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 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 274    an error message.
 275
 276    This function checks whether a given INSN is valid within a low-overhead
 277    loop.  If INSN is invalid it returns the reason for that, otherwise it
 278    returns NULL. A called function may clobber any special registers required
 279    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 280    register for branch on table instructions. We reject the doloop pattern in
 281    these cases.  */
 282
 283 const char *
 284 default_invalid_within_doloop (rtx insn)
 285 {
 286   if (CALL_P (insn))
 287     return "Function call in loop.";
 288
 289   if (JUMP_P (insn)
 290       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 291           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 292     return "Computed branch in the loop.";
 293
 294   return NULL;
 295 }
 296
 297 bool
 298 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 299         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 300         enum machine_mode mode ATTRIBUTE_UNUSED,
 301         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 302 {
 303   return false;
 304 }
 305
 306 bool
 307 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 308         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 309         enum machine_mode mode ATTRIBUTE_UNUSED,
 310         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 311 {
 312   return true;
 313 }
 314
 315 int
 316 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 317         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 318         enum machine_mode mode ATTRIBUTE_UNUSED,
 319         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 320 {
 321   return 0;
 322 }
 323
 324 const char *
 325 hook_invalid_arg_for_unprototyped_fn (
 326         tree typelist ATTRIBUTE_UNUSED,
 327         tree funcdecl ATTRIBUTE_UNUSED,
 328         tree val ATTRIBUTE_UNUSED)
 329 {
 330   return NULL;
 331 }
 332
 333 /* Initialize the stack protection decls.  */
 334
 335 /* Stack protection related decls living in libgcc.  */
 336 static GTY(()) tree stack_chk_guard_decl;
 337
 338 tree
 339 default_stack_protect_guard (void)
 340 {
 341   tree t = stack_chk_guard_decl;
 342
 343   if (t == NULL)
 344     {
 345       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 346                       ptr_type_node);
 347       TREE_STATIC (t) = 1;
 348       TREE_PUBLIC (t) = 1;
 349       DECL_EXTERNAL (t) = 1;
 350       TREE_USED (t) = 1;
 351       TREE_THIS_VOLATILE (t) = 1;
 352       DECL_ARTIFICIAL (t) = 1;
 353       DECL_IGNORED_P (t) = 1;
 354
 355       stack_chk_guard_decl = t;
 356     }
 357
 358   return t;
 359 }
 360
 361 static GTY(()) tree stack_chk_fail_decl;
 362
 363 tree
 364 default_external_stack_protect_fail (void)
 365 {
 366   tree t = stack_chk_fail_decl;
 367
 368   if (t == NULL_TREE)
 369     {
 370       t = build_function_type_list (void_type_node, NULL_TREE);
 371       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 372       TREE_STATIC (t) = 1;
 373       TREE_PUBLIC (t) = 1;
 374       DECL_EXTERNAL (t) = 1;
 375       TREE_USED (t) = 1;
 376       TREE_THIS_VOLATILE (t) = 1;
 377       TREE_NOTHROW (t) = 1;
 378       DECL_ARTIFICIAL (t) = 1;
 379       DECL_IGNORED_P (t) = 1;
 380
 381       stack_chk_fail_decl = t;
 382     }
 383
 384   return build_function_call_expr (t, NULL_TREE);
 385 }
 386
 387 tree
 388 default_hidden_stack_protect_fail (void)
 389 {
 390 #ifndef HAVE_GAS_HIDDEN
 391   return default_external_stack_protect_fail ();
 392 #else
 393   tree t = stack_chk_fail_decl;
 394
 395   if (!flag_pic)
 396     return default_external_stack_protect_fail ();
 397
 398   if (t == NULL_TREE)
 399     {
 400       t = build_function_type_list (void_type_node, NULL_TREE);
 401       t = build_decl (FUNCTION_DECL,
 402                       get_identifier ("__stack_chk_fail_local"), t);
 403       TREE_STATIC (t) = 1;
 404       TREE_PUBLIC (t) = 1;
 405       DECL_EXTERNAL (t) = 1;
 406       TREE_USED (t) = 1;
 407       TREE_THIS_VOLATILE (t) = 1;
 408       TREE_NOTHROW (t) = 1;
 409       DECL_ARTIFICIAL (t) = 1;
 410       DECL_IGNORED_P (t) = 1;
 411       DECL_VISIBILITY_SPECIFIED (t) = 1;
 412       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 413
 414       stack_chk_fail_decl = t;
 415     }
 416
 417   return build_function_call_expr (t, NULL_TREE);
 418 #endif
 419 }
 420
 421 bool
 422 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 423 {
 424   return COMMUTATIVE_P (x);
 425 }
 426
 427 rtx
 428 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 429                         tree fn_decl_or_type,
 430                         bool outgoing ATTRIBUTE_UNUSED)
 431 {
 432   /* The old interface doesn't handle receiving the function type.  */
 433   if (fn_decl_or_type
 434       && !DECL_P (fn_decl_or_type))
 435     fn_decl_or_type = NULL;
 436
 437 #ifdef FUNCTION_OUTGOING_VALUE
 438   if (outgoing)
 439     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 440 #endif
 441
 442 #ifdef FUNCTION_VALUE
 443   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 444 #else
 445   return NULL_RTX;
 446 #endif
 447 }
 448
 449 rtx
 450 default_internal_arg_pointer (void)
 451 {
 452   /* If the reg that the virtual arg pointer will be translated into is
 453      not a fixed reg or is the stack pointer, make a copy of the virtual
 454      arg pointer, and address parms via the copy.  The frame pointer is
 455      considered fixed even though it is not marked as such.  */
 456   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 457        || ! (fixed_regs[ARG_POINTER_REGNUM]
 458              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 459     return copy_to_reg (virtual_incoming_args_rtx);
 460   else
 461     return virtual_incoming_args_rtx;
 462 }
 463
 464 enum reg_class
 465 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 466                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 467                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 468                           secondary_reload_info *sri)
 469 {
 470   enum reg_class class = NO_REGS;
 471
 472   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 473     {
 474       sri->icode = sri->prev_sri->t_icode;
 475       return NO_REGS;
 476     }
 477 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 478   if (in_p)
 479     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 480 #endif
 481 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 482   if (! in_p)
 483     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 484 #endif
 485   if (class != NO_REGS)
 486     {
 487       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 488                               : reload_out_optab[(int) reload_mode]);
 489
 490       if (icode != CODE_FOR_nothing
 491           && insn_data[(int) icode].operand[in_p].predicate
 492           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 493         icode = CODE_FOR_nothing;
 494       else if (icode != CODE_FOR_nothing)
 495         {
 496           const char *insn_constraint, *scratch_constraint;
 497           char insn_letter, scratch_letter;
 498           enum reg_class insn_class, scratch_class;
 499
 500           gcc_assert (insn_data[(int) icode].n_operands == 3);
 501           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 502           if (!*insn_constraint)
 503             insn_class = ALL_REGS;
 504           else
 505             {
 506               if (in_p)
 507                 {
 508                   gcc_assert (*insn_constraint == '=');
 509                   insn_constraint++;
 510                 }
 511               insn_letter = *insn_constraint;
 512               insn_class
 513                 = (insn_letter == 'r' ? GENERAL_REGS
 514                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 515                                                 insn_constraint));
 516               gcc_assert (insn_class != NO_REGS);
 517             }
 518
 519           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 520           /* The scratch register's constraint must start with "=&",
 521              except for an input reload, where only "=" is necessary,
 522              and where it might be beneficial to re-use registers from
 523              the input.  */
 524           gcc_assert (scratch_constraint[0] == '='
 525                       && (in_p || scratch_constraint[1] == '&'));
 526           scratch_constraint++;
 527           if (*scratch_constraint == '&')
 528             scratch_constraint++;
 529           scratch_letter = *scratch_constraint;
 530           scratch_class
 531             = (scratch_letter == 'r' ? GENERAL_REGS
 532                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 533                                             scratch_constraint));
 534
 535           if (reg_class_subset_p (reload_class, insn_class))
 536             {
 537               gcc_assert (scratch_class == class);
 538               class = NO_REGS;
 539             }
 540           else
 541             class = insn_class;
 542
 543         }
 544       if (class == NO_REGS)
 545         sri->icode = icode;
 546       else
 547         sri->t_icode = icode;
 548     }
 549   return class;
 550 }
 551
 552 #include "gt-targhooks.h"