RFR: 8302191: Performance degradation for float/double modulo on Linux

[David Holmes]

On Fri, 10 Feb 2023 09:06:56 GMT, Jan Kratochvil <duke at openjdk.org> wrote:

> I have OCA already processed/approved. I am not Author but my Author request is being processed these days (sent to Rob McKenna).
> I did regression test x86_64 OpenJDK-8. I will leave other regression testing on GHA.
> The patch (and former GCC performance regression) affects only x86_64+i686.

Correction, now IIUC gcc made the change because the code was incorrect in the general sense, and so would only be used when enabled explicitly. So the VM use of fmod started compiling into a more correct but slower form. The claim here is that it is okay for the VM to use the "incorrect" form, and that is being provided directly by use of `fprem`.

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PR: https://git.openjdk.org/jdk/pull/12508