smatch_type.c

   1 /*
   2  * sparse/smatch_types.c
   3  *
   4  * Copyright (C) 2009 Dan Carpenter.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 /*
  11  * The idea here is that you have an expression and you
  12  * want to know what the type is for that.
  13  */
  14
  15 #include "smatch.h"
  16
  17 struct symbol *get_real_base_type(struct symbol *sym)
  18 {
  19         struct symbol *ret;
  20
  21         ret = get_base_type(sym);
  22         if (ret && ret->type == SYM_RESTRICT)
  23                 return get_real_base_type(ret);
  24         return ret;
  25 }
  26
  27 int type_positive_bits(struct symbol *type)
  28 {
  29         if (type_unsigned(type))
  30                 return type->bit_size;
  31         return type->bit_size - 1;
  32 }
  33
  34 static struct symbol *get_binop_type(struct expression *expr)
  35 {
  36         struct symbol *left, *right;
  37
  38         left = get_type(expr->left);
  39         right = get_type(expr->right);
  40
  41         if (!left || !right)
  42                 return NULL;
  43
  44         if (left->type == SYM_PTR || left->type == SYM_ARRAY)
  45                 return left;
  46         if (right->type == SYM_PTR || right->type == SYM_ARRAY)
  47                 return right;
  48
  49         if (expr->op == SPECIAL_LEFTSHIFT ||
  50             expr->op == SPECIAL_RIGHTSHIFT) {
  51                 if (type_positive_bits(left) < 31)
  52                         return &int_ctype;
  53                 return left;
  54         }
  55
  56         if (type_positive_bits(left) < 31 && type_positive_bits(right) < 31)
  57                 return &int_ctype;
  58
  59         if (type_positive_bits(left) > type_positive_bits(right))
  60                 return left;
  61         return right;
  62 }
  63
  64 static struct symbol *get_type_symbol(struct expression *expr)
  65 {
  66         if (!expr || expr->type != EXPR_SYMBOL || !expr->symbol)
  67                 return NULL;
  68
  69         return get_real_base_type(expr->symbol);
  70 }
  71
  72 static struct symbol *get_symbol_from_deref(struct expression *expr)
  73 {
  74         struct ident *member;
  75         struct symbol *struct_sym;
  76         struct symbol *tmp;
  77
  78         if (!expr || expr->type != EXPR_DEREF)
  79                 return NULL;
  80
  81         member = expr->member;
  82         struct_sym = get_type(expr->deref);
  83         if (!struct_sym) {
  84                 // sm_msg("could not find struct type");
  85                 return NULL;
  86         }
  87         if (struct_sym->type == SYM_PTR)
  88                 struct_sym = get_real_base_type(struct_sym);
  89         FOR_EACH_PTR(struct_sym->symbol_list, tmp) {
  90                 if (tmp->ident == member)
  91                         return get_real_base_type(tmp);
  92         } END_FOR_EACH_PTR(tmp);
  93         return NULL;
  94 }
  95
  96 static struct symbol *get_return_type(struct expression *expr)
  97 {
  98         struct symbol *tmp;
  99
 100         tmp = get_type(expr->fn);
 101         if (!tmp)
 102                 return NULL;
 103         return get_real_base_type(tmp);
 104 }
 105
 106 struct symbol *get_pointer_type(struct expression *expr)
 107 {
 108         struct symbol *sym;
 109
 110         sym = get_type(expr);
 111         if (!sym || (sym->type != SYM_PTR && sym->type != SYM_ARRAY))
 112                 return NULL;
 113         return get_real_base_type(sym);
 114 }
 115
 116 static struct symbol *fake_pointer_sym(struct expression *expr)
 117 {
 118         struct symbol *sym;
 119         struct symbol *base;
 120
 121         sym = alloc_symbol(expr->pos, SYM_PTR);
 122         expr = expr->unop;
 123         base = get_type(expr);
 124         if (!base)
 125                 return NULL;
 126         sym->ctype.base_type = base;
 127         return sym;
 128 }
 129
 130 struct symbol *get_type(struct expression *expr)
 131 {
 132         if (!expr)
 133                 return NULL;
 134         expr = strip_parens(expr);
 135
 136         switch (expr->type) {
 137         case EXPR_SYMBOL:
 138                 return get_type_symbol(expr);
 139         case EXPR_DEREF:
 140                 return get_symbol_from_deref(expr);
 141         case EXPR_PREOP:
 142         case EXPR_POSTOP:
 143                 if (expr->op == '&')
 144                         return fake_pointer_sym(expr);
 145                 if (expr->op == '*')
 146                         return get_pointer_type(expr->unop);
 147                 return get_type(expr->unop);
 148         case EXPR_ASSIGNMENT:
 149                 return get_type(expr->left);
 150         case EXPR_CAST:
 151         case EXPR_FORCE_CAST:
 152         case EXPR_IMPLIED_CAST:
 153                 return get_real_base_type(expr->cast_type);
 154         case EXPR_COMPARE:
 155         case EXPR_BINOP:
 156                 return get_binop_type(expr);
 157         case EXPR_CALL:
 158                 return get_return_type(expr);
 159         case EXPR_SIZEOF:
 160                 return &ulong_ctype;
 161         case EXPR_LOGICAL:
 162                 return &int_ctype;
 163         default:
 164 //              sm_msg("unhandled type %d", expr->type);
 165                 return expr->ctype;
 166         }
 167         return NULL;
 168 }
 169
 170 int type_unsigned(struct symbol *base_type)
 171 {
 172         if (!base_type)
 173                 return 0;
 174         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 175                 return 1;
 176         return 0;
 177 }
 178
 179 int type_signed(struct symbol *base_type)
 180 {
 181         if (!base_type)
 182                 return 0;
 183         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 184                 return 0;
 185         return 1;
 186 }
 187
 188 int expr_unsigned(struct expression *expr)
 189 {
 190         struct symbol *sym;
 191
 192         sym = get_type(expr);
 193         if (!sym)
 194                 return 0;
 195         if (type_unsigned(sym))
 196                 return 1;
 197         return 0;
 198 }
 199
 200 int returns_unsigned(struct symbol *sym)
 201 {
 202         if (!sym)
 203                 return 0;
 204         sym = get_base_type(sym);
 205         if (!sym || sym->type != SYM_FN)
 206                 return 0;
 207         sym = get_base_type(sym);
 208         return type_unsigned(sym);
 209 }
 210
 211 int is_pointer(struct expression *expr)
 212 {
 213         struct symbol *sym;
 214
 215         sym = get_type(expr);
 216         if (!sym)
 217                 return 0;
 218         if (sym->type == SYM_PTR)
 219                 return 1;
 220         return 0;
 221 }
 222
 223 int returns_pointer(struct symbol *sym)
 224 {
 225         if (!sym)
 226                 return 0;
 227         sym = get_base_type(sym);
 228         if (!sym || sym->type != SYM_FN)
 229                 return 0;
 230         sym = get_base_type(sym);
 231         if (sym->type == SYM_PTR)
 232                 return 1;
 233         return 0;
 234 }
 235
 236 sval_t sval_type_max(struct symbol *base_type)
 237 {
 238         sval_t ret;
 239
 240         ret.value = (~0ULL) >> 1;
 241         ret.type = base_type;
 242
 243         if (!base_type || !base_type->bit_size)
 244                 return ret;
 245
 246         if (type_unsigned(base_type))
 247                 ret.value = (~0ULL) >> (64 - base_type->bit_size);
 248         else
 249                 ret.value = (~0ULL) >> (64 - (base_type->bit_size - 1));
 250
 251         return ret;
 252 }
 253
 254 sval_t sval_type_min(struct symbol *base_type)
 255 {
 256         sval_t ret;
 257
 258         if (!base_type || !base_type->bit_size)
 259                 base_type = &llong_ctype;
 260         ret.type = base_type;
 261
 262         if (type_unsigned(base_type)) {
 263                 ret.value = 0;
 264                 return ret;
 265         }
 266
 267         ret.value = (~0ULL) << (base_type->bit_size - 1);
 268
 269         return ret;
 270 }
 271
 272 int nr_bits(struct expression *expr)
 273 {
 274         struct symbol *type;
 275
 276         type = get_type(expr);
 277         if (!type)
 278                 return 0;
 279         return type->bit_size;
 280 }
 281
 282 int is_static(struct expression *expr)
 283 {
 284         char *name;
 285         struct symbol *sym;
 286         int ret = 0;
 287
 288         name = get_variable_from_expr_complex(expr, &sym);
 289         if (!name || !sym)
 290                 goto free;
 291
 292         if (sym->ctype.modifiers & MOD_STATIC)
 293                 ret = 1;
 294 free:
 295         free_string(name);
 296         return ret;
 297 }
 298
 299 const char *global_static()
 300 {
 301         if (cur_func_sym->ctype.modifiers & MOD_STATIC)
 302                 return "static";
 303         else
 304                 return "global";
 305 }
 306
 307 struct symbol *cur_func_return_type(void)
 308 {
 309         struct symbol *sym;
 310
 311         sym = get_real_base_type(cur_func_sym);
 312         if (!sym || sym->type != SYM_FN)
 313                 return NULL;
 314         sym = get_real_base_type(sym);
 315         return sym;
 316 }