Update mscorlib declaration and implement Unsafe.As<T> (#3233)

Author: josesimoes

CMake/Modules/FindNF_CoreCLR.cmake

@@ -110,6 +110,7 @@ set(NF_CoreCLR_SRCS
     corlib_native_System_Reflection_Binder.cpp
     corlib_native_System_Reflection_MemberInfo.cpp
     corlib_native_System_Runtime_CompilerServices_RuntimeHelpers.cpp
+    corlib_native_System_Runtime_CompilerServices_Unsafe.cpp
     corlib_native_System_Runtime_Remoting_RemotingServices.cpp
     corlib_native_System_String.cpp
     corlib_native_System_Span_1.cpp

src/CLR/CorLib/CorLib.vcxproj

@@ -60,6 +60,7 @@
     <ClCompile Include="corlib_native_System_Reflection_RuntimeMethodInfo.cpp" />
     <ClCompile Include="corlib_native_System_RuntimeType.cpp" />
     <ClCompile Include="corlib_native_System_Runtime_CompilerServices_RuntimeHelpers.cpp" />
+    <ClCompile Include="corlib_native_System_Runtime_CompilerServices_Unsafe.cpp" />
     <ClCompile Include="corlib_native_System_Runtime_Remoting_RemotingServices.cpp" />
     <ClCompile Include="corlib_native_System_Span_1.cpp" />
     <ClCompile Include="corlib_native_System_String.cpp" />

src/CLR/CorLib/CorLib.vcxproj.filters

@@ -179,5 +179,8 @@
     <ClCompile Include="corlib_native_System_ReadOnlySpan_1.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="corlib_native_System_Runtime_CompilerServices_Unsafe.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
   </ItemGroup>
 </Project>

src/CLR/CorLib/corlib_native.cpp

@@ -278,6 +278,20 @@ static const CLR_RT_MethodHandler method_lookup[] =
     nullptr,
     nullptr,
     nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
     Library_corlib_native_System_BitConverter::get_IsLittleEndian___STATIC__BOOLEAN,
     Library_corlib_native_System_BitConverter::DoubleToInt64Bits___STATIC__I8__R8,
     Library_corlib_native_System_BitConverter::GetBytes___STATIC__SZARRAY_U1__BOOLEAN,
@@ -745,6 +759,7 @@ static const CLR_RT_MethodHandler method_lookup[] =
     Library_corlib_native_System_Runtime_CompilerServices_RuntimeHelpers::RunClassConstructor___STATIC__VOID__SystemRuntimeTypeHandle,
     Library_corlib_native_System_Runtime_CompilerServices_RuntimeHelpers::get_OffsetToStringData___STATIC__I4,
     Library_corlib_native_System_Runtime_CompilerServices_RuntimeHelpers::IsReferenceOrContainsReferences___STATIC__BOOLEAN,
+    Library_corlib_native_System_Runtime_CompilerServices_Unsafe::As___STATIC__GENERICTYPE__OBJECT,
     nullptr,
     Library_corlib_native_System_Runtime_Remoting_RemotingServices::IsTransparentProxy___STATIC__BOOLEAN__OBJECT,
     nullptr,
@@ -1573,7 +1588,7 @@ const CLR_RT_NativeAssemblyData g_CLR_AssemblyNative_mscorlib =
 
 #if (NANOCLR_REFLECTION == TRUE)
 
-    0xCF059C3B,
+    0x559086F3,
 
 #elif (NANOCLR_REFLECTION == FALSE)
 

src/CLR/CorLib/corlib_native.h

@@ -889,6 +889,15 @@ struct Library_corlib_native_System_Runtime_CompilerServices_RuntimeHelpers
         bool &isRefContainsRefs);
 };
 
+#if (NANOCLR_REFLECTION == TRUE)
+struct Library_corlib_native_System_Runtime_CompilerServices_Unsafe
+{
+    NANOCLR_NATIVE_DECLARE(As___STATIC__GENERICTYPE__OBJECT);
+
+    //--//
+};
+#endif
+
 struct Library_corlib_native_System_Runtime_Remoting_RemotingServices
 {
     NANOCLR_NATIVE_DECLARE(IsTransparentProxy___STATIC__BOOLEAN__OBJECT);

src/CLR/CorLib/corlib_native_System_Runtime_CompilerServices_Unsafe.cpp

@@ -0,0 +1,20 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// Portions Copyright (c) Microsoft Corporation.  All rights reserved.
+// See LICENSE file in the project root for full license information.
+//
+
+#include "CorLib.h"
+
+HRESULT Library_corlib_native_System_Runtime_CompilerServices_Unsafe::As___STATIC__GENERICTYPE__OBJECT(
+    CLR_RT_StackFrame &stack)
+{
+    NANOCLR_HEADER();
+
+    CLR_RT_HeapBlock &arg = stack.Arg0();
+
+    // Set the argument as the return value (ldarg.0; ret)
+    stack.PushValueAndAssign(arg);
+
+    NANOCLR_NOCLEANUP_NOLABEL();
+}