RFR: 8312425: [vectorapi] AArch64: Optimize vector math operations with SLEEF [v4]

[Andrew Haley]

On Mon, 27 Nov 2023 15:22:32 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

> In fact, I am not even sure why it seems to the PR author to be a good idea to let the default be dependent on the build machine at all. My personal opinion is that it would be better to select either "SVE enabled" or "SVE disabled" as the default, and then let the user override this on the configure command line, if they target a platform with different SVE availability.

SVE support should be enabled regardless of the build machine. The same binary must run on both SVE and non-SVE machines, using SVE if it is advantageous. I suppose some ancient C++ compilers without SVE support still exist, but I see no very good reason to support them building JDK 22+.

Making a configure option to disable SVE support for vector math is a mistake, but IMO mostly harmless because no-one will ever turn it off.

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PR Review Comment: https://git.openjdk.org/jdk/pull/16234#discussion_r1406450888