Re: [PATCH] Simplify "1 - bool_val" to "bool_val ^ 1"

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

On Wed, Feb 1, 2023 at 2:30 AM Andrew Pinski via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> For bool values, it is easier to deal with
> xor 1 rather than having 1 - a. This is because
> we are more likely to simplify the xor further in many
> cases.
>
> This is a special case for (MASK - b) where MASK
> is a powerof2 - 1 and b <= MASK but only for bool
> ranges ([0,1]) as that is the main case where the
> difference comes into play.
>
> Note this is enabled for gimple folding only
> as the ranges are only know while doing gimple
> folding and cfun is not always set when fold is called.

Can we robustify ssa_name_has_boolean_range_p instead?
I see it's called even from GENERIC folding in match.pd already.

Otherwise OK.

Thanks,
Richard.

>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no
> regressions.
>
> gcc/ChangeLog:
>
>         PR tree-optimization/108355

I think this should be 108354?

>         PR tree-optimization/96921
>         * match.pd: Add pattern for "1 - bool_val".
>
> gcc/testsuite/ChangeLog:
>
>         PR tree-optimization/108355
>         PR tree-optimization/96921
>         * gcc.dg/tree-ssa/bool-minus-1.c: New test.
>         * gcc.dg/tree-ssa/bool-minus-2.c: New test.
>         * gcc.dg/tree-ssa/pr108354-1.c: New test.
> ---
>  gcc/match.pd                                 | 13 ++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c | 11 +++++++
>  gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c | 33 ++++++++++++++++++++
>  gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c   | 26 +++++++++++++++
>  4 files changed, 83 insertions(+)
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index f605b798c44..c9e8bebede2 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -1732,6 +1732,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
>   (if (!FIXED_POINT_TYPE_P (type))
>   (plus @0 (negate @1))))
>
> +#if GIMPLE
> +/* 1 - a is a ^ 1 if a had a bool range. */
> +/* This is only enabled for gimple as sometimes
> +   cfun is not set for the function which contains
> +   the SSA_NAME (e.g. while IPA passes are happening,
> +   fold might be called).  */
> +(simplify
> + (minus integer_onep@0 SSA_NAME@1)
> +  (if (INTEGRAL_TYPE_P (type)
> +       && ssa_name_has_boolean_range (@1))
> +   (bit_xor @1 @0)))
> +#endif
> +
>  /* Other simplifications of negation (c.f. fold_negate_expr_1).  */
>  (simplify
>   (negate (mult:c@0 @1 negate_expr_p@2))
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c
> new file mode 100644
> index 00000000000..e434ff9507a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-1.c
> @@ -0,0 +1,11 @@
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +_Bool
> +foo (_Bool a)
> +{
> +  int c = 1 - a;
> +  return c;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "1 - " 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "~a" 1 "optimized" } } */
> +
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c
> new file mode 100644
> index 00000000000..b77d36c1d3c
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bool-minus-2.c
> @@ -0,0 +1,33 @@
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +_Bool
> +foo (_Bool a, _Bool b)
> +{
> +  int c = 1 - a;
> +  int d = 1 - b;
> +  int e = c & d;
> +  return 1 - e;
> +}
> +
> +_Bool
> +bar (_Bool a, _Bool b)
> +{
> +  int c = 1 - a;
> +  int d = 1 - b;
> +  _Bool e = c & d;
> +  return 1 - e;
> +}
> +
> +_Bool
> +baz (_Bool a, _Bool b)
> +{
> +  _Bool c = 1 - a;
> +  _Bool d = 1 - b;
> +  _Bool e = c & d;
> +  return 1 - e;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "1 - " 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "~a" 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "~b" 0 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "a_\[0-9\]+.D. \\\| b_\[0-9\]+.D." 3 "optimized" } } */
> +
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c
> new file mode 100644
> index 00000000000..60d1dbc281e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr108354-1.c
> @@ -0,0 +1,26 @@
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +
> +int b;
> +int *c;
> +int e;
> +static int *f = &e;
> +int g;
> +void foo();
> +short(a)(short h, short i) { return h - i; }
> +int(d)(int h) { return h == 83647 ? 0 : -h; }
> +int main() {
> +  short j;
> +  int *k = &e, *l = &b;
> +  *f = 0 == c;
> +  j = a(0 != 2, *k);
> +  if (d(j ^ (0 == l || *k)) != *k)
> +    ;
> +  else
> +    foo();
> +  c = &g;
> +}
> +
> +/* { dg-final { scan-tree-dump-times " 1 - " 0 "optimized" } } */
> +/* There should be no calls to foo. */
> +/* { dg-final { scan-tree-dump-times "foo " 0 "optimized" } } */
> +
> --
> 2.17.1
>