Java: Fix performance issue in type flow library

java/ql/lib/semmle/code/java/dataflow/TypeFlow.qll

@@ -72,6 +72,35 @@ module FlowStepsInput implements UniversalFlow::UniversalFlowInput<Location> {
     }
   }
 
+  private class FlowNodeElement extends Element {
+    FlowNodeElement() {
+      this instanceof Field or
+      this instanceof Expr or
+      this instanceof Method
+    }
+  }
+
+  private predicate id(FlowNodeElement x, FlowNodeElement y) { x = y }
+
+  private predicate idOf(FlowNodeElement x, int y) = equivalenceRelation(id/2)(x, y)
+
+  int getFlowNodeId(FlowNode n) {
+    n =
+      rank[result](FlowNode n0, int a, int b |
+        a = 0 and
+        idOf(any(n0.asField()), b)
+        or
+        // no case for `n0.asSsa()`; here we rely on the built-in location-based ranking
+        a = 1 and
+        idOf(any(n0.asExpr()), b)
+        or
+        a = 2 and
+        idOf(any(n0.asMethod()), b)
+      |
+        n0 order by a, b
+      )
+  }
+
   private SrcCallable viableCallable_v1(Call c) {
     result = viableImpl_v1(c)
     or
@@ -165,6 +194,8 @@ private module Input implements TypeFlowInput<Location> {
 
   class TypeFlowNode = FlowNode;
 
+  predicate getTypeFlowNodeId = FlowStepsInput::getFlowNodeId/1;
+
   predicate isExcludedFromNullAnalysis = FlowStepsInput::isExcludedFromNullAnalysis/1;
 
   class Type = RefType;

java/ql/lib/semmle/code/java/security/ListOfConstantsSanitizer.qll

@@ -170,6 +170,8 @@ private class EmptyCollectionConstructor extends Constructor {
 private module CollectionFlowStepsInput implements UniversalFlow::UniversalFlowInput<Location> {
   import FlowStepsInput
 
+  predicate getFlowNodeId = FlowStepsInput::getFlowNodeId/1;
+
   /**
    * Holds if `n2` is a collection/array/constant whose value(s) are
    * determined completely from the range of `n1` nodes.