fix performance regression on intel call api stubs

src/x64/code-stubs-x64.cc

 // Copyright 2013 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.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
@@ skipping 4799 matching lines @@
   __ movp(rax, prev_limit_reg);
   __ jmp(&leave_exit_frame);
 }
 
 
 static void CallApiFunctionStubHelper(MacroAssembler* masm,
                                       const ParameterCount& argc,
                                       bool return_first_arg,
                                       bool call_data_undefined) {
   // ----------- S t a t e -------------
-  //  -- rax                 : callee
+  //  -- rdi                 : callee
   //  -- rbx                 : call_data
   //  -- rcx                 : holder
   //  -- rdx                 : api_function_address
   //  -- rsi                 : context
-  //  -- rdi                 : number of arguments if argc is a register
+  //  -- rax                 : number of arguments if argc is a register
   //  -- rsp[0]              : return address
   //  -- rsp[8]              : last argument
   //  -- ...
   //  -- rsp[argc * 8]       : first argument
   //  -- rsp[(argc + 1) * 8] : receiver
   // -----------------------------------
 
-  Register callee = rax;
+  Register callee = rdi;
   Register call_data = rbx;
   Register holder = rcx;
   Register api_function_address = rdx;
   Register context = rsi;
+  Register return_address = r8;
 
   typedef FunctionCallbackArguments FCA;
 
   STATIC_ASSERT(FCA::kContextSaveIndex == 6);
   STATIC_ASSERT(FCA::kCalleeIndex == 5);
   STATIC_ASSERT(FCA::kDataIndex == 4);
   STATIC_ASSERT(FCA::kReturnValueOffset == 3);
   STATIC_ASSERT(FCA::kReturnValueDefaultValueIndex == 2);
   STATIC_ASSERT(FCA::kIsolateIndex == 1);
   STATIC_ASSERT(FCA::kHolderIndex == 0);
   STATIC_ASSERT(FCA::kArgsLength == 7);
 
-  DCHECK(argc.is_immediate() || rdi.is(argc.reg()));
+  DCHECK(argc.is_immediate() || rax.is(argc.reg()));
 
-  if (kPointerSize == kInt64Size) {
-    //  pop return address and save context
-    __ xchgq(context, Operand(rsp, 0));
-  } else {
-    // x32 handling.
-    __ PopReturnAddressTo(kScratchRegister);
-    __ Push(context);
-    __ movq(context, kScratchRegister);
-  }
+  __ PopReturnAddressTo(return_address);
+
+  // context save
+  __ Push(context);
 
   // callee
   __ Push(callee);
 
   // call data
   __ Push(call_data);
   Register scratch = call_data;
   if (!call_data_undefined) {
     __ LoadRoot(scratch, Heap::kUndefinedValueRootIndex);
   }
   // return value
   __ Push(scratch);
   // return value default
   __ Push(scratch);
   // isolate
   __ Move(scratch, ExternalReference::isolate_address(masm->isolate()));
   __ Push(scratch);
   // holder
   __ Push(holder);
 
   __ movp(scratch, rsp);
   // Push return address back on stack.
-  __ PushReturnAddressFrom(context);
+  __ PushReturnAddressFrom(return_address);
 
   // load context from callee
   __ movp(context, FieldOperand(callee, JSFunction::kContextOffset));
 
   // Allocate the v8::Arguments structure in the arguments' space since
   // it's not controlled by GC.
   const int kApiStackSpace = 4;
 
   PrepareCallApiFunction(masm, kApiStackSpace);
 
@@ skipping 53 matching lines @@
     stack_space = argc.immediate() + FCA::kArgsLength + 1;
     stack_space_operand = nullptr;
   }
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, callback_arg,
                            stack_space, stack_space_operand,
                            return_value_operand, &context_restore_operand);
 }
 
 
 void CallApiFunctionStub::Generate(MacroAssembler* masm) {
-  // TODO(dcarney): make rax contain the function address.
   bool call_data_undefined = this->call_data_undefined();
-  CallApiFunctionStubHelper(masm, ParameterCount(rdi), false,
+  CallApiFunctionStubHelper(masm, ParameterCount(rax), false,
                             call_data_undefined);
 }
 
 
 void CallApiAccessorStub::Generate(MacroAssembler* masm) {
   bool is_store = this->is_store();
   int argc = this->argc();
   bool call_data_undefined = this->call_data_undefined();
   CallApiFunctionStubHelper(masm, ParameterCount(argc), is_store,
                             call_data_undefined);
@@ skipping 56 matching lines @@
   CallApiFunctionAndReturn(masm, api_function_address, thunk_ref, getter_arg,
                            kStackSpace, nullptr, return_value_operand, NULL);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64