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     default:
 266       gcc_unreachable ();
 267     }
 268 }
 269
 270 /* NULL if INSN insn is valid within a low-overhead loop, otherwise returns
 271    an error message.
 272
 273    This function checks whether a given INSN is valid within a low-overhead
 274    loop.  If INSN is invalid it returns the reason for that, otherwise it
 275    returns NULL. A called function may clobber any special registers required
 276    for low-overhead looping. Additionally, some targets (eg, PPC) use the count
 277    register for branch on table instructions. We reject the doloop pattern in
 278    these cases.  */
 279
 280 const char *
 281 default_invalid_within_doloop (rtx insn)
 282 {
 283   if (CALL_P (insn))
 284     return "Function call in loop.";
 285
 286   if (JUMP_P (insn)
 287       && (GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC
 288           || GET_CODE (PATTERN (insn)) == ADDR_VEC))
 289     return "Computed branch in the loop.";
 290
 291   return NULL;
 292 }
 293
 294 bool
 295 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_false (
 296         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 297         enum machine_mode mode ATTRIBUTE_UNUSED,
 298         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 299 {
 300   return false;
 301 }
 302
 303 bool
 304 hook_bool_CUMULATIVE_ARGS_mode_tree_bool_true (
 305         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 306         enum machine_mode mode ATTRIBUTE_UNUSED,
 307         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 308 {
 309   return true;
 310 }
 311
 312 int
 313 hook_int_CUMULATIVE_ARGS_mode_tree_bool_0 (
 314         CUMULATIVE_ARGS *ca ATTRIBUTE_UNUSED,
 315         enum machine_mode mode ATTRIBUTE_UNUSED,
 316         tree type ATTRIBUTE_UNUSED, bool named ATTRIBUTE_UNUSED)
 317 {
 318   return 0;
 319 }
 320
 321 const char *
 322 hook_invalid_arg_for_unprototyped_fn (
 323         tree typelist ATTRIBUTE_UNUSED,
 324         tree funcdecl ATTRIBUTE_UNUSED,
 325         tree val ATTRIBUTE_UNUSED)
 326 {
 327   return NULL;
 328 }
 329
 330 /* Initialize the stack protection decls.  */
 331
 332 /* Stack protection related decls living in libgcc.  */
 333 static GTY(()) tree stack_chk_guard_decl;
 334
 335 tree
 336 default_stack_protect_guard (void)
 337 {
 338   tree t = stack_chk_guard_decl;
 339
 340   if (t == NULL)
 341     {
 342       t = build_decl (VAR_DECL, get_identifier ("__stack_chk_guard"),
 343                       ptr_type_node);
 344       TREE_STATIC (t) = 1;
 345       TREE_PUBLIC (t) = 1;
 346       DECL_EXTERNAL (t) = 1;
 347       TREE_USED (t) = 1;
 348       TREE_THIS_VOLATILE (t) = 1;
 349       DECL_ARTIFICIAL (t) = 1;
 350       DECL_IGNORED_P (t) = 1;
 351
 352       stack_chk_guard_decl = t;
 353     }
 354
 355   return t;
 356 }
 357
 358 static GTY(()) tree stack_chk_fail_decl;
 359
 360 tree
 361 default_external_stack_protect_fail (void)
 362 {
 363   tree t = stack_chk_fail_decl;
 364
 365   if (t == NULL_TREE)
 366     {
 367       t = build_function_type_list (void_type_node, NULL_TREE);
 368       t = build_decl (FUNCTION_DECL, get_identifier ("__stack_chk_fail"), t);
 369       TREE_STATIC (t) = 1;
 370       TREE_PUBLIC (t) = 1;
 371       DECL_EXTERNAL (t) = 1;
 372       TREE_USED (t) = 1;
 373       TREE_THIS_VOLATILE (t) = 1;
 374       TREE_NOTHROW (t) = 1;
 375       DECL_ARTIFICIAL (t) = 1;
 376       DECL_IGNORED_P (t) = 1;
 377
 378       stack_chk_fail_decl = t;
 379     }
 380
 381   return build_function_call_expr (t, NULL_TREE);
 382 }
 383
 384 tree
 385 default_hidden_stack_protect_fail (void)
 386 {
 387 #ifndef HAVE_GAS_HIDDEN
 388   return default_external_stack_protect_fail ();
 389 #else
 390   tree t = stack_chk_fail_decl;
 391
 392   if (!flag_pic)
 393     return default_external_stack_protect_fail ();
 394
 395   if (t == NULL_TREE)
 396     {
 397       t = build_function_type_list (void_type_node, NULL_TREE);
 398       t = build_decl (FUNCTION_DECL,
 399                       get_identifier ("__stack_chk_fail_local"), t);
 400       TREE_STATIC (t) = 1;
 401       TREE_PUBLIC (t) = 1;
 402       DECL_EXTERNAL (t) = 1;
 403       TREE_USED (t) = 1;
 404       TREE_THIS_VOLATILE (t) = 1;
 405       TREE_NOTHROW (t) = 1;
 406       DECL_ARTIFICIAL (t) = 1;
 407       DECL_IGNORED_P (t) = 1;
 408       DECL_VISIBILITY_SPECIFIED (t) = 1;
 409       DECL_VISIBILITY (t) = VISIBILITY_HIDDEN;
 410
 411       stack_chk_fail_decl = t;
 412     }
 413
 414   return build_function_call_expr (t, NULL_TREE);
 415 #endif
 416 }
 417
 418 bool
 419 hook_bool_rtx_commutative_p (rtx x, int outer_code ATTRIBUTE_UNUSED)
 420 {
 421   return COMMUTATIVE_P (x);
 422 }
 423
 424 rtx
 425 default_function_value (tree ret_type ATTRIBUTE_UNUSED,
 426                         tree fn_decl_or_type,
 427                         bool outgoing ATTRIBUTE_UNUSED)
 428 {
 429   /* The old interface doesn't handle receiving the function type.  */
 430   if (fn_decl_or_type
 431       && !DECL_P (fn_decl_or_type))
 432     fn_decl_or_type = NULL;
 433
 434 #ifdef FUNCTION_OUTGOING_VALUE
 435   if (outgoing)
 436     return FUNCTION_OUTGOING_VALUE (ret_type, fn_decl_or_type);
 437 #endif
 438
 439 #ifdef FUNCTION_VALUE
 440   return FUNCTION_VALUE (ret_type, fn_decl_or_type);
 441 #else
 442   return NULL_RTX;
 443 #endif
 444 }
 445
 446 rtx
 447 default_internal_arg_pointer (void)
 448 {
 449   /* If the reg that the virtual arg pointer will be translated into is
 450      not a fixed reg or is the stack pointer, make a copy of the virtual
 451      arg pointer, and address parms via the copy.  The frame pointer is
 452      considered fixed even though it is not marked as such.  */
 453   if ((ARG_POINTER_REGNUM == STACK_POINTER_REGNUM
 454        || ! (fixed_regs[ARG_POINTER_REGNUM]
 455              || ARG_POINTER_REGNUM == FRAME_POINTER_REGNUM)))
 456     return copy_to_reg (virtual_incoming_args_rtx);
 457   else
 458     return virtual_incoming_args_rtx;
 459 }
 460
 461 enum reg_class
 462 default_secondary_reload (bool in_p ATTRIBUTE_UNUSED, rtx x ATTRIBUTE_UNUSED,
 463                           enum reg_class reload_class ATTRIBUTE_UNUSED,
 464                           enum machine_mode reload_mode ATTRIBUTE_UNUSED,
 465                           secondary_reload_info *sri)
 466 {
 467   enum reg_class class = NO_REGS;
 468
 469   if (sri->prev_sri && sri->prev_sri->t_icode != CODE_FOR_nothing)
 470     {
 471       sri->icode = sri->prev_sri->t_icode;
 472       return NO_REGS;
 473     }
 474 #ifdef SECONDARY_INPUT_RELOAD_CLASS
 475   if (in_p)
 476     class = SECONDARY_INPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 477 #endif
 478 #ifdef SECONDARY_OUTPUT_RELOAD_CLASS
 479   if (! in_p)
 480     class = SECONDARY_OUTPUT_RELOAD_CLASS (reload_class, reload_mode, x);
 481 #endif
 482   if (class != NO_REGS)
 483     {
 484       enum insn_code icode = (in_p ? reload_in_optab[(int) reload_mode]
 485                               : reload_out_optab[(int) reload_mode]);
 486
 487       if (icode != CODE_FOR_nothing
 488           && insn_data[(int) icode].operand[in_p].predicate
 489           && ! insn_data[(int) icode].operand[in_p].predicate (x, reload_mode))
 490         icode = CODE_FOR_nothing;
 491       else if (icode != CODE_FOR_nothing)
 492         {
 493           const char *insn_constraint, *scratch_constraint;
 494           char insn_letter, scratch_letter;
 495           enum reg_class insn_class, scratch_class;
 496
 497           gcc_assert (insn_data[(int) icode].n_operands == 3);
 498           insn_constraint = insn_data[(int) icode].operand[!in_p].constraint;
 499           if (!*insn_constraint)
 500             insn_class = ALL_REGS;
 501           else
 502             {
 503               if (in_p)
 504                 {
 505                   gcc_assert (*insn_constraint == '=');
 506                   insn_constraint++;
 507                 }
 508               insn_letter = *insn_constraint;
 509               insn_class
 510                 = (insn_letter == 'r' ? GENERAL_REGS
 511                    : REG_CLASS_FROM_CONSTRAINT ((unsigned char) insn_letter,
 512                                                 insn_constraint));
 513               gcc_assert (insn_class != NO_REGS);
 514             }
 515
 516           scratch_constraint = insn_data[(int) icode].operand[2].constraint;
 517           /* The scratch register's constraint must start with "=&".  */
 518           gcc_assert (scratch_constraint[0] == '='
 519                       && scratch_constraint[1] == '&');
 520           scratch_constraint += 2;
 521           scratch_letter = *scratch_constraint;
 522           scratch_class
 523             = (scratch_letter == 'r' ? GENERAL_REGS
 524                : REG_CLASS_FROM_CONSTRAINT ((unsigned char) scratch_letter,
 525                                             scratch_constraint));
 526
 527           if (reg_class_subset_p (reload_class, insn_class))
 528             {
 529               gcc_assert (scratch_class == class);
 530               class = NO_REGS;
 531             }
 532           else
 533             class = insn_class;
 534
 535         }
 536       if (class == NO_REGS)
 537         sri->icode = icode;
 538       else
 539         sri->t_icode = icode;
 540     }
 541   return class;
 542 }
 543
 544 #include "gt-targhooks.h"