1 /* 2 * Copyright (c) 2016, 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 25 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP 26 #define SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP 27 28 #include "oops/oopsHierarchy.hpp" 29 #include "memory/allocation.hpp" 30 31 class CMTask; 32 33 // Helper class to mark through large objArrays during marking in an efficient way. 34 // Instead of pushing large object arrays, we push continuations onto the 35 // mark stack. These continuations are identified by having their LSB set. 36 // This allows incremental processing of large objects. 37 class G1CMObjArrayProcessor VALUE_OBJ_CLASS_SPEC { 38 private: 39 // The bit mask for the continuation indicator of elements on the mark stack. 40 static const size_t ArraySliceBit = 1; 41 42 // Reference to the task for doing the actual work. 43 CMTask* _task; 44 45 // Encodes the given address as a continuation "oop". 46 oop encode_array_slice(HeapWord* addr); 47 // Remove the continuation marker from the given oop from the mark stack. 48 HeapWord* decode_array_slice(oop value); 49 50 // Push the continuation at the given address onto the mark stack. 51 void push_array_slice(HeapWord* addr); 52 53 // Process (apply the closure) on the given continuation of the given objArray. 54 size_t process_array_slice(objArrayOop const obj, HeapWord* start_from, size_t remaining); 55 public: is_array_slice(void * obj)56 static bool is_array_slice(void* obj) { return ((uintptr_t)obj & ArraySliceBit) != 0; } 57 58 static bool should_be_sliced(oop obj); 59 G1CMObjArrayProcessor(CMTask * task)60 G1CMObjArrayProcessor(CMTask* task) : _task(task) { 61 } 62 63 // Process the given continuation "oop". Returns the number of words scanned. 64 size_t process_slice(oop obj); 65 // Start processing the given objArrayOop by scanning the header and pushing its 66 // continuation. 67 size_t process_obj(oop obj); 68 }; 69 70 #endif /* SHARE_VM_GC_G1_G1CONCURRENTMARKOBJARRAYPROCESSOR_HPP */ 71