On Thu, Aug 13, 2026 at 08:40:38AM +0200, Richard Biener wrote: > Hmm, there's no reason to not perform analysis on SSA names marked > as abnormal. You'd not get any useful control expression for the > edges, but the copy part holds. What you have to be careful with > is not disrupting coalescing during transforms because where > SSA names on abnormal edges (thus in PHI args) are special is that > you cannot insert a copy there, so we have to allocate the incoming > value and the PHI result to the same register. > > So I wonder why gimple_range_ssa_p cares about abnormals at all. > > What can be problematic is duplicating a PHI where the copy > inherits an abnormal incoming edge - extra copies of abnormally > marked SSA names are to be avoided. > > So I wonder if you can split this up and remove the abnormal > restriction from range analysis (and see what breaks - I'm curious).
Surprisingly (for me anyhow), nothing. Also, the consumers of this info (substitute_and_fold and tree-vrp.cc) seem to already have guards for abnormal PHIs. Could these restrictions be an inherited restriction from when we had ASSERT_EXPR copies to represent ranges? Your suggestion reduces my two patches to one line a piece :). I'll post as a follow-up. Thanks. Aldy
