https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66739
--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
I am testing
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 225453)
+++ gcc/match.pd (working copy)
@@ -1336,8 +1353,9 @@ (define_operator_list CBRT BUILT_IN_CBRT
attempts to synthetize ABS_EXPR. */
(for cmp (eq ne)
(simplify
- (cmp (minus @0 @1) integer_zerop)
- (cmp @0 @1)))
+ (cmp (minus@2 @0 @1) integer_zerop)
+ (if (single_use (@2))
+ (cmp @0 @1))))
/* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
signed arithmetic case. That form is created by the compiler
