RFR: 8319781: RISC-V: Refactor UseRVV related checks

[Fei Yang]

On Thu, 9 Nov 2023 10:30:41 GMT, Hamlin Li <mli at openjdk.org> wrote:

> Hi,
> Can you review the patch to refactor the code related UseRVV checks?
> Thanks!
> 
> There are some code (flag setting/checking) depending on UseRVV's value, these code should be refactored, especially after the change of https://bugs.openjdk.org/browse/JDK-8319408:
> 1. some code needs to get the final UseRVV's value rather than the initial value, e.g. ChaCha20 intrinsic.
> 2. refactored to be more readable.
> 3. also add note to make sure the future code get the final UseRVV value instead of inital value.

Changes requested by fyang (Reviewer).

src/hotspot/cpu/riscv/vm_version_riscv.cpp line 295:

> 293: 
> 294:   if (!UseRVV) {
> 295:     FLAG_SET_DEFAULT(SpecialEncodeISOArray, false);

Could you please remove this line while you are on it? I don't think we need to reset `SpecialEncodeISOArray` here.

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PR Review: https://git.openjdk.org/jdk/pull/16580#pullrequestreview-1727476994
PR Review Comment: https://git.openjdk.org/jdk/pull/16580#discussion_r1391214061