[PATCH] phiopt: Simplify (X & Y) == X -> (X & ~Y) == 0 even in presence of integral conversions [PR94589]

[Richard Biener]

On Wed, 19 May 2021, Jakub Jelinek wrote:

> On Wed, May 19, 2021 at 11:09:19AM +0200, Jakub Jelinek via Gcc-patches wrote:
> > On Wed, May 19, 2021 at 10:15:53AM +0200, Christophe Lyon via Gcc-patches wrote:
> > > After this update, the test fails on arm and aarch64: according to the
> > > logs, the optimization is still performed 14 times.
> > 
> > Seems this is because
> >               if (change
> >                   && !flag_syntax_only
> >                   && (load_extend_op (TYPE_MODE (TREE_TYPE (and0)))
> >                       == ZERO_EXTEND))
> >                 {
> >                   tree uns = unsigned_type_for (TREE_TYPE (and0));
> >                   and0 = fold_convert_loc (loc, uns, and0);
> >                   and1 = fold_convert_loc (loc, uns, and1);
> >                 }
> > in fold-const.c adds on these targets extra casts that prevent the
> > optimizations.
> 
> This patch seems to fix it (but I don't have an easy way to test on aarch64
> or arm on the trunk and 11 branch would need numerous backports).

OK if somebody manages to test on arm/aarch64.

Richard.

> 2021-05-19  Jakub Jelinek  <jakub@redhat.com>
> 
> 	PR tree-optimization/94589
> 	* match.pd ((X & Y) == X -> (X & ~Y) == 0): Simplify even in presence
> 	of integral conversions.
> 
> --- gcc/match.pd.jj	2021-05-15 10:10:28.000000000 +0200
> +++ gcc/match.pd	2021-05-19 11:34:42.130624557 +0200
> @@ -4769,6 +4769,16 @@ (define_operator_list COND_TERNARY
>   (simplify
>    (cmp:c (bit_and:c @0 @1) @0)
>    (cmp (bit_and @0 (bit_not! @1)) { build_zero_cst (TREE_TYPE (@0)); }))
> + (simplify
> +  (cmp:c (convert@3 (bit_and (convert@2 @0) INTEGER_CST@1)) (convert @0))
> +  (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
> +       && INTEGRAL_TYPE_P (TREE_TYPE (@2))
> +       && INTEGRAL_TYPE_P (TREE_TYPE (@3))
> +       && TYPE_PRECISION (TREE_TYPE (@2)) == TYPE_PRECISION (TREE_TYPE (@0))
> +       && TYPE_PRECISION (TREE_TYPE (@3)) > TYPE_PRECISION (TREE_TYPE (@2))
> +       && !wi::neg_p (wi::to_wide (@1)))
> +   (cmp (bit_and @0 (convert (bit_not @1)))
> +	{ build_zero_cst (TREE_TYPE (@0)); })))
>  
>   /* (X | Y) == Y becomes (X & ~Y) == 0.  */
>   (simplify
> 
> 
> 	Jakub