Track field types.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index cf345170fb0c7692dbdb42277d7c2d2d5d32db99..c5d45772ef59816d022342b60195ec44925ac828 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5370,7 +5370,7 @@ HInstruction* HOptimizedGraphBuilder::BuildLoadNamedField(
     access = HObjectAccess::ForHeapNumberValue();
   }
   return New<HLoadNamedField>(
-      checked_object, static_cast<HValue*>(NULL), access);
+      checked_object, static_cast<HValue*>(NULL), access, info->field_map());
 }
 
 
@@ -5415,6 +5415,12 @@ HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
                                     value, STORE_TO_INITIALIZED_ENTRY);
     }
   } else {
+    if (!info->field_map().is_null()) {
+      ASSERT(field_access.representation().IsHeapObject());
+      BuildCheckHeapObject(value);
+      value = BuildCheckMap(value, info->field_map());
+    }
+
     // This is a normal store.
     instr = New<HStoreNamedField>(
         checked_object->ActualValue(), field_access, value,
@@ -5478,6 +5484,12 @@ bool HOptimizedGraphBuilder::PropertyAccessInfo::IsCompatible(
   }
   if (info->access_.offset() != access_.offset()) return false;
   if (info->access_.IsInobject() != access_.IsInobject()) return false;
+  if (!field_map_.is_identical_to(info->field_map_)) {
+    if (!IsLoad()) return false;
+
+    // Throw away type information for merging polymorphic loads.
+    field_map_ = info->field_map_ = Handle<Map>();
+  }
   info->GeneralizeRepresentation(r);
   return true;
 }
@@ -5497,7 +5509,26 @@ bool HOptimizedGraphBuilder::PropertyAccessInfo::LoadResult(Handle<Map> map) {
   }
 
   if (lookup_.IsField()) {
+    // Construct the object field access.
     access_ = HObjectAccess::ForField(map, &lookup_, name_);
+
+    if (access_.representation().IsHeapObject()) {
+      // Figure out the field type from the accessor map.
+      HeapType* field_type = lookup_.GetFieldTypeFromMap(*map);
+      if (field_type->IsClass()) {
+        Handle<Map> field_map = field_type->AsClass();
+        if (field_map->is_stable()) {  // TODO(bmeurer)
+          field_map_ = field_map;
+          field_map_->AddDependentCompilationInfo(
+              DependentCode::kPrototypeCheckGroup, top_info());
+
+          // Add dependency on the map that introduced the field.
+          Handle<Map> field_owner = handle(lookup_.GetFieldOwnerFromMap(*map));
+          field_owner->AddDependentCompilationInfo(
+              DependentCode::kFieldTypeGroup, top_info());
+        }
+      }
+    }
   } else if (lookup_.IsPropertyCallbacks()) {
     Handle<Object> callback(lookup_.GetValueFromMap(*map), isolate());
     if (!callback->IsAccessorPair()) return false;