Optimize the typeof operator.

src/x64/lithium-codegen-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/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 5531 matching lines @@
     __ Push(instr->hydrogen()->shared_info());
     __ PushRoot(pretenure ? Heap::kTrueValueRootIndex :
                             Heap::kFalseValueRootIndex);
     CallRuntime(Runtime::kNewClosure, 3, instr);
   }
 }
 
 
 void LCodeGen::DoTypeof(LTypeof* instr) {
   DCHECK(ToRegister(instr->context()).is(rsi));
-  LOperand* input = instr->value();
-  EmitPushTaggedOperand(input);
-  CallRuntime(Runtime::kTypeof, 1, instr);
+  DCHECK(ToRegister(instr->value()).is(rbx));
+  Label end, do_call;
+  Register value_register = ToRegister(instr->value());
+  __ JumpIfNotSmi(value_register, &do_call);
+  __ Move(rax, isolate()->factory()->number_string());
+  __ jmp(&end);
+  __ bind(&do_call);
+  TypeofStub stub(isolate());
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+  __ bind(&end);
 }
 
 
 void LCodeGen::EmitPushTaggedOperand(LOperand* operand) {
   DCHECK(!operand->IsDoubleRegister());
   if (operand->IsConstantOperand()) {
     __ Push(ToHandle(LConstantOperand::cast(operand)));
   } else if (operand->IsRegister()) {
     __ Push(ToRegister(operand));
   } else {
@@ skipping 380 matching lines @@
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64