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 bool
 323 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 324         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 325         enum machine_mode mode ATTRIBUTE_UNUSED,
 326         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 327 {
 328   return false;
 329 }
 330
 331 bool
 332 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 333         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 334         enum machine_mode mode ATTRIBUTE_UNUSED,
 335         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 336 {
 337   return true;
 338 }
 339
 340 int
 341 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 342         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 343         enum machine_mode mode ATTRIBUTE_UNUSED,
 344         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 345 {
 346   return 0;
 347 }
 348
 349 void
 350 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 351 {
 352 }
 353
 354 const char *
 355 hook_invalid_arg_for_unprototyped_fn (
 356         tree typelist ATTRIBUTE_UNUSED,
 357         tree funcdecl ATTRIBUTE_UNUSED,
 358         tree val ATTRIBUTE_UNUSED)
 359 {
 360   return NULL;
 361 }
 362
 363 /* Initialize the stack protection decls.  */
 364
 365 /* Stack protection related decls living in libgcc.  */
 366 static GTY(()) tree stack_chk_guard_decl;
 367
 368 tree
 369 default_stack_protect_guard (void)
 370 {
 371   tree t = stack_chk_guard_decl;
 372
 373   if (t == NULL)
 374     {
 375       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 376                       ptr_type_node);
 377       TREE_STATIC (t) = 1;
 378       TREE_PUBLIC (t) = 1;
 379       DECL_EXTERNAL (t) = 1;
 380       TREE_USED (t) = 1;
 381       TREE_THIS_VOLATILE (t) = 1;
 382       DECL_ARTIFICIAL (t) = 1;
 383       DECL_IGNORED_P (t) = 1;
 384
 385       stack_chk_guard_decl = t;
 386     }
 387
 388   return t;
 389 }
 390
 391 static GTY(()) tree stack_chk_fail_decl;
 392
 393 tree
 394 default_external_stack_protect_fail (void)
 395 {
 396   tree t = stack_chk_fail_decl;
 397
 398   if (t == NULL_TREE)
 399     {
 400       t = build_function_type_list (void_type_node, NULL_TREE);
 401       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 402       TREE_STATIC (t) = 1;
 403       TREE_PUBLIC (t) = 1;
 404       DECL_EXTERNAL (t) = 1;
 405       TREE_USED (t) = 1;
 406       TREE_THIS_VOLATILE (t) = 1;
 407       TREE_NOTHROW (t) = 1;
 408       DECL_ARTIFICIAL (t) = 1;
 409       DECL_IGNORED_P (t) = 1;
 410       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 411       DECL_VISIBILITY_SPECIFIED (t) = 1;
 412
 413       stack_chk_fail_decl = t;
 414     }
 415
 416   return build_function_call_expr (t, NULL_TREE);
 417 }
 418
 419 tree
 420 default_hidden_stack_protect_fail (void)
 421 {
 422 #ifndef HAVE_GAS_HIDDEN
 423   return default_external_stack_protect_fail ();
 424 #else
 425   tree t = stack_chk_fail_decl;
 426
 427   if (!flag_pic)
 428     return default_external_stack_protect_fail ();
 429
 430   if (t == NULL_TREE)
 431     {
 432       t = build_function_type_list (void_type_node, NULL_TREE);
 433       t = build_decl (FUNCTION_DECL,
 434                       get_identifier ("__stack_chk_fail_local"), t);
 435       TREE_STATIC (t) = 1;
 436       TREE_PUBLIC (t) = 1;
 437       DECL_EXTERNAL (t) = 1;
 438       TREE_USED (t) = 1;
 439       TREE_THIS_VOLATILE (t) = 1;
 440       TREE_NOTHROW (t) = 1;
 441       DECL_ARTIFICIAL (t) = 1;
 442       DECL_IGNORED_P (t) = 1;
 443       DECL_VISIBILITY_SPECIFIED (t) = 1;
 444       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 445
 446       stack_chk_fail_decl = t;
 447     }
 448
 449   return build_function_call_expr (t, NULL_TREE);
 450 #endif
 451 }
 452
 453 bool
 454 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 455 {
 456   return COMMUTATIVE_P (x);
 457 }
 458
 459 rtx
 460 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 461                         tree fn_decl_or_type,
 462                         bool outgoing ATTRIBUTE_UNUSED)
 463 {
 464   /* The old interface doesn't handle receiving the function type.  */
 465   if (fn_decl_or_type
 466       && !DECL_P (fn_decl_or_type))
 467     fn_decl_or_type = NULL;
 468
 469 #ifdef FUNCTION_OUTGOING_VALUE
 470   if (outgoing)
 471     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 472 #endif
 473
 474 #ifdef FUNCTION_VALUE
 475   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 476 #else
 477   return NULL_RTX;
 478 #endif
 479 }
 480
 481 rtx
 482 default_internal_arg_pointer (void)
 483 {
 484   /* If the reg that the virtual arg pointer will be translated into is
 485      not a fixed reg or is the stack pointer, make a copy of the virtual
 486      arg pointer, and address parms via the copy.  The frame pointer is
 487      considered fixed even though it is not marked as such.  */
 488   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 489        || ! (fixed_regs[ARG_POINTER_REGNUM]
 490              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 491     return copy_to_reg (virtual_incoming_args_rtx);
 492   else
 493     return virtual_incoming_args_rtx;
 494 }
 495
 496 enum reg_class
 497 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 498                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 499                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 500                           secondary_reload_info *sri)
 501 {
 502   enum reg_class class = NO_REGS;
 503
 504   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 505     {
 506       sri->icode = sri->prev_sri->t_icode;
 507       return NO_REGS;
 508     }
 509 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 510   if (in_p)
 511     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 512 #endif
 513 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 514   if (! in_p)
 515     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 516 #endif
 517   if (class != NO_REGS)
 518     {
 519       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 520                               : reload_out_optab[(int) reload_mode]);
 521
 522       if (icode != CODE_FOR_nothing
 523           && insn_data[(int) icode].operand[in_p].predicate
 524           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 525         icode = CODE_FOR_nothing;
 526       else if (icode != CODE_FOR_nothing)
 527         {
 528           const char *insn_constraint, *scratch_constraint;
 529           char insn_letter, scratch_letter;
 530           enum reg_class insn_class, scratch_class;
 531
 532           gcc_assert (insn_data[(int) icode].n_operands == 3);
 533           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 534           if (!*insn_constraint)
 535             insn_class = ALL_REGS;
 536           else
 537             {
 538               if (in_p)
 539                 {
 540                   gcc_assert (*insn_constraint == '=');
 541                   insn_constraint++;
 542                 }
 543               insn_letter = *insn_constraint;
 544               insn_class
 545                 = (insn_letter == 'r' ? GENERAL_REGS
 546                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 547                                                 insn_constraint));
 548               gcc_assert (insn_class != NO_REGS);
 549             }
 550
 551           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 552           /* The scratch register's constraint must start with "=&",
 553              except for an input reload, where only "=" is necessary,
 554              and where it might be beneficial to re-use registers from
 555              the input.  */
 556           gcc_assert (scratch_constraint[0] == '='
 557                       && (in_p || scratch_constraint[1] == '&'));
 558           scratch_constraint++;
 559           if (*scratch_constraint == '&')
 560             scratch_constraint++;
 561           scratch_letter = *scratch_constraint;
 562           scratch_class
 563             = (scratch_letter == 'r' ? GENERAL_REGS
 564                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 565                                             scratch_constraint));
 566
 567           if (reg_class_subset_p (reload_class, insn_class))
 568             {
 569               gcc_assert (scratch_class == class);
 570               class = NO_REGS;
 571             }
 572           else
 573             class = insn_class;
 574
 575         }
 576       if (class == NO_REGS)
 577         sri->icode = icode;
 578       else
 579         sri->t_icode = icode;
 580     }
 581   return class;
 582 }
 583
 584
 585 /* If STRICT_ALIGNMENT is true we use the container type for accessing
 586    volatile bitfields.  This is generally the preferred behavior for memory
 587    mapped peripherals on RISC architectures.
 588    If STRICT_ALIGNMENT is false we use the narrowest type possible.  This
 589    is typically used to avoid spurious page faults and extra memory accesses
 590    due to unaligned accesses on CISC architectures.  */
 591
 592 bool
 593 default_narrow_bitfield (void)
 594 {
 595   return !STRICT_ALIGNMENT;
 596 }
 597
 598 #include "gt-targhooks.h"