gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  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 enum machine_mode
  80 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  81 {
  82   if (m1 == m2)
  83     return m1;
  84   return VOIDmode;
  85 }
  86
  87 bool
  88 default_return_in_memory (tree type,
  89                           tree fntype ATTRIBUTE_UNUSED)
  90 {
  91 #ifndef RETURN_IN_MEMORY
  92   return (TYPE_MODE (type) == BLKmode);
  93 #else
  94   return RETURN_IN_MEMORY (type);
  95 #endif
  96 }
  97
  98 rtx
  99 default_expand_builtin_saveregs (void)
 100 {
 101   error ("__builtin_saveregs not supported by this target");
 102   return const0_rtx;
 103 }
 104
 105 void
 106 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 107                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 108                                 tree type ATTRIBUTE_UNUSED,
 109                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 110                                 int second_time ATTRIBUTE_UNUSED)
 111 {
 112 }
 113
 114 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 115
 116 rtx
 117 default_builtin_setjmp_frame_value (void)
 118 {
 119   return virtual_stack_vars_rtx;
 120 }
 121
 122 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 123
 124 bool
 125 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 126 {
 127   return false;
 128 }
 129
 130 bool
 131 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 132 {
 133   return (targetm.calls.setup_incoming_varargs
 134           != default_setup_incoming_varargs);
 135 }
 136
 137 enum machine_mode
 138 default_eh_return_filter_mode (void)
 139 {
 140   return word_mode;
 141 }
 142
 143 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 144
 145 unsigned HOST_WIDE_INT
 146 default_shift_truncation_mask (enum machine_mode mode)
 147 {
 148   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 149 }
 150
 151 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 152
 153 unsigned int
 154 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 155 {
 156   return have_insn_for (DIV, mode) ? 3 : 2;
 157 }
 158
 159 /* The default implementation of TARGET_MODE_REP_EXTENDED.  */
 160
 161 int
 162 default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED,
 163                            enum machine_mode mode_rep ATTRIBUTE_UNUSED)
 164 {
 165   return UNKNOWN;
 166 }
 167
 168 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 169
 170 bool
 171 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 172 {
 173   return true;
 174 }
 175
 176
 177 /* The generic C++ ABI specifies this is a 64-bit value.  */
 178 tree
 179 default_cxx_guard_type (void)
 180 {
 181   return long_long_integer_type_node;
 182 }
 183
 184
 185 /* Returns the size of the cookie to use when allocating an array
 186    whose elements have the indicated TYPE.  Assumes that it is already
 187    known that a cookie is needed.  */
 188
 189 tree
 190 default_cxx_get_cookie_size (tree type)
 191 {
 192   tree cookie_size;
 193
 194   /* We need to allocate an additional max (sizeof (size_t), alignof
 195      (true_type)) bytes.  */
 196   tree sizetype_size;
 197   tree type_align;
 198
 199   sizetype_size = size_in_bytes (sizetype);
 200   type_align = size_int (TYPE_ALIGN_UNIT (type));
 201   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 202     cookie_size = sizetype_size;
 203   else
 204     cookie_size = type_align;
 205
 206   return cookie_size;
 207 }
 208
 209 /* Return true if a parameter must be passed by reference.  This version
 210    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 211
 212 bool
 213 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 214         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 215         bool named_arg ATTRIBUTE_UNUSED)
 216 {
 217   return targetm.calls.must_pass_in_stack (mode, type);
 218 }
 219
 220 /* Return true if a parameter follows callee copies conventions.  This
 221    version of the hook is true for all named arguments.  */
 222
 223 bool
 224 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 225                           enum machine_mode mode ATTRIBUTE_UNUSED,
 226                           tree type ATTRIBUTE_UNUSED, bool named)
 227 {
 228   return named;
 229 }
 230
 231 /* Emit any directives required to unwind this instruction.  */
 232
 233 void
 234 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 235                      rtx insn ATTRIBUTE_UNUSED)
 236 {
 237   /* Should never happen.  */
 238   gcc_unreachable ();
 239 }
 240
 241 /* True if MODE is valid for the target.  By "valid", we mean able to
 242    be manipulated in non-trivial ways.  In particular, this means all
 243    the arithmetic is supported.
 244
 245    By default we guess this means that any C type is supported.  If
 246    we can't map the mode back to a type that would be available in C,
 247    then reject it.  Special case, here, is the double-word arithmetic
 248    supported by optabs.c.  */
 249
 250 bool
 251 default_scalar_mode_supported_p (enum machine_mode mode)
 252 {
 253   int precision = GET_MODE_PRECISION (mode);
 254
 255   switch (GET_MODE_CLASS (mode))
 256     {
 257     case MODE_PARTIAL_INT:
 258     case MODE_INT:
 259       if (precision == CHAR_TYPE_SIZE)
 260         return true;
 261       if (precision == SHORT_TYPE_SIZE)
 262         return true;
 263       if (precision == INT_TYPE_SIZE)
 264         return true;
 265       if (precision == LONG_TYPE_SIZE)
 266         return true;
 267       if (precision == LONG_LONG_TYPE_SIZE)
 268         return true;
 269       if (precision == 2 * BITS_PER_WORD)
 270         return true;
 271       return false;
 272
 273     case MODE_FLOAT:
 274       if (precision == FLOAT_TYPE_SIZE)
 275         return true;
 276       if (precision == DOUBLE_TYPE_SIZE)
 277         return true;
 278       if (precision == LONG_DOUBLE_TYPE_SIZE)
 279         return true;
 280       return false;
 281
 282     case MODE_DECIMAL_FLOAT:
 283       return false;
 284
 285     default:
 286       gcc_unreachable ();
 287     }
 288 }
 289
 290 /* True if the target supports decimal floating point.  */
 291
 292 bool
 293 default_decimal_float_supported_p (void)
 294 {
 295   return ENABLE_DECIMAL_FLOAT;
 296 }
 297
 298 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 299    an error message.
 300
 301    This function checks whether a given INSN is valid within a low-overhead
 302    loop.  If INSN is invalid it returns the reason for that, otherwise it
 303    returns NULL. A called function may clobber any special registers required
 304    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 305    register for branch on table instructions. We reject the doloop pattern in
 306    these cases.  */
 307
 308 const char *
 309 default_invalid_within_doloop (rtx insn)
 310 {
 311   if (CALL_P (insn))
 312     return "Function call in loop.";
 313
 314   if (JUMP_P (insn)
 315       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 316           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 317     return "Computed branch in the loop.";
 318
 319   return NULL;
 320 }
 321
 322 /* Mapping of builtin functions to vectorized variants.  */
 323
 324 tree
 325 default_builtin_vectorized_function (enum built_in_function fn ATTRIBUTE_UNUSED,
 326                                      tree type_out ATTRIBUTE_UNUSED,
 327                                      tree type_in ATTRIBUTE_UNUSED)
 328 {
 329   return NULL_TREE;
 330 }
 331
 332 /* Vectorized conversion.  */
 333
 334 tree
 335 default_builtin_vectorized_conversion (enum tree_code code ATTRIBUTE_UNUSED,
 336                                        tree type ATTRIBUTE_UNUSED)
 337 {
 338   return NULL_TREE;
 339 }
 340
 341 bool
 342 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 343         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 344         enum machine_mode mode ATTRIBUTE_UNUSED,
 345         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 346 {
 347   return false;
 348 }
 349
 350 bool
 351 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 352         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 353         enum machine_mode mode ATTRIBUTE_UNUSED,
 354         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 355 {
 356   return true;
 357 }
 358
 359 int
 360 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 361         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 362         enum machine_mode mode ATTRIBUTE_UNUSED,
 363         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 364 {
 365   return 0;
 366 }
 367
 368 void
 369 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 370 {
 371 }
 372
 373 const char *
 374 hook_invalid_arg_for_unprototyped_fn (
 375         tree typelist ATTRIBUTE_UNUSED,
 376         tree funcdecl ATTRIBUTE_UNUSED,
 377         tree val ATTRIBUTE_UNUSED)
 378 {
 379   return NULL;
 380 }
 381
 382 /* Initialize the stack protection decls.  */
 383
 384 /* Stack protection related decls living in libgcc.  */
 385 static GTY(()) tree stack_chk_guard_decl;
 386
 387 tree
 388 default_stack_protect_guard (void)
 389 {
 390   tree t = stack_chk_guard_decl;
 391
 392   if (t == NULL)
 393     {
 394       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 395                       ptr_type_node);
 396       TREE_STATIC (t) = 1;
 397       TREE_PUBLIC (t) = 1;
 398       DECL_EXTERNAL (t) = 1;
 399       TREE_USED (t) = 1;
 400       TREE_THIS_VOLATILE (t) = 1;
 401       DECL_ARTIFICIAL (t) = 1;
 402       DECL_IGNORED_P (t) = 1;
 403
 404       stack_chk_guard_decl = t;
 405     }
 406
 407   return t;
 408 }
 409
 410 static GTY(()) tree stack_chk_fail_decl;
 411
 412 tree
 413 default_external_stack_protect_fail (void)
 414 {
 415   tree t = stack_chk_fail_decl;
 416
 417   if (t == NULL_TREE)
 418     {
 419       t = build_function_type_list (void_type_node, NULL_TREE);
 420       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 421       TREE_STATIC (t) = 1;
 422       TREE_PUBLIC (t) = 1;
 423       DECL_EXTERNAL (t) = 1;
 424       TREE_USED (t) = 1;
 425       TREE_THIS_VOLATILE (t) = 1;
 426       TREE_NOTHROW (t) = 1;
 427       DECL_ARTIFICIAL (t) = 1;
 428       DECL_IGNORED_P (t) = 1;
 429       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 430       DECL_VISIBILITY_SPECIFIED (t) = 1;
 431
 432       stack_chk_fail_decl = t;
 433     }
 434
 435   return build_call_expr (t, 0);
 436 }
 437
 438 tree
 439 default_hidden_stack_protect_fail (void)
 440 {
 441 #ifndef HAVE_GAS_HIDDEN
 442   return default_external_stack_protect_fail ();
 443 #else
 444   tree t = stack_chk_fail_decl;
 445
 446   if (!flag_pic)
 447     return default_external_stack_protect_fail ();
 448
 449   if (t == NULL_TREE)
 450     {
 451       t = build_function_type_list (void_type_node, NULL_TREE);
 452       t = build_decl (FUNCTION_DECL,
 453                       get_identifier ("__stack_chk_fail_local"), t);
 454       TREE_STATIC (t) = 1;
 455       TREE_PUBLIC (t) = 1;
 456       DECL_EXTERNAL (t) = 1;
 457       TREE_USED (t) = 1;
 458       TREE_THIS_VOLATILE (t) = 1;
 459       TREE_NOTHROW (t) = 1;
 460       DECL_ARTIFICIAL (t) = 1;
 461       DECL_IGNORED_P (t) = 1;
 462       DECL_VISIBILITY_SPECIFIED (t) = 1;
 463       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 464
 465       stack_chk_fail_decl = t;
 466     }
 467
 468   return build_call_expr (t, 0);
 469 #endif
 470 }
 471
 472 bool
 473 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 474 {
 475   return COMMUTATIVE_P (x);
 476 }
 477
 478 rtx
 479 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 480                         tree fn_decl_or_type,
 481                         bool outgoing ATTRIBUTE_UNUSED)
 482 {
 483   /* The old interface doesn't handle receiving the function type.  */
 484   if (fn_decl_or_type
 485       && !DECL_P (fn_decl_or_type))
 486     fn_decl_or_type = NULL;
 487
 488 #ifdef FUNCTION_OUTGOING_VALUE
 489   if (outgoing)
 490     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 491 #endif
 492
 493 #ifdef FUNCTION_VALUE
 494   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 495 #else
 496   return NULL_RTX;
 497 #endif
 498 }
 499
 500 rtx
 501 default_internal_arg_pointer (void)
 502 {
 503   /* If the reg that the virtual arg pointer will be translated into is
 504      not a fixed reg or is the stack pointer, make a copy of the virtual
 505      arg pointer, and address parms via the copy.  The frame pointer is
 506      considered fixed even though it is not marked as such.  */
 507   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 508        || ! (fixed_regs[ARG_POINTER_REGNUM]
 509              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 510     return copy_to_reg (virtual_incoming_args_rtx);
 511   else
 512     return virtual_incoming_args_rtx;
 513 }
 514
 515 enum reg_class
 516 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 517                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 518                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 519                           secondary_reload_info *sri)
 520 {
 521   enum reg_class class = NO_REGS;
 522
 523   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 524     {
 525       sri->icode = sri->prev_sri->t_icode;
 526       return NO_REGS;
 527     }
 528 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 529   if (in_p)
 530     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 531 #endif
 532 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 533   if (! in_p)
 534     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 535 #endif
 536   if (class != NO_REGS)
 537     {
 538       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 539                               : reload_out_optab[(int) reload_mode]);
 540
 541       if (icode != CODE_FOR_nothing
 542           && insn_data[(int) icode].operand[in_p].predicate
 543           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 544         icode = CODE_FOR_nothing;
 545       else if (icode != CODE_FOR_nothing)
 546         {
 547           const char *insn_constraint, *scratch_constraint;
 548           char insn_letter, scratch_letter;
 549           enum reg_class insn_class, scratch_class;
 550
 551           gcc_assert (insn_data[(int) icode].n_operands == 3);
 552           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 553           if (!*insn_constraint)
 554             insn_class = ALL_REGS;
 555           else
 556             {
 557               if (in_p)
 558                 {
 559                   gcc_assert (*insn_constraint == '=');
 560                   insn_constraint++;
 561                 }
 562               insn_letter = *insn_constraint;
 563               insn_class
 564                 = (insn_letter == 'r' ? GENERAL_REGS
 565                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 566                                                 insn_constraint));
 567               gcc_assert (insn_class != NO_REGS);
 568             }
 569
 570           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 571           /* The scratch register's constraint must start with "=&",
 572              except for an input reload, where only "=" is necessary,
 573              and where it might be beneficial to re-use registers from
 574              the input.  */
 575           gcc_assert (scratch_constraint[0] == '='
 576                       && (in_p || scratch_constraint[1] == '&'));
 577           scratch_constraint++;
 578           if (*scratch_constraint == '&')
 579             scratch_constraint++;
 580           scratch_letter = *scratch_constraint;
 581           scratch_class
 582             = (scratch_letter == 'r' ? GENERAL_REGS
 583                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 584                                             scratch_constraint));
 585
 586           if (reg_class_subset_p (reload_class, insn_class))
 587             {
 588               gcc_assert (scratch_class == class);
 589               class = NO_REGS;
 590             }
 591           else
 592             class = insn_class;
 593
 594         }
 595       if (class == NO_REGS)
 596         sri->icode = icode;
 597       else
 598         sri->t_icode = icode;
 599     }
 600   return class;
 601 }
 602
 603
 604 /* If STRICT_ALIGNMENT is true we use the container type for accessing
 605    volatile bitfields.  This is generally the preferred behavior for memory
 606    mapped peripherals on RISC architectures.
 607    If STRICT_ALIGNMENT is false we use the narrowest type possible.  This
 608    is typically used to avoid spurious page faults and extra memory accesses
 609    due to unaligned accesses on CISC architectures.  */
 610
 611 bool
 612 default_narrow_bitfield (void)
 613 {
 614   return !STRICT_ALIGNMENT;
 615 }
 616
 617 #include "gt-targhooks.h"