gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001 Free Software Foundation, Inc.
   3
   4 This program is free software; you can redistribute it and/or modify it
   5 under the terms of the GNU General Public License as published by the
   6 Free Software Foundation; either version 2, or (at your option) any
   7 later version.
   8
   9 This program is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17
  18  In other words, you are welcome to use, share and improve this program.
  19  You are forbidden to forbid anyone else to use, share and improve
  20  what you give them.   Help stamp out software-hoarding!  */
  21
  22 /* This file contains a data structure that describes a GCC target.
  23    At present, it is incomplete, but in future it should grow to
  24    contain most or all target machine and target O/S specific
  25    information.
  26
  27    This structure has its initializer declared in target-def.h in the
  28    form of large macro TARGET_INITIALIZER that expands to many smaller
  29    macros.
  30
  31    The smaller macros each initialize one component of the structure,
  32    and each has a default.  Each target should have a file that
  33    includes target.h and target-def.h, and overrides any inappropriate
  34    defaults by undefining the relevant macro and defining a suitable
  35    replacement.  That file should then contain the definition of
  36    "target" like so:
  37
  38    struct gcc_target target = TARGET_INITIALIZER;
  39
  40    Doing things this way allows us to bring together everything that
  41    defines a target to GCC.  By supplying a default that is
  42    appropriate to most targets, we can easily add new items without
  43    needing to edit dozens of target configuration files.  It should
  44    also allow us to gradually reduce the amount of conditional
  45    compilation that is scattered throughout GCC.  */
  46
  47 struct gcc_target
  48 {
  49   /* Functions that output assembler for the target.  */
  50   struct asm_out
  51   {
  52     /* Output the assembler code for entry to a function.  */
  53     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  54
  55     /* Output the assembler code for function exit.  */
  56     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  57   } asm_out;
  58
  59   /* Given two decls, merge their attributes and return the result.  */
  60   tree (* merge_decl_attributes) PARAMS ((tree, tree));
  61
  62   /* Given two types, merge their attributes and return the result.  */
  63   tree (* merge_type_attributes) PARAMS ((tree, tree));
  64
  65   /* Return nonzero if IDENTIFIER with arguments ARGS is a valid machine
  66      specific attribute for DECL.  The attributes in ATTRIBUTES have
  67      previously been assigned to DECL.  */
  68   int (* valid_decl_attribute) PARAMS ((tree decl, tree attributes,
  69                                         tree identifier, tree args));
  70
  71   /* Return nonzero if IDENTIFIER with arguments ARGS is a valid machine
  72      specific attribute for TYPE.  The attributes in ATTRIBUTES have
  73      previously been assigned to TYPE.  */
  74   int (* valid_type_attribute) PARAMS ((tree type, tree attributes,
  75                                         tree identifier, tree args));
  76
  77   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
  78      one if they are compatible and two if they are nearly compatible
  79      (which causes a warning to be generated).  */
  80   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
  81
  82   /* Assign default attributes to the newly defined TYPE.  */
  83   void (* set_default_type_attributes) PARAMS ((tree type));
  84 };
  85
  86 extern struct gcc_target target;