[PATCH 1/2] [PATCH 1/2] Enable Intel AVX512_FP16 instructions

[H.J. Lu]

On Sun, Jul 4, 2021 at 11:30 PM Jan Beulich <jbeulich@suse.com> wrote:
>
> On 01.07.2021 09:47, Cui,Lili wrote:
> >  opcodes/i386-opc.tbl           | 376 +++++++++++++++++++++
>
> A few more observations:
>
> While personally I think what you have is the best way of encoding
> it (allowing 64-bit register use to control EVEX.W in 64-bit bit
> mode), VMOVW is neither consistent with VPEXTRW (using EvexWIG) nor
> with VMOVD (only permitting Reg32). H.J., what are your thoughts
> here?

VMOVD is different.  PEXTRW takes Reg64 for historical reasons.
Lili, please remove Reg64 and add VexWIG on VMOVW.

> The VMOVW template needs splitting afaict: By OR-ing Word with
> Reg32 and/or Reg64, you effectively also permit Reg16, and I guess

Reg16 shouldn't be allowed.

> in Intel syntax VMOVW memory operands using "dword ptr" or
> "qword ptr". You'll notice that e.g. {,V}PEXTRW and {,V}PINSRW
> have separate register and memory operand templates, which is for
> this reason, iirc. (You may recall my other remark regarding
> combining e.g. Reg32 and Dword - there it is merely redundant, but
> having such is liable to suggest to people that combinations like
> Reg32 and Word are also okay. I intend to have i386-gen warn about
> such down the road, but obviously only once all present redundancies
> have been eliminated.)
>
> VCVT{,T}SH2{,U}SI should have EvexWIG for their non-64bit encodings.
> But really it's unclear why each of them has three templates when
> the corresponding pre-existing SD and SS insns get away with two. I
> would have expected new templates to have been cloned from similar
> existing ones, rather than introducing new ones (with new
> inconsistencies). Of course there's (again) the possibility that
> you've spotted a bug with pre-existing templates, but then - if you
> don't want to fix those right away - I'd expect you to at least
> point out why you deviate from what we've got.
>
> I suppose VCMP{P,S}H should have a large set of pseudos just like
> VCMP{P,S}{S,D} do, even if (for now) the spec doesn't spell those
> out.
>
> Jan
>


-- 
H.J.