On Wed, 2014-09-10 at 14:29 -0500, Segher Boessenkool wrote: > Huh, interesting. I assumed 1-(0_or_1) and (0_or_1)^1 would look the > same to combine, but no. > > With subfic, combine optimises it all to a branch on cr0. With xori, > for some reason combine has a much easier job, and it optimises the lot > to a copy of cr0 to some cc, and then branch on that. The RA of course > gets rid of the copy. The extra freedom will more likely help than hurt. > > The simple testcase ends up as just "tbegin. 0; beqlr 0" in either case. > > So, okay?
No objections from me then. Peter
