Optimize the typeof operator.

src/mips/lithium-codegen-mips.cc

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 5547 matching lines @@
     __ li(a2, Operand(instr->hydrogen()->shared_info()));
     __ li(a1, Operand(pretenure ? factory()->true_value()
                                 : factory()->false_value()));
     __ Push(cp, a2, a1);
     CallRuntime(Runtime::kNewClosure, 3, instr);
   }
 }
 
 
 void LCodeGen::DoTypeof(LTypeof* instr) {
+  DCHECK(ToRegister(instr->value()).is(a3));
   DCHECK(ToRegister(instr->result()).is(v0));
-  Register input = ToRegister(instr->value());
-  __ push(input);
-  CallRuntime(Runtime::kTypeof, 1, instr);
+  Label end, do_call;
+  Register value_register = ToRegister(instr->value());
+  __ JumpIfNotSmi(value_register, &do_call);
+  __ li(v0, Operand(isolate()->factory()->number_string()));
+  __ jmp(&end);
+  __ bind(&do_call);
+  TypeofStub stub(isolate());
+  CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
+  __ bind(&end);
 }
 
 
 void LCodeGen::DoTypeofIsAndBranch(LTypeofIsAndBranch* instr) {
   Register input = ToRegister(instr->value());
 
   Register cmp1 = no_reg;
   Operand cmp2 = Operand(no_reg);
 
   Condition final_branch_condition = EmitTypeofIs(instr->TrueLabel(chunk_),
@@ skipping 411 matching lines @@
   __ li(at, scope_info);
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal