> I'd say the problem space is indeed kind of regular still. If there's an > acceptable way of encoding these constraints without going "full dynamic", > that might be preferable. On the other hand, if used sparingly, maybe > dependent constraints won't be too bad?
Oh, I forgot to say that it _is_ possible to implement at least the destination/source part of the problem with register filters and we even tried that before. The patterns get increasingly unwieldy, though, with a mix of earlyclobbers, disabled attributes, and duplicate constraints. I don't recall all details but it worked reasonably well. At least for understanding/comprehension of an insn pattern, a dependent filter is much clearer, though. -- Regards Robin
