2009/5/8 Tim Ellison <[email protected]>:
> Egor Pasko wrote:
>> Ian Rogers wrote:
>>> - is it worth specializing the code in Arrays.lessThan to something
>>> like (I don't think Jikes RVM can inline compareTo and achieve an
>>> equivalent transformation and it saves quite a number of compares):
>>>
>>> private static boolean lessThan(float float1, float float2) {
>>> // Non-zero, non-NaN checking.
>>> if (float2 > float1) {
>>> return true;
>>> }
>>> if (float1 >= float2 && 0.0f != float1) {
>>> return false;
>>> }
>
> For correctness, this got committed as
> + if (float1 >= float2 && (0.0f != float1 || 0.0f != float2)) {
> + return false;
> + }
>
> The problem is that if you pass in float1 or float2 == +/-0.0 (which
> Roger is apparently doing regularly) then it will fall through to the
> slow rawintbits computation.
Roger? Thanks for the fix :-)
>>> // NaNs are equal to other NaNs and larger than any other float
>>> if (isNaN(float1)) {
>>> return false;
>>> } else if (isNaN(float2)) {
>>> return true;
>>> }
>>> // Deal with +0.0 and -0.0
>>> int f1 = floatToRawIntBits(float1);
>>> int f2 = floatToRawIntBits(float2);
>>> return f1 < f2;
>>> }
>
> I think it would be better to separate out the > and == tests, i.e.:
> - if (float1 >= float2 && (0.0f != float1 || 0.0f != float2)) {
> + if (float1 > float2) {
> return false;
> }
> + if (float1 == float2 && 0.0f != float1) {
> + return false;
> + }
>
> WDYT?
I agree :-)
Regards,
Ian
