C++: Use the new predicates in IR dataflow.

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowPrivate.qll

@@ -29,9 +29,7 @@ private class PrimaryArgumentNode extends ArgumentNode {
   PrimaryArgumentNode() { exists(CallInstruction call | op = call.getAnArgumentOperand()) }
 
   override predicate argumentOf(DataFlowCall call, int pos) {
-    op = call.getPositionalArgumentOperand(pos)
-    or
-    op = call.getThisArgumentOperand() and pos = -1
+    op = call.getPositionalOrThisArgumentOperand(pos)
   }
 
   override string toString() {
@@ -110,10 +108,10 @@ class ReturnIndirectionNode extends ReturnNode {
   override ReturnIndirectionInstruction primary;
 
   override ReturnKind getKind() {
-    result = TIndirectReturnKind(-1) and
-    primary.isThisIndirection()
-    or
-    result = TIndirectReturnKind(primary.getParameter().getIndex())
+    exists(int index |
+      primary.isParameterOrThisIndirection(index) and
+      result = TIndirectReturnKind(index)
+    )
   }
 }
 

cpp/ql/src/semmle/code/cpp/ir/dataflow/internal/DataFlowUtil.qll

@@ -266,10 +266,8 @@ class ParameterIndirectionNode extends ParameterNode {
 
   override predicate isParameterOf(Function f, int pos) {
     exists(int index |
-      f.getParameter(index) = instr.getParameter()
-      or
-      index = -1 and
-      instr.getIRVariable().(IRThisVariable).getEnclosingFunction() = f
+      instr.getEnclosingFunction() = f and
+      instr.isParameterOrQualifierIndex(index)
     |
       pos = getArgumentPosOfSideEffect(index)
     )
@@ -476,16 +474,8 @@ class DefinitionByReferenceNode extends InstructionNode {
       instr
           .getPrimaryInstruction()
           .(CallInstruction)
-          .getPositionalArgument(instr.getIndex())
+          .getPositionalOrThisArgument(instr.getIndex())
           .getUnconvertedResultExpression()
-    or
-    result =
-      instr
-          .getPrimaryInstruction()
-          .(CallInstruction)
-          .getThisArgument()
-          .getUnconvertedResultExpression() and
-    instr.getIndex() = -1
   }
 
   /** Gets the parameter through which this value is assigned. */