1//===- yaml2elf - Convert YAML to a ELF object file -----------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9///
10/// \file
11/// \brief The ELF component of yaml2obj.
12///
13//===----------------------------------------------------------------------===//
14
15#include "yaml2obj.h"
16#include "llvm/ADT/ArrayRef.h"
17#include "llvm/MC/StringTableBuilder.h"
18#include "llvm/Object/ELFObjectFile.h"
19#include "llvm/ObjectYAML/ELFYAML.h"
20#include "llvm/Support/ELF.h"
21#include "llvm/Support/MemoryBuffer.h"
22#include "llvm/Support/YAMLTraits.h"
23#include "llvm/Support/raw_ostream.h"
24
25using namespace llvm;
26
27// This class is used to build up a contiguous binary blob while keeping
28// track of an offset in the output (which notionally begins at
29// `InitialOffset`).
30namespace {
31class ContiguousBlobAccumulator {
32  const uint64_t InitialOffset;
33  SmallVector<char, 128> Buf;
34  raw_svector_ostream OS;
35
36  /// \returns The new offset.
37  uint64_t padToAlignment(unsigned Align) {
38    if (Align == 0)
39      Align = 1;
40    uint64_t CurrentOffset = InitialOffset + OS.tell();
41    uint64_t AlignedOffset = alignTo(CurrentOffset, Align);
42    for (; CurrentOffset != AlignedOffset; ++CurrentOffset)
43      OS.write('\0');
44    return AlignedOffset; // == CurrentOffset;
45  }
46
47public:
48  ContiguousBlobAccumulator(uint64_t InitialOffset_)
49      : InitialOffset(InitialOffset_), Buf(), OS(Buf) {}
50  template <class Integer>
51  raw_ostream &getOSAndAlignedOffset(Integer &Offset, unsigned Align) {
52    Offset = padToAlignment(Align);
53    return OS;
54  }
55  void writeBlobToStream(raw_ostream &Out) { Out << OS.str(); }
56};
57} // end anonymous namespace
58
59// Used to keep track of section and symbol names, so that in the YAML file
60// sections and symbols can be referenced by name instead of by index.
61namespace {
62class NameToIdxMap {
63  StringMap<int> Map;
64public:
65  /// \returns true if name is already present in the map.
66  bool addName(StringRef Name, unsigned i) {
67    return !Map.insert(std::make_pair(Name, (int)i)).second;
68  }
69  /// \returns true if name is not present in the map
70  bool lookup(StringRef Name, unsigned &Idx) const {
71    StringMap<int>::const_iterator I = Map.find(Name);
72    if (I == Map.end())
73      return true;
74    Idx = I->getValue();
75    return false;
76  }
77};
78} // end anonymous namespace
79
80template <class T>
81static size_t arrayDataSize(ArrayRef<T> A) {
82  return A.size() * sizeof(T);
83}
84
85template <class T>
86static void writeArrayData(raw_ostream &OS, ArrayRef<T> A) {
87  OS.write((const char *)A.data(), arrayDataSize(A));
88}
89
90template <class T>
91static void zero(T &Obj) {
92  memset(&Obj, 0, sizeof(Obj));
93}
94
95namespace {
96/// \brief "Single point of truth" for the ELF file construction.
97/// TODO: This class still has a ways to go before it is truly a "single
98/// point of truth".
99template <class ELFT>
100class ELFState {
101  typedef typename object::ELFFile<ELFT>::Elf_Ehdr Elf_Ehdr;
102  typedef typename object::ELFFile<ELFT>::Elf_Shdr Elf_Shdr;
103  typedef typename object::ELFFile<ELFT>::Elf_Sym Elf_Sym;
104  typedef typename object::ELFFile<ELFT>::Elf_Rel Elf_Rel;
105  typedef typename object::ELFFile<ELFT>::Elf_Rela Elf_Rela;
106
107  /// \brief The future ".strtab" section.
108  StringTableBuilder DotStrtab{StringTableBuilder::ELF};
109
110  /// \brief The future ".shstrtab" section.
111  StringTableBuilder DotShStrtab{StringTableBuilder::ELF};
112
113  NameToIdxMap SN2I;
114  NameToIdxMap SymN2I;
115  const ELFYAML::Object &Doc;
116
117  bool buildSectionIndex();
118  bool buildSymbolIndex(std::size_t &StartIndex,
119                        const std::vector<ELFYAML::Symbol> &Symbols);
120  void initELFHeader(Elf_Ehdr &Header);
121  bool initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
122                          ContiguousBlobAccumulator &CBA);
123  void initSymtabSectionHeader(Elf_Shdr &SHeader,
124                               ContiguousBlobAccumulator &CBA);
125  void initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
126                               StringTableBuilder &STB,
127                               ContiguousBlobAccumulator &CBA);
128  void addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
129                  std::vector<Elf_Sym> &Syms, unsigned SymbolBinding);
130  void writeSectionContent(Elf_Shdr &SHeader,
131                           const ELFYAML::RawContentSection &Section,
132                           ContiguousBlobAccumulator &CBA);
133  bool writeSectionContent(Elf_Shdr &SHeader,
134                           const ELFYAML::RelocationSection &Section,
135                           ContiguousBlobAccumulator &CBA);
136  bool writeSectionContent(Elf_Shdr &SHeader, const ELFYAML::Group &Group,
137                           ContiguousBlobAccumulator &CBA);
138  bool writeSectionContent(Elf_Shdr &SHeader,
139                           const ELFYAML::MipsABIFlags &Section,
140                           ContiguousBlobAccumulator &CBA);
141
142  // - SHT_NULL entry (placed first, i.e. 0'th entry)
143  // - symbol table (.symtab) (placed third to last)
144  // - string table (.strtab) (placed second to last)
145  // - section header string table (.shstrtab) (placed last)
146  unsigned getDotSymTabSecNo() const { return Doc.Sections.size() + 1; }
147  unsigned getDotStrTabSecNo() const { return Doc.Sections.size() + 2; }
148  unsigned getDotShStrTabSecNo() const { return Doc.Sections.size() + 3; }
149  unsigned getSectionCount() const { return Doc.Sections.size() + 4; }
150
151  ELFState(const ELFYAML::Object &D) : Doc(D) {}
152
153public:
154  static int writeELF(raw_ostream &OS, const ELFYAML::Object &Doc);
155};
156} // end anonymous namespace
157
158template <class ELFT>
159void ELFState<ELFT>::initELFHeader(Elf_Ehdr &Header) {
160  using namespace llvm::ELF;
161  zero(Header);
162  Header.e_ident[EI_MAG0] = 0x7f;
163  Header.e_ident[EI_MAG1] = 'E';
164  Header.e_ident[EI_MAG2] = 'L';
165  Header.e_ident[EI_MAG3] = 'F';
166  Header.e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
167  bool IsLittleEndian = ELFT::TargetEndianness == support::little;
168  Header.e_ident[EI_DATA] = IsLittleEndian ? ELFDATA2LSB : ELFDATA2MSB;
169  Header.e_ident[EI_VERSION] = EV_CURRENT;
170  Header.e_ident[EI_OSABI] = Doc.Header.OSABI;
171  Header.e_ident[EI_ABIVERSION] = 0;
172  Header.e_type = Doc.Header.Type;
173  Header.e_machine = Doc.Header.Machine;
174  Header.e_version = EV_CURRENT;
175  Header.e_entry = Doc.Header.Entry;
176  Header.e_flags = Doc.Header.Flags;
177  Header.e_ehsize = sizeof(Elf_Ehdr);
178  Header.e_shentsize = sizeof(Elf_Shdr);
179  // Immediately following the ELF header.
180  Header.e_shoff = sizeof(Header);
181  Header.e_shnum = getSectionCount();
182  Header.e_shstrndx = getDotShStrTabSecNo();
183}
184
185template <class ELFT>
186bool ELFState<ELFT>::initSectionHeaders(std::vector<Elf_Shdr> &SHeaders,
187                                        ContiguousBlobAccumulator &CBA) {
188  // Ensure SHN_UNDEF entry is present. An all-zero section header is a
189  // valid SHN_UNDEF entry since SHT_NULL == 0.
190  Elf_Shdr SHeader;
191  zero(SHeader);
192  SHeaders.push_back(SHeader);
193
194  for (const auto &Sec : Doc.Sections)
195    DotShStrtab.add(Sec->Name);
196  DotShStrtab.finalize();
197
198  for (const auto &Sec : Doc.Sections) {
199    zero(SHeader);
200    SHeader.sh_name = DotShStrtab.getOffset(Sec->Name);
201    SHeader.sh_type = Sec->Type;
202    SHeader.sh_flags = Sec->Flags;
203    SHeader.sh_addr = Sec->Address;
204    SHeader.sh_addralign = Sec->AddressAlign;
205
206    if (!Sec->Link.empty()) {
207      unsigned Index;
208      if (SN2I.lookup(Sec->Link, Index)) {
209        errs() << "error: Unknown section referenced: '" << Sec->Link
210               << "' at YAML section '" << Sec->Name << "'.\n";
211        return false;
212      }
213      SHeader.sh_link = Index;
214    }
215
216    if (auto S = dyn_cast<ELFYAML::RawContentSection>(Sec.get()))
217      writeSectionContent(SHeader, *S, CBA);
218    else if (auto S = dyn_cast<ELFYAML::RelocationSection>(Sec.get())) {
219      if (S->Link.empty())
220        // For relocation section set link to .symtab by default.
221        SHeader.sh_link = getDotSymTabSecNo();
222
223      unsigned Index;
224      if (SN2I.lookup(S->Info, Index)) {
225        if (S->Info.getAsInteger(0, Index)) {
226          errs() << "error: Unknown section referenced: '" << S->Info
227                 << "' at YAML section '" << S->Name << "'.\n";
228          return false;
229        }
230      }
231      SHeader.sh_info = Index;
232
233      if (!writeSectionContent(SHeader, *S, CBA))
234        return false;
235    } else if (auto S = dyn_cast<ELFYAML::Group>(Sec.get())) {
236      unsigned SymIdx;
237      if (SymN2I.lookup(S->Info, SymIdx)) {
238        errs() << "error: Unknown symbol referenced: '" << S->Info
239               << "' at YAML section '" << S->Name << "'.\n";
240        return false;
241      }
242      SHeader.sh_info = SymIdx;
243      if (!writeSectionContent(SHeader, *S, CBA))
244        return false;
245    } else if (auto S = dyn_cast<ELFYAML::MipsABIFlags>(Sec.get())) {
246      if (!writeSectionContent(SHeader, *S, CBA))
247        return false;
248    } else if (auto S = dyn_cast<ELFYAML::NoBitsSection>(Sec.get())) {
249      SHeader.sh_entsize = 0;
250      SHeader.sh_size = S->Size;
251      // SHT_NOBITS section does not have content
252      // so just to setup the section offset.
253      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
254    } else
255      llvm_unreachable("Unknown section type");
256
257    SHeaders.push_back(SHeader);
258  }
259  return true;
260}
261
262template <class ELFT>
263void ELFState<ELFT>::initSymtabSectionHeader(Elf_Shdr &SHeader,
264                                             ContiguousBlobAccumulator &CBA) {
265  zero(SHeader);
266  SHeader.sh_name = DotShStrtab.getOffset(".symtab");
267  SHeader.sh_type = ELF::SHT_SYMTAB;
268  SHeader.sh_link = getDotStrTabSecNo();
269  // One greater than symbol table index of the last local symbol.
270  SHeader.sh_info = Doc.Symbols.Local.size() + 1;
271  SHeader.sh_entsize = sizeof(Elf_Sym);
272  SHeader.sh_addralign = 8;
273
274  std::vector<Elf_Sym> Syms;
275  {
276    // Ensure STN_UNDEF is present
277    Elf_Sym Sym;
278    zero(Sym);
279    Syms.push_back(Sym);
280  }
281
282  // Add symbol names to .strtab.
283  for (const auto &Sym : Doc.Symbols.Local)
284    DotStrtab.add(Sym.Name);
285  for (const auto &Sym : Doc.Symbols.Global)
286    DotStrtab.add(Sym.Name);
287  for (const auto &Sym : Doc.Symbols.Weak)
288    DotStrtab.add(Sym.Name);
289  DotStrtab.finalize();
290
291  addSymbols(Doc.Symbols.Local, Syms, ELF::STB_LOCAL);
292  addSymbols(Doc.Symbols.Global, Syms, ELF::STB_GLOBAL);
293  addSymbols(Doc.Symbols.Weak, Syms, ELF::STB_WEAK);
294
295  writeArrayData(
296      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign),
297      makeArrayRef(Syms));
298  SHeader.sh_size = arrayDataSize(makeArrayRef(Syms));
299}
300
301template <class ELFT>
302void ELFState<ELFT>::initStrtabSectionHeader(Elf_Shdr &SHeader, StringRef Name,
303                                             StringTableBuilder &STB,
304                                             ContiguousBlobAccumulator &CBA) {
305  zero(SHeader);
306  SHeader.sh_name = DotShStrtab.getOffset(Name);
307  SHeader.sh_type = ELF::SHT_STRTAB;
308  CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign)
309      << STB.data();
310  SHeader.sh_size = STB.data().size();
311  SHeader.sh_addralign = 1;
312}
313
314template <class ELFT>
315void ELFState<ELFT>::addSymbols(const std::vector<ELFYAML::Symbol> &Symbols,
316                                std::vector<Elf_Sym> &Syms,
317                                unsigned SymbolBinding) {
318  for (const auto &Sym : Symbols) {
319    Elf_Sym Symbol;
320    zero(Symbol);
321    if (!Sym.Name.empty())
322      Symbol.st_name = DotStrtab.getOffset(Sym.Name);
323    Symbol.setBindingAndType(SymbolBinding, Sym.Type);
324    if (!Sym.Section.empty()) {
325      unsigned Index;
326      if (SN2I.lookup(Sym.Section, Index)) {
327        errs() << "error: Unknown section referenced: '" << Sym.Section
328               << "' by YAML symbol " << Sym.Name << ".\n";
329        exit(1);
330      }
331      Symbol.st_shndx = Index;
332    } // else Symbol.st_shndex == SHN_UNDEF (== 0), since it was zero'd earlier.
333    Symbol.st_value = Sym.Value;
334    Symbol.st_other = Sym.Other;
335    Symbol.st_size = Sym.Size;
336    Syms.push_back(Symbol);
337  }
338}
339
340template <class ELFT>
341void
342ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
343                                    const ELFYAML::RawContentSection &Section,
344                                    ContiguousBlobAccumulator &CBA) {
345  assert(Section.Size >= Section.Content.binary_size() &&
346         "Section size and section content are inconsistent");
347  raw_ostream &OS =
348      CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
349  Section.Content.writeAsBinary(OS);
350  for (auto i = Section.Content.binary_size(); i < Section.Size; ++i)
351    OS.write(0);
352  SHeader.sh_entsize = 0;
353  SHeader.sh_size = Section.Size;
354}
355
356static bool isMips64EL(const ELFYAML::Object &Doc) {
357  return Doc.Header.Machine == ELFYAML::ELF_EM(llvm::ELF::EM_MIPS) &&
358         Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64) &&
359         Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
360}
361
362template <class ELFT>
363bool
364ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
365                                    const ELFYAML::RelocationSection &Section,
366                                    ContiguousBlobAccumulator &CBA) {
367  assert((Section.Type == llvm::ELF::SHT_REL ||
368          Section.Type == llvm::ELF::SHT_RELA) &&
369         "Section type is not SHT_REL nor SHT_RELA");
370
371  bool IsRela = Section.Type == llvm::ELF::SHT_RELA;
372  SHeader.sh_entsize = IsRela ? sizeof(Elf_Rela) : sizeof(Elf_Rel);
373  SHeader.sh_size = SHeader.sh_entsize * Section.Relocations.size();
374
375  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
376
377  for (const auto &Rel : Section.Relocations) {
378    unsigned SymIdx = 0;
379    // Some special relocation, R_ARM_v4BX for instance, does not have
380    // an external reference.  So it ignores the return value of lookup()
381    // here.
382    SymN2I.lookup(Rel.Symbol, SymIdx);
383
384    if (IsRela) {
385      Elf_Rela REntry;
386      zero(REntry);
387      REntry.r_offset = Rel.Offset;
388      REntry.r_addend = Rel.Addend;
389      REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
390      OS.write((const char *)&REntry, sizeof(REntry));
391    } else {
392      Elf_Rel REntry;
393      zero(REntry);
394      REntry.r_offset = Rel.Offset;
395      REntry.setSymbolAndType(SymIdx, Rel.Type, isMips64EL(Doc));
396      OS.write((const char *)&REntry, sizeof(REntry));
397    }
398  }
399  return true;
400}
401
402template <class ELFT>
403bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
404                                         const ELFYAML::Group &Section,
405                                         ContiguousBlobAccumulator &CBA) {
406  typedef typename object::ELFFile<ELFT>::Elf_Word Elf_Word;
407  assert(Section.Type == llvm::ELF::SHT_GROUP &&
408         "Section type is not SHT_GROUP");
409
410  SHeader.sh_entsize = sizeof(Elf_Word);
411  SHeader.sh_size = SHeader.sh_entsize * Section.Members.size();
412
413  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
414
415  for (auto member : Section.Members) {
416    Elf_Word SIdx;
417    unsigned int sectionIndex = 0;
418    if (member.sectionNameOrType == "GRP_COMDAT")
419      sectionIndex = llvm::ELF::GRP_COMDAT;
420    else if (SN2I.lookup(member.sectionNameOrType, sectionIndex)) {
421      errs() << "error: Unknown section referenced: '"
422             << member.sectionNameOrType << "' at YAML section' "
423             << Section.Name << "\n";
424      return false;
425    }
426    SIdx = sectionIndex;
427    OS.write((const char *)&SIdx, sizeof(SIdx));
428  }
429  return true;
430}
431
432template <class ELFT>
433bool ELFState<ELFT>::writeSectionContent(Elf_Shdr &SHeader,
434                                         const ELFYAML::MipsABIFlags &Section,
435                                         ContiguousBlobAccumulator &CBA) {
436  assert(Section.Type == llvm::ELF::SHT_MIPS_ABIFLAGS &&
437         "Section type is not SHT_MIPS_ABIFLAGS");
438
439  object::Elf_Mips_ABIFlags<ELFT> Flags;
440  zero(Flags);
441  SHeader.sh_entsize = sizeof(Flags);
442  SHeader.sh_size = SHeader.sh_entsize;
443
444  auto &OS = CBA.getOSAndAlignedOffset(SHeader.sh_offset, SHeader.sh_addralign);
445  Flags.version = Section.Version;
446  Flags.isa_level = Section.ISALevel;
447  Flags.isa_rev = Section.ISARevision;
448  Flags.gpr_size = Section.GPRSize;
449  Flags.cpr1_size = Section.CPR1Size;
450  Flags.cpr2_size = Section.CPR2Size;
451  Flags.fp_abi = Section.FpABI;
452  Flags.isa_ext = Section.ISAExtension;
453  Flags.ases = Section.ASEs;
454  Flags.flags1 = Section.Flags1;
455  Flags.flags2 = Section.Flags2;
456  OS.write((const char *)&Flags, sizeof(Flags));
457
458  return true;
459}
460
461template <class ELFT> bool ELFState<ELFT>::buildSectionIndex() {
462  SN2I.addName(".symtab", getDotSymTabSecNo());
463  SN2I.addName(".strtab", getDotStrTabSecNo());
464  SN2I.addName(".shstrtab", getDotShStrTabSecNo());
465
466  for (unsigned i = 0, e = Doc.Sections.size(); i != e; ++i) {
467    StringRef Name = Doc.Sections[i]->Name;
468    if (Name.empty())
469      continue;
470    // "+ 1" to take into account the SHT_NULL entry.
471    if (SN2I.addName(Name, i + 1)) {
472      errs() << "error: Repeated section name: '" << Name
473             << "' at YAML section number " << i << ".\n";
474      return false;
475    }
476  }
477  return true;
478}
479
480template <class ELFT>
481bool
482ELFState<ELFT>::buildSymbolIndex(std::size_t &StartIndex,
483                                 const std::vector<ELFYAML::Symbol> &Symbols) {
484  for (const auto &Sym : Symbols) {
485    ++StartIndex;
486    if (Sym.Name.empty())
487      continue;
488    if (SymN2I.addName(Sym.Name, StartIndex)) {
489      errs() << "error: Repeated symbol name: '" << Sym.Name << "'.\n";
490      return false;
491    }
492  }
493  return true;
494}
495
496template <class ELFT>
497int ELFState<ELFT>::writeELF(raw_ostream &OS, const ELFYAML::Object &Doc) {
498  ELFState<ELFT> State(Doc);
499  if (!State.buildSectionIndex())
500    return 1;
501
502  std::size_t StartSymIndex = 0;
503  if (!State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Local) ||
504      !State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Global) ||
505      !State.buildSymbolIndex(StartSymIndex, Doc.Symbols.Weak))
506    return 1;
507
508  Elf_Ehdr Header;
509  State.initELFHeader(Header);
510
511  // TODO: Flesh out section header support.
512  // TODO: Program headers.
513
514  // XXX: This offset is tightly coupled with the order that we write
515  // things to `OS`.
516  const size_t SectionContentBeginOffset =
517      Header.e_ehsize + Header.e_shentsize * Header.e_shnum;
518  ContiguousBlobAccumulator CBA(SectionContentBeginOffset);
519
520  // Doc might not contain .symtab, .strtab and .shstrtab sections,
521  // but we will emit them, so make sure to add them to ShStrTabSHeader.
522  State.DotShStrtab.add(".symtab");
523  State.DotShStrtab.add(".strtab");
524  State.DotShStrtab.add(".shstrtab");
525
526  std::vector<Elf_Shdr> SHeaders;
527  if(!State.initSectionHeaders(SHeaders, CBA))
528    return 1;
529
530  // .symtab section.
531  Elf_Shdr SymtabSHeader;
532  State.initSymtabSectionHeader(SymtabSHeader, CBA);
533  SHeaders.push_back(SymtabSHeader);
534
535  // .strtab string table header.
536  Elf_Shdr DotStrTabSHeader;
537  State.initStrtabSectionHeader(DotStrTabSHeader, ".strtab", State.DotStrtab,
538                                CBA);
539  SHeaders.push_back(DotStrTabSHeader);
540
541  // .shstrtab string table header.
542  Elf_Shdr ShStrTabSHeader;
543  State.initStrtabSectionHeader(ShStrTabSHeader, ".shstrtab", State.DotShStrtab,
544                                CBA);
545  SHeaders.push_back(ShStrTabSHeader);
546
547  OS.write((const char *)&Header, sizeof(Header));
548  writeArrayData(OS, makeArrayRef(SHeaders));
549  CBA.writeBlobToStream(OS);
550  return 0;
551}
552
553static bool is64Bit(const ELFYAML::Object &Doc) {
554  return Doc.Header.Class == ELFYAML::ELF_ELFCLASS(ELF::ELFCLASS64);
555}
556
557static bool isLittleEndian(const ELFYAML::Object &Doc) {
558  return Doc.Header.Data == ELFYAML::ELF_ELFDATA(ELF::ELFDATA2LSB);
559}
560
561int yaml2elf(llvm::ELFYAML::Object &Doc, raw_ostream &Out) {
562  using object::ELFType;
563  typedef ELFType<support::little, true> LE64;
564  typedef ELFType<support::big, true> BE64;
565  typedef ELFType<support::little, false> LE32;
566  typedef ELFType<support::big, false> BE32;
567  if (is64Bit(Doc)) {
568    if (isLittleEndian(Doc))
569      return ELFState<LE64>::writeELF(Out, Doc);
570    else
571      return ELFState<BE64>::writeELF(Out, Doc);
572  } else {
573    if (isLittleEndian(Doc))
574      return ELFState<LE32>::writeELF(Out, Doc);
575    else
576      return ELFState<BE32>::writeELF(Out, Doc);
577  }
578}
579