vladimir.kozlov at oracle.com
Sat Sep 9 03:22:04 UTC 2017
On 9/8/17 8:17 AM, Dmitrij wrote:
> Hi Andrew,
> I support the idea of intrinsifying Math.multiplyHigh method: it seems like it will be very effective to implement at
> least on aarch64 and x86_64 using umulh and mulq instructions.
> Vladimir, what do you think?
Nobody asked to intrinsify these methods before because they are new in JDK 9 I think.
> If there are no other volunteer I'd be happy to do this.
Yes, please do that for both: aarch64 and x64. Add jtreg hotspot test too, please.
> Enhancing java.lang.Math intrinsics situation for aarch64 port is on my todo list.
> On 08.09.2017 17:38, Andrew Haley wrote:
>> I notice that Math.multiplyHigh(long, long) doesn't use a C2 intrinsic,
>> even on machines with appropriate C2 patterns. So it's rather slow.
>> JDK-5100935, No way to access the 64-bit integer multiplication of
>> 64-bit CPUs efficiently, is closed, even though there is still no
>> efficient way to do this. Is writing an intrinsic for multiplyHigh on
>> someone's to-do list? I see no bug for it.
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