On Mon, Dec 08, 2014 at 09:01:39AM -0600, Segher Boessenkool wrote: > > Why are you removing the alternative instead of clobbering XER[CA]? > > I should have mentioned, sorry. > > We don't want to clobber CA on *every* add, and reload can generate more > adds out of thin air. And CA is a fixed register. > > There may be a better way to do this, but I don't know it.
Some numbers... I checked how often the compiler used to allocate GPR0 here. I looked at cc1 of 4.7.2, 12MB text size. It happened zero times (it already was "?r" to discourage the RA / reload from using that alternative). There are 143962 addi insns in there. Segher
