RFR: 8322179: RISC-V: Implement SHA-1 intrinsic [v10]

[Hamlin Li]

On Sat, 17 Feb 2024 13:27:19 GMT, Fei Yang <fyang at openjdk.org> wrote:

>> Hamlin Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   refine register usage and comment
>
> src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4953:
> 
>> 4951:       __ rolw_imm(cur_w, a, 5, t0);
>> 4952:       // as pointed above, we can use cur_w as temporary register here.
>> 4953:       sha1_f(round, tmp, b, c, d);
> 
> Could we also reuse `cur_k` in this function where input param `tmp` is used? I see `cur_k` will also be recalculated at the beginning of each round like `cur_w`. Hope this could help eliminate `tmp` param and finally free `t2`.

Seems not, as cur_k is only calculated when `(round % 20) == 0`.

Other comments are all resolved.

> src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 5123:
> 
>> 5121: 
>> 5122:     if (multi_block) {
>> 5123:       __ bge(limit, buf, L_sha1_loop, true);
> 
> A small question: Is it OK to continue the loop when `limit` equals `buf`?

I think the answer to your question is at https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/sun/security/provider/DigestBase.java#L130, the `limit` is indeed `limit - blockSize`, hope this answer your question?

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PR Review Comment: https://git.openjdk.org/jdk/pull/17130#discussion_r1497850315
PR Review Comment: https://git.openjdk.org/jdk/pull/17130#discussion_r1497850122