[gcc r17-3283] match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | b, 1) [PR126646]

https://gcc.gnu.org/g:b190388bad47b1d3507abd52dc2a07f39a899984

commit r17-3283-gb190388bad47b1d3507abd52dc2a07f39a899984
Author: Reshma Roy <[email protected]>
Date:   Tue Aug 11 11:48:05 2026 +0530

    match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | b, 1) [PR126646]
    
    gcc/ChangeLog:
    
            PR tree-optimization/126646
            * match.pd: Fold umin(a, 1) | umin(b, 1) into umin(a | b, 1).
    
    gcc/testsuite/ChangeLog:
    
            * gcc.dg/tree-ssa/pr126646-1.c: New test.
            * gcc.dg/tree-ssa/pr126646-2.c: New test.

Diff:
---
 gcc/match.pd                               |  5 +++++
 gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c | 15 +++++++++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c | 13 +++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/gcc/match.pd b/gcc/match.pd
index 7fa15845e7a5..26cb2c9e155b 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -4901,6 +4901,11 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
   (bit_not (minmax:cs (bit_not @0) @1))
   (maxmin @0 (bit_not @1))))
 
+/* umin (a, 1) | umin (b, 1) -> umin (a | b, 1).  */
+ (simplify
+  (bit_ior (min @0 integer_onep@2) (min @1 @2))
+    (if (tree_expr_nonnegative_p (@0) && tree_expr_nonnegative_p (@1))
+     (min (bit_ior @0 @1) @2)))
 /* MIN (X, Y) == X -> X <= Y  */
 /* MIN (X, Y) < X -> X > Y  */
 /* MIN (X, Y) >= X -> X <= Y  */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c
new file mode 100644
index 000000000000..447a1739b5f9
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+/* The test case should produce only one min expr.  */
+/* umin(a,1) | umin(b,1) -> umin(a|b, 1).  */
+
+unsigned min_or (unsigned a, unsigned b)
+{
+  unsigned t = 1;
+  a = a < t ? a : t;
+  b = b < t ? b : t;
+  return a | b;
+}
+
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } */
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c
new file mode 100644
index 000000000000..3b47eee96565
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr126646-2.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+int f (int a, int b)
+{
+  int x = __builtin_abs (a);
+  int y = __builtin_abs (b);
+  int p = x < 1 ? x : 1;
+  int q = y < 1 ? y : 1;
+  return p | q;
+}
+
+/* { dg-final { scan-tree-dump-times "MIN_EXPR" 1 "optimized" } } */