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/Twine.h"
18#include "llvm/MC/MCSection.h"
19#include "llvm/MC/MCSymbol.h"
20#include "llvm/Support/Debug.h"
21#include "llvm/Support/ELF.h"
22#include "llvm/Support/raw_ostream.h"
23
24namespace llvm {
25
26class MCSymbol;
27
28/// MCSectionELF - This represents a section on linux, lots of unix variants
29/// and some bare metal systems.
30class MCSectionELF : public MCSection {
31  /// SectionName - This is the name of the section.  The referenced memory is
32  /// owned by TargetLoweringObjectFileELF's ELFUniqueMap.
33  StringRef SectionName;
34
35  /// Type - This is the sh_type field of a section, drawn from the enums below.
36  unsigned Type;
37
38  /// Flags - This is the sh_flags field of a section, drawn from the enums.
39  /// below.
40  unsigned Flags;
41
42  /// EntrySize - The size of each entry in this section. This size only
43  /// makes sense for sections that contain fixed-sized entries. If a
44  /// section does not contain fixed-sized entries 'EntrySize' will be 0.
45  unsigned EntrySize;
46
47  const MCSymbol *Group;
48
49private:
50  friend class MCContext;
51  MCSectionELF(StringRef Section, unsigned type, unsigned flags,
52               SectionKind K, unsigned entrySize, const MCSymbol *group)
53    : MCSection(SV_ELF, K), SectionName(Section), Type(type), Flags(flags),
54      EntrySize(entrySize), Group(group) {}
55  ~MCSectionELF();
56
57  void setSectionName(StringRef Name) { SectionName = Name; }
58
59public:
60
61  /// ShouldOmitSectionDirective - Decides whether a '.section' directive
62  /// should be printed before the section name
63  bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
64
65  StringRef getSectionName() const { return SectionName; }
66  std::string getLabelBeginName() const override {
67    if (Group)
68      return (SectionName.str() + '_' + Group->getName() + "_begin").str();
69    return SectionName.str() + "_begin";
70  }
71  std::string getLabelEndName() const override {
72    if (Group)
73      return (SectionName.str() + '_' + Group->getName() + "_end").str();
74    return SectionName.str() + "_end";
75  }
76  unsigned getType() const { return Type; }
77  unsigned getFlags() const { return Flags; }
78  unsigned getEntrySize() const { return EntrySize; }
79  const MCSymbol *getGroup() const { return Group; }
80
81  void PrintSwitchToSection(const MCAsmInfo &MAI, raw_ostream &OS,
82                            const MCExpr *Subsection) const override;
83  bool UseCodeAlign() const override;
84  bool isVirtualSection() const override;
85
86  /// isBaseAddressKnownZero - We know that non-allocatable sections (like
87  /// debug info) have a base of zero.
88  bool isBaseAddressKnownZero() const override {
89    return (getFlags() & ELF::SHF_ALLOC) == 0;
90  }
91
92  static bool classof(const MCSection *S) {
93    return S->getVariant() == SV_ELF;
94  }
95
96  // Return the entry size for sections with fixed-width data.
97  static unsigned DetermineEntrySize(SectionKind Kind);
98
99};
100
101} // end namespace llvm
102
103#endif
104