[llvm] Use std::nullopt instead of None in comments (NFC)

This is part of an effort to migrate from llvm::Optional to
std::optional:

https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716

1 files changed, 6 insertions, 7 deletions

diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 3d9fd56..074af66 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -270,8 +270,8 @@ private:
   /// MDNode, compute and return the mapping.  If it's a distinct \a MDNode,
   /// return the result of \a mapDistinctNode().
   ///
-  /// \return None if \c Op is an unmapped uniqued \a MDNode.
-  /// \post getMappedOp(Op) only returns None if this returns None.
+  /// \return std::nullopt if \c Op is an unmapped uniqued \a MDNode.
+  /// \post getMappedOp(Op) only returns std::nullopt if this returns None.
   Optional<Metadata *> tryToMapOperand(const Metadata *Op);
 
   /// Map a distinct node.
@@ -317,11 +317,10 @@ private:
   /// This visits all the nodes in \c G in post-order, using the identity
   /// mapping or creating a new node depending on \a Data::HasChanged.
   ///
-  /// \pre \a getMappedOp() returns None for nodes in \c G, but not for any of
-  /// their operands outside of \c G.
-  /// \pre \a Data::HasChanged is true for a node in \c G iff any of its
-  /// operands have changed.
-  /// \post \a getMappedOp() returns the mapped node for every node in \c G.
+  /// \pre \a getMappedOp() returns std::nullopt for nodes in \c G, but not for
+  /// any of their operands outside of \c G. \pre \a Data::HasChanged is true
+  /// for a node in \c G iff any of its operands have changed. \post \a
+  /// getMappedOp() returns the mapped node for every node in \c G.
   void mapNodesInPOT(UniquedGraph &G);
 
   /// Remap a node's operands using the given functor.