[PATCH] Sunbug 7131192: Optimize BigInteger.doubleValue(), floatValue()

Joseph Darcy joe.darcy at oracle.com
Sat Jul 14 01:20:37 UTC 2012


Hello,

Thanks for the patch Louis.

On 7/12/2012 3:21 AM, Andrew Haley wrote:
> On 07/12/2012 10:32 AM, Louis Wasserman wrote:
>> It was attached to the previous message?  I don't know if this list works
>> with attachments.  Alternately, the patch was attached here:
>> https://bugs.openjdk.java.net/show_bug.cgi?id=100222
>>
>> I'm not sure what you mean by double-rounding bugs, though.  It's
>> not difficult to actually implement the HALF_EVEN rounding behavior
>> with bit twiddling.
> Sure, as long as you've thought about it and done it carefully.  The
> bit twiddling is easy to do, and easy to get wrong.
>
> > From the supplied patch it looks like you've done a good job, but
> there was no way to tell without it.  I presume the listserv dropped
> it on the floor.
>
> Andrew.

I've taken a quick look at the patch.  The concept for the change is 
good; the current path of converting to float/double through a string is 
a simple but very roundabout way to accomplish this task.

Unfortunately, I'm saturated with the JDK bug migration [1] and will 
continue to be saturated for at least several more weeks so I won't be 
able to take a more detailed look at the patch for a while.  I suspect 
some more directly test cases will be needed to test tricky rounding 
situations.

Thanks,

-Joe

[1] https://blogs.oracle.com/darcy/entry/moving_monarchs_dragons



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