[date] Refactor the %_DateField intrinsic to be optimizable.

src/ia32/lithium-codegen-ia32.cc

 // Copyright 2012 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_IA32
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
@@ skipping 1772 matching lines @@
   Register map = ToRegister(instr->value());
   __ EnumLength(result, map);
 }
 
 
 void LCodeGen::DoDateField(LDateField* instr) {
   Register object = ToRegister(instr->date());
   Register result = ToRegister(instr->result());
   Register scratch = ToRegister(instr->temp());
   Smi* index = instr->index();
-  Label runtime, done;
   DCHECK(object.is(result));
   DCHECK(object.is(eax));
 
-  __ test(object, Immediate(kSmiTagMask));
-  DeoptimizeIf(zero, instr, Deoptimizer::kSmi);
-  __ CmpObjectType(object, JS_DATE_TYPE, scratch);
-  DeoptimizeIf(not_equal, instr, Deoptimizer::kNotADateObject);
-
   if (index->value() == 0) {
     __ mov(result, FieldOperand(object, JSDate::kValueOffset));
   } else {
+    Label runtime, done;
     if (index->value() < JSDate::kFirstUncachedField) {
       ExternalReference stamp = ExternalReference::date_cache_stamp(isolate());
       __ mov(scratch, Operand::StaticVariable(stamp));
       __ cmp(scratch, FieldOperand(object, JSDate::kCacheStampOffset));
       __ j(not_equal, &runtime, Label::kNear);
       __ mov(result, FieldOperand(object, JSDate::kValueOffset +
                                           kPointerSize * index->value()));
       __ jmp(&done, Label::kNear);
     }
     __ bind(&runtime);
@@ skipping 4018 matching lines @@
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_IA32