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  1. //===- MCSectionELF.h - ELF Machine Code Sections ---------------*- C++ -*-===//
  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 declares the MCSectionELF class.
  10. //
  11. //===----------------------------------------------------------------------===//
  12.  
  13. #ifndef LLVM_MC_MCSECTIONELF_H
  14. #define LLVM_MC_MCSECTIONELF_H
  15.  
  16. #include "llvm/ADT/PointerIntPair.h"
  17. #include "llvm/ADT/StringRef.h"
  18. #include "llvm/MC/MCSection.h"
  19. #include "llvm/MC/MCSymbolELF.h"
  20. #include "llvm/MC/SectionKind.h"
  21.  
  22. namespace llvm {
  23.  
  24. /// This represents a section on linux, lots of unix variants and some bare
  25. /// metal systems.
  26. class MCSectionELF final : public MCSection {
  27.   /// This is the sh_type field of a section, drawn from the enums below.
  28.   unsigned Type;
  29.  
  30.   /// This is the sh_flags field of a section, drawn from the enums below.
  31.   unsigned Flags;
  32.  
  33.   unsigned UniqueID;
  34.  
  35.   /// The size of each entry in this section. This size only makes sense for
  36.   /// sections that contain fixed-sized entries. If a section does not contain
  37.   /// fixed-sized entries 'EntrySize' will be 0.
  38.   unsigned EntrySize;
  39.  
  40.   /// The section group signature symbol (if not null) and a bool indicating
  41.   /// whether this is a GRP_COMDAT group.
  42.   const PointerIntPair<const MCSymbolELF *, 1, bool> Group;
  43.  
  44.   /// Used by SHF_LINK_ORDER. If non-null, the sh_link field will be set to the
  45.   /// section header index of the section where LinkedToSym is defined.
  46.   const MCSymbol *LinkedToSym;
  47.  
  48. private:
  49.   friend class MCContext;
  50.  
  51.   // The storage of Name is owned by MCContext's ELFUniquingMap.
  52.   MCSectionELF(StringRef Name, unsigned type, unsigned flags, SectionKind K,
  53.                unsigned entrySize, const MCSymbolELF *group, bool IsComdat,
  54.                unsigned UniqueID, MCSymbol *Begin,
  55.                const MCSymbolELF *LinkedToSym)
  56.       : MCSection(SV_ELF, Name, K, Begin), Type(type), Flags(flags),
  57.         UniqueID(UniqueID), EntrySize(entrySize), Group(group, IsComdat),
  58.         LinkedToSym(LinkedToSym) {
  59.     if (Group.getPointer())
  60.       Group.getPointer()->setIsSignature();
  61.   }
  62.  
  63.   // TODO Delete after we stop supporting generation of GNU-style .zdebug_*
  64.   // sections.
  65.   void setSectionName(StringRef Name) { this->Name = Name; }
  66.  
  67. public:
  68.   /// Decides whether a '.section' directive should be printed before the
  69.   /// section name
  70.   bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
  71.  
  72.   unsigned getType() const { return Type; }
  73.   unsigned getFlags() const { return Flags; }
  74.   unsigned getEntrySize() const { return EntrySize; }
  75.   void setFlags(unsigned F) { Flags = F; }
  76.   const MCSymbolELF *getGroup() const { return Group.getPointer(); }
  77.   bool isComdat() const { return Group.getInt(); }
  78.  
  79.   void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
  80.                             raw_ostream &OS,
  81.                             const MCExpr *Subsection) const override;
  82.   bool useCodeAlign() const override;
  83.   bool isVirtualSection() const override;
  84.   StringRef getVirtualSectionKind() const override;
  85.  
  86.   bool isUnique() const { return UniqueID != NonUniqueID; }
  87.   unsigned getUniqueID() const { return UniqueID; }
  88.  
  89.   const MCSection *getLinkedToSection() const {
  90.     return &LinkedToSym->getSection();
  91.   }
  92.   const MCSymbol *getLinkedToSymbol() const { return LinkedToSym; }
  93.  
  94.   static bool classof(const MCSection *S) {
  95.     return S->getVariant() == SV_ELF;
  96.   }
  97. };
  98.  
  99. } // end namespace llvm
  100.  
  101. #endif // LLVM_MC_MCSECTIONELF_H
  102.