RFR: 8323116: [REDO] Computational test more than 2x slower when AVX instructions are used [v5]

[Sandhya Viswanathan]

On Fri, 5 Apr 2024 17:46:17 GMT, Vladimir Kozlov <kvn at openjdk.org> wrote:

>> Srinivas Vamsi Parasa has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   fix failure for KNL
>
> My new testing passed. 
> But I want to hear an answer to @merykitty suggestion about using xmm15.

@vnkozlov  If I understand the proposal from @merykitty correctly, the suggestion is to reserve xmm15 as non allocatable throughout. This sounds like a big overhead for cases where every xmm register is usable say in a Vector API kernel. From Vamsi's microbenchmark runs, he has clearly shown that the gain of his optimization is way more than any overhead of doing pxor just before the converts.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/18503#issuecomment-2040372881