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 cpp_reader;
  48
  49 struct gcc_target
  50 {
  51   /* Functions that output assembler for the target.  */
  52   struct asm_out
  53   {
  54     /* Opening and closing parentheses for asm expression grouping.  */
  55     const char *open_paren, *close_paren;
  56
  57     /* Assembler instructions for creating various kinds of integer object.  */
  58     const char *byte_op;
  59     struct asm_int_op
  60     {
  61       const char *hi;
  62       const char *si;
  63       const char *di;
  64       const char *ti;
  65     } aligned_op, unaligned_op;
  66
  67     /* Try to output the assembler code for an integer object whose
  68        value is given by X.  SIZE is the size of the object in bytes and
  69        ALIGNED_P indicates whether it is aligned.  Return true if
  70        successful.  Only handles cases for which BYTE_OP, ALIGNED_OP
  71        and UNALIGNED_OP are NULL.  */
  72     bool (* integer) PARAMS ((rtx x, unsigned int size, int aligned_p));
  73
  74     /* Output the assembler code for entry to a function.  */
  75     void (* function_prologue) PARAMS ((FILE *, HOST_WIDE_INT));
  76
  77     /* Output the assembler code for end of prologue.  */
  78     void (* function_end_prologue) PARAMS ((FILE *));
  79
  80     /* Output the assembler code for start of epilogue.  */
  81     void (* function_begin_epilogue) PARAMS ((FILE *));
  82
  83     /* Output the assembler code for function exit.  */
  84     void (* function_epilogue) PARAMS ((FILE *, HOST_WIDE_INT));
  85
  86     /* Switch to an arbitrary section NAME with attributes as
  87        specified by FLAGS.  */
  88     void (* named_section) PARAMS ((const char *, unsigned int));
  89
  90     /* Switch to the section that holds the exception table.  */
  91     void (* exception_section) PARAMS ((void));
  92
  93     /* Switch to the section that holds the exception frames.  */
  94     void (* eh_frame_section) PARAMS ((void));
  95
  96     /* Output a constructor for a symbol with a given priority.  */
  97     void (* constructor) PARAMS ((rtx, int));
  98
  99     /* Output a destructor for a symbol with a given priority.  */
 100     void (* destructor) PARAMS ((rtx, int));
 101   } asm_out;
 102
 103   /* Functions relating to instruction scheduling.  */
 104   struct sched
 105   {
 106     /* Given the current cost, COST, of an insn, INSN, calculate and
 107        return a new cost based on its relationship to DEP_INSN through
 108        the dependence LINK.  The default is to make no adjustment.  */
 109     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 110
 111     /* Adjust the priority of an insn as you see fit.  Returns the new
 112        priority.  */
 113     int (* adjust_priority) PARAMS ((rtx, int));
 114
 115     /* Function which returns the maximum number of insns that can be
 116        scheduled in the same machine cycle.  This must be constant
 117        over an entire compilation.  The default is 1.  */
 118     int (* issue_rate) PARAMS ((void));
 119
 120     /* Calculate how much this insn affects how many more insns we
 121        can emit this cycle.  Default is they all cost the same.  */
 122     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 123
 124     /* Initialize machine-dependent scheduling code.  */
 125     void (* md_init) PARAMS ((FILE *, int, int));
 126
 127     /* Finalize machine-dependent scheduling code.  */
 128     void (* md_finish) PARAMS ((FILE *, int));
 129
 130     /* Reorder insns in a machine-dependent fashion, in two different
 131        places.  Default does nothing.  */
 132     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 133     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 134
 135     /* The following member value is a pointer to a function returning
 136        nonzero if we should use DFA based scheduling.  The default is
 137        to use the old pipeline scheduler.  */
 138     int (* use_dfa_pipeline_interface) PARAMS ((void));
 139     /* The values of all the following members are used only for the
 140        DFA based scheduler: */
 141     /* The values of the following four members are pointers to
 142        functions used to simplify the automaton descriptions.
 143        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 144        returning insns which are used to change the pipeline hazard
 145        recognizer state when the new simulated processor cycle
 146        correspondingly starts and finishes.  The function defined by
 147        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 148        to initialize the corresponding insns.  The default values of
 149        the memebers result in not changing the automaton state when
 150        the new simulated processor cycle correspondingly starts and
 151        finishes.  */
 152     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 153     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 154     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 155     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 156     /* The following member value is a pointer to a function returning value
 157        which defines how many insns in queue `ready' will we try for
 158        multi-pass scheduling.  if the member value is nonzero and the
 159        function returns positive value, the DFA based scheduler will make
 160        multi-pass scheduling for the first cycle.  In other words, we will
 161        try to choose ready insn which permits to start maximum number of
 162        insns on the same cycle.  */
 163     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 164     /* The values of the following members are pointers to functions
 165        used to improve the first cycle multipass scheduling by
 166        inserting nop insns.  dfa_scheduler_bubble gives a function
 167        returning a nop insn with given index.  The indexes start with
 168        zero.  The function should return NULL if there are no more nop
 169        insns with indexes greater than given index.  To initialize the
 170        nop insn the function given by member
 171        init_dfa_scheduler_bubbles is used.  The default values of the
 172        members result in not inserting nop insns during the multipass
 173        scheduling.  */
 174     void (* init_dfa_bubbles) PARAMS ((void));
 175     rtx (* dfa_bubble) PARAMS ((int));
 176   } sched;
 177
 178   /* Given two decls, merge their attributes and return the result.  */
 179   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 180
 181   /* Given two types, merge their attributes and return the result.  */
 182   tree (* merge_type_attributes) PARAMS ((tree, tree));
 183
 184   /* Table of machine attributes and functions to handle them.
 185      Ignored if NULL.  */
 186   const struct attribute_spec *attribute_table;
 187
 188   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 189      one if they are compatible and two if they are nearly compatible
 190      (which causes a warning to be generated).  */
 191   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 192
 193   /* Assign default attributes to the newly defined TYPE.  */
 194   void (* set_default_type_attributes) PARAMS ((tree type));
 195
 196   /* Insert attributes on the newly created DECL.  */
 197   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 198
 199   /* Return true if FNDECL (which has at least one machine attribute)
 200      can be inlined despite its machine attributes, false otherwise.  */
 201   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 202
 203   void (* register_cpp_builtins) PARAMS ((struct cpp_reader *));
 204
 205   /* Return true if bitfields in RECORD_TYPE should follow the
 206      Microsoft Visual C++ bitfield layout rules.  */
 207   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 208
 209   /* Set up target-specific built-in functions.  */
 210   void (* init_builtins) PARAMS ((void));
 211
 212   /* Expand a target-specific builtin.  */
 213   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 214                                   enum machine_mode mode, int ignore));
 215
 216   /* Given a decl, a section name, and whether the decl initializer
 217      has relocs, choose attributes for the section.  */
 218   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 219   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 220
 221   /* True if arbitrary sections are supported.  */
 222   bool have_named_sections;
 223
 224   /* True if "native" constructors and destructors are supported,
 225      false if we're using collect2 for the job.  */
 226   bool have_ctors_dtors;
 227
 228   /* True if new jumps cannot be created, to replace existing ones or
 229      not, at the current point in the compilation.  */
 230   bool (* cannot_modify_jumps_p) PARAMS ((void));
 231 };
 232
 233 extern struct gcc_target targetm;