RFR(L): 8074981 (Integer/FP scalar reduction optimization )

[Filipp Zhinkin]

Hi Michael,

thank you for contributing such a great improvement!

Sorry if my question is silly, but I'm curious wouldn't it be better to replace
integer scalar reduction variable with a vector "Rv" in loop's prologue,
compile loop's body as a regular vectorized addition/multiplication,
and reduce "Rv" to a scalar in loop's epilogue?

Why you didn't add SubReduction* nodes?

Best regards,
Filipp.


On Tue, Mar 17, 2015 at 12:40 AM, Berg, Michael C
<michael.c.berg at intel.com> wrote:
> Hi All,
>
>
>
> We would like to contribute the Integer/FP scalar reduction optimization
> from Intel.
>
> The contribution is referenced as Bug ID 8074981 as a performance
> enhancement.
>
>
>
> Please review this patch:
>
> Bug-id: https://bugs.openjdk.java.net/browse/JDK-8074981
>
> webrev: https://bugs.openjdk.java.net/secure/attachment/26101/webrev.zip
>
>
>
> The optimization achieves as much as 2.3x on integer reductions and supports
> float and double precision optimizations
>
> which also have significant optimization uplift an obey strict fp
> constraints.
>
>
>
> Nils Eliasson has offered to sponsor this patch.
>
>
>
> Thanks,
>
>
>
> -Michael
>
>