FEX tests may generate unwanted instruction form
I am not 100% sure if I am right here, so apologies if I am not.
I was looking at test `OpSize/66_D6.asm` which has the instruction:
`movq xmm0, xmm2`
This on NASM generates the (probably unintended) form:
`movq xmm0, xmm2  ; +0 = f3 0f 7e c2` (https://godbolt.org/z/ebWchEcbb)
While I assume the one that the test focuses on testing is the form:
`movq xmm0, xmm2  ; +0 = 66 0f d6 d0`

I assume this doesn't cause any real problems, but I thought you might want to know that the test doesn't test the reg/reg form of the D6 opcode (if I am right).

This may or may not also happen on other tests that have both a xmm/xmm128 and a xmm128/xmm form where NASM compiles them to the unintended form.