Simplify the way constructors are called and avoid pushing...

src/x64/virtual-frame-x64.cc

 // Copyright 2010 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 1212 matching lines @@
   return RawCallCodeObject(ic, mode);
 }
 
 
 Result VirtualFrame::CallConstructor(int arg_count) {
   // Arguments, receiver, and function are on top of the frame.  The
   // IC expects arg count in rax, function in rdi, and the arguments
   // and receiver on the stack.
   Handle<Code> ic(Builtins::builtin(Builtins::JSConstructCall));
   // Duplicate the function before preparing the frame.
-  PushElementAt(arg_count + 1);
+  PushElementAt(arg_count);
   Result function = Pop();
-  PrepareForCall(arg_count + 1, arg_count + 1);  // Spill args and receiver.
+  PrepareForCall(arg_count + 1, arg_count + 1);  // Spill function and args.
   function.ToRegister(rdi);
 
   // Constructors are called with the number of arguments in register
   // rax for now. Another option would be to have separate construct
   // call trampolines per different arguments counts encountered.
   Result num_args = cgen()->allocator()->Allocate(rax);
   ASSERT(num_args.is_valid());
   __ Set(num_args.reg(), arg_count);
 
   function.Unuse();
   num_args.Unuse();
   return RawCallCodeObject(ic, RelocInfo::CONSTRUCT_CALL);
 }
 
 
 void VirtualFrame::PushTryHandler(HandlerType type) {
   ASSERT(cgen()->HasValidEntryRegisters());
   // Grow the expression stack by handler size less one (the return
   // address is already pushed by a call instruction).
   Adjust(kHandlerSize - 1);
   __ PushTryHandler(IN_JAVASCRIPT, type);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64