8211908: PPC64: Enable SuperWordLoopUnrollAnalysis by default

[Lindenmaier, Goetz]

Hi Michihiro, 

the change looks good. 

We ran all our tests of jdk11u with the change, they are quite comprehensive.
This greatly reduces the chance of hidden error like spilling of vector registers 
etc.

Best regards,
  Goetz.

> -----Original Message-----
> 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