On Thu, Oct 22, 2015 at 9:59 AM, Jakub Jelinek <ja...@redhat.com> wrote: > On Thu, Oct 22, 2015 at 09:49:29AM +0200, Richard Biener wrote: >> >> Jakub, IYR I originally had IFN_FORK and IFN_JOIN as such distinct >> >> internal >> >> fns. This replaces that scheme. >> >> >> >> ok? >> > >> > Hmm, I'd just have used gimple_has_volatile_ops on the call? That >> > should have the >> > desired effects. >> >> That is, whatever new IFNs you need are ok, but special-casing them is not >> necessary if you properly mark the calls as volatile. > > I don't see gimple_has_volatile_ops used in tracer.c or > tree-ssa-threadedge.c. Setting gimple_has_volatile_ops on those IFNs is > fine, but I think they are even stronger than that.
Hmm, indeed. Now I fail to see how the implemented property "preserves the CFG looping structure". And I would have expected can_copy_bbs_p to be adjusted instead (catching more cases and the threading and tracer case as well). As far as I can see nothing would prevent dissolving the loop by completely unolling it for example. Or deleting it because it has no side-effects. So you'd need to be more precise as to what properties you are trying to preserve by placing a single stmt somewhere. Richard. > Jakub
