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//===- MCSectionCOFF.h - COFF Machine Code Sections -------------*- C++ -*-===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This file declares the MCSectionCOFF class.
#include "llvm/ADT/StringRef.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/SectionKind.h"
#include <cassert>
namespace llvm {
class MCSymbol;
/// This represents a section on Windows
class MCSectionCOFF final : public MCSection {
// The memory for this string is stored in the same MCContext as *this.
StringRef SectionName;
// FIXME: The following fields should not be mutable, but are for now so the
// asm parser can honor the .linkonce directive.
/// This is the Characteristics field of a section, drawn from the enums
/// below.
mutable unsigned Characteristics;
/// The unique IDs used with the .pdata and .xdata sections created internally
/// by the assembler. This ID is used to ensure that for every .text section,
/// there is exactly one .pdata and one .xdata section, which is required by
/// the Microsoft incremental linker. This data is mutable because this ID is
/// not notionally part of the section.
mutable unsigned WinCFISectionID = ~0U;
/// The COMDAT symbol of this section. Only valid if this is a COMDAT section.
/// Two COMDAT sections are merged if they have the same COMDAT symbol.
MCSymbol *COMDATSymbol;
/// This is the Selection field for the section symbol, if it is a COMDAT
/// section (Characteristics & IMAGE_SCN_LNK_COMDAT) != 0
mutable int Selection;
friend class MCContext;
MCSectionCOFF(StringRef Section, unsigned Characteristics,
MCSymbol *COMDATSymbol, int Selection, SectionKind K,
MCSymbol *Begin)
: MCSection(SV_COFF, K, Begin), SectionName(Section),
Characteristics(Characteristics), COMDATSymbol(COMDATSymbol),
Selection(Selection) {
assert((Characteristics & 0x00F00000) == 0 &&
"alignment must not be set upon section creation");
/// Decides whether a '.section' directive should be printed before the
/// section name
bool ShouldOmitSectionDirective(StringRef Name, const MCAsmInfo &MAI) const;
StringRef getSectionName() const { return SectionName; }
unsigned getCharacteristics() const { return Characteristics; }
MCSymbol *getCOMDATSymbol() const { return COMDATSymbol; }
int getSelection() const { return Selection; }
void setSelection(int Selection) const;
void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
const MCExpr *Subsection) const override;
bool UseCodeAlign() const override;
bool isVirtualSection() const override;
unsigned getOrAssignWinCFISectionID(unsigned *NextID) const {
if (WinCFISectionID == ~0U)
WinCFISectionID = (*NextID)++;
return WinCFISectionID;
static bool isImplicitlyDiscardable(StringRef Name) {
return Name.startswith(".debug");
static bool classof(const MCSection *S) { return S->getVariant() == SV_COFF; }
} // end namespace llvm