1 //===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the DAG Matcher optimizer.
12 //===----------------------------------------------------------------------===//
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"
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();
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());
41 // If we found a movechild node with a node that comes in a 'foochild' form,
43 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
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(),
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());
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());
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);
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);
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();
89 MatcherPtr.reset(MFR);
90 MFR->setNext(EmitNode);
91 EmitNode->setNext(Tail);
92 return ContractNodes(MatcherPtr, CGP);
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;
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();
111 if (!EN->hasChain() &&
112 Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
113 ResultsMatch = false;
115 // If the matched node has glue and the output root doesn't, we can't
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;
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.
130 if ((EN->hasGlue() || EN->hasChain()) &&
131 EN->getNumNonChainGlueVTs() > ... need to get no results reliably ...)
136 const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
137 const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
138 MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
140 EN->hasChain(), EN->hasInFlag(),
143 EN->getNumFixedArityOperands(),
148 // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
152 ContractNodes(N->getNextPtr(), CGP);
155 // If we have a CheckType/CheckChildType/Record node followed by a
156 // CheckOpcode, invert the two nodes. We prefer to do structural checks
157 // before type checks, as this opens opportunities for factoring on targets
158 // like X86 where many operations are valid on multiple types.
159 if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
160 isa<RecordMatcher>(N)) &&
161 isa<CheckOpcodeMatcher>(N->getNext())) {
162 // Unlink the two nodes from the list.
163 Matcher *CheckType = MatcherPtr.take();
164 Matcher *CheckOpcode = CheckType->takeNext();
165 Matcher *Tail = CheckOpcode->takeNext();
168 MatcherPtr.reset(CheckOpcode);
169 CheckOpcode->setNext(CheckType);
170 CheckType->setNext(Tail);
171 return ContractNodes(MatcherPtr, CGP);
175 /// SinkPatternPredicates - Pattern predicates can be checked at any level of
176 /// the matching tree. The generator dumps them at the top level of the pattern
177 /// though, which prevents factoring from being able to see past them. This
178 /// optimization sinks them as far down into the pattern as possible.
180 /// Conceptually, we'd like to sink these predicates all the way to the last
181 /// matcher predicate in the series. However, it turns out that some
182 /// ComplexPatterns have side effects on the graph, so we really don't want to
183 /// run a the complex pattern if the pattern predicate will fail. For this
184 /// reason, we refuse to sink the pattern predicate past a ComplexPattern.
186 static void SinkPatternPredicates(OwningPtr<Matcher> &MatcherPtr) {
187 // Recursively scan for a PatternPredicate.
188 // If we reached the end of the chain, we're done.
189 Matcher *N = MatcherPtr.get();
192 // Walk down all members of a scope node.
193 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
194 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
195 OwningPtr<Matcher> Child(Scope->takeChild(i));
196 SinkPatternPredicates(Child);
197 Scope->resetChild(i, Child.take());
202 // If this node isn't a CheckPatternPredicateMatcher we keep scanning until
204 CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
206 return SinkPatternPredicates(N->getNextPtr());
208 // Ok, we found one, lets try to sink it. Check if we can sink it past the
209 // next node in the chain. If not, we won't be able to change anything and
210 // might as well bail.
211 if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
214 // Okay, we know we can sink it past at least one node. Unlink it from the
215 // chain and scan for the new insertion point.
216 MatcherPtr.take(); // Don't delete CPPM.
217 MatcherPtr.reset(CPPM->takeNext());
219 N = MatcherPtr.get();
220 while (N->getNext()->isSafeToReorderWithPatternPredicate())
223 // At this point, we want to insert CPPM after N.
224 CPPM->setNext(N->takeNext());
228 /// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
229 /// specified kind. Return null if we didn't find one otherwise return the
231 static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
232 for (; M; M = M->getNext())
233 if (M->getKind() == Kind)
239 /// FactorNodes - Turn matches like this:
241 /// OPC_CheckType i32
243 /// OPC_CheckType i32
246 /// OPC_CheckType i32
251 static void FactorNodes(OwningPtr<Matcher> &MatcherPtr) {
252 // If we reached the end of the chain, we're done.
253 Matcher *N = MatcherPtr.get();
256 // If this is not a push node, just scan for one.
257 ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
259 return FactorNodes(N->getNextPtr());
261 // Okay, pull together the children of the scope node into a vector so we can
262 // inspect it more easily. While we're at it, bucket them up by the hash
263 // code of their first predicate.
264 SmallVector<Matcher*, 32> OptionsToMatch;
266 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
267 // Factor the subexpression.
268 OwningPtr<Matcher> Child(Scope->takeChild(i));
271 if (Matcher *N = Child.take())
272 OptionsToMatch.push_back(N);
275 SmallVector<Matcher*, 32> NewOptionsToMatch;
277 // Loop over options to match, merging neighboring patterns with identical
278 // starting nodes into a shared matcher.
279 for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
280 // Find the set of matchers that start with this node.
281 Matcher *Optn = OptionsToMatch[OptionIdx++];
283 if (OptionIdx == e) {
284 NewOptionsToMatch.push_back(Optn);
288 // See if the next option starts with the same matcher. If the two
289 // neighbors *do* start with the same matcher, we can factor the matcher out
290 // of at least these two patterns. See what the maximal set we can merge
292 SmallVector<Matcher*, 8> EqualMatchers;
293 EqualMatchers.push_back(Optn);
295 // Factor all of the known-equal matchers after this one into the same
297 while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
298 EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
300 // If we found a non-equal matcher, see if it is contradictory with the
301 // current node. If so, we know that the ordering relation between the
302 // current sets of nodes and this node don't matter. Look past it to see if
303 // we can merge anything else into this matching group.
304 unsigned Scan = OptionIdx;
306 // If we ran out of stuff to scan, we're done.
307 if (Scan == e) break;
309 Matcher *ScanMatcher = OptionsToMatch[Scan];
311 // If we found an entry that matches out matcher, merge it into the set to
313 if (Optn->isEqual(ScanMatcher)) {
314 // If is equal after all, add the option to EqualMatchers and remove it
315 // from OptionsToMatch.
316 EqualMatchers.push_back(ScanMatcher);
317 OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
322 // If the option we're checking for contradicts the start of the list,
324 if (Optn->isContradictory(ScanMatcher)) {
329 // If we're scanning for a simple node, see if it occurs later in the
330 // sequence. If so, and if we can move it up, it might be contradictory
331 // or the same as what we're looking for. If so, reorder it.
332 if (Optn->isSimplePredicateOrRecordNode()) {
333 Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
334 if (M2 != 0 && M2 != ScanMatcher &&
335 M2->canMoveBefore(ScanMatcher) &&
336 (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
337 Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
338 M2->setNext(MatcherWithoutM2);
339 OptionsToMatch[Scan] = M2;
344 // Otherwise, we don't know how to handle this entry, we have to bail.
349 // Don't print it's obvious nothing extra could be merged anyway.
351 DEBUG(errs() << "Couldn't merge this:\n";
352 Optn->print(errs(), 4);
353 errs() << "into this:\n";
354 OptionsToMatch[Scan]->print(errs(), 4);
356 OptionsToMatch[Scan+1]->printOne(errs());
358 OptionsToMatch[Scan+2]->printOne(errs());
362 // If we only found one option starting with this matcher, no factoring is
364 if (EqualMatchers.size() == 1) {
365 NewOptionsToMatch.push_back(EqualMatchers[0]);
369 // Factor these checks by pulling the first node off each entry and
370 // discarding it. Take the first one off the first entry to reuse.
371 Matcher *Shared = Optn;
372 Optn = Optn->takeNext();
373 EqualMatchers[0] = Optn;
375 // Remove and delete the first node from the other matchers we're factoring.
376 for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
377 Matcher *Tmp = EqualMatchers[i]->takeNext();
378 delete EqualMatchers[i];
379 EqualMatchers[i] = Tmp;
382 Shared->setNext(new ScopeMatcher(EqualMatchers));
384 // Recursively factor the newly created node.
385 FactorNodes(Shared->getNextPtr());
387 NewOptionsToMatch.push_back(Shared);
390 // If we're down to a single pattern to match, then we don't need this scope
392 if (NewOptionsToMatch.size() == 1) {
393 MatcherPtr.reset(NewOptionsToMatch[0]);
397 if (NewOptionsToMatch.empty()) {
402 // If our factoring failed (didn't achieve anything) see if we can simplify in
405 // Check to see if all of the leading entries are now opcode checks. If so,
406 // we can convert this Scope to be a OpcodeSwitch instead.
407 bool AllOpcodeChecks = true, AllTypeChecks = true;
408 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
409 // Check to see if this breaks a series of CheckOpcodeMatchers.
410 if (AllOpcodeChecks &&
411 !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
414 errs() << "FAILING OPC #" << i << "\n";
415 NewOptionsToMatch[i]->dump();
418 AllOpcodeChecks = false;
421 // Check to see if this breaks a series of CheckTypeMatcher's.
423 CheckTypeMatcher *CTM =
424 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
425 Matcher::CheckType));
427 // iPTR checks could alias any other case without us knowing, don't
429 CTM->getType() == MVT::iPTR ||
430 // SwitchType only works for result #0.
431 CTM->getResNo() != 0 ||
432 // If the CheckType isn't at the start of the list, see if we can move
434 !CTM->canMoveBefore(NewOptionsToMatch[i])) {
436 if (i > 3 && AllTypeChecks) {
437 errs() << "FAILING TYPE #" << i << "\n";
438 NewOptionsToMatch[i]->dump();
441 AllTypeChecks = false;
446 // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
447 if (AllOpcodeChecks) {
449 SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
450 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
451 CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
452 assert(Opcodes.insert(COM->getOpcode().getEnumName()) &&
453 "Duplicate opcodes not factored?");
454 Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
457 MatcherPtr.reset(new SwitchOpcodeMatcher(Cases));
461 // If all the options are CheckType's, we can form the SwitchType, woot.
463 DenseMap<unsigned, unsigned> TypeEntry;
464 SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
465 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
466 CheckTypeMatcher *CTM =
467 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
468 Matcher::CheckType));
469 Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
470 MVT::SimpleValueType CTMTy = CTM->getType();
473 unsigned &Entry = TypeEntry[CTMTy];
475 // If we have unfactored duplicate types, then we should factor them.
476 Matcher *PrevMatcher = Cases[Entry-1].second;
477 if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
478 SM->setNumChildren(SM->getNumChildren()+1);
479 SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
483 Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
484 Cases[Entry-1].second = new ScopeMatcher(Entries);
488 Entry = Cases.size()+1;
489 Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
492 if (Cases.size() != 1) {
493 MatcherPtr.reset(new SwitchTypeMatcher(Cases));
495 // If we factored and ended up with one case, create it now.
496 MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
497 MatcherPtr->setNext(Cases[0].second);
503 // Reassemble the Scope node with the adjusted children.
504 Scope->setNumChildren(NewOptionsToMatch.size());
505 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
506 Scope->resetChild(i, NewOptionsToMatch[i]);
509 Matcher *llvm::OptimizeMatcher(Matcher *TheMatcher,
510 const CodeGenDAGPatterns &CGP) {
511 OwningPtr<Matcher> MatcherPtr(TheMatcher);
512 ContractNodes(MatcherPtr, CGP);
513 SinkPatternPredicates(MatcherPtr);
514 FactorNodes(MatcherPtr);
515 return MatcherPtr.take();