1 /*
   2  * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "gc/z/zThreadLocalData.hpp"
  26 #include "gc/z/zObjArrayAllocator.hpp"
  27 #include "gc/z/zUtils.inline.hpp"
  28 #include "oops/arrayKlass.hpp"
  29 #include "runtime/interfaceSupport.inline.hpp"
  30 
  31 ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :
  32     ObjArrayAllocator(klass, word_size, length, false /* do_zero */, thread) {}
  33 
  34 oop ZObjArrayAllocator::finish(HeapWord* mem) const {
  35   // Initialize object header and length field
  36   ObjArrayAllocator::finish(mem);
  37 
  38   // Keep the array alive across safepoints through an invisible
  39   // root. Invisible roots are not visited by the heap itarator
  40   // and the marking logic will not attempt to follow its elements.
  41   ZThreadLocalData::set_invisible_root(_thread, (oop*)&mem);
  42 
  43   // A max segment size of 64K was chosen because microbenchmarking
  44   // suggested that it offered a good trade-off between allocation
  45   // time and time-to-safepoint
  46   const size_t segment_max = ZUtils::bytes_to_words(64 * K);
  47   const size_t skip = arrayOopDesc::header_size(ArrayKlass::cast(_klass)->element_type());
  48   size_t remaining = _word_size - skip;
  49 
  50   while (remaining > 0) {
  51     // Clear segment
  52     const size_t segment = MIN2(remaining, segment_max);
  53     Copy::zero_to_words(mem + (_word_size - remaining), segment);
  54     remaining -= segment;
  55 
  56     if (remaining > 0) {
  57       // Safepoint
  58       ThreadBlockInVM tbivm((JavaThread*)_thread);
  59     }
  60   }
  61 
  62   ZThreadLocalData::clear_invisible_root(_thread);
  63 
  64   return oop(mem);
  65 }