register_offset_hack() vs REGISTER_BYTE()

[Andrew Cagney]

> Can probably change REGISTER_BYTE to a pre-initialized method with predicate (see DEPRECATED_PC_IN_CALL_DUMMY for an example), and then add a predicate test for it to the above mix.

On second thoughts, and having investigate things a bit further ... 
Doing it would revert any architecture [still] defining REGISTER_BYTE 
(almost all of them) back to using the legacy register cache. 
Consequently I'll instead just add sanity checks to ensure that the 
regcache and REGISTER_BYTE are consistent.

> Sentinel frame should probably also be switched to using register_offset_hack(), instead of REGISTER_BYTE(), so that it is more consistent with the frame code.

Appears to work.

> Sounds like it's time to s/ REGISTER_BYTE / DEPRECATED_REGISTER_BYTE /.  It isn't yet possible to eliminate that macro from the MIPS since it is that hardwired mystery that defines the MIPS remote protocol :-(

...

Andrew