[GR-47479] [GR-47477] Add GraphUtil.unproxifyExceptLoopProxies helper

PullRequest: graal/15099

Author: gergo-

compiler/src/jdk.internal.vm.compiler/src/org/graalvm/compiler/nodes/util/GraphUtil.java

@@ -688,6 +688,22 @@ public static ValueNode unproxify(ValueProxy value) {
  }
  }
 
+ /**
+ * Gets the original value by iterating through all {@link ValueProxy value proxies}, except
+ * {@link ProxyNode ProxyNodes}. That is, this method looks through pi nodes, value anchors,
+ * etc., but it does not enter loops.
+ *
+ * @param original the start value
+ * @return the first non-proxy or loop proxy value encountered
+ */
+ public static ValueNode unproxifyExceptLoopProxies(ValueNode original) {
+ ValueNode node = original;
+ while (node instanceof ValueProxy proxy && !(node instanceof ProxyNode)) {
+ node = proxy.getOriginalNode();
+ }
+ return node;
+ }
+
  public static ValueNode skipPi(ValueNode node) {
  ValueNode n = node;
  while (n instanceof PiNode) {