https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102517
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- FAIL: gcc:gcc.dg/dg.exp=gcc.dg/pr78408-1.c scan-tree-dump-times fab1 "after previous" 17 here we perform the desired optimization earlier in FRE. I'll adjust the testcase to make 'S' size not power of two.
