RFR(m) 8164920: ppc: enhancement of CRC32 intrinsic

[Hiroshi H Horii]

Hi all,

Martin thankfully created a webrev with some good correction.
http://cr.openjdk.java.net/~mdoerr/8164920_ppc_crc32/webrev.01/

Could someone review this change again?

Regards,
Hiroshi
-----------------------
Hiroshi Horii, Ph.D.
IBM Research - Tokyo




From:   Hiroshi H Horii/Japan/IBM
To:     "Doerr, Martin" <martin.doerr at sap.com>
Cc:     Gustavo Bueno Romero <gromero at br.ibm.com>, 
"hotspot-compiler-dev at openjdk.java.net" 
<hotspot-compiler-dev at openjdk.java.net>, "Volker Simonis 
(volker.simonis at gmail.com)" <volker.simonis at gmail.com>
Date:   09/19/2016 02:36
Subject:        RE: RFR(m) 8164920: ppc: enhancement of CRC32 intrinsic


Hi Martin, and all
(Please allow me to send this mail twice. The first mail is awaiting 
because it exceeded 100KB)

Thank you for your reviewing. Gustavo and I recreated a new change based 
on your comments. I would like to request a review again.

My account of cr server is not available now (because of my mistake...) 
and Gustavo cannot create a webrev file with another reason. I would like 
to attach a diff file created with "hg diff -g" in hotspot.  If possible, 
could someone create a webrev file with this changeset?

[attachment "hotspot.crc32.20160918.changeset" deleted by Hiroshi H 
Horii/Japan/IBM] 

Regards,
Hiroshi
-----------------------
Hiroshi Horii, Ph.D.
IBM Research - Tokyo

"Doerr, Martin" <martin.doerr at sap.com> wrote on 09/13/2016 18:35:09:

> From: "Doerr, Martin" <martin.doerr at sap.com>
> To: Hiroshi H Horii/Japan/IBM at IBMJP, "hotspot-compiler-
> dev at openjdk.java.net" <hotspot-compiler-dev at openjdk.java.net>
> Cc: "Volker Simonis (volker.simonis at gmail.com)" 
> <volker.simonis at gmail.com>, Gustavo Bueno Romero <gromero at br.ibm.com>
> Date: 09/13/2016 18:36
> Subject: RE: RFR(m) 8164920: ppc: enhancement of CRC32 intrinsic
> 
> Hi Hiroshi,
> 
> we appreciate your change. Thanks for contributing it.
> It basically looks good, but I’d like to propose some minor 
improvements.
> 
> 
> kernel_crc32_1word_vpmsumd:
> 
> 1. The Pre-align code can be implemented shorter:
>     clrldi_(prealign, buf, 57);
>     beq(CCR0, L_alignHead);
> 
>     subfic(prealign, prealign, 128);
> 
> 2. I'd prefer the label name “L_alignedHead”.
> 
> 3. The branch b(L_alignTail) and the label are not needed and should
> get removed.
> 
> 
> kernel_crc32_1word_aligned:
> 
> 1. When saving and restoring non-volatile vector register, please 
> use offset differences of -16 instead of -32.
> (The ABI allows up to 288 bytes to be used in frameless functions so
> it will fit if -16 is used.)
> 
> 2. The std instructions should better be used with int offsets so 
> you can get rid of the addi(offset, offset, -8) instructions.
> 
> 
> Comments:
> For single line comments "//" should be used instead of "/*". Would 
> be nice if you could change them.
> 
> 
> Thanks and best regards,
> Martin
> 
> 
> From: Hiroshi H Horii [mailto:HORII at jp.ibm.com] 
> Sent: Dienstag, 6. September 2016 16:50
> To: hotspot-compiler-dev at openjdk.java.net; vladimir.kozlov at oracle.com
> Cc: Volker Simonis (volker.simonis at gmail.com) 
> <volker.simonis at gmail.com>; Doerr, Martin <martin.doerr at sap.com>; 
> Gustavo Bueno Romero <gromero at br.ibm.com>
> Subject: RFR(m) 8164920: ppc: enhancement of CRC32 intrinsic
> 
> Dear Vladimir and all:
> 
> Can I please request reviews for the following change?
> 
> JIRA: https://bugs.openjdk.java.net/browse/JDK-8164920
> webrev: http://cr.openjdk.java.net/~gromero/8164920/01/
> 
> As Volker's comments in the above JIRA, this is a ppc64-only 
> improvement which will not 
> affect any of the Oracle platforms in any way. 
> 
> This change includes new implementation of CRC32 Intrinsics for ppc64le.
> In my local experiment, CRC32 of 64KB was calculated more than 20 
> times faster than original. 
> Performance of CRC32 Intrinsic is important to run recent Apache 
Cassandra.
> A Cassandra daemon needs to read 64KB data from a disk with CRC32 
> checksum by default.
> 
> This JIRA entry has "jdk9-fc-request" label.
> If there is a chance to include new change in JDK 9 for ppc64le, I 
> would like to request 
> a review for this change.
> 
> Regards,
> Hiroshi
> -----------------------
> Hiroshi Horii, Ph.D.
> IBM Research - Tokyo



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