diff -Nurp a/gcc/testsuite/gcc.dg/torture/pr92252.c b/gcc/testsuite/gcc.dg/torture/pr92252.c
--- a/gcc/testsuite/gcc.dg/torture/pr92252.c	1970-01-01 08:00:00.000000000 +0800
+++ b/gcc/testsuite/gcc.dg/torture/pr92252.c	2020-07-03 10:39:44.808000000 +0800
@@ -0,0 +1,23 @@
+/* { do-do compile } */
+/* { dg-additional-options "-ftree-vectorize" } */
+
+long int ar;
+int dt;
+
+long int
+pc (unsigned long int q3, int zw)
+{
+  long int em = 0;
+
+  while (zw < 1)
+    {
+      q3 = zw * 2ul;
+      if (q3 != 0)
+        for (ar = 0; ar < 2; ++ar)
+          em = dt;
+
+      ++zw;
+    }
+
+  return em;
+}
diff -Nurp a/gcc/tree-vect-slp.c b/gcc/tree-vect-slp.c
--- a/gcc/tree-vect-slp.c	2020-07-03 10:35:59.876000000 +0800
+++ b/gcc/tree-vect-slp.c	2020-07-03 10:39:44.808000000 +0800
@@ -581,6 +581,10 @@ again:
 	    {
 	      swap_ssa_operands (stmt, gimple_assign_rhs2_ptr (stmt),
 				 gimple_assign_rhs3_ptr (stmt));
+	      if (STMT_VINFO_REDUC_IDX (stmt_info) == 1)
+		STMT_VINFO_REDUC_IDX (stmt_info) = 2;
+	      else if (STMT_VINFO_REDUC_IDX (stmt_info) == 2)
+		STMT_VINFO_REDUC_IDX (stmt_info) = 1;
 	      bool honor_nans = HONOR_NANS (TREE_OPERAND (cond, 0));
 	      code = invert_tree_comparison (TREE_CODE (cond), honor_nans);
 	      gcc_assert (code != ERROR_MARK);