MCSectionMachO.h

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//===- MCSectionMachO.h - MachO Machine Code Sections -----------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file declares the MCSectionMachO class.
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_MC_MCSECTIONMACHO_H
#define LLVM_MC_MCSECTIONMACHO_H
 
#include "llvm/ADT/StringRef.h"
#include "llvm/BinaryFormat/MachO.h"
#include "llvm/MC/MCSection.h"
 
namespace llvm {
 
/// This represents a section on a Mach-O system (used by Mac OS X).  On a Mac
/// system, these are also described in /usr/include/mach-o/loader.h.
class MCSectionMachO final : public MCSection {
  char SegmentName[16];  // Not necessarily null terminated!
 
  /// This is the SECTION_TYPE and SECTION_ATTRIBUTES field of a section, drawn
  /// from the enums below.
  unsigned TypeAndAttributes;
 
  /// The 'reserved2' field of a section, used to represent the size of stubs,
  /// for example.
  unsigned Reserved2;
 
  // The index of this section in MachObjectWriter::SectionOrder, which is
  // different from MCSection::Ordinal.
  unsigned LayoutOrder = 0;
 
  // The defining non-temporary symbol for each fragment.
  SmallVector<const MCSymbol *, 0> Atoms;
 
  MCSectionMachO(StringRef Segment, StringRef Section, unsigned TAA,
                 unsigned reserved2, SectionKind K, MCSymbol *Begin);
  friend class MCContext;
public:
 
  StringRef getSegmentName() const {
    // SegmentName is not necessarily null terminated!
    if (SegmentName[15])
      return StringRef(SegmentName, 16);
    return StringRef(SegmentName);
  }
 
  unsigned getTypeAndAttributes() const { return TypeAndAttributes; }
  unsigned getStubSize() const { return Reserved2; }
 
  MachO::SectionType getType() const {
    return static_cast<MachO::SectionType>(TypeAndAttributes &
                                           MachO::SECTION_TYPE);
  }
  bool hasAttribute(unsigned Value) const {
    return (TypeAndAttributes & Value) != 0;
  }
 
  /// Parse the section specifier indicated by "Spec". This is a string that can
  /// appear after a .section directive in a mach-o flavored .s file.  If
  /// successful, this fills in the specified Out parameters and returns an
  /// empty string.  When an invalid section specifier is present, this returns
  /// an Error indicating the problem. If no TAA was parsed, TAA is not altered,
  /// and TAAWasSet becomes false.
  static Error ParseSectionSpecifier(StringRef Spec,      // In.
                                     StringRef &Segment,  // Out.
                                     StringRef &Section,  // Out.
                                     unsigned &TAA,       // Out.
                                     bool &TAAParsed,     // Out.
                                     unsigned &StubSize); // Out.
 
  void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
                            raw_ostream &OS,
                            uint32_t Subsection) const override;
  bool useCodeAlign() const override;
 
  void allocAtoms();
  const MCSymbol *getAtom(size_t I) const;
  void setAtom(size_t I, const MCSymbol *Sym);
 
  unsigned getLayoutOrder() const { return LayoutOrder; }
  void setLayoutOrder(unsigned Value) { LayoutOrder = Value; }
 
  static bool classof(const MCSection *S) {
    return S->getVariant() == SV_MachO;
  }
};
 
} // end namespace llvm
 
#endif