/*
* Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package org.graalvm.compiler.hotspot.replacements;
import static org.graalvm.compiler.core.common.GraalOptions.SnippetCounters;
import static org.graalvm.compiler.hotspot.GraalHotSpotVMConfig.INJECTED_VMCONFIG;
import static org.graalvm.compiler.hotspot.nodes.BeginLockScopeNode.beginLockScope;
import static org.graalvm.compiler.hotspot.nodes.DirectCompareAndSwapNode.compareAndSwap;
import static org.graalvm.compiler.hotspot.nodes.EndLockScopeNode.endLockScope;
import static org.graalvm.compiler.hotspot.nodes.VMErrorNode.vmError;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.DISPLACED_MARK_WORD_LOCATION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.MARK_WORD_LOCATION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.PROTOTYPE_MARK_WORD_LOCATION;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.ageMaskInPlace;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.biasedLockMaskInPlace;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.biasedLockPattern;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.config;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.epochMaskInPlace;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.loadWordFromObject;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.lockDisplacedMarkOffset;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.markOffset;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.pageSize;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.prototypeMarkWordOffset;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.registerAsWord;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.unlockedMask;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.useBiasedLocking;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.verifyOop;
import static org.graalvm.compiler.hotspot.replacements.HotSpotReplacementsUtil.wordSize;
import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.ProfileMonitors;
import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.TraceMonitorsMethodFilter;
import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.TraceMonitorsTypeFilter;
import static org.graalvm.compiler.hotspot.replacements.HotspotSnippetsOptions.VerifyBalancedMonitors;
import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.FREQUENT_PROBABILITY;
import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.VERY_FAST_PATH_PROBABILITY;
import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.VERY_SLOW_PATH_PROBABILITY;
import static org.graalvm.compiler.nodes.extended.BranchProbabilityNode.probability;
import static org.graalvm.compiler.replacements.SnippetTemplate.DEFAULT_REPLACER;
import java.util.List;
import org.graalvm.compiler.api.replacements.Fold;
import org.graalvm.compiler.api.replacements.Snippet;
import org.graalvm.compiler.api.replacements.Snippet.ConstantParameter;
import org.graalvm.compiler.bytecode.Bytecode;
import org.graalvm.compiler.bytecode.ResolvedJavaMethodBytecode;
import org.graalvm.compiler.core.common.LocationIdentity;
import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;
import org.graalvm.compiler.core.common.type.ObjectStamp;
import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.core.common.type.StampPair;
import org.graalvm.compiler.graph.Node.ConstantNodeParameter;
import org.graalvm.compiler.graph.Node.NodeIntrinsic;
import org.graalvm.compiler.graph.iterators.NodeIterable;
import org.graalvm.compiler.hotspot.meta.HotSpotProviders;
import org.graalvm.compiler.hotspot.meta.HotSpotRegistersProvider;
import org.graalvm.compiler.hotspot.nodes.AcquiredCASLockNode;
import org.graalvm.compiler.hotspot.nodes.CurrentLockNode;
import org.graalvm.compiler.hotspot.nodes.DirectCompareAndSwapNode;
import org.graalvm.compiler.hotspot.nodes.FastAcquireBiasedLockNode;
import org.graalvm.compiler.hotspot.nodes.MonitorCounterNode;
import org.graalvm.compiler.hotspot.word.KlassPointer;
import org.graalvm.compiler.nodes.BreakpointNode;
import org.graalvm.compiler.nodes.CallTargetNode.InvokeKind;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.DeoptimizeNode;
import org.graalvm.compiler.nodes.FrameState;
import org.graalvm.compiler.nodes.InvokeNode;
import org.graalvm.compiler.nodes.NamedLocationIdentity;
import org.graalvm.compiler.nodes.ReturnNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.debug.DynamicCounterNode;
import org.graalvm.compiler.nodes.extended.BranchProbabilityNode;
import org.graalvm.compiler.nodes.extended.ForeignCallNode;
import org.graalvm.compiler.nodes.java.MethodCallTargetNode;
import org.graalvm.compiler.nodes.java.MonitorExitNode;
import org.graalvm.compiler.nodes.java.RawMonitorEnterNode;
import org.graalvm.compiler.nodes.memory.address.OffsetAddressNode;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import org.graalvm.compiler.nodes.type.StampTool;
import org.graalvm.compiler.phases.common.inlining.InliningUtil;
import org.graalvm.compiler.replacements.Log;
import org.graalvm.compiler.replacements.SnippetCounter;
import org.graalvm.compiler.replacements.SnippetTemplate.AbstractTemplates;
import org.graalvm.compiler.replacements.SnippetTemplate.Arguments;
import org.graalvm.compiler.replacements.SnippetTemplate.SnippetInfo;
import org.graalvm.compiler.replacements.Snippets;
import org.graalvm.compiler.word.Word;
import org.graalvm.compiler.word.WordBase;
import jdk.vm.ci.code.BytecodeFrame;
import jdk.vm.ci.code.Register;
import jdk.vm.ci.code.TargetDescription;
import jdk.vm.ci.meta.DeoptimizationAction;
import jdk.vm.ci.meta.DeoptimizationReason;
import jdk.vm.ci.meta.JavaType;
import jdk.vm.ci.meta.ResolvedJavaMethod;
import jdk.vm.ci.meta.ResolvedJavaType;
/**
* Snippets used for implementing the monitorenter and monitorexit instructions.
*
* The locking algorithm used is described in the paper
* Eliminating synchronization-related
* atomic operations with biased locking and bulk rebiasing by Kenneth Russell and David
* Detlefs.
*
* Comment below is reproduced from {@code markOop.hpp} for convenience:
*
*
* Bit-format of an object header (most significant first, big endian layout below):
* 32 bits:
* --------
* hash:25 ------------>| age:4 biased_lock:1 lock:2 (normal object)
* JavaThread*:23 epoch:2 age:4 biased_lock:1 lock:2 (biased object)
* size:32 ------------------------------------------>| (CMS free block)
* PromotedObject*:29 ---------->| promo_bits:3 ----->| (CMS promoted object)
*
* 64 bits:
* --------
* unused:25 hash:31 -->| unused:1 age:4 biased_lock:1 lock:2 (normal object)
* JavaThread*:54 epoch:2 unused:1 age:4 biased_lock:1 lock:2 (biased object)
* PromotedObject*:61 --------------------->| promo_bits:3 ----->| (CMS promoted object)
* size:64 ----------------------------------------------------->| (CMS free block)
*
* unused:25 hash:31 -->| cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && normal object)
* JavaThread*:54 epoch:2 cms_free:1 age:4 biased_lock:1 lock:2 (COOPs && biased object)
* narrowOop:32 unused:24 cms_free:1 unused:4 promo_bits:3 ----->| (COOPs && CMS promoted object)
* unused:21 size:35 -->| cms_free:1 unused:7 ------------------>| (COOPs && CMS free block)
*
* - hash contains the identity hash value: largest value is
* 31 bits, see os::random(). Also, 64-bit vm's require
* a hash value no bigger than 32 bits because they will not
* properly generate a mask larger than that: see library_call.cpp
* and c1_CodePatterns_sparc.cpp.
*
* - the biased lock pattern is used to bias a lock toward a given
* thread. When this pattern is set in the low three bits, the lock
* is either biased toward a given thread or "anonymously" biased,
* indicating that it is possible for it to be biased. When the
* lock is biased toward a given thread, locking and unlocking can
* be performed by that thread without using atomic operations.
* When a lock's bias is revoked, it reverts back to the normal
* locking scheme described below.
*
* Note that we are overloading the meaning of the "unlocked" state
* of the header. Because we steal a bit from the age we can
* guarantee that the bias pattern will never be seen for a truly
* unlocked object.
*
* Note also that the biased state contains the age bits normally
* contained in the object header. Large increases in scavenge
* times were seen when these bits were absent and an arbitrary age
* assigned to all biased objects, because they tended to consume a
* significant fraction of the eden semispaces and were not
* promoted promptly, causing an increase in the amount of copying
* performed. The runtime system aligns all JavaThread* pointers to
* a very large value (currently 128 bytes (32bVM) or 256 bytes (64bVM))
* to make room for the age bits & the epoch bits (used in support of
* biased locking), and for the CMS "freeness" bit in the 64bVM (+COOPs).
*
* [JavaThread* | epoch | age | 1 | 01] lock is biased toward given thread
* [0 | epoch | age | 1 | 01] lock is anonymously biased
*
* - the two lock bits are used to describe three states: locked/unlocked and monitor.
*
* [ptr | 00] locked ptr points to real header on stack
* [header | 0 | 01] unlocked regular object header
* [ptr | 10] monitor inflated lock (header is wapped out)
* [ptr | 11] marked used by markSweep to mark an object
* not valid at any other time
*
* We assume that stack/thread pointers have the lowest two bits cleared.
*
*
* Note that {@code Thread::allocate} enforces {@code JavaThread} objects to be aligned
* appropriately to comply with the layouts above.
*/
public class MonitorSnippets implements Snippets {
private static final boolean PROFILE_CONTEXT = false;
@Fold
static boolean doProfile() {
return ProfileMonitors.getValue();
}
@Snippet
public static void monitorenter(Object object, KlassPointer hub, @ConstantParameter int lockDepth, @ConstantParameter Register threadRegister, @ConstantParameter Register stackPointerRegister,
@ConstantParameter boolean trace) {
verifyOop(object);
// Load the mark word - this includes a null-check on object
final Word mark = loadWordFromObject(object, markOffset(INJECTED_VMCONFIG));
final Word lock = beginLockScope(lockDepth);
trace(trace, " object: 0x%016lx\n", Word.objectToTrackedPointer(object));
trace(trace, " lock: 0x%016lx\n", lock);
trace(trace, " mark: 0x%016lx\n", mark);
incCounter();
if (useBiasedLocking(INJECTED_VMCONFIG)) {
// See whether the lock is currently biased toward our thread and
// whether the epoch is still valid.
// Note that the runtime guarantees sufficient alignment of JavaThread
// pointers to allow age to be placed into low bits.
final Word biasableLockBits = mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG));
// Check whether the bias pattern is present in the object's mark word
// and the bias owner and the epoch are both still current.
final Word prototypeMarkWord = hub.readWord(prototypeMarkWordOffset(INJECTED_VMCONFIG), PROTOTYPE_MARK_WORD_LOCATION);
final Word thread = registerAsWord(threadRegister);
final Word tmp = prototypeMarkWord.or(thread).xor(mark).and(~ageMaskInPlace(INJECTED_VMCONFIG));
trace(trace, "prototypeMarkWord: 0x%016lx\n", prototypeMarkWord);
trace(trace, " thread: 0x%016lx\n", thread);
trace(trace, " tmp: 0x%016lx\n", tmp);
if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, tmp.equal(0))) {
// Object is already biased to current thread -> done
traceObject(trace, "+lock{bias:existing}", object, true);
lockBiasExisting.inc();
FastAcquireBiasedLockNode.mark(object);
return;
}
// Now check to see whether biasing is enabled for this object
if (probability(BranchProbabilityNode.FAST_PATH_PROBABILITY, biasableLockBits.notEqual(Word.unsigned(biasedLockPattern(INJECTED_VMCONFIG))))) {
// Biasing not enabled -> fall through to lightweight locking
unbiasable.inc();
} else {
// At this point we know that the mark word has the bias pattern and
// that we are not the bias owner in the current epoch. We need to
// figure out more details about the state of the mark word in order to
// know what operations can be legally performed on the object's
// mark word.
// If the low three bits in the xor result aren't clear, that means
// the prototype header is no longer biasable and we have to revoke
// the bias on this object.
if (probability(FREQUENT_PROBABILITY, tmp.and(biasedLockMaskInPlace(INJECTED_VMCONFIG)).equal(0))) {
// Biasing is still enabled for object's type. See whether the
// epoch of the current bias is still valid, meaning that the epoch
// bits of the mark word are equal to the epoch bits of the
// prototype mark word. (Note that the prototype mark word's epoch bits
// only change at a safepoint.) If not, attempt to rebias the object
// toward the current thread. Note that we must be absolutely sure
// that the current epoch is invalid in order to do this because
// otherwise the manipulations it performs on the mark word are
// illegal.
if (probability(FREQUENT_PROBABILITY, tmp.and(epochMaskInPlace(INJECTED_VMCONFIG)).equal(0))) {
// The epoch of the current bias is still valid but we know nothing
// about the owner; it might be set or it might be clear. Try to
// acquire the bias of the object using an atomic operation. If this
// fails we will go in to the runtime to revoke the object's bias.
// Note that we first construct the presumed unbiased header so we
// don't accidentally blow away another thread's valid bias.
Word unbiasedMark = mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG) | ageMaskInPlace(INJECTED_VMCONFIG) | epochMaskInPlace(INJECTED_VMCONFIG));
Word biasedMark = unbiasedMark.or(thread);
trace(trace, " unbiasedMark: 0x%016lx\n", unbiasedMark);
trace(trace, " biasedMark: 0x%016lx\n", biasedMark);
if (probability(VERY_FAST_PATH_PROBABILITY,
compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), unbiasedMark, biasedMark, MARK_WORD_LOCATION).equal(unbiasedMark))) {
// Object is now biased to current thread -> done
traceObject(trace, "+lock{bias:acquired}", object, true);
lockBiasAcquired.inc();
return;
}
// If the biasing toward our thread failed, this means that another thread
// owns the bias and we need to revoke that bias. The revocation will occur
// in the interpreter runtime.
traceObject(trace, "+lock{stub:revoke}", object, true);
lockStubRevoke.inc();
} else {
// At this point we know the epoch has expired, meaning that the
// current bias owner, if any, is actually invalid. Under these
// circumstances _only_, are we allowed to use the current mark word
// value as the comparison value when doing the CAS to acquire the
// bias in the current epoch. In other words, we allow transfer of
// the bias from one thread to another directly in this situation.
Word biasedMark = prototypeMarkWord.or(thread);
trace(trace, " biasedMark: 0x%016lx\n", biasedMark);
if (probability(VERY_FAST_PATH_PROBABILITY,
compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), mark, biasedMark, MARK_WORD_LOCATION).equal(mark))) {
// Object is now biased to current thread -> done
traceObject(trace, "+lock{bias:transfer}", object, true);
lockBiasTransfer.inc();
return;
}
// If the biasing toward our thread failed, then another thread
// succeeded in biasing it toward itself and we need to revoke that
// bias. The revocation will occur in the runtime in the slow case.
traceObject(trace, "+lock{stub:epoch-expired}", object, true);
lockStubEpochExpired.inc();
}
monitorenterStubC(MONITORENTER, object, lock);
return;
} else {
// The prototype mark word doesn't have the bias bit set any
// more, indicating that objects of this data type are not supposed
// to be biased any more. We are going to try to reset the mark of
// this object to the prototype value and fall through to the
// CAS-based locking scheme. Note that if our CAS fails, it means
// that another thread raced us for the privilege of revoking the
// bias of this particular object, so it's okay to continue in the
// normal locking code.
Word result = compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), mark, prototypeMarkWord, MARK_WORD_LOCATION);
// Fall through to the normal CAS-based lock, because no matter what
// the result of the above CAS, some thread must have succeeded in
// removing the bias bit from the object's header.
if (ENABLE_BREAKPOINT) {
bkpt(object, mark, tmp, result);
}
revokeBias.inc();
}
}
}
// Create the unlocked mark word pattern
Word unlockedMark = mark.or(unlockedMask(INJECTED_VMCONFIG));
trace(trace, " unlockedMark: 0x%016lx\n", unlockedMark);
// Copy this unlocked mark word into the lock slot on the stack
lock.writeWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), unlockedMark, DISPLACED_MARK_WORD_LOCATION);
// Test if the object's mark word is unlocked, and if so, store the
// (address of) the lock slot into the object's mark word.
Word currentMark = compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), unlockedMark, lock, MARK_WORD_LOCATION);
if (probability(BranchProbabilityNode.SLOW_PATH_PROBABILITY, currentMark.notEqual(unlockedMark))) {
trace(trace, " currentMark: 0x%016lx\n", currentMark);
// The mark word in the object header was not the same.
// Either the object is locked by another thread or is already locked
// by the current thread. The latter is true if the mark word
// is a stack pointer into the current thread's stack, i.e.:
//
// 1) (currentMark & aligned_mask) == 0
// 2) rsp <= currentMark
// 3) currentMark <= rsp + page_size
//
// These 3 tests can be done by evaluating the following expression:
//
// (currentMark - rsp) & (aligned_mask - page_size)
//
// assuming both the stack pointer and page_size have their least
// significant 2 bits cleared and page_size is a power of 2
final Word alignedMask = Word.unsigned(wordSize() - 1);
final Word stackPointer = registerAsWord(stackPointerRegister).add(config(INJECTED_VMCONFIG).stackBias);
if (probability(VERY_SLOW_PATH_PROBABILITY, currentMark.subtract(stackPointer).and(alignedMask.subtract(pageSize())).notEqual(0))) {
// Most likely not a recursive lock, go into a slow runtime call
traceObject(trace, "+lock{stub:failed-cas}", object, true);
lockStubFailedCas.inc();
monitorenterStubC(MONITORENTER, object, lock);
return;
} else {
// Recursively locked => write 0 to the lock slot
lock.writeWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), Word.zero(), DISPLACED_MARK_WORD_LOCATION);
traceObject(trace, "+lock{cas:recursive}", object, true);
lockCasRecursive.inc();
}
} else {
traceObject(trace, "+lock{cas}", object, true);
lockCas.inc();
AcquiredCASLockNode.mark(object);
}
}
/**
* Calls straight out to the monitorenter stub.
*/
@Snippet
public static void monitorenterStub(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
verifyOop(object);
incCounter();
if (object == null) {
DeoptimizeNode.deopt(DeoptimizationAction.InvalidateReprofile, DeoptimizationReason.NullCheckException);
}
// BeginLockScope nodes do not read from object so a use of object
// cannot float about the null check above
final Word lock = beginLockScope(lockDepth);
traceObject(trace, "+lock{stub}", object, true);
monitorenterStubC(MONITORENTER, object, lock);
}
@Snippet
public static void monitorexit(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
trace(trace, " object: 0x%016lx\n", Word.objectToTrackedPointer(object));
if (useBiasedLocking(INJECTED_VMCONFIG)) {
// Check for biased locking unlock case, which is a no-op
// Note: we do not have to check the thread ID for two reasons.
// First, the interpreter checks for IllegalMonitorStateException at
// a higher level. Second, if the bias was revoked while we held the
// lock, the object could not be rebiased toward another thread, so
// the bias bit would be clear.
final Word mark = loadWordFromObject(object, markOffset(INJECTED_VMCONFIG));
trace(trace, " mark: 0x%016lx\n", mark);
if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, mark.and(biasedLockMaskInPlace(INJECTED_VMCONFIG)).equal(Word.unsigned(biasedLockPattern(INJECTED_VMCONFIG))))) {
endLockScope();
decCounter();
traceObject(trace, "-lock{bias}", object, false);
unlockBias.inc();
return;
}
}
final Word lock = CurrentLockNode.currentLock(lockDepth);
// Load displaced mark
final Word displacedMark = lock.readWord(lockDisplacedMarkOffset(INJECTED_VMCONFIG), DISPLACED_MARK_WORD_LOCATION);
trace(trace, " displacedMark: 0x%016lx\n", displacedMark);
if (probability(BranchProbabilityNode.NOT_LIKELY_PROBABILITY, displacedMark.equal(0))) {
// Recursive locking => done
traceObject(trace, "-lock{recursive}", object, false);
unlockCasRecursive.inc();
} else {
verifyOop(object);
// Test if object's mark word is pointing to the displaced mark word, and if so, restore
// the displaced mark in the object - if the object's mark word is not pointing to
// the displaced mark word, do unlocking via runtime call.
if (probability(VERY_SLOW_PATH_PROBABILITY,
DirectCompareAndSwapNode.compareAndSwap(OffsetAddressNode.address(object, markOffset(INJECTED_VMCONFIG)), lock, displacedMark, MARK_WORD_LOCATION).notEqual(lock))) {
// The object's mark word was not pointing to the displaced header,
// we do unlocking via runtime call.
traceObject(trace, "-lock{stub}", object, false);
unlockStub.inc();
monitorexitStubC(MONITOREXIT, object, lock);
} else {
traceObject(trace, "-lock{cas}", object, false);
unlockCas.inc();
}
}
endLockScope();
decCounter();
}
/**
* Calls straight out to the monitorexit stub.
*/
@Snippet
public static void monitorexitStub(Object object, @ConstantParameter int lockDepth, @ConstantParameter boolean trace) {
verifyOop(object);
traceObject(trace, "-lock{stub}", object, false);
final Word lock = CurrentLockNode.currentLock(lockDepth);
monitorexitStubC(MONITOREXIT, object, lock);
endLockScope();
decCounter();
}
public static void traceObject(boolean enabled, String action, Object object, boolean enter) {
if (doProfile()) {
DynamicCounterNode.counter(action, enter ? "number of monitor enters" : "number of monitor exits", 1, PROFILE_CONTEXT);
}
if (enabled) {
Log.print(action);
Log.print(' ');
Log.printlnObject(object);
}
}
public static void trace(boolean enabled, String format, WordBase value) {
if (enabled) {
Log.printf(format, value.rawValue());
}
}
/**
* Leaving the breakpoint code in to provide an example of how to use the {@link BreakpointNode}
* intrinsic.
*/
private static final boolean ENABLE_BREAKPOINT = false;
private static final LocationIdentity MONITOR_COUNTER_LOCATION = NamedLocationIdentity.mutable("MonitorCounter");
@NodeIntrinsic(BreakpointNode.class)
static native void bkpt(Object object, Word mark, Word tmp, Word value);
private static final boolean VERIFY_BALANCED_MONITORS = VerifyBalancedMonitors.getValue();
public static void incCounter() {
if (VERIFY_BALANCED_MONITORS) {
final Word counter = MonitorCounterNode.counter();
final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
counter.writeInt(0, count + 1, MONITOR_COUNTER_LOCATION);
}
}
public static void decCounter() {
if (VERIFY_BALANCED_MONITORS) {
final Word counter = MonitorCounterNode.counter();
final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
counter.writeInt(0, count - 1, MONITOR_COUNTER_LOCATION);
}
}
@Snippet
private static void initCounter() {
final Word counter = MonitorCounterNode.counter();
counter.writeInt(0, 0, MONITOR_COUNTER_LOCATION);
}
@Snippet
private static void checkCounter(@ConstantParameter String errMsg) {
final Word counter = MonitorCounterNode.counter();
final int count = counter.readInt(0, MONITOR_COUNTER_LOCATION);
if (count != 0) {
vmError(errMsg, count);
}
}
public static class Templates extends AbstractTemplates {
private final SnippetInfo monitorenter = snippet(MonitorSnippets.class, "monitorenter");
private final SnippetInfo monitorexit = snippet(MonitorSnippets.class, "monitorexit");
private final SnippetInfo monitorenterStub = snippet(MonitorSnippets.class, "monitorenterStub");
private final SnippetInfo monitorexitStub = snippet(MonitorSnippets.class, "monitorexitStub");
private final SnippetInfo initCounter = snippet(MonitorSnippets.class, "initCounter");
private final SnippetInfo checkCounter = snippet(MonitorSnippets.class, "checkCounter");
private final boolean useFastLocking;
public Templates(HotSpotProviders providers, TargetDescription target, boolean useFastLocking) {
super(providers, providers.getSnippetReflection(), target);
this.useFastLocking = useFastLocking;
}
public void lower(RawMonitorEnterNode monitorenterNode, HotSpotRegistersProvider registers, LoweringTool tool) {
StructuredGraph graph = monitorenterNode.graph();
checkBalancedMonitors(graph, tool);
assert ((ObjectStamp) monitorenterNode.object().stamp()).nonNull();
Arguments args;
if (useFastLocking) {
args = new Arguments(monitorenter, graph.getGuardsStage(), tool.getLoweringStage());
args.add("object", monitorenterNode.object());
args.add("hub", monitorenterNode.getHub());
args.addConst("lockDepth", monitorenterNode.getMonitorId().getLockDepth());
args.addConst("threadRegister", registers.getThreadRegister());
args.addConst("stackPointerRegister", registers.getStackPointerRegister());
args.addConst("trace", isTracingEnabledForType(monitorenterNode.object()) || isTracingEnabledForMethod(graph.method()));
} else {
args = new Arguments(monitorenterStub, graph.getGuardsStage(), tool.getLoweringStage());
args.add("object", monitorenterNode.object());
args.addConst("lockDepth", monitorenterNode.getMonitorId().getLockDepth());
args.addConst("trace", isTracingEnabledForType(monitorenterNode.object()) || isTracingEnabledForMethod(graph.method()));
}
template(args).instantiate(providers.getMetaAccess(), monitorenterNode, DEFAULT_REPLACER, args);
}
public void lower(MonitorExitNode monitorexitNode, LoweringTool tool) {
StructuredGraph graph = monitorexitNode.graph();
Arguments args;
if (useFastLocking) {
args = new Arguments(monitorexit, graph.getGuardsStage(), tool.getLoweringStage());
} else {
args = new Arguments(monitorexitStub, graph.getGuardsStage(), tool.getLoweringStage());
}
args.add("object", monitorexitNode.object());
args.addConst("lockDepth", monitorexitNode.getMonitorId().getLockDepth());
args.addConst("trace", isTracingEnabledForType(monitorexitNode.object()) || isTracingEnabledForMethod(graph.method()));
template(args).instantiate(providers.getMetaAccess(), monitorexitNode, DEFAULT_REPLACER, args);
}
public static boolean isTracingEnabledForType(ValueNode object) {
ResolvedJavaType type = StampTool.typeOrNull(object.stamp());
String filter = TraceMonitorsTypeFilter.getValue();
if (filter == null) {
return false;
} else {
if (filter.length() == 0) {
return true;
}
if (type == null) {
return false;
}
return (type.getName().contains(filter));
}
}
public static boolean isTracingEnabledForMethod(ResolvedJavaMethod method) {
String filter = TraceMonitorsMethodFilter.getValue();
if (filter == null) {
return false;
} else {
if (filter.length() == 0) {
return true;
}
if (method == null) {
return false;
}
return (method.format("%H.%n").contains(filter));
}
}
/**
* If balanced monitor checking is enabled then nodes are inserted at the start and all
* return points of the graph to initialize and check the monitor counter respectively.
*/
private void checkBalancedMonitors(StructuredGraph graph, LoweringTool tool) {
if (VERIFY_BALANCED_MONITORS) {
NodeIterable nodes = graph.getNodes().filter(MonitorCounterNode.class);
if (nodes.isEmpty()) {
// Only insert the nodes if this is the first monitorenter being lowered.
JavaType returnType = initCounter.getMethod().getSignature().getReturnType(initCounter.getMethod().getDeclaringClass());
StampPair returnStamp = StampFactory.forDeclaredType(graph.getAssumptions(), returnType, false);
MethodCallTargetNode callTarget = graph.add(new MethodCallTargetNode(InvokeKind.Static, initCounter.getMethod(), new ValueNode[0], returnStamp, null));
InvokeNode invoke = graph.add(new InvokeNode(callTarget, 0));
invoke.setStateAfter(graph.start().stateAfter());
graph.addAfterFixed(graph.start(), invoke);
StructuredGraph inlineeGraph = providers.getReplacements().getSnippet(initCounter.getMethod(), null);
InliningUtil.inline(invoke, inlineeGraph, false, null, null);
List rets = graph.getNodes(ReturnNode.TYPE).snapshot();
for (ReturnNode ret : rets) {
returnType = checkCounter.getMethod().getSignature().getReturnType(checkCounter.getMethod().getDeclaringClass());
String msg = "unbalanced monitors in " + graph.method().format("%H.%n(%p)") + ", count = %d";
ConstantNode errMsg = ConstantNode.forConstant(tool.getConstantReflection().forString(msg), providers.getMetaAccess(), graph);
returnStamp = StampFactory.forDeclaredType(graph.getAssumptions(), returnType, false);
callTarget = graph.add(new MethodCallTargetNode(InvokeKind.Static, checkCounter.getMethod(), new ValueNode[]{errMsg}, returnStamp, null));
invoke = graph.add(new InvokeNode(callTarget, 0));
Bytecode code = new ResolvedJavaMethodBytecode(graph.method());
FrameState stateAfter = new FrameState(null, code, BytecodeFrame.AFTER_BCI, new ValueNode[0], new ValueNode[0], 0, new ValueNode[0], null, false, false);
invoke.setStateAfter(graph.add(stateAfter));
graph.addBeforeFixed(ret, invoke);
Arguments args = new Arguments(checkCounter, graph.getGuardsStage(), tool.getLoweringStage());
args.addConst("errMsg", msg);
inlineeGraph = template(args).copySpecializedGraph();
InliningUtil.inline(invoke, inlineeGraph, false, null, null);
}
}
}
}
}
public static final ForeignCallDescriptor MONITORENTER = new ForeignCallDescriptor("monitorenter", void.class, Object.class, Word.class);
public static final ForeignCallDescriptor MONITOREXIT = new ForeignCallDescriptor("monitorexit", void.class, Object.class, Word.class);
@NodeIntrinsic(ForeignCallNode.class)
private static native void monitorenterStubC(@ConstantNodeParameter ForeignCallDescriptor descriptor, Object object, Word lock);
@NodeIntrinsic(ForeignCallNode.class)
public static native void monitorexitStubC(@ConstantNodeParameter ForeignCallDescriptor descriptor, Object object, Word lock);
/**
* Counters for the various paths for acquiring a lock. The counters whose names start with
* {@code "lock"} are mutually exclusive. The other counters are for paths that may be shared.
*/
public static final SnippetCounter.Group lockCounters = SnippetCounters.getValue() ? new SnippetCounter.Group("MonitorEnters") : null;
public static final SnippetCounter lockBiasExisting = new SnippetCounter(lockCounters, "lock{bias:existing}", "bias-locked previously biased object");
public static final SnippetCounter lockBiasAcquired = new SnippetCounter(lockCounters, "lock{bias:acquired}", "bias-locked newly biased object");
public static final SnippetCounter lockBiasTransfer = new SnippetCounter(lockCounters, "lock{bias:transfer}", "bias-locked, biased transferred");
public static final SnippetCounter lockCas = new SnippetCounter(lockCounters, "lock{cas}", "cas-locked an object");
public static final SnippetCounter lockCasRecursive = new SnippetCounter(lockCounters, "lock{cas:recursive}", "cas-locked, recursive");
public static final SnippetCounter lockStubEpochExpired = new SnippetCounter(lockCounters, "lock{stub:epoch-expired}", "stub-locked, epoch expired");
public static final SnippetCounter lockStubRevoke = new SnippetCounter(lockCounters, "lock{stub:revoke}", "stub-locked, biased revoked");
public static final SnippetCounter lockStubFailedCas = new SnippetCounter(lockCounters, "lock{stub:failed-cas}", "stub-locked, failed cas");
public static final SnippetCounter unbiasable = new SnippetCounter(lockCounters, "unbiasable", "object with unbiasable type");
public static final SnippetCounter revokeBias = new SnippetCounter(lockCounters, "revokeBias", "object had bias revoked");
/**
* Counters for the various paths for releasing a lock. The counters whose names start with
* {@code "unlock"} are mutually exclusive. The other counters are for paths that may be shared.
*/
public static final SnippetCounter.Group unlockCounters = SnippetCounters.getValue() ? new SnippetCounter.Group("MonitorExits") : null;
public static final SnippetCounter unlockBias = new SnippetCounter(unlockCounters, "unlock{bias}", "bias-unlocked an object");
public static final SnippetCounter unlockCas = new SnippetCounter(unlockCounters, "unlock{cas}", "cas-unlocked an object");
public static final SnippetCounter unlockCasRecursive = new SnippetCounter(unlockCounters, "unlock{cas:recursive}", "cas-unlocked an object, recursive");
public static final SnippetCounter unlockStub = new SnippetCounter(unlockCounters, "unlock{stub}", "stub-unlocked an object");
}