On Mon, Oct 16, 2023 at 4:34 AM Andrew Pinski <pins...@gmail.com> wrote:
>
> Currently we able to simplify `~a CMP ~b` to `b CMP a` but we should allow a
> nop
> conversion in between the `~` and the `a` which can show up. A similarly
> thing should
> be done for `~a CMP CST`.
>
> I had originally submitted the `~a CMP CST` case as
> https://gcc.gnu.org/pipermail/gcc-patches/2021-November/585088.html;
> I noticed we should do the same thing for the `~a CMP ~b` case and combined
> it with that one here.
>
> OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.
OK.
> PR tree-optimization/31531
>
> gcc/ChangeLog:
>
> * match.pd (~X op ~Y): Allow for an optional nop convert.
> (~X op C): Likewise.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.dg/tree-ssa/pr31531-1.c: New test.
> * gcc.dg/tree-ssa/pr31531-2.c: New test.
> ---
> gcc/match.pd | 10 ++++---
> gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c | 19 +++++++++++++
> gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c | 34 +++++++++++++++++++++++
> 3 files changed, 59 insertions(+), 4 deletions(-)
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index 51e5065d086..e76ec1ec034 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -5944,18 +5944,20 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
> /* Fold ~X op ~Y as Y op X. */
> (for cmp (simple_comparison)
> (simplify
> - (cmp (bit_not@2 @0) (bit_not@3 @1))
> + (cmp (nop_convert1?@4 (bit_not@2 @0)) (nop_convert2? (bit_not@3 @1)))
> (if (single_use (@2) && single_use (@3))
> - (cmp @1 @0))))
> + (with { tree otype = TREE_TYPE (@4); }
> + (cmp (convert:otype @1) (convert:otype @0))))))
>
> /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
> (for cmp (simple_comparison)
> scmp (swapped_simple_comparison)
> (simplify
> - (cmp (bit_not@2 @0) CONSTANT_CLASS_P@1)
> + (cmp (nop_convert? (bit_not@2 @0)) CONSTANT_CLASS_P@1)
> (if (single_use (@2)
> && (TREE_CODE (@1) == INTEGER_CST || TREE_CODE (@1) == VECTOR_CST))
> - (scmp @0 (bit_not @1)))))
> + (with { tree otype = TREE_TYPE (@1); }
> + (scmp (convert:otype @0) (bit_not @1))))))
>
> (for cmp (simple_comparison)
> (simplify
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> new file mode 100644
> index 00000000000..c27299151eb
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-1.c
> @@ -0,0 +1,19 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* PR tree-optimization/31531 */
> +
> +int f(int a)
> +{
> + int b = ~a;
> + return b<0;
> +}
> +
> +
> +int f1(unsigned a)
> +{
> + int b = ~a;
> + return b<0;
> +}
> +/* We should convert the above two functions from b <0 to ((int)a) >= 0. */
> +/* { dg-final { scan-tree-dump-times ">= 0" 2 "optimized"} } */
> +/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
> b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
> new file mode 100644
> index 00000000000..865ea292215
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr31531-2.c
> @@ -0,0 +1,34 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -fdump-tree-optimized" } */
> +/* PR tree-optimization/31531 */
> +
> +int f0(unsigned x, unsigned t)
> +{
> + x = ~x;
> + t = ~t;
> + int xx = x;
> + int tt = t;
> + return tt < xx;
> +}
> +
> +int f1(unsigned x, int t)
> +{
> + x = ~x;
> + t = ~t;
> + int xx = x;
> + int tt = t;
> + return tt < xx;
> +}
> +
> +int f2(int x, unsigned t)
> +{
> + x = ~x;
> + t = ~t;
> + int xx = x;
> + int tt = t;
> + return tt < xx;
> +}
> +
> +
> +/* We should be able to remove all ~ from the above functions. */
> +/* { dg-final { scan-tree-dump-times "~" 0 "optimized"} } */
> --
> 2.39.3
>
