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.trace;
24
25 import static org.graalvm.compiler.lir.LIRValueUtil.asVirtualStackSlot;
26 import static org.graalvm.compiler.lir.LIRValueUtil.isStackSlotValue;
27 import static org.graalvm.compiler.lir.LIRValueUtil.isVirtualStackSlot;
28 import static org.graalvm.compiler.lir.alloc.trace.TraceUtil.asShadowedRegisterValue;
29 import static org.graalvm.compiler.lir.alloc.trace.TraceUtil.isShadowedRegisterValue;
30 import static jdk.vm.ci.code.ValueUtil.asAllocatableValue;
31 import static jdk.vm.ci.code.ValueUtil.asRegister;
32 import static jdk.vm.ci.code.ValueUtil.asStackSlot;
33 import static jdk.vm.ci.code.ValueUtil.isIllegal;
34 import static jdk.vm.ci.code.ValueUtil.isRegister;
35 import static jdk.vm.ci.code.ValueUtil.isStackSlot;
36
37 import java.util.ArrayList;
38 import java.util.Arrays;
39 import java.util.HashSet;
40 import java.util.List;
41
42 import org.graalvm.compiler.core.common.LIRKind;
43 import org.graalvm.compiler.debug.Debug;
44 import org.graalvm.compiler.debug.DebugCounter;
45 import org.graalvm.compiler.debug.GraalError;
46 import org.graalvm.compiler.debug.Indent;
47 import org.graalvm.compiler.lir.LIRInsertionBuffer;
48 import org.graalvm.compiler.lir.LIRInstruction;
49 import org.graalvm.compiler.lir.VirtualStackSlot;
50 import org.graalvm.compiler.lir.framemap.FrameMap;
51 import org.graalvm.compiler.lir.framemap.FrameMapBuilder;
52 import org.graalvm.compiler.lir.framemap.FrameMapBuilderTool;
53 import org.graalvm.compiler.lir.gen.LIRGenerationResult;
54 import org.graalvm.compiler.lir.gen.LIRGeneratorTool.MoveFactory;
55
56 import jdk.vm.ci.code.Architecture;
57 import jdk.vm.ci.code.RegisterArray;
58 import jdk.vm.ci.code.StackSlot;
59 import jdk.vm.ci.meta.AllocatableValue;
60 import jdk.vm.ci.meta.Value;
61
62 /**
63 */
64 public final class TraceGlobalMoveResolver extends TraceGlobalMoveResolutionPhase.MoveResolver {
65
66 private static final DebugCounter cycleBreakingSlotsAllocated = Debug.counter("TraceRA[cycleBreakingSlotsAllocated(global)]");
67 private static final DebugCounter cycleBreakingSlotsReused = Debug.counter("TraceRA[cycleBreakingSlotsReused(global)]");
68
69 private int insertIdx;
70 private LIRInsertionBuffer insertionBuffer; // buffer where moves are inserted
71
72 private final List<Value> mappingFrom;
73 private final List<Value> mappingFromStack;
74 private final List<AllocatableValue> mappingTo;
75 private final int[] registerBlocked;
76 private static final int STACK_SLOT_IN_CALLER_FRAME_IDX = -1;
77 private int[] stackBlocked;
78 private final int firstVirtualStackIndex;
79 private final MoveFactory spillMoveFactory;
80 private final FrameMapBuilder frameMapBuilder;
81
82 private void setValueBlocked(Value location, int direction) {
83 assert direction == 1 || direction == -1 : "out of bounds";
84 if (isStackSlotValue(location)) {
85 int stackIdx = getStackArrayIndex(location);
86 if (stackIdx == STACK_SLOT_IN_CALLER_FRAME_IDX) {
87 // incoming stack arguments can be ignored
88 return;
89 }
90 if (stackIdx >= stackBlocked.length) {
91 stackBlocked = Arrays.copyOf(stackBlocked, stackIdx + 1);
92 }
93 stackBlocked[stackIdx] += direction;
94 } else {
95 assert direction == 1 || direction == -1 : "out of bounds";
96 if (isRegister(location)) {
97 registerBlocked[asRegister(location).number] += direction;
98 } else {
99 throw GraalError.shouldNotReachHere("unhandled value " + location);
100 }
101 }
102 }
103
104 private int valueBlocked(Value location) {
105 if (isStackSlotValue(location)) {
106 int stackIdx = getStackArrayIndex(location);
107 if (stackIdx == STACK_SLOT_IN_CALLER_FRAME_IDX) {
108 // incoming stack arguments are always blocked (aka they can not be written)
109 return 1;
110 }
111 if (stackIdx >= stackBlocked.length) {
112 return 0;
113 }
114 return stackBlocked[stackIdx];
115 }
116 if (isRegister(location)) {
117 return registerBlocked[asRegister(location).number];
118 }
119 throw GraalError.shouldNotReachHere("unhandled value " + location);
120 }
121
122 private static boolean areMultipleReadsAllowed() {
123 return true;
124 }
125
126 private boolean hasMappings() {
127 return mappingFrom.size() > 0;
128 }
129
130 private MoveFactory getSpillMoveFactory() {
131 return spillMoveFactory;
132 }
133
134 private RegisterArray getRegisters() {
135 return frameMapBuilder.getRegisterConfig().getAllocatableRegisters();
136 }
137
138 public TraceGlobalMoveResolver(LIRGenerationResult res, MoveFactory spillMoveFactory, Architecture arch) {
139
140 this.mappingFrom = new ArrayList<>(8);
141 this.mappingFromStack = new ArrayList<>(8);
142 this.mappingTo = new ArrayList<>(8);
143 this.insertIdx = -1;
144 this.insertionBuffer = new LIRInsertionBuffer();
145
146 this.frameMapBuilder = res.getFrameMapBuilder();
147 this.spillMoveFactory = spillMoveFactory;
148 this.registerBlocked = new int[arch.getRegisters().size()];
149
150 FrameMapBuilderTool frameMapBuilderTool = (FrameMapBuilderTool) frameMapBuilder;
151 this.stackBlocked = new int[frameMapBuilderTool.getNumberOfStackSlots()];
152
153 FrameMap frameMap = frameMapBuilderTool.getFrameMap();
154 this.firstVirtualStackIndex = !frameMap.frameNeedsAllocating() ? 0 : frameMap.currentFrameSize() + 1;
155 }
156
157 private boolean checkEmpty() {
158 for (int i = 0; i < stackBlocked.length; i++) {
159 assert stackBlocked[i] == 0 : "stack map must be empty before and after processing";
160 }
161 assert mappingFrom.size() == 0 && mappingTo.size() == 0 && mappingFromStack.size() == 0 : "list must be empty before and after processing";
162 for (int i = 0; i < getRegisters().size(); i++) {
163 assert registerBlocked[i] == 0 : "register map must be empty before and after processing";
164 }
165 return true;
166 }
167
168 private boolean verifyBeforeResolve() {
169 assert mappingFrom.size() == mappingTo.size() && mappingFrom.size() == mappingFromStack.size() : "length must be equal";
170 assert insertIdx != -1 : "insert position not set";
171
172 int i;
173 int j;
174 if (!areMultipleReadsAllowed()) {
175 for (i = 0; i < mappingFrom.size(); i++) {
176 for (j = i + 1; j < mappingFrom.size(); j++) {
177 assert mappingFrom.get(i) == null || mappingFrom.get(i) != mappingFrom.get(j) : "cannot read from same interval twice";
178 }
179 }
180 }
181
182 for (i = 0; i < mappingTo.size(); i++) {
183 for (j = i + 1; j < mappingTo.size(); j++) {
184 assert mappingTo.get(i) != mappingTo.get(j) : "cannot write to same interval twice";
185 }
186 }
187
188 for (i = 0; i < mappingTo.size(); i++) {
189 Value to = mappingTo.get(i);
190 assert !isStackSlotValue(to) || getStackArrayIndex(to) != STACK_SLOT_IN_CALLER_FRAME_IDX : "Cannot move to in argument: " + to;
191 }
192
193 HashSet<Value> usedRegs = new HashSet<>();
194 if (!areMultipleReadsAllowed()) {
195 for (i = 0; i < mappingFrom.size(); i++) {
196 Value from = mappingFrom.get(i);
197 if (from != null && !isIllegal(from)) {
198 boolean unique = usedRegs.add(from);
199 assert unique : "cannot read from same register twice";
200 }
201 }
202 }
203
204 usedRegs.clear();
205 for (i = 0; i < mappingTo.size(); i++) {
206 Value to = mappingTo.get(i);
207 if (isIllegal(to)) {
208 // After insertion the location may become illegal, so don't check it since multiple
209 // intervals might be illegal.
210 continue;
211 }
212 boolean unique = usedRegs.add(to);
213 assert unique : "cannot write to same register twice";
214 }
215
216 return true;
217 }
218
219 // mark assignedReg and assignedRegHi of the interval as blocked
220 private void block(Value location) {
221 if (mightBeBlocked(location)) {
222 assert areMultipleReadsAllowed() || valueBlocked(location) == 0 : "location already marked as used: " + location;
223 setValueBlocked(location, 1);
224 Debug.log("block %s", location);
225 }
226 }
227
228 // mark assignedReg and assignedRegHi of the interval as unblocked
229 private void unblock(Value location) {
230 if (mightBeBlocked(location)) {
231 assert valueBlocked(location) > 0 : "location already marked as unused: " + location;
232 setValueBlocked(location, -1);
233 Debug.log("unblock %s", location);
234 }
235 }
236
237 /**
238 * Checks if {@code to} is not blocked or is only blocked by {@code from}.
239 */
240 private boolean safeToProcessMove(Value fromLocation, Value toLocation) {
241 if (mightBeBlocked(toLocation)) {
242 if ((valueBlocked(toLocation) > 1 || (valueBlocked(toLocation) == 1 && !isMoveToSelf(fromLocation, toLocation)))) {
243 return false;
244 }
245 }
246
247 return true;
248 }
249
250 public static boolean isMoveToSelf(Value from, Value to) {
251 assert to != null;
252 if (to.equals(from)) {
253 return true;
254 }
255 if (from == null) {
256 return false;
257 }
258 if (isShadowedRegisterValue(from)) {
259 /* From is a shadowed register. */
260 if (isShadowedRegisterValue(to)) {
261 // both shadowed but not equal
262 return false;
263 }
264 ShadowedRegisterValue shadowed = asShadowedRegisterValue(from);
265 if (isRegisterToRegisterMoveToSelf(shadowed.getRegister(), to)) {
266 return true;
267 }
268 if (isStackSlotValue(to)) {
269 return to.equals(shadowed.getStackSlot());
270 }
271 } else {
272 /*
273 * A shadowed destination value is never a self move it both values are not equal. Fall
274 * through.
275 */
276 // if (isShadowedRegisterValue(to)) return false;
277
278 return isRegisterToRegisterMoveToSelf(from, to);
279 }
280 return false;
281 }
282
283 private static boolean isRegisterToRegisterMoveToSelf(Value from, Value to) {
284 if (to.equals(from)) {
285 return true;
286 }
287 if (isRegister(from) && isRegister(to) && asRegister(from).equals(asRegister(to))) {
288 // Values differ but Registers are the same
289 assert LIRKind.verifyMoveKinds(to.getValueKind(), from.getValueKind()) : String.format("Same register but Kind mismatch %s <- %s", to, from);
290 return true;
291 }
292 return false;
293 }
294
295 private static boolean mightBeBlocked(Value location) {
296 return isRegister(location) || isStackSlotValue(location);
297 }
298
299 private void createInsertionBuffer(List<LIRInstruction> list) {
300 assert !insertionBuffer.initialized() : "overwriting existing buffer";
301 insertionBuffer.init(list);
302 }
303
304 private void appendInsertionBuffer() {
305 if (insertionBuffer.initialized()) {
306 insertionBuffer.finish();
307 }
308 assert !insertionBuffer.initialized() : "must be uninitialized now";
309
310 insertIdx = -1;
311 }
312
313 private void insertMove(Value fromOperand, AllocatableValue toOperand) {
314 assert !fromOperand.equals(toOperand) : "from and to are equal: " + fromOperand + " vs. " + toOperand;
315 assert LIRKind.verifyMoveKinds(fromOperand.getValueKind(), fromOperand.getValueKind()) : "move between different types";
316 assert insertIdx != -1 : "must setup insert position first";
317
318 insertionBuffer.append(insertIdx, createMove(fromOperand, toOperand));
319
320 if (Debug.isLogEnabled()) {
321 Debug.log("insert move from %s to %s at %d", fromOperand, toOperand, insertIdx);
322 }
323 }
324
325 /**
326 * @param fromOpr Operand of the {@code from} interval
327 * @param toOpr Operand of the {@code to} interval
328 */
329 private LIRInstruction createMove(Value fromOpr, AllocatableValue toOpr) {
330 if (isStackSlotValue(toOpr) && isStackSlotValue(fromOpr)) {
331 return getSpillMoveFactory().createStackMove(toOpr, asAllocatableValue(fromOpr));
332 }
333 return getSpillMoveFactory().createMove(toOpr, fromOpr);
334 }
335
336 @SuppressWarnings("try")
337 private void resolveMappings() {
338 try (Indent indent = Debug.logAndIndent("resolveMapping")) {
339 assert verifyBeforeResolve();
340 if (Debug.isLogEnabled()) {
341 printMapping();
342 }
343
344 // Block all registers that are used as input operands of a move.
345 // When a register is blocked, no move to this register is emitted.
346 // This is necessary for detecting cycles in moves.
347 for (int i = mappingFrom.size() - 1; i >= 0; i--) {
348 Value from = mappingFrom.get(i);
349 block(from);
350 }
351
352 ArrayList<AllocatableValue> busySpillSlots = null;
353 while (mappingFrom.size() > 0) {
354 boolean processedInterval = false;
355
356 int spillCandidate = -1;
357 for (int i = mappingFrom.size() - 1; i >= 0; i--) {
358 Value fromLocation = mappingFrom.get(i);
359 AllocatableValue toLocation = mappingTo.get(i);
360 if (safeToProcessMove(fromLocation, toLocation)) {
361 // this interval can be processed because target is free
362 insertMove(fromLocation, toLocation);
363 unblock(fromLocation);
364 if (isStackSlotValue(toLocation)) {
365 if (busySpillSlots == null) {
366 busySpillSlots = new ArrayList<>(2);
367 }
368 busySpillSlots.add(toLocation);
369 }
370 mappingFrom.remove(i);
371 mappingFromStack.remove(i);
372 mappingTo.remove(i);
373
374 processedInterval = true;
375 } else if (fromLocation != null) {
376 if (isRegister(fromLocation) && (busySpillSlots == null || !busySpillSlots.contains(mappingFromStack.get(i)))) {
377 // this interval cannot be processed now because target is not free
378 // it starts in a register, so it is a possible candidate for spilling
379 spillCandidate = i;
380 } else if (isStackSlotValue(fromLocation) && spillCandidate == -1) {
381 // fall back to spill a stack slot in case no other candidate is found
382 spillCandidate = i;
383 }
384 }
385 }
386
387 if (!processedInterval) {
388 breakCycle(spillCandidate);
389 }
390 }
391 }
392
393 // check that all intervals have been processed
394 assert checkEmpty();
395 }
396
397 @SuppressWarnings("try")
398 private void breakCycle(int spillCandidate) {
399 // no move could be processed because there is a cycle in the move list
400 // (e.g. r1 . r2, r2 . r1), so one interval must be spilled to memory
401 assert spillCandidate != -1 : "no interval in register for spilling found";
402
403 // create a new spill interval and assign a stack slot to it
404 Value from = mappingFrom.get(spillCandidate);
405 try (Indent indent = Debug.logAndIndent("BreakCycle: %s", from)) {
406 AllocatableValue spillSlot = null;
407 if (TraceRegisterAllocationPhase.Options.TraceRAreuseStackSlotsForMoveResolutionCycleBreaking.getValue() && !isStackSlotValue(from)) {
408 // don't use the stack slot if from is already the stack slot
409 Value fromStack = mappingFromStack.get(spillCandidate);
410 if (fromStack != null) {
411 spillSlot = (AllocatableValue) fromStack;
412 cycleBreakingSlotsReused.increment();
413 Debug.log("reuse slot for spilling: %s", spillSlot);
414 }
415 }
416 if (spillSlot == null) {
417 spillSlot = frameMapBuilder.allocateSpillSlot(from.getValueKind());
418 cycleBreakingSlotsAllocated.increment();
419 Debug.log("created new slot for spilling: %s", spillSlot);
420 // insert a move from register to stack and update the mapping
421 insertMove(from, spillSlot);
422 }
423 block(spillSlot);
424 mappingFrom.set(spillCandidate, spillSlot);
425 unblock(from);
426 }
427 }
428
429 @SuppressWarnings("try")
430 private void printMapping() {
431 try (Indent indent = Debug.logAndIndent("Mapping")) {
432 for (int i = mappingFrom.size() - 1; i >= 0; i--) {
433 Debug.log("move %s <- %s (%s)", mappingTo.get(i), mappingFrom.get(i), mappingFromStack.get(i));
434 }
435 }
436 }
437
438 public void setInsertPosition(List<LIRInstruction> insertList, int insertIdx) {
439 assert this.insertIdx == -1 : "use moveInsertPosition instead of setInsertPosition when data already set";
440
441 createInsertionBuffer(insertList);
442 this.insertIdx = insertIdx;
443 }
444
445 @Override
446 public void addMapping(Value from, AllocatableValue to, Value fromStack) {
447 if (Debug.isLogEnabled()) {
448 Debug.log("add move mapping from %s to %s", from, to);
449 }
450
451 assert !from.equals(to) : "from and to interval equal: " + from;
452 assert LIRKind.verifyMoveKinds(to.getValueKind(), from.getValueKind()) : String.format("Kind mismatch: %s vs. %s, from=%s, to=%s", from.getValueKind(), to.getValueKind(), from, to);
453 assert fromStack == null || LIRKind.verifyMoveKinds(to.getValueKind(), fromStack.getValueKind()) : String.format("Kind mismatch: %s vs. %s, fromStack=%s, to=%s", fromStack.getValueKind(),
454 to.getValueKind(), fromStack, to);
455 mappingFrom.add(from);
456 mappingFromStack.add(fromStack);
457 mappingTo.add(to);
458 }
459
460 public void resolveAndAppendMoves() {
461 if (hasMappings()) {
462 resolveMappings();
463 }
464 appendInsertionBuffer();
465 }
466
467 private int getStackArrayIndex(Value stackSlotValue) {
468 if (isStackSlot(stackSlotValue)) {
469 return getStackArrayIndex(asStackSlot(stackSlotValue));
470 }
471 if (isVirtualStackSlot(stackSlotValue)) {
472 return getStackArrayIndex(asVirtualStackSlot(stackSlotValue));
473 }
474 throw GraalError.shouldNotReachHere("value is not a stack slot: " + stackSlotValue);
475 }
476
477 private int getStackArrayIndex(StackSlot stackSlot) {
478 int stackIdx;
479 if (stackSlot.isInCallerFrame()) {
480 // incoming stack arguments can be ignored
481 stackIdx = STACK_SLOT_IN_CALLER_FRAME_IDX;
482 } else {
483 assert stackSlot.getRawAddFrameSize() : "Unexpected stack slot: " + stackSlot;
484 int offset = -stackSlot.getRawOffset();
485 assert 0 <= offset && offset < firstVirtualStackIndex : String.format("Wrong stack slot offset: %d (first virtual stack slot index: %d", offset, firstVirtualStackIndex);
486 stackIdx = offset;
487 }
488 return stackIdx;
489 }
490
491 private int getStackArrayIndex(VirtualStackSlot virtualStackSlot) {
492 return firstVirtualStackIndex + virtualStackSlot.getId();
493 }
494
495 }