>From 2ad702b7838e5f8962e8c3a917d6834f089ac097 Mon Sep 17 00:00:00 2001
From: Kael Andrew Alonzo Franco <[email protected]>
Date: Fri, 26 Jun 2026 15:17:50 -0400
Subject: [PATCH] match: Use tree_expr_nonnegative_p instead of
TYPE_UNSIGNED for MAX (A, B) (==,!=) 0 -> (A|B) (==,!=) 0 [PR125749]
tree_expr_nonnegative_p covers non negative signed type variables,
unlike TYPE_UNSIGNED.
Bootstrapped and tested on x86_64-pc-linux-gnu
PR tree-optimization/125749
gcc/ChangeLog:
PR tree-optimization/125749
* match.pd: Use tree_expr_nonnegative_p for MAX (A, B) (==,!=) 0 ->
(A|B) (==,!=) 0.
gcc/testsuite/ChangeLog:
PR tree-optimization/125749
* gcc.dg/pr125749.c: New test.
Signed-off-by: Kael Franco <[email protected]>
---
gcc/match.pd | 14 +++++++-------
gcc/testsuite/gcc.dg/pr125749.c | 20 ++++++++++++++++++++
2 files changed, 27 insertions(+), 7 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr125749.c
diff --git a/gcc/match.pd b/gcc/match.pd
index 615ce9b1963..b5587326c88 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4738,15 +4738,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(cmp (minmax @0 INTEGER_CST@1) INTEGER_CST@2)
(comb (cmp @0 @2) (cmp @1 @2))))
-/* MAX (A, B) == 0 -> (A|B) == 0 iff unsigned.
- MAX (A, B) != 0 -> (A|B) != 0 iff unsigned. */
+/* If A >= 0 and B >= 0:
+ MAX (A, B) == 0 -> (A|B) == 0.
+ MAX (A, B) != 0 -> (A|B) != 0. */
(for cmp (eq ne)
(simplify
- (cmp (max @0 @1) integer_zerop)
- (if (TYPE_UNSIGNED (TREE_TYPE (@0)))
- (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
- (cmp (bit_ior (convert:utype @0) (convert:utype @1))
- { build_zero_cst (utype); } )))))
+ (cmp (max tree_expr_nonnegative_p@0 tree_expr_nonnegative_p@1) integer_zerop)
+ (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
+ (cmp (bit_ior (convert:utype @0) (convert:utype @1))
+ { build_zero_cst (utype); } ))))
/* Undo fancy ways of writing max/min or other ?: expressions, like
a - ((a - b) & -(a < b)) and a - (a - b) * (a < b) into (a < b) ? b : a.
diff --git a/gcc/testsuite/gcc.dg/pr125749.c b/gcc/testsuite/gcc.dg/pr125749.c
new file mode 100644
index 00000000000..cf0fc1e8675
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr125749.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+_Bool
+max_eq_zero (unsigned short a, unsigned short b) {
+ int aa = a;
+ int bb = b;
+ int t = aa > bb ? aa : bb;
+ return (t == 0) == ((a | b) == 0);
+}
+
+_Bool
+max_ne_zero (unsigned short a, unsigned short b) {
+ int aa = a;
+ int bb = b;
+ int t = aa > bb ? aa : bb;
+ return (t != 0) == ((a | b) != 0);
+}
+
+/* { dg-final { scan-tree-dump-times "return 1;" 2 "optimized" } } */
--
2.54.0
