From: Richard Biener <rguenther@suse.de>
Date: Mon, 27 Oct 2025 10:31:32 +0000 (+0100)
Subject: tree-optimization/122419 - reduction chain with conversion as op
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=187bccedfc454304f7e35697baa5337c59fa2a58;p=thirdparty%2Fgcc.git

tree-optimization/122419 - reduction chain with conversion as op

The following deals with reduction detection handling a non-noop
conversion as reduction operation and makes the reduction chain
chain re-discovery handle this situation the same.

	PR tree-optimization/122419
	* tree-vect-slp.cc (vect_analyze_slp_reduc_chain): Only
	skip noop conversions.

	* gcc.dg/vect/pr122419.c: New testcase.
---

diff --git a/gcc/testsuite/gcc.dg/vect/pr122419.c b/gcc/testsuite/gcc.dg/vect/pr122419.c
new file mode 100644
index 00000000000..b428cfb1812
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/vect/pr122419.c
@@ -0,0 +1,9 @@
+/* { dg-do compile } */
+
+int a;
+long b;
+void c()
+{
+  for (; b; b--)
+    a = (char)a;
+}
diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
index 31d84857d49..e02b3379bb4 100644
--- a/gcc/tree-vect-slp.cc
+++ b/gcc/tree-vect-slp.cc
@@ -4217,6 +4217,7 @@ vect_analyze_slp_reduc_chain (loop_vec_info vinfo,
       if (!gimple_extract_op (STMT_VINFO_STMT (vect_orig_stmt (stmt)), &op))
 	gcc_unreachable ();
       if (CONVERT_EXPR_CODE_P (op.code)
+	  && tree_nop_conversion_p (op.type, TREE_TYPE (op.ops[0]))
 	  && (first
 	      || is_a <gphi *> (STMT_VINFO_STMT (next_stmt))))
 	;