8287840: Dead copy region node blocks IfNode's fold-compares

Reviewed-by: kvn, thartmann

Author: Xin Liu

src/hotspot/share/opto/node.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1216,6 +1216,9 @@ bool Node::has_special_unique_user() const {
   } else if (is_If() && (n->is_IfFalse() || n->is_IfTrue())) {
     // See IfProjNode::Identity()
     return true;
+  } else if ((is_IfFalse() || is_IfTrue()) && n->is_If()) {
+    // See IfNode::fold_compares
+    return true;
   } else {
     return false;
   }