[PATCH 2/8] Support APX GPR32 with extend evex prefix

[Cui, Lili]

> >> Similary I don't think I can spot anywhere that you would check the
> >> other bits which need to be zero in extended EVEX. Nor Improper use
> >> of EVEX.x4 in certain pre-existing encodings (S/G insns at least; perhaps all
> others are okay).
> >
> > Sorry, I can't get you here, what are S/G insns, could you provide more
> details here, thanks.
> 
> S/G is scatter/gather (i.e. AVX2 and AVX512).
> 
I think you mean EVEX.V4, scatter/gather has VSIB which needs to reuse this bit (EVEX.x4 is EVEX.p[10] which is fixed value 1),
For our current code we will reassign that bit and now I changed it to check the upper 16 registers of GPR32 , do you think it is ok?

@@ -4252,7 +4252,7 @@ build_apx_evex_prefix (void)
   if (i.rex2 & REX_R)
     i.vex.bytes[1] &= 0xef;
   if (i.vex.register_specifier
-      && register_number (i.vex.register_specifier) > 0xf)
+      && (i.vex.register_specifier->reg_flags & RegRex2))
     i.vex.bytes[3] &= 0xf7;
   if (i.rex2 & REX_B)
     i.vex.bytes[1] |= 0x08;

Thanks,
Lili