[builtins] Remove some (now) unused code from C++ builtin adaptor.

src/x64/builtins-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
 #include "src/deoptimizer.h"
 #include "src/full-codegen/full-codegen.h"
@@ skipping 14 matching lines @@
   //                            is not marked as DontAdaptArguments)
   //  -- rdi                 : called function
   //  -- rsp[0]              : return address
   //  -- rsp[8]              : last argument
   //  -- ...
   //  -- rsp[8 * argc]       : first argument
   //  -- rsp[8 * (argc + 1)] : receiver
   // -----------------------------------
   __ AssertFunction(rdi);
 
-  // Make sure we operate in the context of the called function (for example
-  // ConstructStubs implemented in C++ will be run in the context of the caller
-  // instead of the callee, due to the way that [[Construct]] is defined for
-  // ordinary functions).
-  // TODO(bmeurer): Can we make this more robust?
-  __ movp(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
-
   // Insert extra arguments.
   int num_extra_args = 0;
   if (extra_args == NEEDS_CALLED_FUNCTION) {
     num_extra_args = 1;
     __ PopReturnAddressTo(kScratchRegister);
     __ Push(rdi);
     __ PushReturnAddressFrom(kScratchRegister);
   } else {
     DCHECK(extra_args == NO_EXTRA_ARGUMENTS);
   }
 
   // JumpToExternalReference expects rax to contain the number of arguments
-  // including the receiver and the extra arguments.  But rax is only valid
-  // if the called function is marked as DontAdaptArguments, otherwise we
-  // need to load the argument count from the SharedFunctionInfo.
-  Label argc, done_argc;
-  __ movp(rdx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
-  __ LoadSharedFunctionInfoSpecialField(
-      rbx, rdx, SharedFunctionInfo::kFormalParameterCountOffset);
-  __ cmpp(rbx, Immediate(SharedFunctionInfo::kDontAdaptArgumentsSentinel));
-  __ j(equal, &argc, Label::kNear);
-  __ leap(rax, Operand(rbx, num_extra_args + 1));
-  __ jmp(&done_argc, Label::kNear);
-  __ bind(&argc);
+  // including the receiver and the extra arguments.
   __ addp(rax, Immediate(num_extra_args + 1));
-  __ bind(&done_argc);
 
   __ JumpToExternalReference(ExternalReference(id, masm->isolate()), 1);
 }
 
 
 static void CallRuntimePassFunction(
     MacroAssembler* masm, Runtime::FunctionId function_id) {
   // ----------- S t a t e -------------
   //  -- rdx : new target (preserved for callee)
   //  -- rdi : target function (preserved for callee)
@@ skipping 1983 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_X64