Gunther Piez <gupiez@xxxxxxxxxxxxxx> writes: > is there a way to tell gcc to not emit the `vzeroupper` instruction > while using -march=corei7avx? I do realize that this instruction is > neccessary if legacy 128 bit SSE instructions are intermixed with AVX > 128/256 bit code, like calling a libc function which makes use of SSE in > a non-AVX glibc or the other way around. > > But in a pure AVX code environment I noticed it actually does hurt > performance. So how can I tell gcc to not emit vzeroupper while > generating AVX instructions? Try -mno-vzeroupper. Ian
