Schmidt, Lutz at
Tue Sep 19 14:26:48 UTC 2017


there is interest from these guys at SAP as well. I would volunteer to cover ppc and s390, once the initial implementation is available. Any ETA guess on that? I’m not pushing, just to get an idea.


On 09.09.2017, 05:22, "hotspot-compiler-dev on behalf of Vladimir Kozlov" <hotspot-compiler-dev-bounces at on behalf of vladimir.kozlov at> wrote:

    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.
    > Thanks,
    > Dmitrij
    > 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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