[LLVMdev] [ptx] Propose a register class naming convention change

[Che-Liang Chiou]

Hi,

Current register class naming has a confusing prefix letter 'R' (it is
my bad), such as the first 'R' of RRegu32 (for unsigned 32-bit
registers).

I propose a 'Reg' + type name naming convention for register classes; such as:
  Regu16, Regu32, Regf32, Regf64
With one exception for predicate registers (capitalized first letter of 'pred'):
  RegPred

Since predicate registers are special in the way that they can't be
passed as arguments or load from/store to memory, I think a little
name convention exception for it is okay.

What do you think?

If no objection, I will start making the change.

Regards,
Che-Liang