Rename the method FloorLog2 to be more clear & fix spelling (#25335) (#15349)

Author: Zhukov Maxim

src/mscorlib/src/System/Array.cs

@@ -1915,7 +1915,7 @@ private void IntrospectiveSort(int left, int length)
 
                 try
                 {
-                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length));
+                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
                 }
                 catch (IndexOutOfRangeException)
                 {
@@ -2121,7 +2121,7 @@ private void IntrospectiveSort(int left, int length)
 
                 try
                 {
-                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length));
+                    IntroSort(left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
                 }
                 catch (IndexOutOfRangeException)
                 {

src/mscorlib/src/System/Collections/Generic/ArraySortHelper.cs

@@ -32,11 +32,11 @@ internal interface IArraySortHelper<TKey>
     internal static class IntrospectiveSortUtilities
     {
         // This is the threshold where Introspective sort switches to Insertion sort.
-        // Imperically, 16 seems to speed up most cases without slowing down others, at least for integers.
+        // Empirically, 16 seems to speed up most cases without slowing down others, at least for integers.
         // Large value types may benefit from a smaller number.
         internal const int IntrosortSizeThreshold = 16;
 
-        internal static int FloorLog2(int n)
+        internal static int FloorLog2PlusOne(int n)
         {
             int result = 0;
             while (n >= 1)
@@ -213,7 +213,7 @@ internal static void IntrospectiveSort(T[] keys, int left, int length, Compariso
             if (length < 2)
                 return;
 
-            IntroSort(keys, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length), comparer);
+            IntroSort(keys, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length), comparer);
         }
 
         private static void IntroSort(T[] keys, int lo, int hi, int depthLimit, Comparison<T> comparer)
@@ -500,7 +500,7 @@ internal static void IntrospectiveSort(T[] keys, int left, int length)
             if (length < 2)
                 return;
 
-            IntroSort(keys, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length));
+            IntroSort(keys, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
         }
 
         private static void IntroSort(T[] keys, int lo, int hi, int depthLimit)
@@ -778,7 +778,7 @@ internal static void IntrospectiveSort(TKey[] keys, TValue[] values, int left, i
             if (length < 2)
                 return;
 
-            IntroSort(keys, values, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length), comparer);
+            IntroSort(keys, values, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length), comparer);
         }
 
         private static void IntroSort(TKey[] keys, TValue[] values, int lo, int hi, int depthLimit, IComparer<TKey> comparer)
@@ -1027,7 +1027,7 @@ internal static void IntrospectiveSort(TKey[] keys, TValue[] values, int left, i
             if (length < 2)
                 return;
 
-            IntroSort(keys, values, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2(keys.Length));
+            IntroSort(keys, values, left, length + left - 1, 2 * IntrospectiveSortUtilities.FloorLog2PlusOne(keys.Length));
         }
 
         private static void IntroSort(TKey[] keys, TValue[] values, int lo, int hi, int depthLimit)