gold/target-select.h

   1 // target-select.h -- select a target for an object file  -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #ifndef GOLD_TARGET_SELECT_H
  24 #define GOLD_TARGET_SELECT_H
  25
  26 #include <vector>
  27
  28 namespace gold
  29 {
  30
  31 class Target;
  32
  33 // We want to avoid a master list of targets, which implies using a
  34 // global constructor.  And we also want the program to start up as
  35 // quickly as possible, which implies avoiding global constructors.
  36 // We compromise on a very simple global constructor.  We use a target
  37 // selector, which specifies an ELF machine number and a recognition
  38 // function.  We use global constructors to build a linked list of
  39 // target selectors--a simple pointer list, not a std::list.
  40
  41 class Target_selector
  42 {
  43  public:
  44   // Create a target selector for a specific machine number, size (32
  45   // or 64), and endianness.  The machine number can be EM_NONE to
  46   // test for any machine number.  BFD_NAME is the name of the target
  47   // used by the GNU linker, for backward compatibility; it may be
  48   // NULL.
  49   Target_selector(int machine, int size, bool is_big_endian,
  50                   const char* bfd_name);
  51
  52   virtual ~Target_selector()
  53   { }
  54
  55   // If we can handle this target, return a pointer to a target
  56   // structure.  The size and endianness are known.
  57   Target*
  58   recognize(int machine, int osabi, int abiversion)
  59   { return this->do_recognize(machine, osabi, abiversion); }
  60
  61   // If NAME matches the target, return a pointer to a target
  62   // structure.
  63   Target*
  64   recognize_by_name(const char* name)
  65   { return this->do_recognize_by_name(name); }
  66
  67   // Push all supported names onto the vector.  This is only used for
  68   // help output.
  69   void
  70   supported_names(std::vector<const char*>* names)
  71   { this->do_supported_names(names); }
  72
  73   // Return the next Target_selector in the linked list.
  74   Target_selector*
  75   next() const
  76   { return this->next_; }
  77
  78   // Return the machine number this selector is looking for.  This can
  79   // be EM_NONE to match any machine number, in which case the
  80   // do_recognize hook will be responsible for matching the machine
  81   // number.
  82   int
  83   machine() const
  84   { return this->machine_; }
  85
  86   // Return the size this is looking for (32 or 64).
  87   int
  88   get_size() const
  89   { return this->size_; }
  90
  91   // Return the endianness this is looking for.
  92   bool
  93   is_big_endian() const
  94   { return this->is_big_endian_; }
  95
  96   // Return the BFD name.  This may return NULL, in which case the
  97   // do_recognize_by_name hook will be responsible for matching the
  98   // BFD name.
  99   const char*
 100   bfd_name() const
 101   { return this->bfd_name_; }
 102
 103  protected:
 104   // Return an instance of the real target.  This must be implemented
 105   // by the child class.
 106   virtual Target*
 107   do_instantiate_target() = 0;
 108
 109   // Recognize an object file given a machine code, OSABI code, and
 110   // ELF version value.  When this is called we already know that they
 111   // match the machine_, size_, and is_big_endian_ fields.  The child
 112   // class may implement a different version of this to do additional
 113   // checks, or to check for multiple machine codes if the machine_
 114   // field is EM_NONE.
 115   virtual Target*
 116   do_recognize(int, int, int)
 117   { return this->instantiate_target(); }
 118
 119   // Recognize a target by name.  When this is called we already know
 120   // that the name matches (or that the bfd_name_ field is NULL).  The
 121   // child class may implement a different version of this to
 122   // recognize more than one name.
 123   virtual Target*
 124   do_recognize_by_name(const char*)
 125   { return this->instantiate_target(); }
 126
 127   // Return a list of supported BFD names.  The child class may
 128   // implement a different version of this to handle more than one
 129   // name.
 130   virtual void
 131   do_supported_names(std::vector<const char*>* names)
 132   {
 133     gold_assert(this->bfd_name_ != NULL);
 134     names->push_back(this->bfd_name_);
 135   }
 136
 137   // Instantiate the target and return it.
 138   Target*
 139   instantiate_target()
 140   {
 141     if (this->instantiated_target_ == NULL)
 142       this->instantiated_target_ = this->do_instantiate_target();
 143     return this->instantiated_target_;
 144   }
 145
 146  private:
 147   // ELF machine code.
 148   const int machine_;
 149   // Target size--32 or 64.
 150   const int size_;
 151   // Whether the target is big endian.
 152   const bool is_big_endian_;
 153   // BFD name of target, for compatibility.
 154   const char* const bfd_name_;
 155   // Next entry in list built at global constructor time.
 156   Target_selector* next_;
 157   // The singleton Target structure--this points to an instance of the
 158   // real implementation.
 159   Target* instantiated_target_;
 160 };
 161
 162 // Select the target for an ELF file.
 163
 164 extern Target*
 165 select_target(int machine, int size, bool big_endian, int osabi,
 166               int abiversion);
 167
 168 // Select a target using a BFD name.
 169
 170 extern Target*
 171 select_target_by_name(const char* name);
 172
 173 // Fill in a vector with the list of supported targets.  This returns
 174 // a list of BFD names.
 175
 176 extern void
 177 supported_target_names(std::vector<const char*>*);
 178
 179 } // End namespace gold.
 180
 181 #endif // !defined(GOLD_TARGET_SELECT_H)