VSIB encoding errors with vector index registers 16-31

[petercaday]

Hi!
First, thanks for all the work making xbyak, it's a great library to work with. I noticed an encoding bug in AVX-512 gather/scatter instructions when the vector index register is in the high half, one of [x,y,z]mm16-31. For instance,
vgatherdps zmm0{k1}, [rax + ymm18]
would be encoded as
vgatherdps zmm0{k1}, [rax + ymm2].
The problem is that the EVEX.V' bit is not set properly in these situations (it is always 1). I have a patch that appears to fix the issue, but I'm not an expert in xbyak's internals, so it might not be the right approach.

Thanks,
Peter

[petercaday]

Patch attached.
vsib.patch.txt

[herumi]

Thank you for the important information. I'll fix it.

[herumi]

I fixed it. Thank you again.

[petercaday]

Thanks for the quick response, and thanks again for your work on xbyak!