Merge the Merlin heap tracing to top-of-trunk.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index 548e76b39eabfef2fda71a69f8723ea299d1b000..056d4a64fb293e0d2b73e6ad70f8f4c18ada62d8 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1902,4 +1902,20 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t,
 }
 END_LEAF_RUNTIME_ENTRY
 
+
+DEFINE_LEAF_RUNTIME_ENTRY(void,
+                          HeapTraceStore,
+                          RawObject* object,
+                          uword field_addr,
+                          RawObject* value) {
+  if (!(object->IsHeapObject() && value->IsHeapObject())) {

[siva, 2012/12/05 16:06:40]

I am a little confused by this check. Is it here to filter out stores to Smi?

[cshapiro, 2012/12/08 03:23:08]

This check ensures that both the source and destination are values and rejects
all other cases.

+    return;
+  }
+  HeapTrace* heap_trace = Isolate::Current()->heap()->trace();
+  heap_trace->TraceStoreIntoObject(RawObject::ToAddr(object),
+                                   field_addr,
+                                   RawObject::ToAddr(value));
+}
+END_LEAF_RUNTIME_ENTRY
+
 }  // namespace dart