Do not allocate 0-length Node[] arrays

Author: Christian Wimmer

compiler/src/org.graalvm.compiler.graph/src/org/graalvm/compiler/graph/NodeList.java

@@ -76,7 +76,11 @@ protected NodeList(Node self, int initialSize) {
         checkMaxSize(initialSize);
         this.size = initialSize;
         this.initialSize = initialSize;
-        this.nodes = new Node[initialSize];
+        if (initialSize == 0) {
+            this.nodes = EMPTY_NODE_ARRAY;
+        } else {
+            this.nodes = new Node[initialSize];
+        }
     }
 
     protected NodeList(Node self, T[] elements) {
@@ -232,8 +236,13 @@ public void initialize(int index, Node node) {
     void copy(NodeList<? extends Node> other) {
         self.incModCount();
         incModCount();
-        Node[] newNodes = new Node[other.size];
-        System.arraycopy(other.nodes, 0, newNodes, 0, newNodes.length);
+        Node[] newNodes;
+        if (other.size == 0) {
+            newNodes = EMPTY_NODE_ARRAY;
+        } else {
+            newNodes = new Node[other.size];
+            System.arraycopy(other.nodes, 0, newNodes, 0, newNodes.length);
+        }
         nodes = newNodes;
         size = other.size;
     }