instruct loadI2L_immI(iRegL dst, memory mem, immI mask, iRegI tmp) %{
  match(Set dst (ConvI2L (AndI (LoadI mem) mask)));

From inspection, it appears that this rule (on all platforms) only works if the result of the AndI
doesn't need to be sign-extended (>= 0).  My first attempt at a test program didn't work.  For
some reason when using an array, C2 only takes a fast path if the value is positive:

    static long foo(int[] x) {
        return x[0] & 0xfffffffe;
    }

However, using a field instead doesn't have that problem.

% cat a.java
public class a {
    static int x;
    static long foo() {
        return x & 0xfffffffe;
    }

    public static void main(String[] args) {
        x = -1;
        long l = 0;
        for (int i = 0; i < 100000; ++i) {
            l = foo();
        }
        System.out.println(l);
    }
}
% ./bin/java -Xint a
-2
% ./bin/java -XX:-TieredCompilation -server a
4294967294