scope.c

   1 /*
   2  * Symbol scoping.
   3  *
   4  * This is pretty trivial.
   5  *
   6  * Copyright (C) 2003 Transmeta Corp.
   7  *               2003-2004 Linus Torvalds
   8  *
   9  * Permission is hereby granted, free of charge, to any person obtaining a copy
  10  * of this software and associated documentation files (the "Software"), to deal
  11  * in the Software without restriction, including without limitation the rights
  12  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  13  * copies of the Software, and to permit persons to whom the Software is
  14  * furnished to do so, subject to the following conditions:
  15  *
  16  * The above copyright notice and this permission notice shall be included in
  17  * all copies or substantial portions of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  22  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  23  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  24  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  25  * THE SOFTWARE.
  26  */
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <stdio.h>
  30
  31 #include "lib.h"
  32 #include "allocate.h"
  33 #include "symbol.h"
  34 #include "scope.h"
  35
  36 static struct scope builtin_scope = { .next = &builtin_scope };
  37
  38 struct scope    *block_scope = &builtin_scope,          // regular automatic variables etc
  39                 *label_scope = NULL,                    // expr-stmt labels
  40                 *function_scope = &builtin_scope,       // labels, arguments etc
  41                 *file_scope = &builtin_scope,           // static
  42                 *global_scope = &builtin_scope;         // externally visible
  43
  44 void set_current_scope(struct symbol *sym)
  45 {
  46         sym->scope = block_scope;
  47 }
  48
  49 void bind_scope(struct symbol *sym, struct scope *scope)
  50 {
  51         sym->scope = scope;
  52         add_symbol(&scope->symbols, sym);
  53 }
  54
  55 void rebind_scope(struct symbol *sym, struct scope *new)
  56 {
  57         struct scope *old = sym->scope;
  58
  59         if (old == new)
  60                 return;
  61
  62         if (old)
  63                 delete_ptr_list_entry((struct ptr_list**) &old->symbols, sym, 1);
  64
  65         bind_scope(sym, new);
  66 }
  67
  68 static void start_scope(struct scope **s, struct position pos)
  69 {
  70         struct scope *scope = __alloc_scope(0);
  71
  72         scope->token = __alloc_token(0);
  73         scope->token->pos = pos;
  74
  75         scope->next = *s;
  76         *s = scope;
  77 }
  78
  79 void start_file_scope(void)
  80 {
  81         struct scope *scope = __alloc_scope(0);
  82
  83         scope->next = &builtin_scope;
  84         file_scope = scope;
  85
  86         /* top-level stuff defaults to file scope, "extern" etc will choose global scope */
  87         function_scope = scope;
  88         block_scope = scope;
  89 }
  90
  91 void start_block_scope(struct position pos)
  92 {
  93         start_scope(&block_scope, pos);
  94 }
  95
  96 void start_function_scope(struct position pos)
  97 {
  98         start_scope(&block_scope, pos);
  99         start_scope(&label_scope, pos);
 100         function_scope = label_scope;
 101 }
 102
 103 static void remove_symbol_scope(struct symbol *sym)
 104 {
 105         struct symbol **ptr = &sym->ident->symbols;
 106
 107         while (*ptr != sym)
 108                 ptr = &(*ptr)->next_id;
 109         *ptr = sym->next_id;
 110 }
 111
 112 static void end_scope(struct scope **s)
 113 {
 114         struct scope *scope = *s;
 115         struct symbol_list *symbols = scope->symbols;
 116         struct symbol *sym;
 117
 118         *s = scope->next;
 119         scope->symbols = NULL;
 120         FOR_EACH_PTR(symbols, sym) {
 121                 remove_symbol_scope(sym);
 122         } END_FOR_EACH_PTR(sym);
 123 }
 124
 125 void end_file_scope(void)
 126 {
 127         end_scope(&file_scope);
 128 }
 129
 130 void new_file_scope(void)
 131 {
 132         if (file_scope != &builtin_scope)
 133                 end_file_scope();
 134         start_file_scope();
 135 }
 136
 137 void end_block_scope(void)
 138 {
 139         end_scope(&block_scope);
 140 }
 141
 142 void end_function_scope(void)
 143 {
 144         end_scope(&block_scope);
 145         end_label_scope();
 146         function_scope = label_scope;
 147 }
 148
 149 void start_label_scope(struct position pos)
 150 {
 151         start_scope(&label_scope, pos);
 152 }
 153
 154 void end_label_scope(void)
 155 {
 156         struct symbol *sym;
 157
 158         FOR_EACH_PTR(label_scope->symbols, sym) {
 159                 if (!sym->stmt || sym->used)
 160                         continue;
 161                 if (sym->label_modifiers & MOD_UNUSED)
 162                         continue;
 163                 warning(sym->pos, "unused label '%s'", show_ident(sym->ident));
 164         } END_FOR_EACH_PTR(sym);
 165
 166         end_scope(&label_scope);
 167 }
 168
 169 int is_outer_scope(struct scope *scope)
 170 {
 171         if (scope == block_scope)
 172                 return 0;
 173         if (scope == &builtin_scope && block_scope->next == &builtin_scope)
 174                 return 0;
 175         return 1;
 176 }
 177
 178 int is_in_scope(struct scope *outer, struct scope *inner)
 179 {
 180         while (inner != outer) {
 181                 if (inner == function_scope)
 182                         return 0;
 183                 inner = inner->next;
 184         }
 185         return 1;
 186 }