Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1997-2006 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 // arrayOopDesc is the abstract baseclass for all arrays.

 class arrayOopDesc : public oopDesc {

   friend class VMStructs;

  private:

   int _length; // number of elements in the array

  public:

   // Interpreter/Compiler offsets

   static int length_offset_in_bytes()             { return offset_of(arrayOopDesc, _length); }

   static int base_offset_in_bytes(BasicType type) { return header_size(type) * HeapWordSize; }

   // Returns the address of the first element.

   void* base(BasicType type) const              { return (void*) (((intptr_t) this) + base_offset_in_bytes(type)); }

   // Tells whether index is within bounds.

   bool is_within_bounds(int index) const        { return 0 <= index && index < length(); }

   // Accessores for instance variable

   int length() const                            { return _length;   }

   void set_length(int length)                   { _length = length; }

   // Header size computation.

   // Should only be called with constants as argument (will not constant fold otherwise)

   static int header_size(BasicType type) {

     return Universe::element_type_should_be_aligned(type)

       ? align_object_size(sizeof(arrayOopDesc)/HeapWordSize)

       : sizeof(arrayOopDesc)/HeapWordSize;

   }

   // This method returns the  maximum length that can passed into

   // typeArrayOop::object_size(scale, length, header_size) without causing an

   // overflow. We substract an extra 2*wordSize to guard against double word

   // alignments.  It gets the scale from the type2aelembytes array.

   static int32_t max_array_length(BasicType type) {

     assert(type >= 0 && type < T_CONFLICT, "wrong type");

     assert(type2aelembytes(type) != 0, "wrong type");

     // We use max_jint, since object_size is internally represented by an 'int'

     // This gives us an upper bound of max_jint words for the size of the oop.

     int32_t max_words = (max_jint - header_size(type) - 2);

     int elembytes = (type == T_OBJECT) ? T_OBJECT_aelem_bytes : type2aelembytes(type);

     jlong len = ((jlong)max_words * HeapWordSize) / elembytes;

     return (len > max_jint) ? max_jint : (int32_t)len;

   }

 };