From: Richard Biener <rguenther@suse.de>
Date: Fri, 16 Jun 2023 09:47:45 +0000 (+0200)
Subject: tree-optimization/110278 - uns < (typeof uns)(uns != 0) is always false
X-Git-Tag: basepoints/gcc-15~8256
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69b04fe7445c88edafd6983e28353a158e4314b5;p=thirdparty%2Fgcc.git

tree-optimization/110278 - uns < (typeof uns)(uns != 0) is always false

The following adds two patterns simplifying comparisons,
uns < (typeof uns)(uns != 0) is always false and x != (typeof x)(x == 0)
is always true.

	PR tree-optimization/110278
	* match.pd (uns < (typeof uns)(uns != 0) -> false): New.
	(x != (typeof x)(x == 0) -> true): Likewise.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index b7baad6bf1bd..2dd238260346 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6410,6 +6410,17 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
 	 (if (cmp == GT_EXPR)
 	  (lt (view_convert:st @0) { build_zero_cst (st); })))))))))))
 
+/* unsigned < (typeof unsigned)(unsigned != 0) is always false.  */
+(simplify
+ (lt:c @0 (convert (ne @0 integer_zerop)))
+ (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
+  { constant_boolean_node (false, type); }))
+
+/* x != (typeof x)(x == 0) is always true.  */
+(simplify
+ (ne:c @0 (convert (eq @0 integer_zerop)))
+ { constant_boolean_node (true, type); })
+
 (for cmp (unordered ordered unlt unle ungt unge uneq ltgt)
  /* If the second operand is NaN, the result is constant.  */
  (simplify