x86 ISA v3 / v4 coverage

[Jan Beulich]

H.J.,

the other day I came to notice two apparent anomalies:

Shouldn't XOP and FMA4 be excluded from v3, just like LWP and TBM are?

Shouldn't AVX512_4FMAPS be excluded from v4, just like AVX512_4VNNIW is?

And is it correct for new ISA additions (like not so long ago AVX512-FP16)
to become part of what is covered by v3 or v4? AMX, for example, was
excluded from v3 when it was added to the code base. And e.g. GFNI is not
part of v2 because there no "umbrella property" (VEX for v3, EVEX for v4)
is checked, but it's strictly a white-listing of Cpu* flags.

I'm afraid all of this once again is unobvious because the specification
is not clear enough.

Jan