gcc/langhooks.c

   1 /* Default language-specific hooks.
   2    Copyright 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
   3    Contributed by Alexandre Oliva  <aoliva@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  20 Boston, MA 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "intl.h"
  26 #include "tm.h"
  27 #include "toplev.h"
  28 #include "tree.h"
  29 #include "tree-inline.h"
  30 #include "tree-gimple.h"
  31 #include "rtl.h"
  32 #include "insn-config.h"
  33 #include "integrate.h"
  34 #include "flags.h"
  35 #include "langhooks.h"
  36 #include "langhooks-def.h"
  37 #include "ggc.h"
  38 #include "diagnostic.h"
  39
  40 /* Do nothing; in many cases the default hook.  */
  41
  42 void
  43 lhd_do_nothing (void)
  44 {
  45 }
  46
  47 /* Do nothing (tree).  */
  48
  49 void
  50 lhd_do_nothing_t (tree ARG_UNUSED (t))
  51 {
  52 }
  53
  54 /* Do nothing (int).  */
  55
  56 void
  57 lhd_do_nothing_i (int ARG_UNUSED (i))
  58 {
  59 }
  60
  61 /* Do nothing (int, int, int).  Return NULL_TREE.  */
  62
  63 tree
  64 lhd_do_nothing_iii_return_null_tree (int ARG_UNUSED (i),
  65                                      int ARG_UNUSED (j),
  66                                      int ARG_UNUSED (k))
  67 {
  68   return NULL_TREE;
  69 }
  70
  71 /* Do nothing (function).  */
  72
  73 void
  74 lhd_do_nothing_f (struct function * ARG_UNUSED (f))
  75 {
  76 }
  77
  78 /* Do nothing (return the tree node passed).  */
  79
  80 tree
  81 lhd_return_tree (tree t)
  82 {
  83   return t;
  84 }
  85
  86 /* Do nothing (return NULL_TREE).  */
  87
  88 tree
  89 lhd_return_null_tree_v (void)
  90 {
  91   return NULL_TREE;
  92 }
  93
  94 /* Do nothing (return NULL_TREE).  */
  95
  96 tree
  97 lhd_return_null_tree (tree ARG_UNUSED (t))
  98 {
  99   return NULL_TREE;
 100 }
 101
 102 /* The default post options hook.  */
 103
 104 bool
 105 lhd_post_options (const char ** ARG_UNUSED (pfilename))
 106 {
 107   return false;
 108 }
 109
 110 /* Called from by print-tree.c.  */
 111
 112 void
 113 lhd_print_tree_nothing (FILE * ARG_UNUSED (file),
 114                         tree ARG_UNUSED (node),
 115                         int ARG_UNUSED (indent))
 116 {
 117 }
 118
 119 /* Called from safe_from_p.  */
 120
 121 int
 122 lhd_safe_from_p (rtx ARG_UNUSED (x), tree ARG_UNUSED (exp))
 123 {
 124   return 1;
 125 }
 126
 127 /* Called from staticp.  */
 128
 129 tree
 130 lhd_staticp (tree ARG_UNUSED (exp))
 131 {
 132   return NULL;
 133 }
 134
 135 /* Called from check_global_declarations.  */
 136
 137 bool
 138 lhd_warn_unused_global_decl (tree decl)
 139 {
 140   /* This is what used to exist in check_global_declarations.  Probably
 141      not many of these actually apply to non-C languages.  */
 142
 143   if (TREE_CODE (decl) == FUNCTION_DECL && DECL_INLINE (decl))
 144     return false;
 145   if (TREE_CODE (decl) == VAR_DECL && TREE_READONLY (decl))
 146     return false;
 147   if (DECL_IN_SYSTEM_HEADER (decl))
 148     return false;
 149
 150   return true;
 151 }
 152
 153 /* Set the DECL_ASSEMBLER_NAME for DECL.  */
 154 void
 155 lhd_set_decl_assembler_name (tree decl)
 156 {
 157   /* The language-independent code should never use the
 158      DECL_ASSEMBLER_NAME for lots of DECLs.  Only FUNCTION_DECLs and
 159      VAR_DECLs for variables with static storage duration need a real
 160      DECL_ASSEMBLER_NAME.  */
 161   gcc_assert (TREE_CODE (decl) == FUNCTION_DECL
 162               || (TREE_CODE (decl) == VAR_DECL
 163                   && (TREE_STATIC (decl)
 164                       || DECL_EXTERNAL (decl)
 165                       || TREE_PUBLIC (decl))));
 166
 167   /* By default, assume the name to use in assembly code is the same
 168      as that used in the source language.  (That's correct for C, and
 169      GCC used to set DECL_ASSEMBLER_NAME to the same value as
 170      DECL_NAME in build_decl, so this choice provides backwards
 171      compatibility with existing front-ends.
 172
 173      Can't use just the variable's own name for a variable whose scope
 174      is less than the whole compilation.  Concatenate a distinguishing
 175      number - we use the DECL_UID.  */
 176   if (TREE_PUBLIC (decl) || DECL_CONTEXT (decl) == NULL_TREE)
 177     SET_DECL_ASSEMBLER_NAME (decl, DECL_NAME (decl));
 178   else
 179     {
 180       const char *name = IDENTIFIER_POINTER (DECL_NAME (decl));
 181       char *label;
 182
 183       ASM_FORMAT_PRIVATE_NAME (label, name, DECL_UID (decl));
 184       SET_DECL_ASSEMBLER_NAME (decl, get_identifier (label));
 185     }
 186 }
 187
 188 /* By default we always allow bit-field based optimizations.  */
 189 bool
 190 lhd_can_use_bit_fields_p (void)
 191 {
 192   return true;
 193 }
 194
 195 /* Type promotion for variable arguments.  */
 196 tree
 197 lhd_type_promotes_to (tree ARG_UNUSED (type))
 198 {
 199   gcc_unreachable ();
 200 }
 201
 202 /* Registration of machine- or os-specific builtin types.  */
 203 void
 204 lhd_register_builtin_type (tree ARG_UNUSED (type),
 205                            const char * ARG_UNUSED (name))
 206 {
 207 }
 208
 209 /* Invalid use of an incomplete type.  */
 210 void
 211 lhd_incomplete_type_error (tree ARG_UNUSED (value), tree type)
 212 {
 213   gcc_assert (TREE_CODE (type) == ERROR_MARK);
 214   return;
 215 }
 216
 217 /* Provide a default routine for alias sets that always returns -1.  This
 218    is used by languages that don't need to do anything special.  */
 219
 220 HOST_WIDE_INT
 221 lhd_get_alias_set (tree ARG_UNUSED (t))
 222 {
 223   return -1;
 224 }
 225
 226 /* Provide a hook routine for alias sets that always returns 0.  This is
 227    used by languages that haven't deal with alias sets yet.  */
 228
 229 HOST_WIDE_INT
 230 hook_get_alias_set_0 (tree ARG_UNUSED (t))
 231 {
 232   return 0;
 233 }
 234
 235 /* This is the default expand_expr function.  */
 236
 237 rtx
 238 lhd_expand_expr (tree ARG_UNUSED (t), rtx ARG_UNUSED (r),
 239                  enum machine_mode ARG_UNUSED (mm),
 240                  int ARG_UNUSED (em),
 241                  rtx * ARG_UNUSED (a))
 242 {
 243   gcc_unreachable ();
 244 }
 245
 246 /* The default language-specific function for expanding a decl.  After
 247    the language-independent cases are handled, this function will be
 248    called.  If this function is not defined, it is assumed that
 249    declarations other than those for variables and labels do not require
 250    any RTL generation.  */
 251
 252 int
 253 lhd_expand_decl (tree ARG_UNUSED (t))
 254 {
 255   return 0;
 256 }
 257
 258 /* This is the default decl_printable_name function.  */
 259
 260 const char *
 261 lhd_decl_printable_name (tree decl, int ARG_UNUSED (verbosity))
 262 {
 263   gcc_assert (decl && DECL_NAME (decl));
 264   return IDENTIFIER_POINTER (DECL_NAME (decl));
 265 }
 266
 267 /* This is the default dwarf_name function.  */
 268
 269 const char *
 270 lhd_dwarf_name (tree t, int verbosity)
 271 {
 272   gcc_assert (DECL_P (t));
 273
 274   return lang_hooks.decl_printable_name (t, verbosity);
 275 }
 276
 277 /* This compares two types for equivalence ("compatible" in C-based languages).
 278    This routine should only return 1 if it is sure.  It should not be used
 279    in contexts where erroneously returning 0 causes problems.  */
 280
 281 int
 282 lhd_types_compatible_p (tree x, tree y)
 283 {
 284   return TYPE_MAIN_VARIANT (x) == TYPE_MAIN_VARIANT (y);
 285 }
 286
 287 /* lang_hooks.tree_inlining.walk_subtrees is called by walk_tree()
 288    after handling common cases, but before walking code-specific
 289    sub-trees.  If this hook is overridden for a language, it should
 290    handle language-specific tree codes, as well as language-specific
 291    information associated to common tree codes.  If a tree node is
 292    completely handled within this function, it should set *SUBTREES to
 293    0, so that generic handling isn't attempted.  The generic handling
 294    cannot deal with language-specific tree codes, so make sure it is
 295    set properly.  Both SUBTREES and *SUBTREES is guaranteed to be
 296    nonzero when the function is called.  */
 297
 298 tree
 299 lhd_tree_inlining_walk_subtrees (tree *tp ATTRIBUTE_UNUSED,
 300                                  int *subtrees ATTRIBUTE_UNUSED,
 301                                  walk_tree_fn func ATTRIBUTE_UNUSED,
 302                                  void *data ATTRIBUTE_UNUSED,
 303                                  struct pointer_set_t *pset ATTRIBUTE_UNUSED)
 304 {
 305   return NULL_TREE;
 306 }
 307
 308 /* lang_hooks.tree_inlining.cannot_inline_tree_fn is called to
 309    determine whether there are language-specific reasons for not
 310    inlining a given function.  */
 311
 312 int
 313 lhd_tree_inlining_cannot_inline_tree_fn (tree *fnp)
 314 {
 315   if (flag_really_no_inline
 316       && lookup_attribute ("always_inline", DECL_ATTRIBUTES (*fnp)) == NULL)
 317     return 1;
 318
 319   return 0;
 320 }
 321
 322 /* lang_hooks.tree_inlining.disregard_inline_limits is called to
 323    determine whether a function should be considered for inlining even
 324    if it would exceed inlining limits.  */
 325
 326 int
 327 lhd_tree_inlining_disregard_inline_limits (tree fn)
 328 {
 329   if (lookup_attribute ("always_inline", DECL_ATTRIBUTES (fn)) != NULL)
 330     return 1;
 331
 332   return 0;
 333 }
 334
 335 /* lang_hooks.tree_inlining.add_pending_fn_decls is called before
 336    starting to inline a function, to push any language-specific
 337    functions that should not be inlined into the current function,
 338    into VAFNP.  PFN is the top of varray, and should be returned if no
 339    functions are pushed into VAFNP.  The top of the varray should be
 340    returned.  */
 341
 342 tree
 343 lhd_tree_inlining_add_pending_fn_decls (void *vafnp ATTRIBUTE_UNUSED, tree pfn)
 344 {
 345   return pfn;
 346 }
 347
 348 /* lang_hooks.tree_inlining.auto_var_in_fn_p is called to determine
 349    whether VT is an automatic variable defined in function FT.  */
 350
 351 int
 352 lhd_tree_inlining_auto_var_in_fn_p (tree var, tree fn)
 353 {
 354   return (DECL_P (var) && DECL_CONTEXT (var) == fn
 355           && (((TREE_CODE (var) == VAR_DECL || TREE_CODE (var) == PARM_DECL)
 356                && ! TREE_STATIC (var))
 357               || TREE_CODE (var) == LABEL_DECL
 358               || TREE_CODE (var) == RESULT_DECL));
 359 }
 360
 361 /* lang_hooks.tree_inlining.anon_aggr_type_p determines whether T is a
 362    type node representing an anonymous aggregate (union, struct, etc),
 363    i.e., one whose members are in the same scope as the union itself.  */
 364
 365 int
 366 lhd_tree_inlining_anon_aggr_type_p (tree t ATTRIBUTE_UNUSED)
 367 {
 368   return 0;
 369 }
 370
 371 /* lang_hooks.tree_inlining.start_inlining and end_inlining perform any
 372    language-specific bookkeeping necessary for processing
 373    FN. start_inlining returns nonzero if inlining should proceed, zero if
 374    not.
 375
 376    For instance, the C++ version keeps track of template instantiations to
 377    avoid infinite recursion.  */
 378
 379 int
 380 lhd_tree_inlining_start_inlining (tree fn ATTRIBUTE_UNUSED)
 381 {
 382   return 1;
 383 }
 384
 385 void
 386 lhd_tree_inlining_end_inlining (tree fn ATTRIBUTE_UNUSED)
 387 {
 388 }
 389
 390 /* lang_hooks.tree_inlining.convert_parm_for_inlining performs any
 391    language-specific conversion before assigning VALUE to PARM.  */
 392
 393 tree
 394 lhd_tree_inlining_convert_parm_for_inlining (tree parm ATTRIBUTE_UNUSED,
 395                                              tree value,
 396                                              tree fndecl ATTRIBUTE_UNUSED,
 397                                              int argnum ATTRIBUTE_UNUSED)
 398 {
 399   return value;
 400 }
 401
 402 /* lang_hooks.tree_dump.dump_tree:  Dump language-specific parts of tree
 403    nodes.  Returns nonzero if it does not want the usual dumping of the
 404    second argument.  */
 405
 406 bool
 407 lhd_tree_dump_dump_tree (void *di ATTRIBUTE_UNUSED, tree t ATTRIBUTE_UNUSED)
 408 {
 409   return false;
 410 }
 411
 412 /* lang_hooks.tree_dump.type_qual:  Determine type qualifiers in a
 413    language-specific way.  */
 414
 415 int
 416 lhd_tree_dump_type_quals (tree t)
 417 {
 418   return TYPE_QUALS (t);
 419 }
 420
 421 /* lang_hooks.expr_size: Determine the size of the value of an expression T
 422    in a language-specific way.  Returns a tree for the size in bytes.  */
 423
 424 tree
 425 lhd_expr_size (tree exp)
 426 {
 427   if (DECL_P (exp)
 428       && DECL_SIZE_UNIT (exp) != 0)
 429     return DECL_SIZE_UNIT (exp);
 430   else
 431     return size_in_bytes (TREE_TYPE (exp));
 432 }
 433
 434 /* lang_hooks.gimplify_expr re-writes *EXPR_P into GIMPLE form.  */
 435
 436 int
 437 lhd_gimplify_expr (tree *expr_p ATTRIBUTE_UNUSED, tree *pre_p ATTRIBUTE_UNUSED,
 438                    tree *post_p ATTRIBUTE_UNUSED)
 439 {
 440   return GS_UNHANDLED;
 441 }
 442
 443 /* lang_hooks.tree_size: Determine the size of a tree with code C,
 444    which is a language-specific tree code in category tcc_constant or
 445    tcc_exceptional.  The default expects never to be called.  */
 446 size_t
 447 lhd_tree_size (enum tree_code c ATTRIBUTE_UNUSED)
 448 {
 449   gcc_unreachable ();
 450 }
 451
 452 /* Return true if decl, which is a function decl, may be called by a
 453    sibcall.  */
 454
 455 bool
 456 lhd_decl_ok_for_sibcall (tree decl ATTRIBUTE_UNUSED)
 457 {
 458   return true;
 459 }
 460
 461 /* Return the COMDAT group into which DECL should be placed.  */
 462
 463 const char *
 464 lhd_comdat_group (tree decl)
 465 {
 466   return IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 467 }
 468
 469 /* lang_hooks.decls.final_write_globals: perform final processing on
 470    global variables.  */
 471 void
 472 write_global_declarations (void)
 473 {
 474   /* Really define vars that have had only a tentative definition.
 475      Really output inline functions that must actually be callable
 476      and have not been output so far.  */
 477
 478   tree globals = lang_hooks.decls.getdecls ();
 479   int len = list_length (globals);
 480   tree *vec = XNEWVEC (tree, len);
 481   int i;
 482   tree decl;
 483
 484   /* Process the decls in reverse order--earliest first.
 485      Put them into VEC from back to front, then take out from front.  */
 486
 487   for (i = 0, decl = globals; i < len; i++, decl = TREE_CHAIN (decl))
 488     vec[len - i - 1] = decl;
 489
 490   wrapup_global_declarations (vec, len);
 491   check_global_declarations (vec, len);
 492   emit_debug_global_declarations (vec, len);
 493
 494   /* Clean up.  */
 495   free (vec);
 496 }
 497
 498 /* Called to perform language-specific initialization of CTX.  */
 499 void
 500 lhd_initialize_diagnostics (struct diagnostic_context *ctx ATTRIBUTE_UNUSED)
 501 {
 502 }
 503
 504 /* The default function to print out name of current function that caused
 505    an error.  */
 506 void
 507 lhd_print_error_function (diagnostic_context *context, const char *file)
 508 {
 509   if (diagnostic_last_function_changed (context))
 510     {
 511       const char *old_prefix = context->printer->prefix;
 512       char *new_prefix = file ? file_name_as_prefix (file) : NULL;
 513
 514       pp_set_prefix (context->printer, new_prefix);
 515
 516       if (current_function_decl == NULL)
 517         pp_printf (context->printer, _("At top level:"));
 518       else
 519         {
 520           if (TREE_CODE (TREE_TYPE (current_function_decl)) == METHOD_TYPE)
 521             pp_printf
 522               (context->printer, _("In member function %qs:"),
 523                lang_hooks.decl_printable_name (current_function_decl, 2));
 524           else
 525             pp_printf
 526               (context->printer, _("In function %qs:"),
 527                lang_hooks.decl_printable_name (current_function_decl, 2));
 528         }
 529
 530       diagnostic_set_last_function (context);
 531       pp_flush (context->printer);
 532       context->printer->prefix = old_prefix;
 533       free ((char*) new_prefix);
 534     }
 535 }
 536
 537 tree
 538 lhd_callgraph_analyze_expr (tree *tp ATTRIBUTE_UNUSED,
 539                             int *walk_subtrees ATTRIBUTE_UNUSED,
 540                             tree decl ATTRIBUTE_UNUSED)
 541 {
 542   return NULL;
 543 }
 544
 545 tree
 546 lhd_make_node (enum tree_code code)
 547 {
 548   return make_node (code);
 549 }
 550
 551 HOST_WIDE_INT
 552 lhd_to_target_charset (HOST_WIDE_INT c)
 553 {
 554   return c;
 555 }
 556
 557 tree
 558 lhd_expr_to_decl (tree expr, bool *tc ATTRIBUTE_UNUSED,
 559                   bool *ti ATTRIBUTE_UNUSED, bool *se ATTRIBUTE_UNUSED)
 560 {
 561   return expr;
 562 }
 563
 564 /* Return sharing kind if OpenMP sharing attribute of DECL is
 565    predetermined, OMP_CLAUSE_DEFAULT_UNSPECIFIED otherwise.  */
 566
 567 enum omp_clause_default_kind
 568 lhd_omp_predetermined_sharing (tree decl ATTRIBUTE_UNUSED)
 569 {
 570   if (DECL_ARTIFICIAL (decl))
 571     return OMP_CLAUSE_DEFAULT_SHARED;
 572   return OMP_CLAUSE_DEFAULT_UNSPECIFIED;
 573 }
 574
 575 /* Generate code to copy SRC to DST.  */
 576
 577 tree
 578 lhd_omp_assignment (tree clause ATTRIBUTE_UNUSED, tree dst, tree src)
 579 {
 580   return build2 (MODIFY_EXPR, void_type_node, dst, src);
 581 }
 582
 583 /* Register language specific type size variables as potentially OpenMP
 584    firstprivate variables.  */
 585
 586 void
 587 lhd_omp_firstprivatize_type_sizes (struct gimplify_omp_ctx *c ATTRIBUTE_UNUSED,
 588                                    tree t ATTRIBUTE_UNUSED)
 589 {
 590 }
 591
 592 tree
 593 add_builtin_function (const char *name,
 594                       tree type,
 595                       int function_code,
 596                       enum built_in_class cl,
 597                       const char *library_name,
 598                       tree attrs)
 599 {
 600   tree   id = get_identifier (name);
 601   tree decl = build_decl (FUNCTION_DECL, id, type);
 602
 603   TREE_PUBLIC (decl)         = 1;
 604   DECL_EXTERNAL (decl)       = 1;
 605   DECL_BUILT_IN_CLASS (decl) = cl;
 606   DECL_FUNCTION_CODE (decl)  = function_code;
 607
 608   if (library_name)
 609     {
 610       tree libname = get_identifier (library_name);
 611       SET_DECL_ASSEMBLER_NAME (decl, libname);
 612     }
 613
 614   /* Possibly apply some default attributes to this built-in function.  */
 615   if (attrs)
 616     decl_attributes (&decl, attrs, ATTR_FLAG_BUILT_IN);
 617   else
 618     decl_attributes (&decl, NULL_TREE, 0);
 619
 620   return lang_hooks.builtin_function (decl);
 621
 622 }
 623
 624 tree
 625 lhd_builtin_function (tree decl)
 626 {
 627   lang_hooks.decls.pushdecl (decl);
 628   return decl;
 629 }