The following adds two patterns simplifying comparisons,
uns < (typeof uns)(uns != 0) is always false and x != (typeof x)(x == 0)
is always true.
Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed.
PR tree-optimization/110278
* match.pd (uns < (typeof uns)(uns != 0) -> false): New.
(x != (typeof x)(x == 0) -> true): Likewise.
---
gcc/match.pd | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 264f9cb8a40..48b76e6a051 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
--
2.35.3
