Imported Upstream version 2.0.0.11353upstream/2.0.0.11353

47 files changed, 230 insertions, 1131 deletions

diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/AccessedThroughPropertyAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/AccessedThroughPropertyAttribute.cs
deleted file mode 100644
index 34e66beade..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/AccessedThroughPropertyAttribute.cs
+++ /dev/null
@@ -1,30 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-//------------------------------------------------------------------------------
-//------------------------------------------------------------------------------
-namespace System.Runtime.CompilerServices 
-{
-    using System;
-
-    [AttributeUsage(AttributeTargets.Field)]
-    public sealed class AccessedThroughPropertyAttribute : Attribute
-    {
-        private readonly string propertyName;
-
-        public AccessedThroughPropertyAttribute(string propertyName)
-        {
-            this.propertyName = propertyName;
-        }
-
-        public string PropertyName 
-        {
-            get 
-            {
-                return propertyName;
-            }
-        }
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/AssemblySettingAttributes.cs b/src/mscorlib/src/System/Runtime/CompilerServices/AssemblySettingAttributes.cs
deleted file mode 100644
index 5251122629..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/AssemblySettingAttributes.cs
+++ /dev/null
@@ -1,94 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-////////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////////
-
-namespace System.Runtime.CompilerServices 
-{
-
-    using System;
-    using System.Runtime.InteropServices;
-
-    /*
-    NGenHint is not supported in Whidbey     
-
-    [Serializable]
-    public enum NGenHint
-    {    
-        Default             = 0x0000, // No preference specified
-        
-        Eager               = 0x0001, // NGen at install time
-        Lazy                = 0x0002, // NGen after install time
-        Never               = 0x0003, // Assembly should not be ngened      
-    }
-    */
-
-    [Serializable]
-    public enum LoadHint
-    {
-        Default             = 0x0000, // No preference specified
-        
-        Always              = 0x0001, // Dependency is always loaded
-        Sometimes           = 0x0002, // Dependency is sometimes loaded
-        //Never               = 0x0003, // Dependency is never loaded
-    }
-
-    [Serializable]
-    [AttributeUsage(AttributeTargets.Assembly)]  
-    public sealed class DefaultDependencyAttribute : Attribute 
-    {
-        private LoadHint loadHint;
-    
-        public DefaultDependencyAttribute (
-            LoadHint loadHintArgument
-            )
-        {
-            loadHint = loadHintArgument;
-        }  
-    
-        public LoadHint LoadHint
-        {
-            get
-            {
-                return loadHint;
-            }
-        }       
-    } 
-
-
-[Serializable]
-[AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]  
-    public sealed class DependencyAttribute : Attribute 
-    {
-        private String                dependentAssembly;
-        private LoadHint              loadHint;
-
-        public DependencyAttribute (
-            String   dependentAssemblyArgument,
-            LoadHint loadHintArgument
-            )
-        {
-            dependentAssembly     = dependentAssemblyArgument;
-            loadHint              = loadHintArgument;
-        }
-        
-        public String DependentAssembly
-        {
-            get
-            {
-                return dependentAssembly;
-            }
-        }       
-
-        public LoadHint LoadHint
-        {
-            get
-            {
-                return loadHint;
-            }
-        }       
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/AsyncMethodBuilder.cs b/src/mscorlib/src/System/Runtime/CompilerServices/AsyncMethodBuilder.cs
index afb0c22778..fc7a7f01a3 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/AsyncMethodBuilder.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/AsyncMethodBuilder.cs
@@ -63,7 +63,7 @@ namespace System.Runtime.CompilerServices
             // See comment on AsyncMethodBuilderCore.Start
             // AsyncMethodBuilderCore.Start(ref stateMachine);
 
-            if (stateMachine == null) throw new ArgumentNullException(nameof(stateMachine));
+            if (stateMachine == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.stateMachine);
             Contract.EndContractBlock();
 
             // Run the MoveNext method within a copy-on-write ExecutionContext scope.
@@ -72,7 +72,6 @@ namespace System.Runtime.CompilerServices
 
             Thread currentThread = Thread.CurrentThread;
             ExecutionContextSwitcher ecs = default(ExecutionContextSwitcher);
-            RuntimeHelpers.PrepareConstrainedRegions();
             try
             {
                 ExecutionContext.EstablishCopyOnWriteScope(currentThread, ref ecs);
@@ -240,15 +239,8 @@ namespace System.Runtime.CompilerServices
             }
         }
 
-        // This property lazily instantiates the Task in a non-thread-safe manner.  
-        private Task Task 
-        {
-            get
-            {
-                if (m_task == null) m_task = new Task();
-                return m_task;
-            }
-        }
+        /// <summary>Lazily instantiate the Task in a non-thread-safe manner.</summary>
+        private Task Task => m_task ?? (m_task = new Task());
 
         /// <summary>
         /// Gets an object that may be used to uniquely identify this builder to the debugger.
@@ -295,7 +287,7 @@ namespace System.Runtime.CompilerServices
             // See comment on AsyncMethodBuilderCore.Start
             // AsyncMethodBuilderCore.Start(ref stateMachine);
 
-            if (stateMachine == null) throw new ArgumentNullException(nameof(stateMachine));
+            if (stateMachine == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.stateMachine);
             Contract.EndContractBlock();
 
             // Run the MoveNext method within a copy-on-write ExecutionContext scope.
@@ -304,7 +296,6 @@ namespace System.Runtime.CompilerServices
 
             Thread currentThread = Thread.CurrentThread;
             ExecutionContextSwitcher ecs = default(ExecutionContextSwitcher);
-            RuntimeHelpers.PrepareConstrainedRegions();
             try
             {
                 ExecutionContext.EstablishCopyOnWriteScope(currentThread, ref ecs);
@@ -358,7 +349,11 @@ namespace System.Runtime.CompilerServices
         /// <summary>Gets the <see cref="System.Threading.Tasks.Task"/> for this builder.</summary>
         /// <returns>The <see cref="System.Threading.Tasks.Task"/> representing the builder's asynchronous operation.</returns>
         /// <exception cref="System.InvalidOperationException">The builder is not initialized.</exception>
-        public Task Task { get { return m_builder.Task; } }
+        public Task Task
+        {
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get { return m_builder.Task; }
+        }
 
         /// <summary>
         /// Completes the <see cref="System.Threading.Tasks.Task"/> in the 
@@ -449,7 +444,7 @@ namespace System.Runtime.CompilerServices
             // See comment on AsyncMethodBuilderCore.Start
             // AsyncMethodBuilderCore.Start(ref stateMachine);
 
-            if (stateMachine == null) throw new ArgumentNullException(nameof(stateMachine));
+            if (stateMachine == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.stateMachine);
             Contract.EndContractBlock();
 
             // Run the MoveNext method within a copy-on-write ExecutionContext scope.
@@ -458,7 +453,6 @@ namespace System.Runtime.CompilerServices
 
             Thread currentThread = Thread.CurrentThread;
             ExecutionContextSwitcher ecs = default(ExecutionContextSwitcher);
-            RuntimeHelpers.PrepareConstrainedRegions();
             try
             {
                 ExecutionContext.EstablishCopyOnWriteScope(currentThread, ref ecs);
@@ -502,7 +496,7 @@ namespace System.Runtime.CompilerServices
                 {
                     // Force the Task to be initialized prior to the first suspending await so 
                     // that the original stack-based builder has a reference to the right Task.
-                    var builtTask = this.Task;
+                    Task builtTask = this.Task;
 
                     // Box the state machine, then tell the boxed instance to call back into its own builder,
                     // so we can cache the boxed reference. NOTE: The language compiler may choose to use
@@ -542,7 +536,7 @@ namespace System.Runtime.CompilerServices
                 {
                     // Force the Task to be initialized prior to the first suspending await so 
                     // that the original stack-based builder has a reference to the right Task.
-                    var builtTask = this.Task;
+                    Task<TResult> builtTask = this.Task;
 
                     // Box the state machine, then tell the boxed instance to call back into its own builder,
                     // so we can cache the boxed reference. NOTE: The language compiler may choose to use
@@ -563,15 +557,14 @@ namespace System.Runtime.CompilerServices
         /// <returns>The <see cref="System.Threading.Tasks.Task{TResult}"/> representing the builder's asynchronous operation.</returns>
         public Task<TResult> Task
         {
-            get
-            {
-                // Get and return the task. If there isn't one, first create one and store it.
-                var task = m_task;
-                if (task == null) { m_task = task = new Task<TResult>(); }
-                return task;
-            }
+            [MethodImpl(MethodImplOptions.AggressiveInlining)]
+            get { return m_task ?? InitializeTask(); }
         }
 
+        /// <summary>Initializes the task, which must not yet be initialized.</summary>
+        [MethodImpl(MethodImplOptions.NoInlining)]
+        private Task<TResult> InitializeTask() => (m_task = new Task<TResult>());
+
         /// <summary>
         /// Completes the <see cref="System.Threading.Tasks.Task{TResult}"/> in the 
         /// <see cref="System.Threading.Tasks.TaskStatus">RanToCompletion</see> state with the specified result.
@@ -582,28 +575,49 @@ namespace System.Runtime.CompilerServices
         {
             // Get the currently stored task, which will be non-null if get_Task has already been accessed.
             // If there isn't one, get a task and store it.
-            var task = m_task;
-            if (task == null)
+            if (m_task == null)
             {
                 m_task = GetTaskForResult(result);
                 Debug.Assert(m_task != null, "GetTaskForResult should never return null");
             }
-            // Slow path: complete the existing task.
             else
             {
-                if (AsyncCausalityTracer.LoggingOn)
-                    AsyncCausalityTracer.TraceOperationCompletion(CausalityTraceLevel.Required, task.Id, AsyncCausalityStatus.Completed);
+                // Slow path: complete the existing task.
+                SetExistingTaskResult(result);
+            }
+        }
 
-                //only log if we have a real task that was previously created
-                if (System.Threading.Tasks.Task.s_asyncDebuggingEnabled)
-                {
-                    System.Threading.Tasks.Task.RemoveFromActiveTasks(task.Id);
-                }
+        /// <summary>Completes the already initialized task with the specified result.</summary>
+        /// <param name="result">The result to use to complete the task.</param>
+        private void SetExistingTaskResult(TResult result)
+        {
+            Debug.Assert(m_task != null, "Expected non-null task");
 
-                if (!task.TrySetResult(result))
-                {
-                    throw new InvalidOperationException(Environment.GetResourceString("TaskT_TransitionToFinal_AlreadyCompleted"));
-                }
+            if (AsyncCausalityTracer.LoggingOn || System.Threading.Tasks.Task.s_asyncDebuggingEnabled)
+            {
+                LogExistingTaskCompletion();
+            }
+
+            if (!m_task.TrySetResult(result))
+            {
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.TaskT_TransitionToFinal_AlreadyCompleted);
+            }
+        }
+
+        /// <summary>Handles logging for the successful completion of an operation.</summary>
+        private void LogExistingTaskCompletion()
+        {
+            Debug.Assert(m_task != null);
+
+            if (AsyncCausalityTracer.LoggingOn)
+            {
+                AsyncCausalityTracer.TraceOperationCompletion(CausalityTraceLevel.Required, m_task.Id, AsyncCausalityStatus.Completed);
+            }
+
+            // only log if we have a real task that was previously created
+            if (System.Threading.Tasks.Task.s_asyncDebuggingEnabled)
+            {
+                System.Threading.Tasks.Task.RemoveFromActiveTasks(m_task.Id);
             }
         }
 
@@ -620,15 +634,14 @@ namespace System.Runtime.CompilerServices
 
             // Get the currently stored task, which will be non-null if get_Task has already been accessed.
             // If there isn't one, store the supplied completed task.
-            var task = m_task;
-            if (task == null)
+            if (m_task == null)
             {
                 m_task = completedTask;
             }
             else
             {
                 // Otherwise, complete the task that's there.
-                SetResult(default(TResult));
+                SetExistingTaskResult(default(TResult));
             }
         }
 
@@ -667,7 +680,7 @@ namespace System.Runtime.CompilerServices
 
             if (!successfullySet)
             {
-                throw new InvalidOperationException(Environment.GetResourceString("TaskT_TransitionToFinal_AlreadyCompleted"));
+                ThrowHelper.ThrowInvalidOperationException(ExceptionResource.TaskT_TransitionToFinal_AlreadyCompleted);
             }
         }
 
@@ -704,6 +717,7 @@ namespace System.Runtime.CompilerServices
         /// </summary>
         /// <param name="result">The result for which we need a task.</param>
         /// <returns>The completed task containing the result.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)] // method looks long, but for a given TResult it results in a relatively small amount of asm
         private Task<TResult> GetTaskForResult(TResult result)
         {
             Contract.Ensures(
@@ -846,9 +860,9 @@ namespace System.Runtime.CompilerServices
         /// <exception cref="System.InvalidOperationException">The builder is incorrectly initialized.</exception>
         public void SetStateMachine(IAsyncStateMachine stateMachine)
         {
-            if (stateMachine == null) throw new ArgumentNullException(nameof(stateMachine));
+            if (stateMachine == null) ThrowHelper.ThrowArgumentNullException(ExceptionArgument.stateMachine);
             Contract.EndContractBlock();
-            if (m_stateMachine != null) throw new InvalidOperationException(Environment.GetResourceString("AsyncMethodBuilder_InstanceNotInitialized"));
+            if (m_stateMachine != null) ThrowHelper.ThrowInvalidOperationException(ExceptionResource.AsyncMethodBuilder_InstanceNotInitialized);
             m_stateMachine = stateMachine;
         }
 
@@ -1104,12 +1118,12 @@ namespace System.Runtime.CompilerServices
             return action;
         }
 
-    ///<summary>
-    /// Given an action, see if it is a contiunation wrapper and has a Task associated with it.  If so return it (null otherwise)
-    ///</summary>
+        ///<summary>
+        /// Given an action, see if it is a contiunation wrapper and has a Task associated with it.  If so return it (null otherwise)
+        ///</summary>
         internal static Task TryGetContinuationTask(Action action)
         {
-            if (action != null) 
+            if (action != null)
             {
                 var asWrapper = action.Target as ContinuationWrapper;
                 if (asWrapper != null)
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/AsyncStateMachineAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/AsyncStateMachineAttribute.cs
deleted file mode 100644
index f1fc9ced82..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/AsyncStateMachineAttribute.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
-    public sealed class AsyncStateMachineAttribute : StateMachineAttribute
-    {
-        public AsyncStateMachineAttribute(Type stateMachineType)
-            : base(stateMachineType)
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CallerFilePathAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CallerFilePathAttribute.cs
deleted file mode 100644
index 330934cf95..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CallerFilePathAttribute.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
-    public sealed class CallerFilePathAttribute : Attribute
-    {
-        public CallerFilePathAttribute()
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CallerLineNumberAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CallerLineNumberAttribute.cs
deleted file mode 100644
index 9c87e8e25f..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CallerLineNumberAttribute.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
-    public sealed class CallerLineNumberAttribute : Attribute
-    {
-        public CallerLineNumberAttribute()
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CallerMemberNameAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CallerMemberNameAttribute.cs
deleted file mode 100644
index 4fc70908fb..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CallerMemberNameAttribute.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [AttributeUsage(AttributeTargets.Parameter, Inherited = false)]
-    public sealed class CallerMemberNameAttribute : Attribute
-    {
-        public CallerMemberNameAttribute()
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CompilationRelaxations.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CompilationRelaxations.cs
deleted file mode 100644
index c3679b610c..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CompilationRelaxations.cs
+++ /dev/null
@@ -1,50 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-////////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////////
-
-namespace System.Runtime.CompilerServices 
-{
-
-    using System;
-
-    /// IMPORTANT: Keep this in sync with corhdr.h
-[Serializable]
-[Flags]
-    public enum CompilationRelaxations : int
-    { 
-        NoStringInterning       = 0x0008, // Start in 0x0008, we had other non public flags in this enum before,
-                                          // so we'll start here just in case somebody used them. This flag is only
-                                          // valid when set for Assemblies.
-    };
-        
-[Serializable]
-[AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Module | AttributeTargets.Class | AttributeTargets.Method)]  
-    public class CompilationRelaxationsAttribute : Attribute 
-    {
-        private int m_relaxations;      // The relaxations.
-        
-        public CompilationRelaxationsAttribute (
-            int relaxations) 
-        { 
-            m_relaxations = relaxations; 
-        }
-        
-        public CompilationRelaxationsAttribute (
-            CompilationRelaxations relaxations) 
-        { 
-            m_relaxations = (int) relaxations; 
-        }
-        
-        public int CompilationRelaxations
-        { 
-            get 
-            { 
-                return m_relaxations; 
-            } 
-        }
-    }
-    
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGeneratedAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGeneratedAttribute.cs
deleted file mode 100644
index 1778506c7c..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGeneratedAttribute.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-////////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////////
-namespace System.Runtime.CompilerServices {
-
-[Serializable]
-[AttributeUsage(AttributeTargets.All, Inherited = true)]
-    public sealed class CompilerGeneratedAttribute : Attribute
-    {
-        public CompilerGeneratedAttribute () {}
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGlobalScopeAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGlobalScopeAttribute.cs
deleted file mode 100644
index 1cd830cfca..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerGlobalScopeAttribute.cs
+++ /dev/null
@@ -1,26 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-/*============================================================
-**
-**
-**
-** Purpose: Attribute used to communicate to the VS7 debugger
-**          that a class should be treated as if it has
-**          global scope.
-**
-** 
-===========================================================*/
-    
-
-namespace System.Runtime.CompilerServices
-{
-    [Serializable]
-    [AttributeUsage(AttributeTargets.Class)]
-    public class CompilerGlobalScopeAttribute : Attribute
-    {
-       public CompilerGlobalScopeAttribute () {}
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerMarshalOverride.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CompilerMarshalOverride.cs
deleted file mode 100644
index a7b4aca480..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CompilerMarshalOverride.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices
-{
-    // The CLR data marshaler has some behaviors that are incompatible with
-    // C++. Specifically, C++ treats boolean variables as byte size, whereas 
-    // the marshaller treats them as 4-byte size.  Similarly, C++ treats
-    // wchar_t variables as 4-byte size, whereas the marshaller treats them
-    // as single byte size under certain conditions.  In order to work around
-    // such issues, the C++ compiler will emit a type that the marshaller will
-    // marshal using the correct sizes.  In addition, the compiler will place
-    // this modopt onto the variables to indicate that the specified type is
-    // not the true type.  Any compiler that needed to deal with similar
-    // marshalling incompatibilities could use this attribute as well.
-    //
-    // Indicates that the modified instance differs from its true type for
-    // correct marshalling.
-    public static class CompilerMarshalOverride
-    {
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs
index 4b2648ba6f..f32cc2b510 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs
@@ -61,6 +61,7 @@
 
 using System.Collections;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Threading;
 
@@ -164,7 +165,6 @@ namespace System.Runtime.CompilerServices
                 {
                     CreateEntry(key, value);
                 }
-
             }
         }
 
@@ -797,7 +797,7 @@ namespace System.Runtime.CompilerServices
                 }
 
                 return Resize(newSize);
-            }            
+            }
 
             internal Container Resize(int newSize)
             {
@@ -974,7 +974,7 @@ namespace System.Runtime.CompilerServices
             {
                 if (_invalid)
                 {
-                    throw new InvalidOperationException(Environment.GetResourceString("CollectionCorrupted"));
+                    throw new InvalidOperationException(SR.InvalidOperation_CollectionCorrupted);
                 }
             }
 
@@ -1114,7 +1114,7 @@ namespace System.Runtime.CompilerServices
             {
                 IntPtr handle = _handle;
                 _handle = (IntPtr)0;
-                 nFree(handle);
+                nFree(handle);
             }
         }
         #endregion
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/CustomConstantAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/CustomConstantAttribute.cs
index 1a5dcfdc11..8f4c79cd94 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/CustomConstantAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/CustomConstantAttribute.cs
@@ -8,7 +8,7 @@ using System.Collections.Generic;
 namespace System.Runtime.CompilerServices
 {
     [Serializable]
-    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited=false)]
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited = false)]
     public abstract class CustomConstantAttribute : Attribute
     {
         public abstract Object Value { get; }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs
index 148d916be1..7aca42b627 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/DateTimeConstantAttribute.cs
@@ -8,7 +8,7 @@ using System.Diagnostics.Contracts;
 namespace System.Runtime.CompilerServices
 {
     [Serializable]
-    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited=false)]
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited = false)]
     public sealed class DateTimeConstantAttribute : CustomConstantAttribute
     {
         public DateTimeConstantAttribute(long ticks)
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/DecimalConstantAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/DecimalConstantAttribute.cs
index f05191840d..0e2b6f8418 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/DecimalConstantAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/DecimalConstantAttribute.cs
@@ -13,7 +13,7 @@ using System.Collections.Generic;
 namespace System.Runtime.CompilerServices
 {
     [Serializable]
-    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited=false)]
+    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter, Inherited = false)]
     public sealed class DecimalConstantAttribute : Attribute
     {
         [CLSCompliant(false)]
@@ -25,7 +25,7 @@ namespace System.Runtime.CompilerServices
             uint low
         )
         {
-            dec = new System.Decimal((int) low, (int)mid, (int)hi, (sign != 0), scale);
+            dec = new System.Decimal((int)low, (int)mid, (int)hi, (sign != 0), scale);
         }
 
         public DecimalConstantAttribute(
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/DisablePrivateReflectionAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/DisablePrivateReflectionAttribute.cs
deleted file mode 100644
index 46dae10fdd..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/DisablePrivateReflectionAttribute.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-//------------------------------------------------------------------------------
-//------------------------------------------------------------------------------
-
-namespace System.Runtime.CompilerServices
-{
-    using System;
-
-    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=false, Inherited=false)]
-    public sealed class DisablePrivateReflectionAttribute : Attribute
-    {
-        public DisablePrivateReflectionAttribute() {}
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/DiscardableAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/DiscardableAttribute.cs
deleted file mode 100644
index 3fda4624d4..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/DiscardableAttribute.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-////////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////////
-namespace System.Runtime.CompilerServices {
-
-    using System;
-
-    // Custom attribute to indicating a TypeDef is a discardable attribute
-    public class DiscardableAttribute : Attribute
-    {
-        public DiscardableAttribute()
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ExtensionAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ExtensionAttribute.cs
deleted file mode 100644
index 6ec8fa04f5..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ExtensionAttribute.cs
+++ /dev/null
@@ -1,13 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// Indicates that a method is an extension method, or that a class or assembly contains extension methods.
-    /// </summary>
-    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly)]
-    public sealed class ExtensionAttribute : Attribute { }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/FixedAddressValueTypeAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/FixedAddressValueTypeAttribute.cs
deleted file mode 100644
index 679e304ad1..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/FixedAddressValueTypeAttribute.cs
+++ /dev/null
@@ -1,14 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices 
-{    
-    using System;
-    
-[Serializable]
-[AttributeUsage(AttributeTargets.Field)]  
-    sealed public class FixedAddressValueTypeAttribute : Attribute 
-    {        
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/FixedBufferAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/FixedBufferAttribute.cs
deleted file mode 100644
index a7d01b12c4..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/FixedBufferAttribute.cs
+++ /dev/null
@@ -1,43 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-/*============================================================
-**
-**
-** Purpose: Used by a compiler for generating value types
-**   in-place within other value types containing a certain
-**   number of elements of the given (primitive) type.  Somewhat
-**   similar to P/Invoke's ByValTStr attribute.
-**   Used by C# with this syntax: "fixed int buffer[10];"
-**
-===========================================================*/
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [AttributeUsage(AttributeTargets.Field, Inherited=false)]
-    public sealed class FixedBufferAttribute : Attribute
-    {
-        private Type elementType;
-        private int length;
-
-        public FixedBufferAttribute(Type elementType, int length)
-        {
-            this.elementType = elementType;
-            this.length = length;
-        }
-
-        public Type ElementType {
-            get {
-                return elementType;
-            }
-        }
-
-        public int Length {
-            get {
-                return length;
-            }
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/FormattableStringFactory.cs b/src/mscorlib/src/System/Runtime/CompilerServices/FormattableStringFactory.cs
deleted file mode 100644
index 4b99a8a5d9..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/FormattableStringFactory.cs
+++ /dev/null
@@ -1,58 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-/*============================================================
-**
-** Class:  FormattableStringFactory
-**
-**
-** Purpose: implementation of the FormattableStringFactory
-** class.
-**
-===========================================================*/
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// A factory type used by compilers to create instances of the type <see cref="FormattableString"/>.
-    /// </summary>
-    public static class FormattableStringFactory
-    {
-        /// <summary>
-        /// Create a <see cref="FormattableString"/> from a composite format string and object
-        /// array containing zero or more objects to format.
-        /// </summary>
-        public static FormattableString Create(string format, params object[] arguments)
-        {
-            if (format == null)
-            {
-                throw new ArgumentNullException(nameof(format));
-            }
-
-            if (arguments == null)
-            {
-                throw new ArgumentNullException(nameof(arguments));
-            }
-
-            return new ConcreteFormattableString(format, arguments);
-        }
-
-        private sealed class ConcreteFormattableString : FormattableString
-        {
-            private readonly string _format;
-            private readonly object[] _arguments;
-
-            internal ConcreteFormattableString(string format, object[] arguments)
-            {
-                _format = format;
-                _arguments = arguments;
-            }
-
-            public override string Format { get { return _format; } }
-            public override object[] GetArguments() { return _arguments; }
-            public override int ArgumentCount { get { return _arguments.Length; } }
-            public override object GetArgument(int index) { return _arguments[index]; }
-            public override string ToString(IFormatProvider formatProvider) { return string.Format(formatProvider, _format, _arguments); }
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/InternalsVisibleToAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/FriendAccessAllowedAttribute.cs
index ee7807a5dd..9d380e1070 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/InternalsVisibleToAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/FriendAccessAllowedAttribute.cs
@@ -2,40 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-//------------------------------------------------------------------------------
-//------------------------------------------------------------------------------
-
 namespace System.Runtime.CompilerServices
 {
-    using System;
-
-
-    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=true, Inherited=false)]
-    public sealed class InternalsVisibleToAttribute : Attribute
-    {
-        private string _assemblyName;
-        private bool _allInternalsVisible = true;
-
-        public InternalsVisibleToAttribute(string assemblyName)
-        {
-            this._assemblyName = assemblyName;
-        }
-
-        public string AssemblyName 
-        {
-            get 
-            {
-                return _assemblyName;
-            }
-        }
-
-        public bool AllInternalsVisible
-        {
-            get { return _allInternalsVisible; }
-            set { _allInternalsVisible = value; }
-        }
-    }
-
     /// <summary>
     ///     If AllInternalsVisible is not true for a friend assembly, the FriendAccessAllowed attribute
     ///     indicates which internals are shared with that friend assembly.
@@ -52,7 +20,7 @@ namespace System.Runtime.CompilerServices
         AllowMultiple = false,
         Inherited = false)]
     [FriendAccessAllowed]
-    internal sealed class FriendAccessAllowedAttribute : Attribute {
+    internal sealed class FriendAccessAllowedAttribute : Attribute
+    {
     }
 }
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/IAsyncStateMachine.cs b/src/mscorlib/src/System/Runtime/CompilerServices/IAsyncStateMachine.cs
deleted file mode 100644
index 7fb7ea5395..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/IAsyncStateMachine.cs
+++ /dev/null
@@ -1,27 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
-//
-//
-//
-// Represents state machines generated for asynchronous methods.
-//
-// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
-
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// Represents state machines generated for asynchronous methods.
-    /// This type is intended for compiler use only.
-    /// </summary>
-    public interface IAsyncStateMachine
-    {
-        /// <summary>Moves the state machine to its next state.</summary>
-        void MoveNext();
-        /// <summary>Configures the state machine with a heap-allocated replica.</summary>
-        /// <param name="stateMachine">The heap-allocated replica.</param>
-        void SetStateMachine(IAsyncStateMachine stateMachine);
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
index 7ba9434575..e2b76ed973 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
@@ -61,22 +61,22 @@ namespace System.Runtime.CompilerServices
         // IsInstanceOfInterface.
         RuntimeTypeHandle GetImplType(RuntimeTypeHandle interfaceType);
     }
-    
+
     /// <summary>
     /// Helpers that allows VM to call into ICastable methods without having to deal with RuntimeTypeHandle.
     /// RuntimeTypeHandle is a struct and is always passed in stack in x86, which our VM call helpers don't
     /// particularly like.
     /// </summary>
-    class ICastableHelpers
+    internal class ICastableHelpers
     {
         internal static bool IsInstanceOfInterface(ICastable castable, RuntimeType type, out Exception castError)
         {
             return castable.IsInstanceOfInterface(new RuntimeTypeHandle(type), out castError);
-        }    
-        
+        }
+
         internal static RuntimeType GetImplType(ICastable castable, RuntimeType interfaceType)
         {
-            return castable.GetImplType(new RuntimeTypeHandle(interfaceType)).GetRuntimeType(); 
-        }    
+            return castable.GetImplType(new RuntimeTypeHandle(interfaceType)).GetRuntimeType();
+        }
     }
 }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/INotifyCompletion.cs b/src/mscorlib/src/System/Runtime/CompilerServices/INotifyCompletion.cs
deleted file mode 100644
index aba0a0691f..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/INotifyCompletion.cs
+++ /dev/null
@@ -1,39 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-// =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=
-//
-//
-//
-// Interfaces used to represent instances that notify listeners of their completion via continuations.
-// =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
-
-using System;
-using System.Security;
-
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// Represents an operation that will schedule continuations when the operation completes.
-    /// </summary>
-    public interface INotifyCompletion
-    {
-        /// <summary>Schedules the continuation action to be invoked when the instance completes.</summary>
-        /// <param name="continuation">The action to invoke when the operation completes.</param>
-        /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
-        void OnCompleted(Action continuation);
-    }
-
-    /// <summary>
-    /// Represents an awaiter used to schedule continuations when an await operation completes.
-    /// </summary>
-    public interface ICriticalNotifyCompletion : INotifyCompletion
-    {
-        /// <summary>Schedules the continuation action to be invoked when the instance completes.</summary>
-        /// <param name="continuation">The action to invoke when the operation completes.</param>
-        /// <exception cref="System.ArgumentNullException">The <paramref name="continuation"/> argument is null (Nothing in Visual Basic).</exception>
-        /// <remarks>Unlike OnCompleted, UnsafeOnCompleted need not propagate ExecutionContext information.</remarks>
-        void UnsafeOnCompleted(Action continuation);
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ITuple.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ITuple.cs
deleted file mode 100644
index cafee11f8a..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ITuple.cs
+++ /dev/null
@@ -1,22 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// This interface is required for types that want to be indexed into by dynamic patterns.
-    /// </summary>
-    public interface ITuple
-    {
-        /// <summary>
-        /// The number of positions in this data structure.
-        /// </summary>
-        int Length { get; }
-
-        /// <summary>
-        /// Get the element at position <param name="index"/>.
-        /// </summary>
-        object this[int index] { get; }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/IndexerNameAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/IndexerNameAttribute.cs
deleted file mode 100644
index c32be6f3a2..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/IndexerNameAttribute.cs
+++ /dev/null
@@ -1,16 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices
-{
-    using System;
-
-[Serializable]
-[AttributeUsage(AttributeTargets.Property, Inherited = true)]
-    public sealed class IndexerNameAttribute: Attribute
-    {
-        public IndexerNameAttribute(String indexerName)
-        {}
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/IsVolatile.cs b/src/mscorlib/src/System/Runtime/CompilerServices/IsVolatile.cs
deleted file mode 100644
index 5287e82b7b..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/IsVolatile.cs
+++ /dev/null
@@ -1,12 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices 
-{
-    public static class IsVolatile 
-    {
-        // no instantiation, please!
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/IteratorStateMachineAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/IteratorStateMachineAttribute.cs
deleted file mode 100644
index 4bb9b4eb8f..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/IteratorStateMachineAttribute.cs
+++ /dev/null
@@ -1,18 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
-    public sealed class IteratorStateMachineAttribute : StateMachineAttribute
-    {
-        public IteratorStateMachineAttribute(Type stateMachineType)
-            : base(stateMachineType)
-        {
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/MethodImplAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/MethodImplAttribute.cs
index b4991110f8..b24018cf78 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/MethodImplAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/MethodImplAttribute.cs
@@ -2,72 +2,47 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-namespace System.Runtime.CompilerServices {
-    
-    using System;
-    using System.Reflection;    
-    
+
+using System;
+using System.Reflection;
+
+namespace System.Runtime.CompilerServices
+{
     // This Enum matchs the miImpl flags defined in corhdr.h. It is used to specify 
     // certain method properties.
-    
-    [Serializable]
-    [Flags]
-    public enum MethodImplOptions
-    {
-        Unmanaged          =   System.Reflection.MethodImplAttributes.Unmanaged,
-        ForwardRef         =   System.Reflection.MethodImplAttributes.ForwardRef,
-        PreserveSig        =   System.Reflection.MethodImplAttributes.PreserveSig,
-        InternalCall       =   System.Reflection.MethodImplAttributes.InternalCall,
-        Synchronized       =   System.Reflection.MethodImplAttributes.Synchronized,
-        NoInlining         =   System.Reflection.MethodImplAttributes.NoInlining,
-        AggressiveInlining =   System.Reflection.MethodImplAttributes.AggressiveInlining,
-        NoOptimization     =   System.Reflection.MethodImplAttributes.NoOptimization,
-        // **** If you add something, update internal MethodImplAttribute(MethodImplAttributes methodImplAttributes)! ****
-    }
 
+    // Custom attribute to specify additional method properties.
     [Serializable]
-    public enum MethodCodeType
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, Inherited = false)]
+    sealed public class MethodImplAttribute : Attribute
     {
-        IL              =   System.Reflection.MethodImplAttributes.IL,
-        Native          =   System.Reflection.MethodImplAttributes.Native,
-        /// <internalonly/>
-        OPTIL           =   System.Reflection.MethodImplAttributes.OPTIL,
-        Runtime         =   System.Reflection.MethodImplAttributes.Runtime  
-    }
-
-    // Custom attribute to specify additional method properties.
-[Serializable]
-[AttributeUsage(AttributeTargets.Method | AttributeTargets.Constructor, Inherited = false)] 
-    sealed public class MethodImplAttribute : Attribute  
-    {    
-        internal MethodImplOptions  _val;
-        public   MethodCodeType     MethodCodeType;
+        internal MethodImplOptions _val;
+        public MethodCodeType MethodCodeType;
 
         internal MethodImplAttribute(MethodImplAttributes methodImplAttributes)
         {
-            MethodImplOptions all = 
-                MethodImplOptions.Unmanaged | MethodImplOptions.ForwardRef | MethodImplOptions.PreserveSig | 
+            MethodImplOptions all =
+                MethodImplOptions.Unmanaged | MethodImplOptions.ForwardRef | MethodImplOptions.PreserveSig |
                 MethodImplOptions.InternalCall | MethodImplOptions.Synchronized |
                 MethodImplOptions.NoInlining | MethodImplOptions.AggressiveInlining |
                 MethodImplOptions.NoOptimization;
             _val = ((MethodImplOptions)methodImplAttributes) & all;
         }
-        
+
         public MethodImplAttribute(MethodImplOptions methodImplOptions)
         {
             _val = methodImplOptions;
         }
-        
+
         public MethodImplAttribute(short value)
         {
             _val = (MethodImplOptions)value;
         }
-        
+
         public MethodImplAttribute()
         {
         }
-        
-        public MethodImplOptions Value { get {return _val;} }   
-    }
 
+        public MethodImplOptions Value { get { return _val; } }
+    }
 }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ReferenceAssemblyAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ReferenceAssemblyAttribute.cs
deleted file mode 100644
index d5e64a1177..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ReferenceAssemblyAttribute.cs
+++ /dev/null
@@ -1,39 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-/*============================================================
-**
-** Attribute: ReferenceAssemblyAttribute
-**
-** Purpose: Identifies an assembly as being a "reference 
-**    assembly", meaning it contains public surface area but
-**    no usable implementation.  Reference assemblies 
-**    should be loadable for introspection, but not execution.
-**
-============================================================*/
-namespace System.Runtime.CompilerServices 
-{    
-    using System;
-    
-    [Serializable]
-    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=false)]
-    public sealed class ReferenceAssemblyAttribute : Attribute
-    {
-        private String _description;  // Maybe ".NET FX v4.0 SP1, partial trust"?
-
-        public ReferenceAssemblyAttribute()
-        {
-        }
-
-        public ReferenceAssemblyAttribute(String description)
-        {
-            _description = description;
-        }
-
-        public String Description
-        {
-            get { return _description; }
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeCompatibilityAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeCompatibilityAttribute.cs
deleted file mode 100644
index 40a9b7c568..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeCompatibilityAttribute.cs
+++ /dev/null
@@ -1,48 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-////////////////////////////////////////////////////////////////////////////////
-////////////////////////////////////////////////////////////////////////////////
-/*=============================================================================
-**
-**
-**
-** Purpose: Mark up the program to indicate various legacy or new opt-in behaviors.
-**
-**
-=============================================================================*/
-
-namespace System.Runtime.CompilerServices 
-{
-
-    using System;
-
-[Serializable]
-[AttributeUsage(AttributeTargets.Assembly, Inherited=false, AllowMultiple=false)]
-    public sealed class RuntimeCompatibilityAttribute : Attribute 
-    {
-        // fields
-        private bool m_wrapNonExceptionThrows;
-
-        // constructors
-        public RuntimeCompatibilityAttribute() {
-            // legacy behavior is the default, and m_wrapNonExceptionThrows is implicitly
-            // false thanks to the CLR's guarantee of zeroed memory.
-        }
-
-        // properties
-
-        // If a non-CLSCompliant exception (i.e. one that doesn't derive from System.Exception) is
-        // thrown, should it be wrapped up in a System.Runtime.CompilerServices.RuntimeWrappedException
-        // instance when presented to catch handlers?
-        public bool WrapNonExceptionThrows { 
-            get { 
-                return m_wrapNonExceptionThrows; 
-            }
-            set {
-                m_wrapNonExceptionThrows = value;
-            }
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs b/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs
index 509e527ecb..0338b18bee 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs
@@ -9,8 +9,9 @@
 //    This class defines a set of static methods that provide support for compilers.
 //
 //
-namespace System.Runtime.CompilerServices {
 
+namespace System.Runtime.CompilerServices
+{
     using System;
     using System.Security;
     using System.Runtime;
@@ -32,7 +33,7 @@ namespace System.Runtime.CompilerServices {
         }
 
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
-        public static extern void InitializeArray(Array array,RuntimeFieldHandle fldHandle);
+        public static extern void InitializeArray(Array array, RuntimeFieldHandle fldHandle);
 
         // GetObjectValue is intended to allow value classes to be manipulated as 'Object'
         // but have aliasing behavior of a value class.  The intent is that you would use
@@ -61,7 +62,7 @@ namespace System.Runtime.CompilerServices {
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
         private static extern void _RunClassConstructor(RuntimeType type);
 
-        public static void RunClassConstructor(RuntimeTypeHandle type) 
+        public static void RunClassConstructor(RuntimeTypeHandle type)
         {
             _RunClassConstructor(type.GetRuntimeType());
         }
@@ -77,24 +78,24 @@ namespace System.Runtime.CompilerServices {
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
         private static extern void _RunModuleConstructor(System.Reflection.RuntimeModule module);
 
-        public static void RunModuleConstructor(ModuleHandle module) 
+        public static void RunModuleConstructor(ModuleHandle module)
         {
-           _RunModuleConstructor(module.GetRuntimeModule());
+            _RunModuleConstructor(module.GetRuntimeModule());
         }
 
 
         [DllImport(JitHelpers.QCall, CharSet = CharSet.Unicode), SuppressUnmanagedCodeSecurity]
         internal static extern void _CompileMethod(IRuntimeMethodInfo method);
 
-        public static void PrepareMethod(RuntimeMethodHandle method){}
-        public static void PrepareMethod(RuntimeMethodHandle method, RuntimeTypeHandle[] instantiation){}
-        public static void PrepareContractedDelegate(Delegate d){}
-        
+        public static void PrepareMethod(RuntimeMethodHandle method) { }
+        public static void PrepareMethod(RuntimeMethodHandle method, RuntimeTypeHandle[] instantiation) { }
+        public static void PrepareContractedDelegate(Delegate d) { }
+
         public static void PrepareDelegate(Delegate d)
         {
             if (d == null)
             {
-                throw new ArgumentNullException ("d");
+                throw new ArgumentNullException("d");
             }
         }
 
@@ -108,8 +109,9 @@ namespace System.Runtime.CompilerServices {
         {
             // This offset is baked in by string indexer intrinsic, so there is no harm
             // in getting it baked in here as well.
-            [System.Runtime.Versioning.NonVersionable] 
-            get {
+            [System.Runtime.Versioning.NonVersionable]
+            get
+            {
                 // Number of bytes from the address pointed to by a reference to
                 // a String to the first 16-bit character in the String.  Skip 
                 // over the MethodTable pointer, & String 
@@ -167,6 +169,14 @@ namespace System.Runtime.CompilerServices {
         {
             ((CleanupCode)backoutCode)(userData, exceptionThrown);
         }
+
+        /// <returns>true if given type is reference type or value type that contains references</returns>
+        static public bool IsReferenceOrContainsReferences<T>()
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementation for how this happens.
+            throw new InvalidOperationException();
+        }
     }
 }
 
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeWrappedException.cs b/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeWrappedException.cs
index e3b2d2ce62..c050000169 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeWrappedException.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/RuntimeWrappedException.cs
@@ -11,29 +11,34 @@
 **
 =============================================================================*/
 
-namespace System.Runtime.CompilerServices {
-    using System;
-    using System.Runtime.Serialization;
-    using System.Runtime.Remoting;
-    using System.Diagnostics.Contracts;
-        
+using System;
+using System.Runtime.Serialization;
+using System.Runtime.Remoting;
+using System.Diagnostics.Contracts;
+
+namespace System.Runtime.CompilerServices
+{
     [Serializable]
     public sealed class RuntimeWrappedException : Exception
     {
         private RuntimeWrappedException(Object thrownObject)
-            : base(Environment.GetResourceString("RuntimeWrappedException")) {
-            SetErrorCode(System.__HResults.COR_E_RUNTIMEWRAPPED);
+            : base(SR.RuntimeWrappedException)
+        {
+            HResult = System.__HResults.COR_E_RUNTIMEWRAPPED;
             m_wrappedException = thrownObject;
         }
-    
-        public Object WrappedException {
+
+        public Object WrappedException
+        {
             get { return m_wrappedException; }
         }
 
         private Object m_wrappedException;
 
-        public override void GetObjectData(SerializationInfo info, StreamingContext context) {
-            if (info==null) {
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            if (info == null)
+            {
                 throw new ArgumentNullException(nameof(info));
             }
             Contract.EndContractBlock();
@@ -42,7 +47,8 @@ namespace System.Runtime.CompilerServices {
         }
 
         internal RuntimeWrappedException(SerializationInfo info, StreamingContext context)
-            : base(info, context) {
+            : base(info, context)
+        {
             m_wrappedException = info.GetValue("WrappedException", typeof(Object));
         }
     }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/SpecialNameAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/SpecialNameAttribute.cs
deleted file mode 100644
index 38e5538b44..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/SpecialNameAttribute.cs
+++ /dev/null
@@ -1,27 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-using System.Reflection;
-using System.Runtime.InteropServices;
-
-namespace System.Runtime.CompilerServices 
-{
-    [AttributeUsage(AttributeTargets.Class | 
-                    AttributeTargets.Method |
-                    AttributeTargets.Property |
-                    AttributeTargets.Field |
-                    AttributeTargets.Event |
-                    AttributeTargets.Struct)]
-
-   
-    public sealed class SpecialNameAttribute : Attribute
-    {
-        public SpecialNameAttribute() { }
-    }
-}
-
-
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/StateMachineAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/StateMachineAttribute.cs
deleted file mode 100644
index 7c84009e1f..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/StateMachineAttribute.cs
+++ /dev/null
@@ -1,20 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-
-namespace System.Runtime.CompilerServices
-{
-    [Serializable, AttributeUsage(AttributeTargets.Method, Inherited = false, AllowMultiple = false)]
-    public class StateMachineAttribute : Attribute
-    {
-        public Type StateMachineType { get; private set; }
-
-        public StateMachineAttribute(Type stateMachineType)
-        {
-            this.StateMachineType = stateMachineType;
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/SuppressIldasmAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/SuppressIldasmAttribute.cs
deleted file mode 100644
index eb019eecbf..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/SuppressIldasmAttribute.cs
+++ /dev/null
@@ -1,19 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-//------------------------------------------------------------------------------
-//------------------------------------------------------------------------------
-namespace System.Runtime.CompilerServices 
-{
-    using System;
-
-    [AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Module)]
-    public sealed class SuppressIldasmAttribute : Attribute
-    {
-        public SuppressIldasmAttribute()
-        {
-        }
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/SuppressMergeCheckAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/SuppressMergeCheckAttribute.cs
deleted file mode 100644
index 6bb36c4bf5..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/SuppressMergeCheckAttribute.cs
+++ /dev/null
@@ -1,23 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System.Runtime.InteropServices;
-
-namespace System.Runtime.CompilerServices 
-{
-    [AttributeUsage(AttributeTargets.Class | 
-                    AttributeTargets.Constructor | 
-                    AttributeTargets.Method |
-                    AttributeTargets.Field |
-                    AttributeTargets.Event |
-                    AttributeTargets.Property)]
-
-    internal sealed class SuppressMergeCheckAttribute : Attribute
-    {
-        public SuppressMergeCheckAttribute() 
-        {}  
-    }
-}
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/TaskAwaiter.cs b/src/mscorlib/src/System/Runtime/CompilerServices/TaskAwaiter.cs
index f01900a5bf..e2fa6caa2d 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/TaskAwaiter.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/TaskAwaiter.cs
@@ -72,7 +72,7 @@ namespace System.Runtime.CompilerServices
         /// <summary>Gets whether the task being awaited is completed.</summary>
         /// <remarks>This property is intended for compiler user rather than use directly in code.</remarks>
         /// <exception cref="System.NullReferenceException">The awaiter was not properly initialized.</exception>
-        public bool IsCompleted 
+        public bool IsCompleted
         {
             get { return m_task.IsCompleted; }
         }
@@ -84,7 +84,7 @@ namespace System.Runtime.CompilerServices
         /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
         public void OnCompleted(Action continuation)
         {
-            OnCompletedInternal(m_task, continuation, continueOnCapturedContext:true, flowExecutionContext:true);
+            OnCompletedInternal(m_task, continuation, continueOnCapturedContext: true, flowExecutionContext: true);
         }
 
         /// <summary>Schedules the continuation onto the <see cref="System.Threading.Tasks.Task"/> associated with this <see cref="TaskAwaiter"/>.</summary>
@@ -94,7 +94,7 @@ namespace System.Runtime.CompilerServices
         /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
         public void UnsafeOnCompleted(Action continuation)
         {
-            OnCompletedInternal(m_task, continuation, continueOnCapturedContext:true, flowExecutionContext:false);
+            OnCompletedInternal(m_task, continuation, continueOnCapturedContext: true, flowExecutionContext: false);
         }
 
         /// <summary>Ends the await on the completed <see cref="System.Threading.Tasks.Task"/>.</summary>
@@ -240,7 +240,7 @@ namespace System.Runtime.CompilerServices
                 etwLog.TaskWaitBegin(
                     (currentTaskAtBegin != null ? currentTaskAtBegin.m_taskScheduler.Id : TaskScheduler.Default.Id),
                     (currentTaskAtBegin != null ? currentTaskAtBegin.Id : 0),
-                    task.Id, TplEtwProvider.TaskWaitBehavior.Asynchronous, 
+                    task.Id, TplEtwProvider.TaskWaitBehavior.Asynchronous,
                     (continuationTask != null ? continuationTask.Id : 0));
             }
 
@@ -303,7 +303,7 @@ namespace System.Runtime.CompilerServices
         /// <summary>Gets whether the task being awaited is completed.</summary>
         /// <remarks>This property is intended for compiler user rather than use directly in code.</remarks>
         /// <exception cref="System.NullReferenceException">The awaiter was not properly initialized.</exception>
-        public bool IsCompleted 
+        public bool IsCompleted
         {
             get { return m_task.IsCompleted; }
         }
@@ -315,7 +315,7 @@ namespace System.Runtime.CompilerServices
         /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
         public void OnCompleted(Action continuation)
         {
-            TaskAwaiter.OnCompletedInternal(m_task, continuation, continueOnCapturedContext:true, flowExecutionContext:true);
+            TaskAwaiter.OnCompletedInternal(m_task, continuation, continueOnCapturedContext: true, flowExecutionContext: true);
         }
 
         /// <summary>Schedules the continuation onto the <see cref="System.Threading.Tasks.Task"/> associated with this <see cref="TaskAwaiter"/>.</summary>
@@ -325,7 +325,7 @@ namespace System.Runtime.CompilerServices
         /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
         public void UnsafeOnCompleted(Action continuation)
         {
-            TaskAwaiter.OnCompletedInternal(m_task, continuation, continueOnCapturedContext:true, flowExecutionContext:false);
+            TaskAwaiter.OnCompletedInternal(m_task, continuation, continueOnCapturedContext: true, flowExecutionContext: false);
         }
 
         /// <summary>Ends the await on the completed <see cref="System.Threading.Tasks.Task{TResult}"/>.</summary>
@@ -390,7 +390,7 @@ namespace System.Runtime.CompilerServices
             /// <summary>Gets whether the task being awaited is completed.</summary>
             /// <remarks>This property is intended for compiler user rather than use directly in code.</remarks>
             /// <exception cref="System.NullReferenceException">The awaiter was not properly initialized.</exception>
-            public bool IsCompleted 
+            public bool IsCompleted
             {
                 get { return m_task.IsCompleted; }
             }
@@ -402,7 +402,7 @@ namespace System.Runtime.CompilerServices
             /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
             public void OnCompleted(Action continuation)
             {
-                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext:true);
+                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext: true);
             }
 
             /// <summary>Schedules the continuation onto the <see cref="System.Threading.Tasks.Task"/> associated with this <see cref="TaskAwaiter"/>.</summary>
@@ -412,7 +412,7 @@ namespace System.Runtime.CompilerServices
             /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
             public void UnsafeOnCompleted(Action continuation)
             {
-                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext:false);
+                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext: false);
             }
 
             /// <summary>Ends the await on the completed <see cref="System.Threading.Tasks.Task"/>.</summary>
@@ -475,7 +475,7 @@ namespace System.Runtime.CompilerServices
             /// <summary>Gets whether the task being awaited is completed.</summary>
             /// <remarks>This property is intended for compiler user rather than use directly in code.</remarks>
             /// <exception cref="System.NullReferenceException">The awaiter was not properly initialized.</exception>
-            public bool IsCompleted 
+            public bool IsCompleted
             {
                 get { return m_task.IsCompleted; }
             }
@@ -487,7 +487,7 @@ namespace System.Runtime.CompilerServices
             /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
             public void OnCompleted(Action continuation)
             {
-                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext:true);
+                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext: true);
             }
 
             /// <summary>Schedules the continuation onto the <see cref="System.Threading.Tasks.Task"/> associated with this <see cref="TaskAwaiter"/>.</summary>
@@ -497,7 +497,7 @@ namespace System.Runtime.CompilerServices
             /// <remarks>This method is intended for compiler user rather than use directly in code.</remarks>
             public void UnsafeOnCompleted(Action continuation)
             {
-                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext:false);
+                TaskAwaiter.OnCompletedInternal(m_task, continuation, m_continueOnCapturedContext, flowExecutionContext: false);
             }
 
             /// <summary>Ends the await on the completed <see cref="System.Threading.Tasks.Task{TResult}"/>.</summary>
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/TupleElementNamesAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/TupleElementNamesAttribute.cs
deleted file mode 100644
index 65b120e6b4..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/TupleElementNamesAttribute.cs
+++ /dev/null
@@ -1,57 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System.Collections.Generic;
-
-namespace System.Runtime.CompilerServices
-{
-    /// <summary>
-    /// Indicates that the use of <see cref="System.ValueTuple"/> on a member is meant to be treated as a tuple with element names.
-    /// </summary>
-    [CLSCompliant(false)]
-    [AttributeUsage(AttributeTargets.Field | AttributeTargets.Parameter | AttributeTargets.Property | AttributeTargets.ReturnValue | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Event)]
-    public sealed class TupleElementNamesAttribute : Attribute
-    {
-        private readonly string[] _transformNames;
-
-        /// <summary>
-        /// Initializes a new instance of the <see
-        /// cref="TupleElementNamesAttribute"/> class.
-        /// </summary>
-        /// <param name="transformNames">
-        /// Specifies, in a pre-order depth-first traversal of a type's
-        /// construction, which <see cref="System.ValueType"/> occurrences are
-        /// meant to carry element names.
-        /// </param>
-        /// <remarks>
-        /// This constructor is meant to be used on types that contain an
-        /// instantiation of <see cref="System.ValueType"/> that contains
-        /// element names.  For instance, if <c>C</c> is a generic type with
-        /// two type parameters, then a use of the constructed type <c>C{<see
-        /// cref="System.ValueTuple{T1, T2}"/>, <see
-        /// cref="System.ValueTuple{T1, T2, T3}"/></c> might be intended to
-        /// treat the first type argument as a tuple with element names and the
-        /// second as a tuple without element names. In which case, the
-        /// appropriate attribute specification should use a
-        /// <c>transformNames</c> value of <c>{ "name1", "name2", null, null,
-        /// null }</c>.
-        /// </remarks>
-        public TupleElementNamesAttribute(string[] transformNames)
-        {
-            if (transformNames == null)
-            {
-                throw new ArgumentNullException(nameof(transformNames));
-            }
-
-            _transformNames = transformNames;
-        }
-
-        /// <summary>
-        /// Specifies, in a pre-order depth-first traversal of a type's
-        /// construction, which <see cref="System.ValueTuple"/> elements are
-        /// meant to carry element names.
-        /// </summary>
-        public IList<string> TransformNames => _transformNames;
-    }
-}
\ No newline at end of file
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/TypeDependencyAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/TypeDependencyAttribute.cs
index 2de9c1f785..929cbe7608 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/TypeDependencyAttribute.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/TypeDependencyAttribute.cs
@@ -2,28 +2,26 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-namespace System.Runtime.CompilerServices 
-{
-    using System;
-    using System.Diagnostics.Contracts;
+using System;
+using System.Diagnostics.Contracts;
 
+namespace System.Runtime.CompilerServices
+{
     // We might want to make this inherited someday.  But I suspect it shouldn't
     // be necessary.
     [AttributeUsage(AttributeTargets.Struct | AttributeTargets.Class | AttributeTargets.Interface, AllowMultiple = true, Inherited = false)]
-    internal sealed class TypeDependencyAttribute: Attribute    
+    internal sealed class TypeDependencyAttribute : Attribute
     {
-
         private string typeName;
 
-        public TypeDependencyAttribute (string typeName)        
+        public TypeDependencyAttribute(string typeName)
         {
-            if(typeName == null) throw new ArgumentNullException(nameof(typeName));
+            if (typeName == null) throw new ArgumentNullException(nameof(typeName));
             Contract.EndContractBlock();
             this.typeName = typeName;
         }
     }
-
 }
 
- 
+
 
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedFromAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedFromAttribute.cs
deleted file mode 100644
index 671d1f0071..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedFromAttribute.cs
+++ /dev/null
@@ -1,35 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-namespace System.Runtime.CompilerServices
-{
-    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface | AttributeTargets.Delegate, Inherited = false, AllowMultiple = false)]
-    public sealed class TypeForwardedFromAttribute : Attribute
-    {
-        string assemblyFullName;
-
-        private TypeForwardedFromAttribute()
-        {
-            // Disallow default constructor
-        }
-
-
-        public TypeForwardedFromAttribute(string assemblyFullName)
-        {
-            if (String.IsNullOrEmpty(assemblyFullName))
-            {
-                throw new ArgumentNullException(nameof(assemblyFullName));
-            }
-            this.assemblyFullName = assemblyFullName;    
-        }
-
-        public string AssemblyFullName
-        {
-            get { 
-                return assemblyFullName; 
-            }
-        }
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedToAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedToAttribute.cs
deleted file mode 100644
index 147c103047..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/TypeForwardedToAttribute.cs
+++ /dev/null
@@ -1,34 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-
-using System;
-using System.Reflection;
-
-namespace System.Runtime.CompilerServices
-{
-    using System;
-    [AttributeUsage(AttributeTargets.Assembly, AllowMultiple=true, Inherited=false)]
-    public sealed class TypeForwardedToAttribute : Attribute
-    {
-        private Type _destination;
-
-        public TypeForwardedToAttribute(Type destination)
-        {
-            _destination = destination;
-        }
-
-        public Type Destination
-        {
-            get {
-                return _destination;
-            }
-        }
-
-    }
-}
-
-
- 
-
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/Unsafe.cs b/src/mscorlib/src/System/Runtime/CompilerServices/Unsafe.cs
index adfa015161..b184cd9fa8 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/Unsafe.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/Unsafe.cs
@@ -4,6 +4,12 @@
 
 using System.Runtime.Versioning;
 
+#if BIT64
+using nuint = System.UInt64;
+#else
+using nuint = System.UInt32;
+#endif
+
 namespace System.Runtime.CompilerServices
 {
     //
@@ -37,6 +43,7 @@ namespace System.Runtime.CompilerServices
         {
             // The body of this function will be replaced by the EE with unsafe code that just returns sizeof !!T
             // See getILIntrinsicImplementationForUnsafe for how this happens.  
+            typeof(T).ToString(); // Type token used by the actual method body
             throw new InvalidOperationException();
         }
 
@@ -61,7 +68,19 @@ namespace System.Runtime.CompilerServices
         {
             // The body of this function will be replaced by the EE with unsafe code!!!
             // See getILIntrinsicImplementationForUnsafe for how this happens.
-            typeof(T).ToString(); // Type used by the actual method body
+            typeof(T).ToString(); // Type token used by the actual method body
+            throw new InvalidOperationException();
+        }
+
+        /// <summary>
+        /// Adds an element offset to the given reference.
+        /// </summary>
+        [NonVersionable]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ref T AddByteOffset<T>(ref T source, nuint byteOffset)
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementationForUnsafe for how this happens.
             throw new InvalidOperationException();
         }
 
@@ -89,5 +108,45 @@ namespace System.Runtime.CompilerServices
             // See getILIntrinsicImplementationForUnsafe for how this happens.  
             throw new InvalidOperationException();
         }
+
+        [NonVersionable]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static T ReadUnaligned<T>(void* source)
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementationForUnsafe for how this happens.  
+            typeof(T).ToString(); // Type token used by the actual method body
+            throw new InvalidOperationException();
+        }
+
+        [NonVersionable]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static T ReadUnaligned<T>(ref byte source)
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementationForUnsafe for how this happens.  
+            typeof(T).ToString(); // Type token used by the actual method body
+            throw new InvalidOperationException();
+        }
+
+        [NonVersionable]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void WriteUnaligned<T>(void* destination, T value)
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementationForUnsafe for how this happens.  
+            typeof(T).ToString(); // Type token used by the actual method body
+            throw new InvalidOperationException();
+        }
+
+        [NonVersionable]
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void WriteUnaligned<T>(ref byte destination, T value)
+        {
+            // The body of this function will be replaced by the EE with unsafe code!!!
+            // See getILIntrinsicImplementationForUnsafe for how this happens.  
+            typeof(T).ToString(); // Type token used by the actual method body
+            throw new InvalidOperationException();
+        }
     }
 }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/UnsafeValueTypeAttribute.cs b/src/mscorlib/src/System/Runtime/CompilerServices/UnsafeValueTypeAttribute.cs
deleted file mode 100644
index bc210ccb71..0000000000
--- a/src/mscorlib/src/System/Runtime/CompilerServices/UnsafeValueTypeAttribute.cs
+++ /dev/null
@@ -1,14 +0,0 @@
-// Licensed to the .NET Foundation under one or more agreements.
-// The .NET Foundation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-namespace System.Runtime.CompilerServices 
-{    
-    using System;
-    
-[Serializable]
-[AttributeUsage(AttributeTargets.Struct)]  
-    sealed public class UnsafeValueTypeAttribute : Attribute 
-    {        
-    }
-}
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/YieldAwaitable.cs b/src/mscorlib/src/System/Runtime/CompilerServices/YieldAwaitable.cs
index 92d1b4f95b..f1c7772526 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/YieldAwaitable.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/YieldAwaitable.cs
@@ -144,7 +144,6 @@ namespace System.Runtime.CompilerServices
 
                     etwLog.TaskWaitContinuationComplete(continuationId);
                 });
-                
             }
 
             /// <summary>WaitCallback that invokes the Action supplied as object state.</summary>
@@ -157,7 +156,7 @@ namespace System.Runtime.CompilerServices
             private static void RunAction(object state) { ((Action)state)(); }
 
             /// <summary>Ends the await operation.</summary>
-            public void GetResult() {} // Nop. It exists purely because the compiler pattern demands it.
+            public void GetResult() { } // Nop. It exists purely because the compiler pattern demands it.
         }
     }
 }
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/jithelpers.cs b/src/mscorlib/src/System/Runtime/CompilerServices/jithelpers.cs
index 080e42f46f..b86835f778 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/jithelpers.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/jithelpers.cs
@@ -16,8 +16,8 @@ using System.Diagnostics.Contracts;
 using System.Runtime.InteropServices;
 using System.Security;
 
-namespace System.Runtime.CompilerServices {
-
+namespace System.Runtime.CompilerServices
+{
     // Wrapper for address of a string variable on stack
     internal struct StringHandleOnStack
     {
@@ -114,14 +114,14 @@ namespace System.Runtime.CompilerServices {
 
         static internal int UnsafeEnumCast<T>(T val) where T : struct		// Actually T must be 4 byte (or less) enum
         {
-            Debug.Assert(typeof(T).IsEnum 
-                              && (Enum.GetUnderlyingType(typeof(T)) == typeof(int) 
-                                  || Enum.GetUnderlyingType(typeof(T)) == typeof(uint) 
+            Debug.Assert(typeof(T).IsEnum
+                              && (Enum.GetUnderlyingType(typeof(T)) == typeof(int)
+                                  || Enum.GetUnderlyingType(typeof(T)) == typeof(uint)
                                   || Enum.GetUnderlyingType(typeof(T)) == typeof(short)
                                   || Enum.GetUnderlyingType(typeof(T)) == typeof(ushort)
                                   || Enum.GetUnderlyingType(typeof(T)) == typeof(byte)
                                   || Enum.GetUnderlyingType(typeof(T)) == typeof(sbyte)),
-                "Error, T must be an 4 byte (or less) enum JitHelpers.UnsafeEnumCast!");            
+                "Error, T must be an 4 byte (or less) enum JitHelpers.UnsafeEnumCast!");
             return UnsafeEnumCastInternal<T>(val);
         }
 
@@ -134,9 +134,9 @@ namespace System.Runtime.CompilerServices {
 
         static internal long UnsafeEnumCastLong<T>(T val) where T : struct		// Actually T must be 8 byte enum
         {
-            Debug.Assert(typeof(T).IsEnum 
-                              && (Enum.GetUnderlyingType(typeof(T)) == typeof(long) 
-                                  || Enum.GetUnderlyingType(typeof(T)) == typeof(ulong)), 
+            Debug.Assert(typeof(T).IsEnum
+                              && (Enum.GetUnderlyingType(typeof(T)) == typeof(long)
+                                  || Enum.GetUnderlyingType(typeof(T)) == typeof(ulong)),
                 "Error, T must be an 8 byte enum JitHelpers.UnsafeEnumCastLong!");
             return UnsafeEnumCastLongInternal<T>(val);
         }
@@ -213,7 +213,7 @@ namespace System.Runtime.CompilerServices {
 
 #if _DEBUG
         [MethodImplAttribute(MethodImplOptions.InternalCall)]
-        extern static bool IsAddressInStack(IntPtr ptr);
+        private extern static bool IsAddressInStack(IntPtr ptr);
 #endif
 
         static internal bool ByRefLessThan<T>(ref T refA, ref T refB)
@@ -223,14 +223,6 @@ namespace System.Runtime.CompilerServices {
             throw new InvalidOperationException();
         }
 
-        /// <returns>true if given type is reference type or value type that contains references</returns>
-        static internal bool ContainsReferences<T>()
-        {
-            // The body of this function will be replaced by the EE with unsafe code!!!
-            // See getILIntrinsicImplementation for how this happens.
-            throw new InvalidOperationException();
-        }
-
         static internal ref T GetArrayData<T>(T[] array)
         {
             // The body of this function will be replaced by the EE with unsafe code!!!