RFR: 8173472: AArch64: C1 comparisons with null only use 32-bit instructions

[Roland Westrelin]

> Thanks for clarifying that. So can you also clarify why int is used for 
> Address even in 64-bit?

The use of T_ADDRESS is quite limited in c1. It's supposed to be for
anything that's nor a java object or a metadata pointer (but as Stuart
found out it's not that clean). So I suppose we never hit a constant
T_ADDRESS and we're just lucky.

Roland.