Re: [PATCH] vect: Check gather/scatter offset types [PR108316]

[Richard Biener via Gcc-patches]

> Am 08.02.2023 um 10:00 schrieb Richard Sandiford via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> The gather/scatter support can over-widen an offset if the target
> requires it, but this relies on using a pattern sequence to add
> the widening conversion.  That failed in the testcase because an
> earlier pattern (bool) took priority.
> 
> I think we should allow patterns to be applied to other patterns,
> but that's quite an invasive change and isn't suitable for stage 4.
> This patch instead punts if the offset type doesn't match the
> expected one.
> 
> If we switched to using the SLP representation for everything,
> we would probably handle both patterns by rewriting the graph,
> which should be much easier.
> 
> Tested on aarch64-linux-gnu & x86_64-linux-gnu.  OK to install?

Ok.

Richard 

> Richard
> 
> 
> gcc/
>    PR tree-optimization/108316
>    * tree-vect-stmts.cc (get_load_store_type): When using
>    internal functions for gather/scatter, make sure that the type
>    of the offset argument is consistent with the offset vector type.
> 
> gcc/testsuite/
>    PR tree-optimization/108316
>    * gcc.dg/vect/pr108316.c: New test.
> ---
> gcc/testsuite/gcc.dg/vect/pr108316.c | 11 +++++++++++
> gcc/tree-vect-stmts.cc               | 17 +++++++++++++++++
> 2 files changed, 28 insertions(+)
> create mode 100644 gcc/testsuite/gcc.dg/vect/pr108316.c
> 
> diff --git a/gcc/testsuite/gcc.dg/vect/pr108316.c 
> b/gcc/testsuite/gcc.dg/vect/pr108316.c
> new file mode 100644
> index 00000000000..540b7f2aed4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/pr108316.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O3" } */
> +
> +extern _Bool a[];
> +
> +void
> +foo (short i, int b[][64][1])
> +{
> +  for (; i < 64; i += 4)
> +    a[i] = b[0][i] != 0;
> +}
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index eb4ca1f184e..c86249adcc3 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -2474,6 +2474,23 @@ get_load_store_type (vec_info  *vinfo, stmt_vec_info 
> stmt_info,
>       *memory_access_type = VMAT_GATHER_SCATTER;
>       if (!vect_check_gather_scatter (stmt_info, loop_vinfo, gs_info))
>    gcc_unreachable ();
> +      /* When using internal functions, we rely on pattern recognition
> +     to convert the type of the offset to the type that the target
> +     requires, with the result being a call to an internal function.
> +     If that failed for some reason (e.g. because another pattern
> +     took priority), just handle cases in which the offset already
> +     has the right type.  */
> +      else if (gs_info->ifn != IFN_LAST
> +           && !is_gimple_call (stmt_info->stmt)
> +           && !tree_nop_conversion_p (TREE_TYPE (gs_info->offset),
> +                      TREE_TYPE (gs_info->offset_vectype)))
> +    {
> +      if (dump_enabled_p ())
> +        dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                 "%s offset requires a conversion\n",
> +                 vls_type == VLS_LOAD ? "gather" : "scatter");
> +      return false;
> +    }
>       else if (!vect_is_simple_use (gs_info->offset, vinfo,
>                    &gs_info->offset_dt,
>                    &gs_info->offset_vectype))
> -- 
> 2.25.1
>