1 /* 2 * Copyright (c) 2013, 2015, Red Hat, Inc. and/or its affiliates. 3 * 4 * This code is free software; you can redistribute it and/or modify it 5 * under the terms of the GNU General Public License version 2 only, as 6 * published by the Free Software Foundation. 7 * 8 * This code is distributed in the hope that it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 11 * version 2 for more details (a copy is included in the LICENSE file that 12 * accompanied this code). 13 * 14 * You should have received a copy of the GNU General Public License version 15 * 2 along with this work; if not, write to the Free Software Foundation, 16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 17 * 18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 19 * or visit www.oracle.com if you need additional information or have any 20 * questions. 21 * 22 */ 23 24 #ifndef SHARE_VM_GC_SHENANDOAH_BROOKSPOINTER_HPP 25 #define SHARE_VM_GC_SHENANDOAH_BROOKSPOINTER_HPP 26 27 #include "oops/oop.hpp" 28 #include "utilities/globalDefinitions.hpp" 29 #include "gc/shenandoah/shenandoahHeap.hpp" 30 31 class BrooksPointer { 32 33 public: 34 static const uint BROOKS_POINTER_OBJ_SIZE = 1; 35 static const int BYTE_OFFSET = -8; 36 37 private: 38 39 HeapWord** _heap_word; 40 41 BrooksPointer(HeapWord** heap_word); 42 43 public: 44 45 bool check_forwardee_is_in_heap(oop forwardee); 46 47 inline oop get_forwardee_raw() { 48 return oop(*_heap_word); 49 } 50 51 inline oop get_forwardee() { 52 oop forwardee; 53 54 #ifdef ASSERT 55 if (ShenandoahVerifyReadsToFromSpace) { 56 ShenandoahHeap* sh = (ShenandoahHeap*) Universe::heap(); 57 ShenandoahHeapRegion* hr = sh->heap_region_containing(_heap_word); 58 59 { 60 hr->memProtectionOff(); 61 forwardee = (oop) (*_heap_word); 62 hr->memProtectionOn(); 63 } 64 } else { 65 forwardee = get_forwardee_raw(); 66 } 67 #else 68 forwardee = get_forwardee_raw(); 69 #endif 70 71 assert(check_forwardee_is_in_heap(forwardee), "forwardee must be in heap"); 72 assert(forwardee->is_oop(), "forwardee must be valid oop"); 73 return forwardee; 74 } 75 76 void set_forwardee(oop forwardee); 77 HeapWord* cas_forwardee(HeapWord* old, HeapWord* forwardee); 78 79 static BrooksPointer get(oop obj); 80 }; 81 82 #endif // SHARE_VM_GC_SHENANDOAH_BROOKSPOINTER_HPP