RE: [PATCH] Support APX NF

["Cui, Lili" <lili.cui@intel.com>]

> >> -----Original Message-----
> >> From: Jan Beulich <jbeulich@suse.com>
> >> Sent: Thursday, February 29, 2024 8:04 PM
> >> To: Cui, Lili <lili.cui@intel.com>
> >> Cc: Lu, Hongjiu <hongjiu.lu@intel.com>; binutils@sourceware.org
> >> Subject: Re: [PATCH] Support APX NF
> >>
> >> On 29.02.2024 13:00, Cui, Lili wrote:
> >>>> On 27.02.2024 10:01, Cui, Lili wrote:
> >>>>> @@ -8860,6 +8880,9 @@ match_template (char mnem_suffix)
> >>>>>  		  goto check_operands_345;
> >>>>>  		}
> >>>>>  	      else if (t->opcode_space != SPACE_BASE
> >>>>> +		       /* Map0 and map1 are promoted to MAP4 when NF is
> >>>> enabled.
> >>>>> +			*/
> >>>>> +		       && !t->opcode_modifier.nf
> >>>>>  		       && (t->opcode_space != SPACE_0F
> >>>>>  			   /* MOV to/from CR/DR/TR, as an exception, follow
> >>>>>  			      the base opcode space encoding model.  */
> >>>>
> >>>> I don't understand this: How does a template permitting NF matter here?
> >>>> I could see the immediately preceding "else if" become something
> >>>> along the lines of
> >>>>
> >>>> 	      else if (is_cpu (t, CpuAPX_F) && (i.operands == 3 ||
> >>>> i.has_nf))
> >>>>
> >>>> But I admit I didn't fully think this through. It's just that the
> >>>> change as is looks wrong to me.
> >>>>
> >>>
> >>> I was also dissatisfied with this place yesterday and then modified it to:
> >>>
> >>>               else if (t->opcode_space != SPACE_BASE
> >>>                        /* For EVEX-promoted instructions, opcode_space is
> >>>                           promoted to MAP4.  */
> >>>                        && (t->opcode_space != SPACE_EVEXMAP4
> >>>                            || t->mnem_off == MN_movbe)
> >>>                        && (t->opcode_space != SPACE_0F
> >>>                            /* MOV to/from CR/DR/TR, as an exception, follow
> >>>                               the base opcode space encoding model.  */
> >>>                            || (t->base_opcode | 7) != 0x27))
> >>>
> >>> For EVEX-promoted instructions, opcode_space is promoted to MAP4.
> >>> The
> >> old judgment no longer fit for EVEX promoted instructions. However,
> >> the logic of this place is still not good.
> >>
> >> So what about my suggestion?
> >
> > Your suggestion is better, but we need to replace i.has_nf with new
> judgment, i.has_nf cannot cover instructions like adc, the testcase will be
> added by another patch.
> >
> > +             else if (is_cpu (t, CpuAPX_F)
> > +                      && (i.operands == 3 || (t->opcode_space == SPACE_EVEXMAP4
> > +                                              && t->mnem_off !=
> > + MN_movbe)))
> 
> Ah yes, to cover the non-NF 2-operand forms. But then is the "i.operands ==
> 3"
> part actually still needed?
> 

It can be removed,  great suggestion, thanks!

Lili.