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//===- MCSection.h - Machine Code Sections ----------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file declares the MCSection class.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCSECTION_H
#define LLVM_MC_MCSECTION_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/MC/MCFragment.h"
#include "llvm/MC/SectionKind.h"
#include "llvm/Support/Alignment.h"
#include <cassert>
#include <utility>
namespace llvm {
class MCAsmInfo;
class MCAssembler;
class MCContext;
class MCExpr;
class MCObjectStreamer;
class MCSymbol;
class raw_ostream;
class Triple;
/// Instances of this class represent a uniqued identifier for a section in the
/// current translation unit. The MCContext class uniques and creates these.
class MCSection {
public:
friend MCAssembler;
friend MCObjectStreamer;
static constexpr unsigned NonUniqueID = ~0U;
enum SectionVariant {
SV_COFF = 0,
SV_ELF,
SV_GOFF,
SV_MachO,
SV_Wasm,
SV_XCOFF,
SV_SPIRV,
SV_DXContainer,
};
/// Express the state of bundle locked groups while emitting code.
enum BundleLockStateType {
NotBundleLocked,
BundleLocked,
BundleLockedAlignToEnd
};
struct iterator {
MCFragment *F = nullptr;
iterator() = default;
explicit iterator(MCFragment *F) : F(F) {}
MCFragment &operator*() const { return *F; }
bool operator==(const iterator &O) const { return F == O.F; }
bool operator!=(const iterator &O) const { return F != O.F; }
iterator &operator++() {
F = F->Next;
return *this;
}
};
struct FragList {
MCFragment *Head = nullptr;
MCFragment *Tail = nullptr;
};
private:
// At parse time, this holds the fragment list of the current subsection. At
// layout time, this holds the concatenated fragment lists of all subsections.
FragList *CurFragList;
MCSymbol *Begin;
MCSymbol *End = nullptr;
/// The alignment requirement of this section.
Align Alignment;
/// The section index in the assemblers section list.
unsigned Ordinal = 0;
/// Keeping track of bundle-locked state.
BundleLockStateType BundleLockState = NotBundleLocked;
/// Current nesting depth of bundle_lock directives.
unsigned BundleLockNestingDepth = 0;
/// We've seen a bundle_lock directive but not its first instruction
/// yet.
bool BundleGroupBeforeFirstInst : 1;
/// Whether this section has had instructions emitted into it.
bool HasInstructions : 1;
bool HasLayout : 1;
bool IsRegistered : 1;
bool IsText : 1;
bool IsVirtual : 1;
MCDummyFragment DummyFragment;
// Mapping from subsection number to fragment list. At layout time, the
// subsection 0 list is replaced with concatenated fragments from all
// subsections.
SmallVector<std::pair<unsigned, FragList>, 1> Subsections;
protected:
// TODO Make Name private when possible.
StringRef Name;
SectionVariant Variant;
MCSection(SectionVariant V, StringRef Name, bool IsText, bool IsVirtual,
MCSymbol *Begin);
~MCSection();
public:
MCSection(const MCSection &) = delete;
MCSection &operator=(const MCSection &) = delete;
StringRef getName() const { return Name; }
bool isText() const { return IsText; }
SectionVariant getVariant() const { return Variant; }
MCSymbol *getBeginSymbol() { return Begin; }
const MCSymbol *getBeginSymbol() const {
return const_cast<MCSection *>(this)->getBeginSymbol();
}
void setBeginSymbol(MCSymbol *Sym) {
assert(!Begin);
Begin = Sym;
}
MCSymbol *getEndSymbol(MCContext &Ctx);
bool hasEnded() const;
Align getAlign() const { return Alignment; }
void setAlignment(Align Value) { Alignment = Value; }
/// Makes sure that Alignment is at least MinAlignment.
void ensureMinAlignment(Align MinAlignment) {
if (Alignment < MinAlignment)
Alignment = MinAlignment;
}
unsigned getOrdinal() const { return Ordinal; }
void setOrdinal(unsigned Value) { Ordinal = Value; }
BundleLockStateType getBundleLockState() const { return BundleLockState; }
void setBundleLockState(BundleLockStateType NewState);
bool isBundleLocked() const { return BundleLockState != NotBundleLocked; }
bool isBundleGroupBeforeFirstInst() const {
return BundleGroupBeforeFirstInst;
}
void setBundleGroupBeforeFirstInst(bool IsFirst) {
BundleGroupBeforeFirstInst = IsFirst;
}
bool hasInstructions() const { return HasInstructions; }
void setHasInstructions(bool Value) { HasInstructions = Value; }
bool hasLayout() const { return HasLayout; }
void setHasLayout(bool Value) { HasLayout = Value; }
bool isRegistered() const { return IsRegistered; }
void setIsRegistered(bool Value) { IsRegistered = Value; }
const MCDummyFragment &getDummyFragment() const { return DummyFragment; }
MCDummyFragment &getDummyFragment() { return DummyFragment; }
FragList *curFragList() const { return CurFragList; }
iterator begin() const { return iterator(CurFragList->Head); }
iterator end() const { return {}; }
bool empty() const { return !CurFragList->Head; }
void dump() const;
virtual void printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
uint32_t Subsection) const = 0;
/// Return true if a .align directive should use "optimized nops" to fill
/// instead of 0s.
virtual bool useCodeAlign() const = 0;
/// Check whether this section is "virtual", that is has no actual object
/// file contents.
bool isVirtualSection() const { return IsVirtual; }
virtual StringRef getVirtualSectionKind() const;
};
} // end namespace llvm
#endif // LLVM_MC_MCSECTION_H
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