Hydrogenized KeyedLoadGeneric stub: Fix FieldIndex::GetLoadByFieldIndex()

src/field-index.h

 // Copyright 2014 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.
 
 #ifndef V8_FIELD_INDEX_H_
 #define V8_FIELD_INDEX_H_
 
 #include "src/property-details.h"
 #include "src/utils.h"
 
@@ skipping 10 matching lines @@
  public:
   static FieldIndex ForPropertyIndex(Map* map,
                                      int index,
                                      bool is_double = false);
   static FieldIndex ForInObjectOffset(int offset, Map* map = NULL);
   static FieldIndex ForLookupResult(const LookupResult* result);
   static FieldIndex ForDescriptor(Map* map, int descriptor_index);
   static FieldIndex ForLoadByFieldIndex(Map* map, int index);
   static FieldIndex ForKeyedLookupCacheIndex(Map* map, int index);
 
+  int GetLoadByFieldIndex() const;
+
   bool is_inobject() const {
     return IsInObjectBits::decode(bit_field_);
   }
 
   bool is_double() const {
     return IsDoubleBits::decode(bit_field_);
   }
 
   int offset() const {
     return index() * kPointerSize;
   }
 
+  // Zero-indexed from beginning of the object.
   int index() const {
     return IndexBits::decode(bit_field_);
   }
 
   int outobject_array_index() const {
     ASSERT(!is_inobject());
     return index() - first_inobject_property_offset() / kPointerSize;
   }
 
+  // Zero-based from the first inobject property. Overflows to out-of-object
+  // properties.
   int property_index() const {
     ASSERT(!IsHiddenField::decode(bit_field_));
     int result = index() - first_inobject_property_offset() / kPointerSize;
     if (!is_inobject()) {
       result += InObjectPropertyBits::decode(bit_field_);
     }
     return result;
   }
 
-  int GetLoadByFieldIndex() const {
-    // For efficiency, the LoadByFieldIndex instruction takes an index that is
-    // optimized for quick access. If the property is inline, the index is
-    // positive. If it's out-of-line, the encoded index is -raw_index - 1 to
-    // disambiguate the zero out-of-line index from the zero inobject case.
-    // The index itself is shifted up by one bit, the lower-most bit
-    // signifying if the field is a mutable double box (1) or not (0).
-    int result = index() - first_inobject_property_offset() / kPointerSize;
-    if (!is_inobject()) {
-      result = -result - 1;
-    }
-    result <<= 1;
-    return is_double() ? (result | 1) : result;
-  }
-
   int GetKeyedLookupCacheIndex() const;
 
   int GetLoadFieldStubKey() const {
     return bit_field_ &
         (IsInObjectBits::kMask | IsDoubleBits::kMask | IndexBits::kMask);
   }
 
  private:
   FieldIndex(bool is_inobject, int local_index, bool is_double,
              int inobject_properties, int first_inobject_property_offset,
              bool is_hidden = false) {
     ASSERT((first_inobject_property_offset & (kPointerSize - 1)) == 0);
     bit_field_ = IsInObjectBits::encode(is_inobject) |
       IsDoubleBits::encode(is_double) |
       FirstInobjectPropertyOffsetBits::encode(first_inobject_property_offset) |
       IsHiddenField::encode(is_hidden) |
       IndexBits::encode(local_index) |
       InObjectPropertyBits::encode(inobject_properties);
   }
 
   int first_inobject_property_offset() const {
     ASSERT(!IsHiddenField::decode(bit_field_));
     return FirstInobjectPropertyOffsetBits::decode(bit_field_);
   }
 
   static const int kIndexBitsSize = kDescriptorIndexBitCount + 1;
 
+  // Index from beginning of object.
   class IndexBits: public BitField<int, 0, kIndexBitsSize> {};
   class IsInObjectBits: public BitField<bool, IndexBits::kNext, 1> {};
   class IsDoubleBits: public BitField<bool, IsInObjectBits::kNext, 1> {};
+  // Number of inobject properties.
   class InObjectPropertyBits: public BitField<int, IsDoubleBits::kNext,
                                               kDescriptorIndexBitCount> {};
+  // Offset of first inobject property from beginning of object.
   class FirstInobjectPropertyOffsetBits:
       public BitField<int, InObjectPropertyBits::kNext, 7> {};
   class IsHiddenField:
       public BitField<bool, FirstInobjectPropertyOffsetBits::kNext, 1> {};
   STATIC_ASSERT(IsHiddenField::kNext <= 32);
 
   int bit_field_;
 };
 
 } }  // namespace v8::internal
 
 #endif