jdk8-mips64-public/hotspot: src/share/vm/oops/arrayOop.hpp@710a3c8b516e (annotated)

src/share/vm/oops/arrayOop.hpp@710a3c8b516e (annotated)

src/share/vm/oops/arrayOop.hpp

Tue, 08 Aug 2017 15:57:29 +0800

author: aoqi
date: Tue, 08 Aug 2017 15:57:29 +0800
changeset 6876: 710a3c8b516e
parent 6198: 55fb97c4c58d
parent 0: f90c822e73f8
permissions: -rw-r--r--

merge

 /*
  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 #ifndef SHARE_VM_OOPS_ARRAYOOP_HPP
 #define SHARE_VM_OOPS_ARRAYOOP_HPP
 #include "memory/universe.inline.hpp"
 #include "oops/oop.hpp"
 // 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
 //  Klass*    // 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.
   static int header_size_in_bytes() {
     size_t hs = align_size_up(length_offset_in_bytes() + 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 UseCompressedClassPointers ? 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_offset(typesize_in_bytes/HeapWordSize)
       : typesize_in_bytes/HeapWordSize);
   }
   // Return the maximum length of an array of BasicType.  The length can passed
   // to typeArrayOop::object_size(scale, length, header_size) without causing an
   // overflow. We also need to make sure that this will not overflow a size_t on
   // 32 bit platforms when we convert it to a byte size.
   static int32_t max_array_length(BasicType type) {
     assert(type >= 0 && type < T_CONFLICT, "wrong type");
     assert(type2aelembytes(type) != 0, "wrong type");
     const size_t max_element_words_per_size_t =
       align_size_down((SIZE_MAX/HeapWordSize - header_size(type)), MinObjAlignment);
     const size_t max_elements_per_size_t =
       HeapWordSize * max_element_words_per_size_t / type2aelembytes(type);
     if ((size_t)max_jint < max_elements_per_size_t) {
       // It should be ok to return max_jint here, but parts of the code
       // (CollectedHeap, Klass::oop_oop_iterate(), and more) uses an int for
       // passing around the size (in words) of an object. So, we need to avoid
       // overflowing an int when we add the header. See CRs 4718400 and 7110613.
       return align_size_down(max_jint - header_size(type), MinObjAlignment);
     }
     return (int32_t)max_elements_per_size_t;
   }
 // for unit testing
 #ifndef PRODUCT
   static bool check_max_length_overflow(BasicType type);
   static int32_t old_max_array_length(BasicType type);
   static void test_max_array_length();
 #endif
 };
 #endif // SHARE_VM_OOPS_ARRAYOOP_HPP

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/oops/arrayOop.hpp@710a3c8b516e (annotated)

src/share/vm/oops/arrayOop.hpp