RFR: 8343827: RISC-V: set AlignVector as false if applicable to enable SLP

[Vladimir Kempik]

On Tue, 12 Nov 2024 00:22:27 GMT, Fei Yang <fyang at openjdk.org> wrote:

> > hello Hamlin, this could to be wrong. for example: kendryte 230 with c908 core with rv64gcv it has fast misaligned access but only for scalars(rv64gc), not for vectors(rvv) i dont know if it's just a corner case or a possible common practice in future.
> 
> Interesting. Could it be an issue for the kernel running on this platform? I don't understand why it would declare fast misaligned access when it's not the case for the vector part.

for this particular case, it has kernel 5.10 which has no hwprobe. so avoidUnaligned has to be disabled manually. 
but there are more boards based on c908 core which needs to be checked with this change. 
while the c908 isnt the thing we should care much about, right now i think boards with c908 are the main test mule to check  jdk rvv performance changes

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PR Comment: https://git.openjdk.org/jdk/pull/21974#issuecomment-2469809440