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    "targetm" like so:
  37
  38    struct gcc_target targetm = TARGET_INITIALIZER;
  39
  40    Doing things this way allows us to bring together everything that
  41    defines a GCC target.  By supplying a default that is appropriate
  42    to most targets, we can easily add new items without needing to
  43    edit dozens of target configuration files.  It should also allow us
  44    to gradually reduce the amount of conditional compilation that is
  45    scattered throughout GCC.  */
  46
  47 struct gcc_target
  48 {
  49   /* Functions that output assembler for the target.  */
  50   struct asm_out
  51   {
  52     /* Opening and closing parentheses for asm expression grouping.  */
  53     const char *open_paren, *close_paren;
  54
  55     /* Output the assembler code for entry to a function.  */
  56     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  57
  58     /* Output the assembler code for end of prologue.  */
  59     void (* function_end_prologue) PARAMS ((FILE *));
  60
  61     /* Output the assembler code for start of epilogue.  */
  62     void (* function_begin_epilogue) PARAMS ((FILE *));
  63
  64     /* Output the assembler code for function exit.  */
  65     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  66
  67     /* Switch to an arbitrary section NAME with attributes as
  68        specified by FLAGS.  */
  69     void (* named_section) PARAMS ((const char *, unsigned int));
  70
  71     /* Switch to the section that holds the exception table.  */
  72     void (* exception_section) PARAMS ((void));
  73
  74     /* Switch to the section that holds the exception frames.  */
  75     void (* eh_frame_section) PARAMS ((void));
  76
  77     /* Output a constructor for a symbol with a given priority.  */
  78     void (* constructor) PARAMS ((rtx, int));
  79
  80     /* Output a destructor for a symbol with a given priority.  */
  81     void (* destructor) PARAMS ((rtx, int));
  82   } asm_out;
  83
  84   /* Functions relating to instruction scheduling.  */
  85   struct sched
  86   {
  87     /* Given the current cost, COST, of an insn, INSN, calculate and
  88        return a new cost based on its relationship to DEP_INSN through
  89        the dependence LINK.  The default is to make no adjustment.  */
  90     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
  91
  92     /* Adjust the priority of an insn as you see fit.  Returns the new
  93        priority.  */
  94     int (* adjust_priority) PARAMS ((rtx, int));
  95
  96     /* Function which returns the maximum number of insns that can be
  97        scheduled in the same machine cycle.  This must be constant
  98        over an entire compilation.  The default is 1.  */
  99     int (* issue_rate) PARAMS ((void));
 100
 101     /* Calculate how much this insn affects how many more insns we
 102        can emit this cycle.  Default is they all cost the same.  */
 103     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 104
 105     /* Initialize machine-dependent scheduling code.  */
 106     void (* md_init) PARAMS ((FILE *, int, int));
 107
 108     /* Finalize machine-dependent scheduling code.  */
 109     void (* md_finish) PARAMS ((FILE *, int));
 110
 111     /* Reorder insns in a machine-dependent fashion, in two different
 112        places.  Default does nothing.  */
 113     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 114     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 115
 116     /* cycle_display is a pointer to a function which can emit
 117        data into the assembly stream about the current cycle.
 118        Arguments are CLOCK, the data to emit, and LAST, the last
 119        insn in the new chain we're building.  Returns a new LAST.
 120        The default is to do nothing.  */
 121     rtx (* cycle_display) PARAMS ((int clock, rtx last));
 122   } sched;
 123
 124   /* Given two decls, merge their attributes and return the result.  */
 125   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 126
 127   /* Given two types, merge their attributes and return the result.  */
 128   tree (* merge_type_attributes) PARAMS ((tree, tree));
 129
 130   /* Table of machine attributes and functions to handle them.  */
 131   const struct attribute_spec *attribute_table;
 132
 133   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 134      one if they are compatible and two if they are nearly compatible
 135      (which causes a warning to be generated).  */
 136   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 137
 138   /* Assign default attributes to the newly defined TYPE.  */
 139   void (* set_default_type_attributes) PARAMS ((tree type));
 140
 141   /* Insert attributes on the newly created DECL.  */
 142   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 143
 144   /* Return true if FNDECL (which has at least one machine attribute)
 145      can be inlined despite its machine attributes, false otherwise.  */
 146   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 147
 148   /* Set up target-specific built-in functions.  */
 149   void (* init_builtins) PARAMS ((void));
 150
 151   /* Expand a target-specific builtin.  */
 152   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 153                                   enum machine_mode mode, int ignore));
 154
 155   /* Given a decl, a section name, and whether the decl initializer
 156      has relocs, choose attributes for the section.  */
 157   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 158   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 159
 160   /* True if arbitrary sections are supported.  */
 161   bool have_named_sections;
 162
 163   /* True if "native" constructors and destructors are supported,
 164      false if we're using collect2 for the job.  */
 165   bool have_ctors_dtors;
 166 };
 167
 168 extern struct gcc_target targetm;