Generate code for store buffer updates in open-coded object field stores.

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 725858bc713d7946dc32cfd15bbd7e4fc34e102f..b44dc97c806d444bfedda07fcb435601709e5573 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1574,4 +1574,14 @@ RawCode* FunctionsCache::LookupCode(const String& function_name,
   return Code::null();
 }
 
+
+// Adds a pointer to the store buffer.
+// Arg0: the address of a field being stored into
+DEFINE_LEAF_RUNTIME_ENTRY(StoreBuffer, 1) {
+  ASSERT(args.Count() == kStoreBufferRuntimeEntry.argument_count());
+  uword ptr = reinterpret_cast<uword>(args.At(0));
+  isolate->store_buffer()->AddPointer(ptr);
+  return Smi::New(0);  // Just an arbitrary RawObject* value.
+}
+
 }  // namespace dart