#include "snapshot-interface.h"
#include "common.h"
#include "clockvector.h"
+#include "cyclegraph.h"
#define INITIAL_THREAD_ID 0
diverge(NULL),
nextThread(THREAD_ID_T_NONE),
action_trace(new action_list_t()),
- thread_map(new std::map<int, class Thread *>),
+ thread_map(new std::map<int, Thread *>),
+ obj_map(new std::map<const void *, action_list_t>()),
obj_thrd_map(new std::map<void *, std::vector<action_list_t> >()),
thrd_last_action(new std::vector<ModelAction *>(1)),
node_stack(new NodeStack()),
- next_backtrack(NULL)
+ next_backtrack(NULL),
+ cyclegraph(new CycleGraph())
{
}
/** @brief Destructor */
ModelChecker::~ModelChecker()
{
- std::map<int, class Thread *>::iterator it;
+ std::map<int, Thread *>::iterator it;
for (it = thread_map->begin(); it != thread_map->end(); it++)
delete (*it).second;
delete thread_map;
delete obj_thrd_map;
+ delete obj_map;
delete action_trace;
delete thrd_last_action;
delete node_stack;
delete scheduler;
+ delete cyclegraph;
}
/**
}
/** @returns a sequence number for a new ModelAction */
-int ModelChecker::get_next_seq_num()
+modelclock_t ModelChecker::get_next_seq_num()
{
return ++used_sequence_numbers;
}
next = node_stack->get_next()->get_action();
if (next == diverge) {
- Node *node = next->get_node();
-
+ Node *nextnode = next->get_node();
/* Reached divergence point */
+ if (nextnode->increment_read_from()) {
+ /* The next node will read from a different value */
+ tid = next->get_tid();
+ node_stack->pop_restofstack(2);
+ } else {
+ /* Make a different thread execute for next step */
+ Node *node = nextnode->get_parent();
+ tid = node->get_next_backtrack();
+ node_stack->pop_restofstack(1);
+ }
DEBUG("*** Divergence point ***\n");
- tid = node->get_next_backtrack();
diverge = NULL;
} else {
tid = next->get_tid();
action_type type = act->get_type();
switch (type) {
- case THREAD_CREATE:
- case THREAD_YIELD:
- case THREAD_JOIN:
- return NULL;
case ATOMIC_READ:
case ATOMIC_WRITE:
- default:
+ case ATOMIC_RMW:
break;
+ default:
+ return NULL;
}
/* linear search: from most recent to oldest */
+ action_list_t *list = &(*obj_map)[act->get_location()];
action_list_t::reverse_iterator rit;
- for (rit = action_trace->rbegin(); rit != action_trace->rend(); rit++) {
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
if (act->is_synchronizing(prev))
return prev;
if (prev == NULL)
return;
- node = prev->get_node();
+ node = prev->get_node()->get_parent();
while (!node->is_enabled(t))
t = t->get_parent();
if (node->has_been_explored(t->get_id()))
return;
+ /* Cache the latest backtracking point */
if (!next_backtrack || *prev > *next_backtrack)
next_backtrack = prev;
void ModelChecker::check_current_action(void)
{
- Node *currnode;
-
ModelAction *curr = this->current_action;
ModelAction *tmp;
current_action = NULL;
nextThread = get_next_replay_thread();
- currnode = curr->get_node();
+ Node *currnode = curr->get_node();
+ Node *parnode = currnode->get_parent();
- if (!currnode->backtrack_empty())
+ if (!parnode->backtrack_empty()||!currnode->readsfrom_empty())
if (!next_backtrack || *curr > *next_backtrack)
next_backtrack = curr;
set_backtracking(curr);
+ /* Assign reads_from values */
+ /* TODO: perform release/acquire synchronization here; include
+ * reads_from as ModelAction member? */
+ Thread *th = get_thread(curr->get_tid());
+ uint64_t value = VALUE_NONE;
+ if (curr->is_read()) {
+ const ModelAction *reads_from = curr->get_node()->get_read_from();
+ value = reads_from->get_value();
+ /* Assign reads_from, perform release/acquire synchronization */
+ curr->read_from(reads_from);
+ r_modification_order(curr,reads_from);
+ } else if (curr->is_write()) {
+ w_modification_order(curr);
+ }
+
+ th->set_return_value(value);
+
+ /* Add action to list last. */
add_action_to_lists(curr);
}
+bool ModelChecker::isfeasible() {
+ return !cyclegraph->checkForCycles();
+}
+
+void ModelChecker::r_modification_order(ModelAction * curr, const ModelAction *rf) {
+ std::vector<action_list_t> *thrd_lists = &(*obj_thrd_map)[curr->get_location()];
+ unsigned int i;
+ ASSERT(curr->is_read());
+
+ /* Iterate over all threads */
+ for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ if (act->is_read()) {
+ const ModelAction * prevreadfrom=act->get_reads_from();
+ if (rf!=prevreadfrom)
+ cyclegraph->addEdge(rf, prevreadfrom);
+ } else if (rf!=act) {
+ cyclegraph->addEdge(rf, act);
+ }
+ break;
+ }
+ }
+ }
+}
+
+void ModelChecker::w_modification_order(ModelAction * curr) {
+ std::vector<action_list_t> *thrd_lists = &(*obj_thrd_map)[curr->get_location()];
+ unsigned int i;
+ ASSERT(curr->is_write());
+
+ if (curr->is_seqcst()) {
+ /* We have to at least see the last sequentially consistent write,
+ so we are initialized. */
+ ModelAction * last_seq_cst=get_last_seq_cst(curr->get_location());
+ if (last_seq_cst!=NULL)
+ cyclegraph->addEdge(curr, last_seq_cst);
+ }
+
+ /* Iterate over all threads */
+ for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
+ action_list_t *list = &(*thrd_lists)[i];
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ if (act->is_read()) {
+ cyclegraph->addEdge(curr, act->get_reads_from());
+ } else
+ cyclegraph->addEdge(curr, act);
+ break;
+ }
+ }
+ }
+}
+
/**
* Performs various bookkeeping operations for the current ModelAction. For
* instance, adds action to the per-object, per-thread action vector and to the
*/
void ModelChecker::add_action_to_lists(ModelAction *act)
{
+ int tid = id_to_int(act->get_tid());
action_trace->push_back(act);
+ (*obj_map)[act->get_location()].push_back(act);
+
std::vector<action_list_t> *vec = &(*obj_thrd_map)[act->get_location()];
- if (id_to_int(act->get_tid()) >= (int)vec->size())
+ if (tid >= (int)vec->size())
vec->resize(next_thread_id);
- (*vec)[id_to_int(act->get_tid())].push_back(act);
+ (*vec)[tid].push_back(act);
- (*thrd_last_action)[id_to_int(act->get_tid())] = act;
+ if ((int)thrd_last_action->size() <= tid)
+ thrd_last_action->resize(get_num_threads());
+ (*thrd_last_action)[tid] = act;
}
ModelAction * ModelChecker::get_last_action(thread_id_t tid)
return (*thrd_last_action)[id_to_int(tid)];
}
+/**
+ * Gets the last memory_order_seq_cst action (in the total global sequence)
+ * performed on a particular object (i.e., memory location).
+ * @param location The object location to check
+ * @return The last seq_cst action performed
+ */
+ModelAction * ModelChecker::get_last_seq_cst(const void *location)
+{
+ action_list_t *list = &(*obj_map)[location];
+ /* Find: max({i in dom(S) | seq_cst(t_i) && isWrite(t_i) && samevar(t_i, t)}) */
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++)
+ if ((*rit)->is_write() && (*rit)->is_seqcst())
+ return *rit;
+ return NULL;
+}
+
ModelAction * ModelChecker::get_parent_action(thread_id_t tid)
{
ModelAction *parent = get_last_action(tid);
return parent;
}
+ClockVector * ModelChecker::get_cv(thread_id_t tid) {
+ return get_parent_action(tid)->get_cv();
+}
+
/**
* Build up an initial set of all past writes that this 'read' action may read
* from. This set is determined by the clock vector's "happens before"
{
std::vector<action_list_t> *thrd_lists = &(*obj_thrd_map)[curr->get_location()];
unsigned int i;
-
ASSERT(curr->is_read());
+ ModelAction *last_seq_cst = NULL;
+
+ /* Track whether this object has been initialized */
+ bool initialized = false;
+
+ if (curr->is_seqcst()) {
+ last_seq_cst = get_last_seq_cst(curr->get_location());
+ /* We have to at least see the last sequentially consistent write,
+ so we are initialized. */
+ if (last_seq_cst != NULL)
+ initialized = true;
+ }
+
+ /* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
+ /* Iterate over actions in thread, starting from most recent */
action_list_t *list = &(*thrd_lists)[i];
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
if (!act->is_write())
continue;
- DEBUG("Adding action to may_read_from:\n");
- if (DBG_ENABLED()) {
- act->print();
- curr->print();
+ /* Don't consider more than one seq_cst write if we are a seq_cst read. */
+ if (!act->is_seqcst() || !curr->is_seqcst() || act == last_seq_cst) {
+ DEBUG("Adding action to may_read_from:\n");
+ if (DBG_ENABLED()) {
+ act->print();
+ curr->print();
+ }
+ curr->get_node()->add_read_from(act);
}
- curr->get_node()->add_read_from(act);
- /* Include at most one act that "happens before" curr */
- if (act->happens_before(curr))
+ /* Include at most one act per-thread that "happens before" curr */
+ if (act->happens_before(curr)) {
+ initialized = true;
break;
+ }
}
}
-}
-void ModelChecker::print_summary(void)
-{
- printf("\n");
- printf("Number of executions: %d\n", num_executions);
- printf("Total nodes created: %d\n", node_stack->get_total_nodes());
-
- scheduler->print();
-
- print_list(action_trace);
- printf("\n");
+ if (!initialized) {
+ /* TODO: need a more informative way of reporting errors */
+ printf("ERROR: may read from uninitialized atomic\n");
+ }
+
+ if (DBG_ENABLED() || !initialized) {
+ printf("Reached read action:\n");
+ curr->print();
+ printf("Printing may_read_from\n");
+ curr->get_node()->print_may_read_from();
+ printf("End printing may_read_from\n");
+ }
+
+ ASSERT(initialized);
}
-void ModelChecker::print_list(action_list_t *list)
+static void print_list(action_list_t *list)
{
action_list_t::iterator it;
printf("---------------------------------------------------------------------\n");
}
+void ModelChecker::print_summary(void)
+{
+ if (!isfeasible()) {
+ if (DBG_ENABLED())
+ printf("INFEASIBLE EXECUTION!\n");
+ else
+ return;
+ }
+
+ printf("\n");
+ printf("Number of executions: %d\n", num_executions);
+ printf("Total nodes created: %d\n", node_stack->get_total_nodes());
+
+
+ scheduler->print();
+
+ print_list(action_trace);
+ printf("\n");
+}
+
int ModelChecker::add_thread(Thread *t)
{
(*thread_map)[id_to_int(t->get_id())] = t;
scheduler->remove_thread(t);
}
+/**
+ * Switch from a user-context to the "master thread" context (a.k.a. system
+ * context). This switch is made with the intention of exploring a particular
+ * model-checking action (described by a ModelAction object). Must be called
+ * from a user-thread context.
+ * @param act The current action that will be explored. May be NULL, although
+ * there is little reason to switch to the model-checker without an action to
+ * explore (note: act == NULL is sometimes used as a hack to allow a thread to
+ * yield control without performing any progress; see thrd_join()).
+ * @return Return status from the 'swap' call (i.e., success/fail, 0/-1)
+ */
int ModelChecker::switch_to_master(ModelAction *act)
{
Thread *old;
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