- * Optimizes simple tail-recursion calls by
- * converting them into loops. Depends on the flag opt_tail_recursion.
+ * Optimizes tail-recursion calls by converting them into loops.
+ * Depends on the flag opt_tail_recursion.
+ * Currently supports the following forms:
+ * - return func();
+ * - return x + func();
+ * - return func() - x;
+ * - return x * func();
+ * - return -func();