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     /* Select and switch to a section for EXP.  It may be a DECL or a
  95        constant for which TREE_CST_RTL is valid.  RELOC is non-zero if
  96        runtime relocations must be applied; bit 1 will be set if the
  97        runtime relocations require non-local name resolution.  ALIGN is
  98        the required alignment of the data.  */
  99     void (* select_section) PARAMS ((tree, int, unsigned HOST_WIDE_INT));
 100
 101     /* Select a unique section name for DECL.  RELOC is the same as
 102        for SELECT_SECTION.  */
 103     void (* unique_section) PARAMS ((tree, int));
 104
 105     /* Output a constructor for a symbol with a given priority.  */
 106     void (* constructor) PARAMS ((rtx, int));
 107
 108     /* Output a destructor for a symbol with a given priority.  */
 109     void (* destructor) PARAMS ((rtx, int));
 110   } asm_out;
 111
 112   /* Functions relating to instruction scheduling.  */
 113   struct sched
 114   {
 115     /* Given the current cost, COST, of an insn, INSN, calculate and
 116        return a new cost based on its relationship to DEP_INSN through
 117        the dependence LINK.  The default is to make no adjustment.  */
 118     int (* adjust_cost) PARAMS ((rtx insn, rtx link, rtx def_insn, int cost));
 119
 120     /* Adjust the priority of an insn as you see fit.  Returns the new
 121        priority.  */
 122     int (* adjust_priority) PARAMS ((rtx, int));
 123
 124     /* Function which returns the maximum number of insns that can be
 125        scheduled in the same machine cycle.  This must be constant
 126        over an entire compilation.  The default is 1.  */
 127     int (* issue_rate) PARAMS ((void));
 128
 129     /* Calculate how much this insn affects how many more insns we
 130        can emit this cycle.  Default is they all cost the same.  */
 131     int (* variable_issue) PARAMS ((FILE *, int, rtx, int));
 132
 133     /* Initialize machine-dependent scheduling code.  */
 134     void (* md_init) PARAMS ((FILE *, int, int));
 135
 136     /* Finalize machine-dependent scheduling code.  */
 137     void (* md_finish) PARAMS ((FILE *, int));
 138
 139     /* Reorder insns in a machine-dependent fashion, in two different
 140        places.  Default does nothing.  */
 141     int (* reorder)  PARAMS ((FILE *, int, rtx *, int *, int));
 142     int (* reorder2) PARAMS ((FILE *, int, rtx *, int *, int));
 143
 144     /* The following member value is a pointer to a function returning
 145        nonzero if we should use DFA based scheduling.  The default is
 146        to use the old pipeline scheduler.  */
 147     int (* use_dfa_pipeline_interface) PARAMS ((void));
 148     /* The values of all the following members are used only for the
 149        DFA based scheduler: */
 150     /* The values of the following four members are pointers to
 151        functions used to simplify the automaton descriptions.
 152        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 153        returning insns which are used to change the pipeline hazard
 154        recognizer state when the new simulated processor cycle
 155        correspondingly starts and finishes.  The function defined by
 156        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 157        to initialize the corresponding insns.  The default values of
 158        the memebers result in not changing the automaton state when
 159        the new simulated processor cycle correspondingly starts and
 160        finishes.  */
 161     void (* init_dfa_pre_cycle_insn) PARAMS ((void));
 162     rtx (* dfa_pre_cycle_insn) PARAMS ((void));
 163     void (* init_dfa_post_cycle_insn) PARAMS ((void));
 164     rtx (* dfa_post_cycle_insn) PARAMS ((void));
 165     /* The following member value is a pointer to a function returning value
 166        which defines how many insns in queue `ready' will we try for
 167        multi-pass scheduling.  if the member value is nonzero and the
 168        function returns positive value, the DFA based scheduler will make
 169        multi-pass scheduling for the first cycle.  In other words, we will
 170        try to choose ready insn which permits to start maximum number of
 171        insns on the same cycle.  */
 172     int (* first_cycle_multipass_dfa_lookahead) PARAMS ((void));
 173     /* The values of the following members are pointers to functions
 174        used to improve the first cycle multipass scheduling by
 175        inserting nop insns.  dfa_scheduler_bubble gives a function
 176        returning a nop insn with given index.  The indexes start with
 177        zero.  The function should return NULL if there are no more nop
 178        insns with indexes greater than given index.  To initialize the
 179        nop insn the function given by member
 180        init_dfa_scheduler_bubbles is used.  The default values of the
 181        members result in not inserting nop insns during the multipass
 182        scheduling.  */
 183     void (* init_dfa_bubbles) PARAMS ((void));
 184     rtx (* dfa_bubble) PARAMS ((int));
 185   } sched;
 186
 187   /* Given two decls, merge their attributes and return the result.  */
 188   tree (* merge_decl_attributes) PARAMS ((tree, tree));
 189
 190   /* Given two types, merge their attributes and return the result.  */
 191   tree (* merge_type_attributes) PARAMS ((tree, tree));
 192
 193   /* Table of machine attributes and functions to handle them.
 194      Ignored if NULL.  */
 195   const struct attribute_spec *attribute_table;
 196
 197   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 198      one if they are compatible and two if they are nearly compatible
 199      (which causes a warning to be generated).  */
 200   int (* comp_type_attributes) PARAMS ((tree type1, tree type2));
 201
 202   /* Assign default attributes to the newly defined TYPE.  */
 203   void (* set_default_type_attributes) PARAMS ((tree type));
 204
 205   /* Insert attributes on the newly created DECL.  */
 206   void (* insert_attributes) PARAMS ((tree decl, tree *attributes));
 207
 208   /* Return true if FNDECL (which has at least one machine attribute)
 209      can be inlined despite its machine attributes, false otherwise.  */
 210   bool (* function_attribute_inlinable_p) PARAMS ((tree fndecl));
 211
 212   /* Return true if bitfields in RECORD_TYPE should follow the
 213      Microsoft Visual C++ bitfield layout rules.  */
 214   bool (* ms_bitfield_layout_p) PARAMS ((tree record_type));
 215
 216   /* Set up target-specific built-in functions.  */
 217   void (* init_builtins) PARAMS ((void));
 218
 219   /* Expand a target-specific builtin.  */
 220   rtx (* expand_builtin) PARAMS ((tree exp, rtx target, rtx subtarget,
 221                                   enum machine_mode mode, int ignore));
 222
 223   /* Given a decl, a section name, and whether the decl initializer
 224      has relocs, choose attributes for the section.  */
 225   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 226   unsigned int (* section_type_flags) PARAMS ((tree, const char *, int));
 227
 228   /* True if arbitrary sections are supported.  */
 229   bool have_named_sections;
 230
 231   /* True if "native" constructors and destructors are supported,
 232      false if we're using collect2 for the job.  */
 233   bool have_ctors_dtors;
 234
 235   /* True if new jumps cannot be created, to replace existing ones or
 236      not, at the current point in the compilation.  */
 237   bool (* cannot_modify_jumps_p) PARAMS ((void));
 238
 239   /* True if EXP should be placed in a "small data" section.  */
 240   bool (* in_small_data_p) PARAMS ((tree));
 241 };
 242
 243 extern struct gcc_target targetm;