C#: Fix bad join-orders following stats update

csharp/ql/src/semmle/code/cil/DataFlow.qll

@@ -165,14 +165,16 @@ module DefUse {
     (
       exists(int last | last = max(refRank(bb, _, v, _)) | defReachesRank(bb, vu, last, v))
       or
-      exists(BasicBlock pred |
-        pred = bb.getAPredecessor() and
-        defReachesEndOfBlock(pred, vu, v) and
-        not exists(refRank(bb, _, v, Write()))
-      )
+      defReachesStartOfBlock(bb, vu, v) and
+      not exists(refRank(bb, _, v, Write()))
     )
   }
 
+  pragma[noinline]
+  private predicate defReachesStartOfBlock(BasicBlock bb, VariableUpdate vu, StackVariable v) {
+    defReachesEndOfBlock(bb.getAPredecessor(), vu, v)
+  }
+
   /**
    * Holds if the variable update `vu` of stack variable `v` reaches `read` in the
    * same basic block without crossing another update of `v`.

csharp/ql/src/semmle/code/csharp/dataflow/SSA.qll

@@ -1130,7 +1130,7 @@ module Ssa {
         exists(Expr mid | reachesDelegateCall(mid) | delegateFlowStep(e, mid))
       }
 
-      pragma[noinline]
+      pragma[nomagic]
       private predicate delegateFlowStepReaches(Expr pred, Expr succ) {
         delegateFlowStep(pred, succ) and
         reachesDelegateCall(succ)