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
  56 void rebind_scope(struct symbol *sym, struct scope *new)
  57 {
  58         struct scope *old = sym->scope;
  59
  60         if (old == new)
  61                 return;
  62
  63         if (old)
  64                 delete_ptr_list_entry((struct ptr_list**) &old->symbols, sym, 1);
  65
  66         bind_scope(sym, new);
  67 }
  68
  69 static void start_scope(struct scope **s)
  70 {
  71         struct scope *scope = __alloc_scope(0);
  72         scope->next = *s;
  73         *s = scope;
  74 }
  75
  76 void start_file_scope(void)
  77 {
  78         struct scope *scope = __alloc_scope(0);
  79
  80         scope->next = &builtin_scope;
  81         file_scope = scope;
  82
  83         /* top-level stuff defaults to file scope, "extern" etc will choose global scope */
  84         function_scope = scope;
  85         block_scope = scope;
  86 }
  87
  88 void start_block_scope(void)
  89 {
  90         start_scope(&block_scope);
  91 }
  92
  93 void start_function_scope(void)
  94 {
  95         start_scope(&block_scope);
  96         start_scope(&label_scope);
  97         function_scope = label_scope;
  98 }
  99
 100 static void remove_symbol_scope(struct symbol *sym)
 101 {
 102         struct symbol **ptr = &sym->ident->symbols;
 103
 104         while (*ptr != sym)
 105                 ptr = &(*ptr)->next_id;
 106         *ptr = sym->next_id;
 107 }
 108
 109 static void end_scope(struct scope **s)
 110 {
 111         struct scope *scope = *s;
 112         struct symbol_list *symbols = scope->symbols;
 113         struct symbol *sym;
 114
 115         *s = scope->next;
 116         scope->symbols = NULL;
 117         FOR_EACH_PTR(symbols, sym) {
 118                 remove_symbol_scope(sym);
 119         } END_FOR_EACH_PTR(sym);
 120 }
 121
 122 void end_file_scope(void)
 123 {
 124         end_scope(&file_scope);
 125 }
 126
 127 void new_file_scope(void)
 128 {
 129         if (file_scope != &builtin_scope)
 130                 end_file_scope();
 131         start_file_scope();
 132 }
 133
 134 void end_block_scope(void)
 135 {
 136         end_scope(&block_scope);
 137 }
 138
 139 void end_function_scope(void)
 140 {
 141         end_scope(&block_scope);
 142         end_label_scope();
 143         function_scope = label_scope;
 144 }
 145
 146 void start_label_scope(void)
 147 {
 148         start_scope(&label_scope);
 149 }
 150
 151 void end_label_scope(void)
 152 {
 153         struct symbol *sym;
 154
 155         FOR_EACH_PTR(label_scope->symbols, sym) {
 156                 if (!sym->stmt || sym->used)
 157                         continue;
 158                 if (sym->label_modifiers & MOD_UNUSED)
 159                         continue;
 160                 warning(sym->pos, "unused label '%s'", show_ident(sym->ident));
 161         } END_FOR_EACH_PTR(sym);
 162
 163         end_scope(&label_scope);
 164 }
 165
 166 int is_outer_scope(struct scope *scope)
 167 {
 168         if (scope == block_scope)
 169                 return 0;
 170         if (scope == &builtin_scope && block_scope->next == &builtin_scope)
 171                 return 0;
 172         return 1;
 173 }
 174
 175 int is_in_scope(struct scope *outer, struct scope *inner)
 176 {
 177         while (inner != outer) {
 178                 if (inner == function_scope)
 179                         return 0;
 180                 inner = inner->next;
 181         }
 182         return 1;
 183 }