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 bool
  72 default_legitimate_address_p (enum machine_mode mode ATTRIBUTE_UNUSED,
  73                               rtx addr ATTRIBUTE_UNUSED,
  74                               bool strict ATTRIBUTE_UNUSED)
  75 {
  76 #ifdef GO_IF_LEGITIMATE_ADDRESS
  77   /* Defer to the old implementation using a goto.  */
  78   if (strict)
  79     return strict_memory_address_p (mode, addr);
  80   else
  81     return memory_address_p (mode, addr);
  82 #else
  83   gcc_unreachable ();
  84 #endif
  85 }
  86
  87 void
  88 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  89 {
  90 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  91   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  92 #endif
  93 }
  94
  95 int
  96 default_unspec_may_trap_p (const_rtx x, unsigned flags)
  97 {
  98   int i;
  99
 100   if (GET_CODE (x) == UNSPEC_VOLATILE
 101       /* Any floating arithmetic may trap.  */
 102       || (SCALAR_FLOAT_MODE_P (GET_MODE (x))
 103           && flag_trapping_math))
 104     return 1;
 105
 106   for (i = 0; i < XVECLEN (x, 0); ++i)
 107     {
 108       if (may_trap_p_1 (XVECEXP (x, 0, i), flags))
 109         return 1;
 110     }
 111
 112   return 0;
 113 }
 114
 115 enum machine_mode
 116 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
 117 {
 118   if (m1 == m2)
 119     return m1;
 120   return VOIDmode;
 121 }
 122
 123 bool
 124 default_return_in_memory (const_tree type,
 125                           const_tree fntype ATTRIBUTE_UNUSED)
 126 {
 127   return (TYPE_MODE (type) == BLKmode);
 128 }
 129
 130 rtx
 131 default_legitimize_address (rtx x, rtx orig_x ATTRIBUTE_UNUSED,
 132                             enum machine_mode mode ATTRIBUTE_UNUSED)
 133 {
 134   return x;
 135 }
 136
 137 rtx
 138 default_expand_builtin_saveregs (void)
 139 {
 140   error ("__builtin_saveregs not supported by this target");
 141   return const0_rtx;
 142 }
 143
 144 void
 145 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 146                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 147                                 tree type ATTRIBUTE_UNUSED,
 148                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 149                                 int second_time ATTRIBUTE_UNUSED)
 150 {
 151 }
 152
 153 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 154
 155 rtx
 156 default_builtin_setjmp_frame_value (void)
 157 {
 158   return virtual_stack_vars_rtx;
 159 }
 160
 161 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 162
 163 bool
 164 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 165 {
 166   return false;
 167 }
 168
 169 bool
 170 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 171 {
 172   return (targetm.calls.setup_incoming_varargs
 173           != default_setup_incoming_varargs);
 174 }
 175
 176 enum machine_mode
 177 default_eh_return_filter_mode (void)
 178 {
 179   return targetm.unwind_word_mode ();
 180 }
 181
 182 enum machine_mode
 183 default_libgcc_cmp_return_mode (void)
 184 {
 185   return word_mode;
 186 }
 187
 188 enum machine_mode
 189 default_libgcc_shift_count_mode (void)
 190 {
 191   return word_mode;
 192 }
 193
 194 enum machine_mode
 195 default_unwind_word_mode (void)
 196 {
 197   return word_mode;
 198 }
 199
 200 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 201
 202 unsigned HOST_WIDE_INT
 203 default_shift_truncation_mask (enum machine_mode mode)
 204 {
 205   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 206 }
 207
 208 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 209
 210 unsigned int
 211 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 212 {
 213   return have_insn_for (DIV, mode) ? 3 : 2;
 214 }
 215
 216 /* The default implementation of TARGET_MODE_REP_EXTENDED.  */
 217
 218 int
 219 default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED,
 220                            enum machine_mode mode_rep ATTRIBUTE_UNUSED)
 221 {
 222   return UNKNOWN;
 223 }
 224
 225 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 226
 227 bool
 228 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 229 {
 230   return true;
 231 }
 232
 233 /* Return machine mode for non-standard suffix
 234    or VOIDmode if non-standard suffixes are unsupported.  */
 235 enum machine_mode
 236 default_mode_for_suffix (char suffix ATTRIBUTE_UNUSED)
 237 {
 238   return VOIDmode;
 239 }
 240
 241 /* The generic C++ ABI specifies this is a 64-bit value.  */
 242 tree
 243 default_cxx_guard_type (void)
 244 {
 245   return long_long_integer_type_node;
 246 }
 247
 248
 249 /* Returns the size of the cookie to use when allocating an array
 250    whose elements have the indicated TYPE.  Assumes that it is already
 251    known that a cookie is needed.  */
 252
 253 tree
 254 default_cxx_get_cookie_size (tree type)
 255 {
 256   tree cookie_size;
 257
 258   /* We need to allocate an additional max (sizeof (size_t), alignof
 259      (true_type)) bytes.  */
 260   tree sizetype_size;
 261   tree type_align;
 262
 263   sizetype_size = size_in_bytes (sizetype);
 264   type_align = size_int (TYPE_ALIGN_UNIT (type));
 265   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 266     cookie_size = sizetype_size;
 267   else
 268     cookie_size = type_align;
 269
 270   return cookie_size;
 271 }
 272
 273 /* Return true if a parameter must be passed by reference.  This version
 274    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 275
 276 bool
 277 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 278         enum machine_mode mode ATTRIBUTE_UNUSED, const_tree type ATTRIBUTE_UNUSED,
 279         bool named_arg ATTRIBUTE_UNUSED)
 280 {
 281   return targetm.calls.must_pass_in_stack (mode, type);
 282 }
 283
 284 /* Return true if a parameter follows callee copies conventions.  This
 285    version of the hook is true for all named arguments.  */
 286
 287 bool
 288 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 289                           enum machine_mode mode ATTRIBUTE_UNUSED,
 290                           const_tree type ATTRIBUTE_UNUSED, bool named)
 291 {
 292   return named;
 293 }
 294
 295 /* Emit any directives required to unwind this instruction.  */
 296
 297 void
 298 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 299                      rtx insn ATTRIBUTE_UNUSED)
 300 {
 301   /* Should never happen.  */
 302   gcc_unreachable ();
 303 }
 304
 305 /* True if MODE is valid for the target.  By "valid", we mean able to
 306    be manipulated in non-trivial ways.  In particular, this means all
 307    the arithmetic is supported.
 308
 309    By default we guess this means that any C type is supported.  If
 310    we can't map the mode back to a type that would be available in C,
 311    then reject it.  Special case, here, is the double-word arithmetic
 312    supported by optabs.c.  */
 313
 314 bool
 315 default_scalar_mode_supported_p (enum machine_mode mode)
 316 {
 317   int precision = GET_MODE_PRECISION (mode);
 318
 319   switch (GET_MODE_CLASS (mode))
 320     {
 321     case MODE_PARTIAL_INT:
 322     case MODE_INT:
 323       if (precision == CHAR_TYPE_SIZE)
 324         return true;
 325       if (precision == SHORT_TYPE_SIZE)
 326         return true;
 327       if (precision == INT_TYPE_SIZE)
 328         return true;
 329       if (precision == LONG_TYPE_SIZE)
 330         return true;
 331       if (precision == LONG_LONG_TYPE_SIZE)
 332         return true;
 333       if (precision == 2 * BITS_PER_WORD)
 334         return true;
 335       return false;
 336
 337     case MODE_FLOAT:
 338       if (precision == FLOAT_TYPE_SIZE)
 339         return true;
 340       if (precision == DOUBLE_TYPE_SIZE)
 341         return true;
 342       if (precision == LONG_DOUBLE_TYPE_SIZE)
 343         return true;
 344       return false;
 345
 346     case MODE_DECIMAL_FLOAT:
 347     case MODE_FRACT:
 348     case MODE_UFRACT:
 349     case MODE_ACCUM:
 350     case MODE_UACCUM:
 351       return false;
 352
 353     default:
 354       gcc_unreachable ();
 355     }
 356 }
 357
 358 /* True if the target supports decimal floating point.  */
 359
 360 bool
 361 default_decimal_float_supported_p (void)
 362 {
 363   return ENABLE_DECIMAL_FLOAT;
 364 }
 365
 366 /* True if the target supports fixed-point arithmetic.  */
 367
 368 bool
 369 default_fixed_point_supported_p (void)
 370 {
 371   return ENABLE_FIXED_POINT;
 372 }
 373
 374 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 375    an error message.
 376
 377    This function checks whether a given INSN is valid within a low-overhead
 378    loop.  If INSN is invalid it returns the reason for that, otherwise it
 379    returns NULL. A called function may clobber any special registers required
 380    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 381    register for branch on table instructions. We reject the doloop pattern in
 382    these cases.  */
 383
 384 const char *
 385 default_invalid_within_doloop (const_rtx insn)
 386 {
 387   if (CALL_P (insn))
 388     return "Function call in loop.";
 389
 390   if (JUMP_TABLE_DATA_P (insn))
 391     return "Computed branch in the loop.";
 392
 393   return NULL;
 394 }
 395
 396 /* Mapping of builtin functions to vectorized variants.  */
 397
 398 tree
 399 default_builtin_vectorized_function (unsigned int fn ATTRIBUTE_UNUSED,
 400                                      tree type_out ATTRIBUTE_UNUSED,
 401                                      tree type_in ATTRIBUTE_UNUSED)
 402 {
 403   return NULL_TREE;
 404 }
 405
 406 /* Vectorized conversion.  */
 407
 408 tree
 409 default_builtin_vectorized_conversion (unsigned int code ATTRIBUTE_UNUSED,
 410                                        tree type ATTRIBUTE_UNUSED)
 411 {
 412   return NULL_TREE;
 413 }
 414
 415 /* Reciprocal.  */
 416
 417 tree
 418 default_builtin_reciprocal (unsigned int fn ATTRIBUTE_UNUSED,
 419                             bool md_fn ATTRIBUTE_UNUSED,
 420                             bool sqrt ATTRIBUTE_UNUSED)
 421 {
 422   return NULL_TREE;
 423 }
 424
 425 bool
 426 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 427         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 428         enum machine_mode mode ATTRIBUTE_UNUSED,
 429         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 430 {
 431   return false;
 432 }
 433
 434 bool
 435 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 436         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 437         enum machine_mode mode ATTRIBUTE_UNUSED,
 438         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 439 {
 440   return true;
 441 }
 442
 443 int
 444 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 445         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 446         enum machine_mode mode ATTRIBUTE_UNUSED,
 447         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 448 {
 449   return 0;
 450 }
 451
 452 void
 453 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 454 {
 455 }
 456
 457 const char *
 458 hook_invalid_arg_for_unprototyped_fn (
 459         const_tree typelist ATTRIBUTE_UNUSED,
 460         const_tree funcdecl ATTRIBUTE_UNUSED,
 461         const_tree val ATTRIBUTE_UNUSED)
 462 {
 463   return NULL;
 464 }
 465
 466 /* Initialize the stack protection decls.  */
 467
 468 /* Stack protection related decls living in libgcc.  */
 469 static GTY(()) tree stack_chk_guard_decl;
 470
 471 tree
 472 default_stack_protect_guard (void)
 473 {
 474   tree t = stack_chk_guard_decl;
 475
 476   if (t == NULL)
 477     {
 478       t = build_decl (UNKNOWN_LOCATION,
 479                       VAR_DECL, get_identifier ("__stack_chk_guard"),
 480                       ptr_type_node);
 481       TREE_STATIC (t) = 1;
 482       TREE_PUBLIC (t) = 1;
 483       DECL_EXTERNAL (t) = 1;
 484       TREE_USED (t) = 1;
 485       TREE_THIS_VOLATILE (t) = 1;
 486       DECL_ARTIFICIAL (t) = 1;
 487       DECL_IGNORED_P (t) = 1;
 488
 489       stack_chk_guard_decl = t;
 490     }
 491
 492   return t;
 493 }
 494
 495 static GTY(()) tree stack_chk_fail_decl;
 496
 497 tree
 498 default_external_stack_protect_fail (void)
 499 {
 500   tree t = stack_chk_fail_decl;
 501
 502   if (t == NULL_TREE)
 503     {
 504       t = build_function_type_list (void_type_node, NULL_TREE);
 505       t = build_decl (UNKNOWN_LOCATION,
 506                       FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 507       TREE_STATIC (t) = 1;
 508       TREE_PUBLIC (t) = 1;
 509       DECL_EXTERNAL (t) = 1;
 510       TREE_USED (t) = 1;
 511       TREE_THIS_VOLATILE (t) = 1;
 512       TREE_NOTHROW (t) = 1;
 513       DECL_ARTIFICIAL (t) = 1;
 514       DECL_IGNORED_P (t) = 1;
 515       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 516       DECL_VISIBILITY_SPECIFIED (t) = 1;
 517
 518       stack_chk_fail_decl = t;
 519     }
 520
 521   return build_call_expr (t, 0);
 522 }
 523
 524 tree
 525 default_hidden_stack_protect_fail (void)
 526 {
 527 #ifndef HAVE_GAS_HIDDEN
 528   return default_external_stack_protect_fail ();
 529 #else
 530   tree t = stack_chk_fail_decl;
 531
 532   if (!flag_pic)
 533     return default_external_stack_protect_fail ();
 534
 535   if (t == NULL_TREE)
 536     {
 537       t = build_function_type_list (void_type_node, NULL_TREE);
 538       t = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL,
 539                       get_identifier ("__stack_chk_fail_local"), t);
 540       TREE_STATIC (t) = 1;
 541       TREE_PUBLIC (t) = 1;
 542       DECL_EXTERNAL (t) = 1;
 543       TREE_USED (t) = 1;
 544       TREE_THIS_VOLATILE (t) = 1;
 545       TREE_NOTHROW (t) = 1;
 546       DECL_ARTIFICIAL (t) = 1;
 547       DECL_IGNORED_P (t) = 1;
 548       DECL_VISIBILITY_SPECIFIED (t) = 1;
 549       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 550
 551       stack_chk_fail_decl = t;
 552     }
 553
 554   return build_call_expr (t, 0);
 555 #endif
 556 }
 557
 558 bool
 559 hook_bool_const_rtx_commutative_p (const_rtx x,
 560                                    int outer_code ATTRIBUTE_UNUSED)
 561 {
 562   return COMMUTATIVE_P (x);
 563 }
 564
 565 rtx
 566 default_function_value (const_tree ret_type ATTRIBUTE_UNUSED,
 567                         const_tree fn_decl_or_type,
 568                         bool outgoing ATTRIBUTE_UNUSED)
 569 {
 570   /* The old interface doesn't handle receiving the function type.  */
 571   if (fn_decl_or_type
 572       && !DECL_P (fn_decl_or_type))
 573     fn_decl_or_type = NULL;
 574
 575 #ifdef FUNCTION_OUTGOING_VALUE
 576   if (outgoing)
 577     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 578 #endif
 579
 580 #ifdef FUNCTION_VALUE
 581   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 582 #else
 583   return NULL_RTX;
 584 #endif
 585 }
 586
 587 rtx
 588 default_internal_arg_pointer (void)
 589 {
 590   /* If the reg that the virtual arg pointer will be translated into is
 591      not a fixed reg or is the stack pointer, make a copy of the virtual
 592      arg pointer, and address parms via the copy.  The frame pointer is
 593      considered fixed even though it is not marked as such.  */
 594   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 595        || ! (fixed_regs[ARG_POINTER_REGNUM]
 596              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 597     return copy_to_reg (virtual_incoming_args_rtx);
 598   else
 599     return virtual_incoming_args_rtx;
 600 }
 601
 602 enum reg_class
 603 default_branch_target_register_class (void)
 604 {
 605   return NO_REGS;
 606 }
 607
 608 #ifdef IRA_COVER_CLASSES
 609 const enum reg_class *
 610 default_ira_cover_classes (void)
 611 {
 612   static enum reg_class classes[] = IRA_COVER_CLASSES;
 613   return classes;
 614 }
 615 #endif
 616
 617 enum reg_class
 618 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 619                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 620                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 621                           secondary_reload_info *sri)
 622 {
 623   enum reg_class rclass = NO_REGS;
 624
 625   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 626     {
 627       sri->icode = sri->prev_sri->t_icode;
 628       return NO_REGS;
 629     }
 630 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 631   if (in_p)
 632     rclass = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 633 #endif
 634 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 635   if (! in_p)
 636     rclass = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 637 #endif
 638   if (rclass != NO_REGS)
 639     {
 640       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 641                               : reload_out_optab[(int) reload_mode]);
 642
 643       if (icode != CODE_FOR_nothing
 644           && insn_data[(int) icode].operand[in_p].predicate
 645           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 646         icode = CODE_FOR_nothing;
 647       else if (icode != CODE_FOR_nothing)
 648         {
 649           const char *insn_constraint, *scratch_constraint;
 650           char insn_letter, scratch_letter;
 651           enum reg_class insn_class, scratch_class;
 652
 653           gcc_assert (insn_data[(int) icode].n_operands == 3);
 654           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 655           if (!*insn_constraint)
 656             insn_class = ALL_REGS;
 657           else
 658             {
 659               if (in_p)
 660                 {
 661                   gcc_assert (*insn_constraint == '=');
 662                   insn_constraint++;
 663                 }
 664               insn_letter = *insn_constraint;
 665               insn_class
 666                 = (insn_letter == 'r' ? GENERAL_REGS
 667                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 668                                                 insn_constraint));
 669               gcc_assert (insn_class != NO_REGS);
 670             }
 671
 672           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 673           /* The scratch register's constraint must start with "=&",
 674              except for an input reload, where only "=" is necessary,
 675              and where it might be beneficial to re-use registers from
 676              the input.  */
 677           gcc_assert (scratch_constraint[0] == '='
 678                       && (in_p || scratch_constraint[1] == '&'));
 679           scratch_constraint++;
 680           if (*scratch_constraint == '&')
 681             scratch_constraint++;
 682           scratch_letter = *scratch_constraint;
 683           scratch_class
 684             = (scratch_letter == 'r' ? GENERAL_REGS
 685                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 686                                             scratch_constraint));
 687
 688           if (reg_class_subset_p (reload_class, insn_class))
 689             {
 690               gcc_assert (scratch_class == rclass);
 691               rclass = NO_REGS;
 692             }
 693           else
 694             rclass = insn_class;
 695
 696         }
 697       if (rclass == NO_REGS)
 698         sri->icode = icode;
 699       else
 700         sri->t_icode = icode;
 701     }
 702   return rclass;
 703 }
 704
 705 bool
 706 default_handle_c_option (size_t code ATTRIBUTE_UNUSED,
 707                          const char *arg ATTRIBUTE_UNUSED,
 708                          int value ATTRIBUTE_UNUSED)
 709 {
 710   return false;
 711 }
 712
 713 /* By default, if flag_pic is true, then neither local nor global relocs
 714    should be placed in readonly memory.  */
 715
 716 int
 717 default_reloc_rw_mask (void)
 718 {
 719   return flag_pic ? 3 : 0;
 720 }
 721
 722 /* By default, do no modification. */
 723 tree default_mangle_decl_assembler_name (tree decl ATTRIBUTE_UNUSED,
 724                                          tree id)
 725 {
 726    return id;
 727 }
 728
 729 bool
 730 default_builtin_vector_alignment_reachable (const_tree type, bool is_packed)
 731 {
 732   if (is_packed)
 733     return false;
 734
 735   /* Assuming that types whose size is > pointer-size are not guaranteed to be
 736      naturally aligned.  */
 737   if (tree_int_cst_compare (TYPE_SIZE (type), bitsize_int (POINTER_SIZE)) > 0)
 738     return false;
 739
 740   /* Assuming that types whose size is <= pointer-size
 741      are naturally aligned.  */
 742   return true;
 743 }
 744
 745 bool
 746 default_hard_regno_scratch_ok (unsigned int regno ATTRIBUTE_UNUSED)
 747 {
 748   return true;
 749 }
 750
 751 bool
 752 default_target_option_valid_attribute_p (tree ARG_UNUSED (fndecl),
 753                                          tree ARG_UNUSED (name),
 754                                          tree ARG_UNUSED (args),
 755                                          int ARG_UNUSED (flags))
 756 {
 757   warning (OPT_Wattributes,
 758            "target attribute is not supported on this machine");
 759
 760   return false;
 761 }
 762
 763 bool
 764 default_target_option_pragma_parse (tree ARG_UNUSED (args),
 765                                     tree ARG_UNUSED (pop_target))
 766 {
 767   warning (OPT_Wpragmas,
 768            "#pragma GCC target is not supported for this machine");
 769
 770   return false;
 771 }
 772
 773 bool
 774 default_target_option_can_inline_p (tree caller, tree callee)
 775 {
 776   bool ret = false;
 777   tree callee_opts = DECL_FUNCTION_SPECIFIC_TARGET (callee);
 778   tree caller_opts = DECL_FUNCTION_SPECIFIC_TARGET (caller);
 779
 780   /* If callee has no option attributes, then it is ok to inline */
 781   if (!callee_opts)
 782     ret = true;
 783
 784   /* If caller has no option attributes, but callee does then it is not ok to
 785      inline */
 786   else if (!caller_opts)
 787     ret = false;
 788
 789   /* If both caller and callee have attributes, assume that if the pointer is
 790      different, the the two functions have different target options since
 791      build_target_option_node uses a hash table for the options.  */
 792   else
 793     ret = (callee_opts == caller_opts);
 794
 795   return ret;
 796 }
 797
 798 #ifndef HAVE_casesi
 799 # define HAVE_casesi 0
 800 #endif
 801
 802 /* If the machine does not have a case insn that compares the bounds,
 803    this means extra overhead for dispatch tables, which raises the
 804    threshold for using them.  */
 805
 806 unsigned int default_case_values_threshold (void)
 807 {
 808   return (HAVE_casesi ? 4 : 5);
 809 }
 810
 811 #include "gt-targhooks.h"