C#: Deprecate member predicate Definition.getAReadAtNode.

Author: aschackmull

csharp/ql/lib/semmle/code/csharp/controlflow/Guards.qll

@@ -586,7 +586,7 @@ private Ssa::Definition getAnSsaQualifier(Expr e, ControlFlowNode cfn) {
 }
 
 private AssignableAccess getATrackedAccess(Ssa::Definition def, ControlFlowNode cfn) {
-  result = def.getAReadAtNode(cfn)
+  result = def.getARead() and cfn = result.getControlFlowNode()
   or
   result = def.(Ssa::ExplicitDefinition).getADefinition().getTargetAccess() and
   cfn = def.getControlFlowNode()

csharp/ql/lib/semmle/code/csharp/dataflow/Nullness.qll

@@ -124,11 +124,9 @@ private predicate nonNullDef(Ssa::ExplicitDefinition def) {
 }
 
 /**
- * Holds if `node` is a dereference `d` of SSA definition `def`.
+ * Holds if `d` is a dereference of SSA definition `def`.
  */
-private predicate dereferenceAt(ControlFlowNode node, Ssa::Definition def, Dereference d) {
-  d = def.getAReadAtNode(node)
-}
+private predicate dereferenceAt(Ssa::Definition def, Dereference d) { d = def.getARead() }
 
 private predicate isMaybeNullArgument(Ssa::ImplicitParameterDefinition def, MaybeNullExpr arg) {
   exists(AssignableDefinitions::ImplicitParameterDefinition pdef, Parameter p |
@@ -228,7 +226,7 @@ private predicate defMaybeNull(Ssa::Definition def, ControlFlowNode node, string
     )
     or
     // A variable of nullable type may be null
-    exists(Dereference d | dereferenceAt(_, def, d) |
+    exists(Dereference d | dereferenceAt(def, d) |
       node = def.getControlFlowNode() and
       d.hasNullableType() and
       not def instanceof Ssa::PhiNode and
@@ -268,7 +266,8 @@ private module NullnessConfig implements ControlFlowReachability::ConfigSig {
 
   predicate sink(ControlFlowNode node, SsaDefinition def) {
     exists(Dereference d |
-      dereferenceAt(node, def, d) and
+      dereferenceAt(def, d) and
+      node = d.getControlFlowNode() and
       not d instanceof NonNullExpr
     )
   }
@@ -285,7 +284,8 @@ predicate maybeNullDeref(Dereference d, Ssa::SourceVariable v, string msg, Eleme
     defMaybeNull(origin, src, msg, reason) and
     NullnessFlow::flow(src, origin, sink, ssa) and
     ssa.getSourceVariable() = v and
-    dereferenceAt(sink, ssa, d) and
+    dereferenceAt(ssa, d) and
+    sink = d.getControlFlowNode() and
     not d.isAlwaysNull(v)
   )
 }

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

@@ -246,9 +246,11 @@ module Ssa {
      * - The reads of `this.Field` on lines 10 and 11 can be reached from the phi
      *   node between lines 9 and 10.
      */
-    final AssignableRead getARead() { result = this.getAReadAtNode(_) }
+    final AssignableRead getARead() { result = SsaImpl::getAReadAtNode(this, _) }
 
     /**
+     * DEPRECATED: Use `getARead()` instead.
+     *
      * Gets a read of the source variable underlying this SSA definition at
      * control flow node `cfn` that can be reached from this SSA definition
      * without passing through any other SSA definitions. Example:
@@ -275,7 +277,7 @@ module Ssa {
      * - The reads of `this.Field` on lines 10 and 11 can be reached from the phi
      *   node between lines 9 and 10.
      */
-    final AssignableRead getAReadAtNode(ControlFlowNode cfn) {
+    deprecated final AssignableRead getAReadAtNode(ControlFlowNode cfn) {
       result = SsaImpl::getAReadAtNode(this, cfn)
     }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/DataFlowPrivate.qll

@@ -253,7 +253,7 @@ module VariableCapture {
     exists(Ssa::Definition def, AssignableDefinition adef |
       LocalFlow::defAssigns(adef, _, _, e1) and
       def.getAnUltimateDefinition().(Ssa::ExplicitDefinition).getADefinition() = adef and
-      exists(def.getAReadAtNode(e2))
+      def.getARead().getControlFlowNode() = e2
     )
   }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/SignAnalysisSpecific.qll

@@ -245,7 +245,7 @@ private module Impl {
     )
   }
 
-  ExprNode getARead(Ssa::Definition v) { exists(v.getAReadAtNode(result)) }
+  ExprNode getARead(Ssa::Definition v) { v.getARead().getControlFlowNode() = result }
 
   Field getField(ExprNode fa) { result = fa.getExpr().(FieldAccess).getTarget() }
 

csharp/ql/lib/semmle/code/csharp/dataflow/internal/rangeanalysis/SsaUtils.qll

@@ -12,13 +12,13 @@ private class ExprNode = ControlFlowNodes::ExprNode;
 /** An SSA variable. */
 class SsaVariable extends Definition {
   /** Gets a read of this SSA variable. */
-  ExprNode getAUse() { exists(this.getAReadAtNode(result)) }
+  ExprNode getAUse() { this.getARead().getControlFlowNode() = result }
 }
 
 /** Gets a node that reads `src` via an SSA explicit definition. */
 ExprNode getAnExplicitDefinitionRead(ExprNode src) {
   exists(ExplicitDefinition def |
-    exists(def.getAReadAtNode(result)) and
+    def.getARead().getControlFlowNode() = result and
     hasChild(def.getElement(), def.getADefinition().getSource(), def.getControlFlowNode(), src)
   )
 }
@@ -27,7 +27,7 @@ ExprNode getAnExplicitDefinitionRead(ExprNode src) {
  * Gets an expression that equals `v - delta`.
  */
 ExprNode ssaRead(Definition v, int delta) {
-  exists(v.getAReadAtNode(result)) and delta = 0
+  v.getARead().getControlFlowNode() = result and delta = 0
   or
   exists(ExprNode::AddOperation add, int d1, ConstantIntegerExpr c |
     result = add and