gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004, 2005, 2007, 2008, 2009
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 /* The migration of target macros to target hooks works as follows:
  22
  23    1. Create a target hook that uses the existing target macros to
  24       implement the same functionality.
  25
  26    2. Convert all the MI files to use the hook instead of the macro.
  27
  28    3. Repeat for a majority of the remaining target macros.  This will
  29       take some time.
  30
  31    4. Tell target maintainers to start migrating.
  32
  33    5. Eventually convert the backends to override the hook instead of
  34       defining the macros.  This will take some time too.
  35
  36    6. TBD when, poison the macros.  Unmigrated targets will break at
  37       this point.
  38
  39    Note that we expect steps 1-3 to be done by the people that
  40    understand what the MI does with each macro, and step 5 to be done
  41    by the target maintainers for their respective targets.
  42
  43    Note that steps 1 and 2 don't have to be done together, but no
  44    target can override the new hook until step 2 is complete for it.
  45
  46    Once the macros are poisoned, we will revert to the old migration
  47    rules - migrate the macro, callers, and targets all at once.  This
  48    comment can thus be removed at that point.  */
  49
  50 #include "config.h"
  51 #include "system.h"
  52 #include "coretypes.h"
  53 #include "tm.h"
  54 #include "machmode.h"
  55 #include "rtl.h"
  56 #include "tree.h"
  57 #include "expr.h"
  58 #include "output.h"
  59 #include "toplev.h"
  60 #include "function.h"
  61 #include "target.h"
  62 #include "tm_p.h"
  63 #include "target-def.h"
  64 #include "ggc.h"
  65 #include "hard-reg-set.h"
  66 #include "reload.h"
  67 #include "optabs.h"
  68 #include "recog.h"
  69
  70
  71 void
  72 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  73 {
  74 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  75   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  76 #endif
  77 }
  78
  79 int
  80 default_unspec_may_trap_p (const_rtx x, unsigned flags)
  81 {
  82   int i;
  83
  84   if (GET_CODE (x) == UNSPEC_VOLATILE
  85       /* Any floating arithmetic may trap.  */
  86       || (SCALAR_FLOAT_MODE_P (GET_MODE (x))
  87           && flag_trapping_math))
  88     return 1;
  89
  90   for (i = 0; i < XVECLEN (x, 0); ++i)
  91     {
  92       if (may_trap_p_1 (XVECEXP (x, 0, i), flags))
  93         return 1;
  94     }
  95
  96   return 0;
  97 }
  98
  99 enum machine_mode
 100 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
 101 {
 102   if (m1 == m2)
 103     return m1;
 104   return VOIDmode;
 105 }
 106
 107 bool
 108 default_return_in_memory (const_tree type,
 109                           const_tree fntype ATTRIBUTE_UNUSED)
 110 {
 111   return (TYPE_MODE (type) == BLKmode);
 112 }
 113
 114 rtx
 115 default_legitimize_address (rtx x, rtx orig_x ATTRIBUTE_UNUSED,
 116                             enum machine_mode mode ATTRIBUTE_UNUSED)
 117 {
 118   return x;
 119 }
 120
 121 rtx
 122 default_expand_builtin_saveregs (void)
 123 {
 124   error ("__builtin_saveregs not supported by this target");
 125   return const0_rtx;
 126 }
 127
 128 void
 129 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 130                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 131                                 tree type ATTRIBUTE_UNUSED,
 132                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 133                                 int second_time ATTRIBUTE_UNUSED)
 134 {
 135 }
 136
 137 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 138
 139 rtx
 140 default_builtin_setjmp_frame_value (void)
 141 {
 142   return virtual_stack_vars_rtx;
 143 }
 144
 145 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 146
 147 bool
 148 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 149 {
 150   return false;
 151 }
 152
 153 bool
 154 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 155 {
 156   return (targetm.calls.setup_incoming_varargs
 157           != default_setup_incoming_varargs);
 158 }
 159
 160 enum machine_mode
 161 default_eh_return_filter_mode (void)
 162 {
 163   return targetm.unwind_word_mode ();
 164 }
 165
 166 enum machine_mode
 167 default_libgcc_cmp_return_mode (void)
 168 {
 169   return word_mode;
 170 }
 171
 172 enum machine_mode
 173 default_libgcc_shift_count_mode (void)
 174 {
 175   return word_mode;
 176 }
 177
 178 enum machine_mode
 179 default_unwind_word_mode (void)
 180 {
 181   return word_mode;
 182 }
 183
 184 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 185
 186 unsigned HOST_WIDE_INT
 187 default_shift_truncation_mask (enum machine_mode mode)
 188 {
 189   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 190 }
 191
 192 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 193
 194 unsigned int
 195 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 196 {
 197   return have_insn_for (DIV, mode) ? 3 : 2;
 198 }
 199
 200 /* The default implementation of TARGET_MODE_REP_EXTENDED.  */
 201
 202 int
 203 default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED,
 204                            enum machine_mode mode_rep ATTRIBUTE_UNUSED)
 205 {
 206   return UNKNOWN;
 207 }
 208
 209 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 210
 211 bool
 212 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 213 {
 214   return true;
 215 }
 216
 217 /* Return machine mode for non-standard suffix
 218    or VOIDmode if non-standard suffixes are unsupported.  */
 219 enum machine_mode
 220 default_mode_for_suffix (char suffix ATTRIBUTE_UNUSED)
 221 {
 222   return VOIDmode;
 223 }
 224
 225 /* The generic C++ ABI specifies this is a 64-bit value.  */
 226 tree
 227 default_cxx_guard_type (void)
 228 {
 229   return long_long_integer_type_node;
 230 }
 231
 232
 233 /* Returns the size of the cookie to use when allocating an array
 234    whose elements have the indicated TYPE.  Assumes that it is already
 235    known that a cookie is needed.  */
 236
 237 tree
 238 default_cxx_get_cookie_size (tree type)
 239 {
 240   tree cookie_size;
 241
 242   /* We need to allocate an additional max (sizeof (size_t), alignof
 243      (true_type)) bytes.  */
 244   tree sizetype_size;
 245   tree type_align;
 246
 247   sizetype_size = size_in_bytes (sizetype);
 248   type_align = size_int (TYPE_ALIGN_UNIT (type));
 249   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 250     cookie_size = sizetype_size;
 251   else
 252     cookie_size = type_align;
 253
 254   return cookie_size;
 255 }
 256
 257 /* Return true if a parameter must be passed by reference.  This version
 258    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 259
 260 bool
 261 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 262         enum machine_mode mode ATTRIBUTE_UNUSED, const_tree type ATTRIBUTE_UNUSED,
 263         bool named_arg ATTRIBUTE_UNUSED)
 264 {
 265   return targetm.calls.must_pass_in_stack (mode, type);
 266 }
 267
 268 /* Return true if a parameter follows callee copies conventions.  This
 269    version of the hook is true for all named arguments.  */
 270
 271 bool
 272 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 273                           enum machine_mode mode ATTRIBUTE_UNUSED,
 274                           const_tree type ATTRIBUTE_UNUSED, bool named)
 275 {
 276   return named;
 277 }
 278
 279 /* Emit any directives required to unwind this instruction.  */
 280
 281 void
 282 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 283                      rtx insn ATTRIBUTE_UNUSED)
 284 {
 285   /* Should never happen.  */
 286   gcc_unreachable ();
 287 }
 288
 289 /* True if MODE is valid for the target.  By "valid", we mean able to
 290    be manipulated in non-trivial ways.  In particular, this means all
 291    the arithmetic is supported.
 292
 293    By default we guess this means that any C type is supported.  If
 294    we can't map the mode back to a type that would be available in C,
 295    then reject it.  Special case, here, is the double-word arithmetic
 296    supported by optabs.c.  */
 297
 298 bool
 299 default_scalar_mode_supported_p (enum machine_mode mode)
 300 {
 301   int precision = GET_MODE_PRECISION (mode);
 302
 303   switch (GET_MODE_CLASS (mode))
 304     {
 305     case MODE_PARTIAL_INT:
 306     case MODE_INT:
 307       if (precision == CHAR_TYPE_SIZE)
 308         return true;
 309       if (precision == SHORT_TYPE_SIZE)
 310         return true;
 311       if (precision == INT_TYPE_SIZE)
 312         return true;
 313       if (precision == LONG_TYPE_SIZE)
 314         return true;
 315       if (precision == LONG_LONG_TYPE_SIZE)
 316         return true;
 317       if (precision == 2 * BITS_PER_WORD)
 318         return true;
 319       return false;
 320
 321     case MODE_FLOAT:
 322       if (precision == FLOAT_TYPE_SIZE)
 323         return true;
 324       if (precision == DOUBLE_TYPE_SIZE)
 325         return true;
 326       if (precision == LONG_DOUBLE_TYPE_SIZE)
 327         return true;
 328       return false;
 329
 330     case MODE_DECIMAL_FLOAT:
 331     case MODE_FRACT:
 332     case MODE_UFRACT:
 333     case MODE_ACCUM:
 334     case MODE_UACCUM:
 335       return false;
 336
 337     default:
 338       gcc_unreachable ();
 339     }
 340 }
 341
 342 /* True if the target supports decimal floating point.  */
 343
 344 bool
 345 default_decimal_float_supported_p (void)
 346 {
 347   return ENABLE_DECIMAL_FLOAT;
 348 }
 349
 350 /* True if the target supports fixed-point arithmetic.  */
 351
 352 bool
 353 default_fixed_point_supported_p (void)
 354 {
 355   return ENABLE_FIXED_POINT;
 356 }
 357
 358 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 359    an error message.
 360
 361    This function checks whether a given INSN is valid within a low-overhead
 362    loop.  If INSN is invalid it returns the reason for that, otherwise it
 363    returns NULL. A called function may clobber any special registers required
 364    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 365    register for branch on table instructions. We reject the doloop pattern in
 366    these cases.  */
 367
 368 const char *
 369 default_invalid_within_doloop (const_rtx insn)
 370 {
 371   if (CALL_P (insn))
 372     return "Function call in loop.";
 373
 374   if (JUMP_P (insn)
 375       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 376           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 377     return "Computed branch in the loop.";
 378
 379   return NULL;
 380 }
 381
 382 /* Mapping of builtin functions to vectorized variants.  */
 383
 384 tree
 385 default_builtin_vectorized_function (enum built_in_function fn ATTRIBUTE_UNUSED,
 386                                      tree type_out ATTRIBUTE_UNUSED,
 387                                      tree type_in ATTRIBUTE_UNUSED)
 388 {
 389   return NULL_TREE;
 390 }
 391
 392 /* Vectorized conversion.  */
 393
 394 tree
 395 default_builtin_vectorized_conversion (enum tree_code code ATTRIBUTE_UNUSED,
 396                                        tree type ATTRIBUTE_UNUSED)
 397 {
 398   return NULL_TREE;
 399 }
 400
 401 /* Reciprocal.  */
 402
 403 tree
 404 default_builtin_reciprocal (enum built_in_function fn ATTRIBUTE_UNUSED,
 405                             bool md_fn ATTRIBUTE_UNUSED,
 406                             bool sqrt ATTRIBUTE_UNUSED)
 407 {
 408   return NULL_TREE;
 409 }
 410
 411 bool
 412 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 413         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 414         enum machine_mode mode ATTRIBUTE_UNUSED,
 415         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 416 {
 417   return false;
 418 }
 419
 420 bool
 421 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 422         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 423         enum machine_mode mode ATTRIBUTE_UNUSED,
 424         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 425 {
 426   return true;
 427 }
 428
 429 int
 430 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 431         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 432         enum machine_mode mode ATTRIBUTE_UNUSED,
 433         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 434 {
 435   return 0;
 436 }
 437
 438 void
 439 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 440 {
 441 }
 442
 443 const char *
 444 hook_invalid_arg_for_unprototyped_fn (
 445         const_tree typelist ATTRIBUTE_UNUSED,
 446         const_tree funcdecl ATTRIBUTE_UNUSED,
 447         const_tree val ATTRIBUTE_UNUSED)
 448 {
 449   return NULL;
 450 }
 451
 452 /* Initialize the stack protection decls.  */
 453
 454 /* Stack protection related decls living in libgcc.  */
 455 static GTY(()) tree stack_chk_guard_decl;
 456
 457 tree
 458 default_stack_protect_guard (void)
 459 {
 460   tree t = stack_chk_guard_decl;
 461
 462   if (t == NULL)
 463     {
 464       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 465                       ptr_type_node);
 466       TREE_STATIC (t) = 1;
 467       TREE_PUBLIC (t) = 1;
 468       DECL_EXTERNAL (t) = 1;
 469       TREE_USED (t) = 1;
 470       TREE_THIS_VOLATILE (t) = 1;
 471       DECL_ARTIFICIAL (t) = 1;
 472       DECL_IGNORED_P (t) = 1;
 473
 474       stack_chk_guard_decl = t;
 475     }
 476
 477   return t;
 478 }
 479
 480 static GTY(()) tree stack_chk_fail_decl;
 481
 482 tree
 483 default_external_stack_protect_fail (void)
 484 {
 485   tree t = stack_chk_fail_decl;
 486
 487   if (t == NULL_TREE)
 488     {
 489       t = build_function_type_list (void_type_node, NULL_TREE);
 490       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 491       TREE_STATIC (t) = 1;
 492       TREE_PUBLIC (t) = 1;
 493       DECL_EXTERNAL (t) = 1;
 494       TREE_USED (t) = 1;
 495       TREE_THIS_VOLATILE (t) = 1;
 496       TREE_NOTHROW (t) = 1;
 497       DECL_ARTIFICIAL (t) = 1;
 498       DECL_IGNORED_P (t) = 1;
 499       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 500       DECL_VISIBILITY_SPECIFIED (t) = 1;
 501
 502       stack_chk_fail_decl = t;
 503     }
 504
 505   return build_call_expr (t, 0);
 506 }
 507
 508 tree
 509 default_hidden_stack_protect_fail (void)
 510 {
 511 #ifndef HAVE_GAS_HIDDEN
 512   return default_external_stack_protect_fail ();
 513 #else
 514   tree t = stack_chk_fail_decl;
 515
 516   if (!flag_pic)
 517     return default_external_stack_protect_fail ();
 518
 519   if (t == NULL_TREE)
 520     {
 521       t = build_function_type_list (void_type_node, NULL_TREE);
 522       t = build_decl (FUNCTION_DECL,
 523                       get_identifier ("__stack_chk_fail_local"), t);
 524       TREE_STATIC (t) = 1;
 525       TREE_PUBLIC (t) = 1;
 526       DECL_EXTERNAL (t) = 1;
 527       TREE_USED (t) = 1;
 528       TREE_THIS_VOLATILE (t) = 1;
 529       TREE_NOTHROW (t) = 1;
 530       DECL_ARTIFICIAL (t) = 1;
 531       DECL_IGNORED_P (t) = 1;
 532       DECL_VISIBILITY_SPECIFIED (t) = 1;
 533       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 534
 535       stack_chk_fail_decl = t;
 536     }
 537
 538   return build_call_expr (t, 0);
 539 #endif
 540 }
 541
 542 bool
 543 hook_bool_const_rtx_commutative_p (const_rtx x,
 544                                    int outer_code ATTRIBUTE_UNUSED)
 545 {
 546   return COMMUTATIVE_P (x);
 547 }
 548
 549 rtx
 550 default_function_value (const_tree ret_type ATTRIBUTE_UNUSED,
 551                         const_tree fn_decl_or_type,
 552                         bool outgoing ATTRIBUTE_UNUSED)
 553 {
 554   /* The old interface doesn't handle receiving the function type.  */
 555   if (fn_decl_or_type
 556       && !DECL_P (fn_decl_or_type))
 557     fn_decl_or_type = NULL;
 558
 559 #ifdef FUNCTION_OUTGOING_VALUE
 560   if (outgoing)
 561     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 562 #endif
 563
 564 #ifdef FUNCTION_VALUE
 565   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 566 #else
 567   return NULL_RTX;
 568 #endif
 569 }
 570
 571 rtx
 572 default_internal_arg_pointer (void)
 573 {
 574   /* If the reg that the virtual arg pointer will be translated into is
 575      not a fixed reg or is the stack pointer, make a copy of the virtual
 576      arg pointer, and address parms via the copy.  The frame pointer is
 577      considered fixed even though it is not marked as such.  */
 578   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 579        || ! (fixed_regs[ARG_POINTER_REGNUM]
 580              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 581     return copy_to_reg (virtual_incoming_args_rtx);
 582   else
 583     return virtual_incoming_args_rtx;
 584 }
 585
 586 enum reg_class
 587 default_branch_target_register_class (void)
 588 {
 589   return NO_REGS;
 590 }
 591
 592 #ifdef IRA_COVER_CLASSES
 593 const enum reg_class *
 594 default_ira_cover_classes (void)
 595 {
 596   static enum reg_class classes[] = IRA_COVER_CLASSES;
 597   return classes;
 598 }
 599 #endif
 600
 601 enum reg_class
 602 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 603                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 604                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 605                           secondary_reload_info *sri)
 606 {
 607   enum reg_class rclass = NO_REGS;
 608
 609   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 610     {
 611       sri->icode = sri->prev_sri->t_icode;
 612       return NO_REGS;
 613     }
 614 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 615   if (in_p)
 616     rclass = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 617 #endif
 618 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 619   if (! in_p)
 620     rclass = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 621 #endif
 622   if (rclass != NO_REGS)
 623     {
 624       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 625                               : reload_out_optab[(int) reload_mode]);
 626
 627       if (icode != CODE_FOR_nothing
 628           && insn_data[(int) icode].operand[in_p].predicate
 629           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 630         icode = CODE_FOR_nothing;
 631       else if (icode != CODE_FOR_nothing)
 632         {
 633           const char *insn_constraint, *scratch_constraint;
 634           char insn_letter, scratch_letter;
 635           enum reg_class insn_class, scratch_class;
 636
 637           gcc_assert (insn_data[(int) icode].n_operands == 3);
 638           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 639           if (!*insn_constraint)
 640             insn_class = ALL_REGS;
 641           else
 642             {
 643               if (in_p)
 644                 {
 645                   gcc_assert (*insn_constraint == '=');
 646                   insn_constraint++;
 647                 }
 648               insn_letter = *insn_constraint;
 649               insn_class
 650                 = (insn_letter == 'r' ? GENERAL_REGS
 651                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 652                                                 insn_constraint));
 653               gcc_assert (insn_class != NO_REGS);
 654             }
 655
 656           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 657           /* The scratch register's constraint must start with "=&",
 658              except for an input reload, where only "=" is necessary,
 659              and where it might be beneficial to re-use registers from
 660              the input.  */
 661           gcc_assert (scratch_constraint[0] == '='
 662                       && (in_p || scratch_constraint[1] == '&'));
 663           scratch_constraint++;
 664           if (*scratch_constraint == '&')
 665             scratch_constraint++;
 666           scratch_letter = *scratch_constraint;
 667           scratch_class
 668             = (scratch_letter == 'r' ? GENERAL_REGS
 669                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 670                                             scratch_constraint));
 671
 672           if (reg_class_subset_p (reload_class, insn_class))
 673             {
 674               gcc_assert (scratch_class == rclass);
 675               rclass = NO_REGS;
 676             }
 677           else
 678             rclass = insn_class;
 679
 680         }
 681       if (rclass == NO_REGS)
 682         sri->icode = icode;
 683       else
 684         sri->t_icode = icode;
 685     }
 686   return rclass;
 687 }
 688
 689 bool
 690 default_handle_c_option (size_t code ATTRIBUTE_UNUSED,
 691                          const char *arg ATTRIBUTE_UNUSED,
 692                          int value ATTRIBUTE_UNUSED)
 693 {
 694   return false;
 695 }
 696
 697 /* By default, if flag_pic is true, then neither local nor global relocs
 698    should be placed in readonly memory.  */
 699
 700 int
 701 default_reloc_rw_mask (void)
 702 {
 703   return flag_pic ? 3 : 0;
 704 }
 705
 706 /* By default, do no modification. */
 707 tree default_mangle_decl_assembler_name (tree decl ATTRIBUTE_UNUSED,
 708                                          tree id)
 709 {
 710    return id;
 711 }
 712
 713 bool
 714 default_builtin_vector_alignment_reachable (const_tree type, bool is_packed)
 715 {
 716   if (is_packed)
 717     return false;
 718
 719   /* Assuming that types whose size is > pointer-size are not guaranteed to be
 720      naturally aligned.  */
 721   if (tree_int_cst_compare (TYPE_SIZE (type), bitsize_int (POINTER_SIZE)) > 0)
 722     return false;
 723
 724   /* Assuming that types whose size is <= pointer-size
 725      are naturally aligned.  */
 726   return true;
 727 }
 728
 729 bool
 730 default_hard_regno_scratch_ok (unsigned int regno ATTRIBUTE_UNUSED)
 731 {
 732   return true;
 733 }
 734
 735 bool
 736 default_target_option_valid_attribute_p (tree ARG_UNUSED (fndecl),
 737                                          tree ARG_UNUSED (name),
 738                                          tree ARG_UNUSED (args),
 739                                          int ARG_UNUSED (flags))
 740 {
 741   warning (OPT_Wattributes,
 742            "target attribute is not supported on this machine");
 743
 744   return false;
 745 }
 746
 747 bool
 748 default_target_option_pragma_parse (tree ARG_UNUSED (args),
 749                                     tree ARG_UNUSED (pop_target))
 750 {
 751   warning (OPT_Wpragmas,
 752            "#pragma GCC target is not supported for this machine");
 753
 754   return false;
 755 }
 756
 757 bool
 758 default_target_option_can_inline_p (tree caller, tree callee)
 759 {
 760   bool ret = false;
 761   tree callee_opts = DECL_FUNCTION_SPECIFIC_TARGET (callee);
 762   tree caller_opts = DECL_FUNCTION_SPECIFIC_TARGET (caller);
 763
 764   /* If callee has no option attributes, then it is ok to inline */
 765   if (!callee_opts)
 766     ret = true;
 767
 768   /* If caller has no option attributes, but callee does then it is not ok to
 769      inline */
 770   else if (!caller_opts)
 771     ret = false;
 772
 773   /* If both caller and callee have attributes, assume that if the pointer is
 774      different, the the two functions have different target options since
 775      build_target_option_node uses a hash table for the options.  */
 776   else
 777     ret = (callee_opts == caller_opts);
 778
 779   return ret;
 780 }
 781
 782 #ifndef HAVE_casesi
 783 # define HAVE_casesi 0
 784 #endif
 785
 786 /* If the machine does not have a case insn that compares the bounds,
 787    this means extra overhead for dispatch tables, which raises the
 788    threshold for using them.  */
 789
 790 unsigned int default_case_values_threshold (void)
 791 {
 792   return (HAVE_casesi ? 4 : 5);
 793 }
 794
 795 #include "gt-targhooks.h"