new style of property/function callbacks

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 691894c0e2cb4eb92fdad51bf9cbbed5c0c29fc1..2fed6efb1ac8f72efaa6a3214246361f7208a20c 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -692,8 +692,8 @@ void MacroAssembler::PrepareCallApiFunction(int arg_stack_space) {
 
 
 void MacroAssembler::CallApiFunctionAndReturn(Address function_address,
-                                              int stack_space) {
-  Label empty_result;
+                                              int stack_space,
+                                              int return_value_offset) {
   Label prologue;
   Label promote_scheduled_exception;
   Label delete_allocated_handles;
@@ -745,15 +745,26 @@ void MacroAssembler::CallApiFunctionAndReturn(Address function_address,
     PopSafepointRegisters();
   }
 
+  // Can skip the result check for new-style callbacks
+  // TODO(dcarney): may need to pass this information down
+  // as some function_addresses might not have been registered
+  if (!CallbackTable::ReturnsVoid(isolate(), function_address)) {
+    Label empty_result;
 #if defined(_WIN64) && !defined(__MINGW64__)
-  // rax keeps a pointer to v8::Handle, unpack it.
-  movq(rax, Operand(rax, 0));
+    // rax keeps a pointer to v8::Handle, unpack it.
+    movq(rax, Operand(rax, 0));
 #endif
-  // Check if the result handle holds 0.
-  testq(rax, rax);
-  j(zero, &empty_result);
-  // It was non-zero.  Dereference to get the result value.
-  movq(rax, Operand(rax, 0));
+    // Check if the result handle holds 0.
+    testq(rax, rax);
+    j(zero, &empty_result);
+    // It was non-zero.  Dereference to get the result value.
+    movq(rax, Operand(rax, 0));
+    jmp(&prologue);
+    bind(&empty_result);
+  }
+  // Load the value from ReturnValue
+  movq(rax, StackSpaceOperand(0));
+  movq(rax, Operand(rax, return_value_offset * kPointerSize));
   bind(&prologue);
 
   // No more valid handles (the result handle was the last one). Restore
@@ -807,11 +818,6 @@ void MacroAssembler::CallApiFunctionAndReturn(Address function_address,
   LeaveApiExitFrame();
   ret(stack_space * kPointerSize);
 
-  bind(&empty_result);
-  // It was zero; the result is undefined.
-  LoadRoot(rax, Heap::kUndefinedValueRootIndex);
-  jmp(&prologue);
-
   bind(&promote_scheduled_exception);
   TailCallRuntime(Runtime::kPromoteScheduledException, 0, 1);