1 /*
2 * Copyright (c) 1999, 2025, 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 "opto/locknode.hpp"
26 #include "opto/parse.hpp"
27 #include "opto/rootnode.hpp"
28 #include "opto/runtime.hpp"
29
30 //=============================================================================
31 const RegMask &BoxLockNode::in_RegMask(uint i) const {
32 return _inmask;
33 }
34
35 const RegMask &BoxLockNode::out_RegMask() const {
36 return *Matcher::idealreg2regmask[Op_RegP];
37 }
38
39 uint BoxLockNode::size_of() const { return sizeof(*this); }
40
41 BoxLockNode::BoxLockNode( int slot ) : Node( Compile::current()->root() ),
42 _slot(slot), _kind(BoxLockNode::Regular) {
43 init_class_id(Class_BoxLock);
44 init_flags(Flag_rematerialize);
45 OptoReg::Name reg = OptoReg::stack2reg(_slot);
46 if (!RegMask::can_represent(reg, Compile::current()->sync_stack_slots())) {
47 Compile::current()->record_method_not_compilable("must be able to represent all monitor slots in reg mask");
48 return;
49 }
50 _inmask.Insert(reg);
51 }
52
53 uint BoxLockNode::hash() const {
54 if (EliminateNestedLocks) {
55 return NO_HASH; // Each locked region has own BoxLock node
56 }
57 return Node::hash() + _slot + (is_eliminated() ? Compile::current()->fixed_slots() : 0);
58 }
59
60 bool BoxLockNode::cmp( const Node &n ) const {
61 if (EliminateNestedLocks) {
62 return (&n == this); // Always fail except on self
63 }
64 const BoxLockNode &bn = (const BoxLockNode &)n;
65 return (bn._slot == _slot) && (bn.is_eliminated() == is_eliminated());
66 }
67
68 Node* BoxLockNode::Identity(PhaseGVN* phase) {
69 if (!EliminateNestedLocks && !this->is_eliminated()) {
70 Node* n = phase->hash_find(this);
71 if (n == nullptr || n == this) {
72 return this;
73 }
74 BoxLockNode* old_box = n->as_BoxLock();
75 // Set corresponding status (_kind) when commoning BoxLock nodes.
76 if (this->_kind != old_box->_kind) {
77 if (this->is_unbalanced()) {
78 old_box->set_unbalanced();
79 }
80 if (!old_box->is_unbalanced()) {
81 // Only Regular or Coarsened status should be here:
82 // Nested and Local are set only when EliminateNestedLocks is on.
83 if (old_box->is_regular()) {
84 assert(this->is_coarsened(),"unexpected kind: %s", _kind_name[(int)this->_kind]);
85 old_box->set_coarsened();
86 } else {
87 assert(this->is_regular(),"unexpected kind: %s", _kind_name[(int)this->_kind]);
88 assert(old_box->is_coarsened(),"unexpected kind: %s", _kind_name[(int)old_box->_kind]);
89 }
90 }
91 }
92 return old_box;
93 }
94 return this;
95 }
96
97 BoxLockNode* BoxLockNode::box_node(Node* box) {
98 // Chase down the BoxNode after RA which may spill box nodes.
99 while (!box->is_BoxLock()) {
100 // if (box_node->is_SpillCopy()) {
101 // Node *m = box_node->in(1);
102 // if (m->is_Mach() && m->as_Mach()->ideal_Opcode() == Op_StoreP) {
103 // box_node = m->in(m->as_Mach()->operand_index(2));
104 // continue;
105 // }
106 // }
107 assert(box->is_SpillCopy() || box->is_Phi(), "Bad spill of Lock.");
108 // Only BoxLock nodes with the same stack slot are merged.
109 // So it is enough to trace one path to find the slot value.
110 box = box->in(1);
111 }
112 return box->as_BoxLock();
113 }
114
115 OptoReg::Name BoxLockNode::reg(Node* box) {
116 return box_node(box)->in_RegMask(0).find_first_elem();
117 }
118
119 // Is BoxLock node used for one simple lock region (same box and obj)?
120 bool BoxLockNode::is_simple_lock_region(LockNode** unique_lock, Node* obj, Node** bad_lock) {
121 if (is_unbalanced()) {
122 return false;
123 }
124 LockNode* lock = nullptr;
125 bool has_one_lock = false;
126 for (uint i = 0; i < this->outcnt(); i++) {
127 Node* n = this->raw_out(i);
128 assert(!n->is_Phi(), "should not merge BoxLock nodes");
129 if (n->is_AbstractLock()) {
130 AbstractLockNode* alock = n->as_AbstractLock();
131 // Check lock's box since box could be referenced by Lock's debug info.
132 if (alock->box_node() == this) {
133 if (alock->obj_node()->eqv_uncast(obj)) {
134 if ((unique_lock != nullptr) && alock->is_Lock()) {
135 if (lock == nullptr) {
136 lock = alock->as_Lock();
137 has_one_lock = true;
138 } else if (lock != alock->as_Lock()) {
139 has_one_lock = false;
140 if (bad_lock != nullptr) {
141 *bad_lock = alock;
142 }
143 }
144 }
145 } else {
146 if (bad_lock != nullptr) {
147 *bad_lock = alock;
148 }
149 return false; // Different objects
150 }
151 }
152 }
153 }
154 #ifdef ASSERT
155 // Verify that FastLock and Safepoint reference only this lock region.
156 for (uint i = 0; i < this->outcnt(); i++) {
157 Node* n = this->raw_out(i);
158 if (n->is_FastLock()) {
159 FastLockNode* flock = n->as_FastLock();
160 assert((flock->box_node() == this) && flock->obj_node()->eqv_uncast(obj),"");
161 }
162 // Don't check monitor info in safepoints since the referenced object could
163 // be different from the locked object. It could be Phi node of different
164 // cast nodes which point to this locked object.
165 // We assume that no other objects could be referenced in monitor info
166 // associated with this BoxLock node because all associated locks and
167 // unlocks are reference only this one object.
168 }
169 #endif
170 if (unique_lock != nullptr && has_one_lock) {
171 *unique_lock = lock;
172 }
173 return true;
174 }
175
176 //=============================================================================
177 //-----------------------------hash--------------------------------------------
178 uint FastLockNode::hash() const { return NO_HASH; }
179
180 uint FastLockNode::size_of() const { return sizeof(*this); }
181
182 //------------------------------cmp--------------------------------------------
183 bool FastLockNode::cmp( const Node &n ) const {
184 return (&n == this); // Always fail except on self
185 }
186
187 //=============================================================================
188 //-----------------------------hash--------------------------------------------
189 uint FastUnlockNode::hash() const { return NO_HASH; }
190
191 //------------------------------cmp--------------------------------------------
192 bool FastUnlockNode::cmp( const Node &n ) const {
193 return (&n == this); // Always fail except on self
194 }
195
196 //=============================================================================
197 //------------------------------do_monitor_enter-------------------------------
198 void Parse::do_monitor_enter() {
199 kill_dead_locals();
200
201 // Null check; get casted pointer.
202 Node* obj = null_check(peek());
203 // Check for locking null object
204 if (stopped()) return;
205
206 // the monitor object is not part of debug info expression stack
207 pop();
208
209 // Insert a FastLockNode which takes as arguments the current thread pointer,
210 // the obj pointer & the address of the stack slot pair used for the lock.
211 shared_lock(obj);
212 }
213
214 //------------------------------do_monitor_exit--------------------------------
215 void Parse::do_monitor_exit() {
216 kill_dead_locals();
217
218 pop(); // Pop oop to unlock
219 // Because monitors are guaranteed paired (else we bail out), we know
220 // the matching Lock for this Unlock. Hence we know there is no need
221 // for a null check on Unlock.
222 shared_unlock(map()->peek_monitor_box(), map()->peek_monitor_obj());
223 }