2 #define __STDC_FORMAT_MACROS
7 #include "clockvector.h"
9 #include "threads-model.h"
10 #include "nodestack.h"
12 #define ACTION_INITIAL_CLOCK 0
14 /** @brief A special value to represent a successful trylock */
15 #define VALUE_TRYSUCCESS 1
17 /** @brief A special value to represent a failed trylock */
18 #define VALUE_TRYFAILED 0
21 * @brief Construct a new ModelAction
23 * @param type The type of action
24 * @param order The memory order of this action. A "don't care" for non-ATOMIC
25 * actions (e.g., THREAD_* or MODEL_* actions).
26 * @param loc The location that this action acts upon
27 * @param value (optional) A value associated with the action (e.g., the value
28 * read or written). Defaults to a given macro constant, for debugging purposes.
29 * @param thread (optional) The Thread in which this action occurred. If NULL
30 * (default), then a Thread is assigned according to the scheduler.
32 ModelAction::ModelAction(action_type_t type, memory_order order, void *loc,
33 uint64_t value, Thread *thread) :
39 reads_from_promise(NULL),
40 last_fence_release(NULL),
42 seq_number(ACTION_INITIAL_CLOCK),
46 /* References to NULL atomic variables can end up here */
47 ASSERT(loc || type == ATOMIC_FENCE || type == MODEL_FIXUP_RELSEQ);
49 Thread *t = thread ? thread : thread_current();
50 this->tid = t->get_id();
53 /** @brief ModelAction destructor */
54 ModelAction::~ModelAction()
57 * We can't free the clock vector:
58 * Clock vectors are snapshotting state. When we delete model actions,
59 * they are at the end of the node list and have invalid old clock
60 * vectors which have already been rolled back to an unallocated state.
68 void ModelAction::copy_from_new(ModelAction *newaction)
70 seq_number = newaction->seq_number;
73 void ModelAction::set_seq_number(modelclock_t num)
75 /* ATOMIC_UNINIT actions should never have non-zero clock */
76 ASSERT(!is_uninitialized());
77 ASSERT(seq_number == ACTION_INITIAL_CLOCK);
81 bool ModelAction::is_thread_start() const
83 return type == THREAD_START;
86 bool ModelAction::is_thread_join() const
88 return type == THREAD_JOIN;
91 bool ModelAction::is_relseq_fixup() const
93 return type == MODEL_FIXUP_RELSEQ;
96 bool ModelAction::is_mutex_op() const
98 return type == ATOMIC_LOCK || type == ATOMIC_TRYLOCK || type == ATOMIC_UNLOCK || type == ATOMIC_WAIT || type == ATOMIC_NOTIFY_ONE || type == ATOMIC_NOTIFY_ALL;
101 bool ModelAction::is_lock() const
103 return type == ATOMIC_LOCK;
106 bool ModelAction::is_wait() const {
107 return type == ATOMIC_WAIT;
110 bool ModelAction::is_notify() const {
111 return type == ATOMIC_NOTIFY_ONE || type == ATOMIC_NOTIFY_ALL;
114 bool ModelAction::is_notify_one() const {
115 return type == ATOMIC_NOTIFY_ONE;
118 bool ModelAction::is_unlock() const
120 return type == ATOMIC_UNLOCK;
123 bool ModelAction::is_trylock() const
125 return type == ATOMIC_TRYLOCK;
128 bool ModelAction::is_success_lock() const
130 return type == ATOMIC_LOCK || (type == ATOMIC_TRYLOCK && value == VALUE_TRYSUCCESS);
133 bool ModelAction::is_failed_trylock() const
135 return (type == ATOMIC_TRYLOCK && value == VALUE_TRYFAILED);
138 /** @return True if this operation is performed on a C/C++ atomic variable */
139 bool ModelAction::is_atomic_var() const
141 return is_read() || could_be_write();
144 bool ModelAction::is_uninitialized() const
146 return type == ATOMIC_UNINIT;
149 bool ModelAction::is_read() const
151 return type == ATOMIC_READ || type == ATOMIC_RMWR || type == ATOMIC_RMW;
154 bool ModelAction::is_write() const
156 return type == ATOMIC_WRITE || type == ATOMIC_RMW || type == ATOMIC_INIT || type == ATOMIC_UNINIT;
159 bool ModelAction::could_be_write() const
161 return is_write() || is_rmwr();
164 bool ModelAction::is_yield() const
166 return type == THREAD_YIELD;
169 bool ModelAction::is_rmwr() const
171 return type == ATOMIC_RMWR;
174 bool ModelAction::is_rmw() const
176 return type == ATOMIC_RMW;
179 bool ModelAction::is_rmwc() const
181 return type == ATOMIC_RMWC;
184 bool ModelAction::is_fence() const
186 return type == ATOMIC_FENCE;
189 bool ModelAction::is_initialization() const
191 return type == ATOMIC_INIT;
194 bool ModelAction::is_relaxed() const
196 return order == std::memory_order_relaxed;
199 bool ModelAction::is_acquire() const
202 case std::memory_order_acquire:
203 case std::memory_order_acq_rel:
204 case std::memory_order_seq_cst:
211 bool ModelAction::is_release() const
214 case std::memory_order_release:
215 case std::memory_order_acq_rel:
216 case std::memory_order_seq_cst:
223 bool ModelAction::is_seqcst() const
225 return order == std::memory_order_seq_cst;
228 bool ModelAction::same_var(const ModelAction *act) const
230 if (act->is_wait() || is_wait()) {
231 if (act->is_wait() && is_wait()) {
232 if (((void *)value) == ((void *)act->value))
234 } else if (is_wait()) {
235 if (((void *)value) == act->location)
237 } else if (act->is_wait()) {
238 if (location == ((void *)act->value))
243 return location == act->location;
246 bool ModelAction::same_thread(const ModelAction *act) const
248 return tid == act->tid;
251 void ModelAction::copy_typeandorder(ModelAction * act)
253 this->type = act->type;
254 this->order = act->order;
258 * Get the Thread which is the operand of this action. This is only valid for
259 * THREAD_* operations (currently only for THREAD_CREATE and THREAD_JOIN). Note
260 * that this provides a central place for determining the conventions of Thread
261 * storage in ModelAction, where we generally aren't very type-safe (e.g., we
262 * store object references in a (void *) address.
264 * For THREAD_CREATE, this yields the Thread which is created.
265 * For THREAD_JOIN, this yields the Thread we are joining with.
267 * @return The Thread which this action acts on, if exists; otherwise NULL
269 Thread * ModelAction::get_thread_operand() const
271 if (type == THREAD_CREATE) {
272 /* THREAD_CREATE stores its (Thread *) in a thrd_t::priv */
273 thrd_t *thrd = (thrd_t *)get_location();
275 } else if (type == THREAD_JOIN)
276 /* THREAD_JOIN uses (Thread *) for location */
277 return (Thread *)get_location();
283 * @brief Convert the read portion of an RMW
285 * Changes an existing read part of an RMW action into either:
286 * -# a full RMW action in case of the completed write or
287 * -# a READ action in case a failed action.
289 * @todo If the memory_order changes, we may potentially need to update our
292 * @param act The second half of the RMW (either RMWC or RMW)
294 void ModelAction::process_rmw(ModelAction *act)
296 this->order = act->order;
298 this->type = ATOMIC_READ;
299 else if (act->is_rmw()) {
300 this->type = ATOMIC_RMW;
301 this->value = act->value;
306 * @brief Check if this action should be backtracked with another, due to
307 * potential synchronization
309 * The is_synchronizing method should only explore interleavings if:
310 * -# the operations are seq_cst and don't commute or
311 * -# the reordering may establish or break a synchronization relation.
313 * Other memory operations will be dealt with by using the reads_from relation.
315 * @param act The action to consider exploring a reordering
316 * @return True, if we have to explore a reordering; otherwise false
318 bool ModelAction::could_synchronize_with(const ModelAction *act) const
320 // Same thread can't be reordered
321 if (same_thread(act))
324 // Different locations commute
328 // Explore interleavings of seqcst writes/fences to guarantee total
329 // order of seq_cst operations that don't commute
330 if ((could_be_write() || act->could_be_write() || is_fence() || act->is_fence()) && is_seqcst() && act->is_seqcst())
333 // Explore synchronizing read/write pairs
334 if (is_acquire() && act->is_release() && is_read() && act->could_be_write())
337 // lock just released...we can grab lock
338 if ((is_lock() || is_trylock()) && (act->is_unlock() || act->is_wait()))
341 // lock just acquired...we can fail to grab lock
342 if (is_trylock() && act->is_success_lock())
345 // other thread stalling on lock...we can release lock
346 if (is_unlock() && (act->is_trylock() || act->is_lock()))
349 if (is_trylock() && (act->is_unlock() || act->is_wait()))
352 if (is_notify() && act->is_wait())
355 if (is_wait() && act->is_notify())
358 // Otherwise handle by reads_from relation
362 bool ModelAction::is_conflicting_lock(const ModelAction *act) const
364 // Must be different threads to reorder
365 if (same_thread(act))
368 // Try to reorder a lock past a successful lock
369 if (act->is_success_lock())
372 // Try to push a successful trylock past an unlock
373 if (act->is_unlock() && is_trylock() && value == VALUE_TRYSUCCESS)
376 // Try to push a successful trylock past a wait
377 if (act->is_wait() && is_trylock() && value == VALUE_TRYSUCCESS)
384 * Create a new clock vector for this action. Note that this function allows a
385 * user to clobber (and leak) a ModelAction's existing clock vector. A user
386 * should ensure that the vector has already either been rolled back
387 * (effectively "freed") or freed.
389 * @param parent A ModelAction from which to inherit a ClockVector
391 void ModelAction::create_cv(const ModelAction *parent)
394 cv = new ClockVector(parent->cv, this);
396 cv = new ClockVector(NULL, this);
399 void ModelAction::set_try_lock(bool obtainedlock)
401 value = obtainedlock ? VALUE_TRYSUCCESS : VALUE_TRYFAILED;
405 * @brief Get the value read by this load
407 * We differentiate this function from ModelAction::get_write_value and
408 * ModelAction::get_value for the purpose of RMW's, which may have both a
409 * 'read' and a 'write' value.
411 * Note: 'this' must be a load.
413 * @return The value read by this load
415 uint64_t ModelAction::get_reads_from_value() const
419 return reads_from->get_write_value();
420 else if (reads_from_promise)
421 return reads_from_promise->get_value();
422 return VALUE_NONE; /* Only for new actions with no reads-from */
426 * @brief Get the value written by this store
428 * We differentiate this function from ModelAction::get_reads_from_value and
429 * ModelAction::get_value for the purpose of RMW's, which may have both a
430 * 'read' and a 'write' value.
432 * Note: 'this' must be a store.
434 * @return The value written by this store
436 uint64_t ModelAction::get_write_value() const
443 * @brief Get the value returned by this action
445 * For atomic reads (including RMW), an operation returns the value it read.
446 * For atomic writes, an operation returns the value it wrote. For other
447 * operations, the return value varies (sometimes is a "don't care"), but the
448 * value is simply stored in the "value" field.
450 * @return This action's return value
452 uint64_t ModelAction::get_return_value() const
455 return get_reads_from_value();
457 return get_write_value();
462 /** @return The Node associated with this ModelAction */
463 Node * ModelAction::get_node() const
465 /* UNINIT actions do not have a Node */
466 ASSERT(!is_uninitialized());
471 * Update the model action's read_from action
472 * @param act The action to read from; should be a write
474 void ModelAction::set_read_from(const ModelAction *act)
478 reads_from_promise = NULL;
479 if (act->is_uninitialized())
480 model->assert_bug("May read from uninitialized atomic\n");
484 * Set this action's read-from promise
485 * @param promise The promise to read from
487 void ModelAction::set_read_from_promise(Promise *promise)
490 reads_from_promise = promise;
495 * Synchronize the current thread with the thread corresponding to the
496 * ModelAction parameter.
497 * @param act The ModelAction to synchronize with
498 * @return True if this is a valid synchronization; false otherwise
500 bool ModelAction::synchronize_with(const ModelAction *act)
504 model->check_promises(act->get_tid(), cv, act->cv);
509 bool ModelAction::has_synchronized_with(const ModelAction *act) const
511 return cv->synchronized_since(act);
515 * Check whether 'this' happens before act, according to the memory-model's
516 * happens before relation. This is checked via the ClockVector constructs.
517 * @return true if this action's thread has synchronized with act's thread
518 * since the execution of act, false otherwise.
520 bool ModelAction::happens_before(const ModelAction *act) const
522 return act->cv->synchronized_since(this);
525 /** @brief Print nicely-formatted info about this ModelAction */
526 void ModelAction::print() const
528 const char *type_str, *mo_str;
529 switch (this->type) {
530 case MODEL_FIXUP_RELSEQ:
531 type_str = "relseq fixup";
534 type_str = "thread create";
537 type_str = "thread start";
540 type_str = "thread yield";
543 type_str = "thread join";
546 type_str = "thread finish";
549 type_str = "uninitialized";
552 type_str = "atomic read";
555 type_str = "atomic write";
558 type_str = "atomic rmw";
564 type_str = "atomic rmwr";
567 type_str = "atomic rmwc";
570 type_str = "init atomic";
579 type_str = "trylock";
584 case ATOMIC_NOTIFY_ONE:
585 type_str = "notify one";
587 case ATOMIC_NOTIFY_ALL:
588 type_str = "notify all";
591 type_str = "unknown type";
594 switch (this->order) {
595 case std::memory_order_relaxed:
598 case std::memory_order_acquire:
601 case std::memory_order_release:
604 case std::memory_order_acq_rel:
607 case std::memory_order_seq_cst:
615 model_print("(%4d) Thread: %-2d Action: %-13s MO: %7s Loc: %14p Value: %-#18" PRIx64,
616 seq_number, id_to_int(tid), type_str, mo_str, location, get_return_value());
619 model_print(" Rf: %-3d", reads_from->get_seq_number());
620 else if (reads_from_promise) {
621 int idx = model->get_promise_number(reads_from_promise);
623 model_print(" Rf: P%-2d", idx);
625 model_print(" Rf: P? ");
627 model_print(" Rf: ? ");
639 /** @brief Get a (likely) unique hash for this ModelAction */
640 unsigned int ModelAction::hash() const
642 unsigned int hash = (unsigned int)this->type;
643 hash ^= ((unsigned int)this->order) << 3;
644 hash ^= seq_number << 5;
645 hash ^= id_to_int(tid) << 6;
649 hash ^= reads_from->get_seq_number();
650 else if (reads_from_promise)
651 hash ^= model->get_promise_number(reads_from_promise);
652 hash ^= get_reads_from_value();
658 * @brief Checks the NodeStack to see if a ModelAction is in our may-read-from set
659 * @param write The ModelAction to check for
660 * @return True if the ModelAction is found; false otherwise
662 bool ModelAction::may_read_from(const ModelAction *write) const
664 for (int i = 0; i < node->get_read_from_past_size(); i++)
665 if (node->get_read_from_past(i) == write)
671 * @brief Checks the NodeStack to see if a Promise is in our may-read-from set
672 * @param promise The Promise to check for
673 * @return True if the Promise is found; false otherwise
675 bool ModelAction::may_read_from(const Promise *promise) const
677 for (int i = 0; i < node->get_read_from_promise_size(); i++)
678 if (node->get_read_from_promise(i) == promise)
684 * Only valid for LOCK, TRY_LOCK, UNLOCK, and WAIT operations.
685 * @return The mutex operated on by this action, if any; otherwise NULL
687 std::mutex * ModelAction::get_mutex() const
689 if (is_trylock() || is_lock() || is_unlock())
690 return (std::mutex *)get_location();
692 return (std::mutex *)get_value();