X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=model.cc;h=0bccd833ff843e40fd700f8ea3f198b1a2f4e065;hb=1ef66fffe44c297326b1043cab978789b1071704;hp=01e4c491a9e637cb1c1ffd2b78607c82f2472e82;hpb=61eabdb86ab3a0a9a3051bd0bbf4dfed2172fdce;p=c11tester.git

diff --git a/model.cc b/model.cc
index 01e4c491..0bccd833 100644
--- a/model.cc
+++ b/model.cc
@@ -159,6 +159,14 @@ void ModelChecker::reset_to_initial_state()
 	/* 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);
 }
 
@@ -203,11 +211,14 @@ Node * ModelChecker::get_curr_node() const
  * 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)
 {
@@ -221,9 +232,12 @@ Thread * ModelChecker::get_next_thread(ModelAction *curr)
 			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();
@@ -319,11 +333,22 @@ 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;
@@ -2648,6 +2673,19 @@ 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
@@ -2700,35 +2738,10 @@ Thread * ModelChecker::take_step(ModelAction *curr)
 		scheduler->remove_thread(curr_thrd);
 
 	Thread *next_thrd = get_next_thread(curr);
-	next_thrd = scheduler->next_thread(next_thrd);
 
 	DEBUG("(%d, %d)\n", curr_thrd ? id_to_int(curr_thrd->get_id()) : -1,
 			next_thrd ? id_to_int(next_thrd->get_id()) : -1);
 
-	/*
-	 * 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_thrd || next_thrd->is_model_thread()) &&
-			is_feasible_prefix_ignore_relseq() && !unrealizedraces.empty()) {
-		model_print("*** 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);
-		model_thread->set_pending(fixup);
-		return model_thread;
-	}
-
-	/* next_thrd == NULL -> don't take any more steps */
-	if (!next_thrd)
-		return NULL;
-
 	return next_thrd;
 }
 
@@ -2747,12 +2760,17 @@ void ModelChecker::run()
 		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()) {
-					scheduler->next_thread(thr);
-					Thread::swap(&system_context, thr);
+					switch_from_master(thr);
 				}
 			}
 
@@ -2766,8 +2784,29 @@ void ModelChecker::run()
 			t->set_pending(NULL);
 			t = take_step(curr);
 		} while (t && !t->is_model_thread());
-		/** @TODO Re-write release sequence fixups here */
+
+		/*
+		 * 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();
 }