8:25:12no-defun-allowedAs I understand it, it would require passing :L 1 to EMIT-AVX2-INST which is currently not possible. And it couldn't be done implicitly, as REG-IDs don't distinguish between XMM and YMM registers (but they do for RAX, EAX, etc). I noticed some instructions already have size arguments; would it be appropriate to pass an optional size there? That is currently what my modified emitter does too.