8211908: PPC64: Enable SuperWordLoopUnrollAnalysis by default

[Michihiro Horie]

Hi Martin,

> looks good. Thanks for doing some performance measurements.
>
> The change itself could be considered as trivial, but the impact may be
significant, so I’d appreciate a 2nd review.
>
> We already tested this flag in our nightly tests for a few weeks and
didn’t see any issues. It’s also enabled on other platforms which use
vector instructions so I think we should use it on PPC, too.
Thank a lot for your review!


Best regards,
--
Michihiro,
IBM Research - Tokyo



From:	"Doerr, Martin" <martin.doerr at sap.com>
To:	Michihiro Horie <HORIE at jp.ibm.com>, hotspot compiler
            <hotspot-compiler-dev at openjdk.java.net>,
            "ppc-aix-port-dev at openjdk.java.net"
            <ppc-aix-port-dev at openjdk.java.net>
Cc:	"Lindenmaier, Goetz" <goetz.lindenmaier at sap.com>, Gustavo
            Romero <gromero at linux.vnet.ibm.com>
Date:	2018/10/09 22:31
Subject:	RE: 8211908: PPC64: Enable SuperWordLoopUnrollAnalysis by
            default



Hi Michihiro,

looks good. Thanks for doing some performance measurements.

The change itself could be considered as trivial, but the impact may be
significant, so I’d appreciate a 2nd review.

We already tested this flag in our nightly tests for a few weeks and didn’t
see any issues. It’s also enabled on other platforms which use vector
instructions so I think we should use it on PPC, too.

Best regards,
Martin


From: Michihiro Horie <HORIE at jp.ibm.com>
Sent: Dienstag, 9. Oktober 2018 09:11
To: hotspot compiler <hotspot-compiler-dev at openjdk.java.net>;
ppc-aix-port-dev at openjdk.java.net
Cc: Doerr, Martin <martin.doerr at sap.com>; Lindenmaier, Goetz
<goetz.lindenmaier at sap.com>; Gustavo Romero <gromero at linux.vnet.ibm.com>
Subject: RFR: 8211908: PPC64: Enable SuperWordLoopUnrollAnalysis by default



Dear all,

Would you please review this simple change?
Bug: https://bugs.openjdk.java.net/browse/JDK-8211908
Webrev: http://cr.openjdk.java.net/~mhorie/8211908/webrev.00

Since PPC64 supports SLP with VSX, we can have the benefit from enabled
SuperWordLoopUnrollAnalysis on PPC64.

In the attached micro benchmarks, performance improved by 1.7x at maximum.
In SPECjvm2008, the score improved by a couple of % in xml.validation and
scimark.lu.large

(See attached file: microbench_slp.tar.gz)

Best regards,
--
Michihiro,
IBM Research - Tokyo





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