MCSectionCOFF.h revision 263508 
1//===- MCSectionCOFF.h - COFF 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 MCSectionCOFF class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_MC_MCSECTIONCOFF_H
15#define LLVM_MC_MCSECTIONCOFF_H
16
17#include "llvm/ADT/StringRef.h"
18#include "llvm/MC/MCSection.h"
19#include "llvm/Support/COFF.h"
20
21namespace llvm {
22class MCSymbol;
23
24/// MCSectionCOFF - This represents a section on Windows
25  class MCSectionCOFF : public MCSection {
26    // The memory for this string is stored in the same MCContext as *this.
27    StringRef SectionName;
28
29    // FIXME: The following fields should not be mutable, but are for now so
30    // the asm parser can honor the .linkonce directive.
31
32    /// Characteristics - This is the Characteristics field of a section,
33    /// drawn from the enums below.
34    mutable unsigned Characteristics;
35
36    /// The COMDAT symbol of this section. Only valid if this is a COMDAT
37    /// section. Two COMDAT sections are merged if they have the same
38    /// COMDAT symbol.
39    const MCSymbol *COMDATSymbol;
40
41    /// Selection - This is the Selection field for the section symbol, if
42    /// it is a COMDAT section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
43    mutable int Selection;
44
45    /// Assoc - This is name of the associated section, if it is a COMDAT
46    /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0 with an
47    /// associative Selection (IMAGE_COMDAT_SELECT_ASSOCIATIVE).
48    mutable const MCSectionCOFF *Assoc;
49
50  private:
51    friend class MCContext;
52    MCSectionCOFF(StringRef Section, unsigned Characteristics,
53                  const MCSymbol *COMDATSymbol, int Selection,
54                  const MCSectionCOFF *Assoc, SectionKind K)
55        : MCSection(SV_COFF, K), SectionName(Section),
56          Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
57          Selection(Selection), Assoc(Assoc) {
58      assert ((Characteristics & 0x00F00000) == 0 &&
59        "alignment must not be set upon section creation");
60      assert ((Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) ==
61              (Assoc != 0) &&
62        "associative COMDAT section must have an associated section");
63    }
64    ~MCSectionCOFF();
65
66  public:
67    /// ShouldOmitSectionDirective - Decides whether a '.section' directive
68    /// should be printed before the section name
69    bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
70
71    StringRef getSectionName() const { return SectionName; }
72    virtual std::string getLabelBeginName() const {
73      return SectionName.str() + "_begin";
74    }
75    virtual std::string getLabelEndName() const {
76      return SectionName.str() + "_end";
77    }
78    unsigned getCharacteristics() const { return Characteristics; }
79    int getSelection() const { return Selection; }
80    const MCSectionCOFF *getAssocSection() const { return Assoc; }
81
82    void setSelection(int Selection, const MCSectionCOFF *Assoc = 0) const;
83
84    virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
85                                      raw_ostream &OS,
86                                      const MCExpr *Subsection) const;
87    virtual bool UseCodeAlign() const;
88    virtual bool isVirtualSection() const;
89
90    static bool classof(const MCSection *S) {
91      return S->getVariant() == SV_COFF;
92    }
93  };
94
95} // end namespace llvm
96
97#endif
98