https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114767
--- Comment #6 from mjr19 at cam dot ac.uk --- I was starting to wonder whether this issue might be related to that in bug 114324, which is a slightly more complicated example in which multiplication by a purely imaginary number destroys vectorisation. In 114324 the problem seems to arise from a refusal to alternate no-ops and negs along a vector, which is pretty much the issue here too.
