> "Pengxuan Zheng (QUIC)" <quic_pzh...@quicinc.com> writes:
> >> On Thu, Sep 12, 2024 at 2:53 AM Pengxuan Zheng
> >> <quic_pzh...@quicinc.com> wrote:
> >> >
> >> > SVE's INDEX instruction can be used to populate vectors by values
> >> > starting from "base" and incremented by "step" for each subsequent
> >> > value. We can take advantage of it to generate vector constants if
> >> > TARGET_SVE is available and the base and step values are within [-16,
> 15].
> >>
> >> Are there multiplication by or addition of scalar immediate
> >> instructions to enhance this with two-instruction sequences?
> >
> > No, Richard, I can't think of any equivalent two-instruction sequences.
>
> There are some. E.g.:
>
> { 16, 17, 18, 19, ... }
>
> could be:
>
> index z0.b, #0, #1
> add z0.b, z0.b, #16
>
> or, alternatively:
>
> mov w0, #16
> index z0.b, w0, #1
>
> But these cases are less obviously a win, so I think it's ok to handle single
> instructions only for now.
>
> The patch is ok for trunk, thanks, but:
>
> >> > @@ -22991,7 +22991,7 @@ aarch64_simd_valid_immediate (rtx op,
> >> simd_immediate_info *info,
> >> > if (CONST_VECTOR_P (op)
> >> > && CONST_VECTOR_DUPLICATE_P (op))
> >> > n_elts = CONST_VECTOR_NPATTERNS (op);
> >> > - else if ((vec_flags & VEC_SVE_DATA)
> >> > + else if (which == AARCH64_CHECK_MOV && TARGET_SVE
> >> > && const_vec_series_p (op, &base, &step))
>
> ...the convention is to have one && condition per line if the whole expression
> doesn't fit on a single line:
>
> else if (which == AARCH64_CHECK_MOV
> && TARGET_SVE
> && const_vec_series_p (op, &base, &step))
>
Thanks for pointing this out, Richard! I've fixed this and pushed the patch as
r15-3669-ga92f54f580c377.
Thanks,
Pengxuan
> Richard
