1 //===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file declares the MCSectionCOFF class.
12 //===----------------------------------------------------------------------===//
14 #ifndef LLVM_MC_MCSECTIONCOFF_H
15 #define LLVM_MC_MCSECTIONCOFF_H
17 #include "llvm/ADT/StringRef.h"
18 #include "llvm/MC/MCSection.h"
19 #include "llvm/MC/SectionKind.h"
26 /// This represents a section on Windows
27 class MCSectionCOFF final : public MCSection {
28 // The memory for this string is stored in the same MCContext as *this.
29 StringRef SectionName;
31 // FIXME: The following fields should not be mutable, but are for now so the
32 // asm parser can honor the .linkonce directive.
34 /// This is the Characteristics field of a section, drawn from the enums
36 mutable unsigned Characteristics;
38 /// The unique IDs used with the .pdata and .xdata sections created internally
39 /// by the assembler. This ID is used to ensure that for every .text section,
40 /// there is exactly one .pdata and one .xdata section, which is required by
41 /// the Microsoft incremental linker. This data is mutable because this ID is
42 /// not notionally part of the section.
43 mutable unsigned WinCFISectionID = ~0U;
45 /// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
46 /// Two COMDAT sections are merged if they have the same COMDAT symbol.
47 MCSymbol *COMDATSymbol;
49 /// This is the Selection field for the section symbol, if it is a COMDAT
50 /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
51 mutable int Selection;
54 friend class MCContext;
55 MCSectionCOFF(StringRef Section, unsigned Characteristics,
56 MCSymbol *COMDATSymbol, int Selection, SectionKind K,
58 : MCSection(SV_COFF, K, Begin), SectionName(Section),
59 Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
60 Selection(Selection) {
61 assert((Characteristics & 0x00F00000) == 0 &&
62 "alignment must not be set upon section creation");
68 /// Decides whether a '.section' directive should be printed before the
70 bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
72 StringRef getSectionName() const { return SectionName; }
73 unsigned getCharacteristics() const { return Characteristics; }
74 MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
75 int getSelection() const { return Selection; }
77 void setSelection(int Selection) const;
79 void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
81 const MCExpr *Subsection) const override;
82 bool UseCodeAlign() const override;
83 bool isVirtualSection() const override;
85 unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
86 if (WinCFISectionID == ~0U)
87 WinCFISectionID = (*NextID)++;
88 return WinCFISectionID;
91 static bool isImplicitlyDiscardable(StringRef Name) {
92 return Name.startswith(".debug");
95 static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
98 } // end namespace llvm
100 #endif // LLVM_MC_MCSECTIONCOFF_H