evaluateAsAbsolute(Size, Layout))
1379  report_fatal_error(".size expression must be evaluatable");
1380 
1381  auto &DataSection = static_cast<MCSectionWasm &>(WS.getSection());
1382  assert(DataSection.isWasmData());
1383 
1384  // For each data symbol, export it in the symtab as a reference to the
1385  // corresponding Wasm data segment.
1387  DataSection.getSegmentIndex(),
1388  static_cast<uint32_t>(Layout.getSymbolOffset(WS)),
1389  static_cast<uint32_t>(Size)};
1390  DataLocations[&WS] = Ref;
1391  LLVM_DEBUG(dbgs() << " -> segment index: " << Ref.Segment << "\n");
1392 
1393  } else if (WS.isGlobal()) {
1394  // A "true" Wasm global (currently just __stack_pointer)
1395  if (WS.isDefined())
1396  report_fatal_error("don't yet support defined globals");
1397 
1398  // An import; the index was assigned above
1399  LLVM_DEBUG(dbgs() << " -> global index: "
1400  << WasmIndices.find(&WS)->second << "\n");
1401 
1402  } else if (WS.isEvent()) {
1403  // C++ exception symbol (__cpp_exception)
1404  unsigned Index;
1405  if (WS.isDefined()) {
1406  Index = NumEventImports + Events.size();
1407  wasm::WasmEventType Event;
1408  Event.SigIndex = getEventType(WS);
1410  assert(WasmIndices.count(&WS) == 0);
1411  WasmIndices[&WS] = Index;
1412  Events.push_back(Event);
1413  } else {
1414  // An import; the index was assigned above.
1415  assert(WasmIndices.count(&WS) > 0);
1416  }
1417  LLVM_DEBUG(dbgs() << " -> event index: " << WasmIndices.find(&WS)->second
1418  << "\n");
1419 
1420  } else {
1421  assert(WS.isSection());
1422  }
1423  }
1424 
1425  // Populate WasmIndices and DataLocations for aliased symbols. We need to
1426  // process these in a separate pass because we need to have processed the
1427  // target of the alias before the alias itself and the symbols are not
1428  // necessarily ordered in this way.
1429  for (const MCSymbol &S : Asm.symbols()) {
1430  if (!S.isVariable())
1431  continue;
1432 
1433  assert(S.isDefined());
1434 
1435  // Find the target symbol of this weak alias and export that index
1436  const auto &WS = static_cast<const MCSymbolWasm &>(S);
1437  const MCSymbolWasm *ResolvedSym = resolveSymbol(WS);
1438  LLVM_DEBUG(dbgs() << WS.getName() << ": weak alias of '" << *ResolvedSym
1439  << "'\n");
1440 
1441  if (ResolvedSym->isFunction()) {
1442  assert(WasmIndices.count(ResolvedSym) > 0);
1443  uint32_t WasmIndex = WasmIndices.find(ResolvedSym)->second;
1444  assert(WasmIndices.count(&WS) == 0);
1445  WasmIndices[&WS] = WasmIndex;
1446  LLVM_DEBUG(dbgs() << " -> index:" << WasmIndex << "\n");
1447  } else if (ResolvedSym->isData()) {
1448  assert(DataLocations.count(ResolvedSym) > 0);
1449  const wasm::WasmDataReference &Ref =
1450  DataLocations.find(ResolvedSym)->second;
1451  DataLocations[&WS] = Ref;
1452  LLVM_DEBUG(dbgs() << " -> index:" << Ref.Segment << "\n");
1453  } else {
1454  report_fatal_error("don't yet support global/event aliases");
1455  }
1456  }
1457 
1458  // Finally, populate the symbol table itself, in its "natural" order.
1459  for (const MCSymbol &S : Asm.symbols()) {
1460  const auto &WS = static_cast<const MCSymbolWasm &>(S);
1461  if (!isInSymtab(WS)) {
1462  WS.setIndex(InvalidIndex);
1463  continue;
1464  }
1465  LLVM_DEBUG(dbgs() << "adding to symtab: " << WS << "\n");
1466 
1467  uint32_t Flags = 0;
1468  if (WS.isWeak())
1470  if (WS.isHidden())
1472  if (!WS.isExternal() && WS.isDefined())
1474  if (WS.isUndefined())
1475  Flags |= wasm::WASM_SYMBOL_UNDEFINED;
1476  if (WS.isExported())
1477  Flags |= wasm::WASM_SYMBOL_EXPORTED;
1478  if (WS.getName() != WS.getImportName())
1480 
1482  Info.Name = WS.getName();
1483  Info.Kind = WS.getType();
1484  Info.Flags = Flags;
1485  if (!WS.isData()) {
1486  assert(WasmIndices.count(&WS) > 0);
1487  Info.ElementIndex = WasmIndices.find(&WS)->second;
1488  } else if (WS.isDefined()) {
1489  assert(DataLocations.count(&WS) > 0);
1490  Info.DataRef = DataLocations.find(&WS)->second;
1491  }
1492  WS.setIndex(SymbolInfos.size());
1493  SymbolInfos.emplace_back(Info);
1494  }
1495 
1496  {
1497  auto HandleReloc = [&](const WasmRelocationEntry &Rel) {
1498  // Functions referenced by a relocation need to put in the table. This is
1499  // purely to make the object file's provisional values readable, and is
1500  // ignored by the linker, which re-calculates the relocations itself.
1501  if (Rel.Type != wasm::R_WASM_TABLE_INDEX_I32 &&
1502  Rel.Type != wasm::R_WASM_TABLE_INDEX_SLEB)
1503  return;
1504  assert(Rel.Symbol->isFunction());
1505  const MCSymbolWasm &WS = *resolveSymbol(*Rel.Symbol);
1506  uint32_t FunctionIndex = WasmIndices.find(&WS)->second;
1507  uint32_t TableIndex = TableElems.size() + InitialTableOffset;
1508  if (TableIndices.try_emplace(&WS, TableIndex).second) {
1509  LLVM_DEBUG(dbgs() << " -> adding " << WS.getName()
1510  << " to table: " << TableIndex << "\n");
1511  TableElems.push_back(FunctionIndex);
1512  registerFunctionType(WS);
1513  }
1514  };
1515 
1516  for (const WasmRelocationEntry &RelEntry : CodeRelocations)
1517  HandleReloc(RelEntry);
1518  for (const WasmRelocationEntry &RelEntry : DataRelocations)
1519  HandleReloc(RelEntry);
1520  }
1521 
1522  // Translate .init_array section contents into start functions.
1523  for (const MCSection &S : Asm) {
1524  const auto &WS = static_cast<const MCSectionWasm &>(S);
1525  if (WS.getSectionName().startswith(".fini_array"))
1526  report_fatal_error(".fini_array sections are unsupported");
1527  if (!WS.getSectionName().startswith(".init_array"))
1528  continue;
1529  if (WS.getFragmentList().empty())
1530  continue;
1531 
1532  // init_array is expected to contain a single non-empty data fragment
1533  if (WS.getFragmentList().size() != 3)
1534  report_fatal_error("only one .init_array section fragment supported");
1535 
1536  auto IT = WS.begin();
1537  const MCFragment &EmptyFrag = *IT;
1538  if (EmptyFrag.getKind() != MCFragment::FT_Data)
1539  report_fatal_error(".init_array section should be aligned");
1540 
1541  IT = std::next(IT);
1542  const MCFragment &AlignFrag = *IT;
1543  if (AlignFrag.getKind() != MCFragment::FT_Align)
1544  report_fatal_error(".init_array section should be aligned");
1545  if (cast<MCAlignFragment>(AlignFrag).getAlignment() != (is64Bit() ? 8 : 4))
1546  report_fatal_error(".init_array section should be aligned for pointers");
1547 
1548  const MCFragment &Frag = *std::next(IT);
1549  if (Frag.hasInstructions() || Frag.getKind() != MCFragment::FT_Data)
1550  report_fatal_error("only data supported in .init_array section");
1551 
1552  uint16_t Priority = UINT16_MAX;
1553  unsigned PrefixLength = strlen(".init_array");
1554  if (WS.getSectionName().size() > PrefixLength) {
1555  if (WS.getSectionName()[PrefixLength] != '.')
1557  ".init_array section priority should start with '.'");
1558  if (WS.getSectionName()
1559  .substr(PrefixLength + 1)
1560  .getAsInteger(10, Priority))
1561  report_fatal_error("invalid .init_array section priority");
1562  }
1563  const auto &DataFrag = cast<MCDataFragment>(Frag);
1564  const SmallVectorImpl<char> &Contents = DataFrag.getContents();
1565  for (const uint8_t *
1566  P = (const uint8_t *)Contents.data(),
1567  *End = (const uint8_t *)Contents.data() + Contents.size();
1568  P != End; ++P) {
1569  if (*P != 0)
1570  report_fatal_error("non-symbolic data in .init_array section");
1571  }
1572  for (const MCFixup &Fixup : DataFrag.getFixups()) {
1573  assert(Fixup.getKind() ==
1574  MCFixup::getKindForSize(is64Bit() ? 8 : 4, false));
1575  const MCExpr *Expr = Fixup.getValue();
1576  auto *SymRef = dyn_cast<MCSymbolRefExpr>(Expr);
1577  if (!SymRef)
1578  report_fatal_error("fixups in .init_array should be symbol references");
1579  const auto &TargetSym = cast<const MCSymbolWasm>(SymRef->getSymbol());
1580  if (TargetSym.getIndex() == InvalidIndex)
1581  report_fatal_error("symbols in .init_array should exist in symbtab");
1582  if (!TargetSym.isFunction())
1583  report_fatal_error("symbols in .init_array should be for functions");
1584  InitFuncs.push_back(
1585  std::make_pair(Priority, TargetSym.getIndex()));
1586  }
1587  }
1588 
1589  // Write out the Wasm header.
1590  writeHeader(Asm);
1591 
1592  writeTypeSection(Signatures);
1593  writeImportSection(Imports, DataSize, TableElems.size());
1594  writeFunctionSection(Functions);
1595  // Skip the "table" section; we import the table instead.
1596  // Skip the "memory" section; we import the memory instead.
1597  writeEventSection(Events);
1598  writeExportSection(Exports);
1599  writeElemSection(TableElems);
1600  writeDataCountSection();
1601  writeCodeSection(Asm, Layout, Functions);
1602  writeDataSection();
1603  for (auto &CustomSection : CustomSections)
1604  writeCustomSection(CustomSection, Asm, Layout);
1605  writeLinkingMetaDataSection(SymbolInfos, InitFuncs, Comdats);
1606  writeRelocSection(CodeSectionIndex, "CODE", CodeRelocations);
1607  writeRelocSection(DataSectionIndex, "DATA", DataRelocations);
1608  writeCustomRelocSections();
1609  if (ProducersSection)
1610  writeCustomSection(*ProducersSection, Asm, Layout);
1611  if (TargetFeaturesSection)
1612  writeCustomSection(*TargetFeaturesSection, Asm, Layout);
1613 
1614  // TODO: Translate the .comment section to the output.
1615  return W.OS.tell() - StartOffset;
1616 }
1617 
1618 std::unique_ptr<MCObjectWriter>
1619 llvm::createWasmObjectWriter(std::unique_ptr<MCWasmObjectTargetWriter> MOTW,
1620  raw_pwrite_stream &OS) {
1621  return std::make_unique<WasmObjectWriter>(std::move(MOTW), OS);
1622 }
bool isFunction() const
Definition: MCSymbolWasm.h:42
uint64_t CallInst * C
Instances of this class represent a uniqued identifier for a section in the current translation unit...
Definition: MCSection.h:38
reference emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:641
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
SectionKind getKind() const
Definition: MCSection.h:105
raw_ostream & errs()
This returns a reference to a raw_ostream for standard error.
LLVM_NODISCARD std::string str() const
str - Get the contents as an std::string.
Definition: StringRef.h:218
bool isData() const
Definition: MCSymbolWasm.h:43
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:139
This class represents lattice values for constants.
Definition: AllocatorList.h:23
bool isVariable() const
isVariable - Check if this is a variable symbol.
Definition: MCSymbol.h:297
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:473
This represents an "assembler immediate".
Definition: MCValue.h:39
bool relocTypeHasAddend(uint32_t type)
Definition: Wasm.cpp:39
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
VariantKind getKind() const
Definition: MCExpr.h:346
const unsigned WASM_SYMBOL_BINDING_LOCAL
Definition: Wasm.h:315
amdgpu Simplify well known AMD library false FunctionCallee Value const Twine & Name
LLVM_NODISCARD bool startswith(StringRef Prefix) const
Check if this string starts with the given Prefix.
Definition: StringRef.h:256
virtual const MCFixupKindInfo & getFixupKindInfo(MCFixupKind Kind) const
Get information on a fixup kind.
const uint32_t WasmMetadataVersion
Definition: Wasm.h:28
StringRef getSectionName() const
Definition: MCSectionWasm.h:59
FragmentType getKind() const
Definition: MCFragment.h:96
void write32le(void *P, uint32_t V)
Definition: Endian.h:418
Defines the object file and target independent interfaces used by the assembler backend to write nati...
Encode information on a single operation to perform on a byte sequence (e.g., an encoded instruction)...
Definition: MCFixup.h:77
unsigned getAlignment() const
Definition: MCSection.h:120
Export information to summary.
Is this fixup kind PCrelative? This is used by the assembler backend to evaluate fixup values in a ta...
MCContext & getContext() const
Definition: MCAssembler.h:284
const unsigned WASM_SYMBOL_UNDEFINED
Definition: Wasm.h:318
int64_t getConstant() const
Definition: MCValue.h:46
const MCSymbolRefExpr * getSymB() const
Definition: MCValue.h:48
std::string toString(Error E)
Write all error messages (if any) in E to a string.
Definition: Error.h:966
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:80
bool isSection() const
Definition: MCSymbolWasm.h:45
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:28
WasmTable Table
Definition: Wasm.h:115
Base class for the full range of assembler expressions which are needed for parsing.
Definition: MCExpr.h:35
The access may reference the value stored in memory.
StringRef Module
Definition: Wasm.h:109
Represent a reference to a symbol from inside an expression.
Definition: MCExpr.h:173
LLVM_NODISCARD bool empty() const
empty - Check if the string is empty.
Definition: StringRef.h:126
ELFYAML::ELF_STO Other
Definition: ELFYAML.cpp:877
const uint32_t WasmVersion
Definition: Wasm.h:26
Context object for machine code objects.
Definition: MCContext.h:65
bool isText() const
Definition: SectionKind.h:118
const wasm::WasmSignature * getSignature() const
Definition: MCSymbolWasm.h:85
uint32_t Attribute
Definition: Wasm.h:98
ArrayRef - Represent a constant reference to an array (0 or more elements consecutively in memory)...
Definition: APInt.h:32
std::string relocTypetoString(uint32_t type)
Definition: Wasm.cpp:27
LLVM_NODISCARD size_t size() const
size - Get the string size.
Definition: StringRef.h:130
uint32_t SigIndex
Definition: Wasm.h:113
Analysis containing CSE Info
Definition: CSEInfo.cpp:20
#define P(N)
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
Import information from summary.
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
const unsigned WASM_SYMBOL_VISIBILITY_HIDDEN
Definition: Wasm.h:317
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:148
This represents a section on wasm.
Definition: MCSectionWasm.h:27
static bool is64Bit(const char *name)
virtual void reset()
lifetime management
uint8_t ElemType
Definition: Wasm.h:69
const unsigned WASM_SYMBOL_BINDING_WEAK
Definition: Wasm.h:314
bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const
Get the offset of the given symbol, as computed in the current layout.
Definition: MCFragment.cpp:129
bool isTemporary() const
isTemporary - Check if this is an assembler temporary symbol.
Definition: MCSymbol.h:221
void pwrite(const char *Ptr, size_t Size, uint64_t Offset)
Definition: raw_ostream.h:366
std::unique_ptr< MCObjectWriter > createWasmObjectWriter(std::unique_ptr< MCWasmObjectTargetWriter > MOTW, raw_pwrite_stream &OS)
Construct a new Wasm writer instance.
const MCSymbolRefExpr * getSymA() const
Definition: MCValue.h:47
void reportError(SMLoc L, const Twine &Msg)
Definition: MCContext.cpp:686
static void addData(SmallVectorImpl< char > &DataBytes, MCSectionWasm &DataSection)
WasmEventType Event
Definition: Wasm.h:117
static void print(raw_ostream &Out, object::Archive::Kind Kind, T Val)
uint32_t getOffset() const
Definition: MCFixup.h:128
void writeSectionData(raw_ostream &OS, const MCSection *Section, const MCAsmLayout &Layout) const
Emit the section contents to OS.
const MCExpr * getSize() const
Definition: MCSymbolWasm.h:39
size_t size() const
Definition: SmallVector.h:52
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:40
uint64_t getFragmentOffset(const MCFragment *F) const
Get the offset of the given fragment inside its containing section.
Definition: MCFragment.cpp:77
PowerPC TLS Dynamic Call Fixup
const char WasmMagic[]
Definition: Wasm.h:24
SMLoc getLoc() const
Definition: MCFixup.h:195
bool isComdat() const
Definition: MCSymbolWasm.h:63
const unsigned WASM_SYMBOL_EXPLICIT_NAME
Definition: Wasm.h:320
MCAsmBackend & getBackend() const
Definition: MCAssembler.h:292
unsigned encodeULEB128(uint64_t Value, raw_ostream &OS, unsigned PadTo=0)
Utility function to encode a ULEB128 value to an output stream.
Definition: LEB128.h:80
const MCSymbol & getSymbol() const
Definition: MCExpr.h:344
unsigned encodeSLEB128(int64_t Value, raw_ostream &OS, unsigned PadTo=0)
Utility function to encode a SLEB128 value to an output stream.
Definition: LEB128.h:23
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:837
MCSymbol * getBeginSymbol()
Definition: MCSection.h:109
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
unsigned Log2_32(uint32_t Value)
Return the floor log base 2 of the specified value, -1 if the value is zero.
Definition: MathExtras.h:538
bool isDefined() const
isDefined - Check if this symbol is defined (i.e., it has an address).
Definition: MCSymbol.h:249
Target - Wrapper for Target specific information.
MCSection * getParent() const
Definition: MCFragment.h:98
bool hasInstructions() const
Does this fragment have instructions emitted into it? By default this is false, but specific fragment...
Definition: MCFragment.h:109
iterator insert(iterator I, T &&Elt)
Definition: SmallVector.h:467
bool isUsedInReloc() const
Definition: MCSymbol.h:215
static cl::opt< ITMode > IT(cl::desc("IT block support"), cl::Hidden, cl::init(DefaultIT), cl::ZeroOrMore, cl::values(clEnumValN(DefaultIT, "arm-default-it", "Generate IT block based on arch"), clEnumValN(RestrictedIT, "arm-restrict-it", "Disallow deprecated IT based on ARMv8"), clEnumValN(NoRestrictedIT, "arm-no-restrict-it", "Allow IT blocks based on ARMv7")))
Adapter to write values to a stream in a particular byte order.
Definition: EndianStream.h:51
uint64_t alignTo(uint64_t Size, Align A)
Returns a multiple of A needed to store Size bytes.
Definition: Alignment.h:126
WasmGlobalType Global
Definition: Wasm.h:114
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:214
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:332
uint32_t Size
Definition: Profile.cpp:46
symbol_range symbols()
Definition: MCAssembler.h:353
raw_ostream & operator<<(raw_ostream &OS, const APInt &I)
Definition: APInt.h:2045
StringRef getName() const
getName - Get the symbol name.
Definition: MCSymbol.h:204
An abstract base class for streams implementations that also support a pwrite operation.
Definition: raw_ostream.h:359
static MCFixupKind getKindForSize(unsigned Size, bool IsPCRel)
Return the generic fixup kind for a value with the given size.
Definition: MCFixup.h:135
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
const MCExpr * getVariableValue(bool SetUsed=true) const
getVariableValue - Get the value for variable symbols.
Definition: MCSymbol.h:302
void stable_sort(R &&Range)
Definition: STLExtras.h:1301
WasmDataReference DataRef
Definition: Wasm.h:186
LLVM Value Representation.
Definition: Value.h:73
Generic interface to target specific assembler backends.
Definition: MCAsmBackend.h:41
const char SectionName[]
Definition: AMDGPUPTNote.h:23
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:45
bool isEqual(const GCNRPTracker::LiveRegSet &S1, const GCNRPTracker::LiveRegSet &S2)
const MCExpr * getValue() const
Definition: MCFixup.h:131
const uint32_t WasmPageSize
Definition: Wasm.h:30
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
bool operator==(uint64_t V1, const APInt &V2)
Definition: APInt.h:1973
static const MCSymbolWasm * resolveSymbol(const MCSymbolWasm &Symbol)
const unsigned WASM_SYMBOL_EXPORTED
Definition: Wasm.h:319
#define LLVM_DEBUG(X)
Definition: Debug.h:122
static bool isInSymtab(const MCSymbolWasm &Sym)
void setIndex(uint32_t Value) const
Set the (implementation defined) index.
Definition: MCSymbol.h:318
StringRef Field
Definition: Wasm.h:110
MCFixupKind getKind() const
Definition: MCFixup.h:126
bool empty() const
empty - Check if the array is empty.
Definition: ArrayRef.h:143
bool isEvent() const
Definition: MCSymbolWasm.h:46
void resize(size_type N)
Definition: SmallVector.h:344