text: //===- CodeGenDAGPatterns.cpp - Read DAG patterns from .td file -----------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file implements the CodeGenDAGPatterns class, which is used to read and
  // represent the patterns present in a .td file for instructions.
  //
  //===----------------------------------------------------------------------===//
  
  #include "CodeGenDAGPatterns.h"
  #include "llvm/ADT/DenseSet.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallSet.h"
  #include "llvm/ADT/SmallString.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/ADT/StringMap.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/TableGen/Error.h"
  #include "llvm/TableGen/Record.h"
  #include <algorithm>
  #include <cstdio>
  #include <set>
  using namespace llvm;
  
  #define DEBUG_TYPE "dag-patterns"
  
  static inline bool isIntegerOrPtr(MVT VT) {
    return VT.isInteger() || VT == MVT::iPTR;
  }
  static inline bool isFloatingPoint(MVT VT) {
    return VT.isFloatingPoint();
  }
  static inline bool isVector(MVT VT) {
    return VT.isVector();
  }
  static inline bool isScalar(MVT VT) {
    return !VT.isVector();
  }
  
  template <typename Predicate>
  static bool berase_if(MachineValueTypeSet &S, Predicate P) {
    bool Erased = false;
    // It is ok to iterate over MachineValueTypeSet and remove elements from it
    // at the same time.
    for (MVT T : S) {
      if (!P(T))
        continue;
      Erased = true;
      S.erase(T);
    }
    return Erased;
  }
  
  // --- TypeSetByHwMode
  
  // This is a parameterized type-set class. For each mode there is a list
  // of types that are currently possible for a given tree node. Type
  // inference will apply to each mode separately.
  
  TypeSetByHwMode::TypeSetByHwMode(ArrayRef<ValueTypeByHwMode> VTList) {
    for (const ValueTypeByHwMode &VVT : VTList)
      insert(VVT);
  }
  
  bool TypeSetByHwMode::isValueTypeByHwMode(bool AllowEmpty) const {
    for (const auto &I : *this) {
      if (I.second.size() > 1)
        return false;
      if (!AllowEmpty && I.second.empty())
        return false;
    }
    return true;
  }
  
  ValueTypeByHwMode TypeSetByHwMode::getValueTypeByHwMode() const {
    assert(isValueTypeByHwMode(true) &&
           "The type set has multiple types for at least one HW mode");
    ValueTypeByHwMode VVT;
    for (const auto &I : *this) {
      MVT T = I.second.empty() ? MVT::Other : *I.second.begin();
      VVT.getOrCreateTypeForMode(I.first, T);
    }
    return VVT;
  }
  
  bool TypeSetByHwMode::isPossible() const {
    for (const auto &I : *this)
      if (!I.second.empty())
        return true;
    return false;
  }
  
  bool TypeSetByHwMode::insert(const ValueTypeByHwMode &VVT) {
    bool Changed = false;
    SmallDenseSet<unsigned, 4> Modes;
    for (const auto &P : VVT) {
      unsigned M = P.first;
      Modes.insert(M);
      // Make sure there exists a set for each specific mode from VVT.
      Changed |= getOrCreate(M).insert(P.second).second;
    }
  
    // If VVT has a default mode, add the corresponding type to all
    // modes in "this" that do not exist in VVT.
    if (Modes.count(DefaultMode)) {
      MVT DT = VVT.getType(DefaultMode);
      for (auto &I : *this)
        if (!Modes.count(I.first))
          Changed |= I.second.insert(DT).second;
    }
    return Changed;
  }
  
  // Constrain the type set to be the intersection with VTS.
  bool TypeSetByHwMode::constrain(const TypeSetByHwMode &VTS) {
    bool Changed = false;
    if (hasDefault()) {
      for (const auto &I : VTS) {
        unsigned M = I.first;
        if (M == DefaultMode || hasMode(M))
          continue;
        Map.insert({M, Map.at(DefaultMode)});
        Changed = true;
      }
    }
  
    for (auto &I : *this) {
      unsigned M = I.first;
      SetType &S = I.second;
      if (VTS.hasMode(M) || VTS.hasDefault()) {
        Changed |= intersect(I.second, VTS.get(M));
      } else if (!S.empty()) {
        S.clear();
        Changed = true;
      }
    }
    return Changed;
  }
  
  template <typename Predicate>
  bool TypeSetByHwMode::constrain(Predicate P) {
    bool Changed = false;
    for (auto &I : *this)
      Changed |= berase_if(I.second, [&P](MVT VT) { return !P(VT); });
    return Changed;
  }
  
  template <typename Predicate>
  bool TypeSetByHwMode::assign_if(const TypeSetByHwMode &VTS, Predicate P) {
    assert(empty());
    for (const auto &I : VTS) {
      SetType &S = getOrCreate(I.first);
      for (auto J : I.second)
        if (P(J))
          S.insert(J);
    }
    return !empty();
  }
  
  void TypeSetByHwMode::writeToStream(raw_ostream &OS) const {
    SmallVector<unsigned, 4> Modes;
    Modes.reserve(Map.size());
  
    for (const auto &I : *this)
      Modes.push_back(I.first);
    if (Modes.empty()) {
      OS << "{}";
      return;
    }
    array_pod_sort(Modes.begin(), Modes.end());
  
    OS << '{';
    for (unsigned M : Modes) {
      OS << ' ' << getModeName(M) << ':';
      writeToStream(get(M), OS);
    }
    OS << " }";
  }
  
  void TypeSetByHwMode::writeToStream(const SetType &S, raw_ostream &OS) {
    SmallVector<MVT, 4> Types(S.begin(), S.end());
    array_pod_sort(Types.begin(), Types.end());
  
    OS << '[';
    for (unsigned i = 0, e = Types.size(); i != e; ++i) {
      OS << ValueTypeByHwMode::getMVTName(Types[i]);
      if (i != e-1)
        OS << ' ';
    }
    OS << ']';
  }
  
  bool TypeSetByHwMode::operator==(const TypeSetByHwMode &VTS) const {
    bool HaveDefault = hasDefault();
    if (HaveDefault != VTS.hasDefault())
      return false;
  
    if (isSimple()) {
      if (VTS.isSimple())
        return *begin() == *VTS.begin();
      return false;
    }
  
    SmallDenseSet<unsigned, 4> Modes;
    for (auto &I : *this)
      Modes.insert(I.first);
    for (const auto &I : VTS)
      Modes.insert(I.first);
  
    if (HaveDefault) {
      // Both sets have default mode.
      for (unsigned M : Modes) {
        if (get(M) != VTS.get(M))
          return false;
      }
    } else {
      // Neither set has default mode.
      for (unsigned M : Modes) {
        // If there is no default mode, an empty set is equivalent to not having
        // the corresponding mode.
        bool NoModeThis = !hasMode(M) || get(M).empty();
        bool NoModeVTS = !VTS.hasMode(M) || VTS.get(M).empty();
        if (NoModeThis != NoModeVTS)
          return false;
        if (!NoModeThis)
          if (get(M) != VTS.get(M))
            return false;
      }
    }
  
    return true;
  }
  
  namespace llvm {
    raw_ostream &operator<<(raw_ostream &OS, const TypeSetByHwMode &T) {
      T.writeToStream(OS);
      return OS;
    }
  }
  
  LLVM_DUMP_METHOD
  void TypeSetByHwMode::dump() const {
    dbgs() << *this << '\n';
  }
  
  bool TypeSetByHwMode::intersect(SetType &Out, const SetType &In) {
    bool OutP = Out.count(MVT::iPTR), InP = In.count(MVT::iPTR);
    auto Int = [&In](MVT T) -> bool { return !In.count(T); };
  
    if (OutP == InP)
      return berase_if(Out, Int);
  
    // Compute the intersection of scalars separately to account for only
    // one set containing iPTR.
    // The itersection of iPTR with a set of integer scalar types that does not
    // include iPTR will result in the most specific scalar type:
    // - iPTR is more specific than any set with two elements or more
    // - iPTR is less specific than any single integer scalar type.
    // For example
    // { iPTR } * { i32 }     -> { i32 }
    // { iPTR } * { i32 i64 } -> { iPTR }
    // and
    // { iPTR i32 } * { i32 }          -> { i32 }
    // { iPTR i32 } * { i32 i64 }      -> { i32 i64 }
    // { iPTR i32 } * { i32 i64 i128 } -> { iPTR i32 }
  
    // Compute the difference between the two sets in such a way that the
    // iPTR is in the set that is being subtracted. This is to see if there
    // are any extra scalars in the set without iPTR that are not in the
    // set containing iPTR. Then the iPTR could be considered a "wildcard"
    // matching these scalars. If there is only one such scalar, it would
    // replace the iPTR, if there are more, the iPTR would be retained.
    SetType Diff;
    if (InP) {
      Diff = Out;
      berase_if(Diff, [&In](MVT T) { return In.count(T); });
      // Pre-remove these elements and rely only on InP/OutP to determine
      // whether a change has been made.
      berase_if(Out, [&Diff](MVT T) { return Diff.count(T); });
    } else {
      Diff = In;
      berase_if(Diff, [&Out](MVT T) { return Out.count(T); });
      Out.erase(MVT::iPTR);
    }
  
    // The actual intersection.
    bool Changed = berase_if(Out, Int);
    unsigned NumD = Diff.size();
    if (NumD == 0)
      return Changed;
  
    if (NumD == 1) {
      Out.insert(*Diff.begin());
      // This is a change only if Out was the one with iPTR (which is now
      // being replaced).
      Changed |= OutP;
    } else {
      // Multiple elements from Out are now replaced with iPTR.
      Out.insert(MVT::iPTR);
      Changed |= !OutP;
    }
    return Changed;
  }
  
  bool TypeSetByHwMode::validate() const {
  #ifndef NDEBUG
    if (empty())
      return true;
    bool AllEmpty = true;
    for (const auto &I : *this)
      AllEmpty &= I.second.empty();
    return !AllEmpty;
  #endif
    return true;
  }
  
  // --- TypeInfer
  
  bool TypeInfer::MergeInTypeInfo(TypeSetByHwMode &Out,
                                  const TypeSetByHwMode &In) {
    ValidateOnExit _1(Out, *this);
    In.validate();
    if (In.empty() || Out == In || TP.hasError())
      return false;
    if (Out.empty()) {
      Out = In;
      return true;
    }
  
    bool Changed = Out.constrain(In);
    if (Changed && Out.empty())
      TP.error("Type contradiction");
  
    return Changed;
  }
  
  bool TypeInfer::forceArbitrary(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError())
      return false;
    assert(!Out.empty() && "cannot pick from an empty set");
  
    bool Changed = false;
    for (auto &I : Out) {
      TypeSetByHwMode::SetType &S = I.second;
      if (S.size() <= 1)
        continue;
      MVT T = *S.begin(); // Pick the first element.
      S.clear();
      S.insert(T);
      Changed = true;
    }
    return Changed;
  }
  
  bool TypeInfer::EnforceInteger(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError())
      return false;
    if (!Out.empty())
      return Out.constrain(isIntegerOrPtr);
  
    return Out.assign_if(getLegalTypes(), isIntegerOrPtr);
  }
  
  bool TypeInfer::EnforceFloatingPoint(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError())
      return false;
    if (!Out.empty())
      return Out.constrain(isFloatingPoint);
  
    return Out.assign_if(getLegalTypes(), isFloatingPoint);
  }
  
  bool TypeInfer::EnforceScalar(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError())
      return false;
    if (!Out.empty())
      return Out.constrain(isScalar);
  
    return Out.assign_if(getLegalTypes(), isScalar);
  }
  
  bool TypeInfer::EnforceVector(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError())
      return false;
    if (!Out.empty())
      return Out.constrain(isVector);
  
    return Out.assign_if(getLegalTypes(), isVector);
  }
  
  bool TypeInfer::EnforceAny(TypeSetByHwMode &Out) {
    ValidateOnExit _1(Out, *this);
    if (TP.hasError() || !Out.empty())
      return false;
  
    Out = getLegalTypes();
    return true;
  }
  
  template <typename Iter, typename Pred, typename Less>
  static Iter min_if(Iter B, Iter E, Pred P, Less L) {
    if (B == E)
      return E;
    Iter Min = E;
    for (Iter I = B; I != E; ++I) {
      if (!P(*I))
        continue;
      if (Min == E || L(*I, *Min))
        Min = I;
    }
    return Min;
  }
  
  template <typename Iter, typename Pred, typename Less>
  static Iter max_if(Iter B, Iter E, Pred P, Less L) {
    if (B == E)
      return E;
    Iter Max = E;
    for (Iter I = B; I != E; ++I) {
      if (!P(*I))
        continue;
      if (Max == E || L(*Max, *I))
        Max = I;
    }
    return Max;
  }
  
  /// Make sure that for each type in Small, there exists a larger type in Big.
  bool TypeInfer::EnforceSmallerThan(TypeSetByHwMode &Small,
                                     TypeSetByHwMode &Big) {
    ValidateOnExit _1(Small, *this), _2(Big, *this);
    if (TP.hasError())
      return false;
    bool Changed = false;
  
    if (Small.empty())
      Changed |= EnforceAny(Small);
    if (Big.empty())
      Changed |= EnforceAny(Big);
  
    assert(Small.hasDefault() && Big.hasDefault());
  
    std::vector<unsigned> Modes = union_modes(Small, Big);
  
    // 1. Only allow integer or floating point types and make sure that
    //    both sides are both integer or both floating point.
    // 2. Make sure that either both sides have vector types, or neither
    //    of them does.
    for (unsigned M : Modes) {
      TypeSetByHwMode::SetType &S = Small.get(M);
      TypeSetByHwMode::SetType &B = Big.get(M);
  
      if (any_of(S, isIntegerOrPtr) && any_of(S, isIntegerOrPtr)) {
        auto NotInt = [](MVT VT) { return !isIntegerOrPtr(VT); };
        Changed |= berase_if(S, NotInt) |
                   berase_if(B, NotInt);
      } else if (any_of(S, isFloatingPoint) && any_of(B, isFloatingPoint)) {
        auto NotFP = [](MVT VT) { return !isFloatingPoint(VT); };
        Changed |= berase_if(S, NotFP) |
                   berase_if(B, NotFP);
      } else if (S.empty() || B.empty()) {
        Changed = !S.empty() || !B.empty();
        S.clear();
        B.clear();
      } else {
        TP.error("Incompatible types");
        return Changed;
      }
  
      if (none_of(S, isVector) || none_of(B, isVector)) {
        Changed |= berase_if(S, isVector) |
                   berase_if(B, isVector);
      }
    }
  
    auto LT = [](MVT A, MVT B) -> bool {
      return A.getScalarSizeInBits() < B.getScalarSizeInBits() ||
             (A.getScalarSizeInBits() == B.getScalarSizeInBits() &&
              A.getSizeInBits() < B.getSizeInBits());
    };
    auto LE = [](MVT A, MVT B) -> bool {
      // This function is used when removing elements: when a vector is compared
      // to a non-vector, it should return false (to avoid removal).
      if (A.isVector() != B.isVector())
        return false;
  
      // Note on the < comparison below:
      // X86 has patterns like
      //   (set VR128X:$dst, (v16i8 (X86vtrunc (v4i32 VR128X:$src1)))),
      // where the truncated vector is given a type v16i8, while the source
      // vector has type v4i32. They both have the same size in bits.
      // The minimal type in the result is obviously v16i8, and when we remove
      // all types from the source that are smaller-or-equal than v8i16, the
      // only source type would also be removed (since it's equal in size).
      return A.getScalarSizeInBits() <= B.getScalarSizeInBits() ||
             A.getSizeInBits() < B.getSizeInBits();
    };
  
    for (unsigned M : Modes) {
      TypeSetByHwMode::SetType &S = Small.get(M);
      TypeSetByHwMode::SetType &B = Big.get(M);
      // MinS = min scalar in Small, remove all scalars from Big that are
      // smaller-or-equal than MinS.
      auto MinS = min_if(S.begin(), S.end(), isScalar, LT);
      if (MinS != S.end())
        Changed |= berase_if(B, std::bind(LE, std::placeholders::_1, *MinS));
  
      // MaxS = max scalar in Big, remove all scalars from Small that are
      // larger than MaxS.
      auto MaxS = max_if(B.begin(), B.end(), isScalar, LT);
      if (MaxS != B.end())
        Changed |= berase_if(S, std::bind(LE, *MaxS, std::placeholders::_1));
  
      // MinV = min vector in Small, remove all vectors from Big that are
      // smaller-or-equal than MinV.
      auto MinV = min_if(S.begin(), S.end(), isVector, LT);
      if (MinV != S.end())
        Changed |= berase_if(B, std::bind(LE, std::placeholders::_1, *MinV));
  
      // MaxV = max vector in Big, remove all vectors from Small that are
      // larger than MaxV.
      auto MaxV = max_if(B.begin(), B.end(), isVector, LT);
      if (MaxV != B.end())
        Changed |= berase_if(S, std::bind(LE, *MaxV, std::placeholders::_1));
    }
  
    return Changed;
  }
  
  /// 1. Ensure that for each type T in Vec, T is a vector type, and that
  ///    for each type U in Elem, U is a scalar type.
  /// 2. Ensure that for each (scalar) type U in Elem, there exists a (vector)
  ///    type T in Vec, such that U is the element type of T.
  bool TypeInfer::EnforceVectorEltTypeIs(TypeSetByHwMode &Vec,
                                         TypeSetByHwMode &Elem) {
    ValidateOnExit _1(Vec, *this), _2(Elem, *this);
    if (TP.hasError())
      return false;
    bool Changed = false;
  
    if (Vec.empty())
      Changed |= EnforceVector(Vec);
    if (Elem.empty())
      Changed |= EnforceScalar(Elem);
  
    for (unsigned M : union_modes(Vec, Elem)) {
      TypeSetByHwMode::SetType &V = Vec.get(M);
      TypeSetByHwMode::SetType &E = Elem.get(M);
  
      Changed |= berase_if(V, isScalar);  // Scalar = !vector
      Changed |= berase_if(E, isVector);  // Vector = !scalar
      assert(!V.empty() && !E.empty());
  
      SmallSet<MVT,4> VT, ST;
      // Collect element types from the "vector" set.
      for (MVT T : V)
        VT.insert(T.getVectorElementType());
      // Collect scalar types from the "element" set.
      for (MVT T : E)
        ST.insert(T);
  
      // Remove from V all (vector) types whose element type is not in S.
      Changed |= berase_if(V, [&ST](MVT T) -> bool {
                                return !ST.count(T.getVectorElementType());
                              });
      // Remove from E all (scalar) types, for which there is no corresponding
      // type in V.
      Changed |= berase_if(E, [&VT](MVT T) -> bool { return !VT.count(T); });
    }
  
    return Changed;
  }
  
  bool TypeInfer::EnforceVectorEltTypeIs(TypeSetByHwMode &Vec,
                                         const ValueTypeByHwMode &VVT) {
    TypeSetByHwMode Tmp(VVT);
    ValidateOnExit _1(Vec, *this), _2(Tmp, *this);
    return EnforceVectorEltTypeIs(Vec, Tmp);
  }
  
  /// Ensure that for each type T in Sub, T is a vector type, and there
  /// exists a type U in Vec such that U is a vector type with the same
  /// element type as T and at least as many elements as T.
  bool TypeInfer::EnforceVectorSubVectorTypeIs(TypeSetByHwMode &Vec,
                                               TypeSetByHwMode &Sub) {
    ValidateOnExit _1(Vec, *this), _2(Sub, *this);
    if (TP.hasError())
      return false;
  
    /// Return true if B is a suB-vector of P, i.e. P is a suPer-vector of B.
    auto IsSubVec = [](MVT B, MVT P) -> bool {
      if (!B.isVector() || !P.isVector())
        return false;
      // Logically a <4 x i32> is a valid subvector of <n x 4 x i32>
      // but until there are obvious use-cases for this, keep the
      // types separate.
      if (B.isScalableVector() != P.isScalableVector())
        return false;
      if (B.getVectorElementType() != P.getVectorElementType())
        return false;
      return B.getVectorNumElements() < P.getVectorNumElements();
    };
  
    /// Return true if S has no element (vector type) that T is a sub-vector of,
    /// i.e. has the same element type as T and more elements.
    auto NoSubV = [&IsSubVec](const TypeSetByHwMode::SetType &S, MVT T) -> bool {
      for (const auto &I : S)
        if (IsSubVec(T, I))
          return false;
      return true;
    };
  
    /// Return true if S has no element (vector type) that T is a super-vector
    /// of, i.e. has the same element type as T and fewer elements.
    auto NoSupV = [&IsSubVec](const TypeSetByHwMode::SetType &S, MVT T) -> bool {
      for (const auto &I : S)
        if (IsSubVec(I, T))
          return false;
      return true;
    };
  
    bool Changed = false;
  
    if (Vec.empty())
      Changed |= EnforceVector(Vec);
    if (Sub.empty())
      Changed |= EnforceVector(Sub);
  
    for (unsigned M : union_modes(Vec, Sub)) {
      TypeSetByHwMode::SetType &S = Sub.get(M);
      TypeSetByHwMode::SetType &V = Vec.get(M);
  
      Changed |= berase_if(S, isScalar);
  
      // Erase all types from S that are not sub-vectors of a type in V.
      Changed |= berase_if(S, std::bind(NoSubV, V, std::placeholders::_1));
  
      // Erase all types from V that are not super-vectors of a type in S.
      Changed |= berase_if(V, std::bind(NoSupV, S, std::placeholders::_1));
    }
  
    return Changed;
  }
  
  /// 1. Ensure that V has a scalar type iff W has a scalar type.
  /// 2. Ensure that for each vector type T in V, there exists a vector
  ///    type U in W, such that T and U have the same number of elements.
  /// 3. Ensure that for each vector type U in W, there exists a vector
  ///    type T in V, such that T and U have the same number of elements
  ///    (reverse of 2).
  bool TypeInfer::EnforceSameNumElts(TypeSetByHwMode &V, TypeSetByHwMode &W) {
    ValidateOnExit _1(V, *this), _2(W, *this);
    if (TP.hasError())
      return false;
  
    bool Changed = false;
    if (V.empty())
      Changed |= EnforceAny(V);
    if (W.empty())
      Changed |= EnforceAny(W);
  
    // An actual vector type cannot have 0 elements, so we can treat scalars
    // as zero-length vectors. This way both vectors and scalars can be
    // processed identically.
    auto NoLength = [](const SmallSet<unsigned,2> &Lengths, MVT T) -> bool {
      return !Lengths.count(T.isVector() ? T.getVectorNumElements() : 0);
    };
  
    for (unsigned M : union_modes(V, W)) {
      TypeSetByHwMode::SetType &VS = V.get(M);
      TypeSetByHwMode::SetType &WS = W.get(M);
  
      SmallSet<unsigned,2> VN, WN;
      for (MVT T : VS)
        VN.insert(T.isVector() ? T.getVectorNumElements() : 0);
      for (MVT T : WS)
        WN.insert(T.isVector() ? T.getVectorNumElements() : 0);
  
      Changed |= berase_if(VS, std::bind(NoLength, WN, std::placeholders::_1));
      Changed |= berase_if(WS, std::bind(NoLength, VN, std::placeholders::_1));
    }
    return Changed;
  }
  
  /// 1. Ensure that for each type T in A, there exists a type U in B,
  ///    such that T and U have equal size in bits.
  /// 2. Ensure that for each type U in B, there exists a type T in A
  ///    such that T and U have equal size in bits (reverse of 1).
  bool TypeInfer::EnforceSameSize(TypeSetByHwMode &A, TypeSetByHwMode &B) {
    ValidateOnExit _1(A, *this), _2(B, *this);
    if (TP.hasError())
      return false;
    bool Changed = false;
    if (A.empty())
      Changed |= EnforceAny(A);
    if (B.empty())
      Changed |= EnforceAny(B);
  
    auto NoSize = [](const SmallSet<unsigned,2> &Sizes, MVT T) -> bool {
      return !Sizes.count(T.getSizeInBits());
    };
  
    for (unsigned M : union_modes(A, B)) {
      TypeSetByHwMode::SetType &AS = A.get(M);
      TypeSetByHwMode::SetType &BS = B.get(M);
      SmallSet<unsigned,2> AN, BN;
  
      for (MVT T : AS)
        AN.insert(T.getSizeInBits());
      for (MVT T : BS)
        BN.insert(T.getSizeInBits());
  
      Changed |= berase_if(AS, std::bind(NoSize, BN, std::placeholders::_1));
      Changed |= berase_if(BS, std::bind(NoSize, AN, std::placeholders::_1));
    }
  
    return Changed;
  }
  
  void TypeInfer::expandOverloads(TypeSetByHwMode &VTS) {
    ValidateOnExit _1(VTS, *this);
    TypeSetByHwMode Legal = getLegalTypes();
    bool HaveLegalDef = Legal.hasDefault();
  
    for (auto &I : VTS) {
      unsigned M = I.first;
      if (!Legal.hasMode(M) && !HaveLegalDef) {
        TP.error("Invalid mode " + Twine(M));
        return;
      }
      expandOverloads(I.second, Legal.get(M));
    }
  }
  
  void TypeInfer::expandOverloads(TypeSetByHwMode::SetType &Out,
                                  const TypeSetByHwMode::SetType &Legal) {
    std::set<MVT> Ovs;
    for (MVT T : Out) {
      if (!T.isOverloaded())
        continue;
  
      Ovs.insert(T);
      // MachineValueTypeSet allows iteration and erasing.
      Out.erase(T);
    }
  
    for (MVT Ov : Ovs) {
      switch (Ov.SimpleTy) {
        case MVT::iPTRAny:
          Out.insert(MVT::iPTR);
          return;
        case MVT::iAny:
          for (MVT T : MVT::integer_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          for (MVT T : MVT::integer_vector_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          return;
        case MVT::fAny:
          for (MVT T : MVT::fp_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          for (MVT T : MVT::fp_vector_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          return;
        case MVT::vAny:
          for (MVT T : MVT::vector_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          return;
        case MVT::Any:
          for (MVT T : MVT::all_valuetypes())
            if (Legal.count(T))
              Out.insert(T);
          return;
        default:
          break;
      }
    }
  }
  
  TypeSetByHwMode TypeInfer::getLegalTypes() {
    if (!LegalTypesCached) {
      // Stuff all types from all modes into the default mode.
      const TypeSetByHwMode &LTS = TP.getDAGPatterns().getLegalTypes();
      for (const auto &I : LTS)
        LegalCache.insert(I.second);
      LegalTypesCached = true;
    }
    TypeSetByHwMode VTS;
    VTS.getOrCreate(DefaultMode) = LegalCache;
    return VTS;
  }
  
  #ifndef NDEBUG
  TypeInfer::ValidateOnExit::~ValidateOnExit() {
    if (!VTS.validate()) {
      dbgs() << "Type set is empty for each HW mode:\n"
                "possible type contradiction in the pattern below "
                "(use -print-records with llvm-tblgen to see all "
                "expanded records).\n";
      Infer.TP.dump();
      llvm_unreachable(nullptr);
    }
  }
  #endif
  
  //===----------------------------------------------------------------------===//
  // TreePredicateFn Implementation
  //===----------------------------------------------------------------------===//
  
  /// TreePredicateFn constructor.  Here 'N' is a subclass of PatFrag.
  TreePredicateFn::TreePredicateFn(TreePattern *N) : PatFragRec(N) {
    assert(
        (!hasPredCode() || !hasImmCode()) &&
        ".td file corrupt: can't have a node predicate *and* an imm predicate");
  }
  
  bool TreePredicateFn::hasPredCode() const {
    return isLoad() || isStore() || isAtomic() ||
           !PatFragRec->getRecord()->getValueAsString("PredicateCode").empty();
  }
  
  std::string TreePredicateFn::getPredCode() const {
    std::string Code = "";
  
    if (!isLoad() && !isStore() && !isAtomic()) {
      Record *MemoryVT = getMemoryVT();
  
      if (MemoryVT)
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "MemoryVT requires IsLoad or IsStore");
    }
  
    if (!isLoad() && !isStore()) {
      if (isUnindexed())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsUnindexed requires IsLoad or IsStore");
  
      Record *ScalarMemoryVT = getScalarMemoryVT();
  
      if (ScalarMemoryVT)
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "ScalarMemoryVT requires IsLoad or IsStore");
    }
  
    if (isLoad() + isStore() + isAtomic() > 1)
      PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                      "IsLoad, IsStore, and IsAtomic are mutually exclusive");
  
    if (isLoad()) {
      if (!isUnindexed() && !isNonExtLoad() && !isAnyExtLoad() &&
          !isSignExtLoad() && !isZeroExtLoad() && getMemoryVT() == nullptr &&
          getScalarMemoryVT() == nullptr)
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsLoad cannot be used by itself");
    } else {
      if (isNonExtLoad())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsNonExtLoad requires IsLoad");
      if (isAnyExtLoad())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAnyExtLoad requires IsLoad");
      if (isSignExtLoad())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsSignExtLoad requires IsLoad");
      if (isZeroExtLoad())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsZeroExtLoad requires IsLoad");
    }
  
    if (isStore()) {
      if (!isUnindexed() && !isTruncStore() && !isNonTruncStore() &&
          getMemoryVT() == nullptr && getScalarMemoryVT() == nullptr)
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsStore cannot be used by itself");
    } else {
      if (isNonTruncStore())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsNonTruncStore requires IsStore");
      if (isTruncStore())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsTruncStore requires IsStore");
    }
  
    if (isAtomic()) {
      if (getMemoryVT() == nullptr && !isAtomicOrderingMonotonic() &&
          !isAtomicOrderingAcquire() && !isAtomicOrderingRelease() &&
          !isAtomicOrderingAcquireRelease() &&
          !isAtomicOrderingSequentiallyConsistent() &&
          !isAtomicOrderingAcquireOrStronger() &&
          !isAtomicOrderingReleaseOrStronger() &&
          !isAtomicOrderingWeakerThanAcquire() &&
          !isAtomicOrderingWeakerThanRelease())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomic cannot be used by itself");
    } else {
      if (isAtomicOrderingMonotonic())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingMonotonic requires IsAtomic");
      if (isAtomicOrderingAcquire())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingAcquire requires IsAtomic");
      if (isAtomicOrderingRelease())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingRelease requires IsAtomic");
      if (isAtomicOrderingAcquireRelease())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingAcquireRelease requires IsAtomic");
      if (isAtomicOrderingSequentiallyConsistent())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingSequentiallyConsistent requires IsAtomic");
      if (isAtomicOrderingAcquireOrStronger())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingAcquireOrStronger requires IsAtomic");
      if (isAtomicOrderingReleaseOrStronger())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingReleaseOrStronger requires IsAtomic");
      if (isAtomicOrderingWeakerThanAcquire())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsAtomicOrderingWeakerThanAcquire requires IsAtomic");
    }
  
    if (isLoad() || isStore() || isAtomic()) {
      StringRef SDNodeName =
          isLoad() ? "LoadSDNode" : isStore() ? "StoreSDNode" : "AtomicSDNode";
  
      Record *MemoryVT = getMemoryVT();
  
      if (MemoryVT)
        Code += ("if (cast<" + SDNodeName + ">(N)->getMemoryVT() != MVT::" +
                 MemoryVT->getName() + ") return false;\n")
                    .str();
    }
  
    if (isAtomic() && isAtomicOrderingMonotonic())
      Code += "if (cast<AtomicSDNode>(N)->getOrdering() != "
              "AtomicOrdering::Monotonic) return false;\n";
    if (isAtomic() && isAtomicOrderingAcquire())
      Code += "if (cast<AtomicSDNode>(N)->getOrdering() != "
              "AtomicOrdering::Acquire) return false;\n";
    if (isAtomic() && isAtomicOrderingRelease())
      Code += "if (cast<AtomicSDNode>(N)->getOrdering() != "
              "AtomicOrdering::Release) return false;\n";
    if (isAtomic() && isAtomicOrderingAcquireRelease())
      Code += "if (cast<AtomicSDNode>(N)->getOrdering() != "
              "AtomicOrdering::AcquireRelease) return false;\n";
    if (isAtomic() && isAtomicOrderingSequentiallyConsistent())
      Code += "if (cast<AtomicSDNode>(N)->getOrdering() != "
              "AtomicOrdering::SequentiallyConsistent) return false;\n";
  
    if (isAtomic() && isAtomicOrderingAcquireOrStronger())
      Code += "if (!isAcquireOrStronger(cast<AtomicSDNode>(N)->getOrdering())) "
              "return false;\n";
    if (isAtomic() && isAtomicOrderingWeakerThanAcquire())
      Code += "if (isAcquireOrStronger(cast<AtomicSDNode>(N)->getOrdering())) "
              "return false;\n";
  
    if (isAtomic() && isAtomicOrderingReleaseOrStronger())
      Code += "if (!isReleaseOrStronger(cast<AtomicSDNode>(N)->getOrdering())) "
              "return false;\n";
    if (isAtomic() && isAtomicOrderingWeakerThanRelease())
      Code += "if (isReleaseOrStronger(cast<AtomicSDNode>(N)->getOrdering())) "
              "return false;\n";
  
    if (isLoad() || isStore()) {
      StringRef SDNodeName = isLoad() ? "LoadSDNode" : "StoreSDNode";
  
      if (isUnindexed())
        Code += ("if (cast<" + SDNodeName +
                 ">(N)->getAddressingMode() != ISD::UNINDEXED) "
                 "return false;\n")
                    .str();
  
      if (isLoad()) {
        if ((isNonExtLoad() + isAnyExtLoad() + isSignExtLoad() +
             isZeroExtLoad()) > 1)
          PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                          "IsNonExtLoad, IsAnyExtLoad, IsSignExtLoad, and "
                          "IsZeroExtLoad are mutually exclusive");
        if (isNonExtLoad())
          Code += "if (cast<LoadSDNode>(N)->getExtensionType() != "
                  "ISD::NON_EXTLOAD) return false;\n";
        if (isAnyExtLoad())
          Code += "if (cast<LoadSDNode>(N)->getExtensionType() != ISD::EXTLOAD) "
                  "return false;\n";
        if (isSignExtLoad())
          Code += "if (cast<LoadSDNode>(N)->getExtensionType() != ISD::SEXTLOAD) "
                  "return false;\n";
        if (isZeroExtLoad())
          Code += "if (cast<LoadSDNode>(N)->getExtensionType() != ISD::ZEXTLOAD) "
                  "return false;\n";
      } else {
        if ((isNonTruncStore() + isTruncStore()) > 1)
          PrintFatalError(
              getOrigPatFragRecord()->getRecord()->getLoc(),
              "IsNonTruncStore, and IsTruncStore are mutually exclusive");
        if (isNonTruncStore())
          Code +=
              " if (cast<StoreSDNode>(N)->isTruncatingStore()) return false;\n";
        if (isTruncStore())
          Code +=
              " if (!cast<StoreSDNode>(N)->isTruncatingStore()) return false;\n";
      }
  
      Record *ScalarMemoryVT = getScalarMemoryVT();
  
      if (ScalarMemoryVT)
        Code += ("if (cast<" + SDNodeName +
                 ">(N)->getMemoryVT().getScalarType() != MVT::" +
                 ScalarMemoryVT->getName() + ") return false;\n")
                    .str();
    }
  
    std::string PredicateCode = PatFragRec->getRecord()->getValueAsString("PredicateCode");
  
    Code += PredicateCode;
  
    if (PredicateCode.empty() && !Code.empty())
      Code += "return true;\n";
  
    return Code;
  }
  
  bool TreePredicateFn::hasImmCode() const {
    return !PatFragRec->getRecord()->getValueAsString("ImmediateCode").empty();
  }
  
  std::string TreePredicateFn::getImmCode() const {
    return PatFragRec->getRecord()->getValueAsString("ImmediateCode");
  }
  
  bool TreePredicateFn::immCodeUsesAPInt() const {
    return getOrigPatFragRecord()->getRecord()->getValueAsBit("IsAPInt");
  }
  
  bool TreePredicateFn::immCodeUsesAPFloat() const {
    bool Unset;
    // The return value will be false when IsAPFloat is unset.
    return getOrigPatFragRecord()->getRecord()->getValueAsBitOrUnset("IsAPFloat",
                                                                     Unset);
  }
  
  bool TreePredicateFn::isPredefinedPredicateEqualTo(StringRef Field,
                                                     bool Value) const {
    bool Unset;
    bool Result =
        getOrigPatFragRecord()->getRecord()->getValueAsBitOrUnset(Field, Unset);
    if (Unset)
      return false;
    return Result == Value;
  }
  bool TreePredicateFn::isLoad() const {
    return isPredefinedPredicateEqualTo("IsLoad", true);
  }
  bool TreePredicateFn::isStore() const {
    return isPredefinedPredicateEqualTo("IsStore", true);
  }
  bool TreePredicateFn::isAtomic() const {
    return isPredefinedPredicateEqualTo("IsAtomic", true);
  }
  bool TreePredicateFn::isUnindexed() const {
    return isPredefinedPredicateEqualTo("IsUnindexed", true);
  }
  bool TreePredicateFn::isNonExtLoad() const {
    return isPredefinedPredicateEqualTo("IsNonExtLoad", true);
  }
  bool TreePredicateFn::isAnyExtLoad() const {
    return isPredefinedPredicateEqualTo("IsAnyExtLoad", true);
  }
  bool TreePredicateFn::isSignExtLoad() const {
    return isPredefinedPredicateEqualTo("IsSignExtLoad", true);
  }
  bool TreePredicateFn::isZeroExtLoad() const {
    return isPredefinedPredicateEqualTo("IsZeroExtLoad", true);
  }
  bool TreePredicateFn::isNonTruncStore() const {
    return isPredefinedPredicateEqualTo("IsTruncStore", false);
  }
  bool TreePredicateFn::isTruncStore() const {
    return isPredefinedPredicateEqualTo("IsTruncStore", true);
  }
  bool TreePredicateFn::isAtomicOrderingMonotonic() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingMonotonic", true);
  }
  bool TreePredicateFn::isAtomicOrderingAcquire() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingAcquire", true);
  }
  bool TreePredicateFn::isAtomicOrderingRelease() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingRelease", true);
  }
  bool TreePredicateFn::isAtomicOrderingAcquireRelease() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingAcquireRelease", true);
  }
  bool TreePredicateFn::isAtomicOrderingSequentiallyConsistent() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingSequentiallyConsistent",
                                        true);
  }
  bool TreePredicateFn::isAtomicOrderingAcquireOrStronger() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingAcquireOrStronger", true);
  }
  bool TreePredicateFn::isAtomicOrderingWeakerThanAcquire() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingAcquireOrStronger", false);
  }
  bool TreePredicateFn::isAtomicOrderingReleaseOrStronger() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingReleaseOrStronger", true);
  }
  bool TreePredicateFn::isAtomicOrderingWeakerThanRelease() const {
    return isPredefinedPredicateEqualTo("IsAtomicOrderingReleaseOrStronger", false);
  }
  Record *TreePredicateFn::getMemoryVT() const {
    Record *R = getOrigPatFragRecord()->getRecord();
    if (R->isValueUnset("MemoryVT"))
      return nullptr;
    return R->getValueAsDef("MemoryVT");
  }
  Record *TreePredicateFn::getScalarMemoryVT() const {
    Record *R = getOrigPatFragRecord()->getRecord();
    if (R->isValueUnset("ScalarMemoryVT"))
      return nullptr;
    return R->getValueAsDef("ScalarMemoryVT");
  }
  
  StringRef TreePredicateFn::getImmType() const {
    if (immCodeUsesAPInt())
      return "const APInt &";
    if (immCodeUsesAPFloat())
      return "const APFloat &";
    return "int64_t";
  }
  
  StringRef TreePredicateFn::getImmTypeIdentifier() const {
    if (immCodeUsesAPInt())
      return "APInt";
    else if (immCodeUsesAPFloat())
      return "APFloat";
    return "I64";
  }
  
  /// isAlwaysTrue - Return true if this is a noop predicate.
  bool TreePredicateFn::isAlwaysTrue() const {
    return !hasPredCode() && !hasImmCode();
  }
  
  /// Return the name to use in the generated code to reference this, this is
  /// "Predicate_foo" if from a pattern fragment "foo".
  std::string TreePredicateFn::getFnName() const {
    return "Predicate_" + PatFragRec->getRecord()->getName().str();
  }
  
  /// getCodeToRunOnSDNode - Return the code for the function body that
  /// evaluates this predicate.  The argument is expected to be in "Node",
  /// not N.  This handles casting and conversion to a concrete node type as
  /// appropriate.
  std::string TreePredicateFn::getCodeToRunOnSDNode() const {
    // Handle immediate predicates first.
    std::string ImmCode = getImmCode();
    if (!ImmCode.empty()) {
      if (isLoad())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsLoad cannot be used with ImmLeaf or its subclasses");
      if (isStore())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "IsStore cannot be used with ImmLeaf or its subclasses");
      if (isUnindexed())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsUnindexed cannot be used with ImmLeaf or its subclasses");
      if (isNonExtLoad())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsNonExtLoad cannot be used with ImmLeaf or its subclasses");
      if (isAnyExtLoad())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsAnyExtLoad cannot be used with ImmLeaf or its subclasses");
      if (isSignExtLoad())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsSignExtLoad cannot be used with ImmLeaf or its subclasses");
      if (isZeroExtLoad())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsZeroExtLoad cannot be used with ImmLeaf or its subclasses");
      if (isNonTruncStore())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsNonTruncStore cannot be used with ImmLeaf or its subclasses");
      if (isTruncStore())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "IsTruncStore cannot be used with ImmLeaf or its subclasses");
      if (getMemoryVT())
        PrintFatalError(getOrigPatFragRecord()->getRecord()->getLoc(),
                        "MemoryVT cannot be used with ImmLeaf or its subclasses");
      if (getScalarMemoryVT())
        PrintFatalError(
            getOrigPatFragRecord()->getRecord()->getLoc(),
            "ScalarMemoryVT cannot be used with ImmLeaf or its subclasses");
  
      std::string Result = ("    " + getImmType() + " Imm = ").str();
      if (immCodeUsesAPFloat())
        Result += "cast<ConstantFPSDNode>(Node)->getValueAPF();\n";
      else if (immCodeUsesAPInt())
        Result += "cast<ConstantSDNode>(Node)->getAPIntValue();\n";
      else
        Result += "cast<ConstantSDNode>(Node)->getSExtValue();\n";
      return Result + ImmCode;
    }
  
    // Handle arbitrary node predicates.
    assert(hasPredCode() && "Don't have any predicate code!");
    StringRef ClassName;
    if (PatFragRec->getOnlyTree()->isLeaf())
      ClassName = "SDNode";
    else {
      Record *Op = PatFragRec->getOnlyTree()->getOperator();
      ClassName = PatFragRec->getDAGPatterns().getSDNodeInfo(Op).getSDClassName();
    }
    std::string Result;
    if (ClassName == "SDNode")
      Result = "    SDNode *N = Node;\n";
    else
      Result = "    auto *N = cast<" + ClassName.str() + ">(Node);\n";
  
    return Result + getPredCode();
  }
  
  //===----------------------------------------------------------------------===//
  // PatternToMatch implementation
  //
  
  /// getPatternSize - Return the 'size' of this pattern.  We want to match large
  /// patterns before small ones.  This is used to determine the size of a
  /// pattern.
  static unsigned getPatternSize(const TreePatternNode *P,
                                 const CodeGenDAGPatterns &CGP) {
    unsigned Size = 3;  // The node itself.
    // If the root node is a ConstantSDNode, increases its size.
    // e.g. (set R32:$dst, 0).
    if (P->isLeaf() && isa<IntInit>(P->getLeafValue()))
      Size += 2;
  
    if (const ComplexPattern *AM = P->getComplexPatternInfo(CGP)) {
      Size += AM->getComplexity();
      // We don't want to count any children twice, so return early.
      return Size;
    }
  
    // If this node has some predicate function that must match, it adds to the
    // complexity of this node.
    if (!P->getPredicateFns().empty())
      ++Size;
  
    // Count children in the count if they are also nodes.
    for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i) {
      const TreePatternNode *Child = P->getChild(i);
      if (!Child->isLeaf() && Child->getNumTypes()) {
        const TypeSetByHwMode &T0 = Child->getType(0);
        // At this point, all variable type sets should be simple, i.e. only
        // have a default mode.
        if (T0.getMachineValueType() != MVT::Other) {
          Size += getPatternSize(Child, CGP);
          continue;
        }
      }
      if (Child->isLeaf()) {
        if (isa<IntInit>(Child->getLeafValue()))
          Size += 5;  // Matches a ConstantSDNode (+3) and a specific value (+2).
        else if (Child->getComplexPatternInfo(CGP))
          Size += getPatternSize(Child, CGP);
        else if (!Child->getPredicateFns().empty())
          ++Size;
      }
    }
  
    return Size;
  }
  
  /// Compute the complexity metric for the input pattern.  This roughly
  /// corresponds to the number of nodes that are covered.
  int PatternToMatch::
  getPatternComplexity(const CodeGenDAGPatterns &CGP) const {
    return getPatternSize(getSrcPattern(), CGP) + getAddedComplexity();
  }
  
  /// getPredicateCheck - Return a single string containing all of this
  /// pattern's predicates concatenated with "&&" operators.
  ///
  std::string PatternToMatch::getPredicateCheck() const {
    SmallVector<const Predicate*,4> PredList;
    for (const Predicate &P : Predicates)
      PredList.push_back(&P);
    llvm::sort(PredList.begin(), PredList.end(), deref<llvm::less>());
  
    std::string Check;
    for (unsigned i = 0, e = PredList.size(); i != e; ++i) {
      if (i != 0)
        Check += " && ";
      Check += '(' + PredList[i]->getCondString() + ')';
    }
    return Check;
  }
  
  //===----------------------------------------------------------------------===//
  // SDTypeConstraint implementation
  //
  
  SDTypeConstraint::SDTypeConstraint(Record *R, const CodeGenHwModes &CGH) {
    OperandNo = R->getValueAsInt("OperandNum");
  
    if (R->isSubClassOf("SDTCisVT")) {
      ConstraintType = SDTCisVT;
      VVT = getValueTypeByHwMode(R->getValueAsDef("VT"), CGH);
      for (const auto &P : VVT)
        if (P.second == MVT::isVoid)
          PrintFatalError(R->getLoc(), "Cannot use 'Void' as type to SDTCisVT");
    } else if (R->isSubClassOf("SDTCisPtrTy")) {
      ConstraintType = SDTCisPtrTy;
    } else if (R->isSubClassOf("SDTCisInt")) {
      ConstraintType = SDTCisInt;
    } else if (R->isSubClassOf("SDTCisFP")) {
      ConstraintType = SDTCisFP;
    } else if (R->isSubClassOf("SDTCisVec")) {
      ConstraintType = SDTCisVec;
    } else if (R->isSubClassOf("SDTCisSameAs")) {
      ConstraintType = SDTCisSameAs;
      x.SDTCisSameAs_Info.OtherOperandNum = R->getValueAsInt("OtherOperandNum");
    } else if (R->isSubClassOf("SDTCisVTSmallerThanOp")) {
      ConstraintType = SDTCisVTSmallerThanOp;
      x.SDTCisVTSmallerThanOp_Info.OtherOperandNum =
        R->getValueAsInt("OtherOperandNum");
    } else if (R->isSubClassOf("SDTCisOpSmallerThanOp")) {
      ConstraintType = SDTCisOpSmallerThanOp;
      x.SDTCisOpSmallerThanOp_Info.BigOperandNum =
        R->getValueAsInt("BigOperandNum");
    } else if (R->isSubClassOf("SDTCisEltOfVec")) {
      ConstraintType = SDTCisEltOfVec;
      x.SDTCisEltOfVec_Info.OtherOperandNum = R->getValueAsInt("OtherOpNum");
    } else if (R->isSubClassOf("SDTCisSubVecOfVec")) {
      ConstraintType = SDTCisSubVecOfVec;
      x.SDTCisSubVecOfVec_Info.OtherOperandNum =
        R->getValueAsInt("OtherOpNum");
    } else if (R->isSubClassOf("SDTCVecEltisVT")) {
      ConstraintType = SDTCVecEltisVT;
      VVT = getValueTypeByHwMode(R->getValueAsDef("VT"), CGH);
      for (const auto &P : VVT) {
        MVT T = P.second;
        if (T.isVector())
          PrintFatalError(R->getLoc(),
                          "Cannot use vector type as SDTCVecEltisVT");
        if (!T.isInteger() && !T.isFloatingPoint())
          PrintFatalError(R->getLoc(), "Must use integer or floating point type "
                                       "as SDTCVecEltisVT");
      }
    } else if (R->isSubClassOf("SDTCisSameNumEltsAs")) {
      ConstraintType = SDTCisSameNumEltsAs;
      x.SDTCisSameNumEltsAs_Info.OtherOperandNum =
        R->getValueAsInt("OtherOperandNum");
    } else if (R->isSubClassOf("SDTCisSameSizeAs")) {
      ConstraintType = SDTCisSameSizeAs;
      x.SDTCisSameSizeAs_Info.OtherOperandNum =
        R->getValueAsInt("OtherOperandNum");
    } else {
      PrintFatalError("Unrecognized SDTypeConstraint '" + R->getName() + "'!\n");
    }
  }
  
  /// getOperandNum - Return the node corresponding to operand #OpNo in tree
  /// N, and the result number in ResNo.
  static TreePatternNode *getOperandNum(unsigned OpNo, TreePatternNode *N,
                                        const SDNodeInfo &NodeInfo,
                                        unsigned &ResNo) {
    unsigned NumResults = NodeInfo.getNumResults();
    if (OpNo < NumResults) {
      ResNo = OpNo;
      return N;
    }
  
    OpNo -= NumResults;
  
    if (OpNo >= N->getNumChildren()) {
      std::string S;
      raw_string_ostream OS(S);
      OS << "Invalid operand number in type constraint "
             << (OpNo+NumResults) << " ";
      N->print(OS);
      PrintFatalError(OS.str());
    }
  
    return N->getChild(OpNo);
  }
  
  /// ApplyTypeConstraint - Given a node in a pattern, apply this type
  /// constraint to the nodes operands.  This returns true if it makes a
  /// change, false otherwise.  If a type contradiction is found, flag an error.
  bool SDTypeConstraint::ApplyTypeConstraint(TreePatternNode *N,
                                             const SDNodeInfo &NodeInfo,
                                             TreePattern &TP) const {
    if (TP.hasError())
      return false;
  
    unsigned ResNo = 0; // The result number being referenced.
    TreePatternNode *NodeToApply = getOperandNum(OperandNo, N, NodeInfo, ResNo);
    TypeInfer &TI = TP.getInfer();
  
    switch (ConstraintType) {
    case SDTCisVT:
      // Operand must be a particular type.
      return NodeToApply->UpdateNodeType(ResNo, VVT, TP);
    case SDTCisPtrTy:
      // Operand must be same as target pointer type.
      return NodeToApply->UpdateNodeType(ResNo, MVT::iPTR, TP);
    case SDTCisInt:
      // Require it to be one of the legal integer VTs.
       return TI.EnforceInteger(NodeToApply->getExtType(ResNo));
    case SDTCisFP:
      // Require it to be one of the legal fp VTs.
      return TI.EnforceFloatingPoint(NodeToApply->getExtType(ResNo));
    case SDTCisVec:
      // Require it to be one of the legal vector VTs.
      return TI.EnforceVector(NodeToApply->getExtType(ResNo));
    case SDTCisSameAs: {
      unsigned OResNo = 0;
      TreePatternNode *OtherNode =
        getOperandNum(x.SDTCisSameAs_Info.OtherOperandNum, N, NodeInfo, OResNo);
      return NodeToApply->UpdateNodeType(ResNo, OtherNode->getExtType(OResNo),TP)|
             OtherNode->UpdateNodeType(OResNo,NodeToApply->getExtType(ResNo),TP);
    }
    case SDTCisVTSmallerThanOp: {
      // The NodeToApply must be a leaf node that is a VT.  OtherOperandNum must
      // have an integer type that is smaller than the VT.
      if (!NodeToApply->isLeaf() ||
          !isa<DefInit>(NodeToApply->getLeafValue()) ||
          !static_cast<DefInit*>(NodeToApply->getLeafValue())->getDef()
                 ->isSubClassOf("ValueType")) {
        TP.error(N->getOperator()->getName() + " expects a VT operand!");
        return false;
      }
      DefInit *DI = static_cast<DefInit*>(NodeToApply->getLeafValue());
      const CodeGenTarget &T = TP.getDAGPatterns().getTargetInfo();
      auto VVT = getValueTypeByHwMode(DI->getDef(), T.getHwModes());
      TypeSetByHwMode TypeListTmp(VVT);
  
      unsigned OResNo = 0;
      TreePatternNode *OtherNode =
        getOperandNum(x.SDTCisVTSmallerThanOp_Info.OtherOperandNum, N, NodeInfo,
                      OResNo);
  
      return TI.EnforceSmallerThan(TypeListTmp, OtherNode->getExtType(OResNo));
    }
    case SDTCisOpSmallerThanOp: {
      unsigned BResNo = 0;
      TreePatternNode *BigOperand =
        getOperandNum(x.SDTCisOpSmallerThanOp_Info.BigOperandNum, N, NodeInfo,
                      BResNo);
      return TI.EnforceSmallerThan(NodeToApply->getExtType(ResNo),
                                   BigOperand->getExtType(BResNo));
    }
    case SDTCisEltOfVec: {
      unsigned VResNo = 0;
      TreePatternNode *VecOperand =
        getOperandNum(x.SDTCisEltOfVec_Info.OtherOperandNum, N, NodeInfo,
                      VResNo);
      // Filter vector types out of VecOperand that don't have the right element
      // type.
      return TI.EnforceVectorEltTypeIs(VecOperand->getExtType(VResNo),
                                       NodeToApply->getExtType(ResNo));
    }
    case SDTCisSubVecOfVec: {
      unsigned VResNo = 0;
      TreePatternNode *BigVecOperand =
        getOperandNum(x.SDTCisSubVecOfVec_Info.OtherOperandNum, N, NodeInfo,
                      VResNo);
  
      // Filter vector types out of BigVecOperand that don't have the
      // right subvector type.
      return TI.EnforceVectorSubVectorTypeIs(BigVecOperand->getExtType(VResNo),
                                             NodeToApply->getExtType(ResNo));
    }
    case SDTCVecEltisVT: {
      return TI.EnforceVectorEltTypeIs(NodeToApply->getExtType(ResNo), VVT);
    }
    case SDTCisSameNumEltsAs: {
      unsigned OResNo = 0;
      TreePatternNode *OtherNode =
        getOperandNum(x.SDTCisSameNumEltsAs_Info.OtherOperandNum,
                      N, NodeInfo, OResNo);
      return TI.EnforceSameNumElts(OtherNode->getExtType(OResNo),
                                   NodeToApply->getExtType(ResNo));
    }
    case SDTCisSameSizeAs: {
      unsigned OResNo = 0;
      TreePatternNode *OtherNode =
        getOperandNum(x.SDTCisSameSizeAs_Info.OtherOperandNum,
                      N, NodeInfo, OResNo);
      return TI.EnforceSameSize(OtherNode->getExtType(OResNo),
                                NodeToApply->getExtType(ResNo));
    }
    }
    llvm_unreachable("Invalid ConstraintType!");
  }
  
  // Update the node type to match an instruction operand or result as specified
  // in the ins or outs lists on the instruction definition. Return true if the
  // type was actually changed.
  bool TreePatternNode::UpdateNodeTypeFromInst(unsigned ResNo,
                                               Record *Operand,
                                               TreePattern &TP) {
    // The 'unknown' operand indicates that types should be inferred from the
    // context.
    if (Operand->isSubClassOf("unknown_class"))
      return false;
  
    // The Operand class specifies a type directly.
    if (Operand->isSubClassOf("Operand")) {
      Record *R = Operand->getValueAsDef("Type");
      const CodeGenTarget &T = TP.getDAGPatterns().getTargetInfo();
      return UpdateNodeType(ResNo, getValueTypeByHwMode(R, T.getHwModes()), TP);
    }
  
    // PointerLikeRegClass has a type that is determined at runtime.
    if (Operand->isSubClassOf("PointerLikeRegClass"))
      return UpdateNodeType(ResNo, MVT::iPTR, TP);
  
    // Both RegisterClass and RegisterOperand operands derive their types from a
    // register class def.
    Record *RC = nullptr;
    if (Operand->isSubClassOf("RegisterClass"))
      RC = Operand;
    else if (Operand->isSubClassOf("RegisterOperand"))
      RC = Operand->getValueAsDef("RegClass");
  
    assert(RC && "Unknown operand type");
    CodeGenTarget &Tgt = TP.getDAGPatterns().getTargetInfo();
    return UpdateNodeType(ResNo, Tgt.getRegisterClass(RC).getValueTypes(), TP);
  }
  
  bool TreePatternNode::ContainsUnresolvedType(TreePattern &TP) const {
    for (unsigned i = 0, e = Types.size(); i != e; ++i)
      if (!TP.getInfer().isConcrete(Types[i], true))
        return true;
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      if (getChild(i)->ContainsUnresolvedType(TP))
        return true;
    return false;
  }
  
  bool TreePatternNode::hasProperTypeByHwMode() const {
    for (const TypeSetByHwMode &S : Types)
      if (!S.isDefaultOnly())
        return true;
    for (TreePatternNode *C : Children)
      if (C->hasProperTypeByHwMode())
        return true;
    return false;
  }
  
  bool TreePatternNode::hasPossibleType() const {
    for (const TypeSetByHwMode &S : Types)
      if (!S.isPossible())
        return false;
    for (TreePatternNode *C : Children)
      if (!C->hasPossibleType())
        return false;
    return true;
  }
  
  bool TreePatternNode::setDefaultMode(unsigned Mode) {
    for (TypeSetByHwMode &S : Types) {
      S.makeSimple(Mode);
      // Check if the selected mode had a type conflict.
      if (S.get(DefaultMode).empty())
        return false;
    }
    for (TreePatternNode *C : Children)
      if (!C->setDefaultMode(Mode))
        return false;
    return true;
  }
  
  //===----------------------------------------------------------------------===//
  // SDNodeInfo implementation
  //
  SDNodeInfo::SDNodeInfo(Record *R, const CodeGenHwModes &CGH) : Def(R) {
    EnumName    = R->getValueAsString("Opcode");
    SDClassName = R->getValueAsString("SDClass");
    Record *TypeProfile = R->getValueAsDef("TypeProfile");
    NumResults = TypeProfile->getValueAsInt("NumResults");
    NumOperands = TypeProfile->getValueAsInt("NumOperands");
  
    // Parse the properties.
    Properties = parseSDPatternOperatorProperties(R);
  
    // Parse the type constraints.
    std::vector<Record*> ConstraintList =
      TypeProfile->getValueAsListOfDefs("Constraints");
    for (Record *R : ConstraintList)
      TypeConstraints.emplace_back(R, CGH);
  }
  
  /// getKnownType - If the type constraints on this node imply a fixed type
  /// (e.g. all stores return void, etc), then return it as an
  /// MVT::SimpleValueType.  Otherwise, return EEVT::Other.
  MVT::SimpleValueType SDNodeInfo::getKnownType(unsigned ResNo) const {
    unsigned NumResults = getNumResults();
    assert(NumResults <= 1 &&
           "We only work with nodes with zero or one result so far!");
    assert(ResNo == 0 && "Only handles single result nodes so far");
  
    for (const SDTypeConstraint &Constraint : TypeConstraints) {
      // Make sure that this applies to the correct node result.
      if (Constraint.OperandNo >= NumResults)  // FIXME: need value #
        continue;
  
      switch (Constraint.ConstraintType) {
      default: break;
      case SDTypeConstraint::SDTCisVT:
        if (Constraint.VVT.isSimple())
          return Constraint.VVT.getSimple().SimpleTy;
        break;
      case SDTypeConstraint::SDTCisPtrTy:
        return MVT::iPTR;
      }
    }
    return MVT::Other;
  }
  
  //===----------------------------------------------------------------------===//
  // TreePatternNode implementation
  //
  
  TreePatternNode::~TreePatternNode() {
  #if 0 // FIXME: implement refcounted tree nodes!
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      delete getChild(i);
  #endif
  }
  
  static unsigned GetNumNodeResults(Record *Operator, CodeGenDAGPatterns &CDP) {
    if (Operator->getName() == "set" ||
        Operator->getName() == "implicit")
      return 0;  // All return nothing.
  
    if (Operator->isSubClassOf("Intrinsic"))
      return CDP.getIntrinsic(Operator).IS.RetVTs.size();
  
    if (Operator->isSubClassOf("SDNode"))
      return CDP.getSDNodeInfo(Operator).getNumResults();
  
    if (Operator->isSubClassOf("PatFrag")) {
      // If we've already parsed this pattern fragment, get it.  Otherwise, handle
      // the forward reference case where one pattern fragment references another
      // before it is processed.
      if (TreePattern *PFRec = CDP.getPatternFragmentIfRead(Operator))
        return PFRec->getOnlyTree()->getNumTypes();
  
      // Get the result tree.
      DagInit *Tree = Operator->getValueAsDag("Fragment");
      Record *Op = nullptr;
      if (Tree)
        if (DefInit *DI = dyn_cast<DefInit>(Tree->getOperator()))
          Op = DI->getDef();
      assert(Op && "Invalid Fragment");
      return GetNumNodeResults(Op, CDP);
    }
  
    if (Operator->isSubClassOf("Instruction")) {
      CodeGenInstruction &InstInfo = CDP.getTargetInfo().getInstruction(Operator);
  
      unsigned NumDefsToAdd = InstInfo.Operands.NumDefs;
  
      // Subtract any defaulted outputs.
      for (unsigned i = 0; i != InstInfo.Operands.NumDefs; ++i) {
        Record *OperandNode = InstInfo.Operands[i].Rec;
  
        if (OperandNode->isSubClassOf("OperandWithDefaultOps") &&
            !CDP.getDefaultOperand(OperandNode).DefaultOps.empty())
          --NumDefsToAdd;
      }
  
      // Add on one implicit def if it has a resolvable type.
      if (InstInfo.HasOneImplicitDefWithKnownVT(CDP.getTargetInfo()) !=MVT::Other)
        ++NumDefsToAdd;
      return NumDefsToAdd;
    }
  
    if (Operator->isSubClassOf("SDNodeXForm"))
      return 1;  // FIXME: Generalize SDNodeXForm
  
    if (Operator->isSubClassOf("ValueType"))
      return 1;  // A type-cast of one result.
  
    if (Operator->isSubClassOf("ComplexPattern"))
      return 1;
  
    errs() << *Operator;
    PrintFatalError("Unhandled node in GetNumNodeResults");
  }
  
  void TreePatternNode::print(raw_ostream &OS) const {
    if (isLeaf())
      OS << *getLeafValue();
    else
      OS << '(' << getOperator()->getName();
  
    for (unsigned i = 0, e = Types.size(); i != e; ++i) {
      OS << ':';
      getExtType(i).writeToStream(OS);
    }
  
    if (!isLeaf()) {
      if (getNumChildren() != 0) {
        OS << " ";
        getChild(0)->print(OS);
        for (unsigned i = 1, e = getNumChildren(); i != e; ++i) {
          OS << ", ";
          getChild(i)->print(OS);
        }
      }
      OS << ")";
    }
  
    for (const TreePredicateFn &Pred : PredicateFns)
      OS << "<<P:" << Pred.getFnName() << ">>";
    if (TransformFn)
      OS << "<<X:" << TransformFn->getName() << ">>";
    if (!getName().empty())
      OS << ":$" << getName();
  
  }
  void TreePatternNode::dump() const {
    print(errs());
  }
  
  /// isIsomorphicTo - Return true if this node is recursively
  /// isomorphic to the specified node.  For this comparison, the node's
  /// entire state is considered. The assigned name is ignored, since
  /// nodes with differing names are considered isomorphic. However, if
  /// the assigned name is present in the dependent variable set, then
  /// the assigned name is considered significant and the node is
  /// isomorphic if the names match.
  bool TreePatternNode::isIsomorphicTo(const TreePatternNode *N,
                                       const MultipleUseVarSet &DepVars) const {
    if (N == this) return true;
    if (N->isLeaf() != isLeaf() || getExtTypes() != N->getExtTypes() ||
        getPredicateFns() != N->getPredicateFns() ||
        getTransformFn() != N->getTransformFn())
      return false;
  
    if (isLeaf()) {
      if (DefInit *DI = dyn_cast<DefInit>(getLeafValue())) {
        if (DefInit *NDI = dyn_cast<DefInit>(N->getLeafValue())) {
          return ((DI->getDef() == NDI->getDef())
                  && (DepVars.find(getName()) == DepVars.end()
                      || getName() == N->getName()));
        }
      }
      return getLeafValue() == N->getLeafValue();
    }
  
    if (N->getOperator() != getOperator() ||
        N->getNumChildren() != getNumChildren()) return false;
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      if (!getChild(i)->isIsomorphicTo(N->getChild(i), DepVars))
        return false;
    return true;
  }
  
  /// clone - Make a copy of this tree and all of its children.
  ///
  TreePatternNode *TreePatternNode::clone() const {
    TreePatternNode *New;
    if (isLeaf()) {
      New = new TreePatternNode(getLeafValue(), getNumTypes());
    } else {
      std::vector<TreePatternNode*> CChildren;
      CChildren.reserve(Children.size());
      for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
        CChildren.push_back(getChild(i)->clone());
      New = new TreePatternNode(getOperator(), CChildren, getNumTypes());
    }
    New->setName(getName());
    New->Types = Types;
    New->setPredicateFns(getPredicateFns());
    New->setTransformFn(getTransformFn());
    return New;
  }
  
  /// RemoveAllTypes - Recursively strip all the types of this tree.
  void TreePatternNode::RemoveAllTypes() {
    // Reset to unknown type.
    std::fill(Types.begin(), Types.end(), TypeSetByHwMode());
    if (isLeaf()) return;
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      getChild(i)->RemoveAllTypes();
  }
  
  
  /// SubstituteFormalArguments - Replace the formal arguments in this tree
  /// with actual values specified by ArgMap.
  void TreePatternNode::
  SubstituteFormalArguments(std::map<std::string, TreePatternNode*> &ArgMap) {
    if (isLeaf()) return;
  
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i) {
      TreePatternNode *Child = getChild(i);
      if (Child->isLeaf()) {
        Init *Val = Child->getLeafValue();
        // Note that, when substituting into an output pattern, Val might be an
        // UnsetInit.
        if (isa<UnsetInit>(Val) || (isa<DefInit>(Val) &&
            cast<DefInit>(Val)->getDef()->getName() == "node")) {
          // We found a use of a formal argument, replace it with its value.
          TreePatternNode *NewChild = ArgMap[Child->getName()];
          assert(NewChild && "Couldn't find formal argument!");
          assert((Child->getPredicateFns().empty() ||
                  NewChild->getPredicateFns() == Child->getPredicateFns()) &&
                 "Non-empty child predicate clobbered!");
          setChild(i, NewChild);
        }
      } else {
        getChild(i)->SubstituteFormalArguments(ArgMap);
      }
    }
  }
  
  
  /// InlinePatternFragments - If this pattern refers to any pattern
  /// fragments, inline them into place, giving us a pattern without any
  /// PatFrag references.
  TreePatternNode *TreePatternNode::InlinePatternFragments(TreePattern &TP) {
    if (TP.hasError())
      return nullptr;
  
    if (isLeaf())
       return this;  // nothing to do.
    Record *Op = getOperator();
  
    if (!Op->isSubClassOf("PatFrag")) {
      // Just recursively inline children nodes.
      for (unsigned i = 0, e = getNumChildren(); i != e; ++i) {
        TreePatternNode *Child = getChild(i);
        TreePatternNode *NewChild = Child->InlinePatternFragments(TP);
  
        assert((Child->getPredicateFns().empty() ||
                NewChild->getPredicateFns() == Child->getPredicateFns()) &&
               "Non-empty child predicate clobbered!");
  
        setChild(i, NewChild);
      }
      return this;
    }
  
    // Otherwise, we found a reference to a fragment.  First, look up its
    // TreePattern record.
    TreePattern *Frag = TP.getDAGPatterns().getPatternFragment(Op);
  
    // Verify that we are passing the right number of operands.
    if (Frag->getNumArgs() != Children.size()) {
      TP.error("'" + Op->getName() + "' fragment requires " +
               Twine(Frag->getNumArgs()) + " operands!");
      return nullptr;
    }
  
    TreePatternNode *FragTree = Frag->getOnlyTree()->clone();
  
    TreePredicateFn PredFn(Frag);
    if (!PredFn.isAlwaysTrue())
      FragTree->addPredicateFn(PredFn);
  
    // Resolve formal arguments to their actual value.
    if (Frag->getNumArgs()) {
      // Compute the map of formal to actual arguments.
      std::map<std::string, TreePatternNode*> ArgMap;
      for (unsigned i = 0, e = Frag->getNumArgs(); i != e; ++i)
        ArgMap[Frag->getArgName(i)] = getChild(i)->InlinePatternFragments(TP);
  
      FragTree->SubstituteFormalArguments(ArgMap);
    }
  
    FragTree->setName(getName());
    for (unsigned i = 0, e = Types.size(); i != e; ++i)
      FragTree->UpdateNodeType(i, getExtType(i), TP);
  
    // Transfer in the old predicates.
    for (const TreePredicateFn &Pred : getPredicateFns())
      FragTree->addPredicateFn(Pred);
  
    // Get a new copy of this fragment to stitch into here.
    //delete this;    // FIXME: implement refcounting!
  
    // The fragment we inlined could have recursive inlining that is needed.  See
    // if there are any pattern fragments in it and inline them as needed.
    return FragTree->InlinePatternFragments(TP);
  }
  
  /// getImplicitType - Check to see if the specified record has an implicit
  /// type which should be applied to it.  This will infer the type of register
  /// references from the register file information, for example.
  ///
  /// When Unnamed is set, return the type of a DAG operand with no name, such as
  /// the F8RC register class argument in:
  ///
  ///   (COPY_TO_REGCLASS GPR:$src, F8RC)
  ///
  /// When Unnamed is false, return the type of a named DAG operand such as the
  /// GPR:$src operand above.
  ///
  static TypeSetByHwMode getImplicitType(Record *R, unsigned ResNo,
                                         bool NotRegisters,
                                         bool Unnamed,
                                         TreePattern &TP) {
    CodeGenDAGPatterns &CDP = TP.getDAGPatterns();
  
    // Check to see if this is a register operand.
    if (R->isSubClassOf("RegisterOperand")) {
      assert(ResNo == 0 && "Regoperand ref only has one result!");
      if (NotRegisters)
        return TypeSetByHwMode(); // Unknown.
      Record *RegClass = R->getValueAsDef("RegClass");
      const CodeGenTarget &T = TP.getDAGPatterns().getTargetInfo();
      return TypeSetByHwMode(T.getRegisterClass(RegClass).getValueTypes());
    }
  
    // Check to see if this is a register or a register class.
    if (R->isSubClassOf("RegisterClass")) {
      assert(ResNo == 0 && "Regclass ref only has one result!");
      // An unnamed register class represents itself as an i32 immediate, for
      // example on a COPY_TO_REGCLASS instruction.
      if (Unnamed)
        return TypeSetByHwMode(MVT::i32);
  
      // In a named operand, the register class provides the possible set of
      // types.
      if (NotRegisters)
        return TypeSetByHwMode(); // Unknown.
      const CodeGenTarget &T = TP.getDAGPatterns().getTargetInfo();
      return TypeSetByHwMode(T.getRegisterClass(R).getValueTypes());
    }
  
    if (R->isSubClassOf("PatFrag")) {
      assert(ResNo == 0 && "FIXME: PatFrag with multiple results?");
      // Pattern fragment types will be resolved when they are inlined.
      return TypeSetByHwMode(); // Unknown.
    }
  
    if (R->isSubClassOf("Register")) {
      assert(ResNo == 0 && "Registers only produce one result!");
      if (NotRegisters)
        return TypeSetByHwMode(); // Unknown.
      const CodeGenTarget &T = TP.getDAGPatterns().getTargetInfo();
      return TypeSetByHwMode(T.getRegisterVTs(R));
    }
  
    if (R->isSubClassOf("SubRegIndex")) {
      assert(ResNo == 0 && "SubRegisterIndices only produce one result!");
      return TypeSetByHwMode(MVT::i32);
    }
  
    if (R->isSubClassOf("ValueType")) {
      assert(ResNo == 0 && "This node only has one result!");
      // An unnamed VTSDNode represents itself as an MVT::Other immediate.
      //
      //   (sext_inreg GPR:$src, i16)
      //                         ~~~
      if (Unnamed)
        return TypeSetByHwMode(MVT::Other);
      // With a name, the ValueType simply provides the type of the named
      // variable.
      //
      //   (sext_inreg i32:$src, i16)
      //               ~~~~~~~~
      if (NotRegisters)
        return TypeSetByHwMode(); // Unknown.
      const CodeGenHwModes &CGH = CDP.getTargetInfo().getHwModes();
      return TypeSetByHwMode(getValueTypeByHwMode(R, CGH));
    }
  
    if (R->isSubClassOf("CondCode")) {
      assert(ResNo == 0 && "This node only has one result!");
      // Using a CondCodeSDNode.
      return TypeSetByHwMode(MVT::Other);
    }
  
    if (R->isSubClassOf("ComplexPattern")) {
      assert(ResNo == 0 && "FIXME: ComplexPattern with multiple results?");
      if (NotRegisters)
        return TypeSetByHwMode(); // Unknown.
      return TypeSetByHwMode(CDP.getComplexPattern(R).getValueType());
    }
    if (R->isSubClassOf("PointerLikeRegClass")) {
      assert(ResNo == 0 && "Regclass can only have one result!");
      TypeSetByHwMode VTS(MVT::iPTR);
      TP.getInfer().expandOverloads(VTS);
      return VTS;
    }
  
    if (R->getName() == "node" || R->getName() == "srcvalue" ||
        R->getName() == "zero_reg") {
      // Placeholder.
      return TypeSetByHwMode(); // Unknown.
    }
  
    if (R->isSubClassOf("Operand")) {
      const CodeGenHwModes &CGH = CDP.getTargetInfo().getHwModes();
      Record *T = R->getValueAsDef("Type");
      return TypeSetByHwMode(getValueTypeByHwMode(T, CGH));
    }
  
    TP.error("Unknown node flavor used in pattern: " + R->getName());
    return TypeSetByHwMode(MVT::Other);
  }
  
  
  /// getIntrinsicInfo - If this node corresponds to an intrinsic, return the
  /// CodeGenIntrinsic information for it, otherwise return a null pointer.
  const CodeGenIntrinsic *TreePatternNode::
  getIntrinsicInfo(const CodeGenDAGPatterns &CDP) const {
    if (getOperator() != CDP.get_intrinsic_void_sdnode() &&
        getOperator() != CDP.get_intrinsic_w_chain_sdnode() &&
        getOperator() != CDP.get_intrinsic_wo_chain_sdnode())
      return nullptr;
  
    unsigned IID = cast<IntInit>(getChild(0)->getLeafValue())->getValue();
    return &CDP.getIntrinsicInfo(IID);
  }
  
  /// getComplexPatternInfo - If this node corresponds to a ComplexPattern,
  /// return the ComplexPattern information, otherwise return null.
  const ComplexPattern *
  TreePatternNode::getComplexPatternInfo(const CodeGenDAGPatterns &CGP) const {
    Record *Rec;
    if (isLeaf()) {
      DefInit *DI = dyn_cast<DefInit>(getLeafValue());
      if (!DI)
        return nullptr;
      Rec = DI->getDef();
    } else
      Rec = getOperator();
  
    if (!Rec->isSubClassOf("ComplexPattern"))
      return nullptr;
    return &CGP.getComplexPattern(Rec);
  }
  
  unsigned TreePatternNode::getNumMIResults(const CodeGenDAGPatterns &CGP) const {
    // A ComplexPattern specifically declares how many results it fills in.
    if (const ComplexPattern *CP = getComplexPatternInfo(CGP))
      return CP->getNumOperands();
  
    // If MIOperandInfo is specified, that gives the count.
    if (isLeaf()) {
      DefInit *DI = dyn_cast<DefInit>(getLeafValue());
      if (DI && DI->getDef()->isSubClassOf("Operand")) {
        DagInit *MIOps = DI->getDef()->getValueAsDag("MIOperandInfo");
        if (MIOps->getNumArgs())
          return MIOps->getNumArgs();
      }
    }
  
    // Otherwise there is just one result.
    return 1;
  }
  
  /// NodeHasProperty - Return true if this node has the specified property.
  bool TreePatternNode::NodeHasProperty(SDNP Property,
                                        const CodeGenDAGPatterns &CGP) const {
    if (isLeaf()) {
      if (const ComplexPattern *CP = getComplexPatternInfo(CGP))
        return CP->hasProperty(Property);
  
      return false;
    }
  
    if (Property != SDNPHasChain) {
      // The chain proprety is already present on the different intrinsic node
      // types (intrinsic_w_chain, intrinsic_void), and is not explicitly listed
      // on the intrinsic. Anything else is specific to the individual intrinsic.
      if (const CodeGenIntrinsic *Int = getIntrinsicInfo(CGP))
        return Int->hasProperty(Property);
    }
  
    if (!Operator->isSubClassOf("SDPatternOperator"))
      return false;
  
    return CGP.getSDNodeInfo(Operator).hasProperty(Property);
  }
  
  
  
  
  /// TreeHasProperty - Return true if any node in this tree has the specified
  /// property.
  bool TreePatternNode::TreeHasProperty(SDNP Property,
                                        const CodeGenDAGPatterns &CGP) const {
    if (NodeHasProperty(Property, CGP))
      return true;
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      if (getChild(i)->TreeHasProperty(Property, CGP))
        return true;
    return false;
  }
  
  /// isCommutativeIntrinsic - Return true if the node corresponds to a
  /// commutative intrinsic.
  bool
  TreePatternNode::isCommutativeIntrinsic(const CodeGenDAGPatterns &CDP) const {
    if (const CodeGenIntrinsic *Int = getIntrinsicInfo(CDP))
      return Int->isCommutative;
    return false;
  }
  
  static bool isOperandClass(const TreePatternNode *N, StringRef Class) {
    if (!N->isLeaf())
      return N->getOperator()->isSubClassOf(Class);
  
    DefInit *DI = dyn_cast<DefInit>(N->getLeafValue());
    if (DI && DI->getDef()->isSubClassOf(Class))
      return true;
  
    return false;
  }
  
  static void emitTooManyOperandsError(TreePattern &TP,
                                       StringRef InstName,
                                       unsigned Expected,
                                       unsigned Actual) {
    TP.error("Instruction '" + InstName + "' was provided " + Twine(Actual) +
             " operands but expected only " + Twine(Expected) + "!");
  }
  
  static void emitTooFewOperandsError(TreePattern &TP,
                                      StringRef InstName,
                                      unsigned Actual) {
    TP.error("Instruction '" + InstName +
             "' expects more than the provided " + Twine(Actual) + " operands!");
  }
  
  /// ApplyTypeConstraints - Apply all of the type constraints relevant to
  /// this node and its children in the tree.  This returns true if it makes a
  /// change, false otherwise.  If a type contradiction is found, flag an error.
  bool TreePatternNode::ApplyTypeConstraints(TreePattern &TP, bool NotRegisters) {
    if (TP.hasError())
      return false;
  
    CodeGenDAGPatterns &CDP = TP.getDAGPatterns();
    if (isLeaf()) {
      if (DefInit *DI = dyn_cast<DefInit>(getLeafValue())) {
        // If it's a regclass or something else known, include the type.
        bool MadeChange = false;
        for (unsigned i = 0, e = Types.size(); i != e; ++i)
          MadeChange |= UpdateNodeType(i, getImplicitType(DI->getDef(), i,
                                                          NotRegisters,
                                                          !hasName(), TP), TP);
        return MadeChange;
      }
  
      if (IntInit *II = dyn_cast<IntInit>(getLeafValue())) {
        assert(Types.size() == 1 && "Invalid IntInit");
  
        // Int inits are always integers. :)
        bool MadeChange = TP.getInfer().EnforceInteger(Types[0]);
  
        if (!TP.getInfer().isConcrete(Types[0], false))
          return MadeChange;
  
        ValueTypeByHwMode VVT = TP.getInfer().getConcrete(Types[0], false);
        for (auto &P : VVT) {
          MVT::SimpleValueType VT = P.second.SimpleTy;
          if (VT == MVT::iPTR || VT == MVT::iPTRAny)
            continue;
          unsigned Size = MVT(VT).getSizeInBits();
          // Make sure that the value is representable for this type.
          if (Size >= 32)
            continue;
          // Check that the value doesn't use more bits than we have. It must
          // either be a sign- or zero-extended equivalent of the original.
          int64_t SignBitAndAbove = II->getValue() >> (Size - 1);
          if (SignBitAndAbove == -1 || SignBitAndAbove == 0 ||
              SignBitAndAbove == 1)
            continue;
  
          TP.error("Integer value '" + Twine(II->getValue()) +
                   "' is out of range for type '" + getEnumName(VT) + "'!");
          break;
        }
        return MadeChange;
      }
  
      return false;
    }
  
    // special handling for set, which isn't really an SDNode.
    if (getOperator()->getName() == "set") {
      assert(getNumTypes() == 0 && "Set doesn't produce a value");
      assert(getNumChildren() >= 2 && "Missing RHS of a set?");
      unsigned NC = getNumChildren();
  
      TreePatternNode *SetVal = getChild(NC-1);
      bool MadeChange = SetVal->ApplyTypeConstraints(TP, NotRegisters);
  
      for (unsigned i = 0; i < NC-1; ++i) {
        TreePatternNode *Child = getChild(i);
        MadeChange |= Child->ApplyTypeConstraints(TP, NotRegisters);
  
        // Types of operands must match.
        MadeChange |= Child->UpdateNodeType(0, SetVal->getExtType(i), TP);
        MadeChange |= SetVal->UpdateNodeType(i, Child->getExtType(0), TP);
      }
      return MadeChange;
    }
  
    if (getOperator()->getName() == "implicit") {
      assert(getNumTypes() == 0 && "Node doesn't produce a value");
  
      bool MadeChange = false;
      for (unsigned i = 0; i < getNumChildren(); ++i)
        MadeChange |= getChild(i)->ApplyTypeConstraints(TP, NotRegisters);
      return MadeChange;
    }
  
    if (const CodeGenIntrinsic *Int = getIntrinsicInfo(CDP)) {
      bool MadeChange = false;
  
      // Apply the result type to the node.
      unsigned NumRetVTs = Int->IS.RetVTs.size();
      unsigned NumParamVTs = Int->IS.ParamVTs.size();
  
      for (unsigned i = 0, e = NumRetVTs; i != e; ++i)
        MadeChange |= UpdateNodeType(i, Int->IS.RetVTs[i], TP);
  
      if (getNumChildren() != NumParamVTs + 1) {
        TP.error("Intrinsic '" + Int->Name + "' expects " + Twine(NumParamVTs) +
                 " operands, not " + Twine(getNumChildren() - 1) + " operands!");
        return false;
      }
  
      // Apply type info to the intrinsic ID.
      MadeChange |= getChild(0)->UpdateNodeType(0, MVT::iPTR, TP);
  
      for (unsigned i = 0, e = getNumChildren()-1; i != e; ++i) {
        MadeChange |= getChild(i+1)->ApplyTypeConstraints(TP, NotRegisters);
  
        MVT::SimpleValueType OpVT = Int->IS.ParamVTs[i];
        assert(getChild(i+1)->getNumTypes() == 1 && "Unhandled case");
        MadeChange |= getChild(i+1)->UpdateNodeType(0, OpVT, TP);
      }
      return MadeChange;
    }
  
    if (getOperator()->isSubClassOf("SDNode")) {
      const SDNodeInfo &NI = CDP.getSDNodeInfo(getOperator());
  
      // Check that the number of operands is sane.  Negative operands -> varargs.
      if (NI.getNumOperands() >= 0 &&
          getNumChildren() != (unsigned)NI.getNumOperands()) {
        TP.error(getOperator()->getName() + " node requires exactly " +
                 Twine(NI.getNumOperands()) + " operands!");
        return false;
      }
  
      bool MadeChange = false;
      for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
        MadeChange |= getChild(i)->ApplyTypeConstraints(TP, NotRegisters);
      MadeChange |= NI.ApplyTypeConstraints(this, TP);
      return MadeChange;
    }
  
    if (getOperator()->isSubClassOf("Instruction")) {
      const DAGInstruction &Inst = CDP.getInstruction(getOperator());
      CodeGenInstruction &InstInfo =
        CDP.getTargetInfo().getInstruction(getOperator());
  
      bool MadeChange = false;
  
      // Apply the result types to the node, these come from the things in the
      // (outs) list of the instruction.
      unsigned NumResultsToAdd = std::min(InstInfo.Operands.NumDefs,
                                          Inst.getNumResults());
      for (unsigned ResNo = 0; ResNo != NumResultsToAdd; ++ResNo)
        MadeChange |= UpdateNodeTypeFromInst(ResNo, Inst.getResult(ResNo), TP);
  
      // If the instruction has implicit defs, we apply the first one as a result.
      // FIXME: This sucks, it should apply all implicit defs.
      if (!InstInfo.ImplicitDefs.empty()) {
        unsigned ResNo = NumResultsToAdd;
  
        // FIXME: Generalize to multiple possible types and multiple possible
        // ImplicitDefs.
        MVT::SimpleValueType VT =
          InstInfo.HasOneImplicitDefWithKnownVT(CDP.getTargetInfo());
  
        if (VT != MVT::Other)
          MadeChange |= UpdateNodeType(ResNo, VT, TP);
      }
  
      // If this is an INSERT_SUBREG, constrain the source and destination VTs to
      // be the same.
      if (getOperator()->getName() == "INSERT_SUBREG") {
        assert(getChild(0)->getNumTypes() == 1 && "FIXME: Unhandled");
        MadeChange |= UpdateNodeType(0, getChild(0)->getExtType(0), TP);
        MadeChange |= getChild(0)->UpdateNodeType(0, getExtType(0), TP);
      } else if (getOperator()->getName() == "REG_SEQUENCE") {
        // We need to do extra, custom typechecking for REG_SEQUENCE since it is
        // variadic.
  
        unsigned NChild = getNumChildren();
        if (NChild < 3) {
          TP.error("REG_SEQUENCE requires at least 3 operands!");
          return false;
        }
  
        if (NChild % 2 == 0) {
          TP.error("REG_SEQUENCE requires an odd number of operands!");
          return false;
        }
  
        if (!isOperandClass(getChild(0), "RegisterClass")) {
          TP.error("REG_SEQUENCE requires a RegisterClass for first operand!");
          return false;
        }
  
        for (unsigned I = 1; I < NChild; I += 2) {
          TreePatternNode *SubIdxChild = getChild(I + 1);
          if (!isOperandClass(SubIdxChild, "SubRegIndex")) {
            TP.error("REG_SEQUENCE requires a SubRegIndex for operand " +
                     Twine(I + 1) + "!");
            return false;
          }
        }
      }
  
      unsigned ChildNo = 0;
      for (unsigned i = 0, e = Inst.getNumOperands(); i != e; ++i) {
        Record *OperandNode = Inst.getOperand(i);
  
        // If the instruction expects a predicate or optional def operand, we
        // codegen this by setting the operand to it's default value if it has a
        // non-empty DefaultOps field.
        if (OperandNode->isSubClassOf("OperandWithDefaultOps") &&
            !CDP.getDefaultOperand(OperandNode).DefaultOps.empty())
          continue;
  
        // Verify that we didn't run out of provided operands.
        if (ChildNo >= getNumChildren()) {
          emitTooFewOperandsError(TP, getOperator()->getName(), getNumChildren());
          return false;
        }
  
        TreePatternNode *Child = getChild(ChildNo++);
        unsigned ChildResNo = 0;  // Instructions always use res #0 of their op.
  
        // If the operand has sub-operands, they may be provided by distinct
        // child patterns, so attempt to match each sub-operand separately.
        if (OperandNode->isSubClassOf("Operand")) {
          DagInit *MIOpInfo = OperandNode->getValueAsDag("MIOperandInfo");
          if (unsigned NumArgs = MIOpInfo->getNumArgs()) {
            // But don't do that if the whole operand is being provided by
            // a single ComplexPattern-related Operand.
  
            if (Child->getNumMIResults(CDP) < NumArgs) {
              // Match first sub-operand against the child we already have.
              Record *SubRec = cast<DefInit>(MIOpInfo->getArg(0))->getDef();
              MadeChange |=
                Child->UpdateNodeTypeFromInst(ChildResNo, SubRec, TP);
  
              // And the remaining sub-operands against subsequent children.
              for (unsigned Arg = 1; Arg < NumArgs; ++Arg) {
                if (ChildNo >= getNumChildren()) {
                  emitTooFewOperandsError(TP, getOperator()->getName(),
                                          getNumChildren());
                  return false;
                }
                Child = getChild(ChildNo++);
  
                SubRec = cast<DefInit>(MIOpInfo->getArg(Arg))->getDef();
                MadeChange |=
                  Child->UpdateNodeTypeFromInst(ChildResNo, SubRec, TP);
              }
              continue;
            }
          }
        }
  
        // If we didn't match by pieces above, attempt to match the whole
        // operand now.
        MadeChange |= Child->UpdateNodeTypeFromInst(ChildResNo, OperandNode, TP);
      }
  
      if (!InstInfo.Operands.isVariadic && ChildNo != getNumChildren()) {
        emitTooManyOperandsError(TP, getOperator()->getName(),
                                 ChildNo, getNumChildren());
        return false;
      }
  
      for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
        MadeChange |= getChild(i)->ApplyTypeConstraints(TP, NotRegisters);
      return MadeChange;
    }
  
    if (getOperator()->isSubClassOf("ComplexPattern")) {
      bool MadeChange = false;
  
      for (unsigned i = 0; i < getNumChildren(); ++i)
        MadeChange |= getChild(i)->ApplyTypeConstraints(TP, NotRegisters);
  
      return MadeChange;
    }
  
    assert(getOperator()->isSubClassOf("SDNodeXForm") && "Unknown node type!");
  
    // Node transforms always take one operand.
    if (getNumChildren() != 1) {
      TP.error("Node transform '" + getOperator()->getName() +
               "' requires one operand!");
      return false;
    }
  
    bool MadeChange = getChild(0)->ApplyTypeConstraints(TP, NotRegisters);
    return MadeChange;
  }
  
  /// OnlyOnRHSOfCommutative - Return true if this value is only allowed on the
  /// RHS of a commutative operation, not the on LHS.
  static bool OnlyOnRHSOfCommutative(TreePatternNode *N) {
    if (!N->isLeaf() && N->getOperator()->getName() == "imm")
      return true;
    if (N->isLeaf() && isa<IntInit>(N->getLeafValue()))
      return true;
    return false;
  }
  
  
  /// canPatternMatch - If it is impossible for this pattern to match on this
  /// target, fill in Reason and return false.  Otherwise, return true.  This is
  /// used as a sanity check for .td files (to prevent people from writing stuff
  /// that can never possibly work), and to prevent the pattern permuter from
  /// generating stuff that is useless.
  bool TreePatternNode::canPatternMatch(std::string &Reason,
                                        const CodeGenDAGPatterns &CDP) {
    if (isLeaf()) return true;
  
    for (unsigned i = 0, e = getNumChildren(); i != e; ++i)
      if (!getChild(i)->canPatternMatch(Reason, CDP))
        return false;
  
    // If this is an intrinsic, handle cases that would make it not match.  For
    // example, if an operand is required to be an immediate.
    if (getOperator()->isSubClassOf("Intrinsic")) {
      // TODO:
      return true;
    }
  
    if (getOperator()->isSubClassOf("ComplexPattern"))
      return true;
  
    // If this node is a commutative operator, check that the LHS isn't an
    // immediate.
    const SDNodeInfo &NodeInfo = CDP.getSDNodeInfo(getOperator());
    bool isCommIntrinsic = isCommutativeIntrinsic(CDP);
    if (NodeInfo.hasProperty(SDNPCommutative) || isCommIntrinsic) {
      // Scan all of the operands of the node and make sure that only the last one
      // is a constant node, unless the RHS also is.
      if (!OnlyOnRHSOfCommutative(getChild(getNumChildren()-1))) {
        unsigned Skip = isCommIntrinsic ? 1 : 0; // First operand is intrinsic id.
        for (unsigned i = Skip, e = getNumChildren()-1; i != e; ++i)
          if (OnlyOnRHSOfCommutative(getChild(i))) {
            Reason="Immediate value must be on the RHS of commutative operators!";
            return false;
          }
      }
    }
  
    return true;
  }
  
  //===----------------------------------------------------------------------===//
  // TreePattern implementation
  //
  
  TreePattern::TreePattern(Record *TheRec, ListInit *RawPat, bool isInput,
                           CodeGenDAGPatterns &cdp) : TheRecord(TheRec), CDP(cdp),
                           isInputPattern(isInput), HasError(false),
                           Infer(*this) {
    for (Init *I : RawPat->getValues())
      Trees.push_back(ParseTreePattern(I, ""));
  }
  
  TreePattern::TreePattern(Record *TheRec, DagInit *Pat, bool isInput,
                           CodeGenDAGPatterns &cdp) : TheRecord(TheRec), CDP(cdp),
                           isInputPattern(isInput), HasError(false),
                           Infer(*this) {
    Trees.push_back(ParseTreePattern(Pat, ""));
  }
  
  TreePattern::TreePattern(Record *TheRec, TreePatternNode *Pat, bool isInput,
                           CodeGenDAGPatterns &cdp) : TheRecord(TheRec), CDP(cdp),
                           isInputPattern(isInput), HasError(false),
                           Infer(*this) {
    Trees.push_back(Pat);
  }
  
  void TreePattern::error(const Twine &Msg) {
    if (HasError)
      return;
    dump();
    PrintError(TheRecord->getLoc(), "In " + TheRecord->getName() + ": " + Msg);
    HasError = true;
  }
  
  void TreePattern::ComputeNamedNodes() {
    for (TreePatternNode *Tree : Trees)
      ComputeNamedNodes(Tree);
  }
  
  void TreePattern::ComputeNamedNodes(TreePatternNode *N) {
    if (!N->getName().empty())
      NamedNodes[N->getName()].push_back(N);
  
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
      ComputeNamedNodes(N->getChild(i));
  }
  
  
  TreePatternNode *TreePattern::ParseTreePattern(Init *TheInit, StringRef OpName){
    if (DefInit *DI = dyn_cast<DefInit>(TheInit)) {
      Record *R = DI->getDef();
  
      // Direct reference to a leaf DagNode or PatFrag?  Turn it into a
      // TreePatternNode of its own.  For example:
      ///   (foo GPR, imm) -> (foo GPR, (imm))
      if (R->isSubClassOf("SDNode") || R->isSubClassOf("PatFrag"))
        return ParseTreePattern(
          DagInit::get(DI, nullptr,
                       std::vector<std::pair<Init*, StringInit*> >()),
          OpName);
  
      // Input argument?
      TreePatternNode *Res = new TreePatternNode(DI, 1);
      if (R->getName() == "node" && !OpName.empty()) {
        if (OpName.empty())
          error("'node' argument requires a name to match with operand list");
        Args.push_back(OpName);
      }
  
      Res->setName(OpName);
      return Res;
    }
  
    // ?:$name or just $name.
    if (isa<UnsetInit>(TheInit)) {
      if (OpName.empty())
        error("'?' argument requires a name to match with operand list");
      TreePatternNode *Res = new TreePatternNode(TheInit, 1);
      Args.push_back(OpName);
      Res->setName(OpName);
      return Res;
    }
  
    if (IntInit *II = dyn_cast<IntInit>(TheInit)) {
      if (!OpName.empty())
        error("Constant int argument should not have a name!");
      return new TreePatternNode(II, 1);
    }
  
    if (BitsInit *BI = dyn_cast<BitsInit>(TheInit)) {
      // Turn this into an IntInit.
      Init *II = BI->convertInitializerTo(IntRecTy::get());
      if (!II || !isa<IntInit>(II))
        error("Bits value must be constants!");
      return ParseTreePattern(II, OpName);
    }
  
    DagInit *Dag = dyn_cast<DagInit>(TheInit);
    if (!Dag) {
      TheInit->print(errs());
      error("Pattern has unexpected init kind!");
    }
    DefInit *OpDef = dyn_cast<DefInit>(Dag->getOperator());
    if (!OpDef) error("Pattern has unexpected operator type!");
    Record *Operator = OpDef->getDef();
  
    if (Operator->isSubClassOf("ValueType")) {
      // If the operator is a ValueType, then this must be "type cast" of a leaf
      // node.
      if (Dag->getNumArgs() != 1)
        error("Type cast only takes one operand!");
  
      TreePatternNode *New = ParseTreePattern(Dag->getArg(0),
                                              Dag->getArgNameStr(0));
  
      // Apply the type cast.
      assert(New->getNumTypes() == 1 && "FIXME: Unhandled");
      const CodeGenHwModes &CGH = getDAGPatterns().getTargetInfo().getHwModes();
      New->UpdateNodeType(0, getValueTypeByHwMode(Operator, CGH), *this);
  
      if (!OpName.empty())
        error("ValueType cast should not have a name!");
      return New;
    }
  
    // Verify that this is something that makes sense for an operator.
    if (!Operator->isSubClassOf("PatFrag") &&
        !Operator->isSubClassOf("SDNode") &&
        !Operator->isSubClassOf("Instruction") &&
        !Operator->isSubClassOf("SDNodeXForm") &&
        !Operator->isSubClassOf("Intrinsic") &&
        !Operator->isSubClassOf("ComplexPattern") &&
        Operator->getName() != "set" &&
        Operator->getName() != "implicit")
      error("Unrecognized node '" + Operator->getName() + "'!");
  
    //  Check to see if this is something that is illegal in an input pattern.
    if (isInputPattern) {
      if (Operator->isSubClassOf("Instruction") ||
          Operator->isSubClassOf("SDNodeXForm"))
        error("Cannot use '" + Operator->getName() + "' in an input pattern!");
    } else {
      if (Operator->isSubClassOf("Intrinsic"))
        error("Cannot use '" + Operator->getName() + "' in an output pattern!");
  
      if (Operator->isSubClassOf("SDNode") &&
          Operator->getName() != "imm" &&
          Operator->getName() != "fpimm" &&
          Operator->getName() != "tglobaltlsaddr" &&
          Operator->getName() != "tconstpool" &&
          Operator->getName() != "tjumptable" &&
          Operator->getName() != "tframeindex" &&
          Operator->getName() != "texternalsym" &&
          Operator->getName() != "tblockaddress" &&
          Operator->getName() != "tglobaladdr" &&
          Operator->getName() != "bb" &&
          Operator->getName() != "vt" &&
          Operator->getName() != "mcsym")
        error("Cannot use '" + Operator->getName() + "' in an output pattern!");
    }
  
    std::vector<TreePatternNode*> Children;
  
    // Parse all the operands.
    for (unsigned i = 0, e = Dag->getNumArgs(); i != e; ++i)
      Children.push_back(ParseTreePattern(Dag->getArg(i), Dag->getArgNameStr(i)));
  
    // Get the actual number of results before Operator is converted to an intrinsic
    // node (which is hard-coded to have either zero or one result).
    unsigned NumResults = GetNumNodeResults(Operator, CDP);
  
    // If the operator is an intrinsic, then this is just syntactic sugar for
    // (intrinsic_* <number>, ..children..).  Pick the right intrinsic node, and
    // convert the intrinsic name to a number.
    if (Operator->isSubClassOf("Intrinsic")) {
      const CodeGenIntrinsic &Int = getDAGPatterns().getIntrinsic(Operator);
      unsigned IID = getDAGPatterns().getIntrinsicID(Operator)+1;
  
      // If this intrinsic returns void, it must have side-effects and thus a
      // chain.
      if (Int.IS.RetVTs.empty())
        Operator = getDAGPatterns().get_intrinsic_void_sdnode();
      else if (Int.ModRef != CodeGenIntrinsic::NoMem)
        // Has side-effects, requires chain.
        Operator = getDAGPatterns().get_intrinsic_w_chain_sdnode();
      else // Otherwise, no chain.
        Operator = getDAGPatterns().get_intrinsic_wo_chain_sdnode();
  
      TreePatternNode *IIDNode = new TreePatternNode(IntInit::get(IID), 1);
      Children.insert(Children.begin(), IIDNode);
    }
  
    if (Operator->isSubClassOf("ComplexPattern")) {
      for (unsigned i = 0; i < Children.size(); ++i) {
        TreePatternNode *Child = Children[i];
  
        if (Child->getName().empty())
          error("All arguments to a ComplexPattern must be named");
  
        // Check that the ComplexPattern uses are consistent: "(MY_PAT $a, $b)"
        // and "(MY_PAT $b, $a)" should not be allowed in the same pattern;
        // neither should "(MY_PAT_1 $a, $b)" and "(MY_PAT_2 $a, $b)".
        auto OperandId = std::make_pair(Operator, i);
        auto PrevOp = ComplexPatternOperands.find(Child->getName());
        if (PrevOp != ComplexPatternOperands.end()) {
          if (PrevOp->getValue() != OperandId)
            error("All ComplexPattern operands must appear consistently: "
                  "in the same order in just one ComplexPattern instance.");
        } else
          ComplexPatternOperands[Child->getName()] = OperandId;
      }
    }
  
    TreePatternNode *Result = new TreePatternNode(Operator, Children, NumResults);
    Result->setName(OpName);
  
    if (Dag->getName()) {
      assert(Result->getName().empty());
      Result->setName(Dag->getNameStr());
    }
    return Result;
  }
  
  /// SimplifyTree - See if we can simplify this tree to eliminate something that
  /// will never match in favor of something obvious that will.  This is here
  /// strictly as a convenience to target authors because it allows them to write
  /// more type generic things and have useless type casts fold away.
  ///
  /// This returns true if any change is made.
  static bool SimplifyTree(TreePatternNode *&N) {
    if (N->isLeaf())
      return false;
  
    // If we have a bitconvert with a resolved type and if the source and
    // destination types are the same, then the bitconvert is useless, remove it.
    if (N->getOperator()->getName() == "bitconvert" &&
        N->getExtType(0).isValueTypeByHwMode(false) &&
        N->getExtType(0) == N->getChild(0)->getExtType(0) &&
        N->getName().empty()) {
      N = N->getChild(0);
      SimplifyTree(N);
      return true;
    }
  
    // Walk all children.
    bool MadeChange = false;
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
      TreePatternNode *Child = N->getChild(i);
      MadeChange |= SimplifyTree(Child);
      N->setChild(i, Child);
    }
    return MadeChange;
  }
  
  
  
  /// InferAllTypes - Infer/propagate as many types throughout the expression
  /// patterns as possible.  Return true if all types are inferred, false
  /// otherwise.  Flags an error if a type contradiction is found.
  bool TreePattern::
  InferAllTypes(const StringMap<SmallVector<TreePatternNode*,1> > *InNamedTypes) {
    if (NamedNodes.empty())
      ComputeNamedNodes();
  
    bool MadeChange = true;
    while (MadeChange) {
      MadeChange = false;
      for (TreePatternNode *&Tree : Trees) {
        MadeChange |= Tree->ApplyTypeConstraints(*this, false);
        MadeChange |= SimplifyTree(Tree);
      }
  
      // If there are constraints on our named nodes, apply them.
      for (auto &Entry : NamedNodes) {
        SmallVectorImpl<TreePatternNode*> &Nodes = Entry.second;
  
        // If we have input named node types, propagate their types to the named
        // values here.
        if (InNamedTypes) {
          if (!InNamedTypes->count(Entry.getKey())) {
            error("Node '" + std::string(Entry.getKey()) +
                  "' in output pattern but not input pattern");
            return true;
          }
  
          const SmallVectorImpl<TreePatternNode*> &InNodes =
            InNamedTypes->find(Entry.getKey())->second;
  
          // The input types should be fully resolved by now.
          for (TreePatternNode *Node : Nodes) {
            // If this node is a register class, and it is the root of the pattern
            // then we're mapping something onto an input register.  We allow
            // changing the type of the input register in this case.  This allows
            // us to match things like:
            //  def : Pat<(v1i64 (bitconvert(v2i32 DPR:$src))), (v1i64 DPR:$src)>;
            if (Node == Trees[0] && Node->isLeaf()) {
              DefInit *DI = dyn_cast<DefInit>(Node->getLeafValue());
              if (DI && (DI->getDef()->isSubClassOf("RegisterClass") ||
                         DI->getDef()->isSubClassOf("RegisterOperand")))
                continue;
            }
  
            assert(Node->getNumTypes() == 1 &&
                   InNodes[0]->getNumTypes() == 1 &&
                   "FIXME: cannot name multiple result nodes yet");
            MadeChange |= Node->UpdateNodeType(0, InNodes[0]->getExtType(0),
                                               *this);
          }
        }
  
        // If there are multiple nodes with the same name, they must all have the
        // same type.
        if (Entry.second.size() > 1) {
          for (unsigned i = 0, e = Nodes.size()-1; i != e; ++i) {
            TreePatternNode *N1 = Nodes[i], *N2 = Nodes[i+1];
            assert(N1->getNumTypes() == 1 && N2->getNumTypes() == 1 &&
                   "FIXME: cannot name multiple result nodes yet");
  
            MadeChange |= N1->UpdateNodeType(0, N2->getExtType(0), *this);
            MadeChange |= N2->UpdateNodeType(0, N1->getExtType(0), *this);
          }
        }
      }
    }
  
    bool HasUnresolvedTypes = false;
    for (const TreePatternNode *Tree : Trees)
      HasUnresolvedTypes |= Tree->ContainsUnresolvedType(*this);
    return !HasUnresolvedTypes;
  }
  
  void TreePattern::print(raw_ostream &OS) const {
    OS << getRecord()->getName();
    if (!Args.empty()) {
      OS << "(" << Args[0];
      for (unsigned i = 1, e = Args.size(); i != e; ++i)
        OS << ", " << Args[i];
      OS << ")";
    }
    OS << ": ";
  
    if (Trees.size() > 1)
      OS << "[\n";
    for (const TreePatternNode *Tree : Trees) {
      OS << "\t";
      Tree->print(OS);
      OS << "\n";
    }
  
    if (Trees.size() > 1)
      OS << "]\n";
  }
  
  void TreePattern::dump() const { print(errs()); }
  
  //===----------------------------------------------------------------------===//
  // CodeGenDAGPatterns implementation
  //
  
  CodeGenDAGPatterns::CodeGenDAGPatterns(RecordKeeper &R,
                                         PatternRewriterFn PatternRewriter)
      : Records(R), Target(R), LegalVTS(Target.getLegalValueTypes()),
        PatternRewriter(PatternRewriter) {
  
    Intrinsics = CodeGenIntrinsicTable(Records, false);
    TgtIntrinsics = CodeGenIntrinsicTable(Records, true);
    ParseNodeInfo();
    ParseNodeTransforms();
    ParseComplexPatterns();
    ParsePatternFragments();
    ParseDefaultOperands();
    ParseInstructions();
    ParsePatternFragments(/*OutFrags*/true);
    ParsePatterns();
  
    // Break patterns with parameterized types into a series of patterns,
    // where each one has a fixed type and is predicated on the conditions
    // of the associated HW mode.
    ExpandHwModeBasedTypes();
  
    // Generate variants.  For example, commutative patterns can match
    // multiple ways.  Add them to PatternsToMatch as well.
    GenerateVariants();
  
    // Infer instruction flags.  For example, we can detect loads,
    // stores, and side effects in many cases by examining an
    // instruction's pattern.
    InferInstructionFlags();
  
    // Verify that instruction flags match the patterns.
    VerifyInstructionFlags();
  }
  
  Record *CodeGenDAGPatterns::getSDNodeNamed(const std::string &Name) const {
    Record *N = Records.getDef(Name);
    if (!N || !N->isSubClassOf("SDNode"))
      PrintFatalError("Error getting SDNode '" + Name + "'!");
  
    return N;
  }
  
  // Parse all of the SDNode definitions for the target, populating SDNodes.
  void CodeGenDAGPatterns::ParseNodeInfo() {
    std::vector<Record*> Nodes = Records.getAllDerivedDefinitions("SDNode");
    const CodeGenHwModes &CGH = getTargetInfo().getHwModes();
  
    while (!Nodes.empty()) {
      Record *R = Nodes.back();
      SDNodes.insert(std::make_pair(R, SDNodeInfo(R, CGH)));
      Nodes.pop_back();
    }
  
    // Get the builtin intrinsic nodes.
    intrinsic_void_sdnode     = getSDNodeNamed("intrinsic_void");
    intrinsic_w_chain_sdnode  = getSDNodeNamed("intrinsic_w_chain");
    intrinsic_wo_chain_sdnode = getSDNodeNamed("intrinsic_wo_chain");
  }
  
  /// ParseNodeTransforms - Parse all SDNodeXForm instances into the SDNodeXForms
  /// map, and emit them to the file as functions.
  void CodeGenDAGPatterns::ParseNodeTransforms() {
    std::vector<Record*> Xforms = Records.getAllDerivedDefinitions("SDNodeXForm");
    while (!Xforms.empty()) {
      Record *XFormNode = Xforms.back();
      Record *SDNode = XFormNode->getValueAsDef("Opcode");
      StringRef Code = XFormNode->getValueAsString("XFormFunction");
      SDNodeXForms.insert(std::make_pair(XFormNode, NodeXForm(SDNode, Code)));
  
      Xforms.pop_back();
    }
  }
  
  void CodeGenDAGPatterns::ParseComplexPatterns() {
    std::vector<Record*> AMs = Records.getAllDerivedDefinitions("ComplexPattern");
    while (!AMs.empty()) {
      ComplexPatterns.insert(std::make_pair(AMs.back(), AMs.back()));
      AMs.pop_back();
    }
  }
  
  
  /// ParsePatternFragments - Parse all of the PatFrag definitions in the .td
  /// file, building up the PatternFragments map.  After we've collected them all,
  /// inline fragments together as necessary, so that there are no references left
  /// inside a pattern fragment to a pattern fragment.
  ///
  void CodeGenDAGPatterns::ParsePatternFragments(bool OutFrags) {
    std::vector<Record*> Fragments = Records.getAllDerivedDefinitions("PatFrag");
  
    // First step, parse all of the fragments.
    for (Record *Frag : Fragments) {
      if (OutFrags != Frag->isSubClassOf("OutPatFrag"))
        continue;
  
      DagInit *Tree = Frag->getValueAsDag("Fragment");
      TreePattern *P =
          (PatternFragments[Frag] = llvm::make_unique<TreePattern>(
               Frag, Tree, !Frag->isSubClassOf("OutPatFrag"),
               *this)).get();
  
      // Validate the argument list, converting it to set, to discard duplicates.
      std::vector<std::string> &Args = P->getArgList();
      // Copy the args so we can take StringRefs to them.
      auto ArgsCopy = Args;
      SmallDenseSet<StringRef, 4> OperandsSet;
      OperandsSet.insert(ArgsCopy.begin(), ArgsCopy.end());
  
      if (OperandsSet.count(""))
        P->error("Cannot have unnamed 'node' values in pattern fragment!");
  
      // Parse the operands list.
      DagInit *OpsList = Frag->getValueAsDag("Operands");
      DefInit *OpsOp = dyn_cast<DefInit>(OpsList->getOperator());
      // Special cases: ops == outs == ins. Different names are used to
      // improve readability.
      if (!OpsOp ||
          (OpsOp->getDef()->getName() != "ops" &&
           OpsOp->getDef()->getName() != "outs" &&
           OpsOp->getDef()->getName() != "ins"))
        P->error("Operands list should start with '(ops ... '!");
  
      // Copy over the arguments.
      Args.clear();
      for (unsigned j = 0, e = OpsList->getNumArgs(); j != e; ++j) {
        if (!isa<DefInit>(OpsList->getArg(j)) ||
            cast<DefInit>(OpsList->getArg(j))->getDef()->getName() != "node")
          P->error("Operands list should all be 'node' values.");
        if (!OpsList->getArgName(j))
          P->error("Operands list should have names for each operand!");
        StringRef ArgNameStr = OpsList->getArgNameStr(j);
        if (!OperandsSet.count(ArgNameStr))
          P->error("'" + ArgNameStr +
                   "' does not occur in pattern or was multiply specified!");
        OperandsSet.erase(ArgNameStr);
        Args.push_back(ArgNameStr);
      }
  
      if (!OperandsSet.empty())
        P->error("Operands list does not contain an entry for operand '" +
                 *OperandsSet.begin() + "'!");
  
      // If there is a code init for this fragment, keep track of the fact that
      // this fragment uses it.
      TreePredicateFn PredFn(P);
      if (!PredFn.isAlwaysTrue())
        P->getOnlyTree()->addPredicateFn(PredFn);
  
      // If there is a node transformation corresponding to this, keep track of
      // it.
      Record *Transform = Frag->getValueAsDef("OperandTransform");
      if (!getSDNodeTransform(Transform).second.empty())    // not noop xform?
        P->getOnlyTree()->setTransformFn(Transform);
    }
  
    // Now that we've parsed all of the tree fragments, do a closure on them so
    // that there are not references to PatFrags left inside of them.
    for (Record *Frag : Fragments) {
      if (OutFrags != Frag->isSubClassOf("OutPatFrag"))
        continue;
  
      TreePattern &ThePat = *PatternFragments[Frag];
      ThePat.InlinePatternFragments();
  
      // Infer as many types as possible.  Don't worry about it if we don't infer
      // all of them, some may depend on the inputs of the pattern.
      ThePat.InferAllTypes();
      ThePat.resetError();
  
      // If debugging, print out the pattern fragment result.
      DEBUG(ThePat.dump());
    }
  }
  
  void CodeGenDAGPatterns::ParseDefaultOperands() {
    std::vector<Record*> DefaultOps;
    DefaultOps = Records.getAllDerivedDefinitions("OperandWithDefaultOps");
  
    // Find some SDNode.
    assert(!SDNodes.empty() && "No SDNodes parsed?");
    Init *SomeSDNode = DefInit::get(SDNodes.begin()->first);
  
    for (unsigned i = 0, e = DefaultOps.size(); i != e; ++i) {
      DagInit *DefaultInfo = DefaultOps[i]->getValueAsDag("DefaultOps");
  
      // Clone the DefaultInfo dag node, changing the operator from 'ops' to
      // SomeSDnode so that we can parse this.
      std::vector<std::pair<Init*, StringInit*> > Ops;
      for (unsigned op = 0, e = DefaultInfo->getNumArgs(); op != e; ++op)
        Ops.push_back(std::make_pair(DefaultInfo->getArg(op),
                                     DefaultInfo->getArgName(op)));
      DagInit *DI = DagInit::get(SomeSDNode, nullptr, Ops);
  
      // Create a TreePattern to parse this.
      TreePattern P(DefaultOps[i], DI, false, *this);
      assert(P.getNumTrees() == 1 && "This ctor can only produce one tree!");
  
      // Copy the operands over into a DAGDefaultOperand.
      DAGDefaultOperand DefaultOpInfo;
  
      TreePatternNode *T = P.getTree(0);
      for (unsigned op = 0, e = T->getNumChildren(); op != e; ++op) {
        TreePatternNode *TPN = T->getChild(op);
        while (TPN->ApplyTypeConstraints(P, false))
          /* Resolve all types */;
  
        if (TPN->ContainsUnresolvedType(P)) {
          PrintFatalError("Value #" + Twine(i) + " of OperandWithDefaultOps '" +
                          DefaultOps[i]->getName() +
                          "' doesn't have a concrete type!");
        }
        DefaultOpInfo.DefaultOps.push_back(TPN);
      }
  
      // Insert it into the DefaultOperands map so we can find it later.
      DefaultOperands[DefaultOps[i]] = DefaultOpInfo;
    }
  }
  
  /// HandleUse - Given "Pat" a leaf in the pattern, check to see if it is an
  /// instruction input.  Return true if this is a real use.
  static bool HandleUse(TreePattern *I, TreePatternNode *Pat,
                        std::map<std::string, TreePatternNode*> &InstInputs) {
    // No name -> not interesting.
    if (Pat->getName().empty()) {
      if (Pat->isLeaf()) {
        DefInit *DI = dyn_cast<DefInit>(Pat->getLeafValue());
        if (DI && (DI->getDef()->isSubClassOf("RegisterClass") ||
                   DI->getDef()->isSubClassOf("RegisterOperand")))
          I->error("Input " + DI->getDef()->getName() + " must be named!");
      }
      return false;
    }
  
    Record *Rec;
    if (Pat->isLeaf()) {
      DefInit *DI = dyn_cast<DefInit>(Pat->getLeafValue());
      if (!DI) I->error("Input $" + Pat->getName() + " must be an identifier!");
      Rec = DI->getDef();
    } else {
      Rec = Pat->getOperator();
    }
  
    // SRCVALUE nodes are ignored.
    if (Rec->getName() == "srcvalue")
      return false;
  
    TreePatternNode *&Slot = InstInputs[Pat->getName()];
    if (!Slot) {
      Slot = Pat;
      return true;
    }
    Record *SlotRec;
    if (Slot->isLeaf()) {
      SlotRec = cast<DefInit>(Slot->getLeafValue())->getDef();
    } else {
      assert(Slot->getNumChildren() == 0 && "can't be a use with children!");
      SlotRec = Slot->getOperator();
    }
  
    // Ensure that the inputs agree if we've already seen this input.
    if (Rec != SlotRec)
      I->error("All $" + Pat->getName() + " inputs must agree with each other");
    if (Slot->getExtTypes() != Pat->getExtTypes())
      I->error("All $" + Pat->getName() + " inputs must agree with each other");
    return true;
  }
  
  /// FindPatternInputsAndOutputs - Scan the specified TreePatternNode (which is
  /// part of "I", the instruction), computing the set of inputs and outputs of
  /// the pattern.  Report errors if we see anything naughty.
  void CodeGenDAGPatterns::
  FindPatternInputsAndOutputs(TreePattern *I, TreePatternNode *Pat,
                              std::map<std::string, TreePatternNode*> &InstInputs,
                              std::map<std::string, TreePatternNode*>&InstResults,
                              std::vector<Record*> &InstImpResults) {
    if (Pat->isLeaf()) {
      bool isUse = HandleUse(I, Pat, InstInputs);
      if (!isUse && Pat->getTransformFn())
        I->error("Cannot specify a transform function for a non-input value!");
      return;
    }
  
    if (Pat->getOperator()->getName() == "implicit") {
      for (unsigned i = 0, e = Pat->getNumChildren(); i != e; ++i) {
        TreePatternNode *Dest = Pat->getChild(i);
        if (!Dest->isLeaf())
          I->error("implicitly defined value should be a register!");
  
        DefInit *Val = dyn_cast<DefInit>(Dest->getLeafValue());
        if (!Val || !Val->getDef()->isSubClassOf("Register"))
          I->error("implicitly defined value should be a register!");
        InstImpResults.push_back(Val->getDef());
      }
      return;
    }
  
    if (Pat->getOperator()->getName() != "set") {
      // If this is not a set, verify that the children nodes are not void typed,
      // and recurse.
      for (unsigned i = 0, e = Pat->getNumChildren(); i != e; ++i) {
        if (Pat->getChild(i)->getNumTypes() == 0)
          I->error("Cannot have void nodes inside of patterns!");
        FindPatternInputsAndOutputs(I, Pat->getChild(i), InstInputs, InstResults,
                                    InstImpResults);
      }
  
      // If this is a non-leaf node with no children, treat it basically as if
      // it were a leaf.  This handles nodes like (imm).
      bool isUse = HandleUse(I, Pat, InstInputs);
  
      if (!isUse && Pat->getTransformFn())
        I->error("Cannot specify a transform function for a non-input value!");
      return;
    }
  
    // Otherwise, this is a set, validate and collect instruction results.
    if (Pat->getNumChildren() == 0)
      I->error("set requires operands!");
  
    if (Pat->getTransformFn())
      I->error("Cannot specify a transform function on a set node!");
  
    // Check the set destinations.
    unsigned NumDests = Pat->getNumChildren()-1;
    for (unsigned i = 0; i != NumDests; ++i) {
      TreePatternNode *Dest = Pat->getChild(i);
      if (!Dest->isLeaf())
        I->error("set destination should be a register!");
  
      DefInit *Val = dyn_cast<DefInit>(Dest->getLeafValue());
      if (!Val) {
        I->error("set destination should be a register!");
        continue;
      }
  
      if (Val->getDef()->isSubClassOf("RegisterClass") ||
          Val->getDef()->isSubClassOf("ValueType") ||
          Val->getDef()->isSubClassOf("RegisterOperand") ||
          Val->getDef()->isSubClassOf("PointerLikeRegClass")) {
        if (Dest->getName().empty())
          I->error("set destination must have a name!");
        if (InstResults.count(Dest->getName()))
          I->error("cannot set '" + Dest->getName() +"' multiple times");
        InstResults[Dest->getName()] = Dest;
      } else if (Val->getDef()->isSubClassOf("Register")) {
        InstImpResults.push_back(Val->getDef());
      } else {
        I->error("set destination should be a register!");
      }
    }
  
    // Verify and collect info from the computation.
    FindPatternInputsAndOutputs(I, Pat->getChild(NumDests),
                                InstInputs, InstResults, InstImpResults);
  }
  
  //===----------------------------------------------------------------------===//
  // Instruction Analysis
  //===----------------------------------------------------------------------===//
  
  class InstAnalyzer {
    const CodeGenDAGPatterns &CDP;
  public:
    bool hasSideEffects;
    bool mayStore;
    bool mayLoad;
    bool isBitcast;
    bool isVariadic;
  
    InstAnalyzer(const CodeGenDAGPatterns &cdp)
      : CDP(cdp), hasSideEffects(false), mayStore(false), mayLoad(false),
        isBitcast(false), isVariadic(false) {}
  
    void Analyze(const TreePattern *Pat) {
      // Assume only the first tree is the pattern. The others are clobber nodes.
      AnalyzeNode(Pat->getTree(0));
    }
  
    void Analyze(const PatternToMatch &Pat) {
      AnalyzeNode(Pat.getSrcPattern());
    }
  
  private:
    bool IsNodeBitcast(const TreePatternNode *N) const {
      if (hasSideEffects || mayLoad || mayStore || isVariadic)
        return false;
  
      if (N->getNumChildren() != 2)
        return false;
  
      const TreePatternNode *N0 = N->getChild(0);
      if (!N0->isLeaf() || !isa<DefInit>(N0->getLeafValue()))
        return false;
  
      const TreePatternNode *N1 = N->getChild(1);
      if (N1->isLeaf())
        return false;
      if (N1->getNumChildren() != 1 || !N1->getChild(0)->isLeaf())
        return false;
  
      const SDNodeInfo &OpInfo = CDP.getSDNodeInfo(N1->getOperator());
      if (OpInfo.getNumResults() != 1 || OpInfo.getNumOperands() != 1)
        return false;
      return OpInfo.getEnumName() == "ISD::BITCAST";
    }
  
  public:
    void AnalyzeNode(const TreePatternNode *N) {
      if (N->isLeaf()) {
        if (DefInit *DI = dyn_cast<DefInit>(N->getLeafValue())) {
          Record *LeafRec = DI->getDef();
          // Handle ComplexPattern leaves.
          if (LeafRec->isSubClassOf("ComplexPattern")) {
            const ComplexPattern &CP = CDP.getComplexPattern(LeafRec);
            if (CP.hasProperty(SDNPMayStore)) mayStore = true;
            if (CP.hasProperty(SDNPMayLoad)) mayLoad = true;
            if (CP.hasProperty(SDNPSideEffect)) hasSideEffects = true;
          }
        }
        return;
      }
  
      // Analyze children.
      for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
        AnalyzeNode(N->getChild(i));
  
      // Ignore set nodes, which are not SDNodes.
      if (N->getOperator()->getName() == "set") {
        isBitcast = IsNodeBitcast(N);
        return;
      }
  
      // Notice properties of the node.
      if (N->NodeHasProperty(SDNPMayStore, CDP)) mayStore = true;
      if (N->NodeHasProperty(SDNPMayLoad, CDP)) mayLoad = true;
      if (N->NodeHasProperty(SDNPSideEffect, CDP)) hasSideEffects = true;
      if (N->NodeHasProperty(SDNPVariadic, CDP)) isVariadic = true;
  
      if (const CodeGenIntrinsic *IntInfo = N->getIntrinsicInfo(CDP)) {
        // If this is an intrinsic, analyze it.
        if (IntInfo->ModRef & CodeGenIntrinsic::MR_Ref)
          mayLoad = true;// These may load memory.
  
        if (IntInfo->ModRef & CodeGenIntrinsic::MR_Mod)
          mayStore = true;// Intrinsics that can write to memory are 'mayStore'.
  
        if (IntInfo->ModRef >= CodeGenIntrinsic::ReadWriteMem ||
            IntInfo->hasSideEffects)
          // ReadWriteMem intrinsics can have other strange effects.
          hasSideEffects = true;
      }
    }
  
  };
  
  static bool InferFromPattern(CodeGenInstruction &InstInfo,
                               const InstAnalyzer &PatInfo,
                               Record *PatDef) {
    bool Error = false;
  
    // Remember where InstInfo got its flags.
    if (InstInfo.hasUndefFlags())
        InstInfo.InferredFrom = PatDef;
  
    // Check explicitly set flags for consistency.
    if (InstInfo.hasSideEffects != PatInfo.hasSideEffects &&
        !InstInfo.hasSideEffects_Unset) {
      // Allow explicitly setting hasSideEffects = 1 on instructions, even when
      // the pattern has no side effects. That could be useful for div/rem
      // instructions that may trap.
      if (!InstInfo.hasSideEffects) {
        Error = true;
        PrintError(PatDef->getLoc(), "Pattern doesn't match hasSideEffects = " +
                   Twine(InstInfo.hasSideEffects));
      }
    }
  
    if (InstInfo.mayStore != PatInfo.mayStore && !InstInfo.mayStore_Unset) {
      Error = true;
      PrintError(PatDef->getLoc(), "Pattern doesn't match mayStore = " +
                 Twine(InstInfo.mayStore));
    }
  
    if (InstInfo.mayLoad != PatInfo.mayLoad && !InstInfo.mayLoad_Unset) {
      // Allow explicitly setting mayLoad = 1, even when the pattern has no loads.
      // Some targets translate immediates to loads.
      if (!InstInfo.mayLoad) {
        Error = true;
        PrintError(PatDef->getLoc(), "Pattern doesn't match mayLoad = " +
                   Twine(InstInfo.mayLoad));
      }
    }
  
    // Transfer inferred flags.
    InstInfo.hasSideEffects |= PatInfo.hasSideEffects;
    InstInfo.mayStore |= PatInfo.mayStore;
    InstInfo.mayLoad |= PatInfo.mayLoad;
  
    // These flags are silently added without any verification.
    InstInfo.isBitcast |= PatInfo.isBitcast;
  
    // Don't infer isVariadic. This flag means something different on SDNodes and
    // instructions. For example, a CALL SDNode is variadic because it has the
    // call arguments as operands, but a CALL instruction is not variadic - it
    // has argument registers as implicit, not explicit uses.
  
    return Error;
  }
  
  /// hasNullFragReference - Return true if the DAG has any reference to the
  /// null_frag operator.
  static bool hasNullFragReference(DagInit *DI) {
    DefInit *OpDef = dyn_cast<DefInit>(DI->getOperator());
    if (!OpDef) return false;
    Record *Operator = OpDef->getDef();
  
    // If this is the null fragment, return true.
    if (Operator->getName() == "null_frag") return true;
    // If any of the arguments reference the null fragment, return true.
    for (unsigned i = 0, e = DI->getNumArgs(); i != e; ++i) {
      DagInit *Arg = dyn_cast<DagInit>(DI->getArg(i));
      if (Arg && hasNullFragReference(Arg))
        return true;
    }
  
    return false;
  }
  
  /// hasNullFragReference - Return true if any DAG in the list references
  /// the null_frag operator.
  static bool hasNullFragReference(ListInit *LI) {
    for (Init *I : LI->getValues()) {
      DagInit *DI = dyn_cast<DagInit>(I);
      assert(DI && "non-dag in an instruction Pattern list?!");
      if (hasNullFragReference(DI))
        return true;
    }
    return false;
  }
  
  /// Get all the instructions in a tree.
  static void
  getInstructionsInTree(TreePatternNode *Tree, SmallVectorImpl<Record*> &Instrs) {
    if (Tree->isLeaf())
      return;
    if (Tree->getOperator()->isSubClassOf("Instruction"))
      Instrs.push_back(Tree->getOperator());
    for (unsigned i = 0, e = Tree->getNumChildren(); i != e; ++i)
      getInstructionsInTree(Tree->getChild(i), Instrs);
  }
  
  /// Check the class of a pattern leaf node against the instruction operand it
  /// represents.
  static bool checkOperandClass(CGIOperandList::OperandInfo &OI,
                                Record *Leaf) {
    if (OI.Rec == Leaf)
      return true;
  
    // Allow direct value types to be used in instruction set patterns.
    // The type will be checked later.
    if (Leaf->isSubClassOf("ValueType"))
      return true;
  
    // Patterns can also be ComplexPattern instances.
    if (Leaf->isSubClassOf("ComplexPattern"))
      return true;
  
    return false;
  }
  
  const DAGInstruction &CodeGenDAGPatterns::parseInstructionPattern(
      CodeGenInstruction &CGI, ListInit *Pat, DAGInstMap &DAGInsts) {
  
    assert(!DAGInsts.count(CGI.TheDef) && "Instruction already parsed!");
  
    // Parse the instruction.
    TreePattern *I = new TreePattern(CGI.TheDef, Pat, true, *this);
    // Inline pattern fragments into it.
    I->InlinePatternFragments();
  
    // Infer as many types as possible.  If we cannot infer all of them, we can
    // never do anything with this instruction pattern: report it to the user.
    if (!I->InferAllTypes())
      I->error("Could not infer all types in pattern!");
  
    // InstInputs - Keep track of all of the inputs of the instruction, along
    // with the record they are declared as.
    std::map<std::string, TreePatternNode*> InstInputs;
  
    // InstResults - Keep track of all the virtual registers that are 'set'
    // in the instruction, including what reg class they are.
    std::map<std::string, TreePatternNode*> InstResults;
  
    std::vector<Record*> InstImpResults;
  
    // Verify that the top-level forms in the instruction are of void type, and
    // fill in the InstResults map.
    SmallString<32> TypesString;
    for (unsigned j = 0, e = I->getNumTrees(); j != e; ++j) {
      TypesString.clear();
      TreePatternNode *Pat = I->getTree(j);
      if (Pat->getNumTypes() != 0) {
        raw_svector_ostream OS(TypesString);
        for (unsigned k = 0, ke = Pat->getNumTypes(); k != ke; ++k) {
          if (k > 0)
            OS << ", ";
          Pat->getExtType(k).writeToStream(OS);
        }
        I->error("Top-level forms in instruction pattern should have"
                 " void types, has types " +
                 OS.str());
      }
  
      // Find inputs and outputs, and verify the structure of the uses/defs.
      FindPatternInputsAndOutputs(I, Pat, InstInputs, InstResults,
                                  InstImpResults);
    }
  
    // Now that we have inputs and outputs of the pattern, inspect the operands
    // list for the instruction.  This determines the order that operands are
    // added to the machine instruction the node corresponds to.
    unsigned NumResults = InstResults.size();
  
    // Parse the operands list from the (ops) list, validating it.
    assert(I->getArgList().empty() && "Args list should still be empty here!");
  
    // Check that all of the results occur first in the list.
    std::vector<Record*> Results;
    SmallVector<TreePatternNode *, 2> ResNodes;
    for (unsigned i = 0; i != NumResults; ++i) {
      if (i == CGI.Operands.size())
        I->error("'" + InstResults.begin()->first +
                 "' set but does not appear in operand list!");
      const std::string &OpName = CGI.Operands[i].Name;
  
      // Check that it exists in InstResults.
      TreePatternNode *RNode = InstResults[OpName];
      if (!RNode)
        I->error("Operand $" + OpName + " does not exist in operand list!");
  
      ResNodes.push_back(RNode);
  
      Record *R = cast<DefInit>(RNode->getLeafValue())->getDef();
      if (!R)
        I->error("Operand $" + OpName + " should be a set destination: all "
                 "outputs must occur before inputs in operand list!");
  
      if (!checkOperandClass(CGI.Operands[i], R))
        I->error("Operand $" + OpName + " class mismatch!");
  
      // Remember the return type.
      Results.push_back(CGI.Operands[i].Rec);
  
      // Okay, this one checks out.
      InstResults.erase(OpName);
    }
  
    // Loop over the inputs next.  Make a copy of InstInputs so we can destroy
    // the copy while we're checking the inputs.
    std::map<std::string, TreePatternNode*> InstInputsCheck(InstInputs);
  
    std::vector<TreePatternNode*> ResultNodeOperands;
    std::vector<Record*> Operands;
    for (unsigned i = NumResults, e = CGI.Operands.size(); i != e; ++i) {
      CGIOperandList::OperandInfo &Op = CGI.Operands[i];
      const std::string &OpName = Op.Name;
      if (OpName.empty())
        I->error("Operand #" + Twine(i) + " in operands list has no name!");
  
      if (!InstInputsCheck.count(OpName)) {
        // If this is an operand with a DefaultOps set filled in, we can ignore
        // this.  When we codegen it, we will do so as always executed.
        if (Op.Rec->isSubClassOf("OperandWithDefaultOps")) {
          // Does it have a non-empty DefaultOps field?  If so, ignore this
          // operand.
          if (!getDefaultOperand(Op.Rec).DefaultOps.empty())
            continue;
        }
        I->error("Operand $" + OpName +
                 " does not appear in the instruction pattern");
      }
      TreePatternNode *InVal = InstInputsCheck[OpName];
      InstInputsCheck.erase(OpName);   // It occurred, remove from map.
  
      if (InVal->isLeaf() && isa<DefInit>(InVal->getLeafValue())) {
        Record *InRec = static_cast<DefInit*>(InVal->getLeafValue())->getDef();
        if (!checkOperandClass(Op, InRec))
          I->error("Operand $" + OpName + "'s register class disagrees"
                   " between the operand and pattern");
      }
      Operands.push_back(Op.Rec);
  
      // Construct the result for the dest-pattern operand list.
      TreePatternNode *OpNode = InVal->clone();
  
      // No predicate is useful on the result.
      OpNode->clearPredicateFns();
  
      // Promote the xform function to be an explicit node if set.
      if (Record *Xform = OpNode->getTransformFn()) {
        OpNode->setTransformFn(nullptr);
        std::vector<TreePatternNode*> Children;
        Children.push_back(OpNode);
        OpNode = new TreePatternNode(Xform, Children, OpNode->getNumTypes());
      }
  
      ResultNodeOperands.push_back(OpNode);
    }
  
    if (!InstInputsCheck.empty())
      I->error("Input operand $" + InstInputsCheck.begin()->first +
               " occurs in pattern but not in operands list!");
  
    TreePatternNode *ResultPattern =
      new TreePatternNode(I->getRecord(), ResultNodeOperands,
                          GetNumNodeResults(I->getRecord(), *this));
    // Copy fully inferred output node types to instruction result pattern.
    for (unsigned i = 0; i != NumResults; ++i) {
      assert(ResNodes[i]->getNumTypes() == 1 && "FIXME: Unhandled");
      ResultPattern->setType(i, ResNodes[i]->getExtType(0));
    }
  
    // Create and insert the instruction.
    // FIXME: InstImpResults should not be part of DAGInstruction.
    DAGInstruction TheInst(I, Results, Operands, InstImpResults);
    DAGInsts.insert(std::make_pair(I->getRecord(), TheInst));
  
    // Use a temporary tree pattern to infer all types and make sure that the
    // constructed result is correct.  This depends on the instruction already
    // being inserted into the DAGInsts map.
    TreePattern Temp(I->getRecord(), ResultPattern, false, *this);
    Temp.InferAllTypes(&I->getNamedNodesMap());
  
    DAGInstruction &TheInsertedInst = DAGInsts.find(I->getRecord())->second;
    TheInsertedInst.setResultPattern(Temp.getOnlyTree());
  
    return TheInsertedInst;
  }
  
  /// ParseInstructions - Parse all of the instructions, inlining and resolving
  /// any fragments involved.  This populates the Instructions list with fully
  /// resolved instructions.
  void CodeGenDAGPatterns::ParseInstructions() {
    std::vector<Record*> Instrs = Records.getAllDerivedDefinitions("Instruction");
  
    for (Record *Instr : Instrs) {
      ListInit *LI = nullptr;
  
      if (isa<ListInit>(Instr->getValueInit("Pattern")))
        LI = Instr->getValueAsListInit("Pattern");
  
      // If there is no pattern, only collect minimal information about the
      // instruction for its operand list.  We have to assume that there is one
      // result, as we have no detailed info. A pattern which references the
      // null_frag operator is as-if no pattern were specified. Normally this
      // is from a multiclass expansion w/ a SDPatternOperator passed in as
      // null_frag.
      if (!LI || LI->empty() || hasNullFragReference(LI)) {
        std::vector<Record*> Results;
        std::vector<Record*> Operands;
  
        CodeGenInstruction &InstInfo = Target.getInstruction(Instr);
  
        if (InstInfo.Operands.size() != 0) {
          for (unsigned j = 0, e = InstInfo.Operands.NumDefs; j < e; ++j)
            Results.push_back(InstInfo.Operands[j].Rec);
  
          // The rest are inputs.
          for (unsigned j = InstInfo.Operands.NumDefs,
                 e = InstInfo.Operands.size(); j < e; ++j)
            Operands.push_back(InstInfo.Operands[j].Rec);
        }
  
        // Create and insert the instruction.
        std::vector<Record*> ImpResults;
        Instructions.insert(std::make_pair(Instr,
                            DAGInstruction(nullptr, Results, Operands, ImpResults)));
        continue;  // no pattern.
      }
  
      CodeGenInstruction &CGI = Target.getInstruction(Instr);
      const DAGInstruction &DI = parseInstructionPattern(CGI, LI, Instructions);
  
      (void)DI;
      DEBUG(DI.getPattern()->dump());
    }
  
    // If we can, convert the instructions to be patterns that are matched!
    for (auto &Entry : Instructions) {
      DAGInstruction &TheInst = Entry.second;
      TreePattern *I = TheInst.getPattern();
      if (!I) continue;  // No pattern.
  
      if (PatternRewriter)
        PatternRewriter(I);
      // FIXME: Assume only the first tree is the pattern. The others are clobber
      // nodes.
      TreePatternNode *Pattern = I->getTree(0);
      TreePatternNode *SrcPattern;
      if (Pattern->getOperator()->getName() == "set") {
        SrcPattern = Pattern->getChild(Pattern->getNumChildren()-1)->clone();
      } else{
        // Not a set (store or something?)
        SrcPattern = Pattern;
      }
  
      Record *Instr = Entry.first;
      ListInit *Preds = Instr->getValueAsListInit("Predicates");
      int Complexity = Instr->getValueAsInt("AddedComplexity");
      AddPatternToMatch(
          I,
          PatternToMatch(Instr, makePredList(Preds), SrcPattern,
                         TheInst.getResultPattern(), TheInst.getImpResults(),
                         Complexity, Instr->getID()));
    }
  }
  
  
  typedef std::pair<const TreePatternNode*, unsigned> NameRecord;
  
  static void FindNames(const TreePatternNode *P,
                        std::map<std::string, NameRecord> &Names,
                        TreePattern *PatternTop) {
    if (!P->getName().empty()) {
      NameRecord &Rec = Names[P->getName()];
      // If this is the first instance of the name, remember the node.
      if (Rec.second++ == 0)
        Rec.first = P;
      else if (Rec.first->getExtTypes() != P->getExtTypes())
        PatternTop->error("repetition of value: $" + P->getName() +
                          " where different uses have different types!");
    }
  
    if (!P->isLeaf()) {
      for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
        FindNames(P->getChild(i), Names, PatternTop);
    }
  }
  
  std::vector<Predicate> CodeGenDAGPatterns::makePredList(ListInit *L) {
    std::vector<Predicate> Preds;
    for (Init *I : L->getValues()) {
      if (DefInit *Pred = dyn_cast<DefInit>(I))
        Preds.push_back(Pred->getDef());
      else
        llvm_unreachable("Non-def on the list");
    }
  
    // Sort so that different orders get canonicalized to the same string.
    llvm::sort(Preds.begin(), Preds.end());
    return Preds;
  }
  
  void CodeGenDAGPatterns::AddPatternToMatch(TreePattern *Pattern,
                                             PatternToMatch &&PTM) {
    // Do some sanity checking on the pattern we're about to match.
    std::string Reason;
    if (!PTM.getSrcPattern()->canPatternMatch(Reason, *this)) {
      PrintWarning(Pattern->getRecord()->getLoc(),
        Twine("Pattern can never match: ") + Reason);
      return;
    }
  
    // If the source pattern's root is a complex pattern, that complex pattern
    // must specify the nodes it can potentially match.
    if (const ComplexPattern *CP =
          PTM.getSrcPattern()->getComplexPatternInfo(*this))
      if (CP->getRootNodes().empty())
        Pattern->error("ComplexPattern at root must specify list of opcodes it"
                       " could match");
  
  
    // Find all of the named values in the input and output, ensure they have the
    // same type.
    std::map<std::string, NameRecord> SrcNames, DstNames;
    FindNames(PTM.getSrcPattern(), SrcNames, Pattern);
    FindNames(PTM.getDstPattern(), DstNames, Pattern);
  
    // Scan all of the named values in the destination pattern, rejecting them if
    // they don't exist in the input pattern.
    for (const auto &Entry : DstNames) {
      if (SrcNames[Entry.first].first == nullptr)
        Pattern->error("Pattern has input without matching name in output: $" +
                       Entry.first);
    }
  
    // Scan all of the named values in the source pattern, rejecting them if the
    // name isn't used in the dest, and isn't used to tie two values together.
    for (const auto &Entry : SrcNames)
      if (DstNames[Entry.first].first == nullptr &&
          SrcNames[Entry.first].second == 1)
        Pattern->error("Pattern has dead named input: $" + Entry.first);
  
    PatternsToMatch.push_back(std::move(PTM));
  }
  
  void CodeGenDAGPatterns::InferInstructionFlags() {
    ArrayRef<const CodeGenInstruction*> Instructions =
      Target.getInstructionsByEnumValue();
  
    // First try to infer flags from the primary instruction pattern, if any.
    SmallVector<CodeGenInstruction*, 8> Revisit;
    unsigned Errors = 0;
    for (unsigned i = 0, e = Instructions.size(); i != e; ++i) {
      CodeGenInstruction &InstInfo =
        const_cast<CodeGenInstruction &>(*Instructions[i]);
  
      // Get the primary instruction pattern.
      const TreePattern *Pattern = getInstruction(InstInfo.TheDef).getPattern();
      if (!Pattern) {
        if (InstInfo.hasUndefFlags())
          Revisit.push_back(&InstInfo);
        continue;
      }
      InstAnalyzer PatInfo(*this);
      PatInfo.Analyze(Pattern);
      Errors += InferFromPattern(InstInfo, PatInfo, InstInfo.TheDef);
    }
  
    // Second, look for single-instruction patterns defined outside the
    // instruction.
    for (const PatternToMatch &PTM : ptms()) {
      // We can only infer from single-instruction patterns, otherwise we won't
      // know which instruction should get the flags.
      SmallVector<Record*, 8> PatInstrs;
      getInstructionsInTree(PTM.getDstPattern(), PatInstrs);
      if (PatInstrs.size() != 1)
        continue;
  
      // Get the single instruction.
      CodeGenInstruction &InstInfo = Target.getInstruction(PatInstrs.front());
  
      // Only infer properties from the first pattern. We'll verify the others.
      if (InstInfo.InferredFrom)
        continue;
  
      InstAnalyzer PatInfo(*this);
      PatInfo.Analyze(PTM);
      Errors += InferFromPattern(InstInfo, PatInfo, PTM.getSrcRecord());
    }
  
    if (Errors)
      PrintFatalError("pattern conflicts");
  
    // Revisit instructions with undefined flags and no pattern.
    if (Target.guessInstructionProperties()) {
      for (CodeGenInstruction *InstInfo : Revisit) {
        if (InstInfo->InferredFrom)
          continue;
        // The mayLoad and mayStore flags default to false.
        // Conservatively assume hasSideEffects if it wasn't explicit.
        if (InstInfo->hasSideEffects_Unset)
          InstInfo->hasSideEffects = true;
      }
      return;
    }
  
    // Complain about any flags that are still undefined.
    for (CodeGenInstruction *InstInfo : Revisit) {
      if (InstInfo->InferredFrom)
        continue;
      if (InstInfo->hasSideEffects_Unset)
        PrintError(InstInfo->TheDef->getLoc(),
                   "Can't infer hasSideEffects from patterns");
      if (InstInfo->mayStore_Unset)
        PrintError(InstInfo->TheDef->getLoc(),
                   "Can't infer mayStore from patterns");
      if (InstInfo->mayLoad_Unset)
        PrintError(InstInfo->TheDef->getLoc(),
                   "Can't infer mayLoad from patterns");
    }
  }
  
  
  /// Verify instruction flags against pattern node properties.
  void CodeGenDAGPatterns::VerifyInstructionFlags() {
    unsigned Errors = 0;
    for (ptm_iterator I = ptm_begin(), E = ptm_end(); I != E; ++I) {
      const PatternToMatch &PTM = *I;
      SmallVector<Record*, 8> Instrs;
      getInstructionsInTree(PTM.getDstPattern(), Instrs);
      if (Instrs.empty())
        continue;
  
      // Count the number of instructions with each flag set.
      unsigned NumSideEffects = 0;
      unsigned NumStores = 0;
      unsigned NumLoads = 0;
      for (const Record *Instr : Instrs) {
        const CodeGenInstruction &InstInfo = Target.getInstruction(Instr);
        NumSideEffects += InstInfo.hasSideEffects;
        NumStores += InstInfo.mayStore;
        NumLoads += InstInfo.mayLoad;
      }
  
      // Analyze the source pattern.
      InstAnalyzer PatInfo(*this);
      PatInfo.Analyze(PTM);
  
      // Collect error messages.
      SmallVector<std::string, 4> Msgs;
  
      // Check for missing flags in the output.
      // Permit extra flags for now at least.
      if (PatInfo.hasSideEffects && !NumSideEffects)
        Msgs.push_back("pattern has side effects, but hasSideEffects isn't set");
  
      // Don't verify store flags on instructions with side effects. At least for
      // intrinsics, side effects implies mayStore.
      if (!PatInfo.hasSideEffects && PatInfo.mayStore && !NumStores)
        Msgs.push_back("pattern may store, but mayStore isn't set");
  
      // Similarly, mayStore implies mayLoad on intrinsics.
      if (!PatInfo.mayStore && PatInfo.mayLoad && !NumLoads)
        Msgs.push_back("pattern may load, but mayLoad isn't set");
  
      // Print error messages.
      if (Msgs.empty())
        continue;
      ++Errors;
  
      for (const std::string &Msg : Msgs)
        PrintError(PTM.getSrcRecord()->getLoc(), Twine(Msg) + " on the " +
                   (Instrs.size() == 1 ?
                    "instruction" : "output instructions"));
      // Provide the location of the relevant instruction definitions.
      for (const Record *Instr : Instrs) {
        if (Instr != PTM.getSrcRecord())
          PrintError(Instr->getLoc(), "defined here");
        const CodeGenInstruction &InstInfo = Target.getInstruction(Instr);
        if (InstInfo.InferredFrom &&
            InstInfo.InferredFrom != InstInfo.TheDef &&
            InstInfo.InferredFrom != PTM.getSrcRecord())
          PrintError(InstInfo.InferredFrom->getLoc(), "inferred from pattern");
      }
    }
    if (Errors)
      PrintFatalError("Errors in DAG patterns");
  }
  
  /// Given a pattern result with an unresolved type, see if we can find one
  /// instruction with an unresolved result type.  Force this result type to an
  /// arbitrary element if it's possible types to converge results.
  static bool ForceArbitraryInstResultType(TreePatternNode *N, TreePattern &TP) {
    if (N->isLeaf())
      return false;
  
    // Analyze children.
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
      if (ForceArbitraryInstResultType(N->getChild(i), TP))
        return true;
  
    if (!N->getOperator()->isSubClassOf("Instruction"))
      return false;
  
    // If this type is already concrete or completely unknown we can't do
    // anything.
    TypeInfer &TI = TP.getInfer();
    for (unsigned i = 0, e = N->getNumTypes(); i != e; ++i) {
      if (N->getExtType(i).empty() || TI.isConcrete(N->getExtType(i), false))
        continue;
  
      // Otherwise, force its type to an arbitrary choice.
      if (TI.forceArbitrary(N->getExtType(i)))
        return true;
    }
  
    return false;
  }
  
  void CodeGenDAGPatterns::ParsePatterns() {
    std::vector<Record*> Patterns = Records.getAllDerivedDefinitions("Pattern");
  
    for (Record *CurPattern : Patterns) {
      DagInit *Tree = CurPattern->getValueAsDag("PatternToMatch");
  
      // If the pattern references the null_frag, there's nothing to do.
      if (hasNullFragReference(Tree))
        continue;
  
      TreePattern *Pattern = new TreePattern(CurPattern, Tree, true, *this);
  
      // Inline pattern fragments into it.
      Pattern->InlinePatternFragments();
  
      ListInit *LI = CurPattern->getValueAsListInit("ResultInstrs");
      if (LI->empty()) continue;  // no pattern.
  
      // Parse the instruction.
      TreePattern Result(CurPattern, LI, false, *this);
  
      // Inline pattern fragments into it.
      Result.InlinePatternFragments();
  
      if (Result.getNumTrees() != 1)
        Result.error("Cannot handle instructions producing instructions "
                     "with temporaries yet!");
  
      bool IterateInference;
      bool InferredAllPatternTypes, InferredAllResultTypes;
      do {
        // Infer as many types as possible.  If we cannot infer all of them, we
        // can never do anything with this pattern: report it to the user.
        InferredAllPatternTypes =
          Pattern->InferAllTypes(&Pattern->getNamedNodesMap());
  
        // Infer as many types as possible.  If we cannot infer all of them, we
        // can never do anything with this pattern: report it to the user.
        InferredAllResultTypes =
            Result.InferAllTypes(&Pattern->getNamedNodesMap());
  
        IterateInference = false;
  
        // Apply the type of the result to the source pattern.  This helps us
        // resolve cases where the input type is known to be a pointer type (which
        // is considered resolved), but the result knows it needs to be 32- or
        // 64-bits.  Infer the other way for good measure.
        for (unsigned i = 0, e = std::min(Result.getTree(0)->getNumTypes(),
                                          Pattern->getTree(0)->getNumTypes());
             i != e; ++i) {
          IterateInference = Pattern->getTree(0)->UpdateNodeType(
              i, Result.getTree(0)->getExtType(i), Result);
          IterateInference |= Result.getTree(0)->UpdateNodeType(
              i, Pattern->getTree(0)->getExtType(i), Result);
        }
  
        // If our iteration has converged and the input pattern's types are fully
        // resolved but the result pattern is not fully resolved, we may have a
        // situation where we have two instructions in the result pattern and
        // the instructions require a common register class, but don't care about
        // what actual MVT is used.  This is actually a bug in our modelling:
        // output patterns should have register classes, not MVTs.
        //
        // In any case, to handle this, we just go through and disambiguate some
        // arbitrary types to the result pattern's nodes.
        if (!IterateInference && InferredAllPatternTypes &&
            !InferredAllResultTypes)
          IterateInference =
              ForceArbitraryInstResultType(Result.getTree(0), Result);
      } while (IterateInference);
  
      // Verify that we inferred enough types that we can do something with the
      // pattern and result.  If these fire the user has to add type casts.
      if (!InferredAllPatternTypes)
        Pattern->error("Could not infer all types in pattern!");
      if (!InferredAllResultTypes) {
        Pattern->dump();
        Result.error("Could not infer all types in pattern result!");
      }
  
      // Validate that the input pattern is correct.
      std::map<std::string, TreePatternNode*> InstInputs;
      std::map<std::string, TreePatternNode*> InstResults;
      std::vector<Record*> InstImpResults;
      for (unsigned j = 0, ee = Pattern->getNumTrees(); j != ee; ++j)
        FindPatternInputsAndOutputs(Pattern, Pattern->getTree(j),
                                    InstInputs, InstResults,
                                    InstImpResults);
  
      // Promote the xform function to be an explicit node if set.
      TreePatternNode *DstPattern = Result.getOnlyTree();
      std::vector<TreePatternNode*> ResultNodeOperands;
      for (unsigned ii = 0, ee = DstPattern->getNumChildren(); ii != ee; ++ii) {
        TreePatternNode *OpNode = DstPattern->getChild(ii);
        if (Record *Xform = OpNode->getTransformFn()) {
          OpNode->setTransformFn(nullptr);
          std::vector<TreePatternNode*> Children;
          Children.push_back(OpNode);
          OpNode = new TreePatternNode(Xform, Children, OpNode->getNumTypes());
        }
        ResultNodeOperands.push_back(OpNode);
      }
      DstPattern = Result.getOnlyTree();
      if (!DstPattern->isLeaf())
        DstPattern = new TreePatternNode(DstPattern->getOperator(),
                                         ResultNodeOperands,
                                         DstPattern->getNumTypes());
  
      for (unsigned i = 0, e = Result.getOnlyTree()->getNumTypes(); i != e; ++i)
        DstPattern->setType(i, Result.getOnlyTree()->getExtType(i));
  
      TreePattern Temp(Result.getRecord(), DstPattern, false, *this);
      Temp.InferAllTypes();
  
      // A pattern may end up with an "impossible" type, i.e. a situation
      // where all types have been eliminated for some node in this pattern.
      // This could occur for intrinsics that only make sense for a specific
      // value type, and use a specific register class. If, for some mode,
      // that register class does not accept that type, the type inference
      // will lead to a contradiction, which is not an error however, but
      // a sign that this pattern will simply never match.
      if (Pattern->getTree(0)->hasPossibleType() &&
          Temp.getOnlyTree()->hasPossibleType()) {
        ListInit *Preds = CurPattern->getValueAsListInit("Predicates");
        int Complexity = CurPattern->getValueAsInt("AddedComplexity");
        if (PatternRewriter)
          PatternRewriter(Pattern);
        AddPatternToMatch(
            Pattern,
            PatternToMatch(
                CurPattern, makePredList(Preds), Pattern->getTree(0),
                Temp.getOnlyTree(), std::move(InstImpResults), Complexity,
                CurPattern->getID()));
      }
    }
  }
  
  static void collectModes(std::set<unsigned> &Modes, const TreePatternNode *N) {
    for (const TypeSetByHwMode &VTS : N->getExtTypes())
      for (const auto &I : VTS)
        Modes.insert(I.first);
  
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
      collectModes(Modes, N->getChild(i));
  }
  
  void CodeGenDAGPatterns::ExpandHwModeBasedTypes() {
    const CodeGenHwModes &CGH = getTargetInfo().getHwModes();
    std::map<unsigned,std::vector<Predicate>> ModeChecks;
    std::vector<PatternToMatch> Copy = PatternsToMatch;
    PatternsToMatch.clear();
  
    auto AppendPattern = [this,&ModeChecks](PatternToMatch &P, unsigned Mode) {
      TreePatternNode *NewSrc = P.SrcPattern->clone();
      TreePatternNode *NewDst = P.DstPattern->clone();
      if (!NewSrc->setDefaultMode(Mode) || !NewDst->setDefaultMode(Mode)) {
        delete NewSrc;
        delete NewDst;
        return;
      }
  
      std::vector<Predicate> Preds = P.Predicates;
      const std::vector<Predicate> &MC = ModeChecks[Mode];
      Preds.insert(Preds.end(), MC.begin(), MC.end());
      PatternsToMatch.emplace_back(P.getSrcRecord(), Preds, NewSrc, NewDst,
                                   P.getDstRegs(), P.getAddedComplexity(),
                                   Record::getNewUID(), Mode);
    };
  
    for (PatternToMatch &P : Copy) {
      TreePatternNode *SrcP = nullptr, *DstP = nullptr;
      if (P.SrcPattern->hasProperTypeByHwMode())
        SrcP = P.SrcPattern;
      if (P.DstPattern->hasProperTypeByHwMode())
        DstP = P.DstPattern;
      if (!SrcP && !DstP) {
        PatternsToMatch.push_back(P);
        continue;
      }
  
      std::set<unsigned> Modes;
      if (SrcP)
        collectModes(Modes, SrcP);
      if (DstP)
        collectModes(Modes, DstP);
  
      // The predicate for the default mode needs to be constructed for each
      // pattern separately.
      // Since not all modes must be present in each pattern, if a mode m is
      // absent, then there is no point in constructing a check for m. If such
      // a check was created, it would be equivalent to checking the default
      // mode, except not all modes' predicates would be a part of the checking
      // code. The subsequently generated check for the default mode would then
      // have the exact same patterns, but a different predicate code. To avoid
      // duplicated patterns with different predicate checks, construct the
      // default check as a negation of all predicates that are actually present
      // in the source/destination patterns.
      std::vector<Predicate> DefaultPred;
  
      for (unsigned M : Modes) {
        if (M == DefaultMode)
          continue;
        if (ModeChecks.find(M) != ModeChecks.end())
          continue;
  
        // Fill the map entry for this mode.
        const HwMode &HM = CGH.getMode(M);
        ModeChecks[M].emplace_back(Predicate(HM.Features, true));
  
        // Add negations of the HM's predicates to the default predicate.
        DefaultPred.emplace_back(Predicate(HM.Features, false));
      }
  
      for (unsigned M : Modes) {
        if (M == DefaultMode)
          continue;
        AppendPattern(P, M);
      }
  
      bool HasDefault = Modes.count(DefaultMode);
      if (HasDefault)
        AppendPattern(P, DefaultMode);
    }
  }
  
  /// Dependent variable map for CodeGenDAGPattern variant generation
  typedef StringMap<int> DepVarMap;
  
  static void FindDepVarsOf(TreePatternNode *N, DepVarMap &DepMap) {
    if (N->isLeaf()) {
      if (N->hasName() && isa<DefInit>(N->getLeafValue()))
        DepMap[N->getName()]++;
    } else {
      for (size_t i = 0, e = N->getNumChildren(); i != e; ++i)
        FindDepVarsOf(N->getChild(i), DepMap);
    }
  }
  
  /// Find dependent variables within child patterns
  static void FindDepVars(TreePatternNode *N, MultipleUseVarSet &DepVars) {
    DepVarMap depcounts;
    FindDepVarsOf(N, depcounts);
    for (const auto &Pair : depcounts) {
      if (Pair.getValue() > 1)
        DepVars.insert(Pair.getKey());
    }
  }
  
  #ifndef NDEBUG
  /// Dump the dependent variable set:
  static void DumpDepVars(MultipleUseVarSet &DepVars) {
    if (DepVars.empty()) {
      DEBUG(errs() << "<empty set>");
    } else {
      DEBUG(errs() << "[ ");
      for (const auto &DepVar : DepVars) {
        DEBUG(errs() << DepVar.getKey() << " ");
      }
      DEBUG(errs() << "]");
    }
  }
  #endif
  
  
  /// CombineChildVariants - Given a bunch of permutations of each child of the
  /// 'operator' node, put them together in all possible ways.
  static void CombineChildVariants(TreePatternNode *Orig,
                 const std::vector<std::vector<TreePatternNode*> > &ChildVariants,
                                   std::vector<TreePatternNode*> &OutVariants,
                                   CodeGenDAGPatterns &CDP,
                                   const MultipleUseVarSet &DepVars) {
    // Make sure that each operand has at least one variant to choose from.
    for (const auto &Variants : ChildVariants)
      if (Variants.empty())
        return;
  
    // The end result is an all-pairs construction of the resultant pattern.
    std::vector<unsigned> Idxs;
    Idxs.resize(ChildVariants.size());
    bool NotDone;
    do {
  #ifndef NDEBUG
      DEBUG(if (!Idxs.empty()) {
              errs() << Orig->getOperator()->getName() << ": Idxs = [ ";
                for (unsigned Idx : Idxs) {
                  errs() << Idx << " ";
              }
              errs() << "]\n";
            });
  #endif
      // Create the variant and add it to the output list.
      std::vector<TreePatternNode*> NewChildren;
      for (unsigned i = 0, e = ChildVariants.size(); i != e; ++i)
        NewChildren.push_back(ChildVariants[i][Idxs[i]]);
      auto R = llvm::make_unique<TreePatternNode>(
          Orig->getOperator(), NewChildren, Orig->getNumTypes());
  
      // Copy over properties.
      R->setName(Orig->getName());
      R->setPredicateFns(Orig->getPredicateFns());
      R->setTransformFn(Orig->getTransformFn());
      for (unsigned i = 0, e = Orig->getNumTypes(); i != e; ++i)
        R->setType(i, Orig->getExtType(i));
  
      // If this pattern cannot match, do not include it as a variant.
      std::string ErrString;
      // Scan to see if this pattern has already been emitted.  We can get
      // duplication due to things like commuting:
      //   (and GPRC:$a, GPRC:$b) -> (and GPRC:$b, GPRC:$a)
      // which are the same pattern.  Ignore the dups.
      if (R->canPatternMatch(ErrString, CDP) &&
          none_of(OutVariants, [&](TreePatternNode *Variant) {
            return R->isIsomorphicTo(Variant, DepVars);
          }))
        OutVariants.push_back(R.release());
  
      // Increment indices to the next permutation by incrementing the
      // indices from last index backward, e.g., generate the sequence
      // [0, 0], [0, 1], [1, 0], [1, 1].
      int IdxsIdx;
      for (IdxsIdx = Idxs.size() - 1; IdxsIdx >= 0; --IdxsIdx) {
        if (++Idxs[IdxsIdx] == ChildVariants[IdxsIdx].size())
          Idxs[IdxsIdx] = 0;
        else
          break;
      }
      NotDone = (IdxsIdx >= 0);
    } while (NotDone);
  }
  
  /// CombineChildVariants - A helper function for binary operators.
  ///
  static void CombineChildVariants(TreePatternNode *Orig,
                                   const std::vector<TreePatternNode*> &LHS,
                                   const std::vector<TreePatternNode*> &RHS,
                                   std::vector<TreePatternNode*> &OutVariants,
                                   CodeGenDAGPatterns &CDP,
                                   const MultipleUseVarSet &DepVars) {
    std::vector<std::vector<TreePatternNode*> > ChildVariants;
    ChildVariants.push_back(LHS);
    ChildVariants.push_back(RHS);
    CombineChildVariants(Orig, ChildVariants, OutVariants, CDP, DepVars);
  }
  
  
  static void GatherChildrenOfAssociativeOpcode(TreePatternNode *N,
                                       std::vector<TreePatternNode *> &Children) {
    assert(N->getNumChildren()==2 &&"Associative but doesn't have 2 children!");
    Record *Operator = N->getOperator();
  
    // Only permit raw nodes.
    if (!N->getName().empty() || !N->getPredicateFns().empty() ||
        N->getTransformFn()) {
      Children.push_back(N);
      return;
    }
  
    if (N->getChild(0)->isLeaf() || N->getChild(0)->getOperator() != Operator)
      Children.push_back(N->getChild(0));
    else
      GatherChildrenOfAssociativeOpcode(N->getChild(0), Children);
  
    if (N->getChild(1)->isLeaf() || N->getChild(1)->getOperator() != Operator)
      Children.push_back(N->getChild(1));
    else
      GatherChildrenOfAssociativeOpcode(N->getChild(1), Children);
  }
  
  /// GenerateVariantsOf - Given a pattern N, generate all permutations we can of
  /// the (potentially recursive) pattern by using algebraic laws.
  ///
  static void GenerateVariantsOf(TreePatternNode *N,
                                 std::vector<TreePatternNode*> &OutVariants,
                                 CodeGenDAGPatterns &CDP,
                                 const MultipleUseVarSet &DepVars) {
    // We cannot permute leaves or ComplexPattern uses.
    if (N->isLeaf() || N->getOperator()->isSubClassOf("ComplexPattern")) {
      OutVariants.push_back(N);
      return;
    }
  
    // Look up interesting info about the node.
    const SDNodeInfo &NodeInfo = CDP.getSDNodeInfo(N->getOperator());
  
    // If this node is associative, re-associate.
    if (NodeInfo.hasProperty(SDNPAssociative)) {
      // Re-associate by pulling together all of the linked operators
      std::vector<TreePatternNode*> MaximalChildren;
      GatherChildrenOfAssociativeOpcode(N, MaximalChildren);
  
      // Only handle child sizes of 3.  Otherwise we'll end up trying too many
      // permutations.
      if (MaximalChildren.size() == 3) {
        // Find the variants of all of our maximal children.
        std::vector<TreePatternNode*> AVariants, BVariants, CVariants;
        GenerateVariantsOf(MaximalChildren[0], AVariants, CDP, DepVars);
        GenerateVariantsOf(MaximalChildren[1], BVariants, CDP, DepVars);
        GenerateVariantsOf(MaximalChildren[2], CVariants, CDP, DepVars);
  
        // There are only two ways we can permute the tree:
        //   (A op B) op C    and    A op (B op C)
        // Within these forms, we can also permute A/B/C.
  
        // Generate legal pair permutations of A/B/C.
        std::vector<TreePatternNode*> ABVariants;
        std::vector<TreePatternNode*> BAVariants;
        std::vector<TreePatternNode*> ACVariants;
        std::vector<TreePatternNode*> CAVariants;
        std::vector<TreePatternNode*> BCVariants;
        std::vector<TreePatternNode*> CBVariants;
        CombineChildVariants(N, AVariants, BVariants, ABVariants, CDP, DepVars);
        CombineChildVariants(N, BVariants, AVariants, BAVariants, CDP, DepVars);
        CombineChildVariants(N, AVariants, CVariants, ACVariants, CDP, DepVars);
        CombineChildVariants(N, CVariants, AVariants, CAVariants, CDP, DepVars);
        CombineChildVariants(N, BVariants, CVariants, BCVariants, CDP, DepVars);
        CombineChildVariants(N, CVariants, BVariants, CBVariants, CDP, DepVars);
  
        // Combine those into the result: (x op x) op x
        CombineChildVariants(N, ABVariants, CVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, BAVariants, CVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, ACVariants, BVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, CAVariants, BVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, BCVariants, AVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, CBVariants, AVariants, OutVariants, CDP, DepVars);
  
        // Combine those into the result: x op (x op x)
        CombineChildVariants(N, CVariants, ABVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, CVariants, BAVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, BVariants, ACVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, BVariants, CAVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, AVariants, BCVariants, OutVariants, CDP, DepVars);
        CombineChildVariants(N, AVariants, CBVariants, OutVariants, CDP, DepVars);
        return;
      }
    }
  
    // Compute permutations of all children.
    std::vector<std::vector<TreePatternNode*> > ChildVariants;
    ChildVariants.resize(N->getNumChildren());
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
      GenerateVariantsOf(N->getChild(i), ChildVariants[i], CDP, DepVars);
  
    // Build all permutations based on how the children were formed.
    CombineChildVariants(N, ChildVariants, OutVariants, CDP, DepVars);
  
    // If this node is commutative, consider the commuted order.
    bool isCommIntrinsic = N->isCommutativeIntrinsic(CDP);
    if (NodeInfo.hasProperty(SDNPCommutative) || isCommIntrinsic) {
      assert((N->getNumChildren()>=2 || isCommIntrinsic) &&
             "Commutative but doesn't have 2 children!");
      // Don't count children which are actually register references.
      unsigned NC = 0;
      for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
        TreePatternNode *Child = N->getChild(i);
        if (Child->isLeaf())
          if (DefInit *DI = dyn_cast<DefInit>(Child->getLeafValue())) {
            Record *RR = DI->getDef();
            if (RR->isSubClassOf("Register"))
              continue;
          }
        NC++;
      }
      // Consider the commuted order.
      if (isCommIntrinsic) {
        // Commutative intrinsic. First operand is the intrinsic id, 2nd and 3rd
        // operands are the commutative operands, and there might be more operands
        // after those.
        assert(NC >= 3 &&
               "Commutative intrinsic should have at least 3 children!");
        std::vector<std::vector<TreePatternNode*> > Variants;
        Variants.push_back(ChildVariants[0]); // Intrinsic id.
        Variants.push_back(ChildVariants[2]);
        Variants.push_back(ChildVariants[1]);
        for (unsigned i = 3; i != NC; ++i)
          Variants.push_back(ChildVariants[i]);
        CombineChildVariants(N, Variants, OutVariants, CDP, DepVars);
      } else if (NC == N->getNumChildren()) {
        std::vector<std::vector<TreePatternNode*> > Variants;
        Variants.push_back(ChildVariants[1]);
        Variants.push_back(ChildVariants[0]);
        for (unsigned i = 2; i != NC; ++i)
          Variants.push_back(ChildVariants[i]);
        CombineChildVariants(N, Variants, OutVariants, CDP, DepVars);
      }
    }
  }
  
  
  // GenerateVariants - Generate variants.  For example, commutative patterns can
  // match multiple ways.  Add them to PatternsToMatch as well.
  void CodeGenDAGPatterns::GenerateVariants() {
    DEBUG(errs() << "Generating instruction variants.\n");
  
    // Loop over all of the patterns we've collected, checking to see if we can
    // generate variants of the instruction, through the exploitation of
    // identities.  This permits the target to provide aggressive matching without
    // the .td file having to contain tons of variants of instructions.
    //
    // Note that this loop adds new patterns to the PatternsToMatch list, but we
    // intentionally do not reconsider these.  Any variants of added patterns have
    // already been added.
    //
    for (unsigned i = 0, e = PatternsToMatch.size(); i != e; ++i) {
      MultipleUseVarSet             DepVars;
      std::vector<TreePatternNode*> Variants;
      FindDepVars(PatternsToMatch[i].getSrcPattern(), DepVars);
      DEBUG(errs() << "Dependent/multiply used variables: ");
      DEBUG(DumpDepVars(DepVars));
      DEBUG(errs() << "\n");
      GenerateVariantsOf(PatternsToMatch[i].getSrcPattern(), Variants, *this,
                         DepVars);
  
      assert(!Variants.empty() && "Must create at least original variant!");
      if (Variants.size() == 1)  // No additional variants for this pattern.
        continue;
  
      DEBUG(errs() << "FOUND VARIANTS OF: ";
            PatternsToMatch[i].getSrcPattern()->dump();
            errs() << "\n");
  
      for (unsigned v = 0, e = Variants.size(); v != e; ++v) {
        TreePatternNode *Variant = Variants[v];
  
        DEBUG(errs() << "  VAR#" << v <<  ": ";
              Variant->dump();
              errs() << "\n");
  
        // Scan to see if an instruction or explicit pattern already matches this.
        bool AlreadyExists = false;
        for (unsigned p = 0, e = PatternsToMatch.size(); p != e; ++p) {
          // Skip if the top level predicates do not match.
          if (PatternsToMatch[i].getPredicates() !=
              PatternsToMatch[p].getPredicates())
            continue;
          // Check to see if this variant already exists.
          if (Variant->isIsomorphicTo(PatternsToMatch[p].getSrcPattern(),
                                      DepVars)) {
            DEBUG(errs() << "  *** ALREADY EXISTS, ignoring variant.\n");
            AlreadyExists = true;
            break;
          }
        }
        // If we already have it, ignore the variant.
        if (AlreadyExists) continue;
  
        // Otherwise, add it to the list of patterns we have.
        PatternsToMatch.push_back(PatternToMatch(
            PatternsToMatch[i].getSrcRecord(), PatternsToMatch[i].getPredicates(),
            Variant, PatternsToMatch[i].getDstPattern(),
            PatternsToMatch[i].getDstRegs(),
            PatternsToMatch[i].getAddedComplexity(), Record::getNewUID()));
      }
  
      DEBUG(errs() << "\n");
    }
  }
  