Fix mono alc from gchandle (#62120)

* remove MonoManagedAssemblyLoadContext

* fix mono_alc_from_gchandle use field

* change by vargaz review

* formatting

* fixed compiler error

Author: srxqds

src/mono/mono/metadata/assembly-load-context.c

@@ -424,11 +424,19 @@ mono_alc_from_gchandle (MonoGCHandle alc_gchandle)
 	if (alc_gchandle == default_alc->gchandle)
 		return default_alc;
 
-	HANDLE_FUNCTION_ENTER ();
-	MonoManagedAssemblyLoadContextHandle managed_alc = MONO_HANDLE_CAST (MonoManagedAssemblyLoadContext, mono_gchandle_get_target_handle (alc_gchandle));
-	g_assert (!MONO_HANDLE_IS_NULL (managed_alc));
-	MonoAssemblyLoadContext *alc = MONO_HANDLE_GETVAL (managed_alc, native_assembly_load_context);
-	HANDLE_FUNCTION_RETURN_VAL (alc);
+	MONO_STATIC_POINTER_INIT (MonoClassField, resolve)
+	
+		MonoClass *alc_class = mono_class_get_assembly_load_context_class ();
+		g_assert (alc_class);
+		resolve = mono_class_get_field_from_name_full (alc_class, "_nativeAssemblyLoadContext", NULL);
+
+	MONO_STATIC_POINTER_INIT_END (MonoClassField, resolve)
+
+	g_assert (resolve);
+
+	MonoAssemblyLoadContext *alc = NULL;
+	mono_field_get_value_internal (mono_gchandle_get_target_internal (alc_gchandle), resolve, &alc);
+	return alc;	
 }
 
 MonoGCHandle

src/mono/mono/metadata/object-internals.h

@@ -1406,13 +1406,6 @@ typedef enum {
 	UNLOADING = 1
 } MonoManagedAssemblyLoadContextInternalState;
 
-// Keep in sync with System.Runtime.Loader.AssemblyLoadContext
-typedef struct {
-	MonoObject object;
-	MonoAssemblyLoadContext *native_assembly_load_context;
-} MonoManagedAssemblyLoadContext;
-
-TYPED_HANDLE_DECL (MonoManagedAssemblyLoadContext);
 
 /* All MonoInternalThread instances should be pinned, so it's safe to use the raw ptr.  However
  * for uniformity, icall wrapping will make handles anyway.  So this is the method for getting the payload.