File: | src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/CodeGen/ScheduleDAG.cpp |
Warning: | line 663, column 9 Value stored to 'Found' is never read |
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1 | //===- ScheduleDAG.cpp - Implement the ScheduleDAG class ------------------===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | // |
9 | /// \file Implements the ScheduleDAG class, which is a base class used by |
10 | /// scheduling implementation classes. |
11 | // |
12 | //===----------------------------------------------------------------------===// |
13 | |
14 | #include "llvm/CodeGen/ScheduleDAG.h" |
15 | #include "llvm/ADT/STLExtras.h" |
16 | #include "llvm/ADT/SmallVector.h" |
17 | #include "llvm/ADT/Statistic.h" |
18 | #include "llvm/ADT/iterator_range.h" |
19 | #include "llvm/CodeGen/MachineFunction.h" |
20 | #include "llvm/CodeGen/ScheduleHazardRecognizer.h" |
21 | #include "llvm/CodeGen/SelectionDAGNodes.h" |
22 | #include "llvm/CodeGen/TargetInstrInfo.h" |
23 | #include "llvm/CodeGen/TargetRegisterInfo.h" |
24 | #include "llvm/CodeGen/TargetSubtargetInfo.h" |
25 | #include "llvm/Config/llvm-config.h" |
26 | #include "llvm/Support/CommandLine.h" |
27 | #include "llvm/Support/Compiler.h" |
28 | #include "llvm/Support/Debug.h" |
29 | #include "llvm/Support/raw_ostream.h" |
30 | #include <algorithm> |
31 | #include <cassert> |
32 | #include <iterator> |
33 | #include <limits> |
34 | #include <utility> |
35 | #include <vector> |
36 | |
37 | using namespace llvm; |
38 | |
39 | #define DEBUG_TYPE"pre-RA-sched" "pre-RA-sched" |
40 | |
41 | STATISTIC(NumNewPredsAdded, "Number of times a single predecessor was added")static llvm::Statistic NumNewPredsAdded = {"pre-RA-sched", "NumNewPredsAdded" , "Number of times a single predecessor was added"}; |
42 | STATISTIC(NumTopoInits,static llvm::Statistic NumTopoInits = {"pre-RA-sched", "NumTopoInits" , "Number of times the topological order has been recomputed" } |
43 | "Number of times the topological order has been recomputed")static llvm::Statistic NumTopoInits = {"pre-RA-sched", "NumTopoInits" , "Number of times the topological order has been recomputed" }; |
44 | |
45 | #ifndef NDEBUG1 |
46 | static cl::opt<bool> StressSchedOpt( |
47 | "stress-sched", cl::Hidden, cl::init(false), |
48 | cl::desc("Stress test instruction scheduling")); |
49 | #endif |
50 | |
51 | void SchedulingPriorityQueue::anchor() {} |
52 | |
53 | ScheduleDAG::ScheduleDAG(MachineFunction &mf) |
54 | : TM(mf.getTarget()), TII(mf.getSubtarget().getInstrInfo()), |
55 | TRI(mf.getSubtarget().getRegisterInfo()), MF(mf), |
56 | MRI(mf.getRegInfo()) { |
57 | #ifndef NDEBUG1 |
58 | StressSched = StressSchedOpt; |
59 | #endif |
60 | } |
61 | |
62 | ScheduleDAG::~ScheduleDAG() = default; |
63 | |
64 | void ScheduleDAG::clearDAG() { |
65 | SUnits.clear(); |
66 | EntrySU = SUnit(); |
67 | ExitSU = SUnit(); |
68 | } |
69 | |
70 | const MCInstrDesc *ScheduleDAG::getNodeDesc(const SDNode *Node) const { |
71 | if (!Node || !Node->isMachineOpcode()) return nullptr; |
72 | return &TII->get(Node->getMachineOpcode()); |
73 | } |
74 | |
75 | LLVM_DUMP_METHOD__attribute__((noinline)) void SDep::dump(const TargetRegisterInfo *TRI) const { |
76 | switch (getKind()) { |
77 | case Data: dbgs() << "Data"; break; |
78 | case Anti: dbgs() << "Anti"; break; |
79 | case Output: dbgs() << "Out "; break; |
80 | case Order: dbgs() << "Ord "; break; |
81 | } |
82 | |
83 | switch (getKind()) { |
84 | case Data: |
85 | dbgs() << " Latency=" << getLatency(); |
86 | if (TRI && isAssignedRegDep()) |
87 | dbgs() << " Reg=" << printReg(getReg(), TRI); |
88 | break; |
89 | case Anti: |
90 | case Output: |
91 | dbgs() << " Latency=" << getLatency(); |
92 | break; |
93 | case Order: |
94 | dbgs() << " Latency=" << getLatency(); |
95 | switch(Contents.OrdKind) { |
96 | case Barrier: dbgs() << " Barrier"; break; |
97 | case MayAliasMem: |
98 | case MustAliasMem: dbgs() << " Memory"; break; |
99 | case Artificial: dbgs() << " Artificial"; break; |
100 | case Weak: dbgs() << " Weak"; break; |
101 | case Cluster: dbgs() << " Cluster"; break; |
102 | } |
103 | break; |
104 | } |
105 | } |
106 | |
107 | bool SUnit::addPred(const SDep &D, bool Required) { |
108 | // If this node already has this dependence, don't add a redundant one. |
109 | for (SDep &PredDep : Preds) { |
110 | // Zero-latency weak edges may be added purely for heuristic ordering. Don't |
111 | // add them if another kind of edge already exists. |
112 | if (!Required && PredDep.getSUnit() == D.getSUnit()) |
113 | return false; |
114 | if (PredDep.overlaps(D)) { |
115 | // Extend the latency if needed. Equivalent to |
116 | // removePred(PredDep) + addPred(D). |
117 | if (PredDep.getLatency() < D.getLatency()) { |
118 | SUnit *PredSU = PredDep.getSUnit(); |
119 | // Find the corresponding successor in N. |
120 | SDep ForwardD = PredDep; |
121 | ForwardD.setSUnit(this); |
122 | for (SDep &SuccDep : PredSU->Succs) { |
123 | if (SuccDep == ForwardD) { |
124 | SuccDep.setLatency(D.getLatency()); |
125 | break; |
126 | } |
127 | } |
128 | PredDep.setLatency(D.getLatency()); |
129 | } |
130 | return false; |
131 | } |
132 | } |
133 | // Now add a corresponding succ to N. |
134 | SDep P = D; |
135 | P.setSUnit(this); |
136 | SUnit *N = D.getSUnit(); |
137 | // Update the bookkeeping. |
138 | if (D.getKind() == SDep::Data) { |
139 | assert(NumPreds < std::numeric_limits<unsigned>::max() &&((void)0) |
140 | "NumPreds will overflow!")((void)0); |
141 | assert(N->NumSuccs < std::numeric_limits<unsigned>::max() &&((void)0) |
142 | "NumSuccs will overflow!")((void)0); |
143 | ++NumPreds; |
144 | ++N->NumSuccs; |
145 | } |
146 | if (!N->isScheduled) { |
147 | if (D.isWeak()) { |
148 | ++WeakPredsLeft; |
149 | } |
150 | else { |
151 | assert(NumPredsLeft < std::numeric_limits<unsigned>::max() &&((void)0) |
152 | "NumPredsLeft will overflow!")((void)0); |
153 | ++NumPredsLeft; |
154 | } |
155 | } |
156 | if (!isScheduled) { |
157 | if (D.isWeak()) { |
158 | ++N->WeakSuccsLeft; |
159 | } |
160 | else { |
161 | assert(N->NumSuccsLeft < std::numeric_limits<unsigned>::max() &&((void)0) |
162 | "NumSuccsLeft will overflow!")((void)0); |
163 | ++N->NumSuccsLeft; |
164 | } |
165 | } |
166 | Preds.push_back(D); |
167 | N->Succs.push_back(P); |
168 | if (P.getLatency() != 0) { |
169 | this->setDepthDirty(); |
170 | N->setHeightDirty(); |
171 | } |
172 | return true; |
173 | } |
174 | |
175 | void SUnit::removePred(const SDep &D) { |
176 | // Find the matching predecessor. |
177 | SmallVectorImpl<SDep>::iterator I = llvm::find(Preds, D); |
178 | if (I == Preds.end()) |
179 | return; |
180 | // Find the corresponding successor in N. |
181 | SDep P = D; |
182 | P.setSUnit(this); |
183 | SUnit *N = D.getSUnit(); |
184 | SmallVectorImpl<SDep>::iterator Succ = llvm::find(N->Succs, P); |
185 | assert(Succ != N->Succs.end() && "Mismatching preds / succs lists!")((void)0); |
186 | N->Succs.erase(Succ); |
187 | Preds.erase(I); |
188 | // Update the bookkeeping. |
189 | if (P.getKind() == SDep::Data) { |
190 | assert(NumPreds > 0 && "NumPreds will underflow!")((void)0); |
191 | assert(N->NumSuccs > 0 && "NumSuccs will underflow!")((void)0); |
192 | --NumPreds; |
193 | --N->NumSuccs; |
194 | } |
195 | if (!N->isScheduled) { |
196 | if (D.isWeak()) |
197 | --WeakPredsLeft; |
198 | else { |
199 | assert(NumPredsLeft > 0 && "NumPredsLeft will underflow!")((void)0); |
200 | --NumPredsLeft; |
201 | } |
202 | } |
203 | if (!isScheduled) { |
204 | if (D.isWeak()) |
205 | --N->WeakSuccsLeft; |
206 | else { |
207 | assert(N->NumSuccsLeft > 0 && "NumSuccsLeft will underflow!")((void)0); |
208 | --N->NumSuccsLeft; |
209 | } |
210 | } |
211 | if (P.getLatency() != 0) { |
212 | this->setDepthDirty(); |
213 | N->setHeightDirty(); |
214 | } |
215 | } |
216 | |
217 | void SUnit::setDepthDirty() { |
218 | if (!isDepthCurrent) return; |
219 | SmallVector<SUnit*, 8> WorkList; |
220 | WorkList.push_back(this); |
221 | do { |
222 | SUnit *SU = WorkList.pop_back_val(); |
223 | SU->isDepthCurrent = false; |
224 | for (SDep &SuccDep : SU->Succs) { |
225 | SUnit *SuccSU = SuccDep.getSUnit(); |
226 | if (SuccSU->isDepthCurrent) |
227 | WorkList.push_back(SuccSU); |
228 | } |
229 | } while (!WorkList.empty()); |
230 | } |
231 | |
232 | void SUnit::setHeightDirty() { |
233 | if (!isHeightCurrent) return; |
234 | SmallVector<SUnit*, 8> WorkList; |
235 | WorkList.push_back(this); |
236 | do { |
237 | SUnit *SU = WorkList.pop_back_val(); |
238 | SU->isHeightCurrent = false; |
239 | for (SDep &PredDep : SU->Preds) { |
240 | SUnit *PredSU = PredDep.getSUnit(); |
241 | if (PredSU->isHeightCurrent) |
242 | WorkList.push_back(PredSU); |
243 | } |
244 | } while (!WorkList.empty()); |
245 | } |
246 | |
247 | void SUnit::setDepthToAtLeast(unsigned NewDepth) { |
248 | if (NewDepth <= getDepth()) |
249 | return; |
250 | setDepthDirty(); |
251 | Depth = NewDepth; |
252 | isDepthCurrent = true; |
253 | } |
254 | |
255 | void SUnit::setHeightToAtLeast(unsigned NewHeight) { |
256 | if (NewHeight <= getHeight()) |
257 | return; |
258 | setHeightDirty(); |
259 | Height = NewHeight; |
260 | isHeightCurrent = true; |
261 | } |
262 | |
263 | /// Calculates the maximal path from the node to the exit. |
264 | void SUnit::ComputeDepth() { |
265 | SmallVector<SUnit*, 8> WorkList; |
266 | WorkList.push_back(this); |
267 | do { |
268 | SUnit *Cur = WorkList.back(); |
269 | |
270 | bool Done = true; |
271 | unsigned MaxPredDepth = 0; |
272 | for (const SDep &PredDep : Cur->Preds) { |
273 | SUnit *PredSU = PredDep.getSUnit(); |
274 | if (PredSU->isDepthCurrent) |
275 | MaxPredDepth = std::max(MaxPredDepth, |
276 | PredSU->Depth + PredDep.getLatency()); |
277 | else { |
278 | Done = false; |
279 | WorkList.push_back(PredSU); |
280 | } |
281 | } |
282 | |
283 | if (Done) { |
284 | WorkList.pop_back(); |
285 | if (MaxPredDepth != Cur->Depth) { |
286 | Cur->setDepthDirty(); |
287 | Cur->Depth = MaxPredDepth; |
288 | } |
289 | Cur->isDepthCurrent = true; |
290 | } |
291 | } while (!WorkList.empty()); |
292 | } |
293 | |
294 | /// Calculates the maximal path from the node to the entry. |
295 | void SUnit::ComputeHeight() { |
296 | SmallVector<SUnit*, 8> WorkList; |
297 | WorkList.push_back(this); |
298 | do { |
299 | SUnit *Cur = WorkList.back(); |
300 | |
301 | bool Done = true; |
302 | unsigned MaxSuccHeight = 0; |
303 | for (const SDep &SuccDep : Cur->Succs) { |
304 | SUnit *SuccSU = SuccDep.getSUnit(); |
305 | if (SuccSU->isHeightCurrent) |
306 | MaxSuccHeight = std::max(MaxSuccHeight, |
307 | SuccSU->Height + SuccDep.getLatency()); |
308 | else { |
309 | Done = false; |
310 | WorkList.push_back(SuccSU); |
311 | } |
312 | } |
313 | |
314 | if (Done) { |
315 | WorkList.pop_back(); |
316 | if (MaxSuccHeight != Cur->Height) { |
317 | Cur->setHeightDirty(); |
318 | Cur->Height = MaxSuccHeight; |
319 | } |
320 | Cur->isHeightCurrent = true; |
321 | } |
322 | } while (!WorkList.empty()); |
323 | } |
324 | |
325 | void SUnit::biasCriticalPath() { |
326 | if (NumPreds < 2) |
327 | return; |
328 | |
329 | SUnit::pred_iterator BestI = Preds.begin(); |
330 | unsigned MaxDepth = BestI->getSUnit()->getDepth(); |
331 | for (SUnit::pred_iterator I = std::next(BestI), E = Preds.end(); I != E; |
332 | ++I) { |
333 | if (I->getKind() == SDep::Data && I->getSUnit()->getDepth() > MaxDepth) |
334 | BestI = I; |
335 | } |
336 | if (BestI != Preds.begin()) |
337 | std::swap(*Preds.begin(), *BestI); |
338 | } |
339 | |
340 | #if !defined(NDEBUG1) || defined(LLVM_ENABLE_DUMP) |
341 | LLVM_DUMP_METHOD__attribute__((noinline)) void SUnit::dumpAttributes() const { |
342 | dbgs() << " # preds left : " << NumPredsLeft << "\n"; |
343 | dbgs() << " # succs left : " << NumSuccsLeft << "\n"; |
344 | if (WeakPredsLeft) |
345 | dbgs() << " # weak preds left : " << WeakPredsLeft << "\n"; |
346 | if (WeakSuccsLeft) |
347 | dbgs() << " # weak succs left : " << WeakSuccsLeft << "\n"; |
348 | dbgs() << " # rdefs left : " << NumRegDefsLeft << "\n"; |
349 | dbgs() << " Latency : " << Latency << "\n"; |
350 | dbgs() << " Depth : " << getDepth() << "\n"; |
351 | dbgs() << " Height : " << getHeight() << "\n"; |
352 | } |
353 | |
354 | LLVM_DUMP_METHOD__attribute__((noinline)) void ScheduleDAG::dumpNodeName(const SUnit &SU) const { |
355 | if (&SU == &EntrySU) |
356 | dbgs() << "EntrySU"; |
357 | else if (&SU == &ExitSU) |
358 | dbgs() << "ExitSU"; |
359 | else |
360 | dbgs() << "SU(" << SU.NodeNum << ")"; |
361 | } |
362 | |
363 | LLVM_DUMP_METHOD__attribute__((noinline)) void ScheduleDAG::dumpNodeAll(const SUnit &SU) const { |
364 | dumpNode(SU); |
365 | SU.dumpAttributes(); |
366 | if (SU.Preds.size() > 0) { |
367 | dbgs() << " Predecessors:\n"; |
368 | for (const SDep &Dep : SU.Preds) { |
369 | dbgs() << " "; |
370 | dumpNodeName(*Dep.getSUnit()); |
371 | dbgs() << ": "; |
372 | Dep.dump(TRI); |
373 | dbgs() << '\n'; |
374 | } |
375 | } |
376 | if (SU.Succs.size() > 0) { |
377 | dbgs() << " Successors:\n"; |
378 | for (const SDep &Dep : SU.Succs) { |
379 | dbgs() << " "; |
380 | dumpNodeName(*Dep.getSUnit()); |
381 | dbgs() << ": "; |
382 | Dep.dump(TRI); |
383 | dbgs() << '\n'; |
384 | } |
385 | } |
386 | } |
387 | #endif |
388 | |
389 | #ifndef NDEBUG1 |
390 | unsigned ScheduleDAG::VerifyScheduledDAG(bool isBottomUp) { |
391 | bool AnyNotSched = false; |
392 | unsigned DeadNodes = 0; |
393 | for (const SUnit &SUnit : SUnits) { |
394 | if (!SUnit.isScheduled) { |
395 | if (SUnit.NumPreds == 0 && SUnit.NumSuccs == 0) { |
396 | ++DeadNodes; |
397 | continue; |
398 | } |
399 | if (!AnyNotSched) |
400 | dbgs() << "*** Scheduling failed! ***\n"; |
401 | dumpNode(SUnit); |
402 | dbgs() << "has not been scheduled!\n"; |
403 | AnyNotSched = true; |
404 | } |
405 | if (SUnit.isScheduled && |
406 | (isBottomUp ? SUnit.getHeight() : SUnit.getDepth()) > |
407 | unsigned(std::numeric_limits<int>::max())) { |
408 | if (!AnyNotSched) |
409 | dbgs() << "*** Scheduling failed! ***\n"; |
410 | dumpNode(SUnit); |
411 | dbgs() << "has an unexpected " |
412 | << (isBottomUp ? "Height" : "Depth") << " value!\n"; |
413 | AnyNotSched = true; |
414 | } |
415 | if (isBottomUp) { |
416 | if (SUnit.NumSuccsLeft != 0) { |
417 | if (!AnyNotSched) |
418 | dbgs() << "*** Scheduling failed! ***\n"; |
419 | dumpNode(SUnit); |
420 | dbgs() << "has successors left!\n"; |
421 | AnyNotSched = true; |
422 | } |
423 | } else { |
424 | if (SUnit.NumPredsLeft != 0) { |
425 | if (!AnyNotSched) |
426 | dbgs() << "*** Scheduling failed! ***\n"; |
427 | dumpNode(SUnit); |
428 | dbgs() << "has predecessors left!\n"; |
429 | AnyNotSched = true; |
430 | } |
431 | } |
432 | } |
433 | assert(!AnyNotSched)((void)0); |
434 | return SUnits.size() - DeadNodes; |
435 | } |
436 | #endif |
437 | |
438 | void ScheduleDAGTopologicalSort::InitDAGTopologicalSorting() { |
439 | // The idea of the algorithm is taken from |
440 | // "Online algorithms for managing the topological order of |
441 | // a directed acyclic graph" by David J. Pearce and Paul H.J. Kelly |
442 | // This is the MNR algorithm, which was first introduced by |
443 | // A. Marchetti-Spaccamela, U. Nanni and H. Rohnert in |
444 | // "Maintaining a topological order under edge insertions". |
445 | // |
446 | // Short description of the algorithm: |
447 | // |
448 | // Topological ordering, ord, of a DAG maps each node to a topological |
449 | // index so that for all edges X->Y it is the case that ord(X) < ord(Y). |
450 | // |
451 | // This means that if there is a path from the node X to the node Z, |
452 | // then ord(X) < ord(Z). |
453 | // |
454 | // This property can be used to check for reachability of nodes: |
455 | // if Z is reachable from X, then an insertion of the edge Z->X would |
456 | // create a cycle. |
457 | // |
458 | // The algorithm first computes a topological ordering for the DAG by |
459 | // initializing the Index2Node and Node2Index arrays and then tries to keep |
460 | // the ordering up-to-date after edge insertions by reordering the DAG. |
461 | // |
462 | // On insertion of the edge X->Y, the algorithm first marks by calling DFS |
463 | // the nodes reachable from Y, and then shifts them using Shift to lie |
464 | // immediately after X in Index2Node. |
465 | |
466 | // Cancel pending updates, mark as valid. |
467 | Dirty = false; |
468 | Updates.clear(); |
469 | |
470 | unsigned DAGSize = SUnits.size(); |
471 | std::vector<SUnit*> WorkList; |
472 | WorkList.reserve(DAGSize); |
473 | |
474 | Index2Node.resize(DAGSize); |
475 | Node2Index.resize(DAGSize); |
476 | |
477 | // Initialize the data structures. |
478 | if (ExitSU) |
479 | WorkList.push_back(ExitSU); |
480 | for (SUnit &SU : SUnits) { |
481 | int NodeNum = SU.NodeNum; |
482 | unsigned Degree = SU.Succs.size(); |
483 | // Temporarily use the Node2Index array as scratch space for degree counts. |
484 | Node2Index[NodeNum] = Degree; |
485 | |
486 | // Is it a node without dependencies? |
487 | if (Degree == 0) { |
488 | assert(SU.Succs.empty() && "SUnit should have no successors")((void)0); |
489 | // Collect leaf nodes. |
490 | WorkList.push_back(&SU); |
491 | } |
492 | } |
493 | |
494 | int Id = DAGSize; |
495 | while (!WorkList.empty()) { |
496 | SUnit *SU = WorkList.back(); |
497 | WorkList.pop_back(); |
498 | if (SU->NodeNum < DAGSize) |
499 | Allocate(SU->NodeNum, --Id); |
500 | for (const SDep &PredDep : SU->Preds) { |
501 | SUnit *SU = PredDep.getSUnit(); |
502 | if (SU->NodeNum < DAGSize && !--Node2Index[SU->NodeNum]) |
503 | // If all dependencies of the node are processed already, |
504 | // then the node can be computed now. |
505 | WorkList.push_back(SU); |
506 | } |
507 | } |
508 | |
509 | Visited.resize(DAGSize); |
510 | NumTopoInits++; |
511 | |
512 | #ifndef NDEBUG1 |
513 | // Check correctness of the ordering |
514 | for (SUnit &SU : SUnits) { |
515 | for (const SDep &PD : SU.Preds) { |
516 | assert(Node2Index[SU.NodeNum] > Node2Index[PD.getSUnit()->NodeNum] &&((void)0) |
517 | "Wrong topological sorting")((void)0); |
518 | } |
519 | } |
520 | #endif |
521 | } |
522 | |
523 | void ScheduleDAGTopologicalSort::FixOrder() { |
524 | // Recompute from scratch after new nodes have been added. |
525 | if (Dirty) { |
526 | InitDAGTopologicalSorting(); |
527 | return; |
528 | } |
529 | |
530 | // Otherwise apply updates one-by-one. |
531 | for (auto &U : Updates) |
532 | AddPred(U.first, U.second); |
533 | Updates.clear(); |
534 | } |
535 | |
536 | void ScheduleDAGTopologicalSort::AddPredQueued(SUnit *Y, SUnit *X) { |
537 | // Recomputing the order from scratch is likely more efficient than applying |
538 | // updates one-by-one for too many updates. The current cut-off is arbitrarily |
539 | // chosen. |
540 | Dirty = Dirty || Updates.size() > 10; |
541 | |
542 | if (Dirty) |
543 | return; |
544 | |
545 | Updates.emplace_back(Y, X); |
546 | } |
547 | |
548 | void ScheduleDAGTopologicalSort::AddPred(SUnit *Y, SUnit *X) { |
549 | int UpperBound, LowerBound; |
550 | LowerBound = Node2Index[Y->NodeNum]; |
551 | UpperBound = Node2Index[X->NodeNum]; |
552 | bool HasLoop = false; |
553 | // Is Ord(X) < Ord(Y) ? |
554 | if (LowerBound < UpperBound) { |
555 | // Update the topological order. |
556 | Visited.reset(); |
557 | DFS(Y, UpperBound, HasLoop); |
558 | assert(!HasLoop && "Inserted edge creates a loop!")((void)0); |
559 | // Recompute topological indexes. |
560 | Shift(Visited, LowerBound, UpperBound); |
561 | } |
562 | |
563 | NumNewPredsAdded++; |
564 | } |
565 | |
566 | void ScheduleDAGTopologicalSort::RemovePred(SUnit *M, SUnit *N) { |
567 | // InitDAGTopologicalSorting(); |
568 | } |
569 | |
570 | void ScheduleDAGTopologicalSort::DFS(const SUnit *SU, int UpperBound, |
571 | bool &HasLoop) { |
572 | std::vector<const SUnit*> WorkList; |
573 | WorkList.reserve(SUnits.size()); |
574 | |
575 | WorkList.push_back(SU); |
576 | do { |
577 | SU = WorkList.back(); |
578 | WorkList.pop_back(); |
579 | Visited.set(SU->NodeNum); |
580 | for (const SDep &SuccDep |
581 | : make_range(SU->Succs.rbegin(), SU->Succs.rend())) { |
582 | unsigned s = SuccDep.getSUnit()->NodeNum; |
583 | // Edges to non-SUnits are allowed but ignored (e.g. ExitSU). |
584 | if (s >= Node2Index.size()) |
585 | continue; |
586 | if (Node2Index[s] == UpperBound) { |
587 | HasLoop = true; |
588 | return; |
589 | } |
590 | // Visit successors if not already and in affected region. |
591 | if (!Visited.test(s) && Node2Index[s] < UpperBound) { |
592 | WorkList.push_back(SuccDep.getSUnit()); |
593 | } |
594 | } |
595 | } while (!WorkList.empty()); |
596 | } |
597 | |
598 | std::vector<int> ScheduleDAGTopologicalSort::GetSubGraph(const SUnit &StartSU, |
599 | const SUnit &TargetSU, |
600 | bool &Success) { |
601 | std::vector<const SUnit*> WorkList; |
602 | int LowerBound = Node2Index[StartSU.NodeNum]; |
603 | int UpperBound = Node2Index[TargetSU.NodeNum]; |
604 | bool Found = false; |
605 | BitVector VisitedBack; |
606 | std::vector<int> Nodes; |
607 | |
608 | if (LowerBound > UpperBound) { |
609 | Success = false; |
610 | return Nodes; |
611 | } |
612 | |
613 | WorkList.reserve(SUnits.size()); |
614 | Visited.reset(); |
615 | |
616 | // Starting from StartSU, visit all successors up |
617 | // to UpperBound. |
618 | WorkList.push_back(&StartSU); |
619 | do { |
620 | const SUnit *SU = WorkList.back(); |
621 | WorkList.pop_back(); |
622 | for (int I = SU->Succs.size()-1; I >= 0; --I) { |
623 | const SUnit *Succ = SU->Succs[I].getSUnit(); |
624 | unsigned s = Succ->NodeNum; |
625 | // Edges to non-SUnits are allowed but ignored (e.g. ExitSU). |
626 | if (Succ->isBoundaryNode()) |
627 | continue; |
628 | if (Node2Index[s] == UpperBound) { |
629 | Found = true; |
630 | continue; |
631 | } |
632 | // Visit successors if not already and in affected region. |
633 | if (!Visited.test(s) && Node2Index[s] < UpperBound) { |
634 | Visited.set(s); |
635 | WorkList.push_back(Succ); |
636 | } |
637 | } |
638 | } while (!WorkList.empty()); |
639 | |
640 | if (!Found) { |
641 | Success = false; |
642 | return Nodes; |
643 | } |
644 | |
645 | WorkList.clear(); |
646 | VisitedBack.resize(SUnits.size()); |
647 | Found = false; |
648 | |
649 | // Starting from TargetSU, visit all predecessors up |
650 | // to LowerBound. SUs that are visited by the two |
651 | // passes are added to Nodes. |
652 | WorkList.push_back(&TargetSU); |
653 | do { |
654 | const SUnit *SU = WorkList.back(); |
655 | WorkList.pop_back(); |
656 | for (int I = SU->Preds.size()-1; I >= 0; --I) { |
657 | const SUnit *Pred = SU->Preds[I].getSUnit(); |
658 | unsigned s = Pred->NodeNum; |
659 | // Edges to non-SUnits are allowed but ignored (e.g. EntrySU). |
660 | if (Pred->isBoundaryNode()) |
661 | continue; |
662 | if (Node2Index[s] == LowerBound) { |
663 | Found = true; |
Value stored to 'Found' is never read | |
664 | continue; |
665 | } |
666 | if (!VisitedBack.test(s) && Visited.test(s)) { |
667 | VisitedBack.set(s); |
668 | WorkList.push_back(Pred); |
669 | Nodes.push_back(s); |
670 | } |
671 | } |
672 | } while (!WorkList.empty()); |
673 | |
674 | assert(Found && "Error in SUnit Graph!")((void)0); |
675 | Success = true; |
676 | return Nodes; |
677 | } |
678 | |
679 | void ScheduleDAGTopologicalSort::Shift(BitVector& Visited, int LowerBound, |
680 | int UpperBound) { |
681 | std::vector<int> L; |
682 | int shift = 0; |
683 | int i; |
684 | |
685 | for (i = LowerBound; i <= UpperBound; ++i) { |
686 | // w is node at topological index i. |
687 | int w = Index2Node[i]; |
688 | if (Visited.test(w)) { |
689 | // Unmark. |
690 | Visited.reset(w); |
691 | L.push_back(w); |
692 | shift = shift + 1; |
693 | } else { |
694 | Allocate(w, i - shift); |
695 | } |
696 | } |
697 | |
698 | for (unsigned LI : L) { |
699 | Allocate(LI, i - shift); |
700 | i = i + 1; |
701 | } |
702 | } |
703 | |
704 | bool ScheduleDAGTopologicalSort::WillCreateCycle(SUnit *TargetSU, SUnit *SU) { |
705 | FixOrder(); |
706 | // Is SU reachable from TargetSU via successor edges? |
707 | if (IsReachable(SU, TargetSU)) |
708 | return true; |
709 | for (const SDep &PredDep : TargetSU->Preds) |
710 | if (PredDep.isAssignedRegDep() && |
711 | IsReachable(SU, PredDep.getSUnit())) |
712 | return true; |
713 | return false; |
714 | } |
715 | |
716 | void ScheduleDAGTopologicalSort::AddSUnitWithoutPredecessors(const SUnit *SU) { |
717 | assert(SU->NodeNum == Index2Node.size() && "Node cannot be added at the end")((void)0); |
718 | assert(SU->NumPreds == 0 && "Can only add SU's with no predecessors")((void)0); |
719 | Node2Index.push_back(Index2Node.size()); |
720 | Index2Node.push_back(SU->NodeNum); |
721 | Visited.resize(Node2Index.size()); |
722 | } |
723 | |
724 | bool ScheduleDAGTopologicalSort::IsReachable(const SUnit *SU, |
725 | const SUnit *TargetSU) { |
726 | FixOrder(); |
727 | // If insertion of the edge SU->TargetSU would create a cycle |
728 | // then there is a path from TargetSU to SU. |
729 | int UpperBound, LowerBound; |
730 | LowerBound = Node2Index[TargetSU->NodeNum]; |
731 | UpperBound = Node2Index[SU->NodeNum]; |
732 | bool HasLoop = false; |
733 | // Is Ord(TargetSU) < Ord(SU) ? |
734 | if (LowerBound < UpperBound) { |
735 | Visited.reset(); |
736 | // There may be a path from TargetSU to SU. Check for it. |
737 | DFS(TargetSU, UpperBound, HasLoop); |
738 | } |
739 | return HasLoop; |
740 | } |
741 | |
742 | void ScheduleDAGTopologicalSort::Allocate(int n, int index) { |
743 | Node2Index[n] = index; |
744 | Index2Node[index] = n; |
745 | } |
746 | |
747 | ScheduleDAGTopologicalSort:: |
748 | ScheduleDAGTopologicalSort(std::vector<SUnit> &sunits, SUnit *exitsu) |
749 | : SUnits(sunits), ExitSU(exitsu) {} |
750 | |
751 | ScheduleHazardRecognizer::~ScheduleHazardRecognizer() = default; |