RFR: 8165661: SPECjvm2008-crypto.signverify regression in 9-b105

[Rahul Raghavan]

Hi,

Please review following patch for JDK- 8165661.
<webrev.00> :  http://cr.openjdk.java.net/~rraghavan/8165661/webrev.00/

1. <bug details> : https://bugs.openjdk.java.net/browse/JDK-8165661
Performance regression reported with Internal run benchmark harness (SPECjvm2008-crypto.signverify) for x86_64 with JDK9-b105 build onwards.

2. Found following change done as sub-part of old JDK-8145322 Enhancement is the root cause of the reported Performance regression - 
        [the (CastII (AddI x const)) -> (AddI (CastII x) const) transformation change block in CastIINode::Ideal() - castnode.cpp]

      (https://bugs.openjdk.java.net/browse/JDK-8145322 - Code generated from unsafe loops can be slightly improved)
      (http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/c8b709902e0e)
      (http://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2015-December/020381.html)

3. Understood there was no performance numbers with old 8145322 fix.
But now with proposed <webrev.00> change (reverting old sub part of 8145322),
  got no jprt functional failures, no other performance regressions and confirmed reported signverify regression is solved.

4. So to go forward as Roland W suggested, request for review and approval of this proposed <webrev.00> to close this 8165661.
Afterwards I will create a  new separate enhancement CR to investigate 
  why this reverted old 8145322 part caused issues and for a possible better version of the same.


Thanks,
Rahul