xref: /external/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

//===-- DAGCombiner.cpp - Implement a DAG node combiner -------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass combines dag nodes to form fewer, simpler DAG nodes.  It can be run
// both before and after the DAG is legalized.
//
// This pass is not a substitute for the LLVM IR instcombine pass. This pass is
// primarily intended to handle simplification opportunities that are implicit
// in the LLVM IR and exposed by the various codegen lowering phases.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <algorithm>
using namespace llvm;

#define DEBUG_TYPE "dagcombine"

STATISTIC(NodesCombined   , "Number of dag nodes combined");
STATISTIC(PreIndexedNodes , "Number of pre-indexed nodes created");
STATISTIC(PostIndexedNodes, "Number of post-indexed nodes created");
STATISTIC(OpsNarrowed     , "Number of load/op/store narrowed");
STATISTIC(LdStFP2Int      , "Number of fp load/store pairs transformed to int");
STATISTIC(SlicedLoads, "Number of load sliced");

namespace {
  static cl::opt<bool>
    CombinerAA("combiner-alias-analysis", cl::Hidden,
               cl::desc("Enable DAG combiner alias-analysis heuristics"));

  static cl::opt<bool>
    CombinerGlobalAA("combiner-global-alias-analysis", cl::Hidden,
               cl::desc("Enable DAG combiner's use of IR alias analysis"));

  static cl::opt<bool>
    UseTBAA("combiner-use-tbaa", cl::Hidden, cl::init(true),
               cl::desc("Enable DAG combiner's use of TBAA"));

#ifndef NDEBUG
  static cl::opt<std::string>
    CombinerAAOnlyFunc("combiner-aa-only-func", cl::Hidden,
               cl::desc("Only use DAG-combiner alias analysis in this"
                        " function"));
#endif

  /// Hidden option to stress test load slicing, i.e., when this option
  /// is enabled, load slicing bypasses most of its profitability guards.
  static cl::opt<bool>
  StressLoadSlicing("combiner-stress-load-slicing", cl::Hidden,
                    cl::desc("Bypass the profitability model of load "
                             "slicing"),
                    cl::init(false));

  static cl::opt<bool>
    MaySplitLoadIndex("combiner-split-load-index", cl::Hidden, cl::init(true),
                      cl::desc("DAG combiner may split indexing from loads"));

//------------------------------ DAGCombiner ---------------------------------//

  class DAGCombiner {
    SelectionDAG &DAG;
    const TargetLowering &TLI;
    CombineLevel Level;
    CodeGenOpt::Level OptLevel;
    bool LegalOperations;
    bool LegalTypes;
    bool ForCodeSize;

    /// \brief Worklist of all of the nodes that need to be simplified.
    ///
    /// This must behave as a stack -- new nodes to process are pushed onto the
    /// back and when processing we pop off of the back.
    ///
    /// The worklist will not contain duplicates but may contain null entries
    /// due to nodes being deleted from the underlying DAG.
    SmallVector<SDNode *, 64> Worklist;

    /// \brief Mapping from an SDNode to its position on the worklist.
    ///
    /// This is used to find and remove nodes from the worklist (by nulling
    /// them) when they are deleted from the underlying DAG. It relies on
    /// stable indices of nodes within the worklist.
    DenseMap<SDNode *, unsigned> WorklistMap;

    /// \brief Set of nodes which have been combined (at least once).
    ///
    /// This is used to allow us to reliably add any operands of a DAG node
    /// which have not yet been combined to the worklist.
    SmallPtrSet<SDNode *, 64> CombinedNodes;

    // AA - Used for DAG load/store alias analysis.
    AliasAnalysis &AA;

    /// When an instruction is simplified, add all users of the instruction to
    /// the work lists because they might get more simplified now.
    void AddUsersToWorklist(SDNode *N) {
      for (SDNode *Node : N->uses())
        AddToWorklist(Node);
    }

    /// Call the node-specific routine that folds each particular type of node.
    SDValue visit(SDNode *N);

  public:
    /// Add to the worklist making sure its instance is at the back (next to be
    /// processed.)
    void AddToWorklist(SDNode *N) {
      // Skip handle nodes as they can't usefully be combined and confuse the
      // zero-use deletion strategy.
      if (N->getOpcode() == ISD::HANDLENODE)
        return;

      if (WorklistMap.insert(std::make_pair(N, Worklist.size())).second)
        Worklist.push_back(N);
    }

    /// Remove all instances of N from the worklist.
    void removeFromWorklist(SDNode *N) {
      CombinedNodes.erase(N);

      auto It = WorklistMap.find(N);
      if (It == WorklistMap.end())
        return; // Not in the worklist.

      // Null out the entry rather than erasing it to avoid a linear operation.
      Worklist[It->second] = nullptr;
      WorklistMap.erase(It);
    }

    void deleteAndRecombine(SDNode *N);
    bool recursivelyDeleteUnusedNodes(SDNode *N);

    /// Replaces all uses of the results of one DAG node with new values.
    SDValue CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
                      bool AddTo = true);

    /// Replaces all uses of the results of one DAG node with new values.
    SDValue CombineTo(SDNode *N, SDValue Res, bool AddTo = true) {
      return CombineTo(N, &Res, 1, AddTo);
    }

    /// Replaces all uses of the results of one DAG node with new values.
    SDValue CombineTo(SDNode *N, SDValue Res0, SDValue Res1,
                      bool AddTo = true) {
      SDValue To[] = { Res0, Res1 };
      return CombineTo(N, To, 2, AddTo);
    }

    void CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO);

  private:

    /// Check the specified integer node value to see if it can be simplified or
    /// if things it uses can be simplified by bit propagation.
    /// If so, return true.
    bool SimplifyDemandedBits(SDValue Op) {
      unsigned BitWidth = Op.getValueType().getScalarType().getSizeInBits();
      APInt Demanded = APInt::getAllOnesValue(BitWidth);
      return SimplifyDemandedBits(Op, Demanded);
    }

    bool SimplifyDemandedBits(SDValue Op, const APInt &Demanded);

    bool CombineToPreIndexedLoadStore(SDNode *N);
    bool CombineToPostIndexedLoadStore(SDNode *N);
    SDValue SplitIndexingFromLoad(LoadSDNode *LD);
    bool SliceUpLoad(SDNode *N);

    /// \brief Replace an ISD::EXTRACT_VECTOR_ELT of a load with a narrowed
    ///   load.
    ///
    /// \param EVE ISD::EXTRACT_VECTOR_ELT to be replaced.
    /// \param InVecVT type of the input vector to EVE with bitcasts resolved.
    /// \param EltNo index of the vector element to load.
    /// \param OriginalLoad load that EVE came from to be replaced.
    /// \returns EVE on success SDValue() on failure.
    SDValue ReplaceExtractVectorEltOfLoadWithNarrowedLoad(
        SDNode *EVE, EVT InVecVT, SDValue EltNo, LoadSDNode *OriginalLoad);
    void ReplaceLoadWithPromotedLoad(SDNode *Load, SDNode *ExtLoad);
    SDValue PromoteOperand(SDValue Op, EVT PVT, bool &Replace);
    SDValue SExtPromoteOperand(SDValue Op, EVT PVT);
    SDValue ZExtPromoteOperand(SDValue Op, EVT PVT);
    SDValue PromoteIntBinOp(SDValue Op);
    SDValue PromoteIntShiftOp(SDValue Op);
    SDValue PromoteExtend(SDValue Op);
    bool PromoteLoad(SDValue Op);

    void ExtendSetCCUses(const SmallVectorImpl<SDNode *> &SetCCs,
                         SDValue Trunc, SDValue ExtLoad, SDLoc DL,
                         ISD::NodeType ExtType);

    /// Call the node-specific routine that knows how to fold each
    /// particular type of node. If that doesn't do anything, try the
    /// target-specific DAG combines.
    SDValue combine(SDNode *N);

    // Visitation implementation - Implement dag node combining for different
    // node types.  The semantics are as follows:
    // Return Value:
    //   SDValue.getNode() == 0 - No change was made
    //   SDValue.getNode() == N - N was replaced, is dead and has been handled.
    //   otherwise              - N should be replaced by the returned Operand.
    //
    SDValue visitTokenFactor(SDNode *N);
    SDValue visitMERGE_VALUES(SDNode *N);
    SDValue visitADD(SDNode *N);
    SDValue visitSUB(SDNode *N);
    SDValue visitADDC(SDNode *N);
    SDValue visitSUBC(SDNode *N);
    SDValue visitADDE(SDNode *N);
    SDValue visitSUBE(SDNode *N);
    SDValue visitMUL(SDNode *N);
    SDValue useDivRem(SDNode *N);
    SDValue visitSDIV(SDNode *N);
    SDValue visitUDIV(SDNode *N);
    SDValue visitREM(SDNode *N);
    SDValue visitMULHU(SDNode *N);
    SDValue visitMULHS(SDNode *N);
    SDValue visitSMUL_LOHI(SDNode *N);
    SDValue visitUMUL_LOHI(SDNode *N);
    SDValue visitSMULO(SDNode *N);
    SDValue visitUMULO(SDNode *N);
    SDValue visitIMINMAX(SDNode *N);
    SDValue visitAND(SDNode *N);
    SDValue visitANDLike(SDValue N0, SDValue N1, SDNode *LocReference);
    SDValue visitOR(SDNode *N);
    SDValue visitORLike(SDValue N0, SDValue N1, SDNode *LocReference);
    SDValue visitXOR(SDNode *N);
    SDValue SimplifyVBinOp(SDNode *N);
    SDValue visitSHL(SDNode *N);
    SDValue visitSRA(SDNode *N);
    SDValue visitSRL(SDNode *N);
    SDValue visitRotate(SDNode *N);
    SDValue visitBSWAP(SDNode *N);
    SDValue visitCTLZ(SDNode *N);
    SDValue visitCTLZ_ZERO_UNDEF(SDNode *N);
    SDValue visitCTTZ(SDNode *N);
    SDValue visitCTTZ_ZERO_UNDEF(SDNode *N);
    SDValue visitCTPOP(SDNode *N);
    SDValue visitSELECT(SDNode *N);
    SDValue visitVSELECT(SDNode *N);
    SDValue visitSELECT_CC(SDNode *N);
    SDValue visitSETCC(SDNode *N);
    SDValue visitSETCCE(SDNode *N);
    SDValue visitSIGN_EXTEND(SDNode *N);
    SDValue visitZERO_EXTEND(SDNode *N);
    SDValue visitANY_EXTEND(SDNode *N);
    SDValue visitSIGN_EXTEND_INREG(SDNode *N);
    SDValue visitSIGN_EXTEND_VECTOR_INREG(SDNode *N);
    SDValue visitTRUNCATE(SDNode *N);
    SDValue visitBITCAST(SDNode *N);
    SDValue visitBUILD_PAIR(SDNode *N);
    SDValue visitFADD(SDNode *N);
    SDValue visitFSUB(SDNode *N);
    SDValue visitFMUL(SDNode *N);
    SDValue visitFMA(SDNode *N);
    SDValue visitFDIV(SDNode *N);
    SDValue visitFREM(SDNode *N);
    SDValue visitFSQRT(SDNode *N);
    SDValue visitFCOPYSIGN(SDNode *N);
    SDValue visitSINT_TO_FP(SDNode *N);
    SDValue visitUINT_TO_FP(SDNode *N);
    SDValue visitFP_TO_SINT(SDNode *N);
    SDValue visitFP_TO_UINT(SDNode *N);
    SDValue visitFP_ROUND(SDNode *N);
    SDValue visitFP_ROUND_INREG(SDNode *N);
    SDValue visitFP_EXTEND(SDNode *N);
    SDValue visitFNEG(SDNode *N);
    SDValue visitFABS(SDNode *N);
    SDValue visitFCEIL(SDNode *N);
    SDValue visitFTRUNC(SDNode *N);
    SDValue visitFFLOOR(SDNode *N);
    SDValue visitFMINNUM(SDNode *N);
    SDValue visitFMAXNUM(SDNode *N);
    SDValue visitBRCOND(SDNode *N);
    SDValue visitBR_CC(SDNode *N);
    SDValue visitLOAD(SDNode *N);

    SDValue replaceStoreChain(StoreSDNode *ST, SDValue BetterChain);
    SDValue replaceStoreOfFPConstant(StoreSDNode *ST);

    SDValue visitSTORE(SDNode *N);
    SDValue visitINSERT_VECTOR_ELT(SDNode *N);
    SDValue visitEXTRACT_VECTOR_ELT(SDNode *N);
    SDValue visitBUILD_VECTOR(SDNode *N);
    SDValue visitCONCAT_VECTORS(SDNode *N);
    SDValue visitEXTRACT_SUBVECTOR(SDNode *N);
    SDValue visitVECTOR_SHUFFLE(SDNode *N);
    SDValue visitSCALAR_TO_VECTOR(SDNode *N);
    SDValue visitINSERT_SUBVECTOR(SDNode *N);
    SDValue visitMLOAD(SDNode *N);
    SDValue visitMSTORE(SDNode *N);
    SDValue visitMGATHER(SDNode *N);
    SDValue visitMSCATTER(SDNode *N);
    SDValue visitFP_TO_FP16(SDNode *N);
    SDValue visitFP16_TO_FP(SDNode *N);

    SDValue visitFADDForFMACombine(SDNode *N);
    SDValue visitFSUBForFMACombine(SDNode *N);
    SDValue visitFMULForFMACombine(SDNode *N);

    SDValue XformToShuffleWithZero(SDNode *N);
    SDValue ReassociateOps(unsigned Opc, SDLoc DL, SDValue LHS, SDValue RHS);

    SDValue visitShiftByConstant(SDNode *N, ConstantSDNode *Amt);

    bool SimplifySelectOps(SDNode *SELECT, SDValue LHS, SDValue RHS);
    SDValue SimplifyBinOpWithSameOpcodeHands(SDNode *N);
    SDValue SimplifySelect(SDLoc DL, SDValue N0, SDValue N1, SDValue N2);
    SDValue SimplifySelectCC(SDLoc DL, SDValue N0, SDValue N1, SDValue N2,
                             SDValue N3, ISD::CondCode CC,
                             bool NotExtCompare = false);
    SDValue SimplifySetCC(EVT VT, SDValue N0, SDValue N1, ISD::CondCode Cond,
                          SDLoc DL, bool foldBooleans = true);

    bool isSetCCEquivalent(SDValue N, SDValue &LHS, SDValue &RHS,
                           SDValue &CC) const;
    bool isOneUseSetCC(SDValue N) const;

    SDValue SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
                                         unsigned HiOp);
    SDValue CombineConsecutiveLoads(SDNode *N, EVT VT);
    SDValue CombineExtLoad(SDNode *N);
    SDValue combineRepeatedFPDivisors(SDNode *N);
    SDValue ConstantFoldBITCASTofBUILD_VECTOR(SDNode *, EVT);
    SDValue BuildSDIV(SDNode *N);
    SDValue BuildSDIVPow2(SDNode *N);
    SDValue BuildUDIV(SDNode *N);
    SDValue BuildReciprocalEstimate(SDValue Op, SDNodeFlags *Flags);
    SDValue BuildRsqrtEstimate(SDValue Op, SDNodeFlags *Flags);
    SDValue BuildRsqrtNROneConst(SDValue Op, SDValue Est, unsigned Iterations,
                                 SDNodeFlags *Flags);
    SDValue BuildRsqrtNRTwoConst(SDValue Op, SDValue Est, unsigned Iterations,
                                 SDNodeFlags *Flags);
    SDValue MatchBSwapHWordLow(SDNode *N, SDValue N0, SDValue N1,
                               bool DemandHighBits = true);
    SDValue MatchBSwapHWord(SDNode *N, SDValue N0, SDValue N1);
    SDNode *MatchRotatePosNeg(SDValue Shifted, SDValue Pos, SDValue Neg,
                              SDValue InnerPos, SDValue InnerNeg,
                              unsigned PosOpcode, unsigned NegOpcode,
                              SDLoc DL);
    SDNode *MatchRotate(SDValue LHS, SDValue RHS, SDLoc DL);
    SDValue ReduceLoadWidth(SDNode *N);
    SDValue ReduceLoadOpStoreWidth(SDNode *N);
    SDValue TransformFPLoadStorePair(SDNode *N);
    SDValue reduceBuildVecExtToExtBuildVec(SDNode *N);
    SDValue reduceBuildVecConvertToConvertBuildVec(SDNode *N);

    SDValue GetDemandedBits(SDValue V, const APInt &Mask);

    /// Walk up chain skipping non-aliasing memory nodes,
    /// looking for aliasing nodes and adding them to the Aliases vector.
    void GatherAllAliases(SDNode *N, SDValue OriginalChain,
                          SmallVectorImpl<SDValue> &Aliases);

    /// Return true if there is any possibility that the two addresses overlap.
    bool isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) const;

    /// Walk up chain skipping non-aliasing memory nodes, looking for a better
    /// chain (aliasing node.)
    SDValue FindBetterChain(SDNode *N, SDValue Chain);

    /// Do FindBetterChain for a store and any possibly adjacent stores on
    /// consecutive chains.
    bool findBetterNeighborChains(StoreSDNode *St);

    /// Holds a pointer to an LSBaseSDNode as well as information on where it
    /// is located in a sequence of memory operations connected by a chain.
    struct MemOpLink {
      MemOpLink (LSBaseSDNode *N, int64_t Offset, unsigned Seq):
      MemNode(N), OffsetFromBase(Offset), SequenceNum(Seq) { }
      // Ptr to the mem node.
      LSBaseSDNode *MemNode;
      // Offset from the base ptr.
      int64_t OffsetFromBase;
      // What is the sequence number of this mem node.
      // Lowest mem operand in the DAG starts at zero.
      unsigned SequenceNum;
    };

    /// This is a helper function for visitMUL to check the profitability
    /// of folding (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2).
    /// MulNode is the original multiply, AddNode is (add x, c1),
    /// and ConstNode is c2.
    bool isMulAddWithConstProfitable(SDNode *MulNode,
                                     SDValue &AddNode,
                                     SDValue &ConstNode);

    /// This is a helper function for MergeStoresOfConstantsOrVecElts. Returns a
    /// constant build_vector of the stored constant values in Stores.
    SDValue getMergedConstantVectorStore(SelectionDAG &DAG,
                                         SDLoc SL,
                                         ArrayRef<MemOpLink> Stores,
                                         SmallVectorImpl<SDValue> &Chains,
                                         EVT Ty) const;

    /// This is a helper function for visitAND and visitZERO_EXTEND.  Returns
    /// true if the (and (load x) c) pattern matches an extload.  ExtVT returns
    /// the type of the loaded value to be extended.  LoadedVT returns the type
    /// of the original loaded value.  NarrowLoad returns whether the load would
    /// need to be narrowed in order to match.
    bool isAndLoadExtLoad(ConstantSDNode *AndC, LoadSDNode *LoadN,
                          EVT LoadResultTy, EVT &ExtVT, EVT &LoadedVT,
                          bool &NarrowLoad);

    /// This is a helper function for MergeConsecutiveStores. When the source
    /// elements of the consecutive stores are all constants or all extracted
    /// vector elements, try to merge them into one larger store.
    /// \return True if a merged store was created.
    bool MergeStoresOfConstantsOrVecElts(SmallVectorImpl<MemOpLink> &StoreNodes,
                                         EVT MemVT, unsigned NumStores,
                                         bool IsConstantSrc, bool UseVector);

    /// This is a helper function for MergeConsecutiveStores.
    /// Stores that may be merged are placed in StoreNodes.
    /// Loads that may alias with those stores are placed in AliasLoadNodes.
    void getStoreMergeAndAliasCandidates(
        StoreSDNode* St, SmallVectorImpl<MemOpLink> &StoreNodes,
        SmallVectorImpl<LSBaseSDNode*> &AliasLoadNodes);

    /// Merge consecutive store operations into a wide store.
    /// This optimization uses wide integers or vectors when possible.
    /// \return True if some memory operations were changed.
    bool MergeConsecutiveStores(StoreSDNode *N);

    /// \brief Try to transform a truncation where C is a constant:
    ///     (trunc (and X, C)) -> (and (trunc X), (trunc C))
    ///
    /// \p N needs to be a truncation and its first operand an AND. Other
    /// requirements are checked by the function (e.g. that trunc is
    /// single-use) and if missed an empty SDValue is returned.
    SDValue distributeTruncateThroughAnd(SDNode *N);

  public:
    DAGCombiner(SelectionDAG &D, AliasAnalysis &A, CodeGenOpt::Level OL)
        : DAG(D), TLI(D.getTargetLoweringInfo()), Level(BeforeLegalizeTypes),
          OptLevel(OL), LegalOperations(false), LegalTypes(false), AA(A) {
      ForCodeSize = DAG.getMachineFunction().getFunction()->optForSize();
    }

    /// Runs the dag combiner on all nodes in the work list
    void Run(CombineLevel AtLevel);

    SelectionDAG &getDAG() const { return DAG; }

    /// Returns a type large enough to hold any valid shift amount - before type
    /// legalization these can be huge.
    EVT getShiftAmountTy(EVT LHSTy) {
      assert(LHSTy.isInteger() && "Shift amount is not an integer type!");
      if (LHSTy.isVector())
        return LHSTy;
      auto &DL = DAG.getDataLayout();
      return LegalTypes ? TLI.getScalarShiftAmountTy(DL, LHSTy)
                        : TLI.getPointerTy(DL);
    }

    /// This method returns true if we are running before type legalization or
    /// if the specified VT is legal.
    bool isTypeLegal(const EVT &VT) {
      if (!LegalTypes) return true;
      return TLI.isTypeLegal(VT);
    }

    /// Convenience wrapper around TargetLowering::getSetCCResultType
    EVT getSetCCResultType(EVT VT) const {
      return TLI.getSetCCResultType(DAG.getDataLayout(), *DAG.getContext(), VT);
    }
  };
}


namespace {
/// This class is a DAGUpdateListener that removes any deleted
/// nodes from the worklist.
class WorklistRemover : public SelectionDAG::DAGUpdateListener {
  DAGCombiner &DC;
public:
  explicit WorklistRemover(DAGCombiner &dc)
    : SelectionDAG::DAGUpdateListener(dc.getDAG()), DC(dc) {}

  void NodeDeleted(SDNode *N, SDNode *E) override {
    DC.removeFromWorklist(N);
  }
};
}

//===----------------------------------------------------------------------===//
//  TargetLowering::DAGCombinerInfo implementation
//===----------------------------------------------------------------------===//

void TargetLowering::DAGCombinerInfo::AddToWorklist(SDNode *N) {
  ((DAGCombiner*)DC)->AddToWorklist(N);
}

void TargetLowering::DAGCombinerInfo::RemoveFromWorklist(SDNode *N) {
  ((DAGCombiner*)DC)->removeFromWorklist(N);
}

SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, ArrayRef<SDValue> To, bool AddTo) {
  return ((DAGCombiner*)DC)->CombineTo(N, &To[0], To.size(), AddTo);
}

SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDValue Res, bool AddTo) {
  return ((DAGCombiner*)DC)->CombineTo(N, Res, AddTo);
}


SDValue TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDValue Res0, SDValue Res1, bool AddTo) {
  return ((DAGCombiner*)DC)->CombineTo(N, Res0, Res1, AddTo);
}

void TargetLowering::DAGCombinerInfo::
CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO) {
  return ((DAGCombiner*)DC)->CommitTargetLoweringOpt(TLO);
}

//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//

void DAGCombiner::deleteAndRecombine(SDNode *N) {
  removeFromWorklist(N);

  // If the operands of this node are only used by the node, they will now be
  // dead. Make sure to re-visit them and recursively delete dead nodes.
  for (const SDValue &Op : N->ops())
    // For an operand generating multiple values, one of the values may
    // become dead allowing further simplification (e.g. split index
    // arithmetic from an indexed load).
    if (Op->hasOneUse() || Op->getNumValues() > 1)
      AddToWorklist(Op.getNode());

  DAG.DeleteNode(N);
}

/// Return 1 if we can compute the negated form of the specified expression for
/// the same cost as the expression itself, or 2 if we can compute the negated
/// form more cheaply than the expression itself.
static char isNegatibleForFree(SDValue Op, bool LegalOperations,
                               const TargetLowering &TLI,
                               const TargetOptions *Options,
                               unsigned Depth = 0) {
  // fneg is removable even if it has multiple uses.
  if (Op.getOpcode() == ISD::FNEG) return 2;

  // Don't allow anything with multiple uses.
  if (!Op.hasOneUse()) return 0;

  // Don't recurse exponentially.
  if (Depth > 6) return 0;

  switch (Op.getOpcode()) {
  default: return false;
  case ISD::ConstantFP:
    // Don't invert constant FP values after legalize.  The negated constant
    // isn't necessarily legal.
    return LegalOperations ? 0 : 1;
  case ISD::FADD:
    // FIXME: determine better conditions for this xform.
    if (!Options->UnsafeFPMath) return 0;

    // After operation legalization, it might not be legal to create new FSUBs.
    if (LegalOperations &&
        !TLI.isOperationLegalOrCustom(ISD::FSUB,  Op.getValueType()))
      return 0;

    // fold (fneg (fadd A, B)) -> (fsub (fneg A), B)
    if (char V = isNegatibleForFree(Op.getOperand(0), LegalOperations, TLI,
                                    Options, Depth + 1))
      return V;
    // fold (fneg (fadd A, B)) -> (fsub (fneg B), A)
    return isNegatibleForFree(Op.getOperand(1), LegalOperations, TLI, Options,
                              Depth + 1);
  case ISD::FSUB:
    // We can't turn -(A-B) into B-A when we honor signed zeros.
    if (!Options->UnsafeFPMath) return 0;

    // fold (fneg (fsub A, B)) -> (fsub B, A)
    return 1;

  case ISD::FMUL:
  case ISD::FDIV:
    if (Options->HonorSignDependentRoundingFPMath()) return 0;

    // fold (fneg (fmul X, Y)) -> (fmul (fneg X), Y) or (fmul X, (fneg Y))
    if (char V = isNegatibleForFree(Op.getOperand(0), LegalOperations, TLI,
                                    Options, Depth + 1))
      return V;

    return isNegatibleForFree(Op.getOperand(1), LegalOperations, TLI, Options,
                              Depth + 1);

  case ISD::FP_EXTEND:
  case ISD::FP_ROUND:
  case ISD::FSIN:
    return isNegatibleForFree(Op.getOperand(0), LegalOperations, TLI, Options,
                              Depth + 1);
  }
}

/// If isNegatibleForFree returns true, return the newly negated expression.
static SDValue GetNegatedExpression(SDValue Op, SelectionDAG &DAG,
                                    bool LegalOperations, unsigned Depth = 0) {
  const TargetOptions &Options = DAG.getTarget().Options;
  // fneg is removable even if it has multiple uses.
  if (Op.getOpcode() == ISD::FNEG) return Op.getOperand(0);

  // Don't allow anything with multiple uses.
  assert(Op.hasOneUse() && "Unknown reuse!");

  assert(Depth <= 6 && "GetNegatedExpression doesn't match isNegatibleForFree");

  const SDNodeFlags *Flags = Op.getNode()->getFlags();

  switch (Op.getOpcode()) {
  default: llvm_unreachable("Unknown code");
  case ISD::ConstantFP: {
    APFloat V = cast<ConstantFPSDNode>(Op)->getValueAPF();
    V.changeSign();
    return DAG.getConstantFP(V, SDLoc(Op), Op.getValueType());
  }
  case ISD::FADD:
    // FIXME: determine better conditions for this xform.
    assert(Options.UnsafeFPMath);

    // fold (fneg (fadd A, B)) -> (fsub (fneg A), B)
    if (isNegatibleForFree(Op.getOperand(0), LegalOperations,
                           DAG.getTargetLoweringInfo(), &Options, Depth+1))
      return DAG.getNode(ISD::FSUB, SDLoc(Op), Op.getValueType(),
                         GetNegatedExpression(Op.getOperand(0), DAG,
                                              LegalOperations, Depth+1),
                         Op.getOperand(1), Flags);
    // fold (fneg (fadd A, B)) -> (fsub (fneg B), A)
    return DAG.getNode(ISD::FSUB, SDLoc(Op), Op.getValueType(),
                       GetNegatedExpression(Op.getOperand(1), DAG,
                                            LegalOperations, Depth+1),
                       Op.getOperand(0), Flags);
  case ISD::FSUB:
    // We can't turn -(A-B) into B-A when we honor signed zeros.
    assert(Options.UnsafeFPMath);

    // fold (fneg (fsub 0, B)) -> B
    if (ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(Op.getOperand(0)))
      if (N0CFP->isZero())
        return Op.getOperand(1);

    // fold (fneg (fsub A, B)) -> (fsub B, A)
    return DAG.getNode(ISD::FSUB, SDLoc(Op), Op.getValueType(),
                       Op.getOperand(1), Op.getOperand(0), Flags);

  case ISD::FMUL:
  case ISD::FDIV:
    assert(!Options.HonorSignDependentRoundingFPMath());

    // fold (fneg (fmul X, Y)) -> (fmul (fneg X), Y)
    if (isNegatibleForFree(Op.getOperand(0), LegalOperations,
                           DAG.getTargetLoweringInfo(), &Options, Depth+1))
      return DAG.getNode(Op.getOpcode(), SDLoc(Op), Op.getValueType(),
                         GetNegatedExpression(Op.getOperand(0), DAG,
                                              LegalOperations, Depth+1),
                         Op.getOperand(1), Flags);

    // fold (fneg (fmul X, Y)) -> (fmul X, (fneg Y))
    return DAG.getNode(Op.getOpcode(), SDLoc(Op), Op.getValueType(),
                       Op.getOperand(0),
                       GetNegatedExpression(Op.getOperand(1), DAG,
                                            LegalOperations, Depth+1), Flags);

  case ISD::FP_EXTEND:
  case ISD::FSIN:
    return DAG.getNode(Op.getOpcode(), SDLoc(Op), Op.getValueType(),
                       GetNegatedExpression(Op.getOperand(0), DAG,
                                            LegalOperations, Depth+1));
  case ISD::FP_ROUND:
      return DAG.getNode(ISD::FP_ROUND, SDLoc(Op), Op.getValueType(),
                         GetNegatedExpression(Op.getOperand(0), DAG,
                                              LegalOperations, Depth+1),
                         Op.getOperand(1));
  }
}

// Return true if this node is a setcc, or is a select_cc
// that selects between the target values used for true and false, making it
// equivalent to a setcc. Also, set the incoming LHS, RHS, and CC references to
// the appropriate nodes based on the type of node we are checking. This
// simplifies life a bit for the callers.
bool DAGCombiner::isSetCCEquivalent(SDValue N, SDValue &LHS, SDValue &RHS,
                                    SDValue &CC) const {
  if (N.getOpcode() == ISD::SETCC) {
    LHS = N.getOperand(0);
    RHS = N.getOperand(1);
    CC  = N.getOperand(2);
    return true;
  }

  if (N.getOpcode() != ISD::SELECT_CC ||
      !TLI.isConstTrueVal(N.getOperand(2).getNode()) ||
      !TLI.isConstFalseVal(N.getOperand(3).getNode()))
    return false;

  if (TLI.getBooleanContents(N.getValueType()) ==
      TargetLowering::UndefinedBooleanContent)
    return false;

  LHS = N.getOperand(0);
  RHS = N.getOperand(1);
  CC  = N.getOperand(4);
  return true;
}

/// Return true if this is a SetCC-equivalent operation with only one use.
/// If this is true, it allows the users to invert the operation for free when
/// it is profitable to do so.
bool DAGCombiner::isOneUseSetCC(SDValue N) const {
  SDValue N0, N1, N2;
  if (isSetCCEquivalent(N, N0, N1, N2) && N.getNode()->hasOneUse())
    return true;
  return false;
}

/// Returns true if N is a BUILD_VECTOR node whose
/// elements are all the same constant or undefined.
static bool isConstantSplatVector(SDNode *N, APInt& SplatValue) {
  BuildVectorSDNode *C = dyn_cast<BuildVectorSDNode>(N);
  if (!C)
    return false;

  APInt SplatUndef;
  unsigned SplatBitSize;
  bool HasAnyUndefs;
  EVT EltVT = N->getValueType(0).getVectorElementType();
  return (C->isConstantSplat(SplatValue, SplatUndef, SplatBitSize,
                             HasAnyUndefs) &&
          EltVT.getSizeInBits() >= SplatBitSize);
}

// \brief Returns the SDNode if it is a constant integer BuildVector
// or constant integer.
static SDNode *isConstantIntBuildVectorOrConstantInt(SDValue N) {
  if (isa<ConstantSDNode>(N))
    return N.getNode();
  if (ISD::isBuildVectorOfConstantSDNodes(N.getNode()))
    return N.getNode();
  return nullptr;
}

// \brief Returns the SDNode if it is a constant float BuildVector
// or constant float.
static SDNode *isConstantFPBuildVectorOrConstantFP(SDValue N) {
  if (isa<ConstantFPSDNode>(N))
    return N.getNode();
  if (ISD::isBuildVectorOfConstantFPSDNodes(N.getNode()))
    return N.getNode();
  return nullptr;
}

// \brief Returns the SDNode if it is a constant splat BuildVector or constant
// int.
static ConstantSDNode *isConstOrConstSplat(SDValue N) {
  if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N))
    return CN;

  if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N)) {
    BitVector UndefElements;
    ConstantSDNode *CN = BV->getConstantSplatNode(&UndefElements);

    // BuildVectors can truncate their operands. Ignore that case here.
    // FIXME: We blindly ignore splats which include undef which is overly
    // pessimistic.
    if (CN && UndefElements.none() &&
        CN->getValueType(0) == N.getValueType().getScalarType())
      return CN;
  }

  return nullptr;
}

// \brief Returns the SDNode if it is a constant splat BuildVector or constant
// float.
static ConstantFPSDNode *isConstOrConstSplatFP(SDValue N) {
  if (ConstantFPSDNode *CN = dyn_cast<ConstantFPSDNode>(N))
    return CN;

  if (BuildVectorSDNode *BV = dyn_cast<BuildVectorSDNode>(N)) {
    BitVector UndefElements;
    ConstantFPSDNode *CN = BV->getConstantFPSplatNode(&UndefElements);

    if (CN && UndefElements.none())
      return CN;
  }

  return nullptr;
}

SDValue DAGCombiner::ReassociateOps(unsigned Opc, SDLoc DL,
                                    SDValue N0, SDValue N1) {
  EVT VT = N0.getValueType();
  if (N0.getOpcode() == Opc) {
    if (SDNode *L = isConstantIntBuildVectorOrConstantInt(N0.getOperand(1))) {
      if (SDNode *R = isConstantIntBuildVectorOrConstantInt(N1)) {
        // reassoc. (op (op x, c1), c2) -> (op x, (op c1, c2))
        if (SDValue OpNode = DAG.FoldConstantArithmetic(Opc, DL, VT, L, R))
          return DAG.getNode(Opc, DL, VT, N0.getOperand(0), OpNode);
        return SDValue();
      }
      if (N0.hasOneUse()) {
        // reassoc. (op (op x, c1), y) -> (op (op x, y), c1) iff x+c1 has one
        // use
        SDValue OpNode = DAG.getNode(Opc, SDLoc(N0), VT, N0.getOperand(0), N1);
        if (!OpNode.getNode())
          return SDValue();
        AddToWorklist(OpNode.getNode());
        return DAG.getNode(Opc, DL, VT, OpNode, N0.getOperand(1));
      }
    }
  }

  if (N1.getOpcode() == Opc) {
    if (SDNode *R = isConstantIntBuildVectorOrConstantInt(N1.getOperand(1))) {
      if (SDNode *L = isConstantIntBuildVectorOrConstantInt(N0)) {
        // reassoc. (op c2, (op x, c1)) -> (op x, (op c1, c2))
        if (SDValue OpNode = DAG.FoldConstantArithmetic(Opc, DL, VT, R, L))
          return DAG.getNode(Opc, DL, VT, N1.getOperand(0), OpNode);
        return SDValue();
      }
      if (N1.hasOneUse()) {
        // reassoc. (op y, (op x, c1)) -> (op (op x, y), c1) iff x+c1 has one
        // use
        SDValue OpNode = DAG.getNode(Opc, SDLoc(N0), VT, N1.getOperand(0), N0);
        if (!OpNode.getNode())
          return SDValue();
        AddToWorklist(OpNode.getNode());
        return DAG.getNode(Opc, DL, VT, OpNode, N1.getOperand(1));
      }
    }
  }

  return SDValue();
}

SDValue DAGCombiner::CombineTo(SDNode *N, const SDValue *To, unsigned NumTo,
                               bool AddTo) {
  assert(N->getNumValues() == NumTo && "Broken CombineTo call!");
  ++NodesCombined;
  DEBUG(dbgs() << "\nReplacing.1 ";
        N->dump(&DAG);
        dbgs() << "\nWith: ";
        To[0].getNode()->dump(&DAG);
        dbgs() << " and " << NumTo-1 << " other values\n");
  for (unsigned i = 0, e = NumTo; i != e; ++i)
    assert((!To[i].getNode() ||
            N->getValueType(i) == To[i].getValueType()) &&
           "Cannot combine value to value of different type!");

  WorklistRemover DeadNodes(*this);
  DAG.ReplaceAllUsesWith(N, To);
  if (AddTo) {
    // Push the new nodes and any users onto the worklist
    for (unsigned i = 0, e = NumTo; i != e; ++i) {
      if (To[i].getNode()) {
        AddToWorklist(To[i].getNode());
        AddUsersToWorklist(To[i].getNode());
      }
    }
  }

  // Finally, if the node is now dead, remove it from the graph.  The node
  // may not be dead if the replacement process recursively simplified to
  // something else needing this node.
  if (N->use_empty())
    deleteAndRecombine(N);
  return SDValue(N, 0);
}

void DAGCombiner::
CommitTargetLoweringOpt(const TargetLowering::TargetLoweringOpt &TLO) {
  // Replace all uses.  If any nodes become isomorphic to other nodes and
  // are deleted, make sure to remove them from our worklist.
  WorklistRemover DeadNodes(*this);
  DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New);

  // Push the new node and any (possibly new) users onto the worklist.
  AddToWorklist(TLO.New.getNode());
  AddUsersToWorklist(TLO.New.getNode());

  // Finally, if the node is now dead, remove it from the graph.  The node
  // may not be dead if the replacement process recursively simplified to
  // something else needing this node.
  if (TLO.Old.getNode()->use_empty())
    deleteAndRecombine(TLO.Old.getNode());
}

/// Check the specified integer node value to see if it can be simplified or if
/// things it uses can be simplified by bit propagation. If so, return true.
bool DAGCombiner::SimplifyDemandedBits(SDValue Op, const APInt &Demanded) {
  TargetLowering::TargetLoweringOpt TLO(DAG, LegalTypes, LegalOperations);
  APInt KnownZero, KnownOne;
  if (!TLI.SimplifyDemandedBits(Op, Demanded, KnownZero, KnownOne, TLO))
    return false;

  // Revisit the node.
  AddToWorklist(Op.getNode());

  // Replace the old value with the new one.
  ++NodesCombined;
  DEBUG(dbgs() << "\nReplacing.2 ";
        TLO.Old.getNode()->dump(&DAG);
        dbgs() << "\nWith: ";
        TLO.New.getNode()->dump(&DAG);
        dbgs() << '\n');

  CommitTargetLoweringOpt(TLO);
  return true;
}

void DAGCombiner::ReplaceLoadWithPromotedLoad(SDNode *Load, SDNode *ExtLoad) {
  SDLoc dl(Load);
  EVT VT = Load->getValueType(0);
  SDValue Trunc = DAG.getNode(ISD::TRUNCATE, dl, VT, SDValue(ExtLoad, 0));

  DEBUG(dbgs() << "\nReplacing.9 ";
        Load->dump(&DAG);
        dbgs() << "\nWith: ";
        Trunc.getNode()->dump(&DAG);
        dbgs() << '\n');
  WorklistRemover DeadNodes(*this);
  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 0), Trunc);
  DAG.ReplaceAllUsesOfValueWith(SDValue(Load, 1), SDValue(ExtLoad, 1));
  deleteAndRecombine(Load);
  AddToWorklist(Trunc.getNode());
}

SDValue DAGCombiner::PromoteOperand(SDValue Op, EVT PVT, bool &Replace) {
  Replace = false;
  SDLoc dl(Op);
  if (LoadSDNode *LD = dyn_cast<LoadSDNode>(Op)) {
    EVT MemVT = LD->getMemoryVT();
    ISD::LoadExtType ExtType = ISD::isNON_EXTLoad(LD)
      ? (TLI.isLoadExtLegal(ISD::ZEXTLOAD, PVT, MemVT) ? ISD::ZEXTLOAD
                                                       : ISD::EXTLOAD)
      : LD->getExtensionType();
    Replace = true;
    return DAG.getExtLoad(ExtType, dl, PVT,
                          LD->getChain(), LD->getBasePtr(),
                          MemVT, LD->getMemOperand());
  }

  unsigned Opc = Op.getOpcode();
  switch (Opc) {
  default: break;
  case ISD::AssertSext:
    return DAG.getNode(ISD::AssertSext, dl, PVT,
                       SExtPromoteOperand(Op.getOperand(0), PVT),
                       Op.getOperand(1));
  case ISD::AssertZext:
    return DAG.getNode(ISD::AssertZext, dl, PVT,
                       ZExtPromoteOperand(Op.getOperand(0), PVT),
                       Op.getOperand(1));
  case ISD::Constant: {
    unsigned ExtOpc =
      Op.getValueType().isByteSized() ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND;
    return DAG.getNode(ExtOpc, dl, PVT, Op);
  }
  }

  if (!TLI.isOperationLegal(ISD::ANY_EXTEND, PVT))
    return SDValue();
  return DAG.getNode(ISD::ANY_EXTEND, dl, PVT, Op);
}

SDValue DAGCombiner::SExtPromoteOperand(SDValue Op, EVT PVT) {
  if (!TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, PVT))
    return SDValue();
  EVT OldVT = Op.getValueType();
  SDLoc dl(Op);
  bool Replace = false;
  SDValue NewOp = PromoteOperand(Op, PVT, Replace);
  if (!NewOp.getNode())
    return SDValue();
  AddToWorklist(NewOp.getNode());

  if (Replace)
    ReplaceLoadWithPromotedLoad(Op.getNode(), NewOp.getNode());
  return DAG.getNode(ISD::SIGN_EXTEND_INREG, dl, NewOp.getValueType(), NewOp,
                     DAG.getValueType(OldVT));
}

SDValue DAGCombiner::ZExtPromoteOperand(SDValue Op, EVT PVT) {
  EVT OldVT = Op.getValueType();
  SDLoc dl(Op);
  bool Replace = false;
  SDValue NewOp = PromoteOperand(Op, PVT, Replace);
  if (!NewOp.getNode())
    return SDValue();
  AddToWorklist(NewOp.getNode());

  if (Replace)
    ReplaceLoadWithPromotedLoad(Op.getNode(), NewOp.getNode());
  return DAG.getZeroExtendInReg(NewOp, dl, OldVT);
}

/// Promote the specified integer binary operation if the target indicates it is
/// beneficial. e.g. On x86, it's usually better to promote i16 operations to
/// i32 since i16 instructions are longer.
SDValue DAGCombiner::PromoteIntBinOp(SDValue Op) {
  if (!LegalOperations)
    return SDValue();

  EVT VT = Op.getValueType();
  if (VT.isVector() || !VT.isInteger())
    return SDValue();

  // If operation type is 'undesirable', e.g. i16 on x86, consider
  // promoting it.
  unsigned Opc = Op.getOpcode();
  if (TLI.isTypeDesirableForOp(Opc, VT))
    return SDValue();

  EVT PVT = VT;
  // Consult target whether it is a good idea to promote this operation and
  // what's the right type to promote it to.
  if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
    assert(PVT != VT && "Don't know what type to promote to!");

    bool Replace0 = false;
    SDValue N0 = Op.getOperand(0);
    SDValue NN0 = PromoteOperand(N0, PVT, Replace0);
    if (!NN0.getNode())
      return SDValue();

    bool Replace1 = false;
    SDValue N1 = Op.getOperand(1);
    SDValue NN1;
    if (N0 == N1)
      NN1 = NN0;
    else {
      NN1 = PromoteOperand(N1, PVT, Replace1);
      if (!NN1.getNode())
        return SDValue();
    }

    AddToWorklist(NN0.getNode());
    if (NN1.getNode())
      AddToWorklist(NN1.getNode());

    if (Replace0)
      ReplaceLoadWithPromotedLoad(N0.getNode(), NN0.getNode());
    if (Replace1)
      ReplaceLoadWithPromotedLoad(N1.getNode(), NN1.getNode());

    DEBUG(dbgs() << "\nPromoting ";
          Op.getNode()->dump(&DAG));
    SDLoc dl(Op);
    return DAG.getNode(ISD::TRUNCATE, dl, VT,
                       DAG.getNode(Opc, dl, PVT, NN0, NN1));
  }
  return SDValue();
}

/// Promote the specified integer shift operation if the target indicates it is
/// beneficial. e.g. On x86, it's usually better to promote i16 operations to
/// i32 since i16 instructions are longer.
SDValue DAGCombiner::PromoteIntShiftOp(SDValue Op) {
  if (!LegalOperations)
    return SDValue();

  EVT VT = Op.getValueType();
  if (VT.isVector() || !VT.isInteger())
    return SDValue();

  // If operation type is 'undesirable', e.g. i16 on x86, consider
  // promoting it.
  unsigned Opc = Op.getOpcode();
  if (TLI.isTypeDesirableForOp(Opc, VT))
    return SDValue();

  EVT PVT = VT;
  // Consult target whether it is a good idea to promote this operation and
  // what's the right type to promote it to.
  if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
    assert(PVT != VT && "Don't know what type to promote to!");

    bool Replace = false;
    SDValue N0 = Op.getOperand(0);
    if (Opc == ISD::SRA)
      N0 = SExtPromoteOperand(Op.getOperand(0), PVT);
    else if (Opc == ISD::SRL)
      N0 = ZExtPromoteOperand(Op.getOperand(0), PVT);
    else
      N0 = PromoteOperand(N0, PVT, Replace);
    if (!N0.getNode())
      return SDValue();

    AddToWorklist(N0.getNode());
    if (Replace)
      ReplaceLoadWithPromotedLoad(Op.getOperand(0).getNode(), N0.getNode());

    DEBUG(dbgs() << "\nPromoting ";
          Op.getNode()->dump(&DAG));
    SDLoc dl(Op);
    return DAG.getNode(ISD::TRUNCATE, dl, VT,
                       DAG.getNode(Opc, dl, PVT, N0, Op.getOperand(1)));
  }
  return SDValue();
}

SDValue DAGCombiner::PromoteExtend(SDValue Op) {
  if (!LegalOperations)
    return SDValue();

  EVT VT = Op.getValueType();
  if (VT.isVector() || !VT.isInteger())
    return SDValue();

  // If operation type is 'undesirable', e.g. i16 on x86, consider
  // promoting it.
  unsigned Opc = Op.getOpcode();
  if (TLI.isTypeDesirableForOp(Opc, VT))
    return SDValue();

  EVT PVT = VT;
  // Consult target whether it is a good idea to promote this operation and
  // what's the right type to promote it to.
  if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
    assert(PVT != VT && "Don't know what type to promote to!");
    // fold (aext (aext x)) -> (aext x)
    // fold (aext (zext x)) -> (zext x)
    // fold (aext (sext x)) -> (sext x)
    DEBUG(dbgs() << "\nPromoting ";
          Op.getNode()->dump(&DAG));
    return DAG.getNode(Op.getOpcode(), SDLoc(Op), VT, Op.getOperand(0));
  }
  return SDValue();
}

bool DAGCombiner::PromoteLoad(SDValue Op) {
  if (!LegalOperations)
    return false;

  EVT VT = Op.getValueType();
  if (VT.isVector() || !VT.isInteger())
    return false;

  // If operation type is 'undesirable', e.g. i16 on x86, consider
  // promoting it.
  unsigned Opc = Op.getOpcode();
  if (TLI.isTypeDesirableForOp(Opc, VT))
    return false;

  EVT PVT = VT;
  // Consult target whether it is a good idea to promote this operation and
  // what's the right type to promote it to.
  if (TLI.IsDesirableToPromoteOp(Op, PVT)) {
    assert(PVT != VT && "Don't know what type to promote to!");

    SDLoc dl(Op);
    SDNode *N = Op.getNode();
    LoadSDNode *LD = cast<LoadSDNode>(N);
    EVT MemVT = LD->getMemoryVT();
    ISD::LoadExtType ExtType = ISD::isNON_EXTLoad(LD)
      ? (TLI.isLoadExtLegal(ISD::ZEXTLOAD, PVT, MemVT) ? ISD::ZEXTLOAD
                                                       : ISD::EXTLOAD)
      : LD->getExtensionType();
    SDValue NewLD = DAG.getExtLoad(ExtType, dl, PVT,
                                   LD->getChain(), LD->getBasePtr(),
                                   MemVT, LD->getMemOperand());
    SDValue Result = DAG.getNode(ISD::TRUNCATE, dl, VT, NewLD);

    DEBUG(dbgs() << "\nPromoting ";
          N->dump(&DAG);
          dbgs() << "\nTo: ";
          Result.getNode()->dump(&DAG);
          dbgs() << '\n');
    WorklistRemover DeadNodes(*this);
    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 0), Result);
    DAG.ReplaceAllUsesOfValueWith(SDValue(N, 1), NewLD.getValue(1));
    deleteAndRecombine(N);
    AddToWorklist(Result.getNode());
    return true;
  }
  return false;
}

/// \brief Recursively delete a node which has no uses and any operands for
/// which it is the only use.
///
/// Note that this both deletes the nodes and removes them from the worklist.
/// It also adds any nodes who have had a user deleted to the worklist as they
/// may now have only one use and subject to other combines.
bool DAGCombiner::recursivelyDeleteUnusedNodes(SDNode *N) {
  if (!N->use_empty())
    return false;

  SmallSetVector<SDNode *, 16> Nodes;
  Nodes.insert(N);
  do {
    N = Nodes.pop_back_val();
    if (!N)
      continue;

    if (N->use_empty()) {
      for (const SDValue &ChildN : N->op_values())
        Nodes.insert(ChildN.getNode());

      removeFromWorklist(N);
      DAG.DeleteNode(N);
    } else {
      AddToWorklist(N);
    }
  } while (!Nodes.empty());
  return true;
}

//===----------------------------------------------------------------------===//
//  Main DAG Combiner implementation
//===----------------------------------------------------------------------===//

void DAGCombiner::Run(CombineLevel AtLevel) {
  // set the instance variables, so that the various visit routines may use it.
  Level = AtLevel;
  LegalOperations = Level >= AfterLegalizeVectorOps;
  LegalTypes = Level >= AfterLegalizeTypes;

  // Add all the dag nodes to the worklist.
  for (SDNode &Node : DAG.allnodes())
    AddToWorklist(&Node);

  // Create a dummy node (which is not added to allnodes), that adds a reference
  // to the root node, preventing it from being deleted, and tracking any
  // changes of the root.
  HandleSDNode Dummy(DAG.getRoot());

  // while the worklist isn't empty, find a node and
  // try and combine it.
  while (!WorklistMap.empty()) {
    SDNode *N;
    // The Worklist holds the SDNodes in order, but it may contain null entries.
    do {
      N = Worklist.pop_back_val();
    } while (!N);

    bool GoodWorklistEntry = WorklistMap.erase(N);
    (void)GoodWorklistEntry;
    assert(GoodWorklistEntry &&
           "Found a worklist entry without a corresponding map entry!");

    // If N has no uses, it is dead.  Make sure to revisit all N's operands once
    // N is deleted from the DAG, since they too may now be dead or may have a
    // reduced number of uses, allowing other xforms.
    if (recursivelyDeleteUnusedNodes(N))
      continue;

    WorklistRemover DeadNodes(*this);

    // If this combine is running after legalizing the DAG, re-legalize any
    // nodes pulled off the worklist.
    if (Level == AfterLegalizeDAG) {
      SmallSetVector<SDNode *, 16> UpdatedNodes;
      bool NIsValid = DAG.LegalizeOp(N, UpdatedNodes);

      for (SDNode *LN : UpdatedNodes) {
        AddToWorklist(LN);
        AddUsersToWorklist(LN);
      }
      if (!NIsValid)
        continue;
    }

    DEBUG(dbgs() << "\nCombining: "; N->dump(&DAG));

    // Add any operands of the new node which have not yet been combined to the
    // worklist as well. Because the worklist uniques things already, this
    // won't repeatedly process the same operand.
    CombinedNodes.insert(N);
    for (const SDValue &ChildN : N->op_values())
      if (!CombinedNodes.count(ChildN.getNode()))
        AddToWorklist(ChildN.getNode());

    SDValue RV = combine(N);

    if (!RV.getNode())
      continue;

    ++NodesCombined;

    // If we get back the same node we passed in, rather than a new node or
    // zero, we know that the node must have defined multiple values and
    // CombineTo was used.  Since CombineTo takes care of the worklist
    // mechanics for us, we have no work to do in this case.
    if (RV.getNode() == N)
      continue;

    assert(N->getOpcode() != ISD::DELETED_NODE &&
           RV.getNode()->getOpcode() != ISD::DELETED_NODE &&
           "Node was deleted but visit returned new node!");

    DEBUG(dbgs() << " ... into: ";
          RV.getNode()->dump(&DAG));

    // Transfer debug value.
    DAG.TransferDbgValues(SDValue(N, 0), RV);
    if (N->getNumValues() == RV.getNode()->getNumValues())
      DAG.ReplaceAllUsesWith(N, RV.getNode());
    else {
      assert(N->getValueType(0) == RV.getValueType() &&
             N->getNumValues() == 1 && "Type mismatch");
      SDValue OpV = RV;
      DAG.ReplaceAllUsesWith(N, &OpV);
    }

    // Push the new node and any users onto the worklist
    AddToWorklist(RV.getNode());
    AddUsersToWorklist(RV.getNode());

    // Finally, if the node is now dead, remove it from the graph.  The node
    // may not be dead if the replacement process recursively simplified to
    // something else needing this node. This will also take care of adding any
    // operands which have lost a user to the worklist.
    recursivelyDeleteUnusedNodes(N);
  }

  // If the root changed (e.g. it was a dead load, update the root).
  DAG.setRoot(Dummy.getValue());
  DAG.RemoveDeadNodes();
}

SDValue DAGCombiner::visit(SDNode *N) {
  switch (N->getOpcode()) {
  default: break;
  case ISD::TokenFactor:        return visitTokenFactor(N);
  case ISD::MERGE_VALUES:       return visitMERGE_VALUES(N);
  case ISD::ADD:                return visitADD(N);
  case ISD::SUB:                return visitSUB(N);
  case ISD::ADDC:               return visitADDC(N);
  case ISD::SUBC:               return visitSUBC(N);
  case ISD::ADDE:               return visitADDE(N);
  case ISD::SUBE:               return visitSUBE(N);
  case ISD::MUL:                return visitMUL(N);
  case ISD::SDIV:               return visitSDIV(N);
  case ISD::UDIV:               return visitUDIV(N);
  case ISD::SREM:
  case ISD::UREM:               return visitREM(N);
  case ISD::MULHU:              return visitMULHU(N);
  case ISD::MULHS:              return visitMULHS(N);
  case ISD::SMUL_LOHI:          return visitSMUL_LOHI(N);
  case ISD::UMUL_LOHI:          return visitUMUL_LOHI(N);
  case ISD::SMULO:              return visitSMULO(N);
  case ISD::UMULO:              return visitUMULO(N);
  case ISD::SMIN:
  case ISD::SMAX:
  case ISD::UMIN:
  case ISD::UMAX:               return visitIMINMAX(N);
  case ISD::AND:                return visitAND(N);
  case ISD::OR:                 return visitOR(N);
  case ISD::XOR:                return visitXOR(N);
  case ISD::SHL:                return visitSHL(N);
  case ISD::SRA:                return visitSRA(N);
  case ISD::SRL:                return visitSRL(N);
  case ISD::ROTR:
  case ISD::ROTL:               return visitRotate(N);
  case ISD::BSWAP:              return visitBSWAP(N);
  case ISD::CTLZ:               return visitCTLZ(N);
  case ISD::CTLZ_ZERO_UNDEF:    return visitCTLZ_ZERO_UNDEF(N);
  case ISD::CTTZ:               return visitCTTZ(N);
  case ISD::CTTZ_ZERO_UNDEF:    return visitCTTZ_ZERO_UNDEF(N);
  case ISD::CTPOP:              return visitCTPOP(N);
  case ISD::SELECT:             return visitSELECT(N);
  case ISD::VSELECT:            return visitVSELECT(N);
  case ISD::SELECT_CC:          return visitSELECT_CC(N);
  case ISD::SETCC:              return visitSETCC(N);
  case ISD::SETCCE:             return visitSETCCE(N);
  case ISD::SIGN_EXTEND:        return visitSIGN_EXTEND(N);
  case ISD::ZERO_EXTEND:        return visitZERO_EXTEND(N);
  case ISD::ANY_EXTEND:         return visitANY_EXTEND(N);
  case ISD::SIGN_EXTEND_INREG:  return visitSIGN_EXTEND_INREG(N);
  case ISD::SIGN_EXTEND_VECTOR_INREG: return visitSIGN_EXTEND_VECTOR_INREG(N);
  case ISD::TRUNCATE:           return visitTRUNCATE(N);
  case ISD::BITCAST:            return visitBITCAST(N);
  case ISD::BUILD_PAIR:         return visitBUILD_PAIR(N);
  case ISD::FADD:               return visitFADD(N);
  case ISD::FSUB:               return visitFSUB(N);
  case ISD::FMUL:               return visitFMUL(N);
  case ISD::FMA:                return visitFMA(N);
  case ISD::FDIV:               return visitFDIV(N);
  case ISD::FREM:               return visitFREM(N);
  case ISD::FSQRT:              return visitFSQRT(N);
  case ISD::FCOPYSIGN:          return visitFCOPYSIGN(N);
  case ISD::SINT_TO_FP:         return visitSINT_TO_FP(N);
  case ISD::UINT_TO_FP:         return visitUINT_TO_FP(N);
  case ISD::FP_TO_SINT:         return visitFP_TO_SINT(N);
  case ISD::FP_TO_UINT:         return visitFP_TO_UINT(N);
  case ISD::FP_ROUND:           return visitFP_ROUND(N);
  case ISD::FP_ROUND_INREG:     return visitFP_ROUND_INREG(N);
  case ISD::FP_EXTEND:          return visitFP_EXTEND(N);
  case ISD::FNEG:               return visitFNEG(N);
  case ISD::FABS:               return visitFABS(N);
  case ISD::FFLOOR:             return visitFFLOOR(N);
  case ISD::FMINNUM:            return visitFMINNUM(N);
  case ISD::FMAXNUM:            return visitFMAXNUM(N);
  case ISD::FCEIL:              return visitFCEIL(N);
  case ISD::FTRUNC:             return visitFTRUNC(N);
  case ISD::BRCOND:             return visitBRCOND(N);
  case ISD::BR_CC:              return visitBR_CC(N);
  case ISD::LOAD:               return visitLOAD(N);
  case ISD::STORE:              return visitSTORE(N);
  case ISD::INSERT_VECTOR_ELT:  return visitINSERT_VECTOR_ELT(N);
  case ISD::EXTRACT_VECTOR_ELT: return visitEXTRACT_VECTOR_ELT(N);
  case ISD::BUILD_VECTOR:       return visitBUILD_VECTOR(N);
  case ISD::CONCAT_VECTORS:     return visitCONCAT_VECTORS(N);
  case ISD::EXTRACT_SUBVECTOR:  return visitEXTRACT_SUBVECTOR(N);
  case ISD::VECTOR_SHUFFLE:     return visitVECTOR_SHUFFLE(N);
  case ISD::SCALAR_TO_VECTOR:   return visitSCALAR_TO_VECTOR(N);
  case ISD::INSERT_SUBVECTOR:   return visitINSERT_SUBVECTOR(N);
  case ISD::MGATHER:            return visitMGATHER(N);
  case ISD::MLOAD:              return visitMLOAD(N);
  case ISD::MSCATTER:           return visitMSCATTER(N);
  case ISD::MSTORE:             return visitMSTORE(N);
  case ISD::FP_TO_FP16:         return visitFP_TO_FP16(N);
  case ISD::FP16_TO_FP:         return visitFP16_TO_FP(N);
  }
  return SDValue();
}

SDValue DAGCombiner::combine(SDNode *N) {
  SDValue RV = visit(N);

  // If nothing happened, try a target-specific DAG combine.
  if (!RV.getNode()) {
    assert(N->getOpcode() != ISD::DELETED_NODE &&
           "Node was deleted but visit returned NULL!");

    if (N->getOpcode() >= ISD::BUILTIN_OP_END ||
        TLI.hasTargetDAGCombine((ISD::NodeType)N->getOpcode())) {

      // Expose the DAG combiner to the target combiner impls.
      TargetLowering::DAGCombinerInfo
        DagCombineInfo(DAG, Level, false, this);

      RV = TLI.PerformDAGCombine(N, DagCombineInfo);
    }
  }

  // If nothing happened still, try promoting the operation.
  if (!RV.getNode()) {
    switch (N->getOpcode()) {
    default: break;
    case ISD::ADD:
    case ISD::SUB:
    case ISD::MUL:
    case ISD::AND:
    case ISD::OR:
    case ISD::XOR:
      RV = PromoteIntBinOp(SDValue(N, 0));
      break;
    case ISD::SHL:
    case ISD::SRA:
    case ISD::SRL:
      RV = PromoteIntShiftOp(SDValue(N, 0));
      break;
    case ISD::SIGN_EXTEND:
    case ISD::ZERO_EXTEND:
    case ISD::ANY_EXTEND:
      RV = PromoteExtend(SDValue(N, 0));
      break;
    case ISD::LOAD:
      if (PromoteLoad(SDValue(N, 0)))
        RV = SDValue(N, 0);
      break;
    }
  }

  // If N is a commutative binary node, try commuting it to enable more
  // sdisel CSE.
  if (!RV.getNode() && SelectionDAG::isCommutativeBinOp(N->getOpcode()) &&
      N->getNumValues() == 1) {
    SDValue N0 = N->getOperand(0);
    SDValue N1 = N->getOperand(1);

    // Constant operands are canonicalized to RHS.
    if (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1)) {
      SDValue Ops[] = {N1, N0};
      SDNode *CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops,
                                            N->getFlags());
      if (CSENode)
        return SDValue(CSENode, 0);
    }
  }

  return RV;
}

/// Given a node, return its input chain if it has one, otherwise return a null
/// sd operand.
static SDValue getInputChainForNode(SDNode *N) {
  if (unsigned NumOps = N->getNumOperands()) {
    if (N->getOperand(0).getValueType() == MVT::Other)
      return N->getOperand(0);
    if (N->getOperand(NumOps-1).getValueType() == MVT::Other)
      return N->getOperand(NumOps-1);
    for (unsigned i = 1; i < NumOps-1; ++i)
      if (N->getOperand(i).getValueType() == MVT::Other)
        return N->getOperand(i);
  }
  return SDValue();
}

SDValue DAGCombiner::visitTokenFactor(SDNode *N) {
  // If N has two operands, where one has an input chain equal to the other,
  // the 'other' chain is redundant.
  if (N->getNumOperands() == 2) {
    if (getInputChainForNode(N->getOperand(0).getNode()) == N->getOperand(1))
      return N->getOperand(0);
    if (getInputChainForNode(N->getOperand(1).getNode()) == N->getOperand(0))
      return N->getOperand(1);
  }

  SmallVector<SDNode *, 8> TFs;     // List of token factors to visit.
  SmallVector<SDValue, 8> Ops;    // Ops for replacing token factor.
  SmallPtrSet<SDNode*, 16> SeenOps;
  bool Changed = false;             // If we should replace this token factor.

  // Start out with this token factor.
  TFs.push_back(N);

  // Iterate through token factors.  The TFs grows when new token factors are
  // encountered.
  for (unsigned i = 0; i < TFs.size(); ++i) {
    SDNode *TF = TFs[i];

    // Check each of the operands.
    for (const SDValue &Op : TF->op_values()) {

      switch (Op.getOpcode()) {
      case ISD::EntryToken:
        // Entry tokens don't need to be added to the list. They are
        // redundant.
        Changed = true;
        break;

      case ISD::TokenFactor:
        if (Op.hasOneUse() &&
            std::find(TFs.begin(), TFs.end(), Op.getNode()) == TFs.end()) {
          // Queue up for processing.
          TFs.push_back(Op.getNode());
          // Clean up in case the token factor is removed.
          AddToWorklist(Op.getNode());
          Changed = true;
          break;
        }
        // Fall thru

      default:
        // Only add if it isn't already in the list.
        if (SeenOps.insert(Op.getNode()).second)
          Ops.push_back(Op);
        else
          Changed = true;
        break;
      }
    }
  }

  SDValue Result;

  // If we've changed things around then replace token factor.
  if (Changed) {
    if (Ops.empty()) {
      // The entry token is the only possible outcome.
      Result = DAG.getEntryNode();
    } else {
      // New and improved token factor.
      Result = DAG.getNode(ISD::TokenFactor, SDLoc(N), MVT::Other, Ops);
    }

    // Add users to worklist if AA is enabled, since it may introduce
    // a lot of new chained token factors while removing memory deps.
    bool UseAA = CombinerAA.getNumOccurrences() > 0 ? CombinerAA
      : DAG.getSubtarget().useAA();
    return CombineTo(N, Result, UseAA /*add to worklist*/);
  }

  return Result;
}

/// MERGE_VALUES can always be eliminated.
SDValue DAGCombiner::visitMERGE_VALUES(SDNode *N) {
  WorklistRemover DeadNodes(*this);
  // Replacing results may cause a different MERGE_VALUES to suddenly
  // be CSE'd with N, and carry its uses with it. Iterate until no
  // uses remain, to ensure that the node can be safely deleted.
  // First add the users of this node to the work list so that they
  // can be tried again once they have new operands.
  AddUsersToWorklist(N);
  do {
    for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
      DAG.ReplaceAllUsesOfValueWith(SDValue(N, i), N->getOperand(i));
  } while (!N->use_empty());
  deleteAndRecombine(N);
  return SDValue(N, 0);   // Return N so it doesn't get rechecked!
}

/// If \p N is a ContantSDNode with isOpaque() == false return it casted to a
/// ContantSDNode pointer else nullptr.
static ConstantSDNode *getAsNonOpaqueConstant(SDValue N) {
  ConstantSDNode *Const = dyn_cast<ConstantSDNode>(N);
  return Const != nullptr && !Const->isOpaque() ? Const : nullptr;
}

SDValue DAGCombiner::visitADD(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();

  // fold vector ops
  if (VT.isVector()) {
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

    // fold (add x, 0) -> x, vector edition
    if (ISD::isBuildVectorAllZeros(N1.getNode()))
      return N0;
    if (ISD::isBuildVectorAllZeros(N0.getNode()))
      return N1;
  }

  // fold (add x, undef) -> undef
  if (N0.getOpcode() == ISD::UNDEF)
    return N0;
  if (N1.getOpcode() == ISD::UNDEF)
    return N1;
  // fold (add c1, c2) -> c1+c2
  ConstantSDNode *N0C = getAsNonOpaqueConstant(N0);
  ConstantSDNode *N1C = getAsNonOpaqueConstant(N1);
  if (N0C && N1C)
    return DAG.FoldConstantArithmetic(ISD::ADD, SDLoc(N), VT, N0C, N1C);
  // canonicalize constant to RHS
  if (isConstantIntBuildVectorOrConstantInt(N0) &&
     !isConstantIntBuildVectorOrConstantInt(N1))
    return DAG.getNode(ISD::ADD, SDLoc(N), VT, N1, N0);
  // fold (add x, 0) -> x
  if (isNullConstant(N1))
    return N0;
  // fold (add Sym, c) -> Sym+c
  if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(N0))
    if (!LegalOperations && TLI.isOffsetFoldingLegal(GA) && N1C &&
        GA->getOpcode() == ISD::GlobalAddress)
      return DAG.getGlobalAddress(GA->getGlobal(), SDLoc(N1C), VT,
                                  GA->getOffset() +
                                    (uint64_t)N1C->getSExtValue());
  // fold ((c1-A)+c2) -> (c1+c2)-A
  if (N1C && N0.getOpcode() == ISD::SUB)
    if (ConstantSDNode *N0C = getAsNonOpaqueConstant(N0.getOperand(0))) {
      SDLoc DL(N);
      return DAG.getNode(ISD::SUB, DL, VT,
                         DAG.getConstant(N1C->getAPIntValue()+
                                         N0C->getAPIntValue(), DL, VT),
                         N0.getOperand(1));
    }
  // reassociate add
  if (SDValue RADD = ReassociateOps(ISD::ADD, SDLoc(N), N0, N1))
    return RADD;
  // fold ((0-A) + B) -> B-A
  if (N0.getOpcode() == ISD::SUB && isNullConstant(N0.getOperand(0)))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N1, N0.getOperand(1));
  // fold (A + (0-B)) -> A-B
  if (N1.getOpcode() == ISD::SUB && isNullConstant(N1.getOperand(0)))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N0, N1.getOperand(1));
  // fold (A+(B-A)) -> B
  if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(1))
    return N1.getOperand(0);
  // fold ((B-A)+A) -> B
  if (N0.getOpcode() == ISD::SUB && N1 == N0.getOperand(1))
    return N0.getOperand(0);
  // fold (A+(B-(A+C))) to (B-C)
  if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD &&
      N0 == N1.getOperand(1).getOperand(0))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N1.getOperand(0),
                       N1.getOperand(1).getOperand(1));
  // fold (A+(B-(C+A))) to (B-C)
  if (N1.getOpcode() == ISD::SUB && N1.getOperand(1).getOpcode() == ISD::ADD &&
      N0 == N1.getOperand(1).getOperand(1))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N1.getOperand(0),
                       N1.getOperand(1).getOperand(0));
  // fold (A+((B-A)+or-C)) to (B+or-C)
  if ((N1.getOpcode() == ISD::SUB || N1.getOpcode() == ISD::ADD) &&
      N1.getOperand(0).getOpcode() == ISD::SUB &&
      N0 == N1.getOperand(0).getOperand(1))
    return DAG.getNode(N1.getOpcode(), SDLoc(N), VT,
                       N1.getOperand(0).getOperand(0), N1.getOperand(1));

  // fold (A-B)+(C-D) to (A+C)-(B+D) when A or C is constant
  if (N0.getOpcode() == ISD::SUB && N1.getOpcode() == ISD::SUB) {
    SDValue N00 = N0.getOperand(0);
    SDValue N01 = N0.getOperand(1);
    SDValue N10 = N1.getOperand(0);
    SDValue N11 = N1.getOperand(1);

    if (isa<ConstantSDNode>(N00) || isa<ConstantSDNode>(N10))
      return DAG.getNode(ISD::SUB, SDLoc(N), VT,
                         DAG.getNode(ISD::ADD, SDLoc(N0), VT, N00, N10),
                         DAG.getNode(ISD::ADD, SDLoc(N1), VT, N01, N11));
  }

  if (!VT.isVector() && SimplifyDemandedBits(SDValue(N, 0)))
    return SDValue(N, 0);

  // fold (a+b) -> (a|b) iff a and b share no bits.
  if ((!LegalOperations || TLI.isOperationLegal(ISD::OR, VT)) &&
      VT.isInteger() && !VT.isVector() && DAG.haveNoCommonBitsSet(N0, N1))
    return DAG.getNode(ISD::OR, SDLoc(N), VT, N0, N1);

  // fold (add x, shl(0 - y, n)) -> sub(x, shl(y, n))
  if (N1.getOpcode() == ISD::SHL && N1.getOperand(0).getOpcode() == ISD::SUB &&
      isNullConstant(N1.getOperand(0).getOperand(0)))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N0,
                       DAG.getNode(ISD::SHL, SDLoc(N), VT,
                                   N1.getOperand(0).getOperand(1),
                                   N1.getOperand(1)));
  if (N0.getOpcode() == ISD::SHL && N0.getOperand(0).getOpcode() == ISD::SUB &&
      isNullConstant(N0.getOperand(0).getOperand(0)))
    return DAG.getNode(ISD::SUB, SDLoc(N), VT, N1,
                       DAG.getNode(ISD::SHL, SDLoc(N), VT,
                                   N0.getOperand(0).getOperand(1),
                                   N0.getOperand(1)));

  if (N1.getOpcode() == ISD::AND) {
    SDValue AndOp0 = N1.getOperand(0);
    unsigned NumSignBits = DAG.ComputeNumSignBits(AndOp0);
    unsigned DestBits = VT.getScalarType().getSizeInBits();

    // (add z, (and (sbbl x, x), 1)) -> (sub z, (sbbl x, x))
    // and similar xforms where the inner op is either ~0 or 0.
    if (NumSignBits == DestBits && isOneConstant(N1->getOperand(1))) {
      SDLoc DL(N);
      return DAG.getNode(ISD::SUB, DL, VT, N->getOperand(0), AndOp0);
    }
  }

  // add (sext i1), X -> sub X, (zext i1)
  if (N0.getOpcode() == ISD::SIGN_EXTEND &&
      N0.getOperand(0).getValueType() == MVT::i1 &&
      !TLI.isOperationLegal(ISD::SIGN_EXTEND, MVT::i1)) {
    SDLoc DL(N);
    SDValue ZExt = DAG.getNode(ISD::ZERO_EXTEND, DL, VT, N0.getOperand(0));
    return DAG.getNode(ISD::SUB, DL, VT, N1, ZExt);
  }

  // add X, (sextinreg Y i1) -> sub X, (and Y 1)
  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
    VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
    if (TN->getVT() == MVT::i1) {
      SDLoc DL(N);
      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
                                 DAG.getConstant(1, DL, VT));
      return DAG.getNode(ISD::SUB, DL, VT, N0, ZExt);
    }
  }

  return SDValue();
}

SDValue DAGCombiner::visitADDC(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();

  // If the flag result is dead, turn this into an ADD.
  if (!N->hasAnyUseOfValue(1))
    return CombineTo(N, DAG.getNode(ISD::ADD, SDLoc(N), VT, N0, N1),
                     DAG.getNode(ISD::CARRY_FALSE,
                                 SDLoc(N), MVT::Glue));

  // canonicalize constant to RHS.
  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
  if (N0C && !N1C)
    return DAG.getNode(ISD::ADDC, SDLoc(N), N->getVTList(), N1, N0);

  // fold (addc x, 0) -> x + no carry out
  if (isNullConstant(N1))
    return CombineTo(N, N0, DAG.getNode(ISD::CARRY_FALSE,
                                        SDLoc(N), MVT::Glue));

  // fold (addc a, b) -> (or a, b), CARRY_FALSE iff a and b share no bits.
  APInt LHSZero, LHSOne;
  APInt RHSZero, RHSOne;
  DAG.computeKnownBits(N0, LHSZero, LHSOne);

  if (LHSZero.getBoolValue()) {
    DAG.computeKnownBits(N1, RHSZero, RHSOne);

    // If all possibly-set bits on the LHS are clear on the RHS, return an OR.
    // If all possibly-set bits on the RHS are clear on the LHS, return an OR.
    if ((RHSZero & ~LHSZero) == ~LHSZero || (LHSZero & ~RHSZero) == ~RHSZero)
      return CombineTo(N, DAG.getNode(ISD::OR, SDLoc(N), VT, N0, N1),
                       DAG.getNode(ISD::CARRY_FALSE,
                                   SDLoc(N), MVT::Glue));
  }

  return SDValue();
}

SDValue DAGCombiner::visitADDE(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  SDValue CarryIn = N->getOperand(2);

  // canonicalize constant to RHS
  ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
  ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
  if (N0C && !N1C)
    return DAG.getNode(ISD::ADDE, SDLoc(N), N->getVTList(),
                       N1, N0, CarryIn);

  // fold (adde x, y, false) -> (addc x, y)
  if (CarryIn.getOpcode() == ISD::CARRY_FALSE)
    return DAG.getNode(ISD::ADDC, SDLoc(N), N->getVTList(), N0, N1);

  return SDValue();
}

// Since it may not be valid to emit a fold to zero for vector initializers
// check if we can before folding.
static SDValue tryFoldToZero(SDLoc DL, const TargetLowering &TLI, EVT VT,
                             SelectionDAG &DAG,
                             bool LegalOperations, bool LegalTypes) {
  if (!VT.isVector())
    return DAG.getConstant(0, DL, VT);
  if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT))
    return DAG.getConstant(0, DL, VT);
  return SDValue();
}

SDValue DAGCombiner::visitSUB(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();

  // fold vector ops
  if (VT.isVector()) {
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

    // fold (sub x, 0) -> x, vector edition
    if (ISD::isBuildVectorAllZeros(N1.getNode()))
      return N0;
  }

  // fold (sub x, x) -> 0
  // FIXME: Refactor this and xor and other similar operations together.
  if (N0 == N1)
    return tryFoldToZero(SDLoc(N), TLI, VT, DAG, LegalOperations, LegalTypes);
  // fold (sub c1, c2) -> c1-c2
  ConstantSDNode *N0C = getAsNonOpaqueConstant(N0);
  ConstantSDNode *N1C = getAsNonOpaqueConstant(N1);
  if (N0C && N1C)
    return DAG.FoldConstantArithmetic(ISD::SUB, SDLoc(N), VT, N0C, N1C);
  // fold (sub x, c) -> (add x, -c)
  if (N1C) {
    SDLoc DL(N);
    return DAG.getNode(ISD::ADD, DL, VT, N0,
                       DAG.getConstant(-N1C->getAPIntValue(), DL, VT));
  }
  // Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1)
  if (isAllOnesConstant(N0))
    return DAG.getNode(ISD::XOR, SDLoc(N), VT, N1, N0);
  // fold A-(A-B) -> B
  if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(0))
    return N1.getOperand(1);
  // fold (A+B)-A -> B
  if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1)
    return N0.getOperand(1);
  // fold (A+B)-B -> A
  if (N0.getOpcode() == ISD::ADD && N0.getOperand(1) == N1)
    return N0.getOperand(0);
  // fold C2-(A+C1) -> (C2-C1)-A
  ConstantSDNode *N1C1 = N1.getOpcode() != ISD::ADD ? nullptr :
    dyn_cast<ConstantSDNode>(N1.getOperand(1).getNode());
  if (N1.getOpcode() == ISD::ADD && N0C && N1C1) {
    SDLoc DL(N);
    SDValue NewC = DAG.getConstant(N0C->getAPIntValue() - N1C1->getAPIntValue(),
                                   DL, VT);
    return DAG.getNode(ISD::SUB, DL, VT, NewC,
                       N1.getOperand(0));
  }
  // fold ((A+(B+or-C))-B) -> A+or-C
  if (N0.getOpcode() == ISD::ADD &&
      (N0.getOperand(1).getOpcode() == ISD::SUB ||
       N0.getOperand(1).getOpcode() == ISD::ADD) &&
      N0.getOperand(1).getOperand(0) == N1)
    return DAG.getNode(N0.getOperand(1).getOpcode(), SDLoc(N), VT,
                       N0.getOperand(0), N0.getOperand(1).getOperand(1));
  // fold ((A+(C+B))-B) -> A+C
  if (N0.getOpcode() == ISD::ADD &&
      N0.getOperand(1).getOpcode() == ISD::ADD &&
      N0.getOperand(1).getOperand(1) == N1)
    return DAG.getNode(ISD::ADD, SDLoc(N), VT,
                       N0.getOperand(0), N0.getOperand(1).getOperand(0));
  // fold ((A-(B-C))-C) -> A-B
  if (N0.getOpcode() == ISD::SUB &&
      N0.getOperand(1).getOpcode() == ISD::SUB &&
      N0.getOperand(1).getOperand(1) == N1)
    return DAG.getNode(ISD::SUB, SDLoc(N), VT,
                       N0.getOperand(0), N0.getOperand(1).getOperand(0));

  // If either operand of a sub is undef, the result is undef
  if (N0.getOpcode() == ISD::UNDEF)
    return N0;
  if (N1.getOpcode() == ISD::UNDEF)
    return N1;

  // If the relocation model supports it, consider symbol offsets.
  if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(N0))
    if (!LegalOperations && TLI.isOffsetFoldingLegal(GA)) {
      // fold (sub Sym, c) -> Sym-c
      if (N1C && GA->getOpcode() == ISD::GlobalAddress)
        return DAG.getGlobalAddress(GA->getGlobal(), SDLoc(N1C), VT,
                                    GA->getOffset() -
                                      (uint64_t)N1C->getSExtValue());
      // fold (sub Sym+c1, Sym+c2) -> c1-c2
      if (GlobalAddressSDNode *GB = dyn_cast<GlobalAddressSDNode>(N1))
        if (GA->getGlobal() == GB->getGlobal())
          return DAG.getConstant((uint64_t)GA->getOffset() - GB->getOffset(),
                                 SDLoc(N), VT);
    }

  // sub X, (sextinreg Y i1) -> add X, (and Y 1)
  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
    VTSDNode *TN = cast<VTSDNode>(N1.getOperand(1));
    if (TN->getVT() == MVT::i1) {
      SDLoc DL(N);
      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
                                 DAG.getConstant(1, DL, VT));
      return DAG.getNode(ISD::ADD, DL, VT, N0, ZExt);
    }
  }

  return SDValue();
}

SDValue DAGCombiner::visitSUBC(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();
  SDLoc DL(N);

  // If the flag result is dead, turn this into an SUB.
  if (!N->hasAnyUseOfValue(1))
    return CombineTo(N, DAG.getNode(ISD::SUB, DL, VT, N0, N1),
                     DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));

  // fold (subc x, x) -> 0 + no borrow
  if (N0 == N1)
    return CombineTo(N, DAG.getConstant(0, DL, VT),
                     DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));

  // fold (subc x, 0) -> x + no borrow
  if (isNullConstant(N1))
    return CombineTo(N, N0, DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));

  // Canonicalize (sub -1, x) -> ~x, i.e. (xor x, -1) + no borrow
  if (isAllOnesConstant(N0))
    return CombineTo(N, DAG.getNode(ISD::XOR, DL, VT, N1, N0),
                     DAG.getNode(ISD::CARRY_FALSE, DL, MVT::Glue));

  return SDValue();
}

SDValue DAGCombiner::visitSUBE(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  SDValue CarryIn = N->getOperand(2);

  // fold (sube x, y, false) -> (subc x, y)
  if (CarryIn.getOpcode() == ISD::CARRY_FALSE)
    return DAG.getNode(ISD::SUBC, SDLoc(N), N->getVTList(), N0, N1);

  return SDValue();
}

SDValue DAGCombiner::visitMUL(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();

  // fold (mul x, undef) -> 0
  if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, SDLoc(N), VT);

  bool N0IsConst = false;
  bool N1IsConst = false;
  bool N1IsOpaqueConst = false;
  bool N0IsOpaqueConst = false;
  APInt ConstValue0, ConstValue1;
  // fold vector ops
  if (VT.isVector()) {
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

    N0IsConst = isConstantSplatVector(N0.getNode(), ConstValue0);
    N1IsConst = isConstantSplatVector(N1.getNode(), ConstValue1);
  } else {
    N0IsConst = isa<ConstantSDNode>(N0);
    if (N0IsConst) {
      ConstValue0 = cast<ConstantSDNode>(N0)->getAPIntValue();
      N0IsOpaqueConst = cast<ConstantSDNode>(N0)->isOpaque();
    }
    N1IsConst = isa<ConstantSDNode>(N1);
    if (N1IsConst) {
      ConstValue1 = cast<ConstantSDNode>(N1)->getAPIntValue();
      N1IsOpaqueConst = cast<ConstantSDNode>(N1)->isOpaque();
    }
  }

  // fold (mul c1, c2) -> c1*c2
  if (N0IsConst && N1IsConst && !N0IsOpaqueConst && !N1IsOpaqueConst)
    return DAG.FoldConstantArithmetic(ISD::MUL, SDLoc(N), VT,
                                      N0.getNode(), N1.getNode());

  // canonicalize constant to RHS (vector doesn't have to splat)
  if (isConstantIntBuildVectorOrConstantInt(N0) &&
     !isConstantIntBuildVectorOrConstantInt(N1))
    return DAG.getNode(ISD::MUL, SDLoc(N), VT, N1, N0);
  // fold (mul x, 0) -> 0
  if (N1IsConst && ConstValue1 == 0)
    return N1;
  // We require a splat of the entire scalar bit width for non-contiguous
  // bit patterns.
  bool IsFullSplat =
    ConstValue1.getBitWidth() == VT.getScalarType().getSizeInBits();
  // fold (mul x, 1) -> x
  if (N1IsConst && ConstValue1 == 1 && IsFullSplat)
    return N0;
  // fold (mul x, -1) -> 0-x
  if (N1IsConst && ConstValue1.isAllOnesValue()) {
    SDLoc DL(N);
    return DAG.getNode(ISD::SUB, DL, VT,
                       DAG.getConstant(0, DL, VT), N0);
  }
  // fold (mul x, (1 << c)) -> x << c
  if (N1IsConst && !N1IsOpaqueConst && ConstValue1.isPowerOf2() &&
      IsFullSplat) {
    SDLoc DL(N);
    return DAG.getNode(ISD::SHL, DL, VT, N0,
                       DAG.getConstant(ConstValue1.logBase2(), DL,
                                       getShiftAmountTy(N0.getValueType())));
  }
  // fold (mul x, -(1 << c)) -> -(x << c) or (-x) << c
  if (N1IsConst && !N1IsOpaqueConst && (-ConstValue1).isPowerOf2() &&
      IsFullSplat) {
    unsigned Log2Val = (-ConstValue1).logBase2();
    SDLoc DL(N);
    // FIXME: If the input is something that is easily negated (e.g. a
    // single-use add), we should put the negate there.
    return DAG.getNode(ISD::SUB, DL, VT,
                       DAG.getConstant(0, DL, VT),
                       DAG.getNode(ISD::SHL, DL, VT, N0,
                            DAG.getConstant(Log2Val, DL,
                                      getShiftAmountTy(N0.getValueType()))));
  }

  APInt Val;
  // (mul (shl X, c1), c2) -> (mul X, c2 << c1)
  if (N1IsConst && N0.getOpcode() == ISD::SHL &&
      (isConstantSplatVector(N0.getOperand(1).getNode(), Val) ||
                     isa<ConstantSDNode>(N0.getOperand(1)))) {
    SDValue C3 = DAG.getNode(ISD::SHL, SDLoc(N), VT,
                             N1, N0.getOperand(1));
    AddToWorklist(C3.getNode());
    return DAG.getNode(ISD::MUL, SDLoc(N), VT,
                       N0.getOperand(0), C3);
  }

  // Change (mul (shl X, C), Y) -> (shl (mul X, Y), C) when the shift has one
  // use.
  {
    SDValue Sh(nullptr,0), Y(nullptr,0);
    // Check for both (mul (shl X, C), Y)  and  (mul Y, (shl X, C)).
    if (N0.getOpcode() == ISD::SHL &&
        (isConstantSplatVector(N0.getOperand(1).getNode(), Val) ||
                       isa<ConstantSDNode>(N0.getOperand(1))) &&
        N0.getNode()->hasOneUse()) {
      Sh = N0; Y = N1;
    } else if (N1.getOpcode() == ISD::SHL &&
               isa<ConstantSDNode>(N1.getOperand(1)) &&
               N1.getNode()->hasOneUse()) {
      Sh = N1; Y = N0;
    }

    if (Sh.getNode()) {
      SDValue Mul = DAG.getNode(ISD::MUL, SDLoc(N), VT,
                                Sh.getOperand(0), Y);
      return DAG.getNode(ISD::SHL, SDLoc(N), VT,
                         Mul, Sh.getOperand(1));
    }
  }

  // fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2)
  if (isConstantIntBuildVectorOrConstantInt(N1) &&
      N0.getOpcode() == ISD::ADD &&
      isConstantIntBuildVectorOrConstantInt(N0.getOperand(1)) &&
      isMulAddWithConstProfitable(N, N0, N1))
      return DAG.getNode(ISD::ADD, SDLoc(N), VT,
                         DAG.getNode(ISD::MUL, SDLoc(N0), VT,
                                     N0.getOperand(0), N1),
                         DAG.getNode(ISD::MUL, SDLoc(N1), VT,
                                     N0.getOperand(1), N1));

  // reassociate mul
  if (SDValue RMUL = ReassociateOps(ISD::MUL, SDLoc(N), N0, N1))
    return RMUL;

  return SDValue();
}

/// Return true if divmod libcall is available.
static bool isDivRemLibcallAvailable(SDNode *Node, bool isSigned,
                                     const TargetLowering &TLI) {
  RTLIB::Libcall LC;
  switch (Node->getSimpleValueType(0).SimpleTy) {
  default: return false; // No libcall for vector types.
  case MVT::i8:   LC= isSigned ? RTLIB::SDIVREM_I8  : RTLIB::UDIVREM_I8;  break;
  case MVT::i16:  LC= isSigned ? RTLIB::SDIVREM_I16 : RTLIB::UDIVREM_I16; break;
  case MVT::i32:  LC= isSigned ? RTLIB::SDIVREM_I32 : RTLIB::UDIVREM_I32; break;
  case MVT::i64:  LC= isSigned ? RTLIB::SDIVREM_I64 : RTLIB::UDIVREM_I64; break;
  case MVT::i128: LC= isSigned ? RTLIB::SDIVREM_I128:RTLIB::UDIVREM_I128; break;
  }

  return TLI.getLibcallName(LC) != nullptr;
}

/// Issue divrem if both quotient and remainder are needed.
SDValue DAGCombiner::useDivRem(SDNode *Node) {
  if (Node->use_empty())
    return SDValue(); // This is a dead node, leave it alone.

  EVT VT = Node->getValueType(0);
  if (!TLI.isTypeLegal(VT))
    return SDValue();

  unsigned Opcode = Node->getOpcode();
  bool isSigned = (Opcode == ISD::SDIV) || (Opcode == ISD::SREM);

  unsigned DivRemOpc = isSigned ? ISD::SDIVREM : ISD::UDIVREM;
  // If DIVREM is going to get expanded into a libcall,
  // but there is no libcall available, then don't combine.
  if (!TLI.isOperationLegalOrCustom(DivRemOpc, VT) &&
      !isDivRemLibcallAvailable(Node, isSigned, TLI))
    return SDValue();

  // If div is legal, it's better to do the normal expansion
  unsigned OtherOpcode = 0;
  if ((Opcode == ISD::SDIV) || (Opcode == ISD::UDIV)) {
    OtherOpcode = isSigned ? ISD::SREM : ISD::UREM;
    if (TLI.isOperationLegalOrCustom(Opcode, VT))
      return SDValue();
  } else {
    OtherOpcode = isSigned ? ISD::SDIV : ISD::UDIV;
    if (TLI.isOperationLegalOrCustom(OtherOpcode, VT))
      return SDValue();
  }

  SDValue Op0 = Node->getOperand(0);
  SDValue Op1 = Node->getOperand(1);
  SDValue combined;
  for (SDNode::use_iterator UI = Op0.getNode()->use_begin(),
         UE = Op0.getNode()->use_end(); UI != UE; ++UI) {
    SDNode *User = *UI;
    if (User == Node || User->use_empty())
      continue;
    // Convert the other matching node(s), too;
    // otherwise, the DIVREM may get target-legalized into something
    // target-specific that we won't be able to recognize.
    unsigned UserOpc = User->getOpcode();
    if ((UserOpc == Opcode || UserOpc == OtherOpcode || UserOpc == DivRemOpc) &&
        User->getOperand(0) == Op0 &&
        User->getOperand(1) == Op1) {
      if (!combined) {
        if (UserOpc == OtherOpcode) {
          SDVTList VTs = DAG.getVTList(VT, VT);
          combined = DAG.getNode(DivRemOpc, SDLoc(Node), VTs, Op0, Op1);
        } else if (UserOpc == DivRemOpc) {
          combined = SDValue(User, 0);
        } else {
          assert(UserOpc == Opcode);
          continue;
        }
      }
      if (UserOpc == ISD::SDIV || UserOpc == ISD::UDIV)
        CombineTo(User, combined);
      else if (UserOpc == ISD::SREM || UserOpc == ISD::UREM)
        CombineTo(User, combined.getValue(1));
    }
  }
  return combined;
}

SDValue DAGCombiner::visitSDIV(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N->getValueType(0);

  // fold vector ops
  if (VT.isVector())
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

  SDLoc DL(N);

  // fold (sdiv c1, c2) -> c1/c2
  ConstantSDNode *N0C = isConstOrConstSplat(N0);
  ConstantSDNode *N1C = isConstOrConstSplat(N1);
  if (N0C && N1C && !N0C->isOpaque() && !N1C->isOpaque())
    return DAG.FoldConstantArithmetic(ISD::SDIV, DL, VT, N0C, N1C);
  // fold (sdiv X, 1) -> X
  if (N1C && N1C->isOne())
    return N0;
  // fold (sdiv X, -1) -> 0-X
  if (N1C && N1C->isAllOnesValue())
    return DAG.getNode(ISD::SUB, DL, VT,
                       DAG.getConstant(0, DL, VT), N0);

  // If we know the sign bits of both operands are zero, strength reduce to a
  // udiv instead.  Handles (X&15) /s 4 -> X&15 >> 2
  if (!VT.isVector()) {
    if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
      return DAG.getNode(ISD::UDIV, DL, N1.getValueType(), N0, N1);
  }

  // fold (sdiv X, pow2) -> simple ops after legalize
  // FIXME: We check for the exact bit here because the generic lowering gives
  // better results in that case. The target-specific lowering should learn how
  // to handle exact sdivs efficiently.
  if (N1C && !N1C->isNullValue() && !N1C->isOpaque() &&
      !cast<BinaryWithFlagsSDNode>(N)->Flags.hasExact() &&
      (N1C->getAPIntValue().isPowerOf2() ||
       (-N1C->getAPIntValue()).isPowerOf2())) {
    // Target-specific implementation of sdiv x, pow2.
    if (SDValue Res = BuildSDIVPow2(N))
      return Res;

    unsigned lg2 = N1C->getAPIntValue().countTrailingZeros();

    // Splat the sign bit into the register
    SDValue SGN =
        DAG.getNode(ISD::SRA, DL, VT, N0,
                    DAG.getConstant(VT.getScalarSizeInBits() - 1, DL,
                                    getShiftAmountTy(N0.getValueType())));
    AddToWorklist(SGN.getNode());

    // Add (N0 < 0) ? abs2 - 1 : 0;
    SDValue SRL =
        DAG.getNode(ISD::SRL, DL, VT, SGN,
                    DAG.getConstant(VT.getScalarSizeInBits() - lg2, DL,
                                    getShiftAmountTy(SGN.getValueType())));
    SDValue ADD = DAG.getNode(ISD::ADD, DL, VT, N0, SRL);
    AddToWorklist(SRL.getNode());
    AddToWorklist(ADD.getNode());    // Divide by pow2
    SDValue SRA = DAG.getNode(ISD::SRA, DL, VT, ADD,
                  DAG.getConstant(lg2, DL,
                                  getShiftAmountTy(ADD.getValueType())));

    // If we're dividing by a positive value, we're done.  Otherwise, we must
    // negate the result.
    if (N1C->getAPIntValue().isNonNegative())
      return SRA;

    AddToWorklist(SRA.getNode());
    return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), SRA);
  }

  // If integer divide is expensive and we satisfy the requirements, emit an
  // alternate sequence.  Targets may check function attributes for size/speed
  // trade-offs.
  AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();
  if (N1C && !TLI.isIntDivCheap(N->getValueType(0), Attr))
    if (SDValue Op = BuildSDIV(N))
      return Op;

  // sdiv, srem -> sdivrem
  // If the divisor is constant, then return DIVREM only if isIntDivCheap() is true.
  // Otherwise, we break the simplification logic in visitREM().
  if (!N1C || TLI.isIntDivCheap(N->getValueType(0), Attr))
    if (SDValue DivRem = useDivRem(N))
        return DivRem;

  // undef / X -> 0
  if (N0.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, DL, VT);
  // X / undef -> undef
  if (N1.getOpcode() == ISD::UNDEF)
    return N1;

  return SDValue();
}

SDValue DAGCombiner::visitUDIV(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N->getValueType(0);

  // fold vector ops
  if (VT.isVector())
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

  SDLoc DL(N);

  // fold (udiv c1, c2) -> c1/c2
  ConstantSDNode *N0C = isConstOrConstSplat(N0);
  ConstantSDNode *N1C = isConstOrConstSplat(N1);
  if (N0C && N1C)
    if (SDValue Folded = DAG.FoldConstantArithmetic(ISD::UDIV, DL, VT,
                                                    N0C, N1C))
      return Folded;
  // fold (udiv x, (1 << c)) -> x >>u c
  if (N1C && !N1C->isOpaque() && N1C->getAPIntValue().isPowerOf2())
    return DAG.getNode(ISD::SRL, DL, VT, N0,
                       DAG.getConstant(N1C->getAPIntValue().logBase2(), DL,
                                       getShiftAmountTy(N0.getValueType())));

  // fold (udiv x, (shl c, y)) -> x >>u (log2(c)+y) iff c is power of 2
  if (N1.getOpcode() == ISD::SHL) {
    if (ConstantSDNode *SHC = getAsNonOpaqueConstant(N1.getOperand(0))) {
      if (SHC->getAPIntValue().isPowerOf2()) {
        EVT ADDVT = N1.getOperand(1).getValueType();
        SDValue Add = DAG.getNode(ISD::ADD, DL, ADDVT,
                                  N1.getOperand(1),
                                  DAG.getConstant(SHC->getAPIntValue()
                                                                  .logBase2(),
                                                  DL, ADDVT));
        AddToWorklist(Add.getNode());
        return DAG.getNode(ISD::SRL, DL, VT, N0, Add);
      }
    }
  }

  // fold (udiv x, c) -> alternate
  AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();
  if (N1C && !TLI.isIntDivCheap(N->getValueType(0), Attr))
    if (SDValue Op = BuildUDIV(N))
      return Op;

  // sdiv, srem -> sdivrem
  // If the divisor is constant, then return DIVREM only if isIntDivCheap() is true.
  // Otherwise, we break the simplification logic in visitREM().
  if (!N1C || TLI.isIntDivCheap(N->getValueType(0), Attr))
    if (SDValue DivRem = useDivRem(N))
        return DivRem;

  // undef / X -> 0
  if (N0.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, DL, VT);
  // X / undef -> undef
  if (N1.getOpcode() == ISD::UNDEF)
    return N1;

  return SDValue();
}

// handles ISD::SREM and ISD::UREM
SDValue DAGCombiner::visitREM(SDNode *N) {
  unsigned Opcode = N->getOpcode();
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N->getValueType(0);
  bool isSigned = (Opcode == ISD::SREM);
  SDLoc DL(N);

  // fold (rem c1, c2) -> c1%c2
  ConstantSDNode *N0C = isConstOrConstSplat(N0);
  ConstantSDNode *N1C = isConstOrConstSplat(N1);
  if (N0C && N1C)
    if (SDValue Folded = DAG.FoldConstantArithmetic(Opcode, DL, VT, N0C, N1C))
      return Folded;

  if (isSigned) {
    // If we know the sign bits of both operands are zero, strength reduce to a
    // urem instead.  Handles (X & 0x0FFFFFFF) %s 16 -> X&15
    if (!VT.isVector()) {
      if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
        return DAG.getNode(ISD::UREM, DL, VT, N0, N1);
    }
  } else {
    // fold (urem x, pow2) -> (and x, pow2-1)
    if (N1C && !N1C->isNullValue() && !N1C->isOpaque() &&
        N1C->getAPIntValue().isPowerOf2()) {
      return DAG.getNode(ISD::AND, DL, VT, N0,
                         DAG.getConstant(N1C->getAPIntValue() - 1, DL, VT));
    }
    // fold (urem x, (shl pow2, y)) -> (and x, (add (shl pow2, y), -1))
    if (N1.getOpcode() == ISD::SHL) {
      if (ConstantSDNode *SHC = getAsNonOpaqueConstant(N1.getOperand(0))) {
        if (SHC->getAPIntValue().isPowerOf2()) {
          SDValue Add =
            DAG.getNode(ISD::ADD, DL, VT, N1,
                 DAG.getConstant(APInt::getAllOnesValue(VT.getSizeInBits()), DL,
                                 VT));
          AddToWorklist(Add.getNode());
          return DAG.getNode(ISD::AND, DL, VT, N0, Add);
        }
      }
    }
  }

  AttributeSet Attr = DAG.getMachineFunction().getFunction()->getAttributes();

  // If X/C can be simplified by the division-by-constant logic, lower
  // X%C to the equivalent of X-X/C*C.
  // To avoid mangling nodes, this simplification requires that the combine()
  // call for the speculative DIV must not cause a DIVREM conversion.  We guard
  // against this by skipping the simplification if isIntDivCheap().  When
  // div is not cheap, combine will not return a DIVREM.  Regardless,
  // checking cheapness here makes sense since the simplification results in
  // fatter code.
  if (N1C && !N1C->isNullValue() && !TLI.isIntDivCheap(VT, Attr)) {
    unsigned DivOpcode = isSigned ? ISD::SDIV : ISD::UDIV;
    SDValue Div = DAG.getNode(DivOpcode, DL, VT, N0, N1);
    AddToWorklist(Div.getNode());
    SDValue OptimizedDiv = combine(Div.getNode());
    if (OptimizedDiv.getNode() && OptimizedDiv.getNode() != Div.getNode()) {
      assert((OptimizedDiv.getOpcode() != ISD::UDIVREM) &&
             (OptimizedDiv.getOpcode() != ISD::SDIVREM));
      SDValue Mul = DAG.getNode(ISD::MUL, DL, VT, OptimizedDiv, N1);
      SDValue Sub = DAG.getNode(ISD::SUB, DL, VT, N0, Mul);
      AddToWorklist(Mul.getNode());
      return Sub;
    }
  }

  // sdiv, srem -> sdivrem
  if (SDValue DivRem = useDivRem(N))
    return DivRem.getValue(1);

  // undef % X -> 0
  if (N0.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, DL, VT);
  // X % undef -> undef
  if (N1.getOpcode() == ISD::UNDEF)
    return N1;

  return SDValue();
}

SDValue DAGCombiner::visitMULHS(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N->getValueType(0);
  SDLoc DL(N);

  // fold (mulhs x, 0) -> 0
  if (isNullConstant(N1))
    return N1;
  // fold (mulhs x, 1) -> (sra x, size(x)-1)
  if (isOneConstant(N1)) {
    SDLoc DL(N);
    return DAG.getNode(ISD::SRA, DL, N0.getValueType(), N0,
                       DAG.getConstant(N0.getValueType().getSizeInBits() - 1,
                                       DL,
                                       getShiftAmountTy(N0.getValueType())));
  }
  // fold (mulhs x, undef) -> 0
  if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, SDLoc(N), VT);

  // If the type twice as wide is legal, transform the mulhs to a wider multiply
  // plus a shift.
  if (VT.isSimple() && !VT.isVector()) {
    MVT Simple = VT.getSimpleVT();
    unsigned SimpleSize = Simple.getSizeInBits();
    EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
    if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
      N0 = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N0);
      N1 = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N1);
      N1 = DAG.getNode(ISD::MUL, DL, NewVT, N0, N1);
      N1 = DAG.getNode(ISD::SRL, DL, NewVT, N1,
            DAG.getConstant(SimpleSize, DL,
                            getShiftAmountTy(N1.getValueType())));
      return DAG.getNode(ISD::TRUNCATE, DL, VT, N1);
    }
  }

  return SDValue();
}

SDValue DAGCombiner::visitMULHU(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N->getValueType(0);
  SDLoc DL(N);

  // fold (mulhu x, 0) -> 0
  if (isNullConstant(N1))
    return N1;
  // fold (mulhu x, 1) -> 0
  if (isOneConstant(N1))
    return DAG.getConstant(0, DL, N0.getValueType());
  // fold (mulhu x, undef) -> 0
  if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, DL, VT);

  // If the type twice as wide is legal, transform the mulhu to a wider multiply
  // plus a shift.
  if (VT.isSimple() && !VT.isVector()) {
    MVT Simple = VT.getSimpleVT();
    unsigned SimpleSize = Simple.getSizeInBits();
    EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
    if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
      N0 = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N0);
      N1 = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N1);
      N1 = DAG.getNode(ISD::MUL, DL, NewVT, N0, N1);
      N1 = DAG.getNode(ISD::SRL, DL, NewVT, N1,
            DAG.getConstant(SimpleSize, DL,
                            getShiftAmountTy(N1.getValueType())));
      return DAG.getNode(ISD::TRUNCATE, DL, VT, N1);
    }
  }

  return SDValue();
}

/// Perform optimizations common to nodes that compute two values. LoOp and HiOp
/// give the opcodes for the two computations that are being performed. Return
/// true if a simplification was made.
SDValue DAGCombiner::SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
                                                unsigned HiOp) {
  // If the high half is not needed, just compute the low half.
  bool HiExists = N->hasAnyUseOfValue(1);
  if (!HiExists &&
      (!LegalOperations ||
       TLI.isOperationLegalOrCustom(LoOp, N->getValueType(0)))) {
    SDValue Res = DAG.getNode(LoOp, SDLoc(N), N->getValueType(0), N->ops());
    return CombineTo(N, Res, Res);
  }

  // If the low half is not needed, just compute the high half.
  bool LoExists = N->hasAnyUseOfValue(0);
  if (!LoExists &&
      (!LegalOperations ||
       TLI.isOperationLegal(HiOp, N->getValueType(1)))) {
    SDValue Res = DAG.getNode(HiOp, SDLoc(N), N->getValueType(1), N->ops());
    return CombineTo(N, Res, Res);
  }

  // If both halves are used, return as it is.
  if (LoExists && HiExists)
    return SDValue();

  // If the two computed results can be simplified separately, separate them.
  if (LoExists) {
    SDValue Lo = DAG.getNode(LoOp, SDLoc(N), N->getValueType(0), N->ops());
    AddToWorklist(Lo.getNode());
    SDValue LoOpt = combine(Lo.getNode());
    if (LoOpt.getNode() && LoOpt.getNode() != Lo.getNode() &&
        (!LegalOperations ||
         TLI.isOperationLegal(LoOpt.getOpcode(), LoOpt.getValueType())))
      return CombineTo(N, LoOpt, LoOpt);
  }

  if (HiExists) {
    SDValue Hi = DAG.getNode(HiOp, SDLoc(N), N->getValueType(1), N->ops());
    AddToWorklist(Hi.getNode());
    SDValue HiOpt = combine(Hi.getNode());
    if (HiOpt.getNode() && HiOpt != Hi &&
        (!LegalOperations ||
         TLI.isOperationLegal(HiOpt.getOpcode(), HiOpt.getValueType())))
      return CombineTo(N, HiOpt, HiOpt);
  }

  return SDValue();
}

SDValue DAGCombiner::visitSMUL_LOHI(SDNode *N) {
  if (SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHS))
    return Res;

  EVT VT = N->getValueType(0);
  SDLoc DL(N);

  // If the type is twice as wide is legal, transform the mulhu to a wider
  // multiply plus a shift.
  if (VT.isSimple() && !VT.isVector()) {
    MVT Simple = VT.getSimpleVT();
    unsigned SimpleSize = Simple.getSizeInBits();
    EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
    if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
      SDValue Lo = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(0));
      SDValue Hi = DAG.getNode(ISD::SIGN_EXTEND, DL, NewVT, N->getOperand(1));
      Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
      // Compute the high part as N1.
      Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
            DAG.getConstant(SimpleSize, DL,
                            getShiftAmountTy(Lo.getValueType())));
      Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
      // Compute the low part as N0.
      Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
      return CombineTo(N, Lo, Hi);
    }
  }

  return SDValue();
}

SDValue DAGCombiner::visitUMUL_LOHI(SDNode *N) {
  if (SDValue Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHU))
    return Res;

  EVT VT = N->getValueType(0);
  SDLoc DL(N);

  // If the type is twice as wide is legal, transform the mulhu to a wider
  // multiply plus a shift.
  if (VT.isSimple() && !VT.isVector()) {
    MVT Simple = VT.getSimpleVT();
    unsigned SimpleSize = Simple.getSizeInBits();
    EVT NewVT = EVT::getIntegerVT(*DAG.getContext(), SimpleSize*2);
    if (TLI.isOperationLegal(ISD::MUL, NewVT)) {
      SDValue Lo = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(0));
      SDValue Hi = DAG.getNode(ISD::ZERO_EXTEND, DL, NewVT, N->getOperand(1));
      Lo = DAG.getNode(ISD::MUL, DL, NewVT, Lo, Hi);
      // Compute the high part as N1.
      Hi = DAG.getNode(ISD::SRL, DL, NewVT, Lo,
            DAG.getConstant(SimpleSize, DL,
                            getShiftAmountTy(Lo.getValueType())));
      Hi = DAG.getNode(ISD::TRUNCATE, DL, VT, Hi);
      // Compute the low part as N0.
      Lo = DAG.getNode(ISD::TRUNCATE, DL, VT, Lo);
      return CombineTo(N, Lo, Hi);
    }
  }

  return SDValue();
}

SDValue DAGCombiner::visitSMULO(SDNode *N) {
  // (smulo x, 2) -> (saddo x, x)
  if (ConstantSDNode *C2 = dyn_cast<ConstantSDNode>(N->getOperand(1)))
    if (C2->getAPIntValue() == 2)
      return DAG.getNode(ISD::SADDO, SDLoc(N), N->getVTList(),
                         N->getOperand(0), N->getOperand(0));

  return SDValue();
}

SDValue DAGCombiner::visitUMULO(SDNode *N) {
  // (umulo x, 2) -> (uaddo x, x)
  if (ConstantSDNode *C2 = dyn_cast<ConstantSDNode>(N->getOperand(1)))
    if (C2->getAPIntValue() == 2)
      return DAG.getNode(ISD::UADDO, SDLoc(N), N->getVTList(),
                         N->getOperand(0), N->getOperand(0));

  return SDValue();
}

SDValue DAGCombiner::visitIMINMAX(SDNode *N) {
  SDValue N0 = N->getOperand(0);
  SDValue N1 = N->getOperand(1);
  EVT VT = N0.getValueType();

  // fold vector ops
  if (VT.isVector())
    if (SDValue FoldedVOp = SimplifyVBinOp(N))
      return FoldedVOp;

  // fold (add c1, c2) -> c1+c2
  ConstantSDNode *N0C = getAsNonOpaqueConstant(N0);
  ConstantSDNode *N1C = getAsNonOpaqueConstant(N1);
  if (N0C && N1C)
    return DAG.FoldConstantArithmetic(N->getOpcode(), SDLoc(N), VT, N0C, N1C);

  // canonicalize constant to RHS
  if (isConstantIntBuildVectorOrConstantInt(N0) &&
     !isConstantIntBuildVectorOrConstantInt(N1))
    return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N1, N0);

  return SDValue();
}

/// If this is a binary operator with two operands of the same opcode, try to
/// simplify it.
SDValue DAGCombiner::SimplifyBinOpWithSameOpcodeHands(SDNode *N) {
  SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
  EVT VT = N0.getValueType();
  assert(N0.getOpcode() == N1.getOpcode() && "Bad input!");

  // Bail early if none of these transforms apply.
  if (N0.getNode()->getNumOperands() == 0) return SDValue();

  // For each of OP in AND/OR/XOR:
  // fold (OP (zext x), (zext y)) -> (zext (OP x, y))
  // fold (OP (sext x), (sext y)) -> (sext (OP x, y))
  // fold (OP (aext x), (aext y)) -> (aext (OP x, y))
  // fold (OP (bswap x), (bswap y)) -> (bswap (OP x, y))
  // fold (OP (trunc x), (trunc y)) -> (trunc (OP x, y)) (if trunc isn't free)
  //
  // do not sink logical op inside of a vector extend, since it may combine
  // into a vsetcc.
  EVT Op0VT = N0.getOperand(0).getValueType();
  if ((N0.getOpcode() == ISD::ZERO_EXTEND ||
       N0.getOpcode() == ISD::SIGN_EXTEND ||
       N0.getOpcode() == ISD::BSWAP ||
       // Avoid infinite looping with PromoteIntBinOp.
       (N0.getOpcode() == ISD::ANY_EXTEND &&
        (!LegalTypes || TLI.isTypeDesirableForOp(N->getOpcode(), Op0VT))) ||
       (N0.getOpcode() == ISD::TRUNCATE &&
        (!TLI.isZExtFree(VT, Op0VT) ||
         !TLI.isTruncateFree(Op0VT, VT)) &&
        TLI.isTypeLegal(Op0VT))) &&
      !VT.isVector() &&
      Op0VT == N1.getOperand(0).getValueType() &&
      (!LegalOperations || TLI.isOperationLegal(N->getOpcode(), Op0VT))) {
    SDValue ORNode = DAG.getNode(N->getOpcode(), SDLoc(N0),
                                 N0.getOperand(0).getValueType(),
                                 N0.getOperand(0), N1.getOperand(0));
    AddToWorklist(ORNode.getNode());
    return DAG.getNode(N0.getOpcode(), SDLoc(N), VT, ORNode);
  }

  // For each of OP in SHL/SRL/SRA/AND...
  //   fold (and (OP x, z), (OP y, z)) -> (OP (and x, y), z)
  //   fold (or  (OP x, z), (OP y, z)) -> (OP (or  x, y), z)
  //   fold (xor (OP x, z), (OP y, z)) -> (OP (xor x, y), z)
  if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL ||
       N0.getOpcode() == ISD::SRA || N0.getOpcode() == ISD::AND) &&
      N0.getOperand(1) == N1.getOperand(1)) {
    SDValue ORNode = DAG.getNode(N->getOpcode(), SDLoc(N0),
                                 N0.getOperand(0).getValueType(),
                                 N0.getOperand(0), N1.getOperand(0));
    AddToWorklist(ORNode.getNode());
    return DAG.getNode(N0.getOpcode(), SDLoc(N), VT,
                       ORNode, N0.getOperand(1));
  }

  // Simplify xor/and/or (bitcast(A), bitcast(B)) -> bitcast(op (A,B))
  // Only perform this optimization after type legalization and before
  // LegalizeVectorOprs. LegalizeVectorOprs promotes vector operations by
  // adding bitcasts. For example (xor v4i32) is promoted to (v2i64), and
  // we don't want to undo this promotion.
  // We also handle SCALAR_TO_VECTOR because xor/or/and operations are cheaper
  // on scalars.
  if ((N0.getOpcode() == ISD::BITCAST ||
       N0.getOpcode() == ISD::SCALAR_TO_VECTOR) &&
      Level == AfterLegalizeTypes) {
    SDValue In0 = N0.getOperand(0);
    SDValue In1 = N1.getOperand(0);
    EVT In0Ty = In0.getValueType();
    EVT In1Ty = In1.getValueType();
    SDLoc DL(N);
    // If both incoming values are integers, and the original types are the
    // same.
    if (In0Ty.isInteger() && In1Ty.isInteger() && In0Ty == In1Ty) {
      SDValue Op = DAG.getNode(N->getOpcode(), DL, In0Ty, In0, In1);
      SDValue BC = DAG.getNode(N0.getOpcode(), DL, VT, Op);
      AddToWorklist(Op.getNode());
      return BC;
    }
  }

  // Xor/and/or are indifferent to the swizzle operation (shuffle of one value).
  // Simplify xor/and/or (shuff(A), shuff(B)) -> shuff(op (A,B))
  // If both shuffles use the same mask, and both shuffle within a single
  // vector, then it is worthwhile to move the swizzle after the operation.
  // The type-legalizer generates this pattern when loading illegal
  // vector types from memory. In many cases this allows additional shuffle
  // optimizations.
  // There are other cases where moving the shuffle after the xor/and/or
  // is profitable even if shuffles don't perform a swizzle.
  // If both shuffles use the same mask, and both shuffles have the same first
  // or second operand, then it might still be profitable to move the shuffle
  // after the xor/and/or operation.
  if (N0.getOpcode() == ISD::VECTOR_SHUFFLE && Level < AfterLegalizeDAG) {
    ShuffleVectorSDNode *SVN0 = cast<ShuffleVectorSDNode>(N0);
    ShuffleVectorSDNode *SVN1 = cast<ShuffleVectorSDNode>(N1);

    assert(N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType() &&
           "Inputs to shuffles are not the same type");

    // Check that both shuffles use the same mask. The masks are known to be of
    // the same length because the result vector type is the same.
    // Check also that shuffles have only one use to avoid introducing extra
    // instructions.
    if (SVN0->hasOneUse() && SVN1->hasOneUse() &&
        SVN0->getMask().equals(SVN1->getMask())) {
      SDValue ShOp = N0->getOperand(1);

      // Don't try to fold this node if it requires introducing a
      // build vector of all zeros that might be illegal at this stage.
      if (N->getOpcode() == ISD::XOR && ShOp.getOpcode() != ISD::UNDEF) {
        if (!LegalTypes)
          ShOp = DAG.getConstant(0, SDLoc(N), VT);
        else
          ShOp = SDValue();
      }

      // (AND (shuf (A, C), shuf (B, C)) -> shuf (AND (A, B), C)
      // (OR  (shuf (A, C), shuf (B, C)) -> shuf (OR  (A, B), C)
      // (XOR (shuf (A, C), shuf (B, C)) -> shuf (XOR (A, B), V_0)
      if (N0.getOperand(1) == N1.getOperand(1) && ShOp.getNode()) {
        SDValue NewNode = DAG.getNode(N->getOpcode(), SDLoc(N), VT,
                                      N0->getOperand(0), N1->getOperand(0));
        AddToWorklist(NewNode.getNode());
        return DAG.getVectorShuffle(VT, SDLoc(N), NewNode, ShOp,
                                    &SVN0->getMask()[0]);
      }

      // Don't try to fold this node if it requires introducing a
      // build vector of all zeros that might be illegal at this stage.
      ShOp = N0->getOperand(0);
      if (N->getOpcode() == ISD::XOR && ShOp.getOpcode() != ISD::UNDEF) {
        if (!LegalTypes)
          ShOp = DAG.getConstant(0, SDLoc(N), VT);
        else
          ShOp = SDValue();
      }

      // (AND (shuf (C, A), shuf (C, B)) -> shuf (C, AND (A, B))
      // (OR  (shuf (C, A), shuf (C, B)) -> shuf (C, OR  (A, B))
      // (XOR (shuf (C, A), shuf (C, B)) -> shuf (V_0, XOR (A, B))
      if (N0->getOperand(0) == N1->getOperand(0) && ShOp.getNode()) {
        SDValue NewNode = DAG.getNode(N->getOpcode(), SDLoc(N), VT,
                                      N0->getOperand(1), N1->getOperand(1));
        AddToWorklist(NewNode.getNode());
        return DAG.getVectorShuffle(VT, SDLoc(N), ShOp, NewNode,
                                    &SVN0->getMask()[0]);
      }
    }
  }

  return SDValue();
}

/// This contains all DAGCombine rules which reduce two values combined by
/// an And operation to a single value. This makes them reusable in the context
/// of visitSELECT(). Rules involving constants are not included as
/// visitSELECT() already handles those cases.
SDValue DAGCombiner::visitANDLike(SDValue N0, SDValue N1,
                                  SDNode *LocReference) {
  EVT VT = N1.getValueType();

  // fold (and x, undef) -> 0
  if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
    return DAG.getConstant(0, SDLoc(LocReference), VT);
  // fold (and (setcc x), (setcc y)) -> (setcc (and x, y))
  SDValue LL, LR, RL, RR, CC0, CC1;
  if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){
    ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get();
    ISD::CondCode Op1 = cast<CondCodeSDNode>(CC1)->get();

    if (LR == RR && isa<ConstantSDNode>(LR) && Op0 == Op1 &&
        LL.getValueType().isInteger()) {
      // fold (and (seteq X, 0), (seteq Y, 0)) -> (seteq (or X, Y), 0)
      if (isNullConstant(LR) && Op1 == ISD::SETEQ) {
        SDValue ORNode = DAG.getNode(ISD::OR, SDLoc(N0),
                                     LR.getValueType(), LL, RL);
        AddToWorklist(ORNode.getNode());
        return DAG.getSetCC(SDLoc(LocReference), VT, ORNode, LR, Op1);
      }
      if (isAllOnesConstant(LR)) {
        // fold (and (seteq X, -1), (seteq Y, -1)) -> (seteq (and X, Y), -1)
        if (Op1 == ISD::SETEQ) {
          SDValue ANDNode = DAG.getNode(ISD::AND, SDLoc(N0),
                                        LR.getValueType(), LL, RL);
          AddToWorklist(ANDNode.getNode());
          return DAG.getSetCC(SDLoc(LocReference), VT, ANDNode, LR, Op1);
        }
        // fold (and (setgt X, -1), (setgt Y, -1)) -> (setgt (or X, Y), -1)
        if (Op1 == ISD::SETGT) {
          SDValue ORNode = DAG.getNode(ISD::OR, SDLoc(N0),
                                       LR.getValueType(), LL, RL);
          AddToWorklist(ORNode.getNode());
          return DAG.getSetCC(SDLoc(LocReference), VT, ORNode, LR, Op1);
        }
      }
    }
    // Simplify (and (setne X, 0), (setne X, -1)) -> (setuge (add X, 1), 2)
    if (LL == RL && isa<ConstantSDNode>(LR) && isa<ConstantSDNode>(RR) &&
        Op0 == Op1 && LL.getValueType().isInteger() &&
      Op0 == ISD::SETNE && ((isNullConstant(LR) && isAllOnesConstant(RR)) ||
                            (isAllOnesConstant(LR) && isNullConstant(RR)))) {
      SDLoc DL(N0);
      SDValue ADDNode = DAG.getNode(ISD::ADD, DL, LL.getValueType(),
                                    LL, DAG.getConstant(1, DL,
                                                        LL.getValueType()));
      AddToWorklist(ADDNode.getNode());
      return DAG.getSetCC(SDLoc(LocReference), VT, ADDNode,
                          DAG.getConstant(2, DL, LL.getValueType()),
                          ISD::SETUGE);
    }
    // canonicalize equivalent to ll == rl
    if (LL == RR && LR == RL) {
      Op1 = ISD::getSetCCSwappedOperands(Op1);
      std::swap(RL, RR);
    }
    if (LL == RL && LR == RR) {
      bool isInteger = LL.getValueType().isInteger();
      ISD::CondCode Result = ISD::getSetCCAndOperation(Op0, Op1, isInteger);
      if (Result != ISD::SETCC_INVALID &&
          (!LegalOperations ||
           (TLI.isCondCodeLegal(Result, LL.getSimpleValueType()) &&
            TLI.isOperationLegal(ISD::SETCC, LL.getValueType())))) {
        EVT CCVT = getSetCCResultType(LL.getValueType());
        if (N0.getValueType() == CCVT ||
            (!LegalOperations && N0.getValueType() == MVT::i1))
          return DAG.getSetCC(SDLoc(LocReference), N0.getValueType(),
                              LL, LR, Result);
      }
    }
  }

  if (N0.getOpcode() == ISD::ADD && N1.getOpcode() == ISD::SRL &&
      VT.getSizeInBits() <= 64) {
    if (ConstantSDNode *ADDI = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
      APInt ADDC = ADDI->getAPIntValue();
      if (!TLI.isLegalAddImmediate(ADDC.getSExtValue())) {
        // Look for (and (add x, c1), (lshr y, c2)). If C1 wasn't a legal
        // immediate for an add, but it is legal if its top c2 bits are set,
        // transform the ADD so the immediate doesn't need to be materialized
        // in a register.
        if (ConstantSDNode *SRLI = dyn_cast<ConstantSDNode>(N1.getOperand(1))) {
          APInt Mask = APInt::getHighBitsSet(VT.getSizeInBits(),
                                             SRLI->getZExtValue());
          if (DAG.MaskedValueIsZero(N0.getOperand(1), Mask)) {
            ADDC |= Mask;
            if (TLI.isLegalAddImmediate(ADDC.