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

[Vladimir Kozlov]

Note, that if we backport loop reduction vectorization, we backport only 8074981 changes as they are:

http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/6fff5df5f3d2

There will be no support for MulVL in it which requires avx512.

Regards,
Vladimir

On 4/7/15 12:12 PM, Vitaly Davidovich wrote:
> Oh, the motivation is there! :) However, it's not always a quick process even if everyone's motivated as there may be
> changes of consequence.  As a small example, java 8 virtual memory charge is significantly higher than java 7 due to
> metaspace vs permgen differences.  In some cases, this now requires tweaking java 8 settings in order to keep things
> running smoothly.  With a big enough codebase, such migrations are never as quick as one would hope.
>
> At any rate, yes, I meant loop reduction vectorization.  It seems like a fairly self-contained change which should be
> relatively painless to backport, hence my inquiry.
>
> On Tue, Apr 7, 2015 at 3:04 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com <mailto:vladimir.kozlov at oracle.com>> wrote:
>
>     We want to motivate people to migrate to new releases :)
>     If you mean loop reduction vectorization we can consider it after it is tested for some time in jdk9.
>
>     Vladimir
>
>     On 4/7/15 11:55 AM, Vitaly Davidovich wrote:
>
>         Ok, thanks.  That makes sense for avx512 support, but I think having Michael's changes from this thread sooner
>         would be
>         nice as it's quite likely that users are already running java 8 on hardware where this may have benefit.  Java 9 is
>         still ways away, and even when it's released, the migration process is not always quick (depending on the nature of
>         major changes).  But, if backporting it is messy, it's probably not worth it.
>
>         On Tue, Apr 7, 2015 at 2:38 PM, Vladimir Kozlov <vladimir.kozlov at oracle.com <mailto:vladimir.kozlov at oracle.com>
>         <mailto:vladimir.kozlov at __oracle.com <mailto:vladimir.kozlov at oracle.com>>> wrote:
>
>              Currently it is only jdk9. There are no plans to backport to 8u.
>              The thinking is that we will get jdk9 released when this hardware will be widely available.
>
>              Regards,
>              Vladimir
>
>              On 4/7/15 11:30 AM, Vitaly Davidovich wrote:
>
>                  Hi Michael/Vladimir,
>
>                  Out of curiosity, is this change and the out-for-review avx512 one going to be (or planned on being)
>         backported
>                  to java 8?
>
>                  Thanks
>
>                  On Tue, Apr 7, 2015 at 2:07 PM, Berg, Michael C <michael.c.berg at intel.com
>         <mailto:michael.c.berg at intel.com> <mailto:michael.c.berg at intel.__com <mailto:michael.c.berg at intel.com>>
>                  <mailto:michael.c.berg at intel. <mailto:michael.c.berg at intel.>____com <mailto:michael.c.berg at intel.__com
>         <mailto:michael.c.berg at intel.com>>>> wrote:
>
>                       Please ignore this one its already checked in…____
>
>                       __ __
>
>                       *From:* hotspot-compiler-dev [mailto:hotspot-compiler-dev-____bounces at openjdk.java.net
>         <mailto:hotspot-compiler-dev-__bounces at openjdk.java.net>
>                  <mailto:hotspot-compiler-dev-__bounces at openjdk.java.net
>         <mailto:hotspot-compiler-dev-bounces at openjdk.java.net>>
>                       <mailto:hotspot-compiler-dev-____bounces at openjdk.java.net
>         <mailto:hotspot-compiler-dev-__bounces at openjdk.java.net>
>                  <mailto:hotspot-compiler-dev-__bounces at openjdk.java.net
>         <mailto:hotspot-compiler-dev-bounces at openjdk.java.net>>>] *On Behalf Of *Berg, Michael C
>                       *Sent:* Monday, March 16, 2015 2:18 PM
>                       *To:* hotspot-compiler-dev at openjdk.____java.net <http://java.net>
>         <mailto:hotspot-compiler-dev at __openjdk.java.net <mailto:hotspot-compiler-dev at openjdk.java.net>>
>                  <mailto:hotspot-compiler-dev@ <mailto:hotspot-compiler-dev@>____openjdk.java.net
>         <http://openjdk.java.net> <mailto:hotspot-compiler-dev at __openjdk.java.net
>         <mailto:hotspot-compiler-dev at openjdk.java.net>>>
>                       *Subject:* RFR(L): 8074981 (Integer/FP scalar reduction optimization )____
>
>                       __ __
>
>                       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
>         <https://bugs.openjdk.java.net/__browse/JDK-8074981>
>                  <https://bugs.openjdk.java.__net/browse/JDK-8074981 <https://bugs.openjdk.java.net/browse/JDK-8074981>>
>         ____
>
>                       webrev: https://bugs.openjdk.java.net/____secure/attachment/26101/____webrev.zip
>         <https://bugs.openjdk.java.net/__secure/attachment/26101/__webrev.zip>
>                  <https://bugs.openjdk.java.__net/secure/attachment/26101/__webrev.zip
>         <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____
>
>                       __ __
>
>
>
>