From: Richard Biener <rguenther@suse.de>
Date: Wed, 28 Jan 2026 09:04:45 +0000 (+0100)
Subject: tree-optimization/123537 - fix too permissive .REDUC_* folding
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6868526bb79051895864a006c757ee5aee8e9574;p=thirdparty%2Fgcc.git

tree-optimization/123537 - fix too permissive .REDUC_* folding

The following restricts the allowed conversions to those maintaining
the element type size.

	PR tree-optimization/123537
	* match.pd (REDUC (@0 & @1) -> @0[I] & @1[I]): Restrict
	allowed conversions.

	* gcc.dg/pr123537.c: New testcase.
---

diff --git a/gcc/match.pd b/gcc/match.pd
index e94e474bdc5..01b95ec0755 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -11415,10 +11415,11 @@ and,
 	    unsigned int elt_bits = tree_to_uhwi (TYPE_SIZE (elt_type));
 	    tree size = bitsize_int (elt_bits);
 	    tree pos = bitsize_int (elt_bits * i); }
-     (view_convert
-      (bit_and:elt_type
-       (BIT_FIELD_REF:elt_type @0 { size; } { pos; })
-       { elt; })))))))
+     (if (compare_tree_int (TYPE_SIZE (type), elt_bits) == 0)
+      (view_convert
+       (bit_and:elt_type
+        (BIT_FIELD_REF:elt_type @0 { size; } { pos; })
+        { elt; }))))))))
 
 /* Fold reduction of a single nonzero element constructor.  */
 (for reduc (IFN_REDUC_PLUS IFN_REDUC_IOR IFN_REDUC_XOR)
diff --git a/gcc/testsuite/gcc.dg/pr123537.c b/gcc/testsuite/gcc.dg/pr123537.c
new file mode 100644
index 00000000000..ff178358179
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr123537.c
@@ -0,0 +1,20 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-O2" } */
+
+typedef __attribute__((__vector_size__(16))) __int128 V;
+
+union {
+  _Complex long c;
+  V v;
+} u;
+
+__int128 j;
+int i;
+
+void
+foo()
+{
+  u.v &= 4;
+  i %= u.c ? 3 : j;
+}