https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94589
--- Comment #12 from Marc Glisse <glisse at gcc dot gnu.org> --- (In reply to rguent...@suse.de from comment #11) > For PR99997 > I have prototyped a forwprop patch to try constant folding > stmts with all-constant PHIs, thus in this case c$_M_value_2 > 0, > when there's only a single use of it Maybe we could handle any case where trying to fold the single use (counting x*x as a single use of x) with each possible value satisfies is_gimple_val (or whatever the condition is to be allowed in a PHI, and without introducing a use of a ssa_name before it is defined), so that things like PHI<X,0> & X would simplify. But the constant case is indeed the most important, and should allow the optimization in this PR before the vectorizer using reassoc1.
