1 files changed, 19 insertions, 23 deletions

diff --git a/src/System.Private.CoreLib/shared/System/String.Manipulation.cs b/src/System.Private.CoreLib/shared/System/String.Manipulation.cs
index 9ea2ef0f0..3da96bb3b 100644
--- a/src/System.Private.CoreLib/shared/System/String.Manipulation.cs
+++ b/src/System.Private.CoreLib/shared/System/String.Manipulation.cs
@@ -897,7 +897,7 @@ namespace System
             return result;
         }
 
-        // a remove that just takes a startindex. 
+        // a remove that just takes a startindex.
         public string Remove(int startIndex)
         {
             if (startIndex < 0)
@@ -919,16 +919,12 @@ namespace System
             switch (comparisonType)
             {
                 case StringComparison.CurrentCulture:
-                    return ReplaceCore(oldValue, newValue, CultureInfo.CurrentCulture, CompareOptions.None);
-
                 case StringComparison.CurrentCultureIgnoreCase:
-                    return ReplaceCore(oldValue, newValue, CultureInfo.CurrentCulture, CompareOptions.IgnoreCase);
+                    return ReplaceCore(oldValue, newValue, CultureInfo.CurrentCulture, GetCaseCompareOfComparisonCulture(comparisonType));
 
                 case StringComparison.InvariantCulture:
-                    return ReplaceCore(oldValue, newValue, CultureInfo.InvariantCulture, CompareOptions.None);
-
                 case StringComparison.InvariantCultureIgnoreCase:
-                    return ReplaceCore(oldValue, newValue, CultureInfo.InvariantCulture, CompareOptions.IgnoreCase);
+                    return ReplaceCore(oldValue, newValue, CultureInfo.InvariantCulture, GetCaseCompareOfComparisonCulture(comparisonType));
 
                 case StringComparison.Ordinal:
                     return Replace(oldValue, newValue);
@@ -1140,7 +1136,7 @@ namespace System
                 int count = replacementIdx - thisIdx;
                 if (count != 0)
                 {
-                    this.AsSpan().Slice(thisIdx, count).CopyTo(dstSpan.Slice(dstIdx));
+                    this.AsSpan(thisIdx, count).CopyTo(dstSpan.Slice(dstIdx));
                     dstIdx += count;
                 }
                 thisIdx = replacementIdx + oldValueLength;
@@ -1152,7 +1148,7 @@ namespace System
 
             // Copy over the final non-matching portion at the end of the string.
             Debug.Assert(this.Length - thisIdx == dstSpan.Length - dstIdx);
-            this.AsSpan().Slice(thisIdx).CopyTo(dstSpan.Slice(dstIdx));
+            this.AsSpan(thisIdx).CopyTo(dstSpan.Slice(dstIdx));
 
             return dst;
         }
@@ -1252,7 +1248,7 @@ namespace System
                 return new string[] { this };
             }
 
-            string[] result = omitEmptyEntries 
+            string[] result = omitEmptyEntries
                 ? SplitOmitEmptyEntries(sepList, default, 1, count)
                 : SplitKeepEmptyEntries(sepList, default, 1, count);
 
@@ -1266,7 +1262,7 @@ namespace System
             return SplitInternal(separator ?? string.Empty, null, int.MaxValue, options);
         }
 
-        public string[] Split(string separator, Int32 count, StringSplitOptions options = StringSplitOptions.None)
+        public string[] Split(string separator, int count, StringSplitOptions options = StringSplitOptions.None)
         {
             return SplitInternal(separator ?? string.Empty, null, count, options);
         }
@@ -1276,7 +1272,7 @@ namespace System
             return SplitInternal(null, separator, int.MaxValue, options);
         }
 
-        public string[] Split(string[] separator, Int32 count, StringSplitOptions options)
+        public string[] Split(string[] separator, int count, StringSplitOptions options)
         {
             return SplitInternal(null, separator, count, options);
         }
@@ -1317,7 +1313,7 @@ namespace System
             {
                 return SplitInternal(separator, count, options);
             }
-            
+
             Span<int> sepListInitialSpan = stackalloc int[StackallocIntBufferSizeLimit];
             var sepListBuilder = new ValueListBuilder<int>(sepListInitialSpan);
 
@@ -1327,14 +1323,14 @@ namespace System
             MakeSeparatorList(separators, ref sepListBuilder, ref lengthListBuilder);
             ReadOnlySpan<int> sepList = sepListBuilder.AsSpan();
             ReadOnlySpan<int> lengthList = lengthListBuilder.AsSpan();
-            
+
             // Handle the special case of no replaces.
             if (sepList.Length == 0)
             {
                 return new string[] { this };
             }
 
-            string[] result = omitEmptyEntries 
+            string[] result = omitEmptyEntries
                 ? SplitOmitEmptyEntries(sepList, lengthList, 0, count)
                 : SplitKeepEmptyEntries(sepList, lengthList, 0, count);
 
@@ -1357,7 +1353,7 @@ namespace System
                 return new string[] { this };
             }
 
-            string[] result = options == StringSplitOptions.RemoveEmptyEntries 
+            string[] result = options == StringSplitOptions.RemoveEmptyEntries
                 ? SplitOmitEmptyEntries(sepList, default, separator.Length, count)
                 : SplitKeepEmptyEntries(sepList, default, separator.Length, count);
 
@@ -1402,15 +1398,15 @@ namespace System
         }
 
 
-        // This function will not keep the Empty string 
+        // This function will not keep the Empty string
         private string[] SplitOmitEmptyEntries(ReadOnlySpan<int> sepList, ReadOnlySpan<int> lengthList, int defaultLength, int count)
         {
             Debug.Assert(count >= 2);
 
             int numReplaces = sepList.Length;
 
-            // Allocate array to hold items. This array may not be 
-            // filled completely in this function, we will create a 
+            // Allocate array to hold items. This array may not be
+            // filled completely in this function, we will create a
             // new array and copy string references to that new array.
             int maxItems = (numReplaces < count) ? (numReplaces + 1) : count;
             string[] splitStrings = new string[maxItems];
@@ -1557,7 +1553,7 @@ namespace System
                 if (this[i] == separator[0] && currentSepLength <= Length - i)
                 {
                     if (currentSepLength == 1
-                        || CompareOrdinal(this, i, separator, 0, currentSepLength) == 0)
+                        || this.AsSpan(i, currentSepLength).SequenceEqual(separator))
                     {
                         sepListBuilder.Append(i);
                         i += currentSepLength - 1;
@@ -1571,7 +1567,7 @@ namespace System
         /// </summary>
         /// <param name="separators">separator strngs</param>
         /// <param name="sepListBuilder"><see cref="ValueListBuilder{T}"/> for separator indexes</param>
-        /// <param name="lengthListBuilder"><see cref="ValueListBuilder{T}"/> for separator length values</param>        
+        /// <param name="lengthListBuilder"><see cref="ValueListBuilder{T}"/> for separator length values</param>
         private void MakeSeparatorList(string[] separators, ref ValueListBuilder<int> sepListBuilder, ref ValueListBuilder<int> lengthListBuilder)
         {
             Debug.Assert(separators != null && separators.Length > 0, "separators != null && separators.Length > 0");
@@ -1591,7 +1587,7 @@ namespace System
                     if (this[i] == separator[0] && currentSepLength <= Length - i)
                     {
                         if (currentSepLength == 1
-                            || CompareOrdinal(this, i, separator, 0, currentSepLength) == 0)
+                            || this.AsSpan(i, currentSepLength).SequenceEqual(separator))
                         {
                             sepListBuilder.Append(i);
                             lengthListBuilder.Append(currentSepLength);
@@ -1702,7 +1698,7 @@ namespace System
         }
 
         // Trims the whitespace from both ends of the string.  Whitespace is defined by
-        // Char.IsWhiteSpace.
+        // char.IsWhiteSpace.
         //
         public string Trim() => TrimWhiteSpaceHelper(TrimType.Both);