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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/ADT/ilist.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 MCContext;
class MCExpr;
class MCSymbol;
class raw_ostream;
class Triple;
template <> struct ilist_alloc_traits<MCFragment> {
static void deleteNode(MCFragment *V);
};
/// 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:
enum SectionVariant { SV_COFF = 0, SV_ELF, SV_MachO, SV_Wasm, SV_XCOFF };
/// Express the state of bundle locked groups while emitting code.
enum BundleLockStateType {
NotBundleLocked,
BundleLocked,
BundleLockedAlignToEnd
};
using FragmentListType = iplist<MCFragment>;
using const_iterator = FragmentListType::const_iterator;
using iterator = FragmentListType::iterator;
using const_reverse_iterator = FragmentListType::const_reverse_iterator;
using reverse_iterator = FragmentListType::reverse_iterator;
private:
MCSymbol *Begin;
MCSymbol *End = nullptr;
/// The alignment requirement of this section.
Align Alignment;
/// The section index in the assemblers section list.
unsigned Ordinal = 0;
/// The index of this section in the layout order.
unsigned LayoutOrder;
/// 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 IsRegistered : 1;
MCDummyFragment DummyFragment;
FragmentListType Fragments;
/// Mapping from subsection number to insertion point for subsection numbers
/// below that number.
SmallVector<std::pair<unsigned, MCFragment *>, 1> SubsectionFragmentMap;
/// State for tracking labels that don't yet have Fragments
struct PendingLabel {
MCSymbol* Sym;
unsigned Subsection;
PendingLabel(MCSymbol* Sym, unsigned Subsection = 0)
: Sym(Sym), Subsection(Subsection) {}
};
SmallVector<PendingLabel, 2> PendingLabels;
protected:
SectionVariant Variant;
SectionKind Kind;
MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin);
~MCSection();
public:
MCSection(const MCSection &) = delete;
MCSection &operator=(const MCSection &) = delete;
SectionKind getKind() const { return Kind; }
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;
unsigned getAlignment() const { return Alignment.value(); }
void setAlignment(Align Value) { Alignment = Value; }
unsigned getOrdinal() const { return Ordinal; }
void setOrdinal(unsigned Value) { Ordinal = Value; }
unsigned getLayoutOrder() const { return LayoutOrder; }
void setLayoutOrder(unsigned Value) { LayoutOrder = 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 isRegistered() const { return IsRegistered; }
void setIsRegistered(bool Value) { IsRegistered = Value; }
MCSection::FragmentListType &getFragmentList() { return Fragments; }
const MCSection::FragmentListType &getFragmentList() const {
return const_cast<MCSection *>(this)->getFragmentList();
}
/// Support for MCFragment::getNextNode().
static FragmentListType MCSection::*getSublistAccess(MCFragment *) {
return &MCSection::Fragments;
}
const MCDummyFragment &getDummyFragment() const { return DummyFragment; }
MCDummyFragment &getDummyFragment() { return DummyFragment; }
iterator begin() { return Fragments.begin(); }
const_iterator begin() const { return Fragments.begin(); }
iterator end() { return Fragments.end(); }
const_iterator end() const { return Fragments.end(); }
MCSection::iterator getSubsectionInsertionPoint(unsigned Subsection);
void dump() const;
virtual void PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
raw_ostream &OS,
const MCExpr *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.
virtual bool isVirtualSection() const = 0;
/// Add a pending label for the requested subsection. This label will be
/// associated with a fragment in flushPendingLabels()
void addPendingLabel(MCSymbol* label, unsigned Subsection = 0);
/// Associate all pending labels in a subsection with a fragment.
void flushPendingLabels(MCFragment *F, uint64_t FOffset = 0,
unsigned Subsection = 0);
/// Associate all pending labels with empty data fragments. One fragment
/// will be created for each subsection as necessary.
void flushPendingLabels();
};
} // end namespace llvm
#endif // LLVM_MC_MCSECTION_H
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