On Mon, Nov 22, 2021 at 7:26 AM apinski--- via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> From: Andrew Pinski <apin...@marvell.com>
>
> Combine disabled this optimization in r10-254-gddbb5da5199fb42 but it makes
> sense to do this on the gimple level and then let expand decide which way is
> better. So this adds the transformation on the gimple level (late like was
> done for the multiply case).
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> PR tree-optimization/92342
>
> gcc/ChangeLog:
>
> * match.pd (b & -(a CMP c) -> (a CMP c)?b:0): New pattern.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/andnegcmp-1.c: New test.
> * gcc.dg/tree-ssa/andnegcmp-2.c: New test.
> ---
> gcc/match.pd | 8 +++++++-
> gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-1.c | 14 ++++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-2.c | 14 ++++++++++++++
> 3 files changed, 35 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-1.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-2.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index ed43c321cbc..b55cbc91b57 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -1794,7 +1794,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> (for cmp (tcc_comparison)
> (simplify
> (mult:c (convert (cmp @0 @1)) @2)
> - (cond (cmp @0 @1) @2 { build_zero_cst (type); }))))
> + (cond (cmp @0 @1) @2 { build_zero_cst (type); }))
> +/* (-(m1 CMP m2)) & d -> (m1 CMP m2) ? d : 0 */
> + (simplify
> + (bit_and:c (negate (convert (cmp @0 @1))) @2)
I think you need to guard against signed bools (and vector compares,
and allow view_convert for vector compare results?)?
> + (cond (cmp @0 @1) @2 { build_zero_cst (type); }))
> + )
> +)
>
> /* For integral types with undefined overflow and C != 0 fold
> x * C EQ/NE y * C into x EQ/NE y. */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-1.c
> new file mode 100644
> index 00000000000..6f16783f169
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-1.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* PR tree-optimization/92342 */
> +
> +int
> +f (int m1, int m2, int c)
> +{
> + int d = m1 == m2;
> + d = -d;
> + int e = d & c;
> + return e;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "\\? c_\[0-9\]\\(D\\) : 0" 1
> "optimized" } } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-2.c
> new file mode 100644
> index 00000000000..0e25c8abc39
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/andnegcmp-2.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* PR tree-optimization/92342 */
> +
> +int
> +f (int m1, int m2, int c)
> +{
> + int d = m1 < m2;
> + d = -d;
> + int e = c & d;
> + return e;
> +}
> +
> +/* { dg-final { scan-tree-dump-times "\\? c_\[0-9\]\\(D\\) : 0" 1
> "optimized" } } */
> --
> 2.17.1
>
