MCSectionELF.h revision df39be6cb4eb44011db3d3e86f8fe463f81ce127 
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/Support/Debug.h"
20#include "llvm/Support/ELF.h"
21#include "llvm/Support/raw_ostream.h"
22
23namespace llvm {
24
25class MCSymbol;
26
27/// MCSectionELF - This represents a section on linux, lots of unix variants
28/// and some bare metal systems.
29class MCSectionELF : public MCSection {
30  /// SectionName - This is the name of the section.  The referenced memory is
31  /// owned by TargetLoweringObjectFileELF's ELFUniqueMap.
32  StringRef SectionName;
33
34  /// Type - This is the sh_type field of a section, drawn from the enums below.
35  unsigned Type;
36
37  /// Flags - This is the sh_flags field of a section, drawn from the enums.
38  /// below.
39  unsigned Flags;
40
41  /// EntrySize - The size of each entry in this section. This size only
42  /// makes sense for sections that contain fixed-sized entries. If a
43  /// section does not contain fixed-sized entries 'EntrySize' will be 0.
44  unsigned EntrySize;
45
46  const MCSymbol *Group;
47
48private:
49  friend class MCContext;
50  MCSectionELF(StringRef Section, unsigned type, unsigned flags,
51               SectionKind K, unsigned entrySize, const MCSymbol *group)
52    : MCSection(SV_ELF, K), SectionName(Section), Type(type), Flags(flags),
53      EntrySize(entrySize), Group(group) {}
54  ~MCSectionELF();
55public:
56
57  /// ShouldOmitSectionDirective - Decides whether a '.section' directive
58  /// should be printed before the section name
59  bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
60
61  StringRef getSectionName() const { return SectionName; }
62  virtual std::string getLabelBeginName() const {
63    return SectionName.str() + "_begin"; }
64  virtual std::string getLabelEndName() const {
65    return SectionName.str() + "_end";
66  }
67  unsigned getType() const { return Type; }
68  unsigned getFlags() const { return Flags; }
69  unsigned getEntrySize() const { return EntrySize; }
70  const MCSymbol *getGroup() const { return Group; }
71
72  void PrintSwitchToSection(const MCAsmInfo &MAI,
73                            raw_ostream &OS,
74                            const MCExpr *Subsection) const;
75  virtual bool UseCodeAlign() const;
76  virtual bool isVirtualSection() const;
77
78  /// isBaseAddressKnownZero - We know that non-allocatable sections (like
79  /// debug info) have a base of zero.
80  virtual bool isBaseAddressKnownZero() const {
81    return (getFlags() & ELF::SHF_ALLOC) == 0;
82  }
83
84  static bool classof(const MCSection *S) {
85    return S->getVariant() == SV_ELF;
86  }
87
88  // Return the entry size for sections with fixed-width data.
89  static unsigned DetermineEntrySize(SectionKind Kind);
90
91};
92
93} // end namespace llvm
94
95#endif
96