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

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 1776 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(a0));
   DCHECK(result.is(v0));
   DCHECK(!scratch.is(scratch0()));
   DCHECK(!scratch.is(object));
 
-  __ SmiTst(object, at);
-  DeoptimizeIf(eq, instr, Deoptimizer::kSmi, at, Operand(zero_reg));
-  __ GetObjectType(object, scratch, scratch);
-  DeoptimizeIf(ne, instr, Deoptimizer::kNotADateObject, scratch,
-               Operand(JS_DATE_TYPE));
-
   if (index->value() == 0) {
     __ lw(result, FieldMemOperand(object, JSDate::kValueOffset));
   } else {
+    Label runtime, done;
     if (index->value() < JSDate::kFirstUncachedField) {
       ExternalReference stamp = ExternalReference::date_cache_stamp(isolate());
       __ li(scratch, Operand(stamp));
       __ lw(scratch, MemOperand(scratch));
       __ lw(scratch0(), FieldMemOperand(object, JSDate::kCacheStampOffset));
       __ Branch(&runtime, ne, scratch, Operand(scratch0()));
       __ lw(result, FieldMemOperand(object, JSDate::kValueOffset +
                                             kPointerSize * index->value()));
       __ jmp(&done);
     }
@@ skipping 4240 matching lines @@
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8