RE: [PATCH] x86: add missing APX logic to cpu_flags_match()

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

> >> --- a/gas/config/tc-i386.c
> >> +++ b/gas/config/tc-i386.c
> >> @@ -1940,6 +1940,30 @@ cpu_flags_match (const insn_template *t)
> >>  	      any.bitfield.cpuavx512vl = 0;
> >>  	    }
> >>  	}
> >> +
> >> +      /* Dual non-APX/APX templates need massaging from what APX_F() in
> the
> >> +         opcode table has produced.  While the direct transformation of the
> >> +         incoming cpuid&(cpuid|APX_F) would be to cpuid&(cpuid) /
> >> cpuid&(APX_F)
> >> +         respectively, it's cheaper to move to just cpuid / cpuid&APX_F
> >> +         instead.  */
> >> +      if (any.bitfield.cpuapx_f
> >> +	  && (any.bitfield.cpubmi || any.bitfield.cpubmi2
> >> +	      || any.bitfield.cpuavx512f || any.bitfield.cpuavx512bw
> >> +	      || any.bitfield.cpuavx512dq || any.bitfield.cpuamx_tile
> >> +	      || any.bitfield.cpucmpccxadd))
> >> +	{
> >> +	  /* These checks (verifying that APX_F() was properly used in the
> >> +	     opcode table entry) make sure there's no need for an "else" to
> >> +	     the "if()" below.  */
> >> +	  gas_assert (!cpu_flags_all_zero (&all));
> >> +	  cpu = cpu_flags_and (all, any);
> >> +	  gas_assert (cpu_flags_equal (&cpu, &all));
> >> +
> >> +	  if (need_evex_encoding (t))
> >> +	    all = any;
> >> +
> >
> >> +	  memset (&any, 0, sizeof (any));
> >
> > Wouldn't it make sense to put it in the else branch and clean out APX-F
> specifically? Just like you did before.
> >
> >   if (need_evex_encoding (t))
> >     all = any;
> > else
> >    any.bitfield.cpuapx_f = 0;
> 
> That was an alternative I did consider, yes, but the way I've done it is overall
> more self-consistent imo, at the expense of being less consistent with the
> AVX/AVX512 logic (the moving of "any" to "all" isn't consistent with that
> anyway).
> 

  memset (&any, 0, sizeof (any)); 

I'd say this would make "any" not match the actual value, which might be used later, but it's been cleared here.

Lili.