[DAG] Fix typos in comments; NFC

llvm/include/llvm/CodeGen/SelectionDAG.h

@@ -1613,10 +1613,10 @@ class SelectionDAG {
   /// Expand the specified \c ISD::VACOPY node as the Legalize pass would.
   SDValue expandVACopy(SDNode *Node);
 
-  /// Returs an GlobalAddress of the function from the current module with
+  /// Return a GlobalAddress of the function from the current module with
   /// name matching the given ExternalSymbol. Additionally can provide the
   /// matched function.
-  /// Panics the function doesn't exists.
+  /// Panic if the function doesn't exist.
   SDValue getSymbolFunctionGlobalAddress(SDValue Op,
                                          Function **TargetFunction = nullptr);
 
@@ -2255,7 +2255,7 @@ class SelectionDAG {
   std::pair<EVT, EVT> GetDependentSplitDestVTs(const EVT &VT, const EVT &EnvVT,
                                                bool *HiIsEmpty) const;
 
-  /// Split the vector with EXTRACT_SUBVECTOR using the provides
+  /// Split the vector with EXTRACT_SUBVECTOR using the provided
   /// VTs and return the low/high part.
   std::pair<SDValue, SDValue> SplitVector(const SDValue &N, const SDLoc &DL,
                                           const EVT &LoVT, const EVT &HiVT);