gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002 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     /* Assembler instructions for creating various kinds of integer object.  */
  56     const char *byte_op;
  57     struct asm_int_op
  58     {
  59       const char *hi;
  60       const char *si;
  61       const char *di;
  62       const char *ti;
  63     } aligned_op, unaligned_op;
  64
  65     /* Try to output the assembler code for an integer object whose
  66        value is given by X.  SIZE is the size of the object in bytes and
  67        ALIGNED_P indicates whether it is aligned.  Return true if
  68        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
  69        and UNALIGNED_OP are NULL.  */
  70     bool (* integer) PARAMS ((rtx x, unsigned int size, int aligned_p));
  71
  72     /* Output the assembler code for entry to a function.  */
  73     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  74
  75     /* Output the assembler code for end of prologue.  */
  76     void (* function_end_prologue) PARAMS ((FILE *));
  77
  78     /* Output the assembler code for start of epilogue.  */
  79     void (* function_begin_epilogue) PARAMS ((FILE *));
  80
  81     /* Output the assembler code for function exit.  */
  82     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  83
  84     /* Switch to an arbitrary section NAME with attributes as
  85        specified by FLAGS.  */
  86     void (* named_section) PARAMS ((const char *, unsigned int));
  87
  88     /* Switch to the section that holds the exception table.  */
  89     void (* exception_section) PARAMS ((void));
  90
  91     /* Switch to the section that holds the exception frames.  */
  92     void (* eh_frame_section) PARAMS ((void));
  93
  94     /* Output a constructor for a symbol with a given priority.  */
  95     void (* constructor) PARAMS ((rtx, int));
  96
  97     /* Output a destructor for a symbol with a given priority.  */
  98     void (* destructor) PARAMS ((rtx, int));
  99   } asm_out;
 100
 101   /* Functions relating to instruction scheduling.  */
 102   struct sched
 103   {
 104     /* Given the current cost, COST, of an insn, INSN, calculate and
 105        return a new cost based on its relationship to DEP_INSN through
 106        the dependence LINK.  The default is to make no adjustment.  */
 107     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 108
 109     /* Adjust the priority of an insn as you see fit.  Returns the new
 110        priority.  */
 111     int (* adjust_priority) PARAMS ((rtx, int));
 112
 113     /* Function which returns the maximum number of insns that can be
 114        scheduled in the same machine cycle.  This must be constant
 115        over an entire compilation.  The default is 1.  */
 116     int (* issue_rate) PARAMS ((void));
 117
 118     /* Calculate how much this insn affects how many more insns we
 119        can emit this cycle.  Default is they all cost the same.  */
 120     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 121
 122     /* Initialize machine-dependent scheduling code.  */
 123     void (* md_init) PARAMS ((FILE *, int, int));
 124
 125     /* Finalize machine-dependent scheduling code.  */
 126     void (* md_finish) PARAMS ((FILE *, int));
 127
 128     /* Reorder insns in a machine-dependent fashion, in two different
 129        places.  Default does nothing.  */
 130     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 131     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 132
 133     /* The following member value is a pointer to a function returning
 134        nonzero if we should use DFA based scheduling.  The default is
 135        to use the old pipeline scheduler.  */
 136     int (* use_dfa_pipeline_interface) PARAMS ((void));
 137     /* The values of all the following members are used only for the
 138        DFA based scheduler: */
 139     /* The values of the following four members are pointers to
 140        functions used to simplify the automaton descriptions.
 141        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 142        returning insns which are used to change the pipeline hazard
 143        recognizer state when the new simulated processor cycle
 144        correspondingly starts and finishes.  The function defined by
 145        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 146        to initialize the corresponding insns.  The default values of
 147        the memebers result in not changing the automaton state when
 148        the new simulated processor cycle correspondingly starts and
 149        finishes.  */
 150     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 151     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 152     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 153     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 154     /* The following member value is a pointer to a function returning value
 155        which defines how many insns in queue `ready' will we try for
 156        multi-pass scheduling.  if the member value is nonzero and the
 157        function returns positive value, the DFA based scheduler will make
 158        multi-pass scheduling for the first cycle.  In other words, we will
 159        try to choose ready insn which permits to start maximum number of
 160        insns on the same cycle.  */
 161     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 162     /* The values of the following members are pointers to functions
 163        used to improve the first cycle multipass scheduling by
 164        inserting nop insns.  dfa_scheduler_bubble gives a function
 165        returning a nop insn with given index.  The indexes start with
 166        zero.  The function should return NULL if there are no more nop
 167        insns with indexes greater than given index.  To initialize the
 168        nop insn the function given by member
 169        init_dfa_scheduler_bubbles is used.  The default values of the
 170        members result in not inserting nop insns during the multipass
 171        scheduling.  */
 172     void (* init_dfa_bubbles) PARAMS ((void));
 173     rtx (* dfa_bubble) PARAMS ((int));
 174   } sched;
 175
 176   /* Given two decls, merge their attributes and return the result.  */
 177   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 178
 179   /* Given two types, merge their attributes and return the result.  */
 180   tree (* merge_type_attributes) PARAMS ((tree, tree));
 181
 182   /* Table of machine attributes and functions to handle them.
 183      Ignored if NULL.  */
 184   const struct attribute_spec *attribute_table;
 185
 186   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 187      one if they are compatible and two if they are nearly compatible
 188      (which causes a warning to be generated).  */
 189   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 190
 191   /* Assign default attributes to the newly defined TYPE.  */
 192   void (* set_default_type_attributes) PARAMS ((tree type));
 193
 194   /* Insert attributes on the newly created DECL.  */
 195   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 196
 197   /* Return true if FNDECL (which has at least one machine attribute)
 198      can be inlined despite its machine attributes, false otherwise.  */
 199   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 200
 201   /* Return true if bitfields in RECORD_TYPE should follow the
 202      Microsoft Visual C++ bitfield layout rules.  */
 203   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 204
 205   /* Set up target-specific built-in functions.  */
 206   void (* init_builtins) PARAMS ((void));
 207
 208   /* Expand a target-specific builtin.  */
 209   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 210                                   enum machine_mode mode, int ignore));
 211
 212   /* Given a decl, a section name, and whether the decl initializer
 213      has relocs, choose attributes for the section.  */
 214   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 215   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 216
 217   /* True if arbitrary sections are supported.  */
 218   bool have_named_sections;
 219
 220   /* True if "native" constructors and destructors are supported,
 221      false if we're using collect2 for the job.  */
 222   bool have_ctors_dtors;
 223
 224   /* True if new jumps cannot be created, to replace existing ones or
 225      not, at the current point in the compilation.  */
 226   bool (* cannot_modify_jumps_p) PARAMS ((void));
 227 };
 228
 229 extern struct gcc_target targetm;