Allow specifying base offset when constructing Keyed hydrogen instructions

src/elements-kind.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 "elements-kind.h"
 
 #include "api.h"
 #include "elements.h"
 #include "objects.h"
 
@@ skipping 33 matching lines @@
     case FAST_HOLEY_ELEMENTS:
     case DICTIONARY_ELEMENTS:
     case SLOPPY_ARGUMENTS_ELEMENTS:
       return kPointerSizeLog2;
   }
   UNREACHABLE();
   return 0;
 }
 
 
+int GetDefaultHeaderSizeForElementsKind(ElementsKind elements_kind) {
+  return IsExternalArrayElementsKind(elements_kind)
+      ? 0 : (FixedArray::kHeaderSize - kSmiTagSize);
+}
+
+
 const char* ElementsKindToString(ElementsKind kind) {
   ElementsAccessor* accessor = ElementsAccessor::ForKind(kind);
   return accessor->name();
 }
 
 
 void PrintElementsKind(FILE* out, ElementsKind kind) {
   PrintF(out, "%s", ElementsKindToString(kind));
 }
 
@@ skipping 131 matching lines @@
         return false;
       default:
         return false;
     }
   }
   return false;
 }
 
 
 } }  // namespace v8::internal