newfuzzer.cc

   1 #include "newfuzzer.h"
   2 #include "threads-model.h"
   3 #include "model.h"
   4 #include "action.h"
   5 #include "execution.h"
   6 #include "funcnode.h"
   7
   8 NewFuzzer::NewFuzzer() :
   9         thrd_last_read_act(),
  10         thrd_curr_pred(),
  11         thrd_selected_child_branch(),
  12         thrd_pruned_writes()
  13 {}
  14
  15 /**
  16  * @brief Register the ModelHistory and ModelExecution engine
  17  */
  18 void NewFuzzer::register_engine(ModelHistory * history, ModelExecution *execution)
  19 {
  20         this->history = history;
  21         this->execution = execution;
  22 }
  23
  24 int NewFuzzer::selectWrite(ModelAction *read, SnapVector<ModelAction *> * rf_set)
  25 {
  26         thread_id_t tid = read->get_tid();
  27         int thread_id = id_to_int(tid);
  28
  29         if (thrd_last_read_act.size() <= (uint) thread_id)
  30                 thrd_last_read_act.resize(thread_id + 1);
  31
  32         // A new read action is encountered, select a random child branch of current predicate
  33         if (read != thrd_last_read_act[thread_id]) {
  34                 thrd_last_read_act[thread_id] = read;
  35
  36                 SnapVector<func_id_list_t> * thrd_func_list = execution->get_thrd_func_list();
  37                 uint32_t func_id = (*thrd_func_list)[thread_id].back();
  38                 FuncNode * func_node = history->get_func_node(func_id);
  39                 inst_act_map_t * inst_act_map = func_node->get_inst_act_map(tid);
  40                 Predicate * curr_pred = func_node->get_predicate_tree_position(tid);
  41                 FuncInst * read_inst = func_node->get_inst(read);
  42
  43                 Predicate * selected_branch = selectBranch(tid, curr_pred, read_inst);
  44                 prune_writes(tid, selected_branch, rf_set, inst_act_map);
  45         }
  46
  47         // TODO: make this thread sleep if no write satisfies the chosen predicate
  48         // if no read satisfies the selected predicate
  49         if ( rf_set->size() == 0 ) {
  50                 SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
  51                 for (uint i = 0; i < pruned_writes->size(); i++)
  52                         rf_set->push_back( (*pruned_writes)[i] );
  53         }
  54
  55         ASSERT(rf_set->size() != 0);
  56         int random_index = random() % rf_set->size();
  57
  58         return random_index;
  59 }
  60
  61 /* Select a random branch from the children of curr_pred
  62  * @return The selected branch
  63  */
  64 Predicate * NewFuzzer::selectBranch(thread_id_t tid, Predicate * curr_pred, FuncInst * read_inst)
  65 {
  66         int thread_id = id_to_int(tid);
  67         if ( thrd_selected_child_branch.size() <= (uint) thread_id)
  68                 thrd_selected_child_branch.resize(thread_id + 1);
  69
  70         if (curr_pred == NULL || read_inst == NULL) {
  71                 thrd_selected_child_branch[thread_id] = NULL;
  72                 return NULL;
  73         }
  74
  75         ModelVector<Predicate *> * children = curr_pred->get_children();
  76         SnapVector<Predicate *> branches;
  77
  78         for (uint i = 0; i < children->size(); i++) {
  79                 Predicate * child = (*children)[i];
  80                 if (child->get_func_inst() == read_inst)
  81                         branches.push_back(child);
  82         }
  83
  84         // predicate children have not been generated
  85         if (branches.size() == 0) {
  86                 thrd_selected_child_branch[thread_id] = NULL;
  87                 return NULL;
  88         }
  89
  90         // randomly select a branch
  91         int random_index = random() % branches.size();
  92         Predicate * random_branch = branches[ random_index ];
  93         thrd_selected_child_branch[thread_id] = random_branch;
  94
  95         return random_branch;
  96 }
  97
  98 Predicate * NewFuzzer::get_selected_child_branch(thread_id_t tid)
  99 {
 100         int thread_id = id_to_int(tid);
 101         if (thrd_selected_child_branch.size() <= (uint) thread_id)
 102                 return NULL;
 103
 104         return thrd_selected_child_branch[thread_id];
 105 }
 106
 107 /* Remove writes from the rf_set that do not satisfie the selected predicate,
 108  * and store them in thrd_pruned_writes
 109  *
 110  * @return true if rf_set is pruned
 111  */
 112 bool NewFuzzer::prune_writes(thread_id_t tid, Predicate * pred,
 113         SnapVector<ModelAction *> * rf_set, inst_act_map_t * inst_act_map)
 114 {
 115         if (pred == NULL)
 116                 return false;
 117
 118         PredExprSet * pred_expressions = pred->get_pred_expressions();
 119         if (pred_expressions->getSize() == 0)   // unset predicates
 120                 return false;
 121
 122         int thread_id = id_to_int(tid);
 123         uint old_size = thrd_pruned_writes.size();
 124         if (thrd_pruned_writes.size() <= (uint) thread_id) {
 125                 uint new_size = thread_id + 1;
 126                 thrd_pruned_writes.resize(new_size);
 127                 for (uint i = old_size; i < new_size; i++)
 128                         thrd_pruned_writes[i] = new SnapVector<ModelAction *>();
 129         }
 130         SnapVector<ModelAction *> * pruned_writes = thrd_pruned_writes[thread_id];
 131         pruned_writes->clear(); // clear the old pruned_writes set
 132
 133         bool pruned = false;
 134         uint index = 0;
 135         while ( index < rf_set->size() ) {
 136                 ModelAction * write_act = (*rf_set)[index];
 137                 bool satisfy_predicate = true;
 138
 139                 PredExprSetIter * pred_expr_it = pred_expressions->iterator();
 140                 while (pred_expr_it->hasNext()) {
 141                         struct pred_expr * expression = pred_expr_it->next();
 142                         uint64_t write_val = write_act->get_write_value();
 143                         bool equality;
 144
 145                         // No predicate, return false
 146                         if (expression->token == NOPREDICATE)
 147                                 return pruned;
 148
 149                         switch(expression->token) {
 150                                 case EQUALITY:
 151                                         FuncInst * to_be_compared;
 152                                         ModelAction * last_act;
 153                                         uint64_t last_read;
 154
 155                                         to_be_compared = expression->func_inst;
 156                                         last_act = inst_act_map->get(to_be_compared);
 157                                         last_read = last_act->get_reads_from_value();
 158
 159                                         equality = (write_val == last_read);
 160                                         if (equality != expression->value)
 161                                                 satisfy_predicate = false;
 162                                         break;
 163                                 case NULLITY:
 164                                         equality = ((void*)write_val == NULL);
 165                                         if (equality != expression->value)
 166                                                 satisfy_predicate = false;
 167                                         break;
 168                                 default:
 169                                         model_print("unknown predicate token\n");
 170                                         break;
 171                         }
 172
 173                         if (!satisfy_predicate)
 174                                 break;
 175                 }
 176
 177                 if (!satisfy_predicate) {
 178                         ASSERT(rf_set != NULL);
 179                         (*rf_set)[index] = rf_set->back();
 180                         rf_set->pop_back();
 181                         pruned_writes->push_back(write_act);
 182                         pruned = true;
 183                 } else
 184                         index++;
 185         }
 186
 187         return pruned;
 188 }