//===- llvm/MC/MCObjectWriter.h - Object File Writer Interface --*- 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
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_MC_MCOBJECTWRITER_H
#define LLVM_MC_MCOBJECTWRITER_H
#include "llvm/ADT/Triple.h"
#include "llvm/MC/MCSymbol.h"
#include <cstdint>
namespace llvm {
class MCAsmLayout;
class MCAssembler;
class MCFixup;
class MCFragment;
class MCSymbol;
class MCSymbolRefExpr;
class MCValue;
/// Defines the object file and target independent interfaces used by the
/// assembler backend to write native file format object files.
///
/// The object writer contains a few callbacks used by the assembler to allow
/// the object writer to modify the assembler data structures at appropriate
/// points. Once assembly is complete, the object writer is given the
/// MCAssembler instance, which contains all the symbol and section data which
/// should be emitted as part of writeObject().
class MCObjectWriter {
protected:
std::vector<const MCSymbol *> AddrsigSyms;
bool EmitAddrsigSection = false;
MCObjectWriter() = default;
public:
MCObjectWriter(const MCObjectWriter &) = delete;
MCObjectWriter &operator=(const MCObjectWriter &) = delete;
virtual ~MCObjectWriter();
/// lifetime management
virtual void reset() {}
/// \name High-Level API
/// @{
/// Perform any late binding of symbols (for example, to assign symbol
/// indices for use when generating relocations).
///
/// This routine is called by the assembler after layout and relaxation is
/// complete.
virtual void executePostLayoutBinding(MCAssembler &Asm,
const MCAsmLayout &Layout) = 0;
/// Record a relocation entry.
///
/// This routine is called by the assembler after layout and relaxation, and
/// post layout binding. The implementation is responsible for storing
/// information about the relocation so that it can be emitted during
/// writeObject().
virtual void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
const MCFragment *Fragment,
const MCFixup &Fixup, MCValue Target,
uint64_t &FixedValue) = 0;
/// Check whether the difference (A - B) between two symbol references is
/// fully resolved.
///
/// Clients are not required to answer precisely and may conservatively return
/// false, even when a difference is fully resolved.
bool isSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
const MCSymbolRefExpr *A,
const MCSymbolRefExpr *B,
bool InSet) const;
virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
const MCSymbol &A,
const MCSymbol &B,
bool InSet) const;
virtual bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
const MCSymbol &SymA,
const MCFragment &FB,
bool InSet,
bool IsPCRel) const;
/// ELF only. Mark that we have seen GNU ABI usage (e.g. SHF_GNU_RETAIN).
virtual void markGnuAbi() {}
/// Tell the object writer to emit an address-significance table during
/// writeObject(). If this function is not called, all symbols are treated as
/// address-significant.
void emitAddrsigSection() { EmitAddrsigSection = true; }
bool getEmitAddrsigSection() { return EmitAddrsigSection; }
/// Record the given symbol in the address-significance table to be written
/// diring writeObject().
void addAddrsigSymbol(const MCSymbol *Sym) { AddrsigSyms.push_back(Sym); }
std::vector<const MCSymbol *> &getAddrsigSyms() { return AddrsigSyms; }
virtual void addExceptionEntry(const MCSymbol *Symbol, const MCSymbol *Trap,
unsigned LanguageCode, unsigned ReasonCode,
unsigned FunctionSize, bool hasDebug) {
report_fatal_error("addExceptionEntry is only supported on XCOFF targets");
}
/// Write the object file and returns the number of bytes written.
///
/// This routine is called by the assembler after layout and relaxation is
/// complete, fixups have been evaluated and applied, and relocations
/// generated.
virtual uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) = 0;
/// @}
};
/// Base class for classes that define behaviour that is specific to both the
/// target and the object format.
class MCObjectTargetWriter {
public:
virtual ~MCObjectTargetWriter() = default;
virtual Triple::ObjectFormatType getFormat() const = 0;
};
} // end namespace llvm
#endif // LLVM_MC_MCOBJECTWRITER_H