521 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			C++
		
	
	
	
			
		
		
	
	
			521 lines
		
	
	
		
			19 KiB
		
	
	
	
		
			C++
		
	
	
	
//===- DAGISelMatcherOpt.cpp - Optimize a DAG Matcher ---------------------===//
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//
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//                     The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the DAG Matcher optimizer.
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//
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//===----------------------------------------------------------------------===//
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#include "DAGISelMatcher.h"
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#include "CodeGenDAGPatterns.h"
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#include "llvm/ADT/DenseSet.h"
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#include "llvm/ADT/StringSet.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "isel-opt"
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/// ContractNodes - Turn multiple matcher node patterns like 'MoveChild+Record'
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/// into single compound nodes like RecordChild.
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static void ContractNodes(std::unique_ptr<Matcher> &MatcherPtr,
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                          const CodeGenDAGPatterns &CGP) {
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  // If we reached the end of the chain, we're done.
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  Matcher *N = MatcherPtr.get();
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  if (!N) return;
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  // If we have a scope node, walk down all of the children.
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  if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
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    for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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      std::unique_ptr<Matcher> Child(Scope->takeChild(i));
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      ContractNodes(Child, CGP);
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      Scope->resetChild(i, Child.release());
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    }
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    return;
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  }
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  // If we found a movechild node with a node that comes in a 'foochild' form,
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  // transform it.
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  if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N)) {
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    Matcher *New = nullptr;
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    if (RecordMatcher *RM = dyn_cast<RecordMatcher>(MC->getNext()))
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      if (MC->getChildNo() < 8)  // Only have RecordChild0...7
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        New = new RecordChildMatcher(MC->getChildNo(), RM->getWhatFor(),
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                                     RM->getResultNo());
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    if (CheckTypeMatcher *CT = dyn_cast<CheckTypeMatcher>(MC->getNext()))
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      if (MC->getChildNo() < 8 &&  // Only have CheckChildType0...7
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          CT->getResNo() == 0)     // CheckChildType checks res #0
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        New = new CheckChildTypeMatcher(MC->getChildNo(), CT->getType());
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    if (CheckSameMatcher *CS = dyn_cast<CheckSameMatcher>(MC->getNext()))
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      if (MC->getChildNo() < 4)  // Only have CheckChildSame0...3
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        New = new CheckChildSameMatcher(MC->getChildNo(), CS->getMatchNumber());
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    if (CheckIntegerMatcher *CS = dyn_cast<CheckIntegerMatcher>(MC->getNext()))
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      if (MC->getChildNo() < 5)  // Only have CheckChildInteger0...4
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        New = new CheckChildIntegerMatcher(MC->getChildNo(), CS->getValue());
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    if (New) {
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      // Insert the new node.
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      New->setNext(MatcherPtr.release());
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      MatcherPtr.reset(New);
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      // Remove the old one.
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      MC->setNext(MC->getNext()->takeNext());
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      return ContractNodes(MatcherPtr, CGP);
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    }
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  }
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  // Zap movechild -> moveparent.
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  if (MoveChildMatcher *MC = dyn_cast<MoveChildMatcher>(N))
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    if (MoveParentMatcher *MP = 
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          dyn_cast<MoveParentMatcher>(MC->getNext())) {
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      MatcherPtr.reset(MP->takeNext());
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      return ContractNodes(MatcherPtr, CGP);
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    }
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  // Turn EmitNode->MarkFlagResults->CompleteMatch into
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  // MarkFlagResults->EmitNode->CompleteMatch when we can to encourage
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  // MorphNodeTo formation.  This is safe because MarkFlagResults never refers
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  // to the root of the pattern.
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  if (isa<EmitNodeMatcher>(N) && isa<MarkGlueResultsMatcher>(N->getNext()) &&
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      isa<CompleteMatchMatcher>(N->getNext()->getNext())) {
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    // Unlink the two nodes from the list.
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    Matcher *EmitNode = MatcherPtr.release();
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    Matcher *MFR = EmitNode->takeNext();
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    Matcher *Tail = MFR->takeNext();
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    // Relink them.
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    MatcherPtr.reset(MFR);
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    MFR->setNext(EmitNode);
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    EmitNode->setNext(Tail);
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    return ContractNodes(MatcherPtr, CGP);
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  }
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  // Turn EmitNode->CompleteMatch into MorphNodeTo if we can.
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  if (EmitNodeMatcher *EN = dyn_cast<EmitNodeMatcher>(N))
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    if (CompleteMatchMatcher *CM =
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          dyn_cast<CompleteMatchMatcher>(EN->getNext())) {
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      // We can only use MorphNodeTo if the result values match up.
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      unsigned RootResultFirst = EN->getFirstResultSlot();
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      bool ResultsMatch = true;
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      for (unsigned i = 0, e = CM->getNumResults(); i != e; ++i)
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        if (CM->getResult(i) != RootResultFirst+i)
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          ResultsMatch = false;
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      // If the selected node defines a subset of the glue/chain results, we
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      // can't use MorphNodeTo.  For example, we can't use MorphNodeTo if the
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      // matched pattern has a chain but the root node doesn't.
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      const PatternToMatch &Pattern = CM->getPattern();
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      if (!EN->hasChain() &&
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          Pattern.getSrcPattern()->NodeHasProperty(SDNPHasChain, CGP))
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        ResultsMatch = false;
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      // If the matched node has glue and the output root doesn't, we can't
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      // use MorphNodeTo.
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      //
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      // NOTE: Strictly speaking, we don't have to check for glue here
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      // because the code in the pattern generator doesn't handle it right.  We
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      // do it anyway for thoroughness.
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      if (!EN->hasOutFlag() &&
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          Pattern.getSrcPattern()->NodeHasProperty(SDNPOutGlue, CGP))
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        ResultsMatch = false;
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      // If the root result node defines more results than the source root node
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      // *and* has a chain or glue input, then we can't match it because it
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      // would end up replacing the extra result with the chain/glue.
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#if 0
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      if ((EN->hasGlue() || EN->hasChain()) &&
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          EN->getNumNonChainGlueVTs() > ... need to get no results reliably ...)
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        ResultMatch = false;
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#endif
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      if (ResultsMatch) {
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        const SmallVectorImpl<MVT::SimpleValueType> &VTs = EN->getVTList();
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        const SmallVectorImpl<unsigned> &Operands = EN->getOperandList();
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        MatcherPtr.reset(new MorphNodeToMatcher(EN->getOpcodeName(),
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                                                VTs, Operands,
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                                                EN->hasChain(), EN->hasInFlag(),
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                                                EN->hasOutFlag(),
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                                                EN->hasMemRefs(),
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                                                EN->getNumFixedArityOperands(),
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                                                Pattern));
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        return;
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      }
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      // FIXME2: Kill off all the SelectionDAG::SelectNodeTo and getMachineNode
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      // variants.
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    }
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  ContractNodes(N->getNextPtr(), CGP);
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  // If we have a CheckType/CheckChildType/Record node followed by a
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  // CheckOpcode, invert the two nodes.  We prefer to do structural checks
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  // before type checks, as this opens opportunities for factoring on targets
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  // like X86 where many operations are valid on multiple types.
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  if ((isa<CheckTypeMatcher>(N) || isa<CheckChildTypeMatcher>(N) ||
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       isa<RecordMatcher>(N)) &&
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      isa<CheckOpcodeMatcher>(N->getNext())) {
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    // Unlink the two nodes from the list.
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    Matcher *CheckType = MatcherPtr.release();
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    Matcher *CheckOpcode = CheckType->takeNext();
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    Matcher *Tail = CheckOpcode->takeNext();
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    // Relink them.
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    MatcherPtr.reset(CheckOpcode);
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    CheckOpcode->setNext(CheckType);
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    CheckType->setNext(Tail);
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    return ContractNodes(MatcherPtr, CGP);
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  }
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}
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/// SinkPatternPredicates - Pattern predicates can be checked at any level of
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/// the matching tree.  The generator dumps them at the top level of the pattern
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/// though, which prevents factoring from being able to see past them.  This
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/// optimization sinks them as far down into the pattern as possible.
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///
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/// Conceptually, we'd like to sink these predicates all the way to the last
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/// matcher predicate in the series.  However, it turns out that some
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/// ComplexPatterns have side effects on the graph, so we really don't want to
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/// run a complex pattern if the pattern predicate will fail.  For this
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/// reason, we refuse to sink the pattern predicate past a ComplexPattern.
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///
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static void SinkPatternPredicates(std::unique_ptr<Matcher> &MatcherPtr) {
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  // Recursively scan for a PatternPredicate.
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  // If we reached the end of the chain, we're done.
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  Matcher *N = MatcherPtr.get();
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  if (!N) return;
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  // Walk down all members of a scope node.
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  if (ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N)) {
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    for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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      std::unique_ptr<Matcher> Child(Scope->takeChild(i));
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      SinkPatternPredicates(Child);
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      Scope->resetChild(i, Child.release());
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    }
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    return;
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  }
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  // If this node isn't a CheckPatternPredicateMatcher we keep scanning until
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  // we find one.
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  CheckPatternPredicateMatcher *CPPM =dyn_cast<CheckPatternPredicateMatcher>(N);
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  if (!CPPM)
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    return SinkPatternPredicates(N->getNextPtr());
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  // Ok, we found one, lets try to sink it. Check if we can sink it past the
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  // next node in the chain.  If not, we won't be able to change anything and
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  // might as well bail.
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  if (!CPPM->getNext()->isSafeToReorderWithPatternPredicate())
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    return;
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  // Okay, we know we can sink it past at least one node.  Unlink it from the
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  // chain and scan for the new insertion point.
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  MatcherPtr.release();  // Don't delete CPPM.
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  MatcherPtr.reset(CPPM->takeNext());
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  N = MatcherPtr.get();
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  while (N->getNext()->isSafeToReorderWithPatternPredicate())
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    N = N->getNext();
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  // At this point, we want to insert CPPM after N.
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  CPPM->setNext(N->takeNext());
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  N->setNext(CPPM);
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}
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/// FindNodeWithKind - Scan a series of matchers looking for a matcher with a
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/// specified kind.  Return null if we didn't find one otherwise return the
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/// matcher.
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static Matcher *FindNodeWithKind(Matcher *M, Matcher::KindTy Kind) {
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  for (; M; M = M->getNext())
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    if (M->getKind() == Kind)
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      return M;
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  return nullptr;
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}
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/// FactorNodes - Turn matches like this:
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///   Scope
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///     OPC_CheckType i32
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///       ABC
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///     OPC_CheckType i32
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///       XYZ
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/// into:
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///   OPC_CheckType i32
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///     Scope
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///       ABC
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///       XYZ
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///
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static void FactorNodes(std::unique_ptr<Matcher> &MatcherPtr) {
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  // If we reached the end of the chain, we're done.
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  Matcher *N = MatcherPtr.get();
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  if (!N) return;
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  // If this is not a push node, just scan for one.
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  ScopeMatcher *Scope = dyn_cast<ScopeMatcher>(N);
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  if (!Scope)
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    return FactorNodes(N->getNextPtr());
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  // Okay, pull together the children of the scope node into a vector so we can
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  // inspect it more easily.  While we're at it, bucket them up by the hash
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  // code of their first predicate.
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  SmallVector<Matcher*, 32> OptionsToMatch;
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  for (unsigned i = 0, e = Scope->getNumChildren(); i != e; ++i) {
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    // Factor the subexpression.
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    std::unique_ptr<Matcher> Child(Scope->takeChild(i));
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    FactorNodes(Child);
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    if (Matcher *N = Child.release())
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      OptionsToMatch.push_back(N);
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  }
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  SmallVector<Matcher*, 32> NewOptionsToMatch;
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  // Loop over options to match, merging neighboring patterns with identical
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  // starting nodes into a shared matcher.
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  for (unsigned OptionIdx = 0, e = OptionsToMatch.size(); OptionIdx != e;) {
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    // Find the set of matchers that start with this node.
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    Matcher *Optn = OptionsToMatch[OptionIdx++];
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    if (OptionIdx == e) {
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      NewOptionsToMatch.push_back(Optn);
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      continue;
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    }
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    // See if the next option starts with the same matcher.  If the two
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    // neighbors *do* start with the same matcher, we can factor the matcher out
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    // of at least these two patterns.  See what the maximal set we can merge
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    // together is.
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    SmallVector<Matcher*, 8> EqualMatchers;
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    EqualMatchers.push_back(Optn);
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    // Factor all of the known-equal matchers after this one into the same
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    // group.
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    while (OptionIdx != e && OptionsToMatch[OptionIdx]->isEqual(Optn))
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      EqualMatchers.push_back(OptionsToMatch[OptionIdx++]);
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    // If we found a non-equal matcher, see if it is contradictory with the
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    // current node.  If so, we know that the ordering relation between the
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    // current sets of nodes and this node don't matter.  Look past it to see if
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    // we can merge anything else into this matching group.
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    unsigned Scan = OptionIdx;
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    while (1) {
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      // If we ran out of stuff to scan, we're done.
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      if (Scan == e) break;
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      Matcher *ScanMatcher = OptionsToMatch[Scan];
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      // If we found an entry that matches out matcher, merge it into the set to
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      // handle.
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      if (Optn->isEqual(ScanMatcher)) {
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        // If is equal after all, add the option to EqualMatchers and remove it
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        // from OptionsToMatch.
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        EqualMatchers.push_back(ScanMatcher);
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        OptionsToMatch.erase(OptionsToMatch.begin()+Scan);
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        --e;
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        continue;
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      }
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      // If the option we're checking for contradicts the start of the list,
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      // skip over it.
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      if (Optn->isContradictory(ScanMatcher)) {
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        ++Scan;
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        continue;
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      }
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      // If we're scanning for a simple node, see if it occurs later in the
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      // sequence.  If so, and if we can move it up, it might be contradictory
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      // or the same as what we're looking for.  If so, reorder it.
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      if (Optn->isSimplePredicateOrRecordNode()) {
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        Matcher *M2 = FindNodeWithKind(ScanMatcher, Optn->getKind());
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        if (M2 && M2 != ScanMatcher &&
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            M2->canMoveBefore(ScanMatcher) &&
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            (M2->isEqual(Optn) || M2->isContradictory(Optn))) {
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          Matcher *MatcherWithoutM2 = ScanMatcher->unlinkNode(M2);
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          M2->setNext(MatcherWithoutM2);
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          OptionsToMatch[Scan] = M2;
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          continue;
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        }
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      }
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      // Otherwise, we don't know how to handle this entry, we have to bail.
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      break;
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    }
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    if (Scan != e &&
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        // Don't print it's obvious nothing extra could be merged anyway.
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        Scan+1 != e) {
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      DEBUG(errs() << "Couldn't merge this:\n";
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            Optn->print(errs(), 4);
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            errs() << "into this:\n";
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            OptionsToMatch[Scan]->print(errs(), 4);
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            if (Scan+1 != e)
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              OptionsToMatch[Scan+1]->printOne(errs());
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            if (Scan+2 < e)
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              OptionsToMatch[Scan+2]->printOne(errs());
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            errs() << "\n");
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    }
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    // If we only found one option starting with this matcher, no factoring is
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    // possible.
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    if (EqualMatchers.size() == 1) {
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      NewOptionsToMatch.push_back(EqualMatchers[0]);
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      continue;
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    }
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    // Factor these checks by pulling the first node off each entry and
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    // discarding it.  Take the first one off the first entry to reuse.
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    Matcher *Shared = Optn;
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    Optn = Optn->takeNext();
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    EqualMatchers[0] = Optn;
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    // Remove and delete the first node from the other matchers we're factoring.
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    for (unsigned i = 1, e = EqualMatchers.size(); i != e; ++i) {
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      Matcher *Tmp = EqualMatchers[i]->takeNext();
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      delete EqualMatchers[i];
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      EqualMatchers[i] = Tmp;
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    }
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    Shared->setNext(new ScopeMatcher(EqualMatchers));
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    // Recursively factor the newly created node.
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    FactorNodes(Shared->getNextPtr());
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    NewOptionsToMatch.push_back(Shared);
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  }
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  // If we're down to a single pattern to match, then we don't need this scope
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  // anymore.
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  if (NewOptionsToMatch.size() == 1) {
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    MatcherPtr.reset(NewOptionsToMatch[0]);
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    return;
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  }
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  if (NewOptionsToMatch.empty()) {
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    MatcherPtr.reset();
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    return;
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  }
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  // If our factoring failed (didn't achieve anything) see if we can simplify in
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  // other ways.
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 | 
						|
  // Check to see if all of the leading entries are now opcode checks.  If so,
 | 
						|
  // we can convert this Scope to be a OpcodeSwitch instead.
 | 
						|
  bool AllOpcodeChecks = true, AllTypeChecks = true;
 | 
						|
  for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
 | 
						|
    // Check to see if this breaks a series of CheckOpcodeMatchers.
 | 
						|
    if (AllOpcodeChecks &&
 | 
						|
        !isa<CheckOpcodeMatcher>(NewOptionsToMatch[i])) {
 | 
						|
#if 0
 | 
						|
      if (i > 3) {
 | 
						|
        errs() << "FAILING OPC #" << i << "\n";
 | 
						|
        NewOptionsToMatch[i]->dump();
 | 
						|
      }
 | 
						|
#endif
 | 
						|
      AllOpcodeChecks = false;
 | 
						|
    }
 | 
						|
 | 
						|
    // Check to see if this breaks a series of CheckTypeMatcher's.
 | 
						|
    if (AllTypeChecks) {
 | 
						|
      CheckTypeMatcher *CTM =
 | 
						|
        cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
 | 
						|
                                                        Matcher::CheckType));
 | 
						|
      if (!CTM ||
 | 
						|
          // iPTR checks could alias any other case without us knowing, don't
 | 
						|
          // bother with them.
 | 
						|
          CTM->getType() == MVT::iPTR ||
 | 
						|
          // SwitchType only works for result #0.
 | 
						|
          CTM->getResNo() != 0 ||
 | 
						|
          // If the CheckType isn't at the start of the list, see if we can move
 | 
						|
          // it there.
 | 
						|
          !CTM->canMoveBefore(NewOptionsToMatch[i])) {
 | 
						|
#if 0
 | 
						|
        if (i > 3 && AllTypeChecks) {
 | 
						|
          errs() << "FAILING TYPE #" << i << "\n";
 | 
						|
          NewOptionsToMatch[i]->dump();
 | 
						|
        }
 | 
						|
#endif
 | 
						|
        AllTypeChecks = false;
 | 
						|
      }
 | 
						|
    }
 | 
						|
  }
 | 
						|
  
 | 
						|
  // If all the options are CheckOpcode's, we can form the SwitchOpcode, woot.
 | 
						|
  if (AllOpcodeChecks) {
 | 
						|
    StringSet<> Opcodes;
 | 
						|
    SmallVector<std::pair<const SDNodeInfo*, Matcher*>, 8> Cases;
 | 
						|
    for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
 | 
						|
      CheckOpcodeMatcher *COM = cast<CheckOpcodeMatcher>(NewOptionsToMatch[i]);
 | 
						|
      assert(Opcodes.insert(COM->getOpcode().getEnumName()).second &&
 | 
						|
             "Duplicate opcodes not factored?");
 | 
						|
      Cases.push_back(std::make_pair(&COM->getOpcode(), COM->getNext()));
 | 
						|
    }
 | 
						|
    
 | 
						|
    MatcherPtr.reset(new SwitchOpcodeMatcher(Cases));
 | 
						|
    return;
 | 
						|
  }
 | 
						|
  
 | 
						|
  // If all the options are CheckType's, we can form the SwitchType, woot.
 | 
						|
  if (AllTypeChecks) {
 | 
						|
    DenseMap<unsigned, unsigned> TypeEntry;
 | 
						|
    SmallVector<std::pair<MVT::SimpleValueType, Matcher*>, 8> Cases;
 | 
						|
    for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i) {
 | 
						|
      CheckTypeMatcher *CTM =
 | 
						|
        cast_or_null<CheckTypeMatcher>(FindNodeWithKind(NewOptionsToMatch[i],
 | 
						|
                                                        Matcher::CheckType));
 | 
						|
      Matcher *MatcherWithoutCTM = NewOptionsToMatch[i]->unlinkNode(CTM);
 | 
						|
      MVT::SimpleValueType CTMTy = CTM->getType();
 | 
						|
      delete CTM;
 | 
						|
      
 | 
						|
      unsigned &Entry = TypeEntry[CTMTy];
 | 
						|
      if (Entry != 0) {
 | 
						|
        // If we have unfactored duplicate types, then we should factor them.
 | 
						|
        Matcher *PrevMatcher = Cases[Entry-1].second;
 | 
						|
        if (ScopeMatcher *SM = dyn_cast<ScopeMatcher>(PrevMatcher)) {
 | 
						|
          SM->setNumChildren(SM->getNumChildren()+1);
 | 
						|
          SM->resetChild(SM->getNumChildren()-1, MatcherWithoutCTM);
 | 
						|
          continue;
 | 
						|
        }
 | 
						|
        
 | 
						|
        Matcher *Entries[2] = { PrevMatcher, MatcherWithoutCTM };
 | 
						|
        Cases[Entry-1].second = new ScopeMatcher(Entries);
 | 
						|
        continue;
 | 
						|
      }
 | 
						|
      
 | 
						|
      Entry = Cases.size()+1;
 | 
						|
      Cases.push_back(std::make_pair(CTMTy, MatcherWithoutCTM));
 | 
						|
    }
 | 
						|
    
 | 
						|
    if (Cases.size() != 1) {
 | 
						|
      MatcherPtr.reset(new SwitchTypeMatcher(Cases));
 | 
						|
    } else {
 | 
						|
      // If we factored and ended up with one case, create it now.
 | 
						|
      MatcherPtr.reset(new CheckTypeMatcher(Cases[0].first, 0));
 | 
						|
      MatcherPtr->setNext(Cases[0].second);
 | 
						|
    }
 | 
						|
    return;
 | 
						|
  }
 | 
						|
  
 | 
						|
 | 
						|
  // Reassemble the Scope node with the adjusted children.
 | 
						|
  Scope->setNumChildren(NewOptionsToMatch.size());
 | 
						|
  for (unsigned i = 0, e = NewOptionsToMatch.size(); i != e; ++i)
 | 
						|
    Scope->resetChild(i, NewOptionsToMatch[i]);
 | 
						|
}
 | 
						|
 | 
						|
void
 | 
						|
llvm::OptimizeMatcher(std::unique_ptr<Matcher> &MatcherPtr,
 | 
						|
                      const CodeGenDAGPatterns &CGP) {
 | 
						|
  ContractNodes(MatcherPtr, CGP);
 | 
						|
  SinkPatternPredicates(MatcherPtr);
 | 
						|
  FactorNodes(MatcherPtr);
 | 
						|
}
 |