/** Merge the congruence classes containing vertices v1 and v2.; */
public void mergeClasses(OPT_ValueGraphVertex v1, OPT_ValueGraphVertex v2) {
if (DEBUG) {
System.out.println("@@@@ mergeClasses called with v1 = " + v1 + " ; v2 = " + v2);
}
int val1 = v1.getValueNumber();
int val2 = v2.getValueNumber();
if (val1 == val2) return;
OPT_GVCongruenceClass class1 = (OPT_GVCongruenceClass) B.get(val1);
while (true) {
OPT_GVCongruenceClass class2 = (OPT_GVCongruenceClass) B.get(val2);
Iterator i = class2.iterator();
if (!i.hasNext()) break;
OPT_ValueGraphVertex v = (OPT_ValueGraphVertex) i.next();
if (DEBUG)
System.out.println("@@@@ moving vertex " + v + " from class " + val2 + " to class " + val1);
class1.addVertex(v);
class2.removeVertex(v);
v.setValueNumber(val1);
}
// Null out entry for val2
B.set(val2, null);
}
/** Print the value numbers for each node in the value graph. */
public void printValueNumbers() {
for (Enumeration e = valueGraph.enumerateVertices(); e.hasMoreElements(); ) {
OPT_ValueGraphVertex v = (OPT_ValueGraphVertex) e.nextElement();
int valueNumber = v.getValueNumber();
OPT_GVCongruenceClass c = (OPT_GVCongruenceClass) B.get(valueNumber);
System.out.println(v.name + " " + valueNumber + " " + c.getLabel());
}
}
/**
* Definitely-different relation for two value numbers. Returns true for the following cases:
*
* <ul>
* <li>v1 and v2 are both constants, but don't match
* <li>v1 and v2 both result from NEW statements, but don't match
* <li>one of v1 and v2 is a parameter, and the other results from a new statement
* </ul>
*
* <p>TODO: add more smarts
*
* @param v1 first value number
* @param v2 second value number
* @return true iff the value numbers for two variables are definitely different
*/
public boolean DD(int v1, int v2) {
if ((v1 == -1) || (v2 == -1)) return false;
OPT_GVCongruenceClass class1 = (OPT_GVCongruenceClass) B.get(v1);
OPT_GVCongruenceClass class2 = (OPT_GVCongruenceClass) B.get(v2);
Object label1 = class1.getLabel();
Object label2 = class2.getLabel();
// if one is a constant, they must both be ...
if (isConstant(label1) && !isConstant(label2)) return false;
if (!isConstant(label1) && isConstant(label2)) return false;
if (isConstant(label1)) return (v1 != v2);
// handle DD for allocations
if (isBornAtAllocation(label1)) {
if (isBornAtAllocation(label2)) {
// both are NEW. Are they dd?
return (v1 != v2);
} else if (class2.containsParameter()) {
// one is NEW, other is parameter. They are DD.
return true;
}
} else {
if (isBornAtAllocation(label2)) {
if (class1.containsParameter()) {
// one is NEW, other is parameter. They are DD.
return true;
}
}
}
// assume parameters are not aliased?
if (NO_PARAM_ALIAS) {
if (v1 != v2) {
if (class1.containsParameter()) {
if (class2.containsParameter()) {
return true;
}
}
}
}
// if we haven't figured out they're DD, return false;
return false;
}
public OPT_GVCongruenceClass congruenceClass(Object name) {
OPT_ValueGraphVertex v = valueGraph.getVertex(name);
return ((OPT_GVCongruenceClass) B.get(v.getValueNumber()));
}