Don't MISS if you read the hole from certain FastHoley arrays.

src/arm64/lithium-arm64.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 <sstream>
 
 #include "src/v8.h"
 
 #include "src/arm64/lithium-codegen-arm64.h"
 #include "src/hydrogen-osr.h"
@@ skipping 1706 matching lines @@
           new(zone()) LLoadKeyedFixedDouble(elements, key, temp);
       return instr->RequiresHoleCheck()
           ? AssignEnvironment(DefineAsRegister(result))
           : DefineAsRegister(result);
     } else {
       DCHECK(instr->representation().IsSmiOrTagged() ||
              instr->representation().IsInteger32());
       LOperand* temp = instr->key()->IsConstant() ? NULL : TempRegister();
       LLoadKeyedFixed* result =
           new(zone()) LLoadKeyedFixed(elements, key, temp);
-      return instr->RequiresHoleCheck()
-          ? AssignEnvironment(DefineAsRegister(result))
-          : DefineAsRegister(result);
+      return (instr->RequiresHoleCheck() ||

[Jakob Kummerow, 2015/04/23 13:40:00]

Suggestion: I'd model this after the case below (lines 1740 ff.):

      LInstruction* result =
          DefineAsRegister(new(zone()) LLoadKeyedFixed(elements, key, temp));
      if (instr->RequiresHoleCheck() ||
          (instr->hole_mode == ... && info()->IsStub()) {
        result = AssignEnvironment(result);
      }
      return result;

[mvstanton, 2015/04/27 07:57:12]

Done, and I made the double case above follow the same protocol...looks nicer.

+              (instr->hole_mode() == CONVERT_HOLE_TO_UNDEFINED &&
+               info()->IsStub()))
+                 ? AssignEnvironment(DefineAsRegister(result))
+                 : DefineAsRegister(result);
     }
   } else {
     DCHECK((instr->representation().IsInteger32() &&
             !IsDoubleOrFloatElementsKind(instr->elements_kind())) ||
            (instr->representation().IsDouble() &&
             IsDoubleOrFloatElementsKind(instr->elements_kind())));
 
     LOperand* temp = instr->key()->IsConstant() ? NULL : TempRegister();
     LInstruction* result = DefineAsRegister(
         new(zone()) LLoadKeyedExternal(elements, key, temp));
@@ skipping 1009 matching lines @@
     HAllocateBlockContext* instr) {
   LOperand* context = UseFixed(instr->context(), cp);
   LOperand* function = UseRegisterAtStart(instr->function());
   LAllocateBlockContext* result =
       new(zone()) LAllocateBlockContext(context, function);
   return MarkAsCall(DefineFixed(result, cp), instr);
 }
 
 
 } }  // namespace v8::internal