LLVM 19.0.0git
MCSectionCOFF.h
Go to the documentation of this file.
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"
18#include "llvm/MC/MCSection.h"
19#include "llvm/MC/SectionKind.h"
20#include <cassert>
21
22namespace llvm {
23
24class MCSymbol;
25
26/// This represents a section on Windows
27class MCSectionCOFF final : public MCSection {
28 // FIXME: The following fields should not be mutable, but are for now so the
29 // asm parser can honor the .linkonce directive.
30
31 /// This is the Characteristics field of a section, drawn from the enums
32 /// below.
33 mutable unsigned Characteristics;
34
35 /// The unique IDs used with the .pdata and .xdata sections created internally
36 /// by the assembler. This ID is used to ensure that for every .text section,
37 /// there is exactly one .pdata and one .xdata section, which is required by
38 /// the Microsoft incremental linker. This data is mutable because this ID is
39 /// not notionally part of the section.
40 mutable unsigned WinCFISectionID = ~0U;
41
42 /// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
43 /// Two COMDAT sections are merged if they have the same COMDAT symbol.
44 MCSymbol *COMDATSymbol;
45
46 /// This is the Selection field for the section symbol, if it is a COMDAT
47 /// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
48 mutable int Selection;
49
50private:
51 friend class MCContext;
52 // The storage of Name is owned by MCContext's COFFUniquingMap.
54 MCSymbol *COMDATSymbol, int Selection, MCSymbol *Begin)
55 : MCSection(SV_COFF, Name, Characteristics & COFF::IMAGE_SCN_CNT_CODE,
56 Begin),
57 Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
59 assert((Characteristics & 0x00F00000) == 0 &&
60 "alignment must not be set upon section creation");
61 }
62
63public:
64 /// Decides whether a '.section' directive should be printed before the
65 /// section name
66 bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
67
68 unsigned getCharacteristics() const { return Characteristics; }
69 MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
70 int getSelection() const { return Selection; }
71
72 void setSelection(int Selection) const;
73
74 void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
76 uint32_t Subsection) const override;
77 bool useCodeAlign() const override;
78 bool isVirtualSection() const override;
79 StringRef getVirtualSectionKind() const override;
80
81 unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
82 if (WinCFISectionID == ~0U)
83 WinCFISectionID = (*NextID)++;
84 return WinCFISectionID;
85 }
86
88 return Name.starts_with(".debug");
89 }
90
91 static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
92};
93
94} // end namespace llvm
95
96#endif // LLVM_MC_MCSECTIONCOFF_H
amdgpu AMDGPU DAG DAG Pattern Instruction Selection
COFFYAML::WeakExternalCharacteristics Characteristics
Definition: COFFYAML.cpp:331
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
raw_pwrite_stream & OS
This class is intended to be used as a base class for asm properties and features specific to the tar...
Definition: MCAsmInfo.h:56
Context object for machine code objects.
Definition: MCContext.h:83
This represents a section on Windows.
Definition: MCSectionCOFF.h:27
static bool isImplicitlyDiscardable(StringRef Name)
Definition: MCSectionCOFF.h:87
bool shouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const
Decides whether a '.section' directive should be printed before the section name.
void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T, raw_ostream &OS, uint32_t Subsection) const override
MCSymbol * getCOMDATSymbol() const
Definition: MCSectionCOFF.h:69
unsigned getCharacteristics() const
Definition: MCSectionCOFF.h:68
StringRef getVirtualSectionKind() const override
bool isVirtualSection() const override
Check whether this section is "virtual", that is has no actual object file contents.
bool useCodeAlign() const override
Return true if a .align directive should use "optimized nops" to fill instead of 0s.
unsigned getOrAssignWinCFISectionID(unsigned *NextID) const
Definition: MCSectionCOFF.h:81
int getSelection() const
Definition: MCSectionCOFF.h:70
void setSelection(int Selection) const
static bool classof(const MCSection *S)
Definition: MCSectionCOFF.h:91
Instances of this class represent a uniqued identifier for a section in the current translation unit.
Definition: MCSection.h:35
SectionVariant getVariant() const
Definition: MCSection.h:140
StringRef Name
Definition: MCSection.h:127
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:50
bool starts_with(StringRef Prefix) const
Check if this string starts with the given Prefix.
Definition: StringRef.h:258
Triple - Helper class for working with autoconf configuration names.
Definition: Triple.h:44
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18