On Mon, 13 Apr 2009, Dave Korn wrote: > Michael Meissner wrote: > > On Sat, Apr 11, 2009 at 01:40:57AM +0100, Dave Korn wrote: > >> Stelian Pop wrote: > >> > >>>>> Do I need to define movsi3(), addsi3() etc. patterns manually or > >>>>> should GCC figure those by itself ? ... > > Though if you use expanders that need temporary registers, you may have > > problems in reload, and need to delve into the mysteries of secondary > > reload. I would imagine that for pointer sized things it is best if you do > > need to implement multiple instructions that you hold off on splitting > > until after reload is completed. > > Yes, you're right about the register vs reload issue; you must condition any > calls to force_reg on !reload in progress / completed. But I don't think this > is such a problem; reload will only generate movMM instructions based on hard > regs, so you'll only run into secondary reloads if you have complex addressing > modes that need a scratch register to address, won't you?
How about asking the documentation? This isn't the first time for this question. A STFW found me <http://gcc.gnu.org/ml/gcc-patches/2000-04/msg00105.html> for context. Bah. I guess, it doesn't help having it documented... Or maybe you mean "do we *still* need this, given recent register-allocation changes"? (I'm not interested enough though.) brgds, H-P
