From 3d83dd50bc9aed347570e453dfa60f1a69ea4e5a Mon Sep 17 00:00:00 2001
From: Jeff Law <jeffrey.law@oss.qualcomm.com>
Date: Fri, 1 May 2026 15:27:48 -0600
Subject: [PATCH] [PATCH v3] match.pd: (A>>bool) == 0 -> (unsigned)A) <= bool
 [PR119420]

Also add its counterpart:

"(A>>bool) != 0 -> (unsigned)A) > bool"

Changes from v2:
- gate the pattern with "#if GIMPLE"
- use 'single_use' in the rshift result
- add the NE variant
- v2 link: https://gcc.gnu.org/pipermail/gcc-patches/2026-April/712431.html

Bootstrap tested in x86, aarch64 and RISC-V.
Regression tested in x86 and aarch64.

	PR tree-optimization/119420

gcc/ChangeLog

	* match.pd(`(A>>bool) EQ 0 -> (unsigned)A LE bool`): New
	pattern.

gcc/testsuite/ChangeLog

	* gcc.dg/tree-ssa/pr119420.c: New test.
---
 gcc/match.pd                             | 13 ++++++++
 gcc/testsuite/gcc.dg/tree-ssa/pr119420.c | 42 ++++++++++++++++++++++++
 2 files changed, 55 insertions(+)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/pr119420.c

diff --git a/gcc/match.pd b/gcc/match.pd
index 3cf07123e71..5fed1419bdb 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -5439,6 +5439,19 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
       @0)))))
 #endif
 
+#if GIMPLE
+/* PR119420: (A >> bool) == 0 -> (unsigned)a <= (unsigned)bool
+   and its variant:
+   (A >> bool) != 0 -> (unsigned)a > (unsigned)bool;  */
+(for cmp (eq ne)
+     icmp (le gt)
+ (simplify
+  (cmp (rshift@2 @0 zero_one_valued_p@1) integer_zerop)
+  (if (single_use (@2))
+   (with { tree utype = unsigned_type_for (TREE_TYPE (@0)); }
+    (icmp (convert:utype @0) (convert:utype @1))))))
+#endif
+
 /* Rewrite an LROTATE_EXPR by a constant into an
    RROTATE_EXPR by a new constant.  */
 (simplify
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr119420.c b/gcc/testsuite/gcc.dg/tree-ssa/pr119420.c
new file mode 100644
index 00000000000..99259fd4a8b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr119420.c
@@ -0,0 +1,42 @@
+/* { dg-additional-options -O2 } */
+/* { dg-additional-options -fdump-tree-optimized } */
+
+int ll (signed a)
+{
+  int d = a >> 1;
+  return d == 0;
+}
+
+int ll1 (signed a)
+{
+  int d = a & ~1;
+  return d == 0;
+}
+
+int ll2 (signed a)
+{
+  unsigned aa = a;
+  return aa <= 1;
+}
+
+int ll3 (signed a)
+{
+  int d = a >> 1;
+  return d != 0;
+}
+
+int ll4 (signed a)
+{
+  int d = a & ~1;
+  return d != 0;
+}
+
+int ll5 (signed a)
+{
+  unsigned aa = a;
+  return aa > 1;
+}
+
+/* { dg-final { scan-tree-dump-times " >> " 0 optimized } } */
+/* { dg-final { scan-tree-dump-times " <= " 3 optimized } } */
+/* { dg-final { scan-tree-dump-times " > " 3 optimized } } */