http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51078
--- Comment #19 from Paolo Carlini <paolo.carlini at oracle dot com> 2011-11-12 12:34:51 UTC --- All in all - again, without having analyzed in any detail the optimization passes - I come to the conclusion that -funroll-loops is doing its job pretty well, and also that manually unrolling the loop make its life quite a bit harder.