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      1 //===- MCSectionELF.h - ELF Machine Code Sections ---------------*- C++ -*-===//
      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 // This file declares the MCSectionELF class.
     11 //
     12 //===----------------------------------------------------------------------===//
     13 
     14 #ifndef LLVM_MC_MCSECTIONELF_H
     15 #define LLVM_MC_MCSECTIONELF_H
     16 
     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 class MCSymbol;
     25 
     26 /// This represents a section on linux, lots of unix variants and some bare
     27 /// metal systems.
     28 class MCSectionELF final : public MCSection {
     29   /// This is the name of the section.  The referenced memory is owned by
     30   /// TargetLoweringObjectFileELF's ELFUniqueMap.
     31   StringRef SectionName;
     32 
     33   /// This is the sh_type field of a section, drawn from the enums below.
     34   unsigned Type;
     35 
     36   /// This is the sh_flags field of a section, drawn from the enums below.
     37   unsigned Flags;
     38 
     39   unsigned UniqueID;
     40 
     41   /// The size of each entry in this section. This size only makes sense for
     42   /// sections that contain fixed-sized entries. If a section does not contain
     43   /// fixed-sized entries 'EntrySize' will be 0.
     44   unsigned EntrySize;
     45 
     46   const MCSymbolELF *Group;
     47 
     48   /// sh_info for SHF_LINK_ORDER (can be null).
     49   const MCSymbol *AssociatedSymbol;
     50 
     51 private:
     52   friend class MCContext;
     53 
     54   MCSectionELF(StringRef Section, unsigned type, unsigned flags, SectionKind K,
     55                unsigned entrySize, const MCSymbolELF *group, unsigned UniqueID,
     56                MCSymbol *Begin, const MCSymbolELF *AssociatedSymbol)
     57       : MCSection(SV_ELF, K, Begin), SectionName(Section), Type(type),
     58         Flags(flags), UniqueID(UniqueID), EntrySize(entrySize), Group(group),
     59         AssociatedSymbol(AssociatedSymbol) {
     60     if (Group)
     61       Group->setIsSignature();
     62   }
     63 
     64   void setSectionName(StringRef Name) { SectionName = Name; }
     65 
     66 public:
     67   ~MCSectionELF();
     68 
     69   /// Decides whether a '.section' directive should be printed before the
     70   /// section name
     71   bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
     72 
     73   StringRef getSectionName() const { return SectionName; }
     74   unsigned getType() const { return Type; }
     75   unsigned getFlags() const { return Flags; }
     76   unsigned getEntrySize() const { return EntrySize; }
     77   void setFlags(unsigned F) { Flags = F; }
     78   const MCSymbolELF *getGroup() const { return Group; }
     79 
     80   void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
     81                             raw_ostream &OS,
     82                             const MCExpr *Subsection) const override;
     83   bool UseCodeAlign() const override;
     84   bool isVirtualSection() const override;
     85 
     86   bool isUnique() const { return UniqueID != ~0U; }
     87   unsigned getUniqueID() const { return UniqueID; }
     88 
     89   const MCSection *getAssociatedSection() const { return &AssociatedSymbol->getSection(); }
     90   const MCSymbol *getAssociatedSymbol() const { return AssociatedSymbol; }
     91 
     92   static bool classof(const MCSection *S) {
     93     return S->getVariant() == SV_ELF;
     94   }
     95 };
     96 
     97 } // end namespace llvm
     98 
     99 #endif // LLVM_MC_MCSECTIONELF_H
    100