//===- MCAsmLayout.h - Assembly Layout Object -------------------*- 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_MCASMLAYOUT_H
#define LLVM_MC_MCASMLAYOUT_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
namespace llvm {
class MCAssembler;
class MCFragment;
class MCSection;
class MCSymbol;
/// Encapsulates the layout of an assembly file at a particular point in time.
///
/// Assembly may require computing multiple layouts for a particular assembly
/// file as part of the relaxation process. This class encapsulates the layout
/// at a single point in time in such a way that it is always possible to
/// efficiently compute the exact address of any symbol in the assembly file,
/// even during the relaxation process.
class MCAsmLayout {
MCAssembler &Assembler;
/// List of sections in layout order.
llvm::SmallVector<MCSection *, 16> SectionOrder;
/// The last fragment which was laid out, or 0 if nothing has been laid
/// out. Fragments are always laid out in order, so all fragments with a
/// lower ordinal will be valid.
mutable DenseMap<const MCSection *, MCFragment *> LastValidFragment;
/// Make sure that the layout for the given fragment is valid, lazily
/// computing it if necessary.
void ensureValid(const MCFragment *F) const;
/// Is the layout for this fragment valid?
bool isFragmentValid(const MCFragment *F) const;
public:
MCAsmLayout(MCAssembler &Assembler);
/// Get the assembler object this is a layout for.
MCAssembler &getAssembler() const { return Assembler; }
/// \returns whether the offset of fragment \p F can be obtained via
/// getFragmentOffset.
bool canGetFragmentOffset(const MCFragment *F) const;
/// Invalidate the fragments starting with F because it has been
/// resized. The fragment's size should have already been updated, but
/// its bundle padding will be recomputed.
void invalidateFragmentsFrom(MCFragment *F);
/// Perform layout for a single fragment, assuming that the previous
/// fragment has already been laid out correctly, and the parent section has
/// been initialized.
void layoutFragment(MCFragment *Fragment);
/// \name Section Access (in layout order)
/// @{
llvm::SmallVectorImpl<MCSection *> &getSectionOrder() { return SectionOrder; }
const llvm::SmallVectorImpl<MCSection *> &getSectionOrder() const {
return SectionOrder;
}
/// @}
/// \name Fragment Layout Data
/// @{
/// Get the offset of the given fragment inside its containing section.
uint64_t getFragmentOffset(const MCFragment *F) const;
/// @}
/// \name Utility Functions
/// @{
/// Get the address space size of the given section, as it effects
/// layout. This may differ from the size reported by \see
/// getSectionFileSize() by not including section tail padding.
uint64_t getSectionAddressSize(const MCSection *Sec) const;
/// Get the data size of the given section, as emitted to the object
/// file. This may include additional padding, or be 0 for virtual sections.
uint64_t getSectionFileSize(const MCSection *Sec) const;
/// Get the offset of the given symbol, as computed in the current
/// layout.
/// \return True on success.
bool getSymbolOffset(const MCSymbol &S, uint64_t &Val) const;
/// Variant that reports a fatal error if the offset is not computable.
uint64_t getSymbolOffset(const MCSymbol &S) const;
/// If this symbol is equivalent to A + Constant, return A.
const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
/// @}
};
} // end namespace llvm
#endif