RFR: 6506405: Math.abs(float) is slow [v2]

[Joe Darcy]

On 7/8/2021 3:50 AM, Andrew Haley wrote:
> On Thu, 8 Jul 2021 09:43:35 GMT, Andrew Haley <aph at openjdk.org> wrote:
>
>> Moves between GPRs and FPRs are often slow. There's a 10-cycle latency on some AArch64, so we avoid it whenever we can. Mind you, we don't care about this patch because we always generate FABS from an intrinsic anyway.
> For avoidance of doubt, that's the round-trip latency.
>
> -------------
>
> PR: https://git.openjdk.java.net/jdk/pull/4711


For coding this functionality in Java, the natural way to do this uses 
either an if statement or the bit-wise conversion, which usually implies 
GPRs to/from FPRs movement. I don't see a way to avoid both an if 
statement and bitwise conversion.

-Joe