#include <stdio.h>
#include <algorithm>
#include <mutex>
+#include <new>
#include "model.h"
#include "action.h"
#include "promise.h"
#include "datarace.h"
#include "threads-model.h"
+#include "output.h"
#define INITIAL_THREAD_ID 0
ModelChecker *model;
+struct bug_message {
+ bug_message(const char *str) {
+ const char *fmt = " [BUG] %s\n";
+ msg = (char *)snapshot_malloc(strlen(fmt) + strlen(str));
+ sprintf(msg, fmt, str);
+ }
+ ~bug_message() { if (msg) snapshot_free(msg); }
+
+ char *msg;
+ void print() { model_print("%s", msg); }
+
+ SNAPSHOTALLOC
+};
+
+/**
+ * Structure for holding small ModelChecker members that should be snapshotted
+ */
+struct model_snapshot_members {
+ model_snapshot_members() :
+ /* First thread created will have id INITIAL_THREAD_ID */
+ next_thread_id(INITIAL_THREAD_ID),
+ used_sequence_numbers(0),
+ next_backtrack(NULL),
+ bugs(),
+ stats(),
+ failed_promise(false),
+ too_many_reads(false),
+ no_valid_reads(false),
+ bad_synchronization(false),
+ asserted(false)
+ { }
+
+ ~model_snapshot_members() {
+ for (unsigned int i = 0; i < bugs.size(); i++)
+ delete bugs[i];
+ bugs.clear();
+ }
+
+ unsigned int next_thread_id;
+ modelclock_t used_sequence_numbers;
+ ModelAction *next_backtrack;
+ std::vector< bug_message *, SnapshotAlloc<bug_message *> > bugs;
+ struct execution_stats stats;
+ bool failed_promise;
+ bool too_many_reads;
+ bool no_valid_reads;
+ /** @brief Incorrectly-ordered synchronization was made */
+ bool bad_synchronization;
+ bool asserted;
+
+ SNAPSHOTALLOC
+};
+
/** @brief Constructor */
ModelChecker::ModelChecker(struct model_params params) :
/* Initialize default scheduler */
params(params),
scheduler(new Scheduler()),
- num_executions(0),
- num_feasible_executions(0),
diverge(NULL),
earliest_diverge(NULL),
action_trace(new action_list_t()),
thread_map(new HashTable<int, Thread *, int>()),
- obj_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
- lock_waiters_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
- condvar_waiters_map(new HashTable<const void *, action_list_t, uintptr_t, 4>()),
- obj_thrd_map(new HashTable<void *, std::vector<action_list_t>, uintptr_t, 4 >()),
+ obj_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
+ lock_waiters_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
+ condvar_waiters_map(new HashTable<const void *, action_list_t *, uintptr_t, 4>()),
+ obj_thrd_map(new HashTable<void *, std::vector<action_list_t> *, uintptr_t, 4 >()),
promises(new std::vector< Promise *, SnapshotAlloc<Promise *> >()),
futurevalues(new std::vector< struct PendingFutureValue, SnapshotAlloc<struct PendingFutureValue> >()),
pending_rel_seqs(new std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >()),
thrd_last_action(new std::vector< ModelAction *, SnapshotAlloc<ModelAction *> >(1)),
+ thrd_last_fence_release(new std::vector< ModelAction *, SnapshotAlloc<ModelAction *> >()),
node_stack(new NodeStack()),
- mo_graph(new CycleGraph()),
- failed_promise(false),
- too_many_reads(false),
- asserted(false),
- bad_synchronization(false)
+ priv(new struct model_snapshot_members()),
+ mo_graph(new CycleGraph())
{
- /* Allocate this "size" on the snapshotting heap */
- priv = (struct model_snapshot_members *)calloc(1, sizeof(*priv));
- /* First thread created will have id INITIAL_THREAD_ID */
- priv->next_thread_id = INITIAL_THREAD_ID;
-
/* Initialize a model-checker thread, for special ModelActions */
model_thread = new Thread(get_next_id());
thread_map->put(id_to_int(model_thread->get_id()), model_thread);
delete pending_rel_seqs;
delete thrd_last_action;
+ delete thrd_last_fence_release;
delete node_stack;
delete scheduler;
delete mo_graph;
+ delete priv;
+}
+
+static action_list_t * get_safe_ptr_action(HashTable<const void *, action_list_t *, uintptr_t, 4> * hash, void * ptr)
+{
+ action_list_t *tmp = hash->get(ptr);
+ if (tmp == NULL) {
+ tmp = new action_list_t();
+ hash->put(ptr, tmp);
+ }
+ return tmp;
+}
+
+static std::vector<action_list_t> * get_safe_ptr_vect_action(HashTable<void *, std::vector<action_list_t> *, uintptr_t, 4> * hash, void * ptr)
+{
+ std::vector<action_list_t> *tmp = hash->get(ptr);
+ if (tmp == NULL) {
+ tmp = new std::vector<action_list_t>();
+ hash->put(ptr, tmp);
+ }
+ return tmp;
}
/**
{
DEBUG("+++ Resetting to initial state +++\n");
node_stack->reset_execution();
- failed_promise = false;
- too_many_reads = false;
- bad_synchronization = false;
- reset_asserted();
- snapshotObject->backTrackBeforeStep(0);
+
+ /* Print all model-checker output before rollback */
+ fflush(model_out);
+
+ /**
+ * FIXME: if we utilize partial rollback, we will need to free only
+ * those pending actions which were NOT pending before the rollback
+ * point
+ */
+ for (unsigned int i = 0; i < get_num_threads(); i++)
+ delete get_thread(int_to_id(i))->get_pending();
+
+ snapshot_backtrack_before(0);
}
/** @return a thread ID for a new Thread */
}
/** @return the number of user threads created during this execution */
-unsigned int ModelChecker::get_num_threads()
+unsigned int ModelChecker::get_num_threads() const
{
return priv->next_thread_id;
}
-/** @return The currently executing Thread. */
-Thread * ModelChecker::get_current_thread()
+/**
+ * Must be called from user-thread context (e.g., through the global
+ * thread_current() interface)
+ *
+ * @return The currently executing Thread.
+ */
+Thread * ModelChecker::get_current_thread() const
{
return scheduler->get_current_thread();
}
return ++priv->used_sequence_numbers;
}
-Node * ModelChecker::get_curr_node() {
+Node * ModelChecker::get_curr_node() const
+{
return node_stack->get_head();
}
* adjacency of read/write portions of a RMW action, force THREAD_CREATE to be
* followed by a THREAD_START, or it can enforce execution replay/backtracking.
* The model-checker may have no preference regarding the next thread (i.e.,
- * when exploring a new execution ordering), in which case this will return
- * NULL.
- * @param curr The current ModelAction. This action might guide the choice of
- * next thread.
- * @return The next thread to run. If the model-checker has no preference, NULL.
+ * when exploring a new execution ordering), in which case we defer to the
+ * scheduler.
+ *
+ * @param curr Optional: The current ModelAction. Only used if non-NULL and it
+ * might guide the choice of next thread (i.e., THREAD_CREATE should be
+ * followed by THREAD_START, or ATOMIC_RMWR followed by ATOMIC_{RMW,RMWC})
+ * @return The next chosen thread to run, if any exist. Or else if no threads
+ * remain to be executed, return NULL.
*/
Thread * ModelChecker::get_next_thread(ModelAction *curr)
{
thread_id_t tid;
- if (curr!=NULL) {
+ if (curr != NULL) {
/* Do not split atomic actions. */
if (curr->is_rmwr())
- return thread_current();
- /* The THREAD_CREATE action points to the created Thread */
+ return get_thread(curr);
else if (curr->get_type() == THREAD_CREATE)
- return (Thread *)curr->get_location();
+ return curr->get_thread_operand();
}
- /* Have we completed exploring the preselected path? */
+ /*
+ * Have we completed exploring the preselected path? Then let the
+ * scheduler decide
+ */
if (diverge == NULL)
- return NULL;
+ return scheduler->select_next_thread();
/* Else, we are trying to replay an execution */
ModelAction *next = node_stack->get_next()->get_action();
if (next == diverge) {
if (earliest_diverge == NULL || *diverge < *earliest_diverge)
- earliest_diverge=diverge;
+ earliest_diverge = diverge;
Node *nextnode = next->get_node();
Node *prevnode = nextnode->get_parent();
/* The next node will read from a different value. */
tid = next->get_tid();
node_stack->pop_restofstack(2);
- } else if (nextnode->increment_future_value()) {
- /* The next node will try to read from a different future value. */
- tid = next->get_tid();
- node_stack->pop_restofstack(2);
} else if (nextnode->increment_relseq_break()) {
/* The next node will try to resolve a release sequence differently */
tid = next->get_tid();
node_stack->pop_restofstack(2);
} else {
+ ASSERT(prevnode);
/* Make a different thread execute for next step */
- scheduler->add_sleep(thread_map->get(id_to_int(next->get_tid())));
+ scheduler->add_sleep(get_thread(next->get_tid()));
tid = prevnode->get_next_backtrack();
/* Make sure the backtracked thread isn't sleeping. */
node_stack->pop_restofstack(1);
- if (diverge==earliest_diverge) {
- earliest_diverge=prevnode->get_action();
+ if (diverge == earliest_diverge) {
+ earliest_diverge = prevnode->get_action();
}
}
+ /* Start the round robin scheduler from this thread id */
+ scheduler->set_scheduler_thread(tid);
/* The correct sleep set is in the parent node. */
execute_sleep_set();
return thread_map->get(id_to_int(tid));
}
-/**
+/**
* We need to know what the next actions of all threads in the sleep
* set will be. This method computes them and stores the actions at
* the corresponding thread object's pending action.
*/
-void ModelChecker::execute_sleep_set() {
- for(unsigned int i=0;i<get_num_threads();i++) {
- thread_id_t tid=int_to_id(i);
- Thread *thr=get_thread(tid);
- if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
- thr->set_state(THREAD_RUNNING);
- scheduler->next_thread(thr);
- Thread::swap(&system_context, thr);
- priv->current_action->set_sleep_flag();
- thr->set_pending(priv->current_action);
+void ModelChecker::execute_sleep_set()
+{
+ for (unsigned int i = 0; i < get_num_threads(); i++) {
+ thread_id_t tid = int_to_id(i);
+ Thread *thr = get_thread(tid);
+ if (scheduler->is_sleep_set(thr) && thr->get_pending()) {
+ thr->get_pending()->set_sleep_flag();
}
}
- priv->current_action = NULL;
}
-void ModelChecker::wake_up_sleeping_actions(ModelAction * curr) {
- for(unsigned int i=0;i<get_num_threads();i++) {
- thread_id_t tid=int_to_id(i);
- Thread *thr=get_thread(tid);
- if ( scheduler->get_enabled(thr) == THREAD_SLEEP_SET ) {
- ModelAction *pending_act=thr->get_pending();
- if ((!curr->is_rmwr())&&pending_act->could_synchronize_with(curr)) {
- //Remove this thread from sleep set
+/**
+ * @brief Should the current action wake up a given thread?
+ *
+ * @param curr The current action
+ * @param thread The thread that we might wake up
+ * @return True, if we should wake up the sleeping thread; false otherwise
+ */
+bool ModelChecker::should_wake_up(const ModelAction *curr, const Thread *thread) const
+{
+ const ModelAction *asleep = thread->get_pending();
+ /* Don't allow partial RMW to wake anyone up */
+ if (curr->is_rmwr())
+ return false;
+ /* Synchronizing actions may have been backtracked */
+ if (asleep->could_synchronize_with(curr))
+ return true;
+ /* All acquire/release fences and fence-acquire/store-release */
+ if (asleep->is_fence() && asleep->is_acquire() && curr->is_release())
+ return true;
+ /* Fence-release + store can awake load-acquire on the same location */
+ if (asleep->is_read() && asleep->is_acquire() && curr->same_var(asleep) && curr->is_write()) {
+ ModelAction *fence_release = get_last_fence_release(curr->get_tid());
+ if (fence_release && *(get_last_action(thread->get_id())) < *fence_release)
+ return true;
+ }
+ return false;
+}
+
+void ModelChecker::wake_up_sleeping_actions(ModelAction *curr)
+{
+ for (unsigned int i = 0; i < get_num_threads(); i++) {
+ Thread *thr = get_thread(int_to_id(i));
+ if (scheduler->is_sleep_set(thr)) {
+ if (should_wake_up(curr, thr))
+ /* Remove this thread from sleep set */
scheduler->remove_sleep(thr);
- }
}
- }
+ }
+}
+
+/** @brief Alert the model-checker that an incorrectly-ordered
+ * synchronization was made */
+void ModelChecker::set_bad_synchronization()
+{
+ priv->bad_synchronization = true;
+}
+
+/**
+ * Check whether the current trace has triggered an assertion which should halt
+ * its execution.
+ *
+ * @return True, if the execution should be aborted; false otherwise
+ */
+bool ModelChecker::has_asserted() const
+{
+ return priv->asserted;
+}
+
+/**
+ * Trigger a trace assertion which should cause this execution to be halted.
+ * This can be due to a detected bug or due to an infeasibility that should
+ * halt ASAP.
+ */
+void ModelChecker::set_assert()
+{
+ priv->asserted = true;
+}
+
+/**
+ * Check if we are in a deadlock. Should only be called at the end of an
+ * execution, although it should not give false positives in the middle of an
+ * execution (there should be some ENABLED thread).
+ *
+ * @return True if program is in a deadlock; false otherwise
+ */
+bool ModelChecker::is_deadlocked() const
+{
+ bool blocking_threads = false;
+ for (unsigned int i = 0; i < get_num_threads(); i++) {
+ thread_id_t tid = int_to_id(i);
+ if (is_enabled(tid))
+ return false;
+ Thread *t = get_thread(tid);
+ if (!t->is_model_thread() && t->get_pending())
+ blocking_threads = true;
+ }
+ return blocking_threads;
+}
+
+/**
+ * Check if this is a complete execution. That is, have all thread completed
+ * execution (rather than exiting because sleep sets have forced a redundant
+ * execution).
+ *
+ * @return True if the execution is complete.
+ */
+bool ModelChecker::is_complete_execution() const
+{
+ for (unsigned int i = 0; i < get_num_threads(); i++)
+ if (is_enabled(int_to_id(i)))
+ return false;
+ return true;
+}
+
+/**
+ * @brief Assert a bug in the executing program.
+ *
+ * Use this function to assert any sort of bug in the user program. If the
+ * current trace is feasible (actually, a prefix of some feasible execution),
+ * then this execution will be aborted, printing the appropriate message. If
+ * the current trace is not yet feasible, the error message will be stashed and
+ * printed if the execution ever becomes feasible.
+ *
+ * @param msg Descriptive message for the bug (do not include newline char)
+ * @return True if bug is immediately-feasible
+ */
+bool ModelChecker::assert_bug(const char *msg)
+{
+ priv->bugs.push_back(new bug_message(msg));
+
+ if (isfeasibleprefix()) {
+ set_assert();
+ return true;
+ }
+ return false;
+}
+
+/**
+ * @brief Assert a bug in the executing program, asserted by a user thread
+ * @see ModelChecker::assert_bug
+ * @param msg Descriptive message for the bug (do not include newline char)
+ */
+void ModelChecker::assert_user_bug(const char *msg)
+{
+ /* If feasible bug, bail out now */
+ if (assert_bug(msg))
+ switch_to_master(NULL);
+}
+
+/** @return True, if any bugs have been reported for this execution */
+bool ModelChecker::have_bug_reports() const
+{
+ return priv->bugs.size() != 0;
+}
+
+/** @brief Print bug report listing for this execution (if any bugs exist) */
+void ModelChecker::print_bugs() const
+{
+ if (have_bug_reports()) {
+ model_print("Bug report: %zu bug%s detected\n",
+ priv->bugs.size(),
+ priv->bugs.size() > 1 ? "s" : "");
+ for (unsigned int i = 0; i < priv->bugs.size(); i++)
+ priv->bugs[i]->print();
+ }
+}
+
+/**
+ * @brief Record end-of-execution stats
+ *
+ * Must be run when exiting an execution. Records various stats.
+ * @see struct execution_stats
+ */
+void ModelChecker::record_stats()
+{
+ stats.num_total++;
+ if (!isfeasibleprefix())
+ stats.num_infeasible++;
+ else if (have_bug_reports())
+ stats.num_buggy_executions++;
+ else if (is_complete_execution())
+ stats.num_complete++;
+ else if (scheduler->all_threads_sleeping())
+ stats.num_redundant++;
+ else
+ ASSERT(false);
+}
+
+/** @brief Print execution stats */
+void ModelChecker::print_stats() const
+{
+ model_print("Number of complete, bug-free executions: %d\n", stats.num_complete);
+ model_print("Number of redundant executions: %d\n", stats.num_redundant);
+ model_print("Number of buggy executions: %d\n", stats.num_buggy_executions);
+ model_print("Number of infeasible executions: %d\n", stats.num_infeasible);
+ model_print("Total executions: %d\n", stats.num_total);
+ model_print("Total nodes created: %d\n", node_stack->get_total_nodes());
+}
+
+/**
+ * @brief End-of-exeuction print
+ * @param printbugs Should any existing bugs be printed?
+ */
+void ModelChecker::print_execution(bool printbugs) const
+{
+ print_program_output();
+
+ if (DBG_ENABLED() || params.verbose) {
+ model_print("Earliest divergence point since last feasible execution:\n");
+ if (earliest_diverge)
+ earliest_diverge->print();
+ else
+ model_print("(Not set)\n");
+
+ model_print("\n");
+ print_stats();
+ }
+
+ /* Don't print invalid bugs */
+ if (printbugs)
+ print_bugs();
+
+ model_print("\n");
+ print_summary();
}
/**
bool ModelChecker::next_execution()
{
DBG();
+ /* Is this execution a feasible execution that's worth bug-checking? */
+ bool complete = isfeasibleprefix() && (is_complete_execution() ||
+ have_bug_reports());
- num_executions++;
+ /* End-of-execution bug checks */
+ if (complete) {
+ if (is_deadlocked())
+ assert_bug("Deadlock detected");
- if (isfinalfeasible()) {
- printf("Earliest divergence point since last feasible execution:\n");
- if (earliest_diverge)
- earliest_diverge->print();
- else
- printf("(Not set)\n");
-
- earliest_diverge = NULL;
- num_feasible_executions++;
+ checkDataRaces();
}
- DEBUG("Number of acquires waiting on pending release sequences: %zu\n",
- pending_rel_seqs->size());
+ record_stats();
+ /* Output */
+ if (DBG_ENABLED() || params.verbose || (complete && have_bug_reports()))
+ print_execution(complete);
+ else
+ clear_program_output();
- if (isfinalfeasible() || (params.bound != 0 && priv->used_sequence_numbers > params.bound ) || DBG_ENABLED() )
- print_summary();
+ if (complete)
+ earliest_diverge = NULL;
if ((diverge = get_next_backtrack()) == NULL)
return false;
if (DBG_ENABLED()) {
- printf("Next execution will diverge at:\n");
+ model_print("Next execution will diverge at:\n");
diverge->print();
}
return true;
}
-ModelAction * ModelChecker::get_last_conflict(ModelAction *act)
+/**
+ * @brief Find the last fence-related backtracking conflict for a ModelAction
+ *
+ * This function performs the search for the most recent conflicting action
+ * against which we should perform backtracking, as affected by fence
+ * operations. This includes pairs of potentially-synchronizing actions which
+ * occur due to fence-acquire or fence-release, and hence should be explored in
+ * the opposite execution order.
+ *
+ * @param act The current action
+ * @return The most recent action which conflicts with act due to fences
+ */
+ModelAction * ModelChecker::get_last_fence_conflict(ModelAction *act) const
+{
+ /* Only perform release/acquire fence backtracking for stores */
+ if (!act->is_write())
+ return NULL;
+
+ /* Find a fence-release (or, act is a release) */
+ ModelAction *last_release;
+ if (act->is_release())
+ last_release = act;
+ else
+ last_release = get_last_fence_release(act->get_tid());
+ if (!last_release)
+ return NULL;
+
+ /* Skip past the release */
+ action_list_t *list = action_trace;
+ action_list_t::reverse_iterator rit;
+ for (rit = list->rbegin(); rit != list->rend(); rit++)
+ if (*rit == last_release)
+ break;
+ ASSERT(rit != list->rend());
+
+ /* Find a prior:
+ * load-acquire
+ * or
+ * load --sb-> fence-acquire */
+ std::vector< ModelAction *, ModelAlloc<ModelAction *> > acquire_fences(get_num_threads(), NULL);
+ std::vector< ModelAction *, ModelAlloc<ModelAction *> > prior_loads(get_num_threads(), NULL);
+ bool found_acquire_fences = false;
+ for ( ; rit != list->rend(); rit++) {
+ ModelAction *prev = *rit;
+ if (act->same_thread(prev))
+ continue;
+
+ int tid = id_to_int(prev->get_tid());
+
+ if (prev->is_read() && act->same_var(prev)) {
+ if (prev->is_acquire()) {
+ /* Found most recent load-acquire, don't need
+ * to search for more fences */
+ if (!found_acquire_fences)
+ return NULL;
+ } else {
+ prior_loads[tid] = prev;
+ }
+ }
+ if (prev->is_acquire() && prev->is_fence() && !acquire_fences[tid]) {
+ found_acquire_fences = true;
+ acquire_fences[tid] = prev;
+ }
+ }
+
+ ModelAction *latest_backtrack = NULL;
+ for (unsigned int i = 0; i < acquire_fences.size(); i++)
+ if (acquire_fences[i] && prior_loads[i])
+ if (!latest_backtrack || *latest_backtrack < *acquire_fences[i])
+ latest_backtrack = acquire_fences[i];
+ return latest_backtrack;
+}
+
+/**
+ * @brief Find the last backtracking conflict for a ModelAction
+ *
+ * This function performs the search for the most recent conflicting action
+ * against which we should perform backtracking. This primary includes pairs of
+ * synchronizing actions which should be explored in the opposite execution
+ * order.
+ *
+ * @param act The current action
+ * @return The most recent action which conflicts with act
+ */
+ModelAction * ModelChecker::get_last_conflict(ModelAction *act) const
{
switch (act->get_type()) {
+ /* case ATOMIC_FENCE: fences don't directly cause backtracking */
case ATOMIC_READ:
case ATOMIC_WRITE:
case ATOMIC_RMW: {
+ ModelAction *ret = NULL;
+
/* linear search: from most recent to oldest */
- action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (prev->could_synchronize_with(act))
- return prev;
+ if (prev->could_synchronize_with(act)) {
+ ret = prev;
+ break;
+ }
}
- break;
+
+ ModelAction *ret2 = get_last_fence_conflict(act);
+ if (!ret2)
+ return ret;
+ if (!ret)
+ return ret2;
+ if (*ret < *ret2)
+ return ret2;
+ return ret;
}
case ATOMIC_LOCK:
case ATOMIC_TRYLOCK: {
/* linear search: from most recent to oldest */
- action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
}
case ATOMIC_UNLOCK: {
/* linear search: from most recent to oldest */
- action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (!act->same_thread(prev)&&prev->is_failed_trylock())
+ if (!act->same_thread(prev) && prev->is_failed_trylock())
return prev;
}
break;
}
case ATOMIC_WAIT: {
/* linear search: from most recent to oldest */
- action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (!act->same_thread(prev)&&prev->is_failed_trylock())
+ if (!act->same_thread(prev) && prev->is_failed_trylock())
return prev;
- if (!act->same_thread(prev)&&prev->is_notify())
+ if (!act->same_thread(prev) && prev->is_notify())
return prev;
}
break;
case ATOMIC_NOTIFY_ALL:
case ATOMIC_NOTIFY_ONE: {
/* linear search: from most recent to oldest */
- action_list_t *list = obj_map->get_safe_ptr(act->get_location());
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *prev = *rit;
- if (!act->same_thread(prev)&&prev->is_wait())
+ if (!act->same_thread(prev) && prev->is_wait())
return prev;
}
break;
void ModelChecker::set_backtracking(ModelAction *act)
{
Thread *t = get_thread(act);
- ModelAction * prev = get_last_conflict(act);
+ ModelAction *prev = get_last_conflict(act);
if (prev == NULL)
return;
- Node * node = prev->get_node()->get_parent();
+ Node *node = prev->get_node()->get_parent();
int low_tid, high_tid;
- if (node->is_enabled(t)) {
+ if (node->enabled_status(t->get_id()) == THREAD_ENABLED) {
low_tid = id_to_int(act->get_tid());
- high_tid = low_tid+1;
+ high_tid = low_tid + 1;
} else {
low_tid = 0;
high_tid = get_num_threads();
}
- for(int i = low_tid; i < high_tid; i++) {
+ for (int i = low_tid; i < high_tid; i++) {
thread_id_t tid = int_to_id(i);
/* Make sure this thread can be enabled here. */
break;
/* Don't backtrack into a point where the thread is disabled or sleeping. */
- if (node->enabled_status(tid)!=THREAD_ENABLED)
+ if (node->enabled_status(tid) != THREAD_ENABLED)
continue;
-
+
/* Check if this has been explored already */
if (node->has_been_explored(tid))
continue;
/* See if fairness allows */
if (model->params.fairwindow != 0 && !node->has_priority(tid)) {
- bool unfair=false;
- for(int t=0;t<node->get_num_threads();t++) {
- thread_id_t tother=int_to_id(t);
+ bool unfair = false;
+ for (int t = 0; t < node->get_num_threads(); t++) {
+ thread_id_t tother = int_to_id(t);
if (node->is_enabled(tother) && node->has_priority(tother)) {
- unfair=true;
+ unfair = true;
break;
}
}
continue;
}
/* Cache the latest backtracking point */
- if (!priv->next_backtrack || *prev > *priv->next_backtrack)
- priv->next_backtrack = prev;
+ set_latest_backtrack(prev);
/* If this is a new backtracking point, mark the tree */
if (!node->set_backtrack(tid))
}
}
+/**
+ * @brief Cache the a backtracking point as the "most recent", if eligible
+ *
+ * Note that this does not prepare the NodeStack for this backtracking
+ * operation, it only caches the action on a per-execution basis
+ *
+ * @param act The operation at which we should explore a different next action
+ * (i.e., backtracking point)
+ * @return True, if this action is now the most recent backtracking point;
+ * false otherwise
+ */
+bool ModelChecker::set_latest_backtrack(ModelAction *act)
+{
+ if (!priv->next_backtrack || *act > *priv->next_backtrack) {
+ priv->next_backtrack = act;
+ return true;
+ }
+ return false;
+}
+
/**
* Returns last backtracking point. The model checker will explore a different
* path for this point in the next execution.
}
/**
- * Processes a read or rmw model action.
+ * Processes a read model action.
* @param curr is the read model action to process.
- * @param second_part_of_rmw is boolean that is true is this is the second action of a rmw.
* @return True if processing this read updates the mo_graph.
*/
-bool ModelChecker::process_read(ModelAction *curr, bool second_part_of_rmw)
+bool ModelChecker::process_read(ModelAction *curr)
{
+ Node *node = curr->get_node();
uint64_t value = VALUE_NONE;
bool updated = false;
while (true) {
- const ModelAction *reads_from = curr->get_node()->get_read_from();
- if (reads_from != NULL) {
- mo_graph->startChanges();
-
- value = reads_from->get_value();
- bool r_status = false;
-
- if (!second_part_of_rmw) {
- check_recency(curr, reads_from);
- r_status = r_modification_order(curr, reads_from);
- }
+ switch (node->get_read_from_status()) {
+ case READ_FROM_PAST: {
+ const ModelAction *rf = node->get_read_from_past();
+ ASSERT(rf);
+ mo_graph->startChanges();
+ value = rf->get_value();
+ check_recency(curr, rf);
+ bool r_status = r_modification_order(curr, rf);
- if (!second_part_of_rmw&&!isfeasible()&&(curr->get_node()->increment_read_from()||curr->get_node()->increment_future_value())) {
+ if (is_infeasible() && node->increment_read_from()) {
mo_graph->rollbackChanges();
- too_many_reads = false;
+ priv->too_many_reads = false;
continue;
}
- curr->read_from(reads_from);
+ read_from(curr, rf);
mo_graph->commitChanges();
- mo_check_promises(curr->get_tid(), reads_from);
+ mo_check_promises(curr, true);
updated |= r_status;
- } else if (!second_part_of_rmw) {
+ break;
+ }
+ case READ_FROM_PROMISE: {
+ Promise *promise = curr->get_node()->get_read_from_promise();
+ promise->add_reader(curr);
+ value = promise->get_value();
+ curr->set_read_from_promise(promise);
+ mo_graph->startChanges();
+ updated = r_modification_order(curr, promise);
+ mo_graph->commitChanges();
+ break;
+ }
+ case READ_FROM_FUTURE: {
/* Read from future value */
- value = curr->get_node()->get_future_value();
- modelclock_t expiration = curr->get_node()->get_future_value_expiration();
- curr->read_from(NULL);
- Promise *valuepromise = new Promise(curr, value, expiration);
- promises->push_back(valuepromise);
+ struct future_value fv = node->get_future_value();
+ Promise *promise = new Promise(curr, fv);
+ value = fv.value;
+ curr->set_read_from_promise(promise);
+ promises->push_back(promise);
+ mo_graph->startChanges();
+ updated = r_modification_order(curr, promise);
+ mo_graph->commitChanges();
+ break;
+ }
+ default:
+ ASSERT(false);
}
get_thread(curr)->set_return_value(value);
return updated;
*
* @return True if synchronization was updated; false otherwise
*/
-bool ModelChecker::process_mutex(ModelAction *curr) {
- std::mutex *mutex=NULL;
- struct std::mutex_state *state=NULL;
+bool ModelChecker::process_mutex(ModelAction *curr)
+{
+ std::mutex *mutex = NULL;
+ struct std::mutex_state *state = NULL;
if (curr->is_trylock() || curr->is_lock() || curr->is_unlock()) {
mutex = (std::mutex *)curr->get_location();
state = mutex->get_state();
- } else if(curr->is_wait()) {
+ } else if (curr->is_wait()) {
mutex = (std::mutex *)curr->get_value();
state = mutex->get_state();
}
}
//otherwise fall into the lock case
case ATOMIC_LOCK: {
- if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock) {
- printf("Lock access before initialization\n");
- set_assert();
- }
+ if (curr->get_cv()->getClock(state->alloc_tid) <= state->alloc_clock)
+ assert_bug("Lock access before initialization");
state->islocked = true;
ModelAction *unlock = get_last_unlock(curr);
//synchronize with the previous unlock statement
//unlock the lock
state->islocked = false;
//wake up the other threads
- action_list_t *waiters = lock_waiters_map->get_safe_ptr(curr->get_location());
+ action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, curr->get_location());
//activate all the waiting threads
for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
scheduler->wake(get_thread(*rit));
//unlock the lock
state->islocked = false;
//wake up the other threads
- action_list_t *waiters = lock_waiters_map->get_safe_ptr((void *) curr->get_value());
+ action_list_t *waiters = get_safe_ptr_action(lock_waiters_map, (void *) curr->get_value());
//activate all the waiting threads
for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
scheduler->wake(get_thread(*rit));
}
waiters->clear();
//check whether we should go to sleep or not...simulate spurious failures
- if (curr->get_node()->get_misc()==0) {
- condvar_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr);
+ if (curr->get_node()->get_misc() == 0) {
+ get_safe_ptr_action(condvar_waiters_map, curr->get_location())->push_back(curr);
//disable us
- scheduler->sleep(get_current_thread());
+ scheduler->sleep(get_thread(curr));
}
break;
}
case ATOMIC_NOTIFY_ALL: {
- action_list_t *waiters = condvar_waiters_map->get_safe_ptr(curr->get_location());
+ action_list_t *waiters = get_safe_ptr_action(condvar_waiters_map, curr->get_location());
//activate all the waiting threads
for (action_list_t::iterator rit = waiters->begin(); rit != waiters->end(); rit++) {
scheduler->wake(get_thread(*rit));
break;
}
case ATOMIC_NOTIFY_ONE: {
- action_list_t *waiters = condvar_waiters_map->get_safe_ptr(curr->get_location());
- int wakeupthread=curr->get_node()->get_misc();
+ action_list_t *waiters = get_safe_ptr_action(condvar_waiters_map, curr->get_location());
+ int wakeupthread = curr->get_node()->get_misc();
action_list_t::iterator it = waiters->begin();
advance(it, wakeupthread);
scheduler->wake(get_thread(*it));
return false;
}
+void ModelChecker::add_future_value(const ModelAction *writer, ModelAction *reader)
+{
+ /* Do more ambitious checks now that mo is more complete */
+ if (mo_may_allow(writer, reader)) {
+ Node *node = reader->get_node();
+
+ /* Find an ancestor thread which exists at the time of the reader */
+ Thread *write_thread = get_thread(writer);
+ while (id_to_int(write_thread->get_id()) >= node->get_num_threads())
+ write_thread = write_thread->get_parent();
+
+ struct future_value fv = {
+ writer->get_value(),
+ writer->get_seq_number() + params.maxfuturedelay,
+ write_thread->get_id(),
+ };
+ if (node->add_future_value(fv))
+ set_latest_backtrack(reader);
+ }
+}
+
/**
* Process a write ModelAction
* @param curr The ModelAction to process
if (promises->size() == 0) {
for (unsigned int i = 0; i < futurevalues->size(); i++) {
struct PendingFutureValue pfv = (*futurevalues)[i];
- //Do more ambitious checks now that mo is more complete
- if (mo_may_allow(pfv.writer, pfv.act)&&
- pfv.act->get_node()->add_future_value(pfv.writer->get_value(), pfv.writer->get_seq_number()+params.maxfuturedelay) &&
- (!priv->next_backtrack || *pfv.act > *priv->next_backtrack))
- priv->next_backtrack = pfv.act;
+ add_future_value(pfv.writer, pfv.act);
}
- futurevalues->resize(0);
+ futurevalues->clear();
}
mo_graph->commitChanges();
- mo_check_promises(curr->get_tid(), curr);
+ mo_check_promises(curr, false);
get_thread(curr)->set_return_value(VALUE_NONE);
return updated_mod_order || updated_promises;
}
+/**
+ * Process a fence ModelAction
+ * @param curr The ModelAction to process
+ * @return True if synchronization was updated
+ */
+bool ModelChecker::process_fence(ModelAction *curr)
+{
+ /*
+ * fence-relaxed: no-op
+ * fence-release: only log the occurence (not in this function), for
+ * use in later synchronization
+ * fence-acquire (this function): search for hypothetical release
+ * sequences
+ */
+ bool updated = false;
+ if (curr->is_acquire()) {
+ action_list_t *list = action_trace;
+ action_list_t::reverse_iterator rit;
+ /* Find X : is_read(X) && X --sb-> curr */
+ for (rit = list->rbegin(); rit != list->rend(); rit++) {
+ ModelAction *act = *rit;
+ if (act == curr)
+ continue;
+ if (act->get_tid() != curr->get_tid())
+ continue;
+ /* Stop at the beginning of the thread */
+ if (act->is_thread_start())
+ break;
+ /* Stop once we reach a prior fence-acquire */
+ if (act->is_fence() && act->is_acquire())
+ break;
+ if (!act->is_read())
+ continue;
+ /* read-acquire will find its own release sequences */
+ if (act->is_acquire())
+ continue;
+
+ /* Establish hypothetical release sequences */
+ rel_heads_list_t release_heads;
+ get_release_seq_heads(curr, act, &release_heads);
+ for (unsigned int i = 0; i < release_heads.size(); i++)
+ if (!curr->synchronize_with(release_heads[i]))
+ set_bad_synchronization();
+ if (release_heads.size() != 0)
+ updated = true;
+ }
+ }
+ return updated;
+}
+
/**
* @brief Process the current action for thread-related activity
*
switch (curr->get_type()) {
case THREAD_CREATE: {
- Thread *th = (Thread *)curr->get_location();
+ thrd_t *thrd = (thrd_t *)curr->get_location();
+ struct thread_params *params = (struct thread_params *)curr->get_value();
+ Thread *th = new Thread(thrd, params->func, params->arg, get_thread(curr));
+ add_thread(th);
th->set_creation(curr);
+ /* Promises can be satisfied by children */
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ if (promise->thread_is_available(curr->get_tid()))
+ promise->add_thread(th->get_id());
+ }
break;
}
case THREAD_JOIN: {
- Thread *blocking = (Thread *)curr->get_location();
+ Thread *blocking = curr->get_thread_operand();
ModelAction *act = get_last_action(blocking->get_id());
curr->synchronize_with(act);
updated = true; /* trigger rel-seq checks */
scheduler->wake(get_thread(act));
}
th->complete();
+ /* Completed thread can't satisfy promises */
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ if (promise->thread_is_available(th->get_id()))
+ if (promise->eliminate_thread(th->get_id()))
+ priv->failed_promise = true;
+ }
updated = true; /* trigger rel-seq checks */
break;
}
}
/* See if we have realized a data race */
- if (checkDataRaces())
- set_assert();
+ checkDataRaces();
}
/**
(*curr)->set_seq_number(get_next_seq_num());
- newcurr = node_stack->explore_action(*curr, scheduler->get_enabled());
+ newcurr = node_stack->explore_action(*curr, scheduler->get_enabled_array());
if (newcurr) {
/* First restore type and order in case of RMW operation */
if ((*curr)->is_rmwr())
/* Always compute new clock vector */
newcurr->create_cv(get_parent_action(newcurr->get_tid()));
+
+ /* Assign most recent release fence */
+ newcurr->set_last_fence_release(get_last_fence_release(newcurr->get_tid()));
+
/*
* Perform one-time actions when pushing new ModelAction onto
* NodeStack
else if (newcurr->is_wait())
newcurr->get_node()->set_misc_max(2);
else if (newcurr->is_notify_one()) {
- newcurr->get_node()->set_misc_max(condvar_waiters_map->get_safe_ptr(newcurr->get_location())->size());
+ newcurr->get_node()->set_misc_max(get_safe_ptr_action(condvar_waiters_map, newcurr->get_location())->size());
}
return true; /* This was a new ModelAction */
}
}
+/**
+ * @brief Establish reads-from relation between two actions
+ *
+ * Perform basic operations involved with establishing a concrete rf relation,
+ * including setting the ModelAction data and checking for release sequences.
+ *
+ * @param act The action that is reading (must be a read)
+ * @param rf The action from which we are reading (must be a write)
+ *
+ * @return True if this read established synchronization
+ */
+bool ModelChecker::read_from(ModelAction *act, const ModelAction *rf)
+{
+ act->set_read_from(rf);
+ if (rf != NULL && act->is_acquire()) {
+ rel_heads_list_t release_heads;
+ get_release_seq_heads(act, act, &release_heads);
+ int num_heads = release_heads.size();
+ for (unsigned int i = 0; i < release_heads.size(); i++)
+ if (!act->synchronize_with(release_heads[i])) {
+ set_bad_synchronization();
+ num_heads--;
+ }
+ return num_heads > 0;
+ }
+ return false;
+}
+
+/**
+ * Check promises and eliminate potentially-satisfying threads when a thread is
+ * blocked (e.g., join, lock). A thread which is waiting on another thread can
+ * no longer satisfy a promise generated from that thread.
+ *
+ * @param blocker The thread on which a thread is waiting
+ * @param waiting The waiting thread
+ */
+void ModelChecker::thread_blocking_check_promises(Thread *blocker, Thread *waiting)
+{
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ if (!promise->thread_is_available(waiting->get_id()))
+ continue;
+ for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+ ModelAction *reader = promise->get_reader(j);
+ if (reader->get_tid() != blocker->get_id())
+ continue;
+ if (promise->eliminate_thread(waiting->get_id())) {
+ /* Promise has failed */
+ priv->failed_promise = true;
+ } else {
+ /* Only eliminate the 'waiting' thread once */
+ return;
+ }
+ }
+ }
+}
+
/**
* @brief Check whether a model action is enabled.
*
*/
bool ModelChecker::check_action_enabled(ModelAction *curr) {
if (curr->is_lock()) {
- std::mutex * lock = (std::mutex *)curr->get_location();
- struct std::mutex_state * state = lock->get_state();
+ std::mutex *lock = (std::mutex *)curr->get_location();
+ struct std::mutex_state *state = lock->get_state();
if (state->islocked) {
//Stick the action in the appropriate waiting queue
- lock_waiters_map->get_safe_ptr(curr->get_location())->push_back(curr);
+ get_safe_ptr_action(lock_waiters_map, curr->get_location())->push_back(curr);
return false;
}
} else if (curr->get_type() == THREAD_JOIN) {
Thread *blocking = (Thread *)curr->get_location();
if (!blocking->is_complete()) {
blocking->push_wait_list(curr);
+ thread_blocking_check_promises(blocking, get_thread(curr));
return false;
}
}
* execution when running permutations of previously-observed executions.
*
* @param curr The current action to process
- * @return The next Thread that must be executed. May be NULL if ModelChecker
- * makes no choice (e.g., according to replay execution, combining RMW actions,
- * etc.)
+ * @return The ModelAction that is actually executed; may be different than
+ * curr; may be NULL, if the current action is not enabled to run
*/
-Thread * ModelChecker::check_current_action(ModelAction *curr)
+ModelAction * ModelChecker::check_current_action(ModelAction *curr)
{
ASSERT(curr);
bool second_part_of_rmw = curr->is_rmwc() || curr->is_rmw();
if (!check_action_enabled(curr)) {
/* Make the execution look like we chose to run this action
* much later, when a lock/join can succeed */
- get_current_thread()->set_pending(curr);
- scheduler->sleep(get_current_thread());
- return get_next_thread(NULL);
+ get_thread(curr)->set_pending(curr);
+ scheduler->sleep(get_thread(curr));
+ return NULL;
}
bool newly_explored = initialize_curr_action(&curr);
+ DBG();
+ if (DBG_ENABLED())
+ curr->print();
+
wake_up_sleeping_actions(curr);
/* Add the action to lists before any other model-checking tasks */
/* Build may_read_from set for newly-created actions */
if (newly_explored && curr->is_read())
- build_reads_from_past(curr);
+ build_may_read_from(curr);
/* Initialize work_queue with the "current action" work */
work_queue_t work_queue(1, CheckCurrWorkEntry(curr));
- while (!work_queue.empty()) {
+ while (!work_queue.empty() && !has_asserted()) {
WorkQueueEntry work = work_queue.front();
work_queue.pop_front();
if (process_thread_action(curr))
update_all = true;
- if (act->is_read() && process_read(act, second_part_of_rmw))
+ if (act->is_read() && !second_part_of_rmw && process_read(act))
update = true;
if (act->is_write() && process_write(act))
update = true;
+ if (act->is_fence() && process_fence(act))
+ update_all = true;
+
if (act->is_mutex_op() && process_mutex(act))
update_all = true;
if (act->is_read()) {
const ModelAction *rf = act->get_reads_from();
- if (rf != NULL && r_modification_order(act, rf))
- updated = true;
+ const Promise *promise = act->get_reads_from_promise();
+ if (rf) {
+ if (r_modification_order(act, rf))
+ updated = true;
+ } else if (promise) {
+ if (r_modification_order(act, promise))
+ updated = true;
+ }
}
if (act->is_write()) {
if (w_modification_order(act))
check_curr_backtracking(curr);
set_backtracking(curr);
- return get_next_thread(curr);
+ return curr;
}
-void ModelChecker::check_curr_backtracking(ModelAction * curr) {
+void ModelChecker::check_curr_backtracking(ModelAction *curr)
+{
Node *currnode = curr->get_node();
Node *parnode = currnode->get_parent();
- if ((!parnode->backtrack_empty() ||
+ if ((parnode && !parnode->backtrack_empty()) ||
!currnode->misc_empty() ||
!currnode->read_from_empty() ||
- !currnode->future_value_empty() ||
!currnode->promise_empty() ||
- !currnode->relseq_break_empty())
- && (!priv->next_backtrack ||
- *curr > *priv->next_backtrack)) {
- priv->next_backtrack = curr;
+ !currnode->relseq_break_empty()) {
+ set_latest_backtrack(curr);
}
}
-bool ModelChecker::promises_expired() {
- for (unsigned int promise_index = 0; promise_index < promises->size(); promise_index++) {
- Promise *promise = (*promises)[promise_index];
- if (promise->get_expiration()<priv->used_sequence_numbers) {
+bool ModelChecker::promises_expired() const
+{
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ if (promise->get_expiration() < priv->used_sequence_numbers)
return true;
- }
}
return false;
}
-/** @return whether the current partial trace must be a prefix of a
- * feasible trace. */
-bool ModelChecker::isfeasibleprefix() {
- return promises->size() == 0 && pending_rel_seqs->size() == 0;
+/**
+ * This is the strongest feasibility check available.
+ * @return whether the current trace (partial or complete) must be a prefix of
+ * a feasible trace.
+ */
+bool ModelChecker::isfeasibleprefix() const
+{
+ return pending_rel_seqs->size() == 0 && is_feasible_prefix_ignore_relseq();
}
-/** @return whether the current partial trace is feasible. */
-bool ModelChecker::isfeasible() {
- if (DBG_ENABLED() && mo_graph->checkForRMWViolation())
- DEBUG("Infeasible: RMW violation\n");
-
- return !mo_graph->checkForRMWViolation() && isfeasibleotherthanRMW();
+/**
+ * Print disagnostic information about an infeasible execution
+ * @param prefix A string to prefix the output with; if NULL, then a default
+ * message prefix will be provided
+ */
+void ModelChecker::print_infeasibility(const char *prefix) const
+{
+ char buf[100];
+ char *ptr = buf;
+ if (mo_graph->checkForCycles())
+ ptr += sprintf(ptr, "[mo cycle]");
+ if (priv->failed_promise)
+ ptr += sprintf(ptr, "[failed promise]");
+ if (priv->too_many_reads)
+ ptr += sprintf(ptr, "[too many reads]");
+ if (priv->no_valid_reads)
+ ptr += sprintf(ptr, "[no valid reads-from]");
+ if (priv->bad_synchronization)
+ ptr += sprintf(ptr, "[bad sw ordering]");
+ if (promises_expired())
+ ptr += sprintf(ptr, "[promise expired]");
+ if (promises->size() != 0)
+ ptr += sprintf(ptr, "[unresolved promise]");
+ if (ptr != buf)
+ model_print("%s: %s\n", prefix ? prefix : "Infeasible", buf);
}
-/** @return whether the current partial trace is feasible other than
- * multiple RMW reading from the same store. */
-bool ModelChecker::isfeasibleotherthanRMW() {
- if (DBG_ENABLED()) {
- if (mo_graph->checkForCycles())
- DEBUG("Infeasible: modification order cycles\n");
- if (failed_promise)
- DEBUG("Infeasible: failed promise\n");
- if (too_many_reads)
- DEBUG("Infeasible: too many reads\n");
- if (bad_synchronization)
- DEBUG("Infeasible: bad synchronization ordering\n");
- if (promises_expired())
- DEBUG("Infeasible: promises expired\n");
- }
- return !mo_graph->checkForCycles() && !failed_promise && !too_many_reads && !bad_synchronization && !promises_expired();
+/**
+ * Returns whether the current completed trace is feasible, except for pending
+ * release sequences.
+ */
+bool ModelChecker::is_feasible_prefix_ignore_relseq() const
+{
+ return !is_infeasible() && promises->size() == 0;
}
-/** Returns whether the current completed trace is feasible. */
-bool ModelChecker::isfinalfeasible() {
- if (DBG_ENABLED() && promises->size() != 0)
- DEBUG("Infeasible: unrevolved promises\n");
-
- return isfeasible() && promises->size() == 0;
+/**
+ * Check if the current partial trace is infeasible. Does not check any
+ * end-of-execution flags, which might rule out the execution. Thus, this is
+ * useful only for ruling an execution as infeasible.
+ * @return whether the current partial trace is infeasible.
+ */
+bool ModelChecker::is_infeasible() const
+{
+ return mo_graph->checkForCycles() ||
+ priv->no_valid_reads ||
+ priv->failed_promise ||
+ priv->too_many_reads ||
+ priv->bad_synchronization ||
+ promises_expired();
}
/** Close out a RMWR by converting previous RMWR into a RMW or READ. */
ModelAction * ModelChecker::process_rmw(ModelAction *act) {
ModelAction *lastread = get_last_action(act->get_tid());
lastread->process_rmw(act);
- if (act->is_rmw() && lastread->get_reads_from()!=NULL) {
- mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
+ if (act->is_rmw()) {
+ if (lastread->get_reads_from())
+ mo_graph->addRMWEdge(lastread->get_reads_from(), lastread);
+ else
+ mo_graph->addRMWEdge(lastread->get_reads_from_promise(), lastread);
mo_graph->commitChanges();
}
return lastread;
*
* If so, we decide that the execution is no longer feasible.
*/
-void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf) {
+void ModelChecker::check_recency(ModelAction *curr, const ModelAction *rf)
+{
if (params.maxreads != 0) {
-
- if (curr->get_node()->get_read_from_size() <= 1)
+ if (curr->get_node()->get_read_from_past_size() <= 1)
return;
//Must make sure that execution is currently feasible... We could
//accidentally clear by rolling back
- if (!isfeasible())
+ if (is_infeasible())
return;
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
int tid = id_to_int(curr->get_tid());
/* Skip checks */
action_list_t::reverse_iterator ritcopy = rit;
//See if we have enough reads from the same value
int count = 0;
- for (; count < params.maxreads; rit++,count++) {
- if (rit==list->rend())
+ for (; count < params.maxreads; rit++, count++) {
+ if (rit == list->rend())
return;
ModelAction *act = *rit;
if (!act->is_read())
return;
-
+
if (act->get_reads_from() != rf)
return;
- if (act->get_node()->get_read_from_size() <= 1)
+ if (act->get_node()->get_read_from_past_size() <= 1)
return;
}
- for (int i = 0; i<curr->get_node()->get_read_from_size(); i++) {
- //Get write
- const ModelAction * write = curr->get_node()->get_read_from_at(i);
+ for (int i = 0; i < curr->get_node()->get_read_from_past_size(); i++) {
+ /* Get write */
+ const ModelAction *write = curr->get_node()->get_read_from_past(i);
- //Need a different write
- if (write==rf)
+ /* Need a different write */
+ if (write == rf)
continue;
- /* Test to see whether this is a feasible write to read from*/
- mo_graph->startChanges();
- r_modification_order(curr, write);
- bool feasiblereadfrom = isfeasible();
- mo_graph->rollbackChanges();
+ /* Test to see whether this is a feasible write to read from */
+ /** NOTE: all members of read-from set should be
+ * feasible, so we no longer check it here **/
- if (!feasiblereadfrom)
- continue;
rit = ritcopy;
bool feasiblewrite = true;
//new we need to see if this write works for everyone
- for (int loop = count; loop>0; loop--,rit++) {
- ModelAction *act=*rit;
+ for (int loop = count; loop > 0; loop--, rit++) {
+ ModelAction *act = *rit;
bool foundvalue = false;
- for (int j = 0; j<act->get_node()->get_read_from_size(); j++) {
- if (act->get_node()->get_read_from_at(i)==write) {
+ for (int j = 0; j < act->get_node()->get_read_from_past_size(); j++) {
+ if (act->get_node()->get_read_from_past(j) == write) {
foundvalue = true;
break;
}
}
}
if (feasiblewrite) {
- too_many_reads = true;
+ priv->too_many_reads = true;
return;
}
}
* read.
*
* Basic idea is the following: Go through each other thread and find
- * the lastest action that happened before our read. Two cases:
+ * the last action that happened before our read. Two cases:
*
* (1) The action is a write => that write must either occur before
* the write we read from or be the write we read from.
* must occur before the write we read from or be the same write.
*
* @param curr The current action. Must be a read.
- * @param rf The action that curr reads from. Must be a write.
+ * @param rf The ModelAction or Promise that curr reads from. Must be a write.
* @return True if modification order edges were added; false otherwise
*/
-bool ModelChecker::r_modification_order(ModelAction *curr, const ModelAction *rf)
+template <typename rf_type>
+bool ModelChecker::r_modification_order(ModelAction *curr, const rf_type *rf)
{
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
unsigned int i;
bool added = false;
ASSERT(curr->is_read());
+ /* Last SC fence in the current thread */
+ ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
+
/* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
+ /* Last SC fence in thread i */
+ ModelAction *last_sc_fence_thread_local = NULL;
+ if (int_to_id((int)i) != curr->get_tid())
+ last_sc_fence_thread_local = get_last_seq_cst_fence(int_to_id(i), NULL);
+
+ /* Last SC fence in thread i, before last SC fence in current thread */
+ ModelAction *last_sc_fence_thread_before = NULL;
+ if (last_sc_fence_local)
+ last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(i), last_sc_fence_local);
+
/* 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;
+ if (act->is_write() && !act->equals(rf) && act != curr) {
+ /* C++, Section 29.3 statement 5 */
+ if (curr->is_seqcst() && last_sc_fence_thread_local &&
+ *act < *last_sc_fence_thread_local) {
+ added = mo_graph->addEdge(act, rf) || added;
+ break;
+ }
+ /* C++, Section 29.3 statement 4 */
+ else if (act->is_seqcst() && last_sc_fence_local &&
+ *act < *last_sc_fence_local) {
+ added = mo_graph->addEdge(act, rf) || added;
+ break;
+ }
+ /* C++, Section 29.3 statement 6 */
+ else if (last_sc_fence_thread_before &&
+ *act < *last_sc_fence_thread_before) {
+ added = mo_graph->addEdge(act, rf) || added;
+ break;
+ }
+ }
+
/*
* Include at most one act per-thread that "happens
* before" curr. Don't consider reflexively.
*/
if (act->happens_before(curr) && act != curr) {
if (act->is_write()) {
- if (rf != act) {
- mo_graph->addEdge(act, rf);
- added = true;
+ if (!act->equals(rf)) {
+ added = mo_graph->addEdge(act, rf) || added;
}
} else {
- const ModelAction *prevreadfrom = act->get_reads_from();
- //if the previous read is unresolved, keep going...
- if (prevreadfrom == NULL)
- continue;
-
- if (rf != prevreadfrom) {
- mo_graph->addEdge(prevreadfrom, rf);
- added = true;
+ const ModelAction *prevrf = act->get_reads_from();
+ const Promise *prevrf_promise = act->get_reads_from_promise();
+ if (prevrf) {
+ if (!prevrf->equals(rf))
+ added = mo_graph->addEdge(prevrf, rf) || added;
+ } else if (!prevrf_promise->equals(rf)) {
+ added = mo_graph->addEdge(prevrf_promise, rf) || added;
}
}
break;
}
}
- return added;
-}
-
-/** This method fixes up the modification order when we resolve a
- * promises. The basic problem is that actions that occur after the
- * read curr could not property add items to the modification order
- * for our read.
- *
- * So for each thread, we find the earliest item that happens after
- * the read curr. This is the item we have to fix up with additional
- * constraints. If that action is write, we add a MO edge between
- * the Action rf and that action. If the action is a read, we add a
- * MO edge between the Action rf, and whatever the read accessed.
- *
- * @param curr is the read ModelAction that we are fixing up MO edges for.
- * @param rf is the write ModelAction that curr reads from.
- *
- */
-void ModelChecker::post_r_modification_order(ModelAction *curr, const ModelAction *rf)
-{
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(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;
- ModelAction *lastact = NULL;
-
- /* Find last action that happens after curr that is either not curr or a rmw */
- for (rit = list->rbegin(); rit != list->rend(); rit++) {
- ModelAction *act = *rit;
- if (curr->happens_before(act) && (curr != act || curr->is_rmw())) {
- lastact = act;
- } else
- break;
- }
+ /*
+ * All compatible, thread-exclusive promises must be ordered after any
+ * concrete loads from the same thread
+ */
+ for (unsigned int i = 0; i < promises->size(); i++)
+ if ((*promises)[i]->is_compatible_exclusive(curr))
+ added = mo_graph->addEdge(rf, (*promises)[i]) || added;
- /* Include at most one act per-thread that "happens before" curr */
- if (lastact != NULL) {
- if (lastact==curr) {
- //Case 1: The resolved read is a RMW, and we need to make sure
- //that the write portion of the RMW mod order after rf
-
- mo_graph->addEdge(rf, lastact);
- } else if (lastact->is_read()) {
- //Case 2: The resolved read is a normal read and the next
- //operation is a read, and we need to make sure the value read
- //is mod ordered after rf
-
- const ModelAction *postreadfrom = lastact->get_reads_from();
- if (postreadfrom != NULL&&rf != postreadfrom)
- mo_graph->addEdge(rf, postreadfrom);
- } else {
- //Case 3: The resolved read is a normal read and the next
- //operation is a write, and we need to make sure that the
- //write is mod ordered after rf
- if (lastact!=rf)
- mo_graph->addEdge(rf, lastact);
- }
- break;
- }
- }
+ return added;
}
/**
*/
bool ModelChecker::w_modification_order(ModelAction *curr)
{
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
unsigned int i;
bool added = false;
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);
+ ModelAction *last_seq_cst = get_last_seq_cst_write(curr);
if (last_seq_cst != NULL) {
- mo_graph->addEdge(last_seq_cst, curr);
- added = true;
+ added = mo_graph->addEdge(last_seq_cst, curr) || added;
}
}
+ /* Last SC fence in the current thread */
+ ModelAction *last_sc_fence_local = get_last_seq_cst_fence(curr->get_tid(), NULL);
+
/* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
+ /* Last SC fence in thread i, before last SC fence in current thread */
+ ModelAction *last_sc_fence_thread_before = NULL;
+ if (last_sc_fence_local && int_to_id((int)i) != curr->get_tid())
+ last_sc_fence_thread_before = get_last_seq_cst_fence(int_to_id(i), last_sc_fence_local);
+
/* Iterate over actions in thread, starting from most recent */
action_list_t *list = &(*thrd_lists)[i];
action_list_t::reverse_iterator rit;
* 1) If RMW and it actually read from something, then we
* already have all relevant edges, so just skip to next
* thread.
- *
+ *
* 2) If RMW and it didn't read from anything, we should
* whatever edge we can get to speed up convergence.
*
* continue processing list.
*/
if (curr->is_rmw()) {
- if (curr->get_reads_from()!=NULL)
+ if (curr->get_reads_from() != NULL)
break;
- else
+ else
continue;
} else
continue;
}
+ /* C++, Section 29.3 statement 7 */
+ if (last_sc_fence_thread_before && act->is_write() &&
+ *act < *last_sc_fence_thread_before) {
+ added = mo_graph->addEdge(act, curr) || added;
+ break;
+ }
+
/*
* Include at most one act per-thread that "happens
* before" curr
* readfrom(act) --mo--> act
*/
if (act->is_write())
- mo_graph->addEdge(act, curr);
- else if (act->is_read()) {
+ added = mo_graph->addEdge(act, curr) || added;
+ else if (act->is_read()) {
//if previous read accessed a null, just keep going
if (act->get_reads_from() == NULL)
continue;
- mo_graph->addEdge(act->get_reads_from(), curr);
+ added = mo_graph->addEdge(act->get_reads_from(), curr) || added;
}
- added = true;
break;
} else if (act->is_read() && !act->could_synchronize_with(curr) &&
!act->same_thread(curr)) {
*/
if (thin_air_constraint_may_allow(curr, act)) {
- if (isfeasible() ||
- (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() == act->get_reads_from() && isfeasibleotherthanRMW())) {
- struct PendingFutureValue pfv = {curr,act};
- futurevalues->push_back(pfv);
- }
+ if (!is_infeasible())
+ futurevalues->push_back(PendingFutureValue(curr, act));
+ else if (curr->is_rmw() && act->is_rmw() && curr->get_reads_from() && curr->get_reads_from() == act->get_reads_from())
+ add_future_value(curr, act);
}
}
}
}
+ /*
+ * All compatible, thread-exclusive promises must be ordered after any
+ * concrete stores to the same thread, or else they can be merged with
+ * this store later
+ */
+ for (unsigned int i = 0; i < promises->size(); i++)
+ if ((*promises)[i]->is_compatible_exclusive(curr))
+ added = mo_graph->addEdge(curr, (*promises)[i]) || added;
+
return added;
}
/** Arbitrary reads from the future are not allowed. Section 29.3
* part 9 places some constraints. This method checks one result of constraint
* constraint. Others require compiler support. */
-bool ModelChecker::thin_air_constraint_may_allow(const ModelAction * writer, const ModelAction *reader) {
+bool ModelChecker::thin_air_constraint_may_allow(const ModelAction *writer, const ModelAction *reader)
+{
if (!writer->is_rmw())
return true;
*/
bool ModelChecker::mo_may_allow(const ModelAction *writer, const ModelAction *reader)
{
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(reader->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, reader->get_location());
unsigned int i;
-
/* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
- ModelAction *write_after_read = NULL;
+ const ModelAction *write_after_read = NULL;
/* Iterate over actions in thread, starting from most recent */
action_list_t *list = &(*thrd_lists)[i];
for (rit = list->rbegin(); rit != list->rend(); rit++) {
ModelAction *act = *rit;
- if (!reader->happens_before(act))
+ /* Don't disallow due to act == reader */
+ if (!reader->happens_before(act) || reader == act)
break;
else if (act->is_write())
write_after_read = act;
+ else if (act->is_read() && act->get_reads_from() != NULL)
+ write_after_read = act->get_reads_from();
}
- if (write_after_read && mo_graph->checkReachable(write_after_read, writer))
+ if (write_after_read && write_after_read != writer && mo_graph->checkReachable(write_after_read, writer))
return false;
}
-
return true;
}
if (mo_graph->checkForCycles())
return false;
- while (rf) {
+ for ( ; rf != NULL; rf = rf->get_reads_from()) {
ASSERT(rf->is_write());
if (rf->is_release())
release_heads->push_back(rf);
+ else if (rf->get_last_fence_release())
+ release_heads->push_back(rf->get_last_fence_release());
if (!rf->is_rmw())
break; /* End of RMW chain */
/* acq_rel RMW is a sufficient stopping condition */
if (rf->is_acquire() && rf->is_release())
return true; /* complete */
-
- rf = rf->get_reads_from();
};
if (!rf) {
/* read from future: need to settle this later */
if (rf->is_release())
return true; /* complete */
- /* else relaxed write; check modification order for contiguous subsequence
- * -> rf must be same thread as release */
+ /* else relaxed write
+ * - check for fence-release in the same thread (29.8, stmt. 3)
+ * - check modification order for contiguous subsequence
+ * -> rf must be same thread as release */
+
+ const ModelAction *fence_release = rf->get_last_fence_release();
+ /* Synchronize with a fence-release unconditionally; we don't need to
+ * find any more "contiguous subsequence..." for it */
+ if (fence_release)
+ release_heads->push_back(fence_release);
+
int tid = id_to_int(rf->get_tid());
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(rf->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, rf->get_location());
action_list_t *list = &(*thrd_lists)[tid];
action_list_t::const_reverse_iterator rit;
rit = std::find(list->rbegin(), list->rend(), rf);
ASSERT(rit != list->rend());
- /* Find the last write/release */
- for (; rit != list->rend(); rit++)
+ /* Find the last {write,fence}-release */
+ for (; rit != list->rend(); rit++) {
+ if (fence_release && *(*rit) < *fence_release)
+ break;
if ((*rit)->is_release())
break;
+ }
if (rit == list->rend()) {
/* No write-release in this thread */
return true; /* complete */
- }
+ } else if (fence_release && *(*rit) < *fence_release) {
+ /* The fence-release is more recent (and so, "stronger") than
+ * the most recent write-release */
+ return true; /* complete */
+ } /* else, need to establish contiguous release sequence */
ModelAction *release = *rit;
ASSERT(rf->same_thread(release));
ModelAction *last = get_last_action(int_to_id(i));
Thread *th = get_thread(int_to_id(i));
if ((last && rf->happens_before(last)) ||
- !scheduler->is_enabled(th) ||
+ !is_enabled(th) ||
th->is_complete())
future_ordered = true;
}
/**
- * A public interface for getting the release sequence head(s) with which a
+ * An interface for getting the release sequence head(s) with which a
* given ModelAction must synchronize. This function only returns a non-empty
* result when it can locate a release sequence head with certainty. Otherwise,
* it may mark the internal state of the ModelChecker so that it will handle
- * the release sequence at a later time, causing @a act to update its
+ * the release sequence at a later time, causing @a acquire to update its
* synchronization at some later point in execution.
- * @param act The 'acquire' action that may read from a release sequence
+ *
+ * @param acquire The 'acquire' action that may synchronize with a release
+ * sequence
+ * @param read The read action that may read from a release sequence; this may
+ * be the same as acquire, or else an earlier action in the same thread (i.e.,
+ * when 'acquire' is a fence-acquire)
* @param release_heads A pass-by-reference return parameter. Will be filled
* with the head(s) of the release sequence(s), if they exists with certainty.
* @see ModelChecker::release_seq_heads
*/
-void ModelChecker::get_release_seq_heads(ModelAction *act, rel_heads_list_t *release_heads)
+void ModelChecker::get_release_seq_heads(ModelAction *acquire,
+ ModelAction *read, rel_heads_list_t *release_heads)
{
- const ModelAction *rf = act->get_reads_from();
+ const ModelAction *rf = read->get_reads_from();
struct release_seq *sequence = (struct release_seq *)snapshot_calloc(1, sizeof(struct release_seq));
- sequence->acquire = act;
+ sequence->acquire = acquire;
+ sequence->read = read;
if (!release_seq_heads(rf, release_heads, sequence)) {
/* add act to 'lazy checking' list */
std::vector< struct release_seq *, SnapshotAlloc<struct release_seq *> >::iterator it = pending_rel_seqs->begin();
while (it != pending_rel_seqs->end()) {
struct release_seq *pending = *it;
- ModelAction *act = pending->acquire;
+ ModelAction *acquire = pending->acquire;
+ const ModelAction *read = pending->read;
/* Only resolve sequences on the given location, if provided */
- if (location && act->get_location() != location) {
+ if (location && read->get_location() != location) {
it++;
continue;
}
- const ModelAction *rf = act->get_reads_from();
+ const ModelAction *rf = read->get_reads_from();
rel_heads_list_t release_heads;
bool complete;
complete = release_seq_heads(rf, &release_heads, pending);
for (unsigned int i = 0; i < release_heads.size(); i++) {
- if (!act->has_synchronized_with(release_heads[i])) {
- if (act->synchronize_with(release_heads[i]))
+ if (!acquire->has_synchronized_with(release_heads[i])) {
+ if (acquire->synchronize_with(release_heads[i]))
updated = true;
else
set_bad_synchronization();
if (updated) {
/* Re-check all pending release sequences */
work_queue->push_back(CheckRelSeqWorkEntry(NULL));
- /* Re-check act for mo_graph edges */
- work_queue->push_back(MOEdgeWorkEntry(act));
+ /* Re-check read-acquire for mo_graph edges */
+ if (acquire->is_read())
+ work_queue->push_back(MOEdgeWorkEntry(acquire));
/* propagate synchronization to later actions */
action_list_t::reverse_iterator rit = action_trace->rbegin();
- for (; (*rit) != act; rit++) {
+ for (; (*rit) != acquire; rit++) {
ModelAction *propagate = *rit;
- if (act->happens_before(propagate)) {
- propagate->synchronize_with(act);
+ if (acquire->happens_before(propagate)) {
+ propagate->synchronize_with(acquire);
/* Re-check 'propagate' for mo_graph edges */
work_queue->push_back(MOEdgeWorkEntry(propagate));
}
}
// If we resolved promises or data races, see if we have realized a data race.
- if (checkDataRaces()) {
- set_assert();
- }
+ checkDataRaces();
return updated;
}
void ModelChecker::add_action_to_lists(ModelAction *act)
{
int tid = id_to_int(act->get_tid());
- action_trace->push_back(act);
+ ModelAction *uninit = NULL;
+ int uninit_id = -1;
+ action_list_t *list = get_safe_ptr_action(obj_map, act->get_location());
+ if (list->empty() && act->is_atomic_var()) {
+ uninit = new_uninitialized_action(act->get_location());
+ uninit_id = id_to_int(uninit->get_tid());
+ list->push_back(uninit);
+ }
+ list->push_back(act);
- obj_map->get_safe_ptr(act->get_location())->push_back(act);
+ action_trace->push_back(act);
+ if (uninit)
+ action_trace->push_front(uninit);
- std::vector<action_list_t> *vec = obj_thrd_map->get_safe_ptr(act->get_location());
+ std::vector<action_list_t> *vec = get_safe_ptr_vect_action(obj_thrd_map, act->get_location());
if (tid >= (int)vec->size())
vec->resize(priv->next_thread_id);
(*vec)[tid].push_back(act);
+ if (uninit)
+ (*vec)[uninit_id].push_front(uninit);
if ((int)thrd_last_action->size() <= tid)
thrd_last_action->resize(get_num_threads());
(*thrd_last_action)[tid] = act;
+ if (uninit)
+ (*thrd_last_action)[uninit_id] = uninit;
+
+ if (act->is_fence() && act->is_release()) {
+ if ((int)thrd_last_fence_release->size() <= tid)
+ thrd_last_fence_release->resize(get_num_threads());
+ (*thrd_last_fence_release)[tid] = act;
+ }
if (act->is_wait()) {
- void *mutex_loc=(void *) act->get_value();
- obj_map->get_safe_ptr(mutex_loc)->push_back(act);
-
- std::vector<action_list_t> *vec = obj_thrd_map->get_safe_ptr(mutex_loc);
+ void *mutex_loc = (void *) act->get_value();
+ get_safe_ptr_action(obj_map, mutex_loc)->push_back(act);
+
+ std::vector<action_list_t> *vec = get_safe_ptr_vect_action(obj_thrd_map, mutex_loc);
if (tid >= (int)vec->size())
vec->resize(priv->next_thread_id);
(*vec)[tid].push_back(act);
-
- if ((int)thrd_last_action->size() <= tid)
- thrd_last_action->resize(get_num_threads());
- (*thrd_last_action)[tid] = act;
}
}
return NULL;
}
+/**
+ * @brief Get the last fence release performed by a particular Thread
+ * @param tid The thread ID of the Thread in question
+ * @return The last fence release in the thread, if one exists; NULL otherwise
+ */
+ModelAction * ModelChecker::get_last_fence_release(thread_id_t tid) const
+{
+ int threadid = id_to_int(tid);
+ if (threadid < (int)thrd_last_fence_release->size())
+ return (*thrd_last_fence_release)[id_to_int(tid)];
+ else
+ return NULL;
+}
+
/**
* Gets the last memory_order_seq_cst write (in the total global sequence)
* performed on a particular object (i.e., memory location), not including the
* check
* @return The last seq_cst write
*/
-ModelAction * ModelChecker::get_last_seq_cst(ModelAction *curr) const
+ModelAction * ModelChecker::get_last_seq_cst_write(ModelAction *curr) const
{
void *location = curr->get_location();
- action_list_t *list = obj_map->get_safe_ptr(location);
+ action_list_t *list = get_safe_ptr_action(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++)
return NULL;
}
+/**
+ * Gets the last memory_order_seq_cst fence (in the total global sequence)
+ * performed in a particular thread, prior to a particular fence.
+ * @param tid The ID of the thread to check
+ * @param before_fence The fence from which to begin the search; if NULL, then
+ * search for the most recent fence in the thread.
+ * @return The last prior seq_cst fence in the thread, if exists; otherwise, NULL
+ */
+ModelAction * ModelChecker::get_last_seq_cst_fence(thread_id_t tid, const ModelAction *before_fence) const
+{
+ /* All fences should have NULL location */
+ action_list_t *list = get_safe_ptr_action(obj_map, NULL);
+ action_list_t::reverse_iterator rit = list->rbegin();
+
+ if (before_fence) {
+ for (; rit != list->rend(); rit++)
+ if (*rit == before_fence)
+ break;
+
+ ASSERT(*rit == before_fence);
+ rit++;
+ }
+
+ for (; rit != list->rend(); rit++)
+ if ((*rit)->is_fence() && (tid == (*rit)->get_tid()) && (*rit)->is_seqcst())
+ return *rit;
+ return NULL;
+}
+
/**
* Gets the last unlock operation performed on a particular mutex (i.e., memory
* location). This function identifies the mutex according to the current
ModelAction * ModelChecker::get_last_unlock(ModelAction *curr) const
{
void *location = curr->get_location();
- action_list_t *list = obj_map->get_safe_ptr(location);
+ action_list_t *list = get_safe_ptr_action(obj_map, location);
/* Find: max({i in dom(S) | isUnlock(t_i) && samevar(t_i, t)}) */
action_list_t::reverse_iterator rit;
for (rit = list->rbegin(); rit != list->rend(); rit++)
return NULL;
}
-ModelAction * ModelChecker::get_parent_action(thread_id_t tid)
+ModelAction * ModelChecker::get_parent_action(thread_id_t tid) const
{
ModelAction *parent = get_last_action(tid);
if (!parent)
* @param tid The thread whose clock vector we want
* @return Desired clock vector
*/
-ClockVector * ModelChecker::get_cv(thread_id_t tid)
+ClockVector * ModelChecker::get_cv(thread_id_t tid) const
{
return get_parent_action(tid)->get_cv();
}
*/
bool ModelChecker::resolve_promises(ModelAction *write)
{
- bool resolved = false;
- std::vector< thread_id_t, ModelAlloc<thread_id_t> > threads_to_check;
+ bool haveResolved = false;
+ std::vector< ModelAction *, ModelAlloc<ModelAction *> > actions_to_check;
+ promise_list_t mustResolve, resolved;
for (unsigned int i = 0, promise_index = 0; promise_index < promises->size(); i++) {
Promise *promise = (*promises)[promise_index];
if (write->get_node()->get_promise(i)) {
- ModelAction *read = promise->get_action();
- if (read->is_rmw()) {
- mo_graph->addRMWEdge(write, read);
+ for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+ ModelAction *read = promise->get_reader(j);
+ read_from(read, write);
+ actions_to_check.push_back(read);
}
- read->read_from(write);
- //First fix up the modification order for actions that happened
- //before the read
- r_modification_order(read, write);
- //Next fix up the modification order for actions that happened
- //after the read.
- post_r_modification_order(read, write);
//Make sure the promise's value matches the write's value
- ASSERT(promise->get_value() == write->get_value());
- delete(promise);
-
+ ASSERT(promise->is_compatible(write));
+ mo_graph->resolvePromise(promise, write, &mustResolve);
+
+ resolved.push_back(promise);
promises->erase(promises->begin() + promise_index);
- threads_to_check.push_back(read->get_tid());
- resolved = true;
+ haveResolved = true;
} else
promise_index++;
}
+ for (unsigned int i = 0; i < mustResolve.size(); i++) {
+ if (std::find(resolved.begin(), resolved.end(), mustResolve[i])
+ == resolved.end())
+ priv->failed_promise = true;
+ }
+ for (unsigned int i = 0; i < resolved.size(); i++)
+ delete resolved[i];
//Check whether reading these writes has made threads unable to
//resolve promises
- for(unsigned int i=0;i<threads_to_check.size();i++)
- mo_check_promises(threads_to_check[i], write);
+ for (unsigned int i = 0; i < actions_to_check.size(); i++) {
+ ModelAction *read = actions_to_check[i];
+ mo_check_promises(read, true);
+ }
- return resolved;
+ return haveResolved;
}
/**
{
for (unsigned int i = 0; i < promises->size(); i++) {
Promise *promise = (*promises)[i];
- const ModelAction *act = promise->get_action();
- if (!act->happens_before(curr) &&
- act->is_read() &&
- !act->could_synchronize_with(curr) &&
- !act->same_thread(curr) &&
- act->get_location() == curr->get_location() &&
- promise->get_value() == curr->get_value()) {
- curr->get_node()->set_promise(i);
+ if (!promise->is_compatible(curr) || promise->get_value() != curr->get_value())
+ continue;
+
+ bool satisfy = true;
+ for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+ const ModelAction *act = promise->get_reader(j);
+ if (act->happens_before(curr) ||
+ act->could_synchronize_with(curr)) {
+ satisfy = false;
+ break;
+ }
}
+ if (satisfy)
+ curr->get_node()->set_promise(i);
}
}
{
for (unsigned int i = 0; i < promises->size(); i++) {
Promise *promise = (*promises)[i];
- const ModelAction *act = promise->get_action();
- if ((old_cv == NULL || !old_cv->synchronized_since(act)) &&
- merge_cv->synchronized_since(act)) {
- if (promise->increment_threads(tid)) {
- //Promise has failed
- failed_promise = true;
- return;
+ if (!promise->thread_is_available(tid))
+ continue;
+ for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+ const ModelAction *act = promise->get_reader(j);
+ if ((!old_cv || !old_cv->synchronized_since(act)) &&
+ merge_cv->synchronized_since(act)) {
+ if (promise->eliminate_thread(tid)) {
+ /* Promise has failed */
+ priv->failed_promise = true;
+ return;
+ }
}
}
}
}
-/** Checks promises in response to addition to modification order for threads.
- * Definitions:
- * pthread is the thread that performed the read that created the promise
- *
- * pread is the read that created the promise
- *
- * pwrite is either the first write to same location as pread by
- * pthread that is sequenced after pread or the value read by the
- * first read to the same lcoation as pread by pthread that is
- * sequenced after pread..
- *
- * 1. If tid=pthread, then we check what other threads are reachable
- * through the mode order starting with pwrite. Those threads cannot
- * perform a write that will resolve the promise due to modification
- * order constraints.
- *
- * 2. If the tid is not pthread, we check whether pwrite can reach the
- * action write through the modification order. If so, that thread
- * cannot perform a future write that will resolve the promise due to
- * modificatin order constraints.
+void ModelChecker::check_promises_thread_disabled()
+{
+ for (unsigned int i = 0; i < promises->size(); i++) {
+ Promise *promise = (*promises)[i];
+ if (promise->has_failed()) {
+ priv->failed_promise = true;
+ return;
+ }
+ }
+}
+
+/**
+ * @brief Checks promises in response to addition to modification order for
+ * threads.
*
- * @parem tid The thread that either read from the model action
- * write, or actually did the model action write.
+ * We test whether threads are still available for satisfying promises after an
+ * addition to our modification order constraints. Those that are unavailable
+ * are "eliminated". Once all threads are eliminated from satisfying a promise,
+ * that promise has failed.
*
- * @parem write The ModelAction representing the relevant write.
+ * @param act The ModelAction which updated the modification order
+ * @param is_read_check Should be true if act is a read and we must check for
+ * updates to the store from which it read (there is a distinction here for
+ * RMW's, which are both a load and a store)
*/
+void ModelChecker::mo_check_promises(const ModelAction *act, bool is_read_check)
+{
+ const ModelAction *write = is_read_check ? act->get_reads_from() : act;
-void ModelChecker::mo_check_promises(thread_id_t tid, const ModelAction *write) {
- void * location = write->get_location();
for (unsigned int i = 0; i < promises->size(); i++) {
Promise *promise = (*promises)[i];
- const ModelAction *act = promise->get_action();
-
- //Is this promise on the same location?
- if ( act->get_location() != location )
- continue;
- //same thread as the promise
- if ( act->get_tid()==tid ) {
+ // Is this promise on the same location?
+ if (promise->get_value() != write->get_value())
+ continue;
- //do we have a pwrite for the promise, if not, set it
- if (promise->get_write() == NULL ) {
- promise->set_write(write);
- //The pwrite cannot happen before the promise
- if (write->happens_before(act) && (write != act)) {
- failed_promise = true;
- return;
- }
- }
+ for (unsigned int j = 0; j < promise->get_num_readers(); j++) {
+ const ModelAction *pread = promise->get_reader(j);
+ if (!pread->happens_before(act))
+ continue;
if (mo_graph->checkPromise(write, promise)) {
- failed_promise = true;
+ priv->failed_promise = true;
return;
}
+ break;
}
-
- //Don't do any lookups twice for the same thread
- if (promise->has_sync_thread(tid))
+
+ // Don't do any lookups twice for the same thread
+ if (!promise->thread_is_available(act->get_tid()))
continue;
-
- if (mo_graph->checkReachable(promise->get_write(), write)) {
- if (promise->increment_threads(tid)) {
- failed_promise = true;
+
+ if (mo_graph->checkReachable(promise, write)) {
+ if (mo_graph->checkPromise(write, promise)) {
+ priv->failed_promise = true;
return;
}
}
/**
* 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"
- * relationship.
+ * from, as well as any previously-observed future values that must still be valid.
+ *
* @param curr is the current ModelAction that we are exploring; it must be a
* 'read' operation.
*/
-void ModelChecker::build_reads_from_past(ModelAction *curr)
+void ModelChecker::build_may_read_from(ModelAction *curr)
{
- std::vector<action_list_t> *thrd_lists = obj_thrd_map->get_safe_ptr(curr->get_location());
+ std::vector<action_list_t> *thrd_lists = get_safe_ptr_vect_action(obj_thrd_map, curr->get_location());
unsigned int i;
ASSERT(curr->is_read());
- ModelAction *last_seq_cst = NULL;
+ ModelAction *last_sc_write = NULL;
- /* Track whether this object has been initialized */
- bool initialized = false;
-
- if (curr->is_seqcst()) {
- last_seq_cst = get_last_seq_cst(curr);
- /* We have to at least see the last sequentially consistent write,
- so we are initialized. */
- if (last_seq_cst != NULL)
- initialized = true;
- }
+ if (curr->is_seqcst())
+ last_sc_write = get_last_seq_cst_write(curr);
/* Iterate over all threads */
for (i = 0; i < thrd_lists->size(); i++) {
continue;
/* Don't consider more than one seq_cst write if we are a seq_cst read. */
- if (!curr->is_seqcst() || (!act->is_seqcst() && (last_seq_cst == NULL || !act->happens_before(last_seq_cst))) || act == last_seq_cst) {
- DEBUG("Adding action to may_read_from:\n");
- if (DBG_ENABLED()) {
- act->print();
- curr->print();
- }
-
- if (curr->get_sleep_flag() && ! curr->is_seqcst()) {
- if (sleep_can_read_from(curr, act))
- curr->get_node()->add_read_from(act);
- } else
- curr->get_node()->add_read_from(act);
+ bool allow_read = true;
+
+ if (curr->is_seqcst() && (act->is_seqcst() || (last_sc_write != NULL && act->happens_before(last_sc_write))) && act != last_sc_write)
+ allow_read = false;
+ else if (curr->get_sleep_flag() && !curr->is_seqcst() && !sleep_can_read_from(curr, act))
+ allow_read = false;
+
+ if (allow_read) {
+ /* Only add feasible reads */
+ mo_graph->startChanges();
+ r_modification_order(curr, act);
+ if (!is_infeasible())
+ curr->get_node()->add_read_from_past(act);
+ mo_graph->rollbackChanges();
}
/* Include at most one act per-thread that "happens before" curr */
- if (act->happens_before(curr)) {
- initialized = true;
+ if (act->happens_before(curr))
break;
- }
}
}
- if (!initialized) {
- /** @todo Need a more informative way of reporting errors. */
- printf("ERROR: may read from uninitialized atomic\n");
+ /* Inherit existing, promised future values */
+ for (i = 0; i < promises->size(); i++) {
+ const Promise *promise = (*promises)[i];
+ const ModelAction *promise_read = promise->get_reader(0);
+ if (promise_read->same_var(curr)) {
+ /* Only add feasible future-values */
+ mo_graph->startChanges();
+ r_modification_order(curr, promise);
+ if (!is_infeasible())
+ curr->get_node()->add_read_from_promise(promise_read);
+ mo_graph->rollbackChanges();
+ }
+ }
+
+ /* We may find no valid may-read-from only if the execution is doomed */
+ if (!curr->get_node()->read_from_size()) {
+ priv->no_valid_reads = true;
set_assert();
}
- if (DBG_ENABLED() || !initialized) {
- printf("Reached read action:\n");
+ if (DBG_ENABLED()) {
+ model_print("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");
+ model_print("Printing read_from_past\n");
+ curr->get_node()->print_read_from_past();
+ model_print("End printing read_from_past\n");
}
}
-bool ModelChecker::sleep_can_read_from(ModelAction * curr, const ModelAction *write) {
- while(true) {
- Node *prevnode=write->get_node()->get_parent();
-
- bool thread_sleep=prevnode->enabled_status(curr->get_tid())==THREAD_SLEEP_SET;
- if (write->is_release()&&thread_sleep)
+bool ModelChecker::sleep_can_read_from(ModelAction *curr, const ModelAction *write)
+{
+ for ( ; write != NULL; write = write->get_reads_from()) {
+ /* UNINIT actions don't have a Node, and they never sleep */
+ if (write->is_uninitialized())
return true;
- if (!write->is_rmw()) {
- return false;
- }
- if (write->get_reads_from()==NULL)
+ Node *prevnode = write->get_node()->get_parent();
+
+ bool thread_sleep = prevnode->enabled_status(curr->get_tid()) == THREAD_SLEEP_SET;
+ if (write->is_release() && thread_sleep)
return true;
- write=write->get_reads_from();
+ if (!write->is_rmw())
+ return false;
}
+ return true;
+}
+
+/**
+ * @brief Create a new action representing an uninitialized atomic
+ * @param location The memory location of the atomic object
+ * @return A pointer to a new ModelAction
+ */
+ModelAction * ModelChecker::new_uninitialized_action(void *location) const
+{
+ ModelAction *act = (ModelAction *)snapshot_malloc(sizeof(class ModelAction));
+ act = new (act) ModelAction(ATOMIC_UNINIT, std::memory_order_relaxed, location, 0, model_thread);
+ act->create_cv(NULL);
+ return act;
}
static void print_list(action_list_t *list)
{
action_list_t::iterator it;
- printf("---------------------------------------------------------------------\n");
- printf("Trace:\n");
- unsigned int hash=0;
-
+ model_print("---------------------------------------------------------------------\n");
+
+ unsigned int hash = 0;
+
for (it = list->begin(); it != list->end(); it++) {
(*it)->print();
- hash=hash^(hash<<3)^((*it)->hash());
+ hash = hash^(hash<<3)^((*it)->hash());
}
- printf("HASH %u\n", hash);
- printf("---------------------------------------------------------------------\n");
+ model_print("HASH %u\n", hash);
+ model_print("---------------------------------------------------------------------\n");
}
#if SUPPORT_MOD_ORDER_DUMP
-void ModelChecker::dumpGraph(char *filename) {
+void ModelChecker::dumpGraph(char *filename) const
+{
char buffer[200];
- sprintf(buffer, "%s.dot",filename);
- FILE *file=fopen(buffer, "w");
- fprintf(file, "digraph %s {\n",filename);
+ sprintf(buffer, "%s.dot", filename);
+ FILE *file = fopen(buffer, "w");
+ fprintf(file, "digraph %s {\n", filename);
mo_graph->dumpNodes(file);
- ModelAction ** thread_array=(ModelAction **)model_calloc(1, sizeof(ModelAction *)*get_num_threads());
-
+ ModelAction **thread_array = (ModelAction **)model_calloc(1, sizeof(ModelAction *) * get_num_threads());
+
for (action_list_t::iterator it = action_trace->begin(); it != action_trace->end(); it++) {
- ModelAction *action=*it;
+ ModelAction *action = *it;
if (action->is_read()) {
- fprintf(file, "N%u [label=\"%u, T%u\"];\n", action->get_seq_number(),action->get_seq_number(), action->get_tid());
- if (action->get_reads_from()!=NULL)
+ fprintf(file, "N%u [label=\"N%u, T%u\"];\n", action->get_seq_number(), action->get_seq_number(), action->get_tid());
+ if (action->get_reads_from() != NULL)
fprintf(file, "N%u -> N%u[label=\"rf\", color=red];\n", action->get_seq_number(), action->get_reads_from()->get_seq_number());
}
if (thread_array[action->get_tid()] != NULL) {
fprintf(file, "N%u -> N%u[label=\"sb\", color=blue];\n", thread_array[action->get_tid()]->get_seq_number(), action->get_seq_number());
}
-
- thread_array[action->get_tid()]=action;
+
+ thread_array[action->get_tid()] = action;
}
- fprintf(file,"}\n");
+ fprintf(file, "}\n");
model_free(thread_array);
- fclose(file);
+ fclose(file);
}
#endif
-void ModelChecker::print_summary()
+/** @brief Prints an execution trace summary. */
+void ModelChecker::print_summary() const
{
- printf("\n");
- printf("Number of executions: %d\n", num_executions);
- printf("Number of feasible executions: %d\n", num_feasible_executions);
- printf("Total nodes created: %d\n", node_stack->get_total_nodes());
-
#if SUPPORT_MOD_ORDER_DUMP
- scheduler->print();
char buffername[100];
- sprintf(buffername, "exec%04u", num_executions);
+ sprintf(buffername, "exec%04u", stats.num_total);
mo_graph->dumpGraphToFile(buffername);
- sprintf(buffername, "graph%04u", num_executions);
- dumpGraph(buffername);
+ sprintf(buffername, "graph%04u", stats.num_total);
+ dumpGraph(buffername);
#endif
- if (!isfinalfeasible())
- printf("INFEASIBLE EXECUTION!\n");
+ model_print("Execution %d:", stats.num_total);
+ if (isfeasibleprefix()) {
+ if (scheduler->all_threads_sleeping())
+ model_print(" SLEEP-SET REDUNDANT");
+ model_print("\n");
+ } else
+ print_infeasibility(" INFEASIBLE");
print_list(action_trace);
- printf("\n");
+ model_print("\n");
}
/**
}
/**
- * Removes a thread from the scheduler.
+ * Removes a thread from the scheduler.
* @param the thread to remove.
*/
void ModelChecker::remove_thread(Thread *t)
* @param act The ModelAction
* @return A Thread reference
*/
-Thread * ModelChecker::get_thread(ModelAction *act) const
+Thread * ModelChecker::get_thread(const ModelAction *act) const
{
return get_thread(act->get_tid());
}
+/**
+ * @brief Get a Promise's "promise number"
+ *
+ * A "promise number" is an index number that is unique to a promise, valid
+ * only for a specific snapshot of an execution trace. Promises may come and go
+ * as they are generated an resolved, so an index only retains meaning for the
+ * current snapshot.
+ *
+ * @param promise The Promise to check
+ * @return The promise index, if the promise still is valid; otherwise -1
+ */
+int ModelChecker::get_promise_number(const Promise *promise) const
+{
+ for (unsigned int i = 0; i < promises->size(); i++)
+ if ((*promises)[i] == promise)
+ return i;
+ /* Not found */
+ return -1;
+}
+
+/**
+ * @brief Check if a Thread is currently enabled
+ * @param t The Thread to check
+ * @return True if the Thread is currently enabled
+ */
+bool ModelChecker::is_enabled(Thread *t) const
+{
+ return scheduler->is_enabled(t);
+}
+
+/**
+ * @brief Check if a Thread is currently enabled
+ * @param tid The ID of the Thread to check
+ * @return True if the Thread is currently enabled
+ */
+bool ModelChecker::is_enabled(thread_id_t tid) const
+{
+ return scheduler->is_enabled(tid);
+}
+
+/**
+ * Switch from a model-checker context to a user-thread context. This is the
+ * complement of ModelChecker::switch_to_master and must be called from the
+ * model-checker context
+ *
+ * @param thread The user-thread to switch to
+ */
+void ModelChecker::switch_from_master(Thread *thread)
+{
+ scheduler->set_current_thread(thread);
+ Thread::swap(&system_context, thread);
+}
+
/**
* 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
* @param act The current action that will be explored. May be NULL only if
* trace is exiting via an assertion (see ModelChecker::set_assert and
* ModelChecker::has_asserted).
- * @return Return status from the 'swap' call (i.e., success/fail, 0/-1)
+ * @return Return the value returned by the current action
*/
-int ModelChecker::switch_to_master(ModelAction *act)
+uint64_t ModelChecker::switch_to_master(ModelAction *act)
{
DBG();
Thread *old = thread_current();
- set_current_action(act);
- old->set_state(THREAD_READY);
- return Thread::swap(old, &system_context);
+ ASSERT(!old->get_pending());
+ old->set_pending(act);
+ if (Thread::swap(old, &system_context) < 0) {
+ perror("swap threads");
+ exit(EXIT_FAILURE);
+ }
+ return old->get_return_value();
}
/**
* Takes the next step in the execution, if possible.
- * @return Returns true (success) if a step was taken and false otherwise.
+ * @param curr The current step to take
+ * @return Returns the next Thread to run, if any; NULL if this execution
+ * should terminate
*/
-bool ModelChecker::take_step() {
- if (has_asserted())
- return false;
-
- Thread *curr = priv->current_action ? get_thread(priv->current_action) : NULL;
- if (curr) {
- if (curr->get_state() == THREAD_READY) {
- ASSERT(priv->current_action);
-
- priv->nextThread = check_current_action(priv->current_action);
- priv->current_action = NULL;
+Thread * ModelChecker::take_step(ModelAction *curr)
+{
+ Thread *curr_thrd = get_thread(curr);
+ ASSERT(curr_thrd->get_state() == THREAD_READY);
- if (curr->is_blocked() || curr->is_complete())
- scheduler->remove_thread(curr);
- } else {
- ASSERT(false);
- }
- }
- Thread *next = scheduler->next_thread(priv->nextThread);
+ curr = check_current_action(curr);
/* Infeasible -> don't take any more steps */
- if (!isfeasible())
- return false;
-
- if (params.bound != 0) {
- if (priv->used_sequence_numbers > params.bound) {
- return false;
- }
+ if (is_infeasible())
+ return NULL;
+ else if (isfeasibleprefix() && have_bug_reports()) {
+ set_assert();
+ return NULL;
}
- DEBUG("(%d, %d)\n", curr ? id_to_int(curr->get_id()) : -1,
- next ? id_to_int(next->get_id()) : -1);
+ if (params.bound != 0 && priv->used_sequence_numbers > params.bound)
+ return NULL;
- /*
- * Launch end-of-execution release sequence fixups only when there are:
- *
- * (1) no more user threads to run (or when execution replay chooses
- * the 'model_thread')
- * (2) pending release sequences
- * (3) pending assertions (i.e., data races)
- * (4) no pending promises
- */
- if (!pending_rel_seqs->empty() && (!next || next->is_model_thread()) &&
- isfinalfeasible() && !unrealizedraces.empty()) {
- printf("*** WARNING: release sequence fixup action (%zu pending release seuqences) ***\n",
- pending_rel_seqs->size());
- ModelAction *fixup = new ModelAction(MODEL_FIXUP_RELSEQ,
- std::memory_order_seq_cst, NULL, VALUE_NONE,
- model_thread);
- set_current_action(fixup);
- return true;
- }
+ if (curr_thrd->is_blocked() || curr_thrd->is_complete())
+ scheduler->remove_thread(curr_thrd);
- /* next == NULL -> don't take any more steps */
- if (!next)
- return false;
+ Thread *next_thrd = get_next_thread(curr);
- next->set_state(THREAD_RUNNING);
+ DEBUG("(%d, %d)\n", curr_thrd ? id_to_int(curr_thrd->get_id()) : -1,
+ next_thrd ? id_to_int(next_thrd->get_id()) : -1);
- if (next->get_pending() != NULL) {
- /* restart a pending action */
- set_current_action(next->get_pending());
- next->set_pending(NULL);
- next->set_state(THREAD_READY);
- return true;
- }
+ return next_thrd;
+}
- /* Return false only if swap fails with an error */
- return (Thread::swap(&system_context, next) == 0);
+/** Wrapper to run the user's main function, with appropriate arguments */
+void user_main_wrapper(void *)
+{
+ user_main(model->params.argc, model->params.argv);
}
-/** Runs the current execution until threre are no more steps to take. */
-void ModelChecker::finish_execution() {
- DBG();
+/** @brief Run ModelChecker for the user program */
+void ModelChecker::run()
+{
+ do {
+ thrd_t user_thread;
+ Thread *t = new Thread(&user_thread, &user_main_wrapper, NULL, NULL);
+ add_thread(t);
+
+ do {
+ /*
+ * Stash next pending action(s) for thread(s). There
+ * should only need to stash one thread's action--the
+ * thread which just took a step--plus the first step
+ * for any newly-created thread
+ */
+ for (unsigned int i = 0; i < get_num_threads(); i++) {
+ thread_id_t tid = int_to_id(i);
+ Thread *thr = get_thread(tid);
+ if (!thr->is_model_thread() && !thr->is_complete() && !thr->get_pending()) {
+ switch_from_master(thr);
+ }
+ }
+
+ /* Catch assertions from prior take_step or from
+ * between-ModelAction bugs (e.g., data races) */
+ if (has_asserted())
+ break;
+
+ /* Consume the next action for a Thread */
+ ModelAction *curr = t->get_pending();
+ t->set_pending(NULL);
+ t = take_step(curr);
+ } while (t && !t->is_model_thread());
- while (take_step());
+ /*
+ * Launch end-of-execution release sequence fixups only when
+ * the execution is otherwise feasible AND there are:
+ *
+ * (1) pending release sequences
+ * (2) pending assertions that could be invalidated by a change
+ * in clock vectors (i.e., data races)
+ * (3) no pending promises
+ */
+ while (!pending_rel_seqs->empty() &&
+ is_feasible_prefix_ignore_relseq() &&
+ !unrealizedraces.empty()) {
+ model_print("*** WARNING: release sequence fixup action "
+ "(%zu pending release seuqence(s)) ***\n",
+ pending_rel_seqs->size());
+ ModelAction *fixup = new ModelAction(MODEL_FIXUP_RELSEQ,
+ std::memory_order_seq_cst, NULL, VALUE_NONE,
+ model_thread);
+ take_step(fixup);
+ };
+ } while (next_execution());
+
+ model_print("******* Model-checking complete: *******\n");
+ print_stats();
}
projects / model-checker.git / blobdiff