1 /*
2 * Copyright (c) 2019, 2020, 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
ZObjArrayAllocator(Klass * klass,size_t word_size,int length,Thread * thread)31 ZObjArrayAllocator::ZObjArrayAllocator(Klass* klass, size_t word_size, int length, Thread* thread) :
32 ObjArrayAllocator(klass, word_size, length, false /* do_zero */, thread) {}
33
finish(HeapWord * mem) const34 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(_thread->as_Java_thread());
59 }
60 }
61
62 ZThreadLocalData::clear_invisible_root(_thread);
63
64 return cast_to_oop(mem);
65 }
66