Mark methods specially handled in JitInterface Intrinsic (dotnet#26209)

* Mark methods specially handled in JitInterface Intrinsic

For CPAOT compiler's sake.

src/System.Private.CoreLib/shared/System/Activator.RuntimeType.cs

@@ -136,6 +136,7 @@ public static partial class Activator
             return o != null ? new ObjectHandle(o) : null;
         }
 
+        [System.Runtime.CompilerServices.Intrinsic]
         public static T CreateInstance<T>()
         {
             return (T)((RuntimeType)typeof(T)).CreateInstanceDefaultCtor(publicOnly: true, skipCheckThis: true, fillCache: true, wrapExceptions: true);

src/System.Private.CoreLib/src/System/Runtime/CompilerServices/RuntimeHelpers.cs

@@ -146,6 +146,7 @@ internal static void ExecuteBackoutCodeHelper(object backoutCode, object? userDa
         }
 
         /// <returns>true if given type is reference type or value type that contains references</returns>
+        [Intrinsic]
         public static bool IsReferenceOrContainsReferences<T>()
         {
             // The body of this function will be replaced by the EE with unsafe code!!!
@@ -157,6 +158,7 @@ public static bool IsReferenceOrContainsReferences<T>()
         /// <remarks>
         /// Only use the result of this for Equals() comparison, not for CompareTo() comparison.
         /// </remarks>
+        [Intrinsic]
         internal static bool IsBitwiseEquatable<T>()
         {
             // The body of this function will be replaced by the EE with unsafe code!!!
@@ -167,6 +169,7 @@ internal static bool IsBitwiseEquatable<T>()
         internal static ref byte GetRawData(this object obj) =>
             ref Unsafe.As<RawData>(obj).Data;
 
+        [Intrinsic]
         internal static ref byte GetRawSzArrayData(this Array array) =>
             ref Unsafe.As<RawSzArrayData>(array).Data;
 

src/System.Private.CoreLib/src/System/Runtime/CompilerServices/jithelpers.cs

@@ -155,13 +155,15 @@ internal static StackCrawlMarkHandle GetStackCrawlMarkHandle(ref StackCrawlMark
             return new StackCrawlMarkHandle((IntPtr)Unsafe.AsPointer(ref stackMark));
         }
 
+        [Intrinsic]
         internal static bool EnumEquals<T>(T x, T y) where T : struct, Enum
         {
             // The body of this function will be replaced by the EE with unsafe code
             // See getILIntrinsicImplementation for how this happens.
             return x.Equals(y);
         }
 
+        [Intrinsic]
         internal static int EnumCompareTo<T>(T x, T y) where T : struct, Enum
         {
             // The body of this function will be replaced by the EE with unsafe code

src/System.Private.CoreLib/src/System/Threading/Interlocked.cs

@@ -107,6 +107,7 @@ public static T Exchange<T>([NotNullIfNotNull("value")] ref T location1, T value
         // The workaround is no longer strictly necessary now that we have Unsafe.As but it does
         // have the advantage of being less sensitive to JIT's inliner decisions.
         [return: NotNullIfNotNull("location1")]
+        [Intrinsic]
         public static T CompareExchange<T>(ref T location1, T value, T comparand) where T : class?
         {
             return Unsafe.As<T>(CompareExchange(ref Unsafe.As<T, object?>(ref location1), value, comparand));

src/vm/jitinterface.cpp

@@ -7638,7 +7638,7 @@ getMethodInfoHelper(
 
         MethodTable * pMT  = ftn->GetMethodTable();
 
-        if (pMT->GetModule()->IsSystem())
+        if (ftn->IsJitIntrinsic())
         {
             if (MscorlibBinder::IsClass(pMT, CLASS__JIT_HELPERS))
             {