Sharing of descriptor arrays.

test/cctest/test-heap-profiler.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 //
 // Tests for heap profiler
 
 #include <ctype.h>
 
 #include "v8.h"
 
 #include "cctest.h"
 #include "hashmap.h"
@@ skipping 1652 matching lines @@
 TEST(MapHasDescriptorsAndTransitions) {
   v8::HandleScope scope;
   LocalContext env;
   CompileRun("obj = { a: 10 };\n");
   const v8::HeapSnapshot* snapshot =
       v8::HeapProfiler::TakeSnapshot(v8_str("snapshot"));
   const v8::HeapGraphNode* global = GetGlobalObject(snapshot);
   const v8::HeapGraphNode* global_object =
       GetProperty(global, v8::HeapGraphEdge::kProperty, "obj");
   CHECK_NE(NULL, global_object);
+
   const v8::HeapGraphNode* map =
       GetProperty(global_object, v8::HeapGraphEdge::kInternal, "map");
   CHECK_NE(NULL, map);
-  const v8::HeapGraphNode* descriptors =
-      GetProperty(map, v8::HeapGraphEdge::kInternal, "descriptors");
+  const v8::HeapGraphNode* own_descriptors = GetProperty(
+      map, v8::HeapGraphEdge::kInternal, "descriptors");
+  CHECK_EQ(NULL, own_descriptors);
+  const v8::HeapGraphNode* own_transitions = GetProperty(
+      map, v8::HeapGraphEdge::kInternal, "transitions");
+  CHECK_EQ(NULL, own_transitions);
+
+  const v8::HeapGraphNode* back_pointer_map =
+      GetProperty(map, v8::HeapGraphEdge::kInternal, "backpointer");
+  CHECK_NE(NULL, back_pointer_map);
+  const v8::HeapGraphNode* descriptors = GetProperty(
+      back_pointer_map, v8::HeapGraphEdge::kInternal, "descriptors");
   CHECK_NE(NULL, descriptors);
-  const v8::HeapGraphNode* transitions =
-      GetProperty(map, v8::HeapGraphEdge::kInternal, "transitions");
+  const v8::HeapGraphNode* transitions = GetProperty(
+      back_pointer_map, v8::HeapGraphEdge::kInternal, "transitions");
   CHECK_NE(NULL, transitions);
 }