Re: [PATCH v3 3/3] target/arm: Use clear_vec_high more effectively

[Philippe Mathieu-Daudé]

On Tue, May 5, 2020 at 4:22 PM Richard Henderson
<address@hidden> wrote:
>
> On 5/4/20 11:09 PM, Philippe Mathieu-Daudé wrote:
> >> @@ -7111,7 +7121,7 @@ static void disas_simd_zip_trn
> >>       }
> >>         tcg_resl = tcg_const_i64(0);
> >> -    tcg_resh = tcg_const_i64(0);
> >> +    tcg_resh = is_q ? tcg_const_i64(0) : NULL;
> >>       tcg_res = tcg_temp_new_i64();
> >>         for (i = 0; i < elements; i++) {
> >> @@ -7162,9 +7172,12 @@ static void disas_simd_zip_trn(DisasContext *s,
> >> uint32_t insn)
> >
> > More context:
> >
> >            ...
> >            ofs = i * esize;
> >            if (ofs < 64) {
> >                tcg_gen_shli_i64(tcg_res, tcg_res, ofs);
> >                tcg_gen_or_i64(tcg_resl, tcg_resl, tcg_res);
> >            } else {
> >                tcg_gen_shli_i64(tcg_res, tcg_res, ofs - 64);
> >                tcg_gen_or_i64(tcg_resh, tcg_resh, tcg_res);
> >
> >                          here ^^^^^^^^ tcg_resh is NULL too.
> >
> >            }
> >        }
>
> When is_q is false, the vector length is 64.  Thus that line is not reachable.

OK.

>
>
> r~