RFR: 8238669: Long.divideUnsigned is extremely slow for certain values (Needs to be Intrinsic)

[Raffaello Giulietti]

Hi Brian,

thanks for taking a look.

I didn't write JMH benchmarks.


Greetings
Raffaello



On 2020-09-02 16:25, Brian Burkhalter wrote:
> Hi Raffaello,
> 
> I can take a look. Did you write any (JMH?) microbenchmarks?
> 
> Thanks,
> 
> Brian
> 
>> On Sep 2, 2020, at 5:52 AM, Raffaello Giulietti 
>> <raffaello.giulietti at gmail.com <mailto:raffaello.giulietti at gmail.com>> 
>> wrote:
>>
>> here's a patch for [1], which is currently unassigned. Anybody willing 
>> to sponsor it?
>>
>> The fix is based on "Hacker's Delight" (2nd ed), section 9.3 and makes 
>> use of longs only, no BigInteger, no garbage to collect. It is faster 
>> and "greener" than the current code.
>>
>> Contrary to the dramatic plea in the subject, with this fix I think 
>> there's no pressing need for an intrinsic.
>>
>> The fix should be back-portable to 11 and 8, where the methods first 
>> appeared, but I only tried on a current changeset [2].
>>
>> Passes tier1.
>>
>> If anybody needs the fix as attachment, just let me know.
>