// Returns the number of descendants with the specified type.
private int countsOperations(int op) {
int ret = 0;
if (children == null) return ret;
for (SimpleExpression child : children) ret += child.countsOperations(op);
if (sop == op) ret += children.size() - 1;
return ret;
}
// Aggressively normalize divisible expressions to minimize ADD operations.
// This method is called only by induction variable substitution where
// the divisibility of an expression is defined well.
protected SimpleExpression normalizeDivisible() {
SimpleExpression ret = this;
if (sop == DIV) {
if (getChild(0).sop == DIV)
ret = divide(getChild(0).getChild(0), multiply(getChild(0).getChild(1), getChild(1)));
} else if (sop == MUL) {
ret = toDivision().normalize();
} else if (sop == ADD) {
ret = toDivision();
if (ret.sop == DIV && ret.getChild(0).sop == ADD) {
SimpleExpression non_div = szero, dividend = szero;
SimpleExpression divider = ret.getChild(1);
for (SimpleExpression child : ret.getChild(0).children) {
SimpleExpression divided = divide(child, divider);
if (divided.sop == DIV) dividend = add(dividend, child);
else non_div = add(non_div, divided);
}
if (non_div.equals(szero) && ret.countsOperations(ADD) >= countsOperations(ADD))
ret = this; // heuristics: no benefit from the simplification.
else ret = add(non_div, divide(dividend, divider));
}
}
return ret;
}