RFR: JDK-8216437 : PPC64: Add intrinsic for GHASH algorithm [v26]

[Suchismith Roy]

On Fri, 21 Feb 2025 16:21:49 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>> As per the algorithm mentioned section 6.4 in Power ISA, we need 2 loads to access from nearest aligned address(to the unaligned address) and the next aligned address. 
>> 
>> Without the vec_perm, I faced the issue of wrong control vectors generated due to Endianness. Hence I had to include them.
>
> Please understand my question correctly. I didn't propose to remove all `ver_perm`. The idea is to do the same job in the loop with one `vec_perm`.

Hi @TheRealMDoerr  Maybe my answer was not clear. I am not proposing to remove them. I am unable to decipher how to  reduce the 3 instructions to one, as I feel the below 2 lines are required , as per the algorithm.
 __ vec_perm(vTmp4, vHigh, vHigh, loadOrder);
 __ vec_perm(vTmp5, vLow, vLow, loadOrder);

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PR Review Comment: https://git.openjdk.org/jdk/pull/20235#discussion_r1965901600