8345158: IGV: local scheduling should not place successors before predecessors

Reviewed-by: rcastanedalo, chagedorn

Author: danielogh

src/utils/IdealGraphVisualizer/ServerCompiler/src/main/java/com/sun/hotspot/igv/servercompiler/ServerCompilerScheduler.java

@@ -382,7 +382,7 @@ private void scheduleLocal() {
     };
 
     private List<InputNode> scheduleBlock(Collection<Node> nodes) {
-        List<InputNode> schedule = new ArrayList<>();
+        LinkedHashSet<InputNode> schedule = new LinkedHashSet<InputNode>();
 
         // Initialize ready priority queue with nodes without predecessors.
         Queue<Node> ready = new PriorityQueue<>(schedulePriority);
@@ -407,7 +407,7 @@ private List<InputNode> scheduleBlock(Collection<Node> nodes) {
                 }
                 boolean allPredsScheduled = true;
                 for (Node p : s.preds) {
-                    if (!visited.contains(p)) {
+                    if (!schedule.contains(p.inputNode)) {
                         allPredsScheduled = false;
                         break;
                     }
@@ -419,7 +419,7 @@ private List<InputNode> scheduleBlock(Collection<Node> nodes) {
             }
         }
         assert(schedule.size() == nodes.size());
-        return schedule;
+        return new ArrayList<InputNode>(schedule);
     }
 
     // Return latest block that dominates all successors of n, or null if any