Richard Biener <rguent...@suse.de> writes:
> The following avoids re-analyzing the loop as epilogue when not
> using partial vectors and the mode is the same as the autodetected
> vector mode and that has a too high VF for a non-predicated loop.
> This situation occurs almost always on x86 and saves us one
> re-analysis unless --param vect-partial-vector-usage is non-default.
>
> Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
>
> Thanks,
> Richard.
>
> * tree-vect-loop.cc (vect_analyze_loop): Prune epilogue
> analysis further when not using partial vectors.
> ---
> gcc/tree-vect-loop.cc | 20 ++++++++++++++++++++
> 1 file changed, 20 insertions(+)
>
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index b91ef4a2325..d9091c6c705 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -3770,6 +3770,26 @@ vect_analyze_loop (class loop *loop, gimple
> *loop_vectorized_call,
> break;
> continue;
> }
> + /* We would need an exhaustive search to find all modes we
> + skipped but that would lead to the same result as another
> + and where we'd could check cached_vf_per_mode against.
I didn't really follow this. Is there a missing word around "another"?
> + Check for the autodetected mode, which is the common
> + situation on x86 which does not perform cost comparison. */
> + if (!supports_partial_vectors
> + && maybe_ge (cached_vf_per_mode[0], first_vinfo_vf)
> + && VECTOR_MODE_P (autodetected_vector_mode)
> + && (related_vector_mode (vector_modes[mode_i],
> + GET_MODE_INNER
> (autodetected_vector_mode))
> + == autodetected_vector_mode)
> + && (related_vector_mode (autodetected_vector_mode,
> + GET_MODE_INNER (vector_modes[mode_i]))
> + == vector_modes[mode_i]))
Not too keen on cutting-&-pasting all this :-) Could we split the
VECTOR_MODE_P onwards into a subroutine that's shared with
vect_analyze_loop_1?
LGTM otherwise FWIW.
Thanks,
Richard
> + {
> + mode_i++;
> + if (mode_i == vector_modes.length ())
> + break;
> + continue;
> + }
>
> if (dump_enabled_p ())
> dump_printf_loc (MSG_NOTE, vect_location,
