On Fri, Jun 26, 2015 at 09:42:06AM +0200, Uros Bizjak wrote: > Hello! > > > > > [ I see i386 also does PUT_CODE in a few more splitters, hrm. ] > > > > > > I think the splitters need to be fixed but I also think that > > > shallow_copy_rtx should > > > be enough, no? combine will not actually end up generating more > > > references > > > to the original RTX so we won't end up with invalid RTX sharing (the same > > > logic > > > is why the splitters didn't care). > > > > That probably is enough; I haven't thought about it too much, all other > > splitters doing a copy do a deep copy. I don't think it is worth being > > too tricky here, those splitters do not match often at all. > > > > > It would be cleaner to write the splitters in a way that doesnt copy the > > > RTX > > > but creates a new RTX with proper code/mode and operands (but that's more > > > work on your side - maybe Uros wants to help here). > > > > I think people use "copy_rtx; PUT_*" because it is less typing work ;-) > > If that is the only thing you change about the rtx, it even is easier > > to understand than creating a new one. > > Attached patch implements both suggestions. It uses shallow_copy_rtx > before all PUT_* calls in the splitters, to avoid nasty surprises like > this one in the future. shallow_ropy_rtx copies just one level of RTX, > and this is all what we need. Also, the patch changes existing uses of > copy_rtx to shallow_copy_rtx.
Thanks for doing the legwork Uros! Much appreciated. Andreas, s390 does a bit of this too (in vector.md). I cannot really test for that at all, can you take care of it? Segher
