gcc/target.h

   1 /* Data structure definitions for a generic GCC target.
   2    Copyright (C) 2001, 2002, 2003, 2004 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 #include "tm.h"
  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) (rtx x, unsigned int size, int aligned_p);
  73
  74     /* Output code that will globalize a label.  */
  75     void (* globalize_label) (FILE *, const char *);
  76
  77     /* Output code that will emit a label for unwind info, if this
  78        target requires such labels.  Second argument is the decl the
  79        unwind info is associated with, third is a boolean: true if
  80        this is for exception handling, fourth is a boolean: true if
  81        this is only a placeholder for an omitted FDE. */
  82     void (* unwind_label) (FILE *, tree, int, int);
  83
  84     /* Output an internal label.  */
  85     void (* internal_label) (FILE *, const char *, unsigned long);
  86
  87     /* Emit an assembler directive to set visibility for the symbol
  88        associated with the tree decl.  */
  89     void (* visibility) (tree, int);
  90
  91     /* Output the assembler code for entry to a function.  */
  92     void (* function_prologue) (FILE *, HOST_WIDE_INT);
  93
  94     /* Output the assembler code for end of prologue.  */
  95     void (* function_end_prologue) (FILE *);
  96
  97     /* Output the assembler code for start of epilogue.  */
  98     void (* function_begin_epilogue) (FILE *);
  99
 100     /* Output the assembler code for function exit.  */
 101     void (* function_epilogue) (FILE *, HOST_WIDE_INT);
 102
 103     /* Switch to an arbitrary section NAME with attributes as
 104        specified by FLAGS.  */
 105     void (* named_section) (const char *, unsigned int);
 106
 107     /* Switch to the section that holds the exception table.  */
 108     void (* exception_section) (void);
 109
 110     /* Switch to the section that holds the exception frames.  */
 111     void (* eh_frame_section) (void);
 112
 113     /* Select and switch to a section for EXP.  It may be a DECL or a
 114        constant.  RELOC is nonzero if runtime relocations must be applied;
 115        bit 1 will be set if the runtime relocations require non-local
 116        name resolution.  ALIGN is the required alignment of the data.  */
 117     void (* select_section) (tree, int, unsigned HOST_WIDE_INT);
 118
 119     /* Select and switch to a section for X with MODE.  ALIGN is
 120        the desired alignment of the data.  */
 121     void (* select_rtx_section) (enum machine_mode, rtx,
 122                                  unsigned HOST_WIDE_INT);
 123
 124     /* Select a unique section name for DECL.  RELOC is the same as
 125        for SELECT_SECTION.  */
 126     void (* unique_section) (tree, int);
 127
 128     /* Output a constructor for a symbol with a given priority.  */
 129     void (* constructor) (rtx, int);
 130
 131     /* Output a destructor for a symbol with a given priority.  */
 132     void (* destructor) (rtx, int);
 133
 134     /* Output the assembler code for a thunk function.  THUNK_DECL is the
 135        declaration for the thunk function itself, FUNCTION is the decl for
 136        the target function.  DELTA is an immediate constant offset to be
 137        added to THIS.  If VCALL_OFFSET is nonzero, the word at
 138        *(*this + vcall_offset) should be added to THIS.  */
 139     void (* output_mi_thunk) (FILE *file, tree thunk_decl,
 140                               HOST_WIDE_INT delta, HOST_WIDE_INT vcall_offset,
 141                               tree function_decl);
 142
 143     /* Determine whether output_mi_thunk would succeed.  */
 144     /* ??? Ideally, this hook would not exist, and success or failure
 145        would be returned from output_mi_thunk directly.  But there's
 146        too much undo-able setup involved in invoking output_mi_thunk.
 147        Could be fixed by making output_mi_thunk emit rtl instead of
 148        text to the output file.  */
 149     bool (* can_output_mi_thunk) (tree thunk_decl, HOST_WIDE_INT delta,
 150                                   HOST_WIDE_INT vcall_offset,
 151                                   tree function_decl);
 152
 153     /* Output any boilerplate text needed at the beginning of a
 154        translation unit.  */
 155     void (*file_start) (void);
 156
 157     /* Output any boilerplate text needed at the end of a
 158        translation unit.  */
 159     void (*file_end) (void);
 160
 161     /* Output an assembler pseudo-op to declare a library function name
 162        external.  */
 163     void (*external_libcall) (rtx);
 164   } asm_out;
 165
 166   /* Functions relating to instruction scheduling.  */
 167   struct sched
 168   {
 169     /* Given the current cost, COST, of an insn, INSN, calculate and
 170        return a new cost based on its relationship to DEP_INSN through
 171        the dependence LINK.  The default is to make no adjustment.  */
 172     int (* adjust_cost) (rtx insn, rtx link, rtx def_insn, int cost);
 173
 174     /* Adjust the priority of an insn as you see fit.  Returns the new
 175        priority.  */
 176     int (* adjust_priority) (rtx, int);
 177
 178     /* Function which returns the maximum number of insns that can be
 179        scheduled in the same machine cycle.  This must be constant
 180        over an entire compilation.  The default is 1.  */
 181     int (* issue_rate) (void);
 182
 183     /* Calculate how much this insn affects how many more insns we
 184        can emit this cycle.  Default is they all cost the same.  */
 185     int (* variable_issue) (FILE *, int, rtx, int);
 186
 187     /* Initialize machine-dependent scheduling code.  */
 188     void (* md_init) (FILE *, int, int);
 189
 190     /* Finalize machine-dependent scheduling code.  */
 191     void (* md_finish) (FILE *, int);
 192
 193     /* Initialize machine-dependent function while scheduling code.  */
 194     void (* md_init_global) (FILE *, int, int);
 195
 196     /* Finalize machine-dependent function wide scheduling code.  */
 197     void (* md_finish_global) (FILE *, int);
 198
 199     /* Reorder insns in a machine-dependent fashion, in two different
 200        places.  Default does nothing.  */
 201     int (* reorder) (FILE *, int, rtx *, int *, int);
 202     int (* reorder2) (FILE *, int, rtx *, int *, int);
 203
 204     /* The following member value is a pointer to a function called
 205        after evaluation forward dependencies of insns in chain given
 206        by two parameter values (head and tail correspondingly).  */
 207     void (* dependencies_evaluation_hook) (rtx, rtx);
 208
 209     /* The following member value is a pointer to a function returning
 210        nonzero if we should use DFA based scheduling.  The default is
 211        to use the old pipeline scheduler.  */
 212     int (* use_dfa_pipeline_interface) (void);
 213     /* The values of all the following members are used only for the
 214        DFA based scheduler: */
 215     /* The values of the following four members are pointers to
 216        functions used to simplify the automaton descriptions.
 217        dfa_pre_cycle_insn and dfa_post_cycle_insn give functions
 218        returning insns which are used to change the pipeline hazard
 219        recognizer state when the new simulated processor cycle
 220        correspondingly starts and finishes.  The function defined by
 221        init_dfa_pre_cycle_insn and init_dfa_post_cycle_insn are used
 222        to initialize the corresponding insns.  The default values of
 223        the members result in not changing the automaton state when
 224        the new simulated processor cycle correspondingly starts and
 225        finishes.  */
 226     void (* init_dfa_pre_cycle_insn) (void);
 227     rtx (* dfa_pre_cycle_insn) (void);
 228     void (* init_dfa_post_cycle_insn) (void);
 229     rtx (* dfa_post_cycle_insn) (void);
 230     /* The following member value is a pointer to a function returning value
 231        which defines how many insns in queue `ready' will we try for
 232        multi-pass scheduling.  if the member value is nonzero and the
 233        function returns positive value, the DFA based scheduler will make
 234        multi-pass scheduling for the first cycle.  In other words, we will
 235        try to choose ready insn which permits to start maximum number of
 236        insns on the same cycle.  */
 237     int (* first_cycle_multipass_dfa_lookahead) (void);
 238     /* The following member value is pointer to a function controlling
 239        what insns from the ready insn queue will be considered for the
 240        multipass insn scheduling.  If the hook returns zero for insn
 241        passed as the parameter, the insn will be not chosen to be
 242        issued.  */
 243     int (* first_cycle_multipass_dfa_lookahead_guard) (rtx);
 244     /* The following member value is pointer to a function called by
 245        the insn scheduler before issuing insn passed as the third
 246        parameter on given cycle.  If the hook returns nonzero, the
 247        insn is not issued on given processors cycle.  Instead of that,
 248        the processor cycle is advanced.  If the value passed through
 249        the last parameter is zero, the insn ready queue is not sorted
 250        on the new cycle start as usually.  The first parameter passes
 251        file for debugging output.  The second one passes the scheduler
 252        verbose level of the debugging output.  The forth and the fifth
 253        parameter values are correspondingly processor cycle on which
 254        the previous insn has been issued and the current processor
 255        cycle.  */
 256     int (* dfa_new_cycle) (FILE *, int, rtx, int, int, int *);
 257     /* The values of the following members are pointers to functions
 258        used to improve the first cycle multipass scheduling by
 259        inserting nop insns.  dfa_scheduler_bubble gives a function
 260        returning a nop insn with given index.  The indexes start with
 261        zero.  The function should return NULL if there are no more nop
 262        insns with indexes greater than given index.  To initialize the
 263        nop insn the function given by member
 264        init_dfa_scheduler_bubbles is used.  The default values of the
 265        members result in not inserting nop insns during the multipass
 266        scheduling.  */
 267     void (* init_dfa_bubbles) (void);
 268     rtx (* dfa_bubble) (int);
 269     /* The following member value is a pointer to a function called
 270        by the insn scheduler.  It should return true if there exists a
 271        dependence which is considered costly by the target, between
 272        the insn passed as the first parameter, and the insn passed as
 273        the second parameter.  The third parameter is the INSN_DEPEND
 274        link that represents the dependence between the two insns.  The
 275        fourth argument is the cost of the dependence as estimated by
 276        the scheduler.  The last argument is the distance in cycles
 277        between the already scheduled insn (first parameter) and the
 278        the second insn (second parameter).  */
 279     bool (* is_costly_dependence) (rtx, rtx, rtx, int, int);
 280   } sched;
 281
 282   /* Given two decls, merge their attributes and return the result.  */
 283   tree (* merge_decl_attributes) (tree, tree);
 284
 285   /* Given two types, merge their attributes and return the result.  */
 286   tree (* merge_type_attributes) (tree, tree);
 287
 288   /* Table of machine attributes and functions to handle them.
 289      Ignored if NULL.  */
 290   const struct attribute_spec *attribute_table;
 291
 292   /* Return zero if the attributes on TYPE1 and TYPE2 are incompatible,
 293      one if they are compatible and two if they are nearly compatible
 294      (which causes a warning to be generated).  */
 295   int (* comp_type_attributes) (tree type1, tree type2);
 296
 297   /* Assign default attributes to the newly defined TYPE.  */
 298   void (* set_default_type_attributes) (tree type);
 299
 300   /* Insert attributes on the newly created DECL.  */
 301   void (* insert_attributes) (tree decl, tree *attributes);
 302
 303   /* Return true if FNDECL (which has at least one machine attribute)
 304      can be inlined despite its machine attributes, false otherwise.  */
 305   bool (* function_attribute_inlinable_p) (tree fndecl);
 306
 307   /* Return true if bitfields in RECORD_TYPE should follow the
 308      Microsoft Visual C++ bitfield layout rules.  */
 309   bool (* ms_bitfield_layout_p) (tree record_type);
 310
 311   /* Return true if anonymous bitfields affect structure alignment.  */
 312   bool (* align_anon_bitfield) (void);
 313
 314   /* Set up target-specific built-in functions.  */
 315   void (* init_builtins) (void);
 316
 317   /* Expand a target-specific builtin.  */
 318   rtx (* expand_builtin) (tree exp, rtx target, rtx subtarget,
 319                           enum machine_mode mode, int ignore);
 320
 321   /* For a vendor-specific fundamental TYPE, return a pointer to
 322      a statically-allocated string containing the C++ mangling for
 323      TYPE.  In all other cases, return NULL.  */
 324   const char * (* mangle_fundamental_type) (tree type);
 325
 326   /* Make any adjustments to libfunc names needed for this target.  */
 327   void (* init_libfuncs) (void);
 328
 329   /* Given a decl, a section name, and whether the decl initializer
 330      has relocs, choose attributes for the section.  */
 331   /* ??? Should be merged with SELECT_SECTION and UNIQUE_SECTION.  */
 332   unsigned int (* section_type_flags) (tree, const char *, int);
 333
 334   /* True if new jumps cannot be created, to replace existing ones or
 335      not, at the current point in the compilation.  */
 336   bool (* cannot_modify_jumps_p) (void);
 337
 338   /* Return a register class for which branch target register
 339      optimizations should be applied.  */
 340   int (* branch_target_register_class) (void);
 341
 342   /* Return true if branch target register optimizations should include
 343      callee-saved registers that are not already live during the current
 344      function.  AFTER_PE_GEN is true if prologues and epilogues have
 345      already been generated.  */
 346   bool (* branch_target_register_callee_saved) (bool after_pe_gen);
 347
 348   /* True if the constant X cannot be placed in the constant pool.  */
 349   bool (* cannot_force_const_mem) (rtx);
 350
 351   /* True if the insn X cannot be duplicated.  */
 352   bool (* cannot_copy_insn_p) (rtx);
 353
 354   /* Given an address RTX, undo the effects of LEGITIMIZE_ADDRESS.  */
 355   rtx (* delegitimize_address) (rtx);
 356
 357   /* True if it is OK to do sibling call optimization for the specified
 358      call expression EXP.  DECL will be the called function, or NULL if
 359      this is an indirect call.  */
 360   bool (*function_ok_for_sibcall) (tree decl, tree exp);
 361
 362   /* True if EXP should be placed in a "small data" section.  */
 363   bool (* in_small_data_p) (tree);
 364
 365   /* True if EXP names an object for which name resolution must resolve
 366      to the current module.  */
 367   bool (* binds_local_p) (tree);
 368
 369   /* Do something target-specific to record properties of the DECL into
 370      the associated SYMBOL_REF.  */
 371   void (* encode_section_info) (tree, rtx, int);
 372
 373   /* Undo the effects of encode_section_info on the symbol string.  */
 374   const char * (* strip_name_encoding) (const char *);
 375
 376   /* True if MODE is valid for a pointer in __attribute__((mode("MODE"))).  */
 377   bool (* valid_pointer_mode) (enum machine_mode mode);
 378
 379   /* True if a vector is opaque.  */
 380   bool (* vector_opaque_p) (tree);
 381
 382   /* Compute a (partial) cost for rtx X.  Return true if the complete
 383      cost has been computed, and false if subexpressions should be
 384      scanned.  In either case, *TOTAL contains the cost result.  */
 385   /* Note that CODE and OUTER_CODE ought to be RTX_CODE, but that's
 386      not necessarily defined at this point.  */
 387   bool (* rtx_costs) (rtx x, int code, int outer_code, int *total);
 388
 389   /* Compute the cost of X, used as an address.  Never called with
 390      invalid addresses.  */
 391   int (* address_cost) (rtx x);
 392
 393   /* Given a register, this hook should return a parallel of registers
 394      to represent where to find the register pieces.  Define this hook
 395      if the register and its mode are represented in Dwarf in
 396      non-contiguous locations, or if the register should be
 397      represented in more than one register in Dwarf.  Otherwise, this
 398      hook should return NULL_RTX.  */
 399   rtx (* dwarf_register_span) (rtx);
 400
 401   /* Fetch the fixed register(s) which hold condition codes, for
 402      targets where it makes sense to look for duplicate assignments to
 403      the condition codes.  This should return true if there is such a
 404      register, false otherwise.  The arguments should be set to the
 405      fixed register numbers.  Up to two condition code registers are
 406      supported.  If there is only one for this target, the int pointed
 407      at by the second argument should be set to -1.  */
 408   bool (* fixed_condition_code_regs) (unsigned int *, unsigned int *);
 409
 410   /* If two condition code modes are compatible, return a condition
 411      code mode which is compatible with both, such that a comparison
 412      done in the returned mode will work for both of the original
 413      modes.  If the condition code modes are not compatible, return
 414      VOIDmode.  */
 415   enum machine_mode (* cc_modes_compatible) (enum machine_mode,
 416                                              enum machine_mode);
 417
 418   /* Do machine-dependent code transformations.  Called just before
 419      delayed-branch scheduling.  */
 420   void (* machine_dependent_reorg) (void);
 421
 422   /* Create the __builtin_va_list type.  */
 423   tree (* build_builtin_va_list) (void);
 424
 425   /* Validity-checking routines for PCH files, target-specific.
 426      get_pch_validity returns a pointer to the data to be stored,
 427      and stores the size in its argument.  pch_valid_p gets the same
 428      information back and returns NULL if the PCH is valid,
 429      or an error message if not.
 430   */
 431   void * (* get_pch_validity) (size_t *);
 432   const char * (* pch_valid_p) (const void *, size_t);
 433
 434   /* True if the compiler should give an enum type only as many
 435      bytes as it takes to represent the range of possible values of
 436      that type.  */
 437   bool (* default_short_enums) (void);
 438
 439   /* This target hook returns an rtx that is used to store the address
 440      of the current frame into the built-in setjmp buffer.  */
 441   rtx (* builtin_setjmp_frame_value) (void);
 442
 443   /* This target hook should add STRING_CST trees for any hard regs
 444      the port wishes to automatically clobber for all asms.  */
 445   tree (* md_asm_clobbers) (tree);
 446
 447   /* Functions relating to calls - argument passing, returns, etc.  */
 448   struct calls {
 449     bool (*promote_function_args) (tree fntype);
 450     bool (*promote_function_return) (tree fntype);
 451     bool (*promote_prototypes) (tree fntype);
 452     rtx (*struct_value_rtx) (tree fndecl, int incoming);
 453     bool (*return_in_memory) (tree type, tree fndecl);
 454     bool (*return_in_msb) (tree type);
 455     rtx (*expand_builtin_saveregs) (void);
 456     /* Returns pretend_argument_size.  */
 457     void (*setup_incoming_varargs) (CUMULATIVE_ARGS *ca, enum machine_mode mode,
 458                                     tree type, int *pretend_arg_size,
 459                                     int second_time);
 460     bool (*strict_argument_naming) (CUMULATIVE_ARGS *ca);
 461     /* Returns true if we should use
 462        targetm.calls.setup_incoming_varargs() and/or
 463        targetm.calls.strict_argument_naming().  */
 464     bool (*pretend_outgoing_varargs_named) (CUMULATIVE_ARGS *ca);
 465
 466     /* Given a complex type T, return true if a parameter of type T
 467        should be passed as two scalars.  */
 468     bool (* split_complex_arg) (tree type);
 469   } calls;
 470
 471   /* Leave the boolean fields at the end.  */
 472
 473   /* True if arbitrary sections are supported.  */
 474   bool have_named_sections;
 475
 476   /* True if "native" constructors and destructors are supported,
 477      false if we're using collect2 for the job.  */
 478   bool have_ctors_dtors;
 479
 480   /* True if thread-local storage is supported.  */
 481   bool have_tls;
 482
 483   /* True if a small readonly data section is supported.  */
 484   bool have_srodata_section;
 485
 486   /* True if EH frame info sections should be zero-terminated.  */
 487   bool terminate_dw2_eh_frame_info;
 488
 489   /* True if #NO_APP should be emitted at the beginning of
 490      assembly output.  */
 491   bool file_start_app_off;
 492
 493   /* True if output_file_directive should be called for main_input_filename
 494      at the beginning of assembly output.  */
 495   bool file_start_file_directive;
 496
 497   /* Leave the boolean fields at the end.  */
 498 };
 499
 500 extern struct gcc_target targetm;