Andrew Hutchinson <andrewhutchin...@cox.net> writes: > I can use "=" modifier to make operands use same register and early > clobber "&" to avoid overlaps. > > Is it possible to have or construct a contraint that permits partial > overlap operands. (which neither = or & would allow) > The case would be wide types taking multiple hard registers. > > eg Input r20..23 Output r22..25
There is no such constraint today. I suppose it would be possible to define such a constraint if it seemed useful. It would not be a simple change. A number of different parts of the compiler know about register constraints, and some of them would have to change in relatively substantial ways to track this. Ian
