Re: [PATCH v6 55/61] target/riscv: integer extract instruction

[LIU Zhiwei]

On 2020/3/28 11:36, Richard Henderson wrote:
> On 3/17/20 8:06 AM, LIU Zhiwei wrote:
> > +/* Integer Extract Instruction */
> > +static void extract_element(TCGv dest, TCGv_ptr base,
> > +                            int ofs, int sew)
> > +{
> > +    switch (sew) {
> > +    case MO_8:
> > +        tcg_gen_ld8u_tl(dest, base, ofs);
> > +        break;
> > +    case MO_16:
> > +        tcg_gen_ld16u_tl(dest, base, ofs);
> > +        break;
> > +    default:
> > +        tcg_gen_ld32u_tl(dest, base, ofs);
> > +        break;
> > +#if TARGET_LONG_BITS == 64
> > +    case MO_64:
> > +        tcg_gen_ld_i64(dest, base, ofs);
> > +        break;
> > +#endif
> > +    }
> > +}
> I just remembered that this doesn't handle HOST_WORDS_BIGENDIAN properly -- the
> MO_64 case for TARGET_LONG_BITS == 32.
>
> Because we computed the offset for MO_64, not MO_32, we need
>
>      case MO_64:
>          if (TARGET_LONG_BITS == 64) {
>              tcg_gen_ld_i64(dest, base, ofs);
>              break;
>          }
> #ifdef HOST_WORDS_BIGENDIAN
>          ofs += 4;
> #endif
>          /* fall through */
>      case MO_32:
>          tcg_gen_ld32u_tl(dest, base, ofs);
>          break;
>      default:
>          g_assert_not_reached();
Yes, it should be.

As extract_element and gather_element are very similar . I
will merge them to  load_element in v7.

Zhiwei
> r~