[mono][interp] Avoid calls to m_class_get_mem_manager () in get_virtu…

…al_method_fast () (#60229)

unless needed.

src/mono/mono/mini/interp/interp.c

@@ -694,11 +694,12 @@ static InterpMethod* // Inlining causes additional stack use in caller.
 get_virtual_method_fast (InterpMethod *imethod, MonoVTable *vtable, int offset)
 {
 	gpointer *table;
-	MonoMemoryManager *memory_manager = m_class_get_mem_manager (vtable->klass);
+	MonoMemoryManager *memory_manager = NULL;
 
 	table = get_method_table (vtable, offset);
 
-	if (!table) {
+	if (G_UNLIKELY (!table)) {
+		memory_manager = m_class_get_mem_manager (vtable->klass);
 		/* Lazily allocate method table */
 		mono_mem_manager_lock (memory_manager);
 		table = get_method_table (vtable, offset);
@@ -707,8 +708,10 @@ get_virtual_method_fast (InterpMethod *imethod, MonoVTable *vtable, int offset)
 		mono_mem_manager_unlock (memory_manager);
 	}
 
-	if (!table [offset]) {
+	if (G_UNLIKELY (!table [offset])) {
 		InterpMethod *target_imethod = get_virtual_method (imethod, vtable);
+		if (!memory_manager)
+			memory_manager = m_class_get_mem_manager (vtable->klass);
 		/* Lazily initialize the method table slot */
 		mono_mem_manager_lock (memory_manager);
 		if (!table [offset]) {
@@ -727,8 +730,10 @@ get_virtual_method_fast (InterpMethod *imethod, MonoVTable *vtable, int offset)
 		/* Virtual generic or interface call. Multiple methods in slot */
 		InterpMethod *target_imethod = get_target_imethod ((GSList*)table [offset], imethod);
 
-		if (!target_imethod) {
+		if (G_UNLIKELY (!target_imethod)) {
 			target_imethod = get_virtual_method (imethod, vtable);
+			if (!memory_manager)
+				memory_manager = m_class_get_mem_manager (vtable->klass);
 			mono_mem_manager_lock (memory_manager);
 			if (!get_target_imethod ((GSList*)table [offset], imethod))
 				table [offset] = append_imethod (memory_manager, (GSList*)table [offset], imethod, target_imethod);