From: Jakub Jelinek <jakub@redhat.com>
Date: Thu, 20 May 2021 07:10:38 +0000 (+0200)
Subject: phiopt: Simplify (X & Y) == X -> (X & ~Y) == 0 even in presence of integral conversio... 
X-Git-Tag: basepoints/gcc-13~7378
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=2b536797f7e43c55072a3215735f5833f1d6d218;p=thirdparty%2Fgcc.git

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

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.

2021-05-20  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/94589
	* match.pd ((X & Y) == X -> (X & ~Y) == 0): Simplify even in presence
	of integral conversions.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index cdb876369518..e01bb7a4080c 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4769,6 +4769,16 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
  (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