gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002, 2003 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) (rtx x, unsigned int size, int aligned_p);
  71
  72     /* Output code that will globalize a label.  */
  73     void (* globalize_label) (FILE *, const char *);
  74
  75     /* Output an internal label.  */
  76     void (* internal_label) (FILE *, const char *, unsigned long);
  77
  78     /* Emit an assembler directive to set visibility for the symbol
  79        associated with the tree decl.  */
  80     void (* visibility) (tree, int);
  81
  82     /* Output the assembler code for entry to a function.  */
  83     void (* function_prologue) (FILE *, HOST_WIDE_INT);
  84
  85     /* Output the assembler code for end of prologue.  */
  86     void (* function_end_prologue) (FILE *);
  87
  88     /* Output the assembler code for start of epilogue.  */
  89     void (* function_begin_epilogue) (FILE *);
  90
  91     /* Output the assembler code for function exit.  */
  92     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
  93
  94     /* Switch to an arbitrary section NAME with attributes as
  95        specified by FLAGS.  */
  96     void (* named_section) (const char *, unsigned int);
  97
  98     /* Switch to the section that holds the exception table.  */
  99     void (* exception_section) (void);
 100
 101     /* Switch to the section that holds the exception frames.  */
 102     void (* eh_frame_section) (void);
 103
 104     /* Select and switch to a section for EXP.  It may be a DECL or a
 105        constant.  RELOC is nonzero if runtime relocations must be applied;
 106        bit 1 will be set if the runtime relocations require non-local
 107        name resolution.  ALIGN is the required alignment of the data.  */
 108     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 109
 110     /* Select and switch to a section for X with MODE.  ALIGN is
 111        the desired alignment of the data.  */
 112     void (* select_rtx_section) (enum machine_mode, rtx,
 113                                  unsigned HOST_WIDE_INT);
 114
 115     /* Select a unique section name for DECL.  RELOC is the same as
 116        for SELECT_SECTION.  */
 117     void (* unique_section) (tree, int);
 118
 119     /* Output a constructor for a symbol with a given priority.  */
 120     void (* constructor) (rtx, int);
 121
 122     /* Output a destructor for a symbol with a given priority.  */
 123     void (* destructor) (rtx, int);
 124
 125     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 126        declaration for the thunk function itself, FUNCTION is the decl for
 127        the target function.  DELTA is an immediate constant offset to be
 128        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 129        *(*this + vcall_offset) should be added to THIS.  */
 130     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 131                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 132                               tree function_decl);
 133
 134     /* Determine whether output_mi_thunk would succeed.  */
 135     /* ??? Ideally, this hook would not exist, and success or failure
 136        would be returned from output_mi_thunk directly.  But there's
 137        too much undo-able setup involved in invoking output_mi_thunk.
 138        Could be fixed by making output_mi_thunk emit rtl instead of
 139        text to the output file.  */
 140     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 141                                   HOST_WIDE_INT vcall_offset,
 142                                   tree function_decl);
 143
 144     /* Output any boilerplate text needed at the beginning of a
 145        translation unit.  */
 146     void (*file_start) (void);
 147
 148     /* Output any boilerplate text needed at the end of a
 149        translation unit.  */
 150     void (*file_end) (void);
 151
 152     /* Output an assembler pseudo-op to declare a library function name
 153        external.  */
 154     void (*external_libcall) (rtx);
 155   } asm_out;
 156
 157   /* Functions relating to instruction scheduling.  */
 158   struct sched
 159   {
 160     /* Given the current cost, COST, of an insn, INSN, calculate and
 161        return a new cost based on its relationship to DEP_INSN through
 162        the dependence LINK.  The default is to make no adjustment.  */
 163     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 164
 165     /* Adjust the priority of an insn as you see fit.  Returns the new
 166        priority.  */
 167     int (* adjust_priority) (rtx, int);
 168
 169     /* Function which returns the maximum number of insns that can be
 170        scheduled in the same machine cycle.  This must be constant
 171        over an entire compilation.  The default is 1.  */
 172     int (* issue_rate) (void);
 173
 174     /* Calculate how much this insn affects how many more insns we
 175        can emit this cycle.  Default is they all cost the same.  */
 176     int (* variable_issue) (FILE *, int, rtx, int);
 177
 178     /* Initialize machine-dependent scheduling code.  */
 179     void (* md_init) (FILE *, int, int);
 180
 181     /* Finalize machine-dependent scheduling code.  */
 182     void (* md_finish) (FILE *, int);
 183
 184     /* Reorder insns in a machine-dependent fashion, in two different
 185        places.  Default does nothing.  */
 186     int (* reorder) (FILE *, int, rtx *, int *, int);
 187     int (* reorder2) (FILE *, int, rtx *, int *, int);
 188
 189     /* The following member value is a pointer to a function called
 190        after evaluation forward dependencies of insns in chain given
 191        by two parameter values (head and tail correspondingly).  */
 192     void (* dependencies_evaluation_hook) (rtx, rtx);
 193
 194     /* The following member value is a pointer to a function returning
 195        nonzero if we should use DFA based scheduling.  The default is
 196        to use the old pipeline scheduler.  */
 197     int (* use_dfa_pipeline_interface) (void);
 198     /* The values of all the following members are used only for the
 199        DFA based scheduler: */
 200     /* The values of the following four members are pointers to
 201        functions used to simplify the automaton descriptions.
 202        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 203        returning insns which are used to change the pipeline hazard
 204        recognizer state when the new simulated processor cycle
 205        correspondingly starts and finishes.  The function defined by
 206        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 207        to initialize the corresponding insns.  The default values of
 208        the memebers result in not changing the automaton state when
 209        the new simulated processor cycle correspondingly starts and
 210        finishes.  */
 211     void (* init_dfa_pre_cycle_insn) (void);
 212     rtx (* dfa_pre_cycle_insn) (void);
 213     void (* init_dfa_post_cycle_insn) (void);
 214     rtx (* dfa_post_cycle_insn) (void);
 215     /* The following member value is a pointer to a function returning value
 216        which defines how many insns in queue `ready' will we try for
 217        multi-pass scheduling.  if the member value is nonzero and the
 218        function returns positive value, the DFA based scheduler will make
 219        multi-pass scheduling for the first cycle.  In other words, we will
 220        try to choose ready insn which permits to start maximum number of
 221        insns on the same cycle.  */
 222     int (* first_cycle_multipass_dfa_lookahead) (void);
 223     /* The following member value is pointer to a function controlling
 224        what insns from the ready insn queue will be considered for the
 225        multipass insn scheduling.  If the hook returns zero for insn
 226        passed as the parameter, the insn will be not chosen to be
 227        issued.  */
 228     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 229     /* The following member value is pointer to a function called by
 230        the insn scheduler before issuing insn passed as the third
 231        parameter on given cycle.  If the hook returns nonzero, the
 232        insn is not issued on given processors cycle.  Instead of that,
 233        the processor cycle is advanced.  If the value passed through
 234        the last parameter is zero, the insn ready queue is not sorted
 235        on the new cycle start as usually.  The first parameter passes
 236        file for debugging output.  The second one passes the scheduler
 237        verbose level of the debugging output.  The forth and the fifth
 238        parameter values are correspondingly processor cycle on which
 239        the previous insn has been issued and the current processor
 240        cycle.  */
 241     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 242     /* The values of the following members are pointers to functions
 243        used to improve the first cycle multipass scheduling by
 244        inserting nop insns.  dfa_scheduler_bubble gives a function
 245        returning a nop insn with given index.  The indexes start with
 246        zero.  The function should return NULL if there are no more nop
 247        insns with indexes greater than given index.  To initialize the
 248        nop insn the function given by member
 249        init_dfa_scheduler_bubbles is used.  The default values of the
 250        members result in not inserting nop insns during the multipass
 251        scheduling.  */
 252     void (* init_dfa_bubbles) (void);
 253     rtx (* dfa_bubble) (int);
 254     /* The following member value is a pointer to a function called
 255        by the insn scheduler.  It should return true if there exists a
 256        dependence which is considered costly by the target, between
 257        the insn passed as the first parameter, and the insn passed as
 258        the second parameter.  The third parameter is the INSN_DEPEND
 259        link that represents the dependence between the two insns.  The
 260        fourth argument is the cost of the dependence as estimated by
 261        the scheduler.  The last argument is the distance in cycles
 262        between the already scheduled insn (first parameter) and the
 263        the second insn (second parameter).
 264     */
 265     bool (* is_costly_dependence) PARAMS ((rtx, rtx, rtx, int, int));
 266   } sched;
 267
 268   /* Given two decls, merge their attributes and return the result.  */
 269   tree (* merge_decl_attributes) (tree, tree);
 270
 271   /* Given two types, merge their attributes and return the result.  */
 272   tree (* merge_type_attributes) (tree, tree);
 273
 274   /* Table of machine attributes and functions to handle them.
 275      Ignored if NULL.  */
 276   const struct attribute_spec *attribute_table;
 277
 278   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 279      one if they are compatible and two if they are nearly compatible
 280      (which causes a warning to be generated).  */
 281   int (* comp_type_attributes) (tree type1, tree type2);
 282
 283   /* Assign default attributes to the newly defined TYPE.  */
 284   void (* set_default_type_attributes) (tree type);
 285
 286   /* Insert attributes on the newly created DECL.  */
 287   void (* insert_attributes) (tree decl, tree *attributes);
 288
 289   /* Return true if FNDECL (which has at least one machine attribute)
 290      can be inlined despite its machine attributes, false otherwise.  */
 291   bool (* function_attribute_inlinable_p) (tree fndecl);
 292
 293   /* Return true if bitfields in RECORD_TYPE should follow the
 294      Microsoft Visual C++ bitfield layout rules.  */
 295   bool (* ms_bitfield_layout_p) (tree record_type);
 296
 297   /* Set up target-specific built-in functions.  */
 298   void (* init_builtins) (void);
 299
 300   /* Expand a target-specific builtin.  */
 301   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 302                           enum machine_mode mode, int ignore);
 303
 304   /* Make any adjustments to libfunc names needed for this target.  */
 305   void (* init_libfuncs) (void);
 306
 307   /* Given a decl, a section name, and whether the decl initializer
 308      has relocs, choose attributes for the section.  */
 309   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 310   unsigned int (* section_type_flags) (tree, const char *, int);
 311
 312   /* True if new jumps cannot be created, to replace existing ones or
 313      not, at the current point in the compilation.  */
 314   bool (* cannot_modify_jumps_p) (void);
 315
 316   /* Return a register class for which branch target register
 317      optimizations should be applied.  */
 318   int (* branch_target_register_class) (void);
 319
 320   /* Return true if branch target register optimizations should include
 321      callee-saved registers that are not already live during the current
 322      function.  AFTER_PE_GEN is true if prologues and epilogues have
 323      already been generated.  */
 324   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 325
 326   /* True if the constant X cannot be placed in the constant pool.  */
 327   bool (* cannot_force_const_mem) (rtx);
 328
 329   /* True if the insn X cannot be duplicated.  */
 330   bool (* cannot_copy_insn_p) (rtx);
 331
 332   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 333   rtx (* delegitimize_address) (rtx);
 334
 335   /* True if it is OK to do sibling call optimization for the specified
 336      call expression EXP.  DECL will be the called function, or NULL if
 337      this is an indirect call.  */
 338   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 339
 340   /* True if EXP should be placed in a "small data" section.  */
 341   bool (* in_small_data_p) (tree);
 342
 343   /* True if EXP names an object for which name resolution must resolve
 344      to the current module.  */
 345   bool (* binds_local_p) (tree);
 346
 347   /* Do something target-specific to record properties of the DECL into
 348      the associated SYMBOL_REF.  */
 349   void (* encode_section_info) (tree, rtx, int);
 350
 351   /* Undo the effects of encode_section_info on the symbol string.  */
 352   const char * (* strip_name_encoding) (const char *);
 353
 354   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 355   bool (* valid_pointer_mode) (enum machine_mode mode);
 356
 357   /* True if a vector is opaque.  */
 358   bool (* vector_opaque_p) (tree);
 359
 360   /* Compute a (partial) cost for rtx X.  Return true if the complete
 361      cost has been computed, and false if subexpressions should be
 362      scanned.  In either case, *TOTAL contains the cost result.  */
 363   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 364      not necessarily defined at this point.  */
 365   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 366
 367   /* Compute the cost of X, used as an address.  Never called with
 368      invalid addresses.  */
 369   int (* address_cost) (rtx x);
 370
 371   /* Given a register, this hook should return a parallel of registers
 372      to represent where to find the register pieces.  Define this hook
 373      if the register and its mode are represented in Dwarf in
 374      non-contiguous locations, or if the register should be
 375      represented in more than one register in Dwarf.  Otherwise, this
 376      hook should return NULL_RTX.  */
 377   rtx (* dwarf_register_span) (rtx);
 378
 379   /* Do machine-dependent code transformations.  Called just before
 380      delayed-branch scheduling.  */
 381   void (* machine_dependent_reorg) (void);
 382
 383   /* Leave the boolean fields at the end.  */
 384
 385   /* True if arbitrary sections are supported.  */
 386   bool have_named_sections;
 387
 388   /* True if "native" constructors and destructors are supported,
 389      false if we're using collect2 for the job.  */
 390   bool have_ctors_dtors;
 391
 392   /* True if thread-local storage is supported.  */
 393   bool have_tls;
 394
 395   /* True if a small readonly data section is supported.  */
 396   bool have_srodata_section;
 397
 398   /* True if EH frame info sections should be zero-terminated.  */
 399   bool terminate_dw2_eh_frame_info;
 400
 401   /* True if #NO_APP should be emitted at the beginning of
 402      assembly output.  */
 403   bool file_start_app_off;
 404
 405   /* True if output_file_directive should be called for main_input_filename
 406      at the beginning of assembly output.  */
 407   bool file_start_file_directive;
 408
 409   /* Functions relating to calls - argument passing, returns, etc.  */
 410   struct calls {
 411     bool (*promote_function_args) (tree fntype);
 412     bool (*promote_function_return) (tree fntype);
 413     bool (*promote_prototypes) (tree fntype);
 414     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 415     bool (*return_in_memory) (tree type, tree fndecl);
 416     rtx (*expand_builtin_saveregs) (void);
 417     /* Returns pretend_argument_size.  */
 418     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 419                                     tree type, int *pretend_arg_size, int second_time);
 420     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 421     /* Returns true if we should use SETUP_INCOMING_VARARGS and/or
 422        STRICT_ARGUMENT_NAMING.  */
 423     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 424   } calls;
 425 };
 426
 427 extern struct gcc_target targetm;