Re: [PATCH v2 2/4] target/ppc: Move VSX vector with length storage access insns to decodetree.

[Richard Henderson]

On 6/17/24 04:51, Chinmay Rath wrote:
> Hi Richard,
> On 6/17/24 00:43, Richard Henderson wrote:
> > On 6/13/24 02:33, Chinmay Rath wrote:
> > > +/* EA <- (ra == 0) ? 0 : GPR[ra] */
> > > +static TCGv do_ea_calc_ra(DisasContext *ctx, int ra)
> > > +{
> > > +    TCGv EA;
> > > +    if (!ra) {
> > > +        EA = tcg_constant_tl(0);
> > > +        return EA;
> > > +    }
> > > +    EA = tcg_temp_new();
> > > +    if (NARROW_MODE(ctx)) {
> > > +        tcg_gen_ext32u_tl(EA, cpu_gpr[ra]);
> > > +    } else {
> > > +        tcg_gen_mov_tl(EA, cpu_gpr[ra]);
> >
> > Why are you making a copy, rather than just returning cpu_gpr[ra]?
> > If you need to modify the resulting EA, then you also need to make a copy for 0.
> Please ignore my previous response.
> I think do_ea_calc_ra should allow modification to the resulting EA, hence below change 
> appears more appropriate to me :
>
> /* EA <- (ra == 0) ? 0 : GPR[ra] */
> static TCGv do_ea_calc_ra(DisasContext *ctx, int ra)
> {
>      TCGv EA = tcg_temp_new();
>      if (!ra) {
>          tcg_gen_movi_tl(EA, 0);
>          return EA;
>      }
>      if (NARROW_MODE(ctx)) {
>          tcg_gen_ext32u_tl(EA, cpu_gpr[ra]);
>      } else {
>          tcg_gen_mov_tl(EA, cpu_gpr[ra]);
>      }
>      return EA;
> }

If that's what's needed by the callers of do_ea_calc_ra, then yes.
You can drop the first return EA and use else if instead.


r~