1 /*
2 * Copyright (c) 2012, 2016, 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 package org.graalvm.compiler.hotspot.replacements;
24
25 import static org.graalvm.compiler.core.common.GraalOptions.SnippetCounters;
26 import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_VMCONFIG;
27 import static org.graalvm.compiler.hotspot.nodes.BeginLockScopeNode.beginLockScope;
28 import static org.graalvm.compiler.hotspot.nodes.DirectCompareAndSwapNode.compareAndSwap;
29 import static org.graalvm.compiler.hotspot.nodes.EndLockScopeNode.endLockScope;
30 import static org.graalvm.compiler.hotspot.nodes.VMErrorNode.vmError;
31 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.DISPLACED_MARK_WORD_LOCATION;
32 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.MARK_WORD_LOCATION;
33 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.PROTOTYPE_MARK_WORD_LOCATION;
34 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.ageMaskInPlace;
35 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.biasedLockMaskInPlace;
36 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.biasedLockPattern;
37 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.config;
38 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.epochMaskInPlace;
39 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.loadWordFromObject;
40 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.lockDisplacedMarkOffset;
41 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.markOffset;
42 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.pageSize;
43 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.prototypeMarkWordOffset;
44 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.registerAsWord;
45 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.unlockedMask;
46 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.useBiasedLocking;
47 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.verifyOop;
48 import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.wordSize;
49 import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.ProfileMonitors;
50 import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.TraceMonitorsMethodFilter;
51 import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.TraceMonitorsTypeFilter;
52 import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.VerifyBalancedMonitors;
53 import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.FREQUENT_PROBABILITY;
54 import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.VERY_FAST_PATH_PROBABILITY;
55 import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.VERY_SLOW_PATH_PROBABILITY;
56 import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.probability;
57 import static org.graalvm.compiler.replacements.SnippetTemplate.DEFAULT_REPLACER;
58
59 import java.util.List;
60
61 import org.graalvm.compiler.api.replacements.Fold;
62 import org.graalvm.compiler.api.replacements.Snippet;
63 import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;
64 import org.graalvm.compiler.bytecode.Bytecode;
65 import org.graalvm.compiler.bytecode.ResolvedJavaMethodBytecode;
66 import org.graalvm.compiler.core.common.LocationIdentity;
67 import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;
68 import org.graalvm.compiler.core.common.type.ObjectStamp;
69 import org.graalvm.compiler.core.common.type.StampFactory;
70 import org.graalvm.compiler.core.common.type.StampPair;
71 import org.graalvm.compiler.graph.Node.ConstantNodeParameter;
72 import org.graalvm.compiler.graph.Node.NodeIntrinsic;
73 import org.graalvm.compiler.graph.iterators.NodeIterable;
74 import org.graalvm.compiler.hotspot.meta.HotSpotProviders;
75 import org.graalvm.compiler.hotspot.meta.HotSpotRegistersProvider;
76 import org.graalvm.compiler.hotspot.nodes.AcquiredCASLockNode;
77 import org.graalvm.compiler.hotspot.nodes.CurrentLockNode;
78 import org.graalvm.compiler.hotspot.nodes.DirectCompareAndSwapNode;
79 import org.graalvm.compiler.hotspot.nodes.FastAcquireBiasedLockNode;
80 import org.graalvm.compiler.hotspot.nodes.MonitorCounterNode;
81 import org.graalvm.compiler.hotspot.word.KlassPointer;
82 import org.graalvm.compiler.nodes.BreakpointNode;
83 import org.graalvm.compiler.nodes.CallTargetNode.InvokeKind;
84 import org.graalvm.compiler.nodes.ConstantNode;
85 import org.graalvm.compiler.nodes.DeoptimizeNode;
86 import org.graalvm.compiler.nodes.FrameState;
87 import org.graalvm.compiler.nodes.InvokeNode;
88 import org.graalvm.compiler.nodes.NamedLocationIdentity;
89 import org.graalvm.compiler.nodes.ReturnNode;
90 import org.graalvm.compiler.nodes.StructuredGraph;
91 import org.graalvm.compiler.nodes.ValueNode;
92 import org.graalvm.compiler.nodes.debug.DynamicCounterNode;
93 import org.graalvm.compiler.nodes.extended.BranchProbabilityNode;
94 import org.graalvm.compiler.nodes.extended.ForeignCallNode;
95 import org.graalvm.compiler.nodes.java.MethodCallTargetNode;
96 import org.graalvm.compiler.nodes.java.MonitorExitNode;
97 import org.graalvm.compiler.nodes.java.RawMonitorEnterNode;
98 import org.graalvm.compiler.nodes.memory.address.OffsetAddressNode;
99 import org.graalvm.compiler.nodes.spi.LoweringTool;
100 import org.graalvm.compiler.nodes.type.StampTool;
101 import org.graalvm.compiler.phases.common.inlining.InliningUtil;
102 import org.graalvm.compiler.replacements.Log;
103 import org.graalvm.compiler.replacements.SnippetCounter;
104 import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
105 import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
106 import org.graalvm.compiler.replacements.SnippetTemplate.SnippetInfo;
107 import org.graalvm.compiler.replacements.Snippets;
108 import org.graalvm.compiler.word.Word;
109 import org.graalvm.compiler.word.WordBase;
110
111 import jdk.vm.ci.code.BytecodeFrame;
112 import jdk.vm.ci.code.Register;
113 import jdk.vm.ci.code.TargetDescription;
114 import jdk.vm.ci.meta.DeoptimizationAction;
115 import jdk.vm.ci.meta.DeoptimizationReason;
116 import jdk.vm.ci.meta.JavaType;
117 import jdk.vm.ci.meta.ResolvedJavaMethod;
118 import jdk.vm.ci.meta.ResolvedJavaType;
119
120 /**
121 * Snippets used for implementing the monitorenter and monitorexit instructions.
122 *
123 * The locking algorithm used is described in the paper
124 * <a href="http://dl.acm.org/citation.cfm?id=1167515.1167496"> Eliminating synchronization-related
125 * atomic operations with biased locking and bulk rebiasing</a> by Kenneth Russell and David
126 * Detlefs.
127 *
128 * Comment below is reproduced from {@code markOop.hpp} for convenience:
129 *
130 * <pre>
131 * Bit-format of an object header (most significant first, big endian layout below):
132 * 32 bits:
133 * --------
134 * hash:25 ------------>| age:4 biased_lock:1 lock:2 (normal object)
135 * JavaThread*:23 epoch:2 age:4 biased_lock:1 lock:2 (biased object)
136 * size:32 ------------------------------------------>| (CMS free block)
137 * PromotedObject*:29 ---------->| promo_bits:3 ----->| (CMS promoted object)
138 *
139 * 64 bits:
140 * --------
141 * unused:25 hash:31 -->| unused:1 age:4 biased_lock:1 lock:2 (normal object)
142 * JavaThread*:54 epoch:2 unused:1 age:4 biased_lock:1 lock:2 (biased object)
143 * PromotedObject*:61 --------------------->| promo_bits:3 ----->| (CMS promoted object)
144 * size:64 ----------------------------------------------------->| (CMS free block)
145 *
146 * unused:25 hash:31 -->| cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && normal object)
147 * JavaThread*:54 epoch:2 cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && biased object)
148 * narrowOop:32 unused:24 cms_free:1 unused:4 promo_bits:3 ----->| (COOPs && CMS promoted object)
149 * unused:21 size:35 -->| cms_free:1 unused:7 ------------------>| (COOPs && CMS free block)
150 *
151 * - hash contains the identity hash value: largest value is
152 * 31 bits, see os::random(). Also, 64-bit vm's require
153 * a hash value no bigger than 32 bits because they will not
154 * properly generate a mask larger than that: see library_call.cpp
155 * and c1_CodePatterns_sparc.cpp.
156 *
157 * - the biased lock pattern is used to bias a lock toward a given
158 * thread. When this pattern is set in the low three bits, the lock
159 * is either biased toward a given thread or "anonymously" biased,
160 * indicating that it is possible for it to be biased. When the
161 * lock is biased toward a given thread, locking and unlocking can
162 * be performed by that thread without using atomic operations.
163 * When a lock's bias is revoked, it reverts back to the normal
164 * locking scheme described below.
165 *
166 * Note that we are overloading the meaning of the "unlocked" state
167 * of the header. Because we steal a bit from the age we can
168 * guarantee that the bias pattern will never be seen for a truly
169 * unlocked object.
170 *
171 * Note also that the biased state contains the age bits normally
172 * contained in the object header. Large increases in scavenge
173 * times were seen when these bits were absent and an arbitrary age
174 * assigned to all biased objects, because they tended to consume a
175 * significant fraction of the eden semispaces and were not
176 * promoted promptly, causing an increase in the amount of copying
177 * performed. The runtime system aligns all JavaThread* pointers to
178 * a very large value (currently 128 bytes (32bVM) or 256 bytes (64bVM))
179 * to make room for the age bits & the epoch bits (used in support of
180 * biased locking), and for the CMS "freeness" bit in the 64bVM (+COOPs).
181 *
182 * [JavaThread* | epoch | age | 1 | 01] lock is biased toward given thread
183 * [0 | epoch | age | 1 | 01] lock is anonymously biased
184 *
185 * - the two lock bits are used to describe three states: locked/unlocked and monitor.
186 *
187 * [ptr | 00] locked ptr points to real header on stack
188 * [header | 0 | 01] unlocked regular object header
189 * [ptr | 10] monitor inflated lock (header is wapped out)
190 * [ptr | 11] marked used by markSweep to mark an object
191 * not valid at any other time
192 *
193 * We assume that stack/thread pointers have the lowest two bits cleared.
194 * </pre>
195 *
196 * Note that {@code Thread::allocate} enforces {@code JavaThread} objects to be aligned
197 * appropriately to comply with the layouts above.
198 */
199 public class MonitorSnippets implements Snippets {
200
201 private static final boolean PROFILE_CONTEXT = false;
202
203 @Fold
204 static boolean doProfile() {
205 return ProfileMonitors.getValue();
206 }
207
208 @Snippet
209 public static void monitorenter(Object object, KlassPointer hub, @ConstantParameter int lockDepth, @ConstantParameter Register threadRegister, @ConstantParameter Register stackPointerRegister,
210 @ConstantParameter boolean trace) {
211 verifyOop(object);
212
213 // Load the mark word - this includes a null-check on object
214 final Word mark = loadWordFromObject(object, markOffset(INJECTED_VMCONFIG));
215
216 final Word lock = beginLockScope(lockDepth);
217
218 trace(trace, " object: 0x%016lx\n", Word.objectToTrackedPointer(object));
219 trace(trace, " lock: 0x%016lx\n", lock);
220 trace(trace, " mark: 0x%016lx\n", mark);
221
222 incCounter();
223
224 if (useBiasedLocking(INJECTED_VMCONFIG)) {
225 // See whether the lock is currently biased toward our thread and
226 // whether the epoch is still valid.
227 // Note that the runtime guarantees sufficient alignment of JavaThread
228 // pointers to allow age to be placed into low bits.
229 final Word biasableLockBits = mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG));
230
231 // Check whether the bias pattern is present in the object's mark word
232 // and the bias owner and the epoch are both still current.
233 final Word prototypeMarkWord = hub.readWord(prototypeMarkWordOffset(INJECTED_VMCONFIG), PROTOTYPE_MARK_WORD_LOCATION);
234 final Word thread = registerAsWord(threadRegister);
235 final Word tmp = prototypeMarkWord.or(thread).xor(mark).and(~ageMaskInPlace(INJECTED_VMCONFIG));
236 trace(trace, "prototypeMarkWord: 0x%016lx\n", prototypeMarkWord);
237 trace(trace, " thread: 0x%016lx\n", thread);
238 trace(trace, " tmp: 0x%016lx\n", tmp);
239 if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, tmp.equal(0))) {
240 // Object is already biased to current thread -> done
241 traceObject(trace, "+lock{bias:existing}", object, true);
242 lockBiasExisting.inc();
243 FastAcquireBiasedLockNode.mark(object);
244 return;
245 }
246
247 // Now check to see whether biasing is enabled for this object
248 if (probability(BranchProbabilityNode.FAST_PATH_PROBABILITY, biasableLockBits.notEqual(Word.unsigned(biasedLockPattern(INJECTED_VMCONFIG))))) {
249 // Biasing not enabled -> fall through to lightweight locking
250 unbiasable.inc();
251 } else {
252 // At this point we know that the mark word has the bias pattern and
253 // that we are not the bias owner in the current epoch. We need to
254 // figure out more details about the state of the mark word in order to
255 // know what operations can be legally performed on the object's
256 // mark word.
257
258 // If the low three bits in the xor result aren't clear, that means
259 // the prototype header is no longer biasable and we have to revoke
260 // the bias on this object.
261 if (probability(FREQUENT_PROBABILITY, tmp.and(biasedLockMaskInPlace(INJECTED_VMCONFIG)).equal(0))) {
262 // Biasing is still enabled for object's type. See whether the
263 // epoch of the current bias is still valid, meaning that the epoch
264 // bits of the mark word are equal to the epoch bits of the
265 // prototype mark word. (Note that the prototype mark word's epoch bits
266 // only change at a safepoint.) If not, attempt to rebias the object
267 // toward the current thread. Note that we must be absolutely sure
268 // that the current epoch is invalid in order to do this because
269 // otherwise the manipulations it performs on the mark word are
270 // illegal.
271 if (probability(FREQUENT_PROBABILITY, tmp.and(epochMaskInPlace(INJECTED_VMCONFIG)).equal(0))) {
272 // The epoch of the current bias is still valid but we know nothing
273 // about the owner; it might be set or it might be clear. Try to
274 // acquire the bias of the object using an atomic operation. If this
275 // fails we will go in to the runtime to revoke the object's bias.
276 // Note that we first construct the presumed unbiased header so we
277 // don't accidentally blow away another thread's valid bias.
278 Word unbiasedMark = mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG) | ageMaskInPlace(INJECTED_VMCONFIG) | epochMaskInPlace(INJECTED_VMCONFIG));
279 Word biasedMark = unbiasedMark.or(thread);
280 trace(trace, " unbiasedMark: 0x%016lx\n", unbiasedMark);
281 trace(trace, " biasedMark: 0x%016lx\n", biasedMark);
282 if (probability(VERY_FAST_PATH_PROBABILITY,
283 compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), unbiasedMark, biasedMark, MARK_WORD_LOCATION).equal(unbiasedMark))) {
284 // Object is now biased to current thread -> done
285 traceObject(trace, "+lock{bias:acquired}", object, true);
286 lockBiasAcquired.inc();
287 return;
288 }
289 // If the biasing toward our thread failed, this means that another thread
290 // owns the bias and we need to revoke that bias. The revocation will occur
291 // in the interpreter runtime.
292 traceObject(trace, "+lock{stub:revoke}", object, true);
293 lockStubRevoke.inc();
294 } else {
295 // At this point we know the epoch has expired, meaning that the
296 // current bias owner, if any, is actually invalid. Under these
297 // circumstances _only_, are we allowed to use the current mark word
298 // value as the comparison value when doing the CAS to acquire the
299 // bias in the current epoch. In other words, we allow transfer of
300 // the bias from one thread to another directly in this situation.
301 Word biasedMark = prototypeMarkWord.or(thread);
302 trace(trace, " biasedMark: 0x%016lx\n", biasedMark);
303 if (probability(VERY_FAST_PATH_PROBABILITY,
304 compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), mark, biasedMark, MARK_WORD_LOCATION).equal(mark))) {
305 // Object is now biased to current thread -> done
306 traceObject(trace, "+lock{bias:transfer}", object, true);
307 lockBiasTransfer.inc();
308 return;
309 }
310 // If the biasing toward our thread failed, then another thread
311 // succeeded in biasing it toward itself and we need to revoke that
312 // bias. The revocation will occur in the runtime in the slow case.
313 traceObject(trace, "+lock{stub:epoch-expired}", object, true);
314 lockStubEpochExpired.inc();
315 }
316 monitorenterStubC(MONITORENTER, object, lock);
317 return;
318 } else {
319 // The prototype mark word doesn't have the bias bit set any
320 // more, indicating that objects of this data type are not supposed
321 // to be biased any more. We are going to try to reset the mark of
322 // this object to the prototype value and fall through to the
323 // CAS-based locking scheme. Note that if our CAS fails, it means
324 // that another thread raced us for the privilege of revoking the
325 // bias of this particular object, so it's okay to continue in the
326 // normal locking code.
327 Word result = compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), mark, prototypeMarkWord, MARK_WORD_LOCATION);
328
329 // Fall through to the normal CAS-based lock, because no matter what
330 // the result of the above CAS, some thread must have succeeded in
331 // removing the bias bit from the object's header.
332
333 if (ENABLE_BREAKPOINT) {
334 bkpt(object, mark, tmp, result);
335 }
336 revokeBias.inc();
337 }
338 }
339 }
340
341 // Create the unlocked mark word pattern
342 Word unlockedMark = mark.or(unlockedMask(INJECTED_VMCONFIG));
343 trace(trace, " unlockedMark: 0x%016lx\n", unlockedMark);
344
345 // Copy this unlocked mark word into the lock slot on the stack
346 lock.writeWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), unlockedMark, DISPLACED_MARK_WORD_LOCATION);
347
348 // Test if the object's mark word is unlocked, and if so, store the
349 // (address of) the lock slot into the object's mark word.
350 Word currentMark = compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), unlockedMark, lock, MARK_WORD_LOCATION);
351 if (probability(BranchProbabilityNode.SLOW_PATH_PROBABILITY, currentMark.notEqual(unlockedMark))) {
352 trace(trace, " currentMark: 0x%016lx\n", currentMark);
353 // The mark word in the object header was not the same.
354 // Either the object is locked by another thread or is already locked
355 // by the current thread. The latter is true if the mark word
356 // is a stack pointer into the current thread's stack, i.e.:
357 //
358 // 1) (currentMark & aligned_mask) == 0
359 // 2) rsp <= currentMark
360 // 3) currentMark <= rsp + page_size
361 //
362 // These 3 tests can be done by evaluating the following expression:
363 //
364 // (currentMark - rsp) & (aligned_mask - page_size)
365 //
366 // assuming both the stack pointer and page_size have their least
367 // significant 2 bits cleared and page_size is a power of 2
368 final Word alignedMask = Word.unsigned(wordSize() - 1);
369 final Word stackPointer = registerAsWord(stackPointerRegister).add(config(INJECTED_VMCONFIG).stackBias);
370 if (probability(VERY_SLOW_PATH_PROBABILITY, currentMark.subtract(stackPointer).and(alignedMask.subtract(pageSize())).notEqual(0))) {
371 // Most likely not a recursive lock, go into a slow runtime call
372 traceObject(trace, "+lock{stub:failed-cas}", object, true);
373 lockStubFailedCas.inc();
374 monitorenterStubC(MONITORENTER, object, lock);
375 return;
376 } else {
377 // Recursively locked => write 0 to the lock slot
378 lock.writeWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), Word.zero(), DISPLACED_MARK_WORD_LOCATION);
379 traceObject(trace, "+lock{cas:recursive}", object, true);
380 lockCasRecursive.inc();
381 }
382 } else {
383 traceObject(trace, "+lock{cas}", object, true);
384 lockCas.inc();
385 AcquiredCASLockNode.mark(object);
386 }
387 }
388
389 /**
390 * Calls straight out to the monitorenter stub.
391 */
392 @Snippet
393 public static void monitorenterStub(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
394 verifyOop(object);
395 incCounter();
396 if (object == null) {
397 DeoptimizeNode.deopt(DeoptimizationAction.InvalidateReprofile, DeoptimizationReason.NullCheckException);
398 }
399 // BeginLockScope nodes do not read from object so a use of object
400 // cannot float about the null check above
401 final Word lock = beginLockScope(lockDepth);
402 traceObject(trace, "+lock{stub}", object, true);
403 monitorenterStubC(MONITORENTER, object, lock);
404 }
405
406 @Snippet
407 public static void monitorexit(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
408 trace(trace, " object: 0x%016lx\n", Word.objectToTrackedPointer(object));
409 if (useBiasedLocking(INJECTED_VMCONFIG)) {
410 // Check for biased locking unlock case, which is a no-op
411 // Note: we do not have to check the thread ID for two reasons.
412 // First, the interpreter checks for IllegalMonitorStateException at
413 // a higher level. Second, if the bias was revoked while we held the
414 // lock, the object could not be rebiased toward another thread, so
415 // the bias bit would be clear.
416 final Word mark = loadWordFromObject(object, markOffset(INJECTED_VMCONFIG));
417 trace(trace, " mark: 0x%016lx\n", mark);
418 if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG)).equal(Word.unsigned(biasedLockPattern(INJECTED_VMCONFIG))))) {
419 endLockScope();
420 decCounter();
421 traceObject(trace, "-lock{bias}", object, false);
422 unlockBias.inc();
423 return;
424 }
425 }
426
427 final Word lock = CurrentLockNode.currentLock(lockDepth);
428
429 // Load displaced mark
430 final Word displacedMark = lock.readWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), DISPLACED_MARK_WORD_LOCATION);
431 trace(trace, " displacedMark: 0x%016lx\n", displacedMark);
432
433 if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, displacedMark.equal(0))) {
434 // Recursive locking => done
435 traceObject(trace, "-lock{recursive}", object, false);
436 unlockCasRecursive.inc();
437 } else {
438 verifyOop(object);
439 // Test if object's mark word is pointing to the displaced mark word, and if so, restore
440 // the displaced mark in the object - if the object's mark word is not pointing to
441 // the displaced mark word, do unlocking via runtime call.
442 if (probability(VERY_SLOW_PATH_PROBABILITY,
443 DirectCompareAndSwapNode.compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), lock, displacedMark, MARK_WORD_LOCATION).notEqual(lock))) {
444 // The object's mark word was not pointing to the displaced header,
445 // we do unlocking via runtime call.
446 traceObject(trace, "-lock{stub}", object, false);
447 unlockStub.inc();
448 monitorexitStubC(MONITOREXIT, object, lock);
449 } else {
450 traceObject(trace, "-lock{cas}", object, false);
451 unlockCas.inc();
452 }
453 }
454 endLockScope();
455 decCounter();
456 }
457
458 /**
459 * Calls straight out to the monitorexit stub.
460 */
461 @Snippet
462 public static void monitorexitStub(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
463 verifyOop(object);
464 traceObject(trace, "-lock{stub}", object, false);
465 final Word lock = CurrentLockNode.currentLock(lockDepth);
466 monitorexitStubC(MONITOREXIT, object, lock);
467 endLockScope();
468 decCounter();
469 }
470
471 public static void traceObject(boolean enabled, String action, Object object, boolean enter) {
472 if (doProfile()) {
473 DynamicCounterNode.counter(action, enter ? "number of monitor enters" : "number of monitor exits", 1, PROFILE_CONTEXT);
474 }
475 if (enabled) {
476 Log.print(action);
477 Log.print(' ');
478 Log.printlnObject(object);
479 }
480 }
481
482 public static void trace(boolean enabled, String format, WordBase value) {
483 if (enabled) {
484 Log.printf(format, value.rawValue());
485 }
486 }
487
488 /**
489 * Leaving the breakpoint code in to provide an example of how to use the {@link BreakpointNode}
490 * intrinsic.
491 */
492 private static final boolean ENABLE_BREAKPOINT = false;
493
494 private static final LocationIdentity MONITOR_COUNTER_LOCATION = NamedLocationIdentity.mutable("MonitorCounter");
495
496 @NodeIntrinsic(BreakpointNode.class)
497 static native void bkpt(Object object, Word mark, Word tmp, Word value);
498
499 private static final boolean VERIFY_BALANCED_MONITORS = VerifyBalancedMonitors.getValue();
500
501 public static void incCounter() {
502 if (VERIFY_BALANCED_MONITORS) {
503 final Word counter = MonitorCounterNode.counter();
504 final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
505 counter.writeInt(0, count + 1, MONITOR_COUNTER_LOCATION);
506 }
507 }
508
509 public static void decCounter() {
510 if (VERIFY_BALANCED_MONITORS) {
511 final Word counter = MonitorCounterNode.counter();
512 final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
513 counter.writeInt(0, count - 1, MONITOR_COUNTER_LOCATION);
514 }
515 }
516
517 @Snippet
518 private static void initCounter() {
519 final Word counter = MonitorCounterNode.counter();
520 counter.writeInt(0, 0, MONITOR_COUNTER_LOCATION);
521 }
522
523 @Snippet
524 private static void checkCounter(@ConstantParameter String errMsg) {
525 final Word counter = MonitorCounterNode.counter();
526 final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
527 if (count != 0) {
528 vmError(errMsg, count);
529 }
530 }
531
532 public static class Templates extends AbstractTemplates {
533
534 private final SnippetInfo monitorenter = snippet(MonitorSnippets.class, "monitorenter");
535 private final SnippetInfo monitorexit = snippet(MonitorSnippets.class, "monitorexit");
536 private final SnippetInfo monitorenterStub = snippet(MonitorSnippets.class, "monitorenterStub");
537 private final SnippetInfo monitorexitStub = snippet(MonitorSnippets.class, "monitorexitStub");
538 private final SnippetInfo initCounter = snippet(MonitorSnippets.class, "initCounter");
539 private final SnippetInfo checkCounter = snippet(MonitorSnippets.class, "checkCounter");
540
541 private final boolean useFastLocking;
542
543 public Templates(HotSpotProviders providers, TargetDescription target, boolean useFastLocking) {
544 super(providers, providers.getSnippetReflection(), target);
545 this.useFastLocking = useFastLocking;
546 }
547
548 public void lower(RawMonitorEnterNode monitorenterNode, HotSpotRegistersProvider registers, LoweringTool tool) {
549 StructuredGraph graph = monitorenterNode.graph();
550 checkBalancedMonitors(graph, tool);
551
552 assert ((ObjectStamp) monitorenterNode.object().stamp()).nonNull();
553
554 Arguments args;
555 if (useFastLocking) {
556 args = new Arguments(monitorenter, graph.getGuardsStage(), tool.getLoweringStage());
557 args.add("object", monitorenterNode.object());
558 args.add("hub", monitorenterNode.getHub());
559 args.addConst("lockDepth", monitorenterNode.getMonitorId().getLockDepth());
560 args.addConst("threadRegister", registers.getThreadRegister());
561 args.addConst("stackPointerRegister", registers.getStackPointerRegister());
562 args.addConst("trace", isTracingEnabledForType(monitorenterNode.object()) || isTracingEnabledForMethod(graph.method()));
563 } else {
564 args = new Arguments(monitorenterStub, graph.getGuardsStage(), tool.getLoweringStage());
565 args.add("object", monitorenterNode.object());
566 args.addConst("lockDepth", monitorenterNode.getMonitorId().getLockDepth());
567 args.addConst("trace", isTracingEnabledForType(monitorenterNode.object()) || isTracingEnabledForMethod(graph.method()));
568 }
569
570 template(args).instantiate(providers.getMetaAccess(), monitorenterNode, DEFAULT_REPLACER, args);
571 }
572
573 public void lower(MonitorExitNode monitorexitNode, LoweringTool tool) {
574 StructuredGraph graph = monitorexitNode.graph();
575
576 Arguments args;
577 if (useFastLocking) {
578 args = new Arguments(monitorexit, graph.getGuardsStage(), tool.getLoweringStage());
579 } else {
580 args = new Arguments(monitorexitStub, graph.getGuardsStage(), tool.getLoweringStage());
581 }
582 args.add("object", monitorexitNode.object());
583 args.addConst("lockDepth", monitorexitNode.getMonitorId().getLockDepth());
584 args.addConst("trace", isTracingEnabledForType(monitorexitNode.object()) || isTracingEnabledForMethod(graph.method()));
585
586 template(args).instantiate(providers.getMetaAccess(), monitorexitNode, DEFAULT_REPLACER, args);
587 }
588
589 public static boolean isTracingEnabledForType(ValueNode object) {
590 ResolvedJavaType type = StampTool.typeOrNull(object.stamp());
591 String filter = TraceMonitorsTypeFilter.getValue();
592 if (filter == null) {
593 return false;
594 } else {
595 if (filter.length() == 0) {
596 return true;
597 }
598 if (type == null) {
599 return false;
600 }
601 return (type.getName().contains(filter));
602 }
603 }
604
605 public static boolean isTracingEnabledForMethod(ResolvedJavaMethod method) {
606 String filter = TraceMonitorsMethodFilter.getValue();
607 if (filter == null) {
608 return false;
609 } else {
610 if (filter.length() == 0) {
611 return true;
612 }
613 if (method == null) {
614 return false;
615 }
616 return (method.format("%H.%n").contains(filter));
617 }
618 }
619
620 /**
621 * If balanced monitor checking is enabled then nodes are inserted at the start and all
622 * return points of the graph to initialize and check the monitor counter respectively.
623 */
624 private void checkBalancedMonitors(StructuredGraph graph, LoweringTool tool) {
625 if (VERIFY_BALANCED_MONITORS) {
626 NodeIterable<MonitorCounterNode> nodes = graph.getNodes().filter(MonitorCounterNode.class);
627 if (nodes.isEmpty()) {
628 // Only insert the nodes if this is the first monitorenter being lowered.
629 JavaType returnType = initCounter.getMethod().getSignature().getReturnType(initCounter.getMethod().getDeclaringClass());
630 StampPair returnStamp = StampFactory.forDeclaredType(graph.getAssumptions(), returnType, false);
631 MethodCallTargetNode callTarget = graph.add(new MethodCallTargetNode(InvokeKind.Static, initCounter.getMethod(), new ValueNode[0], returnStamp, null));
632 InvokeNode invoke = graph.add(new InvokeNode(callTarget, 0));
633 invoke.setStateAfter(graph.start().stateAfter());
634 graph.addAfterFixed(graph.start(), invoke);
635
636 StructuredGraph inlineeGraph = providers.getReplacements().getSnippet(initCounter.getMethod(), null);
637 InliningUtil.inline(invoke, inlineeGraph, false, null, null);
638
639 List<ReturnNode> rets = graph.getNodes(ReturnNode.TYPE).snapshot();
640 for (ReturnNode ret : rets) {
641 returnType = checkCounter.getMethod().getSignature().getReturnType(checkCounter.getMethod().getDeclaringClass());
642 String msg = "unbalanced monitors in " + graph.method().format("%H.%n(%p)") + ", count = %d";
643 ConstantNode errMsg = ConstantNode.forConstant(tool.getConstantReflection().forString(msg), providers.getMetaAccess(), graph);
644 returnStamp = StampFactory.forDeclaredType(graph.getAssumptions(), returnType, false);
645 callTarget = graph.add(new MethodCallTargetNode(InvokeKind.Static, checkCounter.getMethod(), new ValueNode[]{errMsg}, returnStamp, null));
646 invoke = graph.add(new InvokeNode(callTarget, 0));
647 Bytecode code = new ResolvedJavaMethodBytecode(graph.method());
648 FrameState stateAfter = new FrameState(null, code, BytecodeFrame.AFTER_BCI, new ValueNode[0], new ValueNode[0], 0, new ValueNode[0], null, false, false);
649 invoke.setStateAfter(graph.add(stateAfter));
650 graph.addBeforeFixed(ret, invoke);
651
652 Arguments args = new Arguments(checkCounter, graph.getGuardsStage(), tool.getLoweringStage());
653 args.addConst("errMsg", msg);
654 inlineeGraph = template(args).copySpecializedGraph();
655 InliningUtil.inline(invoke, inlineeGraph, false, null, null);
656 }
657 }
658 }
659 }
660 }
661
662 public static final ForeignCallDescriptor MONITORENTER = new ForeignCallDescriptor("monitorenter", void.class, Object.class, Word.class);
663 public static final ForeignCallDescriptor MONITOREXIT = new ForeignCallDescriptor("monitorexit", void.class, Object.class, Word.class);
664
665 @NodeIntrinsic(ForeignCallNode.class)
666 private static native void monitorenterStubC(@ConstantNodeParameter ForeignCallDescriptor descriptor, Object object, Word lock);
667
668 @NodeIntrinsic(ForeignCallNode.class)
669 public static native void monitorexitStubC(@ConstantNodeParameter ForeignCallDescriptor descriptor, Object object, Word lock);
670
671 /**
672 * Counters for the various paths for acquiring a lock. The counters whose names start with
673 * {@code "lock"} are mutually exclusive. The other counters are for paths that may be shared.
674 */
675 public static final SnippetCounter.Group lockCounters = SnippetCounters.getValue() ? new SnippetCounter.Group("MonitorEnters") : null;
676 public static final SnippetCounter lockBiasExisting = new SnippetCounter(lockCounters, "lock{bias:existing}", "bias-locked previously biased object");
677 public static final SnippetCounter lockBiasAcquired = new SnippetCounter(lockCounters, "lock{bias:acquired}", "bias-locked newly biased object");
678 public static final SnippetCounter lockBiasTransfer = new SnippetCounter(lockCounters, "lock{bias:transfer}", "bias-locked, biased transferred");
679 public static final SnippetCounter lockCas = new SnippetCounter(lockCounters, "lock{cas}", "cas-locked an object");
680 public static final SnippetCounter lockCasRecursive = new SnippetCounter(lockCounters, "lock{cas:recursive}", "cas-locked, recursive");
681 public static final SnippetCounter lockStubEpochExpired = new SnippetCounter(lockCounters, "lock{stub:epoch-expired}", "stub-locked, epoch expired");
682 public static final SnippetCounter lockStubRevoke = new SnippetCounter(lockCounters, "lock{stub:revoke}", "stub-locked, biased revoked");
683 public static final SnippetCounter lockStubFailedCas = new SnippetCounter(lockCounters, "lock{stub:failed-cas}", "stub-locked, failed cas");
684
685 public static final SnippetCounter unbiasable = new SnippetCounter(lockCounters, "unbiasable", "object with unbiasable type");
686 public static final SnippetCounter revokeBias = new SnippetCounter(lockCounters, "revokeBias", "object had bias revoked");
687
688 /**
689 * Counters for the various paths for releasing a lock. The counters whose names start with
690 * {@code "unlock"} are mutually exclusive. The other counters are for paths that may be shared.
691 */
692 public static final SnippetCounter.Group unlockCounters = SnippetCounters.getValue() ? new SnippetCounter.Group("MonitorExits") : null;
693 public static final SnippetCounter unlockBias = new SnippetCounter(unlockCounters, "unlock{bias}", "bias-unlocked an object");
694 public static final SnippetCounter unlockCas = new SnippetCounter(unlockCounters, "unlock{cas}", "cas-unlocked an object");
695 public static final SnippetCounter unlockCasRecursive = new SnippetCounter(unlockCounters, "unlock{cas:recursive}", "cas-unlocked an object, recursive");
696 public static final SnippetCounter unlockStub = new SnippetCounter(unlockCounters, "unlock{stub}", "stub-unlocked an object");
697 }