check_bool_implications.c

   1 /*
   2  * sparse/check_bool_implications.c
   3  *
   4  * Copyright (C) 2012 Oracle.
   5  *
   6  * Licensed under the Open Software License version 1.1
   7  *
   8  */
   9
  10 #include "smatch.h"
  11 #include "smatch_extra.h"
  12 #include "smatch_slist.h"
  13
  14 static int my_id;
  15
  16 static struct state_list_stack *true_stack;
  17 static struct state_list_stack *false_stack;
  18
  19 static int returns_other;
  20
  21 static int non_bool(struct expression *expr)
  22 {
  23         if (possibly_true(expr, '<', zero_expr()))
  24                 return 1;
  25         if (possibly_true(expr, '>', value_expr(1)))
  26                 return 1;
  27         return 0;
  28 }
  29
  30 static void handle_condition_return(struct expression *expr)
  31 {
  32         struct state_list *slist;
  33         int was_final_pass;
  34
  35         was_final_pass = final_pass;
  36         final_pass = 0;
  37         __push_fake_cur_slist();
  38         __split_whole_condition(expr);
  39         push_slist(&true_stack, clone_slist(__get_cur_slist()));
  40         __push_true_states();
  41         __use_false_states();
  42         push_slist(&false_stack, clone_slist(__get_cur_slist()));
  43         __merge_true_states();
  44         slist = __pop_fake_cur_slist();
  45         final_pass = was_final_pass;
  46         free_slist(&slist);
  47 }
  48
  49 static void match_return(struct expression *ret_value)
  50 {
  51         long long val;
  52
  53         if (returns_other || !ret_value)
  54                 return;
  55
  56         if (non_bool(ret_value)) {
  57                 returns_other = 1;
  58                 return;
  59         }
  60
  61         if (get_implied_value(ret_value, &val) && val == 1) {
  62                 push_slist(&true_stack, clone_slist(__get_cur_slist()));
  63                 return;
  64         }
  65
  66         if (get_implied_value(ret_value, &val) && val == 0) {
  67                 push_slist(&false_stack, clone_slist(__get_cur_slist()));
  68                 return;
  69         }
  70
  71         handle_condition_return(ret_value);
  72 }
  73
  74 static void print_implications(struct symbol *sym, int param,
  75                 struct state_list *true_states,
  76                 struct state_list *false_states)
  77 {
  78         struct smatch_state *true_state;
  79         struct smatch_state *false_state;
  80
  81         if (!sym->ident)
  82                 return;
  83
  84         true_state = get_state_slist(true_states, SMATCH_EXTRA, sym->ident->name, sym);
  85         false_state = get_state_slist(false_states, SMATCH_EXTRA, sym->ident->name, sym);
  86
  87         if (!true_state || !false_state)
  88                 return;
  89
  90         if (range_lists_equiv(estate_ranges(true_state),
  91                                 estate_ranges(false_state)))
  92                 return;
  93
  94         sm_msg("info: bool_return_implication \"1\" %d \"%s\" %s", param,
  95                show_ranges(estate_ranges(true_state)), global_static());
  96         sm_msg("info: bool_return_implication \"0\" %d \"%s\" %s", param,
  97                show_ranges(estate_ranges(false_state)), global_static());
  98 }
  99
 100 static void cleanup(void)
 101 {
 102         free_stack_and_slists(&true_stack);
 103         free_stack_and_slists(&false_stack);
 104         returns_other = 0;
 105 }
 106
 107 static void match_end_func(struct symbol *sym)
 108 {
 109         struct state_list *merged_true = NULL;
 110         struct state_list *merged_false = NULL;
 111         struct state_list *tmp;
 112         struct symbol *param_sym;
 113         int i;
 114
 115         if (returns_other) {
 116                 cleanup();
 117                 return;
 118         }
 119
 120         FOR_EACH_PTR(true_stack, tmp) {
 121                 merge_slist(&merged_true, tmp);
 122         } END_FOR_EACH_PTR(tmp);
 123
 124         FOR_EACH_PTR(false_stack, tmp) {
 125                 merge_slist(&merged_false, tmp);
 126         } END_FOR_EACH_PTR(tmp);
 127
 128         i = 0;
 129         FOR_EACH_PTR(sym->ctype.base_type->arguments, param_sym) {
 130                 print_implications(param_sym, i, merged_true, merged_false);
 131                 i++;
 132         } END_FOR_EACH_PTR(param_sym);
 133
 134
 135         free_slist(&merged_true);
 136         free_slist(&merged_false);
 137
 138         cleanup();
 139 }
 140
 141 void check_bool_implications(int id)
 142 {
 143         if (!option_info)
 144                 return;
 145
 146         my_id = id;
 147         add_hook(&match_return, RETURN_HOOK);
 148         add_hook(&match_end_func, END_FUNC_HOOK);
 149 }