[Lightning] RFC: conditional move

[Paul Cercueil]

Hi,

I was thinking that we could have a conditional move operation, 
something like:

movs    01 = (04 != 0) ? 02 : 03
movc    01 = (04 == 0) ? 02 : 03

(of course 'movc' is just a 'movs' with inverted 02/03 operands, so 
there could be only one operation)

That would be easy to implement on MIPS with MOVZ/MOVN, ARM with 
TST/MOVS, AArch64 with TST/CSEL. The other platforms could resolve to 
emitting branches.

That's something that would be very useful to me.

Thoughts?

Thanks,
-Paul