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 static struct symbol *get_type_symbol(struct expression *expr)
  28 {
  29         if (!expr || expr->type != EXPR_SYMBOL || !expr->symbol)
  30                 return NULL;
  31
  32         return get_real_base_type(expr->symbol);
  33 }
  34
  35 static struct symbol *get_symbol_from_deref(struct expression *expr)
  36 {
  37         struct ident *member;
  38         struct symbol *struct_sym;
  39         struct symbol *tmp;
  40
  41         if (!expr || expr->type != EXPR_DEREF)
  42                 return NULL;
  43
  44         member = expr->member;
  45         struct_sym = get_type(expr->deref);
  46         if (!struct_sym) {
  47                 // sm_msg("could not find struct type");
  48                 return NULL;
  49         }
  50         if (struct_sym->type == SYM_PTR)
  51                 struct_sym = get_real_base_type(struct_sym);
  52         FOR_EACH_PTR(struct_sym->symbol_list, tmp) {
  53                 if (tmp->ident == member)
  54                         return get_real_base_type(tmp);
  55         } END_FOR_EACH_PTR(tmp);
  56         return NULL;
  57 }
  58
  59 static struct symbol *get_return_type(struct expression *expr)
  60 {
  61         struct symbol *tmp;
  62
  63         tmp = get_type(expr->fn);
  64         if (!tmp)
  65                 return NULL;
  66         return get_real_base_type(tmp);
  67 }
  68
  69 struct symbol *get_pointer_type(struct expression *expr)
  70 {
  71         struct symbol *sym;
  72
  73         sym = get_type(expr);
  74         if (!sym || (sym->type != SYM_PTR && sym->type != SYM_ARRAY))
  75                 return NULL;
  76         return get_real_base_type(sym);
  77 }
  78
  79 static struct symbol *fake_pointer_sym(struct expression *expr)
  80 {
  81         struct symbol *sym;
  82         struct symbol *base;
  83
  84         sym = alloc_symbol(expr->pos, SYM_PTR);
  85         expr = expr->unop;
  86         base = get_type(expr);
  87         if (!base)
  88                 return NULL;
  89         sym->ctype.base_type = base;
  90         return sym;
  91 }
  92
  93 struct symbol *get_type(struct expression *expr)
  94 {
  95         struct symbol *tmp;
  96
  97         if (!expr)
  98                 return NULL;
  99         expr = strip_parens(expr);
 100
 101         switch (expr->type) {
 102         case EXPR_SYMBOL:
 103                 return get_type_symbol(expr);
 104         case EXPR_DEREF:
 105                 return get_symbol_from_deref(expr);
 106         case EXPR_PREOP:
 107                 if (expr->op == '&')
 108                         return fake_pointer_sym(expr);
 109                 if (expr->op == '*')
 110                         return get_pointer_type(expr->unop);
 111                 return get_type(expr->unop);
 112         case EXPR_CAST:
 113         case EXPR_FORCE_CAST:
 114         case EXPR_IMPLIED_CAST:
 115                 return get_real_base_type(expr->cast_type);
 116         case EXPR_BINOP:
 117                 if (expr->op != '+')
 118                         return NULL;
 119                 tmp = get_type(expr->left);
 120                 return tmp;
 121         case EXPR_CALL:
 122                 return get_return_type(expr);
 123         case EXPR_SIZEOF:
 124                 return &ulong_ctype;
 125         default:
 126                 return expr->ctype;
 127 //              sm_msg("unhandled type %d", expr->type);
 128         }
 129
 130
 131         return NULL;
 132 }
 133
 134 int type_unsigned(struct symbol *base_type)
 135 {
 136         if (!base_type)
 137                 return 0;
 138         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 139                 return 1;
 140         return 0;
 141 }
 142
 143 int expr_unsigned(struct expression *expr)
 144 {
 145         struct symbol *sym;
 146
 147         sym = get_type(expr);
 148         if (!sym)
 149                 return 0;
 150         if (type_unsigned(sym))
 151                 return 1;
 152         return 0;
 153 }
 154
 155 int returns_unsigned(struct symbol *sym)
 156 {
 157         if (!sym)
 158                 return 0;
 159         sym = get_base_type(sym);
 160         if (!sym || sym->type != SYM_FN)
 161                 return 0;
 162         sym = get_base_type(sym);
 163         return type_unsigned(sym);
 164 }
 165
 166 int returns_pointer(struct symbol *sym)
 167 {
 168         if (!sym)
 169                 return 0;
 170         sym = get_base_type(sym);
 171         if (!sym || sym->type != SYM_FN)
 172                 return 0;
 173         sym = get_base_type(sym);
 174         if (sym->type == SYM_PTR)
 175                 return 1;
 176         return 0;
 177 }
 178
 179 long long type_max(struct symbol *base_type)
 180 {
 181         long long ret = whole_range.max;
 182         int bits;
 183
 184         if (!base_type || !base_type->bit_size)
 185                 return ret;
 186         bits = base_type->bit_size;
 187         if (bits == 64)
 188                 return ret;
 189         if (!type_unsigned(base_type))
 190                 bits--;
 191         ret >>= (63 - bits);
 192         return ret;
 193 }
 194
 195 long long type_min(struct symbol *base_type)
 196 {
 197         long long ret = whole_range.min;
 198         int bits;
 199
 200         if (!base_type || !base_type->bit_size)
 201                 return ret;
 202         if (type_unsigned(base_type))
 203                 return 0;
 204         ret = whole_range.max;
 205         bits = base_type->bit_size - 1;
 206         ret >>= (63 - bits);
 207         return -(ret + 1);
 208 }
 209
 210 int nr_bits(struct expression *expr)
 211 {
 212         struct symbol *type;
 213
 214         type = get_type(expr);
 215         if (!type)
 216                 return 0;
 217         return type->bit_size;
 218 }