Re: [PATCH] match.pd: Improve y == MIN || x < y optimization [PR105983]

[Richard Biener via Gcc-patches]

> Am 16.06.2022 um 11:14 schrieb Jakub Jelinek via Gcc-patches 
> <gcc-patches@gcc.gnu.org>:
> 
> Hi!
> 
> On the following testcase, we only optimize bar where this optimization
> is performed at GENERIC folding time, but on GIMPLE it doesn't trigger
> anymore, as we actually don't see
>  (bit_and (ne @1 min_value) (ge @0 @1))
> but
>  (bit_and (ne @1 min_value) (le @1 @0))
> genmatch handles :c modifier not just on commutative operations, but
> also comparisons and in that case it means it swaps the comparison.
> 
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
> 

Ok.

Richard 
> 2022-06-16  Jakub Jelinek  <ja...@redhat.com>
> 
>    PR tree-optimization/105983
>    * match.pd (y == XXX_MIN || x < y -> x <= y - 1,
>    y != XXX_MIN && x >= y -> x > y - 1): Use :cs instead of :s
>    on non-equality comparisons.
> 
>    * gcc.dg/tree-ssa/pr105983.c: New test.
> 
> --- gcc/match.pd.jj    2022-06-15 12:52:04.640981511 +0200
> +++ gcc/match.pd    2022-06-15 16:25:58.133845269 +0200
> @@ -2379,14 +2379,14 @@ (define_operator_list SYNC_FETCH_AND_AND
> 
> /* y == XXX_MIN || x < y --> x <= y - 1 */
> (simplify
> - (bit_ior:c (eq:s @1 min_value) (lt:s @0 @1))
> + (bit_ior:c (eq:s @1 min_value) (lt:cs @0 @1))
>   (if (INTEGRAL_TYPE_P (TREE_TYPE (@1))
>        && TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
>   (le @0 (minus @1 { build_int_cst (TREE_TYPE (@1), 1); }))))
> 
> /* y != XXX_MIN && x >= y --> x > y - 1 */
> (simplify
> - (bit_and:c (ne:s @1 min_value) (ge:s @0 @1))
> + (bit_and:c (ne:s @1 min_value) (ge:cs @0 @1))
>   (if (INTEGRAL_TYPE_P (TREE_TYPE (@1))
>        && TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
>   (gt @0 (minus @1 { build_int_cst (TREE_TYPE (@1), 1); }))))
> --- gcc/testsuite/gcc.dg/tree-ssa/pr105983.c.jj    2022-06-15 
> 16:41:56.214166604 +0200
> +++ gcc/testsuite/gcc.dg/tree-ssa/pr105983.c    2022-06-15 16:41:33.150470043 
> +0200
> @@ -0,0 +1,17 @@
> +/* PR tree-optimization/105983 */
> +/* { dg-do compile } */
> +/* { dg-options "-O2 --param=logical-op-non-short-circuit=1 
> -fdump-tree-optimized" } */
> +/* { dg-final { scan-tree-dump-not " != 0;" "optimized" } } */
> +/* { dg-final { scan-tree-dump-not " & " "optimized" } } */
> +
> +int
> +foo (unsigned a, unsigned b)
> +{
> +  return b != 0 && a >= b;
> +}
> +
> +int
> +bar (unsigned a, unsigned b)
> +{
> +  return b != 0 & a >= b;
> +}
> 
>    Jakub
>