1 /*
2 * Copyright (c) 2011, 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.virtual.phases.ea;
24
25 import static org.graalvm.compiler.core.common.GraalOptions.ReadEliminationMaxLoopVisits;
26 import static org.graalvm.compiler.nodes.NamedLocationIdentity.ARRAY_LENGTH_LOCATION;
27
28 import java.util.EnumMap;
29 import java.util.Iterator;
30 import java.util.List;
31
32 import org.graalvm.compiler.core.common.cfg.Loop;
33 import org.graalvm.compiler.core.common.spi.ConstantFieldProvider;
34 import org.graalvm.compiler.core.common.type.Stamp;
35 import org.graalvm.compiler.graph.Node;
36 import org.graalvm.compiler.nodes.AbstractBeginNode;
37 import org.graalvm.compiler.nodes.FieldLocationIdentity;
38 import org.graalvm.compiler.nodes.FixedNode;
39 import org.graalvm.compiler.nodes.FixedWithNextNode;
40 import org.graalvm.compiler.nodes.LoopBeginNode;
41 import org.graalvm.compiler.nodes.LoopExitNode;
42 import org.graalvm.compiler.nodes.NamedLocationIdentity;
43 import org.graalvm.compiler.nodes.PhiNode;
44 import org.graalvm.compiler.nodes.ProxyNode;
45 import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;
46 import org.graalvm.compiler.nodes.ValueNode;
47 import org.graalvm.compiler.nodes.ValueProxyNode;
48 import org.graalvm.compiler.nodes.cfg.Block;
49 import org.graalvm.compiler.nodes.extended.RawLoadNode;
50 import org.graalvm.compiler.nodes.extended.RawStoreNode;
51 import org.graalvm.compiler.nodes.extended.UnboxNode;
52 import org.graalvm.compiler.nodes.java.ArrayLengthNode;
53 import org.graalvm.compiler.nodes.java.LoadFieldNode;
54 import org.graalvm.compiler.nodes.java.LoadIndexedNode;
55 import org.graalvm.compiler.nodes.java.StoreFieldNode;
56 import org.graalvm.compiler.nodes.java.StoreIndexedNode;
57 import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;
58 import org.graalvm.compiler.nodes.spi.LoweringProvider;
59 import org.graalvm.compiler.nodes.type.StampTool;
60 import org.graalvm.compiler.nodes.util.GraphUtil;
61 import org.graalvm.compiler.nodes.virtual.VirtualArrayNode;
62 import org.graalvm.compiler.options.OptionValues;
63 import org.graalvm.compiler.virtual.phases.ea.PEReadEliminationBlockState.ReadCacheEntry;
64 import org.graalvm.util.EconomicMap;
65 import org.graalvm.util.EconomicSet;
66 import org.graalvm.util.Equivalence;
67 import org.graalvm.util.MapCursor;
68 import org.graalvm.util.Pair;
69 import org.graalvm.word.LocationIdentity;
70
71 import jdk.vm.ci.meta.ConstantReflectionProvider;
72 import jdk.vm.ci.meta.JavaConstant;
73 import jdk.vm.ci.meta.JavaKind;
74 import jdk.vm.ci.meta.MetaAccessProvider;
75 import jdk.vm.ci.meta.ResolvedJavaType;
76
77 public final class PEReadEliminationClosure extends PartialEscapeClosure<PEReadEliminationBlockState> {
78
79 private static final EnumMap<JavaKind, LocationIdentity> UNBOX_LOCATIONS;
80
81 static {
82 UNBOX_LOCATIONS = new EnumMap<>(JavaKind.class);
83 for (JavaKind kind : JavaKind.values()) {
84 UNBOX_LOCATIONS.put(kind, NamedLocationIdentity.immutable("PEA unbox " + kind.getJavaName()));
85 }
86 }
87
88 public PEReadEliminationClosure(ScheduleResult schedule, MetaAccessProvider metaAccess, ConstantReflectionProvider constantReflection, ConstantFieldProvider constantFieldProvider,
89 LoweringProvider loweringProvider) {
90 super(schedule, metaAccess, constantReflection, constantFieldProvider, loweringProvider);
91 }
92
93 @Override
94 protected PEReadEliminationBlockState getInitialState() {
95 return new PEReadEliminationBlockState(tool.getOptions(), tool.getDebug());
96 }
97
98 @Override
99 protected boolean processNode(Node node, PEReadEliminationBlockState state, GraphEffectList effects, FixedWithNextNode lastFixedNode) {
100 if (super.processNode(node, state, effects, lastFixedNode)) {
101 return true;
102 }
103
104 if (node instanceof LoadFieldNode) {
105 return processLoadField((LoadFieldNode) node, state, effects);
106 } else if (node instanceof StoreFieldNode) {
107 return processStoreField((StoreFieldNode) node, state, effects);
108 } else if (node instanceof LoadIndexedNode) {
109 return processLoadIndexed((LoadIndexedNode) node, state, effects);
110 } else if (node instanceof StoreIndexedNode) {
111 return processStoreIndexed((StoreIndexedNode) node, state, effects);
112 } else if (node instanceof ArrayLengthNode) {
113 return processArrayLength((ArrayLengthNode) node, state, effects);
114 } else if (node instanceof UnboxNode) {
115 return processUnbox((UnboxNode) node, state, effects);
116 } else if (node instanceof RawLoadNode) {
117 return processUnsafeLoad((RawLoadNode) node, state, effects);
118 } else if (node instanceof RawStoreNode) {
119 return processUnsafeStore((RawStoreNode) node, state, effects);
120 } else if (node instanceof MemoryCheckpoint.Single) {
121 COUNTER_MEMORYCHECKPOINT.increment(node.getDebug());
122 LocationIdentity identity = ((MemoryCheckpoint.Single) node).getLocationIdentity();
123 processIdentity(state, identity);
124 } else if (node instanceof MemoryCheckpoint.Multi) {
125 COUNTER_MEMORYCHECKPOINT.increment(node.getDebug());
126 for (LocationIdentity identity : ((MemoryCheckpoint.Multi) node).getLocationIdentities()) {
127 processIdentity(state, identity);
128 }
129 }
130
131 return false;
132 }
133
134 private boolean processStore(FixedNode store, ValueNode object, LocationIdentity identity, int index, JavaKind kind, ValueNode value, PEReadEliminationBlockState state, GraphEffectList effects) {
135 ValueNode unproxiedObject = GraphUtil.unproxify(object);
136 ValueNode cachedValue = state.getReadCache(object, identity, index, kind, this);
137
138 ValueNode finalValue = getScalarAlias(value);
139 boolean result = false;
140 if (GraphUtil.unproxify(finalValue) == GraphUtil.unproxify(cachedValue)) {
141 effects.deleteNode(store);
142 result = true;
143 }
144 state.killReadCache(identity, index);
145 state.addReadCache(unproxiedObject, identity, index, kind, finalValue, this);
146 return result;
147 }
148
149 private boolean processLoad(FixedNode load, ValueNode object, LocationIdentity identity, int index, JavaKind kind, PEReadEliminationBlockState state, GraphEffectList effects) {
150 ValueNode unproxiedObject = GraphUtil.unproxify(object);
151 ValueNode cachedValue = state.getReadCache(unproxiedObject, identity, index, kind, this);
152 if (cachedValue != null) {
153 Stamp loadStamp = load.stamp();
154 Stamp cachedValueStamp = cachedValue.stamp();
155 if (!loadStamp.isCompatible(cachedValueStamp)) {
156 /*
157 * Can either be the first field of a two slot write to a one slot field which would
158 * have a non compatible stamp or the second load which will see Illegal.
159 */
160 assert load.stamp().getStackKind() == JavaKind.Int && (cachedValue.stamp().getStackKind() == JavaKind.Long || cachedValue.getStackKind() == JavaKind.Double ||
161 cachedValue.getStackKind() == JavaKind.Illegal) : "Can only allow different stack kind two slot marker writes on one slot fields.";
162 return false;
163 } else {
164 // perform the read elimination
165 effects.replaceAtUsages(load, cachedValue, load);
166 addScalarAlias(load, cachedValue);
167 return true;
168 }
169 } else {
170 state.addReadCache(unproxiedObject, identity, index, kind, load, this);
171 return false;
172 }
173 }
174
175 private boolean processUnsafeLoad(RawLoadNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
176 if (load.offset().isConstant()) {
177 ResolvedJavaType type = StampTool.typeOrNull(load.object());
178 if (type != null && type.isArray()) {
179 long offset = load.offset().asJavaConstant().asLong();
180 int index = VirtualArrayNode.entryIndexForOffset(offset, load.accessKind(), type.getComponentType(), Integer.MAX_VALUE);
181 ValueNode object = GraphUtil.unproxify(load.object());
182 LocationIdentity location = NamedLocationIdentity.getArrayLocation(type.getComponentType().getJavaKind());
183 ValueNode cachedValue = state.getReadCache(object, location, index, load.accessKind(), this);
184 if (cachedValue != null && load.stamp().isCompatible(cachedValue.stamp())) {
185 effects.replaceAtUsages(load, cachedValue, load);
186 addScalarAlias(load, cachedValue);
187 return true;
188 } else {
189 state.addReadCache(object, location, index, load.accessKind(), load, this);
190 }
191 }
192 }
193 return false;
194 }
195
196 private boolean processUnsafeStore(RawStoreNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
197 ResolvedJavaType type = StampTool.typeOrNull(store.object());
198 if (type != null && type.isArray()) {
199 LocationIdentity location = NamedLocationIdentity.getArrayLocation(type.getComponentType().getJavaKind());
200 if (store.offset().isConstant()) {
201 long offset = store.offset().asJavaConstant().asLong();
202 int index = VirtualArrayNode.entryIndexForOffset(offset, store.accessKind(), type.getComponentType(), Integer.MAX_VALUE);
203 return processStore(store, store.object(), location, index, store.accessKind(), store.value(), state, effects);
204 } else {
205 processIdentity(state, location);
206 }
207 } else {
208 state.killReadCache();
209 }
210 return false;
211 }
212
213 private boolean processArrayLength(ArrayLengthNode length, PEReadEliminationBlockState state, GraphEffectList effects) {
214 return processLoad(length, length.array(), ARRAY_LENGTH_LOCATION, -1, JavaKind.Int, state, effects);
215 }
216
217 private boolean processStoreField(StoreFieldNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
218 if (store.isVolatile()) {
219 state.killReadCache();
220 return false;
221 }
222 return processStore(store, store.object(), new FieldLocationIdentity(store.field()), -1, store.field().getJavaKind(), store.value(), state, effects);
223 }
224
225 private boolean processLoadField(LoadFieldNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
226 if (load.isVolatile()) {
227 state.killReadCache();
228 return false;
229 }
230 return processLoad(load, load.object(), new FieldLocationIdentity(load.field()), -1, load.field().getJavaKind(), state, effects);
231 }
232
233 private boolean processStoreIndexed(StoreIndexedNode store, PEReadEliminationBlockState state, GraphEffectList effects) {
234 LocationIdentity arrayLocation = NamedLocationIdentity.getArrayLocation(store.elementKind());
235 if (store.index().isConstant()) {
236 int index = ((JavaConstant) store.index().asConstant()).asInt();
237 return processStore(store, store.array(), arrayLocation, index, store.elementKind(), store.value(), state, effects);
238 } else {
239 state.killReadCache(arrayLocation, -1);
240 }
241 return false;
242 }
243
244 private boolean processLoadIndexed(LoadIndexedNode load, PEReadEliminationBlockState state, GraphEffectList effects) {
245 if (load.index().isConstant()) {
246 int index = ((JavaConstant) load.index().asConstant()).asInt();
247 LocationIdentity arrayLocation = NamedLocationIdentity.getArrayLocation(load.elementKind());
248 return processLoad(load, load.array(), arrayLocation, index, load.elementKind(), state, effects);
249 }
250 return false;
251 }
252
253 private boolean processUnbox(UnboxNode unbox, PEReadEliminationBlockState state, GraphEffectList effects) {
254 return processLoad(unbox, unbox.getValue(), UNBOX_LOCATIONS.get(unbox.getBoxingKind()), -1, unbox.getBoxingKind(), state, effects);
255 }
256
257 private static void processIdentity(PEReadEliminationBlockState state, LocationIdentity identity) {
258 if (identity.isAny()) {
259 state.killReadCache();
260 } else {
261 state.killReadCache(identity, -1);
262 }
263 }
264
265 @SuppressWarnings("unchecked")
266 @Override
267 protected void processInitialLoopState(Loop<Block> loop, PEReadEliminationBlockState initialState) {
268 super.processInitialLoopState(loop, initialState);
269
270 if (!initialState.getReadCache().isEmpty()) {
271 EconomicMap<ValueNode, Pair<ValueNode, Object>> firstValueSet = null;
272 for (PhiNode phi : ((LoopBeginNode) loop.getHeader().getBeginNode()).phis()) {
273 ValueNode firstValue = phi.valueAt(0);
274 if (firstValue != null && phi.getStackKind().isObject()) {
275 ValueNode unproxified = GraphUtil.unproxify(firstValue);
276 if (firstValueSet == null) {
277 firstValueSet = EconomicMap.create(Equivalence.IDENTITY_WITH_SYSTEM_HASHCODE);
278 }
279 Pair<ValueNode, Object> pair = Pair.create(unproxified, firstValueSet.get(unproxified));
280 firstValueSet.put(unproxified, pair);
281 }
282 }
283
284 if (firstValueSet != null) {
285 ReadCacheEntry[] entries = new ReadCacheEntry[initialState.getReadCache().size()];
286 int z = 0;
287 for (ReadCacheEntry entry : initialState.getReadCache().getKeys()) {
288 entries[z++] = entry;
289 }
290
291 for (ReadCacheEntry entry : entries) {
292 ValueNode object = entry.object;
293 if (object != null) {
294 Pair<ValueNode, Object> pair = firstValueSet.get(object);
295 while (pair != null) {
296 initialState.addReadCache(pair.getLeft(), entry.identity, entry.index, entry.kind, initialState.getReadCache().get(entry), this);
297 pair = (Pair<ValueNode, Object>) pair.getRight();
298 }
299 }
300 }
301 }
302 }
303 }
304
305 @Override
306 protected void processLoopExit(LoopExitNode exitNode, PEReadEliminationBlockState initialState, PEReadEliminationBlockState exitState, GraphEffectList effects) {
307 super.processLoopExit(exitNode, initialState, exitState, effects);
308
309 if (exitNode.graph().hasValueProxies()) {
310 MapCursor<ReadCacheEntry, ValueNode> entry = exitState.getReadCache().getEntries();
311 while (entry.advance()) {
312 if (initialState.getReadCache().get(entry.getKey()) != entry.getValue()) {
313 ValueNode value = exitState.getReadCache(entry.getKey().object, entry.getKey().identity, entry.getKey().index, entry.getKey().kind, this);
314 assert value != null : "Got null from read cache, entry's value:" + entry.getValue();
315 if (!(value instanceof ProxyNode) || ((ProxyNode) value).proxyPoint() != exitNode) {
316 ProxyNode proxy = new ValueProxyNode(value, exitNode);
317 effects.addFloatingNode(proxy, "readCacheProxy");
318 exitState.getReadCache().put(entry.getKey(), proxy);
319 }
320 }
321 }
322 }
323 }
324
325 @Override
326 protected PEReadEliminationBlockState cloneState(PEReadEliminationBlockState other) {
327 return new PEReadEliminationBlockState(other);
328 }
329
330 @Override
331 protected MergeProcessor createMergeProcessor(Block merge) {
332 return new ReadEliminationMergeProcessor(merge);
333 }
334
335 private class ReadEliminationMergeProcessor extends MergeProcessor {
336
337 ReadEliminationMergeProcessor(Block mergeBlock) {
338 super(mergeBlock);
339 }
340
341 @Override
342 protected void merge(List<PEReadEliminationBlockState> states) {
343 super.merge(states);
344
345 mergeReadCache(states);
346 }
347
348 private void mergeReadCache(List<PEReadEliminationBlockState> states) {
349 MapCursor<ReadCacheEntry, ValueNode> cursor = states.get(0).readCache.getEntries();
350 while (cursor.advance()) {
351 ReadCacheEntry key = cursor.getKey();
352 ValueNode value = cursor.getValue();
353 boolean phi = false;
354 for (int i = 1; i < states.size(); i++) {
355 ValueNode otherValue = states.get(i).readCache.get(key);
356 // e.g. unsafe loads / stores with different access kinds have different stamps
357 // although location, object and offset are the same, in this case we cannot
358 // create a phi nor can we set a common value
359 if (otherValue == null || !value.stamp().isCompatible(otherValue.stamp())) {
360 value = null;
361 phi = false;
362 break;
363 }
364 if (!phi && otherValue != value) {
365 phi = true;
366 }
367 }
368 if (phi) {
369 PhiNode phiNode = getPhi(key, value.stamp().unrestricted());
370 mergeEffects.addFloatingNode(phiNode, "mergeReadCache");
371 for (int i = 0; i < states.size(); i++) {
372 ValueNode v = states.get(i).getReadCache(key.object, key.identity, key.index, key.kind, PEReadEliminationClosure.this);
373 assert phiNode.stamp().isCompatible(v.stamp()) : "Cannot create read elimination phi for inputs with incompatible stamps.";
374 setPhiInput(phiNode, i, v);
375 }
376 newState.readCache.put(key, phiNode);
377 } else if (value != null) {
378 newState.readCache.put(key, value);
379 }
380 }
381 /*
382 * For object phis, see if there are known reads on all predecessors, for which we could
383 * create new phis.
384 */
385 for (PhiNode phi : getPhis()) {
386 if (phi.getStackKind() == JavaKind.Object) {
387 for (ReadCacheEntry entry : states.get(0).readCache.getKeys()) {
388 if (entry.object == getPhiValueAt(phi, 0)) {
389 mergeReadCachePhi(phi, entry.identity, entry.index, entry.kind, states);
390 }
391 }
392 }
393 }
394 }
395
396 private void mergeReadCachePhi(PhiNode phi, LocationIdentity identity, int index, JavaKind kind, List<PEReadEliminationBlockState> states) {
397 ValueNode[] values = new ValueNode[states.size()];
398 values[0] = states.get(0).getReadCache(getPhiValueAt(phi, 0), identity, index, kind, PEReadEliminationClosure.this);
399 if (values[0] != null) {
400 for (int i = 1; i < states.size(); i++) {
401 ValueNode value = states.get(i).getReadCache(getPhiValueAt(phi, i), identity, index, kind, PEReadEliminationClosure.this);
402 // e.g. unsafe loads / stores with same identity and different access kinds see
403 // mergeReadCache(states)
404 if (value == null || !values[i - 1].stamp().isCompatible(value.stamp())) {
405 return;
406 }
407 values[i] = value;
408 }
409
410 PhiNode phiNode = getPhi(new ReadCacheEntry(identity, phi, index, kind), values[0].stamp().unrestricted());
411 mergeEffects.addFloatingNode(phiNode, "mergeReadCachePhi");
412 for (int i = 0; i < values.length; i++) {
413 setPhiInput(phiNode, i, values[i]);
414 }
415 newState.readCache.put(new ReadCacheEntry(identity, phi, index, kind), phiNode);
416 }
417 }
418 }
419
420 @Override
421 protected void processKilledLoopLocations(Loop<Block> loop, PEReadEliminationBlockState initialState, PEReadEliminationBlockState mergedStates) {
422 assert initialState != null;
423 assert mergedStates != null;
424 if (initialState.readCache.size() > 0) {
425 LoopKillCache loopKilledLocations = loopLocationKillCache.get(loop);
426 // we have fully processed this loop the first time, remember to cache it the next time
427 // it is visited
428 if (loopKilledLocations == null) {
429 loopKilledLocations = new LoopKillCache(1/* 1.visit */);
430 loopLocationKillCache.put(loop, loopKilledLocations);
431 } else {
432 AbstractBeginNode beginNode = loop.getHeader().getBeginNode();
433 OptionValues options = beginNode.getOptions();
434 if (loopKilledLocations.visits() > ReadEliminationMaxLoopVisits.getValue(options)) {
435 // we have processed the loop too many times, kill all locations so the inner
436 // loop will never be processed more than once again on visit
437 loopKilledLocations.setKillsAll();
438 } else {
439 // we have fully processed this loop >1 times, update the killed locations
440 EconomicSet<LocationIdentity> forwardEndLiveLocations = EconomicSet.create(Equivalence.DEFAULT);
441 for (ReadCacheEntry entry : initialState.readCache.getKeys()) {
442 forwardEndLiveLocations.add(entry.identity);
443 }
444 for (ReadCacheEntry entry : mergedStates.readCache.getKeys()) {
445 forwardEndLiveLocations.remove(entry.identity);
446 }
447 // every location that is alive before the loop but not after is killed by the
448 // loop
449 for (LocationIdentity location : forwardEndLiveLocations) {
450 loopKilledLocations.rememberLoopKilledLocation(location);
451 }
452 if (debug.isLogEnabled() && loopKilledLocations != null) {
453 debug.log("[Early Read Elimination] Setting loop killed locations of loop at node %s with %s",
454 beginNode, forwardEndLiveLocations);
455 }
456 }
457 // remember the loop visit
458 loopKilledLocations.visited();
459 }
460 }
461 }
462
463 @Override
464 protected PEReadEliminationBlockState stripKilledLoopLocations(Loop<Block> loop, PEReadEliminationBlockState originalInitialState) {
465 PEReadEliminationBlockState initialState = super.stripKilledLoopLocations(loop, originalInitialState);
466 LoopKillCache loopKilledLocations = loopLocationKillCache.get(loop);
467 if (loopKilledLocations != null && loopKilledLocations.loopKillsLocations()) {
468 Iterator<ReadCacheEntry> it = initialState.readCache.getKeys().iterator();
469 while (it.hasNext()) {
470 ReadCacheEntry entry = it.next();
471 if (loopKilledLocations.containsLocation(entry.identity)) {
472 it.remove();
473 }
474 }
475 }
476 return initialState;
477 }
478
479 }