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//===- MCAsmLayout.h - Assembly Layout Object -------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#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 MCSectionData;
class MCSymbol;
class MCSymbolData;
/// 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 {
public:
typedef llvm::SmallVectorImpl<MCSectionData*>::const_iterator const_iterator;
typedef llvm::SmallVectorImpl<MCSectionData*>::iterator iterator;
private:
MCAssembler &Assembler;
/// List of sections in layout order.
llvm::SmallVector<MCSectionData*, 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 MCSectionData*, MCFragment*> LastValidFragment;
/// \brief Make sure that the layout for the given fragment is valid, lazily
/// computing it if necessary.
void ensureValid(const MCFragment *F) const;
/// \brief Is the layout for this fragment valid?
bool isFragmentValid(const MCFragment *F) const;
/// \brief Compute the amount of padding required before this fragment to
/// obey bundling restrictions.
uint64_t computeBundlePadding(const MCFragment *F,
uint64_t FOffset, uint64_t FSize);
public:
MCAsmLayout(MCAssembler &_Assembler);
/// Get the assembler object this is a layout for.
MCAssembler &getAssembler() const { return Assembler; }
/// \brief 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);
/// \brief 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<MCSectionData*> &getSectionOrder() {
return SectionOrder;
}
const llvm::SmallVectorImpl<MCSectionData*> &getSectionOrder() const {
return SectionOrder;
}
/// @}
/// @name Fragment Layout Data
/// @{
/// \brief Get the offset of the given fragment inside its containing section.
uint64_t getFragmentOffset(const MCFragment *F) const;
/// @}
/// @name Utility Functions
/// @{
/// \brief Get the address space size of the given section, as it effects
/// layout. This may differ from the size reported by \see getSectionSize() by
/// not including section tail padding.
uint64_t getSectionAddressSize(const MCSectionData *SD) const;
/// \brief 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 MCSectionData *SD) const;
/// \brief Get the offset of the given symbol, as computed in the current
/// layout.
/// \result True on success.
bool getSymbolOffset(const MCSymbolData *SD, uint64_t &Val) const;
/// \brief Variant that reports a fatal error if the offset is not computable.
uint64_t getSymbolOffset(const MCSymbolData *SD) const;
/// \brief If this symbol is equivalent to A + Constant, return A.
const MCSymbol *getBaseSymbol(const MCSymbol &Symbol) const;
/// @}
};
} // end namespace llvm
#endif
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