Rounding differences between 1.8 and 1.7 (including -Xint mode).

Dawid Weiss dawid.weiss at
Sat Jul 21 02:29:10 PDT 2012

Thanks Vladimir.

I will try to narrow it down although it may be hard because of the
complexity of components involved. I know for sure that the difference is
by one on raw long representation so it looks like rounding issues but I
will take a closer look.

Unfortunately I am on vacation this week but I will do it early next week

On Jul 21, 2012 12:18 AM, "Vladimir Kozlov" <vladimir.kozlov at>

> Dawid,
> It would be nice if you can provide a test case for us. What jdk8 build
> you are using?
> We recently changed implementation of exp() and pow() in VM on x86 from C
> code to use FPU instructions. It created a bugs tail. The latest bug
> 7177917 was fixed in jdk8b48.
> Thanks,
> Vladimir
> Dawid Weiss wrote:
>> Hi everyone.
>> We observe test regressions on fairly complex computational code
>> resulting from small differences in double roundings. They show up
>> when executed with latest 1.8 snapshot (compared to 1.7 and 1.6). Also
>> applies when run in interpreted mode (-Xint).
>> I was wondering if this is something to be expected? Thanks,
>> Dawid
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