Re: [PATCH] tree-optimization/101756 - avoid vectorizing boolean MAX reductions

[Christophe Lyon <christophe.lyon.oss@gmail.com>]

On Wed, Aug 4, 2021 at 12:33 PM Richard Biener <rguenther@suse.de> wrote:

> The following avoids vectorizing MIN/MAX reductions on bools which,
> when ending up as vector(2) <signed-boolean:64> would need to be
> adjusted because of the sign change.  The fix instead avoids any
> reduction vectorization where the result isn't compatible
> to the original scalar type since we don't compensate for that
> either.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
>
> 2021-08-04  Richard Biener  <rguenther@suse.de>
>
>         PR tree-optimization/101756
>         * tree-vect-slp.c (vectorizable_bb_reduc_epilogue): Make sure
>         the result of the reduction epilogue is compatible to the original
>         scalar result.
>
>         * gcc.dg/vect/bb-slp-pr101756.c: New testcase.
>

Hi,

The new testcase fails on aarch64 because:
 FAIL: gcc.dg/vect/bb-slp-pr101756.c (test for excess errors)
Excess errors:
/gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c:4:1: warning: GCC does not
currently support mixed size types for 'simd' functions

Can you check?

Thanks

Christophe




> ---
>  gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c | 15 +++++++++++++++
>  gcc/tree-vect-slp.c                         |  8 +++++---
>  2 files changed, 20 insertions(+), 3 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c
>
> diff --git a/gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c
> b/gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c
> new file mode 100644
> index 00000000000..9420e77f64e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/vect/bb-slp-pr101756.c
> @@ -0,0 +1,15 @@
> +/* { dg-do compile } */
> +
> +__attribute__ ((simd)) int
> +tq (long int ea, int of, int kk)
> +{
> +  int bc;
> +
> +  for (bc = 0; bc < 2; ++bc)
> +    {
> +      ++ea;
> +      of |= !!kk < !!ea;
> +    }
> +
> +  return of;
> +}
> diff --git a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
> index a554c24e0fb..d169bed8e94 100644
> --- a/gcc/tree-vect-slp.c
> +++ b/gcc/tree-vect-slp.c
> @@ -4847,15 +4847,17 @@ static bool
>  vectorizable_bb_reduc_epilogue (slp_instance instance,
>                                 stmt_vector_for_cost *cost_vec)
>  {
> -  enum tree_code reduc_code
> -    = gimple_assign_rhs_code (instance->root_stmts[0]->stmt);
> +  gassign *stmt = as_a <gassign *> (instance->root_stmts[0]->stmt);
> +  enum tree_code reduc_code = gimple_assign_rhs_code (stmt);
>    if (reduc_code == MINUS_EXPR)
>      reduc_code = PLUS_EXPR;
>    internal_fn reduc_fn;
>    tree vectype = SLP_TREE_VECTYPE (SLP_INSTANCE_TREE (instance));
>    if (!reduction_fn_for_scalar_code (reduc_code, &reduc_fn)
>        || reduc_fn == IFN_LAST
> -      || !direct_internal_fn_supported_p (reduc_fn, vectype,
> OPTIMIZE_FOR_BOTH))
> +      || !direct_internal_fn_supported_p (reduc_fn, vectype,
> OPTIMIZE_FOR_BOTH)
> +      || !useless_type_conversion_p (TREE_TYPE (gimple_assign_lhs (stmt)),
> +                                    TREE_TYPE (vectype)))
>      return false;
>
>    /* There's no way to cost a horizontal vector reduction via REDUC_FN so
> --
> 2.31.1
>