On Fri, Apr 26, 2019 at 07:51:05PM +0200, Richard Biener wrote: > On April 26, 2019 6:59:43 PM GMT+02:00, Segher Boessenkool > <seg...@kernel.crashing.org> wrote: > >So, make it a doloop in gimple, and still have the rtl pass, but that > >only reverts it to a non-doloop if it turns out it has to. Does that > >sound like a good plan? > > Yes, that's more or less what I had in mind. Note that you'd have a doloop > early in RTL, sth we might not expect?
I don't think there are any fundamental reasons to not have that. Maybe some adjustments are needed, sure. > Maybe we already have a GIMPLE way of saying decrement and test zero (one of > the overflow builtins?), if not we'd need to add such to have > > Flag_1 = IFN_decandtest (i_2); > If (Flag_1! = 0) > ... > > As 'doloop-end' on GIMPLE. Just adjusting RTL expansion to catch a regular > Dec and test would be possible > As well of course. I don't know if we should have any special instructions in GIMPLE for this. Maybe it is enough to just mark up the loop? It would be a lot simpler, if it *works* that is :-) Segher
