Annotating System.Formats.Asn1 library for Aot

src/libraries/System.Formats.Asn1/src/System.Formats.Asn1.csproj

@@ -4,6 +4,7 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <DefineConstants>$(DefineConstants);CP_NO_ZEROMEMORY</DefineConstants>
     <IsPackable>true</IsPackable>
+    <EnableAOTAnalyzer>true</EnableAOTAnalyzer>
     <PackageDescription>Provides classes that can read and write the ASN.1 BER, CER, and DER data formats.
 
 Commonly Used Types:

src/libraries/System.Formats.Asn1/src/System/Formats/Asn1/AsnDecoder.Enumerated.cs

@@ -211,7 +211,7 @@ public static Enum ReadEnumeratedValue(
             }
 
             // T-REC-X.690-201508 sec 8.4 says the contents are the same as for integers.
-            int sizeLimit = Marshal.SizeOf(backingType);
+            int sizeLimit = GetPrimitiveIntegerSize(backingType);
 
             if (backingType == typeof(int) ||
                 backingType == typeof(long) ||

src/libraries/System.Formats.Asn1/src/System/Formats/Asn1/AsnDecoder.NamedBitList.cs

@@ -196,7 +196,7 @@ public static Enum ReadNamedBitListValue(
             }
 
             Span<byte> stackSpan = stackalloc byte[sizeof(ulong)];
-            int sizeLimit = Marshal.SizeOf(backingType);
+            int sizeLimit = GetPrimitiveIntegerSize(backingType);
             stackSpan = stackSpan.Slice(0, sizeLimit);
 
             bool read = TryReadBitString(

src/libraries/System.Formats.Asn1/src/System/Formats/Asn1/AsnDecoder.cs

@@ -466,6 +466,19 @@ private static AsnContentException GetValidityException(LengthValidity validity)
             }
         }
 
+        private static int GetPrimitiveIntegerSize(Type primitiveType)
+        {
+            if (primitiveType == typeof(byte) || primitiveType == typeof(sbyte))
+                return 1;
+            if (primitiveType == typeof(short) || primitiveType == typeof(ushort))
+                return 2;
+            if (primitiveType == typeof(int) || primitiveType == typeof(uint))
+                return 4;
+            if (primitiveType == typeof(long) || primitiveType == typeof(ulong))
+                return 8;
+            return 0;
+        }
+
         /// <summary>
         /// Get the number of bytes between the start of <paramref name="source" /> and
         /// the End-of-Contents marker