On Wed, Oct 11, 2023 at 2:46 AM Andrew Pinski <pins...@gmail.com> wrote:
>
> While `a & (b ^ ~a)` is optimized to `a & b` on the rtl level,
> it is always good to optimize this at the gimple level and allows
> us to match a few extra things including where a is a comparison.
>
> Note I had to update/change the testcase and-1.c to avoid matching
> this case as we can match -2 and 1 as bitwise inversions.
OK.
> PR tree-optimization/111282
>
> gcc/ChangeLog:
>
> * match.pd (`a & ~(a ^ b)`, `a & (a == b)`,
> `a & ((~a) ^ b)`): New patterns.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/and-1.c: Update testcase to avoid
> matching `~1 & (a ^ 1)` simplification.
> * gcc.dg/tree-ssa/bitops-6.c: New test.
> ---
> gcc/match.pd | 20 ++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/and-1.c | 6 ++---
> gcc/testsuite/gcc.dg/tree-ssa/bitops-6.c | 33 ++++++++++++++++++++++++
> 3 files changed, 56 insertions(+), 3 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/bitops-6.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 49740d189a7..26b05c157c1 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -1358,6 +1358,26 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> && (!wascmp || element_precision (type) == 1))
> (bit_ior @0 (bit_not @2)))))
>
> +/* a & ~(a ^ b) --> a & b */
> +(simplify
> + (bit_and:c @0 (bit_not (bit_xor:c @0 @1)))
> + (bit_and @0 @1))
> +
> +/* a & (a == b) --> a & b (boolean version of the above). */
> +(simplify
> + (bit_and:c @0 (nop_convert? (eq:c @0 @1)))
> + (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
> + && TYPE_PRECISION (TREE_TYPE (@0)) == 1)
> + (bit_and @0 @1)))
> +
> +/* a & ((~a) ^ b) --> a & b (alt version of the above 2) */
> +(simplify
> + (bit_and:c @0 (bit_xor:c @1 @2))
> + (with { bool wascmp; }
> + (if (bitwise_inverted_equal_p (@0, @1, wascmp)
> + && (!wascmp || element_precision (type) == 1))
> + (bit_and @0 @2))))
> +
> /* (a | b) | (a &^ b) --> a | b */
> (for op (bit_and bit_xor)
> (simplify
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
> index 276c2b9bd8a..27d38907eea 100644
> --- a/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/and-1.c
> @@ -2,10 +2,10 @@
> /* { dg-options "-O -fdump-tree-optimized-raw" } */
>
> int f(int in) {
> - in = in | 3;
> - in = in ^ 1;
> + in = in | 7;
> + in = in ^ 3;
> in = (in & ~(unsigned long)1);
> return in;
> }
>
> -/* { dg-final { scan-tree-dump-not "bit_and_expr" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "bit_and_expr, " "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/bitops-6.c
> b/gcc/testsuite/gcc.dg/tree-ssa/bitops-6.c
> new file mode 100644
> index 00000000000..e6ab2fd6c71
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/bitops-6.c
> @@ -0,0 +1,33 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized-raw" } */
> +/* PR tree-optimization/111282 */
> +
> +
> +int f(int a, int b)
> +{
> + return a & (b ^ ~a); // a & b
> +}
> +
> +_Bool fb(_Bool x, _Bool y)
> +{
> + return x & (y ^ !x); // x & y
> +}
> +
> +int fa(int w, int z)
> +{
> + return (~w) & (w ^ z); // ~w & z
> +}
> +
> +int fcmp(int x, int y)
> +{
> + _Bool a = x == 2;
> + _Bool b = y == 1;
> + return a & (b ^ !a); // (x == 2) & (y == 1)
> +}
> +
> +/* { dg-final { scan-tree-dump-not "bit_xor_expr, " "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "bit_and_expr, " 4 "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "bit_not_expr, " 1 "optimized" } } */
> +/* { dg-final { scan-tree-dump-not "ne_expr, " "optimized" } } */
> +/* { dg-final { scan-tree-dump-times "eq_expr, " 2 "optimized" } } */
> +
> --
> 2.39.3
>
