optimization - a given write can resolve at most one promise from a rmw
[model-checker.git] / nodestack.cc
index d08fa5c..22cc378 100644 (file)
@@ -105,11 +105,14 @@ void Node::print_may_read_from()
  * Sets a promise to explore meeting with the given node.
  * @param i is the promise index.
  */
-void Node::set_promise(unsigned int i) {
+void Node::set_promise(unsigned int i, bool is_rmw) {
        if (i >= promises.size())
                promises.resize(i + 1, PROMISE_IGNORE);
-       if (promises[i] == PROMISE_IGNORE)
+       if (promises[i] == PROMISE_IGNORE) {
                promises[i] = PROMISE_UNFULFILLED;
+               if (is_rmw)
+                       promises[i] |= PROMISE_RMW;
+       }
 }
 
 /**
@@ -118,7 +121,7 @@ void Node::set_promise(unsigned int i) {
  * @return true if the promise should be satisfied by the given model action.
  */
 bool Node::get_promise(unsigned int i) {
-       return (i < promises.size()) && (promises[i] == PROMISE_FULFILLED);
+       return (i < promises.size()) && ((promises[i] & PROMISE_MASK) == PROMISE_FULFILLED);
 }
 
 /**
@@ -127,16 +130,27 @@ bool Node::get_promise(unsigned int i) {
  */
 bool Node::increment_promise() {
        DBG();
-
+       unsigned int rmw_count=0;
        for (unsigned int i = 0; i < promises.size(); i++) {
-               if (promises[i] == PROMISE_UNFULFILLED) {
-                       promises[i] = PROMISE_FULFILLED;
+               if (promises[i]==(PROMISE_RMW|PROMISE_FULFILLED))
+                       rmw_count++;
+       }
+       
+       for (unsigned int i = 0; i < promises.size(); i++) {
+               if ((promises[i] & PROMISE_MASK) == PROMISE_UNFULFILLED) {
+                       if ((rmw_count > 0) && (promises[i] & PROMISE_RMW)) {
+                               //sending our value to two rmws... not going to work..try next combination
+                               continue;
+                       }
+                       promises[i] = (promises[i] & PROMISE_RMW) |PROMISE_FULFILLED;
                        while (i > 0) {
                                i--;
-                               if (promises[i] == PROMISE_FULFILLED)
-                                       promises[i] = PROMISE_UNFULFILLED;
+                               if ((promises[i] & PROMISE_MASK) == PROMISE_FULFILLED)
+                                       promises[i] = (promises[i] & PROMISE_RMW) | PROMISE_UNFULFILLED;
                        }
                        return true;
+               } else if (promises[i] == (PROMISE_RMW|PROMISE_FULFILLED)) {
+                       rmw_count--;
                }
        }
        return false;
@@ -147,9 +161,22 @@ bool Node::increment_promise() {
  * @return true if we have explored all promise combinations.
  */
 bool Node::promise_empty() {
-       for (unsigned int i = 0; i < promises.size();i++)
-               if (promises[i] == PROMISE_UNFULFILLED)
+       unsigned int rmw_count=0;
+       for (unsigned int i = 0; i < promises.size(); i++) {
+               if (promises[i]==(PROMISE_RMW|PROMISE_FULFILLED))
+                       rmw_count++;
+       }
+
+       for (unsigned int i = 0; i < promises.size();i++) {
+               if ((promises[i]& PROMISE_MASK) == PROMISE_UNFULFILLED) {
+                       //if this isn't a feasible option, keep going
+                       if ((rmw_count > 0)&&(promises[i] & PROMISE_RMW))
+                               continue;
                        return false;
+               } else if (promises[i] == (PROMISE_RMW|PROMISE_FULFILLED)) {
+                       rmw_count--;
+               }
+       }
        return true;
 }