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 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 160
 161 bool
 162 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 163 {
 164   return true;
 165 }
 166
 167
 168 /* The generic C++ ABI specifies this is a 64-bit value.  */
 169 tree
 170 default_cxx_guard_type (void)
 171 {
 172   return long_long_integer_type_node;
 173 }
 174
 175
 176 /* Returns the size of the cookie to use when allocating an array
 177    whose elements have the indicated TYPE.  Assumes that it is already
 178    known that a cookie is needed.  */
 179
 180 tree
 181 default_cxx_get_cookie_size (tree type)
 182 {
 183   tree cookie_size;
 184
 185   /* We need to allocate an additional max (sizeof (size_t), alignof
 186      (true_type)) bytes.  */
 187   tree sizetype_size;
 188   tree type_align;
 189
 190   sizetype_size = size_in_bytes (sizetype);
 191   type_align = size_int (TYPE_ALIGN_UNIT (type));
 192   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 193     cookie_size = sizetype_size;
 194   else
 195     cookie_size = type_align;
 196
 197   return cookie_size;
 198 }
 199
 200 /* Return true if a parameter must be passed by reference.  This version
 201    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 202
 203 bool
 204 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 205         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 206         bool named_arg ATTRIBUTE_UNUSED)
 207 {
 208   return targetm.calls.must_pass_in_stack (mode, type);
 209 }
 210
 211 /* Return true if a parameter follows callee copies conventions.  This
 212    version of the hook is true for all named arguments.  */
 213
 214 bool
 215 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 216                           enum machine_mode mode ATTRIBUTE_UNUSED,
 217                           tree type ATTRIBUTE_UNUSED, bool named)
 218 {
 219   return named;
 220 }
 221
 222 /* Emit any directives required to unwind this instruction.  */
 223
 224 void
 225 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 226                      rtx insn ATTRIBUTE_UNUSED)
 227 {
 228   /* Should never happen.  */
 229   gcc_unreachable ();
 230 }
 231
 232 /* True if MODE is valid for the target.  By "valid", we mean able to
 233    be manipulated in non-trivial ways.  In particular, this means all
 234    the arithmetic is supported.
 235
 236    By default we guess this means that any C type is supported.  If
 237    we can't map the mode back to a type that would be available in C,
 238    then reject it.  Special case, here, is the double-word arithmetic
 239    supported by optabs.c.  */
 240
 241 bool
 242 default_scalar_mode_supported_p (enum machine_mode mode)
 243 {
 244   int precision = GET_MODE_PRECISION (mode);
 245
 246   switch (GET_MODE_CLASS (mode))
 247     {
 248     case MODE_PARTIAL_INT:
 249     case MODE_INT:
 250       if (precision == CHAR_TYPE_SIZE)
 251         return true;
 252       if (precision == SHORT_TYPE_SIZE)
 253         return true;
 254       if (precision == INT_TYPE_SIZE)
 255         return true;
 256       if (precision == LONG_TYPE_SIZE)
 257         return true;
 258       if (precision == LONG_LONG_TYPE_SIZE)
 259         return true;
 260       if (precision == 2 * BITS_PER_WORD)
 261         return true;
 262       return false;
 263
 264     case MODE_FLOAT:
 265       if (precision == FLOAT_TYPE_SIZE)
 266         return true;
 267       if (precision == DOUBLE_TYPE_SIZE)
 268         return true;
 269       if (precision == LONG_DOUBLE_TYPE_SIZE)
 270         return true;
 271       return false;
 272
 273     case MODE_DECIMAL_FLOAT:
 274       return false;
 275
 276     default:
 277       gcc_unreachable ();
 278     }
 279 }
 280
 281 /* True if the target supports decimal floating point.  */
 282
 283 bool
 284 default_decimal_float_supported_p (void)
 285 {
 286   return ENABLE_DECIMAL_FLOAT;
 287 }
 288
 289 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 290    an error message.
 291
 292    This function checks whether a given INSN is valid within a low-overhead
 293    loop.  If INSN is invalid it returns the reason for that, otherwise it
 294    returns NULL. A called function may clobber any special registers required
 295    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 296    register for branch on table instructions. We reject the doloop pattern in
 297    these cases.  */
 298
 299 const char *
 300 default_invalid_within_doloop (rtx insn)
 301 {
 302   if (CALL_P (insn))
 303     return "Function call in loop.";
 304
 305   if (JUMP_P (insn)
 306       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 307           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 308     return "Computed branch in the loop.";
 309
 310   return NULL;
 311 }
 312
 313 bool
 314 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 315         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 316         enum machine_mode mode ATTRIBUTE_UNUSED,
 317         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 318 {
 319   return false;
 320 }
 321
 322 bool
 323 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 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 true;
 329 }
 330
 331 int
 332 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 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 0;
 338 }
 339
 340 void
 341 hook_void_bitmap (bitmap regs ATTRIBUTE_UNUSED)
 342 {
 343 }
 344
 345 const char *
 346 hook_invalid_arg_for_unprototyped_fn (
 347         tree typelist ATTRIBUTE_UNUSED,
 348         tree funcdecl ATTRIBUTE_UNUSED,
 349         tree val ATTRIBUTE_UNUSED)
 350 {
 351   return NULL;
 352 }
 353
 354 /* Initialize the stack protection decls.  */
 355
 356 /* Stack protection related decls living in libgcc.  */
 357 static GTY(()) tree stack_chk_guard_decl;
 358
 359 tree
 360 default_stack_protect_guard (void)
 361 {
 362   tree t = stack_chk_guard_decl;
 363
 364   if (t == NULL)
 365     {
 366       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 367                       ptr_type_node);
 368       TREE_STATIC (t) = 1;
 369       TREE_PUBLIC (t) = 1;
 370       DECL_EXTERNAL (t) = 1;
 371       TREE_USED (t) = 1;
 372       TREE_THIS_VOLATILE (t) = 1;
 373       DECL_ARTIFICIAL (t) = 1;
 374       DECL_IGNORED_P (t) = 1;
 375
 376       stack_chk_guard_decl = t;
 377     }
 378
 379   return t;
 380 }
 381
 382 static GTY(()) tree stack_chk_fail_decl;
 383
 384 tree
 385 default_external_stack_protect_fail (void)
 386 {
 387   tree t = stack_chk_fail_decl;
 388
 389   if (t == NULL_TREE)
 390     {
 391       t = build_function_type_list (void_type_node, NULL_TREE);
 392       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 393       TREE_STATIC (t) = 1;
 394       TREE_PUBLIC (t) = 1;
 395       DECL_EXTERNAL (t) = 1;
 396       TREE_USED (t) = 1;
 397       TREE_THIS_VOLATILE (t) = 1;
 398       TREE_NOTHROW (t) = 1;
 399       DECL_ARTIFICIAL (t) = 1;
 400       DECL_IGNORED_P (t) = 1;
 401       DECL_VISIBILITY (t) = VISIBILITY_DEFAULT;
 402       DECL_VISIBILITY_SPECIFIED (t) = 1;
 403
 404       stack_chk_fail_decl = t;
 405     }
 406
 407   return build_function_call_expr (t, NULL_TREE);
 408 }
 409
 410 tree
 411 default_hidden_stack_protect_fail (void)
 412 {
 413 #ifndef HAVE_GAS_HIDDEN
 414   return default_external_stack_protect_fail ();
 415 #else
 416   tree t = stack_chk_fail_decl;
 417
 418   if (!flag_pic)
 419     return default_external_stack_protect_fail ();
 420
 421   if (t == NULL_TREE)
 422     {
 423       t = build_function_type_list (void_type_node, NULL_TREE);
 424       t = build_decl (FUNCTION_DECL,
 425                       get_identifier ("__stack_chk_fail_local"), t);
 426       TREE_STATIC (t) = 1;
 427       TREE_PUBLIC (t) = 1;
 428       DECL_EXTERNAL (t) = 1;
 429       TREE_USED (t) = 1;
 430       TREE_THIS_VOLATILE (t) = 1;
 431       TREE_NOTHROW (t) = 1;
 432       DECL_ARTIFICIAL (t) = 1;
 433       DECL_IGNORED_P (t) = 1;
 434       DECL_VISIBILITY_SPECIFIED (t) = 1;
 435       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 436
 437       stack_chk_fail_decl = t;
 438     }
 439
 440   return build_function_call_expr (t, NULL_TREE);
 441 #endif
 442 }
 443
 444 bool
 445 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 446 {
 447   return COMMUTATIVE_P (x);
 448 }
 449
 450 rtx
 451 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 452                         tree fn_decl_or_type,
 453                         bool outgoing ATTRIBUTE_UNUSED)
 454 {
 455   /* The old interface doesn't handle receiving the function type.  */
 456   if (fn_decl_or_type
 457       && !DECL_P (fn_decl_or_type))
 458     fn_decl_or_type = NULL;
 459
 460 #ifdef FUNCTION_OUTGOING_VALUE
 461   if (outgoing)
 462     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 463 #endif
 464
 465 #ifdef FUNCTION_VALUE
 466   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 467 #else
 468   return NULL_RTX;
 469 #endif
 470 }
 471
 472 rtx
 473 default_internal_arg_pointer (void)
 474 {
 475   /* If the reg that the virtual arg pointer will be translated into is
 476      not a fixed reg or is the stack pointer, make a copy of the virtual
 477      arg pointer, and address parms via the copy.  The frame pointer is
 478      considered fixed even though it is not marked as such.  */
 479   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 480        || ! (fixed_regs[ARG_POINTER_REGNUM]
 481              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 482     return copy_to_reg (virtual_incoming_args_rtx);
 483   else
 484     return virtual_incoming_args_rtx;
 485 }
 486
 487 enum reg_class
 488 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 489                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 490                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 491                           secondary_reload_info *sri)
 492 {
 493   enum reg_class class = NO_REGS;
 494
 495   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 496     {
 497       sri->icode = sri->prev_sri->t_icode;
 498       return NO_REGS;
 499     }
 500 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 501   if (in_p)
 502     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 503 #endif
 504 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 505   if (! in_p)
 506     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 507 #endif
 508   if (class != NO_REGS)
 509     {
 510       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 511                               : reload_out_optab[(int) reload_mode]);
 512
 513       if (icode != CODE_FOR_nothing
 514           && insn_data[(int) icode].operand[in_p].predicate
 515           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 516         icode = CODE_FOR_nothing;
 517       else if (icode != CODE_FOR_nothing)
 518         {
 519           const char *insn_constraint, *scratch_constraint;
 520           char insn_letter, scratch_letter;
 521           enum reg_class insn_class, scratch_class;
 522
 523           gcc_assert (insn_data[(int) icode].n_operands == 3);
 524           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 525           if (!*insn_constraint)
 526             insn_class = ALL_REGS;
 527           else
 528             {
 529               if (in_p)
 530                 {
 531                   gcc_assert (*insn_constraint == '=');
 532                   insn_constraint++;
 533                 }
 534               insn_letter = *insn_constraint;
 535               insn_class
 536                 = (insn_letter == 'r' ? GENERAL_REGS
 537                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 538                                                 insn_constraint));
 539               gcc_assert (insn_class != NO_REGS);
 540             }
 541
 542           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 543           /* The scratch register's constraint must start with "=&",
 544              except for an input reload, where only "=" is necessary,
 545              and where it might be beneficial to re-use registers from
 546              the input.  */
 547           gcc_assert (scratch_constraint[0] == '='
 548                       && (in_p || scratch_constraint[1] == '&'));
 549           scratch_constraint++;
 550           if (*scratch_constraint == '&')
 551             scratch_constraint++;
 552           scratch_letter = *scratch_constraint;
 553           scratch_class
 554             = (scratch_letter == 'r' ? GENERAL_REGS
 555                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 556                                             scratch_constraint));
 557
 558           if (reg_class_subset_p (reload_class, insn_class))
 559             {
 560               gcc_assert (scratch_class == class);
 561               class = NO_REGS;
 562             }
 563           else
 564             class = insn_class;
 565
 566         }
 567       if (class == NO_REGS)
 568         sri->icode = icode;
 569       else
 570         sri->t_icode = icode;
 571     }
 572   return class;
 573 }
 574
 575
 576 /* If STRICT_ALIGNMENT is true we use the container type for accessing
 577    volatile bitfields.  This is generally the preferred behavior for memory
 578    mapped peripherals on RISC architectures.
 579    If STRICT_ALIGNMENT is false we use the narrowest type possible.  This
 580    is typically used to avoid spurious page faults and extra memory accesses
 581    due to unaligned accesses on CISC architectures.  */
 582
 583 bool
 584 default_narrow_bitfield (void)
 585 {
 586   return !STRICT_ALIGNMENT;
 587 }
 588
 589 #include "gt-targhooks.h"