[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
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.

diff --git a/gcc/match.pd b/gcc/match.pd
index 3cf07123e716755256f05600ad01c409ddb50fb9..5fed1419bdb30e841e8927b5f79755a7f3389a3a 100644 (file)
--- 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 (file)
index 0000000..99259fd
--- /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 } } */