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     /* Output a constructor for a symbol with a given priority.  */
  72     void (* constructor) PARAMS ((rtx, int));
  73
  74     /* Output a destructor for a symbol with a given priority.  */
  75     void (* destructor) PARAMS ((rtx, int));
  76   } asm_out;
  77
  78   /* Functions relating to instruction scheduling.  */
  79   struct sched
  80   {
  81     /* Given the current cost, COST, of an insn, INSN, calculate and
  82        return a new cost based on its relationship to DEP_INSN through
  83        the dependence LINK.  The default is to make no adjustment.  */
  84     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
  85
  86     /* Adjust the priority of an insn as you see fit.  Returns the new
  87        priority.  */
  88     int (* adjust_priority) PARAMS ((rtx, int));
  89
  90     /* Function which returns the maximum number of insns that can be
  91        scheduled in the same machine cycle.  This must be constant
  92        over an entire compilation.  The default is 1.  */
  93     int (* issue_rate) PARAMS ((void));
  94
  95     /* Calculate how much this insn affects how many more insns we
  96        can emit this cycle.  Default is they all cost the same.  */
  97     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
  98
  99     /* Initialize machine-dependent scheduling code.  */
 100     void (* md_init) PARAMS ((FILE *, int, int));
 101
 102     /* Finalize machine-dependent scheduling code.  */
 103     void (* md_finish) PARAMS ((FILE *, int));
 104
 105     /* Reorder insns in a machine-dependent fashion, in two different
 106        places.  Default does nothing.  */
 107     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 108     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 109
 110     /* cycle_display is a pointer to a function which can emit
 111        data into the assembly stream about the current cycle.
 112        Arguments are CLOCK, the data to emit, and LAST, the last
 113        insn in the new chain we're building.  Returns a new LAST.
 114        The default is to do nothing.  */
 115     rtx (* cycle_display) PARAMS ((int clock, rtx last));
 116     /* The following member value is a pointer to a function returning
 117        nonzero if we should use DFA based scheduling.  The default is
 118        to use the old pipeline scheduler.  */
 119     int (* use_dfa_pipeline_interface) PARAMS ((void));
 120     /* The values of all the following members are used only for the
 121        DFA based scheduler: */
 122     /* The values of the following four members are pointers to
 123        functions used to simplify the automaton descriptions.
 124        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 125        returning insns which are used to change the pipeline hazard
 126        recognizer state when the new simulated processor cycle
 127        correspondingly starts and finishes.  The function defined by
 128        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 129        to initialize the corresponding insns.  The default values of
 130        the memebers result in not changing the automaton state when
 131        the new simulated processor cycle correspondingly starts and
 132        finishes.  */
 133     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 134     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 135     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 136     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 137     /* The following member value is a pointer to a function returning value
 138        which defines how many insns in queue `ready' will we try for
 139        multi-pass scheduling.  if the member value is nonzero and the
 140        function returns positive value, the DFA based scheduler will make
 141        multi-pass scheduling for the first cycle.  In other words, we will
 142        try to choose ready insn which permits to start maximum number of
 143        insns on the same cycle.  */
 144     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 145     /* The values of the following members are pointers to functions
 146        used to improve the first cycle multipass scheduling by
 147        inserting nop insns.  dfa_scheduler_bubble gives a function
 148        returning a nop insn with given index.  The indexes start with
 149        zero.  The function should return NULL if there are no more nop
 150        insns with indexes greater than given index.  To initialize the
 151        nop insn the function given by member
 152        init_dfa_scheduler_bubbles is used.  The default values of the
 153        members result in not inserting nop insns during the multipass
 154        scheduling.  */
 155     void (* init_dfa_bubbles) PARAMS ((void));
 156     rtx (* dfa_bubble) PARAMS ((int));
 157   } sched;
 158
 159   /* Given two decls, merge their attributes and return the result.  */
 160   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 161
 162   /* Given two types, merge their attributes and return the result.  */
 163   tree (* merge_type_attributes) PARAMS ((tree, tree));
 164
 165   /* Return nonzero if IDENTIFIER with arguments ARGS is a valid machine
 166      specific attribute for DECL.  The attributes in ATTRIBUTES have
 167      previously been assigned to DECL.  */
 168   int (* valid_decl_attribute) PARAMS ((tree decl, tree attributes,
 169                                         tree identifier, tree args));
 170
 171   /* Return nonzero if IDENTIFIER with arguments ARGS is a valid machine
 172      specific attribute for TYPE.  The attributes in ATTRIBUTES have
 173      previously been assigned to TYPE.  */
 174   int (* valid_type_attribute) PARAMS ((tree type, tree attributes,
 175                                         tree identifier, tree args));
 176
 177   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 178      one if they are compatible and two if they are nearly compatible
 179      (which causes a warning to be generated).  */
 180   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 181
 182   /* Assign default attributes to the newly defined TYPE.  */
 183   void (* set_default_type_attributes) PARAMS ((tree type));
 184
 185   /* Insert attributes on the newly created DECL.  */
 186   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 187
 188   /* Set up target-specific built-in functions.  */
 189   void (* init_builtins) PARAMS ((void));
 190
 191   /* Expand a target-specific builtin.  */
 192   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 193                                   enum machine_mode mode, int ignore));
 194
 195   /* Given a decl, a section name, and whether the decl initializer
 196      has relocs, choose attributes for the section.  */
 197   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 198   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 199
 200   /* True if arbitrary sections are supported.  */
 201   bool have_named_sections;
 202
 203   /* True if "native" constructors and destructors are supported,
 204      false if we're using collect2 for the job.  */
 205   bool have_ctors_dtors;
 206 };
 207
 208 extern struct gcc_target targetm;