https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87561
--- Comment #9 from Michael Matz <matz at gcc dot gnu.org> --- (In reply to Richard Biener from comment #8) > > I'm out of ideas suitable for GCC 9 (besides reverting the patch, reverting > to bogus state). Either that or some hack (e.g. artificially avoiding vectorization if runtime checks are necessary and the loop-nest isn't a box but a pyramid). Whatever we do it's better to release GCC with internal bogus state than to release GCC with a known 10% performance regression (you could revert only on the release branch so that the regression stays in trunk).