[8u20] RFR: 8029302: Performance regression in Math.pow intrinsic

[Niclas Adlertz]

Hi all,

Please review the backport of 8029302 together with 8042052, where 
8042052 fixed an issue introduced by 8029302.

The changesets apply cleanly. I intend push 8029302 and 8042052 as 
separate changesets.

8029302: http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/6314
          http://cr.openjdk.java.net/~adlertz/JDK-8029302/webrev01/

8042052: http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/6385
          http://cr.openjdk.java.net/~anoll/8042052/webrev.01/

Kind Regards,
Niclas Adlertz