+// target-select.h -- select a target for an object file -*- C++ -*-
+
+// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
+// Written by Ian Lance Taylor <iant@google.com>.
+
+// This file is part of gold.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
+// MA 02110-1301, USA.
+
+#ifndef GOLD_TARGET_SELECT_H
+#define GOLD_TARGET_SELECT_H
+
+#include <vector>
+
+#include "gold-threads.h"
+
+namespace gold
+{
+
+class Target;
+
+// We want to avoid a master list of targets, which implies using a
+// global constructor. And we also want the program to start up as
+// quickly as possible, which implies avoiding global constructors.
+// We compromise on a very simple global constructor. We use a target
+// selector, which specifies an ELF machine number and a recognition
+// function. We use global constructors to build a linked list of
+// target selectors--a simple pointer list, not a std::list.
+
+class Target_selector
+{
+ public:
+ // Create a target selector for a specific machine number, size (32
+ // or 64), and endianness. The machine number can be EM_NONE to
+ // test for any machine number. BFD_NAME is the name of the target
+ // used by the GNU linker, for backward compatibility; it may be
+ // NULL.
+ Target_selector(int machine, int size, bool is_big_endian,
+ const char* bfd_name);
+
+ virtual ~Target_selector()
+ { }
+
+ // If we can handle this target, return a pointer to a target
+ // structure. The size and endianness are known.
+ Target*
+ recognize(int machine, int osabi, int abiversion)
+ { return this->do_recognize(machine, osabi, abiversion); }
+
+ // If NAME matches the target, return a pointer to a target
+ // structure.
+ Target*
+ recognize_by_name(const char* name)
+ { return this->do_recognize_by_name(name); }
+
+ // Push all supported names onto the vector. This is only used for
+ // help output.
+ void
+ supported_names(std::vector<const char*>* names)
+ { this->do_supported_names(names); }
+
+ // Return the next Target_selector in the linked list.
+ Target_selector*
+ next() const
+ { return this->next_; }
+
+ // Return the machine number this selector is looking for. This can
+ // be EM_NONE to match any machine number, in which case the
+ // do_recognize hook will be responsible for matching the machine
+ // number.
+ int
+ machine() const
+ { return this->machine_; }
+
+ // Return the size this is looking for (32 or 64).
+ int
+ get_size() const
+ { return this->size_; }
+
+ // Return the endianness this is looking for.
+ bool
+ is_big_endian() const
+ { return this->is_big_endian_; }
+
+ // Return the BFD name. This may return NULL, in which case the
+ // do_recognize_by_name hook will be responsible for matching the
+ // BFD name.
+ const char*
+ bfd_name() const
+ { return this->bfd_name_; }
+
+ protected:
+ // Return an instance of the real target. This must be implemented
+ // by the child class.
+ virtual Target*
+ do_instantiate_target() = 0;
+
+ // Recognize an object file given a machine code, OSABI code, and
+ // ELF version value. When this is called we already know that they
+ // match the machine_, size_, and is_big_endian_ fields. The child
+ // class may implement a different version of this to do additional
+ // checks, or to check for multiple machine codes if the machine_
+ // field is EM_NONE.
+ virtual Target*
+ do_recognize(int, int, int)
+ { return this->instantiate_target(); }
+
+ // Recognize a target by name. When this is called we already know
+ // that the name matches (or that the bfd_name_ field is NULL). The
+ // child class may implement a different version of this to
+ // recognize more than one name.
+ virtual Target*
+ do_recognize_by_name(const char*)
+ { return this->instantiate_target(); }
+
+ // Return a list of supported BFD names. The child class may
+ // implement a different version of this to handle more than one
+ // name.
+ virtual void
+ do_supported_names(std::vector<const char*>* names)
+ {
+ gold_assert(this->bfd_name_ != NULL);
+ names->push_back(this->bfd_name_);
+ }
+
+ // Instantiate the target and return it.
+ Target*
+ instantiate_target();
+
+ private:
+ // ELF machine code.
+ const int machine_;
+ // Target size--32 or 64.
+ const int size_;
+ // Whether the target is big endian.
+ const bool is_big_endian_;
+ // BFD name of target, for compatibility.
+ const char* const bfd_name_;
+ // Next entry in list built at global constructor time.
+ Target_selector* next_;
+ // The singleton Target structure--this points to an instance of the
+ // real implementation.
+ Target* instantiated_target_;
+ // Lock to make sure that we don't instantiate the target more than
+ // once.
+ Lock* lock_;
+ // We only want to initialize the lock_ pointer once.
+ Initialize_lock initialize_lock_;
+};
+
+// Select the target for an ELF file.
+
+extern Target*
+select_target(int machine, int size, bool big_endian, int osabi,
+ int abiversion);
+
+// Select a target using a BFD name.
+
+extern Target*
+select_target_by_name(const char* name);
+
+// Fill in a vector with the list of supported targets. This returns
+// a list of BFD names.
+
+extern void
+supported_target_names(std::vector<const char*>*);
+
+} // End namespace gold.
+
+#endif // !defined(GOLD_TARGET_SELECT_H)