X87: fix performance regression on intel call api stubs

src/x87/code-stubs-x87.cc

Index: src/x87/code-stubs-x87.cc
diff --git a/src/x87/code-stubs-x87.cc b/src/x87/code-stubs-x87.cc
index 28baf49fabc314eab7ba8d389d82c1cde94a60fe..c2bf5e97b8e8b41e0fb34b75d8e648e38308081e 100644
--- a/src/x87/code-stubs-x87.cc
+++ b/src/x87/code-stubs-x87.cc
@@ -4543,12 +4543,12 @@ static void CallApiFunctionStubHelper(MacroAssembler* masm,
                                       bool return_first_arg,
                                       bool call_data_undefined) {
   // ----------- S t a t e -------------
-  //  -- eax                 : callee
+  //  -- edi                 : callee
   //  -- ebx                 : call_data
   //  -- ecx                 : holder
   //  -- edx                 : api_function_address
   //  -- esi                 : context
-  //  -- edi                 : number of arguments if argc is a register
+  //  -- eax                 : number of arguments if argc is a register
   //  --
   //  -- esp[0]              : return address
   //  -- esp[4]              : last argument
@@ -4557,11 +4557,12 @@ static void CallApiFunctionStubHelper(MacroAssembler* masm,
   //  -- esp[(argc + 1) * 4] : receiver
   // -----------------------------------
 
-  Register callee = eax;
+  Register callee = edi;
   Register call_data = ebx;
   Register holder = ecx;
   Register api_function_address = edx;
   Register context = esi;
+  Register return_address = eax;
 
   typedef FunctionCallbackArguments FCA;
 
@@ -4574,10 +4575,17 @@ static void CallApiFunctionStubHelper(MacroAssembler* masm,
   STATIC_ASSERT(FCA::kHolderIndex == 0);
   STATIC_ASSERT(FCA::kArgsLength == 7);
 
-  DCHECK(argc.is_immediate() || edi.is(argc.reg()));
+  DCHECK(argc.is_immediate() || eax.is(argc.reg()));
 
-  // pop return address and save context
-  __ xchg(context, Operand(esp, 0));
+  if (argc.is_immediate()) {
+    __ pop(return_address);
+    // context save.
+    __ push(context);
+  } else {
+    // pop return address and save context
+    __ xchg(context, Operand(esp, 0));
+    return_address = context;
+  }
 
   // callee
   __ push(callee);
@@ -4605,7 +4613,7 @@ static void CallApiFunctionStubHelper(MacroAssembler* masm,
   __ mov(scratch, esp);
 
   // push return address
-  __ push(context);
+  __ push(return_address);
 
   // load context from callee
   __ mov(context, FieldOperand(callee, JSFunction::kContextOffset));
@@ -4678,9 +4686,8 @@ static void CallApiFunctionStubHelper(MacroAssembler* masm,
 
 
 void CallApiFunctionStub::Generate(MacroAssembler* masm) {
-  // TODO(dcarney): make eax contain the function address.
   bool call_data_undefined = this->call_data_undefined();
-  CallApiFunctionStubHelper(masm, ParameterCount(edi), false,
+  CallApiFunctionStubHelper(masm, ParameterCount(eax), false,
                             call_data_undefined);
 }