hope this hasn't been asked before, but I couldn't find a way to search the forum..?
In high performance code I'm using MMX and SSE together, since this gives me 8 additional very valuable registers. Looking at the AVX docs, this seems no longer possible with AVX code, since all MMX-related SSE instructions have not been promoted with a VEX prefix, and are therefore legacy instructions which I may no longer use (or face the deadly mixing penalty that requires VZEROUPPER etc.).
Is is correct that it's no longer possible to make heavy use of MMX registers in AVX code?
Can I at least continue using MMX registers without performance impact as long as there is no data transfer between MMX and SSE registers?