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// target.h -- target support for gold -*- C++ -*-
// The abstract class Target is the interface for target specific
// support. It defines abstract methods which each target must
// implement. Typically there will be one target per processor, but
// in some cases it may be necessary to have subclasses.
// For speed and consistency we want to use inline functions to handle
// relocation processing. So besides implementations of the abstract
// methods, each target is expected to define a template
// specialization of the relocation functions.
#ifndef GOLD_TARGET_H
#define GOLD_TARGET_H
#include "symtab.h"
#include "elfcpp.h"
namespace gold
{
class Object;
// The abstract class for target specific handling.
class Target
{
public:
virtual ~Target()
{ }
// Return the bit size that this target implements. This should
// return 32 or 64.
int
get_size() const
{ return this->size_; }
// Return whether this target is big-endian.
bool
is_big_endian() const
{ return this->is_big_endian_; }
// Whether this target has a specific make_symbol function.
bool
has_make_symbol() const
{ return this->has_make_symbol_; }
// Whether this target has a specific resolve function.
bool
has_resolve() const
{ return this->has_resolve_; }
// Resolve a symbol. This is called when we see a symbol with a
// target specific binding (STB_LOOS through STB_HIOS or STB_LOPROC
// through STB_HIPROC). TO is a pre-existing symbol. SYM is the
// new symbol, seen in OBJECT. This returns true on success, false
// if the symbol can not be resolved.
template<int size, bool big_endian>
bool
resolve(Sized_symbol<size>* to, const elfcpp::Sym<size, big_endian>& sym,
Object* object);
protected:
Target(int size, bool is_big_endian, bool has_make_symbol, bool has_resolve)
: size_(size),
is_big_endian_(is_big_endian),
has_make_symbol_(has_make_symbol),
has_resolve_(has_resolve)
{ }
private:
Target(const Target&);
Target& operator=(const Target&);
// The target size.
int size_;
// Whether this target is big endian.
bool is_big_endian_;
// Whether this target has a special make_symbol function.
bool has_make_symbol_;
// Whether this target has a special resolve function.
bool has_resolve_;
};
// The abstract class for a specific size and endianness of target.
// Each actual target implementation class should derive from an
// instantiation of Sized_target.
template<int size, bool big_endian>
class Sized_target : public Target
{
public:
// Make a new symbol table entry for the target. This should be
// overridden by a target which needs additional information in the
// symbol table. This will only be called if has_make_symbol()
// returns true.
virtual Sized_symbol<size>*
make_symbol()
{ abort(); }
// Resolve a symbol for the target. This should be overridden by a
// target which needs to take special action. TO is the
// pre-existing symbol. SYM is the new symbol, seen in OBJECT.
virtual void
resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*)
{ abort(); }
protected:
Sized_target(bool has_make_symbol, bool has_resolve)
: Target(size, big_endian, has_make_symbol, has_resolve)
{ }
};
} // End namespace gold.
#endif // !defined(GOLD_TARGET_H)
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