1 /*
2 * Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24
25 package org.graalvm.compiler.nodes;
26
27 import static org.graalvm.compiler.debug.GraalError.shouldNotReachHere;
28 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_IGNORED;
29 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_IGNORED;
30
31 import java.util.ArrayDeque;
32 import java.util.ArrayList;
33 import java.util.Arrays;
34 import java.util.BitSet;
35 import java.util.Deque;
36 import java.util.Iterator;
37 import java.util.List;
38 import java.util.Map;
39 import java.util.SortedMap;
40 import java.util.TreeMap;
41
42 import jdk.internal.vm.compiler.collections.EconomicMap;
43 import jdk.internal.vm.compiler.collections.EconomicSet;
44 import jdk.internal.vm.compiler.collections.Equivalence;
45 import org.graalvm.compiler.core.common.Fields;
46 import org.graalvm.compiler.core.common.PermanentBailoutException;
47 import org.graalvm.compiler.core.common.util.TypeReader;
48 import org.graalvm.compiler.core.common.util.UnsafeArrayTypeReader;
49 import org.graalvm.compiler.debug.DebugContext;
50 import org.graalvm.compiler.debug.GraalError;
51 import org.graalvm.compiler.graph.Edges;
52 import org.graalvm.compiler.graph.Graph;
53 import org.graalvm.compiler.graph.Node;
54 import org.graalvm.compiler.graph.NodeBitMap;
55 import org.graalvm.compiler.graph.NodeClass;
56 import org.graalvm.compiler.graph.NodeInputList;
57 import org.graalvm.compiler.graph.NodeList;
58 import org.graalvm.compiler.graph.NodeSourcePosition;
59 import org.graalvm.compiler.graph.NodeSuccessorList;
60 import org.graalvm.compiler.graph.spi.Canonicalizable;
61 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
62 import org.graalvm.compiler.nodeinfo.InputType;
63 import org.graalvm.compiler.nodeinfo.NodeInfo;
64 import org.graalvm.compiler.nodes.GraphDecoder.MethodScope;
65 import org.graalvm.compiler.nodes.GraphDecoder.ProxyPlaceholder;
66 import org.graalvm.compiler.nodes.calc.FloatingNode;
67 import org.graalvm.compiler.nodes.extended.IntegerSwitchNode;
68 import org.graalvm.compiler.nodes.graphbuilderconf.LoopExplosionPlugin.LoopExplosionKind;
69 import org.graalvm.compiler.options.OptionValues;
70
71 import jdk.vm.ci.code.Architecture;
72 import jdk.vm.ci.meta.DeoptimizationAction;
73 import jdk.vm.ci.meta.DeoptimizationReason;
74 import jdk.vm.ci.meta.JavaConstant;
75 import jdk.vm.ci.meta.JavaKind;
76 import jdk.vm.ci.meta.PrimitiveConstant;
77 import jdk.vm.ci.meta.ResolvedJavaType;
78
79 /**
80 * Decoder for {@link EncodedGraph encoded graphs} produced by {@link GraphEncoder}. Support for
81 * loop explosion during decoding is built into this class, because it requires many interactions
82 * with the decoding process. Subclasses can provide canonicalization and simplification of nodes
83 * during decoding, as well as method inlining during decoding.
84 */
85 public class GraphDecoder {
86
87 /** Decoding state maintained for each encoded graph. */
88 protected class MethodScope {
89 /** The loop that contains the call. Only non-null during method inlining. */
90 public final LoopScope callerLoopScope;
91 /**
92 * Mark for nodes that were present before the decoding of this method started. Note that
93 * nodes that were decoded after the mark can still be part of an outer method, since
94 * floating nodes of outer methods are decoded lazily.
95 */
96 public final Graph.Mark methodStartMark;
97 /** The encode graph that is decoded. */
98 public final EncodedGraph encodedGraph;
99 /** The highest node order id that a fixed node has in the EncodedGraph. */
100 public final int maxFixedNodeOrderId;
101 /** Access to the encoded graph. */
102 public final TypeReader reader;
103 /** The kind of loop explosion to be performed during decoding. */
104 public final LoopExplosionKind loopExplosion;
105
106 /** All return nodes encountered during decoding. */
107 public final List<ControlSinkNode> returnAndUnwindNodes;
108
109 /** All merges created during loop explosion. */
110 public final EconomicSet<Node> loopExplosionMerges;
111
112 /**
113 * The start of explosion, and the merge point for when irreducible loops are detected. Only
114 * used when {@link MethodScope#loopExplosion} is {@link LoopExplosionKind#MERGE_EXPLODE}.
115 */
116 public MergeNode loopExplosionHead;
117
118 protected MethodScope(LoopScope callerLoopScope, StructuredGraph graph, EncodedGraph encodedGraph, LoopExplosionKind loopExplosion) {
119 this.callerLoopScope = callerLoopScope;
120 this.methodStartMark = graph.getMark();
121 this.encodedGraph = encodedGraph;
122 this.loopExplosion = loopExplosion;
123 this.returnAndUnwindNodes = new ArrayList<>(2);
124
125 if (encodedGraph != null) {
126 reader = UnsafeArrayTypeReader.create(encodedGraph.getEncoding(), encodedGraph.getStartOffset(), architecture.supportsUnalignedMemoryAccess());
127 maxFixedNodeOrderId = reader.getUVInt();
128 if (encodedGraph.nodeStartOffsets == null) {
129 int nodeCount = reader.getUVInt();
130 int[] nodeStartOffsets = new int[nodeCount];
131 for (int i = 0; i < nodeCount; i++) {
132 nodeStartOffsets[i] = encodedGraph.getStartOffset() - reader.getUVInt();
133 }
134 encodedGraph.nodeStartOffsets = nodeStartOffsets;
135 }
136 } else {
137 reader = null;
138 maxFixedNodeOrderId = 0;
139 }
140
141 if (loopExplosion != LoopExplosionKind.NONE) {
142 loopExplosionMerges = EconomicSet.create(Equivalence.IDENTITY);
143 } else {
144 loopExplosionMerges = null;
145 }
146 }
147
148 public boolean isInlinedMethod() {
149 return false;
150 }
151
152 public NodeSourcePosition getCallerBytecodePosition() {
153 return getCallerBytecodePosition(null);
154 }
155
156 public NodeSourcePosition getCallerBytecodePosition(NodeSourcePosition position) {
157 return position;
158 }
159
160 }
161
162 /** Decoding state maintained for each loop in the encoded graph. */
163 protected static class LoopScope {
164 public final MethodScope methodScope;
165 public final LoopScope outer;
166 public final int loopDepth;
167 public final int loopIteration;
168 /**
169 * Upcoming loop iterations during loop explosions that have not been processed yet. Only
170 * used when {@link MethodScope#loopExplosion} is not {@link LoopExplosionKind#NONE}.
171 */
172 public Deque<LoopScope> nextIterations;
173 /**
174 * Information about already processed loop iterations for state merging during loop
175 * explosion. Only used when {@link MethodScope#loopExplosion} is
176 * {@link LoopExplosionKind#MERGE_EXPLODE}.
177 */
178 public final EconomicMap<LoopExplosionState, LoopExplosionState> iterationStates;
179 public final int loopBeginOrderId;
180 /**
181 * The worklist of fixed nodes to process. Since we already the correct processing order
182 * from the orderId, we just set the orderId bit in the bitset when a node is ready for
183 * processing. The lowest set bit is the next node to process.
184 */
185 public final BitSet nodesToProcess;
186 /** Nodes that have been created, indexed by the orderId. */
187 public final Node[] createdNodes;
188 /**
189 * Nodes that have been created in outer loop scopes and existed before starting to process
190 * this loop, indexed by the orderId. Only used when {@link MethodScope#loopExplosion} is
191 * not {@link LoopExplosionKind#NONE}.
192 */
193 public final Node[] initialCreatedNodes;
194
195 protected LoopScope(MethodScope methodScope) {
196 this.methodScope = methodScope;
197 this.outer = null;
198 this.nextIterations = methodScope.loopExplosion == LoopExplosionKind.FULL_EXPLODE_UNTIL_RETURN ? new ArrayDeque<>(2) : null;
199 this.loopDepth = 0;
200 this.loopIteration = 0;
201 this.iterationStates = null;
202 this.loopBeginOrderId = -1;
203
204 int nodeCount = methodScope.encodedGraph.nodeStartOffsets.length;
205 this.nodesToProcess = new BitSet(methodScope.maxFixedNodeOrderId);
206 this.createdNodes = new Node[nodeCount];
207 this.initialCreatedNodes = null;
208 }
209
210 protected LoopScope(MethodScope methodScope, LoopScope outer, int loopDepth, int loopIteration, int loopBeginOrderId, Node[] initialCreatedNodes, Node[] createdNodes,
211 Deque<LoopScope> nextIterations, EconomicMap<LoopExplosionState, LoopExplosionState> iterationStates) {
212 this.methodScope = methodScope;
213 this.outer = outer;
214 this.loopDepth = loopDepth;
215 this.loopIteration = loopIteration;
216 this.nextIterations = nextIterations;
217 this.iterationStates = iterationStates;
218 this.loopBeginOrderId = loopBeginOrderId;
219 this.nodesToProcess = new BitSet(methodScope.maxFixedNodeOrderId);
220 this.initialCreatedNodes = initialCreatedNodes;
221 this.createdNodes = createdNodes;
222 }
223
224 @Override
225 public String toString() {
226 return loopDepth + "," + loopIteration + (loopBeginOrderId == -1 ? "" : "#" + loopBeginOrderId);
227 }
228 }
229
230 protected static class LoopExplosionState {
231 public final FrameState state;
232 public final MergeNode merge;
233 public final int hashCode;
234
235 protected LoopExplosionState(FrameState state, MergeNode merge) {
236 this.state = state;
237 this.merge = merge;
238
239 int h = 0;
240 for (ValueNode value : state.values()) {
241 if (value == null) {
242 h = h * 31 + 1234;
243 } else {
244 h = h * 31 + ProxyPlaceholder.unwrap(value).hashCode();
245 }
246 }
247 this.hashCode = h;
248 }
249
250 @Override
251 public boolean equals(Object obj) {
252 if (!(obj instanceof LoopExplosionState)) {
253 return false;
254 }
255
256 FrameState otherState = ((LoopExplosionState) obj).state;
257 FrameState thisState = state;
258 assert thisState.outerFrameState() == otherState.outerFrameState();
259
260 Iterator<ValueNode> thisIter = thisState.values().iterator();
261 Iterator<ValueNode> otherIter = otherState.values().iterator();
262 while (thisIter.hasNext() && otherIter.hasNext()) {
263 ValueNode thisValue = ProxyPlaceholder.unwrap(thisIter.next());
264 ValueNode otherValue = ProxyPlaceholder.unwrap(otherIter.next());
265 if (thisValue != otherValue) {
266 return false;
267 }
268 }
269 return thisIter.hasNext() == otherIter.hasNext();
270 }
271
272 @Override
273 public int hashCode() {
274 return hashCode;
275 }
276 }
277
278 /**
279 * Additional information encoded for {@link Invoke} nodes to allow method inlining without
280 * decoding the frame state and successors beforehand.
281 */
282 protected static class InvokeData {
283 public final Invoke invoke;
284 public final ResolvedJavaType contextType;
285 public final int invokeOrderId;
286 public final int callTargetOrderId;
287 public final int stateAfterOrderId;
288 public final int nextOrderId;
289
290 public final int nextNextOrderId;
291 public final int exceptionOrderId;
292 public final int exceptionStateOrderId;
293 public final int exceptionNextOrderId;
294 public JavaConstant constantReceiver;
295
296 protected InvokeData(Invoke invoke, ResolvedJavaType contextType, int invokeOrderId, int callTargetOrderId, int stateAfterOrderId, int nextOrderId, int nextNextOrderId, int exceptionOrderId,
297 int exceptionStateOrderId, int exceptionNextOrderId) {
298 this.invoke = invoke;
299 this.contextType = contextType;
300 this.invokeOrderId = invokeOrderId;
301 this.callTargetOrderId = callTargetOrderId;
302 this.stateAfterOrderId = stateAfterOrderId;
303 this.nextOrderId = nextOrderId;
304 this.nextNextOrderId = nextNextOrderId;
305 this.exceptionOrderId = exceptionOrderId;
306 this.exceptionStateOrderId = exceptionStateOrderId;
307 this.exceptionNextOrderId = exceptionNextOrderId;
308 }
309 }
310
311 /**
312 * A node that is created during {@link LoopExplosionKind#MERGE_EXPLODE loop explosion} that can
313 * later be replaced by a ProxyNode if {@link LoopDetector loop detection} finds out that the
314 * value is defined in the loop, but used outside the loop.
315 */
316 @NodeInfo(cycles = CYCLES_IGNORED, size = SIZE_IGNORED)
317 protected static final class ProxyPlaceholder extends FloatingNode implements Canonicalizable {
318 public static final NodeClass<ProxyPlaceholder> TYPE = NodeClass.create(ProxyPlaceholder.class);
319
320 @Input ValueNode value;
321 @Input(InputType.Unchecked) Node proxyPoint;
322
323 public ProxyPlaceholder(ValueNode value, MergeNode proxyPoint) {
324 super(TYPE, value.stamp(NodeView.DEFAULT));
325 this.value = value;
326 this.proxyPoint = proxyPoint;
327 }
328
329 void setValue(ValueNode value) {
330 updateUsages(this.value, value);
331 this.value = value;
332 }
333
334 @Override
335 public Node canonical(CanonicalizerTool tool) {
336 if (tool.allUsagesAvailable()) {
337 /* The node is always unnecessary after graph decoding. */
338 return value;
339 } else {
340 return this;
341 }
342 }
343
344 public static ValueNode unwrap(ValueNode value) {
345 ValueNode result = value;
346 while (result instanceof ProxyPlaceholder) {
347 result = ((ProxyPlaceholder) result).value;
348 }
349 return result;
350 }
351 }
352
353 protected final Architecture architecture;
354 /** The target graph where decoded nodes are added to. */
355 protected final StructuredGraph graph;
356 protected final OptionValues options;
357 protected final DebugContext debug;
358
359 private final EconomicMap<NodeClass<?>, ArrayDeque<Node>> reusableFloatingNodes;
360
361 public GraphDecoder(Architecture architecture, StructuredGraph graph) {
362 this.architecture = architecture;
363 this.graph = graph;
364 this.options = graph.getOptions();
365 this.debug = graph.getDebug();
366 reusableFloatingNodes = EconomicMap.create(Equivalence.IDENTITY);
367 }
368
369 @SuppressWarnings("try")
370 public final void decode(EncodedGraph encodedGraph) {
371 try (DebugContext.Scope scope = debug.scope("GraphDecoder", graph)) {
372 MethodScope methodScope = new MethodScope(null, graph, encodedGraph, LoopExplosionKind.NONE);
373 decode(createInitialLoopScope(methodScope, null));
374 cleanupGraph(methodScope);
375 assert graph.verify();
376 } catch (Throwable ex) {
377 debug.handle(ex);
378 }
379 }
380
381 protected final LoopScope createInitialLoopScope(MethodScope methodScope, FixedWithNextNode startNode) {
382 LoopScope loopScope = new LoopScope(methodScope);
383 FixedNode firstNode;
384 if (startNode != null) {
385 /*
386 * The start node of a graph can be referenced as the guard for a GuardedNode. We
387 * register the previous block node, so that such guards are correctly anchored when
388 * doing inlining during graph decoding.
389 */
390 registerNode(loopScope, GraphEncoder.START_NODE_ORDER_ID, AbstractBeginNode.prevBegin(startNode), false, false);
391
392 firstNode = makeStubNode(methodScope, loopScope, GraphEncoder.FIRST_NODE_ORDER_ID);
393 startNode.setNext(firstNode);
394 loopScope.nodesToProcess.set(GraphEncoder.FIRST_NODE_ORDER_ID);
395 } else {
396 firstNode = graph.start();
397 registerNode(loopScope, GraphEncoder.START_NODE_ORDER_ID, firstNode, false, false);
398 loopScope.nodesToProcess.set(GraphEncoder.START_NODE_ORDER_ID);
399 }
400 return loopScope;
401 }
402
403 protected final void decode(LoopScope initialLoopScope) {
404 LoopScope loopScope = initialLoopScope;
405 /* Process (inlined) methods. */
406 while (loopScope != null) {
407 MethodScope methodScope = loopScope.methodScope;
408
409 /* Process loops of method. */
410 while (loopScope != null) {
411
412 /* Process nodes of loop. */
413 while (!loopScope.nodesToProcess.isEmpty()) {
414 loopScope = processNextNode(methodScope, loopScope);
415 methodScope = loopScope.methodScope;
416 /*
417 * We can have entered a new loop, and we can have entered a new inlined method.
418 */
419 }
420
421 /* Finished with a loop. */
422 if (loopScope.nextIterations != null && !loopScope.nextIterations.isEmpty()) {
423 /* Loop explosion: process the loop iteration. */
424 assert loopScope.nextIterations.peekFirst().loopIteration == loopScope.loopIteration + 1;
425 loopScope = loopScope.nextIterations.removeFirst();
426 } else {
427 propagateCreatedNodes(loopScope);
428 loopScope = loopScope.outer;
429 }
430 }
431
432 /*
433 * Finished with an inlined method. Perform end-of-method cleanup tasks.
434 */
435 if (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE) {
436 LoopDetector loopDetector = new LoopDetector(graph, methodScope);
437 loopDetector.run();
438 }
439 if (methodScope.isInlinedMethod()) {
440 finishInlining(methodScope);
441 }
442
443 /* continue with the caller */
444 loopScope = methodScope.callerLoopScope;
445 }
446 }
447
448 protected void finishInlining(@SuppressWarnings("unused") MethodScope inlineScope) {
449 }
450
451 private static void propagateCreatedNodes(LoopScope loopScope) {
452 if (loopScope.outer == null || loopScope.createdNodes != loopScope.outer.createdNodes) {
453 return;
454 }
455
456 /* Register nodes that were created while decoding the loop to the outside scope. */
457 for (int i = 0; i < loopScope.createdNodes.length; i++) {
458 if (loopScope.outer.createdNodes[i] == null) {
459 loopScope.outer.createdNodes[i] = loopScope.createdNodes[i];
460 }
461 }
462 }
463
464 protected LoopScope processNextNode(MethodScope methodScope, LoopScope loopScope) {
465 int nodeOrderId = loopScope.nodesToProcess.nextSetBit(0);
466 loopScope.nodesToProcess.clear(nodeOrderId);
467
468 FixedNode node = (FixedNode) lookupNode(loopScope, nodeOrderId);
469 if (node.isDeleted()) {
470 return loopScope;
471 }
472
473 if ((node instanceof MergeNode ||
474 (node instanceof LoopBeginNode && (methodScope.loopExplosion == LoopExplosionKind.FULL_UNROLL || methodScope.loopExplosion == LoopExplosionKind.FULL_EXPLODE ||
475 methodScope.loopExplosion == LoopExplosionKind.FULL_EXPLODE_UNTIL_RETURN))) &&
476 ((AbstractMergeNode) node).forwardEndCount() == 1) {
477 AbstractMergeNode merge = (AbstractMergeNode) node;
478 EndNode singleEnd = merge.forwardEndAt(0);
479
480 /* Nodes that would use this merge as the guard need to use the previous block. */
481 registerNode(loopScope, nodeOrderId, AbstractBeginNode.prevBegin(singleEnd), true, false);
482
483 FixedNode next = makeStubNode(methodScope, loopScope, nodeOrderId + GraphEncoder.BEGIN_NEXT_ORDER_ID_OFFSET);
484 singleEnd.replaceAtPredecessor(next);
485
486 merge.safeDelete();
487 singleEnd.safeDelete();
488 return loopScope;
489 }
490
491 LoopScope successorAddScope = loopScope;
492 boolean updatePredecessors = true;
493 if (node instanceof LoopExitNode) {
494 if (methodScope.loopExplosion == LoopExplosionKind.FULL_EXPLODE_UNTIL_RETURN || (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE && loopScope.loopDepth > 1)) {
495 /*
496 * We do not want to merge loop exits of inner loops. Instead, we want to keep
497 * exploding the outer loop separately for every loop exit and then merge the outer
498 * loop. Therefore, we create a new LoopScope of the outer loop for every loop exit
499 * of the inner loop.
500 */
501 LoopScope outerScope = loopScope.outer;
502 int nextIterationNumber = outerScope.nextIterations.isEmpty() ? outerScope.loopIteration + 1 : outerScope.nextIterations.getLast().loopIteration + 1;
503 successorAddScope = new LoopScope(methodScope, outerScope.outer, outerScope.loopDepth, nextIterationNumber, outerScope.loopBeginOrderId,
504 outerScope.initialCreatedNodes == null ? null : Arrays.copyOf(outerScope.initialCreatedNodes, outerScope.initialCreatedNodes.length),
505 Arrays.copyOf(loopScope.initialCreatedNodes, loopScope.initialCreatedNodes.length), outerScope.nextIterations, outerScope.iterationStates);
506 checkLoopExplosionIteration(methodScope, successorAddScope);
507
508 /*
509 * Nodes that are still unprocessed in the outer scope might be merge nodes that are
510 * also reachable from the new exploded scope. Clearing them ensures that we do not
511 * merge, but instead keep exploding.
512 */
513 for (int id = outerScope.nodesToProcess.nextSetBit(0); id >= 0; id = outerScope.nodesToProcess.nextSetBit(id + 1)) {
514 successorAddScope.createdNodes[id] = null;
515 }
516
517 outerScope.nextIterations.addLast(successorAddScope);
518 } else {
519 successorAddScope = loopScope.outer;
520 }
521 updatePredecessors = methodScope.loopExplosion == LoopExplosionKind.NONE;
522 }
523
524 methodScope.reader.setByteIndex(methodScope.encodedGraph.nodeStartOffsets[nodeOrderId]);
525 int typeId = methodScope.reader.getUVInt();
526 assert node.getNodeClass() == methodScope.encodedGraph.getNodeClasses()[typeId];
527 makeFixedNodeInputs(methodScope, loopScope, node);
528 readProperties(methodScope, node);
529 makeSuccessorStubs(methodScope, successorAddScope, node, updatePredecessors);
530
531 LoopScope resultScope = loopScope;
532 if (node instanceof LoopBeginNode) {
533 if (methodScope.loopExplosion != LoopExplosionKind.NONE) {
534 handleLoopExplosionBegin(methodScope, loopScope, (LoopBeginNode) node);
535 }
536
537 } else if (node instanceof LoopExitNode) {
538 if (methodScope.loopExplosion != LoopExplosionKind.NONE) {
539 handleLoopExplosionProxyNodes(methodScope, loopScope, successorAddScope, (LoopExitNode) node, nodeOrderId);
540 } else {
541 handleProxyNodes(methodScope, loopScope, (LoopExitNode) node);
542 }
543
544 } else if (node instanceof MergeNode) {
545 handleMergeNode(((MergeNode) node));
546
547 } else if (node instanceof AbstractEndNode) {
548 LoopScope phiInputScope = loopScope;
549 LoopScope phiNodeScope = loopScope;
550
551 if (methodScope.loopExplosion != LoopExplosionKind.NONE && node instanceof LoopEndNode) {
552 node = handleLoopExplosionEnd(methodScope, loopScope, (LoopEndNode) node);
553 phiNodeScope = loopScope.nextIterations.getLast();
554 }
555
556 int mergeOrderId = readOrderId(methodScope);
557 AbstractMergeNode merge = (AbstractMergeNode) lookupNode(phiNodeScope, mergeOrderId);
558 if (merge == null) {
559 merge = (AbstractMergeNode) makeStubNode(methodScope, phiNodeScope, mergeOrderId);
560
561 if (merge instanceof LoopBeginNode) {
562 assert phiNodeScope == phiInputScope && phiNodeScope == loopScope;
563 resultScope = new LoopScope(methodScope, loopScope, loopScope.loopDepth + 1, 0, mergeOrderId,
564 methodScope.loopExplosion != LoopExplosionKind.NONE ? Arrays.copyOf(loopScope.createdNodes, loopScope.createdNodes.length) : null,
565 methodScope.loopExplosion != LoopExplosionKind.NONE ? Arrays.copyOf(loopScope.createdNodes, loopScope.createdNodes.length) : loopScope.createdNodes, //
566 methodScope.loopExplosion != LoopExplosionKind.NONE ? new ArrayDeque<>(2) : null, //
567 methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE ? EconomicMap.create(Equivalence.DEFAULT) : null);
568 phiInputScope = resultScope;
569 phiNodeScope = resultScope;
570
571 if (methodScope.loopExplosion != LoopExplosionKind.NONE) {
572 registerNode(loopScope, mergeOrderId, null, true, true);
573 }
574 loopScope.nodesToProcess.clear(mergeOrderId);
575 resultScope.nodesToProcess.set(mergeOrderId);
576 }
577 }
578
579 handlePhiFunctions(methodScope, phiInputScope, phiNodeScope, (AbstractEndNode) node, merge);
580
581 } else if (node instanceof Invoke) {
582 InvokeData invokeData = readInvokeData(methodScope, nodeOrderId, (Invoke) node);
583 resultScope = handleInvoke(methodScope, loopScope, invokeData);
584
585 } else if (node instanceof ReturnNode || node instanceof UnwindNode) {
586 methodScope.returnAndUnwindNodes.add((ControlSinkNode) node);
587 } else {
588 handleFixedNode(methodScope, loopScope, nodeOrderId, node);
589 }
590
591 return resultScope;
592 }
593
594 protected InvokeData readInvokeData(MethodScope methodScope, int invokeOrderId, Invoke invoke) {
595 ResolvedJavaType contextType = (ResolvedJavaType) readObject(methodScope);
596 int callTargetOrderId = readOrderId(methodScope);
597 int stateAfterOrderId = readOrderId(methodScope);
598 int nextOrderId = readOrderId(methodScope);
599
600 if (invoke instanceof InvokeWithExceptionNode) {
601 int nextNextOrderId = readOrderId(methodScope);
602 int exceptionOrderId = readOrderId(methodScope);
603 int exceptionStateOrderId = readOrderId(methodScope);
604 int exceptionNextOrderId = readOrderId(methodScope);
605 return new InvokeData(invoke, contextType, invokeOrderId, callTargetOrderId, stateAfterOrderId, nextOrderId, nextNextOrderId, exceptionOrderId, exceptionStateOrderId,
606 exceptionNextOrderId);
607 } else {
608 return new InvokeData(invoke, contextType, invokeOrderId, callTargetOrderId, stateAfterOrderId, nextOrderId, -1, -1, -1, -1);
609 }
610 }
611
612 /**
613 * {@link Invoke} nodes do not have the {@link CallTargetNode}, {@link FrameState}, and
614 * successors encoded. Instead, this information is provided separately to allow method inlining
615 * without decoding and adding them to the graph upfront. For non-inlined methods, this method
616 * restores the normal state. Subclasses can override it to perform method inlining.
617 *
618 * The return value is the loop scope where decoding should continue. When method inlining
619 * should be performed, the returned loop scope must be a new loop scope for the inlined method.
620 * Without inlining, the original loop scope must be returned.
621 */
622 protected LoopScope handleInvoke(MethodScope methodScope, LoopScope loopScope, InvokeData invokeData) {
623 assert invokeData.invoke.callTarget() == null : "callTarget edge is ignored during decoding of Invoke";
624 CallTargetNode callTarget = (CallTargetNode) ensureNodeCreated(methodScope, loopScope, invokeData.callTargetOrderId);
625 appendInvoke(methodScope, loopScope, invokeData, callTarget);
626 return loopScope;
627 }
628
629 protected void appendInvoke(MethodScope methodScope, LoopScope loopScope, InvokeData invokeData, CallTargetNode callTarget) {
630 if (invokeData.invoke instanceof InvokeWithExceptionNode) {
631 ((InvokeWithExceptionNode) invokeData.invoke).setCallTarget(callTarget);
632 } else {
633 ((InvokeNode) invokeData.invoke).setCallTarget(callTarget);
634 }
635
636 assert invokeData.invoke.stateAfter() == null && invokeData.invoke.stateDuring() == null : "FrameState edges are ignored during decoding of Invoke";
637 invokeData.invoke.setStateAfter((FrameState) ensureNodeCreated(methodScope, loopScope, invokeData.stateAfterOrderId));
638
639 invokeData.invoke.setNext(makeStubNode(methodScope, loopScope, invokeData.nextOrderId));
640 if (invokeData.invoke instanceof InvokeWithExceptionNode) {
641 ((InvokeWithExceptionNode) invokeData.invoke).setExceptionEdge((AbstractBeginNode) makeStubNode(methodScope, loopScope, invokeData.exceptionOrderId));
642 }
643 }
644
645 /**
646 * Hook for subclasses to perform simplifications for a non-loop-header control flow merge.
647 *
648 * @param merge The control flow merge.
649 */
650 protected void handleMergeNode(MergeNode merge) {
651 }
652
653 protected void handleLoopExplosionBegin(MethodScope methodScope, LoopScope loopScope, LoopBeginNode loopBegin) {
654 checkLoopExplosionIteration(methodScope, loopScope);
655
656 List<EndNode> predecessors = loopBegin.forwardEnds().snapshot();
657 FixedNode successor = loopBegin.next();
658 FrameState frameState = loopBegin.stateAfter();
659
660 if (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE) {
661 LoopExplosionState queryState = new LoopExplosionState(frameState, null);
662 LoopExplosionState existingState = loopScope.iterationStates.get(queryState);
663 if (existingState != null) {
664 loopBegin.replaceAtUsagesAndDelete(existingState.merge);
665 successor.safeDelete();
666 for (EndNode predecessor : predecessors) {
667 existingState.merge.addForwardEnd(predecessor);
668 }
669 return;
670 }
671 }
672
673 MergeNode merge = graph.add(new MergeNode());
674 methodScope.loopExplosionMerges.add(merge);
675
676 if (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE) {
677 if (loopScope.iterationStates.size() == 0 && loopScope.loopDepth == 1) {
678 if (methodScope.loopExplosionHead != null) {
679 throw new PermanentBailoutException("Graal implementation restriction: Method with %s loop explosion must not have more than one top-level loop", LoopExplosionKind.MERGE_EXPLODE);
680 }
681 methodScope.loopExplosionHead = merge;
682 }
683
684 List<ValueNode> newFrameStateValues = new ArrayList<>();
685 for (ValueNode frameStateValue : frameState.values) {
686 if (frameStateValue == null || frameStateValue.isConstant() || !graph.isNew(methodScope.methodStartMark, frameStateValue)) {
687 newFrameStateValues.add(frameStateValue);
688
689 } else {
690 ProxyPlaceholder newFrameStateValue = graph.unique(new ProxyPlaceholder(frameStateValue, merge));
691 newFrameStateValues.add(newFrameStateValue);
692
693 /*
694 * We do not have the orderID of the value anymore, so we need to search through
695 * the complete list of nodes to find a match.
696 */
697 for (int i = 0; i < loopScope.createdNodes.length; i++) {
698 if (loopScope.createdNodes[i] == frameStateValue) {
699 loopScope.createdNodes[i] = newFrameStateValue;
700 }
701 }
702
703 if (loopScope.initialCreatedNodes != null) {
704 for (int i = 0; i < loopScope.initialCreatedNodes.length; i++) {
705 if (loopScope.initialCreatedNodes[i] == frameStateValue) {
706 loopScope.initialCreatedNodes[i] = newFrameStateValue;
707 }
708 }
709 }
710 }
711 }
712
713 FrameState newFrameState = graph.add(new FrameState(frameState.outerFrameState(), frameState.getCode(), frameState.bci, newFrameStateValues, frameState.localsSize(),
714 frameState.stackSize(), frameState.rethrowException(), frameState.duringCall(), frameState.monitorIds(), frameState.virtualObjectMappings()));
715
716 frameState.replaceAtUsagesAndDelete(newFrameState);
717 frameState = newFrameState;
718 }
719
720 loopBegin.replaceAtUsagesAndDelete(merge);
721 merge.setStateAfter(frameState);
722 merge.setNext(successor);
723 for (EndNode predecessor : predecessors) {
724 merge.addForwardEnd(predecessor);
725 }
726
727 if (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE) {
728 LoopExplosionState explosionState = new LoopExplosionState(frameState, merge);
729 loopScope.iterationStates.put(explosionState, explosionState);
730 }
731 }
732
733 /**
734 * Hook for subclasses.
735 *
736 * @param methodScope The current method.
737 * @param loopScope The current loop.
738 */
739 protected void checkLoopExplosionIteration(MethodScope methodScope, LoopScope loopScope) {
740 throw shouldNotReachHere("when subclass uses loop explosion, it needs to implement this method");
741 }
742
743 protected FixedNode handleLoopExplosionEnd(MethodScope methodScope, LoopScope loopScope, LoopEndNode loopEnd) {
744 EndNode replacementNode = graph.add(new EndNode());
745 loopEnd.replaceAtPredecessor(replacementNode);
746 loopEnd.safeDelete();
747
748 assert methodScope.loopExplosion != LoopExplosionKind.NONE;
749 if (methodScope.loopExplosion != LoopExplosionKind.FULL_UNROLL || loopScope.nextIterations.isEmpty()) {
750 int nextIterationNumber = loopScope.nextIterations.isEmpty() ? loopScope.loopIteration + 1 : loopScope.nextIterations.getLast().loopIteration + 1;
751 LoopScope nextIterationScope = new LoopScope(methodScope, loopScope.outer, loopScope.loopDepth, nextIterationNumber, loopScope.loopBeginOrderId,
752 Arrays.copyOf(loopScope.initialCreatedNodes, loopScope.initialCreatedNodes.length),
753 Arrays.copyOf(loopScope.initialCreatedNodes, loopScope.initialCreatedNodes.length), loopScope.nextIterations, loopScope.iterationStates);
754 checkLoopExplosionIteration(methodScope, nextIterationScope);
755 loopScope.nextIterations.addLast(nextIterationScope);
756 registerNode(nextIterationScope, loopScope.loopBeginOrderId, null, true, true);
757 makeStubNode(methodScope, nextIterationScope, loopScope.loopBeginOrderId);
758 }
759 return replacementNode;
760 }
761
762 /**
763 * Hook for subclasses.
764 *
765 * @param methodScope The current method.
766 * @param loopScope The current loop.
767 * @param nodeOrderId The orderId of the node.
768 * @param node The node to be simplified.
769 */
770 protected void handleFixedNode(MethodScope methodScope, LoopScope loopScope, int nodeOrderId, FixedNode node) {
771 }
772
773 protected void handleProxyNodes(MethodScope methodScope, LoopScope loopScope, LoopExitNode loopExit) {
774 assert loopExit.stateAfter() == null;
775 int stateAfterOrderId = readOrderId(methodScope);
776 loopExit.setStateAfter((FrameState) ensureNodeCreated(methodScope, loopScope, stateAfterOrderId));
777
778 int numProxies = methodScope.reader.getUVInt();
779 for (int i = 0; i < numProxies; i++) {
780 int proxyOrderId = readOrderId(methodScope);
781 ProxyNode proxy = (ProxyNode) ensureNodeCreated(methodScope, loopScope, proxyOrderId);
782 /*
783 * The ProxyNode transports a value from the loop to the outer scope. We therefore
784 * register it in the outer scope.
785 */
786 if (loopScope.outer.createdNodes != loopScope.createdNodes) {
787 registerNode(loopScope.outer, proxyOrderId, proxy, false, false);
788 }
789 }
790 }
791
792 protected void handleLoopExplosionProxyNodes(MethodScope methodScope, LoopScope loopScope, LoopScope outerScope, LoopExitNode loopExit, int loopExitOrderId) {
793 assert loopExit.stateAfter() == null;
794 int stateAfterOrderId = readOrderId(methodScope);
795
796 BeginNode begin = graph.add(new BeginNode());
797
798 FixedNode loopExitSuccessor = loopExit.next();
799 loopExit.replaceAtPredecessor(begin);
800
801 MergeNode loopExitPlaceholder = null;
802 if (methodScope.loopExplosion == LoopExplosionKind.MERGE_EXPLODE && loopScope.loopDepth == 1) {
803 /*
804 * This exit might end up as a loop exit of a loop detected after partial evaluation. We
805 * need to be able to create a FrameState and the necessary proxy nodes in this case.
806 */
807 loopExitPlaceholder = graph.add(new MergeNode());
808 methodScope.loopExplosionMerges.add(loopExitPlaceholder);
809
810 EndNode end = graph.add(new EndNode());
811 begin.setNext(end);
812 loopExitPlaceholder.addForwardEnd(end);
813
814 begin = graph.add(new BeginNode());
815 loopExitPlaceholder.setNext(begin);
816 }
817
818 /*
819 * In the original graph, the loop exit is not a merge node. Multiple exploded loop
820 * iterations now take the same loop exit, so we have to introduce a new merge node to
821 * handle the merge.
822 */
823 MergeNode merge = null;
824 Node existingExit = lookupNode(outerScope, loopExitOrderId);
825 if (existingExit == null) {
826 /* First loop iteration that exits. No merge necessary yet. */
827 registerNode(outerScope, loopExitOrderId, begin, false, false);
828 begin.setNext(loopExitSuccessor);
829
830 } else if (existingExit instanceof BeginNode) {
831 /* Second loop iteration that exits. Create the merge. */
832 merge = graph.add(new MergeNode());
833 registerNode(outerScope, loopExitOrderId, merge, true, false);
834 /* Add the first iteration. */
835 EndNode firstEnd = graph.add(new EndNode());
836 ((BeginNode) existingExit).setNext(firstEnd);
837 merge.addForwardEnd(firstEnd);
838 merge.setNext(loopExitSuccessor);
839
840 } else {
841 /* Subsequent loop iteration. Merge already created. */
842 merge = (MergeNode) existingExit;
843 }
844
845 if (merge != null) {
846 EndNode end = graph.add(new EndNode());
847 begin.setNext(end);
848 merge.addForwardEnd(end);
849 }
850
851 /*
852 * Possibly create phi nodes for the original proxy nodes that flow out of the loop. Note
853 * that we definitely do not need a proxy node itself anymore, since the loop was exploded
854 * and is no longer present.
855 */
856 int numProxies = methodScope.reader.getUVInt();
857 boolean phiCreated = false;
858 for (int i = 0; i < numProxies; i++) {
859 int proxyOrderId = readOrderId(methodScope);
860 ProxyNode proxy = (ProxyNode) ensureNodeCreated(methodScope, loopScope, proxyOrderId);
861 ValueNode phiInput = proxy.value();
862
863 if (loopExitPlaceholder != null) {
864 if (!phiInput.isConstant()) {
865 phiInput = graph.unique(new ProxyPlaceholder(phiInput, loopExitPlaceholder));
866 }
867 registerNode(loopScope, proxyOrderId, phiInput, true, false);
868 }
869
870 ValueNode replacement;
871 ValueNode existing = (ValueNode) outerScope.createdNodes[proxyOrderId];
872 if (existing == null || existing == phiInput) {
873 /*
874 * We are at the first loop exit, or the proxy carries the same value for all exits.
875 * We do not need a phi node yet.
876 */
877 registerNode(outerScope, proxyOrderId, phiInput, true, false);
878 replacement = phiInput;
879
880 } else if (!merge.isPhiAtMerge(existing)) {
881 /* Now we have two different values, so we need to create a phi node. */
882 PhiNode phi;
883 if (proxy instanceof ValueProxyNode) {
884 phi = graph.addWithoutUnique(new ValuePhiNode(proxy.stamp(NodeView.DEFAULT), merge));
885 } else if (proxy instanceof GuardProxyNode) {
886 phi = graph.addWithoutUnique(new GuardPhiNode(merge));
887 } else {
888 throw GraalError.shouldNotReachHere();
889 }
890 /* Add the inputs from all previous exits. */
891 for (int j = 0; j < merge.phiPredecessorCount() - 1; j++) {
892 phi.addInput(existing);
893 }
894 /* Add the input from this exit. */
895 phi.addInput(phiInput);
896 registerNode(outerScope, proxyOrderId, phi, true, false);
897 replacement = phi;
898 phiCreated = true;
899
900 } else {
901 /* Phi node has been created before, so just add the new input. */
902 PhiNode phi = (PhiNode) existing;
903 phi.addInput(phiInput);
904 replacement = phi;
905 }
906
907 proxy.replaceAtUsagesAndDelete(replacement);
908 }
909
910 if (loopExitPlaceholder != null) {
911 registerNode(loopScope, stateAfterOrderId, null, true, true);
912 loopExitPlaceholder.setStateAfter((FrameState) ensureNodeCreated(methodScope, loopScope, stateAfterOrderId));
913 }
914
915 if (merge != null && (merge.stateAfter() == null || phiCreated)) {
916 FrameState oldStateAfter = merge.stateAfter();
917 registerNode(outerScope, stateAfterOrderId, null, true, true);
918 merge.setStateAfter((FrameState) ensureNodeCreated(methodScope, outerScope, stateAfterOrderId));
919 if (oldStateAfter != null) {
920 oldStateAfter.safeDelete();
921 }
922 }
923 loopExit.safeDelete();
924 assert loopExitSuccessor.predecessor() == null;
925 if (merge != null) {
926 merge.getNodeClass().getSuccessorEdges().update(merge, null, loopExitSuccessor);
927 } else {
928 begin.getNodeClass().getSuccessorEdges().update(begin, null, loopExitSuccessor);
929 }
930 }
931
932 protected void handlePhiFunctions(MethodScope methodScope, LoopScope phiInputScope, LoopScope phiNodeScope, AbstractEndNode end, AbstractMergeNode merge) {
933
934 if (end instanceof LoopEndNode) {
935 /*
936 * Fix the loop end index and the number of loop ends. When we do canonicalization
937 * during decoding, we can end up with fewer ends than the encoded graph had. And the
938 * order of loop ends can be different.
939 */
940 int numEnds = ((LoopBeginNode) merge).loopEnds().count();
941 ((LoopBeginNode) merge).nextEndIndex = numEnds;
942 ((LoopEndNode) end).endIndex = numEnds - 1;
943
944 } else {
945 if (merge.ends == null) {
946 merge.ends = new NodeInputList<>(merge);
947 }
948 merge.addForwardEnd((EndNode) end);
949 }
950
951 /*
952 * We create most phi functions lazily. Canonicalization and simplification during decoding
953 * can lead to dead branches that are not decoded, so we might not need all phi functions
954 * that the original graph contained. Since we process all predecessors before actually
955 * processing the merge node, we have the final phi function when processing the merge node.
956 * The only exception are loop headers of non-exploded loops: since backward branches are
957 * not processed yet when processing the loop body, we need to create all phi functions
958 * upfront.
959 */
960 boolean lazyPhi = allowLazyPhis() && (!(merge instanceof LoopBeginNode) || methodScope.loopExplosion != LoopExplosionKind.NONE);
961 int numPhis = methodScope.reader.getUVInt();
962 for (int i = 0; i < numPhis; i++) {
963 int phiInputOrderId = readOrderId(methodScope);
964 int phiNodeOrderId = readOrderId(methodScope);
965
966 ValueNode phiInput = (ValueNode) ensureNodeCreated(methodScope, phiInputScope, phiInputOrderId);
967 ValueNode existing = (ValueNode) lookupNode(phiNodeScope, phiNodeOrderId);
968
969 if (existing != null && merge.phiPredecessorCount() == 1) {
970 /*
971 * When exploding loops and the code after the loop (FULL_EXPLODE_UNTIL_RETURN),
972 * then an existing value can already be registered: Parsing of the code before the
973 * loop registers it when preparing for the later merge. The code after the loop,
974 * which starts with a clone of the values that were created before the loop, sees
975 * the stale value when processing the merge the first time. We can safely ignore
976 * the stale value because it will never be needed to be merged (we are exploding
977 * until we hit a return).
978 */
979 assert methodScope.loopExplosion == LoopExplosionKind.FULL_EXPLODE_UNTIL_RETURN && phiNodeScope.loopIteration > 0;
980 existing = null;
981 }
982
983 if (lazyPhi && (existing == null || existing == phiInput)) {
984 /* Phi function not yet necessary. */
985 registerNode(phiNodeScope, phiNodeOrderId, phiInput, true, false);
986
987 } else if (!merge.isPhiAtMerge(existing)) {
988 /*
989 * Phi function is necessary. Create it and fill it with existing inputs as well as
990 * the new input.
991 */
992 registerNode(phiNodeScope, phiNodeOrderId, null, true, true);
993 PhiNode phi = (PhiNode) ensureNodeCreated(methodScope, phiNodeScope, phiNodeOrderId);
994
995 phi.setMerge(merge);
996 for (int j = 0; j < merge.phiPredecessorCount() - 1; j++) {
997 phi.addInput(existing);
998 }
999 phi.addInput(phiInput);
1000
1001 } else {
1002 /* Phi node has been created before, so just add the new input. */
1003 PhiNode phi = (PhiNode) existing;
1004 phi.addInput(phiInput);
1005 }
1006 }
1007 }
1008
1009 protected boolean allowLazyPhis() {
1010 /* We need to exactly reproduce the encoded graph, including unnecessary phi functions. */
1011 return false;
1012 }
1013
1014 protected void readProperties(MethodScope methodScope, Node node) {
1015 NodeSourcePosition position = (NodeSourcePosition) readObject(methodScope);
1016 Fields fields = node.getNodeClass().getData();
1017 for (int pos = 0; pos < fields.getCount(); pos++) {
1018 if (fields.getType(pos).isPrimitive()) {
1019 long primitive = methodScope.reader.getSV();
1020 fields.setRawPrimitive(node, pos, primitive);
1021 } else {
1022 Object value = readObject(methodScope);
1023 fields.putObject(node, pos, value);
1024 }
1025 }
1026 if (graph.trackNodeSourcePosition() && position != null) {
1027 NodeSourcePosition callerBytecodePosition = methodScope.getCallerBytecodePosition(position);
1028 node.setNodeSourcePosition(callerBytecodePosition);
1029 if (node instanceof DeoptimizingGuard) {
1030 ((DeoptimizingGuard) node).addCallerToNoDeoptSuccessorPosition(callerBytecodePosition.getCaller());
1031 }
1032 }
1033 }
1034
1035 /**
1036 * Process the input edges of a node. Input nodes that have not yet been created must be
1037 * non-fixed nodes (because fixed nodes are processed in reverse postorder. Such non-fixed nodes
1038 * are created on demand (recursively since they can themselves reference not yet created
1039 * nodes).
1040 */
1041 protected void makeFixedNodeInputs(MethodScope methodScope, LoopScope loopScope, Node node) {
1042 Edges edges = node.getNodeClass().getInputEdges();
1043 for (int index = 0; index < edges.getDirectCount(); index++) {
1044 if (skipDirectEdge(node, edges, index)) {
1045 continue;
1046 }
1047 int orderId = readOrderId(methodScope);
1048 Node value = ensureNodeCreated(methodScope, loopScope, orderId);
1049 edges.initializeNode(node, index, value);
1050 if (value != null && !value.isDeleted()) {
1051 edges.update(node, null, value);
1052
1053 }
1054 }
1055
1056 if (node instanceof AbstractMergeNode) {
1057 /* The ends of merge nodes are filled manually when the ends are processed. */
1058 assert edges.getCount() - edges.getDirectCount() == 1 : "MergeNode has one variable size input (the ends)";
1059 assert Edges.getNodeList(node, edges.getOffsets(), edges.getDirectCount()) != null : "Input list must have been already created";
1060 } else {
1061 for (int index = edges.getDirectCount(); index < edges.getCount(); index++) {
1062 int size = methodScope.reader.getSVInt();
1063 if (size != -1) {
1064 NodeList<Node> nodeList = new NodeInputList<>(node, size);
1065 edges.initializeList(node, index, nodeList);
1066 for (int idx = 0; idx < size; idx++) {
1067 int orderId = readOrderId(methodScope);
1068 Node value = ensureNodeCreated(methodScope, loopScope, orderId);
1069 nodeList.initialize(idx, value);
1070 if (value != null && !value.isDeleted()) {
1071 edges.update(node, null, value);
1072 }
1073 }
1074 }
1075 }
1076 }
1077 }
1078
1079 protected void makeFloatingNodeInputs(MethodScope methodScope, LoopScope loopScope, Node node) {
1080 Edges edges = node.getNodeClass().getInputEdges();
1081 if (node instanceof PhiNode) {
1082 /*
1083 * The inputs of phi functions are filled manually when the end nodes are processed.
1084 * However, the values must not be null, so initialize them with an empty list.
1085 */
1086 assert edges.getDirectCount() == 1 : "PhiNode has one direct input (the MergeNode)";
1087 assert edges.getCount() - edges.getDirectCount() == 1 : "PhiNode has one variable size input (the values)";
1088 edges.initializeList(node, edges.getDirectCount(), new NodeInputList<>(node));
1089 } else {
1090 for (int index = 0; index < edges.getDirectCount(); index++) {
1091 int orderId = readOrderId(methodScope);
1092 Node value = ensureNodeCreated(methodScope, loopScope, orderId);
1093 edges.initializeNode(node, index, value);
1094 }
1095 for (int index = edges.getDirectCount(); index < edges.getCount(); index++) {
1096 int size = methodScope.reader.getSVInt();
1097 if (size != -1) {
1098 NodeList<Node> nodeList = new NodeInputList<>(node, size);
1099 edges.initializeList(node, index, nodeList);
1100 for (int idx = 0; idx < size; idx++) {
1101 int orderId = readOrderId(methodScope);
1102 Node value = ensureNodeCreated(methodScope, loopScope, orderId);
1103 nodeList.initialize(idx, value);
1104 }
1105 }
1106 }
1107 }
1108 }
1109
1110 protected Node ensureNodeCreated(MethodScope methodScope, LoopScope loopScope, int nodeOrderId) {
1111 if (nodeOrderId == GraphEncoder.NULL_ORDER_ID) {
1112 return null;
1113 }
1114 Node node = lookupNode(loopScope, nodeOrderId);
1115 if (node != null) {
1116 return node;
1117 }
1118
1119 node = decodeFloatingNode(methodScope, loopScope, nodeOrderId);
1120 if (node instanceof ProxyNode || node instanceof PhiNode) {
1121 /*
1122 * We need these nodes as they were in the original graph, without any canonicalization
1123 * or value numbering.
1124 */
1125 node = graph.addWithoutUnique(node);
1126 } else {
1127 /* Allow subclasses to canonicalize and intercept nodes. */
1128 Node newNode = handleFloatingNodeBeforeAdd(methodScope, loopScope, node);
1129 if (newNode != node) {
1130 releaseFloatingNode(node);
1131 }
1132
1133 if (!newNode.isAlive()) {
1134 newNode = addFloatingNode(methodScope, newNode);
1135 }
1136 node = handleFloatingNodeAfterAdd(methodScope, loopScope, newNode);
1137 }
1138 registerNode(loopScope, nodeOrderId, node, false, false);
1139 return node;
1140 }
1141
1142 protected Node addFloatingNode(@SuppressWarnings("unused") MethodScope methodScope, Node node) {
1143 /*
1144 * We want to exactly reproduce the encoded graph. Even though nodes should be unique in the
1145 * encoded graph, this is not always guaranteed.
1146 */
1147 return graph.addWithoutUnique(node);
1148 }
1149
1150 /**
1151 * Decodes a non-fixed node, but does not do any post-processing and does not register it.
1152 */
1153 protected Node decodeFloatingNode(MethodScope methodScope, LoopScope loopScope, int nodeOrderId) {
1154 long readerByteIndex = methodScope.reader.getByteIndex();
1155
1156 methodScope.reader.setByteIndex(methodScope.encodedGraph.nodeStartOffsets[nodeOrderId]);
1157 NodeClass<?> nodeClass = methodScope.encodedGraph.getNodeClasses()[methodScope.reader.getUVInt()];
1158 Node node = allocateFloatingNode(nodeClass);
1159 if (node instanceof FixedNode) {
1160 /*
1161 * This is a severe error that will lead to a corrupted graph, so it is better not to
1162 * continue decoding at all.
1163 */
1164 throw shouldNotReachHere("Not a floating node: " + node.getClass().getName());
1165 }
1166
1167 /* Read the inputs of the node, possibly creating them recursively. */
1168 makeFloatingNodeInputs(methodScope, loopScope, node);
1169
1170 /* Read the properties of the node. */
1171 readProperties(methodScope, node);
1172 /* There must not be any successors to read, since it is a non-fixed node. */
1173 assert node.getNodeClass().getEdges(Edges.Type.Successors).getCount() == 0;
1174
1175 methodScope.reader.setByteIndex(readerByteIndex);
1176 return node;
1177 }
1178
1179 private Node allocateFloatingNode(NodeClass<?> nodeClass) {
1180 ArrayDeque<? extends Node> cachedNodes = reusableFloatingNodes.get(nodeClass);
1181 if (cachedNodes != null) {
1182 Node node = cachedNodes.poll();
1183 if (node != null) {
1184 return node;
1185 }
1186 }
1187 return nodeClass.allocateInstance();
1188 }
1189
1190 private void releaseFloatingNode(Node node) {
1191 ArrayDeque<Node> cachedNodes = reusableFloatingNodes.get(node.getNodeClass());
1192 if (cachedNodes == null) {
1193 cachedNodes = new ArrayDeque<>(2);
1194 reusableFloatingNodes.put(node.getNodeClass(), cachedNodes);
1195 }
1196 cachedNodes.push(node);
1197 }
1198
1199 /**
1200 * Hook for subclasses to process a non-fixed node before it is added to the graph.
1201 *
1202 * @param methodScope The current method.
1203 * @param loopScope The current loop.
1204 * @param node The node to be canonicalized.
1205 * @return The replacement for the node, or the node itself.
1206 */
1207 protected Node handleFloatingNodeBeforeAdd(MethodScope methodScope, LoopScope loopScope, Node node) {
1208 return node;
1209 }
1210
1211 /**
1212 * Hook for subclasses to process a non-fixed node after it is added to the graph.
1213 *
1214 * If this method replaces a node with another node, it must update its source position if the
1215 * original node has the source position set.
1216 *
1217 * @param methodScope The current method.
1218 * @param loopScope The current loop.
1219 * @param node The node to be canonicalized.
1220 * @return The replacement for the node, or the node itself.
1221 */
1222 protected Node handleFloatingNodeAfterAdd(MethodScope methodScope, LoopScope loopScope, Node node) {
1223 return node;
1224 }
1225
1226 /**
1227 * Process successor edges of a node. We create the successor nodes so that we can fill the
1228 * successor list, but no properties or edges are loaded yet. That is done when the successor is
1229 * on top of the worklist in {@link #processNextNode}.
1230 */
1231 protected void makeSuccessorStubs(MethodScope methodScope, LoopScope loopScope, Node node, boolean updatePredecessors) {
1232 Edges edges = node.getNodeClass().getSuccessorEdges();
1233 for (int index = 0; index < edges.getDirectCount(); index++) {
1234 if (skipDirectEdge(node, edges, index)) {
1235 continue;
1236 }
1237 int orderId = readOrderId(methodScope);
1238 Node value = makeStubNode(methodScope, loopScope, orderId);
1239 edges.initializeNode(node, index, value);
1240 if (updatePredecessors && value != null) {
1241 edges.update(node, null, value);
1242 }
1243 }
1244 for (int index = edges.getDirectCount(); index < edges.getCount(); index++) {
1245 int size = methodScope.reader.getSVInt();
1246 if (size != -1) {
1247 NodeList<Node> nodeList = new NodeSuccessorList<>(node, size);
1248 edges.initializeList(node, index, nodeList);
1249 for (int idx = 0; idx < size; idx++) {
1250 int orderId = readOrderId(methodScope);
1251 Node value = makeStubNode(methodScope, loopScope, orderId);
1252 nodeList.initialize(idx, value);
1253 if (updatePredecessors && value != null) {
1254 edges.update(node, null, value);
1255 }
1256 }
1257 }
1258 }
1259 }
1260
1261 protected FixedNode makeStubNode(MethodScope methodScope, LoopScope loopScope, int nodeOrderId) {
1262 if (nodeOrderId == GraphEncoder.NULL_ORDER_ID) {
1263 return null;
1264 }
1265 FixedNode node = (FixedNode) lookupNode(loopScope, nodeOrderId);
1266 if (node != null) {
1267 return node;
1268 }
1269
1270 long readerByteIndex = methodScope.reader.getByteIndex();
1271 methodScope.reader.setByteIndex(methodScope.encodedGraph.nodeStartOffsets[nodeOrderId]);
1272 NodeClass<?> nodeClass = methodScope.encodedGraph.getNodeClasses()[methodScope.reader.getUVInt()];
1273 Node stubNode = nodeClass.allocateInstance();
1274 if (graph.trackNodeSourcePosition()) {
1275 stubNode.setNodeSourcePosition(NodeSourcePosition.placeholder(graph.method()));
1276 }
1277 node = (FixedNode) graph.add(stubNode);
1278 /* Properties and edges are not filled yet, the node remains uninitialized. */
1279 methodScope.reader.setByteIndex(readerByteIndex);
1280
1281 registerNode(loopScope, nodeOrderId, node, false, false);
1282 loopScope.nodesToProcess.set(nodeOrderId);
1283 return node;
1284 }
1285
1286 protected static boolean skipDirectEdge(Node node, Edges edges, int index) {
1287 if (node instanceof Invoke) {
1288 assert node instanceof InvokeNode || node instanceof InvokeWithExceptionNode : "The only two Invoke node classes. Got " + node.getClass();
1289 if (edges.type() == Edges.Type.Successors) {
1290 assert edges.getCount() == (node instanceof InvokeWithExceptionNode ? 2 : 1) : "InvokeNode has one successor (next); InvokeWithExceptionNode has two successors (next, exceptionEdge)";
1291 return true;
1292 } else {
1293 assert edges.type() == Edges.Type.Inputs;
1294 if (edges.getType(index) == CallTargetNode.class) {
1295 return true;
1296 } else if (edges.getType(index) == FrameState.class) {
1297 assert edges.get(node, index) == null || edges.get(node, index) == ((Invoke) node).stateAfter() : "Only stateAfter can be a FrameState during encoding";
1298 return true;
1299 }
1300 }
1301 } else if (node instanceof LoopExitNode && edges.type() == Edges.Type.Inputs && edges.getType(index) == FrameState.class) {
1302 /* The stateAfter of the loop exit is filled manually. */
1303 return true;
1304
1305 }
1306 return false;
1307 }
1308
1309 protected Node lookupNode(LoopScope loopScope, int nodeOrderId) {
1310 return loopScope.createdNodes[nodeOrderId];
1311 }
1312
1313 protected void registerNode(LoopScope loopScope, int nodeOrderId, Node node, boolean allowOverwrite, boolean allowNull) {
1314 assert node == null || node.isAlive();
1315 assert allowNull || node != null;
1316 assert allowOverwrite || lookupNode(loopScope, nodeOrderId) == null;
1317 loopScope.createdNodes[nodeOrderId] = node;
1318 }
1319
1320 protected int readOrderId(MethodScope methodScope) {
1321 return methodScope.reader.getUVInt();
1322 }
1323
1324 protected Object readObject(MethodScope methodScope) {
1325 return methodScope.encodedGraph.getObjects()[methodScope.reader.getUVInt()];
1326 }
1327
1328 /**
1329 * Removes unnecessary nodes from the graph after decoding.
1330 *
1331 * @param methodScope The current method.
1332 */
1333 protected void cleanupGraph(MethodScope methodScope) {
1334 assert verifyEdges();
1335 }
1336
1337 protected boolean verifyEdges() {
1338 for (Node node : graph.getNodes()) {
1339 assert node.isAlive();
1340 for (Node i : node.inputs()) {
1341 assert i.isAlive();
1342 assert i.usages().contains(node);
1343 }
1344 for (Node s : node.successors()) {
1345 assert s.isAlive();
1346 assert s.predecessor() == node;
1347 }
1348
1349 for (Node usage : node.usages()) {
1350 assert usage.isAlive();
1351 assert usage.inputs().contains(node) : node + " / " + usage + " / " + usage.inputs().count();
1352 }
1353 if (node.predecessor() != null) {
1354 assert node.predecessor().isAlive();
1355 assert node.predecessor().successors().contains(node);
1356 }
1357 }
1358 return true;
1359 }
1360 }
1361
1362 class LoopDetector implements Runnable {
1363
1364 /**
1365 * Information about loops before the actual loop nodes are inserted.
1366 */
1367 static class Loop {
1368 /**
1369 * The header, i.e., the target of backward branches.
1370 */
1371 MergeNode header;
1372 /**
1373 * The ends, i.e., the source of backward branches. The {@link EndNode#successors successor}
1374 * is the {@link #header loop header}.
1375 */
1376 List<EndNode> ends = new ArrayList<>(2);
1377 /**
1378 * Exits of the loop. The successor is a {@link MergeNode} marked in
1379 * {@link MethodScope#loopExplosionMerges}.
1380 */
1381 List<AbstractEndNode> exits = new ArrayList<>();
1382 /**
1383 * Set to true when the loop is irreducible, i.e., has multiple entries. See
1384 * {@link #handleIrreducibleLoop} for details on the handling.
1385 */
1386 boolean irreducible;
1387 }
1388
1389 private final StructuredGraph graph;
1390 private final MethodScope methodScope;
1391
1392 private Loop irreducibleLoopHandler;
1393 private IntegerSwitchNode irreducibleLoopSwitch;
1394
1395 protected LoopDetector(StructuredGraph graph, MethodScope methodScope) {
1396 this.graph = graph;
1397 this.methodScope = methodScope;
1398 }
1399
1400 @Override
1401 public void run() {
1402 DebugContext debug = graph.getDebug();
1403 debug.dump(DebugContext.DETAILED_LEVEL, graph, "Before loop detection");
1404
1405 if (methodScope.loopExplosionHead == null) {
1406 /*
1407 * The to-be-exploded loop was not reached during partial evaluation (e.g., because
1408 * there was a deoptimization beforehand), or the method might not even contain a loop.
1409 * This is an uncommon case, but not an error.
1410 */
1411 return;
1412 }
1413
1414 List<Loop> orderedLoops = findLoops();
1415 assert orderedLoops.get(orderedLoops.size() - 1) == irreducibleLoopHandler : "outermost loop must be the last element in the list";
1416
1417 for (Loop loop : orderedLoops) {
1418 if (loop.ends.isEmpty()) {
1419 assert loop == irreducibleLoopHandler;
1420 continue;
1421 }
1422
1423 /*
1424 * The algorithm to find loop exits requires that inner loops have already been
1425 * processed. Therefore, we need to iterate the loops in order (inner loops before outer
1426 * loops), and we cannot find the exits for all loops before we start inserting nodes.
1427 */
1428 findLoopExits(loop);
1429
1430 if (loop.irreducible) {
1431 handleIrreducibleLoop(loop);
1432 } else {
1433 insertLoopNodes(loop);
1434 }
1435 debug.dump(DebugContext.DETAILED_LEVEL, graph, "After handling of loop %s", loop.header);
1436 }
1437
1438 logIrreducibleLoops();
1439 debug.dump(DebugContext.DETAILED_LEVEL, graph, "After loop detection");
1440 }
1441
1442 private List<Loop> findLoops() {
1443 /* Mapping from the loop header node to additional loop information. */
1444 EconomicMap<MergeNode, Loop> unorderedLoops = EconomicMap.create(Equivalence.IDENTITY);
1445 /* Loops in reverse order of, i.e., inner loops before outer loops. */
1446 List<Loop> orderedLoops = new ArrayList<>();
1447
1448 /*
1449 * Ensure we have an outermost loop that we can use to eliminate irreducible loops. This
1450 * loop can remain empty (no ends), in which case it is ignored.
1451 */
1452 irreducibleLoopHandler = findOrCreateLoop(unorderedLoops, methodScope.loopExplosionHead);
1453
1454 NodeBitMap visited = graph.createNodeBitMap();
1455 NodeBitMap active = graph.createNodeBitMap();
1456 Deque<Node> stack = new ArrayDeque<>();
1457 visited.mark(methodScope.loopExplosionHead);
1458 stack.push(methodScope.loopExplosionHead);
1459
1460 while (!stack.isEmpty()) {
1461 Node current = stack.peek();
1462 assert visited.isMarked(current);
1463
1464 if (active.isMarked(current)) {
1465 /* We are back-tracking, i.e., all successor nodes have been processed. */
1466 stack.pop();
1467 active.clear(current);
1468
1469 if (current instanceof MergeNode) {
1470 Loop loop = unorderedLoops.get((MergeNode) current);
1471 if (loop != null) {
1472 /*
1473 * Since nodes are popped in reverse order that they were pushed, we add
1474 * inner loops before outer loops here.
1475 */
1476 assert !orderedLoops.contains(loop);
1477 orderedLoops.add(loop);
1478 }
1479 }
1480
1481 } else {
1482 /*
1483 * Process the node. Note that we do not remove the node from the stack, i.e., we
1484 * will peek it again. But the next time the node is marked as active, so we do not
1485 * execute this code again.
1486 */
1487 active.mark(current);
1488 for (Node successor : current.cfgSuccessors()) {
1489 if (active.isMarked(successor)) {
1490 /* Detected a cycle, i.e., a backward branch of a loop. */
1491 Loop loop = findOrCreateLoop(unorderedLoops, (MergeNode) successor);
1492 assert !loop.ends.contains(current);
1493 loop.ends.add((EndNode) current);
1494
1495 } else if (visited.isMarked(successor)) {
1496 /* Forward merge into a branch we are already exploring. */
1497
1498 } else {
1499 /* Forward branch to a node we have not seen yet. */
1500 visited.mark(successor);
1501 stack.push(successor);
1502 }
1503 }
1504 }
1505 }
1506 return orderedLoops;
1507 }
1508
1509 private Loop findOrCreateLoop(EconomicMap<MergeNode, Loop> unorderedLoops, MergeNode loopHeader) {
1510 assert methodScope.loopExplosionMerges.contains(loopHeader) : loopHeader;
1511 Loop loop = unorderedLoops.get(loopHeader);
1512 if (loop == null) {
1513 loop = new Loop();
1514 loop.header = loopHeader;
1515 unorderedLoops.put(loopHeader, loop);
1516 }
1517 return loop;
1518 }
1519
1520 private void findLoopExits(Loop loop) {
1521 /*
1522 * Backward marking of loop nodes: Starting with the known loop ends, we mark all nodes that
1523 * are reachable until we hit the loop begin. All successors of loop nodes that are not
1524 * marked as loop nodes themselves are exits of the loop. We mark all successors, and then
1525 * subtract the loop nodes, to find the exits.
1526 */
1527
1528 List<Node> possibleExits = new ArrayList<>();
1529 NodeBitMap visited = graph.createNodeBitMap();
1530 Deque<Node> stack = new ArrayDeque<>();
1531 for (EndNode loopEnd : loop.ends) {
1532 stack.push(loopEnd);
1533 visited.mark(loopEnd);
1534 }
1535
1536 while (!stack.isEmpty()) {
1537 Node current = stack.pop();
1538 if (current == loop.header) {
1539 continue;
1540 }
1541 if (!graph.isNew(methodScope.methodStartMark, current)) {
1542 /*
1543 * The current node is before the method that contains the exploded loop. The loop
1544 * must have a second entry point, i.e., it is an irreducible loop.
1545 */
1546 loop.irreducible = true;
1547 return;
1548 }
1549
1550 for (Node predecessor : current.cfgPredecessors()) {
1551 if (predecessor instanceof LoopExitNode) {
1552 /*
1553 * Inner loop. We do not need to mark every node of it, instead we just continue
1554 * marking at the loop header.
1555 */
1556 LoopBeginNode innerLoopBegin = ((LoopExitNode) predecessor).loopBegin();
1557 if (!visited.isMarked(innerLoopBegin)) {
1558 stack.push(innerLoopBegin);
1559 visited.mark(innerLoopBegin);
1560
1561 /*
1562 * All loop exits of the inner loop possibly need a LoopExit of our loop.
1563 * Because we are processing inner loops first, we are guaranteed to already
1564 * have all exits of the inner loop.
1565 */
1566 for (LoopExitNode exit : innerLoopBegin.loopExits()) {
1567 possibleExits.add(exit);
1568 }
1569 }
1570
1571 } else if (!visited.isMarked(predecessor)) {
1572 stack.push(predecessor);
1573 visited.mark(predecessor);
1574
1575 if (predecessor instanceof ControlSplitNode) {
1576 for (Node succ : predecessor.cfgSuccessors()) {
1577 /*
1578 * We would not need to mark the current node, and would not need to
1579 * mark visited nodes. But it is easier to just mark everything, since
1580 * we subtract all visited nodes in the end anyway. Note that at this
1581 * point we do not have the complete visited information, so we would
1582 * always mark too many possible exits.
1583 */
1584 possibleExits.add(succ);
1585 }
1586 }
1587 }
1588 }
1589 }
1590
1591 /*
1592 * Now we know all the actual loop exits. Ideally, we would insert LoopExit nodes for them.
1593 * However, a LoopExit needs a valid FrameState that captures the state at the point where
1594 * we exit the loop. During graph decoding, we create a FrameState for every exploded loop
1595 * iteration. We need to do a forward marking until we hit the next such point. This puts
1596 * some nodes into the loop that are actually not part of the loop.
1597 *
1598 * In some cases, we did not create a FrameState during graph decoding: when there was no
1599 * LoopExit in the original loop that we exploded. This happens for code paths that lead
1600 * immediately to a DeoptimizeNode.
1601 *
1602 * Both cases mimic the behavior of the BytecodeParser, which also puts more nodes than
1603 * necessary into a loop because it computes loop information based on bytecodes, before the
1604 * actual parsing.
1605 */
1606 for (Node succ : possibleExits) {
1607 if (!visited.contains(succ)) {
1608 stack.push(succ);
1609 visited.mark(succ);
1610 assert !methodScope.loopExplosionMerges.contains(succ);
1611 }
1612 }
1613
1614 while (!stack.isEmpty()) {
1615 Node current = stack.pop();
1616 assert visited.isMarked(current);
1617 assert current instanceof ControlSinkNode || current instanceof LoopEndNode || current.cfgSuccessors().iterator().hasNext() : "Must not reach a node that has not been decoded yet";
1618
1619 for (Node successor : current.cfgSuccessors()) {
1620 if (visited.isMarked(successor)) {
1621 /* Already processed this successor. */
1622
1623 } else if (methodScope.loopExplosionMerges.contains(successor)) {
1624 /*
1625 * We have a FrameState for the successor. The LoopExit will be inserted between
1626 * the current node and the successor node. Since the successor node is a
1627 * MergeNode, the current node mus be a AbstractEndNode with only that MergeNode
1628 * as the successor.
1629 */
1630 assert successor instanceof MergeNode;
1631 assert !loop.exits.contains(current);
1632 loop.exits.add((AbstractEndNode) current);
1633
1634 } else {
1635 /* Node we have not seen yet. */
1636 visited.mark(successor);
1637 stack.push(successor);
1638 }
1639 }
1640 }
1641 }
1642
1643 private void insertLoopNodes(Loop loop) {
1644 MergeNode merge = loop.header;
1645 FrameState stateAfter = merge.stateAfter().duplicate();
1646 FixedNode afterMerge = merge.next();
1647 merge.setNext(null);
1648 EndNode preLoopEnd = graph.add(new EndNode());
1649 LoopBeginNode loopBegin = graph.add(new LoopBeginNode());
1650
1651 merge.setNext(preLoopEnd);
1652 /* Add the single non-loop predecessor of the loop header. */
1653 loopBegin.addForwardEnd(preLoopEnd);
1654 loopBegin.setNext(afterMerge);
1655 loopBegin.setStateAfter(stateAfter);
1656
1657 /*
1658 * Phi functions of the original merge need to be split: inputs that come from forward edges
1659 * remain with the original phi function; inputs that come from backward edges are added to
1660 * new phi functions.
1661 */
1662 List<PhiNode> mergePhis = merge.phis().snapshot();
1663 List<PhiNode> loopBeginPhis = new ArrayList<>(mergePhis.size());
1664 for (int i = 0; i < mergePhis.size(); i++) {
1665 PhiNode mergePhi = mergePhis.get(i);
1666 PhiNode loopBeginPhi = graph.addWithoutUnique(new ValuePhiNode(mergePhi.stamp(NodeView.DEFAULT), loopBegin));
1667 mergePhi.replaceAtUsages(loopBeginPhi);
1668 /*
1669 * The first input of the new phi function is the original phi function, for the one
1670 * forward edge of the LoopBeginNode.
1671 */
1672 loopBeginPhi.addInput(mergePhi);
1673 loopBeginPhis.add(loopBeginPhi);
1674 }
1675
1676 for (EndNode endNode : loop.ends) {
1677 for (int i = 0; i < mergePhis.size(); i++) {
1678 PhiNode mergePhi = mergePhis.get(i);
1679 PhiNode loopBeginPhi = loopBeginPhis.get(i);
1680 loopBeginPhi.addInput(mergePhi.valueAt(endNode));
1681 }
1682
1683 merge.removeEnd(endNode);
1684 LoopEndNode loopEnd = graph.add(new LoopEndNode(loopBegin));
1685 endNode.replaceAndDelete(loopEnd);
1686 }
1687
1688 /*
1689 * Insert the LoopExit nodes (the easy part) and compute the FrameState for the new exits
1690 * (the difficult part).
1691 */
1692 for (AbstractEndNode exit : loop.exits) {
1693 AbstractMergeNode loopExplosionMerge = exit.merge();
1694 assert methodScope.loopExplosionMerges.contains(loopExplosionMerge);
1695
1696 LoopExitNode loopExit = graph.add(new LoopExitNode(loopBegin));
1697 exit.replaceAtPredecessor(loopExit);
1698 loopExit.setNext(exit);
1699 assignLoopExitState(loopExit, loopExplosionMerge, exit);
1700 }
1701 }
1702
1703 /**
1704 * During graph decoding, we create a FrameState for every exploded loop iteration. This is
1705 * mostly the state that we want, we only need to tweak it a little bit: we need to insert the
1706 * appropriate ProxyNodes for all values that are created inside the loop and that flow out of
1707 * the loop.
1708 */
1709 private void assignLoopExitState(LoopExitNode loopExit, AbstractMergeNode loopExplosionMerge, AbstractEndNode loopExplosionEnd) {
1710 FrameState oldState = loopExplosionMerge.stateAfter();
1711
1712 /* Collect all nodes that are in the FrameState at the LoopBegin. */
1713 EconomicSet<Node> loopBeginValues = EconomicSet.create(Equivalence.IDENTITY);
1714 for (FrameState state = loopExit.loopBegin().stateAfter(); state != null; state = state.outerFrameState()) {
1715 for (ValueNode value : state.values()) {
1716 if (value != null && !value.isConstant() && !loopExit.loopBegin().isPhiAtMerge(value)) {
1717 loopBeginValues.add(ProxyPlaceholder.unwrap(value));
1718 }
1719 }
1720 }
1721
1722 List<ValueNode> newValues = new ArrayList<>(oldState.values().size());
1723 for (ValueNode v : oldState.values()) {
1724 ValueNode value = v;
1725 ValueNode realValue = ProxyPlaceholder.unwrap(value);
1726
1727 /*
1728 * The LoopExit is inserted before the existing merge, i.e., separately for every branch
1729 * that leads to the merge. So for phi functions of the merge, we need to take the input
1730 * that corresponds to our branch.
1731 */
1732 if (realValue instanceof PhiNode && loopExplosionMerge.isPhiAtMerge(realValue)) {
1733 value = ((PhiNode) realValue).valueAt(loopExplosionEnd);
1734 realValue = ProxyPlaceholder.unwrap(value);
1735 }
1736
1737 if (realValue == null || realValue.isConstant() || loopBeginValues.contains(realValue) || !graph.isNew(methodScope.methodStartMark, realValue)) {
1738 newValues.add(realValue);
1739 } else {
1740 /*
1741 * The node is not in the FrameState of the LoopBegin, i.e., it is a value computed
1742 * inside the loop.
1743 */
1744 GraalError.guarantee(value instanceof ProxyPlaceholder && ((ProxyPlaceholder) value).proxyPoint == loopExplosionMerge,
1745 "Value flowing out of loop, but we are not prepared to insert a ProxyNode");
1746
1747 ProxyPlaceholder proxyPlaceholder = (ProxyPlaceholder) value;
1748 ValueProxyNode proxy = ProxyNode.forValue(proxyPlaceholder.value, loopExit, graph);
1749 proxyPlaceholder.setValue(proxy);
1750 newValues.add(proxy);
1751 }
1752 }
1753
1754 FrameState newState = new FrameState(oldState.outerFrameState(), oldState.getCode(), oldState.bci, newValues, oldState.localsSize(), oldState.stackSize(), oldState.rethrowException(),
1755 oldState.duringCall(), oldState.monitorIds(), oldState.virtualObjectMappings());
1756
1757 assert loopExit.stateAfter() == null;
1758 loopExit.setStateAfter(graph.add(newState));
1759 }
1760
1761 /**
1762 * Graal does not support irreducible loops (loops with more than one entry point). There are
1763 * two ways to make them reducible: 1) duplicate nodes (peel a loop iteration starting at the
1764 * second entry point until we reach the first entry point), or 2) insert a big outer loop
1765 * covering the whole method and build a state machine for the different loop entry points.
1766 * Since node duplication can lead to an exponential explosion of nodes in the worst case, we
1767 * use the second approach.
1768 *
1769 * We already did some preparations to insert a big outer loop:
1770 * {@link MethodScope#loopExplosionHead} is the loop header for the outer loop, and we ensured
1771 * that we have a {@link Loop} data object for it in {@link #irreducibleLoopHandler}.
1772 *
1773 * Now we need to insert the state machine. We have several implementation restrictions to make
1774 * that efficient:
1775 * <ul>
1776 * <li>There must be only one loop variable, i.e., one value that is different in the
1777 * {@link FrameState} of the different loop headers.</li>
1778 * <li>The loop variable must use the primitive {@code int} type, because Graal only has a
1779 * {@link IntegerSwitchNode switch node} for {@code int}.</li>
1780 * <li>The values of the loop variable that are merged are {@link PrimitiveConstant compile time
1781 * constants}.</li>
1782 * </ul>
1783 */
1784 private void handleIrreducibleLoop(Loop loop) {
1785 assert loop != irreducibleLoopHandler;
1786
1787 FrameState loopState = loop.header.stateAfter();
1788 FrameState explosionHeadState = irreducibleLoopHandler.header.stateAfter();
1789 assert loopState.outerFrameState() == explosionHeadState.outerFrameState();
1790 NodeInputList<ValueNode> loopValues = loopState.values();
1791 NodeInputList<ValueNode> explosionHeadValues = explosionHeadState.values();
1792 assert loopValues.size() == explosionHeadValues.size();
1793
1794 /*
1795 * Find the loop variable, and the value of the loop variable for our loop and the outermost
1796 * loop. There must be exactly one loop variable.
1797 */
1798 int loopVariableIndex = -1;
1799 ValueNode loopValue = null;
1800 ValueNode explosionHeadValue = null;
1801 for (int i = 0; i < loopValues.size(); i++) {
1802 ValueNode curLoopValue = loopValues.get(i);
1803 ValueNode curExplosionHeadValue = explosionHeadValues.get(i);
1804
1805 if (curLoopValue != curExplosionHeadValue) {
1806 if (loopVariableIndex != -1) {
1807 throw bailout("must have only one variable that is changed in loop. " + loopValue + " != " + explosionHeadValue + " and " + curLoopValue + " != " + curExplosionHeadValue);
1808 }
1809
1810 loopVariableIndex = i;
1811 loopValue = curLoopValue;
1812 explosionHeadValue = curExplosionHeadValue;
1813 }
1814 }
1815 assert loopVariableIndex != -1;
1816
1817 ValuePhiNode loopVariablePhi;
1818 SortedMap<Integer, AbstractBeginNode> dispatchTable = new TreeMap<>();
1819 AbstractBeginNode unreachableDefaultSuccessor;
1820 if (irreducibleLoopSwitch == null) {
1821 /*
1822 * This is the first irreducible loop. We need to build the initial state machine
1823 * (dispatch for the loop header of the outermost loop).
1824 */
1825 assert !irreducibleLoopHandler.header.isPhiAtMerge(explosionHeadValue);
1826 assert irreducibleLoopHandler.header.phis().isEmpty();
1827
1828 /* The new phi function for the loop variable. */
1829 loopVariablePhi = graph.addWithoutUnique(new ValuePhiNode(explosionHeadValue.stamp(NodeView.DEFAULT).unrestricted(), irreducibleLoopHandler.header));
1830 for (int i = 0; i < irreducibleLoopHandler.header.phiPredecessorCount(); i++) {
1831 loopVariablePhi.addInput(explosionHeadValue);
1832 }
1833
1834 /*
1835 * Build the new FrameState for the loop header. There is only once change in comparison
1836 * to the old FrameState: the loop variable is replaced with the phi function.
1837 */
1838 FrameState oldFrameState = explosionHeadState;
1839 List<ValueNode> newFrameStateValues = new ArrayList<>(explosionHeadValues.size());
1840 for (int i = 0; i < explosionHeadValues.size(); i++) {
1841 if (i == loopVariableIndex) {
1842 newFrameStateValues.add(loopVariablePhi);
1843 } else {
1844 newFrameStateValues.add(explosionHeadValues.get(i));
1845 }
1846 }
1847
1848 FrameState newFrameState = graph.add(
1849 new FrameState(oldFrameState.outerFrameState(), oldFrameState.getCode(), oldFrameState.bci, newFrameStateValues, oldFrameState.localsSize(),
1850 oldFrameState.stackSize(), oldFrameState.rethrowException(), oldFrameState.duringCall(), oldFrameState.monitorIds(),
1851 oldFrameState.virtualObjectMappings()));
1852 oldFrameState.replaceAtUsages(newFrameState);
1853
1854 /*
1855 * Disconnect the outermost loop header from its loop body, so that we can later on
1856 * insert the switch node. Collect dispatch information for the outermost loop.
1857 */
1858 FixedNode handlerNext = irreducibleLoopHandler.header.next();
1859 irreducibleLoopHandler.header.setNext(null);
1860 BeginNode handlerBegin = graph.add(new BeginNode());
1861 handlerBegin.setNext(handlerNext);
1862 dispatchTable.put(asInt(explosionHeadValue), handlerBegin);
1863
1864 /*
1865 * We know that there will always be a matching key in the switch. But Graal always
1866 * wants a default successor, so we build a dummy block that just deoptimizes.
1867 */
1868 unreachableDefaultSuccessor = graph.add(new BeginNode());
1869 DeoptimizeNode deopt = graph.add(new DeoptimizeNode(DeoptimizationAction.InvalidateRecompile, DeoptimizationReason.UnreachedCode));
1870 unreachableDefaultSuccessor.setNext(deopt);
1871
1872 } else {
1873 /*
1874 * This is the second or a subsequent irreducible loop, i.e., we already inserted a
1875 * switch node before. We re-create the dispatch state machine of that switch, so that
1876 * we can extend it with one more branch.
1877 */
1878 assert irreducibleLoopHandler.header.isPhiAtMerge(explosionHeadValue);
1879 assert irreducibleLoopHandler.header.phis().count() == 1 && irreducibleLoopHandler.header.phis().first() == explosionHeadValue;
1880 assert irreducibleLoopSwitch.value() == explosionHeadValue;
1881
1882 /* We can modify the phi function used by the old switch node. */
1883 loopVariablePhi = (ValuePhiNode) explosionHeadValue;
1884
1885 /*
1886 * We cannot modify the old switch node. Insert all information from the old switch node
1887 * into our temporary data structures for the new, larger, switch node.
1888 */
1889 for (int i = 0; i < irreducibleLoopSwitch.keyCount(); i++) {
1890 int key = irreducibleLoopSwitch.keyAt(i).asInt();
1891 dispatchTable.put(key, irreducibleLoopSwitch.successorAtKey(key));
1892 }
1893 unreachableDefaultSuccessor = irreducibleLoopSwitch.defaultSuccessor();
1894
1895 /* Unlink and delete the old switch node, we do not need it anymore. */
1896 assert irreducibleLoopHandler.header.next() == irreducibleLoopSwitch;
1897 irreducibleLoopHandler.header.setNext(null);
1898 irreducibleLoopSwitch.clearSuccessors();
1899 irreducibleLoopSwitch.safeDelete();
1900 }
1901
1902 /* Insert our loop into the dispatch state machine. */
1903 assert loop.header.phis().isEmpty();
1904 BeginNode dispatchBegin = graph.add(new BeginNode());
1905 EndNode dispatchEnd = graph.add(new EndNode());
1906 dispatchBegin.setNext(dispatchEnd);
1907 loop.header.addForwardEnd(dispatchEnd);
1908 int intLoopValue = asInt(loopValue);
1909 assert !dispatchTable.containsKey(intLoopValue);
1910 dispatchTable.put(intLoopValue, dispatchBegin);
1911
1912 /* Disconnect the ends of our loop and re-connect them to the outermost loop header. */
1913 for (EndNode end : loop.ends) {
1914 loop.header.removeEnd(end);
1915 irreducibleLoopHandler.ends.add(end);
1916 irreducibleLoopHandler.header.addForwardEnd(end);
1917 loopVariablePhi.addInput(loopValue);
1918 }
1919
1920 /* Build and insert the switch node. */
1921 irreducibleLoopSwitch = graph.add(createSwitch(loopVariablePhi, dispatchTable, unreachableDefaultSuccessor));
1922 irreducibleLoopHandler.header.setNext(irreducibleLoopSwitch);
1923 }
1924
1925 private static int asInt(ValueNode node) {
1926 if (!node.isConstant() || node.asJavaConstant().getJavaKind() != JavaKind.Int) {
1927 throw bailout("must have a loop variable of type int. " + node);
1928 }
1929 return node.asJavaConstant().asInt();
1930 }
1931
1932 private static RuntimeException bailout(String msg) {
1933 throw new PermanentBailoutException("Graal implementation restriction: Method with %s loop explosion %s", LoopExplosionKind.MERGE_EXPLODE, msg);
1934 }
1935
1936 private static IntegerSwitchNode createSwitch(ValuePhiNode switchedValue, SortedMap<Integer, AbstractBeginNode> dispatchTable, AbstractBeginNode defaultSuccessor) {
1937 int numKeys = dispatchTable.size();
1938 int numSuccessors = numKeys + 1;
1939
1940 AbstractBeginNode[] switchSuccessors = new AbstractBeginNode[numSuccessors];
1941 int[] switchKeys = new int[numKeys];
1942 double[] switchKeyProbabilities = new double[numSuccessors];
1943 int[] switchKeySuccessors = new int[numSuccessors];
1944
1945 int idx = 0;
1946 for (Map.Entry<Integer, AbstractBeginNode> entry : dispatchTable.entrySet()) {
1947 switchSuccessors[idx] = entry.getValue();
1948 switchKeys[idx] = entry.getKey();
1949 switchKeyProbabilities[idx] = 1d / numKeys;
1950 switchKeySuccessors[idx] = idx;
1951 idx++;
1952 }
1953 switchSuccessors[idx] = defaultSuccessor;
1954 /* We know the default branch is never going to be executed. */
1955 switchKeyProbabilities[idx] = 0;
1956 switchKeySuccessors[idx] = idx;
1957
1958 return new IntegerSwitchNode(switchedValue, switchSuccessors, switchKeys, switchKeyProbabilities, switchKeySuccessors);
1959 }
1960
1961 /**
1962 * Print information about irreducible loops, when enabled with -Dgraal.Log=IrreducibleLoops.
1963 */
1964 @SuppressWarnings("try")
1965 private void logIrreducibleLoops() {
1966 DebugContext debug = graph.getDebug();
1967 try (DebugContext.Scope s = debug.scope("IrreducibleLoops")) {
1968 if (debug.isLogEnabled(DebugContext.BASIC_LEVEL) && irreducibleLoopSwitch != null) {
1969 StringBuilder msg = new StringBuilder("Inserted state machine to remove irreducible loops. Dispatching to the following states: ");
1970 String sep = "";
1971 for (int i = 0; i < irreducibleLoopSwitch.keyCount(); i++) {
1972 msg.append(sep).append(irreducibleLoopSwitch.keyAt(i).asInt());
1973 sep = ", ";
1974 }
1975 debug.log(DebugContext.BASIC_LEVEL, "%s", msg);
1976 }
1977 }
1978 }
1979 }