Reland "Add basic crankshaft support for slow-mode for-in to avoid disabling optimizations"

src/mips64/lithium-codegen-mips64.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"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/cpu-profiler.h"
 #include "src/hydrogen-osr.h"
@@ skipping 5862 matching lines @@
   DCHECK(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
 
   GenerateOsrPrologue();
 }
 
 
 void LCodeGen::DoForInPrepareMap(LForInPrepareMap* instr) {
   Register result = ToRegister(instr->result());
   Register object = ToRegister(instr->object());
-  __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
-  DeoptimizeIf(eq, instr, Deoptimizer::kUndefined, object, Operand(at));
-
-  Register null_value = a5;
-  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
-  DeoptimizeIf(eq, instr, Deoptimizer::kNull, object, Operand(null_value));
 
   __ And(at, object, kSmiTagMask);
   DeoptimizeIf(eq, instr, Deoptimizer::kSmi, at, Operand(zero_reg));
 
   STATIC_ASSERT(FIRST_JS_PROXY_TYPE == FIRST_SPEC_OBJECT_TYPE);
   __ GetObjectType(object, a1, a1);
   DeoptimizeIf(le, instr, Deoptimizer::kNotAJavaScriptObject, a1,
                Operand(LAST_JS_PROXY_TYPE));
 
   Label use_cache, call_runtime;
   DCHECK(object.is(a0));
+  Register null_value = a5;
+  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ CheckEnumCache(null_value, &call_runtime);
 
   __ ld(result, FieldMemOperand(object, HeapObject::kMapOffset));
   __ Branch(&use_cache);
 
   // Get the set of properties to enumerate.
   __ bind(&call_runtime);
   __ push(object);
   CallRuntime(Runtime::kGetPropertyNamesFast, 1, instr);
 
@@ skipping 118 matching lines @@
   __ li(at, scope_info);
   __ Push(at, ToRegister(instr->function()));
   CallRuntime(Runtime::kPushBlockContext, 2, instr);
   RecordSafepoint(Safepoint::kNoLazyDeopt);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal