C++ MCSectionMachO类代码示例

static bool canGoAfterDWARF(const MCSectionMachO &MSec) {
  // These sections are created by the assembler itself after the end of
  // the .s file.
  StringRef SegName = MSec.getSegmentName();
  StringRef SecName = MSec.getSectionName();

  if (SegName == "__LD" && SecName == "__compact_unwind")
    return true;

  if (SegName == "__IMPORT") {
    if (SecName == "__jump_table")
      return true;

    if (SecName == "__pointers")
      return true;
  }

  if (SegName == "__TEXT" && SecName == "__eh_frame")
    return true;

  if (SegName == "__DATA" && SecName == "__nl_symbol_ptr")
    return true;

  return false;
}

static bool canUseLocalRelocation(const MCSectionMachO &Section,
                                  const MCSymbol &Symbol, unsigned Log2Size) {
    // Debug info sections can use local relocations.
    if (Section.hasAttribute(MachO::S_ATTR_DEBUG))
        return true;

    // Otherwise, only pointer sized relocations are supported.
    if (Log2Size != 3)
        return false;

    // But only if they don't point to a few forbidden sections.
    if (!Symbol.isInSection())
        return true;
    const MCSectionMachO &RefSec = cast<MCSectionMachO>(Symbol.getSection());
    if (RefSec.getType() == MachO::S_CSTRING_LITERALS)
        return false;

    if (RefSec.getSegmentName() == "__DATA" &&
            RefSec.getSectionName() == "__cfstring")
        return false;

    if (RefSec.getSegmentName() == "__DATA" &&
            RefSec.getSectionName() == "__objc_classrefs")
        return false;

    return true;
}

static bool canUseLocalRelocation(const MCSectionMachO &Section,
                                  const MCSymbol &Symbol, unsigned Log2Size) {
  // Debug info sections can use local relocations.
  if (Section.hasAttribute(MachO::S_ATTR_DEBUG))
    return true;

  // Otherwise, only pointer sized relocations are supported.
  if (Log2Size != 3)
    return false;

  // But only if they don't point to a few forbidden sections.
  if (!Symbol.isInSection())
    return true;
  const MCSectionMachO &RefSec = cast<MCSectionMachO>(Symbol.getSection());
  if (RefSec.getType() == MachO::S_CSTRING_LITERALS)
    return false;

  if (RefSec.getSegmentName() == "__DATA" &&
      RefSec.getSectionName() == "__objc_classrefs")
    return false;

  // FIXME: ld64 currently handles internal pointer-sized relocations
  // incorrectly (applying the addend twice). We should be able to return true
  // unconditionally by this point when that's fixed.
  return false;
}

MCSection *TargetLoweringObjectFileMachO::getExplicitSectionGlobal(
    const GlobalValue *GV, SectionKind Kind, Mangler &Mang,
    const TargetMachine &TM) const {
  // Parse the section specifier and create it if valid.
  StringRef Segment, Section;
  unsigned TAA = 0, StubSize = 0;
  bool TAAParsed;

  checkMachOComdat(GV);

  std::string ErrorCode =
    MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
                                          TAA, TAAParsed, StubSize);
  if (!ErrorCode.empty()) {
    // If invalid, report the error with report_fatal_error.
    report_fatal_error("Global variable '" + GV->getName() +
                       "' has an invalid section specifier '" +
                       GV->getSection() + "': " + ErrorCode + ".");
  }

  // Get the section.
  MCSectionMachO *S =
      getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);

  // If TAA wasn't set by ParseSectionSpecifier() above,
  // use the value returned by getMachOSection() as a default.
  if (!TAAParsed)
    TAA = S->getTypeAndAttributes();

  // Okay, now that we got the section, verify that the TAA & StubSize agree.
  // If the user declared multiple globals with different section flags, we need
  // to reject it here.
  if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
    // If invalid, report the error with report_fatal_error.
    report_fatal_error("Global variable '" + GV->getName() +
                       "' section type or attributes does not match previous"
                       " section specifier");
  }

  return S;
}