diff --git a/src/arm/lithium-codegen-arm.cc b/src/arm/lithium-codegen-arm.cc
index c6b40ee46d..33b6731633 100644
--- a/src/arm/lithium-codegen-arm.cc
+++ b/src/arm/lithium-codegen-arm.cc
@@ -46,7 +46,7 @@ class SafepointGenerator : public CallWrapper {
         deoptimization_index_(deoptimization_index) { }
   virtual ~SafepointGenerator() { }
 
-  virtual void BeforeCall(int call_size) {
+  virtual void BeforeCall(int call_size) const {
     ASSERT(call_size >= 0);
     // Ensure that we have enough space after the previous safepoint position
     // for the generated code there.
@@ -63,7 +63,7 @@ class SafepointGenerator : public CallWrapper {
     }
   }
 
-  virtual void AfterCall() {
+  virtual void AfterCall() const {
     codegen_->RecordSafepoint(pointers_, deoptimization_index_);
   }
 
@@ -2641,7 +2641,7 @@ void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
   // The number of arguments is stored in receiver which is r0, as expected
   // by InvokeFunction.
   v8::internal::ParameterCount actual(receiver);
-  __ InvokeFunction(function, actual, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeFunction(function, actual, CALL_FUNCTION, safepoint_generator);
   __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
 }
 
@@ -3084,7 +3084,7 @@ void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
   RegisterEnvironmentForDeoptimization(env);
   SafepointGenerator generator(this, pointers, env->deoptimization_index());
   ParameterCount count(instr->arity());
-  __ InvokeFunction(r1, count, CALL_FUNCTION, &generator);
+  __ InvokeFunction(r1, count, CALL_FUNCTION, generator);
   __ ldr(cp, MemOperand(fp, StandardFrameConstants::kContextOffset));
 }
 
@@ -4256,7 +4256,7 @@ void LCodeGen::DoDeleteProperty(LDeleteProperty* instr) {
   SafepointGenerator safepoint_generator(this,
                                          pointers,
                                          env->deoptimization_index());
-  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -4272,7 +4272,7 @@ void LCodeGen::DoIn(LIn* instr) {
   SafepointGenerator safepoint_generator(this,
                                          pointers,
                                          env->deoptimization_index());
-  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index eeaba733ee..3f2b01ea2c 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -886,7 +886,7 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
                                     Register code_reg,
                                     Label* done,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   bool definitely_matches = false;
   Label regular_invoke;
 
@@ -941,11 +941,9 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
     Handle<Code> adaptor =
         isolate()->builtins()->ArgumentsAdaptorTrampoline();
     if (flag == CALL_FUNCTION) {
-      if (call_wrapper != NULL) {
-        call_wrapper->BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
-      }
+      call_wrapper.BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
       Call(adaptor, RelocInfo::CODE_TARGET);
-      if (call_wrapper != NULL) call_wrapper->AfterCall();
+      call_wrapper.AfterCall();
       b(done);
     } else {
       Jump(adaptor, RelocInfo::CODE_TARGET);
@@ -959,15 +957,15 @@ void MacroAssembler::InvokeCode(Register code,
                                 const ParameterCount& expected,
                                 const ParameterCount& actual,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   Label done;
 
   InvokePrologue(expected, actual, Handle<Code>::null(), code, &done, flag,
                  call_wrapper);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(code));
+    call_wrapper.BeforeCall(CallSize(code));
     Call(code);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     Jump(code);
@@ -1002,7 +1000,7 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
 void MacroAssembler::InvokeFunction(Register fun,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   // Contract with called JS functions requires that function is passed in r1.
   ASSERT(fun.is(r1));
 
@@ -2314,12 +2312,12 @@ MaybeObject* MacroAssembler::TryJumpToExternalReference(
 
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id,
                                    InvokeFlag flag,
-                                   CallWrapper* call_wrapper) {
+                                   const CallWrapper& call_wrapper) {
   GetBuiltinEntry(r2, id);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(r2));
+    call_wrapper.BeforeCall(CallSize(r2));
     Call(r2);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     Jump(r2);
diff --git a/src/arm/macro-assembler-arm.h b/src/arm/macro-assembler-arm.h
index ba35769d8c..ca6b015714 100644
--- a/src/arm/macro-assembler-arm.h
+++ b/src/arm/macro-assembler-arm.h
@@ -350,7 +350,7 @@ class MacroAssembler: public Assembler {
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeCode(Handle<Code> code,
                   const ParameterCount& expected,
@@ -363,7 +363,7 @@ class MacroAssembler: public Assembler {
   void InvokeFunction(Register function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeFunction(JSFunction* function,
                       const ParameterCount& actual,
@@ -799,7 +799,7 @@ class MacroAssembler: public Assembler {
   // the unresolved list if the name does not resolve.
   void InvokeBuiltin(Builtins::JavaScript id,
                      InvokeFlag flag,
-                     CallWrapper* call_wrapper = NULL);
+                     const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Store the code object for the given builtin in the target register and
   // setup the function in r1.
@@ -1002,7 +1002,7 @@ class MacroAssembler: public Assembler {
                       Register code_reg,
                       Label* done,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Activation support.
   void EnterFrame(StackFrame::Type type);
diff --git a/src/assembler.h b/src/assembler.h
index 4cc352b819..ef4ddc0cda 100644
--- a/src/assembler.h
+++ b/src/assembler.h
@@ -852,9 +852,17 @@ class CallWrapper {
   virtual ~CallWrapper() { }
   // Called just before emitting a call. Argument is the size of the generated
   // call code.
-  virtual void BeforeCall(int call_size) = 0;
+  virtual void BeforeCall(int call_size) const = 0;
   // Called just after emitting a call, i.e., at the return site for the call.
-  virtual void AfterCall() = 0;
+  virtual void AfterCall() const = 0;
+};
+
+class NullCallWrapper : public CallWrapper {
+ public:
+  NullCallWrapper() { }
+  virtual ~NullCallWrapper() { }
+  virtual void BeforeCall(int call_size) const { }
+  virtual void AfterCall() const { }
 };
 
 } }  // namespace v8::internal
diff --git a/src/ia32/lithium-codegen-ia32.cc b/src/ia32/lithium-codegen-ia32.cc
index c94b6563c4..25138df9de 100644
--- a/src/ia32/lithium-codegen-ia32.cc
+++ b/src/ia32/lithium-codegen-ia32.cc
@@ -50,9 +50,9 @@ class SafepointGenerator : public CallWrapper {
         deoptimization_index_(deoptimization_index) {}
   virtual ~SafepointGenerator() { }
 
-  virtual void BeforeCall(int call_size) {}
+  virtual void BeforeCall(int call_size) const {}
 
-  virtual void AfterCall() {
+  virtual void AfterCall() const {
     codegen_->RecordSafepoint(pointers_, deoptimization_index_);
   }
 
@@ -2552,7 +2552,7 @@ void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
                                          pointers,
                                          env->deoptimization_index());
   ParameterCount actual(eax);
-  __ InvokeFunction(function, actual, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeFunction(function, actual, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -2974,7 +2974,7 @@ void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
   RegisterEnvironmentForDeoptimization(env);
   SafepointGenerator generator(this, pointers, env->deoptimization_index());
   ParameterCount count(instr->arity());
-  __ InvokeFunction(edi, count, CALL_FUNCTION, &generator);
+  __ InvokeFunction(edi, count, CALL_FUNCTION, generator);
 }
 
 
@@ -4237,7 +4237,7 @@ void LCodeGen::DoDeleteProperty(LDeleteProperty* instr) {
                                          env->deoptimization_index());
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
   __ push(Immediate(Smi::FromInt(strict_mode_flag())));
-  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -4297,7 +4297,7 @@ void LCodeGen::DoIn(LIn* instr) {
                                          pointers,
                                          env->deoptimization_index());
   __ mov(esi, Operand(ebp, StandardFrameConstants::kContextOffset));
-  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
diff --git a/src/ia32/macro-assembler-ia32.cc b/src/ia32/macro-assembler-ia32.cc
index 92464b7679..f13585d0d6 100644
--- a/src/ia32/macro-assembler-ia32.cc
+++ b/src/ia32/macro-assembler-ia32.cc
@@ -1435,7 +1435,7 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
                                     const Operand& code_operand,
                                     NearLabel* done,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   bool definitely_matches = false;
   Label invoke;
   if (expected.is_immediate()) {
@@ -1485,11 +1485,9 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
     }
 
     if (flag == CALL_FUNCTION) {
-      if (call_wrapper != NULL) {
-        call_wrapper->BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
-      }
+      call_wrapper.BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
       call(adaptor, RelocInfo::CODE_TARGET);
-      if (call_wrapper != NULL) call_wrapper->AfterCall();
+      call_wrapper.AfterCall();
       jmp(done);
     } else {
       jmp(adaptor, RelocInfo::CODE_TARGET);
@@ -1503,14 +1501,14 @@ void MacroAssembler::InvokeCode(const Operand& code,
                                 const ParameterCount& expected,
                                 const ParameterCount& actual,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   NearLabel done;
   InvokePrologue(expected, actual, Handle<Code>::null(), code,
                  &done, flag, call_wrapper);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(code));
+    call_wrapper.BeforeCall(CallSize(code));
     call(code);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     jmp(code);
@@ -1524,14 +1522,14 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
                                 const ParameterCount& actual,
                                 RelocInfo::Mode rmode,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   NearLabel done;
   Operand dummy(eax);
   InvokePrologue(expected, actual, code, dummy, &done, flag, call_wrapper);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(code, rmode));
+    call_wrapper.BeforeCall(CallSize(code, rmode));
     call(code, rmode);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     jmp(code, rmode);
@@ -1543,7 +1541,7 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
 void MacroAssembler::InvokeFunction(Register fun,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   ASSERT(fun.is(edi));
   mov(edx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
   mov(esi, FieldOperand(edi, JSFunction::kContextOffset));
@@ -1559,7 +1557,7 @@ void MacroAssembler::InvokeFunction(Register fun,
 void MacroAssembler::InvokeFunction(JSFunction* function,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   ASSERT(function->is_compiled());
   // Get the function and setup the context.
   mov(edi, Immediate(Handle<JSFunction>(function)));
@@ -1582,7 +1580,7 @@ void MacroAssembler::InvokeFunction(JSFunction* function,
 
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id,
                                    InvokeFlag flag,
-                                   CallWrapper* call_wrapper) {
+                                   const CallWrapper& call_wrapper) {
   // Calls are not allowed in some stubs.
   ASSERT(flag == JUMP_FUNCTION || allow_stub_calls());
 
diff --git a/src/ia32/macro-assembler-ia32.h b/src/ia32/macro-assembler-ia32.h
index cb0081bdb4..ee8c0c79b6 100644
--- a/src/ia32/macro-assembler-ia32.h
+++ b/src/ia32/macro-assembler-ia32.h
@@ -157,32 +157,32 @@ class MacroAssembler: public Assembler {
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeCode(Handle<Code> code,
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   RelocInfo::Mode rmode,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Invoke the JavaScript function in the given register. Changes the
   // current context to the context in the function before invoking.
   void InvokeFunction(Register function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeFunction(JSFunction* function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Invoke specified builtin JavaScript function. Adds an entry to
   // the unresolved list if the name does not resolve.
   void InvokeBuiltin(Builtins::JavaScript id,
                      InvokeFlag flag,
-                     CallWrapper* call_wrapper = NULL);
+                     const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Store the function for the given builtin in the target register.
   void GetBuiltinFunction(Register target, Builtins::JavaScript id);
@@ -649,7 +649,7 @@ class MacroAssembler: public Assembler {
                       const Operand& code_operand,
                       NearLabel* done,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Activation support.
   void EnterFrame(StackFrame::Type type);
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 03e243ccd9..f24ed6ff0e 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -2255,7 +2255,7 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
                                     Register code_reg,
                                     Label* done,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   bool definitely_matches = false;
   Label regular_invoke;
 
@@ -2308,11 +2308,9 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
     Handle<Code> adaptor =
         isolate()->builtins()->ArgumentsAdaptorTrampoline();
     if (flag == CALL_FUNCTION) {
-      if (call_wrapper != NULL) {
-        call_wrapper->BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
-      }
+      call_wrapper.BeforeCall(CallSize(adaptor, RelocInfo::CODE_TARGET));
       Call(adaptor, RelocInfo::CODE_TARGET);
-      if (call_wrapper != NULL) call_wrapper->AfterCall();
+      call_wrapper.AfterCall();
       jmp(done);
     } else {
       Jump(adaptor, RelocInfo::CODE_TARGET);
@@ -2326,7 +2324,7 @@ void MacroAssembler::InvokeCode(Register code,
                                 const ParameterCount& expected,
                                 const ParameterCount& actual,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   Label done;
 
   InvokePrologue(expected, actual, Handle<Code>::null(), code, &done, flag,
@@ -2365,7 +2363,7 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
 void MacroAssembler::InvokeFunction(Register function,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   // Contract with called JS functions requires that function is passed in a1.
   ASSERT(function.is(a1));
   Register expected_reg = a2;
@@ -2657,12 +2655,12 @@ void MacroAssembler::JumpToExternalReference(const ExternalReference& builtin) {
 
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id,
                                    InvokeFlag flag,
-                                   CallWrapper* call_wrapper) {
+                                   const CallWrapper& call_wrapper) {
   GetBuiltinEntry(t9, id);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(t9));
+    call_wrapper.BeforeCall(CallSize(t9));
     Call(t9);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     Jump(t9);
diff --git a/src/mips/macro-assembler-mips.h b/src/mips/macro-assembler-mips.h
index 0e6393cee7..266ef71297 100644
--- a/src/mips/macro-assembler-mips.h
+++ b/src/mips/macro-assembler-mips.h
@@ -587,7 +587,7 @@ DECLARE_NOTARGET_PROTOTYPE(Ret)
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeCode(Handle<Code> code,
                   const ParameterCount& expected,
@@ -600,7 +600,7 @@ DECLARE_NOTARGET_PROTOTYPE(Ret)
   void InvokeFunction(Register function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeFunction(JSFunction* function,
                       const ParameterCount& actual,
@@ -770,7 +770,7 @@ DECLARE_NOTARGET_PROTOTYPE(Ret)
   // the unresolved list if the name does not resolve.
   void InvokeBuiltin(Builtins::JavaScript id,
                      InvokeFlag flag,
-                     CallWrapper* call_wrapper = NULL);
+                     const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Store the code object for the given builtin in the target register and
   // setup the function in a1.
@@ -953,7 +953,7 @@ DECLARE_NOTARGET_PROTOTYPE(Ret)
                       Register code_reg,
                       Label* done,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Get the code for the given builtin. Returns if able to resolve
   // the function in the 'resolved' flag.
diff --git a/src/x64/lithium-codegen-x64.cc b/src/x64/lithium-codegen-x64.cc
index 388d69814d..5b45b136e7 100644
--- a/src/x64/lithium-codegen-x64.cc
+++ b/src/x64/lithium-codegen-x64.cc
@@ -49,7 +49,7 @@ class SafepointGenerator : public CallWrapper {
         deoptimization_index_(deoptimization_index) { }
   virtual ~SafepointGenerator() { }
 
-  virtual void BeforeCall(int call_size) {
+  virtual void BeforeCall(int call_size) const {
     ASSERT(call_size >= 0);
     // Ensure that we have enough space after the previous safepoint position
     // for the jump generated there.
@@ -62,7 +62,7 @@ class SafepointGenerator : public CallWrapper {
     }
   }
 
-  virtual void AfterCall() {
+  virtual void AfterCall() const {
     codegen_->RecordSafepoint(pointers_, deoptimization_index_);
   }
 
@@ -2562,7 +2562,7 @@ void LCodeGen::DoApplyArguments(LApplyArguments* instr) {
                                          pointers,
                                          env->deoptimization_index());
   v8::internal::ParameterCount actual(rax);
-  __ InvokeFunction(function, actual, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeFunction(function, actual, CALL_FUNCTION, safepoint_generator);
   __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
 }
 
@@ -2969,7 +2969,7 @@ void LCodeGen::DoInvokeFunction(LInvokeFunction* instr) {
   RegisterEnvironmentForDeoptimization(env);
   SafepointGenerator generator(this, pointers, env->deoptimization_index());
   ParameterCount count(instr->arity());
-  __ InvokeFunction(rdi, count, CALL_FUNCTION, &generator);
+  __ InvokeFunction(rdi, count, CALL_FUNCTION, generator);
   __ movq(rsi, Operand(rbp, StandardFrameConstants::kContextOffset));
 }
 
@@ -4046,7 +4046,7 @@ void LCodeGen::DoDeleteProperty(LDeleteProperty* instr) {
                                          pointers,
                                          env->deoptimization_index());
   __ Push(Smi::FromInt(strict_mode_flag()));
-  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::DELETE, CALL_FUNCTION, safepoint_generator);
 }
 
 
@@ -4066,7 +4066,7 @@ void LCodeGen::DoIn(LIn* instr) {
   SafepointGenerator safepoint_generator(this,
                                          pointers,
                                          env->deoptimization_index());
-  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, &safepoint_generator);
+  __ InvokeBuiltin(Builtins::IN, CALL_FUNCTION, safepoint_generator);
 }
 
 
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index 24f2fefcd8..5cf959fcd8 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -755,7 +755,7 @@ MaybeObject* MacroAssembler::TryJumpToExternalReference(
 
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id,
                                    InvokeFlag flag,
-                                   CallWrapper* call_wrapper) {
+                                   const CallWrapper& call_wrapper) {
   // Calls are not allowed in some stubs.
   ASSERT(flag == JUMP_FUNCTION || allow_stub_calls());
 
@@ -2056,7 +2056,7 @@ void MacroAssembler::InvokeCode(Register code,
                                 const ParameterCount& expected,
                                 const ParameterCount& actual,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   NearLabel done;
   InvokePrologue(expected,
                  actual,
@@ -2066,9 +2066,9 @@ void MacroAssembler::InvokeCode(Register code,
                  flag,
                  call_wrapper);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(code));
+    call_wrapper.BeforeCall(CallSize(code));
     call(code);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     jmp(code);
@@ -2082,7 +2082,7 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
                                 const ParameterCount& actual,
                                 RelocInfo::Mode rmode,
                                 InvokeFlag flag,
-                                CallWrapper* call_wrapper) {
+                                const CallWrapper& call_wrapper) {
   NearLabel done;
   Register dummy = rax;
   InvokePrologue(expected,
@@ -2093,9 +2093,9 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
                  flag,
                  call_wrapper);
   if (flag == CALL_FUNCTION) {
-    if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(code));
+    call_wrapper.BeforeCall(CallSize(code));
     Call(code, rmode);
-    if (call_wrapper != NULL) call_wrapper->AfterCall();
+    call_wrapper.AfterCall();
   } else {
     ASSERT(flag == JUMP_FUNCTION);
     Jump(code, rmode);
@@ -2107,7 +2107,7 @@ void MacroAssembler::InvokeCode(Handle<Code> code,
 void MacroAssembler::InvokeFunction(Register function,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   ASSERT(function.is(rdi));
   movq(rdx, FieldOperand(function, JSFunction::kSharedFunctionInfoOffset));
   movq(rsi, FieldOperand(function, JSFunction::kContextOffset));
@@ -2125,7 +2125,7 @@ void MacroAssembler::InvokeFunction(Register function,
 void MacroAssembler::InvokeFunction(JSFunction* function,
                                     const ParameterCount& actual,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   ASSERT(function->is_compiled());
   // Get the function and setup the context.
   Move(rdi, Handle<JSFunction>(function));
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index db8bfb9867..400bdce3dc 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -244,32 +244,32 @@ class MacroAssembler: public Assembler {
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeCode(Handle<Code> code,
                   const ParameterCount& expected,
                   const ParameterCount& actual,
                   RelocInfo::Mode rmode,
                   InvokeFlag flag,
-                  CallWrapper* call_wrapper = NULL);
+                  const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Invoke the JavaScript function in the given register. Changes the
   // current context to the context in the function before invoking.
   void InvokeFunction(Register function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   void InvokeFunction(JSFunction* function,
                       const ParameterCount& actual,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper = NULL);
+                      const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Invoke specified builtin JavaScript function. Adds an entry to
   // the unresolved list if the name does not resolve.
   void InvokeBuiltin(Builtins::JavaScript id,
                      InvokeFlag flag,
-                     CallWrapper* call_wrapper = NULL);
+                     const CallWrapper& call_wrapper = NullCallWrapper());
 
   // Store the function for the given builtin in the target register.
   void GetBuiltinFunction(Register target, Builtins::JavaScript id);
@@ -1126,7 +1126,7 @@ class MacroAssembler: public Assembler {
                       Register code_register,
                       LabelType* done,
                       InvokeFlag flag,
-                      CallWrapper* call_wrapper);
+                      const CallWrapper& call_wrapper);
 
   // Activation support.
   void EnterFrame(StackFrame::Type type);
@@ -1936,7 +1936,7 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
                                     Register code_register,
                                     LabelType* done,
                                     InvokeFlag flag,
-                                    CallWrapper* call_wrapper) {
+                                    const CallWrapper& call_wrapper) {
   bool definitely_matches = false;
   NearLabel invoke;
   if (expected.is_immediate()) {
@@ -1985,9 +1985,9 @@ void MacroAssembler::InvokePrologue(const ParameterCount& expected,
     }
 
     if (flag == CALL_FUNCTION) {
-      if (call_wrapper != NULL) call_wrapper->BeforeCall(CallSize(adaptor));
+      call_wrapper.BeforeCall(CallSize(adaptor));
       Call(adaptor, RelocInfo::CODE_TARGET);
-      if (call_wrapper != NULL) call_wrapper->AfterCall();
+      call_wrapper.AfterCall();
       jmp(done);
     } else {
       Jump(adaptor, RelocInfo::CODE_TARGET);