1 /*
  2  * Copyright (c) 1999, 2021, 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 #include "precompiled.hpp"
 26 #include "opto/locknode.hpp"
 27 #include "opto/parse.hpp"
 28 #include "opto/rootnode.hpp"
 29 #include "opto/runtime.hpp"
 30 
 31 //=============================================================================
 32 const RegMask &BoxLockNode::in_RegMask(uint i) const {
 33   return _inmask;
 34 }
 35 
 36 const RegMask &BoxLockNode::out_RegMask() const {
 37   return *Matcher::idealreg2regmask[Op_RegP];
 38 }
 39 
 40 uint BoxLockNode::size_of() const { return sizeof(*this); }
 41 
 42 BoxLockNode::BoxLockNode( int slot ) : Node( Compile::current()->root() ),
 43                                        _slot(slot), _is_eliminated(false) {
 44   init_class_id(Class_BoxLock);
 45   init_flags(Flag_rematerialize);
 46   OptoReg::Name reg = OptoReg::stack2reg(_slot);
 47   _inmask.Insert(reg);
 48 }
 49 
 50 //-----------------------------hash--------------------------------------------
 51 uint BoxLockNode::hash() const {
 52   if (EliminateNestedLocks)
 53     return NO_HASH; // Each locked region has own BoxLock node
 54   return Node::hash() + _slot + (_is_eliminated ? Compile::current()->fixed_slots() : 0);
 55 }
 56 
 57 //------------------------------cmp--------------------------------------------
 58 bool BoxLockNode::cmp( const Node &n ) const {
 59   if (EliminateNestedLocks)
 60     return (&n == this); // Always fail except on self
 61   const BoxLockNode &bn = (const BoxLockNode &)n;
 62   return bn._slot == _slot && bn._is_eliminated == _is_eliminated;
 63 }
 64 
 65 BoxLockNode* BoxLockNode::box_node(Node* box) {
 66   // Chase down the BoxNode after RA which may spill box nodes.
 67   while (!box->is_BoxLock()) {
 68     //    if (box_node->is_SpillCopy()) {
 69     //      Node *m = box_node->in(1);
 70     //      if (m->is_Mach() && m->as_Mach()->ideal_Opcode() == Op_StoreP) {
 71     //        box_node = m->in(m->as_Mach()->operand_index(2));
 72     //        continue;
 73     //      }
 74     //    }
 75     assert(box->is_SpillCopy() || box->is_Phi(), "Bad spill of Lock.");
 76     // Only BoxLock nodes with the same stack slot are merged.
 77     // So it is enough to trace one path to find the slot value.
 78     box = box->in(1);
 79   }
 80   return box->as_BoxLock();
 81 }
 82 
 83 OptoReg::Name BoxLockNode::reg(Node* box) {
 84   return box_node(box)->in_RegMask(0).find_first_elem();
 85 }
 86 
 87 // Is BoxLock node used for one simple lock region (same box and obj)?
 88 bool BoxLockNode::is_simple_lock_region(LockNode** unique_lock, Node* obj, Node** bad_lock) {
 89   LockNode* lock = NULL;
 90   bool has_one_lock = false;
 91   for (uint i = 0; i < this->outcnt(); i++) {
 92     Node* n = this->raw_out(i);
 93     assert(!n->is_Phi(), "should not merge BoxLock nodes");
 94     if (n->is_AbstractLock()) {
 95       AbstractLockNode* alock = n->as_AbstractLock();
 96       // Check lock's box since box could be referenced by Lock's debug info.
 97       if (alock->box_node() == this) {
 98         if (alock->obj_node()->eqv_uncast(obj)) {
 99           if ((unique_lock != NULL) && alock->is_Lock()) {
100             if (lock == NULL) {
101               lock = alock->as_Lock();
102               has_one_lock = true;
103             } else if (lock != alock->as_Lock()) {
104               has_one_lock = false;
105               if (bad_lock != NULL) {
106                 *bad_lock = alock;
107               }
108             }
109           }
110         } else {
111           if (bad_lock != NULL) {
112             *bad_lock = alock;
113           }
114           return false; // Different objects
115         }
116       }
117     }
118   }
119 #ifdef ASSERT
120   // Verify that FastLock and Safepoint reference only this lock region.
121   for (uint i = 0; i < this->outcnt(); i++) {
122     Node* n = this->raw_out(i);
123     if (n->is_FastLock()) {
124       FastLockNode* flock = n->as_FastLock();
125       assert((flock->box_node() == this) && flock->obj_node()->eqv_uncast(obj),"");
126     }
127     // Don't check monitor info in safepoints since the referenced object could
128     // be different from the locked object. It could be Phi node of different
129     // cast nodes which point to this locked object.
130     // We assume that no other objects could be referenced in monitor info
131     // associated with this BoxLock node because all associated locks and
132     // unlocks are reference only this one object.
133   }
134 #endif
135   if (unique_lock != NULL && has_one_lock) {
136     *unique_lock = lock;
137   }
138   return true;
139 }
140 
141 //=============================================================================
142 //-----------------------------hash--------------------------------------------
143 uint FastLockNode::hash() const { return NO_HASH; }
144 
145 uint FastLockNode::size_of() const { return sizeof(*this); }
146 
147 //------------------------------cmp--------------------------------------------
148 bool FastLockNode::cmp( const Node &n ) const {
149   return (&n == this);                // Always fail except on self
150 }
151 
152 //=============================================================================
153 //-----------------------------hash--------------------------------------------
154 uint FastUnlockNode::hash() const { return NO_HASH; }
155 
156 //------------------------------cmp--------------------------------------------
157 bool FastUnlockNode::cmp( const Node &n ) const {
158   return (&n == this);                // Always fail except on self
159 }
160 
161 void FastLockNode::create_rtm_lock_counter(JVMState* state) {
162 #if INCLUDE_RTM_OPT
163   Compile* C = Compile::current();
164   if (C->profile_rtm() || (PrintPreciseRTMLockingStatistics && C->use_rtm())) {
165     RTMLockingNamedCounter* rlnc = (RTMLockingNamedCounter*)
166            OptoRuntime::new_named_counter(state, NamedCounter::RTMLockingCounter);
167     _rtm_counters = rlnc->counters();
168     if (UseRTMForStackLocks) {
169       rlnc = (RTMLockingNamedCounter*)
170            OptoRuntime::new_named_counter(state, NamedCounter::RTMLockingCounter);
171       _stack_rtm_counters = rlnc->counters();
172     }
173   }
174 #endif
175 }
176 
177 //=============================================================================
178 //------------------------------do_monitor_enter-------------------------------
179 void Parse::do_monitor_enter() {
180   kill_dead_locals();
181 
182   C->set_has_monitors(true);
183 
184   // Null check; get casted pointer.
185   Node* obj = null_check(peek());
186   // Check for locking null object
187   if (stopped()) return;
188 
189   // the monitor object is not part of debug info expression stack
190   pop();
191 
192   // Insert a FastLockNode which takes as arguments the current thread pointer,
193   // the obj pointer & the address of the stack slot pair used for the lock.
194   shared_lock(obj);
195 }
196 
197 //------------------------------do_monitor_exit--------------------------------
198 void Parse::do_monitor_exit() {
199   kill_dead_locals();
200 
201   // need to set it for monitor exit as well.
202   // OSR compiled methods can start with lock taken
203   C->set_has_monitors(true);
204 
205   pop();                        // Pop oop to unlock
206   // Because monitors are guaranteed paired (else we bail out), we know
207   // the matching Lock for this Unlock.  Hence we know there is no need
208   // for a null check on Unlock.
209   shared_unlock(map()->peek_monitor_box(), map()->peek_monitor_obj());
210 }