cleanup api callbacks now that handles are never returned directly

src/x64/macro-assembler-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 667 matching lines @@
 
 
 static int Offset(ExternalReference ref0, ExternalReference ref1) {
   int64_t offset = (ref0.address() - ref1.address());
   // Check that fits into int.
   ASSERT(static_cast<int>(offset) == offset);
   return static_cast<int>(offset);
 }
 
 
-void MacroAssembler::PrepareCallApiFunction(int arg_stack_space,
-                                            bool returns_handle) {
-#if defined(_WIN64) && !defined(__MINGW64__)
-  if (!returns_handle) {
-    EnterApiExitFrame(arg_stack_space);
-    return;
-  }
-  // We need to prepare a slot for result handle on stack and put
-  // a pointer to it into 1st arg register.
-  EnterApiExitFrame(arg_stack_space + 1);
-
-  // rcx must be used to pass the pointer to the return value slot.
-  lea(rcx, StackSpaceOperand(arg_stack_space));
-#else
+void MacroAssembler::PrepareCallApiFunction(int arg_stack_space) {
   EnterApiExitFrame(arg_stack_space);
-#endif
 }
 
 
 void MacroAssembler::CallApiFunctionAndReturn(Address function_address,
                                               Address thunk_address,
                                               Register thunk_last_arg,
                                               int stack_space,
-                                              bool returns_handle,
                                               int return_value_offset) {
   Label prologue;
   Label promote_scheduled_exception;
   Label delete_allocated_handles;
   Label leave_exit_frame;
   Label write_back;
 
   Factory* factory = isolate()->factory();
   ExternalReference next_address =
       ExternalReference::handle_scope_next_address(isolate());
@@ skipping 52 matching lines @@
 
   if (FLAG_log_timer_events) {
     FrameScope frame(this, StackFrame::MANUAL);
     PushSafepointRegisters();
     PrepareCallCFunction(1);
     LoadAddress(arg_reg_1, ExternalReference::isolate_address(isolate()));
     CallCFunction(ExternalReference::log_leave_external_function(isolate()), 1);
     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 (returns_handle) {
-    Label empty_result;
-#if defined(_WIN64) && !defined(__MINGW64__)
-    // 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));
-    jmp(&prologue);
-    bind(&empty_result);
-  }
   // Load the value from ReturnValue
   movq(rax, Operand(rbp, return_value_offset * kPointerSize));
   bind(&prologue);
 
   // No more valid handles (the result handle was the last one). Restore
   // previous handle scope.
   subl(Operand(base_reg, kLevelOffset), Immediate(1));
   movq(Operand(base_reg, kNextOffset), prev_next_address_reg);
   cmpq(prev_limit_reg, Operand(base_reg, kLimitOffset));
   j(not_equal, &delete_allocated_handles);
@@ skipping 3889 matching lines @@
   j(greater, &no_memento_available);
   CompareRoot(MemOperand(scratch_reg, -AllocationMemento::kSize),
               Heap::kAllocationMementoMapRootIndex);
   bind(&no_memento_available);
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64