[MLIR][NFC] Simplex::restoreRow: improve documentation

mlir/include/mlir/Analysis/Presburger/Simplex.h

@@ -310,8 +310,8 @@ private:
 
   /// Restore the unknown to a non-negative sample value.
   ///
-  /// Returns true if the unknown was successfully restored to a non-negative
-  /// sample value, false otherwise.
+  /// Returns success if the unknown was successfully restored to a non-negative
+  /// sample value, failure otherwise.
   LogicalResult restoreRow(Unknown &u);
 
   /// Compute the maximum or minimum of the specified Unknown, depending on

mlir/lib/Analysis/Presburger/Simplex.cpp

@@ -259,8 +259,8 @@ void Simplex::pivot(unsigned pivotRow, unsigned pivotCol) {
 }
 
 /// Perform pivots until the unknown has a non-negative sample value or until
-/// no more upward pivots can be performed. Return the sign of the final sample
-/// value.
+/// no more upward pivots can be performed. Return success if we were able to
+/// bring the row to a non-negative sample value, and failure otherwise.
 LogicalResult Simplex::restoreRow(Unknown &u) {
   assert(u.orientation == Orientation::Row &&
          "unknown should be in row position");