void MachObjectWriter::bindIndirectSymbols(MCAssembler &Asm) {
// This is the point where 'as' creates actual symbols for indirect symbols
// (in the following two passes). It would be easier for us to do this sooner
// when we see the attribute, but that makes getting the order in the symbol
// table much more complicated than it is worth.
//
// FIXME: Revisit this when the dust settles.
// Report errors for use of .indirect_symbol not in a symbol pointer section
// or stub section.
for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it) {
const MCSectionMachO &Section = cast<MCSectionMachO>(*it->Section);
if (Section.getType() != MachO::S_NON_LAZY_SYMBOL_POINTERS &&
Section.getType() != MachO::S_LAZY_SYMBOL_POINTERS &&
Section.getType() != MachO::S_SYMBOL_STUBS) {
MCSymbol &Symbol = *it->Symbol;
report_fatal_error("indirect symbol '" + Symbol.getName() +
"' not in a symbol pointer or stub section");
}
}
// Bind non-lazy symbol pointers first.
unsigned IndirectIndex = 0;
for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
const MCSectionMachO &Section = cast<MCSectionMachO>(*it->Section);
if (Section.getType() != MachO::S_NON_LAZY_SYMBOL_POINTERS)
continue;
// Initialize the section indirect symbol base, if necessary.
IndirectSymBase.insert(std::make_pair(it->Section, IndirectIndex));
Asm.registerSymbol(*it->Symbol);
}
// Then lazy symbol pointers and symbol stubs.
IndirectIndex = 0;
for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
const MCSectionMachO &Section = cast<MCSectionMachO>(*it->Section);
if (Section.getType() != MachO::S_LAZY_SYMBOL_POINTERS &&
Section.getType() != MachO::S_SYMBOL_STUBS)
continue;
// Initialize the section indirect symbol base, if necessary.
IndirectSymBase.insert(std::make_pair(it->Section, IndirectIndex));
// Set the symbol type to undefined lazy, but only on construction.
//
// FIXME: Do not hardcode.
bool Created;
Asm.registerSymbol(*it->Symbol, &Created);
if (Created)
cast<MCSymbolMachO>(it->Symbol)->setReferenceTypeUndefinedLazy(true);
}
}
void ELFObjectWriter::writeObject(MCAssembler &Asm,
const MCAsmLayout &Layout) {
MCContext &Ctx = Asm.getContext();
MCSectionELF *StrtabSection =
Ctx.getELFSection(".strtab", ELF::SHT_STRTAB, 0);
StringTableIndex = addToSectionTable(StrtabSection);
RevGroupMapTy RevGroupMap;
SectionIndexMapTy SectionIndexMap;
std::map<const MCSymbol *, std::vector<const MCSectionELF *>> GroupMembers;
// Write out the ELF header ...
writeHeader(Asm);
// ... then the sections ...
SectionOffsetsTy SectionOffsets;
std::vector<MCSectionELF *> Groups;
std::vector<MCSectionELF *> Relocations;
for (MCSection &Sec : Asm) {
MCSectionELF &Section = static_cast<MCSectionELF &>(Sec);
align(Section.getAlignment());
// Remember the offset into the file for this section.
uint64_t SecStart = getStream().tell();
const MCSymbolELF *SignatureSymbol = Section.getGroup();
writeSectionData(Asm, Section, Layout);
uint64_t SecEnd = getStream().tell();
SectionOffsets[&Section] = std::make_pair(SecStart, SecEnd);
MCSectionELF *RelSection = createRelocationSection(Ctx, Section);
if (SignatureSymbol) {
Asm.registerSymbol(*SignatureSymbol);
unsigned &GroupIdx = RevGroupMap[SignatureSymbol];
if (!GroupIdx) {
MCSectionELF *Group = Ctx.createELFGroupSection(SignatureSymbol);
GroupIdx = addToSectionTable(Group);
Group->setAlignment(4);
Groups.push_back(Group);
}
std::vector<const MCSectionELF *> &Members =
GroupMembers[SignatureSymbol];
Members.push_back(&Section);
if (RelSection)
Members.push_back(RelSection);
}
SectionIndexMap[&Section] = addToSectionTable(&Section);
if (RelSection) {
SectionIndexMap[RelSection] = addToSectionTable(RelSection);
Relocations.push_back(RelSection);
}
}
for (MCSectionELF *Group : Groups) {
align(Group->getAlignment());
// Remember the offset into the file for this section.
uint64_t SecStart = getStream().tell();
const MCSymbol *SignatureSymbol = Group->getGroup();
assert(SignatureSymbol);
write(uint32_t(ELF::GRP_COMDAT));
for (const MCSectionELF *Member : GroupMembers[SignatureSymbol]) {
uint32_t SecIndex = SectionIndexMap.lookup(Member);
write(SecIndex);
}
uint64_t SecEnd = getStream().tell();
SectionOffsets[Group] = std::make_pair(SecStart, SecEnd);
}
// Compute symbol table information.
computeSymbolTable(Asm, Layout, SectionIndexMap, RevGroupMap, SectionOffsets);
for (MCSectionELF *RelSection : Relocations) {
align(RelSection->getAlignment());
// Remember the offset into the file for this section.
uint64_t SecStart = getStream().tell();
writeRelocations(Asm,
cast<MCSectionELF>(*RelSection->getAssociatedSection()));
uint64_t SecEnd = getStream().tell();
SectionOffsets[RelSection] = std::make_pair(SecStart, SecEnd);
}
{
uint64_t SecStart = getStream().tell();
const MCSectionELF *Sec = createStringTable(Ctx);
uint64_t SecEnd = getStream().tell();
SectionOffsets[Sec] = std::make_pair(SecStart, SecEnd);
}
uint64_t NaturalAlignment = is64Bit() ? 8 : 4;
align(NaturalAlignment);
const uint64_t SectionHeaderOffset = getStream().tell();
// ... then the section header table ...
writeSectionHeader(Layout, SectionIndexMap, SectionOffsets);
uint16_t NumSections = (SectionTable.size() + 1 >= ELF::SHN_LORESERVE)
? (uint16_t)ELF::SHN_UNDEF
: SectionTable.size() + 1;
if (sys::IsLittleEndianHost != IsLittleEndian)
sys::swapByteOrder(NumSections);
unsigned NumSectionsOffset;
if (is64Bit()) {
uint64_t Val = SectionHeaderOffset;
if (sys::IsLittleEndianHost != IsLittleEndian)
sys::swapByteOrder(Val);
getStream().pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
offsetof(ELF::Elf64_Ehdr, e_shoff));
NumSectionsOffset = offsetof(ELF::Elf64_Ehdr, e_shnum);
} else {
uint32_t Val = SectionHeaderOffset;
if (sys::IsLittleEndianHost != IsLittleEndian)
sys::swapByteOrder(Val);
getStream().pwrite(reinterpret_cast<char *>(&Val), sizeof(Val),
offsetof(ELF::Elf32_Ehdr, e_shoff));
NumSectionsOffset = offsetof(ELF::Elf32_Ehdr, e_shnum);
}
getStream().pwrite(reinterpret_cast<char *>(&NumSections),
sizeof(NumSections), NumSectionsOffset);
}
