Initial UserTag and dart:profiler library

runtime/vm/tags.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/tags.h"
 
 #include "vm/isolate.h"
 #include "vm/json_stream.h"
+#include "vm/object.h"
+#include "vm/object_store.h"
 
 namespace dart {
 
 const char* VMTag::TagName(uword tag) {
   ASSERT(tag != kInvalidTagId);
   ASSERT(tag < kNumVMTags);
   const TagEntry& entry = entries_[tag];
   ASSERT(entry.id == tag);
   return entry.name;
 }
@@ skipping 52 matching lines @@
     }
   }
   {
     JSONArray arr(obj, "counters");
     for (intptr_t i = 1; i < VMTag::kNumVMTags; i++) {
       arr.AddValue64(counters_[i]);
     }
   }
 }
 
+
+const char* UserTagHelper::TagName(uword tag_address) {
+  Isolate* isolate = Isolate::Current();
+  const Instance& tag = Instance::Handle(
+    isolate,
+    reinterpret_cast<RawInstance*>(tag_address));
+  if (tag.IsNull()) {
+    return "Default User Tag";
+  }
+  const Library& profiler_lib = Library::Handle(
+      isolate,
+      isolate->object_store()->profiler_library());
+  ASSERT(!profiler_lib.IsNull());
+  const String& tag_class_name = String::Handle(isolate, String::New("Tag"));
+  ASSERT(!tag_class_name.IsNull());
+  const Class& tag_class = Class::Handle(
+      profiler_lib.LookupClass(tag_class_name));
+  ASSERT(!tag_class.IsNull());
+  const String& label_field_name = String::Handle(String::New("label"));
+  ASSERT(!label_field_name.IsNull());
+  const Field& label_field =
+      Field::Handle(tag_class.LookupField(label_field_name));
+  ASSERT(!label_field.IsNull());
+  const Object& field = Object::Handle(tag.GetField(label_field));
+  ASSERT(!field.IsNull());
+  const String& label = String::Cast(field);
+  return label.ToCString();
+}
+
+
 }  // namespace dart