[Atomics] code stubs for atomic operations

src/x64/interface-descriptors-x64.cc

Index: src/x64/interface-descriptors-x64.cc
diff --git a/src/x64/interface-descriptors-x64.cc b/src/x64/interface-descriptors-x64.cc
index 0fd2b83fd2bb8b4a04ca45851893ee930cf98798..c1e4064d9d54c39ad710ab2bad73ec3dc8de3f4c 100644
--- a/src/x64/interface-descriptors-x64.cc
+++ b/src/x64/interface-descriptors-x64.cc
@@ -437,6 +437,24 @@ void InterpreterCEntryDescriptor::InitializePlatformSpecific(
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
+
+void AtomicsLoadDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {rdx, rax};
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
+
+void BuiltinDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {
+      rax /* argc */, rbx /* argv */, rsi /* context */, rdi /* function */,
+      rdx /* new.target */
+  };
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
+
 }  // namespace internal
 }  // namespace v8