RFR (S) 8035974: Refactor DigestBase.engineUpdate() method for better code generation by JIT compiler

[james cheng]

On 5/23/2014 3:17 AM, Remi Forax wrote:
>
> On 05/23/2014 11:06 AM, Paul Sandoz wrote:
>> On May 22, 2014, at 1:34 AM, Vladimir Kozlov <vladimir.kozlov at oracle.com> wrote:
>>
>>> http://cr.openjdk.java.net/~kvn/8035974/webrev
>>> https://bugs.openjdk.java.net/browse/JDK-8035974
>>>
>>> Contributed by James Cheng and modified by me.
>>>
>> Looks good to me.
>>
>> Paul.
>
> implCompressMultiBlock should be private thus don't need to be final.
>
> Rémi

I pulled it out of engineUpdate() so kept it "protected final" as before.  I
just tried it with "private" and it still could be intrinsified.  So either way
is okay in terms of intrinsification.

Thanks,
-James

>
>>
>>> To use intrinsics to accelerate SHA operations on multiple blocks [1], it is needed to pull a loop out of DigestBase.engineUpdate() and make a new method
>>> implCompressMultiBlock() which contains only the loop and can be intrinsified.
>>>
>>> On platforms which does not use intrinsic implCompressMultiBlock() method will be inlined by JIT and the same code will be generated as before. So no performance
>>> regression with the pure Java SUN provider is expected.
>>>
>>> About arithmetic change. limit = ofs + len will not overflow integer because ofs <= b.length - len (there is check).
>>>
>>> Tested with jdk jtreg tests and new hotspot jtreg test James wrote for 8035968.
>>>
>>> Thanks,
>>> Vladimir
>>>
>>> [1] https://bugs.openjdk.java.net/browse/JDK-8035968
>