RFR: 6506405: Math.abs(float) is slow [v9]

[Tagir F.Valeev]

On Mon, 12 Jul 2021 17:59:32 GMT, Brian Burkhalter <bpb at openjdk.org> wrote:

>> Please consider this change to make the `float` and `double` versions of `java.lang.Math.abs()` branch-free.
>
> Brian Burkhalter has refreshed the contents of this pull request, and previous commits have been removed. The incremental views will show differences compared to the previous content of the PR.

I wonder when this improvement actually takes place. I see that there's equivalent asm [generated](https://github.com/openjdk/jdk/blob/87d2761f1b4572633de020b2d4681918c6f10f06/src/hotspot/cpu/x86/x86.ad#L3215) for x86 for 10 years already. Why the intrinsified version doesn't work on Linux, so changes in Java result in performance improvement? Just curious. Thanks.

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PR: https://git.openjdk.java.net/jdk/pull/4711