Re: [PATCH] MATCH: Fix zero_one_valued_p not to match signed 1 bit integers

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

On Fri, Jun 9, 2023 at 3:48 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> So for the attached testcase, we assumed that zero_one_valued_p would
> be the value [0,1] but currently zero_one_valued_p matches also
> signed 1 bit integers.
> This changes that not to match that and fixes the 2 new testcases at
> all optimization levels.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

OK.

> Note the GCC 13 patch will be slightly different due to the changes
> made to zero_one_valued_p.
>
>         PR tree-optimization/110165
>         PR tree-optimization/110166
>
> gcc/ChangeLog:
>
>         * match.pd (zero_one_valued_p): Don't accept
>         signed 1-bit integers.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.c-torture/execute/pr110165-1.c: New test.
>         * gcc.c-torture/execute/pr110166-1.c: New test.
> ---
>  gcc/match.pd                                  | 13 ++++++--
>  .../gcc.c-torture/execute/pr110165-1.c        | 28 ++++++++++++++++
>  .../gcc.c-torture/execute/pr110166-1.c        | 33 +++++++++++++++++++
>  3 files changed, 71 insertions(+), 3 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr110165-1.c
>  create mode 100644 gcc/testsuite/gcc.c-torture/execute/pr110166-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 4ad037d641a..9a6bc2e9348 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -1984,12 +1984,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>    @0)
>
>  /* zero_one_valued_p will match when a value is known to be either
> -   0 or 1 including constants 0 or 1. */
> +   0 or 1 including constants 0 or 1.
> +   Signed 1-bits includes -1 so they cannot match here. */
>  (match zero_one_valued_p
>   @0
> - (if (INTEGRAL_TYPE_P (type) && wi::leu_p (tree_nonzero_bits (@0), 1))))
> + (if (INTEGRAL_TYPE_P (type)
> +      && (TYPE_UNSIGNED (type)
> +         || TYPE_PRECISION (type) > 1)
> +      && wi::leu_p (tree_nonzero_bits (@0), 1))))
>  (match zero_one_valued_p
> - truth_valued_p@0)
> + truth_valued_p@0
> + (if (INTEGRAL_TYPE_P (type)
> +      && (TYPE_UNSIGNED (type)
> +         || TYPE_PRECISION (type) > 1))))
>
>  /* Transform { 0 or 1 } * { 0 or 1 } into { 0 or 1 } & { 0 or 1 }.  */
>  (simplify
> diff --git a/gcc/testsuite/gcc.c-torture/execute/pr110165-1.c b/gcc/testsuite/gcc.c-torture/execute/pr110165-1.c
> new file mode 100644
> index 00000000000..9521a19428e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/pr110165-1.c
> @@ -0,0 +1,28 @@
> +struct s
> +{
> +  int t : 1;
> +};
> +
> +int f(struct s t, int a, int b) __attribute__((noinline));
> +int f(struct s t, int a, int b)
> +{
> +        int bd = t.t;
> +        if (bd) a|=b;
> +        return a;
> +}
> +
> +int main(void)
> +{
> +        struct s t;
> +        for(int i = -1;i <= 1; i++)
> +        {
> +                int a = 0x10;
> +                int b = 0x0f;
> +                int c = a | b;
> +               struct s t = {i};
> +                int r = f(t, a, b);
> +                int exp = (i != 0) ? a | b : a;
> +                if (exp != r)
> +                 __builtin_abort();
> +        }
> +}
> diff --git a/gcc/testsuite/gcc.c-torture/execute/pr110166-1.c b/gcc/testsuite/gcc.c-torture/execute/pr110166-1.c
> new file mode 100644
> index 00000000000..f999d47fe69
> --- /dev/null
> +++ b/gcc/testsuite/gcc.c-torture/execute/pr110166-1.c
> @@ -0,0 +1,33 @@
> +struct s
> +{
> +  int t : 1;
> +  int t1 : 1;
> +};
> +
> +int f(struct s t) __attribute__((noinline));
> +int f(struct s t)
> +{
> +   int c = t.t;
> +   int d = t.t1;
> +   if (c > d)
> +     t.t = d;
> +   else
> +     t.t = c;
> +  return t.t;
> +}
> +
> +int main(void)
> +{
> +        struct s t;
> +        for(int i = -1;i <= 0; i++)
> +        {
> +          for(int j = -1;j <= 0; j++)
> +          {
> +               struct s t = {i, j};
> +                int r = f(t);
> +                int exp = i < j ? i : j;
> +                if (exp != r)
> +                 __builtin_abort();
> +          }
> +        }
> +}
> --
> 2.31.1
>