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comparison utils/TableGen/DAGISelMatcherOpt.cpp @ 0:95c75e76d11b LLVM3.4

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LLVM 3.4
author Kaito Tokumori <e105711@ie.u-ryukyu.ac.jp>
date Thu, 12 Dec 2013 13:56:28 +0900
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children 54457678186b
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-1:000000000000 0:95c75e76d11b
1 //===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the DAG Matcher optimizer.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #define DEBUG_TYPE "isel-opt"
15 #include "DAGISelMatcher.h"
16 #include "CodeGenDAGPatterns.h"
17 #include "llvm/ADT/DenseSet.h"
18 #include "llvm/ADT/StringSet.h"
19 #include "llvm/Support/Debug.h"
20 #include "llvm/Support/raw_ostream.h"
21 using namespace llvm;
22
23 /// ContractNodes - Turn multiple matcher node patterns like 'MoveChild+Record'
24 /// into single compound nodes like RecordChild.
25 static void ContractNodes(OwningPtr<Matcher> &MatcherPtr,
26 const CodeGenDAGPatterns &CGP) {
27 // If we reached the end of the chain, we're done.
28 Matcher *N = MatcherPtr.get();
29 if (N == 0) return;
30
31 // If we have a scope node, walk down all of the children.
32 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
33 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
34 OwningPtr<Matcher> Child(Scope->takeChild(i));
35 ContractNodes(Child, CGP);
36 Scope->resetChild(i, Child.take());
37 }
38 return;
39 }
40
41 // If we found a movechild node with a node that comes in a 'foochild' form,
42 // transform it.
43 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
44 Matcher *New = 0;
45 if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
46 if (MC->getChildNo() < 8) // Only have RecordChild0...7
47 New = new RecordChildMatcher(MC->getChildNo(), RM->getWhatFor(),
48 RM->getResultNo());
49
50 if (CheckTypeMatcher *CT = dyn_cast<CheckTypeMatcher>(MC->getNext()))
51 if (MC->getChildNo() < 8 && // Only have CheckChildType0...7
52 CT->getResNo() == 0) // CheckChildType checks res #0
53 New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
54
55 if (CheckSameMatcher *CS = dyn_cast<CheckSameMatcher>(MC->getNext()))
56 if (MC->getChildNo() < 4) // Only have CheckChildSame0...3
57 New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());
58
59 if (New) {
60 // Insert the new node.
61 New->setNext(MatcherPtr.take());
62 MatcherPtr.reset(New);
63 // Remove the old one.
64 MC->setNext(MC->getNext()->takeNext());
65 return ContractNodes(MatcherPtr, CGP);
66 }
67 }
68
69 // Zap movechild -> moveparent.
70 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
71 if (MoveParentMatcher *MP =
72 dyn_cast<MoveParentMatcher>(MC->getNext())) {
73 MatcherPtr.reset(MP->takeNext());
74 return ContractNodes(MatcherPtr, CGP);
75 }
76
77 // Turn EmitNode->MarkFlagResults->CompleteMatch into
78 // MarkFlagResults->EmitNode->CompleteMatch when we can to encourage
79 // MorphNodeTo formation. This is safe because MarkFlagResults never refers
80 // to the root of the pattern.
81 if (isa<EmitNodeMatcher>(N) && isa<MarkGlueResultsMatcher>(N->getNext()) &&
82 isa<CompleteMatchMatcher>(N->getNext()->getNext())) {
83 // Unlink the two nodes from the list.
84 Matcher *EmitNode = MatcherPtr.take();
85 Matcher *MFR = EmitNode->takeNext();
86 Matcher *Tail = MFR->takeNext();
87
88 // Relink them.
89 MatcherPtr.reset(MFR);
90 MFR->setNext(EmitNode);
91 EmitNode->setNext(Tail);
92 return ContractNodes(MatcherPtr, CGP);
93 }
94
95 // Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
96 if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
97 if (CompleteMatchMatcher *CM =
98 dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
99 // We can only use MorphNodeTo if the result values match up.
100 unsigned RootResultFirst = EN->getFirstResultSlot();
101 bool ResultsMatch = true;
102 for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
103 if (CM->getResult(i) != RootResultFirst+i)
104 ResultsMatch = false;
105
106 // If the selected node defines a subset of the glue/chain results, we
107 // can't use MorphNodeTo. For example, we can't use MorphNodeTo if the
108 // matched pattern has a chain but the root node doesn't.
109 const PatternToMatch &Pattern = CM->getPattern();
110
111 if (!EN->hasChain() &&
112 Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
113 ResultsMatch = false;
114
115 // If the matched node has glue and the output root doesn't, we can't
116 // use MorphNodeTo.
117 //
118 // NOTE: Strictly speaking, we don't have to check for glue here
119 // because the code in the pattern generator doesn't handle it right. We
120 // do it anyway for thoroughness.
121 if (!EN->hasOutFlag() &&
122 Pattern.getSrcPattern()->NodeHasProperty(SDNPOutGlue, CGP))
123 ResultsMatch = false;
124
125
126 // If the root result node defines more results than the source root node
127 // *and* has a chain or glue input, then we can't match it because it
128 // would end up replacing the extra result with the chain/glue.
129 #if 0
130 if ((EN->hasGlue() || EN->hasChain()) &&
131 EN->getNumNonChainGlueVTs() > ... need to get no results reliably ...)
132 ResultMatch = false;
133 #endif
134
135 if (ResultsMatch) {
136 const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
137 const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
138 MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
139 VTs.data(), VTs.size(),
140 Operands.data(),Operands.size(),
141 EN->hasChain(), EN->hasInFlag(),
142 EN->hasOutFlag(),
143 EN->hasMemRefs(),
144 EN->getNumFixedArityOperands(),
145 Pattern));
146 return;
147 }
148
149 // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
150 // variants.
151 }
152
153 ContractNodes(N->getNextPtr(), CGP);
154
155
156 // If we have a CheckType/CheckChildType/Record node followed by a
157 // CheckOpcode, invert the two nodes. We prefer to do structural checks
158 // before type checks, as this opens opportunities for factoring on targets
159 // like X86 where many operations are valid on multiple types.
160 if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
161 isa<RecordMatcher>(N)) &&
162 isa<CheckOpcodeMatcher>(N->getNext())) {
163 // Unlink the two nodes from the list.
164 Matcher *CheckType = MatcherPtr.take();
165 Matcher *CheckOpcode = CheckType->takeNext();
166 Matcher *Tail = CheckOpcode->takeNext();
167
168 // Relink them.
169 MatcherPtr.reset(CheckOpcode);
170 CheckOpcode->setNext(CheckType);
171 CheckType->setNext(Tail);
172 return ContractNodes(MatcherPtr, CGP);
173 }
174 }
175
176 /// SinkPatternPredicates - Pattern predicates can be checked at any level of
177 /// the matching tree. The generator dumps them at the top level of the pattern
178 /// though, which prevents factoring from being able to see past them. This
179 /// optimization sinks them as far down into the pattern as possible.
180 ///
181 /// Conceptually, we'd like to sink these predicates all the way to the last
182 /// matcher predicate in the series. However, it turns out that some
183 /// ComplexPatterns have side effects on the graph, so we really don't want to
184 /// run a the complex pattern if the pattern predicate will fail. For this
185 /// reason, we refuse to sink the pattern predicate past a ComplexPattern.
186 ///
187 static void SinkPatternPredicates(OwningPtr<Matcher> &MatcherPtr) {
188 // Recursively scan for a PatternPredicate.
189 // If we reached the end of the chain, we're done.
190 Matcher *N = MatcherPtr.get();
191 if (N == 0) return;
192
193 // Walk down all members of a scope node.
194 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
195 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
196 OwningPtr<Matcher> Child(Scope->takeChild(i));
197 SinkPatternPredicates(Child);
198 Scope->resetChild(i, Child.take());
199 }
200 return;
201 }
202
203 // If this node isn't a CheckPatternPredicateMatcher we keep scanning until
204 // we find one.
205 CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
206 if (CPPM == 0)
207 return SinkPatternPredicates(N->getNextPtr());
208
209 // Ok, we found one, lets try to sink it. Check if we can sink it past the
210 // next node in the chain. If not, we won't be able to change anything and
211 // might as well bail.
212 if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
213 return;
214
215 // Okay, we know we can sink it past at least one node. Unlink it from the
216 // chain and scan for the new insertion point.
217 MatcherPtr.take(); // Don't delete CPPM.
218 MatcherPtr.reset(CPPM->takeNext());
219
220 N = MatcherPtr.get();
221 while (N->getNext()->isSafeToReorderWithPatternPredicate())
222 N = N->getNext();
223
224 // At this point, we want to insert CPPM after N.
225 CPPM->setNext(N->takeNext());
226 N->setNext(CPPM);
227 }
228
229 /// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
230 /// specified kind. Return null if we didn't find one otherwise return the
231 /// matcher.
232 static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
233 for (; M; M = M->getNext())
234 if (M->getKind() == Kind)
235 return M;
236 return 0;
237 }
238
239
240 /// FactorNodes - Turn matches like this:
241 /// Scope
242 /// OPC_CheckType i32
243 /// ABC
244 /// OPC_CheckType i32
245 /// XYZ
246 /// into:
247 /// OPC_CheckType i32
248 /// Scope
249 /// ABC
250 /// XYZ
251 ///
252 static void FactorNodes(OwningPtr<Matcher> &MatcherPtr) {
253 // If we reached the end of the chain, we're done.
254 Matcher *N = MatcherPtr.get();
255 if (N == 0) return;
256
257 // If this is not a push node, just scan for one.
258 ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
259 if (Scope == 0)
260 return FactorNodes(N->getNextPtr());
261
262 // Okay, pull together the children of the scope node into a vector so we can
263 // inspect it more easily. While we're at it, bucket them up by the hash
264 // code of their first predicate.
265 SmallVector<Matcher*, 32> OptionsToMatch;
266
267 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
268 // Factor the subexpression.
269 OwningPtr<Matcher> Child(Scope->takeChild(i));
270 FactorNodes(Child);
271
272 if (Matcher *N = Child.take())
273 OptionsToMatch.push_back(N);
274 }
275
276 SmallVector<Matcher*, 32> NewOptionsToMatch;
277
278 // Loop over options to match, merging neighboring patterns with identical
279 // starting nodes into a shared matcher.
280 for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
281 // Find the set of matchers that start with this node.
282 Matcher *Optn = OptionsToMatch[OptionIdx++];
283
284 if (OptionIdx == e) {
285 NewOptionsToMatch.push_back(Optn);
286 continue;
287 }
288
289 // See if the next option starts with the same matcher. If the two
290 // neighbors *do* start with the same matcher, we can factor the matcher out
291 // of at least these two patterns. See what the maximal set we can merge
292 // together is.
293 SmallVector<Matcher*, 8> EqualMatchers;
294 EqualMatchers.push_back(Optn);
295
296 // Factor all of the known-equal matchers after this one into the same
297 // group.
298 while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
299 EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
300
301 // If we found a non-equal matcher, see if it is contradictory with the
302 // current node. If so, we know that the ordering relation between the
303 // current sets of nodes and this node don't matter. Look past it to see if
304 // we can merge anything else into this matching group.
305 unsigned Scan = OptionIdx;
306 while (1) {
307 // If we ran out of stuff to scan, we're done.
308 if (Scan == e) break;
309
310 Matcher *ScanMatcher = OptionsToMatch[Scan];
311
312 // If we found an entry that matches out matcher, merge it into the set to
313 // handle.
314 if (Optn->isEqual(ScanMatcher)) {
315 // If is equal after all, add the option to EqualMatchers and remove it
316 // from OptionsToMatch.
317 EqualMatchers.push_back(ScanMatcher);
318 OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
319 --e;
320 continue;
321 }
322
323 // If the option we're checking for contradicts the start of the list,
324 // skip over it.
325 if (Optn->isContradictory(ScanMatcher)) {
326 ++Scan;
327 continue;
328 }
329
330 // If we're scanning for a simple node, see if it occurs later in the
331 // sequence. If so, and if we can move it up, it might be contradictory
332 // or the same as what we're looking for. If so, reorder it.
333 if (Optn->isSimplePredicateOrRecordNode()) {
334 Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
335 if (M2 != 0 && M2 != ScanMatcher &&
336 M2->canMoveBefore(ScanMatcher) &&
337 (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
338 Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
339 M2->setNext(MatcherWithoutM2);
340 OptionsToMatch[Scan] = M2;
341 continue;
342 }
343 }
344
345 // Otherwise, we don't know how to handle this entry, we have to bail.
346 break;
347 }
348
349 if (Scan != e &&
350 // Don't print it's obvious nothing extra could be merged anyway.
351 Scan+1 != e) {
352 DEBUG(errs() << "Couldn't merge this:\n";
353 Optn->print(errs(), 4);
354 errs() << "into this:\n";
355 OptionsToMatch[Scan]->print(errs(), 4);
356 if (Scan+1 != e)
357 OptionsToMatch[Scan+1]->printOne(errs());
358 if (Scan+2 < e)
359 OptionsToMatch[Scan+2]->printOne(errs());
360 errs() << "\n");
361 }
362
363 // If we only found one option starting with this matcher, no factoring is
364 // possible.
365 if (EqualMatchers.size() == 1) {
366 NewOptionsToMatch.push_back(EqualMatchers[0]);
367 continue;
368 }
369
370 // Factor these checks by pulling the first node off each entry and
371 // discarding it. Take the first one off the first entry to reuse.
372 Matcher *Shared = Optn;
373 Optn = Optn->takeNext();
374 EqualMatchers[0] = Optn;
375
376 // Remove and delete the first node from the other matchers we're factoring.
377 for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
378 Matcher *Tmp = EqualMatchers[i]->takeNext();
379 delete EqualMatchers[i];
380 EqualMatchers[i] = Tmp;
381 }
382
383 Shared->setNext(new ScopeMatcher(&EqualMatchers[0], EqualMatchers.size()));
384
385 // Recursively factor the newly created node.
386 FactorNodes(Shared->getNextPtr());
387
388 NewOptionsToMatch.push_back(Shared);
389 }
390
391 // If we're down to a single pattern to match, then we don't need this scope
392 // anymore.
393 if (NewOptionsToMatch.size() == 1) {
394 MatcherPtr.reset(NewOptionsToMatch[0]);
395 return;
396 }
397
398 if (NewOptionsToMatch.empty()) {
399 MatcherPtr.reset(0);
400 return;
401 }
402
403 // If our factoring failed (didn't achieve anything) see if we can simplify in
404 // other ways.
405
406 // Check to see if all of the leading entries are now opcode checks. If so,
407 // we can convert this Scope to be a OpcodeSwitch instead.
408 bool AllOpcodeChecks = true, AllTypeChecks = true;
409 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
410 // Check to see if this breaks a series of CheckOpcodeMatchers.
411 if (AllOpcodeChecks &&
412 !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
413 #if 0
414 if (i > 3) {
415 errs() << "FAILING OPC #" << i << "\n";
416 NewOptionsToMatch[i]->dump();
417 }
418 #endif
419 AllOpcodeChecks = false;
420 }
421
422 // Check to see if this breaks a series of CheckTypeMatcher's.
423 if (AllTypeChecks) {
424 CheckTypeMatcher *CTM =
425 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
426 Matcher::CheckType));
427 if (CTM == 0 ||
428 // iPTR checks could alias any other case without us knowing, don't
429 // bother with them.
430 CTM->getType() == MVT::iPTR ||
431 // SwitchType only works for result #0.
432 CTM->getResNo() != 0 ||
433 // If the CheckType isn't at the start of the list, see if we can move
434 // it there.
435 !CTM->canMoveBefore(NewOptionsToMatch[i])) {
436 #if 0
437 if (i > 3 && AllTypeChecks) {
438 errs() << "FAILING TYPE #" << i << "\n";
439 NewOptionsToMatch[i]->dump();
440 }
441 #endif
442 AllTypeChecks = false;
443 }
444 }
445 }
446
447 // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
448 if (AllOpcodeChecks) {
449 StringSet<> Opcodes;
450 SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
451 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
452 CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
453 assert(Opcodes.insert(COM->getOpcode().getEnumName()) &&
454 "Duplicate opcodes not factored?");
455 Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
456 }
457
458 MatcherPtr.reset(new SwitchOpcodeMatcher(&Cases[0], Cases.size()));
459 return;
460 }
461
462 // If all the options are CheckType's, we can form the SwitchType, woot.
463 if (AllTypeChecks) {
464 DenseMap<unsigned, unsigned> TypeEntry;
465 SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
466 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
467 CheckTypeMatcher *CTM =
468 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
469 Matcher::CheckType));
470 Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
471 MVT::SimpleValueType CTMTy = CTM->getType();
472 delete CTM;
473
474 unsigned &Entry = TypeEntry[CTMTy];
475 if (Entry != 0) {
476 // If we have unfactored duplicate types, then we should factor them.
477 Matcher *PrevMatcher = Cases[Entry-1].second;
478 if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
479 SM->setNumChildren(SM->getNumChildren()+1);
480 SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
481 continue;
482 }
483
484 Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
485 Cases[Entry-1].second = new ScopeMatcher(Entries, 2);
486 continue;
487 }
488
489 Entry = Cases.size()+1;
490 Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
491 }
492
493 if (Cases.size() != 1) {
494 MatcherPtr.reset(new SwitchTypeMatcher(&Cases[0], Cases.size()));
495 } else {
496 // If we factored and ended up with one case, create it now.
497 MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
498 MatcherPtr->setNext(Cases[0].second);
499 }
500 return;
501 }
502
503
504 // Reassemble the Scope node with the adjusted children.
505 Scope->setNumChildren(NewOptionsToMatch.size());
506 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
507 Scope->resetChild(i, NewOptionsToMatch[i]);
508 }
509
510 Matcher *llvm::OptimizeMatcher(Matcher *TheMatcher,
511 const CodeGenDAGPatterns &CGP) {
512 OwningPtr<Matcher> MatcherPtr(TheMatcher);
513 ContractNodes(MatcherPtr, CGP);
514 SinkPatternPredicates(MatcherPtr);
515 FactorNodes(MatcherPtr);
516 return MatcherPtr.take();
517 }