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.lir.alloc.lsra;
26
27 import static jdk.vm.ci.code.ValueUtil.asRegister;
28 import static jdk.vm.ci.code.ValueUtil.asStackSlot;
29 import static jdk.vm.ci.code.ValueUtil.isRegister;
30 import static jdk.vm.ci.code.ValueUtil.isStackSlot;
31 import static org.graalvm.compiler.lir.LIRValueUtil.asVariable;
32 import static org.graalvm.compiler.lir.LIRValueUtil.isVariable;
33 import static org.graalvm.compiler.lir.debug.LIRGenerationDebugContext.getSourceForOperandFromDebugContext;
34
35 import java.util.ArrayDeque;
36 import java.util.ArrayList;
37 import java.util.BitSet;
38 import java.util.EnumSet;
39
40 import jdk.internal.vm.compiler.collections.EconomicSet;
41 import jdk.internal.vm.compiler.collections.Equivalence;
42 import org.graalvm.compiler.core.common.LIRKind;
43 import org.graalvm.compiler.core.common.PermanentBailoutException;
44 import org.graalvm.compiler.core.common.alloc.ComputeBlockOrder;
45 import org.graalvm.compiler.core.common.cfg.AbstractBlockBase;
46 import org.graalvm.compiler.core.common.util.BitMap2D;
47 import org.graalvm.compiler.debug.Assertions;
48 import org.graalvm.compiler.debug.DebugContext;
49 import org.graalvm.compiler.debug.GraalError;
50 import org.graalvm.compiler.debug.Indent;
51 import org.graalvm.compiler.lir.InstructionValueConsumer;
52 import org.graalvm.compiler.lir.LIRInstruction;
53 import org.graalvm.compiler.lir.LIRInstruction.OperandFlag;
54 import org.graalvm.compiler.lir.LIRInstruction.OperandMode;
55 import org.graalvm.compiler.lir.StandardOp.LoadConstantOp;
56 import org.graalvm.compiler.lir.StandardOp.ValueMoveOp;
57 import org.graalvm.compiler.lir.ValueConsumer;
58 import org.graalvm.compiler.lir.alloc.lsra.Interval.RegisterPriority;
59 import org.graalvm.compiler.lir.alloc.lsra.Interval.SpillState;
60 import org.graalvm.compiler.lir.alloc.lsra.LinearScan.BlockData;
61 import org.graalvm.compiler.lir.gen.LIRGenerationResult;
62 import org.graalvm.compiler.lir.phases.AllocationPhase.AllocationContext;
63
64 import jdk.vm.ci.code.Register;
65 import jdk.vm.ci.code.RegisterArray;
66 import jdk.vm.ci.code.StackSlot;
67 import jdk.vm.ci.code.TargetDescription;
68 import jdk.vm.ci.meta.AllocatableValue;
69 import jdk.vm.ci.meta.Constant;
70 import jdk.vm.ci.meta.JavaConstant;
71 import jdk.vm.ci.meta.Value;
72 import jdk.vm.ci.meta.ValueKind;
73
74 public class LinearScanLifetimeAnalysisPhase extends LinearScanAllocationPhase {
75
76 protected final LinearScan allocator;
77 protected final DebugContext debug;
78
79 /**
80 * @param linearScan
81 */
82 protected LinearScanLifetimeAnalysisPhase(LinearScan linearScan) {
83 allocator = linearScan;
84 debug = allocator.getDebug();
85 }
86
87 @Override
88 protected void run(TargetDescription target, LIRGenerationResult lirGenRes, AllocationContext context) {
89 numberInstructions();
90 debug.dump(DebugContext.VERBOSE_LEVEL, lirGenRes.getLIR(), "Before register allocation");
91 computeLocalLiveSets();
92 computeGlobalLiveSets();
93 buildIntervals(Assertions.detailedAssertionsEnabled(allocator.getOptions()));
94 }
95
96 /**
97 * Bit set for each variable that is contained in each loop.
98 */
99 private BitMap2D intervalInLoop;
100
101 boolean isIntervalInLoop(int interval, int loop) {
102 return intervalInLoop.at(interval, loop);
103 }
104
105 /**
106 * Numbers all instructions in all blocks. The numbering follows the
107 * {@linkplain ComputeBlockOrder linear scan order}.
108 */
109 protected void numberInstructions() {
110
111 allocator.initIntervals();
112
113 ValueConsumer setVariableConsumer = (value, mode, flags) -> {
114 if (isVariable(value)) {
115 allocator.getOrCreateInterval(asVariable(value));
116 }
117 };
118
119 // Assign IDs to LIR nodes and build a mapping, lirOps, from ID to LIRInstruction node.
120 int numInstructions = 0;
121 for (AbstractBlockBase<?> block : allocator.sortedBlocks()) {
122 numInstructions += allocator.getLIR().getLIRforBlock(block).size();
123 }
124
125 // initialize with correct length
126 allocator.initOpIdMaps(numInstructions);
127
128 int opId = 0;
129 int index = 0;
130 for (AbstractBlockBase<?> block : allocator.sortedBlocks()) {
131 allocator.initBlockData(block);
132
133 ArrayList<LIRInstruction> instructions = allocator.getLIR().getLIRforBlock(block);
134
135 int numInst = instructions.size();
136 for (int j = 0; j < numInst; j++) {
137 LIRInstruction op = instructions.get(j);
138 op.setId(opId);
139
140 allocator.putOpIdMaps(index, op, block);
141 assert allocator.instructionForId(opId) == op : "must match";
142
143 op.visitEachTemp(setVariableConsumer);
144 op.visitEachOutput(setVariableConsumer);
145
146 index++;
147 opId += 2; // numbering of lirOps by two
148 }
149 }
150 assert index == numInstructions : "must match";
151 assert (index << 1) == opId : "must match: " + (index << 1);
152 }
153
154 /**
155 * Computes local live sets (i.e. {@link BlockData#liveGen} and {@link BlockData#liveKill})
156 * separately for each block.
157 */
158 @SuppressWarnings("try")
159 void computeLocalLiveSets() {
160 int liveSize = allocator.liveSetSize();
161
162 intervalInLoop = new BitMap2D(allocator.operandSize(), allocator.numLoops());
163
164 try {
165 final BitSet liveGenScratch = new BitSet(liveSize);
166 final BitSet liveKillScratch = new BitSet(liveSize);
167 // iterate all blocks
168 for (final AbstractBlockBase<?> block : allocator.sortedBlocks()) {
169 try (Indent indent = debug.logAndIndent("compute local live sets for block %s", block)) {
170
171 liveGenScratch.clear();
172 liveKillScratch.clear();
173
174 ArrayList<LIRInstruction> instructions = allocator.getLIR().getLIRforBlock(block);
175 int numInst = instructions.size();
176
177 ValueConsumer useConsumer = (operand, mode, flags) -> {
178 if (isVariable(operand)) {
179 int operandNum = allocator.operandNumber(operand);
180 if (!liveKillScratch.get(operandNum)) {
181 liveGenScratch.set(operandNum);
182 if (debug.isLogEnabled()) {
183 debug.log("liveGen for operand %d(%s)", operandNum, operand);
184 }
185 }
186 if (block.getLoop() != null) {
187 intervalInLoop.setBit(operandNum, block.getLoop().getIndex());
188 }
189 }
190
191 if (allocator.detailedAsserts) {
192 verifyInput(block, liveKillScratch, operand);
193 }
194 };
195 ValueConsumer stateConsumer = (operand, mode, flags) -> {
196 if (LinearScan.isVariableOrRegister(operand)) {
197 int operandNum = allocator.operandNumber(operand);
198 if (!liveKillScratch.get(operandNum)) {
199 liveGenScratch.set(operandNum);
200 if (debug.isLogEnabled()) {
201 debug.log("liveGen in state for operand %d(%s)", operandNum, operand);
202 }
203 }
204 }
205 };
206 ValueConsumer defConsumer = (operand, mode, flags) -> {
207 if (isVariable(operand)) {
208 int varNum = allocator.operandNumber(operand);
209 liveKillScratch.set(varNum);
210 if (debug.isLogEnabled()) {
211 debug.log("liveKill for operand %d(%s)", varNum, operand);
212 }
213 if (block.getLoop() != null) {
214 intervalInLoop.setBit(varNum, block.getLoop().getIndex());
215 }
216 }
217
218 if (allocator.detailedAsserts) {
219 /*
220 * Fixed intervals are never live at block boundaries, so they need not
221 * be processed in live sets. Process them only in debug mode so that
222 * this can be checked
223 */
224 verifyTemp(liveKillScratch, operand);
225 }
226 };
227
228 // iterate all instructions of the block
229 for (int j = 0; j < numInst; j++) {
230 final LIRInstruction op = instructions.get(j);
231
232 try (Indent indent2 = debug.logAndIndent("handle op %d: %s", op.id(), op)) {
233 op.visitEachInput(useConsumer);
234 op.visitEachAlive(useConsumer);
235 /*
236 * Add uses of live locals from interpreter's point of view for proper
237 * debug information generation.
238 */
239 op.visitEachState(stateConsumer);
240 op.visitEachTemp(defConsumer);
241 op.visitEachOutput(defConsumer);
242 }
243 } // end of instruction iteration
244
245 BlockData blockSets = allocator.getBlockData(block);
246 blockSets.liveGen = trimClone(liveGenScratch);
247 blockSets.liveKill = trimClone(liveKillScratch);
248 // sticky size, will get non-sticky in computeGlobalLiveSets
249 blockSets.liveIn = new BitSet(0);
250 blockSets.liveOut = new BitSet(0);
251
252 if (debug.isLogEnabled()) {
253 debug.log("liveGen B%d %s", block.getId(), blockSets.liveGen);
254 debug.log("liveKill B%d %s", block.getId(), blockSets.liveKill);
255 }
256
257 }
258 } // end of block iteration
259 } catch (OutOfMemoryError oom) {
260 throw new PermanentBailoutException(oom, "Out-of-memory during live set allocation of size %d", liveSize);
261 }
262 }
263
264 private void verifyTemp(BitSet liveKill, Value operand) {
265 /*
266 * Fixed intervals are never live at block boundaries, so they need not be processed in live
267 * sets. Process them only in debug mode so that this can be checked
268 */
269 if (isRegister(operand)) {
270 if (allocator.isProcessed(operand)) {
271 liveKill.set(allocator.operandNumber(operand));
272 }
273 }
274 }
275
276 private void verifyInput(AbstractBlockBase<?> block, BitSet liveKill, Value operand) {
277 /*
278 * Fixed intervals are never live at block boundaries, so they need not be processed in live
279 * sets. This is checked by these assertions to be sure about it. The entry block may have
280 * incoming values in registers, which is ok.
281 */
282 if (isRegister(operand) && block != allocator.getLIR().getControlFlowGraph().getStartBlock()) {
283 if (allocator.isProcessed(operand)) {
284 assert liveKill.get(allocator.operandNumber(operand)) : "using fixed register " + asRegister(operand) + " that is not defined in this block " + block;
285 }
286 }
287 }
288
289 /**
290 * Performs a backward dataflow analysis to compute global live sets (i.e.
291 * {@link BlockData#liveIn} and {@link BlockData#liveOut}) for each block.
292 */
293 @SuppressWarnings("try")
294 protected void computeGlobalLiveSets() {
295 try (Indent indent = debug.logAndIndent("compute global live sets")) {
296 int numBlocks = allocator.blockCount();
297 boolean changeOccurred;
298 boolean changeOccurredInBlock;
299 int iterationCount = 0;
300 BitSet scratch = new BitSet(allocator.liveSetSize()); // scratch set for calculations
301
302 /*
303 * Perform a backward dataflow analysis to compute liveOut and liveIn for each block.
304 * The loop is executed until a fixpoint is reached (no changes in an iteration).
305 */
306 do {
307 changeOccurred = false;
308
309 try (Indent indent2 = debug.logAndIndent("new iteration %d", iterationCount)) {
310
311 // iterate all blocks in reverse order
312 for (int i = numBlocks - 1; i >= 0; i--) {
313 AbstractBlockBase<?> block = allocator.blockAt(i);
314 BlockData blockSets = allocator.getBlockData(block);
315
316 changeOccurredInBlock = false;
317
318 /*
319 * liveOut(block) is the union of liveIn(sux), for successors sux of block.
320 */
321 int n = block.getSuccessorCount();
322 if (n > 0) {
323 scratch.clear();
324 // block has successors
325 if (n > 0) {
326 for (AbstractBlockBase<?> successor : block.getSuccessors()) {
327 scratch.or(allocator.getBlockData(successor).liveIn);
328 }
329 }
330
331 if (!blockSets.liveOut.equals(scratch)) {
332 blockSets.liveOut = trimClone(scratch);
333
334 changeOccurred = true;
335 changeOccurredInBlock = true;
336 }
337 }
338
339 if (iterationCount == 0 || changeOccurredInBlock) {
340 /*
341 * liveIn(block) is the union of liveGen(block) with (liveOut(block) &
342 * !liveKill(block)).
343 *
344 * Note: liveIn has to be computed only in first iteration or if liveOut
345 * has changed!
346 *
347 * Note: liveIn set can only grow, never shrink. No need to clear it.
348 */
349 BitSet liveIn = blockSets.liveIn;
350 /*
351 * BitSet#or will call BitSet#ensureSize (since the bit set is of length
352 * 0 initially) and set sticky to false
353 */
354 liveIn.or(blockSets.liveOut);
355 liveIn.andNot(blockSets.liveKill);
356 liveIn.or(blockSets.liveGen);
357
358 liveIn.clone(); // trimToSize()
359
360 if (debug.isLogEnabled()) {
361 debug.log("block %d: livein = %s, liveout = %s", block.getId(), liveIn, blockSets.liveOut);
362 }
363 }
364 }
365 iterationCount++;
366
367 if (changeOccurred && iterationCount > 50) {
368 /*
369 * Very unlikely, should never happen: If it happens we cannot guarantee it
370 * won't happen again.
371 */
372 throw new PermanentBailoutException("too many iterations in computeGlobalLiveSets");
373 }
374 }
375 } while (changeOccurred);
376
377 if (Assertions.detailedAssertionsEnabled(allocator.getOptions())) {
378 verifyLiveness();
379 }
380
381 // check that the liveIn set of the first block is empty
382 AbstractBlockBase<?> startBlock = allocator.getLIR().getControlFlowGraph().getStartBlock();
383 if (allocator.getBlockData(startBlock).liveIn.cardinality() != 0) {
384 if (Assertions.detailedAssertionsEnabled(allocator.getOptions())) {
385 reportFailure(numBlocks);
386 }
387 // bailout if this occurs in product mode.
388 throw new GraalError("liveIn set of first block must be empty: " + allocator.getBlockData(startBlock).liveIn);
389 }
390 }
391 }
392
393 /**
394 * Creates a trimmed copy a bit set.
395 *
396 * {@link BitSet#clone()} cannot be used since it will not {@linkplain BitSet#trimToSize trim}
397 * the array if the bit set is {@linkplain BitSet#sizeIsSticky sticky}.
398 */
399 @SuppressWarnings("javadoc")
400 private static BitSet trimClone(BitSet set) {
401 BitSet trimmedSet = new BitSet(0); // zero-length words array, sticky
402 trimmedSet.or(set); // words size ensured to be words-in-use of set,
403 // also makes it non-sticky
404 return trimmedSet;
405 }
406
407 @SuppressWarnings("try")
408 protected void reportFailure(int numBlocks) {
409 try (DebugContext.Scope s = debug.forceLog()) {
410 try (Indent indent = debug.logAndIndent("report failure")) {
411
412 BitSet startBlockLiveIn = allocator.getBlockData(allocator.getLIR().getControlFlowGraph().getStartBlock()).liveIn;
413 try (Indent indent2 = debug.logAndIndent("Error: liveIn set of first block must be empty (when this fails, variables are used before they are defined):")) {
414 for (int operandNum = startBlockLiveIn.nextSetBit(0); operandNum >= 0; operandNum = startBlockLiveIn.nextSetBit(operandNum + 1)) {
415 Interval interval = allocator.intervalFor(operandNum);
416 if (interval != null) {
417 Value operand = interval.operand;
418 debug.log("var %d; operand=%s; node=%s", operandNum, operand, getSourceForOperandFromDebugContext(debug, operand));
419 } else {
420 debug.log("var %d; missing operand", operandNum);
421 }
422 }
423 }
424
425 // print some additional information to simplify debugging
426 for (int operandNum = startBlockLiveIn.nextSetBit(0); operandNum >= 0; operandNum = startBlockLiveIn.nextSetBit(operandNum + 1)) {
427 Interval interval = allocator.intervalFor(operandNum);
428 Value operand = null;
429 Object valueForOperandFromDebugContext = null;
430 if (interval != null) {
431 operand = interval.operand;
432 valueForOperandFromDebugContext = getSourceForOperandFromDebugContext(debug, operand);
433 }
434 try (Indent indent2 = debug.logAndIndent("---- Detailed information for var %d; operand=%s; node=%s ----", operandNum, operand, valueForOperandFromDebugContext)) {
435
436 ArrayDeque<AbstractBlockBase<?>> definedIn = new ArrayDeque<>();
437 EconomicSet<AbstractBlockBase<?>> usedIn = EconomicSet.create(Equivalence.IDENTITY);
438 for (AbstractBlockBase<?> block : allocator.sortedBlocks()) {
439 if (allocator.getBlockData(block).liveGen.get(operandNum)) {
440 usedIn.add(block);
441 try (Indent indent3 = debug.logAndIndent("used in block B%d", block.getId())) {
442 for (LIRInstruction ins : allocator.getLIR().getLIRforBlock(block)) {
443 try (Indent indent4 = debug.logAndIndent("%d: %s", ins.id(), ins)) {
444 ins.forEachState((liveStateOperand, mode, flags) -> {
445 debug.log("operand=%s", liveStateOperand);
446 return liveStateOperand;
447 });
448 }
449 }
450 }
451 }
452 if (allocator.getBlockData(block).liveKill.get(operandNum)) {
453 definedIn.add(block);
454 try (Indent indent3 = debug.logAndIndent("defined in block B%d", block.getId())) {
455 for (LIRInstruction ins : allocator.getLIR().getLIRforBlock(block)) {
456 debug.log("%d: %s", ins.id(), ins);
457 }
458 }
459 }
460 }
461
462 int[] hitCount = new int[numBlocks];
463
464 while (!definedIn.isEmpty()) {
465 AbstractBlockBase<?> block = definedIn.removeFirst();
466 usedIn.remove(block);
467 for (AbstractBlockBase<?> successor : block.getSuccessors()) {
468 if (successor.isLoopHeader()) {
469 if (!block.isLoopEnd()) {
470 definedIn.add(successor);
471 }
472 } else {
473 if (++hitCount[successor.getId()] == successor.getPredecessorCount()) {
474 definedIn.add(successor);
475 }
476 }
477 }
478 }
479 try (Indent indent3 = debug.logAndIndent("**** offending usages are in: ")) {
480 for (AbstractBlockBase<?> block : usedIn) {
481 debug.log("B%d", block.getId());
482 }
483 }
484 }
485 }
486 }
487 } catch (Throwable e) {
488 throw debug.handle(e);
489 }
490 }
491
492 protected void verifyLiveness() {
493 /*
494 * Check that fixed intervals are not live at block boundaries (live set must be empty at
495 * fixed intervals).
496 */
497 for (AbstractBlockBase<?> block : allocator.sortedBlocks()) {
498 for (int j = 0; j <= allocator.maxRegisterNumber(); j++) {
499 assert !allocator.getBlockData(block).liveIn.get(j) : "liveIn set of fixed register must be empty";
500 assert !allocator.getBlockData(block).liveOut.get(j) : "liveOut set of fixed register must be empty";
501 assert !allocator.getBlockData(block).liveGen.get(j) : "liveGen set of fixed register must be empty";
502 }
503 }
504 }
505
506 protected void addUse(AllocatableValue operand, int from, int to, RegisterPriority registerPriority, ValueKind<?> kind, boolean detailedAsserts) {
507 if (!allocator.isProcessed(operand)) {
508 return;
509 }
510
511 Interval interval = allocator.getOrCreateInterval(operand);
512 if (!kind.equals(LIRKind.Illegal)) {
513 interval.setKind(kind);
514 }
515
516 interval.addRange(from, to);
517
518 // Register use position at even instruction id.
519 interval.addUsePos(to & ~1, registerPriority, detailedAsserts);
520
521 if (debug.isLogEnabled()) {
522 debug.log("add use: %s, from %d to %d (%s)", interval, from, to, registerPriority.name());
523 }
524 }
525
526 protected void addTemp(AllocatableValue operand, int tempPos, RegisterPriority registerPriority, ValueKind<?> kind, boolean detailedAsserts) {
527 if (!allocator.isProcessed(operand)) {
528 return;
529 }
530
531 Interval interval = allocator.getOrCreateInterval(operand);
532 if (!kind.equals(LIRKind.Illegal)) {
533 interval.setKind(kind);
534 }
535
536 interval.addRange(tempPos, tempPos + 1);
537 interval.addUsePos(tempPos, registerPriority, detailedAsserts);
538 interval.addMaterializationValue(null);
539
540 if (debug.isLogEnabled()) {
541 debug.log("add temp: %s tempPos %d (%s)", interval, tempPos, RegisterPriority.MustHaveRegister.name());
542 }
543 }
544
545 protected void addDef(AllocatableValue operand, LIRInstruction op, RegisterPriority registerPriority, ValueKind<?> kind, boolean detailedAsserts) {
546 if (!allocator.isProcessed(operand)) {
547 return;
548 }
549 int defPos = op.id();
550
551 Interval interval = allocator.getOrCreateInterval(operand);
552 if (!kind.equals(LIRKind.Illegal)) {
553 interval.setKind(kind);
554 }
555
556 Range r = interval.first();
557 if (r.from <= defPos) {
558 /*
559 * Update the starting point (when a range is first created for a use, its start is the
560 * beginning of the current block until a def is encountered).
561 */
562 r.from = defPos;
563 interval.addUsePos(defPos, registerPriority, detailedAsserts);
564
565 } else {
566 /*
567 * Dead value - make vacuous interval also add register priority for dead intervals
568 */
569 interval.addRange(defPos, defPos + 1);
570 interval.addUsePos(defPos, registerPriority, detailedAsserts);
571 if (debug.isLogEnabled()) {
572 debug.log("Warning: def of operand %s at %d occurs without use", operand, defPos);
573 }
574 }
575
576 changeSpillDefinitionPos(op, operand, interval, defPos);
577 if (registerPriority == RegisterPriority.None && interval.spillState().ordinal() <= SpillState.StartInMemory.ordinal() && isStackSlot(operand)) {
578 // detection of method-parameters and roundfp-results
579 interval.setSpillState(SpillState.StartInMemory);
580 }
581 interval.addMaterializationValue(getMaterializedValue(op, operand, interval));
582
583 if (debug.isLogEnabled()) {
584 debug.log("add def: %s defPos %d (%s)", interval, defPos, registerPriority.name());
585 }
586 }
587
588 /**
589 * Optimizes moves related to incoming stack based arguments. The interval for the destination
590 * of such moves is assigned the stack slot (which is in the caller's frame) as its spill slot.
591 */
592 protected void handleMethodArguments(LIRInstruction op) {
593 if (ValueMoveOp.isValueMoveOp(op)) {
594 ValueMoveOp move = ValueMoveOp.asValueMoveOp(op);
595 if (optimizeMethodArgument(move.getInput())) {
596 StackSlot slot = asStackSlot(move.getInput());
597 if (Assertions.detailedAssertionsEnabled(allocator.getOptions())) {
598 assert op.id() > 0 : "invalid id";
599 assert allocator.blockForId(op.id()).getPredecessorCount() == 0 : "move from stack must be in first block";
600 assert isVariable(move.getResult()) : "result of move must be a variable";
601
602 if (debug.isLogEnabled()) {
603 debug.log("found move from stack slot %s to %s", slot, move.getResult());
604 }
605 }
606
607 Interval interval = allocator.intervalFor(move.getResult());
608 interval.setSpillSlot(slot);
609 interval.assignLocation(slot);
610 }
611 }
612 }
613
614 protected void addRegisterHint(final LIRInstruction op, final Value targetValue, OperandMode mode, EnumSet<OperandFlag> flags, final boolean hintAtDef) {
615 if (flags.contains(OperandFlag.HINT) && LinearScan.isVariableOrRegister(targetValue)) {
616
617 op.forEachRegisterHint(targetValue, mode, (registerHint, valueMode, valueFlags) -> {
618 if (LinearScan.isVariableOrRegister(registerHint)) {
619 Interval from = allocator.getOrCreateInterval((AllocatableValue) registerHint);
620 Interval to = allocator.getOrCreateInterval((AllocatableValue) targetValue);
621
622 /* hints always point from def to use */
623 if (hintAtDef) {
624 to.setLocationHint(from);
625 } else {
626 from.setLocationHint(to);
627 }
628 if (debug.isLogEnabled()) {
629 debug.log("operation at opId %d: added hint from interval %d to %d", op.id(), from.operandNumber, to.operandNumber);
630 }
631
632 return registerHint;
633 }
634 return null;
635 });
636 }
637 }
638
639 /**
640 * Eliminates moves from register to stack if the stack slot is known to be correct.
641 *
642 * @param op
643 * @param operand
644 */
645 protected void changeSpillDefinitionPos(LIRInstruction op, AllocatableValue operand, Interval interval, int defPos) {
646 assert interval.isSplitParent() : "can only be called for split parents";
647
648 switch (interval.spillState()) {
649 case NoDefinitionFound:
650 assert interval.spillDefinitionPos() == -1 : "must no be set before";
651 interval.setSpillDefinitionPos(defPos);
652 interval.setSpillState(SpillState.NoSpillStore);
653 break;
654
655 case NoSpillStore:
656 assert defPos <= interval.spillDefinitionPos() : "positions are processed in reverse order when intervals are created";
657 if (defPos < interval.spillDefinitionPos() - 2) {
658 // second definition found, so no spill optimization possible for this interval
659 interval.setSpillState(SpillState.NoOptimization);
660 } else {
661 // two consecutive definitions (because of two-operand LIR form)
662 assert allocator.blockForId(defPos) == allocator.blockForId(interval.spillDefinitionPos()) : "block must be equal";
663 }
664 break;
665
666 case NoOptimization:
667 // nothing to do
668 break;
669
670 default:
671 throw GraalError.shouldNotReachHere("other states not allowed at this time");
672 }
673 }
674
675 private static boolean optimizeMethodArgument(Value value) {
676 /*
677 * Object method arguments that are passed on the stack are currently not optimized because
678 * this requires that the runtime visits method arguments during stack walking.
679 */
680 return isStackSlot(value) && asStackSlot(value).isInCallerFrame() && LIRKind.isValue(value);
681 }
682
683 /**
684 * Determines the register priority for an instruction's output/result operand.
685 */
686 protected RegisterPriority registerPriorityOfOutputOperand(LIRInstruction op) {
687 if (ValueMoveOp.isValueMoveOp(op)) {
688 ValueMoveOp move = ValueMoveOp.asValueMoveOp(op);
689 if (optimizeMethodArgument(move.getInput())) {
690 return RegisterPriority.None;
691 }
692 }
693
694 // all other operands require a register
695 return RegisterPriority.MustHaveRegister;
696 }
697
698 /**
699 * Determines the priority which with an instruction's input operand will be allocated a
700 * register.
701 */
702 protected static RegisterPriority registerPriorityOfInputOperand(EnumSet<OperandFlag> flags) {
703 if (flags.contains(OperandFlag.STACK)) {
704 return RegisterPriority.ShouldHaveRegister;
705 }
706 // all other operands require a register
707 return RegisterPriority.MustHaveRegister;
708 }
709
710 @SuppressWarnings("try")
711 protected void buildIntervals(boolean detailedAsserts) {
712
713 try (Indent indent = debug.logAndIndent("build intervals")) {
714 InstructionValueConsumer outputConsumer = (op, operand, mode, flags) -> {
715 if (LinearScan.isVariableOrRegister(operand)) {
716 addDef((AllocatableValue) operand, op, registerPriorityOfOutputOperand(op), operand.getValueKind(), detailedAsserts);
717 addRegisterHint(op, operand, mode, flags, true);
718 }
719 };
720
721 InstructionValueConsumer tempConsumer = (op, operand, mode, flags) -> {
722 if (LinearScan.isVariableOrRegister(operand)) {
723 addTemp((AllocatableValue) operand, op.id(), RegisterPriority.MustHaveRegister, operand.getValueKind(), detailedAsserts);
724 addRegisterHint(op, operand, mode, flags, false);
725 }
726 };
727
728 InstructionValueConsumer aliveConsumer = (op, operand, mode, flags) -> {
729 if (LinearScan.isVariableOrRegister(operand)) {
730 RegisterPriority p = registerPriorityOfInputOperand(flags);
731 int opId = op.id();
732 int blockFrom = allocator.getFirstLirInstructionId((allocator.blockForId(opId)));
733 addUse((AllocatableValue) operand, blockFrom, opId + 1, p, operand.getValueKind(), detailedAsserts);
734 addRegisterHint(op, operand, mode, flags, false);
735 }
736 };
737
738 InstructionValueConsumer inputConsumer = (op, operand, mode, flags) -> {
739 if (LinearScan.isVariableOrRegister(operand)) {
740 int opId = op.id();
741 int blockFrom = allocator.getFirstLirInstructionId((allocator.blockForId(opId)));
742 RegisterPriority p = registerPriorityOfInputOperand(flags);
743 addUse((AllocatableValue) operand, blockFrom, opId, p, operand.getValueKind(), detailedAsserts);
744 addRegisterHint(op, operand, mode, flags, false);
745 }
746 };
747
748 InstructionValueConsumer stateProc = (op, operand, mode, flags) -> {
749 if (LinearScan.isVariableOrRegister(operand)) {
750 int opId = op.id();
751 int blockFrom = allocator.getFirstLirInstructionId((allocator.blockForId(opId)));
752 addUse((AllocatableValue) operand, blockFrom, opId + 1, RegisterPriority.None, operand.getValueKind(), detailedAsserts);
753 }
754 };
755
756 // create a list with all caller-save registers (cpu, fpu, xmm)
757 RegisterArray callerSaveRegs = allocator.getRegisterAllocationConfig().getRegisterConfig().getCallerSaveRegisters();
758
759 // iterate all blocks in reverse order
760 for (int i = allocator.blockCount() - 1; i >= 0; i--) {
761
762 AbstractBlockBase<?> block = allocator.blockAt(i);
763 try (Indent indent2 = debug.logAndIndent("handle block %d", block.getId())) {
764
765 ArrayList<LIRInstruction> instructions = allocator.getLIR().getLIRforBlock(block);
766 final int blockFrom = allocator.getFirstLirInstructionId(block);
767 int blockTo = allocator.getLastLirInstructionId(block);
768
769 assert blockFrom == instructions.get(0).id();
770 assert blockTo == instructions.get(instructions.size() - 1).id();
771
772 // Update intervals for operands live at the end of this block;
773 BitSet live = allocator.getBlockData(block).liveOut;
774 for (int operandNum = live.nextSetBit(0); operandNum >= 0; operandNum = live.nextSetBit(operandNum + 1)) {
775 assert live.get(operandNum) : "should not stop here otherwise";
776 AllocatableValue operand = allocator.intervalFor(operandNum).operand;
777 if (debug.isLogEnabled()) {
778 debug.log("live in %d: %s", operandNum, operand);
779 }
780
781 addUse(operand, blockFrom, blockTo + 2, RegisterPriority.None, LIRKind.Illegal, detailedAsserts);
782
783 /*
784 * Add special use positions for loop-end blocks when the interval is used
785 * anywhere inside this loop. It's possible that the block was part of a
786 * non-natural loop, so it might have an invalid loop index.
787 */
788 if (block.isLoopEnd() && block.getLoop() != null && isIntervalInLoop(operandNum, block.getLoop().getIndex())) {
789 allocator.intervalFor(operandNum).addUsePos(blockTo + 1, RegisterPriority.LiveAtLoopEnd, detailedAsserts);
790 }
791 }
792
793 /*
794 * Iterate all instructions of the block in reverse order. definitions of
795 * intervals are processed before uses.
796 */
797 for (int j = instructions.size() - 1; j >= 0; j--) {
798 final LIRInstruction op = instructions.get(j);
799 final int opId = op.id();
800
801 try (Indent indent3 = debug.logAndIndent("handle inst %d: %s", opId, op)) {
802
803 // add a temp range for each register if operation destroys
804 // caller-save registers
805 if (op.destroysCallerSavedRegisters()) {
806 for (Register r : callerSaveRegs) {
807 if (allocator.attributes(r).isAllocatable()) {
808 addTemp(r.asValue(), opId, RegisterPriority.None, LIRKind.Illegal, detailedAsserts);
809 }
810 }
811 if (debug.isLogEnabled()) {
812 debug.log("operation destroys all caller-save registers");
813 }
814 }
815
816 op.visitEachOutput(outputConsumer);
817 op.visitEachTemp(tempConsumer);
818 op.visitEachAlive(aliveConsumer);
819 op.visitEachInput(inputConsumer);
820
821 /*
822 * Add uses of live locals from interpreter's point of view for proper
823 * debug information generation. Treat these operands as temp values (if
824 * the live range is extended to a call site, the value would be in a
825 * register at the call otherwise).
826 */
827 op.visitEachState(stateProc);
828
829 // special steps for some instructions (especially moves)
830 handleMethodArguments(op);
831
832 }
833
834 } // end of instruction iteration
835 }
836 } // end of block iteration
837
838 /*
839 * Add the range [0, 1] to all fixed intervals. the register allocator need not handle
840 * unhandled fixed intervals.
841 */
842 for (Interval interval : allocator.intervals()) {
843 if (interval != null && isRegister(interval.operand)) {
844 interval.addRange(0, 1);
845 }
846 }
847 }
848 }
849
850 /**
851 * Returns a value for a interval definition, which can be used for re-materialization.
852 *
853 * @param op An instruction which defines a value
854 * @param operand The destination operand of the instruction
855 * @param interval The interval for this defined value.
856 * @return Returns the value which is moved to the instruction and which can be reused at all
857 * reload-locations in case the interval of this instruction is spilled. Currently this
858 * can only be a {@link JavaConstant}.
859 */
860 protected Constant getMaterializedValue(LIRInstruction op, Value operand, Interval interval) {
861 if (LoadConstantOp.isLoadConstantOp(op)) {
862 LoadConstantOp move = LoadConstantOp.asLoadConstantOp(op);
863
864 if (!allocator.neverSpillConstants()) {
865 /*
866 * Check if the interval has any uses which would accept an stack location (priority
867 * == ShouldHaveRegister). Rematerialization of such intervals can result in a
868 * degradation, because rematerialization always inserts a constant load, even if
869 * the value is not needed in a register.
870 */
871 Interval.UsePosList usePosList = interval.usePosList();
872 int numUsePos = usePosList.size();
873 for (int useIdx = 0; useIdx < numUsePos; useIdx++) {
874 Interval.RegisterPriority priority = usePosList.registerPriority(useIdx);
875 if (priority == Interval.RegisterPriority.ShouldHaveRegister) {
876 return null;
877 }
878 }
879 }
880 return move.getConstant();
881 }
882 return null;
883 }
884 }