https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123414
--- Comment #4 from Robin Dapp <rdapp at gcc dot gnu.org> --- Somewhere in the vicinity of vcompress the problem surely is. The vcompresses are part of a reduction by vector right shifts. For those to work we must preserve the neutral element 1 even in the elements that are not part of the multiplication before (we have a VL of 5 and a VLEN of 256...). We don't, however, but have zeros instead. As the reduction operates on full vectors those zeros just zero out our multiplication, returning the value 0 eventually. Need to dig a bit deeper still, though.
