Optimization in std.algorithm.max?

[Jesse Phillips]

There is a good possibility that I don't know anything, but is there something about doing two checks that goes faster?

        static if (isIntegral!(T1) && isIntegral!(T2)
                   && (mostNegative!(T1) < 0) != (mostNegative!(T2) < 0))
            static if (mostNegative!(T1) < 0)
                immutable chooseB = b > a || a < 0;
            else
                immutable chooseB = b > a && b > 0;
        else
            immutable chooseB = b > a;

What has me baffled is the second checks after b > a. Doesn't b > a always answer the question? The only thing I can think of is a check for negative being faster, so shouldn't they come before the b > a check?