RFR: 8325991: Accelerate Poly1305 on x86_64 using AVX2 instructions [v4]

[Srinivas Vamsi Parasa]

On Thu, 22 Feb 2024 01:21:30 GMT, Sandhya Viswanathan <sviswanathan at openjdk.org> wrote:

>> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   remove unused uniions and fix uses_vl
>
> src/hotspot/cpu/x86/stubGenerator_x86_64_poly.cpp line 1252:
> 
>> 1250: 
>> 1251:   // Calculate R^2
>> 1252:   __ movq(t0, c1); // c1 = R1 + (R1 >> 2)
> 
> This move is not required. Function poly1305_multiply_scalar() is not using t0.

Please see the redundant mov removed.

> src/hotspot/cpu/x86/stubGenerator_x86_64_poly.cpp line 1364:
> 
>> 1362:   __ movq(t0, length);
>> 1363:   __ mov64(t1, 0xffffffffffffffc0);
>> 1364:   __ andq(t0, t1);
> 
> We could directly  do andq(t0, 0xffffffc0) here?

Please see the code updated to andq(t0, 0xffffffc0)

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PR Review Comment: https://git.openjdk.org/jdk/pull/17881#discussion_r1500138535
PR Review Comment: https://git.openjdk.org/jdk/pull/17881#discussion_r1500137672