Dataflow: Simplify branch and join.

Author: aschackmull

shared/dataflow/codeql/dataflow/internal/DataFlowImpl.qll

@@ -1156,12 +1156,11 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
      * contexts.
      */
     pragma[nomagic]
-    private int branch(NodeEx n1) {
+    private int branch(ArgNodeEx n1) {
       result =
         strictcount(DataFlowCallable c |
             exists(NodeEx n |
-              flowOutOfCallNodeCand1(_, n1, _, n) or flowIntoCallNodeCand1(_, n1, n)
-            |
+              flowIntoCallNodeCand1(_, n1, n) and
               c = n.getEnclosingCallable()
             )
           ) + sum(ParamNodeEx p1 | | getLanguageSpecificFlowIntoCallNodeCand1(n1, p1))
@@ -1173,12 +1172,11 @@ module MakeImpl<LocationSig Location, InputSig<Location> Lang> {
      * contexts.
      */
     pragma[nomagic]
-    private int join(NodeEx n2) {
+    private int join(ParamNodeEx n2) {
       result =
         strictcount(DataFlowCallable c |
             exists(NodeEx n |
-              flowOutOfCallNodeCand1(_, n, _, n2) or flowIntoCallNodeCand1(_, n, n2)
-            |
+              flowIntoCallNodeCand1(_, n, n2) and
               c = n.getEnclosingCallable()
             )
           ) + sum(ArgNodeEx arg2 | | getLanguageSpecificFlowIntoCallNodeCand1(arg2, n2))