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