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());
59 if (CheckIntegerMatcher *CS = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
60 if (MC->getChildNo() < 5) // Only have CheckChildInteger0...4
61 New = new CheckChildIntegerMatcher(MC->getChildNo(), CS->getValue());
64 // Insert the new node.
65 New->setNext(MatcherPtr.take());
66 MatcherPtr.reset(New);
67 // Remove the old one.
68 MC->setNext(MC->getNext()->takeNext());
69 return ContractNodes(MatcherPtr, CGP);
73 // Zap movechild -> moveparent.
74 if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
75 if (MoveParentMatcher *MP =
76 dyn_cast<MoveParentMatcher>(MC->getNext())) {
77 MatcherPtr.reset(MP->takeNext());
78 return ContractNodes(MatcherPtr, CGP);
81 // Turn EmitNode->MarkFlagResults->CompleteMatch into
82 // MarkFlagResults->EmitNode->CompleteMatch when we can to encourage
83 // MorphNodeTo formation. This is safe because MarkFlagResults never refers
84 // to the root of the pattern.
85 if (isa<EmitNodeMatcher>(N) && isa<MarkGlueResultsMatcher>(N->getNext()) &&
86 isa<CompleteMatchMatcher>(N->getNext()->getNext())) {
87 // Unlink the two nodes from the list.
88 Matcher *EmitNode = MatcherPtr.take();
89 Matcher *MFR = EmitNode->takeNext();
90 Matcher *Tail = MFR->takeNext();
93 MatcherPtr.reset(MFR);
94 MFR->setNext(EmitNode);
95 EmitNode->setNext(Tail);
96 return ContractNodes(MatcherPtr, CGP);
99 // Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
100 if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
101 if (CompleteMatchMatcher *CM =
102 dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
103 // We can only use MorphNodeTo if the result values match up.
104 unsigned RootResultFirst = EN->getFirstResultSlot();
105 bool ResultsMatch = true;
106 for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
107 if (CM->getResult(i) != RootResultFirst+i)
108 ResultsMatch = false;
110 // If the selected node defines a subset of the glue/chain results, we
111 // can't use MorphNodeTo. For example, we can't use MorphNodeTo if the
112 // matched pattern has a chain but the root node doesn't.
113 const PatternToMatch &Pattern = CM->getPattern();
115 if (!EN->hasChain() &&
116 Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
117 ResultsMatch = false;
119 // If the matched node has glue and the output root doesn't, we can't
122 // NOTE: Strictly speaking, we don't have to check for glue here
123 // because the code in the pattern generator doesn't handle it right. We
124 // do it anyway for thoroughness.
125 if (!EN->hasOutFlag() &&
126 Pattern.getSrcPattern()->NodeHasProperty(SDNPOutGlue, CGP))
127 ResultsMatch = false;
130 // If the root result node defines more results than the source root node
131 // *and* has a chain or glue input, then we can't match it because it
132 // would end up replacing the extra result with the chain/glue.
134 if ((EN->hasGlue() || EN->hasChain()) &&
135 EN->getNumNonChainGlueVTs() > ... need to get no results reliably ...)
140 const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
141 const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
142 MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
144 EN->hasChain(), EN->hasInFlag(),
147 EN->getNumFixedArityOperands(),
152 // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
156 ContractNodes(N->getNextPtr(), CGP);
159 // If we have a CheckType/CheckChildType/Record node followed by a
160 // CheckOpcode, invert the two nodes. We prefer to do structural checks
161 // before type checks, as this opens opportunities for factoring on targets
162 // like X86 where many operations are valid on multiple types.
163 if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
164 isa<RecordMatcher>(N)) &&
165 isa<CheckOpcodeMatcher>(N->getNext())) {
166 // Unlink the two nodes from the list.
167 Matcher *CheckType = MatcherPtr.take();
168 Matcher *CheckOpcode = CheckType->takeNext();
169 Matcher *Tail = CheckOpcode->takeNext();
172 MatcherPtr.reset(CheckOpcode);
173 CheckOpcode->setNext(CheckType);
174 CheckType->setNext(Tail);
175 return ContractNodes(MatcherPtr, CGP);
179 /// SinkPatternPredicates - Pattern predicates can be checked at any level of
180 /// the matching tree. The generator dumps them at the top level of the pattern
181 /// though, which prevents factoring from being able to see past them. This
182 /// optimization sinks them as far down into the pattern as possible.
184 /// Conceptually, we'd like to sink these predicates all the way to the last
185 /// matcher predicate in the series. However, it turns out that some
186 /// ComplexPatterns have side effects on the graph, so we really don't want to
187 /// run a the complex pattern if the pattern predicate will fail. For this
188 /// reason, we refuse to sink the pattern predicate past a ComplexPattern.
190 static void SinkPatternPredicates(OwningPtr<Matcher> &MatcherPtr) {
191 // Recursively scan for a PatternPredicate.
192 // If we reached the end of the chain, we're done.
193 Matcher *N = MatcherPtr.get();
196 // Walk down all members of a scope node.
197 if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
198 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
199 OwningPtr<Matcher> Child(Scope->takeChild(i));
200 SinkPatternPredicates(Child);
201 Scope->resetChild(i, Child.take());
206 // If this node isn't a CheckPatternPredicateMatcher we keep scanning until
208 CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
210 return SinkPatternPredicates(N->getNextPtr());
212 // Ok, we found one, lets try to sink it. Check if we can sink it past the
213 // next node in the chain. If not, we won't be able to change anything and
214 // might as well bail.
215 if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
218 // Okay, we know we can sink it past at least one node. Unlink it from the
219 // chain and scan for the new insertion point.
220 MatcherPtr.take(); // Don't delete CPPM.
221 MatcherPtr.reset(CPPM->takeNext());
223 N = MatcherPtr.get();
224 while (N->getNext()->isSafeToReorderWithPatternPredicate())
227 // At this point, we want to insert CPPM after N.
228 CPPM->setNext(N->takeNext());
232 /// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
233 /// specified kind. Return null if we didn't find one otherwise return the
235 static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
236 for (; M; M = M->getNext())
237 if (M->getKind() == Kind)
243 /// FactorNodes - Turn matches like this:
245 /// OPC_CheckType i32
247 /// OPC_CheckType i32
250 /// OPC_CheckType i32
255 static void FactorNodes(OwningPtr<Matcher> &MatcherPtr) {
256 // If we reached the end of the chain, we're done.
257 Matcher *N = MatcherPtr.get();
260 // If this is not a push node, just scan for one.
261 ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
263 return FactorNodes(N->getNextPtr());
265 // Okay, pull together the children of the scope node into a vector so we can
266 // inspect it more easily. While we're at it, bucket them up by the hash
267 // code of their first predicate.
268 SmallVector<Matcher*, 32> OptionsToMatch;
270 for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
271 // Factor the subexpression.
272 OwningPtr<Matcher> Child(Scope->takeChild(i));
275 if (Matcher *N = Child.take())
276 OptionsToMatch.push_back(N);
279 SmallVector<Matcher*, 32> NewOptionsToMatch;
281 // Loop over options to match, merging neighboring patterns with identical
282 // starting nodes into a shared matcher.
283 for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
284 // Find the set of matchers that start with this node.
285 Matcher *Optn = OptionsToMatch[OptionIdx++];
287 if (OptionIdx == e) {
288 NewOptionsToMatch.push_back(Optn);
292 // See if the next option starts with the same matcher. If the two
293 // neighbors *do* start with the same matcher, we can factor the matcher out
294 // of at least these two patterns. See what the maximal set we can merge
296 SmallVector<Matcher*, 8> EqualMatchers;
297 EqualMatchers.push_back(Optn);
299 // Factor all of the known-equal matchers after this one into the same
301 while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
302 EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
304 // If we found a non-equal matcher, see if it is contradictory with the
305 // current node. If so, we know that the ordering relation between the
306 // current sets of nodes and this node don't matter. Look past it to see if
307 // we can merge anything else into this matching group.
308 unsigned Scan = OptionIdx;
310 // If we ran out of stuff to scan, we're done.
311 if (Scan == e) break;
313 Matcher *ScanMatcher = OptionsToMatch[Scan];
315 // If we found an entry that matches out matcher, merge it into the set to
317 if (Optn->isEqual(ScanMatcher)) {
318 // If is equal after all, add the option to EqualMatchers and remove it
319 // from OptionsToMatch.
320 EqualMatchers.push_back(ScanMatcher);
321 OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
326 // If the option we're checking for contradicts the start of the list,
328 if (Optn->isContradictory(ScanMatcher)) {
333 // If we're scanning for a simple node, see if it occurs later in the
334 // sequence. If so, and if we can move it up, it might be contradictory
335 // or the same as what we're looking for. If so, reorder it.
336 if (Optn->isSimplePredicateOrRecordNode()) {
337 Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
338 if (M2 != 0 && M2 != ScanMatcher &&
339 M2->canMoveBefore(ScanMatcher) &&
340 (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
341 Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
342 M2->setNext(MatcherWithoutM2);
343 OptionsToMatch[Scan] = M2;
348 // Otherwise, we don't know how to handle this entry, we have to bail.
353 // Don't print it's obvious nothing extra could be merged anyway.
355 DEBUG(errs() << "Couldn't merge this:\n";
356 Optn->print(errs(), 4);
357 errs() << "into this:\n";
358 OptionsToMatch[Scan]->print(errs(), 4);
360 OptionsToMatch[Scan+1]->printOne(errs());
362 OptionsToMatch[Scan+2]->printOne(errs());
366 // If we only found one option starting with this matcher, no factoring is
368 if (EqualMatchers.size() == 1) {
369 NewOptionsToMatch.push_back(EqualMatchers[0]);
373 // Factor these checks by pulling the first node off each entry and
374 // discarding it. Take the first one off the first entry to reuse.
375 Matcher *Shared = Optn;
376 Optn = Optn->takeNext();
377 EqualMatchers[0] = Optn;
379 // Remove and delete the first node from the other matchers we're factoring.
380 for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
381 Matcher *Tmp = EqualMatchers[i]->takeNext();
382 delete EqualMatchers[i];
383 EqualMatchers[i] = Tmp;
386 Shared->setNext(new ScopeMatcher(EqualMatchers));
388 // Recursively factor the newly created node.
389 FactorNodes(Shared->getNextPtr());
391 NewOptionsToMatch.push_back(Shared);
394 // If we're down to a single pattern to match, then we don't need this scope
396 if (NewOptionsToMatch.size() == 1) {
397 MatcherPtr.reset(NewOptionsToMatch[0]);
401 if (NewOptionsToMatch.empty()) {
406 // If our factoring failed (didn't achieve anything) see if we can simplify in
409 // Check to see if all of the leading entries are now opcode checks. If so,
410 // we can convert this Scope to be a OpcodeSwitch instead.
411 bool AllOpcodeChecks = true, AllTypeChecks = true;
412 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
413 // Check to see if this breaks a series of CheckOpcodeMatchers.
414 if (AllOpcodeChecks &&
415 !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
418 errs() << "FAILING OPC #" << i << "\n";
419 NewOptionsToMatch[i]->dump();
422 AllOpcodeChecks = false;
425 // Check to see if this breaks a series of CheckTypeMatcher's.
427 CheckTypeMatcher *CTM =
428 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
429 Matcher::CheckType));
431 // iPTR checks could alias any other case without us knowing, don't
433 CTM->getType() == MVT::iPTR ||
434 // SwitchType only works for result #0.
435 CTM->getResNo() != 0 ||
436 // If the CheckType isn't at the start of the list, see if we can move
438 !CTM->canMoveBefore(NewOptionsToMatch[i])) {
440 if (i > 3 && AllTypeChecks) {
441 errs() << "FAILING TYPE #" << i << "\n";
442 NewOptionsToMatch[i]->dump();
445 AllTypeChecks = false;
450 // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
451 if (AllOpcodeChecks) {
453 SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
454 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
455 CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
456 assert(Opcodes.insert(COM->getOpcode().getEnumName()) &&
457 "Duplicate opcodes not factored?");
458 Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
461 MatcherPtr.reset(new SwitchOpcodeMatcher(Cases));
465 // If all the options are CheckType's, we can form the SwitchType, woot.
467 DenseMap<unsigned, unsigned> TypeEntry;
468 SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
469 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
470 CheckTypeMatcher *CTM =
471 cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
472 Matcher::CheckType));
473 Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
474 MVT::SimpleValueType CTMTy = CTM->getType();
477 unsigned &Entry = TypeEntry[CTMTy];
479 // If we have unfactored duplicate types, then we should factor them.
480 Matcher *PrevMatcher = Cases[Entry-1].second;
481 if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
482 SM->setNumChildren(SM->getNumChildren()+1);
483 SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
487 Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
488 Cases[Entry-1].second = new ScopeMatcher(Entries);
492 Entry = Cases.size()+1;
493 Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
496 if (Cases.size() != 1) {
497 MatcherPtr.reset(new SwitchTypeMatcher(Cases));
499 // If we factored and ended up with one case, create it now.
500 MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
501 MatcherPtr->setNext(Cases[0].second);
507 // Reassemble the Scope node with the adjusted children.
508 Scope->setNumChildren(NewOptionsToMatch.size());
509 for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
510 Scope->resetChild(i, NewOptionsToMatch[i]);
513 Matcher *llvm::OptimizeMatcher(Matcher *TheMatcher,
514 const CodeGenDAGPatterns &CGP) {
515 OwningPtr<Matcher> MatcherPtr(TheMatcher);
516 ContractNodes(MatcherPtr, CGP);
517 SinkPatternPredicates(MatcherPtr);
518 FactorNodes(MatcherPtr);
519 return MatcherPtr.take();