vincent-coder0119
diff --git a/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/MS/Internal/MarkupCompiler/MarkupCompiler.cs
Lines changed: 5 additions & 12 deletions b/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/MS/Internal/MarkupCompiler/MarkupCompiler.cs
Lines changed: 5 additions & 12 deletions
diff --git a/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/MS/Internal/MarkupCompiler/NETFrameworkGetRelativePath.cs
Lines changed: 17 additions & 7 deletions b/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/MS/Internal/MarkupCompiler/NETFrameworkGetRelativePath.cs
Lines changed: 17 additions & 7 deletions
diff --git a/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/PresentationBuildTasks.csproj
Lines changed: 1 addition & 0 deletions b/‎src/Microsoft.DotNet.Wpf/src/PresentationBuildTasks/PresentationBuildTasks.csproj
Lines changed: 1 addition & 0 deletions
@@ -1568,19 +1568,12 @@ private string ParentFolderPrefix
         {
             get
             {
-                string parentFolderPrefix = string.Empty;
-                if (TargetPath.StartsWith(SourceFileInfo.SourcePath, StringComparison.OrdinalIgnoreCase))
-                {
-                    string relPath = TargetPath.Substring(SourceFileInfo.SourcePath.Length);
-                    relPath += SourceFileInfo.RelativeSourceFilePath;
-                    string[] dirs = relPath.Split(new Char[] { ESCAPED_BACKSLASH_CHAR });
-                    for (int i = 1; i < dirs.Length; i++)
-                    {
-                        parentFolderPrefix += PARENTFOLDER;
-                    }
-                }
+#if NETFX && !NETCOREAPP
+                return PathInternal.GetRelativePath(TargetPath, SourceFileInfo.SourcePath, StringComparison.OrdinalIgnoreCase);
+#else
 
-                return parentFolderPrefix;
+                return Path.GetRelativePath(TargetPath, SourceFileInfo.SourcePath);
+#endif
             }
         }
 
 
@@ -273,20 +273,30 @@ internal static int GetRootLength(ReadOnlySpan<char> path)
         /// <summary>
         /// Gets the count of common characters from the left optionally ignoring case
         /// </summary>
-        internal static int EqualStartingCharacterCount(string first, string second, bool ignoreCase)
+        internal static unsafe int EqualStartingCharacterCount(string first, string second, bool ignoreCase)
         {
             if (string.IsNullOrEmpty(first) || string.IsNullOrEmpty(second)) return 0;
 
-            // Current index
-            int index = 0; 
+            int commonChars = 0;
 
-            while (index != first.Length && index != second.Length &&
-                    first[index] == second[index] || (ignoreCase && char.ToUpperInvariant(first[index]) == char.ToUpperInvariant(second[index])))
+            fixed (char* f = first)
+            fixed (char* s = second)
             {
-               index++;
+                char* l = f;
+                char* r = s;
+                char* leftEnd = l + first.Length;
+                char* rightEnd = r + second.Length;
+
+                while (l != leftEnd && r != rightEnd
+                    && (*l == *r || (ignoreCase && char.ToUpperInvariant((*l)) == char.ToUpperInvariant((*r)))))
+                {
+                    commonChars++;
+                    l++;
+                    r++;
+                }
             }
 
-            return index;
+            return commonChars;
         }
 
             /// <summary>
 
@@ -27,6 +27,7 @@
     <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
     <GenerateBindingRedirectsOutputType>true</GenerateBindingRedirectsOutputType>
     <Platforms>AnyCPU;x64</Platforms>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemDefinitionGroup Condition="'$(CopyTransitiveReferences)'=='true'">
Original file line number	Diff line number	Diff line change
`@@ -1568,19 +1568,12 @@ private string ParentFolderPrefix`
`1568`	`1568`	`{`
`1569`	`1569`	`get`
`1570`	`1570`	`{`
`1571`		`- string parentFolderPrefix = string.Empty;`
`1572`		`- if (TargetPath.StartsWith(SourceFileInfo.SourcePath, StringComparison.OrdinalIgnoreCase))`
`1573`		`- {`
`1574`		`- string relPath = TargetPath.Substring(SourceFileInfo.SourcePath.Length);`
`1575`		`- relPath += SourceFileInfo.RelativeSourceFilePath;`
`1576`		`- string[] dirs = relPath.Split(new Char[] { ESCAPED_BACKSLASH_CHAR });`
`1577`		`- for (int i = 1; i < dirs.Length; i++)`
`1578`		`- {`
`1579`		`- parentFolderPrefix += PARENTFOLDER;`
`1580`		`- }`
`1581`		`- }`
	`1571`	`+#if NETFX && !NETCOREAPP`
	`1572`	`+ return PathInternal.GetRelativePath(TargetPath, SourceFileInfo.SourcePath, StringComparison.OrdinalIgnoreCase);`
	`1573`	`+#else`
`1582`	`1574`
`1583`		`- return parentFolderPrefix;`
	`1575`	`+ return Path.GetRelativePath(TargetPath, SourceFileInfo.SourcePath);`
	`1576`	`+#endif`
`1584`	`1577`	`}`
`1585`	`1578`	`}`
`1586`	`1579`