Fix x86 only ICastable feature bug.

When we call ICastable.IsInstanceOfInterface, we treat RuntimeTypeHandle as a OBJECTREF, which is incorrect as-per x86 calling convention since RuntimeTypehandle is a struct that contains a RuntimeType ref field and needs to be passed in stack. Our VM simple call helpers CALL_MANAGED_METHOD doesn't handle this correctly (it does the simple thing that always assume all the arguments are passed in register first). I'm fixing this by using a static method that takes RuntimeType instead of RuntimeTypeHandle, then convert it to RuntimeTypehandle.
Also switch to use PREPARE_NONVIRTUAL_CALLSITE(METHODID) as per Jan's suggestion.
ICastable test is now enabled in x86 for both JITs.

3 files changed, 26 insertions, 0 deletions

diff --git a/src/mscorlib/model.CoreLib.xml b/src/mscorlib/model.CoreLib.xml
index 6ea5768f28..114b4505e6 100644
--- a/src/mscorlib/model.CoreLib.xml
+++ b/src/mscorlib/model.CoreLib.xml
@@ -5539,6 +5539,10 @@
       <Member Name="IsInstanceOfInterface(System.RuntimeTypeHandle,System.Exception@)" /> <!-- EE -->
       <Member Name="GetImplType(System.RuntimeTypeHandle)" /> <!-- EE -->
     </Type>
+    <Type Name="System.Runtime.CompilerServices.ICastableHelpers"> 
+      <Member Name="IsInstanceOfInterface(System.Runtime.CompilerServices.ICastable,System.RuntimeType,System.Exception@)" /> <!-- EE -->
+      <Member Name="GetImplType(System.Runtime.CompilerServices.ICastable,System.RuntimeType)" /> <!-- EE -->
+    </Type>
     <Type Name="System.Runtime.CompilerServices.IsExplicitlyDereferenced"> <!-- for MC++ -->
     </Type>
     <Type Name="System.Runtime.CompilerServices.IsImplicitlyDereferenced">  <!-- for MC++ -->
diff --git a/src/mscorlib/model.xml b/src/mscorlib/model.xml
index ef2774a9f3..671da7e1dd 100644
--- a/src/mscorlib/model.xml
+++ b/src/mscorlib/model.xml
@@ -5539,6 +5539,10 @@
       <Member Name="IsInstanceOfInterface(System.RuntimeTypeHandle,System.Exception@)" /> <!-- EE -->
       <Member Name="GetImplType(System.RuntimeTypeHandle)" /> <!-- EE -->
     </Type>
+    <Type Name="System.Runtime.CompilerServices.ICastableHelpers"> 
+      <Member Name="IsInstanceOfInterface(System.Runtime.CompilerServices.ICastable,System.RuntimeType, System.Exception@)" /> <!-- EE -->
+      <Member Name="GetImplType(System.Runtime.CompilerServices.ICastable,System.RuntimeType)" /> <!-- EE -->
+    </Type>  
     <Type Name="System.Runtime.CompilerServices.IsExplicitlyDereferenced"> <!-- for MC++ -->
     </Type>
     <Type Name="System.Runtime.CompilerServices.IsImplicitlyDereferenced">  <!-- for MC++ -->
diff --git a/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs b/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
index bd04647332..7ba9434575 100644
--- a/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
+++ b/src/mscorlib/src/System/Runtime/CompilerServices/ICastable.cs
@@ -61,4 +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 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(); 
+        }    
+    }
 }