[8u40] backport RFR (M) 8052081: Optimize generated by C2 code for Intel's Atom processor

[Vladimir Kozlov]

8u40 backport request.  Changes were pushed week ago into jdk9, no 
problems were found since then. Changes are applied to 8u without conflicts.

http://cr.openjdk.java.net/~kvn/8052081/webrev/
https://bugs.openjdk.java.net/browse/JDK-8052081
http://hg.openjdk.java.net/jdk9/hs-comp/hotspot/rev/76913ad3cd41

Thanks,
Vladimir