This patch introduces a simplification rule in match.pd to reduce bitwise
expressions against zero. Specifically, it simplifies patterns where a
variable checked against zero is combined via bitwise AND/OR with a compounded
bitwise OR check against zero.
PR tree-optimization/125442
gcc/ChangeLog:
* match.pd: Add simplification rules for
(a == 0) | ((a | b) == 0) -> (a == 0) and
(a != 0) & ((a | b) != 0) -> (a != 0).
---
gcc/match.pd | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/gcc/match.pd b/gcc/match.pd
index 8a2de136e..4a2f9a784 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -6660,6 +6660,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(simplify
(bitop (neeql @0 @1) (neeqr (bit_ior @0 @1) integer_zerop))
{ constant_boolean_node (bitop == BIT_IOR_EXPR, type); }))
+
+/* (a == 0) | ((a | b) == 0) -> (a == 0) -- PR125442
+ (a != 0) & ((a | b) != 0) -> (a != 0) -- PR125442 */
+
+(for bitop (bit_and bit_ior)
+ neeq (ne eq)
+(simplify
+ (bitop:c (neeq@2 @0 integer_zerop) (neeq (bit_ior:c @0 @1) integer_zerop))
+ @2))
#endif
/* These was part of minmax phiopt. */
--
2.43.0
