[Atomics] code stubs for atomic operations

src/arm64/interface-descriptors-arm64.cc

Index: src/arm64/interface-descriptors-arm64.cc
diff --git a/src/arm64/interface-descriptors-arm64.cc b/src/arm64/interface-descriptors-arm64.cc
index f5e0fa8206f1ed25f64ecac1c95cf3e63849ffc0..12302e45de5be13981bab2f4684cfb28dced00b4 100644
--- a/src/arm64/interface-descriptors-arm64.cc
+++ b/src/arm64/interface-descriptors-arm64.cc
@@ -477,6 +477,15 @@ void ResumeGeneratorDescriptor::InitializePlatformSpecific(
   data->InitializePlatformSpecific(arraysize(registers), registers);
 }
 
+void AtomicsLoadDescriptor::InitializePlatformSpecific(
+    CallInterfaceDescriptorData* data) {
+  Register registers[] = {
+      x1,  // the typedarray object
+      x0   // the index to load (untagged)
+  };
+  data->InitializePlatformSpecific(arraysize(registers), registers);
+}
+
 }  // namespace internal
 }  // namespace v8