Implement common super type in reference type propagation.

Currently only if both types are classes.

Change-Id: I06e98211ead56875a42bd17f099e319b107a50d4

1 files changed, 20 insertions, 7 deletions

diff --git a/compiler/optimizing/reference_type_propagation.cc b/compiler/optimizing/reference_type_propagation.cc
index 3b78264727..0d05c49fc5 100644
--- a/compiler/optimizing/reference_type_propagation.cc
+++ b/compiler/optimizing/reference_type_propagation.cc
@@ -614,23 +614,36 @@ ReferenceTypeInfo ReferenceTypePropagation::MergeTypes(const ReferenceTypeInfo&
   }
 
   bool is_exact = a.IsExact() && b.IsExact();
-  Handle<mirror::Class> type_handle;
+  ReferenceTypeInfo::TypeHandle result_type_handle;
+  ReferenceTypeInfo::TypeHandle a_type_handle = a.GetTypeHandle();
+  ReferenceTypeInfo::TypeHandle b_type_handle = b.GetTypeHandle();
+  bool a_is_interface = a_type_handle->IsInterface();
+  bool b_is_interface = b_type_handle->IsInterface();
 
   if (a.GetTypeHandle().Get() == b.GetTypeHandle().Get()) {
-    type_handle = a.GetTypeHandle();
+    result_type_handle = a_type_handle;
   } else if (a.IsSupertypeOf(b)) {
-    type_handle = a.GetTypeHandle();
+    result_type_handle = a_type_handle;
     is_exact = false;
   } else if (b.IsSupertypeOf(a)) {
-    type_handle = b.GetTypeHandle();
+    result_type_handle = b_type_handle;
+    is_exact = false;
+  } else if (!a_is_interface && !b_is_interface) {
+    result_type_handle = handles_->NewHandle(a_type_handle->GetCommonSuperClass(b_type_handle));
     is_exact = false;
   } else {
-    // TODO: Find the first common super class.
-    type_handle = object_class_handle_;
+    // This can happen if:
+    //    - both types are interfaces. TODO(calin): implement
+    //    - one is an interface, the other a class, and the type does not implement the interface
+    //      e.g:
+    //        void foo(Interface i, boolean cond) {
+    //          Object o = cond ? i : new Object();
+    //        }
+    result_type_handle = object_class_handle_;
     is_exact = false;
   }
 
-  return ReferenceTypeInfo::Create(type_handle, is_exact);
+  return ReferenceTypeInfo::Create(result_type_handle, is_exact);
 }
 
 static void UpdateArrayGet(HArrayGet* instr,