1 /* 2 * Copyright (c) 1998, 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 25 #ifndef SHARE_RUNTIME_BASICLOCK_HPP 26 #define SHARE_RUNTIME_BASICLOCK_HPP 27 28 #include "oops/markWord.hpp" 29 #include "runtime/atomic.hpp" 30 #include "runtime/handles.hpp" 31 32 class BasicLock { 33 friend class VMStructs; 34 friend class JVMCIVMStructs; 35 private: 36 volatile markWord _displaced_header; 37 public: 38 markWord displaced_header() const { 39 return Atomic::load(&_displaced_header); 40 } 41 42 void set_displaced_header(markWord header) { 43 Atomic::store(header, &_displaced_header); 44 } 45 46 void print_on(outputStream* st) const; 47 48 // move a basic lock (used during deoptimization 49 void move_to(oop obj, BasicLock* dest); 50 51 static int displaced_header_offset_in_bytes() { return offset_of(BasicLock, _displaced_header); } 52 }; 53 54 // A BasicObjectLock associates a specific Java object with a BasicLock. 55 // It is currently embedded in an interpreter frame. 56 57 // Because some machines have alignment restrictions on the control stack, 58 // the actual space allocated by the interpreter may include padding words 59 // after the end of the BasicObjectLock. Also, in order to guarantee 60 // alignment of the embedded BasicLock objects on such machines, we 61 // put the embedded BasicLock at the beginning of the struct. 62 63 class BasicObjectLock { 64 friend class VMStructs; 65 private: 66 BasicLock _lock; // the lock, must be double word aligned 67 oop _obj; // object holds the lock; 68 69 public: 70 // Manipulation 71 oop obj() const { return _obj; } 72 void set_obj(oop obj) { _obj = obj; } 73 BasicLock* lock() { return &_lock; } 74 75 // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks 76 // in interpreter activation frames since it includes machine-specific padding. 77 static int size() { return sizeof(BasicObjectLock)/wordSize; } 78 79 // GC support 80 void oops_do(OopClosure* f) { f->do_oop(&_obj); } 81 82 static int obj_offset_in_bytes() { return offset_of(BasicObjectLock, _obj); } 83 static int lock_offset_in_bytes() { return offset_of(BasicObjectLock, _lock); } 84 }; 85 86 87 #endif // SHARE_RUNTIME_BASICLOCK_HPP