gcc/targhooks.c

   1 /* Default target hook functions.
   2    Copyright (C) 2003, 2004, 2005, 2007 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 3, 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 COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 /* The migration of target macros to target hooks works as follows:
  21
  22    1. Create a target hook that uses the existing target macros to
  23       implement the same functionality.
  24
  25    2. Convert all the MI files to use the hook instead of the macro.
  26
  27    3. Repeat for a majority of the remaining target macros.  This will
  28       take some time.
  29
  30    4. Tell target maintainers to start migrating.
  31
  32    5. Eventually convert the backends to override the hook instead of
  33       defining the macros.  This will take some time too.
  34
  35    6. TBD when, poison the macros.  Unmigrated targets will break at
  36       this point.
  37
  38    Note that we expect steps 1-3 to be done by the people that
  39    understand what the MI does with each macro, and step 5 to be done
  40    by the target maintainers for their respective targets.
  41
  42    Note that steps 1 and 2 don't have to be done together, but no
  43    target can override the new hook until step 2 is complete for it.
  44
  45    Once the macros are poisoned, we will revert to the old migration
  46    rules - migrate the macro, callers, and targets all at once.  This
  47    comment can thus be removed at that point.  */
  48
  49 #include "config.h"
  50 #include "system.h"
  51 #include "coretypes.h"
  52 #include "tm.h"
  53 #include "machmode.h"
  54 #include "rtl.h"
  55 #include "tree.h"
  56 #include "expr.h"
  57 #include "output.h"
  58 #include "toplev.h"
  59 #include "function.h"
  60 #include "target.h"
  61 #include "tm_p.h"
  62 #include "target-def.h"
  63 #include "ggc.h"
  64 #include "hard-reg-set.h"
  65 #include "reload.h"
  66 #include "optabs.h"
  67 #include "recog.h"
  68
  69
  70 void
  71 default_external_libcall (rtx fun ATTRIBUTE_UNUSED)
  72 {
  73 #ifdef ASM_OUTPUT_EXTERNAL_LIBCALL
  74   ASM_OUTPUT_EXTERNAL_LIBCALL(asm_out_file, fun);
  75 #endif
  76 }
  77
  78 enum machine_mode
  79 default_cc_modes_compatible (enum machine_mode m1, enum machine_mode m2)
  80 {
  81   if (m1 == m2)
  82     return m1;
  83   return VOIDmode;
  84 }
  85
  86 bool
  87 default_return_in_memory (tree type,
  88                           tree fntype ATTRIBUTE_UNUSED)
  89 {
  90 #ifndef RETURN_IN_MEMORY
  91   return (TYPE_MODE (type) == BLKmode);
  92 #else
  93   return RETURN_IN_MEMORY (type);
  94 #endif
  95 }
  96
  97 rtx
  98 default_expand_builtin_saveregs (void)
  99 {
 100   error ("__builtin_saveregs not supported by this target");
 101   return const0_rtx;
 102 }
 103
 104 void
 105 default_setup_incoming_varargs (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 106                                 enum machine_mode mode ATTRIBUTE_UNUSED,
 107                                 tree type ATTRIBUTE_UNUSED,
 108                                 int *pretend_arg_size ATTRIBUTE_UNUSED,
 109                                 int second_time ATTRIBUTE_UNUSED)
 110 {
 111 }
 112
 113 /* The default implementation of TARGET_BUILTIN_SETJMP_FRAME_VALUE.  */
 114
 115 rtx
 116 default_builtin_setjmp_frame_value (void)
 117 {
 118   return virtual_stack_vars_rtx;
 119 }
 120
 121 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns false.  */
 122
 123 bool
 124 hook_bool_CUMULATIVE_ARGS_false (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 125 {
 126   return false;
 127 }
 128
 129 bool
 130 default_pretend_outgoing_varargs_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED)
 131 {
 132   return (targetm.calls.setup_incoming_varargs
 133           != default_setup_incoming_varargs);
 134 }
 135
 136 enum machine_mode
 137 default_eh_return_filter_mode (void)
 138 {
 139   return word_mode;
 140 }
 141
 142 /* The default implementation of TARGET_SHIFT_TRUNCATION_MASK.  */
 143
 144 unsigned HOST_WIDE_INT
 145 default_shift_truncation_mask (enum machine_mode mode)
 146 {
 147   return SHIFT_COUNT_TRUNCATED ? GET_MODE_BITSIZE (mode) - 1 : 0;
 148 }
 149
 150 /* The default implementation of TARGET_MIN_DIVISIONS_FOR_RECIP_MUL.  */
 151
 152 unsigned int
 153 default_min_divisions_for_recip_mul (enum machine_mode mode ATTRIBUTE_UNUSED)
 154 {
 155   return have_insn_for (DIV, mode) ? 3 : 2;
 156 }
 157
 158 /* The default implementation of TARGET_MODE_REP_EXTENDED.  */
 159
 160 int
 161 default_mode_rep_extended (enum machine_mode mode ATTRIBUTE_UNUSED,
 162                            enum machine_mode mode_rep ATTRIBUTE_UNUSED)
 163 {
 164   return UNKNOWN;
 165 }
 166
 167 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 168
 169 bool
 170 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 171 {
 172   return true;
 173 }
 174
 175
 176 /* The generic C++ ABI specifies this is a 64-bit value.  */
 177 tree
 178 default_cxx_guard_type (void)
 179 {
 180   return long_long_integer_type_node;
 181 }
 182
 183
 184 /* Returns the size of the cookie to use when allocating an array
 185    whose elements have the indicated TYPE.  Assumes that it is already
 186    known that a cookie is needed.  */
 187
 188 tree
 189 default_cxx_get_cookie_size (tree type)
 190 {
 191   tree cookie_size;
 192
 193   /* We need to allocate an additional max (sizeof (size_t), alignof
 194      (true_type)) bytes.  */
 195   tree sizetype_size;
 196   tree type_align;
 197
 198   sizetype_size = size_in_bytes (sizetype);
 199   type_align = size_int (TYPE_ALIGN_UNIT (type));
 200   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 201     cookie_size = sizetype_size;
 202   else
 203     cookie_size = type_align;
 204
 205   return cookie_size;
 206 }
 207
 208 /* Return true if a parameter must be passed by reference.  This version
 209    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 210
 211 bool
 212 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 213         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 214         bool named_arg ATTRIBUTE_UNUSED)
 215 {
 216   return targetm.calls.must_pass_in_stack (mode, type);
 217 }
 218
 219 /* Return true if a parameter follows callee copies conventions.  This
 220    version of the hook is true for all named arguments.  */
 221
 222 bool
 223 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 224                           enum machine_mode mode ATTRIBUTE_UNUSED,
 225                           tree type ATTRIBUTE_UNUSED, bool named)
 226 {
 227   return named;
 228 }
 229
 230 /* Emit any directives required to unwind this instruction.  */
 231
 232 void
 233 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 234                      rtx insn ATTRIBUTE_UNUSED)
 235 {
 236   /* Should never happen.  */
 237   gcc_unreachable ();
 238 }
 239
 240 /* True if MODE is valid for the target.  By "valid", we mean able to
 241    be manipulated in non-trivial ways.  In particular, this means all
 242    the arithmetic is supported.
 243
 244    By default we guess this means that any C type is supported.  If
 245    we can't map the mode back to a type that would be available in C,
 246    then reject it.  Special case, here, is the double-word arithmetic
 247    supported by optabs.c.  */
 248
 249 bool
 250 default_scalar_mode_supported_p (enum machine_mode mode)
 251 {
 252   int precision = GET_MODE_PRECISION (mode);
 253
 254   switch (GET_MODE_CLASS (mode))
 255     {
 256     case MODE_PARTIAL_INT:
 257     case MODE_INT:
 258       if (precision == CHAR_TYPE_SIZE)
 259         return true;
 260       if (precision == SHORT_TYPE_SIZE)
 261         return true;
 262       if (precision == INT_TYPE_SIZE)
 263         return true;
 264       if (precision == LONG_TYPE_SIZE)
 265         return true;
 266       if (precision == LONG_LONG_TYPE_SIZE)
 267         return true;
 268       if (precision == 2 * BITS_PER_WORD)
 269         return true;
 270       return false;
 271
 272     case MODE_FLOAT:
 273       if (precision == FLOAT_TYPE_SIZE)
 274         return true;
 275       if (precision == DOUBLE_TYPE_SIZE)
 276         return true;
 277       if (precision == LONG_DOUBLE_TYPE_SIZE)
 278         return true;
 279       return false;
 280
 281     case MODE_DECIMAL_FLOAT:
 282       return false;
 283
 284     default:
 285       gcc_unreachable ();
 286     }
 287 }
 288
 289 /* True if the target supports decimal floating point.  */
 290
 291 bool
 292 default_decimal_float_supported_p (void)
 293 {
 294   return ENABLE_DECIMAL_FLOAT;
 295 }
 296
 297 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 298    an error message.
 299
 300    This function checks whether a given INSN is valid within a low-overhead
 301    loop.  If INSN is invalid it returns the reason for that, otherwise it
 302    returns NULL. A called function may clobber any special registers required
 303    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 304    register for branch on table instructions. We reject the doloop pattern in
 305    these cases.  */
 306
 307 const char *
 308 default_invalid_within_doloop (rtx insn)
 309 {
 310   if (CALL_P (insn))
 311     return "Function call in loop.";
 312
 313   if (JUMP_P (insn)
 314       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 315           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 316     return "Computed branch in the loop.";
 317
 318   return NULL;
 319 }
 320
 321 bool
 322 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 323         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 324         enum machine_mode mode ATTRIBUTE_UNUSED,
 325         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 326 {
 327   return false;
 328 }
 329
 330 bool
 331 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 332         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 333         enum machine_mode mode ATTRIBUTE_UNUSED,
 334         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 335 {
 336   return true;
 337 }
 338
 339 int
 340 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 341         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 342         enum machine_mode mode ATTRIBUTE_UNUSED,
 343         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 344 {
 345   return 0;
 346 }
 347
 348 void
 349 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 350 {
 351 }
 352
 353 const char *
 354 hook_invalid_arg_for_unprototyped_fn (
 355         tree typelist ATTRIBUTE_UNUSED,
 356         tree funcdecl ATTRIBUTE_UNUSED,
 357         tree val ATTRIBUTE_UNUSED)
 358 {
 359   return NULL;
 360 }
 361
 362 /* Initialize the stack protection decls.  */
 363
 364 /* Stack protection related decls living in libgcc.  */
 365 static GTY(()) tree stack_chk_guard_decl;
 366
 367 tree
 368 default_stack_protect_guard (void)
 369 {
 370   tree t = stack_chk_guard_decl;
 371
 372   if (t == NULL)
 373     {
 374       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 375                       ptr_type_node);
 376       TREE_STATIC (t) = 1;
 377       TREE_PUBLIC (t) = 1;
 378       DECL_EXTERNAL (t) = 1;
 379       TREE_USED (t) = 1;
 380       TREE_THIS_VOLATILE (t) = 1;
 381       DECL_ARTIFICIAL (t) = 1;
 382       DECL_IGNORED_P (t) = 1;
 383
 384       stack_chk_guard_decl = t;
 385     }
 386
 387   return t;
 388 }
 389
 390 static GTY(()) tree stack_chk_fail_decl;
 391
 392 tree
 393 default_external_stack_protect_fail (void)
 394 {
 395   tree t = stack_chk_fail_decl;
 396
 397   if (t == NULL_TREE)
 398     {
 399       t = build_function_type_list (void_type_node, NULL_TREE);
 400       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 401       TREE_STATIC (t) = 1;
 402       TREE_PUBLIC (t) = 1;
 403       DECL_EXTERNAL (t) = 1;
 404       TREE_USED (t) = 1;
 405       TREE_THIS_VOLATILE (t) = 1;
 406       TREE_NOTHROW (t) = 1;
 407       DECL_ARTIFICIAL (t) = 1;
 408       DECL_IGNORED_P (t) = 1;
 409       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 410       DECL_VISIBILITY_SPECIFIED (t) = 1;
 411
 412       stack_chk_fail_decl = t;
 413     }
 414
 415   return build_function_call_expr (t, NULL_TREE);
 416 }
 417
 418 tree
 419 default_hidden_stack_protect_fail (void)
 420 {
 421 #ifndef HAVE_GAS_HIDDEN
 422   return default_external_stack_protect_fail ();
 423 #else
 424   tree t = stack_chk_fail_decl;
 425
 426   if (!flag_pic)
 427     return default_external_stack_protect_fail ();
 428
 429   if (t == NULL_TREE)
 430     {
 431       t = build_function_type_list (void_type_node, NULL_TREE);
 432       t = build_decl (FUNCTION_DECL,
 433                       get_identifier ("__stack_chk_fail_local"), t);
 434       TREE_STATIC (t) = 1;
 435       TREE_PUBLIC (t) = 1;
 436       DECL_EXTERNAL (t) = 1;
 437       TREE_USED (t) = 1;
 438       TREE_THIS_VOLATILE (t) = 1;
 439       TREE_NOTHROW (t) = 1;
 440       DECL_ARTIFICIAL (t) = 1;
 441       DECL_IGNORED_P (t) = 1;
 442       DECL_VISIBILITY_SPECIFIED (t) = 1;
 443       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 444
 445       stack_chk_fail_decl = t;
 446     }
 447
 448   return build_function_call_expr (t, NULL_TREE);
 449 #endif
 450 }
 451
 452 bool
 453 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 454 {
 455   return COMMUTATIVE_P (x);
 456 }
 457
 458 rtx
 459 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 460                         tree fn_decl_or_type,
 461                         bool outgoing ATTRIBUTE_UNUSED)
 462 {
 463   /* The old interface doesn't handle receiving the function type.  */
 464   if (fn_decl_or_type
 465       && !DECL_P (fn_decl_or_type))
 466     fn_decl_or_type = NULL;
 467
 468 #ifdef FUNCTION_OUTGOING_VALUE
 469   if (outgoing)
 470     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 471 #endif
 472
 473 #ifdef FUNCTION_VALUE
 474   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 475 #else
 476   return NULL_RTX;
 477 #endif
 478 }
 479
 480 rtx
 481 default_internal_arg_pointer (void)
 482 {
 483   /* If the reg that the virtual arg pointer will be translated into is
 484      not a fixed reg or is the stack pointer, make a copy of the virtual
 485      arg pointer, and address parms via the copy.  The frame pointer is
 486      considered fixed even though it is not marked as such.  */
 487   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 488        || ! (fixed_regs[ARG_POINTER_REGNUM]
 489              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 490     return copy_to_reg (virtual_incoming_args_rtx);
 491   else
 492     return virtual_incoming_args_rtx;
 493 }
 494
 495 enum reg_class
 496 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 497                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 498                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 499                           secondary_reload_info *sri)
 500 {
 501   enum reg_class class = NO_REGS;
 502
 503   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 504     {
 505       sri->icode = sri->prev_sri->t_icode;
 506       return NO_REGS;
 507     }
 508 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 509   if (in_p)
 510     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 511 #endif
 512 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 513   if (! in_p)
 514     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 515 #endif
 516   if (class != NO_REGS)
 517     {
 518       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 519                               : reload_out_optab[(int) reload_mode]);
 520
 521       if (icode != CODE_FOR_nothing
 522           && insn_data[(int) icode].operand[in_p].predicate
 523           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 524         icode = CODE_FOR_nothing;
 525       else if (icode != CODE_FOR_nothing)
 526         {
 527           const char *insn_constraint, *scratch_constraint;
 528           char insn_letter, scratch_letter;
 529           enum reg_class insn_class, scratch_class;
 530
 531           gcc_assert (insn_data[(int) icode].n_operands == 3);
 532           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 533           if (!*insn_constraint)
 534             insn_class = ALL_REGS;
 535           else
 536             {
 537               if (in_p)
 538                 {
 539                   gcc_assert (*insn_constraint == '=');
 540                   insn_constraint++;
 541                 }
 542               insn_letter = *insn_constraint;
 543               insn_class
 544                 = (insn_letter == 'r' ? GENERAL_REGS
 545                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 546                                                 insn_constraint));
 547               gcc_assert (insn_class != NO_REGS);
 548             }
 549
 550           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 551           /* The scratch register's constraint must start with "=&",
 552              except for an input reload, where only "=" is necessary,
 553              and where it might be beneficial to re-use registers from
 554              the input.  */
 555           gcc_assert (scratch_constraint[0] == '='
 556                       && (in_p || scratch_constraint[1] == '&'));
 557           scratch_constraint++;
 558           if (*scratch_constraint == '&')
 559             scratch_constraint++;
 560           scratch_letter = *scratch_constraint;
 561           scratch_class
 562             = (scratch_letter == 'r' ? GENERAL_REGS
 563                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 564                                             scratch_constraint));
 565
 566           if (reg_class_subset_p (reload_class, insn_class))
 567             {
 568               gcc_assert (scratch_class == class);
 569               class = NO_REGS;
 570             }
 571           else
 572             class = insn_class;
 573
 574         }
 575       if (class == NO_REGS)
 576         sri->icode = icode;
 577       else
 578         sri->t_icode = icode;
 579     }
 580   return class;
 581 }
 582
 583
 584 /* If STRICT_ALIGNMENT is true we use the container type for accessing
 585    volatile bitfields.  This is generally the preferred behavior for memory
 586    mapped peripherals on RISC architectures.
 587    If STRICT_ALIGNMENT is false we use the narrowest type possible.  This
 588    is typically used to avoid spurious page faults and extra memory accesses
 589    due to unaligned accesses on CISC architectures.  */
 590
 591 bool
 592 default_narrow_bitfield (void)
 593 {
 594   return !STRICT_ALIGNMENT;
 595 }
 596
 597 /* By default, if flag_pic is true, then neither local nor global relocs
 598    should be placed in readonly memory.  */
 599
 600 int
 601 default_reloc_rw_mask (void)
 602 {
 603   return flag_pic ? 3 : 0;
 604 }
 605
 606 bool
 607 default_builtin_vector_alignment_reachable (tree type, bool is_packed)
 608 {
 609   if (is_packed)
 610     return false;
 611
 612   /* Assuming that types whose size is > pointer-size are not guaranteed to be
 613      naturally aligned.  */
 614   if (tree_int_cst_compare (TYPE_SIZE (type), bitsize_int (POINTER_SIZE)) > 0)
 615     return false;
 616
 617   /* Assuming that types whose size is <= pointer-size
 618      are naturally aligned.  */
 619   return true;
 620 }
 621
 622 #include "gt-targhooks.h"