https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71762
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |law at gcc dot gnu.org --- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- The easiest "fix" might be to expand X < Y of 1-bit entities back to and-not... Or to remove these patterns from match.pd again, because if expansion needs to insert truncations for them to be valid that's never going to be a win. Jeff, you added those initially: 2013-06-19 Jeff Law <l...@redhat.com> * tree-ssa-forwprop.c (simplify_bitwise_binary_boolean): Fix typo in comment. * tree-ssa-forwprop.c (simplify_bitwise_binary_boolean): New function. (simplify_bitwise_binary): Use it to simpify certain binary ops on booleans. any preference? I'd rip them out and maybe teach the transform to combine/simplify-rtx which could check known-zero-bits to make sure the upper bits are not undefined.