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 /* Generic hook that takes a CUMULATIVE_ARGS pointer and returns true.  */
 152
 153 bool
 154 hook_bool_CUMULATIVE_ARGS_true (CUMULATIVE_ARGS * a ATTRIBUTE_UNUSED)
 155 {
 156   return true;
 157 }
 158
 159
 160 /* The generic C++ ABI specifies this is a 64-bit value.  */
 161 tree
 162 default_cxx_guard_type (void)
 163 {
 164   return long_long_integer_type_node;
 165 }
 166
 167
 168 /* Returns the size of the cookie to use when allocating an array
 169    whose elements have the indicated TYPE.  Assumes that it is already
 170    known that a cookie is needed.  */
 171
 172 tree
 173 default_cxx_get_cookie_size (tree type)
 174 {
 175   tree cookie_size;
 176
 177   /* We need to allocate an additional max (sizeof (size_t), alignof
 178      (true_type)) bytes.  */
 179   tree sizetype_size;
 180   tree type_align;
 181
 182   sizetype_size = size_in_bytes (sizetype);
 183   type_align = size_int (TYPE_ALIGN_UNIT (type));
 184   if (INT_CST_LT_UNSIGNED (type_align, sizetype_size))
 185     cookie_size = sizetype_size;
 186   else
 187     cookie_size = type_align;
 188
 189   return cookie_size;
 190 }
 191
 192 /* Return true if a parameter must be passed by reference.  This version
 193    of the TARGET_PASS_BY_REFERENCE hook uses just MUST_PASS_IN_STACK.  */
 194
 195 bool
 196 hook_pass_by_reference_must_pass_in_stack (CUMULATIVE_ARGS *c ATTRIBUTE_UNUSED,
 197         enum machine_mode mode ATTRIBUTE_UNUSED, tree type ATTRIBUTE_UNUSED,
 198         bool named_arg ATTRIBUTE_UNUSED)
 199 {
 200   return targetm.calls.must_pass_in_stack (mode, type);
 201 }
 202
 203 /* Return true if a parameter follows callee copies conventions.  This
 204    version of the hook is true for all named arguments.  */
 205
 206 bool
 207 hook_callee_copies_named (CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 208                           enum machine_mode mode ATTRIBUTE_UNUSED,
 209                           tree type ATTRIBUTE_UNUSED, bool named)
 210 {
 211   return named;
 212 }
 213
 214 /* Emit any directives required to unwind this instruction.  */
 215
 216 void
 217 default_unwind_emit (FILE * stream ATTRIBUTE_UNUSED,
 218                      rtx insn ATTRIBUTE_UNUSED)
 219 {
 220   /* Should never happen.  */
 221   gcc_unreachable ();
 222 }
 223
 224 /* True if MODE is valid for the target.  By "valid", we mean able to
 225    be manipulated in non-trivial ways.  In particular, this means all
 226    the arithmetic is supported.
 227
 228    By default we guess this means that any C type is supported.  If
 229    we can't map the mode back to a type that would be available in C,
 230    then reject it.  Special case, here, is the double-word arithmetic
 231    supported by optabs.c.  */
 232
 233 bool
 234 default_scalar_mode_supported_p (enum machine_mode mode)
 235 {
 236   int precision = GET_MODE_PRECISION (mode);
 237
 238   switch (GET_MODE_CLASS (mode))
 239     {
 240     case MODE_PARTIAL_INT:
 241     case MODE_INT:
 242       if (precision == CHAR_TYPE_SIZE)
 243         return true;
 244       if (precision == SHORT_TYPE_SIZE)
 245         return true;
 246       if (precision == INT_TYPE_SIZE)
 247         return true;
 248       if (precision == LONG_TYPE_SIZE)
 249         return true;
 250       if (precision == LONG_LONG_TYPE_SIZE)
 251         return true;
 252       if (precision == 2 * BITS_PER_WORD)
 253         return true;
 254       return false;
 255
 256     case MODE_FLOAT:
 257       if (precision == FLOAT_TYPE_SIZE)
 258         return true;
 259       if (precision == DOUBLE_TYPE_SIZE)
 260         return true;
 261       if (precision == LONG_DOUBLE_TYPE_SIZE)
 262         return true;
 263       return false;
 264
 265     case MODE_DECIMAL_FLOAT:
 266       return false;
 267
 268     default:
 269       gcc_unreachable ();
 270     }
 271 }
 272
 273 /* True if the target supports decimal floating point.  */
 274
 275 bool
 276 default_decimal_float_supported_p (void)
 277 {
 278   return ENABLE_DECIMAL_FLOAT;
 279 }
 280
 281 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 282    an error message.
 283
 284    This function checks whether a given INSN is valid within a low-overhead
 285    loop.  If INSN is invalid it returns the reason for that, otherwise it
 286    returns NULL. A called function may clobber any special registers required
 287    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 288    register for branch on table instructions. We reject the doloop pattern in
 289    these cases.  */
 290
 291 const char *
 292 default_invalid_within_doloop (rtx insn)
 293 {
 294   if (CALL_P (insn))
 295     return "Function call in loop.";
 296
 297   if (JUMP_P (insn)
 298       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 299           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 300     return "Computed branch in the loop.";
 301
 302   return NULL;
 303 }
 304
 305 bool
 306 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 307         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 308         enum machine_mode mode ATTRIBUTE_UNUSED,
 309         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 310 {
 311   return false;
 312 }
 313
 314 bool
 315 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 316         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 317         enum machine_mode mode ATTRIBUTE_UNUSED,
 318         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 319 {
 320   return true;
 321 }
 322
 323 int
 324 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 325         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 326         enum machine_mode mode ATTRIBUTE_UNUSED,
 327         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 328 {
 329   return 0;
 330 }
 331
 332 const char *
 333 hook_invalid_arg_for_unprototyped_fn (
 334         tree typelist ATTRIBUTE_UNUSED,
 335         tree funcdecl ATTRIBUTE_UNUSED,
 336         tree val ATTRIBUTE_UNUSED)
 337 {
 338   return NULL;
 339 }
 340
 341 /* Initialize the stack protection decls.  */
 342
 343 /* Stack protection related decls living in libgcc.  */
 344 static GTY(()) tree stack_chk_guard_decl;
 345
 346 tree
 347 default_stack_protect_guard (void)
 348 {
 349   tree t = stack_chk_guard_decl;
 350
 351   if (t == NULL)
 352     {
 353       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 354                       ptr_type_node);
 355       TREE_STATIC (t) = 1;
 356       TREE_PUBLIC (t) = 1;
 357       DECL_EXTERNAL (t) = 1;
 358       TREE_USED (t) = 1;
 359       TREE_THIS_VOLATILE (t) = 1;
 360       DECL_ARTIFICIAL (t) = 1;
 361       DECL_IGNORED_P (t) = 1;
 362
 363       stack_chk_guard_decl = t;
 364     }
 365
 366   return t;
 367 }
 368
 369 static GTY(()) tree stack_chk_fail_decl;
 370
 371 tree
 372 default_external_stack_protect_fail (void)
 373 {
 374   tree t = stack_chk_fail_decl;
 375
 376   if (t == NULL_TREE)
 377     {
 378       t = build_function_type_list (void_type_node, NULL_TREE);
 379       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 380       TREE_STATIC (t) = 1;
 381       TREE_PUBLIC (t) = 1;
 382       DECL_EXTERNAL (t) = 1;
 383       TREE_USED (t) = 1;
 384       TREE_THIS_VOLATILE (t) = 1;
 385       TREE_NOTHROW (t) = 1;
 386       DECL_ARTIFICIAL (t) = 1;
 387       DECL_IGNORED_P (t) = 1;
 388
 389       stack_chk_fail_decl = t;
 390     }
 391
 392   return build_function_call_expr (t, NULL_TREE);
 393 }
 394
 395 tree
 396 default_hidden_stack_protect_fail (void)
 397 {
 398 #ifndef HAVE_GAS_HIDDEN
 399   return default_external_stack_protect_fail ();
 400 #else
 401   tree t = stack_chk_fail_decl;
 402
 403   if (!flag_pic)
 404     return default_external_stack_protect_fail ();
 405
 406   if (t == NULL_TREE)
 407     {
 408       t = build_function_type_list (void_type_node, NULL_TREE);
 409       t = build_decl (FUNCTION_DECL,
 410                       get_identifier ("__stack_chk_fail_local"), t);
 411       TREE_STATIC (t) = 1;
 412       TREE_PUBLIC (t) = 1;
 413       DECL_EXTERNAL (t) = 1;
 414       TREE_USED (t) = 1;
 415       TREE_THIS_VOLATILE (t) = 1;
 416       TREE_NOTHROW (t) = 1;
 417       DECL_ARTIFICIAL (t) = 1;
 418       DECL_IGNORED_P (t) = 1;
 419       DECL_VISIBILITY_SPECIFIED (t) = 1;
 420       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 421
 422       stack_chk_fail_decl = t;
 423     }
 424
 425   return build_function_call_expr (t, NULL_TREE);
 426 #endif
 427 }
 428
 429 bool
 430 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 431 {
 432   return COMMUTATIVE_P (x);
 433 }
 434
 435 rtx
 436 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 437                         tree fn_decl_or_type,
 438                         bool outgoing ATTRIBUTE_UNUSED)
 439 {
 440   /* The old interface doesn't handle receiving the function type.  */
 441   if (fn_decl_or_type
 442       && !DECL_P (fn_decl_or_type))
 443     fn_decl_or_type = NULL;
 444
 445 #ifdef FUNCTION_OUTGOING_VALUE
 446   if (outgoing)
 447     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 448 #endif
 449
 450 #ifdef FUNCTION_VALUE
 451   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 452 #else
 453   return NULL_RTX;
 454 #endif
 455 }
 456
 457 rtx
 458 default_internal_arg_pointer (void)
 459 {
 460   /* If the reg that the virtual arg pointer will be translated into is
 461      not a fixed reg or is the stack pointer, make a copy of the virtual
 462      arg pointer, and address parms via the copy.  The frame pointer is
 463      considered fixed even though it is not marked as such.  */
 464   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 465        || ! (fixed_regs[ARG_POINTER_REGNUM]
 466              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 467     return copy_to_reg (virtual_incoming_args_rtx);
 468   else
 469     return virtual_incoming_args_rtx;
 470 }
 471
 472 enum reg_class
 473 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 474                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 475                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 476                           secondary_reload_info *sri)
 477 {
 478   enum reg_class class = NO_REGS;
 479
 480   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 481     {
 482       sri->icode = sri->prev_sri->t_icode;
 483       return NO_REGS;
 484     }
 485 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 486   if (in_p)
 487     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 488 #endif
 489 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 490   if (! in_p)
 491     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 492 #endif
 493   if (class != NO_REGS)
 494     {
 495       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 496                               : reload_out_optab[(int) reload_mode]);
 497
 498       if (icode != CODE_FOR_nothing
 499           && insn_data[(int) icode].operand[in_p].predicate
 500           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 501         icode = CODE_FOR_nothing;
 502       else if (icode != CODE_FOR_nothing)
 503         {
 504           const char *insn_constraint, *scratch_constraint;
 505           char insn_letter, scratch_letter;
 506           enum reg_class insn_class, scratch_class;
 507
 508           gcc_assert (insn_data[(int) icode].n_operands == 3);
 509           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 510           if (!*insn_constraint)
 511             insn_class = ALL_REGS;
 512           else
 513             {
 514               if (in_p)
 515                 {
 516                   gcc_assert (*insn_constraint == '=');
 517                   insn_constraint++;
 518                 }
 519               insn_letter = *insn_constraint;
 520               insn_class
 521                 = (insn_letter == 'r' ? GENERAL_REGS
 522                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 523                                                 insn_constraint));
 524               gcc_assert (insn_class != NO_REGS);
 525             }
 526
 527           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 528           /* The scratch register's constraint must start with "=&",
 529              except for an input reload, where only "=" is necessary,
 530              and where it might be beneficial to re-use registers from
 531              the input.  */
 532           gcc_assert (scratch_constraint[0] == '='
 533                       && (in_p || scratch_constraint[1] == '&'));
 534           scratch_constraint++;
 535           if (*scratch_constraint == '&')
 536             scratch_constraint++;
 537           scratch_letter = *scratch_constraint;
 538           scratch_class
 539             = (scratch_letter == 'r' ? GENERAL_REGS
 540                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 541                                             scratch_constraint));
 542
 543           if (reg_class_subset_p (reload_class, insn_class))
 544             {
 545               gcc_assert (scratch_class == class);
 546               class = NO_REGS;
 547             }
 548           else
 549             class = insn_class;
 550
 551         }
 552       if (class == NO_REGS)
 553         sri->icode = icode;
 554       else
 555         sri->t_icode = icode;
 556     }
 557   return class;
 558 }
 559
 560 #include "gt-targhooks.h"