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_promote_function_mode (const_tree type ATTRIBUTE_UNUSED,
 117                                enum machine_mode mode,
 118                                int *punsignedp ATTRIBUTE_UNUSED,
 119                                const_tree funtype ATTRIBUTE_UNUSED,
 120                                int for_return ATTRIBUTE_UNUSED)
 121 {
 122   if (for_return == 2)
 123     return promote_mode (type, mode, punsignedp);
 124   return mode;
 125 }
 126
 127 enum machine_mode
 128 default_promote_function_mode_always_promote (const_tree type,
 129                                               enum machine_mode mode,
 130                                               int *punsignedp,
 131                                               const_tree funtype ATTRIBUTE_UNUSED,
 132                                               int for_return ATTRIBUTE_UNUSED)
 133 {
 134   return promote_mode (type, mode, punsignedp);
 135 }
 136
 137
 138 enum machine_mode
 139 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
 140 {
 141   if (m1 == m2)
 142     return m1;
 143   return VOIDmode;
 144 }
 145
 146 bool
 147 default_return_in_memory (const_tree type,
 148                           const_tree fntype ATTRIBUTE_UNUSED)
 149 {
 150   return (TYPE_MODE (type) == BLKmode);
 151 }
 152
 153 rtx
 154 default_legitimize_address (rtx x, rtx orig_x ATTRIBUTE_UNUSED,
 155                             enum machine_mode mode ATTRIBUTE_UNUSED)
 156 {
 157   return x;
 158 }
 159
 160 rtx
 161 default_expand_builtin_saveregs (void)
 162 {
 163   error ("__builtin_saveregs not supported by this target");
 164   return const0_rtx;
 165 }
 166
 167 void
 168 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 169                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 170                                 tree type ATTRIBUTE_UNUSED,
 171                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 172                                 int second_time ATTRIBUTE_UNUSED)
 173 {
 174 }
 175
 176 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 177
 178 rtx
 179 default_builtin_setjmp_frame_value (void)
 180 {
 181   return virtual_stack_vars_rtx;
 182 }
 183
 184 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 185
 186 bool
 187 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 188 {
 189   return false;
 190 }
 191
 192 bool
 193 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 194 {
 195   return (targetm.calls.setup_incoming_varargs
 196           != default_setup_incoming_varargs);
 197 }
 198
 199 enum machine_mode
 200 default_eh_return_filter_mode (void)
 201 {
 202   return targetm.unwind_word_mode ();
 203 }
 204
 205 enum machine_mode
 206 default_libgcc_cmp_return_mode (void)
 207 {
 208   return word_mode;
 209 }
 210
 211 enum machine_mode
 212 default_libgcc_shift_count_mode (void)
 213 {
 214   return word_mode;
 215 }
 216
 217 enum machine_mode
 218 default_unwind_word_mode (void)
 219 {
 220   return word_mode;
 221 }
 222
 223 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 224
 225 unsigned HOST_WIDE_INT
 226 default_shift_truncation_mask (enum machine_mode mode)
 227 {
 228   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 229 }
 230
 231 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 232
 233 unsigned int
 234 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 235 {
 236   return have_insn_for (DIV, mode) ? 3 : 2;
 237 }
 238
 239 /* The default implementation of TARGET_MODE_REP_EXTENDED.  */
 240
 241 int
 242 default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED,
 243                            enum machine_mode mode_rep ATTRIBUTE_UNUSED)
 244 {
 245   return UNKNOWN;
 246 }
 247
 248 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 249
 250 bool
 251 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 252 {
 253   return true;
 254 }
 255
 256 /* Return machine mode for non-standard suffix
 257    or VOIDmode if non-standard suffixes are unsupported.  */
 258 enum machine_mode
 259 default_mode_for_suffix (char suffix ATTRIBUTE_UNUSED)
 260 {
 261   return VOIDmode;
 262 }
 263
 264 /* The generic C++ ABI specifies this is a 64-bit value.  */
 265 tree
 266 default_cxx_guard_type (void)
 267 {
 268   return long_long_integer_type_node;
 269 }
 270
 271
 272 /* Returns the size of the cookie to use when allocating an array
 273    whose elements have the indicated TYPE.  Assumes that it is already
 274    known that a cookie is needed.  */
 275
 276 tree
 277 default_cxx_get_cookie_size (tree type)
 278 {
 279   tree cookie_size;
 280
 281   /* We need to allocate an additional max (sizeof (size_t), alignof
 282      (true_type)) bytes.  */
 283   tree sizetype_size;
 284   tree type_align;
 285
 286   sizetype_size = size_in_bytes (sizetype);
 287   type_align = size_int (TYPE_ALIGN_UNIT (type));
 288   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 289     cookie_size = sizetype_size;
 290   else
 291     cookie_size = type_align;
 292
 293   return cookie_size;
 294 }
 295
 296 /* Return true if a parameter must be passed by reference.  This version
 297    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 298
 299 bool
 300 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 301         enum machine_mode mode ATTRIBUTE_UNUSED, const_tree type ATTRIBUTE_UNUSED,
 302         bool named_arg ATTRIBUTE_UNUSED)
 303 {
 304   return targetm.calls.must_pass_in_stack (mode, type);
 305 }
 306
 307 /* Return true if a parameter follows callee copies conventions.  This
 308    version of the hook is true for all named arguments.  */
 309
 310 bool
 311 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 312                           enum machine_mode mode ATTRIBUTE_UNUSED,
 313                           const_tree type ATTRIBUTE_UNUSED, bool named)
 314 {
 315   return named;
 316 }
 317
 318 /* Emit any directives required to unwind this instruction.  */
 319
 320 void
 321 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 322                      rtx insn ATTRIBUTE_UNUSED)
 323 {
 324   /* Should never happen.  */
 325   gcc_unreachable ();
 326 }
 327
 328 /* True if MODE is valid for the target.  By "valid", we mean able to
 329    be manipulated in non-trivial ways.  In particular, this means all
 330    the arithmetic is supported.
 331
 332    By default we guess this means that any C type is supported.  If
 333    we can't map the mode back to a type that would be available in C,
 334    then reject it.  Special case, here, is the double-word arithmetic
 335    supported by optabs.c.  */
 336
 337 bool
 338 default_scalar_mode_supported_p (enum machine_mode mode)
 339 {
 340   int precision = GET_MODE_PRECISION (mode);
 341
 342   switch (GET_MODE_CLASS (mode))
 343     {
 344     case MODE_PARTIAL_INT:
 345     case MODE_INT:
 346       if (precision == CHAR_TYPE_SIZE)
 347         return true;
 348       if (precision == SHORT_TYPE_SIZE)
 349         return true;
 350       if (precision == INT_TYPE_SIZE)
 351         return true;
 352       if (precision == LONG_TYPE_SIZE)
 353         return true;
 354       if (precision == LONG_LONG_TYPE_SIZE)
 355         return true;
 356       if (precision == 2 * BITS_PER_WORD)
 357         return true;
 358       return false;
 359
 360     case MODE_FLOAT:
 361       if (precision == FLOAT_TYPE_SIZE)
 362         return true;
 363       if (precision == DOUBLE_TYPE_SIZE)
 364         return true;
 365       if (precision == LONG_DOUBLE_TYPE_SIZE)
 366         return true;
 367       return false;
 368
 369     case MODE_DECIMAL_FLOAT:
 370     case MODE_FRACT:
 371     case MODE_UFRACT:
 372     case MODE_ACCUM:
 373     case MODE_UACCUM:
 374       return false;
 375
 376     default:
 377       gcc_unreachable ();
 378     }
 379 }
 380
 381 /* True if the target supports decimal floating point.  */
 382
 383 bool
 384 default_decimal_float_supported_p (void)
 385 {
 386   return ENABLE_DECIMAL_FLOAT;
 387 }
 388
 389 /* True if the target supports fixed-point arithmetic.  */
 390
 391 bool
 392 default_fixed_point_supported_p (void)
 393 {
 394   return ENABLE_FIXED_POINT;
 395 }
 396
 397 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 398    an error message.
 399
 400    This function checks whether a given INSN is valid within a low-overhead
 401    loop.  If INSN is invalid it returns the reason for that, otherwise it
 402    returns NULL. A called function may clobber any special registers required
 403    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 404    register for branch on table instructions. We reject the doloop pattern in
 405    these cases.  */
 406
 407 const char *
 408 default_invalid_within_doloop (const_rtx insn)
 409 {
 410   if (CALL_P (insn))
 411     return "Function call in loop.";
 412
 413   if (JUMP_TABLE_DATA_P (insn))
 414     return "Computed branch in the loop.";
 415
 416   return NULL;
 417 }
 418
 419 /* Mapping of builtin functions to vectorized variants.  */
 420
 421 tree
 422 default_builtin_vectorized_function (unsigned int fn ATTRIBUTE_UNUSED,
 423                                      tree type_out ATTRIBUTE_UNUSED,
 424                                      tree type_in ATTRIBUTE_UNUSED)
 425 {
 426   return NULL_TREE;
 427 }
 428
 429 /* Vectorized conversion.  */
 430
 431 tree
 432 default_builtin_vectorized_conversion (unsigned int code ATTRIBUTE_UNUSED,
 433                                        tree type ATTRIBUTE_UNUSED)
 434 {
 435   return NULL_TREE;
 436 }
 437
 438 /* Reciprocal.  */
 439
 440 tree
 441 default_builtin_reciprocal (unsigned int fn ATTRIBUTE_UNUSED,
 442                             bool md_fn ATTRIBUTE_UNUSED,
 443                             bool sqrt ATTRIBUTE_UNUSED)
 444 {
 445   return NULL_TREE;
 446 }
 447
 448 bool
 449 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 450         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 451         enum machine_mode mode ATTRIBUTE_UNUSED,
 452         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 453 {
 454   return false;
 455 }
 456
 457 bool
 458 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 459         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 460         enum machine_mode mode ATTRIBUTE_UNUSED,
 461         const_tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 462 {
 463   return true;
 464 }
 465
 466 int
 467 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 468         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 469         enum machine_mode mode ATTRIBUTE_UNUSED,
 470         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 471 {
 472   return 0;
 473 }
 474
 475 void
 476 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 477 {
 478 }
 479
 480 const char *
 481 hook_invalid_arg_for_unprototyped_fn (
 482         const_tree typelist ATTRIBUTE_UNUSED,
 483         const_tree funcdecl ATTRIBUTE_UNUSED,
 484         const_tree val ATTRIBUTE_UNUSED)
 485 {
 486   return NULL;
 487 }
 488
 489 /* Initialize the stack protection decls.  */
 490
 491 /* Stack protection related decls living in libgcc.  */
 492 static GTY(()) tree stack_chk_guard_decl;
 493
 494 tree
 495 default_stack_protect_guard (void)
 496 {
 497   tree t = stack_chk_guard_decl;
 498
 499   if (t == NULL)
 500     {
 501       t = build_decl (UNKNOWN_LOCATION,
 502                       VAR_DECL, get_identifier ("__stack_chk_guard"),
 503                       ptr_type_node);
 504       TREE_STATIC (t) = 1;
 505       TREE_PUBLIC (t) = 1;
 506       DECL_EXTERNAL (t) = 1;
 507       TREE_USED (t) = 1;
 508       TREE_THIS_VOLATILE (t) = 1;
 509       DECL_ARTIFICIAL (t) = 1;
 510       DECL_IGNORED_P (t) = 1;
 511
 512       stack_chk_guard_decl = t;
 513     }
 514
 515   return t;
 516 }
 517
 518 static GTY(()) tree stack_chk_fail_decl;
 519
 520 tree
 521 default_external_stack_protect_fail (void)
 522 {
 523   tree t = stack_chk_fail_decl;
 524
 525   if (t == NULL_TREE)
 526     {
 527       t = build_function_type_list (void_type_node, NULL_TREE);
 528       t = build_decl (UNKNOWN_LOCATION,
 529                       FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 530       TREE_STATIC (t) = 1;
 531       TREE_PUBLIC (t) = 1;
 532       DECL_EXTERNAL (t) = 1;
 533       TREE_USED (t) = 1;
 534       TREE_THIS_VOLATILE (t) = 1;
 535       TREE_NOTHROW (t) = 1;
 536       DECL_ARTIFICIAL (t) = 1;
 537       DECL_IGNORED_P (t) = 1;
 538       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 539       DECL_VISIBILITY_SPECIFIED (t) = 1;
 540
 541       stack_chk_fail_decl = t;
 542     }
 543
 544   return build_call_expr (t, 0);
 545 }
 546
 547 tree
 548 default_hidden_stack_protect_fail (void)
 549 {
 550 #ifndef HAVE_GAS_HIDDEN
 551   return default_external_stack_protect_fail ();
 552 #else
 553   tree t = stack_chk_fail_decl;
 554
 555   if (!flag_pic)
 556     return default_external_stack_protect_fail ();
 557
 558   if (t == NULL_TREE)
 559     {
 560       t = build_function_type_list (void_type_node, NULL_TREE);
 561       t = build_decl (UNKNOWN_LOCATION, FUNCTION_DECL,
 562                       get_identifier ("__stack_chk_fail_local"), t);
 563       TREE_STATIC (t) = 1;
 564       TREE_PUBLIC (t) = 1;
 565       DECL_EXTERNAL (t) = 1;
 566       TREE_USED (t) = 1;
 567       TREE_THIS_VOLATILE (t) = 1;
 568       TREE_NOTHROW (t) = 1;
 569       DECL_ARTIFICIAL (t) = 1;
 570       DECL_IGNORED_P (t) = 1;
 571       DECL_VISIBILITY_SPECIFIED (t) = 1;
 572       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 573
 574       stack_chk_fail_decl = t;
 575     }
 576
 577   return build_call_expr (t, 0);
 578 #endif
 579 }
 580
 581 bool
 582 hook_bool_const_rtx_commutative_p (const_rtx x,
 583                                    int outer_code ATTRIBUTE_UNUSED)
 584 {
 585   return COMMUTATIVE_P (x);
 586 }
 587
 588 rtx
 589 default_function_value (const_tree ret_type ATTRIBUTE_UNUSED,
 590                         const_tree fn_decl_or_type,
 591                         bool outgoing ATTRIBUTE_UNUSED)
 592 {
 593   /* The old interface doesn't handle receiving the function type.  */
 594   if (fn_decl_or_type
 595       && !DECL_P (fn_decl_or_type))
 596     fn_decl_or_type = NULL;
 597
 598 #ifdef FUNCTION_OUTGOING_VALUE
 599   if (outgoing)
 600     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 601 #endif
 602
 603 #ifdef FUNCTION_VALUE
 604   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 605 #else
 606   return NULL_RTX;
 607 #endif
 608 }
 609
 610 rtx
 611 default_libcall_value (enum machine_mode mode, rtx fun ATTRIBUTE_UNUSED)
 612 {
 613   return LIBCALL_VALUE (mode);
 614 }
 615
 616 rtx
 617 default_internal_arg_pointer (void)
 618 {
 619   /* If the reg that the virtual arg pointer will be translated into is
 620      not a fixed reg or is the stack pointer, make a copy of the virtual
 621      arg pointer, and address parms via the copy.  The frame pointer is
 622      considered fixed even though it is not marked as such.  */
 623   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 624        || ! (fixed_regs[ARG_POINTER_REGNUM]
 625              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 626     return copy_to_reg (virtual_incoming_args_rtx);
 627   else
 628     return virtual_incoming_args_rtx;
 629 }
 630
 631 enum reg_class
 632 default_branch_target_register_class (void)
 633 {
 634   return NO_REGS;
 635 }
 636
 637 #ifdef IRA_COVER_CLASSES
 638 const enum reg_class *
 639 default_ira_cover_classes (void)
 640 {
 641   static enum reg_class classes[] = IRA_COVER_CLASSES;
 642   return classes;
 643 }
 644 #endif
 645
 646 enum reg_class
 647 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 648                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 649                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 650                           secondary_reload_info *sri)
 651 {
 652   enum reg_class rclass = NO_REGS;
 653
 654   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 655     {
 656       sri->icode = sri->prev_sri->t_icode;
 657       return NO_REGS;
 658     }
 659 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 660   if (in_p)
 661     rclass = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 662 #endif
 663 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 664   if (! in_p)
 665     rclass = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 666 #endif
 667   if (rclass != NO_REGS)
 668     {
 669       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 670                               : reload_out_optab[(int) reload_mode]);
 671
 672       if (icode != CODE_FOR_nothing
 673           && insn_data[(int) icode].operand[in_p].predicate
 674           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 675         icode = CODE_FOR_nothing;
 676       else if (icode != CODE_FOR_nothing)
 677         {
 678           const char *insn_constraint, *scratch_constraint;
 679           char insn_letter, scratch_letter;
 680           enum reg_class insn_class, scratch_class;
 681
 682           gcc_assert (insn_data[(int) icode].n_operands == 3);
 683           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 684           if (!*insn_constraint)
 685             insn_class = ALL_REGS;
 686           else
 687             {
 688               if (in_p)
 689                 {
 690                   gcc_assert (*insn_constraint == '=');
 691                   insn_constraint++;
 692                 }
 693               insn_letter = *insn_constraint;
 694               insn_class
 695                 = (insn_letter == 'r' ? GENERAL_REGS
 696                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 697                                                 insn_constraint));
 698               gcc_assert (insn_class != NO_REGS);
 699             }
 700
 701           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 702           /* The scratch register's constraint must start with "=&",
 703              except for an input reload, where only "=" is necessary,
 704              and where it might be beneficial to re-use registers from
 705              the input.  */
 706           gcc_assert (scratch_constraint[0] == '='
 707                       && (in_p || scratch_constraint[1] == '&'));
 708           scratch_constraint++;
 709           if (*scratch_constraint == '&')
 710             scratch_constraint++;
 711           scratch_letter = *scratch_constraint;
 712           scratch_class
 713             = (scratch_letter == 'r' ? GENERAL_REGS
 714                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 715                                             scratch_constraint));
 716
 717           if (reg_class_subset_p (reload_class, insn_class))
 718             {
 719               gcc_assert (scratch_class == rclass);
 720               rclass = NO_REGS;
 721             }
 722           else
 723             rclass = insn_class;
 724
 725         }
 726       if (rclass == NO_REGS)
 727         sri->icode = icode;
 728       else
 729         sri->t_icode = icode;
 730     }
 731   return rclass;
 732 }
 733
 734 bool
 735 default_handle_c_option (size_t code ATTRIBUTE_UNUSED,
 736                          const char *arg ATTRIBUTE_UNUSED,
 737                          int value ATTRIBUTE_UNUSED)
 738 {
 739   return false;
 740 }
 741
 742 /* By default, if flag_pic is true, then neither local nor global relocs
 743    should be placed in readonly memory.  */
 744
 745 int
 746 default_reloc_rw_mask (void)
 747 {
 748   return flag_pic ? 3 : 0;
 749 }
 750
 751 /* By default, do no modification. */
 752 tree default_mangle_decl_assembler_name (tree decl ATTRIBUTE_UNUSED,
 753                                          tree id)
 754 {
 755    return id;
 756 }
 757
 758 bool
 759 default_builtin_vector_alignment_reachable (const_tree type, bool is_packed)
 760 {
 761   if (is_packed)
 762     return false;
 763
 764   /* Assuming that types whose size is > pointer-size are not guaranteed to be
 765      naturally aligned.  */
 766   if (tree_int_cst_compare (TYPE_SIZE (type), bitsize_int (POINTER_SIZE)) > 0)
 767     return false;
 768
 769   /* Assuming that types whose size is <= pointer-size
 770      are naturally aligned.  */
 771   return true;
 772 }
 773
 774 bool
 775 default_hard_regno_scratch_ok (unsigned int regno ATTRIBUTE_UNUSED)
 776 {
 777   return true;
 778 }
 779
 780 bool
 781 default_target_option_valid_attribute_p (tree ARG_UNUSED (fndecl),
 782                                          tree ARG_UNUSED (name),
 783                                          tree ARG_UNUSED (args),
 784                                          int ARG_UNUSED (flags))
 785 {
 786   warning (OPT_Wattributes,
 787            "target attribute is not supported on this machine");
 788
 789   return false;
 790 }
 791
 792 bool
 793 default_target_option_pragma_parse (tree ARG_UNUSED (args),
 794                                     tree ARG_UNUSED (pop_target))
 795 {
 796   warning (OPT_Wpragmas,
 797            "#pragma GCC target is not supported for this machine");
 798
 799   return false;
 800 }
 801
 802 bool
 803 default_target_can_inline_p (tree caller, tree callee)
 804 {
 805   bool ret = false;
 806   tree callee_opts = DECL_FUNCTION_SPECIFIC_TARGET (callee);
 807   tree caller_opts = DECL_FUNCTION_SPECIFIC_TARGET (caller);
 808
 809   /* If callee has no option attributes, then it is ok to inline */
 810   if (!callee_opts)
 811     ret = true;
 812
 813   /* If caller has no option attributes, but callee does then it is not ok to
 814      inline */
 815   else if (!caller_opts)
 816     ret = false;
 817
 818   /* If both caller and callee have attributes, assume that if the pointer is
 819      different, the the two functions have different target options since
 820      build_target_option_node uses a hash table for the options.  */
 821   else
 822     ret = (callee_opts == caller_opts);
 823
 824   return ret;
 825 }
 826
 827 #ifndef HAVE_casesi
 828 # define HAVE_casesi 0
 829 #endif
 830
 831 /* If the machine does not have a case insn that compares the bounds,
 832    this means extra overhead for dispatch tables, which raises the
 833    threshold for using them.  */
 834
 835 unsigned int default_case_values_threshold (void)
 836 {
 837   return (HAVE_casesi ? 4 : 5);
 838 }
 839
 840 #include "gt-targhooks.h"