SSA: Update input to use member predicates.

python/ql/lib/semmle/python/Flow.qll

@@ -1082,9 +1082,15 @@ class BasicBlock extends @py_flow_node {
    * Dominance frontier of a node x is the set of all nodes `other` such that `this` dominates a predecessor
    * of `other` but does not strictly dominate `other`
    */
-  pragma[noinline]
-  predicate dominanceFrontier(BasicBlock other) {
-    this.dominates(other.getAPredecessor()) and not this.strictlyDominates(other)
+  predicate dominanceFrontier(BasicBlock other) { this.inDominanceFrontier(other) }
+
+  predicate inDominanceFrontier(BasicBlock df) {
+    this = df.getAPredecessor() and not this = df.getImmediateDominator()
+    or
+    exists(BasicBlock prev | prev.inDominanceFrontier(df) |
+      this = prev.getImmediateDominator() and
+      not this = df.getImmediateDominator()
+    )
   }
 
   private ControlFlowNode firstNode() { result = this }

python/ql/lib/semmle/python/dataflow/new/internal/VariableCapture.qll

@@ -23,7 +23,9 @@ private module CaptureInput implements Shared::InputSig<Location> {
     predicate isConstructor() { none() }
   }
 
-  class BasicBlock extends PY::BasicBlock {
+  final private class PyBasicBlock = PY::BasicBlock;
+
+  class BasicBlock extends PyBasicBlock {
     int length() { result = count(int i | exists(this.getNode(i))) }
 
     Callable getEnclosingCallable() { result = this.getScope() }
@@ -34,14 +36,16 @@ private module CaptureInput implements Shared::InputSig<Location> {
     // and we just need a way to identify the basic block
     // during debugging, so this will be serviceable.
     Location getLocation() { result = super.getNode(0).getLocation() }
+
+    BasicBlock getASuccessor() { result = super.getASuccessor() }
+
+    BasicBlock getImmediateDominator() { result = super.getImmediateDominator() }
+
+    predicate inDominanceFrontier(BasicBlock df) { super.inDominanceFrontier(df) }
   }
 
   class ControlFlowNode = PY::ControlFlowNode;
 
-  BasicBlock getImmediateBasicBlockDominator(BasicBlock bb) { result = bb.getImmediateDominator() }
-
-  BasicBlock getABasicBlockSuccessor(BasicBlock bb) { result = bb.getASuccessor() }
-
   class CapturedVariable extends LocalVariable {
     Function f;