1//===-- LegalizeTypes.cpp - Common code for DAG type legalizer ------------===//
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// This file implements the SelectionDAG::LegalizeTypes method. It transforms
10// an arbitrary well-formed SelectionDAG to only consist of legal types. This
11// is common code shared among the LegalizeTypes*.cpp files.
12//
13//===----------------------------------------------------------------------===//
14
15#include "LegalizeTypes.h"
16#include "llvm/ADT/SetVector.h"
17#include "llvm/IR/DataLayout.h"
18#include "llvm/Support/CommandLine.h"
19#include "llvm/Support/ErrorHandling.h"
20#include "llvm/Support/raw_ostream.h"
21using namespace llvm;
22
23#define DEBUG_TYPE "legalize-types"
24
25static cl::opt<bool>
26EnableExpensiveChecks("enable-legalize-types-checking", cl::Hidden);
27
28/// Do extensive, expensive, basic correctness checking.
29void DAGTypeLegalizer::PerformExpensiveChecks() {
30 // If a node is not processed, then none of its values should be mapped by any
31 // of PromotedIntegers, ExpandedIntegers, ..., ReplacedValues.
32
33 // If a node is processed, then each value with an illegal type must be mapped
34 // by exactly one of PromotedIntegers, ExpandedIntegers, ..., ReplacedValues.
35 // Values with a legal type may be mapped by ReplacedValues, but not by any of
36 // the other maps.
37
38 // Note that these invariants may not hold momentarily when processing a node:
39 // the node being processed may be put in a map before being marked Processed.
40
41 // Note that it is possible to have nodes marked NewNode in the DAG. This can
42 // occur in two ways. Firstly, a node may be created during legalization but
43 // never passed to the legalization core. This is usually due to the implicit
44 // folding that occurs when using the DAG.getNode operators. Secondly, a new
45 // node may be passed to the legalization core, but when analyzed may morph
46 // into a different node, leaving the original node as a NewNode in the DAG.
47 // A node may morph if one of its operands changes during analysis. Whether
48 // it actually morphs or not depends on whether, after updating its operands,
49 // it is equivalent to an existing node: if so, it morphs into that existing
50 // node (CSE). An operand can change during analysis if the operand is a new
51 // node that morphs, or it is a processed value that was mapped to some other
52 // value (as recorded in ReplacedValues) in which case the operand is turned
53 // into that other value. If a node morphs then the node it morphed into will
54 // be used instead of it for legalization, however the original node continues
55 // to live on in the DAG.
56 // The conclusion is that though there may be nodes marked NewNode in the DAG,
57 // all uses of such nodes are also marked NewNode: the result is a fungus of
58 // NewNodes growing on top of the useful nodes, and perhaps using them, but
59 // not used by them.
60
61 // If a value is mapped by ReplacedValues, then it must have no uses, except
62 // by nodes marked NewNode (see above).
63
64 // The final node obtained by mapping by ReplacedValues is not marked NewNode.
65 // Note that ReplacedValues should be applied iteratively.
66
67 // Note that the ReplacedValues map may also map deleted nodes (by iterating
68 // over the DAG we never dereference deleted nodes). This means that it may
69 // also map nodes marked NewNode if the deallocated memory was reallocated as
70 // another node, and that new node was not seen by the LegalizeTypes machinery
71 // (for example because it was created but not used). In general, we cannot
72 // distinguish between new nodes and deleted nodes.
73 SmallVector<SDNode*, 16> NewNodes;
74 for (SDNode &Node : DAG.allnodes()) {
75 // Remember nodes marked NewNode - they are subject to extra checking below.
76 if (Node.getNodeId() == NewNode)
77 NewNodes.push_back(Elt: &Node);
78
79 for (unsigned i = 0, e = Node.getNumValues(); i != e; ++i) {
80 SDValue Res(&Node, i);
81 bool Failed = false;
82 // Don't create a value in map.
83 auto ResId = ValueToIdMap.lookup(Val: Res);
84
85 unsigned Mapped = 0;
86 if (ResId) {
87 auto I = ReplacedValues.find(Val: ResId);
88 if (I != ReplacedValues.end()) {
89 Mapped |= 1;
90 // Check that remapped values are only used by nodes marked NewNode.
91 for (SDUse &U : Node.uses())
92 if (U.getResNo() == i)
93 assert(U.getUser()->getNodeId() == NewNode &&
94 "Remapped value has non-trivial use!");
95
96 // Check that the final result of applying ReplacedValues is not
97 // marked NewNode.
98 auto NewValId = I->second;
99 I = ReplacedValues.find(Val: NewValId);
100 while (I != ReplacedValues.end()) {
101 NewValId = I->second;
102 I = ReplacedValues.find(Val: NewValId);
103 }
104 SDValue NewVal = getSDValue(Id&: NewValId);
105 (void)NewVal;
106 assert(NewVal.getNode()->getNodeId() != NewNode &&
107 "ReplacedValues maps to a new node!");
108 }
109 if (PromotedIntegers.count(Val: ResId))
110 Mapped |= 2;
111 if (SoftenedFloats.count(Val: ResId))
112 Mapped |= 4;
113 if (ScalarizedVectors.count(Val: ResId))
114 Mapped |= 8;
115 if (ExpandedIntegers.count(Val: ResId))
116 Mapped |= 16;
117 if (ExpandedFloats.count(Val: ResId))
118 Mapped |= 32;
119 if (SplitVectors.count(Val: ResId))
120 Mapped |= 64;
121 if (WidenedVectors.count(Val: ResId))
122 Mapped |= 128;
123 if (PromotedFloats.count(Val: ResId))
124 Mapped |= 256;
125 if (SoftPromotedHalfs.count(Val: ResId))
126 Mapped |= 512;
127 }
128
129 if (Node.getNodeId() != Processed) {
130 // Since we allow ReplacedValues to map deleted nodes, it may map nodes
131 // marked NewNode too, since a deleted node may have been reallocated as
132 // another node that has not been seen by the LegalizeTypes machinery.
133 if ((Node.getNodeId() == NewNode && Mapped > 1) ||
134 (Node.getNodeId() != NewNode && Mapped != 0)) {
135 dbgs() << "Unprocessed value in a map!";
136 Failed = true;
137 }
138 } else if (isTypeLegal(VT: Res.getValueType()) || IgnoreNodeResults(N: &Node)) {
139 if (Mapped > 1) {
140 dbgs() << "Value with legal type was transformed!";
141 Failed = true;
142 }
143 } else {
144 if (Mapped == 0) {
145 SDValue NodeById = IdToValueMap.lookup(Val: ResId);
146 // It is possible the node has been remapped to another node and had
147 // its Id updated in the Value to Id table. The node it remapped to
148 // may not have been processed yet. Look up the Id in the Id to Value
149 // table and re-check the Processed state. If the node hasn't been
150 // remapped we'll get the same state as we got earlier.
151 if (NodeById->getNodeId() == Processed) {
152 dbgs() << "Processed value not in any map!";
153 Failed = true;
154 }
155 } else if (Mapped & (Mapped - 1)) {
156 dbgs() << "Value in multiple maps!";
157 Failed = true;
158 }
159 }
160
161 if (Failed) {
162 if (Mapped & 1)
163 dbgs() << " ReplacedValues";
164 if (Mapped & 2)
165 dbgs() << " PromotedIntegers";
166 if (Mapped & 4)
167 dbgs() << " SoftenedFloats";
168 if (Mapped & 8)
169 dbgs() << " ScalarizedVectors";
170 if (Mapped & 16)
171 dbgs() << " ExpandedIntegers";
172 if (Mapped & 32)
173 dbgs() << " ExpandedFloats";
174 if (Mapped & 64)
175 dbgs() << " SplitVectors";
176 if (Mapped & 128)
177 dbgs() << " WidenedVectors";
178 if (Mapped & 256)
179 dbgs() << " PromotedFloats";
180 if (Mapped & 512)
181 dbgs() << " SoftPromoteHalfs";
182 dbgs() << "\n";
183 llvm_unreachable(nullptr);
184 }
185 }
186 }
187
188#ifndef NDEBUG
189 // Checked that NewNodes are only used by other NewNodes.
190 for (SDNode *N : NewNodes) {
191 for (SDNode *U : N->users())
192 assert(U->getNodeId() == NewNode && "NewNode used by non-NewNode!");
193 }
194#endif
195}
196
197/// This is the main entry point for the type legalizer. This does a top-down
198/// traversal of the dag, legalizing types as it goes. Returns "true" if it made
199/// any changes.
200bool DAGTypeLegalizer::run() {
201 bool Changed = false;
202
203 // Create a dummy node (which is not added to allnodes), that adds a reference
204 // to the root node, preventing it from being deleted, and tracking any
205 // changes of the root.
206 HandleSDNode Dummy(DAG.getRoot());
207 Dummy.setNodeId(Unanalyzed);
208
209 // The root of the dag may dangle to deleted nodes until the type legalizer is
210 // done. Set it to null to avoid confusion.
211 DAG.setRoot(SDValue());
212
213 // Walk all nodes in the graph, assigning them a NodeId of 'ReadyToProcess'
214 // (and remembering them) if they are leaves and assigning 'Unanalyzed' if
215 // non-leaves.
216 for (SDNode &Node : DAG.allnodes()) {
217 if (Node.getNumOperands() == 0) {
218 Node.setNodeId(ReadyToProcess);
219 Worklist.push_back(Elt: &Node);
220 } else {
221 Node.setNodeId(Unanalyzed);
222 }
223 }
224
225 // Now that we have a set of nodes to process, handle them all.
226 while (!Worklist.empty()) {
227#ifndef EXPENSIVE_CHECKS
228 if (EnableExpensiveChecks)
229#endif
230 PerformExpensiveChecks();
231
232 SDNode *N = Worklist.pop_back_val();
233 assert(N->getNodeId() == ReadyToProcess &&
234 "Node should be ready if on worklist!");
235
236 // Preserve fast math flags
237 SDNodeFlags FastMathFlags = N->getFlags() & SDNodeFlags::FastMathFlags;
238 SelectionDAG::FlagInserter FlagsInserter(DAG, FastMathFlags);
239
240 LLVM_DEBUG(dbgs() << "\nLegalizing node: "; N->dump(&DAG));
241 if (IgnoreNodeResults(N)) {
242 LLVM_DEBUG(dbgs() << "Ignoring node results\n");
243 goto ScanOperands;
244 }
245
246 // Scan the values produced by the node, checking to see if any result
247 // types are illegal.
248 for (unsigned i = 0, NumResults = N->getNumValues(); i < NumResults; ++i) {
249 EVT ResultVT = N->getValueType(ResNo: i);
250 LLVM_DEBUG(dbgs() << "Analyzing result type: " << ResultVT << "\n");
251 switch (getTypeAction(VT: ResultVT)) {
252 case TargetLowering::TypeLegal:
253 LLVM_DEBUG(dbgs() << "Legal result type\n");
254 break;
255 case TargetLowering::TypeScalarizeScalableVector:
256 report_fatal_error(
257 reason: "Scalarization of scalable vectors is not supported.");
258 // The following calls must take care of *all* of the node's results,
259 // not just the illegal result they were passed (this includes results
260 // with a legal type). Results can be remapped using ReplaceValueWith,
261 // or their promoted/expanded/etc values registered in PromotedIntegers,
262 // ExpandedIntegers etc.
263 case TargetLowering::TypePromoteInteger:
264 PromoteIntegerResult(N, ResNo: i);
265 Changed = true;
266 goto NodeDone;
267 case TargetLowering::TypeExpandInteger:
268 ExpandIntegerResult(N, ResNo: i);
269 Changed = true;
270 goto NodeDone;
271 case TargetLowering::TypeSoftenFloat:
272 SoftenFloatResult(N, ResNo: i);
273 Changed = true;
274 goto NodeDone;
275 case TargetLowering::TypeExpandFloat:
276 ExpandFloatResult(N, ResNo: i);
277 Changed = true;
278 goto NodeDone;
279 case TargetLowering::TypeScalarizeVector:
280 ScalarizeVectorResult(N, ResNo: i);
281 Changed = true;
282 goto NodeDone;
283 case TargetLowering::TypeSplitVector:
284 SplitVectorResult(N, ResNo: i);
285 Changed = true;
286 goto NodeDone;
287 case TargetLowering::TypeWidenVector:
288 WidenVectorResult(N, ResNo: i);
289 Changed = true;
290 goto NodeDone;
291 case TargetLowering::TypePromoteFloat:
292 PromoteFloatResult(N, ResNo: i);
293 Changed = true;
294 goto NodeDone;
295 case TargetLowering::TypeSoftPromoteHalf:
296 SoftPromoteHalfResult(N, ResNo: i);
297 Changed = true;
298 goto NodeDone;
299 }
300 }
301
302ScanOperands:
303 // Scan the operand list for the node, handling any nodes with operands that
304 // are illegal.
305 {
306 unsigned NumOperands = N->getNumOperands();
307 bool NeedsReanalyzing = false;
308 unsigned i;
309 for (i = 0; i != NumOperands; ++i) {
310 if (IgnoreNodeResults(N: N->getOperand(Num: i).getNode()))
311 continue;
312
313 const auto &Op = N->getOperand(Num: i);
314 LLVM_DEBUG(dbgs() << "Analyzing operand: "; Op.dump(&DAG));
315 EVT OpVT = Op.getValueType();
316 switch (getTypeAction(VT: OpVT)) {
317 case TargetLowering::TypeLegal:
318 LLVM_DEBUG(dbgs() << "Legal operand\n");
319 continue;
320 case TargetLowering::TypeScalarizeScalableVector:
321 report_fatal_error(
322 reason: "Scalarization of scalable vectors is not supported.");
323 // The following calls must either replace all of the node's results
324 // using ReplaceValueWith, and return "false"; or update the node's
325 // operands in place, and return "true".
326 case TargetLowering::TypePromoteInteger:
327 NeedsReanalyzing = PromoteIntegerOperand(N, OpNo: i);
328 Changed = true;
329 break;
330 case TargetLowering::TypeExpandInteger:
331 NeedsReanalyzing = ExpandIntegerOperand(N, OpNo: i);
332 Changed = true;
333 break;
334 case TargetLowering::TypeSoftenFloat:
335 NeedsReanalyzing = SoftenFloatOperand(N, OpNo: i);
336 Changed = true;
337 break;
338 case TargetLowering::TypeExpandFloat:
339 NeedsReanalyzing = ExpandFloatOperand(N, OpNo: i);
340 Changed = true;
341 break;
342 case TargetLowering::TypeScalarizeVector:
343 NeedsReanalyzing = ScalarizeVectorOperand(N, OpNo: i);
344 Changed = true;
345 break;
346 case TargetLowering::TypeSplitVector:
347 NeedsReanalyzing = SplitVectorOperand(N, OpNo: i);
348 Changed = true;
349 break;
350 case TargetLowering::TypeWidenVector:
351 NeedsReanalyzing = WidenVectorOperand(N, OpNo: i);
352 Changed = true;
353 break;
354 case TargetLowering::TypePromoteFloat:
355 NeedsReanalyzing = PromoteFloatOperand(N, OpNo: i);
356 Changed = true;
357 break;
358 case TargetLowering::TypeSoftPromoteHalf:
359 NeedsReanalyzing = SoftPromoteHalfOperand(N, OpNo: i);
360 Changed = true;
361 break;
362 }
363 break;
364 }
365
366 // The sub-method updated N in place. Check to see if any operands are new,
367 // and if so, mark them. If the node needs revisiting, don't add all users
368 // to the worklist etc.
369 if (NeedsReanalyzing) {
370 assert(N->getNodeId() == ReadyToProcess && "Node ID recalculated?");
371
372 N->setNodeId(NewNode);
373 // Recompute the NodeId and correct processed operands, adding the node to
374 // the worklist if ready.
375 SDNode *M = AnalyzeNewNode(N);
376 if (M == N)
377 // The node didn't morph - nothing special to do, it will be revisited.
378 continue;
379
380 // The node morphed - this is equivalent to legalizing by replacing every
381 // value of N with the corresponding value of M. So do that now.
382 assert(N->getNumValues() == M->getNumValues() &&
383 "Node morphing changed the number of results!");
384 for (unsigned i = 0, e = N->getNumValues(); i != e; ++i)
385 // Replacing the value takes care of remapping the new value.
386 ReplaceValueWith(From: SDValue(N, i), To: SDValue(M, i));
387 assert(N->getNodeId() == NewNode && "Unexpected node state!");
388 // The node continues to live on as part of the NewNode fungus that
389 // grows on top of the useful nodes. Nothing more needs to be done
390 // with it - move on to the next node.
391 continue;
392 }
393
394 if (i == NumOperands) {
395 LLVM_DEBUG(dbgs() << "Legally typed node: "; N->dump(&DAG));
396 }
397 }
398NodeDone:
399
400 // If we reach here, the node was processed, potentially creating new nodes.
401 // Mark it as processed and add its users to the worklist as appropriate.
402 assert(N->getNodeId() == ReadyToProcess && "Node ID recalculated?");
403 N->setNodeId(Processed);
404
405 for (SDNode *User : N->users()) {
406 int NodeId = User->getNodeId();
407
408 // This node has two options: it can either be a new node or its Node ID
409 // may be a count of the number of operands it has that are not ready.
410 if (NodeId > 0) {
411 User->setNodeId(NodeId-1);
412
413 // If this was the last use it was waiting on, add it to the ready list.
414 if (NodeId-1 == ReadyToProcess)
415 Worklist.push_back(Elt: User);
416 continue;
417 }
418
419 // If this is an unreachable new node, then ignore it. If it ever becomes
420 // reachable by being used by a newly created node then it will be handled
421 // by AnalyzeNewNode.
422 if (NodeId == NewNode)
423 continue;
424
425 // Otherwise, this node is new: this is the first operand of it that
426 // became ready. Its new NodeId is the number of operands it has minus 1
427 // (as this node is now processed).
428 assert(NodeId == Unanalyzed && "Unknown node ID!");
429 User->setNodeId(User->getNumOperands() - 1);
430
431 // If the node only has a single operand, it is now ready.
432 if (User->getNumOperands() == 1)
433 Worklist.push_back(Elt: User);
434 }
435 }
436
437#ifndef EXPENSIVE_CHECKS
438 if (EnableExpensiveChecks)
439#endif
440 PerformExpensiveChecks();
441
442 // If the root changed (e.g. it was a dead load) update the root.
443 DAG.setRoot(Dummy.getValue());
444
445 // Remove dead nodes. This is important to do for cleanliness but also before
446 // the checking loop below. Implicit folding by the DAG.getNode operators and
447 // node morphing can cause unreachable nodes to be around with their flags set
448 // to new.
449 DAG.RemoveDeadNodes();
450
451 // In a debug build, scan all the nodes to make sure we found them all. This
452 // ensures that there are no cycles and that everything got processed.
453#ifndef NDEBUG
454 for (SDNode &Node : DAG.allnodes()) {
455 bool Failed = false;
456
457 // Check that all result types are legal.
458 if (!IgnoreNodeResults(&Node))
459 for (unsigned i = 0, NumVals = Node.getNumValues(); i < NumVals; ++i)
460 if (!isTypeLegal(Node.getValueType(i))) {
461 dbgs() << "Result type " << i << " illegal: ";
462 Node.dump(&DAG);
463 Failed = true;
464 }
465
466 // Check that all operand types are legal.
467 for (unsigned i = 0, NumOps = Node.getNumOperands(); i < NumOps; ++i)
468 if (!IgnoreNodeResults(Node.getOperand(i).getNode()) &&
469 !isTypeLegal(Node.getOperand(i).getValueType())) {
470 dbgs() << "Operand type " << i << " illegal: ";
471 Node.getOperand(i).dump(&DAG);
472 Failed = true;
473 }
474
475 if (Node.getNodeId() != Processed) {
476 if (Node.getNodeId() == NewNode)
477 dbgs() << "New node not analyzed?\n";
478 else if (Node.getNodeId() == Unanalyzed)
479 dbgs() << "Unanalyzed node not noticed?\n";
480 else if (Node.getNodeId() > 0)
481 dbgs() << "Operand not processed?\n";
482 else if (Node.getNodeId() == ReadyToProcess)
483 dbgs() << "Not added to worklist?\n";
484 Failed = true;
485 }
486
487 if (Failed) {
488 Node.dump(&DAG); dbgs() << "\n";
489 llvm_unreachable(nullptr);
490 }
491 }
492#endif
493
494 return Changed;
495}
496
497/// The specified node is the root of a subtree of potentially new nodes.
498/// Correct any processed operands (this may change the node) and calculate the
499/// NodeId. If the node itself changes to a processed node, it is not remapped -
500/// the caller needs to take care of this. Returns the potentially changed node.
501SDNode *DAGTypeLegalizer::AnalyzeNewNode(SDNode *N) {
502 // If this was an existing node that is already done, we're done.
503 if (N->getNodeId() != NewNode && N->getNodeId() != Unanalyzed)
504 return N;
505
506 // Okay, we know that this node is new. Recursively walk all of its operands
507 // to see if they are new also. The depth of this walk is bounded by the size
508 // of the new tree that was constructed (usually 2-3 nodes), so we don't worry
509 // about revisiting of nodes.
510 //
511 // As we walk the operands, keep track of the number of nodes that are
512 // processed. If non-zero, this will become the new nodeid of this node.
513 // Operands may morph when they are analyzed. If so, the node will be
514 // updated after all operands have been analyzed. Since this is rare,
515 // the code tries to minimize overhead in the non-morphing case.
516
517 std::vector<SDValue> NewOps;
518 unsigned NumProcessed = 0;
519 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
520 SDValue OrigOp = N->getOperand(Num: i);
521 SDValue Op = OrigOp;
522
523 AnalyzeNewValue(Val&: Op); // Op may morph.
524
525 if (Op.getNode()->getNodeId() == Processed)
526 ++NumProcessed;
527
528 if (!NewOps.empty()) {
529 // Some previous operand changed. Add this one to the list.
530 NewOps.push_back(x: Op);
531 } else if (Op != OrigOp) {
532 // This is the first operand to change - add all operands so far.
533 llvm::append_range(C&: NewOps, R: N->ops().take_front(N: i));
534 NewOps.push_back(x: Op);
535 }
536 }
537
538 // Some operands changed - update the node.
539 if (!NewOps.empty()) {
540 SDNode *M = DAG.UpdateNodeOperands(N, Ops: NewOps);
541 if (M != N) {
542 // The node morphed into a different node. Normally for this to happen
543 // the original node would have to be marked NewNode. However this can
544 // in theory momentarily not be the case while ReplaceValueWith is doing
545 // its stuff. Mark the original node NewNode to help basic correctness
546 // checking.
547 N->setNodeId(NewNode);
548 if (M->getNodeId() != NewNode && M->getNodeId() != Unanalyzed)
549 // It morphed into a previously analyzed node - nothing more to do.
550 return M;
551
552 // It morphed into a different new node. Do the equivalent of passing
553 // it to AnalyzeNewNode: expunge it and calculate the NodeId. No need
554 // to remap the operands, since they are the same as the operands we
555 // remapped above.
556 N = M;
557 }
558 }
559
560 // Calculate the NodeId.
561 N->setNodeId(N->getNumOperands() - NumProcessed);
562 if (N->getNodeId() == ReadyToProcess)
563 Worklist.push_back(Elt: N);
564
565 return N;
566}
567
568/// Call AnalyzeNewNode, updating the node in Val if needed.
569/// If the node changes to a processed node, then remap it.
570void DAGTypeLegalizer::AnalyzeNewValue(SDValue &Val) {
571 Val.setNode(AnalyzeNewNode(N: Val.getNode()));
572 if (Val.getNode()->getNodeId() == Processed)
573 // We were passed a processed node, or it morphed into one - remap it.
574 RemapValue(V&: Val);
575}
576
577/// If the specified value was already legalized to another value,
578/// replace it by that value.
579void DAGTypeLegalizer::RemapValue(SDValue &V) {
580 auto Id = getTableId(V);
581 V = getSDValue(Id);
582}
583
584void DAGTypeLegalizer::RemapId(TableId &Id) {
585 auto I = ReplacedValues.find(Val: Id);
586 if (I != ReplacedValues.end()) {
587 assert(Id != I->second && "Id is mapped to itself.");
588 // Use path compression to speed up future lookups if values get multiply
589 // replaced with other values.
590 RemapId(Id&: I->second);
591 Id = I->second;
592
593 // Note that N = IdToValueMap[Id] it is possible to have
594 // N.getNode()->getNodeId() == NewNode at this point because it is possible
595 // for a node to be put in the map before being processed.
596 }
597}
598
599namespace {
600 /// This class is a DAGUpdateListener that listens for updates to nodes and
601 /// recomputes their ready state.
602 class NodeUpdateListener : public SelectionDAG::DAGUpdateListener {
603 DAGTypeLegalizer &DTL;
604 SmallSetVector<SDNode*, 16> &NodesToAnalyze;
605 public:
606 explicit NodeUpdateListener(DAGTypeLegalizer &dtl,
607 SmallSetVector<SDNode*, 16> &nta)
608 : SelectionDAG::DAGUpdateListener(dtl.getDAG()),
609 DTL(dtl), NodesToAnalyze(nta) {}
610
611 void NodeDeleted(SDNode *N, SDNode *E) override {
612 assert(N->getNodeId() != DAGTypeLegalizer::ReadyToProcess &&
613 N->getNodeId() != DAGTypeLegalizer::Processed &&
614 "Invalid node ID for RAUW deletion!");
615 // It is possible, though rare, for the deleted node N to occur as a
616 // target in a map, so note the replacement N -> E in ReplacedValues.
617 assert(E && "Node not replaced?");
618 DTL.NoteDeletion(Old: N, New: E);
619
620 // In theory the deleted node could also have been scheduled for analysis.
621 // So remove it from the set of nodes which will be analyzed.
622 NodesToAnalyze.remove(X: N);
623
624 // In general nothing needs to be done for E, since it didn't change but
625 // only gained new uses. However N -> E was just added to ReplacedValues,
626 // and the result of a ReplacedValues mapping is not allowed to be marked
627 // NewNode. So if E is marked NewNode, then it needs to be analyzed.
628 if (E->getNodeId() == DAGTypeLegalizer::NewNode)
629 NodesToAnalyze.insert(X: E);
630 }
631
632 void NodeUpdated(SDNode *N) override {
633 // Node updates can mean pretty much anything. It is possible that an
634 // operand was set to something already processed (f.e.) in which case
635 // this node could become ready. Recompute its flags.
636 assert(N->getNodeId() != DAGTypeLegalizer::ReadyToProcess &&
637 N->getNodeId() != DAGTypeLegalizer::Processed &&
638 "Invalid node ID for RAUW deletion!");
639 N->setNodeId(DAGTypeLegalizer::NewNode);
640 NodesToAnalyze.insert(X: N);
641 }
642 };
643}
644
645
646/// The specified value was legalized to the specified other value.
647/// Update the DAG and NodeIds replacing any uses of From to use To instead.
648void DAGTypeLegalizer::ReplaceValueWith(SDValue From, SDValue To) {
649 assert(From.getNode() != To.getNode() && "Potential legalization loop!");
650
651 // If expansion produced new nodes, make sure they are properly marked.
652 AnalyzeNewValue(Val&: To);
653
654 // Anything that used the old node should now use the new one. Note that this
655 // can potentially cause recursive merging.
656 SmallSetVector<SDNode*, 16> NodesToAnalyze;
657 NodeUpdateListener NUL(*this, NodesToAnalyze);
658 do {
659
660 // The old node may be present in a map like ExpandedIntegers or
661 // PromotedIntegers. Inform maps about the replacement.
662 auto FromId = getTableId(V: From);
663 auto ToId = getTableId(V: To);
664
665 if (FromId != ToId)
666 ReplacedValues[FromId] = ToId;
667 DAG.ReplaceAllUsesOfValueWith(From, To);
668
669 // Process the list of nodes that need to be reanalyzed.
670 while (!NodesToAnalyze.empty()) {
671 SDNode *N = NodesToAnalyze.pop_back_val();
672 if (N->getNodeId() != DAGTypeLegalizer::NewNode)
673 // The node was analyzed while reanalyzing an earlier node - it is safe
674 // to skip. Note that this is not a morphing node - otherwise it would
675 // still be marked NewNode.
676 continue;
677
678 // Analyze the node's operands and recalculate the node ID.
679 SDNode *M = AnalyzeNewNode(N);
680 if (M != N) {
681 // The node morphed into a different node. Make everyone use the new
682 // node instead.
683 assert(M->getNodeId() != NewNode && "Analysis resulted in NewNode!");
684 assert(N->getNumValues() == M->getNumValues() &&
685 "Node morphing changed the number of results!");
686 for (unsigned i = 0, e = N->getNumValues(); i != e; ++i) {
687 SDValue OldVal(N, i);
688 SDValue NewVal(M, i);
689 if (M->getNodeId() == Processed)
690 RemapValue(V&: NewVal);
691 // OldVal may be a target of the ReplacedValues map which was marked
692 // NewNode to force reanalysis because it was updated. Ensure that
693 // anything that ReplacedValues mapped to OldVal will now be mapped
694 // all the way to NewVal.
695 auto OldValId = getTableId(V: OldVal);
696 auto NewValId = getTableId(V: NewVal);
697 DAG.ReplaceAllUsesOfValueWith(From: OldVal, To: NewVal);
698 if (OldValId != NewValId)
699 ReplacedValues[OldValId] = NewValId;
700 }
701 // The original node continues to exist in the DAG, marked NewNode.
702 }
703 }
704 // When recursively update nodes with new nodes, it is possible to have
705 // new uses of From due to CSE. If this happens, replace the new uses of
706 // From with To.
707 } while (!From.use_empty());
708}
709
710void DAGTypeLegalizer::SetPromotedInteger(SDValue Op, SDValue Result) {
711 assert(Result.getValueType() ==
712 TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType()) &&
713 "Invalid type for promoted integer");
714 AnalyzeNewValue(Val&: Result);
715
716 auto &OpIdEntry = PromotedIntegers[getTableId(V: Op)];
717 assert((OpIdEntry == 0) && "Node is already promoted!");
718 OpIdEntry = getTableId(V: Result);
719
720 DAG.transferDbgValues(From: Op, To: Result);
721}
722
723void DAGTypeLegalizer::SetSoftenedFloat(SDValue Op, SDValue Result) {
724#ifndef NDEBUG
725 EVT VT = Result.getValueType();
726 LLVMContext &Ctx = *DAG.getContext();
727 assert((VT == EVT::getIntegerVT(Ctx, 80) ||
728 VT == TLI.getTypeToTransformTo(Ctx, Op.getValueType())) &&
729 "Invalid type for softened float");
730#endif
731 AnalyzeNewValue(Val&: Result);
732
733 auto &OpIdEntry = SoftenedFloats[getTableId(V: Op)];
734 assert((OpIdEntry == 0) && "Node is already converted to integer!");
735 OpIdEntry = getTableId(V: Result);
736}
737
738void DAGTypeLegalizer::SetPromotedFloat(SDValue Op, SDValue Result) {
739 assert(Result.getValueType() ==
740 TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType()) &&
741 "Invalid type for promoted float");
742 AnalyzeNewValue(Val&: Result);
743
744 auto &OpIdEntry = PromotedFloats[getTableId(V: Op)];
745 assert((OpIdEntry == 0) && "Node is already promoted!");
746 OpIdEntry = getTableId(V: Result);
747}
748
749void DAGTypeLegalizer::SetSoftPromotedHalf(SDValue Op, SDValue Result) {
750 assert(Result.getValueType() == MVT::i16 &&
751 "Invalid type for soft-promoted half");
752 AnalyzeNewValue(Val&: Result);
753
754 auto &OpIdEntry = SoftPromotedHalfs[getTableId(V: Op)];
755 assert((OpIdEntry == 0) && "Node is already promoted!");
756 OpIdEntry = getTableId(V: Result);
757}
758
759void DAGTypeLegalizer::SetScalarizedVector(SDValue Op, SDValue Result) {
760 // Note that in some cases vector operation operands may be greater than
761 // the vector element type. For example BUILD_VECTOR of type <1 x i1> with
762 // a constant i8 operand.
763
764 // We don't currently support the scalarization of scalable vector types.
765 assert(Result.getValueSizeInBits().getFixedValue() >=
766 Op.getScalarValueSizeInBits() &&
767 "Invalid type for scalarized vector");
768 AnalyzeNewValue(Val&: Result);
769
770 auto &OpIdEntry = ScalarizedVectors[getTableId(V: Op)];
771 assert((OpIdEntry == 0) && "Node is already scalarized!");
772 OpIdEntry = getTableId(V: Result);
773}
774
775void DAGTypeLegalizer::GetExpandedInteger(SDValue Op, SDValue &Lo,
776 SDValue &Hi) {
777 std::pair<TableId, TableId> &Entry = ExpandedIntegers[getTableId(V: Op)];
778 assert((Entry.first != 0) && "Operand isn't expanded");
779 Lo = getSDValue(Id&: Entry.first);
780 Hi = getSDValue(Id&: Entry.second);
781}
782
783void DAGTypeLegalizer::SetExpandedInteger(SDValue Op, SDValue Lo,
784 SDValue Hi) {
785 assert(Lo.getValueType() ==
786 TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType()) &&
787 Hi.getValueType() == Lo.getValueType() &&
788 "Invalid type for expanded integer");
789 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
790 AnalyzeNewValue(Val&: Lo);
791 AnalyzeNewValue(Val&: Hi);
792
793 // Transfer debug values. Don't invalidate the source debug value until it's
794 // been transferred to the high and low bits.
795 if (DAG.getDataLayout().isBigEndian()) {
796 DAG.transferDbgValues(From: Op, To: Hi, OffsetInBits: 0, SizeInBits: Hi.getValueSizeInBits(), InvalidateDbg: false);
797 DAG.transferDbgValues(From: Op, To: Lo, OffsetInBits: Hi.getValueSizeInBits(),
798 SizeInBits: Lo.getValueSizeInBits());
799 } else {
800 DAG.transferDbgValues(From: Op, To: Lo, OffsetInBits: 0, SizeInBits: Lo.getValueSizeInBits(), InvalidateDbg: false);
801 DAG.transferDbgValues(From: Op, To: Hi, OffsetInBits: Lo.getValueSizeInBits(),
802 SizeInBits: Hi.getValueSizeInBits());
803 }
804
805 // Remember that this is the result of the node.
806 std::pair<TableId, TableId> &Entry = ExpandedIntegers[getTableId(V: Op)];
807 assert((Entry.first == 0) && "Node already expanded");
808 Entry.first = getTableId(V: Lo);
809 Entry.second = getTableId(V: Hi);
810}
811
812void DAGTypeLegalizer::GetExpandedFloat(SDValue Op, SDValue &Lo,
813 SDValue &Hi) {
814 std::pair<TableId, TableId> &Entry = ExpandedFloats[getTableId(V: Op)];
815 assert((Entry.first != 0) && "Operand isn't expanded");
816 Lo = getSDValue(Id&: Entry.first);
817 Hi = getSDValue(Id&: Entry.second);
818}
819
820void DAGTypeLegalizer::SetExpandedFloat(SDValue Op, SDValue Lo,
821 SDValue Hi) {
822 assert(Lo.getValueType() ==
823 TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType()) &&
824 Hi.getValueType() == Lo.getValueType() &&
825 "Invalid type for expanded float");
826 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
827 AnalyzeNewValue(Val&: Lo);
828 AnalyzeNewValue(Val&: Hi);
829
830 std::pair<TableId, TableId> &Entry = ExpandedFloats[getTableId(V: Op)];
831 assert((Entry.first == 0) && "Node already expanded");
832 Entry.first = getTableId(V: Lo);
833 Entry.second = getTableId(V: Hi);
834}
835
836void DAGTypeLegalizer::GetSplitVector(SDValue Op, SDValue &Lo,
837 SDValue &Hi) {
838 std::pair<TableId, TableId> &Entry = SplitVectors[getTableId(V: Op)];
839 Lo = getSDValue(Id&: Entry.first);
840 Hi = getSDValue(Id&: Entry.second);
841 assert(Lo.getNode() && "Operand isn't split");
842 ;
843}
844
845void DAGTypeLegalizer::SetSplitVector(SDValue Op, SDValue Lo,
846 SDValue Hi) {
847 assert(Lo.getValueType().getVectorElementType() ==
848 Op.getValueType().getVectorElementType() &&
849 Lo.getValueType().getVectorElementCount() * 2 ==
850 Op.getValueType().getVectorElementCount() &&
851 Hi.getValueType() == Lo.getValueType() &&
852 "Invalid type for split vector");
853 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant.
854 AnalyzeNewValue(Val&: Lo);
855 AnalyzeNewValue(Val&: Hi);
856
857 // Remember that this is the result of the node.
858 std::pair<TableId, TableId> &Entry = SplitVectors[getTableId(V: Op)];
859 assert((Entry.first == 0) && "Node already split");
860 Entry.first = getTableId(V: Lo);
861 Entry.second = getTableId(V: Hi);
862}
863
864void DAGTypeLegalizer::SetWidenedVector(SDValue Op, SDValue Result) {
865 assert(Result.getValueType() ==
866 TLI.getTypeToTransformTo(*DAG.getContext(), Op.getValueType()) &&
867 "Invalid type for widened vector");
868 AnalyzeNewValue(Val&: Result);
869
870 auto &OpIdEntry = WidenedVectors[getTableId(V: Op)];
871 assert((OpIdEntry == 0) && "Node already widened!");
872 OpIdEntry = getTableId(V: Result);
873}
874
875
876//===----------------------------------------------------------------------===//
877// Utilities.
878//===----------------------------------------------------------------------===//
879
880/// Convert to an integer of the same size.
881SDValue DAGTypeLegalizer::BitConvertToInteger(SDValue Op) {
882 unsigned BitWidth = Op.getValueSizeInBits();
883 return DAG.getNode(Opcode: ISD::BITCAST, DL: SDLoc(Op),
884 VT: EVT::getIntegerVT(Context&: *DAG.getContext(), BitWidth), Operand: Op);
885}
886
887/// Convert to a vector of integers of the same size.
888SDValue DAGTypeLegalizer::BitConvertVectorToIntegerVector(SDValue Op) {
889 assert(Op.getValueType().isVector() && "Only applies to vectors!");
890 unsigned EltWidth = Op.getScalarValueSizeInBits();
891 EVT EltNVT = EVT::getIntegerVT(Context&: *DAG.getContext(), BitWidth: EltWidth);
892 auto EltCnt = Op.getValueType().getVectorElementCount();
893 return DAG.getNode(Opcode: ISD::BITCAST, DL: SDLoc(Op),
894 VT: EVT::getVectorVT(Context&: *DAG.getContext(), VT: EltNVT, EC: EltCnt), Operand: Op);
895}
896
897SDValue DAGTypeLegalizer::CreateStackStoreLoad(SDValue Op,
898 EVT DestVT) {
899 SDLoc dl(Op);
900 // Create the stack frame object. Make sure it is aligned for both
901 // the source and destination types.
902
903 // In cases where the vector is illegal it will be broken down into parts
904 // and stored in parts - we should use the alignment for the smallest part.
905 Align DestAlign = DAG.getReducedAlign(VT: DestVT, /*UseABI=*/false);
906 Align OpAlign = DAG.getReducedAlign(VT: Op.getValueType(), /*UseABI=*/false);
907 Align Align = std::max(a: DestAlign, b: OpAlign);
908 SDValue StackPtr =
909 DAG.CreateStackTemporary(Bytes: Op.getValueType().getStoreSize(), Alignment: Align);
910 // Emit a store to the stack slot.
911 SDValue Store = DAG.getStore(Chain: DAG.getEntryNode(), dl, Val: Op, Ptr: StackPtr,
912 PtrInfo: MachinePointerInfo(), Alignment: Align);
913 // Result is a load from the stack slot.
914 return DAG.getLoad(VT: DestVT, dl, Chain: Store, Ptr: StackPtr, PtrInfo: MachinePointerInfo(), Alignment: Align);
915}
916
917/// Replace the node's results with custom code provided by the target and
918/// return "true", or do nothing and return "false".
919/// The last parameter is FALSE if we are dealing with a node with legal
920/// result types and illegal operand. The second parameter denotes the type of
921/// illegal OperandNo in that case.
922/// The last parameter being TRUE means we are dealing with a
923/// node with illegal result types. The second parameter denotes the type of
924/// illegal ResNo in that case.
925bool DAGTypeLegalizer::CustomLowerNode(SDNode *N, EVT VT, bool LegalizeResult) {
926 // See if the target wants to custom lower this node.
927 if (TLI.getOperationAction(Op: N->getOpcode(), VT) != TargetLowering::Custom)
928 return false;
929
930 SmallVector<SDValue, 8> Results;
931 if (LegalizeResult)
932 TLI.ReplaceNodeResults(N, Results, DAG);
933 else
934 TLI.LowerOperationWrapper(N, Results, DAG);
935
936 if (Results.empty())
937 // The target didn't want to custom lower it after all.
938 return false;
939
940 // Make everything that once used N's values now use those in Results instead.
941 assert(Results.size() == N->getNumValues() &&
942 "Custom lowering returned the wrong number of results!");
943 for (unsigned i = 0, e = Results.size(); i != e; ++i) {
944 ReplaceValueWith(From: SDValue(N, i), To: Results[i]);
945 }
946 return true;
947}
948
949
950/// Widen the node's results with custom code provided by the target and return
951/// "true", or do nothing and return "false".
952bool DAGTypeLegalizer::CustomWidenLowerNode(SDNode *N, EVT VT) {
953 // See if the target wants to custom lower this node.
954 if (TLI.getOperationAction(Op: N->getOpcode(), VT) != TargetLowering::Custom)
955 return false;
956
957 SmallVector<SDValue, 8> Results;
958 TLI.ReplaceNodeResults(N, Results, DAG);
959
960 if (Results.empty())
961 // The target didn't want to custom widen lower its result after all.
962 return false;
963
964 // Update the widening map.
965 assert(Results.size() == N->getNumValues() &&
966 "Custom lowering returned the wrong number of results!");
967 for (unsigned i = 0, e = Results.size(); i != e; ++i) {
968 // If this is a chain output or already widened just replace it.
969 bool WasWidened = SDValue(N, i).getValueType() != Results[i].getValueType();
970 if (WasWidened)
971 SetWidenedVector(Op: SDValue(N, i), Result: Results[i]);
972 else
973 ReplaceValueWith(From: SDValue(N, i), To: Results[i]);
974 }
975 return true;
976}
977
978SDValue DAGTypeLegalizer::DisintegrateMERGE_VALUES(SDNode *N, unsigned ResNo) {
979 for (unsigned i = 0, e = N->getNumValues(); i != e; ++i)
980 if (i != ResNo)
981 ReplaceValueWith(From: SDValue(N, i), To: SDValue(N->getOperand(Num: i)));
982 return SDValue(N->getOperand(Num: ResNo));
983}
984
985/// Use ISD::EXTRACT_ELEMENT nodes to extract the low and high parts of the
986/// given value.
987void DAGTypeLegalizer::GetPairElements(SDValue Pair,
988 SDValue &Lo, SDValue &Hi) {
989 SDLoc dl(Pair);
990 EVT NVT = TLI.getTypeToTransformTo(Context&: *DAG.getContext(), VT: Pair.getValueType());
991 std::tie(args&: Lo, args&: Hi) = DAG.SplitScalar(N: Pair, DL: dl, LoVT: NVT, HiVT: NVT);
992}
993
994/// Build an integer with low bits Lo and high bits Hi.
995SDValue DAGTypeLegalizer::JoinIntegers(SDValue Lo, SDValue Hi) {
996 // Arbitrarily use dlHi for result SDLoc
997 SDLoc dlHi(Hi);
998 SDLoc dlLo(Lo);
999 EVT LVT = Lo.getValueType();
1000 EVT HVT = Hi.getValueType();
1001 EVT NVT = EVT::getIntegerVT(Context&: *DAG.getContext(),
1002 BitWidth: LVT.getSizeInBits() + HVT.getSizeInBits());
1003
1004 EVT ShiftAmtVT = TLI.getShiftAmountTy(LHSTy: NVT, DL: DAG.getDataLayout());
1005 Lo = DAG.getNode(Opcode: ISD::ZERO_EXTEND, DL: dlLo, VT: NVT, Operand: Lo);
1006 Hi = DAG.getNode(Opcode: ISD::ANY_EXTEND, DL: dlHi, VT: NVT, Operand: Hi);
1007 Hi = DAG.getNode(Opcode: ISD::SHL, DL: dlHi, VT: NVT, N1: Hi,
1008 N2: DAG.getConstant(Val: LVT.getSizeInBits(), DL: dlHi, VT: ShiftAmtVT));
1009 return DAG.getNode(Opcode: ISD::OR, DL: dlHi, VT: NVT, N1: Lo, N2: Hi);
1010}
1011
1012/// Promote the given target boolean to a target boolean of the given type.
1013/// A target boolean is an integer value, not necessarily of type i1, the bits
1014/// of which conform to getBooleanContents.
1015///
1016/// ValVT is the type of values that produced the boolean.
1017SDValue DAGTypeLegalizer::PromoteTargetBoolean(SDValue Bool, EVT ValVT) {
1018 return TLI.promoteTargetBoolean(DAG, Bool, ValVT);
1019}
1020
1021/// Return the lower LoVT bits of Op in Lo and the upper HiVT bits in Hi.
1022void DAGTypeLegalizer::SplitInteger(SDValue Op,
1023 EVT LoVT, EVT HiVT,
1024 SDValue &Lo, SDValue &Hi) {
1025 SDLoc dl(Op);
1026 assert(LoVT.getSizeInBits() + HiVT.getSizeInBits() ==
1027 Op.getValueSizeInBits() && "Invalid integer splitting!");
1028 Lo = DAG.getNode(Opcode: ISD::TRUNCATE, DL: dl, VT: LoVT, Operand: Op);
1029 unsigned ReqShiftAmountInBits =
1030 Log2_32_Ceil(Value: Op.getValueType().getSizeInBits());
1031 MVT ShiftAmountTy =
1032 TLI.getScalarShiftAmountTy(DAG.getDataLayout(), Op.getValueType());
1033 if (ReqShiftAmountInBits > ShiftAmountTy.getSizeInBits())
1034 ShiftAmountTy = MVT::getIntegerVT(BitWidth: NextPowerOf2(A: ReqShiftAmountInBits));
1035 Hi = DAG.getNode(Opcode: ISD::SRL, DL: dl, VT: Op.getValueType(), N1: Op,
1036 N2: DAG.getConstant(Val: LoVT.getSizeInBits(), DL: dl, VT: ShiftAmountTy));
1037 Hi = DAG.getNode(Opcode: ISD::TRUNCATE, DL: dl, VT: HiVT, Operand: Hi);
1038}
1039
1040/// Return the lower and upper halves of Op's bits in a value type half the
1041/// size of Op's.
1042void DAGTypeLegalizer::SplitInteger(SDValue Op,
1043 SDValue &Lo, SDValue &Hi) {
1044 EVT HalfVT =
1045 EVT::getIntegerVT(Context&: *DAG.getContext(), BitWidth: Op.getValueSizeInBits() / 2);
1046 SplitInteger(Op, LoVT: HalfVT, HiVT: HalfVT, Lo, Hi);
1047}
1048
1049
1050//===----------------------------------------------------------------------===//
1051// Entry Point
1052//===----------------------------------------------------------------------===//
1053
1054/// This transforms the SelectionDAG into a SelectionDAG that only uses types
1055/// natively supported by the target. Returns "true" if it made any changes.
1056///
1057/// Note that this is an involved process that may invalidate pointers into
1058/// the graph.
1059bool SelectionDAG::LegalizeTypes() {
1060 return DAGTypeLegalizer(*this).run();
1061}
1062