https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85891
--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> --- The log file shows the loop was already vectorized by loop vectorization. How did you configure gcc? It might be you configured a default -march/tune that doesn't match the testcase expectation (and the testcase could probably use -ftree-slp-vectorize instead of -ftree-vectorize).
