[WIP] Initial CallFunctionCallback builtin.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index c3c3367b10937d9b8223f8db099d81300733c8ac..8769f0079daf9e19db3ce4050b868df518f3fada 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -2828,11 +2828,6 @@ void InternalArrayConstructorStub::Generate(MacroAssembler* masm) {
 static const int kCallApiFunctionSpillSpace = 4;
 
 
-static int AddressOffset(ExternalReference ref0, ExternalReference ref1) {
-  return static_cast<int>(ref0.address() - ref1.address());
-}
-
-
 // Calls an API function. Allocates HandleScope, extracts returned value
 // from handle and propagates exceptions.
 // 'stack_space' is the space to be unwound on exit (includes the call JS
@@ -2962,6 +2957,9 @@ static void CallApiFunctionAndReturn(
   __ JumpIfNotRoot(x5, Heap::kTheHoleValueRootIndex,
                    &promote_scheduled_exception);
 
+  // Check if the function returned a valid JavaScript value.
+  __ AssertApiCallResult(x0);
+
   if (stack_space_operand != NULL) {
     __ Drop(x2, 1);
   } else {
@@ -3039,6 +3037,12 @@ void CallApiCallbackStub::Generate(MacroAssembler* masm) {
   //    return value, return value default, isolate, holder.
   __ Push(call_data, call_data, isolate_reg, holder);
 
+  if (!is_store()) {
+    __ Mov(x0, argc());
+    __ Jump(masm->isolate()->builtins()->CallFunctionCallback(),
+            RelocInfo::CODE_TARGET);
+  }
+
   // Prepare arguments.
   Register args = x6;
   __ Mov(args, masm->StackPointer());