[PATCH 2/5] x86: re-order optimize_disp()

[H.J. Lu]

On Thu, Apr 22, 2021 at 1:39 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> While I can't point out any specific case where things break, it looks
> wrong to have the consumer of a flag before its producer. Set .disp32
> first, then do the possible conversion to signed 32-bit, and finally
> check whether the value fits in a signed long.
>
> gas/
> 2021-04-XX  Jan Beulich  <jbeulich@suse.com>
>
>         * config/tc-i386.c (optimize_disp): Move down BFD64 section.
>         Move up setting of disp32.
>
> --- a/gas/config/tc-i386.c
> +++ b/gas/config/tc-i386.c
> @@ -5707,19 +5707,6 @@ optimize_disp (void)
>                 op_disp = (((op_disp & 0xffff) ^ 0x8000) - 0x8000);
>                 i.types[op].bitfield.disp64 = 0;
>               }
> -#ifdef BFD64
> -           /* Optimize 64-bit displacement to 32-bit for 64-bit BFD.  */
> -           if (i.types[op].bitfield.disp32
> -               && (op_disp & ~(((offsetT) 2 << 31) - 1)) == 0)
> -             {
> -               /* If this operand is at most 32 bits, convert
> -                  to a signed 32 bit number and don't use 64bit
> -                  displacement.  */
> -               op_disp &= (((offsetT) 2 << 31) - 1);
> -               op_disp = (op_disp ^ ((offsetT) 1 << 31)) - ((addressT) 1 << 31);
> -               i.types[op].bitfield.disp64 = 0;
> -             }
> -#endif
>             if (!op_disp && i.types[op].bitfield.baseindex)
>               {
>                 i.types[op].bitfield.disp8 = 0;
> @@ -5730,17 +5717,32 @@ optimize_disp (void)
>                 i.op[op].disps = 0;
>                 i.disp_operands--;
>               }
> +#ifdef BFD64
>             else if (flag_code == CODE_64BIT)
>               {
> +               if (i.prefix[ADDR_PREFIX]
> +                   && fits_in_unsigned_long (op_disp))
> +                 i.types[op].bitfield.disp32 = 1;
> +
> +               /* Optimize 64-bit displacement to 32-bit for 64-bit BFD.  */
> +               if (i.types[op].bitfield.disp32
> +                   && (op_disp & ~(((offsetT) 2 << 31) - 1)) == 0)
> +                 {
> +                   /* If this operand is at most 32 bits, convert
> +                      to a signed 32 bit number and don't use 64bit
> +                      displacement.  */
> +                   op_disp &= (((offsetT) 2 << 31) - 1);
> +                   op_disp = (op_disp ^ ((offsetT) 1 << 31)) - ((addressT) 1 << 31);
> +                   i.types[op].bitfield.disp64 = 0;
> +                 }
> +
>                 if (fits_in_signed_long (op_disp))
>                   {
>                     i.types[op].bitfield.disp64 = 0;
>                     i.types[op].bitfield.disp32s = 1;
>                   }
> -               if (i.prefix[ADDR_PREFIX]
> -                   && fits_in_unsigned_long (op_disp))
> -                 i.types[op].bitfield.disp32 = 1;
>               }
> +#endif
>             if ((i.types[op].bitfield.disp32
>                  || i.types[op].bitfield.disp32s
>                  || i.types[op].bitfield.disp16)
>

OK.

Thanks.

-- 
H.J.