https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70359
--- Comment #28 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- (In reply to Richard Biener from comment #25) > What usually makes things complicated in the end is when for an IV > we get overlapping life-ranges for the before and after value because > that inhibits coalescing. Is this what happens here? ... ... > So we indeed have p_20 and p_9 live as p_9 is used after the loop. > Originally > this wasn't the case but fold_stmt in the first forwprop pass does this > by means of following use-def chains. I'm a bit confused. Where are you looking, after the forprop1 pass? Because after forwprop1 I see: <bb 5> : p_22 = p_8 + 4294967294; MEM[(char *)p_19 + 4294967295B] = 45; <bb 6> : # p_9 = PHI <p_19(4), p_22(5)> return p_9; Which as I understand has: p_8 being the IV at the beginning of the last iteration. p_19 being the IV at the end of the last iteration. p_22 being the IV at the end of the last iteration MINUS 1. I don't see a p_20 anywhere. Did you mean that p_8 and p_19 where both live at the end of the loop? Thanks for all the feedback BTW.
