https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110202
--- Comment #7 from Alexander Monakov <amonakov at gcc dot gnu.org> --- Note that vpxor serves as a dependency-breaking instruction (see PR 110438). So in negate1 we do the right thing for the wrong reasons, and in negate2 we can cause a substantial stall if the previous computation of xmm0 has a non-trivial dependency chain.
