[clang][dataflow][NFC] Remove obsolete references to ReferenceValue…

… from comments.

`ReferenceValue` was removed in https://reviews.llvm.org/D155922.

Reviewed By: xazax.hun

Differential Revision: https://reviews.llvm.org/D159090

clang/include/clang/Analysis/FlowSensitive/DataflowEnvironment.h

@@ -254,17 +254,10 @@ class Environment {
   /// Requirements:
   ///
   ///  `D` must not already have a storage location in the environment.
-  ///
-  ///  If `D` has reference type, `Loc` must refer directly to the referenced
-  ///  object (if any), not to a `ReferenceValue`, and it is not permitted to
-  ///  later change `Loc` to refer to a `ReferenceValue.`
   void setStorageLocation(const ValueDecl &D, StorageLocation &Loc);
 
   /// Returns the storage location assigned to `D` in the environment, or null
   /// if `D` isn't assigned a storage location in the environment.
-  ///
-  /// Note that if `D` has reference type, the storage location that is returned
-  /// refers directly to the referenced object, not a `ReferenceValue`.
   StorageLocation *getStorageLocation(const ValueDecl &D) const;
 
   /// Assigns `Loc` as the storage location of the glvalue `E` in the
@@ -280,9 +273,6 @@ class Environment {
   /// environment, or null if `E` isn't assigned a storage location in the
   /// environment.
   ///
-  /// If the storage location for `E` is associated with a
-  /// `ReferenceValue RefVal`, returns `RefVal.getReferentLoc()` instead.
-  ///
   /// Requirements:
   ///  `E` must be a glvalue or a `BuiltinType::BuiltinFn`
   StorageLocation *getStorageLocation(const Expr &E) const;
@@ -437,7 +427,6 @@ class Environment {
   /// Requirements:
   ///
   ///  `E` must be a prvalue
-  ///  `Val` must not be a `ReferenceValue`
   ///  If `Val` is a `RecordValue`, its `RecordStorageLocation` must be the
   ///  same as that of any `RecordValue` that has already been associated with
   ///  `E`. This is to guarantee that the result object initialized by a prvalue

clang/include/clang/Analysis/FlowSensitive/Value.h

@@ -83,8 +83,8 @@ class Value {
 /// transitivity. It does *not* include comparison of `Properties`.
 ///
 /// Computes equivalence for these subclasses:
-/// * ReferenceValue, PointerValue -- pointee locations are equal. Does not
-///   compute deep equality of `Value` at said location.
+/// * PointerValue -- pointee locations are equal. Does not compute deep
+///   equality of `Value` at said location.
 /// * TopBoolValue -- both are `TopBoolValue`s.
 ///
 /// Otherwise, falls back to pointer equality.

clang/lib/Analysis/FlowSensitive/Transfer.cpp

@@ -276,8 +276,7 @@ class TransferVisitor : public ConstStmtVisitor<TransferVisitor> {
 
     case CK_LValueToRValue: {
       // When an L-value is used as an R-value, it may result in sharing, so we
-      // need to unpack any nested `Top`s. We also need to strip off the
-      // `ReferenceValue` associated with the lvalue.
+      // need to unpack any nested `Top`s.
       auto *SubExprVal = maybeUnpackLValueExpr(*SubExpr, Env);
       if (SubExprVal == nullptr)
         break;

clang/unittests/Analysis/FlowSensitive/TypeErasedDataflowAnalysisTest.cpp

@@ -153,9 +153,9 @@ TEST(DataflowAnalysisTest, NonConvergingAnalysis) {
 
 // Regression test for joins of bool-typed lvalue expressions. The first loop
 // results in two passes through the code that follows. Each pass results in a
-// different `ReferenceValue` for the pointee of `v`. Then, the second loop
+// different `StorageLocation` for the pointee of `v`. Then, the second loop
 // causes a join at the loop head where the two environments map expresssion
-// `*v` to different `ReferenceValue`s.
+// `*v` to different `StorageLocation`s.
 //
 // An earlier version crashed for this condition (for boolean-typed lvalues), so
 // this test only verifies that the analysis runs successfully, without