Re: [PATCH V2] Restrict the two sources of vect_recog_cond_expr_convert_pattern to be of the same type when convert is extension.

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Feb 17, 2022 at 6:32 AM liuhongt via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> > I find this quite unreadable, it looks like if @2 and @3 are treated
> > differently.  I think keeping the old 3 lines and just adding
> >       && (TYPE_PRECISION (TREE_TYPE (@0)) >= TYPE_PRECISION (type)
> >           || (TYPE_UNSIGNED (TREE_TYPE (@2))
> >               == TYPE_UNSIGNED (TREE_TYPE (@3))))
> > after it ideally with a comment why would be better.
> Update patch.

OK.

Thanks,
Richard.

> gcc/ChangeLog:
>
>         PR tree-optimization/104551
>         PR tree-optimization/103771
>         * match.pd (cond_expr_convert_p): Add types_match check when
>         convert is extension.
>         * tree-vect-patterns.cc
>         (gimple_cond_expr_convert_p): Adjust comments.
>         (vect_recog_cond_expr_convert_pattern): Ditto.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr104551.c: New test.
> ---
>  gcc/match.pd                             |  6 ++++++
>  gcc/testsuite/gcc.target/i386/pr104551.c | 24 ++++++++++++++++++++++++
>  gcc/tree-vect-patterns.cc                |  6 ++++--
>  3 files changed, 34 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr104551.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 05a10ab6bfd..8b6f22f1065 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -7698,5 +7698,11 @@ and,
>           == TYPE_PRECISION (TREE_TYPE (@2))
>         && TYPE_PRECISION (TREE_TYPE (@0))
>           == TYPE_PRECISION (TREE_TYPE (@3))
> +       /* For vect_recog_cond_expr_convert_pattern, @2 and @3 can differ in
> +         signess when convert is truncation, but not ok for extension since
> +         it's sign_extend vs zero_extend.  */
> +       && (TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (type)
> +          || (TYPE_UNSIGNED (TREE_TYPE (@2))
> +              == TYPE_UNSIGNED (TREE_TYPE (@3))))
>         && single_use (@4)
>         && single_use (@5))))
> diff --git a/gcc/testsuite/gcc.target/i386/pr104551.c b/gcc/testsuite/gcc.target/i386/pr104551.c
> new file mode 100644
> index 00000000000..6300f25c0d5
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr104551.c
> @@ -0,0 +1,24 @@
> +/* { dg-do run } */
> +/* { dg-options "-O3 -mavx2" } */
> +/* { dg-require-effective-target avx2 } */
> +
> +unsigned int
> +__attribute__((noipa))
> +test(unsigned int a, unsigned char p[16]) {
> +  unsigned int res = 0;
> +  for (unsigned b = 0; b < a; b += 1)
> +    res = p[b] ? p[b] : (char) b;
> +  return res;
> +}
> +
> +int main ()
> +{
> +  unsigned int a = 16U;
> +  unsigned char p[16];
> +  for (int i = 0; i != 16; i++)
> +    p[i] = (unsigned char)128;
> +  unsigned int res = test (a, p);
> +  if (res != 128)
> +    __builtin_abort ();
> +  return 0;
> +}
> diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
> index a8f96d59643..217bdfd7045 100644
> --- a/gcc/tree-vect-patterns.cc
> +++ b/gcc/tree-vect-patterns.cc
> @@ -929,8 +929,10 @@ vect_reassociating_reduction_p (vec_info *vinfo,
>     with conditions:
>     1) @1, @2, c, d, a, b are all integral type.
>     2) There's single_use for both @1 and @2.
> -   3) a, c and d have same precision.
> +   3) a, c have same precision.
>     4) c and @1 have different precision.
> +   5) c, d are the same type or they can differ in sign when convert is
> +   truncation.
>
>     record a and c and d and @3.  */
>
> @@ -952,7 +954,7 @@ extern bool gimple_cond_expr_convert_p (tree, tree*, tree (*)(tree));
>     TYPE_PRECISION (TYPE_E) != TYPE_PRECISION (TYPE_CD);
>     TYPE_PRECISION (TYPE_AB) == TYPE_PRECISION (TYPE_CD);
>     single_use of op_true and op_false.
> -   TYPE_AB could differ in sign.
> +   TYPE_AB could differ in sign when (TYPE_E) A is a truncation.
>
>     Input:
>
> --
> 2.18.1
>