RFR: 8319716: RISC-V: Add SHA-2 [v7]

[Robbin Ehn]

On Thu, 21 Dec 2023 12:44:25 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Robbin Ehn has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 11 additional commits since the last revision:
>> 
>>  - t2 caller saved, no need to push/pop
>>  - Merge branch 'master' into sha256
>>  - Removed swap file
>>  - Index load, other comment
>>  - Merge branch 'master' into sha256
>>  - Materialize constants address once
>>  - Removed template
>>  - Flag fixes
>>  - Merge branch 'master' into sha256
>>  - Share code
>>  - ... and 1 more: https://git.openjdk.org/jdk/compare/2ecad50c...be46fe4f
>
> src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4039:
> 
>> 4037:       __ vslideup_vi(v16, v27, 2);                     // v16 = {d,c,_,_}
>> 4038:       // Merge elements [1..0] of v26 ({a,b}) into elements [1..0] of v16
>> 4039:       __ vmerge_vvm(v16, v16, v26);                    // v16 = {d,c,b,a}
> 
> Hi, Great to see that we are switching to use index-load to get {f,e,b,a},{h,g,d,c} pre-loop. But I was also expecting to use index-store to put {f,e,b,a},{h,g,d,c} back to {a,b,c,d},{e,f,g,h} post-loop as I mentioned in my previous comment [1]. Seems that was missed? I would prefer to have this change before we go.
> 
> [1] https://github.com/openjdk/jdk/pull/16562#discussion_r1393767555

Yes, I missed that, thanks!

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PR Review Comment: https://git.openjdk.org/jdk/pull/16562#discussion_r1434094296