https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68027
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2015-10-20 Component|middle-end |tree-optimization Version|unknown |5.2.0 Ever confirmed|0 |1 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- Confirmed. It's VRP doing this constant propagation and uncprop not undoing it. When we do not need to spill 'a' then re-using 'a' would be better but the optimization is supposed to catch the more frequent case where we'd have to spill 'a'.