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//===- MCSectionXCOFF.h - XCOFF 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 MCSectionXCOFF class.
#include "llvm/BinaryFormat/XCOFF.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSymbolXCOFF.h"
namespace llvm {
// This class represents an XCOFF `Control Section`, more commonly referred to
// as a csect. A csect represents the smallest possible unit of data/code which
// will be relocated as a single block. A csect can either be:
// 1) Initialized: The Type will be XTY_SD, and the symbols inside the csect
// will have a label definition representing their offset within the csect.
// 2) Uninitialized: The Type will be XTY_CM, it will contain a single symbol,
// and may not contain label definitions.
// 3) An external reference providing a symbol table entry for a symbol
// contained in another XCOFF object file. External reference csects are not
// implemented yet.
class MCSectionXCOFF final : public MCSection {
friend class MCContext;
Optional<XCOFF::CsectProperties> CsectProp;
MCSymbolXCOFF *const QualName;
StringRef SymbolTableName;
Optional<XCOFF::DwarfSectionSubtypeFlags> DwarfSubtypeFlags;
bool MultiSymbolsAllowed;
static constexpr unsigned DefaultAlignVal = 4;
MCSectionXCOFF(StringRef Name, XCOFF::StorageMappingClass SMC,
XCOFF::SymbolType ST, SectionKind K, MCSymbolXCOFF *QualName,
MCSymbol *Begin, StringRef SymbolTableName,
bool MultiSymbolsAllowed)
: MCSection(SV_XCOFF, Name, K, Begin),
CsectProp(XCOFF::CsectProperties(SMC, ST)), QualName(QualName),
SymbolTableName(SymbolTableName), DwarfSubtypeFlags(None),
MultiSymbolsAllowed(MultiSymbolsAllowed) {
"Invalid or unhandled type for csect.");
assert(QualName != nullptr && "QualName is needed.");
assert((ST == XCOFF::XTY_CM || ST == XCOFF::XTY_ER) &&
"Invalid csect type for storage mapping class XCOFF::XMC_UL");
// A csect is 4 byte aligned by default, except for undefined symbol csects.
if (ST != XCOFF::XTY_ER)
MCSectionXCOFF(StringRef Name, SectionKind K, MCSymbolXCOFF *QualName,
XCOFF::DwarfSectionSubtypeFlags DwarfSubtypeFlags,
MCSymbol *Begin, StringRef SymbolTableName,
bool MultiSymbolsAllowed)
: MCSection(SV_XCOFF, Name, K, Begin), QualName(QualName),
SymbolTableName(SymbolTableName), DwarfSubtypeFlags(DwarfSubtypeFlags),
MultiSymbolsAllowed(MultiSymbolsAllowed) {
assert(QualName != nullptr && "QualName is needed.");
// FIXME: use a more meaningful name for non csect sections.
// Set default alignment 4 for all non csect sections for now.
// FIXME: set different alignments according to section types.
void printCsectDirective(raw_ostream &OS) const;
static bool classof(const MCSection *S) {
return S->getVariant() == SV_XCOFF;
XCOFF::StorageMappingClass getMappingClass() const {
assert(isCsect() && "Only csect section has mapping class property!");
return CsectProp->MappingClass;
XCOFF::StorageClass getStorageClass() const {
return QualName->getStorageClass();
XCOFF::SymbolType getCSectType() const {
assert(isCsect() && "Only csect section has symbol type property!");
return CsectProp->Type;
MCSymbolXCOFF *getQualNameSymbol() const { return QualName; }
void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
const MCExpr *Subsection) const override;
bool UseCodeAlign() const override;
bool isVirtualSection() const override;
StringRef getSymbolTableName() const { return SymbolTableName; }
bool isMultiSymbolsAllowed() const { return MultiSymbolsAllowed; }
bool isCsect() const { return CsectProp.hasValue(); }
bool isDwarfSect() const { return DwarfSubtypeFlags.hasValue(); }
Optional<XCOFF::DwarfSectionSubtypeFlags> getDwarfSubtypeFlags() const {
return DwarfSubtypeFlags;
} // end namespace llvm