On 13/10/15 10:22, Paul Sandoz wrote:
> Analysis so far indicate big gains are to be had on larger arrays with better
> or no impact on small arrays if i do the following instead:
>
> if (Double.doubleToRawLongBits(a[i]) !=
> Double.doubleToRawLongBits(b[i])) {
> int c = Double.compare(a[i], b[i]);
> if (c != 0) return c;
> }
I was about to make a similar comment. My experiment was with
if (Double.doubleToRawLongBits(a[i]) != Double.doubleToRawLongBits(b[i])
&& (Double.doubleToLongBits(a[i]) !=
Double.doubleToLongBits(b[i])))
return Double.compare(a[i], b[i]);
}
which is about twice as fast as the original version, as is yours.
But yours is more elegant. :-)
It's a shame that HotSpot doesn't see through the load of a
double and then the conversion through doubleToRawLongBits:
it could just load directly into the integer registers.
Andrew.
