RFR(M): 8154826: AArch64: take better advantage of base + shifted offset addressing mode

[Roland Westrelin]

Thanks for the review.

Here is a change that should import cleanly:

http://cr.openjdk.java.net/~roland/8154826/8154826.patch

> Yes, looks good. Closed changes will be simple now :)
>
> Roland, are you on hotspot-compiler-dev at openjdk.java.net list? Or I should CC to you for reviews?

No CC needed. I'm on hotspot-compiler-dev at openjdk.java.net.

Roland.