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//===- Thunks.h --------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#ifndef LLD_ELF_THUNKS_H
#define LLD_ELF_THUNKS_H
#include "Relocations.h"
namespace lld {
namespace elf {
class SymbolBody;
template <class ELFT> class InputSection;
// Class to describe an instance of a Thunk.
// A Thunk is a code-sequence inserted by the linker in between a caller and
// the callee. The relocation to the callee is redirected to the Thunk, which
// after executing transfers control to the callee. Typical uses of Thunks
// include transferring control from non-pi to pi and changing state on
// targets like ARM.
//
// Thunks can be created for DefinedRegular and Shared Symbols. The Thunk
// is stored in a field of the Symbol Destination.
// Thunks to be written to an InputSection are recorded by the InputSection.
template <class ELFT> class Thunk {
typedef typename ELFT::uint uintX_t;
public:
Thunk(const SymbolBody &Destination, const InputSection<ELFT> &Owner);
virtual ~Thunk();
virtual uint32_t size() const { return 0; }
virtual void writeTo(uint8_t *Buf) const {}
uintX_t getVA() const;
protected:
const SymbolBody &Destination;
const InputSection<ELFT> &Owner;
uint64_t Offset;
};
// For a Relocation to symbol S from InputSection Src, create a Thunk and
// update the fields of S and the InputSection that the Thunk body will be
// written to. At present there are implementations for ARM and Mips Thunks.
template <class ELFT>
void addThunk(uint32_t RelocType, SymbolBody &S, InputSection<ELFT> &Src);
} // namespace elf
} // namespace lld
#endif
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