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"
24 /// ContractNodes - Turn multiple matcher node patterns like 'MoveChild+Record'
25 /// into single compound nodes like RecordChild.
26 static void ContractNodes(OwningPtr<Matcher> &MatcherPtr,
27 const CodeGenDAGPatterns &CGP) {
28 // If we reached the end of the chain, we're done.
29 Matcher *N = MatcherPtr.get();
32 // If we have a scope node, walk down all of the children.
33 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
34 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
35 OwningPtr<Matcher> Child(Scope->takeChild(i));
36 ContractNodes(Child, CGP);
37 Scope->resetChild(i, Child.take());
42 // If we found a movechild node with a node that comes in a 'foochild' form,
44 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
46 if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
47 New = new RecordChildMatcher(MC->getChildNo(), RM->getWhatFor(),
50 if (CheckTypeMatcher *CT= dyn_cast<CheckTypeMatcher>(MC->getNext()))
51 New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
54 // Insert the new node.
55 New->setNext(MatcherPtr.take());
56 MatcherPtr.reset(New);
57 // Remove the old one.
58 MC->setNext(MC->getNext()->takeNext());
59 return ContractNodes(MatcherPtr, CGP);
63 // Zap movechild -> moveparent.
64 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
65 if (MoveParentMatcher *MP =
66 dyn_cast<MoveParentMatcher>(MC->getNext())) {
67 MatcherPtr.reset(MP->takeNext());
68 return ContractNodes(MatcherPtr, CGP);
71 // Turn EmitNode->MarkFlagResults->CompleteMatch into
72 // MarkFlagResults->EmitNode->CompleteMatch when we can to encourage
73 // MorphNodeTo formation. This is safe because MarkFlagResults never refers
74 // to the root of the pattern.
75 if (isa<EmitNodeMatcher>(N) && isa<MarkFlagResultsMatcher>(N->getNext()) &&
76 isa<CompleteMatchMatcher>(N->getNext()->getNext())) {
77 // Unlink the two nodes from the list.
78 Matcher *EmitNode = MatcherPtr.take();
79 Matcher *MFR = EmitNode->takeNext();
80 Matcher *Tail = MFR->takeNext();
83 MatcherPtr.reset(MFR);
84 MFR->setNext(EmitNode);
85 EmitNode->setNext(Tail);
86 return ContractNodes(MatcherPtr, CGP);
89 // Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
90 if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
91 if (CompleteMatchMatcher *CM =
92 dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
93 // We can only use MorphNodeTo if the result values match up.
94 unsigned RootResultFirst = EN->getFirstResultSlot();
95 bool ResultsMatch = true;
96 for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
97 if (CM->getResult(i) != RootResultFirst+i)
100 // If the selected node defines a subset of the flag/chain results, we
101 // can't use MorphNodeTo. For example, we can't use MorphNodeTo if the
102 // matched pattern has a chain but the root node doesn't.
103 const PatternToMatch &Pattern = CM->getPattern();
105 if (!EN->hasChain() &&
106 Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
107 ResultsMatch = false;
109 // If the matched node has a flag and the output root doesn't, we can't
112 // NOTE: Strictly speaking, we don't have to check for the flag here
113 // because the code in the pattern generator doesn't handle it right. We
114 // do it anyway for thoroughness.
115 if (!EN->hasOutFlag() &&
116 Pattern.getSrcPattern()->NodeHasProperty(SDNPOutFlag, CGP))
117 ResultsMatch = false;
120 // If the root result node defines more results than the source root node
121 // *and* has a chain or flag input, then we can't match it because it
122 // would end up replacing the extra result with the chain/flag.
124 if ((EN->hasFlag() || EN->hasChain()) &&
125 EN->getNumNonChainFlagVTs() > ... need to get no results reliably ...)
130 const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
131 const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
132 MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
133 VTs.data(), VTs.size(),
134 Operands.data(),Operands.size(),
135 EN->hasChain(), EN->hasInFlag(),
138 EN->getNumFixedArityOperands(),
143 // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
147 ContractNodes(N->getNextPtr(), CGP);
150 // If we have a CheckType/CheckChildType/Record node followed by a
151 // CheckOpcode, invert the two nodes. We prefer to do structural checks
152 // before type checks, as this opens opportunities for factoring on targets
153 // like X86 where many operations are valid on multiple types.
154 if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
155 isa<RecordMatcher>(N)) &&
156 isa<CheckOpcodeMatcher>(N->getNext())) {
157 // Unlink the two nodes from the list.
158 Matcher *CheckType = MatcherPtr.take();
159 Matcher *CheckOpcode = CheckType->takeNext();
160 Matcher *Tail = CheckOpcode->takeNext();
163 MatcherPtr.reset(CheckOpcode);
164 CheckOpcode->setNext(CheckType);
165 CheckType->setNext(Tail);
166 return ContractNodes(MatcherPtr, CGP);
170 /// SinkPatternPredicates - Pattern predicates can be checked at any level of
171 /// the matching tree. The generator dumps them at the top level of the pattern
172 /// though, which prevents factoring from being able to see past them. This
173 /// optimization sinks them as far down into the pattern as possible.
175 /// Conceptually, we'd like to sink these predicates all the way to the last
176 /// matcher predicate in the series. However, it turns out that some
177 /// ComplexPatterns have side effects on the graph, so we really don't want to
178 /// run a the complex pattern if the pattern predicate will fail. For this
179 /// reason, we refuse to sink the pattern predicate past a ComplexPattern.
181 static void SinkPatternPredicates(OwningPtr<Matcher> &MatcherPtr) {
182 // Recursively scan for a PatternPredicate.
183 // If we reached the end of the chain, we're done.
184 Matcher *N = MatcherPtr.get();
187 // Walk down all members of a scope node.
188 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
189 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
190 OwningPtr<Matcher> Child(Scope->takeChild(i));
191 SinkPatternPredicates(Child);
192 Scope->resetChild(i, Child.take());
197 // If this node isn't a CheckPatternPredicateMatcher we keep scanning until
199 CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
201 return SinkPatternPredicates(N->getNextPtr());
203 // Ok, we found one, lets try to sink it. Check if we can sink it past the
204 // next node in the chain. If not, we won't be able to change anything and
205 // might as well bail.
206 if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
209 // Okay, we know we can sink it past at least one node. Unlink it from the
210 // chain and scan for the new insertion point.
211 MatcherPtr.take(); // Don't delete CPPM.
212 MatcherPtr.reset(CPPM->takeNext());
214 N = MatcherPtr.get();
215 while (N->getNext()->isSafeToReorderWithPatternPredicate())
218 // At this point, we want to insert CPPM after N.
219 CPPM->setNext(N->takeNext());
223 /// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
224 /// specified kind. Return null if we didn't find one otherwise return the
226 static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
227 for (; M; M = M->getNext())
228 if (M->getKind() == Kind)
234 /// FactorNodes - Turn matches like this:
236 /// OPC_CheckType i32
238 /// OPC_CheckType i32
241 /// OPC_CheckType i32
246 static void FactorNodes(OwningPtr<Matcher> &MatcherPtr) {
247 // If we reached the end of the chain, we're done.
248 Matcher *N = MatcherPtr.get();
251 // If this is not a push node, just scan for one.
252 ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
254 return FactorNodes(N->getNextPtr());
256 // Okay, pull together the children of the scope node into a vector so we can
257 // inspect it more easily. While we're at it, bucket them up by the hash
258 // code of their first predicate.
259 SmallVector<Matcher*, 32> OptionsToMatch;
261 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
262 // Factor the subexpression.
263 OwningPtr<Matcher> Child(Scope->takeChild(i));
266 if (Matcher *N = Child.take())
267 OptionsToMatch.push_back(N);
270 SmallVector<Matcher*, 32> NewOptionsToMatch;
272 // Loop over options to match, merging neighboring patterns with identical
273 // starting nodes into a shared matcher.
274 for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
275 // Find the set of matchers that start with this node.
276 Matcher *Optn = OptionsToMatch[OptionIdx++];
278 if (OptionIdx == e) {
279 NewOptionsToMatch.push_back(Optn);
283 // See if the next option starts with the same matcher. If the two
284 // neighbors *do* start with the same matcher, we can factor the matcher out
285 // of at least these two patterns. See what the maximal set we can merge
287 SmallVector<Matcher*, 8> EqualMatchers;
288 EqualMatchers.push_back(Optn);
290 // Factor all of the known-equal matchers after this one into the same
292 while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
293 EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
295 // If we found a non-equal matcher, see if it is contradictory with the
296 // current node. If so, we know that the ordering relation between the
297 // current sets of nodes and this node don't matter. Look past it to see if
298 // we can merge anything else into this matching group.
299 unsigned Scan = OptionIdx;
301 // If we ran out of stuff to scan, we're done.
302 if (Scan == e) break;
304 Matcher *ScanMatcher = OptionsToMatch[Scan];
306 // If we found an entry that matches out matcher, merge it into the set to
308 if (Optn->isEqual(ScanMatcher)) {
309 // If is equal after all, add the option to EqualMatchers and remove it
310 // from OptionsToMatch.
311 EqualMatchers.push_back(ScanMatcher);
312 OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
317 // If the option we're checking for contradicts the start of the list,
319 if (Optn->isContradictory(ScanMatcher)) {
324 // If we're scanning for a simple node, see if it occurs later in the
325 // sequence. If so, and if we can move it up, it might be contradictory
326 // or the same as what we're looking for. If so, reorder it.
327 if (Optn->isSimplePredicateOrRecordNode()) {
328 Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
329 if (M2 != 0 && M2 != ScanMatcher &&
330 M2->canMoveBefore(ScanMatcher) &&
331 (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
332 Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
333 M2->setNext(MatcherWithoutM2);
334 OptionsToMatch[Scan] = M2;
339 // Otherwise, we don't know how to handle this entry, we have to bail.
344 // Don't print it's obvious nothing extra could be merged anyway.
346 DEBUG(errs() << "Couldn't merge this:\n";
347 Optn->print(errs(), 4);
348 errs() << "into this:\n";
349 OptionsToMatch[Scan]->print(errs(), 4);
351 OptionsToMatch[Scan+1]->printOne(errs());
353 OptionsToMatch[Scan+2]->printOne(errs());
357 // If we only found one option starting with this matcher, no factoring is
359 if (EqualMatchers.size() == 1) {
360 NewOptionsToMatch.push_back(EqualMatchers[0]);
364 // Factor these checks by pulling the first node off each entry and
365 // discarding it. Take the first one off the first entry to reuse.
366 Matcher *Shared = Optn;
367 Optn = Optn->takeNext();
368 EqualMatchers[0] = Optn;
370 // Remove and delete the first node from the other matchers we're factoring.
371 for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
372 Matcher *Tmp = EqualMatchers[i]->takeNext();
373 delete EqualMatchers[i];
374 EqualMatchers[i] = Tmp;
377 Shared->setNext(new ScopeMatcher(&EqualMatchers[0], EqualMatchers.size()));
379 // Recursively factor the newly created node.
380 FactorNodes(Shared->getNextPtr());
382 NewOptionsToMatch.push_back(Shared);
385 // If we're down to a single pattern to match, then we don't need this scope
387 if (NewOptionsToMatch.size() == 1) {
388 MatcherPtr.reset(NewOptionsToMatch[0]);
392 if (NewOptionsToMatch.empty()) {
397 // If our factoring failed (didn't achieve anything) see if we can simplify in
400 // Check to see if all of the leading entries are now opcode checks. If so,
401 // we can convert this Scope to be a OpcodeSwitch instead.
402 bool AllOpcodeChecks = true, AllTypeChecks = true;
403 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
404 // Check to see if this breaks a series of CheckOpcodeMatchers.
405 if (AllOpcodeChecks &&
406 !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
409 errs() << "FAILING OPC #" << i << "\n";
410 NewOptionsToMatch[i]->dump();
413 AllOpcodeChecks = false;
416 // Check to see if this breaks a series of CheckTypeMatcher's.
418 CheckTypeMatcher *CTM =
419 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
420 Matcher::CheckType));
422 // iPTR checks could alias any other case without us knowing, don't
424 CTM->getType() == MVT::iPTR ||
425 // If the CheckType isn't at the start of the list, see if we can move
427 !CTM->canMoveBefore(NewOptionsToMatch[i])) {
429 if (i > 3 && AllTypeChecks) {
430 errs() << "FAILING TYPE #" << i << "\n";
431 NewOptionsToMatch[i]->dump();
434 AllTypeChecks = false;
439 // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
440 if (AllOpcodeChecks) {
442 SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
443 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
444 CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
445 assert(Opcodes.insert(COM->getOpcode().getEnumName()) &&
446 "Duplicate opcodes not factored?");
447 Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
450 MatcherPtr.reset(new SwitchOpcodeMatcher(&Cases[0], Cases.size()));
454 // If all the options are CheckType's, we can form the SwitchType, woot.
456 DenseMap<unsigned, unsigned> TypeEntry;
457 SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
458 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
459 CheckTypeMatcher *CTM =
460 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
461 Matcher::CheckType));
462 Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
463 MVT::SimpleValueType CTMTy = CTM->getType();
466 unsigned &Entry = TypeEntry[CTMTy];
468 // If we have unfactored duplicate types, then we should factor them.
469 Matcher *PrevMatcher = Cases[Entry-1].second;
470 if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
471 SM->setNumChildren(SM->getNumChildren()+1);
472 SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
476 Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
477 Cases[Entry-1].second = new ScopeMatcher(Entries, 2);
481 Entry = Cases.size()+1;
482 Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
485 if (Cases.size() != 1) {
486 MatcherPtr.reset(new SwitchTypeMatcher(&Cases[0], Cases.size()));
488 // If we factored and ended up with one case, create it now.
489 MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first));
490 MatcherPtr->setNext(Cases[0].second);
496 // Reassemble the Scope node with the adjusted children.
497 Scope->setNumChildren(NewOptionsToMatch.size());
498 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
499 Scope->resetChild(i, NewOptionsToMatch[i]);
502 Matcher *llvm::OptimizeMatcher(Matcher *TheMatcher,
503 const CodeGenDAGPatterns &CGP) {
504 OwningPtr<Matcher> MatcherPtr(TheMatcher);
505 ContractNodes(MatcherPtr, CGP);
506 SinkPatternPredicates(MatcherPtr);
507 FactorNodes(MatcherPtr);
508 return MatcherPtr.take();