[PATCH] x86: add missing APX logic to cpu_flags_match()
Cui, Lili
lili.cui@intel.com
Mon Jan 8 08:30:49 GMT 2024
> >> --- 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.
More information about the Binutils
mailing list