RFR: 8284563: AArch64: bitperm feature detection for SVE2 on Linux [v2]

[Andrew Haley]

On Mon, 18 Apr 2022 11:06:05 GMT, Eric Liu <eliu at openjdk.org> wrote:

>> `STXR_PREFETCH` is usually done unconditionally in non-JVM code. Does it ever hurt performance? If not, let's get rid of `STXR_PREFETCH` and do prefetching unconditionally.
>
> @theRealAph 
> 
> TBH I don't know the history about this code. Considering that may impact the performance, I don't have too much confidence to dispose of  it in this patch.
> 
> Do you think it's fine to trace it in a separate JBS?

Absolutely, yes, getting rid of `STXR_PREFETCH` should be separate from this patch.

We need, as a group, to keep on top of accreting complexity. That's hard when the people changing code don't know the history of that code.

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PR: https://git.openjdk.java.net/jdk/pull/8258