jdk8-mips64-public/hotspot: src/share/vm/oops/arrayOop.hpp@ba764ed4b6f2 (annotated)

src/share/vm/oops/arrayOop.hpp@ba764ed4b6f2 (annotated)

src/share/vm/oops/arrayOop.hpp

Sun, 13 Apr 2008 17:43:42 -0400

author: coleenp
date: Sun, 13 Apr 2008 17:43:42 -0400
changeset 548: ba764ed4b6f2
parent 464: d5fc211aea19
child 600: 437d03ea40b1
permissions: -rw-r--r--

6420645: Create a vm that uses compressed oops for up to 32gb heapsizes
Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv
Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold

 /*
  * 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.  It doesn't
 // declare pure virtual to enforce this because that would allocate a vtbl
 // in each instance, which we don't want.
 // The layout of array Oops is:
 //
 //  markOop
 //  klassOop  // 32 bits if compressed but declared 64 in LP64.
 //  length    // shares klass memory or allocated after declared fields.
 class arrayOopDesc : public oopDesc {
   friend class VMStructs;
   // Interpreter/Compiler offsets
   // Header size computation.
   // The header is considered the oop part of this type plus the length.
   // Returns the aligned header_size_in_bytes.  This is not equivalent to
   // sizeof(arrayOopDesc) which should not appear in the code, except here.
   static int header_size_in_bytes() {
     size_t hs = UseCompressedOops ?
             sizeof(arrayOopDesc) :
             align_size_up(sizeof(arrayOopDesc) + sizeof(int), HeapWordSize);
 #ifdef ASSERT
     // make sure it isn't called before UseCompressedOops is initialized.
     static size_t arrayoopdesc_hs = 0;
     if (arrayoopdesc_hs == 0) arrayoopdesc_hs = hs;
     assert(arrayoopdesc_hs == hs, "header size can't change");
 #endif // ASSERT
     return (int)hs;
   }
  public:
   // The _length field is not declared in C++.  It is allocated after the
   // declared nonstatic fields in arrayOopDesc if not compressed, otherwise
   // it occupies the second half of the _klass field in oopDesc.
   static int length_offset_in_bytes() {
     return UseCompressedOops ? klass_gap_offset_in_bytes() :
                                sizeof(arrayOopDesc);
   }
   // Returns the offset of the first element.
   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(); }
   // Accessors for instance variable which is not a C++ declared nonstatic
   // field.
   int length() const {
     return *(int*)(((intptr_t)this) + length_offset_in_bytes());
   }
   void set_length(int length) {
     *(int*)(((intptr_t)this) + length_offset_in_bytes()) = length;
   }
   // Should only be called with constants as argument
   // (will not constant fold otherwise)
   // Returns the header size in words aligned to the requirements of the
   // array object type.
   static int header_size(BasicType type) {
     size_t typesize_in_bytes = header_size_in_bytes();
     return (int)(Universe::element_type_should_be_aligned(type)
       ? align_object_size(typesize_in_bytes/HeapWordSize)
       : typesize_in_bytes/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 = type2aelembytes(type);
     jlong len = ((jlong)max_words * HeapWordSize) / elembytes;
     return (len > max_jint) ? max_jint : (int32_t)len;
   }
 };

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src/share/vm/oops/arrayOop.hpp@ba764ed4b6f2 (annotated)

src/share/vm/oops/arrayOop.hpp