[aarch64-port-dev ] [PATCH] 8217561 : X86: Add floating-point Math.min/max intrinsics, approval request

Andrew Haley aph at redhat.com
Thu Feb 28 12:38:53 UTC 2019

On 2/28/19 9:54 AM, Andrew Haley wrote:
> On 2/27/19 8:21 PM, Vladimir Kozlov wrote:
>> So I have question for aarch64 developers. Are aarch64 fmin/fmax
>> instructions are always faster than code generated by default?
> Be aware that AArch64 is an abstract architecture, so it cannot be
> said to have performance properties.
> In real hardware, however, the answer is no. Nothing like. I have seen
> the fmin/fmax instructions cause a 3x slowdown on a reduction loop.

So Andrew Dinn asked me what machine, and what test. After some time
trying I confess that I cannot reproduce this result. I didn't think
much of it at the time, which was why I didn't record that
information. My apologies.

Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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