gcc/cp/cp-lang.c

   1 /* Language-dependent hooks for C++.
   2    Copyright 2001, 2002 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, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "cp-tree.h"
  28 #include "c-common.h"
  29 #include "toplev.h"
  30 #include "langhooks.h"
  31 #include "langhooks-def.h"
  32
  33 static HOST_WIDE_INT cxx_get_alias_set (tree);
  34 static bool ok_to_generate_alias_set_for_type (tree);
  35 static bool cxx_warn_unused_global_decl (tree);
  36 static tree cp_expr_size (tree);
  37 static size_t cp_tree_size (enum tree_code);
  38 static bool cp_var_mod_type_p (tree);
  39
  40 #undef LANG_HOOKS_NAME
  41 #define LANG_HOOKS_NAME "GNU C++"
  42 #undef LANG_HOOKS_TREE_SIZE
  43 #define LANG_HOOKS_TREE_SIZE cp_tree_size
  44 #undef LANG_HOOKS_INIT
  45 #define LANG_HOOKS_INIT cxx_init
  46 #undef LANG_HOOKS_FINISH
  47 #define LANG_HOOKS_FINISH cxx_finish
  48 #undef LANG_HOOKS_CLEAR_BINDING_STACK
  49 #define LANG_HOOKS_CLEAR_BINDING_STACK pop_everything
  50 #undef LANG_HOOKS_INIT_OPTIONS
  51 #define LANG_HOOKS_INIT_OPTIONS cxx_init_options
  52 #undef LANG_HOOKS_DECODE_OPTION
  53 #define LANG_HOOKS_DECODE_OPTION c_common_decode_option
  54 #undef LANG_HOOKS_POST_OPTIONS
  55 #define LANG_HOOKS_POST_OPTIONS c_common_post_options
  56 #undef LANG_HOOKS_GET_ALIAS_SET
  57 #define LANG_HOOKS_GET_ALIAS_SET cxx_get_alias_set
  58 #undef LANG_HOOKS_EXPAND_CONSTANT
  59 #define LANG_HOOKS_EXPAND_CONSTANT cplus_expand_constant
  60 #undef LANG_HOOKS_EXPAND_EXPR
  61 #define LANG_HOOKS_EXPAND_EXPR cxx_expand_expr
  62 #undef LANG_HOOKS_SAFE_FROM_P
  63 #define LANG_HOOKS_SAFE_FROM_P c_safe_from_p
  64 #undef LANG_HOOKS_PARSE_FILE
  65 #define LANG_HOOKS_PARSE_FILE c_common_parse_file
  66 #undef LANG_HOOKS_DUP_LANG_SPECIFIC_DECL
  67 #define LANG_HOOKS_DUP_LANG_SPECIFIC_DECL cxx_dup_lang_specific_decl
  68 #undef LANG_HOOKS_UNSAVE_EXPR_NOW
  69 #define LANG_HOOKS_UNSAVE_EXPR_NOW cxx_unsave_expr_now
  70 #undef LANG_HOOKS_MAYBE_BUILD_CLEANUP
  71 #define LANG_HOOKS_MAYBE_BUILD_CLEANUP cxx_maybe_build_cleanup
  72 #undef LANG_HOOKS_TRUTHVALUE_CONVERSION
  73 #define LANG_HOOKS_TRUTHVALUE_CONVERSION c_common_truthvalue_conversion
  74 #undef LANG_HOOKS_INSERT_DEFAULT_ATTRIBUTES
  75 #define LANG_HOOKS_INSERT_DEFAULT_ATTRIBUTES cxx_insert_default_attributes
  76 #undef LANG_HOOKS_UNSAFE_FOR_REEVAL
  77 #define LANG_HOOKS_UNSAFE_FOR_REEVAL c_common_unsafe_for_reeval
  78 #undef LANG_HOOKS_SET_DECL_ASSEMBLER_NAME
  79 #define LANG_HOOKS_SET_DECL_ASSEMBLER_NAME mangle_decl
  80 #undef LANG_HOOKS_MARK_ADDRESSABLE
  81 #define LANG_HOOKS_MARK_ADDRESSABLE cxx_mark_addressable
  82 #undef LANG_HOOKS_PRINT_STATISTICS
  83 #define LANG_HOOKS_PRINT_STATISTICS cxx_print_statistics
  84 #undef LANG_HOOKS_PRINT_XNODE
  85 #define LANG_HOOKS_PRINT_XNODE cxx_print_xnode
  86 #undef LANG_HOOKS_PRINT_DECL
  87 #define LANG_HOOKS_PRINT_DECL cxx_print_decl
  88 #undef LANG_HOOKS_PRINT_TYPE
  89 #define LANG_HOOKS_PRINT_TYPE cxx_print_type
  90 #undef LANG_HOOKS_PRINT_IDENTIFIER
  91 #define LANG_HOOKS_PRINT_IDENTIFIER cxx_print_identifier
  92 #undef LANG_HOOKS_DECL_PRINTABLE_NAME
  93 #define LANG_HOOKS_DECL_PRINTABLE_NAME  cxx_printable_name
  94 #undef LANG_HOOKS_PRINT_ERROR_FUNCTION
  95 #define LANG_HOOKS_PRINT_ERROR_FUNCTION cxx_print_error_function
  96 #undef LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL
  97 #define LANG_HOOKS_WARN_UNUSED_GLOBAL_DECL cxx_warn_unused_global_decl
  98 #undef LANG_HOOKS_WRITE_GLOBALS
  99 #define LANG_HOOKS_WRITE_GLOBALS lhd_do_nothing
 100
 101
 102 #undef LANG_HOOKS_FUNCTION_INIT
 103 #define LANG_HOOKS_FUNCTION_INIT cxx_push_function_context
 104 #undef LANG_HOOKS_FUNCTION_FINAL
 105 #define LANG_HOOKS_FUNCTION_FINAL cxx_pop_function_context
 106
 107 /* Attribute hooks.  */
 108 #undef LANG_HOOKS_COMMON_ATTRIBUTE_TABLE
 109 #define LANG_HOOKS_COMMON_ATTRIBUTE_TABLE c_common_attribute_table
 110 #undef LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE
 111 #define LANG_HOOKS_FORMAT_ATTRIBUTE_TABLE c_common_format_attribute_table
 112 #undef LANG_HOOKS_ATTRIBUTE_TABLE
 113 #define LANG_HOOKS_ATTRIBUTE_TABLE cxx_attribute_table
 114
 115 #undef LANG_HOOKS_TREE_INLINING_WALK_SUBTREES
 116 #define LANG_HOOKS_TREE_INLINING_WALK_SUBTREES \
 117   cp_walk_subtrees
 118 #undef LANG_HOOKS_TREE_INLINING_CANNOT_INLINE_TREE_FN
 119 #define LANG_HOOKS_TREE_INLINING_CANNOT_INLINE_TREE_FN \
 120   cp_cannot_inline_tree_fn
 121 #undef LANG_HOOKS_TREE_INLINING_ADD_PENDING_FN_DECLS
 122 #define LANG_HOOKS_TREE_INLINING_ADD_PENDING_FN_DECLS \
 123   cp_add_pending_fn_decls
 124 #undef LANG_HOOKS_TREE_INLINING_TREE_CHAIN_MATTERS_P
 125 #define LANG_HOOKS_TREE_INLINING_TREE_CHAIN_MATTERS_P \
 126   cp_is_overload_p
 127 #undef LANG_HOOKS_TREE_INLINING_AUTO_VAR_IN_FN_P
 128 #define LANG_HOOKS_TREE_INLINING_AUTO_VAR_IN_FN_P \
 129   cp_auto_var_in_fn_p
 130 #undef LANG_HOOKS_TREE_INLINING_COPY_RES_DECL_FOR_INLINING
 131 #define LANG_HOOKS_TREE_INLINING_COPY_RES_DECL_FOR_INLINING \
 132   cp_copy_res_decl_for_inlining
 133 #undef LANG_HOOKS_TREE_INLINING_ANON_AGGR_TYPE_P
 134 #define LANG_HOOKS_TREE_INLINING_ANON_AGGR_TYPE_P anon_aggr_type_p
 135 #undef LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P
 136 #define LANG_HOOKS_TREE_INLINING_VAR_MOD_TYPE_P cp_var_mod_type_p
 137 #undef LANG_HOOKS_TREE_INLINING_START_INLINING
 138 #define LANG_HOOKS_TREE_INLINING_START_INLINING cp_start_inlining
 139 #undef LANG_HOOKS_TREE_INLINING_END_INLINING
 140 #define LANG_HOOKS_TREE_INLINING_END_INLINING cp_end_inlining
 141 #undef LANG_HOOKS_TREE_DUMP_DUMP_TREE_FN
 142 #define LANG_HOOKS_TREE_DUMP_DUMP_TREE_FN cp_dump_tree
 143 #undef LANG_HOOKS_TREE_DUMP_TYPE_QUALS_FN
 144 #define LANG_HOOKS_TREE_DUMP_TYPE_QUALS_FN cp_type_quals
 145 #undef LANG_HOOKS_EXPR_SIZE
 146 #define LANG_HOOKS_EXPR_SIZE cp_expr_size
 147
 148 #undef LANG_HOOKS_MAKE_TYPE
 149 #define LANG_HOOKS_MAKE_TYPE cxx_make_type
 150 #undef LANG_HOOKS_TYPE_FOR_MODE
 151 #define LANG_HOOKS_TYPE_FOR_MODE c_common_type_for_mode
 152 #undef LANG_HOOKS_TYPE_FOR_SIZE
 153 #define LANG_HOOKS_TYPE_FOR_SIZE c_common_type_for_size
 154 #undef LANG_HOOKS_SIGNED_TYPE
 155 #define LANG_HOOKS_SIGNED_TYPE c_common_signed_type
 156 #undef LANG_HOOKS_UNSIGNED_TYPE
 157 #define LANG_HOOKS_UNSIGNED_TYPE c_common_unsigned_type
 158 #undef LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE
 159 #define LANG_HOOKS_SIGNED_OR_UNSIGNED_TYPE c_common_signed_or_unsigned_type
 160 #undef LANG_HOOKS_INCOMPLETE_TYPE_ERROR
 161 #define LANG_HOOKS_INCOMPLETE_TYPE_ERROR cxx_incomplete_type_error
 162 #undef LANG_HOOKS_TYPE_PROMOTES_TO
 163 #define LANG_HOOKS_TYPE_PROMOTES_TO cxx_type_promotes_to
 164
 165 /* Each front end provides its own hooks, for toplev.c.  */
 166 const struct lang_hooks lang_hooks = LANG_HOOKS_INITIALIZER;
 167
 168 /* Tree code classes.  */
 169
 170 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) TYPE,
 171
 172 const char tree_code_type[] = {
 173 #include "tree.def"
 174   'x',
 175 #include "c-common.def"
 176   'x',
 177 #include "cp-tree.def"
 178 };
 179 #undef DEFTREECODE
 180
 181 /* Table indexed by tree code giving number of expression
 182    operands beyond the fixed part of the node structure.
 183    Not used for types or decls.  */
 184
 185 #define DEFTREECODE(SYM, NAME, TYPE, LENGTH) LENGTH,
 186
 187 const unsigned char tree_code_length[] = {
 188 #include "tree.def"
 189   0,
 190 #include "c-common.def"
 191   0,
 192 #include "cp-tree.def"
 193 };
 194 #undef DEFTREECODE
 195
 196 /* Names of tree components.
 197    Used for printing out the tree and error messages.  */
 198 #define DEFTREECODE(SYM, NAME, TYPE, LEN) NAME,
 199
 200 const char *const tree_code_name[] = {
 201 #include "tree.def"
 202   "@@dummy",
 203 #include "c-common.def"
 204   "@@dummy",
 205 #include "cp-tree.def"
 206 };
 207 #undef DEFTREECODE
 208
 209 /* Check if a C++ type is safe for aliasing.
 210    Return TRUE if T safe for aliasing FALSE otherwise.  */
 211
 212 static bool
 213 ok_to_generate_alias_set_for_type (tree t)
 214 {
 215   if (TYPE_PTRMEMFUNC_P (t))
 216     return true;
 217   if (AGGREGATE_TYPE_P (t))
 218     {
 219       if ((TREE_CODE (t) == RECORD_TYPE) || (TREE_CODE (t) == UNION_TYPE))
 220         {
 221           tree fields;
 222           /* Backend-created structs are safe.  */
 223           if (! CLASS_TYPE_P (t))
 224             return true;
 225           /* PODs are safe.  */
 226           if (! CLASSTYPE_NON_POD_P(t))
 227             return true;
 228           /* Classes with virtual baseclasses are not.  */
 229           if (TYPE_USES_VIRTUAL_BASECLASSES (t))
 230             return false;
 231           /* Recursively check the base classes.  */
 232           if (TYPE_BINFO (t) != NULL && TYPE_BINFO_BASETYPES (t) != NULL)
 233             {
 234               int i;
 235               for (i = 0; i < TREE_VEC_LENGTH (TYPE_BINFO_BASETYPES (t)); i++)
 236                 {
 237                   tree binfo = TREE_VEC_ELT (TYPE_BINFO_BASETYPES (t), i);
 238                   if (!ok_to_generate_alias_set_for_type (BINFO_TYPE (binfo)))
 239                     return false;
 240                 }
 241             }
 242           /* Check all the fields.  */
 243           for (fields = TYPE_FIELDS (t); fields; fields = TREE_CHAIN (fields))
 244             {
 245               if (TREE_CODE (fields) != FIELD_DECL)
 246                 continue;
 247               if (! ok_to_generate_alias_set_for_type (TREE_TYPE (fields)))
 248                 return false;
 249             }
 250           return true;
 251         }
 252       else if (TREE_CODE (t) == ARRAY_TYPE)
 253         return ok_to_generate_alias_set_for_type (TREE_TYPE (t));
 254       else
 255         /* This should never happen, we dealt with all the aggregate
 256            types that can appear in C++ above.  */
 257         abort ();
 258     }
 259   else
 260     return true;
 261 }
 262
 263 /* Special routine to get the alias set for C++.  */
 264
 265 static HOST_WIDE_INT
 266 cxx_get_alias_set (tree t)
 267 {
 268
 269   if (/* It's not yet safe to use alias sets for some classes in C++.  */
 270       !ok_to_generate_alias_set_for_type (t)
 271       /* Nor is it safe to use alias sets for pointers-to-member
 272          functions, due to the fact that there may be more than one
 273          RECORD_TYPE type corresponding to the same pointer-to-member
 274          type.  */
 275       || TYPE_PTRMEMFUNC_P (t))
 276     return 0;
 277
 278   return c_common_get_alias_set (t);
 279 }
 280
 281 /* Called from check_global_declarations.  */
 282
 283 static bool
 284 cxx_warn_unused_global_decl (tree decl)
 285 {
 286   if (TREE_CODE (decl) == FUNCTION_DECL && DECL_DECLARED_INLINE_P (decl))
 287     return false;
 288   if (DECL_IN_SYSTEM_HEADER (decl))
 289     return false;
 290
 291   /* Const variables take the place of #defines in C++.  */
 292   if (TREE_CODE (decl) == VAR_DECL && TREE_READONLY (decl))
 293     return false;
 294
 295   return true;
 296 }
 297
 298 /* Langhook for expr_size: Tell the backend that the value of an expression
 299    of non-POD class type does not include any tail padding; a derived class
 300    might have allocated something there.  */
 301
 302 static tree
 303 cp_expr_size (tree exp)
 304 {
 305   if (CLASS_TYPE_P (TREE_TYPE (exp)))
 306     {
 307       /* The backend should not be interested in the size of an expression
 308          of a type with both of these set; all copies of such types must go
 309          through a constructor or assignment op.  */
 310       if (TYPE_HAS_COMPLEX_INIT_REF (TREE_TYPE (exp))
 311           && TYPE_HAS_COMPLEX_ASSIGN_REF (TREE_TYPE (exp))
 312           /* But storing a CONSTRUCTOR isn't a copy.  */
 313           && TREE_CODE (exp) != CONSTRUCTOR)
 314         abort ();
 315       /* This would be wrong for a type with virtual bases, but they are
 316          caught by the abort above.  */
 317       return CLASSTYPE_SIZE_UNIT (TREE_TYPE (exp));
 318     }
 319   else
 320     /* Use the default code.  */
 321     return lhd_expr_size (exp);
 322 }
 323
 324 /* Langhook for tree_size: determine size of our 'x' and 'c' nodes.  */
 325 static size_t
 326 cp_tree_size (enum tree_code code)
 327 {
 328   switch (code)
 329     {
 330     case PTRMEM_CST:            return sizeof (struct ptrmem_cst);
 331     case BASELINK:              return sizeof (struct tree_baselink);
 332     case TEMPLATE_PARM_INDEX:   return sizeof (template_parm_index);
 333     case DEFAULT_ARG:           return sizeof (struct tree_default_arg);
 334     case OVERLOAD:              return sizeof (struct tree_overload);
 335     case WRAPPER:               return sizeof (struct tree_wrapper);
 336     default:
 337       abort ();
 338     }
 339   /* NOTREACHED */
 340 }
 341
 342 /* Returns true if T is a variably modified type, in the sense of C99.
 343    This routine needs only check cases that cannot be handled by the
 344    language-independent logic in tree-inline.c.  */
 345
 346 static bool
 347 cp_var_mod_type_p (tree type)
 348 {
 349   /* If TYPE is a pointer-to-member, it is variably modified if either
 350      the class or the member are variably modified.  */
 351   if (TYPE_PTRMEM_P (type) || TYPE_PTRMEMFUNC_P (type))
 352     return (variably_modified_type_p (TYPE_PTRMEM_CLASS_TYPE (type))
 353             || variably_modified_type_p (TYPE_PTRMEM_POINTED_TO_TYPE (type)));
 354
 355   /* All other types are not variably modified.  */
 356   return false;
 357 }
 358