1//===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file declares the MCSectionCOFF class.
10//
11//===----------------------------------------------------------------------===//
12
13#ifndef LLVM_MC_MCSECTIONCOFF_H
14#define LLVM_MC_MCSECTIONCOFF_H
15
16#include "llvm/ADT/StringRef.h"
17#include "llvm/MC/MCSection.h"
18#include "llvm/MC/SectionKind.h"
19#include <cassert>
20
21namespace llvm {
22
23class MCSymbol;
24
25/// This represents a section on Windows
26class MCSectionCOFF final : public MCSection {
27 // FIXME: The following fields should not be mutable, but are for now so the
28 // asm parser can honor the .linkonce directive.
29
30 /// This is the Characteristics field of a section, drawn from the enums
31 /// below.
32 mutable unsigned Characteristics;
33
34 /// The unique IDs used with the .pdata and .xdata sections created internally
35 /// by the assembler. This ID is used to ensure that for every .text section,
36 /// there is exactly one .pdata and one .xdata section, which is required by
37 /// the Microsoft incremental linker. This data is mutable because this ID is
38 /// not notionally part of the section.
39 mutable unsigned WinCFISectionID = ~0U;
40
41 /// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
42 /// Two COMDAT sections are merged if they have the same COMDAT symbol.
43 MCSymbol *COMDATSymbol;
44
45 /// This is the Selection field for the section symbol, if it is a COMDAT
46 /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
47 mutable int Selection;
48
49private:
50 friend class MCContext;
51 // The storage of Name is owned by MCContext's COFFUniquingMap.
52 MCSectionCOFF(StringRef Name, unsigned Characteristics,
53 MCSymbol *COMDATSymbol, int Selection, SectionKind K,
54 MCSymbol *Begin)
55 : MCSection(SV_COFF, Name, K, Begin), Characteristics(Characteristics),
56 COMDATSymbol(COMDATSymbol), Selection(Selection) {
57 assert((Characteristics & 0x00F00000) == 0 &&
58 "alignment must not be set upon section creation");
59 }
60
61public:
62 /// Decides whether a '.section' directive should be printed before the
63 /// section name
64 bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
65
66 unsigned getCharacteristics() const { return Characteristics; }
67 MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
68 int getSelection() const { return Selection; }
69
70 void setSelection(int Selection) const;
71
72 void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
73 raw_ostream &OS,
74 const MCExpr *Subsection) const override;
75 bool useCodeAlign() const override;
76 bool isVirtualSection() const override;
77 StringRef getVirtualSectionKind() const override;
78
79 unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
80 if (WinCFISectionID == ~0U)
81 WinCFISectionID = (*NextID)++;
82 return WinCFISectionID;
83 }
84
85 static bool isImplicitlyDiscardable(StringRef Name) {
86 return Name.starts_with(Prefix: ".debug");
87 }
88
89 static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
90};
91
92} // end namespace llvm
93
94#endif // LLVM_MC_MCSECTIONCOFF_H
95

source code of llvm/include/llvm/MC/MCSectionCOFF.h