1 /*
2 * Copyright (c) 2009, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 package org.graalvm.compiler.lir.alloc.lsra;
24
25 import static jdk.vm.ci.code.ValueUtil.asRegister;
26 import static jdk.vm.ci.code.ValueUtil.isIllegal;
27 import static jdk.vm.ci.code.ValueUtil.isRegister;
28
29 import java.util.ArrayList;
30
31 import org.graalvm.compiler.core.common.LIRKind;
32 import org.graalvm.compiler.debug.Debug;
33 import org.graalvm.compiler.debug.DebugCounter;
34 import org.graalvm.compiler.debug.GraalError;
35 import org.graalvm.compiler.debug.Indent;
36 import org.graalvm.compiler.lir.LIRInsertionBuffer;
37 import org.graalvm.compiler.lir.LIRInstruction;
38 import org.graalvm.compiler.lir.LIRValueUtil;
39 import org.graalvm.compiler.lir.gen.LIRGenerationResult;
40 import org.graalvm.util.Equivalence;
41 import org.graalvm.util.EconomicSet;
42
43 import jdk.vm.ci.meta.AllocatableValue;
44 import jdk.vm.ci.meta.Constant;
45 import jdk.vm.ci.meta.Value;
46
47 /**
48 */
49 public class MoveResolver {
50
51 private static final DebugCounter cycleBreakingSlotsAllocated = Debug.counter("LSRA[cycleBreakingSlotsAllocated]");
52
53 private final LinearScan allocator;
54
55 private int insertIdx;
56 private LIRInsertionBuffer insertionBuffer; // buffer where moves are inserted
57
58 private final ArrayList<Interval> mappingFrom;
59 private final ArrayList<Constant> mappingFromOpr;
60 private final ArrayList<Interval> mappingTo;
61 private boolean multipleReadsAllowed;
62 private final int[] registerBlocked;
63
64 private final LIRGenerationResult res;
65
66 protected void setValueBlocked(Value location, int direction) {
67 assert direction == 1 || direction == -1 : "out of bounds";
68 if (isRegister(location)) {
69 registerBlocked[asRegister(location).number] += direction;
70 } else {
71 throw GraalError.shouldNotReachHere("unhandled value " + location);
72 }
73 }
74
75 protected Interval getMappingFrom(int i) {
76 return mappingFrom.get(i);
77 }
78
79 protected int mappingFromSize() {
80 return mappingFrom.size();
81 }
82
83 protected int valueBlocked(Value location) {
84 if (isRegister(location)) {
85 return registerBlocked[asRegister(location).number];
86 }
87 throw GraalError.shouldNotReachHere("unhandled value " + location);
88 }
89
90 void setMultipleReadsAllowed() {
91 multipleReadsAllowed = true;
92 }
93
94 protected boolean areMultipleReadsAllowed() {
95 return multipleReadsAllowed;
96 }
97
98 boolean hasMappings() {
99 return mappingFrom.size() > 0;
100 }
101
102 protected LinearScan getAllocator() {
103 return allocator;
104 }
105
106 protected MoveResolver(LinearScan allocator) {
107 this.allocator = allocator;
108 this.multipleReadsAllowed = false;
109 this.mappingFrom = new ArrayList<>(8);
110 this.mappingFromOpr = new ArrayList<>(8);
111 this.mappingTo = new ArrayList<>(8);
112 this.insertIdx = -1;
113 this.insertionBuffer = new LIRInsertionBuffer();
114 this.registerBlocked = new int[allocator.getRegisters().size()];
115 this.res = allocator.getLIRGenerationResult();
116 }
117
118 protected boolean checkEmpty() {
119 assert mappingFrom.size() == 0 && mappingFromOpr.size() == 0 && mappingTo.size() == 0 : "list must be empty before and after processing";
120 for (int i = 0; i < getAllocator().getRegisters().size(); i++) {
121 assert registerBlocked[i] == 0 : "register map must be empty before and after processing";
122 }
123 checkMultipleReads();
124 return true;
125 }
126
127 protected void checkMultipleReads() {
128 assert !areMultipleReadsAllowed() : "must have default value";
129 }
130
131 private boolean verifyBeforeResolve() {
132 assert mappingFrom.size() == mappingFromOpr.size() : "length must be equal";
133 assert mappingFrom.size() == mappingTo.size() : "length must be equal";
134 assert insertIdx != -1 : "insert position not set";
135
136 int i;
137 int j;
138 if (!areMultipleReadsAllowed()) {
139 for (i = 0; i < mappingFrom.size(); i++) {
140 for (j = i + 1; j < mappingFrom.size(); j++) {
141 assert mappingFrom.get(i) == null || mappingFrom.get(i) != mappingFrom.get(j) : "cannot read from same interval twice";
142 }
143 }
144 }
145
146 for (i = 0; i < mappingTo.size(); i++) {
147 for (j = i + 1; j < mappingTo.size(); j++) {
148 assert mappingTo.get(i) != mappingTo.get(j) : "cannot write to same interval twice";
149 }
150 }
151
152 EconomicSet<Value> usedRegs = EconomicSet.create(Equivalence.DEFAULT);
153 if (!areMultipleReadsAllowed()) {
154 for (i = 0; i < mappingFrom.size(); i++) {
155 Interval interval = mappingFrom.get(i);
156 if (interval != null && !isIllegal(interval.location())) {
157 boolean unique = usedRegs.add(interval.location());
158 assert unique : "cannot read from same register twice";
159 }
160 }
161 }
162
163 usedRegs.clear();
164 for (i = 0; i < mappingTo.size(); i++) {
165 Interval interval = mappingTo.get(i);
166 if (isIllegal(interval.location())) {
167 // After insertion the location may become illegal, so don't check it since multiple
168 // intervals might be illegal.
169 continue;
170 }
171 boolean unique = usedRegs.add(interval.location());
172 assert unique : "cannot write to same register twice";
173 }
174
175 verifyStackSlotMapping();
176
177 return true;
178 }
179
180 protected void verifyStackSlotMapping() {
181 EconomicSet<Value> usedRegs = EconomicSet.create(Equivalence.DEFAULT);
182 for (int i = 0; i < mappingFrom.size(); i++) {
183 Interval interval = mappingFrom.get(i);
184 if (interval != null && !isRegister(interval.location())) {
185 usedRegs.add(interval.location());
186 }
187 }
188 for (int i = 0; i < mappingTo.size(); i++) {
189 Interval interval = mappingTo.get(i);
190 assert !usedRegs.contains(interval.location()) ||
191 checkIntervalLocation(mappingFrom.get(i), interval, mappingFromOpr.get(i)) : "stack slots used in mappingFrom must be disjoint to mappingTo";
192 }
193 }
194
195 private static boolean checkIntervalLocation(Interval from, Interval to, Constant fromOpr) {
196 if (from == null) {
197 return fromOpr != null;
198 } else {
199 return to.location().equals(from.location());
200 }
201 }
202
203 // mark assignedReg and assignedRegHi of the interval as blocked
204 private void blockRegisters(Interval interval) {
205 Value location = interval.location();
206 if (mightBeBlocked(location)) {
207 assert areMultipleReadsAllowed() || valueBlocked(location) == 0 : "location already marked as used: " + location;
208 int direction = 1;
209 setValueBlocked(location, direction);
210 Debug.log("block %s", location);
211 }
212 }
213
214 // mark assignedReg and assignedRegHi of the interval as unblocked
215 private void unblockRegisters(Interval interval) {
216 Value location = interval.location();
217 if (mightBeBlocked(location)) {
218 assert valueBlocked(location) > 0 : "location already marked as unused: " + location;
219 setValueBlocked(location, -1);
220 Debug.log("unblock %s", location);
221 }
222 }
223
224 /**
225 * Checks if the {@linkplain Interval#location() location} of {@code to} is not blocked or is
226 * only blocked by {@code from}.
227 */
228 private boolean safeToProcessMove(Interval from, Interval to) {
229 Value fromReg = from != null ? from.location() : null;
230
231 Value location = to.location();
232 if (mightBeBlocked(location)) {
233 if ((valueBlocked(location) > 1 || (valueBlocked(location) == 1 && !isMoveToSelf(fromReg, location)))) {
234 return false;
235 }
236 }
237
238 return true;
239 }
240
241 protected boolean isMoveToSelf(Value from, Value to) {
242 assert to != null;
243 if (to.equals(from)) {
244 return true;
245 }
246 if (from != null && isRegister(from) && isRegister(to) && asRegister(from).equals(asRegister(to))) {
247 assert LIRKind.verifyMoveKinds(to.getValueKind(), from.getValueKind(), allocator.getRegisterAllocationConfig()) : String.format("Same register but Kind mismatch %s <- %s", to, from);
248 return true;
249 }
250 return false;
251 }
252
253 protected boolean mightBeBlocked(Value location) {
254 return isRegister(location);
255 }
256
257 private void createInsertionBuffer(ArrayList<LIRInstruction> list) {
258 assert !insertionBuffer.initialized() : "overwriting existing buffer";
259 insertionBuffer.init(list);
260 }
261
262 private void appendInsertionBuffer() {
263 if (insertionBuffer.initialized()) {
264 insertionBuffer.finish();
265 }
266 assert !insertionBuffer.initialized() : "must be uninitialized now";
267
268 insertIdx = -1;
269 }
270
271 private LIRInstruction insertMove(Interval fromInterval, Interval toInterval) {
272 assert !fromInterval.operand.equals(toInterval.operand) : "from and to interval equal: " + fromInterval;
273 assert LIRKind.verifyMoveKinds(toInterval.kind(), fromInterval.kind(), allocator.getRegisterAllocationConfig()) : "move between different types";
274 assert insertIdx != -1 : "must setup insert position first";
275
276 LIRInstruction move = createMove(fromInterval.operand, toInterval.operand, fromInterval.location(), toInterval.location());
277 insertionBuffer.append(insertIdx, move);
278
279 if (Debug.isLogEnabled()) {
280 Debug.log("insert move from %s to %s at %d", fromInterval, toInterval, insertIdx);
281 }
282 return move;
283 }
284
285 /**
286 * @param fromOpr {@link Interval#operand operand} of the {@code from} interval
287 * @param toOpr {@link Interval#operand operand} of the {@code to} interval
288 * @param fromLocation {@link Interval#location() location} of the {@code to} interval
289 * @param toLocation {@link Interval#location() location} of the {@code to} interval
290 */
291 protected LIRInstruction createMove(AllocatableValue fromOpr, AllocatableValue toOpr, AllocatableValue fromLocation, AllocatableValue toLocation) {
292 return getAllocator().getSpillMoveFactory().createMove(toOpr, fromOpr);
293 }
294
295 private LIRInstruction insertMove(Constant fromOpr, Interval toInterval) {
296 assert insertIdx != -1 : "must setup insert position first";
297
298 AllocatableValue toOpr = toInterval.operand;
299 LIRInstruction move = getAllocator().getSpillMoveFactory().createLoad(toOpr, fromOpr);
300 insertionBuffer.append(insertIdx, move);
301
302 if (Debug.isLogEnabled()) {
303 Debug.log("insert move from value %s to %s at %d", fromOpr, toInterval, insertIdx);
304 }
305 return move;
306 }
307
308 @SuppressWarnings("try")
309 private void resolveMappings() {
310 try (Indent indent = Debug.logAndIndent("resolveMapping")) {
311 assert verifyBeforeResolve();
312 if (Debug.isLogEnabled()) {
313 printMapping();
314 }
315
316 // Block all registers that are used as input operands of a move.
317 // When a register is blocked, no move to this register is emitted.
318 // This is necessary for detecting cycles in moves.
319 int i;
320 for (i = mappingFrom.size() - 1; i >= 0; i--) {
321 Interval fromInterval = mappingFrom.get(i);
322 if (fromInterval != null) {
323 blockRegisters(fromInterval);
324 }
325 }
326
327 ArrayList<AllocatableValue> busySpillSlots = null;
328 while (mappingFrom.size() > 0) {
329 boolean processedInterval = false;
330
331 int spillCandidate = -1;
332 for (i = mappingFrom.size() - 1; i >= 0; i--) {
333 Interval fromInterval = mappingFrom.get(i);
334 Interval toInterval = mappingTo.get(i);
335
336 if (safeToProcessMove(fromInterval, toInterval)) {
337 // this interval can be processed because target is free
338 final LIRInstruction move;
339 if (fromInterval != null) {
340 move = insertMove(fromInterval, toInterval);
341 unblockRegisters(fromInterval);
342 } else {
343 move = insertMove(mappingFromOpr.get(i), toInterval);
344 }
345 move.setComment(res, "MoveResolver resolve mapping");
346 if (LIRValueUtil.isStackSlotValue(toInterval.location())) {
347 if (busySpillSlots == null) {
348 busySpillSlots = new ArrayList<>(2);
349 }
350 busySpillSlots.add(toInterval.location());
351 }
352 mappingFrom.remove(i);
353 mappingFromOpr.remove(i);
354 mappingTo.remove(i);
355
356 processedInterval = true;
357 } else if (fromInterval != null && isRegister(fromInterval.location()) &&
358 (busySpillSlots == null || !busySpillSlots.contains(fromInterval.spillSlot()))) {
359 // this interval cannot be processed now because target is not free
360 // it starts in a register, so it is a possible candidate for spilling
361 spillCandidate = i;
362 }
363 }
364
365 if (!processedInterval) {
366 breakCycle(spillCandidate);
367 }
368 }
369 }
370
371 // reset to default value
372 multipleReadsAllowed = false;
373
374 // check that all intervals have been processed
375 assert checkEmpty();
376 }
377
378 protected void breakCycle(int spillCandidate) {
379 // no move could be processed because there is a cycle in the move list
380 // (e.g. r1 . r2, r2 . r1), so one interval must be spilled to memory
381 assert spillCandidate != -1 : "no interval in register for spilling found";
382
383 // create a new spill interval and assign a stack slot to it
384 Interval fromInterval = mappingFrom.get(spillCandidate);
385 // do not allocate a new spill slot for temporary interval, but
386 // use spill slot assigned to fromInterval. Otherwise moves from
387 // one stack slot to another can happen (not allowed by LIRAssembler
388 AllocatableValue spillSlot = fromInterval.spillSlot();
389 if (spillSlot == null) {
390 spillSlot = getAllocator().getFrameMapBuilder().allocateSpillSlot(fromInterval.kind());
391 fromInterval.setSpillSlot(spillSlot);
392 cycleBreakingSlotsAllocated.increment();
393 }
394 spillInterval(spillCandidate, fromInterval, spillSlot);
395 }
396
397 protected void spillInterval(int spillCandidate, Interval fromInterval, AllocatableValue spillSlot) {
398 assert mappingFrom.get(spillCandidate).equals(fromInterval);
399 Interval spillInterval = getAllocator().createDerivedInterval(fromInterval);
400 spillInterval.setKind(fromInterval.kind());
401
402 // add a dummy range because real position is difficult to calculate
403 // Note: this range is a special case when the integrity of the allocation is
404 // checked
405 spillInterval.addRange(1, 2);
406
407 spillInterval.assignLocation(spillSlot);
408
409 if (Debug.isLogEnabled()) {
410 Debug.log("created new Interval for spilling: %s", spillInterval);
411 }
412 blockRegisters(spillInterval);
413
414 // insert a move from register to stack and update the mapping
415 LIRInstruction move = insertMove(fromInterval, spillInterval);
416 mappingFrom.set(spillCandidate, spillInterval);
417 unblockRegisters(fromInterval);
418 move.setComment(res, "MoveResolver break cycle");
419 }
420
421 @SuppressWarnings("try")
422 private void printMapping() {
423 try (Indent indent = Debug.logAndIndent("Mapping")) {
424 for (int i = mappingFrom.size() - 1; i >= 0; i--) {
425 Interval fromInterval = mappingFrom.get(i);
426 Interval toInterval = mappingTo.get(i);
427 String from;
428 Value to = toInterval.location();
429 if (fromInterval == null) {
430 from = mappingFromOpr.get(i).toString();
431 } else {
432 from = fromInterval.location().toString();
433 }
434 Debug.log("move %s <- %s", from, to);
435 }
436 }
437 }
438
439 void setInsertPosition(ArrayList<LIRInstruction> insertList, int insertIdx) {
440 assert this.insertIdx == -1 : "use moveInsertPosition instead of setInsertPosition when data already set";
441
442 createInsertionBuffer(insertList);
443 this.insertIdx = insertIdx;
444 }
445
446 void moveInsertPosition(ArrayList<LIRInstruction> newInsertList, int newInsertIdx) {
447 if (insertionBuffer.lirList() != null && (insertionBuffer.lirList() != newInsertList || this.insertIdx != newInsertIdx)) {
448 // insert position changed . resolve current mappings
449 resolveMappings();
450 }
451
452 if (insertionBuffer.lirList() != newInsertList) {
453 // block changed . append insertionBuffer because it is
454 // bound to a specific block and create a new insertionBuffer
455 appendInsertionBuffer();
456 createInsertionBuffer(newInsertList);
457 }
458
459 this.insertIdx = newInsertIdx;
460 }
461
462 public void addMapping(Interval fromInterval, Interval toInterval) {
463
464 if (isIllegal(toInterval.location()) && toInterval.canMaterialize()) {
465 if (Debug.isLogEnabled()) {
466 Debug.log("no store to rematerializable interval %s needed", toInterval);
467 }
468 return;
469 }
470 if (isIllegal(fromInterval.location()) && fromInterval.canMaterialize()) {
471 // Instead of a reload, re-materialize the value
472 Constant rematValue = fromInterval.getMaterializedValue();
473 addMapping(rematValue, toInterval);
474 return;
475 }
476 if (Debug.isLogEnabled()) {
477 Debug.log("add move mapping from %s to %s", fromInterval, toInterval);
478 }
479
480 assert !fromInterval.operand.equals(toInterval.operand) : "from and to interval equal: " + fromInterval;
481 assert LIRKind.verifyMoveKinds(toInterval.kind(), fromInterval.kind(), allocator.getRegisterAllocationConfig()) : String.format("Kind mismatch: %s vs. %s, from=%s, to=%s", fromInterval.kind(),
482 toInterval.kind(), fromInterval, toInterval);
483 mappingFrom.add(fromInterval);
484 mappingFromOpr.add(null);
485 mappingTo.add(toInterval);
486 }
487
488 public void addMapping(Constant fromOpr, Interval toInterval) {
489 if (Debug.isLogEnabled()) {
490 Debug.log("add move mapping from %s to %s", fromOpr, toInterval);
491 }
492
493 mappingFrom.add(null);
494 mappingFromOpr.add(fromOpr);
495 mappingTo.add(toInterval);
496 }
497
498 void resolveAndAppendMoves() {
499 if (hasMappings()) {
500 resolveMappings();
501 }
502 appendInsertionBuffer();
503 }
504 }