[aarch64-port-dev ] [16] RFR(S): 8251525: AARCH64: Faster Math.signum(fp)

[Dmitry Chuyko]

I pushed the change for signum, and opened an RFE [1] for fp 
re-materialization on aarch64. We've made some experiments already. On 
N1 simply enabling it makes workloads like Lucene geo search ~0.7% 
faster, will get back with more data.

I haven't made RFE for "Constants as TEMPs" but will be glad to participate.

-Dmitry

[1] https://bugs.openjdk.java.net/browse/JDK-8252760

On 9/3/20 11:34 AM, Andrew Haley wrote:
> On 02/09/2020 18:40, Vladimir Ivanov wrote:
>> C2 doesn't rematerialize FP constants on AArch64
> I think that's probably right, even though a few FP constants are
> cheap. Loads from L1 usually have a 4 (or 5) cycle latency, which can
> make spilling constants expensive around calls. We could be smarter
> about this.
>