[collections] Shuffle OrderedHashTable fields around for future optimization

src/objects.h

 // Copyright 2015 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_OBJECTS_H_
 #define V8_OBJECTS_H_
 
 #include <iosfwd>
 #include <memory>
 
@@ skipping 2856 matching lines @@
 
   inline void FillWithHoles(int from, int to);
 
   // Shrink length and insert filler objects.
   void Shrink(int length);
 
   // Copy a sub array from the receiver to dest.
   void CopyTo(int pos, FixedArray* dest, int dest_pos, int len);
 
   // Garbage collection support.
-  static int SizeFor(int length) { return kHeaderSize + length * kPointerSize; }
+  static constexpr int SizeFor(int length) {
+    return kHeaderSize + length * kPointerSize;
+  }
 
   // Code Generation support.
-  static int OffsetOfElementAt(int index) { return SizeFor(index); }
+  static constexpr int OffsetOfElementAt(int index) { return SizeFor(index); }
 
   // Garbage collection support.
   inline Object** RawFieldOfElementAt(int index);
 
   DECLARE_CAST(FixedArray)
 
   // Maximal allowed size, in bytes, of a single FixedArray.
   // Prevents overflowing size computations, as well as extreme memory
   // consumption.
   static const int kMaxSize = 128 * MB * kPointerSize;
@@ skipping 1380 matching lines @@
   }
 
   // When the table is obsolete we store the indexes of the removed holes.
   int RemovedIndexAt(int index) {
     return Smi::cast(get(kRemovedHolesIndex + index))->value();
   }
 
   static const int kNotFound = -1;
   static const int kMinCapacity = 4;
 
-  static const int kNumberOfBucketsIndex = 0;
-  static const int kNumberOfElementsIndex = kNumberOfBucketsIndex + 1;
+  static const int kNumberOfElementsIndex = 0;
+  // The next table is stored at the same index as the nof elements.
+  static const int kNextTableIndex = kNumberOfElementsIndex;
   static const int kNumberOfDeletedElementsIndex = kNumberOfElementsIndex + 1;
-  static const int kHashTableStartIndex = kNumberOfDeletedElementsIndex + 1;
-  static const int kNextTableIndex = kNumberOfElementsIndex;
+  static const int kNumberOfBucketsIndex = kNumberOfDeletedElementsIndex + 1;
+  static const int kHashTableStartIndex = kNumberOfBucketsIndex + 1;
 
-  static const int kNumberOfBucketsOffset =
-      kHeaderSize + kNumberOfBucketsIndex * kPointerSize;
-  static const int kNumberOfElementsOffset =
-      kHeaderSize + kNumberOfElementsIndex * kPointerSize;
-  static const int kNumberOfDeletedElementsOffset =
-      kHeaderSize + kNumberOfDeletedElementsIndex * kPointerSize;
-  static const int kHashTableStartOffset =
-      kHeaderSize + kHashTableStartIndex * kPointerSize;
-  static const int kNextTableOffset =
-      kHeaderSize + kNextTableIndex * kPointerSize;
+  static constexpr const int kNumberOfElementsOffset =
+      FixedArray::OffsetOfElementAt(kNumberOfElementsIndex);
+  static constexpr const int kNextTableOffset =
+      FixedArray::OffsetOfElementAt(kNextTableIndex);
+  static constexpr const int kNumberOfDeletedElementsOffset =
+      FixedArray::OffsetOfElementAt(kNumberOfDeletedElementsIndex);
+  static constexpr const int kNumberOfBucketsOffset =
+      FixedArray::OffsetOfElementAt(kNumberOfBucketsIndex);
+  static constexpr const int kHashTableStartOffset =
+      FixedArray::OffsetOfElementAt(kHashTableStartIndex);
 
   static const int kEntrySize = entrysize + 1;
   static const int kChainOffset = entrysize;
 
   static const int kLoadFactor = 2;
 
   // NumberOfDeletedElements is set to kClearedTableSentinel when
   // the table is cleared, which allows iterator transitions to
   // optimize that case.
   static const int kClearedTableSentinel = -1;
@@ skipping 7390 matching lines @@
   }
 };
 
 
 }  // NOLINT, false-positive due to second-order macros.
 }  // NOLINT, false-positive due to second-order macros.
 
 #include "src/objects/object-macros-undef.h"
 
 #endif  // V8_OBJECTS_H_