RFR: 8315716: RISC-V: implement ChaCha20 intrinsic

[Ludovic Henry]

On Tue, 26 Sep 2023 17:43:15 GMT, Hamlin Li <mli at openjdk.org> wrote:

>> src/hotspot/cpu/riscv/stubGenerator_riscv.cpp line 4342:
>> 
>>> 4340:     // Put 16 here, as com.sun.crypto.providerChaCha20Cipher.KS_MAX_LEN is 1024
>>> 4341:     // in java level.
>>> 4342:     __ li(avl, 16);
>> 
>> It's recommended to use `__ mv(avl, 16);` to copy a constant to a register.
>
> Is there a difference between mv and li? Seems that mv(...) is calling li(...)?
> 
>   template<typename T, ENABLE_IF(std::is_integral<T>::value)>
>   inline void mv(Register Rd, T o)                    { li(Rd, (int64_t)o); }
> 
> Or the recommendation is a code convention?

It's only code convention in Hotspot.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15899#discussion_r1338340087