1 /*
2 * Copyright (c) 1999, 2023, 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 = nullptr;
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 != nullptr) && alock->is_Lock()) {
100 if (lock == nullptr) {
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 != nullptr) {
106 *bad_lock = alock;
107 }
108 }
109 }
110 } else {
111 if (bad_lock != nullptr) {
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 != nullptr && 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 // Null check; get casted pointer.
183 Node* obj = null_check(peek());
184 // Check for locking null object
185 if (stopped()) return;
186
187 // the monitor object is not part of debug info expression stack
188 pop();
189
190 if (DoPartialEscapeAnalysis) {
191 PEAState& state = jvms()->alloc_state();
192 VirtualState* vs = state.as_virtual(PEA(), obj);
193
194 if (vs != nullptr) {
195 vs->lock_inc();
196 }
197 }
198
199 // Insert a FastLockNode which takes as arguments the current thread pointer,
200 // the obj pointer & the address of the stack slot pair used for the lock.
201 shared_lock(obj);
202 }
203
204 //------------------------------do_monitor_exit--------------------------------
205 void Parse::do_monitor_exit() {
206 kill_dead_locals();
207
208 // need to set it for monitor exit as well.
209 // OSR compiled methods can start with lock taken
210 C->set_has_monitors(true);
211 Node* obj = map()->peek_monitor_obj();
212
213 if (DoPartialEscapeAnalysis) {
214 PEAState& state = jvms()->alloc_state();
215 ObjID id = PEA()->is_alias(obj); //
216 if (id != nullptr && state.contains(id)) {
217 ObjectState* os = state.get_object_state(id);
218 if (os->is_virtual()) {
219 static_cast<VirtualState*>(os)->lock_dec();
220 } else {
221 auto materialized = state.get_materialized_value(id);
222 if (materialized != nullptr) {
223 obj = materialized;
224
225 if (obj->is_Phi()) {
226 pop();
227
228 // We need to split Phi + Unlock like this:
229 // +------+ +-----+ +------+
230 // |Region| | obj | | obj' | (PEA materialized object)
231 // +------+ +-----+ +------+
232 // \ | /
233 // +------------+
234 // |phi| |
235 // +------------+
236 // |P0
237 // +--------------+
238 // | UnlockNode |
239 // +--------------+
240 //
241 // split this phi because it helps EA and ME eliminate Unlock nodes.
242 // bytecode monitor_exit post-dominates the object, so PhiNode has been finalized.
243 // for GraphKit::shared_unlock(), the only side-effect is ctrl + abio + memory.
244 //
245 //
246 // +------+ +-----+ +------+
247 // |Region| | obj | | obj' |
248 // +------+ +-----+ +------+
249 // | /
250 // |P0 |P0
251 // +--------------+ +--------------+
252 // | UnlockNode | | UnlockNode |
253 // +--------------+ +--------------+
254 // | |abio |memory | |abio |memory
255 // | /-----/
256 // | ctrl / ctrl
257 // +--------------------+
258 // | new_rgn | ( new_rgn merges abio and memory as well)
259 // +--------------------+
260 // |ctrl |abio |memory
261 // +--------------------+
262 // | sfpt (map) |
263 // +--------------------+
264 //
265 RegionNode* region = obj->in(0)->as_Region();
266 BoxLockNode* box = map()->peek_monitor_box()->as_BoxLock();
267
268 Node* new_rgn = new RegionNode(region->req());
269 gvn().set_type(new_rgn, Type::CONTROL);
270
271 bool merged = false;
272 GraphKit saved_ctx = {clone_map()->jvms()};
273
274 // reverse i to simulate merging normal paths.
275 // merge_memory_edges() will do GVN when i == 1
276 for (uint i = region->req()-1; i > 0; --i) {
277 Node* ctrl = region->in(i);
278 Node* abio = nullptr;
279 MergeMemNode* mem = nullptr;
280
281 if (ctrl != nullptr && ctrl != C->top()) {
282 SafePointNode* curr = saved_ctx.clone_map();
283 GraphKit kit = { curr->jvms() };
284
285 kit.set_control(ctrl);
286 // We need to resume SafePointNode to the state as if it was the predecessor controlled by region->in(i).
287 for (uint j = 1; j < curr->req(); ++j) {
288 Node* m = curr->in(j);
289
290 if (j == TypeFunc::Memory) {
291 if (m->is_Phi() && m->in(0) == region) {
292 m = m->in(i);
293 } else if (m->is_MergeMem()) {
294 // a blank memory
295 MergeMemNode* new_all_mem = MergeMemNode::make(MergeMemNode::make_empty_memory());
296 new_all_mem->grow_to_match(m->as_MergeMem());
297 for (MergeMemStream mms(m->as_MergeMem()); mms.next_non_empty(); ) {
298 Node* p = mms.memory();
299 if (p->is_Phi() && p->in(0) == region) {
300 new_all_mem->set_req(mms.alias_idx(), p->in(i));
301 } else {
302 new_all_mem->set_req(mms.alias_idx(), p);
303 }
304 }
305 m = new_all_mem;
306 }
307 curr->set_memory(m);
308 } else if (m != nullptr && m->is_Phi() && m->in(0) == region) {
309 curr->set_req(j, m->in(i));
310 }
311 }
312
313 kit.shared_unlock(box, obj->in(i), true);
314
315 ctrl = kit.control();
316 mem = kit.merged_memory();
317 abio = kit.i_o();
318 } else {
319 assert(false, "impossible! monitorExit must post-dominate the PhiNode.");
320 }
321
322 new_rgn->init_req(i, ctrl);
323
324 if (!merged) {
325 merged = true;
326 set_control(new_rgn); // merge_memory_edges() requires that ctrl() is a RegionNode.
327 set_all_memory(mem);
328 set_i_o(abio);
329 } else {
330 merge_memory_edges(mem, i, false);
331 Node* phi = i_o();
332 if (!(phi->is_Phi() && phi->in(0) != new_rgn)) {
333 phi = PhiNode::make(new_rgn, phi);
334 gvn().set_type(phi, Type::ABIO);
335 record_for_igvn(phi);
336 }
337 phi->set_req(i, abio);
338 set_i_o(phi);
339 }
340 }
341
342 new_rgn = _gvn.transform(new_rgn);
343 set_control(new_rgn);
344 record_for_igvn(new_rgn);
345
346 map()->pop_monitor();
347 return ;
348 }
349 }
350 }
351 }
352 }
353
354 pop(); // Pop oop to unlock
355 // Because monitors are guaranteed paired (else we bail out), we know
356 // the matching Lock for this Unlock. Hence we know there is no need
357 // for a null check on Unlock.
358 shared_unlock(map()->peek_monitor_box(), obj);
359 }