Create a common subclass for arrays

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index ff13aedcce6f9ba667cccbcdc20b8fd49f4c3f2e..792fdbfad1ea546ab7a74324dd150bf10d1e3029 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -62,17 +62,8 @@
 //           - JSMessageObject
 //         - JSProxy
 //           - JSFunctionProxy
-//       - ByteArray
-//       - ExternalArray
-//         - ExternalPixelArray
-//         - ExternalByteArray
-//         - ExternalUnsignedByteArray
-//         - ExternalShortArray
-//         - ExternalUnsignedShortArray
-//         - ExternalIntArray
-//         - ExternalUnsignedIntArray
-//         - ExternalFloatArray
 //       - FixedArrayBase

[Kevin Millikin (Chromium), 2011/08/11 08:13:06]

I don't like this name, because FixedArray is one of the subclasses.  The sane
thing is to call the base class "FixedArray" and the current FixedArray class
"ObjectArray" (because it contains Objects as elements).  And FixedDoubleArray
could become DoubleArray.

There are some problems with that suggestion.  "Object" is already overloaded to
the point of confusion.  To a much lesser extent, the V8 devs are used to a
specific meaning of "FixedArray".

I can't think of anything better.

[danno, 2011/08/11 13:59:42]

I hate the name, too, but I'd like to fix that in another CL.

On 2011/08/11 08:13:06, Kevin Millikin wrote:

+//         - ByteArray
 //         - FixedArray
 //           - DescriptorArray
 //           - HashTable
@@ -85,6 +76,15 @@
 //           - JSFunctionResultCache
 //           - SerializedScopeInfo
 //         - FixedDoubleArray
+//         - ExternalArray
+//           - ExternalPixelArray
+//           - ExternalByteArray
+//           - ExternalUnsignedByteArray
+//           - ExternalShortArray
+//           - ExternalUnsignedShortArray
+//           - ExternalIntArray
+//           - ExternalUnsignedIntArray
+//           - ExternalFloatArray
 //       - String
 //         - SeqString
 //           - SeqAsciiString
@@ -2084,6 +2084,7 @@ class FixedArrayBase: public HeapObject {
   static const int kHeaderSize = kLengthOffset + kPointerSize;
 };
 
+
 class FixedDoubleArray;
 
 // FixedArray describes fixed-sized arrays with element type Object*.
@@ -3053,12 +3054,8 @@ class NormalizedMapCache: public FixedArray {
 // ByteArray represents fixed sized byte arrays.  Used by the outside world,
 // such as PCRE, and also by the memory allocator and garbage collector to
 // fill in free blocks in the heap.
-class ByteArray: public HeapObject {
+class ByteArray: public FixedArrayBase {
  public:
-  // [length]: length of the array.
-  inline int length();
-  inline void set_length(int value);
-
   // Setter and getter.
   inline byte get(int index);
   inline void set(int index, byte value);
@@ -3103,10 +3100,6 @@ class ByteArray: public HeapObject {
 #endif
 
   // Layout description.
-  // Length is smi tagged when it is stored.
-  static const int kLengthOffset = HeapObject::kHeaderSize;
-  static const int kHeaderSize = kLengthOffset + kPointerSize;
-
   static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);
 
   // Maximal memory consumption for a single ByteArray.
@@ -3130,11 +3123,8 @@ class ByteArray: public HeapObject {
 // Out-of-range values passed to the setter are converted via a C
 // cast, not clamping. Out-of-range indices cause exceptions to be
 // raised rather than being silently ignored.
-class ExternalArray: public HeapObject {
+class ExternalArray: public FixedArrayBase {
  public:
-  // [length]: length of the array.
-  inline int length();
-  inline void set_length(int value);
 
   inline bool is_the_hole(int index) { return false; }
 
@@ -3149,9 +3139,8 @@ class ExternalArray: public HeapObject {
   static const int kMaxLength = 0x3fffffff;
 
   // ExternalArray headers are not quadword aligned.
-  static const int kLengthOffset = HeapObject::kHeaderSize;
   static const int kExternalPointerOffset =
-      POINTER_SIZE_ALIGN(kLengthOffset + kIntSize);
+      POINTER_SIZE_ALIGN(kLengthOffset + kPointerSize);

[Kevin Millikin (Chromium), 2011/08/11 08:13:06]

Hmmm.  Can you write FixedArrayBase::kLengthOffset to be clear where the length
is coming from?

[danno, 2011/08/11 13:59:42]

Done.

   static const int kHeaderSize = kExternalPointerOffset + kPointerSize;
   static const int kAlignedSize = OBJECT_POINTER_ALIGN(kHeaderSize);