https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80548
--- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> --- (In reply to Aldy Hernandez from comment #4) > Created attachment 51908 [details] > untested patch > > Like this. It fixes the problem at least for -O2. For -O1 y'all are on your own because there are no threaders smart enough to pick up the pattern. We'd need a threader at -O1 that runs after loop_done to pick it up: $ ./cc1 a.c -O1 -Wall -fenable-tree-threadfull2 -quiet cc1: note: enable pass tree-threadfull2 for functions in the range of [0, 4294967295] $ Voila, no warning. DOM3 runs after loop_done, so that would be candidate to handle this since it threads at -O1. However, this won't happen in this release. It would require a converting DOM threading to a hybrid approach (and see if the custom copier can handle cross-loop threading), or convert it entirely to the backward threader (would require ranger handling floats).
