1 /*
2 * Copyright (c) 1999, 2024, 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), _kind(BoxLockNode::Regular) {
44 init_class_id(Class_BoxLock);
45 init_flags(Flag_rematerialize);
46 OptoReg::Name reg = OptoReg::stack2reg(_slot);
47 if (!RegMask::can_represent(reg, Compile::current()->sync_stack_slots())) {
48 Compile::current()->record_method_not_compilable("must be able to represent all monitor slots in reg mask");
49 return;
50 }
51 _inmask.Insert(reg);
52 }
53
54 uint BoxLockNode::hash() const {
55 if (EliminateNestedLocks) {
56 return NO_HASH; // Each locked region has own BoxLock node
57 }
58 return Node::hash() + _slot + (is_eliminated() ? Compile::current()->fixed_slots() : 0);
59 }
60
61 bool BoxLockNode::cmp( const Node &n ) const {
62 if (EliminateNestedLocks) {
63 return (&n == this); // Always fail except on self
64 }
65 const BoxLockNode &bn = (const BoxLockNode &)n;
66 return (bn._slot == _slot) && (bn.is_eliminated() == is_eliminated());
67 }
68
69 Node* BoxLockNode::Identity(PhaseGVN* phase) {
70 if (!EliminateNestedLocks && !this->is_eliminated()) {
71 Node* n = phase->hash_find(this);
72 if (n == nullptr || n == this) {
73 return this;
74 }
75 BoxLockNode* old_box = n->as_BoxLock();
76 // Set corresponding status (_kind) when commoning BoxLock nodes.
77 if (this->_kind != old_box->_kind) {
78 if (this->is_unbalanced()) {
79 old_box->set_unbalanced();
80 }
81 if (!old_box->is_unbalanced()) {
82 // Only Regular or Coarsened status should be here:
83 // Nested and Local are set only when EliminateNestedLocks is on.
84 if (old_box->is_regular()) {
85 assert(this->is_coarsened(),"unexpected kind: %s", _kind_name[(int)this->_kind]);
86 old_box->set_coarsened();
87 } else {
88 assert(this->is_regular(),"unexpected kind: %s", _kind_name[(int)this->_kind]);
89 assert(old_box->is_coarsened(),"unexpected kind: %s", _kind_name[(int)old_box->_kind]);
90 }
91 }
92 }
93 return old_box;
94 }
95 return this;
96 }
97
98 BoxLockNode* BoxLockNode::box_node(Node* box) {
99 // Chase down the BoxNode after RA which may spill box nodes.
100 while (!box->is_BoxLock()) {
101 // if (box_node->is_SpillCopy()) {
102 // Node *m = box_node->in(1);
103 // if (m->is_Mach() && m->as_Mach()->ideal_Opcode() == Op_StoreP) {
104 // box_node = m->in(m->as_Mach()->operand_index(2));
105 // continue;
106 // }
107 // }
108 assert(box->is_SpillCopy() || box->is_Phi(), "Bad spill of Lock.");
109 // Only BoxLock nodes with the same stack slot are merged.
110 // So it is enough to trace one path to find the slot value.
111 box = box->in(1);
112 }
113 return box->as_BoxLock();
114 }
115
116 OptoReg::Name BoxLockNode::reg(Node* box) {
117 return box_node(box)->in_RegMask(0).find_first_elem();
118 }
119
120 // Is BoxLock node used for one simple lock region (same box and obj)?
121 bool BoxLockNode::is_simple_lock_region(LockNode** unique_lock, Node* obj, Node** bad_lock) {
122 if (is_unbalanced()) {
123 return false;
124 }
125 LockNode* lock = nullptr;
126 bool has_one_lock = false;
127 for (uint i = 0; i < this->outcnt(); i++) {
128 Node* n = this->raw_out(i);
129 assert(!n->is_Phi(), "should not merge BoxLock nodes");
130 if (n->is_AbstractLock()) {
131 AbstractLockNode* alock = n->as_AbstractLock();
132 // Check lock's box since box could be referenced by Lock's debug info.
133 if (alock->box_node() == this) {
134 if (alock->obj_node()->eqv_uncast(obj)) {
135 if ((unique_lock != nullptr) && alock->is_Lock()) {
136 if (lock == nullptr) {
137 lock = alock->as_Lock();
138 has_one_lock = true;
139 } else if (lock != alock->as_Lock()) {
140 has_one_lock = false;
141 if (bad_lock != nullptr) {
142 *bad_lock = alock;
143 }
144 }
145 }
146 } else {
147 if (bad_lock != nullptr) {
148 *bad_lock = alock;
149 }
150 return false; // Different objects
151 }
152 }
153 }
154 }
155 #ifdef ASSERT
156 // Verify that FastLock and Safepoint reference only this lock region.
157 for (uint i = 0; i < this->outcnt(); i++) {
158 Node* n = this->raw_out(i);
159 if (n->is_FastLock()) {
160 FastLockNode* flock = n->as_FastLock();
161 assert((flock->box_node() == this) && flock->obj_node()->eqv_uncast(obj),"");
162 }
163 // Don't check monitor info in safepoints since the referenced object could
164 // be different from the locked object. It could be Phi node of different
165 // cast nodes which point to this locked object.
166 // We assume that no other objects could be referenced in monitor info
167 // associated with this BoxLock node because all associated locks and
168 // unlocks are reference only this one object.
169 }
170 #endif
171 if (unique_lock != nullptr && has_one_lock) {
172 *unique_lock = lock;
173 }
174 return true;
175 }
176
177 //=============================================================================
178 //-----------------------------hash--------------------------------------------
179 uint FastLockNode::hash() const { return NO_HASH; }
180
181 uint FastLockNode::size_of() const { return sizeof(*this); }
182
183 //------------------------------cmp--------------------------------------------
184 bool FastLockNode::cmp( const Node &n ) const {
185 return (&n == this); // Always fail except on self
186 }
187
188 //=============================================================================
189 //-----------------------------hash--------------------------------------------
190 uint FastUnlockNode::hash() const { return NO_HASH; }
191
192 //------------------------------cmp--------------------------------------------
193 bool FastUnlockNode::cmp( const Node &n ) const {
194 return (&n == this); // Always fail except on self
195 }
196
197 //=============================================================================
198 //------------------------------do_monitor_enter-------------------------------
199 void Parse::do_monitor_enter() {
200 kill_dead_locals();
201
202 // Null check; get casted pointer.
203 Node* obj = null_check(peek());
204 // Check for locking null object
205 if (stopped()) return;
206
207 // the monitor object is not part of debug info expression stack
208 pop();
209
210 // Insert a FastLockNode which takes as arguments the current thread pointer,
211 // the obj pointer & the address of the stack slot pair used for the lock.
212 shared_lock(obj);
213 }
214
215 //------------------------------do_monitor_exit--------------------------------
216 void Parse::do_monitor_exit() {
217 kill_dead_locals();
218
219 pop(); // Pop oop to unlock
220 // Because monitors are guaranteed paired (else we bail out), we know
221 // the matching Lock for this Unlock. Hence we know there is no need
222 // for a null check on Unlock.
223 shared_unlock(map()->peek_monitor_box(), map()->peek_monitor_obj());
224 }