RFR: 8319716: RISC-V: Add SHA-2 [v12]

[Fei Yang]

On Fri, 5 Jan 2024 09:05:57 GMT, Robbin Ehn <rehn at openjdk.org> wrote:

>> Hi, please consider.
>> 
>> Main author is @luhenry, I only fixed some minor things and tested it.
>> 
>> Such as:
>> test/hotspot/jtreg/compiler/intrinsics/sha/
>> test/jdk/java/security/MessageDigest/
>> test/jdk/jdk/security/
>> tier1
>> 
>> And still running some test.
>
> 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 21 additional commits since the last revision:
> 
>  - Merge branch 'master' into sha256
>  - Fixed comment
>  - Fixed flags
>  - Fixed vlen 128
>  - Merge branch 'master' into sha256
>  - fixed lmul
>  - remove merge, renames
>  - Easier reg layout and 128/m2
>  - Minor update
>  - index store state back
>  - ... and 11 more: https://git.openjdk.org/jdk/compare/3cb4c349...2442b9c6

Two minor comments remain, otherwise looks good.

src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4029:

> 4027:       if (multi_block) {
> 4028:         int total_adds = vset_sew == Assembler::e32 ? 240 : 608;
> 4029:         __ addi(consts, consts, -total_adds);

Maybe leave a TODO about future investigation of preloading of constants in vector registers for SHA256?

src/hotspot/cpu/riscv/vm_version_riscv.cpp line 269:

> 267:       FLAG_SET_DEFAULT(UseChaCha20Intrinsics, true);
> 268:     }
> 269:   } if (UseChaCha20Intrinsics) {

What's the purpose of this change?

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PR Review: https://git.openjdk.org/jdk/pull/16562#pullrequestreview-1807963701
PR Review Comment: https://git.openjdk.org/jdk/pull/16562#discussion_r1444225566
PR Review Comment: https://git.openjdk.org/jdk/pull/16562#discussion_r1444133690