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 static struct symbol *get_type_symbol(struct expression *expr)
  18 {
  19         if (!expr || expr->type != EXPR_SYMBOL)
  20                 return NULL;
  21
  22         return get_base_type(expr->symbol);
  23 }
  24
  25 static struct symbol *get_symbol_from_deref(struct expression *expr)
  26 {
  27         struct ident *member;
  28         struct symbol *struct_sym;
  29         struct symbol *tmp;
  30
  31         if (!expr || expr->type != EXPR_DEREF)
  32                 return NULL;
  33
  34         member = expr->member;
  35         struct_sym = get_type(expr->deref);
  36         if (!struct_sym) {
  37 //              sm_msg("could not find struct type");
  38                 return NULL;
  39         }
  40         if (struct_sym->type == SYM_PTR)
  41                 struct_sym = get_base_type(struct_sym);
  42         FOR_EACH_PTR(struct_sym->symbol_list, tmp) {
  43                 if (tmp->ident == member)
  44                         return get_base_type(tmp);
  45         } END_FOR_EACH_PTR(tmp);
  46         return NULL;
  47 }
  48
  49 static struct symbol *get_return_type(struct expression *expr)
  50 {
  51         struct symbol *tmp;
  52
  53         tmp = get_type(expr->fn);
  54         if (!tmp)
  55                 return NULL;
  56         return get_base_type(tmp);
  57 }
  58
  59 static struct symbol *fake_pointer_sym(struct expression *expr)
  60 {
  61         struct symbol *sym;
  62         struct symbol *base;
  63
  64         sym = alloc_symbol(expr->pos, SYM_PTR);
  65         expr = expr->unop;
  66         base = get_type(expr);
  67         if (!base)
  68                 return NULL;
  69         sym->ctype.base_type = base;
  70         return sym;
  71 }
  72
  73 struct symbol *get_type(struct expression *expr)
  74 {
  75         struct symbol *tmp;
  76
  77         if (!expr)
  78                 return NULL;
  79         expr = strip_parens(expr);
  80
  81         switch (expr->type) {
  82         case EXPR_SYMBOL:
  83                 return get_type_symbol(expr);
  84         case EXPR_DEREF:
  85                 return get_symbol_from_deref(expr);
  86         case EXPR_PREOP:
  87                 if (expr->op == '&')
  88                         return fake_pointer_sym(expr);
  89                 return get_type(expr->unop);
  90         case EXPR_CAST:
  91         case EXPR_FORCE_CAST:
  92         case EXPR_IMPLIED_CAST:
  93                 return get_base_type(expr->cast_type);
  94         case EXPR_BINOP:
  95                 if (expr->op != '+')
  96                         return NULL;
  97                 tmp = get_type(expr->left);
  98                 if (!tmp || (tmp->type != SYM_ARRAY && tmp->type != SYM_PTR))
  99                         return NULL;
 100                 return get_base_type(tmp);
 101         case EXPR_CALL:
 102                 return get_return_type(expr);
 103 //      default:
 104 //              sm_msg("unhandled type %d", expr->type);
 105         }
 106
 107
 108         return NULL;
 109 }
 110
 111 int type_unsigned(struct symbol *base_type)
 112 {
 113         if (base_type->ctype.modifiers & MOD_UNSIGNED)
 114                 return 1;
 115         return 0;
 116 }
 117
 118 long long type_max(struct symbol *base_type)
 119 {
 120         long long ret = whole_range.max;
 121         int bits;
 122
 123         if (!base_type || !base_type->bit_size)
 124                 return ret;
 125         bits = base_type->bit_size;
 126         if (!type_unsigned(base_type))
 127                 bits--;
 128         ret >>= (63 - bits);
 129         return ret;
 130 }
 131
 132 long long type_min(struct symbol *base_type)
 133 {
 134         long long ret = whole_range.min;
 135         int bits;
 136
 137         if (!base_type || !base_type->bit_size)
 138                 return ret;
 139         if (type_unsigned(base_type))
 140                 return 0;
 141         ret = whole_range.max;
 142         bits = base_type->bit_size - 1;
 143         ret >>= (63 - bits);
 144         return -(ret + 1);
 145 }
 146