SelectionDAG.cpp

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//===- SelectionDAG.cpp - Implement the SelectionDAG data structures ------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This implements the SelectionDAG class.
//
//===----------------------------------------------------------------------===//
 
#include "llvm/CodeGen/SelectionDAG.h"
#include "SDNodeDbgValue.h"
#include "llvm/ADT/APFloat.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/APSInt.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/BinaryFormat/Dwarf.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CodeGenCommonISel.h"
#include "llvm/CodeGen/FunctionLoweringInfo.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/RuntimeLibcallUtil.h"
#include "llvm/CodeGen/SDPatternMatch.h"
#include "llvm/CodeGen/SelectionDAGAddressAnalysis.h"
#include "llvm/CodeGen/SelectionDAGNodes.h"
#include "llvm/CodeGen/SelectionDAGTargetInfo.h"
#include "llvm/CodeGen/TargetFrameLowering.h"
#include "llvm/CodeGen/TargetLowering.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/CodeGenTypes/MachineValueType.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/CodeGen.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/KnownBits.h"
#include "llvm/Support/KnownFPClass.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <limits>
#include <optional>
#include <string>
#include <utility>
#include <vector>
 
using namespace llvm;
using namespace llvm::SDPatternMatch;
 
/// makeVTList - Return an instance of the SDVTList struct initialized with the
/// specified members.
static SDVTList makeVTList(const EVT *VTs, unsigned NumVTs) {
  SDVTList Res = {VTs, NumVTs};
  return Res;
}
 
// Default null implementations of the callbacks.
void SelectionDAG::DAGUpdateListener::NodeDeleted(SDNode*, SDNode*) {}
void SelectionDAG::DAGUpdateListener::NodeUpdated(SDNode*) {}
void SelectionDAG::DAGUpdateListener::NodeInserted(SDNode *) {}
 
void SelectionDAG::DAGNodeDeletedListener::anchor() {}
void SelectionDAG::DAGNodeInsertedListener::anchor() {}
 
#define DEBUG_TYPE "selectiondag"
 
static cl::opt<bool> EnableMemCpyDAGOpt("enable-memcpy-dag-opt",
       cl::Hidden, cl::init(true),
       cl::desc("Gang up loads and stores generated by inlining of memcpy"));
 
static cl::opt<int> MaxLdStGlue("ldstmemcpy-glue-max",
       cl::desc("Number limit for gluing ld/st of memcpy."),
       cl::Hidden, cl::init(0));
 
static cl::opt<unsigned>
    MaxSteps("has-predecessor-max-steps", cl::Hidden, cl::init(8192),
             cl::desc("DAG combiner limit number of steps when searching DAG "
                      "for predecessor nodes"));
 
static void NewSDValueDbgMsg(SDValue V, StringRef Msg, SelectionDAG *G) {
  LLVM_DEBUG(dbgs() << Msg; V.getNode()->dump(G););
}
 
unsigned SelectionDAG::getHasPredecessorMaxSteps() { return MaxSteps; }
 
//===----------------------------------------------------------------------===//
//                              ConstantFPSDNode Class
//===----------------------------------------------------------------------===//
 
/// isExactlyValue - We don't rely on operator== working on double values, as
/// it returns true for things that are clearly not equal, like -0.0 and 0.0.
/// As such, this method can be used to do an exact bit-for-bit comparison of
/// two floating point values.
bool ConstantFPSDNode::isExactlyValue(const APFloat& V) const {
  return getValueAPF().bitwiseIsEqual(V);
}
 
bool ConstantFPSDNode::isValueValidForType(EVT VT,
                                           const APFloat& Val) {
  assert(VT.isFloatingPoint() && "Can only convert between FP types");
 
  // convert modifies in place, so make a copy.
  APFloat Val2 = APFloat(Val);
  bool losesInfo;
  (void)Val2.convert(VT.getFltSemantics(), APFloat::rmNearestTiesToEven,
                     &losesInfo);
  return !losesInfo;
}
 
//===----------------------------------------------------------------------===//
//                              ISD Namespace
//===----------------------------------------------------------------------===//
 
bool ISD::isConstantSplatVector(const SDNode *N, APInt &SplatVal) {
  if (N->getOpcode() == ISD::SPLAT_VECTOR) {
    if (auto OptAPInt = N->getOperand(0)->bitcastToAPInt()) {
      unsigned EltSize =
          N->getValueType(0).getVectorElementType().getSizeInBits();
      SplatVal = OptAPInt->trunc(EltSize);
      return true;
    }
  }
 
  auto *BV = dyn_cast<BuildVectorSDNode>(N);
  if (!BV)
    return false;
 
  APInt SplatUndef;
  unsigned SplatBitSize;
  bool HasUndefs;
  unsigned EltSize = N->getValueType(0).getVectorElementType().getSizeInBits();
  // Endianness does not matter here. We are checking for a splat given the
  // element size of the vector, and if we find such a splat for little endian
  // layout, then that should be valid also for big endian (as the full vector
  // size is known to be a multiple of the element size).
  const bool IsBigEndian = false;
  return BV->isConstantSplat(SplatVal, SplatUndef, SplatBitSize, HasUndefs,
                             EltSize, IsBigEndian) &&
         EltSize == SplatBitSize;
}
 
// FIXME: AllOnes and AllZeros duplicate a lot of code. Could these be
// specializations of the more general isConstantSplatVector()?
 
bool ISD::isConstantSplatVectorAllOnes(const SDNode *N, bool BuildVectorOnly) {
  // Look through a bit convert.
  while (N->getOpcode() == ISD::BITCAST)
    N = N->getOperand(0).getNode();
 
  if (!BuildVectorOnly && N->getOpcode() == ISD::SPLAT_VECTOR) {
    APInt SplatVal;
    return isConstantSplatVector(N, SplatVal) && SplatVal.isAllOnes();
  }
 
  if (N->getOpcode() != ISD::BUILD_VECTOR) return false;
 
  unsigned i = 0, e = N->getNumOperands();
 
  // Skip over all of the undef values.
  while (i != e && N->getOperand(i).isUndef())
    ++i;
 
  // Do not accept an all-undef vector.
  if (i == e) return false;
 
  // Do not accept build_vectors that aren't all constants or which have non-~0
  // elements. We have to be a bit careful here, as the type of the constant
  // may not be the same as the type of the vector elements due to type
  // legalization (the elements are promoted to a legal type for the target and
  // a vector of a type may be legal when the base element type is not).
  // We only want to check enough bits to cover the vector elements, because
  // we care if the resultant vector is all ones, not whether the individual
  // constants are.
  SDValue NotZero = N->getOperand(i);
  if (auto OptAPInt = NotZero->bitcastToAPInt()) {
    unsigned EltSize = N->getValueType(0).getScalarSizeInBits();
    if (OptAPInt->countr_one() < EltSize)
      return false;
  } else
    return false;
 
  // Okay, we have at least one ~0 value, check to see if the rest match or are
  // undefs. Even with the above element type twiddling, this should be OK, as
  // the same type legalization should have applied to all the elements.
  for (++i; i != e; ++i)
    if (N->getOperand(i) != NotZero && !N->getOperand(i).isUndef())
      return false;
  return true;
}
 
bool ISD::isConstantSplatVectorAllZeros(const SDNode *N, bool BuildVectorOnly) {
  // Look through a bit convert.
  while (N->getOpcode() == ISD::BITCAST)
    N = N->getOperand(0).getNode();
 
  if (!BuildVectorOnly && N->getOpcode() == ISD::SPLAT_VECTOR) {
    APInt SplatVal;
    return isConstantSplatVector(N, SplatVal) && SplatVal.isZero();
  }
 
  if (N->getOpcode() != ISD::BUILD_VECTOR) return false;
 
  bool IsAllUndef = true;
  for (const SDValue &Op : N->op_values()) {
    if (Op.isUndef())
      continue;
    IsAllUndef = false;
    // Do not accept build_vectors that aren't all constants or which have non-0
    // elements. We have to be a bit careful here, as the type of the constant
    // may not be the same as the type of the vector elements due to type
    // legalization (the elements are promoted to a legal type for the target
    // and a vector of a type may be legal when the base element type is not).
    // We only want to check enough bits to cover the vector elements, because
    // we care if the resultant vector is all zeros, not whether the individual
    // constants are.
    if (auto OptAPInt = Op->bitcastToAPInt()) {
      unsigned EltSize = N->getValueType(0).getScalarSizeInBits();
      if (OptAPInt->countr_zero() < EltSize)
        return false;
    } else
      return false;
  }
 
  // Do not accept an all-undef vector.
  if (IsAllUndef)
    return false;
  return true;
}
 
bool ISD::isBuildVectorAllOnes(const SDNode *N) {
  return isConstantSplatVectorAllOnes(N, /*BuildVectorOnly*/ true);
}
 
bool ISD::isBuildVectorAllZeros(const SDNode *N) {
  return isConstantSplatVectorAllZeros(N, /*BuildVectorOnly*/ true);
}
 
bool ISD::isBuildVectorOfConstantSDNodes(const SDNode *N) {
  if (N->getOpcode() != ISD::BUILD_VECTOR)
    return false;
 
  for (const SDValue &Op : N->op_values()) {
    if (Op.isUndef())
      continue;
    if (!isa<ConstantSDNode>(Op))
      return false;
  }
  return true;
}
 
bool ISD::isBuildVectorOfConstantFPSDNodes(const SDNode *N) {
  if (N->getOpcode() != ISD::BUILD_VECTOR)
    return false;
 
  for (const SDValue &Op : N->op_values()) {
    if (Op.isUndef())
      continue;
    if (!isa<ConstantFPSDNode>(Op))
      return false;
  }
  return true;
}
 
bool ISD::isVectorShrinkable(const SDNode *N, unsigned NewEltSize,
                             bool Signed) {
  assert(N->getValueType(0).isVector() && "Expected a vector!");
 
  unsigned EltSize = N->getValueType(0).getScalarSizeInBits();
  if (EltSize <= NewEltSize)
    return false;
 
  if (N->getOpcode() == ISD::ZERO_EXTEND) {
    return (N->getOperand(0).getValueType().getScalarSizeInBits() <=
            NewEltSize) &&
           !Signed;
  }
  if (N->getOpcode() == ISD::SIGN_EXTEND) {
    return (N->getOperand(0).getValueType().getScalarSizeInBits() <=
            NewEltSize) &&
           Signed;
  }
  if (N->getOpcode() != ISD::BUILD_VECTOR)
    return false;
 
  for (const SDValue &Op : N->op_values()) {
    if (Op.isUndef())
      continue;
    if (!isa<ConstantSDNode>(Op))
      return false;
 
    APInt C = Op->getAsAPIntVal().trunc(EltSize);
    if (Signed && C.trunc(NewEltSize).sext(EltSize) != C)
      return false;
    if (!Signed && C.trunc(NewEltSize).zext(EltSize) != C)
      return false;
  }
 
  return true;
}
 
bool ISD::allOperandsUndef(const SDNode *N) {
  // Return false if the node has no operands.
  // This is "logically inconsistent" with the definition of "all" but
  // is probably the desired behavior.
  if (N->getNumOperands() == 0)
    return false;
  return all_of(N->op_values(), [](SDValue Op) { return Op.isUndef(); });
}
 
bool ISD::isFreezeUndef(const SDNode *N) {
  return N->getOpcode() == ISD::FREEZE && N->getOperand(0).isUndef();
}
 
template <typename ConstNodeType>
bool ISD::matchUnaryPredicateImpl(SDValue Op, const APInt &DemandedElts,
                                  std::function<bool(ConstNodeType *)> Match,
                                  bool AllowUndefs, bool AllowTruncation) {
  // FIXME: Add support for scalar UNDEF cases?
  if (auto *C = dyn_cast<ConstNodeType>(Op))
    return Match(C);
 
  // FIXME: Add support for vector UNDEF cases?
  if (ISD::BUILD_VECTOR != Op.getOpcode() &&
      ISD::SPLAT_VECTOR != Op.getOpcode())
    return false;
 
  if (ISD::SPLAT_VECTOR == Op.getOpcode() && !DemandedElts)
    return true;
 
  EVT SVT = Op.getValueType().getScalarType();
  for (unsigned i = 0, e = Op.getNumOperands(); i != e; ++i) {
    if (ISD::SPLAT_VECTOR != Op.getOpcode() && !DemandedElts[i])
      continue;
 
    if (AllowUndefs && Op.getOperand(i).isUndef()) {
      if (!Match(nullptr))
        return false;
      continue;
    }
 
    auto *Cst = dyn_cast<ConstNodeType>(Op.getOperand(i));
    if (!Cst || (!AllowTruncation && Cst->getValueType(0) != SVT) ||
        !Match(Cst))
      return false;
  }
  return true;
}
// Build used template types.
template bool ISD::matchUnaryPredicateImpl<ConstantSDNode>(
    SDValue, const APInt &, std::function<bool(ConstantSDNode *)>, bool, bool);
template bool ISD::matchUnaryPredicateImpl<ConstantFPSDNode>(
    SDValue, const APInt &, std::function<bool(ConstantFPSDNode *)>, bool,
    bool);
 
bool ISD::matchBinaryPredicate(
    SDValue LHS, SDValue RHS, const APInt &DemandedElts,
    std::function<bool(ConstantSDNode *, ConstantSDNode *)> Match,
    bool AllowUndefs, bool AllowTypeMismatch) {
  if (!AllowTypeMismatch && LHS.getValueType() != RHS.getValueType())
    return false;
 
  // TODO: Add support for scalar UNDEF cases?
  if (auto *LHSCst = dyn_cast<ConstantSDNode>(LHS))
    if (auto *RHSCst = dyn_cast<ConstantSDNode>(RHS))
      return Match(LHSCst, RHSCst);
 
  // TODO: Add support for vector UNDEF cases?
  if (LHS.getOpcode() != RHS.getOpcode() ||
      (LHS.getOpcode() != ISD::BUILD_VECTOR &&
       LHS.getOpcode() != ISD::SPLAT_VECTOR))
    return false;
 
  if (ISD::SPLAT_VECTOR == LHS.getOpcode() && !DemandedElts)
    return true;
 
  EVT SVT = LHS.getValueType().getScalarType();
  for (unsigned i = 0, e = LHS.getNumOperands(); i != e; ++i) {
    if (ISD::SPLAT_VECTOR != LHS.getOpcode() && !DemandedElts[i])
      continue;
    SDValue LHSOp = LHS.getOperand(i);
    SDValue RHSOp = RHS.getOperand(i);
    bool LHSUndef = AllowUndefs && LHSOp.isUndef();
    bool RHSUndef = AllowUndefs && RHSOp.isUndef();
    auto *LHSCst = dyn_cast<ConstantSDNode>(LHSOp);
    auto *RHSCst = dyn_cast<ConstantSDNode>(RHSOp);
    if ((!LHSCst && !LHSUndef) || (!RHSCst && !RHSUndef))
      return false;
    if (!AllowTypeMismatch && (LHSOp.getValueType() != SVT ||
                               LHSOp.getValueType() != RHSOp.getValueType()))
      return false;
    if (!Match(LHSCst, RHSCst))
      return false;
  }
  return true;
}
 
ISD::NodeType ISD::getInverseMinMaxOpcode(unsigned MinMaxOpc) {
  switch (MinMaxOpc) {
  default:
    llvm_unreachable("unrecognized opcode");
  case ISD::UMIN:
    return ISD::UMAX;
  case ISD::UMAX:
    return ISD::UMIN;
  case ISD::SMIN:
    return ISD::SMAX;
  case ISD::SMAX:
    return ISD::SMIN;
  }
}
 
ISD::NodeType ISD::getOppositeSignednessMinMaxOpcode(unsigned MinMaxOpc) {
  switch (MinMaxOpc) {
  default:
    llvm_unreachable("unrecognized min/max opcode");
  case ISD::SMIN:
    return ISD::UMIN;
  case ISD::SMAX:
    return ISD::UMAX;
  case ISD::UMIN:
    return ISD::SMIN;
  case ISD::UMAX:
    return ISD::SMAX;
  }
}
 
ISD::NodeType ISD::getVecReduceBaseOpcode(unsigned VecReduceOpcode) {
  switch (VecReduceOpcode) {
  default:
    llvm_unreachable("Expected VECREDUCE opcode");
  case ISD::VECREDUCE_FADD:
  case ISD::VECREDUCE_SEQ_FADD:
  case ISD::VP_REDUCE_FADD:
  case ISD::VP_REDUCE_SEQ_FADD:
    return ISD::FADD;
  case ISD::VECREDUCE_FMUL:
  case ISD::VECREDUCE_SEQ_FMUL:
  case ISD::VP_REDUCE_FMUL:
  case ISD::VP_REDUCE_SEQ_FMUL:
    return ISD::FMUL;
  case ISD::VECREDUCE_ADD:
  case ISD::VP_REDUCE_ADD:
    return ISD::ADD;
  case ISD::VECREDUCE_MUL:
  case ISD::VP_REDUCE_MUL:
    return ISD::MUL;
  case ISD::VECREDUCE_AND:
  case ISD::VP_REDUCE_AND:
    return ISD::AND;
  case ISD::VECREDUCE_OR:
  case ISD::VP_REDUCE_OR:
    return ISD::OR;
  case ISD::VECREDUCE_XOR:
  case ISD::VP_REDUCE_XOR:
    return ISD::XOR;
  case ISD::VECREDUCE_SMAX:
  case ISD::VP_REDUCE_SMAX:
    return ISD::SMAX;
  case ISD::VECREDUCE_SMIN:
  case ISD::VP_REDUCE_SMIN:
    return ISD::SMIN;
  case ISD::VECREDUCE_UMAX:
  case ISD::VP_REDUCE_UMAX:
    return ISD::UMAX;
  case ISD::VECREDUCE_UMIN:
  case ISD::VP_REDUCE_UMIN:
    return ISD::UMIN;
  case ISD::VECREDUCE_FMAX:
  case ISD::VP_REDUCE_FMAX:
    return ISD::FMAXNUM;
  case ISD::VECREDUCE_FMIN:
  case ISD::VP_REDUCE_FMIN:
    return ISD::FMINNUM;
  case ISD::VECREDUCE_FMAXIMUM:
  case ISD::VP_REDUCE_FMAXIMUM:
    return ISD::FMAXIMUM;
  case ISD::VECREDUCE_FMINIMUM:
  case ISD::VP_REDUCE_FMINIMUM:
    return ISD::FMINIMUM;
  case ISD::VECREDUCE_FMAXIMUMNUM:
    return ISD::FMAXIMUMNUM;
  case ISD::VECREDUCE_FMINIMUMNUM:
    return ISD::FMINIMUMNUM;
  }
}
 
ISD::NodeType ISD::getUnmaskedBinOpOpcode(unsigned MaskedOpc) {
  switch (MaskedOpc) {
  case ISD::MASKED_UDIV:
    return ISD::UDIV;
  case ISD::MASKED_SDIV:
    return ISD::SDIV;
  case ISD::MASKED_UREM:
    return ISD::UREM;
  case ISD::MASKED_SREM:
    return ISD::SREM;
  default:
    llvm_unreachable("Expected masked binop opcode");
  }
}
 
bool ISD::isVPOpcode(unsigned Opcode) {
  switch (Opcode) {
  default:
    return false;
#define BEGIN_REGISTER_VP_SDNODE(VPSD, ...)                                    \
  case ISD::VPSD:                                                              \
    return true;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
bool ISD::isVPBinaryOp(unsigned Opcode) {
  switch (Opcode) {
  default:
    break;
#define BEGIN_REGISTER_VP_SDNODE(VPSD, ...) case ISD::VPSD:
#define VP_PROPERTY_BINARYOP return true;
#define END_REGISTER_VP_SDNODE(VPSD) break;
#include "llvm/IR/VPIntrinsics.def"
  }
  return false;
}
 
bool ISD::isVPReduction(unsigned Opcode) {
  switch (Opcode) {
  default:
    return false;
  case ISD::VP_REDUCE_ADD:
  case ISD::VP_REDUCE_MUL:
  case ISD::VP_REDUCE_AND:
  case ISD::VP_REDUCE_OR:
  case ISD::VP_REDUCE_XOR:
  case ISD::VP_REDUCE_SMAX:
  case ISD::VP_REDUCE_SMIN:
  case ISD::VP_REDUCE_UMAX:
  case ISD::VP_REDUCE_UMIN:
  case ISD::VP_REDUCE_FMAX:
  case ISD::VP_REDUCE_FMIN:
  case ISD::VP_REDUCE_FMAXIMUM:
  case ISD::VP_REDUCE_FMINIMUM:
  case ISD::VP_REDUCE_FADD:
  case ISD::VP_REDUCE_FMUL:
  case ISD::VP_REDUCE_SEQ_FADD:
  case ISD::VP_REDUCE_SEQ_FMUL:
    return true;
  }
}
 
/// The operand position of the vector mask.
std::optional<unsigned> ISD::getVPMaskIdx(unsigned Opcode) {
  switch (Opcode) {
  default:
    return std::nullopt;
#define BEGIN_REGISTER_VP_SDNODE(VPSD, LEGALPOS, TDNAME, MASKPOS, ...)         \
  case ISD::VPSD:                                                              \
    return MASKPOS;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
/// The operand position of the explicit vector length parameter.
std::optional<unsigned> ISD::getVPExplicitVectorLengthIdx(unsigned Opcode) {
  switch (Opcode) {
  default:
    return std::nullopt;
#define BEGIN_REGISTER_VP_SDNODE(VPSD, LEGALPOS, TDNAME, MASKPOS, EVLPOS)      \
  case ISD::VPSD:                                                              \
    return EVLPOS;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
std::optional<unsigned> ISD::getBaseOpcodeForVP(unsigned VPOpcode,
                                                bool hasFPExcept) {
  // FIXME: Return strict opcodes in case of fp exceptions.
  switch (VPOpcode) {
  default:
    return std::nullopt;
#define BEGIN_REGISTER_VP_SDNODE(VPOPC, ...) case ISD::VPOPC:
#define VP_PROPERTY_FUNCTIONAL_SDOPC(SDOPC) return ISD::SDOPC;
#define END_REGISTER_VP_SDNODE(VPOPC) break;
#include "llvm/IR/VPIntrinsics.def"
  }
  return std::nullopt;
}
 
std::optional<unsigned> ISD::getVPForBaseOpcode(unsigned Opcode) {
  switch (Opcode) {
  default:
    return std::nullopt;
#define BEGIN_REGISTER_VP_SDNODE(VPOPC, ...) break;
#define VP_PROPERTY_FUNCTIONAL_SDOPC(SDOPC) case ISD::SDOPC:
#define END_REGISTER_VP_SDNODE(VPOPC) return ISD::VPOPC;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
ISD::NodeType ISD::getExtForLoadExtType(bool IsFP, ISD::LoadExtType ExtType) {
  switch (ExtType) {
  case ISD::EXTLOAD:
    return IsFP ? ISD::FP_EXTEND : ISD::ANY_EXTEND;
  case ISD::SEXTLOAD:
    return ISD::SIGN_EXTEND;
  case ISD::ZEXTLOAD:
    return ISD::ZERO_EXTEND;
  default:
    break;
  }
 
  llvm_unreachable("Invalid LoadExtType");
}
 
ISD::CondCode ISD::getSetCCSwappedOperands(ISD::CondCode Operation) {
  // To perform this operation, we just need to swap the L and G bits of the
  // operation.
  unsigned OldL = (Operation >> 2) & 1;
  unsigned OldG = (Operation >> 1) & 1;
  return ISD::CondCode((Operation & ~6) |  // Keep the N, U, E bits
                       (OldL << 1) |       // New G bit
                       (OldG << 2));       // New L bit.
}
 
static ISD::CondCode getSetCCInverseImpl(ISD::CondCode Op, bool isIntegerLike) {
  unsigned Operation = Op;
  if (isIntegerLike)
    Operation ^= 7;   // Flip L, G, E bits, but not U.
  else
    Operation ^= 15;  // Flip all of the condition bits.
 
  if (Operation > ISD::SETTRUE2)
    Operation &= ~8;  // Don't let N and U bits get set.
 
  return ISD::CondCode(Operation);
}
 
ISD::CondCode ISD::getSetCCInverse(ISD::CondCode Op, EVT Type) {
  return getSetCCInverseImpl(Op, Type.isInteger());
}
 
ISD::CondCode ISD::GlobalISel::getSetCCInverse(ISD::CondCode Op,
                                               bool isIntegerLike) {
  return getSetCCInverseImpl(Op, isIntegerLike);
}
 
/// For an integer comparison, return 1 if the comparison is a signed operation
/// and 2 if the result is an unsigned comparison. Return zero if the operation
/// does not depend on the sign of the input (setne and seteq).
static int isSignedOp(ISD::CondCode Opcode) {
  switch (Opcode) {
  default: llvm_unreachable("Illegal integer setcc operation!");
  case ISD::SETEQ:
  case ISD::SETNE: return 0;
  case ISD::SETLT:
  case ISD::SETLE:
  case ISD::SETGT:
  case ISD::SETGE: return 1;
  case ISD::SETULT:
  case ISD::SETULE:
  case ISD::SETUGT:
  case ISD::SETUGE: return 2;
  }
}
 
ISD::CondCode ISD::getSetCCOrOperation(ISD::CondCode Op1, ISD::CondCode Op2,
                                       EVT Type) {
  bool IsInteger = Type.isInteger();
  if (IsInteger && (isSignedOp(Op1) | isSignedOp(Op2)) == 3)
    // Cannot fold a signed integer setcc with an unsigned integer setcc.
    return ISD::SETCC_INVALID;
 
  unsigned Op = Op1 | Op2;  // Combine all of the condition bits.
 
  // If the N and U bits get set, then the resultant comparison DOES suddenly
  // care about orderedness, and it is true when ordered.
  if (Op > ISD::SETTRUE2)
    Op &= ~16;     // Clear the U bit if the N bit is set.
 
  // Canonicalize illegal integer setcc's.
  if (IsInteger && Op == ISD::SETUNE)  // e.g. SETUGT | SETULT
    Op = ISD::SETNE;
 
  return ISD::CondCode(Op);
}
 
ISD::CondCode ISD::getSetCCAndOperation(ISD::CondCode Op1, ISD::CondCode Op2,
                                        EVT Type) {
  bool IsInteger = Type.isInteger();
  if (IsInteger && (isSignedOp(Op1) | isSignedOp(Op2)) == 3)
    // Cannot fold a signed setcc with an unsigned setcc.
    return ISD::SETCC_INVALID;
 
  // Combine all of the condition bits.
  ISD::CondCode Result = ISD::CondCode(Op1 & Op2);
 
  // Canonicalize illegal integer setcc's.
  if (IsInteger) {
    switch (Result) {
    default: break;
    case ISD::SETUO : Result = ISD::SETFALSE; break;  // SETUGT & SETULT
    case ISD::SETOEQ:                                 // SETEQ  & SETU[LG]E
    case ISD::SETUEQ: Result = ISD::SETEQ   ; break;  // SETUGE & SETULE
    case ISD::SETOLT: Result = ISD::SETULT  ; break;  // SETULT & SETNE
    case ISD::SETOGT: Result = ISD::SETUGT  ; break;  // SETUGT & SETNE
    }
  }
 
  return Result;
}
 
//===----------------------------------------------------------------------===//
//                           SDNode Profile Support
//===----------------------------------------------------------------------===//
 
/// AddNodeIDOpcode - Add the node opcode to the NodeID data.
static void AddNodeIDOpcode(FoldingSetNodeID &ID, unsigned OpC)  {
  ID.AddInteger(OpC);
}
 
/// AddNodeIDValueTypes - Value type lists are intern'd so we can represent them
/// solely with their pointer.
static void AddNodeIDValueTypes(FoldingSetNodeID &ID, SDVTList VTList) {
  ID.AddPointer(VTList.VTs);
}
 
/// AddNodeIDOperands - Various routines for adding operands to the NodeID data.
static void AddNodeIDOperands(FoldingSetNodeID &ID,
                              ArrayRef<SDValue> Ops) {
  for (const auto &Op : Ops) {
    ID.AddPointer(Op.getNode());
    ID.AddInteger(Op.getResNo());
  }
}
 
/// AddNodeIDOperands - Various routines for adding operands to the NodeID data.
static void AddNodeIDOperands(FoldingSetNodeID &ID,
                              ArrayRef<SDUse> Ops) {
  for (const auto &Op : Ops) {
    ID.AddPointer(Op.getNode());
    ID.AddInteger(Op.getResNo());
  }
}
 
static void AddNodeIDNode(FoldingSetNodeID &ID, unsigned OpC,
                          SDVTList VTList, ArrayRef<SDValue> OpList) {
  AddNodeIDOpcode(ID, OpC);
  AddNodeIDValueTypes(ID, VTList);
  AddNodeIDOperands(ID, OpList);
}
 
/// If this is an SDNode with special info, add this info to the NodeID data.
static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
  switch (N->getOpcode()) {
  case ISD::TargetExternalSymbol:
  case ISD::ExternalSymbol:
  case ISD::MCSymbol:
    llvm_unreachable("Should only be used on nodes with operands");
  default: break;  // Normal nodes don't need extra info.
  case ISD::TargetConstant:
  case ISD::Constant: {
    const ConstantSDNode *C = cast<ConstantSDNode>(N);
    ID.AddPointer(C->getConstantIntValue());
    ID.AddBoolean(C->isOpaque());
    break;
  }
  case ISD::TargetConstantFP:
  case ISD::ConstantFP:
    ID.AddPointer(cast<ConstantFPSDNode>(N)->getConstantFPValue());
    break;
  case ISD::TargetGlobalAddress:
  case ISD::GlobalAddress:
  case ISD::TargetGlobalTLSAddress:
  case ISD::GlobalTLSAddress: {
    const GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(N);
    ID.AddPointer(GA->getGlobal());
    ID.AddInteger(GA->getOffset());
    ID.AddInteger(GA->getTargetFlags());
    break;
  }
  case ISD::BasicBlock:
    ID.AddPointer(cast<BasicBlockSDNode>(N)->getBasicBlock());
    break;
  case ISD::Register:
    ID.AddInteger(cast<RegisterSDNode>(N)->getReg().id());
    break;
  case ISD::RegisterMask:
    ID.AddPointer(cast<RegisterMaskSDNode>(N)->getRegMask());
    break;
  case ISD::SRCVALUE:
    ID.AddPointer(cast<SrcValueSDNode>(N)->getValue());
    break;
  case ISD::FrameIndex:
  case ISD::TargetFrameIndex:
    ID.AddInteger(cast<FrameIndexSDNode>(N)->getIndex());
    break;
  case ISD::PSEUDO_PROBE:
    ID.AddInteger(cast<PseudoProbeSDNode>(N)->getGuid());
    ID.AddInteger(cast<PseudoProbeSDNode>(N)->getIndex());
    ID.AddInteger(cast<PseudoProbeSDNode>(N)->getAttributes());
    break;
  case ISD::JumpTable:
  case ISD::TargetJumpTable:
    ID.AddInteger(cast<JumpTableSDNode>(N)->getIndex());
    ID.AddInteger(cast<JumpTableSDNode>(N)->getTargetFlags());
    break;
  case ISD::ConstantPool:
  case ISD::TargetConstantPool: {
    const ConstantPoolSDNode *CP = cast<ConstantPoolSDNode>(N);
    ID.AddInteger(CP->getAlign().value());
    ID.AddInteger(CP->getOffset());
    if (CP->isMachineConstantPoolEntry())
      CP->getMachineCPVal()->addSelectionDAGCSEId(ID);
    else
      ID.AddPointer(CP->getConstVal());
    ID.AddInteger(CP->getTargetFlags());
    break;
  }
  case ISD::TargetIndex: {
    const TargetIndexSDNode *TI = cast<TargetIndexSDNode>(N);
    ID.AddInteger(TI->getIndex());
    ID.AddInteger(TI->getOffset());
    ID.AddInteger(TI->getTargetFlags());
    break;
  }
  case ISD::LOAD: {
    const LoadSDNode *LD = cast<LoadSDNode>(N);
    ID.AddInteger(LD->getMemoryVT().getRawBits());
    ID.AddInteger(LD->getRawSubclassData());
    ID.AddInteger(LD->getPointerInfo().getAddrSpace());
    ID.AddInteger(LD->getMemOperand()->getFlags());
    break;
  }
  case ISD::STORE: {
    const StoreSDNode *ST = cast<StoreSDNode>(N);
    ID.AddInteger(ST->getMemoryVT().getRawBits());
    ID.AddInteger(ST->getRawSubclassData());
    ID.AddInteger(ST->getPointerInfo().getAddrSpace());
    ID.AddInteger(ST->getMemOperand()->getFlags());
    break;
  }
  case ISD::VP_LOAD: {
    const VPLoadSDNode *ELD = cast<VPLoadSDNode>(N);
    ID.AddInteger(ELD->getMemoryVT().getRawBits());
    ID.AddInteger(ELD->getRawSubclassData());
    ID.AddInteger(ELD->getPointerInfo().getAddrSpace());
    ID.AddInteger(ELD->getMemOperand()->getFlags());
    break;
  }
  case ISD::VP_LOAD_FF: {
    const auto *LD = cast<VPLoadFFSDNode>(N);
    ID.AddInteger(LD->getMemoryVT().getRawBits());
    ID.AddInteger(LD->getRawSubclassData());
    ID.AddInteger(LD->getPointerInfo().getAddrSpace());
    ID.AddInteger(LD->getMemOperand()->getFlags());
    break;
  }
  case ISD::VP_STORE: {
    const VPStoreSDNode *EST = cast<VPStoreSDNode>(N);
    ID.AddInteger(EST->getMemoryVT().getRawBits());
    ID.AddInteger(EST->getRawSubclassData());
    ID.AddInteger(EST->getPointerInfo().getAddrSpace());
    ID.AddInteger(EST->getMemOperand()->getFlags());
    break;
  }
  case ISD::EXPERIMENTAL_VP_STRIDED_LOAD: {
    const VPStridedLoadSDNode *SLD = cast<VPStridedLoadSDNode>(N);
    ID.AddInteger(SLD->getMemoryVT().getRawBits());
    ID.AddInteger(SLD->getRawSubclassData());
    ID.AddInteger(SLD->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::EXPERIMENTAL_VP_STRIDED_STORE: {
    const VPStridedStoreSDNode *SST = cast<VPStridedStoreSDNode>(N);
    ID.AddInteger(SST->getMemoryVT().getRawBits());
    ID.AddInteger(SST->getRawSubclassData());
    ID.AddInteger(SST->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::VP_GATHER: {
    const VPGatherSDNode *EG = cast<VPGatherSDNode>(N);
    ID.AddInteger(EG->getMemoryVT().getRawBits());
    ID.AddInteger(EG->getRawSubclassData());
    ID.AddInteger(EG->getPointerInfo().getAddrSpace());
    ID.AddInteger(EG->getMemOperand()->getFlags());
    break;
  }
  case ISD::VP_SCATTER: {
    const VPScatterSDNode *ES = cast<VPScatterSDNode>(N);
    ID.AddInteger(ES->getMemoryVT().getRawBits());
    ID.AddInteger(ES->getRawSubclassData());
    ID.AddInteger(ES->getPointerInfo().getAddrSpace());
    ID.AddInteger(ES->getMemOperand()->getFlags());
    break;
  }
  case ISD::MLOAD: {
    const MaskedLoadSDNode *MLD = cast<MaskedLoadSDNode>(N);
    ID.AddInteger(MLD->getMemoryVT().getRawBits());
    ID.AddInteger(MLD->getRawSubclassData());
    ID.AddInteger(MLD->getPointerInfo().getAddrSpace());
    ID.AddInteger(MLD->getMemOperand()->getFlags());
    break;
  }
  case ISD::MSTORE: {
    const MaskedStoreSDNode *MST = cast<MaskedStoreSDNode>(N);
    ID.AddInteger(MST->getMemoryVT().getRawBits());
    ID.AddInteger(MST->getRawSubclassData());
    ID.AddInteger(MST->getPointerInfo().getAddrSpace());
    ID.AddInteger(MST->getMemOperand()->getFlags());
    break;
  }
  case ISD::MGATHER: {
    const MaskedGatherSDNode *MG = cast<MaskedGatherSDNode>(N);
    ID.AddInteger(MG->getMemoryVT().getRawBits());
    ID.AddInteger(MG->getRawSubclassData());
    ID.AddInteger(MG->getPointerInfo().getAddrSpace());
    ID.AddInteger(MG->getMemOperand()->getFlags());
    break;
  }
  case ISD::MSCATTER: {
    const MaskedScatterSDNode *MS = cast<MaskedScatterSDNode>(N);
    ID.AddInteger(MS->getMemoryVT().getRawBits());
    ID.AddInteger(MS->getRawSubclassData());
    ID.AddInteger(MS->getPointerInfo().getAddrSpace());
    ID.AddInteger(MS->getMemOperand()->getFlags());
    break;
  }
  case ISD::ATOMIC_CMP_SWAP:
  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
  case ISD::ATOMIC_SWAP:
  case ISD::ATOMIC_LOAD_ADD:
  case ISD::ATOMIC_LOAD_SUB:
  case ISD::ATOMIC_LOAD_AND:
  case ISD::ATOMIC_LOAD_CLR:
  case ISD::ATOMIC_LOAD_OR:
  case ISD::ATOMIC_LOAD_XOR:
  case ISD::ATOMIC_LOAD_NAND:
  case ISD::ATOMIC_LOAD_MIN:
  case ISD::ATOMIC_LOAD_MAX:
  case ISD::ATOMIC_LOAD_UMIN:
  case ISD::ATOMIC_LOAD_UMAX:
  case ISD::ATOMIC_LOAD:
  case ISD::ATOMIC_STORE: {
    const AtomicSDNode *AT = cast<AtomicSDNode>(N);
    ID.AddInteger(AT->getMemoryVT().getRawBits());
    ID.AddInteger(AT->getRawSubclassData());
    ID.AddInteger(AT->getPointerInfo().getAddrSpace());
    ID.AddInteger(AT->getMemOperand()->getFlags());
    break;
  }
  case ISD::VECTOR_SHUFFLE: {
    ArrayRef<int> Mask = cast<ShuffleVectorSDNode>(N)->getMask();
    for (int M : Mask)
      ID.AddInteger(M);
    break;
  }
  case ISD::ADDRSPACECAST: {
    const AddrSpaceCastSDNode *ASC = cast<AddrSpaceCastSDNode>(N);
    ID.AddInteger(ASC->getSrcAddressSpace());
    ID.AddInteger(ASC->getDestAddressSpace());
    break;
  }
  case ISD::TargetBlockAddress:
  case ISD::BlockAddress: {
    const BlockAddressSDNode *BA = cast<BlockAddressSDNode>(N);
    ID.AddPointer(BA->getBlockAddress());
    ID.AddInteger(BA->getOffset());
    ID.AddInteger(BA->getTargetFlags());
    break;
  }
  case ISD::AssertAlign:
    ID.AddInteger(cast<AssertAlignSDNode>(N)->getAlign().value());
    break;
  case ISD::PREFETCH:
  case ISD::INTRINSIC_VOID:
  case ISD::INTRINSIC_W_CHAIN:
    // Handled by MemIntrinsicSDNode check after the switch.
    break;
  case ISD::MDNODE_SDNODE:
    ID.AddPointer(cast<MDNodeSDNode>(N)->getMD());
    break;
  } // end switch (N->getOpcode())
 
  // MemIntrinsic nodes could also have subclass data, address spaces, and flags
  // to check.
  if (auto *MN = dyn_cast<MemIntrinsicSDNode>(N)) {
    ID.AddInteger(MN->getRawSubclassData());
    ID.AddInteger(MN->getMemoryVT().getRawBits());
    for (const MachineMemOperand *MMO : MN->memoperands()) {
      ID.AddInteger(MMO->getPointerInfo().getAddrSpace());
      ID.AddInteger(MMO->getFlags());
    }
  }
}
 
/// AddNodeIDNode - Generic routine for adding a nodes info to the NodeID
/// data.
static void AddNodeIDNode(FoldingSetNodeID &ID, const SDNode *N) {
  AddNodeIDOpcode(ID, N->getOpcode());
  // Add the return value info.
  AddNodeIDValueTypes(ID, N->getVTList());
  // Add the operand info.
  AddNodeIDOperands(ID, N->ops());
 
  // Handle SDNode leafs with special info.
  AddNodeIDCustom(ID, N);
}
 
//===----------------------------------------------------------------------===//
//                              SelectionDAG Class
//===----------------------------------------------------------------------===//
 
/// doNotCSE - Return true if CSE should not be performed for this node.
static bool doNotCSE(SDNode *N) {
  if (N->getValueType(0) == MVT::Glue)
    return true; // Never CSE anything that produces a glue result.
 
  switch (N->getOpcode()) {
  default: break;
  case ISD::HANDLENODE:
  case ISD::EH_LABEL:
    return true;   // Never CSE these nodes.
  }
 
  // Check that remaining values produced are not flags.
  for (unsigned i = 1, e = N->getNumValues(); i != e; ++i)
    if (N->getValueType(i) == MVT::Glue)
      return true; // Never CSE anything that produces a glue result.
 
  return false;
}
 
/// Construct a DemandedElts mask which demands all elements of \p V.
/// If \p V is not a fixed-length vector, then this will return a single bit.
static APInt getDemandAllEltsMask(SDValue V) {
  EVT VT = V.getValueType();
  // Since the number of lanes in a scalable vector is unknown at compile time,
  // we track one bit which is implicitly broadcast to all lanes.  This means
  // that all lanes in a scalable vector are considered demanded.
  return VT.isFixedLengthVector() ? APInt::getAllOnes(VT.getVectorNumElements())
                                  : APInt(1, 1);
}
 
/// RemoveDeadNodes - This method deletes all unreachable nodes in the
/// SelectionDAG.
void SelectionDAG::RemoveDeadNodes() {
  // Create a dummy node (which is not added to allnodes), that adds a reference
  // to the root node, preventing it from being deleted.
  HandleSDNode Dummy(getRoot());
 
  SmallVector<SDNode*, 128> DeadNodes;
 
  // Add all obviously-dead nodes to the DeadNodes worklist.
  for (SDNode &Node : allnodes())
    if (Node.use_empty())
      DeadNodes.push_back(&Node);
 
  RemoveDeadNodes(DeadNodes);
 
  // If the root changed (e.g. it was a dead load, update the root).
  setRoot(Dummy.getValue());
}
 
/// RemoveDeadNodes - This method deletes the unreachable nodes in the
/// given list, and any nodes that become unreachable as a result.
void SelectionDAG::RemoveDeadNodes(SmallVectorImpl<SDNode *> &DeadNodes) {
 
  // Process the worklist, deleting the nodes and adding their uses to the
  // worklist.
  while (!DeadNodes.empty()) {
    SDNode *N = DeadNodes.pop_back_val();
    // Skip to next node if we've already managed to delete the node. This could
    // happen if replacing a node causes a node previously added to the node to
    // be deleted.
    if (N->getOpcode() == ISD::DELETED_NODE)
      continue;
 
    for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
      DUL->NodeDeleted(N, nullptr);
 
    // Take the node out of the appropriate CSE map.
    RemoveNodeFromCSEMaps(N);
 
    // Next, brutally remove the operand list.  This is safe to do, as there are
    // no cycles in the graph.
    for (SDNode::op_iterator I = N->op_begin(), E = N->op_end(); I != E; ) {
      SDUse &Use = *I++;
      SDNode *Operand = Use.getNode();
      Use.set(SDValue());
 
      // Now that we removed this operand, see if there are no uses of it left.
      if (Operand->use_empty())
        DeadNodes.push_back(Operand);
    }
 
    DeallocateNode(N);
  }
}
 
void SelectionDAG::RemoveDeadNode(SDNode *N){
  SmallVector<SDNode*, 16> DeadNodes(1, N);
 
  // Create a dummy node that adds a reference to the root node, preventing
  // it from being deleted.  (This matters if the root is an operand of the
  // dead node.)
  HandleSDNode Dummy(getRoot());
 
  RemoveDeadNodes(DeadNodes);
}
 
void SelectionDAG::DeleteNode(SDNode *N) {
  // First take this out of the appropriate CSE map.
  RemoveNodeFromCSEMaps(N);
 
  // Finally, remove uses due to operands of this node, remove from the
  // AllNodes list, and delete the node.
  DeleteNodeNotInCSEMaps(N);
}
 
void SelectionDAG::DeleteNodeNotInCSEMaps(SDNode *N) {
  assert(N->getIterator() != AllNodes.begin() &&
         "Cannot delete the entry node!");
  assert(N->use_empty() && "Cannot delete a node that is not dead!");
 
  // Drop all of the operands and decrement used node's use counts.
  N->DropOperands();
 
  DeallocateNode(N);
}
 
void SDDbgInfo::add(SDDbgValue *V, bool isParameter) {
  assert(!(V->isVariadic() && isParameter));
  if (isParameter)
    ByvalParmDbgValues.push_back(V);
  else
    DbgValues.push_back(V);
  for (const SDNode *Node : V->getSDNodes())
    if (Node)
      DbgValMap[Node].push_back(V);
}
 
void SDDbgInfo::erase(const SDNode *Node) {
  DbgValMapType::iterator I = DbgValMap.find(Node);
  if (I == DbgValMap.end())
    return;
  for (auto &Val: I->second)
    Val->setIsInvalidated();
  DbgValMap.erase(I);
}
 
void SelectionDAG::DeallocateNode(SDNode *N) {
  // If we have operands, deallocate them.
  removeOperands(N);
 
  NodeAllocator.Deallocate(AllNodes.remove(N));
 
  // Set the opcode to DELETED_NODE to help catch bugs when node
  // memory is reallocated.
  // FIXME: There are places in SDag that have grown a dependency on the opcode
  // value in the released node.
  __asan_unpoison_memory_region(&N->NodeType, sizeof(N->NodeType));
  N->NodeType = ISD::DELETED_NODE;
 
  // If any of the SDDbgValue nodes refer to this SDNode, invalidate
  // them and forget about that node.
  DbgInfo->erase(N);
 
  // Invalidate extra info.
  SDEI.erase(N);
}
 
#ifndef NDEBUG
/// VerifySDNode - Check the given SDNode.  Aborts if it is invalid.
void SelectionDAG::verifyNode(SDNode *N) const {
  switch (N->getOpcode()) {
  default:
    if (N->isTargetOpcode())
      getSelectionDAGInfo().verifyTargetNode(*this, N);
    break;
  case ISD::BUILD_PAIR: {
    EVT VT = N->getValueType(0);
    assert(N->getNumValues() == 1 && "Too many results!");
    assert(!VT.isVector() && (VT.isInteger() || VT.isFloatingPoint()) &&
           "Wrong return type!");
    assert(N->getNumOperands() == 2 && "Wrong number of operands!");
    assert(N->getOperand(0).getValueType() == N->getOperand(1).getValueType() &&
           "Mismatched operand types!");
    assert(N->getOperand(0).getValueType().isInteger() == VT.isInteger() &&
           "Wrong operand type!");
    assert(VT.getSizeInBits() == 2 * N->getOperand(0).getValueSizeInBits() &&
           "Wrong return type size");
    break;
  }
  case ISD::BUILD_VECTOR: {
    assert(N->getNumValues() == 1 && "Too many results!");
    assert(N->getValueType(0).isVector() && "Wrong return type!");
    assert(N->getNumOperands() == N->getValueType(0).getVectorNumElements() &&
           "Wrong number of operands!");
    EVT EltVT = N->getValueType(0).getVectorElementType();
    for (const SDUse &Op : N->ops()) {
      assert((Op.getValueType() == EltVT ||
              (EltVT.isInteger() && Op.getValueType().isInteger() &&
               EltVT.bitsLE(Op.getValueType()))) &&
             "Wrong operand type!");
      assert(Op.getValueType() == N->getOperand(0).getValueType() &&
             "Operands must all have the same type");
    }
    break;
  }
  case ISD::SADDO:
  case ISD::UADDO:
  case ISD::SSUBO:
  case ISD::USUBO:
    assert(N->getNumValues() == 2 && "Wrong number of results!");
    assert(N->getVTList().NumVTs == 2 && N->getNumOperands() == 2 &&
           "Invalid add/sub overflow op!");
    assert(N->getVTList().VTs[0].isInteger() &&
           N->getVTList().VTs[1].isInteger() &&
           N->getOperand(0).getValueType() == N->getOperand(1).getValueType() &&
           N->getOperand(0).getValueType() == N->getVTList().VTs[0] &&
           "Binary operator types must match!");
    break;
  }
}
#endif // NDEBUG
 
/// Insert a newly allocated node into the DAG.
///
/// Handles insertion into the all nodes list and CSE map, as well as
/// verification and other common operations when a new node is allocated.
void SelectionDAG::InsertNode(SDNode *N) {
  AllNodes.push_back(N);
#ifndef NDEBUG
  N->PersistentId = NextPersistentId++;
  verifyNode(N);
#endif
  for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
    DUL->NodeInserted(N);
}
 
/// RemoveNodeFromCSEMaps - Take the specified node out of the CSE map that
/// correspond to it.  This is useful when we're about to delete or repurpose
/// the node.  We don't want future request for structurally identical nodes
/// to return N anymore.
bool SelectionDAG::RemoveNodeFromCSEMaps(SDNode *N) {
  bool Erased = false;
  switch (N->getOpcode()) {
  case ISD::HANDLENODE: return false;  // noop.
  case ISD::CONDCODE:
    assert(CondCodeNodes[cast<CondCodeSDNode>(N)->get()] &&
           "Cond code doesn't exist!");
    Erased = CondCodeNodes[cast<CondCodeSDNode>(N)->get()] != nullptr;
    CondCodeNodes[cast<CondCodeSDNode>(N)->get()] = nullptr;
    break;
  case ISD::ExternalSymbol:
    Erased = ExternalSymbols.erase(cast<ExternalSymbolSDNode>(N)->getSymbol());
    break;
  case ISD::TargetExternalSymbol: {
    ExternalSymbolSDNode *ESN = cast<ExternalSymbolSDNode>(N);
    Erased = TargetExternalSymbols.erase(std::pair<std::string, unsigned>(
        ESN->getSymbol(), ESN->getTargetFlags()));
    break;
  }
  case ISD::MCSymbol: {
    auto *MCSN = cast<MCSymbolSDNode>(N);
    Erased = MCSymbols.erase(MCSN->getMCSymbol());
    break;
  }
  case ISD::VALUETYPE: {
    EVT VT = cast<VTSDNode>(N)->getVT();
    if (VT.isExtended()) {
      Erased = ExtendedValueTypeNodes.erase(VT);
    } else {
      Erased = ValueTypeNodes[VT.getSimpleVT().SimpleTy] != nullptr;
      ValueTypeNodes[VT.getSimpleVT().SimpleTy] = nullptr;
    }
    break;
  }
  default:
    // Remove it from the CSE Map.
    assert(N->getOpcode() != ISD::DELETED_NODE && "DELETED_NODE in CSEMap!");
    assert(N->getOpcode() != ISD::EntryToken && "EntryToken in CSEMap!");
    Erased = CSEMap.erase(N);
    break;
  }
#ifndef NDEBUG
  // Verify that the node was actually in one of the CSE maps, unless it has a
  // glue result (which cannot be CSE'd) or is one of the special cases that are
  // not subject to CSE.
  if (!Erased && N->getValueType(N->getNumValues()-1) != MVT::Glue &&
      !N->isMachineOpcode() && !doNotCSE(N)) {
    N->dump(this);
    dbgs() << "\n";
    llvm_unreachable("Node is not in map!");
  }
#endif
  return Erased;
}
 
/// AddModifiedNodeToCSEMaps - The specified node has been removed from the CSE
/// maps and modified in place. Add it back to the CSE maps, unless an identical
/// node already exists, in which case transfer all its users to the existing
/// node. This transfer can potentially trigger recursive merging.
void
SelectionDAG::AddModifiedNodeToCSEMaps(SDNode *N) {
  // For node types that aren't CSE'd, just act as if no identical node
  // already exists.
  if (!doNotCSE(N)) {
    SDNode *Existing = CSEMap.getOrInsert(N);
    if (Existing != N) {
      // If there was already an existing matching node, use ReplaceAllUsesWith
      // to replace the dead one with the existing one.  This can cause
      // recursive merging of other unrelated nodes down the line.
      Existing->intersectFlagsWith(N->getFlags());
      if (auto *MemNode = dyn_cast<MemSDNode>(Existing)) {
        ArrayRef<MachineMemOperand *> NewMMOs =
            cast<MemSDNode>(N)->memoperands();
        // Range and cache hint metadata are not part of the DAG CSE key because
        // we prefer to CSE even when metadata does not match. Merge potentially
        // differing metadata conservatively.
        MemNode->refineMMOMetadata(NewMMOs);
      }
      ReplaceAllUsesWith(N, Existing);
 
      // N is now dead. Inform the listeners and delete it.
      for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
        DUL->NodeDeleted(N, Existing);
      DeleteNodeNotInCSEMaps(N);
      return;
    }
  }
 
  // If the node doesn't already exist, we updated it.  Inform listeners.
  for (DAGUpdateListener *DUL = UpdateListeners; DUL; DUL = DUL->Next)
    DUL->NodeUpdated(N);
}
 
/// FindModifiedNodeSlot - Find a slot for the specified node if its operands
/// were replaced with those specified.  If this node is never memoized,
/// return null, otherwise return a pointer to the slot it would take.  If a
/// node already exists with these operands, the slot will be non-null.
SDNode *SelectionDAG::FindModifiedNodeSlot(SDNode *N, SDValue Op,
                                           FoldingSetInsertToken &InsertToken) {
  if (doNotCSE(N))
    return nullptr;
 
  SDValue Ops[] = { Op };
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = lookupNode(ID, SDLoc(N), InsertToken);
  if (Node)
    Node->intersectFlagsWith(N->getFlags());
  return Node;
}
 
/// FindModifiedNodeSlot - Find a slot for the specified node if its operands
/// were replaced with those specified.  If this node is never memoized,
/// return null, otherwise return a pointer to the slot it would take.  If a
/// node already exists with these operands, the slot will be non-null.
SDNode *SelectionDAG::FindModifiedNodeSlot(SDNode *N, SDValue Op1, SDValue Op2,
                                           FoldingSetInsertToken &InsertToken) {
  if (doNotCSE(N))
    return nullptr;
 
  SDValue Ops[] = { Op1, Op2 };
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = lookupNode(ID, SDLoc(N), InsertToken);
  if (Node)
    Node->intersectFlagsWith(N->getFlags());
  return Node;
}
 
/// FindModifiedNodeSlot - Find a slot for the specified node if its operands
/// were replaced with those specified.  If this node is never memoized,
/// return null, otherwise return a pointer to the slot it would take.  If a
/// node already exists with these operands, the slot will be non-null.
SDNode *SelectionDAG::FindModifiedNodeSlot(SDNode *N, ArrayRef<SDValue> Ops,
                                           FoldingSetInsertToken &InsertToken) {
  if (doNotCSE(N))
    return nullptr;
 
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = lookupNode(ID, SDLoc(N), InsertToken);
  if (Node)
    Node->intersectFlagsWith(N->getFlags());
  return Node;
}
 
Align SelectionDAG::getEVTAlign(EVT VT) const {
  Type *Ty = VT == MVT::iPTR ? PointerType::get(*getContext(), 0)
                             : VT.getTypeForEVT(*getContext());
 
  return getDataLayout().getABITypeAlign(Ty);
}
 
// EntryNode could meaningfully have debug info if we can find it...
SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOptLevel OL)
    : TM(tm), OptLevel(OL), EntryNode(ISD::EntryToken, 0, DebugLoc(),
                                      getVTList(MVT::Other, MVT::Glue)),
      Root(getEntryNode()) {
  InsertNode(&EntryNode);
  DbgInfo = new SDDbgInfo();
}
 
void SelectionDAG::init(MachineFunction &NewMF,
                        OptimizationRemarkEmitter &NewORE, Pass *PassPtr,
                        const TargetLibraryInfo *LibraryInfo,
                        const LibcallLoweringInfo *LibcallsInfo,
                        UniformityInfo *NewUA, ProfileSummaryInfo *PSIin,
                        BlockFrequencyInfo *BFIin, MachineModuleInfo &MMIin,
                        FunctionVarLocs const *VarLocs) {
  MF = &NewMF;
  SDAGISelPass = PassPtr;
  ORE = &NewORE;
  TLI = getSubtarget().getTargetLowering();
  TSI = getSubtarget().getSelectionDAGInfo();
  LibInfo = LibraryInfo;
  Libcalls = LibcallsInfo;
  Context = &MF->getFunction().getContext();
  UA = NewUA;
  PSI = PSIin;
  BFI = BFIin;
  MMI = &MMIin;
  FnVarLocs = VarLocs;
}
 
SelectionDAG::~SelectionDAG() {
  assert(!UpdateListeners && "Dangling registered DAGUpdateListeners");
  allnodes_clear();
  OperandRecycler.clear(OperandAllocator);
  delete DbgInfo;
}
 
bool SelectionDAG::shouldOptForSize() const {
  return llvm::shouldOptimizeForSize(FLI->MBB->getBasicBlock(), PSI, BFI);
}
 
void SelectionDAG::allnodes_clear() {
  assert(&*AllNodes.begin() == &EntryNode);
  AllNodes.remove(AllNodes.begin());
  while (!AllNodes.empty())
    DeallocateNode(&AllNodes.front());
#ifndef NDEBUG
  NextPersistentId = 0;
#endif
}
 
SDNode *SelectionDAG::lookupNode(const FoldingSetNodeID &ID,
                                 FoldingSetInsertToken &InsertToken) {
  SDNode *N = CSEMap.lookup(ID, InsertToken);
  if (N) {
    switch (N->getOpcode()) {
    default: break;
    case ISD::Constant:
    case ISD::ConstantFP:
      llvm_unreachable("Querying for Constant and ConstantFP nodes requires "
                       "debug location.  Use another overload.");
    }
  }
  return N;
}
 
SDNode *SelectionDAG::lookupNode(const FoldingSetNodeID &ID, const SDLoc &DL,
                                 FoldingSetInsertToken &InsertToken) {
  SDNode *N = CSEMap.lookup(ID, InsertToken);
  if (N) {
    switch (N->getOpcode()) {
    case ISD::Constant:
    case ISD::ConstantFP:
      // Erase debug location from the node if the node is used at several
      // different places. Do not propagate one location to all uses as it
      // will cause a worse single stepping debugging experience.
      if (N->getDebugLoc() != DL.getDebugLoc())
        N->setDebugLoc(DebugLoc());
      break;
    default:
      // When the node's point of use is located earlier in the instruction
      // sequence than its prior point of use, update its debug info to the
      // earlier location.
      if (DL.getIROrder() && DL.getIROrder() < N->getIROrder())
        N->setDebugLoc(DL.getDebugLoc());
      break;
    }
  }
  return N;
}
 
void SelectionDAG::clear() {
  allnodes_clear();
  OperandRecycler.clear(OperandAllocator);
  OperandAllocator.Reset();
  CSEMap.clear();
 
  ExtendedValueTypeNodes.clear();
  ExternalSymbols.clear();
  TargetExternalSymbols.clear();
  MCSymbols.clear();
  SDEI.clear();
  llvm::fill(CondCodeNodes, nullptr);
  llvm::fill(ValueTypeNodes, nullptr);
 
  EntryNode.UseList = nullptr;
  InsertNode(&EntryNode);
  Root = getEntryNode();
  DbgInfo->clear();
}
 
SDValue SelectionDAG::getFPExtendOrRound(SDValue Op, const SDLoc &DL, EVT VT) {
  return VT.bitsGT(Op.getValueType())
             ? getNode(ISD::FP_EXTEND, DL, VT, Op)
             : getNode(ISD::FP_ROUND, DL, VT, Op,
                       getIntPtrConstant(0, DL, /*isTarget=*/true));
}
 
std::pair<SDValue, SDValue>
SelectionDAG::getStrictFPExtendOrRound(SDValue Op, SDValue Chain,
                                       const SDLoc &DL, EVT VT) {
  assert(!VT.bitsEq(Op.getValueType()) &&
         "Strict no-op FP extend/round not allowed.");
  SDValue Res =
      VT.bitsGT(Op.getValueType())
          ? getNode(ISD::STRICT_FP_EXTEND, DL, {VT, MVT::Other}, {Chain, Op})
          : getNode(ISD::STRICT_FP_ROUND, DL, {VT, MVT::Other},
                    {Chain, Op, getIntPtrConstant(0, DL, /*isTarget=*/true)});
 
  return std::pair<SDValue, SDValue>(Res, SDValue(Res.getNode(), 1));
}
 
SDValue SelectionDAG::getAnyExtOrTrunc(SDValue Op, const SDLoc &DL, EVT VT) {
  return VT.bitsGT(Op.getValueType()) ?
    getNode(ISD::ANY_EXTEND, DL, VT, Op) :
    getNode(ISD::TRUNCATE, DL, VT, Op);
}
 
SDValue SelectionDAG::getSExtOrTrunc(SDValue Op, const SDLoc &DL, EVT VT) {
  return VT.bitsGT(Op.getValueType()) ?
    getNode(ISD::SIGN_EXTEND, DL, VT, Op) :
    getNode(ISD::TRUNCATE, DL, VT, Op);
}
 
SDValue SelectionDAG::getZExtOrTrunc(SDValue Op, const SDLoc &DL, EVT VT) {
  return VT.bitsGT(Op.getValueType()) ?
    getNode(ISD::ZERO_EXTEND, DL, VT, Op) :
    getNode(ISD::TRUNCATE, DL, VT, Op);
}
 
SDValue SelectionDAG::getBitcastedAnyExtOrTrunc(SDValue Op, const SDLoc &DL,
                                                EVT VT) {
  assert(!VT.isVector());
  auto Type = Op.getValueType();
  SDValue DestOp;
  if (Type == VT)
    return Op;
  auto Size = Op.getValueSizeInBits();
  DestOp = getBitcast(EVT::getIntegerVT(*Context, Size), Op);
  if (DestOp.getValueType() == VT)
    return DestOp;
 
  return getAnyExtOrTrunc(DestOp, DL, VT);
}
 
SDValue SelectionDAG::getBitcastedSExtOrTrunc(SDValue Op, const SDLoc &DL,
                                               EVT VT) {
  assert(!VT.isVector());
  auto Type = Op.getValueType();
  SDValue DestOp;
  if (Type == VT)
    return Op;
  auto Size = Op.getValueSizeInBits();
  DestOp = getBitcast(MVT::getIntegerVT(Size), Op);
  if (DestOp.getValueType() == VT)
    return DestOp;
 
  return getSExtOrTrunc(DestOp, DL, VT);
}
 
SDValue SelectionDAG::getBitcastedZExtOrTrunc(SDValue Op, const SDLoc &DL,
                                               EVT VT) {
  assert(!VT.isVector());
  auto Type = Op.getValueType();
  SDValue DestOp;
  if (Type == VT)
    return Op;
  auto Size = Op.getValueSizeInBits();
  DestOp = getBitcast(MVT::getIntegerVT(Size), Op);
  if (DestOp.getValueType() == VT)
    return DestOp;
 
  return getZExtOrTrunc(DestOp, DL, VT);
}
 
SDValue SelectionDAG::getBoolExtOrTrunc(SDValue Op, const SDLoc &SL, EVT VT,
                                        EVT OpVT) {
  if (VT.bitsLE(Op.getValueType()))
    return getNode(ISD::TRUNCATE, SL, VT, Op);
 
  TargetLowering::BooleanContent BType = TLI->getBooleanContents(OpVT);
  return getNode(TLI->getExtendForContent(BType), SL, VT, Op);
}
 
SDValue SelectionDAG::getZeroExtendInReg(SDValue Op, const SDLoc &DL, EVT VT) {
  EVT OpVT = Op.getValueType();
  assert(VT.isInteger() && OpVT.isInteger() &&
         "Cannot getZeroExtendInReg FP types");
  assert(VT.isVector() == OpVT.isVector() &&
         "getZeroExtendInReg type should be vector iff the operand "
         "type is vector!");
  assert((!VT.isVector() ||
          VT.getVectorElementCount() == OpVT.getVectorElementCount()) &&
         "Vector element counts must match in getZeroExtendInReg");
  assert(VT.getScalarType().bitsLE(OpVT.getScalarType()) && "Not extending!");
  if (OpVT == VT)
    return Op;
  // TODO: Use computeKnownBits instead of AssertZext.
  if (Op.getOpcode() == ISD::AssertZext && cast<VTSDNode>(Op.getOperand(1))
                                               ->getVT()
                                               .getScalarType()
                                               .bitsLE(VT.getScalarType()))
    return Op;
  APInt Imm = APInt::getLowBitsSet(OpVT.getScalarSizeInBits(),
                                   VT.getScalarSizeInBits());
  return getNode(ISD::AND, DL, OpVT, Op, getConstant(Imm, DL, OpVT));
}
 
SDValue SelectionDAG::getPtrExtOrTrunc(SDValue Op, const SDLoc &DL, EVT VT) {
  // Only unsigned pointer semantics are supported right now. In the future this
  // might delegate to TLI to check pointer signedness.
  return getZExtOrTrunc(Op, DL, VT);
}
 
SDValue SelectionDAG::getPtrExtendInReg(SDValue Op, const SDLoc &DL, EVT VT) {
  // Only unsigned pointer semantics are supported right now. In the future this
  // might delegate to TLI to check pointer signedness.
  return getZeroExtendInReg(Op, DL, VT);
}
 
SDValue SelectionDAG::getNegative(SDValue Val, const SDLoc &DL, EVT VT) {
  return getNode(ISD::SUB, DL, VT, getConstant(0, DL, VT), Val);
}
 
/// getNOT - Create a bitwise NOT operation as (XOR Val, -1).
SDValue SelectionDAG::getNOT(const SDLoc &DL, SDValue Val, EVT VT) {
  return getNode(ISD::XOR, DL, VT, Val, getAllOnesConstant(DL, VT));
}
 
SDValue SelectionDAG::getLogicalNOT(const SDLoc &DL, SDValue Val, EVT VT) {
  SDValue TrueValue = getBoolConstant(true, DL, VT, VT);
  return getNode(ISD::XOR, DL, VT, Val, TrueValue);
}
 
SDValue SelectionDAG::getBoolConstant(bool V, const SDLoc &DL, EVT VT,
                                      EVT OpVT) {
  if (!V)
    return getConstant(0, DL, VT);
 
  switch (TLI->getBooleanContents(OpVT)) {
  case TargetLowering::ZeroOrOneBooleanContent:
  case TargetLowering::UndefinedBooleanContent:
    return getConstant(1, DL, VT);
  case TargetLowering::ZeroOrNegativeOneBooleanContent:
    return getAllOnesConstant(DL, VT);
  }
  llvm_unreachable("Unexpected boolean content enum!");
}
 
SDValue SelectionDAG::getConstant(uint64_t Val, const SDLoc &DL, EVT VT,
                                  bool isT, bool isO) {
  return getConstant(APInt(VT.getScalarSizeInBits(), Val, /*isSigned=*/false),
                     DL, VT, isT, isO);
}
 
SDValue SelectionDAG::getConstant(const APInt &Val, const SDLoc &DL, EVT VT,
                                  bool isT, bool isO) {
  return getConstant(*ConstantInt::get(*Context, Val), DL, VT, isT, isO);
}
 
SDValue SelectionDAG::getConstant(const ConstantInt &Val, const SDLoc &DL,
                                  EVT VT, bool isT, bool isO) {
  assert(VT.isInteger() && "Cannot create FP integer constant!");
 
  EVT EltVT = VT.getScalarType();
  const ConstantInt *Elt = &Val;
 
  // Vector splats are explicit within the DAG, with ConstantSDNode holding the
  // to-be-splatted scalar ConstantInt.
  if (isa<VectorType>(Elt->getType()))
    Elt = ConstantInt::get(*getContext(), Elt->getValue());
 
  // In some cases the vector type is legal but the element type is illegal and
  // needs to be promoted, for example v8i8 on ARM.  In this case, promote the
  // inserted value (the type does not need to match the vector element type).
  // Any extra bits introduced will be truncated away.
  if (VT.isVector() && TLI->getTypeAction(*getContext(), EltVT) ==
                           TargetLowering::TypePromoteInteger) {
    EltVT = TLI->getTypeToTransformTo(*getContext(), EltVT);
    APInt NewVal;
    if (TLI->isSExtCheaperThanZExt(VT.getScalarType(), EltVT))
      NewVal = Elt->getValue().sextOrTrunc(EltVT.getSizeInBits());
    else
      NewVal = Elt->getValue().zextOrTrunc(EltVT.getSizeInBits());
    Elt = ConstantInt::get(*getContext(), NewVal);
  }
  // In other cases the element type is illegal and needs to be expanded, for
  // example v2i64 on MIPS32. In this case, find the nearest legal type, split
  // the value into n parts and use a vector type with n-times the elements.
  // Then bitcast to the type requested.
  // Legalizing constants too early makes the DAGCombiner's job harder so we
  // only legalize if the DAG tells us we must produce legal types.
  else if (NewNodesMustHaveLegalTypes && VT.isVector() &&
           TLI->getTypeAction(*getContext(), EltVT) ==
               TargetLowering::TypeExpandInteger) {
    const APInt &NewVal = Elt->getValue();
    EVT ViaEltVT = TLI->getTypeToTransformTo(*getContext(), EltVT);
    unsigned ViaEltSizeInBits = ViaEltVT.getSizeInBits();
 
    // For scalable vectors, try to use a SPLAT_VECTOR_PARTS node.
    if (VT.isScalableVector() ||
        TLI->isOperationLegal(ISD::SPLAT_VECTOR, VT)) {
      assert(EltVT.getSizeInBits() % ViaEltSizeInBits == 0 &&
             "Can only handle an even split!");
      unsigned Parts = EltVT.getSizeInBits() / ViaEltSizeInBits;
 
      SmallVector<SDValue, 2> ScalarParts;
      for (unsigned i = 0; i != Parts; ++i)
        ScalarParts.push_back(getConstant(
            NewVal.extractBits(ViaEltSizeInBits, i * ViaEltSizeInBits), DL,
            ViaEltVT, isT, isO));
 
      return getNode(ISD::SPLAT_VECTOR_PARTS, DL, VT, ScalarParts);
    }
 
    unsigned ViaVecNumElts = VT.getSizeInBits() / ViaEltSizeInBits;
    EVT ViaVecVT = EVT::getVectorVT(*getContext(), ViaEltVT, ViaVecNumElts);
 
    // Check the temporary vector is the correct size. If this fails then
    // getTypeToTransformTo() probably returned a type whose size (in bits)
    // isn't a power-of-2 factor of the requested type size.
    assert(ViaVecVT.getSizeInBits() == VT.getSizeInBits());
 
    SmallVector<SDValue, 2> EltParts;
    for (unsigned i = 0; i < ViaVecNumElts / VT.getVectorNumElements(); ++i)
      EltParts.push_back(getConstant(
          NewVal.extractBits(ViaEltSizeInBits, i * ViaEltSizeInBits), DL,
          ViaEltVT, isT, isO));
 
    // EltParts is currently in little endian order. If we actually want
    // big-endian order then reverse it now.
    if (getDataLayout().isBigEndian())
      std::reverse(EltParts.begin(), EltParts.end());
 
    // The elements must be reversed when the element order is different
    // to the endianness of the elements (because the BITCAST is itself a
    // vector shuffle in this situation). However, we do not need any code to
    // perform this reversal because getConstant() is producing a vector
    // splat.
    // This situation occurs in MIPS MSA.
 
    SmallVector<SDValue, 8> Ops;
    for (unsigned i = 0, e = VT.getVectorNumElements(); i != e; ++i)
      llvm::append_range(Ops, EltParts);
 
    SDValue V =
        getNode(ISD::BITCAST, DL, VT, getBuildVector(ViaVecVT, DL, Ops));
    return V;
  }
 
  assert(Elt->getBitWidth() == EltVT.getSizeInBits() &&
         "APInt size does not match type size!");
  unsigned Opc = isT ? ISD::TargetConstant : ISD::Constant;
  SDVTList VTs = getVTList(EltVT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddPointer(Elt);
  ID.AddBoolean(isO);
  FoldingSetInsertToken InsertToken;
  SDNode *N = nullptr;
  if ((N = lookupNode(ID, DL, InsertToken)))
    if (!VT.isVector())
      return SDValue(N, 0);
 
  if (!N) {
    N = newSDNode<ConstantSDNode>(isT, isO, Elt, VTs);
    if (!isT)
      N->setDebugLoc(DL.getDebugLoc());
    CSEMap.insert(N, InsertToken);
    InsertNode(N);
    NewSDValueDbgMsg(SDValue(N, 0), "Creating constant: ", this);
  }
 
  SDValue Result(N, 0);
  if (VT.isVector())
    Result = getSplat(VT, DL, Result);
  return Result;
}
 
SDValue SelectionDAG::getSignedConstant(int64_t Val, const SDLoc &DL, EVT VT,
                                        bool isT, bool isO) {
  unsigned Size = VT.getScalarSizeInBits();
  return getConstant(APInt(Size, Val, /*isSigned=*/true), DL, VT, isT, isO);
}
 
SDValue SelectionDAG::getAllOnesConstant(const SDLoc &DL, EVT VT, bool IsTarget,
                                         bool IsOpaque) {
  return getConstant(APInt::getAllOnes(VT.getScalarSizeInBits()), DL, VT,
                     IsTarget, IsOpaque);
}
 
SDValue SelectionDAG::getIntPtrConstant(uint64_t Val, const SDLoc &DL,
                                        bool isTarget) {
  return getConstant(Val, DL, TLI->getPointerTy(getDataLayout()), isTarget);
}
 
SDValue SelectionDAG::getShiftAmountConstant(uint64_t Val, EVT VT,
                                             const SDLoc &DL) {
  assert(VT.isInteger() && "Shift amount is not an integer type!");
  EVT ShiftVT = TLI->getShiftAmountTy(VT, getDataLayout());
  return getConstant(Val, DL, ShiftVT);
}
 
SDValue SelectionDAG::getShiftAmountConstant(const APInt &Val, EVT VT,
                                             const SDLoc &DL) {
  assert(Val.ult(VT.getScalarSizeInBits()) && "Out of range shift");
  return getShiftAmountConstant(Val.getZExtValue(), VT, DL);
}
 
SDValue SelectionDAG::getVectorIdxConstant(uint64_t Val, const SDLoc &DL,
                                           bool isTarget) {
  return getConstant(Val, DL, TLI->getVectorIdxTy(getDataLayout()), isTarget);
}
 
SDValue SelectionDAG::getConstantFP(const APFloat &V, const SDLoc &DL, EVT VT,
                                    bool isTarget) {
  return getConstantFP(*ConstantFP::get(*getContext(), V), DL, VT, isTarget);
}
 
SDValue SelectionDAG::getConstantFP(const ConstantFP &V, const SDLoc &DL,
                                    EVT VT, bool isTarget) {
  assert(VT.isFloatingPoint() && "Cannot create integer FP constant!");
 
  EVT EltVT = VT.getScalarType();
  const ConstantFP *Elt = &V;
 
  // Vector splats are explicit within the DAG, with ConstantFPSDNode holding
  // the to-be-splatted scalar ConstantFP.
  if (isa<VectorType>(Elt->getType()))
    Elt = ConstantFP::get(*getContext(), Elt->getValue());
 
  // Do the map lookup using the actual bit pattern for the floating point
  // value, so that we don't have problems with 0.0 comparing equal to -0.0, and
  // we don't have issues with SNANs.
  unsigned Opc = isTarget ? ISD::TargetConstantFP : ISD::ConstantFP;
  SDVTList VTs = getVTList(EltVT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddPointer(Elt);
  FoldingSetInsertToken InsertToken;
  SDNode *N = nullptr;
  if ((N = lookupNode(ID, DL, InsertToken)))
    if (!VT.isVector())
      return SDValue(N, 0);
 
  if (!N) {
    N = newSDNode<ConstantFPSDNode>(isTarget, Elt, VTs);
    CSEMap.insert(N, InsertToken);
    InsertNode(N);
  }
 
  SDValue Result(N, 0);
  if (VT.isVector())
    Result = getSplat(VT, DL, Result);
  NewSDValueDbgMsg(Result, "Creating fp constant: ", this);
  return Result;
}
 
SDValue SelectionDAG::getConstantFP(double Val, const SDLoc &DL, EVT VT,
                                    bool isTarget) {
  EVT EltVT = VT.getScalarType();
  if (EltVT == MVT::f32)
    return getConstantFP(APFloat((float)Val), DL, VT, isTarget);
  if (EltVT == MVT::f64)
    return getConstantFP(APFloat(Val), DL, VT, isTarget);
  if (EltVT == MVT::f80 || EltVT == MVT::f128 || EltVT == MVT::ppcf128 ||
      EltVT == MVT::f16 || EltVT == MVT::bf16) {
    bool Ignored;
    APFloat APF = APFloat(Val);
    APF.convert(EltVT.getFltSemantics(), APFloat::rmNearestTiesToEven,
                &Ignored);
    return getConstantFP(APF, DL, VT, isTarget);
  }
  llvm_unreachable("Unsupported type in getConstantFP");
}
 
SDValue SelectionDAG::getGlobalAddress(const GlobalValue *GV, const SDLoc &DL,
                                       EVT VT, int64_t Offset, bool isTargetGA,
                                       unsigned TargetFlags) {
  assert((TargetFlags == 0 || isTargetGA) &&
         "Cannot set target flags on target-independent globals");
 
  // Truncate (with sign-extension) the offset value to the pointer size.
  unsigned BitWidth = getDataLayout().getPointerTypeSizeInBits(GV->getType());
  if (BitWidth < 64)
    Offset = SignExtend64(Offset, BitWidth);
 
  unsigned Opc;
  if (GV->isThreadLocal())
    Opc = isTargetGA ? ISD::TargetGlobalTLSAddress : ISD::GlobalTLSAddress;
  else
    Opc = isTargetGA ? ISD::TargetGlobalAddress : ISD::GlobalAddress;
 
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddPointer(GV);
  ID.AddInteger(Offset);
  ID.AddInteger(TargetFlags);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, DL, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<GlobalAddressSDNode>(
      Opc, DL.getIROrder(), DL.getDebugLoc(), GV, VTs, Offset, TargetFlags);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getDeactivationSymbol(const GlobalValue *GV) {
  SDVTList VTs = getVTList(MVT::Untyped);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::DEACTIVATION_SYMBOL, VTs, {});
  ID.AddPointer(GV);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, SDLoc(), InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<DeactivationSymbolSDNode>(GV, VTs);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getFrameIndex(int FI, EVT VT, bool isTarget) {
  unsigned Opc = isTarget ? ISD::TargetFrameIndex : ISD::FrameIndex;
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddInteger(FI);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<FrameIndexSDNode>(FI, VTs, isTarget);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getJumpTable(int JTI, EVT VT, bool isTarget,
                                   unsigned TargetFlags) {
  assert((TargetFlags == 0 || isTarget) &&
         "Cannot set target flags on target-independent jump tables");
  unsigned Opc = isTarget ? ISD::TargetJumpTable : ISD::JumpTable;
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddInteger(JTI);
  ID.AddInteger(TargetFlags);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<JumpTableSDNode>(JTI, VTs, isTarget, TargetFlags);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getJumpTableDebugInfo(int JTI, SDValue Chain,
                                            const SDLoc &DL) {
  EVT PTy = getTargetLoweringInfo().getPointerTy(getDataLayout());
  return getNode(ISD::JUMP_TABLE_DEBUG_INFO, DL, MVT::Other, Chain,
                 getTargetConstant(static_cast<uint64_t>(JTI), DL, PTy, true));
}
 
SDValue SelectionDAG::getConstantPool(const Constant *C, EVT VT,
                                      MaybeAlign Alignment, int Offset,
                                      bool isTarget, unsigned TargetFlags) {
  assert((TargetFlags == 0 || isTarget) &&
         "Cannot set target flags on target-independent globals");
  if (!Alignment)
    Alignment = shouldOptForSize()
                    ? getDataLayout().getABITypeAlign(C->getType())
                    : getDataLayout().getPrefTypeAlign(C->getType());
  unsigned Opc = isTarget ? ISD::TargetConstantPool : ISD::ConstantPool;
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddInteger(Alignment->value());
  ID.AddInteger(Offset);
  ID.AddPointer(C);
  ID.AddInteger(TargetFlags);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<ConstantPoolSDNode>(isTarget, C, VTs, Offset, *Alignment,
                                          TargetFlags);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  SDValue V = SDValue(N, 0);
  NewSDValueDbgMsg(V, "Creating new constant pool: ", this);
  return V;
}
 
SDValue SelectionDAG::getConstantPool(MachineConstantPoolValue *C, EVT VT,
                                      MaybeAlign Alignment, int Offset,
                                      bool isTarget, unsigned TargetFlags) {
  assert((TargetFlags == 0 || isTarget) &&
         "Cannot set target flags on target-independent globals");
  if (!Alignment)
    Alignment = getDataLayout().getPrefTypeAlign(C->getType());
  unsigned Opc = isTarget ? ISD::TargetConstantPool : ISD::ConstantPool;
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddInteger(Alignment->value());
  ID.AddInteger(Offset);
  C->addSelectionDAGCSEId(ID);
  ID.AddInteger(TargetFlags);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<ConstantPoolSDNode>(isTarget, C, VTs, Offset, *Alignment,
                                          TargetFlags);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getBasicBlock(MachineBasicBlock *MBB) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::BasicBlock, getVTList(MVT::Other), {});
  ID.AddPointer(MBB);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<BasicBlockSDNode>(MBB);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getValueType(EVT VT) {
  if (VT.isSimple() && (unsigned)VT.getSimpleVT().SimpleTy >=
      ValueTypeNodes.size())
    ValueTypeNodes.resize(VT.getSimpleVT().SimpleTy+1);
 
  SDNode *&N = VT.isExtended() ?
    ExtendedValueTypeNodes[VT] : ValueTypeNodes[VT.getSimpleVT().SimpleTy];
 
  if (N) return SDValue(N, 0);
  N = newSDNode<VTSDNode>(VT);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getExternalSymbol(const char *Sym, EVT VT) {
  SDNode *&N = ExternalSymbols[Sym];
  if (N) return SDValue(N, 0);
  N = newSDNode<ExternalSymbolSDNode>(false, Sym, 0, getVTList(VT));
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getExternalSymbol(RTLIB::LibcallImpl Libcall, EVT VT) {
  StringRef SymName = RTLIB::RuntimeLibcallsInfo::getLibcallImplName(Libcall);
  return getExternalSymbol(SymName.data(), VT);
}
 
SDValue SelectionDAG::getMCSymbol(MCSymbol *Sym, EVT VT) {
  SDNode *&N = MCSymbols[Sym];
  if (N)
    return SDValue(N, 0);
  N = newSDNode<MCSymbolSDNode>(Sym, getVTList(VT));
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getTargetExternalSymbol(const char *Sym, EVT VT,
                                              unsigned TargetFlags) {
  SDNode *&N =
      TargetExternalSymbols[std::pair<std::string, unsigned>(Sym, TargetFlags)];
  if (N) return SDValue(N, 0);
  N = newSDNode<ExternalSymbolSDNode>(true, Sym, TargetFlags, getVTList(VT));
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getTargetExternalSymbol(RTLIB::LibcallImpl Libcall,
                                              EVT VT, unsigned TargetFlags) {
  StringRef SymName = RTLIB::RuntimeLibcallsInfo::getLibcallImplName(Libcall);
  return getTargetExternalSymbol(SymName.data(), VT, TargetFlags);
}
 
SDValue SelectionDAG::getCondCode(ISD::CondCode Cond) {
  if ((unsigned)Cond >= CondCodeNodes.size())
    CondCodeNodes.resize(Cond+1);
 
  if (!CondCodeNodes[Cond]) {
    auto *N = newSDNode<CondCodeSDNode>(Cond);
    CondCodeNodes[Cond] = N;
    InsertNode(N);
  }
 
  return SDValue(CondCodeNodes[Cond], 0);
}
 
SDValue SelectionDAG::getVScale(const SDLoc &DL, EVT VT, APInt MulImm) {
  assert(MulImm.getBitWidth() == VT.getSizeInBits() &&
         "APInt size does not match type size!");
 
  if (MulImm == 0)
    return getConstant(0, DL, VT);
 
  const MachineFunction &MF = getMachineFunction();
  const Function &F = MF.getFunction();
  ConstantRange CR = getVScaleRange(&F, 64);
  if (const APInt *C = CR.getSingleElement())
    return getConstant(MulImm * C->getZExtValue(), DL, VT);
 
  return getNode(ISD::VSCALE, DL, VT, getConstant(MulImm, DL, VT));
}
 
/// \returns a value of type \p VT that represents the runtime value of \p
/// Quantity, i.e. scaled by vscale if it's scalable, or a fixed constant
/// otherwise. Quantity should be a FixedOrScalableQuantity, i.e. ElementCount
/// or TypeSize.
template <typename Ty>
static SDValue getFixedOrScalableQuantity(SelectionDAG &DAG, const SDLoc &DL,
                                          EVT VT, Ty Quantity) {
  if (Quantity.isScalable())
    return DAG.getVScale(
        DL, VT, APInt(VT.getSizeInBits(), Quantity.getKnownMinValue()));
 
  return DAG.getConstant(Quantity.getKnownMinValue(), DL, VT);
}
 
SDValue SelectionDAG::getElementCount(const SDLoc &DL, EVT VT,
                                      ElementCount EC) {
  return getFixedOrScalableQuantity(*this, DL, VT, EC);
}
 
SDValue SelectionDAG::getTypeSize(const SDLoc &DL, EVT VT, TypeSize TS) {
  return getFixedOrScalableQuantity(*this, DL, VT, TS);
}
 
SDValue SelectionDAG::getMaskFromElementCount(const SDLoc &DL, EVT DataVT,
                                              ElementCount EC) {
  EVT IdxVT = TLI->getVectorIdxTy(getDataLayout());
  EVT MaskVT = TLI->getSetCCResultType(getDataLayout(), *getContext(), DataVT);
  return getNode(ISD::GET_ACTIVE_LANE_MASK, DL, MaskVT,
                 getConstant(0, DL, IdxVT), getElementCount(DL, IdxVT, EC));
}
 
SDValue SelectionDAG::getStepVector(const SDLoc &DL, EVT ResVT) {
  APInt One(ResVT.getScalarSizeInBits(), 1);
  return getStepVector(DL, ResVT, One);
}
 
SDValue SelectionDAG::getStepVector(const SDLoc &DL, EVT ResVT,
                                    const APInt &StepVal) {
  assert(ResVT.getScalarSizeInBits() == StepVal.getBitWidth());
  if (ResVT.isScalableVector())
    return getNode(
        ISD::STEP_VECTOR, DL, ResVT,
        getTargetConstant(StepVal, DL, ResVT.getVectorElementType()));
 
  SmallVector<SDValue, 16> OpsStepConstants;
  for (uint64_t i = 0; i < ResVT.getVectorNumElements(); i++)
    OpsStepConstants.push_back(
        getConstant(StepVal * i, DL, ResVT.getVectorElementType()));
  return getBuildVector(ResVT, DL, OpsStepConstants);
}
 
/// Swaps the values of N1 and N2. Swaps all indices in the shuffle mask M that
/// point at N1 to point at N2 and indices that point at N2 to point at N1.
static void commuteShuffle(SDValue &N1, SDValue &N2, MutableArrayRef<int> M) {
  std::swap(N1, N2);
  ShuffleVectorSDNode::commuteMask(M);
}
 
SDValue SelectionDAG::getVectorShuffle(EVT VT, const SDLoc &dl, SDValue N1,
                                       SDValue N2, ArrayRef<int> Mask) {
  assert(VT.getVectorNumElements() == Mask.size() &&
         "Must have the same number of vector elements as mask elements!");
  assert(VT == N1.getValueType() && VT == N2.getValueType() &&
         "Invalid VECTOR_SHUFFLE");
 
  // Canonicalize shuffle undef, undef -> undef
  if (N1.isUndef() && N2.isUndef()) {
    if (N1.getOpcode() == ISD::POISON && N2.getOpcode() == ISD::POISON)
      return getPOISON(VT);
    return getUNDEF(VT);
  }
 
  // Validate that all indices in Mask are within the range of the elements
  // input to the shuffle.
  int NElts = Mask.size();
  assert(llvm::all_of(Mask,
                      [&](int M) { return M < (NElts * 2) && M >= -1; }) &&
         "Index out of range");
 
  // Copy the mask so we can do any needed cleanup.
  SmallVector<int, 8> MaskVec(Mask);
 
  // Canonicalize shuffle v, v -> v, poison
  if (N1 == N2) {
    N2 = getPOISON(VT);
    for (int i = 0; i != NElts; ++i)
      if (MaskVec[i] >= NElts) MaskVec[i] -= NElts;
  }
 
  // Canonicalize shuffle undef, v -> v, undef.  Commute the shuffle mask.
  if (N1.isUndef())
    commuteShuffle(N1, N2, MaskVec);
 
  if (TLI->hasVectorBlend()) {
    // If shuffling a splat, try to blend the splat instead. We do this here so
    // that even when this arises during lowering we don't have to re-handle it.
    auto BlendSplat = [&](BuildVectorSDNode *BV, int Offset) {
      BitVector UndefElements;
      SDValue Splat = BV->getSplatValue(&UndefElements);
      if (!Splat)
        return;
 
      for (int i = 0; i < NElts; ++i) {
        if (MaskVec[i] < Offset || MaskVec[i] >= (Offset + NElts))
          continue;
 
        // If this input comes from undef, mark it as such.
        if (UndefElements[MaskVec[i] - Offset]) {
          MaskVec[i] = -1;
          continue;
        }
 
        // If we can blend a non-undef lane, use that instead.
        if (!UndefElements[i])
          MaskVec[i] = i + Offset;
      }
    };
    if (auto *N1BV = dyn_cast<BuildVectorSDNode>(N1))
      BlendSplat(N1BV, 0);
    if (auto *N2BV = dyn_cast<BuildVectorSDNode>(N2))
      BlendSplat(N2BV, NElts);
  }
 
  // Canonicalize all index into lhs, -> shuffle lhs, poison
  // Canonicalize all index into rhs, -> shuffle rhs, poison
  bool AllLHS = true, AllRHS = true;
  bool N2Undef = N2.isUndef();
  for (int i = 0; i != NElts; ++i) {
    if (MaskVec[i] >= NElts) {
      if (N2Undef)
        MaskVec[i] = -1;
      else
        AllLHS = false;
    } else if (MaskVec[i] >= 0) {
      AllRHS = false;
    }
  }
  if (AllLHS && AllRHS)
    return getPOISON(VT);
  if (AllLHS && !N2Undef)
    N2 = getPOISON(VT);
  if (AllRHS) {
    N1 = getPOISON(VT);
    commuteShuffle(N1, N2, MaskVec);
  }
  // Reset our undef status after accounting for the mask.
  N2Undef = N2.isUndef();
  // Re-check whether both sides ended up undef.
  if (N1.isUndef() && N2Undef) {
    if (N1.getOpcode() == ISD::POISON && N2.getOpcode() == ISD::POISON)
      return getPOISON(VT);
    return getUNDEF(VT);
  }
 
  // If Identity shuffle return that node.
  bool Identity = true, AllSame = true;
  for (int i = 0; i != NElts; ++i) {
    if (MaskVec[i] >= 0 && MaskVec[i] != i) Identity = false;
    if (MaskVec[i] != MaskVec[0]) AllSame = false;
  }
  if (Identity && NElts)
    return N1;
 
  // Shuffling a constant splat doesn't change the result.
  if (N2Undef) {
    SDValue V = N1;
 
    // Look through any bitcasts. We check that these don't change the number
    // (and size) of elements and just changes their types.
    while (V.getOpcode() == ISD::BITCAST)
      V = V->getOperand(0);
 
    // A splat should always show up as a build vector node.
    if (auto *BV = dyn_cast<BuildVectorSDNode>(V)) {
      BitVector UndefElements;
      SDValue Splat = BV->getSplatValue(&UndefElements);
      // If this is a splat of an undef, shuffling it is also undef.
      if (Splat && Splat.isUndef())
        return Splat.getOpcode() == ISD::POISON ? getPOISON(VT) : getUNDEF(VT);
 
      bool SameNumElts =
          V.getValueType().getVectorNumElements() == VT.getVectorNumElements();
 
      // We only have a splat which can skip shuffles if there is a splatted
      // value and no undef lanes rearranged by the shuffle.
      if (Splat && UndefElements.none()) {
        // Splat of <x, x, ..., x>, return <x, x, ..., x>, provided that the
        // number of elements match or the value splatted is a zero constant.
        if (SameNumElts || isNullConstant(Splat))
          return N1;
      }
 
      // If the shuffle itself creates a splat, build the vector directly.
      if (AllSame && SameNumElts) {
        EVT BuildVT = BV->getValueType(0);
        const SDValue &Splatted = BV->getOperand(MaskVec[0]);
        SDValue NewBV = getSplatBuildVector(BuildVT, dl, Splatted);
 
        // We may have jumped through bitcasts, so the type of the
        // BUILD_VECTOR may not match the type of the shuffle.
        if (BuildVT != VT)
          NewBV = getNode(ISD::BITCAST, dl, VT, NewBV);
        return NewBV;
      }
    }
  }
 
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  SDValue Ops[2] = { N1, N2 };
  AddNodeIDNode(ID, ISD::VECTOR_SHUFFLE, VTs, Ops);
  for (int i = 0; i != NElts; ++i)
    ID.AddInteger(MaskVec[i]);
 
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, dl, InsertToken))
    return SDValue(E, 0);
 
  // Allocate the mask array for the node out of the BumpPtrAllocator, since
  // SDNode doesn't have access to it.  This memory will be "leaked" when
  // the node is deallocated, but recovered when the NodeAllocator is released.
  int *MaskAlloc = OperandAllocator.Allocate<int>(NElts);
  llvm::copy(MaskVec, MaskAlloc);
 
  auto *N = newSDNode<ShuffleVectorSDNode>(VTs, dl.getIROrder(),
                                           dl.getDebugLoc(), MaskAlloc);
  createOperands(N, Ops);
 
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  SDValue V = SDValue(N, 0);
  NewSDValueDbgMsg(V, "Creating new node: ", this);
  return V;
}
 
SDValue SelectionDAG::getCommutedVectorShuffle(const ShuffleVectorSDNode &SV) {
  EVT VT = SV.getValueType(0);
  SmallVector<int, 8> MaskVec(SV.getMask());
  ShuffleVectorSDNode::commuteMask(MaskVec);
 
  SDValue Op0 = SV.getOperand(0);
  SDValue Op1 = SV.getOperand(1);
  return getVectorShuffle(VT, SDLoc(&SV), Op1, Op0, MaskVec);
}
 
SDValue SelectionDAG::getRegister(Register Reg, EVT VT) {
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::Register, VTs, {});
  ID.AddInteger(Reg.id());
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<RegisterSDNode>(Reg, VTs);
  N->SDNodeBits.IsDivergent = TLI->isSDNodeSourceOfDivergence(N, FLI, UA);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getRegisterMask(const uint32_t *RegMask) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::RegisterMask, getVTList(MVT::Untyped), {});
  ID.AddPointer(RegMask);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<RegisterMaskSDNode>(RegMask);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getEHLabel(const SDLoc &dl, SDValue Root,
                                 MCSymbol *Label) {
  return getLabelNode(ISD::EH_LABEL, dl, Root, Label);
}
 
SDValue SelectionDAG::getLabelNode(unsigned Opcode, const SDLoc &dl,
                                   SDValue Root, MCSymbol *Label) {
  FoldingSetNodeID ID;
  SDValue Ops[] = { Root };
  AddNodeIDNode(ID, Opcode, getVTList(MVT::Other), Ops);
  ID.AddPointer(Label);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N =
      newSDNode<LabelSDNode>(Opcode, dl.getIROrder(), dl.getDebugLoc(), Label);
  createOperands(N, Ops);
 
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getBlockAddress(const BlockAddress *BA, EVT VT,
                                      int64_t Offset, bool isTarget,
                                      unsigned TargetFlags) {
  unsigned Opc = isTarget ? ISD::TargetBlockAddress : ISD::BlockAddress;
  SDVTList VTs = getVTList(VT);
 
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, VTs, {});
  ID.AddPointer(BA);
  ID.AddInteger(Offset);
  ID.AddInteger(TargetFlags);
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<BlockAddressSDNode>(Opc, VTs, BA, Offset, TargetFlags);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getSrcValue(const Value *V) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::SRCVALUE, getVTList(MVT::Other), {});
  ID.AddPointer(V);
 
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<SrcValueSDNode>(V);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getMDNode(const MDNode *MD) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::MDNODE_SDNODE, getVTList(MVT::Other), {});
  ID.AddPointer(MD);
 
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<MDNodeSDNode>(MD);
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getBitcast(EVT VT, SDValue V) {
  if (VT == V.getValueType())
    return V;
 
  return getNode(ISD::BITCAST, SDLoc(V), VT, V);
}
 
SDValue SelectionDAG::getAddrSpaceCast(const SDLoc &dl, EVT VT, SDValue Ptr,
                                       unsigned SrcAS, unsigned DestAS) {
  SDVTList VTs = getVTList(VT);
  SDValue Ops[] = {Ptr};
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::ADDRSPACECAST, VTs, Ops);
  ID.AddInteger(SrcAS);
  ID.AddInteger(DestAS);
 
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, dl, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<AddrSpaceCastSDNode>(dl.getIROrder(), dl.getDebugLoc(),
                                           VTs, SrcAS, DestAS);
  createOperands(N, Ops);
 
  CSEMap.insert(N, InsertToken);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getFreeze(SDValue V) {
  return getNode(ISD::FREEZE, SDLoc(V), V.getValueType(), V);
}
 
SDValue SelectionDAG::getFreeze(SDValue V, const APInt &DemandedElts,
                                UndefPoisonKind Kind) {
  if (isGuaranteedNotToBeUndefOrPoison(V, DemandedElts, Kind))
    return V;
  return getFreeze(V);
}
 
/// getShiftAmountOperand - Return the specified value casted to
/// the target's desired shift amount type.
SDValue SelectionDAG::getShiftAmountOperand(EVT LHSTy, SDValue Op) {
  EVT OpTy = Op.getValueType();
  EVT ShTy = TLI->getShiftAmountTy(LHSTy, getDataLayout());
  if (OpTy == ShTy || OpTy.isVector()) return Op;
 
  return getZExtOrTrunc(Op, SDLoc(Op), ShTy);
}
 
SDValue SelectionDAG::expandVAArg(SDNode *Node) {
  SDLoc dl(Node);
  const TargetLowering &TLI = getTargetLoweringInfo();
  const Value *V = cast<SrcValueSDNode>(Node->getOperand(2))->getValue();
  EVT VT = Node->getValueType(0);
  SDValue Tmp1 = Node->getOperand(0);
  SDValue Tmp2 = Node->getOperand(1);
  const MaybeAlign MA(Node->getConstantOperandVal(3));
 
  SDValue VAListLoad = getLoad(TLI.getPointerTy(getDataLayout()), dl, Tmp1,
                               Tmp2, MachinePointerInfo(V));
  SDValue VAList = VAListLoad;
 
  if (MA && *MA > TLI.getMinStackArgumentAlignment()) {
    VAList = getNode(ISD::ADD, dl, VAList.getValueType(), VAList,
                     getConstant(MA->value() - 1, dl, VAList.getValueType()));
 
    VAList = getNode(
        ISD::AND, dl, VAList.getValueType(), VAList,
        getSignedConstant(-(int64_t)MA->value(), dl, VAList.getValueType()));
  }
 
  // Increment the pointer, VAList, to the next vaarg
  Tmp1 = getNode(ISD::ADD, dl, VAList.getValueType(), VAList,
                 getConstant(getDataLayout().getTypeAllocSize(
                                               VT.getTypeForEVT(*getContext())),
                             dl, VAList.getValueType()));
  // Store the incremented VAList to the legalized pointer
  Tmp1 =
      getStore(VAListLoad.getValue(1), dl, Tmp1, Tmp2, MachinePointerInfo(V));
  // Load the actual argument out of the pointer VAList
  return getLoad(VT, dl, Tmp1, VAList, MachinePointerInfo());
}
 
SDValue SelectionDAG::expandVACopy(SDNode *Node) {
  SDLoc dl(Node);
  const TargetLowering &TLI = getTargetLoweringInfo();
  // This defaults to loading a pointer from the input and storing it to the
  // output, returning the chain.
  const Value *VD = cast<SrcValueSDNode>(Node->getOperand(3))->getValue();
  const Value *VS = cast<SrcValueSDNode>(Node->getOperand(4))->getValue();
  SDValue Tmp1 =
      getLoad(TLI.getPointerTy(getDataLayout()), dl, Node->getOperand(0),
              Node->getOperand(2), MachinePointerInfo(VS));
  return getStore(Tmp1.getValue(1), dl, Tmp1, Node->getOperand(1),
                  MachinePointerInfo(VD));
}
 
Align SelectionDAG::getReducedAlign(EVT VT, bool UseABI) {
  const DataLayout &DL = getDataLayout();
  Type *Ty = VT.getTypeForEVT(*getContext());
  Align RedAlign = UseABI ? DL.getABITypeAlign(Ty) : DL.getPrefTypeAlign(Ty);
 
  if (TLI->isTypeLegal(VT) || !VT.isVector())
    return RedAlign;
 
  const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
  const Align StackAlign = TFI->getStackAlign();
 
  // See if we can choose a smaller ABI alignment in cases where it's an
  // illegal vector type that will get broken down.
  if (RedAlign > StackAlign) {
    EVT IntermediateVT;
    MVT RegisterVT;
    unsigned NumIntermediates;
    TLI->getVectorTypeBreakdown(*getContext(), VT, IntermediateVT,
                                NumIntermediates, RegisterVT);
    Ty = IntermediateVT.getTypeForEVT(*getContext());
    Align RedAlign2 = UseABI ? DL.getABITypeAlign(Ty) : DL.getPrefTypeAlign(Ty);
    if (RedAlign2 < RedAlign)
      RedAlign = RedAlign2;
 
    if (!getMachineFunction().getFrameInfo().isStackRealignable())
      // If the stack is not realignable, the alignment should be limited to the
      // StackAlignment
      RedAlign = std::min(RedAlign, StackAlign);
  }
 
  return RedAlign;
}
 
SDValue SelectionDAG::CreateStackTemporary(TypeSize Bytes, Align Alignment) {
  MachineFrameInfo &MFI = MF->getFrameInfo();
  const TargetFrameLowering *TFI = MF->getSubtarget().getFrameLowering();
  int StackID = 0;
  if (Bytes.isScalable())
    StackID = TFI->getStackIDForScalableVectors();
  // The stack id gives an indication of whether the object is scalable or
  // not, so it's safe to pass in the minimum size here.
  int FrameIdx = MFI.CreateStackObject(Bytes.getKnownMinValue(), Alignment,
                                       false, nullptr, StackID);
  return getFrameIndex(FrameIdx, TLI->getFrameIndexTy(getDataLayout()));
}
 
SDValue SelectionDAG::CreateStackTemporary(EVT VT, unsigned minAlign) {
  Type *Ty = VT.getTypeForEVT(*getContext());
  Align StackAlign =
      std::max(getDataLayout().getPrefTypeAlign(Ty), Align(minAlign));
  return CreateStackTemporary(VT.getStoreSize(), StackAlign);
}
 
SDValue SelectionDAG::CreateStackTemporary(EVT VT1, EVT VT2) {
  TypeSize VT1Size = VT1.getStoreSize();
  TypeSize VT2Size = VT2.getStoreSize();
  assert(VT1Size.isScalable() == VT2Size.isScalable() &&
         "Don't know how to choose the maximum size when creating a stack "
         "temporary");
  TypeSize Bytes = VT1Size.getKnownMinValue() > VT2Size.getKnownMinValue()
                       ? VT1Size
                       : VT2Size;
 
  Type *Ty1 = VT1.getTypeForEVT(*getContext());
  Type *Ty2 = VT2.getTypeForEVT(*getContext());
  const DataLayout &DL = getDataLayout();
  Align Align = std::max(DL.getPrefTypeAlign(Ty1), DL.getPrefTypeAlign(Ty2));
  return CreateStackTemporary(Bytes, Align);
}
 
SDValue SelectionDAG::FoldSetCC(EVT VT, SDValue N1, SDValue N2,
                                ISD::CondCode Cond, const SDLoc &dl,
                                SDNodeFlags Flags) {
  EVT OpVT = N1.getValueType();
 
  auto GetUndefBooleanConstant = [&]() {
    if (VT.getScalarType() == MVT::i1 ||
        TLI->getBooleanContents(OpVT) ==
            TargetLowering::UndefinedBooleanContent)
      return getUNDEF(VT);
    // ZeroOrOne / ZeroOrNegative require specific values for the high bits,
    // so we cannot use getUNDEF(). Return zero instead.
    return getConstant(0, dl, VT);
  };
 
  // These setcc operations always fold.
  switch (Cond) {
  default: break;
  case ISD::SETFALSE:
  case ISD::SETFALSE2: return getBoolConstant(false, dl, VT, OpVT);
  case ISD::SETTRUE:
  case ISD::SETTRUE2: return getBoolConstant(true, dl, VT, OpVT);
 
  case ISD::SETOEQ:
  case ISD::SETOGT:
  case ISD::SETOGE:
  case ISD::SETOLT:
  case ISD::SETOLE:
  case ISD::SETONE:
  case ISD::SETO:
  case ISD::SETUO:
  case ISD::SETUEQ:
  case ISD::SETUNE:
    assert(!OpVT.isInteger() && "Illegal setcc for integer!");
    break;
  }
 
  if (OpVT.isInteger()) {
    // For EQ and NE, we can always pick a value for the undef to make the
    // predicate pass or fail, so we can return undef.
    // Matches behavior in llvm::ConstantFoldCompareInstruction.
    // icmp eq/ne X, undef -> undef.
    if ((N1.isUndef() || N2.isUndef()) &&
        (Cond == ISD::SETEQ || Cond == ISD::SETNE))
      return GetUndefBooleanConstant();
 
    // If both operands are undef, we can return undef for int comparison.
    // icmp undef, undef -> undef.
    if (N1.isUndef() && N2.isUndef())
      return GetUndefBooleanConstant();
 
    // icmp X, X -> true/false
    // icmp X, undef -> true/false because undef could be X.
    if (N1.isUndef() || N2.isUndef() || N1 == N2)
      return getBoolConstant(ISD::isTrueWhenEqual(Cond), dl, VT, OpVT);
  }
 
  if (ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2)) {
    const APInt &C2 = N2C->getAPIntValue();
    if (ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1)) {
      const APInt &C1 = N1C->getAPIntValue();
 
      return getBoolConstant(ICmpInst::compare(C1, C2, getICmpCondCode(Cond)),
                             dl, VT, OpVT);
    }
  }
 
  auto *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
  auto *N2CFP = dyn_cast<ConstantFPSDNode>(N2);
 
  if (N1CFP && N2CFP) {
    APFloat::cmpResult R = N1CFP->getValueAPF().compare(N2CFP->getValueAPF());
    switch (Cond) {
    default: break;
    case ISD::SETEQ:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETOEQ: return getBoolConstant(R==APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETNE:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETONE: return getBoolConstant(R==APFloat::cmpGreaterThan ||
                                             R==APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    case ISD::SETLT:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETOLT: return getBoolConstant(R==APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    case ISD::SETGT:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETOGT: return getBoolConstant(R==APFloat::cmpGreaterThan, dl,
                                             VT, OpVT);
    case ISD::SETLE:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETOLE: return getBoolConstant(R==APFloat::cmpLessThan ||
                                             R==APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETGE:  if (R==APFloat::cmpUnordered)
                        return GetUndefBooleanConstant();
                      [[fallthrough]];
    case ISD::SETOGE: return getBoolConstant(R==APFloat::cmpGreaterThan ||
                                         R==APFloat::cmpEqual, dl, VT, OpVT);
    case ISD::SETO:   return getBoolConstant(R!=APFloat::cmpUnordered, dl, VT,
                                             OpVT);
    case ISD::SETUO:  return getBoolConstant(R==APFloat::cmpUnordered, dl, VT,
                                             OpVT);
    case ISD::SETUEQ: return getBoolConstant(R==APFloat::cmpUnordered ||
                                             R==APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETUNE: return getBoolConstant(R!=APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETULT: return getBoolConstant(R==APFloat::cmpUnordered ||
                                             R==APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    case ISD::SETUGT: return getBoolConstant(R==APFloat::cmpGreaterThan ||
                                             R==APFloat::cmpUnordered, dl, VT,
                                             OpVT);
    case ISD::SETULE: return getBoolConstant(R!=APFloat::cmpGreaterThan, dl,
                                             VT, OpVT);
    case ISD::SETUGE: return getBoolConstant(R!=APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    }
  } else if (N1CFP && OpVT.isSimple() && !N2.isUndef()) {
    // Ensure that the constant occurs on the RHS.
    ISD::CondCode SwappedCond = ISD::getSetCCSwappedOperands(Cond);
    if (!TLI->isCondCodeLegal(SwappedCond, OpVT.getSimpleVT()))
      return SDValue();
    return getSetCC(dl, VT, N2, N1, SwappedCond, /*Chain=*/{},
                    /*IsSignaling=*/false, Flags);
  } else if ((N2CFP && N2CFP->getValueAPF().isNaN()) ||
             (OpVT.isFloatingPoint() && (N1.isUndef() || N2.isUndef()))) {
    // If an operand is known to be a nan (or undef that could be a nan), we can
    // fold it.
    // Choosing NaN for the undef will always make unordered comparison succeed
    // and ordered comparison fails.
    // Matches behavior in llvm::ConstantFoldCompareInstruction.
    switch (ISD::getUnorderedFlavor(Cond)) {
    default:
      llvm_unreachable("Unknown flavor!");
    case 0: // Known false.
      return getBoolConstant(false, dl, VT, OpVT);
    case 1: // Known true.
      return getBoolConstant(true, dl, VT, OpVT);
    case 2: // Undefined.
      return GetUndefBooleanConstant();
    }
  }
 
  // Could not fold it.
  return SDValue();
}
 
/// SignBitIsZero - Return true if the sign bit of Op is known to be zero.  We
/// use this predicate to simplify operations downstream.
bool SelectionDAG::SignBitIsZero(SDValue Op, unsigned Depth) const {
  unsigned BitWidth = Op.getScalarValueSizeInBits();
  return MaskedValueIsZero(Op, APInt::getSignMask(BitWidth), Depth);
}
 
// TODO: Should have argument to specify if sign bit of nan is ignorable.
bool SelectionDAG::SignBitIsZeroFP(SDValue Op, unsigned Depth) const {
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  unsigned Opc = Op.getOpcode();
  switch (Opc) {
  case ISD::FABS:
    return true;
  case ISD::AssertNoFPClass: {
    FPClassTest NoFPClass =
        static_cast<FPClassTest>(Op.getConstantOperandVal(1));
 
    const FPClassTest TestMask = fcNan | fcNegative;
    return (NoFPClass & TestMask) == TestMask;
  }
  case ISD::ARITH_FENCE:
    return SignBitIsZeroFP(Op.getOperand(0), Depth + 1);
  case ISD::FEXP:
  case ISD::FEXP2:
  case ISD::FEXP10:
    return Op->getFlags().hasNoNaNs();
  case ISD::FMINNUM:
  case ISD::FMINNUM_IEEE:
  case ISD::FMINIMUM:
  case ISD::FMINIMUMNUM:
    return SignBitIsZeroFP(Op.getOperand(1), Depth + 1) &&
           SignBitIsZeroFP(Op.getOperand(0), Depth + 1);
  case ISD::FMAXNUM:
  case ISD::FMAXNUM_IEEE:
  case ISD::FMAXIMUM:
  case ISD::FMAXIMUMNUM:
    // TODO: If we can ignore the sign bit of nans, only one side being known 0
    // is sufficient.
    return SignBitIsZeroFP(Op.getOperand(1), Depth + 1) &&
           SignBitIsZeroFP(Op.getOperand(0), Depth + 1);
  default:
    return false;
  }
 
  llvm_unreachable("covered opcode switch");
}
 
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero.  We use
/// this predicate to simplify operations downstream.  Mask is known to be zero
/// for bits that V cannot have.
bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
                                     unsigned Depth) const {
  return Mask.isSubsetOf(computeKnownBits(V, Depth).Zero);
}
 
/// MaskedValueIsZero - Return true if 'V & Mask' is known to be zero in
/// DemandedElts.  We use this predicate to simplify operations downstream.
/// Mask is known to be zero for bits that V cannot have.
bool SelectionDAG::MaskedValueIsZero(SDValue V, const APInt &Mask,
                                     const APInt &DemandedElts,
                                     unsigned Depth) const {
  return Mask.isSubsetOf(computeKnownBits(V, DemandedElts, Depth).Zero);
}
 
/// MaskedVectorIsZero - Return true if 'Op' is known to be zero in
/// DemandedElts.  We use this predicate to simplify operations downstream.
bool SelectionDAG::MaskedVectorIsZero(SDValue V, const APInt &DemandedElts,
                                      unsigned Depth /* = 0 */) const {
  return computeKnownBits(V, DemandedElts, Depth).isZero();
}
 
/// MaskedValueIsAllOnes - Return true if '(Op & Mask) == Mask'.
bool SelectionDAG::MaskedValueIsAllOnes(SDValue V, const APInt &Mask,
                                        unsigned Depth) const {
  return Mask.isSubsetOf(computeKnownBits(V, Depth).One);
}
 
APInt SelectionDAG::computeVectorKnownZeroElements(SDValue Op,
                                                   const APInt &DemandedElts,
                                                   unsigned Depth) const {
  EVT VT = Op.getValueType();
  assert(VT.isVector() && !VT.isScalableVector() && "Only for fixed vectors!");
 
  unsigned NumElts = VT.getVectorNumElements();
  assert(DemandedElts.getBitWidth() == NumElts && "Unexpected demanded mask.");
 
  APInt KnownZeroElements = APInt::getZero(NumElts);
  for (unsigned EltIdx = 0; EltIdx != NumElts; ++EltIdx) {
    if (!DemandedElts[EltIdx])
      continue; // Don't query elements that are not demanded.
    APInt Mask = APInt::getOneBitSet(NumElts, EltIdx);
    if (MaskedVectorIsZero(Op, Mask, Depth))
      KnownZeroElements.setBit(EltIdx);
  }
  return KnownZeroElements;
}
 
/// isSplatValue - Return true if the vector V has the same value
/// across all DemandedElts. For scalable vectors, we don't know the
/// number of lanes at compile time.  Instead, we use a 1 bit APInt
/// to represent a conservative value for all lanes; that is, that
/// one bit value is implicitly splatted across all lanes.
bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts,
                                APInt &UndefElts, unsigned Depth) const {
  unsigned Opcode = V.getOpcode();
  EVT VT = V.getValueType();
  assert(VT.isVector() && "Vector type expected");
  assert((!VT.isScalableVector() || DemandedElts.getBitWidth() == 1) &&
         "scalable demanded bits are ignored");
 
  if (!DemandedElts)
    return false; // No demanded elts, better to assume we don't know anything.
 
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  // Deal with some common cases here that work for both fixed and scalable
  // vector types.
  switch (Opcode) {
  case ISD::SPLAT_VECTOR:
    UndefElts = V.getOperand(0).isUndef()
                    ? APInt::getAllOnes(DemandedElts.getBitWidth())
                    : APInt(DemandedElts.getBitWidth(), 0);
    return true;
  case ISD::ADD:
  case ISD::SUB:
  case ISD::AND:
  case ISD::XOR:
  case ISD::OR: {
    APInt UndefLHS, UndefRHS;
    SDValue LHS = V.getOperand(0);
    SDValue RHS = V.getOperand(1);
    // Only recognize splats with the same demanded undef elements for both
    // operands, otherwise we might fail to handle binop-specific undef
    // handling.
    // e.g. (and undef, 0) -> 0 etc.
    if (isSplatValue(LHS, DemandedElts, UndefLHS, Depth + 1) &&
        isSplatValue(RHS, DemandedElts, UndefRHS, Depth + 1) &&
        (DemandedElts & UndefLHS) == (DemandedElts & UndefRHS)) {
      UndefElts = UndefLHS | UndefRHS;
      return true;
    }
    return false;
  }
  case ISD::ABS:
  case ISD::ABS_MIN_POISON:
  case ISD::TRUNCATE:
  case ISD::SIGN_EXTEND:
  case ISD::ZERO_EXTEND:
    return isSplatValue(V.getOperand(0), DemandedElts, UndefElts, Depth + 1);
  default:
    if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
        Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID)
      return TLI->isSplatValueForTargetNode(V, DemandedElts, UndefElts, *this,
                                            Depth);
    break;
  }
 
  // We don't support other cases than those above for scalable vectors at
  // the moment.
  if (VT.isScalableVector())
    return false;
 
  unsigned NumElts = VT.getVectorNumElements();
  assert(NumElts == DemandedElts.getBitWidth() && "Vector size mismatch");
  UndefElts = APInt::getZero(NumElts);
 
  switch (Opcode) {
  case ISD::BUILD_VECTOR: {
    SDValue Scl;
    for (unsigned i = 0; i != NumElts; ++i) {
      SDValue Op = V.getOperand(i);
      if (Op.isUndef()) {
        UndefElts.setBit(i);
        continue;
      }
      if (!DemandedElts[i])
        continue;
      if (Scl && Scl != Op)
        return false;
      Scl = Op;
    }
    return true;
  }
  case ISD::VECTOR_SHUFFLE: {
    // Check if this is a shuffle node doing a splat or a shuffle of a splat.
    APInt DemandedLHS = APInt::getZero(NumElts);
    APInt DemandedRHS = APInt::getZero(NumElts);
    ArrayRef<int> Mask = cast<ShuffleVectorSDNode>(V)->getMask();
    for (int i = 0; i != (int)NumElts; ++i) {
      int M = Mask[i];
      if (M < 0) {
        UndefElts.setBit(i);
        continue;
      }
      if (!DemandedElts[i])
        continue;
      if (M < (int)NumElts)
        DemandedLHS.setBit(M);
      else
        DemandedRHS.setBit(M - NumElts);
    }
 
    // If we aren't demanding either op, assume there's no splat.
    // If we are demanding both ops, assume there's no splat.
    if ((DemandedLHS.isZero() && DemandedRHS.isZero()) ||
        (!DemandedLHS.isZero() && !DemandedRHS.isZero()))
      return false;
 
    // See if the demanded elts of the source op is a splat or we only demand
    // one element, which should always be a splat.
    // TODO: Handle source ops splats with undefs.
    auto CheckSplatSrc = [&](SDValue Src, const APInt &SrcElts) {
      APInt SrcUndefs;
      return (SrcElts.popcount() == 1) ||
             (isSplatValue(Src, SrcElts, SrcUndefs, Depth + 1) &&
              (SrcElts & SrcUndefs).isZero());
    };
    if (!DemandedLHS.isZero())
      return CheckSplatSrc(V.getOperand(0), DemandedLHS);
    return CheckSplatSrc(V.getOperand(1), DemandedRHS);
  }
  case ISD::EXTRACT_SUBVECTOR: {
    // Offset the demanded elts by the subvector index.
    SDValue Src = V.getOperand(0);
    // We don't support scalable vectors at the moment.
    if (Src.getValueType().isScalableVector())
      return false;
    uint64_t Idx = V.getConstantOperandVal(1);
    unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
    APInt UndefSrcElts;
    APInt DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
    if (isSplatValue(Src, DemandedSrcElts, UndefSrcElts, Depth + 1)) {
      UndefElts = UndefSrcElts.extractBits(NumElts, Idx);
      return true;
    }
    break;
  }
  case ISD::ANY_EXTEND_VECTOR_INREG:
  case ISD::SIGN_EXTEND_VECTOR_INREG:
  case ISD::ZERO_EXTEND_VECTOR_INREG: {
    // Widen the demanded elts by the src element count.
    SDValue Src = V.getOperand(0);
    // We don't support scalable vectors at the moment.
    if (Src.getValueType().isScalableVector())
      return false;
    unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
    APInt UndefSrcElts;
    APInt DemandedSrcElts = DemandedElts.zext(NumSrcElts);
    if (isSplatValue(Src, DemandedSrcElts, UndefSrcElts, Depth + 1)) {
      UndefElts = UndefSrcElts.trunc(NumElts);
      return true;
    }
    break;
  }
  case ISD::BITCAST: {
    SDValue Src = V.getOperand(0);
    EVT SrcVT = Src.getValueType();
    unsigned SrcBitWidth = SrcVT.getScalarSizeInBits();
    unsigned BitWidth = VT.getScalarSizeInBits();
 
    // Ignore bitcasts from unsupported types.
    // TODO: Add fp support?
    if (!SrcVT.isVector() || !SrcVT.isInteger() || !VT.isInteger())
      break;
 
    // Bitcast 'small element' vector to 'large element' vector.
    if ((BitWidth % SrcBitWidth) == 0) {
      // See if each sub element is a splat.
      unsigned Scale = BitWidth / SrcBitWidth;
      unsigned NumSrcElts = SrcVT.getVectorNumElements();
      APInt ScaledDemandedElts =
          APIntOps::ScaleBitMask(DemandedElts, NumSrcElts);
      for (unsigned I = 0; I != Scale; ++I) {
        APInt SubUndefElts;
        APInt SubDemandedElt = APInt::getOneBitSet(Scale, I);
        APInt SubDemandedElts = APInt::getSplat(NumSrcElts, SubDemandedElt);
        SubDemandedElts &= ScaledDemandedElts;
        if (!isSplatValue(Src, SubDemandedElts, SubUndefElts, Depth + 1))
          return false;
        // TODO: Add support for merging sub undef elements.
        if (!SubUndefElts.isZero())
          return false;
      }
      return true;
    }
    break;
  }
  }
 
  return false;
}
 
/// Helper wrapper to main isSplatValue function.
bool SelectionDAG::isSplatValue(SDValue V, bool AllowUndefs) const {
  EVT VT = V.getValueType();
  assert(VT.isVector() && "Vector type expected");
 
  APInt UndefElts;
  // Since the number of lanes in a scalable vector is unknown at compile time,
  // we track one bit which is implicitly broadcast to all lanes.  This means
  // that all lanes in a scalable vector are considered demanded.
  APInt DemandedElts
    = APInt::getAllOnes(VT.isScalableVector() ? 1 : VT.getVectorNumElements());
  return isSplatValue(V, DemandedElts, UndefElts) &&
         (AllowUndefs || !UndefElts);
}
 
SDValue SelectionDAG::getSplatSourceVector(SDValue V, int &SplatIdx) {
  V = peekThroughExtractSubvectors(V);
 
  EVT VT = V.getValueType();
  unsigned Opcode = V.getOpcode();
  switch (Opcode) {
  default: {
    APInt UndefElts;
    // Since the number of lanes in a scalable vector is unknown at compile time,
    // we track one bit which is implicitly broadcast to all lanes.  This means
    // that all lanes in a scalable vector are considered demanded.
    APInt DemandedElts
      = APInt::getAllOnes(VT.isScalableVector() ? 1 : VT.getVectorNumElements());
 
    if (isSplatValue(V, DemandedElts, UndefElts)) {
      if (VT.isScalableVector()) {
        // DemandedElts and UndefElts are ignored for scalable vectors, since
        // the only supported cases are SPLAT_VECTOR nodes.
        SplatIdx = 0;
      } else {
        // Handle case where all demanded elements are UNDEF.
        if (DemandedElts.isSubsetOf(UndefElts)) {
          SplatIdx = 0;
          return getUNDEF(VT);
        }
        SplatIdx = (UndefElts & DemandedElts).countr_one();
      }
      return V;
    }
    break;
  }
  case ISD::SPLAT_VECTOR:
    SplatIdx = 0;
    return V;
  case ISD::VECTOR_SHUFFLE: {
    assert(!VT.isScalableVector());
    // Check if this is a shuffle node doing a splat.
    // TODO - remove this and rely purely on SelectionDAG::isSplatValue,
    // getTargetVShiftNode currently struggles without the splat source.
    auto *SVN = cast<ShuffleVectorSDNode>(V);
    if (!SVN->isSplat())
      break;
    int Idx = SVN->getSplatIndex();
    int NumElts = V.getValueType().getVectorNumElements();
    SplatIdx = Idx % NumElts;
    return V.getOperand(Idx / NumElts);
  }
  }
 
  return SDValue();
}
 
SDValue SelectionDAG::getSplatValue(SDValue V, bool LegalTypes) {
  int SplatIdx;
  if (SDValue SrcVector = getSplatSourceVector(V, SplatIdx)) {
    EVT SVT = SrcVector.getValueType().getScalarType();
    EVT LegalSVT = SVT;
    if (LegalTypes && !TLI->isTypeLegal(SVT)) {
      if (!SVT.isInteger())
        return SDValue();
      LegalSVT = TLI->getTypeToTransformTo(*getContext(), LegalSVT);
      if (LegalSVT.bitsLT(SVT))
        return SDValue();
    }
    return getExtractVectorElt(SDLoc(V), LegalSVT, SrcVector, SplatIdx);
  }
  return SDValue();
}
 
std::optional<ConstantRange>
SelectionDAG::getValidShiftAmountRange(SDValue V, const APInt &DemandedElts,
                                       unsigned Depth) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  // Shifting more than the bitwidth is not valid.
  unsigned BitWidth = V.getScalarValueSizeInBits();
 
  if (auto *Cst = dyn_cast<ConstantSDNode>(V.getOperand(1))) {
    const APInt &ShAmt = Cst->getAPIntValue();
    if (ShAmt.uge(BitWidth))
      return std::nullopt;
    return ConstantRange(ShAmt);
  }
 
  if (auto *BV = dyn_cast<BuildVectorSDNode>(V.getOperand(1))) {
    const APInt *MinAmt = nullptr, *MaxAmt = nullptr;
    for (unsigned i = 0, e = BV->getNumOperands(); i != e; ++i) {
      if (!DemandedElts[i])
        continue;
      auto *SA = dyn_cast<ConstantSDNode>(BV->getOperand(i));
      if (!SA) {
        MinAmt = MaxAmt = nullptr;
        break;
      }
      const APInt &ShAmt = SA->getAPIntValue();
      if (ShAmt.uge(BitWidth))
        return std::nullopt;
      if (!MinAmt || MinAmt->ugt(ShAmt))
        MinAmt = &ShAmt;
      if (!MaxAmt || MaxAmt->ult(ShAmt))
        MaxAmt = &ShAmt;
    }
    assert(((!MinAmt && !MaxAmt) || (MinAmt && MaxAmt)) &&
           "Failed to find matching min/max shift amounts");
    if (MinAmt && MaxAmt)
      return ConstantRange(*MinAmt, *MaxAmt + 1);
  }
 
  // Use computeKnownBits to find a hidden constant/knownbits (usually type
  // legalized). e.g. Hidden behind multiple bitcasts/build_vector/casts etc.
  KnownBits KnownAmt = computeKnownBits(V.getOperand(1), DemandedElts, Depth);
  if (KnownAmt.getMaxValue().ult(BitWidth))
    return ConstantRange::fromKnownBits(KnownAmt, /*IsSigned=*/false);
 
  return std::nullopt;
}
 
std::optional<unsigned>
SelectionDAG::getValidShiftAmount(SDValue V, const APInt &DemandedElts,
                                  unsigned Depth) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  if (std::optional<ConstantRange> AmtRange =
          getValidShiftAmountRange(V, DemandedElts, Depth))
    if (const APInt *ShAmt = AmtRange->getSingleElement())
      return ShAmt->getZExtValue();
  return std::nullopt;
}
 
std::optional<unsigned>
SelectionDAG::getValidShiftAmount(SDValue V, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(V);
  return getValidShiftAmount(V, DemandedElts, Depth);
}
 
std::optional<unsigned>
SelectionDAG::getValidMinimumShiftAmount(SDValue V, const APInt &DemandedElts,
                                         unsigned Depth) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  if (std::optional<ConstantRange> AmtRange =
          getValidShiftAmountRange(V, DemandedElts, Depth))
    return AmtRange->getUnsignedMin().getZExtValue();
  return std::nullopt;
}
 
std::optional<unsigned>
SelectionDAG::getValidMinimumShiftAmount(SDValue V, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(V);
  return getValidMinimumShiftAmount(V, DemandedElts, Depth);
}
 
std::optional<unsigned>
SelectionDAG::getValidMaximumShiftAmount(SDValue V, const APInt &DemandedElts,
                                         unsigned Depth) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  if (std::optional<ConstantRange> AmtRange =
          getValidShiftAmountRange(V, DemandedElts, Depth))
    return AmtRange->getUnsignedMax().getZExtValue();
  return std::nullopt;
}
 
std::optional<unsigned>
SelectionDAG::getValidMaximumShiftAmount(SDValue V, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(V);
  return getValidMaximumShiftAmount(V, DemandedElts, Depth);
}
 
/// Determine which bits of Op are known to be either zero or one and return
/// them in Known. For vectors, the known bits are those that are shared by
/// every vector element.
KnownBits SelectionDAG::computeKnownBits(SDValue Op, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return computeKnownBits(Op, DemandedElts, Depth);
}
 
/// Determine which bits of Op are known to be either zero or one and return
/// them in Known. The DemandedElts argument allows us to only collect the known
/// bits that are shared by the requested vector elements.
KnownBits SelectionDAG::computeKnownBits(SDValue Op, const APInt &DemandedElts,
                                         unsigned Depth) const {
  unsigned BitWidth = Op.getScalarValueSizeInBits();
 
  KnownBits Known(BitWidth);   // Don't know anything.
 
  if (auto OptAPInt = Op->bitcastToAPInt()) {
    // We know all of the bits for a constant!
    return KnownBits::makeConstant(*std::move(OptAPInt));
  }
 
  if (Depth >= MaxRecursionDepth)
    return Known;  // Limit search depth.
 
  KnownBits Known2;
  unsigned NumElts = DemandedElts.getBitWidth();
  assert((!Op.getValueType().isScalableVector() || NumElts == 1) &&
         "DemandedElts for scalable vectors must be 1 to represent all lanes");
  assert((!Op.getValueType().isFixedLengthVector() ||
          NumElts == Op.getValueType().getVectorNumElements()) &&
         "Unexpected vector size");
 
  if (!DemandedElts)
    return Known;  // No demanded elts, better to assume we don't know anything.
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  case ISD::FREEZE: {
    if (isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), DemandedElts,
                                         UndefPoisonKind::UndefOrPoison))
      Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    break;
  }
  case ISD::MERGE_VALUES:
    return computeKnownBits(Op.getOperand(Op.getResNo()), DemandedElts,
                            Depth + 1);
  case ISD::SPLAT_VECTOR: {
    SDValue SrcOp = Op.getOperand(0);
    assert(SrcOp.getValueSizeInBits() >= BitWidth &&
           "Expected SPLAT_VECTOR implicit truncation");
    // Implicitly truncate the bits to match the official semantics of
    // SPLAT_VECTOR.
    Known = computeKnownBits(SrcOp, Depth + 1).trunc(BitWidth);
    break;
  }
  case ISD::SPLAT_VECTOR_PARTS: {
    unsigned ScalarSize = Op.getOperand(0).getScalarValueSizeInBits();
    assert(ScalarSize * Op.getNumOperands() == BitWidth &&
           "Expected SPLAT_VECTOR_PARTS scalars to cover element width");
    for (auto [I, SrcOp] : enumerate(Op->ops())) {
      Known.insertBits(computeKnownBits(SrcOp, Depth + 1), ScalarSize * I);
    }
    break;
  }
  case ISD::STEP_VECTOR: {
    const APInt &Step = Op.getConstantOperandAPInt(0);
 
    if (Step.isPowerOf2())
      Known.Zero.setLowBits(Step.logBase2());
 
    const Function &F = getMachineFunction().getFunction();
 
    if (!isUIntN(BitWidth, Op.getValueType().getVectorMinNumElements()))
      break;
    const APInt MinNumElts =
        APInt(BitWidth, Op.getValueType().getVectorMinNumElements());
 
    bool Overflow;
    const APInt MaxNumElts = getVScaleRange(&F, BitWidth)
                                 .getUnsignedMax()
                                 .umul_ov(MinNumElts, Overflow);
    if (Overflow)
      break;
 
    const APInt MaxValue = (MaxNumElts - 1).umul_ov(Step, Overflow);
    if (Overflow)
      break;
 
    Known.Zero.setHighBits(MaxValue.countl_zero());
    break;
  }
  case ISD::BUILD_VECTOR:
    assert(!Op.getValueType().isScalableVector());
    // Collect the known bits that are shared by every demanded vector element.
    Known.setAllConflict();
    for (unsigned i = 0, e = Op.getNumOperands(); i != e; ++i) {
      if (!DemandedElts[i])
        continue;
 
      SDValue SrcOp = Op.getOperand(i);
      if (SrcOp.getOpcode() == ISD::POISON)
        continue;
 
      Known2 = computeKnownBits(SrcOp, Depth + 1);
 
      // BUILD_VECTOR can implicitly truncate sources, we must handle this.
      if (SrcOp.getValueSizeInBits() != BitWidth) {
        assert(SrcOp.getValueSizeInBits() > BitWidth &&
               "Expected BUILD_VECTOR implicit truncation");
        Known2 = Known2.trunc(BitWidth);
      }
 
      // Known bits are the values that are shared by every demanded element.
      Known = Known.intersectWith(Known2);
 
      // If we don't know any bits, early out.
      if (Known.isUnknown())
        break;
    }
 
    // If every demanded element was poison, we know nothing.
    if (Known.hasConflict())
      Known.resetAll();
    break;
  case ISD::VECTOR_COMPRESS: {
    SDValue Vec = Op.getOperand(0);
    SDValue PassThru = Op.getOperand(2);
    Known = computeKnownBits(PassThru, DemandedElts, Depth + 1);
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
    Known2 = computeKnownBits(Vec, Depth + 1);
    Known = Known.intersectWith(Known2);
    break;
  }
  case ISD::VECTOR_SHUFFLE: {
    assert(!Op.getValueType().isScalableVector());
    // Collect the known bits that are shared by every vector element referenced
    // by the shuffle.
    APInt DemandedLHS, DemandedRHS;
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Op);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    if (!getShuffleDemandedElts(NumElts, SVN->getMask(), DemandedElts,
                                DemandedLHS, DemandedRHS))
      break;
 
    // Known bits are the values that are shared by every demanded element.
    Known.setAllConflict();
    if (!!DemandedLHS) {
      SDValue LHS = Op.getOperand(0);
      Known2 = computeKnownBits(LHS, DemandedLHS, Depth + 1);
      Known = Known.intersectWith(Known2);
    }
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
    if (!!DemandedRHS) {
      SDValue RHS = Op.getOperand(1);
      Known2 = computeKnownBits(RHS, DemandedRHS, Depth + 1);
      Known = Known.intersectWith(Known2);
    }
    break;
  }
  case ISD::VSCALE: {
    const Function &F = getMachineFunction().getFunction();
    const APInt &Multiplier = Op.getConstantOperandAPInt(0);
    Known = getVScaleRange(&F, BitWidth).multiply(Multiplier).toKnownBits();
    break;
  }
  case ISD::CONCAT_VECTORS: {
    if (Op.getValueType().isScalableVector())
      break;
    // Split DemandedElts and test each of the demanded subvectors.
    Known.setAllConflict();
    EVT SubVectorVT = Op.getOperand(0).getValueType();
    unsigned NumSubVectorElts = SubVectorVT.getVectorNumElements();
    unsigned NumSubVectors = Op.getNumOperands();
    for (unsigned i = 0; i != NumSubVectors; ++i) {
      APInt DemandedSub =
          DemandedElts.extractBits(NumSubVectorElts, i * NumSubVectorElts);
      if (!!DemandedSub) {
        SDValue Sub = Op.getOperand(i);
        Known2 = computeKnownBits(Sub, DemandedSub, Depth + 1);
        Known = Known.intersectWith(Known2);
      }
      // If we don't know any bits, early out.
      if (Known.isUnknown())
        break;
    }
    break;
  }
  case ISD::INSERT_SUBVECTOR: {
    if (Op.getValueType().isScalableVector())
      break;
    // Demand any elements from the subvector and the remainder from the src its
    // inserted into.
    SDValue Src = Op.getOperand(0);
    SDValue Sub = Op.getOperand(1);
    uint64_t Idx = Op.getConstantOperandVal(2);
    unsigned NumSubElts = Sub.getValueType().getVectorNumElements();
    APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
    APInt DemandedSrcElts = DemandedElts;
    DemandedSrcElts.clearBits(Idx, Idx + NumSubElts);
 
    Known.setAllConflict();
    if (!!DemandedSubElts) {
      Known = computeKnownBits(Sub, DemandedSubElts, Depth + 1);
      if (Known.isUnknown())
        break; // early-out.
    }
    if (!!DemandedSrcElts) {
      Known2 = computeKnownBits(Src, DemandedSrcElts, Depth + 1);
      Known = Known.intersectWith(Known2);
    }
    break;
  }
  case ISD::EXTRACT_SUBVECTOR: {
    // Offset the demanded elts by the subvector index.
    SDValue Src = Op.getOperand(0);
 
    APInt DemandedSrcElts;
    if (Src.getValueType().isScalableVector())
      DemandedSrcElts = APInt(1, 1); // <=> 'demand all elements'
    else {
      uint64_t Idx = Op.getConstantOperandVal(1);
      unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
      DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
    }
    Known = computeKnownBits(Src, DemandedSrcElts, Depth + 1);
    break;
  }
  case ISD::SCALAR_TO_VECTOR: {
    if (Op.getValueType().isScalableVector())
      break;
    // We know about scalar_to_vector as much as we know about it source,
    // which becomes the first element of otherwise unknown vector.
    if (DemandedElts != 1)
      break;
 
    SDValue N0 = Op.getOperand(0);
    Known = computeKnownBits(N0, Depth + 1);
    if (N0.getValueSizeInBits() != BitWidth)
      Known = Known.trunc(BitWidth);
 
    break;
  }
  case ISD::BITCAST: {
    if (Op.getValueType().isScalableVector())
      break;
 
    SDValue N0 = Op.getOperand(0);
    EVT SubVT = N0.getValueType();
    unsigned SubBitWidth = SubVT.getScalarSizeInBits();
 
    // Ignore bitcasts from unsupported types.
    if (!(SubVT.isInteger() || SubVT.isFloatingPoint()))
      break;
 
    // Fast handling of 'identity' bitcasts.
    if (BitWidth == SubBitWidth) {
      Known = computeKnownBits(N0, DemandedElts, Depth + 1);
      break;
    }
 
    bool IsLE = getDataLayout().isLittleEndian();
 
    // Bitcast 'small element' vector to 'large element' scalar/vector.
    if ((BitWidth % SubBitWidth) == 0) {
      assert(N0.getValueType().isVector() && "Expected bitcast from vector");
 
      // Collect known bits for the (larger) output by collecting the known
      // bits from each set of sub elements and shift these into place.
      // We need to separately call computeKnownBits for each set of
      // sub elements as the knownbits for each is likely to be different.
      unsigned SubScale = BitWidth / SubBitWidth;
      APInt SubDemandedElts(NumElts * SubScale, 0);
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i])
          SubDemandedElts.setBit(i * SubScale);
 
      for (unsigned i = 0; i != SubScale; ++i) {
        Known2 = computeKnownBits(N0, SubDemandedElts.shl(i),
                         Depth + 1);
        unsigned Shifts = IsLE ? i : SubScale - 1 - i;
        Known.insertBits(Known2, SubBitWidth * Shifts);
      }
    }
 
    // Bitcast 'large element' scalar/vector to 'small element' vector.
    if ((SubBitWidth % BitWidth) == 0) {
      assert(Op.getValueType().isVector() && "Expected bitcast to vector");
 
      // Collect known bits for the (smaller) output by collecting the known
      // bits from the overlapping larger input elements and extracting the
      // sub sections we actually care about.
      unsigned SubScale = SubBitWidth / BitWidth;
      APInt SubDemandedElts =
          APIntOps::ScaleBitMask(DemandedElts, NumElts / SubScale);
      Known2 = computeKnownBits(N0, SubDemandedElts, Depth + 1);
 
      Known.setAllConflict();
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i]) {
          unsigned Shifts = IsLE ? i : NumElts - 1 - i;
          unsigned Offset = (Shifts % SubScale) * BitWidth;
          Known = Known.intersectWith(Known2.extractBits(BitWidth, Offset));
          // If we don't know any bits, early out.
          if (Known.isUnknown())
            break;
        }
    }
    break;
  }
  case ISD::AND:
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
    Known &= Known2;
    break;
  case ISD::OR:
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
    Known |= Known2;
    break;
  case ISD::XOR:
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
    Known ^= Known2;
    break;
  case ISD::MUL: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    bool SelfMultiply = Op.getOperand(0) == Op.getOperand(1);
    // TODO: SelfMultiply can be poison, but not undef.
    if (SelfMultiply)
      SelfMultiply &= isGuaranteedNotToBeUndefOrPoison(
          Op.getOperand(0), DemandedElts, UndefPoisonKind::UndefOrPoison,
          Depth + 1);
    Known = KnownBits::mul(Known, Known2, SelfMultiply);
 
    // If the multiplication is known not to overflow, the product of a number
    // with itself is non-negative. Only do this if we didn't already computed
    // the opposite value for the sign bit.
    if (Op->getFlags().hasNoSignedWrap() &&
        Op.getOperand(0) == Op.getOperand(1) &&
        !Known.isNegative())
      Known.makeNonNegative();
    break;
  }
  case ISD::MULHU: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::mulhu(Known, Known2);
    break;
  }
  case ISD::MULHS: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::mulhs(Known, Known2);
    break;
  }
  case ISD::ABDU: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::abdu(Known, Known2);
    break;
  }
  case ISD::ABDS: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::abds(Known, Known2);
    unsigned SignBits1 =
        ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (SignBits1 == 1)
      break;
    unsigned SignBits0 =
        ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known.Zero.setHighBits(std::min(SignBits0, SignBits1) - 1);
    break;
  }
  case ISD::UMUL_LOHI: {
    assert((Op.getResNo() == 0 || Op.getResNo() == 1) && "Unknown result");
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    bool SelfMultiply = Op.getOperand(0) == Op.getOperand(1);
    if (Op.getResNo() == 0)
      Known = KnownBits::mul(Known, Known2, SelfMultiply);
    else
      Known = KnownBits::mulhu(Known, Known2);
    break;
  }
  case ISD::SMUL_LOHI: {
    assert((Op.getResNo() == 0 || Op.getResNo() == 1) && "Unknown result");
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    bool SelfMultiply = Op.getOperand(0) == Op.getOperand(1);
    if (Op.getResNo() == 0)
      Known = KnownBits::mul(Known, Known2, SelfMultiply);
    else
      Known = KnownBits::mulhs(Known, Known2);
    break;
  }
  case ISD::AVGFLOORU: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::avgFloorU(Known, Known2);
    break;
  }
  case ISD::AVGCEILU: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::avgCeilU(Known, Known2);
    break;
  }
  case ISD::AVGFLOORS: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::avgFloorS(Known, Known2);
    break;
  }
  case ISD::AVGCEILS: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::avgCeilS(Known, Known2);
    break;
  }
  case ISD::SELECT:
  case ISD::VSELECT:
    Known = computeKnownBits(Op.getOperand(2), DemandedElts, Depth+1);
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth+1);
 
    // Only known if known in both the LHS and RHS.
    Known = Known.intersectWith(Known2);
    break;
  case ISD::SELECT_CC:
    Known = computeKnownBits(Op.getOperand(3), DemandedElts, Depth+1);
    // If we don't know any bits, early out.
    if (Known.isUnknown())
      break;
    Known2 = computeKnownBits(Op.getOperand(2), DemandedElts, Depth+1);
 
    // Only known if known in both the LHS and RHS.
    Known = Known.intersectWith(Known2);
    break;
  case ISD::SMULO:
  case ISD::UMULO:
    if (Op.getResNo() != 1)
      break;
    // The boolean result conforms to getBooleanContents.
    // If we know the result of a setcc has the top bits zero, use this info.
    // We know that we have an integer-based boolean since these operations
    // are only available for integer.
    if (TLI->getBooleanContents(Op.getValueType().isVector(), false) ==
            TargetLowering::ZeroOrOneBooleanContent &&
        BitWidth > 1)
      Known.Zero.setBitsFrom(1);
    break;
  case ISD::SETCC:
  case ISD::SETCCCARRY:
  case ISD::STRICT_FSETCC:
  case ISD::STRICT_FSETCCS: {
    unsigned OpNo = Op->isStrictFPOpcode() ? 1 : 0;
    // If we know the result of a setcc has the top bits zero, use this info.
    if (TLI->getBooleanContents(Op.getOperand(OpNo).getValueType()) ==
            TargetLowering::ZeroOrOneBooleanContent &&
        BitWidth > 1)
      Known.Zero.setBitsFrom(1);
    break;
  }
  case ISD::SHL: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
 
    bool NUW = Op->getFlags().hasNoUnsignedWrap();
    bool NSW = Op->getFlags().hasNoSignedWrap();
 
    bool ShAmtNonZero = Known2.isNonZero();
 
    Known = KnownBits::shl(Known, Known2, NUW, NSW, ShAmtNonZero);
 
    // Minimum shift low bits are known zero.
    if (std::optional<unsigned> ShMinAmt =
            getValidMinimumShiftAmount(Op, DemandedElts, Depth + 1))
      Known.Zero.setLowBits(*ShMinAmt);
    break;
  }
  case ISD::SRL:
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::lshr(Known, Known2, /*ShAmtNonZero=*/false,
                            Op->getFlags().hasExact());
 
    // Minimum shift high bits are known zero.
    if (std::optional<unsigned> ShMinAmt =
            getValidMinimumShiftAmount(Op, DemandedElts, Depth + 1))
      Known.Zero.setHighBits(*ShMinAmt);
    break;
  case ISD::SRA:
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::ashr(Known, Known2, /*ShAmtNonZero=*/false,
                            Op->getFlags().hasExact());
    break;
  case ISD::ROTL:
  case ISD::ROTR:
    if (ConstantSDNode *C =
            isConstOrConstSplat(Op.getOperand(1), DemandedElts)) {
      unsigned Amt = C->getAPIntValue().urem(BitWidth);
 
      Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
      // Canonicalize to ROTR.
      if (Opcode == ISD::ROTL && Amt != 0)
        Amt = BitWidth - Amt;
 
      Known.Zero = Known.Zero.rotr(Amt);
      Known.One = Known.One.rotr(Amt);
    }
    break;
  case ISD::FSHL:
  case ISD::FSHR:
    if (ConstantSDNode *C = isConstOrConstSplat(Op.getOperand(2), DemandedElts)) {
      unsigned Amt = C->getAPIntValue().urem(BitWidth);
 
      // For fshl, 0-shift returns the 1st arg.
      // For fshr, 0-shift returns the 2nd arg.
      if (Amt == 0) {
        Known = computeKnownBits(Op.getOperand(Opcode == ISD::FSHL ? 0 : 1),
                                 DemandedElts, Depth + 1);
        break;
      }
 
      // fshl: (X << (Z % BW)) | (Y >> (BW - (Z % BW)))
      // fshr: (X << (BW - (Z % BW))) | (Y >> (Z % BW))
      const APInt ShAmt(BitWidth, Amt);
      Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
      Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
      Known = Opcode == ISD::FSHL ? KnownBits::fshl(Known, Known2, ShAmt)
                                  : KnownBits::fshr(Known, Known2, ShAmt);
    }
    break;
  case ISD::SHL_PARTS:
  case ISD::SRA_PARTS:
  case ISD::SRL_PARTS: {
    assert((Op.getResNo() == 0 || Op.getResNo() == 1) && "Unknown result");
 
    // Collect lo/hi source values and concatenate.
    unsigned LoBits = Op.getOperand(0).getScalarValueSizeInBits();
    unsigned HiBits = Op.getOperand(1).getScalarValueSizeInBits();
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = Known2.concat(Known);
 
    // Collect shift amount.
    Known2 = computeKnownBits(Op.getOperand(2), DemandedElts, Depth + 1);
 
    if (Opcode == ISD::SHL_PARTS)
      Known = KnownBits::shl(Known, Known2);
    else if (Opcode == ISD::SRA_PARTS)
      Known = KnownBits::ashr(Known, Known2);
    else // if (Opcode == ISD::SRL_PARTS)
      Known = KnownBits::lshr(Known, Known2);
 
    // TODO: Minimum shift low/high bits are known zero.
 
    if (Op.getResNo() == 0)
      Known = Known.extractBits(LoBits, 0);
    else
      Known = Known.extractBits(HiBits, LoBits);
    break;
  }
  case ISD::SIGN_EXTEND_INREG: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    EVT EVT = cast<VTSDNode>(Op.getOperand(1))->getVT();
    Known = Known.sextInReg(EVT.getScalarSizeInBits());
    break;
  }
  case ISD::CTTZ:
  case ISD::CTTZ_ZERO_POISON: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // If we have a known 1, its position is our upper bound.
    unsigned PossibleTZ = Known2.countMaxTrailingZeros();
    unsigned LowBits = llvm::bit_width(PossibleTZ);
    Known.Zero.setBitsFrom(LowBits);
    break;
  }
  case ISD::CTLZ:
  case ISD::CTLZ_ZERO_POISON: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // If we have a known 1, its position is our upper bound.
    unsigned PossibleLZ = Known2.countMaxLeadingZeros();
    unsigned LowBits = llvm::bit_width(PossibleLZ);
    Known.Zero.setBitsFrom(LowBits);
    break;
  }
  case ISD::CTLS: {
    unsigned MinRedundantSignBits =
        ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1) - 1;
    ConstantRange Range(APInt(BitWidth, MinRedundantSignBits),
                        APInt(BitWidth, BitWidth));
    Known = Range.toKnownBits();
    break;
  }
  case ISD::CTPOP: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // If we know some of the bits are zero, they can't be one.
    unsigned PossibleOnes = Known2.countMaxPopulation();
    Known.Zero.setBitsFrom(llvm::bit_width(PossibleOnes));
    break;
  }
  case ISD::PARITY: {
    // Parity returns 0 everywhere but the LSB.
    Known.Zero.setBitsFrom(1);
    break;
  }
  case ISD::PDEP: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::pdep(Known2, Known);
    break;
  }
  case ISD::PEXT: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::pext(Known2, Known);
    break;
  }
  case ISD::CLMUL: {
    Known = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = KnownBits::clmul(Known, Known2);
    break;
  }
  case ISD::MGATHER:
  case ISD::MLOAD: {
    ISD::LoadExtType ETy =
        (Opcode == ISD::MGATHER)
            ? cast<MaskedGatherSDNode>(Op)->getExtensionType()
            : cast<MaskedLoadSDNode>(Op)->getExtensionType();
    if (ETy == ISD::ZEXTLOAD) {
      EVT MemVT = cast<MemSDNode>(Op)->getMemoryVT();
      KnownBits Known0(MemVT.getScalarSizeInBits());
      return Known0.zext(BitWidth);
    }
    break;
  }
  case ISD::LOAD: {
    LoadSDNode *LD = cast<LoadSDNode>(Op);
    const Constant *Cst = TLI->getTargetConstantFromLoad(LD);
    if (ISD::isNON_EXTLoad(LD) && Cst) {
      // Determine any common known bits from the loaded constant pool value.
      Type *CstTy = Cst->getType();
      if ((NumElts * BitWidth) == CstTy->getPrimitiveSizeInBits() &&
          !Op.getValueType().isScalableVector()) {
        // If its a vector splat, then we can (quickly) reuse the scalar path.
        // NOTE: We assume all elements match and none are UNDEF.
        if (CstTy->isVectorTy()) {
          if (const Constant *Splat = Cst->getSplatValue()) {
            Cst = Splat;
            CstTy = Cst->getType();
          }
        }
        // TODO - do we need to handle different bitwidths?
        if (CstTy->isVectorTy() && BitWidth == CstTy->getScalarSizeInBits()) {
          // Iterate across all vector elements finding common known bits.
          Known.setAllConflict();
          for (unsigned i = 0; i != NumElts; ++i) {
            if (!DemandedElts[i])
              continue;
            if (Constant *Elt = Cst->getAggregateElement(i)) {
              if (auto *CInt = dyn_cast<ConstantInt>(Elt)) {
                const APInt &Value = CInt->getValue();
                Known.One &= Value;
                Known.Zero &= ~Value;
                continue;
              }
              if (auto *CFP = dyn_cast<ConstantFP>(Elt)) {
                APInt Value = CFP->getValueAPF().bitcastToAPInt();
                Known.One &= Value;
                Known.Zero &= ~Value;
                continue;
              }
            }
            Known.One.clearAllBits();
            Known.Zero.clearAllBits();
            break;
          }
        } else if (BitWidth == CstTy->getPrimitiveSizeInBits()) {
          if (auto *CInt = dyn_cast<ConstantInt>(Cst)) {
            Known = KnownBits::makeConstant(CInt->getValue());
          } else if (auto *CFP = dyn_cast<ConstantFP>(Cst)) {
            Known =
                KnownBits::makeConstant(CFP->getValueAPF().bitcastToAPInt());
          }
        }
      }
    } else if (Op.getResNo() == 0) {
      unsigned ScalarMemorySize = LD->getMemoryVT().getScalarSizeInBits();
      KnownBits KnownScalarMemory(ScalarMemorySize);
      if (const MDNode *MD = LD->getRanges())
        computeKnownBitsFromRangeMetadata(*MD, KnownScalarMemory);
 
      // Extend the Known bits from memory to the size of the scalar result.
      if (ISD::isZEXTLoad(Op.getNode()))
        Known = KnownScalarMemory.zext(BitWidth);
      else if (ISD::isSEXTLoad(Op.getNode()))
        Known = KnownScalarMemory.sext(BitWidth);
      else if (ISD::isEXTLoad(Op.getNode()))
        Known = KnownScalarMemory.anyext(BitWidth);
      else
        Known = KnownScalarMemory;
      assert(Known.getBitWidth() == BitWidth);
      return Known;
    }
    break;
  }
  case ISD::ZERO_EXTEND_VECTOR_INREG: {
    if (Op.getValueType().isScalableVector())
      break;
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zext(InVT.getVectorNumElements());
    Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
    Known = Known.zext(BitWidth);
    break;
  }
  case ISD::ZERO_EXTEND: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.zext(BitWidth);
    break;
  }
  case ISD::SIGN_EXTEND_VECTOR_INREG: {
    if (Op.getValueType().isScalableVector())
      break;
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zext(InVT.getVectorNumElements());
    Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
    // If the sign bit is known to be zero or one, then sext will extend
    // it to the top bits, else it will just zext.
    Known = Known.sext(BitWidth);
    break;
  }
  case ISD::SIGN_EXTEND: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // If the sign bit is known to be zero or one, then sext will extend
    // it to the top bits, else it will just zext.
    Known = Known.sext(BitWidth);
    break;
  }
  case ISD::ANY_EXTEND_VECTOR_INREG: {
    if (Op.getValueType().isScalableVector())
      break;
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zext(InVT.getVectorNumElements());
    Known = computeKnownBits(Op.getOperand(0), InDemandedElts, Depth + 1);
    Known = Known.anyext(BitWidth);
    break;
  }
  case ISD::ANY_EXTEND: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.anyext(BitWidth);
    break;
  }
  case ISD::TRUNCATE: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.trunc(BitWidth);
    break;
  }
  case ISD::TRUNCATE_SSAT_S: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.truncSSat(BitWidth);
    break;
  }
  case ISD::TRUNCATE_SSAT_U: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.truncSSatU(BitWidth);
    break;
  }
  case ISD::TRUNCATE_USAT_U: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known.truncUSat(BitWidth);
    break;
  }
  case ISD::AssertZext: {
    EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
    APInt InMask = APInt::getLowBitsSet(BitWidth, VT.getSizeInBits());
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known.Zero |= (~InMask);
    Known.One  &= (~Known.Zero);
    break;
  }
  case ISD::AssertAlign: {
    unsigned LogOfAlign = Log2(cast<AssertAlignSDNode>(Op)->getAlign());
    assert(LogOfAlign != 0);
 
    // TODO: Should use maximum with source
    // If a node is guaranteed to be aligned, set low zero bits accordingly as
    // well as clearing one bits.
    Known.Zero.setLowBits(LogOfAlign);
    Known.One.clearLowBits(LogOfAlign);
    break;
  }
  case ISD::AssertNoFPClass: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
    FPClassTest NoFPClass =
        static_cast<FPClassTest>(Op.getConstantOperandVal(1));
    const FPClassTest NegativeTestMask = fcNan | fcNegative;
    if ((NoFPClass & NegativeTestMask) == NegativeTestMask) {
      // Cannot be negative.
      Known.makeNonNegative();
    }
 
    const FPClassTest PositiveTestMask = fcNan | fcPositive;
    if ((NoFPClass & PositiveTestMask) == PositiveTestMask) {
      // Cannot be positive.
      Known.makeNegative();
    }
 
    break;
  }
  case ISD::FABS:
    // fabs clears the sign bit
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known.makeNonNegative();
    break;
  case ISD::FGETSIGN:
    // All bits are zero except the low bit.
    Known.Zero.setBitsFrom(1);
    break;
  case ISD::ADD: {
    SDNodeFlags Flags = Op.getNode()->getFlags();
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    bool SelfAdd = Op.getOperand(0) == Op.getOperand(1) &&
                   isGuaranteedNotToBeUndefOrPoison(
                       Op.getOperand(0), DemandedElts,
                       UndefPoisonKind::UndefOrPoison, Depth + 1);
    Known = KnownBits::add(Known, Known2, Flags.hasNoSignedWrap(),
                           Flags.hasNoUnsignedWrap(), SelfAdd);
    break;
  }
  case ISD::SUB: {
    SDNodeFlags Flags = Op.getNode()->getFlags();
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::sub(Known, Known2, Flags.hasNoSignedWrap(),
                           Flags.hasNoUnsignedWrap());
    break;
  }
  case ISD::USUBO:
  case ISD::SSUBO:
  case ISD::USUBO_CARRY:
  case ISD::SSUBO_CARRY:
    if (Op.getResNo() == 1) {
      // If we know the result of a setcc has the top bits zero, use this info.
      if (TLI->getBooleanContents(Op.getOperand(0).getValueType()) ==
              TargetLowering::ZeroOrOneBooleanContent &&
          BitWidth > 1)
        Known.Zero.setBitsFrom(1);
      break;
    }
    [[fallthrough]];
  case ISD::SUBC: {
    assert(Op.getResNo() == 0 &&
           "We only compute knownbits for the difference here.");
 
    // With USUBO_CARRY and SSUBO_CARRY a borrow bit may be added in.
    KnownBits Borrow(1);
    if (Opcode == ISD::USUBO_CARRY || Opcode == ISD::SSUBO_CARRY) {
      Borrow = computeKnownBits(Op.getOperand(2), DemandedElts, Depth + 1);
      // Borrow has bit width 1
      Borrow = Borrow.trunc(1);
    } else {
      Borrow.setAllZero();
    }
 
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::computeForSubBorrow(Known, Known2, Borrow);
    break;
  }
  case ISD::UADDO:
  case ISD::SADDO:
  case ISD::UADDO_CARRY:
  case ISD::SADDO_CARRY:
    if (Op.getResNo() == 1) {
      // If we know the result of a setcc has the top bits zero, use this info.
      if (TLI->getBooleanContents(Op.getOperand(0).getValueType()) ==
              TargetLowering::ZeroOrOneBooleanContent &&
          BitWidth > 1)
        Known.Zero.setBitsFrom(1);
      break;
    }
    [[fallthrough]];
  case ISD::ADDC:
  case ISD::ADDE: {
    assert(Op.getResNo() == 0 && "We only compute knownbits for the sum here.");
 
    // With ADDE and UADDO_CARRY, a carry bit may be added in.
    KnownBits Carry(1);
    if (Opcode == ISD::ADDE)
      // Can't track carry from glue, set carry to unknown.
      Carry.resetAll();
    else if (Opcode == ISD::UADDO_CARRY || Opcode == ISD::SADDO_CARRY) {
      Carry = computeKnownBits(Op.getOperand(2), DemandedElts, Depth + 1);
      // Carry has bit width 1
      Carry = Carry.trunc(1);
    } else {
      Carry.setAllZero();
    }
 
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::computeForAddCarry(Known, Known2, Carry);
    break;
  }
  case ISD::UDIV: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::udiv(Known, Known2, Op->getFlags().hasExact());
    break;
  }
  case ISD::SDIV: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::sdiv(Known, Known2, Op->getFlags().hasExact());
    break;
  }
  case ISD::SREM: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::srem(Known, Known2);
    break;
  }
  case ISD::UREM: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::urem(Known, Known2);
    break;
  }
  case ISD::EXTRACT_ELEMENT: {
    Known = computeKnownBits(Op.getOperand(0), Depth+1);
    const unsigned Index = Op.getConstantOperandVal(1);
    const unsigned EltBitWidth = Op.getValueSizeInBits();
 
    // Remove low part of known bits mask
    Known.Zero = Known.Zero.getHiBits(Known.getBitWidth() - Index * EltBitWidth);
    Known.One = Known.One.getHiBits(Known.getBitWidth() - Index * EltBitWidth);
 
    // Remove high part of known bit mask
    Known = Known.trunc(EltBitWidth);
    break;
  }
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue InVec = Op.getOperand(0);
    SDValue EltNo = Op.getOperand(1);
    EVT VecVT = InVec.getValueType();
    // computeKnownBits not yet implemented for scalable vectors.
    if (VecVT.isScalableVector())
      break;
    const unsigned EltBitWidth = VecVT.getScalarSizeInBits();
    const unsigned NumSrcElts = VecVT.getVectorNumElements();
 
    // If BitWidth > EltBitWidth the value is anyext:ed. So we do not know
    // anything about the extended bits.
    if (BitWidth > EltBitWidth)
      Known = Known.trunc(EltBitWidth);
 
    // If we know the element index, just demand that vector element, else for
    // an unknown element index, ignore DemandedElts and demand them all.
    APInt DemandedSrcElts = APInt::getAllOnes(NumSrcElts);
    auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
    if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts))
      DemandedSrcElts =
          APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue());
 
    Known = computeKnownBits(InVec, DemandedSrcElts, Depth + 1);
    if (BitWidth > EltBitWidth)
      Known = Known.anyext(BitWidth);
    break;
  }
  case ISD::INSERT_VECTOR_ELT: {
    if (Op.getValueType().isScalableVector())
      break;
 
    // If we know the element index, split the demand between the
    // source vector and the inserted element, otherwise assume we need
    // the original demanded vector elements and the value.
    SDValue InVec = Op.getOperand(0);
    SDValue InVal = Op.getOperand(1);
    SDValue EltNo = Op.getOperand(2);
    bool DemandedVal = true;
    APInt DemandedVecElts = DemandedElts;
    auto *CEltNo = dyn_cast<ConstantSDNode>(EltNo);
    if (CEltNo && CEltNo->getAPIntValue().ult(NumElts)) {
      unsigned EltIdx = CEltNo->getZExtValue();
      DemandedVal = !!DemandedElts[EltIdx];
      DemandedVecElts.clearBit(EltIdx);
    }
    Known.setAllConflict();
    if (DemandedVal) {
      Known2 = computeKnownBits(InVal, Depth + 1);
      Known = Known.intersectWith(Known2.zextOrTrunc(BitWidth));
    }
    if (!!DemandedVecElts) {
      Known2 = computeKnownBits(InVec, DemandedVecElts, Depth + 1);
      Known = Known.intersectWith(Known2);
    }
    break;
  }
  case ISD::BITREVERSE: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known2.reverseBits();
    break;
  }
  case ISD::BSWAP: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known2.byteSwap();
    break;
  }
  case ISD::ABS:
  case ISD::ABS_MIN_POISON: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known2.abs();
    Known.Zero.setHighBits(
        ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1) - 1);
    break;
  }
  case ISD::USUBSAT: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::usub_sat(Known, Known2);
    break;
  }
  case ISD::UMIN: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::umin(Known, Known2);
    break;
  }
  case ISD::UMAX: {
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::umax(Known, Known2);
    break;
  }
  case ISD::SMIN:
  case ISD::SMAX: {
    // If we have a clamp pattern, we know that the number of sign bits will be
    // the minimum of the clamp min/max range.
    bool IsMax = (Opcode == ISD::SMAX);
    ConstantSDNode *CstLow = nullptr, *CstHigh = nullptr;
    if ((CstLow = isConstOrConstSplat(Op.getOperand(1), DemandedElts)))
      if (Op.getOperand(0).getOpcode() == (IsMax ? ISD::SMIN : ISD::SMAX))
        CstHigh =
            isConstOrConstSplat(Op.getOperand(0).getOperand(1), DemandedElts);
    if (CstLow && CstHigh) {
      if (!IsMax)
        std::swap(CstLow, CstHigh);
 
      const APInt &ValueLow = CstLow->getAPIntValue();
      const APInt &ValueHigh = CstHigh->getAPIntValue();
      if (ValueLow.sle(ValueHigh)) {
        unsigned LowSignBits = ValueLow.getNumSignBits();
        unsigned HighSignBits = ValueHigh.getNumSignBits();
        unsigned MinSignBits = std::min(LowSignBits, HighSignBits);
        if (ValueLow.isNegative() && ValueHigh.isNegative()) {
          Known.One.setHighBits(MinSignBits);
          break;
        }
        if (ValueLow.isNonNegative() && ValueHigh.isNonNegative()) {
          Known.Zero.setHighBits(MinSignBits);
          break;
        }
      }
    }
 
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (IsMax)
      Known = KnownBits::smax(Known, Known2);
    else
      Known = KnownBits::smin(Known, Known2);
 
    // For SMAX, if CstLow is non-negative we know the result will be
    // non-negative and thus all sign bits are 0.
    // TODO: There's an equivalent of this for smin with negative constant for
    // known ones.
    if (IsMax && CstLow) {
      const APInt &ValueLow = CstLow->getAPIntValue();
      if (ValueLow.isNonNegative()) {
        unsigned SignBits = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
        Known.Zero.setHighBits(std::min(SignBits, ValueLow.getNumSignBits()));
      }
    }
 
    break;
  }
  case ISD::UINT_TO_FP: {
    Known.makeNonNegative();
    break;
  }
  case ISD::SINT_TO_FP: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Known2.isNonNegative())
      Known.makeNonNegative();
    else if (Known2.isNegative())
      Known.makeNegative();
    break;
  }
  case ISD::FP_TO_UINT_SAT: {
    // FP_TO_UINT_SAT produces an unsigned value that fits in the saturating VT.
    EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
    Known.Zero |= APInt::getBitsSetFrom(BitWidth, VT.getScalarSizeInBits());
    break;
  }
  case ISD::ATOMIC_LOAD: {
    // If we are looking at the loaded value.
    if (Op.getResNo() == 0) {
      auto *AT = cast<AtomicSDNode>(Op);
      unsigned ScalarMemorySize = AT->getMemoryVT().getScalarSizeInBits();
      KnownBits KnownScalarMemory(ScalarMemorySize);
      if (const MDNode *MD = AT->getRanges())
        computeKnownBitsFromRangeMetadata(*MD, KnownScalarMemory);
 
      switch (AT->getExtensionType()) {
      case ISD::ZEXTLOAD:
        Known = KnownScalarMemory.zext(BitWidth);
        break;
      case ISD::SEXTLOAD:
        Known = KnownScalarMemory.sext(BitWidth);
        break;
      case ISD::EXTLOAD:
        switch (TLI->getExtendForAtomicOps()) {
        case ISD::ZERO_EXTEND:
          Known = KnownScalarMemory.zext(BitWidth);
          break;
        case ISD::SIGN_EXTEND:
          Known = KnownScalarMemory.sext(BitWidth);
          break;
        default:
          Known = KnownScalarMemory.anyext(BitWidth);
          break;
        }
        break;
      case ISD::NON_EXTLOAD:
        Known = KnownScalarMemory;
        break;
      }
      assert(Known.getBitWidth() == BitWidth);
    }
    break;
  }
  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
    if (Op.getResNo() == 1) {
      // The boolean result conforms to getBooleanContents.
      // If we know the result of a setcc has the top bits zero, use this info.
      // We know that we have an integer-based boolean since these operations
      // are only available for integer.
      if (TLI->getBooleanContents(Op.getValueType().isVector(), false) ==
              TargetLowering::ZeroOrOneBooleanContent &&
          BitWidth > 1)
        Known.Zero.setBitsFrom(1);
      break;
    }
    [[fallthrough]];
  case ISD::ATOMIC_CMP_SWAP:
  case ISD::ATOMIC_SWAP:
  case ISD::ATOMIC_LOAD_ADD:
  case ISD::ATOMIC_LOAD_SUB:
  case ISD::ATOMIC_LOAD_AND:
  case ISD::ATOMIC_LOAD_CLR:
  case ISD::ATOMIC_LOAD_OR:
  case ISD::ATOMIC_LOAD_XOR:
  case ISD::ATOMIC_LOAD_NAND:
  case ISD::ATOMIC_LOAD_MIN:
  case ISD::ATOMIC_LOAD_MAX:
  case ISD::ATOMIC_LOAD_UMIN:
  case ISD::ATOMIC_LOAD_UMAX: {
    // If we are looking at the loaded value.
    if (Op.getResNo() == 0) {
      auto *AT = cast<AtomicSDNode>(Op);
      unsigned MemBits = AT->getMemoryVT().getScalarSizeInBits();
 
      if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
        Known.Zero.setBitsFrom(MemBits);
    }
    break;
  }
  case ISD::FrameIndex:
  case ISD::TargetFrameIndex: {
    const MachineFunction &MF = getMachineFunction();
    int FrameIdx = cast<FrameIndexSDNode>(Op)->getIndex();
    TLI->computeKnownBitsForStackObjectPointer(
        Known, MF, MF.getFrameInfo().getObjectAlign(FrameIdx));
    break;
  }
 
  default:
    if (Opcode < ISD::BUILTIN_OP_END)
      break;
    [[fallthrough]];
  case ISD::INTRINSIC_WO_CHAIN:
  case ISD::INTRINSIC_W_CHAIN:
  case ISD::INTRINSIC_VOID:
    // Allow the target to implement this method for its nodes.
    TLI->computeKnownBitsForTargetNode(Op, Known, DemandedElts, *this, Depth);
    break;
  }
 
  return Known;
}
 
/// Convert ConstantRange OverflowResult into SelectionDAG::OverflowKind.
static SelectionDAG::OverflowKind mapOverflowResult(ConstantRange::OverflowResult OR) {
  switch (OR) {
  case ConstantRange::OverflowResult::MayOverflow:
    return SelectionDAG::OFK_Sometime;
  case ConstantRange::OverflowResult::AlwaysOverflowsLow:
  case ConstantRange::OverflowResult::AlwaysOverflowsHigh:
    return SelectionDAG::OFK_Always;
  case ConstantRange::OverflowResult::NeverOverflows:
    return SelectionDAG::OFK_Never;
  }
  llvm_unreachable("Unknown OverflowResult");
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForSignedAdd(SDValue N0, SDValue N1) const {
  // X + 0 never overflow
  if (isNullConstant(N1))
    return OFK_Never;
 
  // If both operands each have at least two sign bits, the addition
  // cannot overflow.
  if (ComputeNumSignBits(N0) > 1 && ComputeNumSignBits(N1) > 1)
    return OFK_Never;
 
  // TODO: Add ConstantRange::signedAddMayOverflow handling.
  return OFK_Sometime;
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForUnsignedAdd(SDValue N0, SDValue N1) const {
  // X + 0 never overflow
  if (isNullConstant(N1))
    return OFK_Never;
 
  // mulhi + 1 never overflow
  KnownBits N1Known = computeKnownBits(N1);
  if (N0.getOpcode() == ISD::UMUL_LOHI && N0.getResNo() == 1 &&
      N1Known.getMaxValue().ult(2))
    return OFK_Never;
 
  KnownBits N0Known = computeKnownBits(N0);
  if (N1.getOpcode() == ISD::UMUL_LOHI && N1.getResNo() == 1 &&
      N0Known.getMaxValue().ult(2))
    return OFK_Never;
 
  // Fallback to ConstantRange::unsignedAddMayOverflow handling.
  ConstantRange N0Range = ConstantRange::fromKnownBits(N0Known, false);
  ConstantRange N1Range = ConstantRange::fromKnownBits(N1Known, false);
  return mapOverflowResult(N0Range.unsignedAddMayOverflow(N1Range));
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForSignedSub(SDValue N0, SDValue N1) const {
  // X - 0 never overflow
  if (isNullConstant(N1))
    return OFK_Never;
 
  // If both operands each have at least two sign bits, the subtraction
  // cannot overflow.
  if (ComputeNumSignBits(N0) > 1 && ComputeNumSignBits(N1) > 1)
    return OFK_Never;
 
  KnownBits N0Known = computeKnownBits(N0);
  KnownBits N1Known = computeKnownBits(N1);
  ConstantRange N0Range = ConstantRange::fromKnownBits(N0Known, true);
  ConstantRange N1Range = ConstantRange::fromKnownBits(N1Known, true);
  return mapOverflowResult(N0Range.signedSubMayOverflow(N1Range));
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForUnsignedSub(SDValue N0, SDValue N1) const {
  // X - 0 never overflow
  if (isNullConstant(N1))
    return OFK_Never;
 
  ConstantRange N0Range =
      computeConstantRangeIncludingKnownBits(N0, /*ForSigned=*/false);
  ConstantRange N1Range =
      computeConstantRangeIncludingKnownBits(N1, /*ForSigned=*/false);
  return mapOverflowResult(N0Range.unsignedSubMayOverflow(N1Range));
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForUnsignedMul(SDValue N0, SDValue N1) const {
  // X * 0 and X * 1 never overflow.
  if (isNullConstant(N1) || isOneConstant(N1))
    return OFK_Never;
 
  ConstantRange N0Range = computeConstantRangeIncludingKnownBits(N0, false);
  ConstantRange N1Range = computeConstantRangeIncludingKnownBits(N1, false);
  return mapOverflowResult(N0Range.unsignedMulMayOverflow(N1Range));
}
 
SelectionDAG::OverflowKind
SelectionDAG::computeOverflowForSignedMul(SDValue N0, SDValue N1) const {
  // X * 0 and X * 1 never overflow.
  if (isNullConstant(N1) || isOneConstant(N1))
    return OFK_Never;
 
  // Get the size of the result.
  unsigned BitWidth = N0.getScalarValueSizeInBits();
 
  // Sum of the sign bits.
  unsigned SignBits = ComputeNumSignBits(N0) + ComputeNumSignBits(N1);
 
  // If we have enough sign bits, then there's no overflow.
  if (SignBits > BitWidth + 1)
    return OFK_Never;
 
  if (SignBits == BitWidth + 1) {
    // The overflow occurs when the true multiplication of the
    // the operands is the minimum negative number.
    KnownBits N0Known = computeKnownBits(N0);
    KnownBits N1Known = computeKnownBits(N1);
    // If one of the operands is non-negative, then there's no
    // overflow.
    if (N0Known.isNonNegative() || N1Known.isNonNegative())
      return OFK_Never;
  }
 
  return OFK_Sometime;
}
 
ConstantRange SelectionDAG::computeConstantRange(SDValue Op, bool ForSigned,
                                                 unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return computeConstantRange(Op, DemandedElts, ForSigned, Depth);
}
 
ConstantRange SelectionDAG::computeConstantRange(SDValue Op,
                                                 const APInt &DemandedElts,
                                                 bool ForSigned,
                                                 unsigned Depth) const {
  EVT VT = Op.getValueType();
  unsigned BitWidth = VT.getScalarSizeInBits();
 
  if (Depth >= MaxRecursionDepth)
    return ConstantRange::getFull(BitWidth);
 
  if (ConstantSDNode *C = isConstOrConstSplat(Op, DemandedElts))
    return ConstantRange(C->getAPIntValue());
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  case ISD::VSCALE: {
    const Function &F = getMachineFunction().getFunction();
    const APInt &Multiplier = Op.getConstantOperandAPInt(0);
    return getVScaleRange(&F, BitWidth).multiply(Multiplier);
  }
  default:
    break;
  }
 
  return ConstantRange::getFull(BitWidth);
}
 
ConstantRange
SelectionDAG::computeConstantRangeIncludingKnownBits(SDValue Op, bool ForSigned,
                                                     unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return computeConstantRangeIncludingKnownBits(Op, DemandedElts, ForSigned,
                                                Depth);
}
 
ConstantRange SelectionDAG::computeConstantRangeIncludingKnownBits(
    SDValue Op, const APInt &DemandedElts, bool ForSigned,
    unsigned Depth) const {
  KnownBits Known = computeKnownBits(Op, DemandedElts, Depth);
  ConstantRange CR1 = ConstantRange::fromKnownBits(Known, ForSigned);
  ConstantRange CR2 = computeConstantRange(Op, DemandedElts, ForSigned, Depth);
  ConstantRange::PreferredRangeType RangeType =
      ForSigned ? ConstantRange::Signed : ConstantRange::Unsigned;
  return CR1.intersectWith(CR2, RangeType);
}
 
bool SelectionDAG::isKnownToBeAPowerOfTwo(SDValue Val, bool OrZero,
                                          unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Val);
  return isKnownToBeAPowerOfTwo(Val, DemandedElts, OrZero, Depth);
}
 
bool SelectionDAG::isKnownToBeAPowerOfTwo(SDValue Val,
                                          const APInt &DemandedElts,
                                          bool OrZero, unsigned Depth) const {
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  EVT OpVT = Val.getValueType();
  unsigned BitWidth = OpVT.getScalarSizeInBits();
  [[maybe_unused]] unsigned NumElts = DemandedElts.getBitWidth();
  assert((!OpVT.isScalableVector() || NumElts == 1) &&
         "DemandedElts for scalable vectors must be 1 to represent all lanes");
  assert(
      (!OpVT.isFixedLengthVector() || NumElts == OpVT.getVectorNumElements()) &&
      "Unexpected vector size");
 
  auto IsPowerOfTwoOrZero = [BitWidth, OrZero](const ConstantSDNode *C) {
    APInt V = C->getAPIntValue().zextOrTrunc(BitWidth);
    return (OrZero && V.isZero()) || V.isPowerOf2();
  };
 
  // Is the constant a known power of 2 or zero?
  if (ISD::matchUnaryPredicate(Val, DemandedElts, IsPowerOfTwoOrZero,
                               /*AllowUndefs=*/false, /*AllowTruncation=*/true))
    return true;
 
  switch (Val.getOpcode()) {
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue InVec = Val.getOperand(0);
    SDValue EltNo = Val.getOperand(1);
    EVT VecVT = InVec.getValueType();
 
    // Skip scalable vectors or implicit extensions.
    if (VecVT.isScalableVector() ||
        OpVT.getScalarSizeInBits() != VecVT.getScalarSizeInBits())
      break;
 
    // If we know the element index, just demand that vector element, else for
    // an unknown element index, ignore DemandedElts and demand them all.
    const unsigned NumSrcElts = VecVT.getVectorNumElements();
    auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
    APInt DemandedSrcElts =
        ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts)
            ? APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue())
            : APInt::getAllOnes(NumSrcElts);
    return isKnownToBeAPowerOfTwo(InVec, DemandedSrcElts, OrZero, Depth + 1);
  }
 
  case ISD::AND: {
    // Looking for `x & -x` pattern:
    // If x == 0:
    //    x & -x -> 0
    // If x != 0:
    //    x & -x -> non-zero pow2
    // so if we find the pattern return whether we know `x` is non-zero.
    SDValue X, Z;
    if (sd_match(Val, m_And(m_Value(X), m_Neg(m_Deferred(X)))) ||
        (sd_match(Val, m_And(m_Value(X), m_Sub(m_Value(Z), m_Deferred(X)))) &&
         MaskedVectorIsZero(Z, DemandedElts, Depth + 1)))
      return OrZero || isKnownNeverZero(X, DemandedElts, Depth);
    break;
  }
 
  case ISD::SHL: {
    // A left-shift of a constant one will have exactly one bit set because
    // shifting the bit off the end is undefined.
    auto *C = isConstOrConstSplat(Val.getOperand(0), DemandedElts);
    if (C && C->getAPIntValue() == 1)
      return true;
    return (OrZero || isKnownNeverZero(Val, DemandedElts, Depth)) &&
           isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
  }
 
  case ISD::SRL: {
    // A logical right-shift of a constant sign-bit will have exactly
    // one bit set.
    auto *C = isConstOrConstSplat(Val.getOperand(0), DemandedElts);
    if (C && C->getAPIntValue().isSignMask())
      return true;
    return (OrZero || isKnownNeverZero(Val, DemandedElts, Depth)) &&
           isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
  }
 
  case ISD::TRUNCATE:
    return (OrZero || isKnownNeverZero(Val, DemandedElts, Depth)) &&
           isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
 
  case ISD::ROTL:
  case ISD::ROTR:
    return isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
  case ISD::BSWAP:
  case ISD::BITREVERSE:
    return isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
 
  case ISD::SMIN:
  case ISD::SMAX:
  case ISD::UMIN:
  case ISD::UMAX:
    return isKnownToBeAPowerOfTwo(Val.getOperand(1), DemandedElts, OrZero,
                                  Depth + 1) &&
           isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
 
  case ISD::SELECT:
  case ISD::VSELECT:
    return isKnownToBeAPowerOfTwo(Val.getOperand(2), DemandedElts, OrZero,
                                  Depth + 1) &&
           isKnownToBeAPowerOfTwo(Val.getOperand(1), DemandedElts, OrZero,
                                  Depth + 1);
 
  case ISD::ZERO_EXTEND:
    return isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedElts, OrZero,
                                  Depth + 1);
 
  case ISD::VSCALE:
    // vscale(power-of-two) is a power-of-two
    return isKnownToBeAPowerOfTwo(Val.getOperand(0), /*OrZero=*/false,
                                  Depth + 1);
 
  case ISD::VECTOR_SHUFFLE: {
    assert(!Val.getValueType().isScalableVector());
    // Demanded elements with undef shuffle mask elements are unknown
    // - we cannot guarantee they are a power of two, so return false.
    APInt DemandedLHS, DemandedRHS;
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Val);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    if (!getShuffleDemandedElts(NumElts, SVN->getMask(), DemandedElts,
                                DemandedLHS, DemandedRHS))
      return false;
 
    // All demanded elements from LHS must be known power of two.
    if (!!DemandedLHS && !isKnownToBeAPowerOfTwo(Val.getOperand(0), DemandedLHS,
                                                 OrZero, Depth + 1))
      return false;
 
    // All demanded elements from RHS must be known power of two.
    if (!!DemandedRHS && !isKnownToBeAPowerOfTwo(Val.getOperand(1), DemandedRHS,
                                                 OrZero, Depth + 1))
      return false;
 
    return true;
  }
  }
 
  // More could be done here, though the above checks are enough
  // to handle some common cases.
  return false;
}
 
bool SelectionDAG::isKnownToBeAPowerOfTwoFP(SDValue Val, unsigned Depth) const {
  if (ConstantFPSDNode *C1 = isConstOrConstSplatFP(Val, true))
    return C1->getValueAPF().getExactLog2Abs() >= 0;
 
  if (Val.getOpcode() == ISD::UINT_TO_FP || Val.getOpcode() == ISD::SINT_TO_FP)
    return isKnownToBeAPowerOfTwo(Val.getOperand(0), Depth + 1);
 
  return false;
}
 
unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return ComputeNumSignBits(Op, DemandedElts, Depth);
}
 
unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, const APInt &DemandedElts,
                                          unsigned Depth) const {
  EVT VT = Op.getValueType();
  assert((VT.isInteger() || VT.isFloatingPoint()) && "Invalid VT!");
  unsigned VTBits = VT.getScalarSizeInBits();
  unsigned NumElts = DemandedElts.getBitWidth();
  unsigned Tmp, Tmp2;
  unsigned FirstAnswer = 1;
 
  assert((!VT.isScalableVector() || NumElts == 1) &&
         "DemandedElts for scalable vectors must be 1 to represent all lanes");
 
  if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
    const APInt &Val = C->getAPIntValue();
    return Val.getNumSignBits();
  }
 
  if (Depth >= MaxRecursionDepth)
    return 1;  // Limit search depth.
 
  if (!DemandedElts)
    return 1;  // No demanded elts, better to assume we don't know anything.
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  default: break;
  case ISD::AssertSext:
    Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getSizeInBits();
    return VTBits-Tmp+1;
  case ISD::AssertZext:
    Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getSizeInBits();
    return VTBits-Tmp;
  case ISD::FREEZE:
    if (isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), DemandedElts,
                                         UndefPoisonKind::UndefOrPoison))
      return ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    break;
  case ISD::MERGE_VALUES:
    return ComputeNumSignBits(Op.getOperand(Op.getResNo()), DemandedElts,
                              Depth + 1);
  case ISD::SPLAT_VECTOR: {
    // Check if the sign bits of source go down as far as the truncated value.
    unsigned NumSrcBits = Op.getOperand(0).getValueSizeInBits();
    unsigned NumSrcSignBits = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
    if (NumSrcSignBits > (NumSrcBits - VTBits))
      return NumSrcSignBits - (NumSrcBits - VTBits);
    break;
  }
  case ISD::BUILD_VECTOR:
    assert(!VT.isScalableVector());
    Tmp = VTBits;
    for (unsigned i = 0, e = Op.getNumOperands(); (i < e) && (Tmp > 1); ++i) {
      if (!DemandedElts[i])
        continue;
 
      SDValue SrcOp = Op.getOperand(i);
      // BUILD_VECTOR can implicitly truncate sources, we handle this specially
      // for constant nodes to ensure we only look at the sign bits.
      if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(SrcOp)) {
        APInt T = C->getAPIntValue().trunc(VTBits);
        Tmp2 = T.getNumSignBits();
      } else {
        Tmp2 = ComputeNumSignBits(SrcOp, Depth + 1);
 
        if (SrcOp.getValueSizeInBits() != VTBits) {
          assert(SrcOp.getValueSizeInBits() > VTBits &&
                 "Expected BUILD_VECTOR implicit truncation");
          unsigned ExtraBits = SrcOp.getValueSizeInBits() - VTBits;
          Tmp2 = (Tmp2 > ExtraBits ? Tmp2 - ExtraBits : 1);
        }
      }
      Tmp = std::min(Tmp, Tmp2);
    }
    return Tmp;
 
  case ISD::VECTOR_COMPRESS: {
    SDValue Vec = Op.getOperand(0);
    SDValue PassThru = Op.getOperand(2);
    Tmp = ComputeNumSignBits(PassThru, DemandedElts, Depth + 1);
    if (Tmp == 1)
      return 1;
    Tmp2 = ComputeNumSignBits(Vec, Depth + 1);
    Tmp = std::min(Tmp, Tmp2);
    return Tmp;
  }
 
  case ISD::VECTOR_SHUFFLE: {
    // Collect the minimum number of sign bits that are shared by every vector
    // element referenced by the shuffle.
    APInt DemandedLHS, DemandedRHS;
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Op);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    if (!getShuffleDemandedElts(NumElts, SVN->getMask(), DemandedElts,
                                DemandedLHS, DemandedRHS))
      return 1;
 
    Tmp = std::numeric_limits<unsigned>::max();
    if (!!DemandedLHS)
      Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedLHS, Depth + 1);
    if (!!DemandedRHS) {
      Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedRHS, Depth + 1);
      Tmp = std::min(Tmp, Tmp2);
    }
    // If we don't know anything, early out and try computeKnownBits fall-back.
    if (Tmp == 1)
      break;
    assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
    return Tmp;
  }
 
  case ISD::BITCAST: {
    if (VT.isScalableVector())
      break;
    SDValue N0 = Op.getOperand(0);
    EVT SrcVT = N0.getValueType();
    unsigned SrcBits = SrcVT.getScalarSizeInBits();
 
    // Ignore bitcasts from unsupported types..
    if (!(SrcVT.isInteger() || SrcVT.isFloatingPoint()))
      break;
 
    // Fast handling of 'identity' bitcasts.
    if (VTBits == SrcBits)
      return ComputeNumSignBits(N0, DemandedElts, Depth + 1);
 
    bool IsLE = getDataLayout().isLittleEndian();
 
    // Bitcast 'large element' scalar/vector to 'small element' vector.
    if ((SrcBits % VTBits) == 0) {
      assert(VT.isVector() && "Expected bitcast to vector");
 
      unsigned Scale = SrcBits / VTBits;
      APInt SrcDemandedElts =
          APIntOps::ScaleBitMask(DemandedElts, NumElts / Scale);
 
      // Fast case - sign splat can be simply split across the small elements.
      Tmp = ComputeNumSignBits(N0, SrcDemandedElts, Depth + 1);
      if (Tmp == SrcBits)
        return VTBits;
 
      // Slow case - determine how far the sign extends into each sub-element.
      Tmp2 = VTBits;
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i]) {
          unsigned SubOffset = i % Scale;
          SubOffset = (IsLE ? ((Scale - 1) - SubOffset) : SubOffset);
          SubOffset = SubOffset * VTBits;
          if (Tmp <= SubOffset)
            return 1;
          Tmp2 = std::min(Tmp2, Tmp - SubOffset);
        }
      return Tmp2;
    }
    break;
  }
 
  case ISD::FP_TO_SINT_SAT:
    // FP_TO_SINT_SAT produces a signed value that fits in the saturating VT.
    Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getScalarSizeInBits();
    return VTBits - Tmp + 1;
  case ISD::SIGN_EXTEND:
    Tmp = VTBits - Op.getOperand(0).getScalarValueSizeInBits();
    return ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth+1) + Tmp;
  case ISD::SIGN_EXTEND_INREG:
    // Max of the input and what this extends.
    Tmp = cast<VTSDNode>(Op.getOperand(1))->getVT().getScalarSizeInBits();
    Tmp = VTBits-Tmp+1;
    Tmp2 = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth+1);
    return std::max(Tmp, Tmp2);
  case ISD::SIGN_EXTEND_VECTOR_INREG: {
    if (VT.isScalableVector())
      break;
    SDValue Src = Op.getOperand(0);
    EVT SrcVT = Src.getValueType();
    APInt DemandedSrcElts = DemandedElts.zext(SrcVT.getVectorNumElements());
    Tmp = VTBits - SrcVT.getScalarSizeInBits();
    return ComputeNumSignBits(Src, DemandedSrcElts, Depth+1) + Tmp;
  }
  case ISD::SRA:
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // SRA X, C -> adds C sign bits.
    if (std::optional<unsigned> ShAmt =
            getValidMinimumShiftAmount(Op, DemandedElts, Depth + 1))
      Tmp = std::min(Tmp + *ShAmt, VTBits);
    return Tmp;
  case ISD::SHL:
    if (std::optional<ConstantRange> ShAmtRange =
            getValidShiftAmountRange(Op, DemandedElts, Depth + 1)) {
      unsigned MaxShAmt = ShAmtRange->getUnsignedMax().getZExtValue();
      unsigned MinShAmt = ShAmtRange->getUnsignedMin().getZExtValue();
      // Try to look through ZERO/SIGN/ANY_EXTEND. If all extended bits are
      // shifted out, then we can compute the number of sign bits for the
      // operand being extended. A future improvement could be to pass along the
      // "shifted left by" information in the recursive calls to
      // ComputeKnownSignBits. Allowing us to handle this more generically.
      if (ISD::isExtOpcode(Op.getOperand(0).getOpcode())) {
        SDValue Ext = Op.getOperand(0);
        EVT ExtVT = Ext.getValueType();
        SDValue Extendee = Ext.getOperand(0);
        EVT ExtendeeVT = Extendee.getValueType();
        unsigned SizeDifference =
            ExtVT.getScalarSizeInBits() - ExtendeeVT.getScalarSizeInBits();
        if (SizeDifference <= MinShAmt) {
          Tmp = SizeDifference +
                ComputeNumSignBits(Extendee, DemandedElts, Depth + 1);
          if (MaxShAmt < Tmp)
            return Tmp - MaxShAmt;
        }
      }
      // shl destroys sign bits, ensure it doesn't shift out all sign bits.
      Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
      if (MaxShAmt < Tmp)
        return Tmp - MaxShAmt;
    }
    break;
  case ISD::AND:
  case ISD::OR:
  case ISD::XOR:    // NOT is handled here.
    // Logical binary ops preserve the number of sign bits at the worst.
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth+1);
    if (Tmp != 1) {
      Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth+1);
      FirstAnswer = std::min(Tmp, Tmp2);
      // We computed what we know about the sign bits as our first
      // answer. Now proceed to the generic code that uses
      // computeKnownBits, and pick whichever answer is better.
    }
    break;
 
  case ISD::SELECT:
  case ISD::VSELECT:
    Tmp = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth+1);
    if (Tmp == 1) return 1;  // Early out.
    Tmp2 = ComputeNumSignBits(Op.getOperand(2), DemandedElts, Depth+1);
    return std::min(Tmp, Tmp2);
  case ISD::SELECT_CC:
    Tmp = ComputeNumSignBits(Op.getOperand(2), DemandedElts, Depth+1);
    if (Tmp == 1) return 1;  // Early out.
    Tmp2 = ComputeNumSignBits(Op.getOperand(3), DemandedElts, Depth+1);
    return std::min(Tmp, Tmp2);
 
  case ISD::SMIN:
  case ISD::SMAX: {
    // If we have a clamp pattern, we know that the number of sign bits will be
    // the minimum of the clamp min/max range.
    bool IsMax = (Opcode == ISD::SMAX);
    ConstantSDNode *CstLow = nullptr, *CstHigh = nullptr;
    if ((CstLow = isConstOrConstSplat(Op.getOperand(1), DemandedElts)))
      if (Op.getOperand(0).getOpcode() == (IsMax ? ISD::SMIN : ISD::SMAX))
        CstHigh =
            isConstOrConstSplat(Op.getOperand(0).getOperand(1), DemandedElts);
    if (CstLow && CstHigh) {
      if (!IsMax)
        std::swap(CstLow, CstHigh);
      if (CstLow->getAPIntValue().sle(CstHigh->getAPIntValue())) {
        Tmp = CstLow->getAPIntValue().getNumSignBits();
        Tmp2 = CstHigh->getAPIntValue().getNumSignBits();
        return std::min(Tmp, Tmp2);
      }
    }
 
    // Fallback - just get the minimum number of sign bits of the operands.
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Tmp == 1)
      return 1;  // Early out.
    Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    return std::min(Tmp, Tmp2);
  }
  case ISD::UMIN:
  case ISD::UMAX:
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Tmp == 1)
      return 1;  // Early out.
    Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    return std::min(Tmp, Tmp2);
  case ISD::SSUBO_CARRY:
  case ISD::USUBO_CARRY:
    // sub_carry(x,x,c) -> 0/-1 (sext carry)
    if (Op.getResNo() == 0 && Op.getOperand(0) == Op.getOperand(1))
      return VTBits;
    [[fallthrough]];
  case ISD::SADDO:
  case ISD::UADDO:
  case ISD::SADDO_CARRY:
  case ISD::UADDO_CARRY:
  case ISD::SSUBO:
  case ISD::USUBO:
  case ISD::SMULO:
  case ISD::UMULO:
    if (Op.getResNo() != 1)
      break;
    // The boolean result conforms to getBooleanContents.  Fall through.
    // If setcc returns 0/-1, all bits are sign bits.
    // We know that we have an integer-based boolean since these operations
    // are only available for integer.
    if (TLI->getBooleanContents(VT.isVector(), false) ==
        TargetLowering::ZeroOrNegativeOneBooleanContent)
      return VTBits;
    break;
  case ISD::SETCC:
  case ISD::SETCCCARRY:
  case ISD::STRICT_FSETCC:
  case ISD::STRICT_FSETCCS: {
    unsigned OpNo = Op->isStrictFPOpcode() ? 1 : 0;
    // If setcc returns 0/-1, all bits are sign bits.
    if (TLI->getBooleanContents(Op.getOperand(OpNo).getValueType()) ==
        TargetLowering::ZeroOrNegativeOneBooleanContent)
      return VTBits;
    break;
  }
  case ISD::GET_ACTIVE_LANE_MASK:
    // Semantically similar to icmp ult.
    if (TLI->getBooleanContents(VT.isVector(), /*isFloat=*/false) ==
        TargetLowering::ZeroOrNegativeOneBooleanContent)
      return VTBits;
    break;
  case ISD::ROTL:
  case ISD::ROTR: {
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    ConstantSDNode *C = isConstOrConstSplat(Op.getOperand(1), DemandedElts);
    FirstAnswer = SignBitsOps::rot(
        Tmp, VTBits, C ? std::optional(C->getAPIntValue()) : std::nullopt,
        Opcode == ISD::ROTR);
    break;
  }
  case ISD::ADD:
  case ISD::ADDC:
    // TODO: Move Operand 1 check before Operand 0 check
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Tmp == 1) return 1; // Early out.
 
    // Special case decrementing a value (ADD X, -1):
    if (ConstantSDNode *CRHS =
            isConstOrConstSplat(Op.getOperand(1), DemandedElts))
      if (CRHS->isAllOnes()) {
        KnownBits Known =
            computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
        // If the input is known to be 0 or 1, the output is 0/-1, which is all
        // sign bits set.
        if ((Known.Zero | 1).isAllOnes())
          return VTBits;
 
        // If we are subtracting one from a positive number, there is no carry
        // out of the result.
        if (Known.isNonNegative())
          return Tmp;
      }
 
    Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (Tmp2 == 1) return 1; // Early out.
 
    // Add can have at most one carry bit.  Thus we know that the output
    // is, at worst, one more bit than the inputs.
    return std::min(Tmp, Tmp2) - 1;
  case ISD::SUB:
    Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (Tmp2 == 1) return 1; // Early out.
 
    // Handle NEG.
    if (ConstantSDNode *CLHS =
            isConstOrConstSplat(Op.getOperand(0), DemandedElts))
      if (CLHS->isZero()) {
        KnownBits Known =
            computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
        // If the input is known to be 0 or 1, the output is 0/-1, which is all
        // sign bits set.
        if ((Known.Zero | 1).isAllOnes())
          return VTBits;
 
        // If the input is known to be positive (the sign bit is known clear),
        // the output of the NEG has the same number of sign bits as the input.
        if (Known.isNonNegative())
          return Tmp2;
 
        // Otherwise, we treat this like a SUB.
      }
 
    // Sub can have at most one carry bit.  Thus we know that the output
    // is, at worst, one more bit than the inputs.
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Tmp == 1) return 1; // Early out.
    return std::min(Tmp, Tmp2) - 1;
  case ISD::MUL: {
    // The output of the Mul can be at most twice the valid bits in the inputs.
    unsigned SignBitsOp0 = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
    if (SignBitsOp0 == 1)
      break;
    unsigned SignBitsOp1 = ComputeNumSignBits(Op.getOperand(1), Depth + 1);
    if (SignBitsOp1 == 1)
      break;
    unsigned OutValidBits =
        (VTBits - SignBitsOp0 + 1) + (VTBits - SignBitsOp1 + 1);
    return OutValidBits > VTBits ? 1 : VTBits - OutValidBits + 1;
  }
  case ISD::AVGCEILS:
  case ISD::AVGFLOORS:
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Tmp == 1)
      return 1; // Early out.
    Tmp2 = ComputeNumSignBits(Op.getOperand(1), DemandedElts, Depth + 1);
    return std::min(Tmp, Tmp2);
  case ISD::SREM:
    // The sign bit is the LHS's sign bit, except when the result of the
    // remainder is zero. The magnitude of the result should be less than or
    // equal to the magnitude of the LHS. Therefore, the result should have
    // at least as many sign bits as the left hand side.
    return ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
  case ISD::TRUNCATE: {
    // Check if the sign bits of source go down as far as the truncated value.
    unsigned NumSrcBits = Op.getOperand(0).getScalarValueSizeInBits();
    unsigned NumSrcSignBits = ComputeNumSignBits(Op.getOperand(0), Depth + 1);
    if (NumSrcSignBits > (NumSrcBits - VTBits))
      return NumSrcSignBits - (NumSrcBits - VTBits);
    break;
  }
  case ISD::EXTRACT_ELEMENT: {
    if (VT.isScalableVector())
      break;
    const int KnownSign = ComputeNumSignBits(Op.getOperand(0), Depth+1);
    const int BitWidth = Op.getValueSizeInBits();
    const int Items = Op.getOperand(0).getValueSizeInBits() / BitWidth;
 
    // Get reverse index (starting from 1), Op1 value indexes elements from
    // little end. Sign starts at big end.
    const int rIndex = Items - 1 - Op.getConstantOperandVal(1);
 
    // If the sign portion ends in our element the subtraction gives correct
    // result. Otherwise it gives either negative or > bitwidth result
    return std::clamp(KnownSign - rIndex * BitWidth, 1, BitWidth);
  }
  case ISD::INSERT_VECTOR_ELT: {
    if (VT.isScalableVector())
      break;
    // If we know the element index, split the demand between the
    // source vector and the inserted element, otherwise assume we need
    // the original demanded vector elements and the value.
    SDValue InVec = Op.getOperand(0);
    SDValue InVal = Op.getOperand(1);
    SDValue EltNo = Op.getOperand(2);
    bool DemandedVal = true;
    APInt DemandedVecElts = DemandedElts;
    auto *CEltNo = dyn_cast<ConstantSDNode>(EltNo);
    if (CEltNo && CEltNo->getAPIntValue().ult(NumElts)) {
      unsigned EltIdx = CEltNo->getZExtValue();
      DemandedVal = !!DemandedElts[EltIdx];
      DemandedVecElts.clearBit(EltIdx);
    }
    Tmp = std::numeric_limits<unsigned>::max();
    if (DemandedVal) {
      // TODO - handle implicit truncation of inserted elements.
      if (InVal.getScalarValueSizeInBits() != VTBits)
        break;
      Tmp2 = ComputeNumSignBits(InVal, Depth + 1);
      Tmp = std::min(Tmp, Tmp2);
    }
    if (!!DemandedVecElts) {
      Tmp2 = ComputeNumSignBits(InVec, DemandedVecElts, Depth + 1);
      Tmp = std::min(Tmp, Tmp2);
    }
    assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
    return Tmp;
  }
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue InVec = Op.getOperand(0);
    SDValue EltNo = Op.getOperand(1);
    EVT VecVT = InVec.getValueType();
    // ComputeNumSignBits not yet implemented for scalable vectors.
    if (VecVT.isScalableVector())
      break;
    const unsigned BitWidth = Op.getValueSizeInBits();
    const unsigned EltBitWidth = Op.getOperand(0).getScalarValueSizeInBits();
    const unsigned NumSrcElts = VecVT.getVectorNumElements();
 
    // If BitWidth > EltBitWidth the value is anyext:ed, and we do not know
    // anything about sign bits. But if the sizes match we can derive knowledge
    // about sign bits from the vector operand.
    if (BitWidth != EltBitWidth)
      break;
 
    // If we know the element index, just demand that vector element, else for
    // an unknown element index, ignore DemandedElts and demand them all.
    APInt DemandedSrcElts = APInt::getAllOnes(NumSrcElts);
    auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
    if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts))
      DemandedSrcElts =
          APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue());
 
    return ComputeNumSignBits(InVec, DemandedSrcElts, Depth + 1);
  }
  case ISD::EXTRACT_SUBVECTOR: {
    // Offset the demanded elts by the subvector index.
    SDValue Src = Op.getOperand(0);
 
    APInt DemandedSrcElts;
    if (Src.getValueType().isScalableVector())
      DemandedSrcElts = APInt(1, 1);
    else {
      uint64_t Idx = Op.getConstantOperandVal(1);
      unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
      DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
    }
    return ComputeNumSignBits(Src, DemandedSrcElts, Depth + 1);
  }
  case ISD::CONCAT_VECTORS: {
    if (VT.isScalableVector())
      break;
    // Determine the minimum number of sign bits across all demanded
    // elts of the input vectors. Early out if the result is already 1.
    Tmp = std::numeric_limits<unsigned>::max();
    EVT SubVectorVT = Op.getOperand(0).getValueType();
    unsigned NumSubVectorElts = SubVectorVT.getVectorNumElements();
    unsigned NumSubVectors = Op.getNumOperands();
    for (unsigned i = 0; (i < NumSubVectors) && (Tmp > 1); ++i) {
      APInt DemandedSub =
          DemandedElts.extractBits(NumSubVectorElts, i * NumSubVectorElts);
      if (!DemandedSub)
        continue;
      Tmp2 = ComputeNumSignBits(Op.getOperand(i), DemandedSub, Depth + 1);
      Tmp = std::min(Tmp, Tmp2);
    }
    assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
    return Tmp;
  }
  case ISD::INSERT_SUBVECTOR: {
    if (VT.isScalableVector())
      break;
    // Demand any elements from the subvector and the remainder from the src its
    // inserted into.
    SDValue Src = Op.getOperand(0);
    SDValue Sub = Op.getOperand(1);
    uint64_t Idx = Op.getConstantOperandVal(2);
    unsigned NumSubElts = Sub.getValueType().getVectorNumElements();
    APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
    APInt DemandedSrcElts = DemandedElts;
    DemandedSrcElts.clearBits(Idx, Idx + NumSubElts);
 
    Tmp = std::numeric_limits<unsigned>::max();
    if (!!DemandedSubElts) {
      Tmp = ComputeNumSignBits(Sub, DemandedSubElts, Depth + 1);
      if (Tmp == 1)
        return 1; // early-out
    }
    if (!!DemandedSrcElts) {
      Tmp2 = ComputeNumSignBits(Src, DemandedSrcElts, Depth + 1);
      Tmp = std::min(Tmp, Tmp2);
    }
    assert(Tmp <= VTBits && "Failed to determine minimum sign bits");
    return Tmp;
  }
  case ISD::LOAD: {
    // If we are looking at the loaded value of the SDNode.
    if (Op.getResNo() != 0)
      break;
 
    LoadSDNode *LD = cast<LoadSDNode>(Op);
    if (const MDNode *Ranges = LD->getRanges()) {
      if (DemandedElts != 1)
        break;
 
      ConstantRange CR = getConstantRangeFromMetadata(*Ranges);
      if (VTBits > CR.getBitWidth()) {
        switch (LD->getExtensionType()) {
        case ISD::SEXTLOAD:
          CR = CR.signExtend(VTBits);
          break;
        case ISD::ZEXTLOAD:
          CR = CR.zeroExtend(VTBits);
          break;
        default:
          break;
        }
      }
 
      if (VTBits != CR.getBitWidth())
        break;
      return std::min(CR.getSignedMin().getNumSignBits(),
                      CR.getSignedMax().getNumSignBits());
    }
 
    unsigned ExtType = LD->getExtensionType();
    switch (ExtType) {
    default:
      break;
    case ISD::SEXTLOAD: // e.g. i16->i32 = '17' bits known.
      Tmp = LD->getMemoryVT().getScalarSizeInBits();
      return VTBits - Tmp + 1;
    case ISD::ZEXTLOAD: // e.g. i16->i32 = '16' bits known.
      Tmp = LD->getMemoryVT().getScalarSizeInBits();
      return VTBits - Tmp;
    case ISD::NON_EXTLOAD:
      if (const Constant *Cst = TLI->getTargetConstantFromLoad(LD)) {
        // We only need to handle vectors - computeKnownBits should handle
        // scalar cases.
        Type *CstTy = Cst->getType();
        if (CstTy->isVectorTy() && !VT.isScalableVector() &&
            (NumElts * VTBits) == CstTy->getPrimitiveSizeInBits() &&
            VTBits == CstTy->getScalarSizeInBits()) {
          Tmp = VTBits;
          for (unsigned i = 0; i != NumElts; ++i) {
            if (!DemandedElts[i])
              continue;
            if (Constant *Elt = Cst->getAggregateElement(i)) {
              if (auto *CInt = dyn_cast<ConstantInt>(Elt)) {
                const APInt &Value = CInt->getValue();
                Tmp = std::min(Tmp, Value.getNumSignBits());
                continue;
              }
              if (auto *CFP = dyn_cast<ConstantFP>(Elt)) {
                APInt Value = CFP->getValueAPF().bitcastToAPInt();
                Tmp = std::min(Tmp, Value.getNumSignBits());
                continue;
              }
            }
            // Unknown type. Conservatively assume no bits match sign bit.
            return 1;
          }
          return Tmp;
        }
      }
      break;
    }
 
    break;
  }
  case ISD::ATOMIC_CMP_SWAP:
  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
  case ISD::ATOMIC_SWAP:
  case ISD::ATOMIC_LOAD_ADD:
  case ISD::ATOMIC_LOAD_SUB:
  case ISD::ATOMIC_LOAD_AND:
  case ISD::ATOMIC_LOAD_CLR:
  case ISD::ATOMIC_LOAD_OR:
  case ISD::ATOMIC_LOAD_XOR:
  case ISD::ATOMIC_LOAD_NAND:
  case ISD::ATOMIC_LOAD_MIN:
  case ISD::ATOMIC_LOAD_MAX:
  case ISD::ATOMIC_LOAD_UMIN:
  case ISD::ATOMIC_LOAD_UMAX:
  case ISD::ATOMIC_LOAD: {
    auto *AT = cast<AtomicSDNode>(Op);
    // If we are looking at the loaded value.
    if (Op.getResNo() == 0) {
      Tmp = AT->getMemoryVT().getScalarSizeInBits();
      if (Tmp == VTBits)
        return 1; // early-out
 
      // For atomic_load, prefer to use the extension type.
      if (Op->getOpcode() == ISD::ATOMIC_LOAD) {
        switch (AT->getExtensionType()) {
        default:
          break;
        case ISD::SEXTLOAD:
          return VTBits - Tmp + 1;
        case ISD::ZEXTLOAD:
          return VTBits - Tmp;
        }
      }
 
      if (TLI->getExtendForAtomicOps() == ISD::SIGN_EXTEND)
        return VTBits - Tmp + 1;
      if (TLI->getExtendForAtomicOps() == ISD::ZERO_EXTEND)
        return VTBits - Tmp;
    }
    break;
  }
  }
 
  // Allow the target to implement this method for its nodes.
  if (Opcode >= ISD::BUILTIN_OP_END ||
      Opcode == ISD::INTRINSIC_WO_CHAIN ||
      Opcode == ISD::INTRINSIC_W_CHAIN ||
      Opcode == ISD::INTRINSIC_VOID) {
    // TODO: This can probably be removed once target code is audited.  This
    // is here purely to reduce patch size and review complexity.
    if (!VT.isScalableVector()) {
      unsigned NumBits =
        TLI->ComputeNumSignBitsForTargetNode(Op, DemandedElts, *this, Depth);
      if (NumBits > 1)
        FirstAnswer = std::max(FirstAnswer, NumBits);
    }
  }
 
  // Finally, if we can prove that the top bits of the result are 0's or 1's,
  // use this information.
  KnownBits Known = computeKnownBits(Op, DemandedElts, Depth);
  return std::max(FirstAnswer, Known.countMinSignBits());
}
 
unsigned SelectionDAG::ComputeMaxSignificantBits(SDValue Op,
                                                 unsigned Depth) const {
  unsigned SignBits = ComputeNumSignBits(Op, Depth);
  return Op.getScalarValueSizeInBits() - SignBits + 1;
}
 
unsigned SelectionDAG::ComputeMaxSignificantBits(SDValue Op,
                                                 const APInt &DemandedElts,
                                                 unsigned Depth) const {
  unsigned SignBits = ComputeNumSignBits(Op, DemandedElts, Depth);
  return Op.getScalarValueSizeInBits() - SignBits + 1;
}
 
bool SelectionDAG::isGuaranteedNotToBeUndefOrPoison(SDValue Op,
                                                    UndefPoisonKind Kind,
                                                    unsigned Depth) const {
  // Early out for FREEZE.
  if (Op.getOpcode() == ISD::FREEZE)
    return true;
 
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return isGuaranteedNotToBeUndefOrPoison(Op, DemandedElts, Kind, Depth);
}
 
bool SelectionDAG::isGuaranteedNotToBeUndefOrPoison(SDValue Op,
                                                    const APInt &DemandedElts,
                                                    UndefPoisonKind Kind,
                                                    unsigned Depth) const {
  unsigned Opcode = Op.getOpcode();
 
  // Early out for FREEZE.
  if (Opcode == ISD::FREEZE)
    return true;
 
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  if (isIntOrFPConstant(Op))
    return true;
 
  switch (Opcode) {
  case ISD::CONDCODE:
  case ISD::VALUETYPE:
  case ISD::FrameIndex:
  case ISD::TargetFrameIndex:
  case ISD::CopyFromReg:
    return true;
 
  case ISD::POISON:
    return !includesPoison(Kind);
 
  case ISD::UNDEF:
    return !includesUndef(Kind);
 
  case ISD::BITCAST: {
    SDValue Src = Op.getOperand(0);
    EVT SrcVT = Src.getValueType();
    EVT DstVT = Op.getValueType();
 
    if (!SrcVT.isVector() || !DstVT.isVector())
      return isGuaranteedNotToBeUndefOrPoison(Src, Kind, Depth + 1);
 
    unsigned SrcEltBits = SrcVT.getScalarSizeInBits();
    unsigned DstEltBits = DstVT.getScalarSizeInBits();
    ElementCount NumSrcElts = SrcVT.getVectorElementCount();
    [[maybe_unused]] ElementCount NumDstElts = DstVT.getVectorElementCount();
 
    if (SrcEltBits == DstEltBits)
      return isGuaranteedNotToBeUndefOrPoison(Src, DemandedElts, Kind,
                                              Depth + 1);
 
    if (SrcEltBits < DstEltBits) {
      if (DstEltBits % SrcEltBits != 0)
        return isGuaranteedNotToBeUndefOrPoison(Src, Kind, Depth + 1);
 
      assert(NumSrcElts == NumDstElts * (DstEltBits / SrcEltBits) &&
             "Unexpected vector bitcast");
      APInt DemandedSrcElts =
          APIntOps::ScaleBitMask(DemandedElts, NumSrcElts.getKnownMinValue());
      return isGuaranteedNotToBeUndefOrPoison(Src, DemandedSrcElts, Kind,
                                              Depth + 1);
    }
 
    if (SrcEltBits % DstEltBits != 0)
      return isGuaranteedNotToBeUndefOrPoison(Src, Kind, Depth + 1);
 
    assert(NumDstElts == NumSrcElts * (SrcEltBits / DstEltBits) &&
           "Unexpected vector bitcast");
    APInt DemandedSrcElts =
        APIntOps::ScaleBitMask(DemandedElts, NumSrcElts.getKnownMinValue());
    return isGuaranteedNotToBeUndefOrPoison(Src, DemandedSrcElts, Kind,
                                            Depth + 1);
  }
 
  case ISD::BUILD_VECTOR:
    // NOTE: BUILD_VECTOR has implicit truncation of wider scalar elements -
    // this shouldn't affect the result.
    for (unsigned i = 0, e = Op.getNumOperands(); i < e; ++i) {
      if (!DemandedElts[i])
        continue;
      if (!isGuaranteedNotToBeUndefOrPoison(Op.getOperand(i), Kind, Depth + 1))
        return false;
    }
    return true;
 
  case ISD::CONCAT_VECTORS: {
    EVT VT = Op.getValueType();
    if (!VT.isFixedLengthVector())
      break;
 
    EVT SubVT = Op.getOperand(0).getValueType();
    unsigned NumSubElts = SubVT.getVectorNumElements();
    for (unsigned I = 0, E = Op.getNumOperands(); I != E; ++I) {
      APInt DemandedSubElts =
          DemandedElts.extractBits(NumSubElts, I * NumSubElts);
      if (!!DemandedSubElts &&
          !isGuaranteedNotToBeUndefOrPoison(Op.getOperand(I), DemandedSubElts,
                                            Kind, Depth + 1))
        return false;
    }
    return true;
  }
 
  case ISD::EXTRACT_SUBVECTOR: {
    SDValue Src = Op.getOperand(0);
    if (Src.getValueType().isScalableVector())
      break;
    uint64_t Idx = Op.getConstantOperandVal(1);
    unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
    APInt DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
    return isGuaranteedNotToBeUndefOrPoison(Src, DemandedSrcElts, Kind,
                                            Depth + 1);
  }
 
  case ISD::INSERT_SUBVECTOR: {
    if (Op.getValueType().isScalableVector())
      break;
    SDValue Src = Op.getOperand(0);
    SDValue Sub = Op.getOperand(1);
    uint64_t Idx = Op.getConstantOperandVal(2);
    unsigned NumSubElts = Sub.getValueType().getVectorNumElements();
    APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
    APInt DemandedSrcElts = DemandedElts;
    DemandedSrcElts.clearBits(Idx, Idx + NumSubElts);
 
    if (!!DemandedSubElts && !isGuaranteedNotToBeUndefOrPoison(
                                 Sub, DemandedSubElts, Kind, Depth + 1))
      return false;
    if (!!DemandedSrcElts && !isGuaranteedNotToBeUndefOrPoison(
                                 Src, DemandedSrcElts, Kind, Depth + 1))
      return false;
    return true;
  }
 
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue Src = Op.getOperand(0);
    auto *IndexC = dyn_cast<ConstantSDNode>(Op.getOperand(1));
    EVT SrcVT = Src.getValueType();
    if (SrcVT.isFixedLengthVector() && IndexC &&
        IndexC->getAPIntValue().ult(SrcVT.getVectorNumElements())) {
      APInt DemandedSrcElts = APInt::getOneBitSet(SrcVT.getVectorNumElements(),
                                                  IndexC->getZExtValue());
      return isGuaranteedNotToBeUndefOrPoison(Src, DemandedSrcElts, Kind,
                                              Depth + 1);
    }
    break;
  }
 
  case ISD::INSERT_VECTOR_ELT: {
    SDValue InVec = Op.getOperand(0);
    SDValue InVal = Op.getOperand(1);
    SDValue EltNo = Op.getOperand(2);
    EVT VT = InVec.getValueType();
    auto *IndexC = dyn_cast<ConstantSDNode>(EltNo);
    if (IndexC && VT.isFixedLengthVector() &&
        IndexC->getAPIntValue().ult(VT.getVectorNumElements())) {
      if (DemandedElts[IndexC->getZExtValue()] &&
          !isGuaranteedNotToBeUndefOrPoison(InVal, Kind, Depth + 1))
        return false;
      APInt InVecDemandedElts = DemandedElts;
      InVecDemandedElts.clearBit(IndexC->getZExtValue());
      if (!!InVecDemandedElts &&
          !isGuaranteedNotToBeUndefOrPoison(
              peekThroughInsertVectorElt(InVec, InVecDemandedElts),
              InVecDemandedElts, Kind, Depth + 1))
        return false;
      return true;
    }
    break;
  }
 
  case ISD::SCALAR_TO_VECTOR:
    // Check upper (known undef) elements.
    if (DemandedElts.ugt(1) && includesUndef(Kind))
      return false;
    // Check element zero.
    if (DemandedElts[0] &&
        !isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), Kind, Depth + 1))
      return false;
    return true;
 
  case ISD::SPLAT_VECTOR:
    return isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), Kind, Depth + 1);
 
  case ISD::SELECT: {
    return !canCreateUndefOrPoison(Op, DemandedElts, Kind,
                                   /*ConsiderFlags*/ true, Depth) &&
           isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), Kind,
                                            Depth + 1) &&
           isGuaranteedNotToBeUndefOrPoison(Op.getOperand(1), DemandedElts,
                                            Kind, Depth + 1) &&
           isGuaranteedNotToBeUndefOrPoison(Op.getOperand(2), DemandedElts,
                                            Kind, Depth + 1);
  }
 
  case ISD::VECTOR_SHUFFLE: {
    APInt DemandedLHS, DemandedRHS;
    auto *SVN = cast<ShuffleVectorSDNode>(Op);
    if (!getShuffleDemandedElts(DemandedElts.getBitWidth(), SVN->getMask(),
                                DemandedElts, DemandedLHS, DemandedRHS,
                                /*AllowUndefElts=*/false))
      return false;
    if (!DemandedLHS.isZero() &&
        !isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), DemandedLHS, Kind,
                                          Depth + 1))
      return false;
    if (!DemandedRHS.isZero() &&
        !isGuaranteedNotToBeUndefOrPoison(Op.getOperand(1), DemandedRHS, Kind,
                                          Depth + 1))
      return false;
    return true;
  }
 
  case ISD::SHL:
  case ISD::SRL:
  case ISD::SRA:
    // Shift amount operand is checked by canCreateUndefOrPoison. So it is
    // enough to check operand 0 if Op can't create undef/poison.
    return !canCreateUndefOrPoison(Op, DemandedElts, Kind,
                                   /*ConsiderFlags*/ true, Depth) &&
           isGuaranteedNotToBeUndefOrPoison(Op.getOperand(0), DemandedElts,
                                            Kind, Depth + 1);
 
  case ISD::BSWAP:
  case ISD::CTPOP:
  case ISD::BITREVERSE:
  case ISD::AND:
  case ISD::OR:
  case ISD::XOR:
  case ISD::ADD:
  case ISD::SUB:
  case ISD::MUL:
  case ISD::SADDSAT:
  case ISD::UADDSAT:
  case ISD::SSUBSAT:
  case ISD::USUBSAT:
  case ISD::SSHLSAT:
  case ISD::USHLSAT:
  case ISD::SMIN:
  case ISD::SMAX:
  case ISD::UMIN:
  case ISD::UMAX:
  case ISD::ZERO_EXTEND:
  case ISD::SIGN_EXTEND:
  case ISD::ANY_EXTEND:
  case ISD::TRUNCATE:
  case ISD::VSELECT: {
    // If Op can't create undef/poison and none of its operands are undef/poison
    // then Op is never undef/poison. A difference from the more common check
    // below, outside the switch, is that we handle elementwise operations for
    // which the DemandedElts mask is valid for all operands here.
    return !canCreateUndefOrPoison(Op, DemandedElts, Kind,
                                   /*ConsiderFlags*/ true, Depth) &&
           all_of(Op->ops(), [&](SDValue V) {
             return isGuaranteedNotToBeUndefOrPoison(V, DemandedElts, Kind,
                                                     Depth + 1);
           });
  }
 
    // TODO: Search for noundef attributes from library functions.
 
    // TODO: Pointers dereferenced by ISD::LOAD/STORE ops are noundef.
 
  default:
    // Allow the target to implement this method for its nodes.
    if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
        Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID)
      return TLI->isGuaranteedNotToBeUndefOrPoisonForTargetNode(
          Op, DemandedElts, *this, Kind, Depth);
    break;
  }
 
  // If Op can't create undef/poison and none of its operands are undef/poison
  // then Op is never undef/poison.
  // NOTE: TargetNodes can handle this in themselves in
  // isGuaranteedNotToBeUndefOrPoisonForTargetNode or let
  // TargetLowering::isGuaranteedNotToBeUndefOrPoisonForTargetNode handle it.
  return !canCreateUndefOrPoison(Op, Kind, /*ConsiderFlags*/ true, Depth) &&
         all_of(Op->ops(), [&](SDValue V) {
           return isGuaranteedNotToBeUndefOrPoison(V, Kind, Depth + 1);
         });
}
 
bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, UndefPoisonKind Kind,
                                          bool ConsiderFlags,
                                          unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return canCreateUndefOrPoison(Op, DemandedElts, Kind, ConsiderFlags, Depth);
}
 
bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
                                          UndefPoisonKind Kind,
                                          bool ConsiderFlags,
                                          unsigned Depth) const {
  if (ConsiderFlags && includesPoison(Kind) && Op->hasPoisonGeneratingFlags())
    return true;
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  case ISD::AssertSext:
  case ISD::AssertZext:
  case ISD::AssertAlign:
  case ISD::AssertNoFPClass:
    // Assertion nodes can create poison if the assertion fails.
    return includesPoison(Kind);
 
  case ISD::FREEZE:
  case ISD::CONCAT_VECTORS:
  case ISD::INSERT_SUBVECTOR:
  case ISD::EXTRACT_SUBVECTOR:
  case ISD::SADDSAT:
  case ISD::UADDSAT:
  case ISD::SSUBSAT:
  case ISD::USUBSAT:
  case ISD::MULHU:
  case ISD::MULHS:
  case ISD::AVGFLOORS:
  case ISD::AVGFLOORU:
  case ISD::AVGCEILS:
  case ISD::AVGCEILU:
  case ISD::ABDU:
  case ISD::ABDS:
  case ISD::SMIN:
  case ISD::SMAX:
  case ISD::SCMP:
  case ISD::UMIN:
  case ISD::UMAX:
  case ISD::UCMP:
  case ISD::AND:
  case ISD::XOR:
  case ISD::ROTL:
  case ISD::ROTR:
  case ISD::FSHL:
  case ISD::FSHR:
  case ISD::BSWAP:
  case ISD::CTTZ:
  case ISD::CTLZ:
  case ISD::CTLS:
  case ISD::CTPOP:
  case ISD::BITREVERSE:
  case ISD::PARITY:
  case ISD::SIGN_EXTEND:
  case ISD::TRUNCATE:
  case ISD::SIGN_EXTEND_INREG:
  case ISD::SIGN_EXTEND_VECTOR_INREG:
  case ISD::ZERO_EXTEND_VECTOR_INREG:
  case ISD::BITCAST:
  case ISD::BUILD_VECTOR:
  case ISD::BUILD_PAIR:
  case ISD::SPLAT_VECTOR:
  case ISD::FABS:
  case ISD::FCEIL:
  case ISD::FFLOOR:
  case ISD::FTRUNC:
  case ISD::FRINT:
  case ISD::FNEARBYINT:
  case ISD::FROUND:
  case ISD::FROUNDEVEN:
    return false;
 
  case ISD::ABS:
    // ISD::ABS defines abs(INT_MIN) -> INT_MIN and never generates poison.
    // Different to Intrinsic::abs.
    return false;
  case ISD::ABS_MIN_POISON:
    // ABS_MIN_POISON may produce poison if the input is INT_MIN.
    return ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1) <= 1;
 
  case ISD::ADDC:
  case ISD::SUBC:
  case ISD::ADDE:
  case ISD::SUBE:
  case ISD::SADDO:
  case ISD::SSUBO:
  case ISD::SMULO:
  case ISD::SADDO_CARRY:
  case ISD::SSUBO_CARRY:
  case ISD::UADDO:
  case ISD::USUBO:
  case ISD::UMULO:
  case ISD::UADDO_CARRY:
  case ISD::USUBO_CARRY:
    // No poison on result or overflow flags.
    return false;
 
  case ISD::SELECT_CC:
  case ISD::SETCC: {
    // Integer setcc cannot create undef or poison.
    if (Op.getOperand(0).getValueType().isInteger())
      return false;
 
    // FP compares are more complicated. They can create poison for nan/infinity
    // based on options and flags. The options and flags also cause special
    // nonan condition codes to be used. Those condition codes may be preserved
    // even if the nonan flag is dropped somewhere.
    unsigned CCOp = Opcode == ISD::SETCC ? 2 : 4;
    ISD::CondCode CCCode = cast<CondCodeSDNode>(Op.getOperand(CCOp))->get();
    return (unsigned)CCCode & 0x10U;
  }
 
  case ISD::OR:
  case ISD::ZERO_EXTEND:
  case ISD::SELECT:
  case ISD::VSELECT:
  case ISD::ADD:
  case ISD::SUB:
  case ISD::MUL:
  case ISD::FNEG:
  case ISD::FADD:
  case ISD::FSUB:
  case ISD::FMUL:
  case ISD::FDIV:
  case ISD::FREM:
  case ISD::FCOPYSIGN:
  case ISD::FMA:
  case ISD::FMAD:
  case ISD::FMULADD:
  case ISD::FP_EXTEND:
  case ISD::FMINNUM:
  case ISD::FMAXNUM:
  case ISD::FMINNUM_IEEE:
  case ISD::FMAXNUM_IEEE:
  case ISD::FMINIMUM:
  case ISD::FMAXIMUM:
  case ISD::FMINIMUMNUM:
  case ISD::FMAXIMUMNUM:
  case ISD::FP_TO_SINT_SAT:
  case ISD::FP_TO_UINT_SAT:
  case ISD::TRUNCATE_SSAT_S:
  case ISD::TRUNCATE_SSAT_U:
  case ISD::TRUNCATE_USAT_U:
    // No poison except from flags (which is handled above)
    return false;
 
  case ISD::SHL:
  case ISD::SRL:
  case ISD::SRA:
    // If the max shift amount isn't in range, then the shift can
    // create poison.
    return includesPoison(Kind) &&
           !getValidMaximumShiftAmount(Op, DemandedElts, Depth + 1);
 
  case ISD::CTTZ_ZERO_POISON:
  case ISD::CTLZ_ZERO_POISON:
    // If the amount is zero then the result will be poison.
    // TODO: Add isKnownNeverZero DemandedElts handling.
    return includesPoison(Kind) &&
           !isKnownNeverZero(Op.getOperand(0), Depth + 1);
 
  case ISD::SCALAR_TO_VECTOR:
    // Check if we demand any upper (undef) elements.
    return includesUndef(Kind) && DemandedElts.ugt(1);
 
  case ISD::INSERT_VECTOR_ELT:
  case ISD::EXTRACT_VECTOR_ELT: {
    // Ensure that the element index is in bounds.
    if (includesPoison(Kind)) {
      EVT VecVT = Op.getOperand(0).getValueType();
      SDValue Idx = Op.getOperand(Opcode == ISD::INSERT_VECTOR_ELT ? 2 : 1);
      KnownBits KnownIdx = computeKnownBits(Idx, Depth + 1);
      return KnownIdx.getMaxValue().uge(VecVT.getVectorMinNumElements());
    }
    return false;
  }
 
  case ISD::VECTOR_SHUFFLE: {
    // Check for any demanded shuffle element that is undef.
    auto *SVN = cast<ShuffleVectorSDNode>(Op);
    for (auto [Idx, Elt] : enumerate(SVN->getMask()))
      if (Elt < 0 && DemandedElts[Idx])
        return true;
    return false;
  }
 
  case ISD::VECTOR_COMPRESS:
    return false;
 
  default:
    // Allow the target to implement this method for its nodes.
    if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
        Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID)
      return TLI->canCreateUndefOrPoisonForTargetNode(
          Op, DemandedElts, *this, Kind, ConsiderFlags, Depth);
    break;
  }
 
  // Be conservative and return true.
  return true;
}
 
bool SelectionDAG::isADDLike(SDValue Op, bool NoWrap) const {
  unsigned Opcode = Op.getOpcode();
  if (Opcode == ISD::OR)
    return Op->getFlags().hasDisjoint() ||
           haveNoCommonBitsSet(Op.getOperand(0), Op.getOperand(1));
  if (Opcode == ISD::XOR)
    return !NoWrap && isMinSignedConstant(Op.getOperand(1));
  return false;
}
 
bool SelectionDAG::isBaseWithConstantOffset(SDValue Op) const {
  return Op.getNumOperands() == 2 && isa<ConstantSDNode>(Op.getOperand(1)) &&
         (Op.isAnyAdd() || isADDLike(Op));
}
 
KnownFPClass SelectionDAG::computeKnownFPClass(SDValue Op,
                                               FPClassTest InterestedClasses,
                                               unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return computeKnownFPClass(Op, DemandedElts, InterestedClasses, Depth);
}
 
KnownFPClass SelectionDAG::computeKnownFPClass(SDValue Op,
                                               const APInt &DemandedElts,
                                               FPClassTest InterestedClasses,
                                               unsigned Depth) const {
  KnownFPClass Known;
 
  if (const auto *CFP = dyn_cast<ConstantFPSDNode>(Op))
    return KnownFPClass(CFP->getValueAPF());
 
  if (Depth >= MaxRecursionDepth)
    return Known;
 
  if (Op.getOpcode() == ISD::UNDEF)
    return Known;
 
  EVT VT = Op.getValueType();
  assert(VT.isFloatingPoint() && "Computing KnownFPClass on non-FP op!");
  assert((!VT.isFixedLengthVector() ||
          DemandedElts.getBitWidth() == VT.getVectorNumElements()) &&
         "Unexpected vector size");
 
  if (!DemandedElts)
    return Known;
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  case ISD::POISON: {
    Known.KnownFPClasses = fcNone;
    Known.SignBit = false;
    break;
  }
  case ISD::FNEG: {
    Known = computeKnownFPClass(Op.getOperand(0), DemandedElts,
                                InterestedClasses, Depth + 1);
    Known.fneg();
    break;
  }
  case ISD::BUILD_VECTOR: {
    assert(!VT.isScalableVector());
    bool First = true;
    for (unsigned I = 0, E = Op.getNumOperands(); I != E; ++I) {
      if (!DemandedElts[I])
        continue;
 
      if (First) {
        Known =
            computeKnownFPClass(Op.getOperand(I), InterestedClasses, Depth + 1);
        First = false;
      } else {
        Known |=
            computeKnownFPClass(Op.getOperand(I), InterestedClasses, Depth + 1);
      }
 
      if (Known.isUnknown())
        break;
    }
    break;
  }
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue Src = Op.getOperand(0);
    auto *CIdx = dyn_cast<ConstantSDNode>(Op.getOperand(1));
    EVT SrcVT = Src.getValueType();
    if (SrcVT.isFixedLengthVector() && CIdx) {
      if (CIdx->getAPIntValue().ult(SrcVT.getVectorNumElements())) {
        APInt DemandedSrcElts = APInt::getOneBitSet(
            SrcVT.getVectorNumElements(), CIdx->getZExtValue());
        Known = computeKnownFPClass(Src, DemandedSrcElts, InterestedClasses,
                                    Depth + 1);
      } else {
        // Out of bounds index is poison.
        Known.KnownFPClasses = fcNone;
      }
    } else {
      Known = computeKnownFPClass(Src, InterestedClasses, Depth + 1);
    }
    break;
  }
  case ISD::SPLAT_VECTOR: {
    Known = computeKnownFPClass(Op.getOperand(0), InterestedClasses, Depth + 1);
    break;
  }
  case ISD::BITCAST: {
    // FIXME: It should not be necessary to check for an elementwise bitcast.
    // If a bitcast is not elementwise between vector / scalar types,
    // computeKnownBits already splices the known bits of the source elements
    // appropriately so as to line up with the bits of the result's demanded
    // elements.
    EVT SrcVT = Op.getOperand(0).getValueType();
    if (VT.isScalableVector() || SrcVT.isScalableVector())
      break;
    unsigned VTNumElts = VT.isVector() ? VT.getVectorNumElements() : 1;
    unsigned SrcVTNumElts = SrcVT.isVector() ? SrcVT.getVectorNumElements() : 1;
    if (VTNumElts != SrcVTNumElts)
      break;
 
    KnownBits Bits = computeKnownBits(Op, DemandedElts, Depth + 1);
    Known = KnownFPClass::bitcast(VT.getFltSemantics(), Bits);
    break;
  }
  case ISD::FABS: {
    Known = computeKnownFPClass(Op.getOperand(0), DemandedElts,
                                InterestedClasses, Depth + 1);
    Known.fabs();
    break;
  }
  case ISD::FCOPYSIGN: {
    Known = computeKnownFPClass(Op.getOperand(0), DemandedElts,
                                InterestedClasses, Depth + 1);
    KnownFPClass KnownSign = computeKnownFPClass(Op.getOperand(1), DemandedElts,
                                                 InterestedClasses, Depth + 1);
    Known.copysign(KnownSign);
    break;
  }
  case ISD::AssertNoFPClass: {
    Known = computeKnownFPClass(Op.getOperand(0), DemandedElts,
                                InterestedClasses, Depth + 1);
    FPClassTest AssertedClasses =
        static_cast<FPClassTest>(Op->getConstantOperandVal(1));
    Known.KnownFPClasses &= ~AssertedClasses;
    break;
  }
  case ISD::EXTRACT_SUBVECTOR: {
    SDValue Src = Op.getOperand(0);
    EVT SrcVT = Src.getValueType();
    if (SrcVT.isFixedLengthVector()) {
      unsigned Idx = Op.getConstantOperandVal(1);
      unsigned NumSrcElts = SrcVT.getVectorNumElements();
 
      APInt DemandedSrcElts = DemandedElts.zextOrTrunc(NumSrcElts).shl(Idx);
      Known = computeKnownFPClass(Src, DemandedSrcElts, InterestedClasses,
                                  Depth + 1);
    } else {
      Known = computeKnownFPClass(Src, InterestedClasses, Depth + 1);
    }
    break;
  }
  case ISD::INSERT_SUBVECTOR: {
    SDValue BaseVector = Op.getOperand(0);
    SDValue SubVector = Op.getOperand(1);
    EVT BaseVT = BaseVector.getValueType();
    if (BaseVT.isFixedLengthVector()) {
      unsigned Idx = Op.getConstantOperandVal(2);
      unsigned NumBaseElts = BaseVT.getVectorNumElements();
      unsigned NumSubElts = SubVector.getValueType().getVectorNumElements();
 
      APInt DemandedMask =
          APInt::getBitsSet(NumBaseElts, Idx, Idx + NumSubElts);
      APInt DemandedSrcElts = DemandedElts & ~DemandedMask;
      APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
 
      if (!DemandedSrcElts.isZero())
        Known = computeKnownFPClass(BaseVector, DemandedSrcElts,
                                    InterestedClasses, Depth + 1);
      if (!DemandedSubElts.isZero()) {
        KnownFPClass SubKnown = computeKnownFPClass(
            SubVector, DemandedSubElts, InterestedClasses, Depth + 1);
        Known = DemandedSrcElts.isZero() ? SubKnown : (Known | SubKnown);
      }
    } else {
      Known = computeKnownFPClass(SubVector, InterestedClasses, Depth + 1);
      if (!Known.isUnknown())
        Known |= computeKnownFPClass(BaseVector, InterestedClasses, Depth + 1);
    }
    break;
  }
  case ISD::SELECT:
  case ISD::VSELECT: {
    // TODO: Add adjustKnownFPClassForSelectArm clamp recognition as in
    // IR-level ValueTracking.
    KnownFPClass KnownFalseClass = computeKnownFPClass(
        Op.getOperand(2), DemandedElts, InterestedClasses, Depth + 1);
    if (KnownFalseClass.isUnknown())
      break;
    KnownFPClass KnownTrueClass = computeKnownFPClass(
        Op.getOperand(1), DemandedElts, InterestedClasses, Depth + 1);
    Known = KnownTrueClass.intersectWith(KnownFalseClass);
    break;
  }
  default:
    if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
        Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID) {
      TLI->computeKnownFPClassForTargetNode(Op, Known, DemandedElts, *this,
                                            Depth);
    }
    break;
  }
 
  return Known;
}
 
bool SelectionDAG::isKnownNeverNaN(SDValue Op, bool SNaN,
                                   unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return isKnownNeverNaN(Op, DemandedElts, SNaN, Depth);
}
 
bool SelectionDAG::isKnownNeverNaN(SDValue Op, const APInt &DemandedElts,
                                   bool SNaN, unsigned Depth) const {
  assert(!DemandedElts.isZero() && "No demanded elements");
 
  // If we're told that NaNs won't happen, assume they won't.
  if (Op->getFlags().hasNoNaNs())
    return true;
 
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  unsigned Opcode = Op.getOpcode();
  switch (Opcode) {
  case ISD::FADD:
  case ISD::FSUB:
  case ISD::FMUL:
  case ISD::FDIV:
  case ISD::FREM:
  case ISD::FSIN:
  case ISD::FCOS:
  case ISD::FTAN:
  case ISD::FASIN:
  case ISD::FACOS:
  case ISD::FATAN:
  case ISD::FATAN2:
  case ISD::FSINH:
  case ISD::FCOSH:
  case ISD::FTANH:
  case ISD::FMA:
  case ISD::FMULADD:
  case ISD::FMAD: {
    if (SNaN)
      return true;
    // TODO: Need isKnownNeverInfinity
    return false;
  }
  case ISD::FCANONICALIZE:
  case ISD::FEXP:
  case ISD::FEXP2:
  case ISD::FEXP10:
  case ISD::FTRUNC:
  case ISD::FFLOOR:
  case ISD::FCEIL:
  case ISD::FROUND:
  case ISD::FROUNDEVEN:
  case ISD::LROUND:
  case ISD::LLROUND:
  case ISD::FRINT:
  case ISD::LRINT:
  case ISD::LLRINT:
  case ISD::FNEARBYINT:
  case ISD::FLDEXP: {
    if (SNaN)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1);
  }
  case ISD::FABS:
  case ISD::FNEG:
  case ISD::FCOPYSIGN: {
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1);
  }
  case ISD::SELECT:
    return isKnownNeverNaN(Op.getOperand(1), DemandedElts, SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(2), DemandedElts, SNaN, Depth + 1);
  case ISD::FP_EXTEND:
  case ISD::FP_ROUND: {
    if (SNaN)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1);
  }
  case ISD::SINT_TO_FP:
  case ISD::UINT_TO_FP:
    return true;
  case ISD::FSQRT: // Need is known positive
  case ISD::FLOG:
  case ISD::FLOG2:
  case ISD::FLOG10:
  case ISD::FPOWI:
  case ISD::FPOW: {
    if (SNaN)
      return true;
    // TODO: Refine on operand
    return false;
  }
  case ISD::FMINNUM:
  case ISD::FMAXNUM:
  case ISD::FMINIMUMNUM:
  case ISD::FMAXIMUMNUM: {
    // Only one needs to be known not-nan, since it will be returned if the
    // other ends up being one.
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1) ||
           isKnownNeverNaN(Op.getOperand(1), DemandedElts, SNaN, Depth + 1);
  }
  case ISD::FMINNUM_IEEE:
  case ISD::FMAXNUM_IEEE: {
    if (SNaN)
      return true;
    // This can return a NaN if either operand is an sNaN, or if both operands
    // are NaN.
    return (isKnownNeverNaN(Op.getOperand(0), DemandedElts, false, Depth + 1) &&
            isKnownNeverSNaN(Op.getOperand(1), DemandedElts, Depth + 1)) ||
           (isKnownNeverNaN(Op.getOperand(1), DemandedElts, false, Depth + 1) &&
            isKnownNeverSNaN(Op.getOperand(0), DemandedElts, Depth + 1));
  }
  case ISD::FMINIMUM:
  case ISD::FMAXIMUM: {
    // TODO: Does this quiet or return the origina NaN as-is?
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(1), DemandedElts, SNaN, Depth + 1);
  }
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue Src = Op.getOperand(0);
    auto *Idx = dyn_cast<ConstantSDNode>(Op.getOperand(1));
    EVT SrcVT = Src.getValueType();
    if (SrcVT.isFixedLengthVector() && Idx &&
        Idx->getAPIntValue().ult(SrcVT.getVectorNumElements())) {
      APInt DemandedSrcElts = APInt::getOneBitSet(SrcVT.getVectorNumElements(),
                                                  Idx->getZExtValue());
      return isKnownNeverNaN(Src, DemandedSrcElts, SNaN, Depth + 1);
    }
    return isKnownNeverNaN(Src, SNaN, Depth + 1);
  }
  case ISD::EXTRACT_SUBVECTOR: {
    SDValue Src = Op.getOperand(0);
    if (Src.getValueType().isFixedLengthVector()) {
      unsigned Idx = Op.getConstantOperandVal(1);
      unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
      APInt DemandedSrcElts = DemandedElts.zext(NumSrcElts).shl(Idx);
      return isKnownNeverNaN(Src, DemandedSrcElts, SNaN, Depth + 1);
    }
    return isKnownNeverNaN(Src, SNaN, Depth + 1);
  }
  case ISD::INSERT_SUBVECTOR: {
    SDValue BaseVector = Op.getOperand(0);
    SDValue SubVector = Op.getOperand(1);
    EVT BaseVectorVT = BaseVector.getValueType();
    if (BaseVectorVT.isFixedLengthVector()) {
      unsigned Idx = Op.getConstantOperandVal(2);
      unsigned NumBaseElts = BaseVectorVT.getVectorNumElements();
      unsigned NumSubElts = SubVector.getValueType().getVectorNumElements();
 
      // Clear/Extract the bits at the position where the subvector will be
      // inserted.
      APInt DemandedMask =
          APInt::getBitsSet(NumBaseElts, Idx, Idx + NumSubElts);
      APInt DemandedSrcElts = DemandedElts & ~DemandedMask;
      APInt DemandedSubElts = DemandedElts.extractBits(NumSubElts, Idx);
 
      bool NeverNaN = true;
      if (!DemandedSrcElts.isZero())
        NeverNaN &=
            isKnownNeverNaN(BaseVector, DemandedSrcElts, SNaN, Depth + 1);
      if (NeverNaN && !DemandedSubElts.isZero())
        NeverNaN &=
            isKnownNeverNaN(SubVector, DemandedSubElts, SNaN, Depth + 1);
      return NeverNaN;
    }
    return isKnownNeverNaN(BaseVector, SNaN, Depth + 1) &&
           isKnownNeverNaN(SubVector, SNaN, Depth + 1);
  }
  case ISD::BUILD_VECTOR: {
    unsigned NumElts = Op.getNumOperands();
    for (unsigned I = 0; I != NumElts; ++I)
      if (DemandedElts[I] &&
          !isKnownNeverNaN(Op.getOperand(I), SNaN, Depth + 1))
        return false;
    return true;
  }
  case ISD::SPLAT_VECTOR:
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
  case ISD::AssertNoFPClass: {
    FPClassTest NoFPClass =
        static_cast<FPClassTest>(Op.getConstantOperandVal(1));
    if ((NoFPClass & fcNan) == fcNan)
      return true;
    if (SNaN && (NoFPClass & fcSNan) == fcSNan)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), DemandedElts, SNaN, Depth + 1);
  }
  default:
    if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::INTRINSIC_WO_CHAIN ||
        Opcode == ISD::INTRINSIC_W_CHAIN || Opcode == ISD::INTRINSIC_VOID) {
      return TLI->isKnownNeverNaNForTargetNode(Op, DemandedElts, *this, SNaN,
                                               Depth);
    }
    break;
  }
 
  FPClassTest NanMask = SNaN ? fcSNan : fcNan;
  KnownFPClass Known = computeKnownFPClass(Op, DemandedElts, NanMask, Depth);
  return Known.isKnownNever(NanMask);
}
 
bool SelectionDAG::isKnownNeverLogicalZero(SDValue Op, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return isKnownNeverLogicalZero(Op, DemandedElts, Depth);
}
 
bool SelectionDAG::isKnownNeverLogicalZero(SDValue Op,
                                           const APInt &DemandedElts,
                                           unsigned Depth) const {
  assert(!DemandedElts.isZero() && "No demanded elements");
  EVT VT = Op.getValueType();
  KnownFPClass Known =
      computeKnownFPClass(Op, DemandedElts, fcZero | fcSubnormal, Depth);
  return Known.isKnownNeverLogicalZero(getDenormalMode(VT));
}
 
bool SelectionDAG::isKnownNeverZero(SDValue Op, unsigned Depth) const {
  APInt DemandedElts = getDemandAllEltsMask(Op);
  return isKnownNeverZero(Op, DemandedElts, Depth);
}
 
bool SelectionDAG::isKnownNeverZero(SDValue Op, const APInt &DemandedElts,
                                    unsigned Depth) const {
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  EVT OpVT = Op.getValueType();
  unsigned BitWidth = OpVT.getScalarSizeInBits();
 
  assert(!Op.getValueType().isFloatingPoint() &&
         "Floating point types unsupported - use isKnownNeverLogicalZero");
 
  // If the value is a constant, we can obviously see if it is a zero or not.
  auto IsNeverZero = [BitWidth](const ConstantSDNode *C) {
    APInt V = C->getAPIntValue().zextOrTrunc(BitWidth);
    return !V.isZero();
  };
 
  if (ISD::matchUnaryPredicate(Op, DemandedElts, IsNeverZero,
                               /*AllowUndefs=*/false, /*AllowTruncation=*/true))
    return true;
 
  // TODO: Recognize more cases here. Most of the cases are also incomplete to
  // some degree.
  switch (Op.getOpcode()) {
  default:
    break;
 
  case ISD::EXTRACT_VECTOR_ELT: {
    SDValue InVec = Op.getOperand(0);
    SDValue EltNo = Op.getOperand(1);
    EVT VecVT = InVec.getValueType();
 
    // Skip scalable vectors or implicit extensions.
    if (VecVT.isScalableVector() ||
        OpVT.getScalarSizeInBits() != VecVT.getScalarSizeInBits())
      break;
 
    // If we know the element index, just demand that vector element, else for
    // an unknown element index, ignore DemandedElts and demand them all.
    const unsigned NumSrcElts = VecVT.getVectorNumElements();
    APInt DemandedSrcElts = APInt::getAllOnes(NumSrcElts);
    auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo);
    if (ConstEltNo && ConstEltNo->getAPIntValue().ult(NumSrcElts))
      DemandedSrcElts =
          APInt::getOneBitSet(NumSrcElts, ConstEltNo->getZExtValue());
 
    return isKnownNeverZero(InVec, DemandedSrcElts, Depth + 1);
  }
 
  case ISD::OR:
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) ||
           isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
 
  case ISD::VSELECT:
  case ISD::SELECT:
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) &&
           isKnownNeverZero(Op.getOperand(2), DemandedElts, Depth + 1);
 
  case ISD::SHL: {
    if (Op->getFlags().hasNoSignedWrap() || Op->getFlags().hasNoUnsignedWrap())
      return isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
    KnownBits ValKnown =
        computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    // 1 << X is never zero.
    if (ValKnown.One[0])
      return true;
    // If max shift cnt of known ones is non-zero, result is non-zero.
    APInt MaxCnt = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1)
                       .getMaxValue();
    if (MaxCnt.ult(ValKnown.getBitWidth()) &&
        !ValKnown.One.shl(MaxCnt).isZero())
      return true;
    break;
  }
 
  case ISD::VECTOR_SHUFFLE: {
    if (Op.getValueType().isScalableVector())
      return false;
 
    unsigned NumElts = DemandedElts.getBitWidth();
 
    // All demanded elements from LHS and RHS must be known non-zero.
    // Demanded elements with undef shuffle mask elements are unknown.
 
    APInt DemandedLHS, DemandedRHS;
    auto *SVN = cast<ShuffleVectorSDNode>(Op);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    if (!getShuffleDemandedElts(NumElts, SVN->getMask(), DemandedElts,
                                DemandedLHS, DemandedRHS))
      return false;
 
    return (!DemandedLHS ||
            isKnownNeverZero(Op.getOperand(0), DemandedLHS, Depth + 1)) &&
           (!DemandedRHS ||
            isKnownNeverZero(Op.getOperand(1), DemandedRHS, Depth + 1));
  }
 
  case ISD::UADDSAT:
  case ISD::UMAX:
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) ||
           isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
 
  case ISD::UMIN:
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) &&
           isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
 
    // For smin/smax: If either operand is known negative/positive
    // respectively we don't need the other to be known at all.
  case ISD::SMAX: {
    KnownBits Op1 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (Op1.isStrictlyPositive())
      return true;
 
    KnownBits Op0 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Op0.isStrictlyPositive())
      return true;
 
    if (Op1.isNonZero() && Op0.isNonZero())
      return true;
 
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) &&
           isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
  }
  case ISD::SMIN: {
    KnownBits Op1 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    if (Op1.isNegative())
      return true;
 
    KnownBits Op0 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (Op0.isNegative())
      return true;
 
    if (Op1.isNonZero() && Op0.isNonZero())
      return true;
 
    return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) &&
           isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
  }
 
  case ISD::ROTL:
  case ISD::ROTR:
  case ISD::BITREVERSE:
  case ISD::BSWAP:
  case ISD::CTPOP:
  case ISD::ABS:
  case ISD::ABS_MIN_POISON:
    return isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
 
  case ISD::SRA:
  case ISD::SRL: {
    if (Op->getFlags().hasExact())
      return isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
    KnownBits ValKnown =
        computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    if (ValKnown.isNegative())
      return true;
    // If max shift cnt of known ones is non-zero, result is non-zero.
    APInt MaxCnt = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1)
                       .getMaxValue();
    if (MaxCnt.ult(ValKnown.getBitWidth()) &&
        !ValKnown.One.lshr(MaxCnt).isZero())
      return true;
    break;
  }
  case ISD::UDIV:
  case ISD::SDIV:
    // div exact can only produce a zero if the dividend is zero.
    // TODO: For udiv this is also true if Op1 u<= Op0
    if (Op->getFlags().hasExact())
      return isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
    break;
 
  case ISD::ADD:
    if (Op->getFlags().hasNoUnsignedWrap())
      if (isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1) ||
          isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1))
        return true;
    // TODO: There are a lot more cases we can prove for add.
    break;
 
  case ISD::SUB: {
    if (isNullConstant(Op.getOperand(0)))
      return isKnownNeverZero(Op.getOperand(1), DemandedElts, Depth + 1);
 
    std::optional<bool> ne = KnownBits::ne(
        computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1),
        computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1));
    return ne && *ne;
  }
 
  case ISD::MUL:
    if (Op->getFlags().hasNoSignedWrap() || Op->getFlags().hasNoUnsignedWrap())
      if (isKnownNeverZero(Op.getOperand(1), Depth + 1) &&
          isKnownNeverZero(Op.getOperand(0), Depth + 1))
        return true;
    break;
 
  case ISD::ZERO_EXTEND:
  case ISD::SIGN_EXTEND:
    return isKnownNeverZero(Op.getOperand(0), DemandedElts, Depth + 1);
  case ISD::VSCALE: {
    const Function &F = getMachineFunction().getFunction();
    const APInt &Multiplier = Op.getConstantOperandAPInt(0);
    ConstantRange CR =
        getVScaleRange(&F, Op.getScalarValueSizeInBits()).multiply(Multiplier);
    if (!CR.contains(APInt(CR.getBitWidth(), 0)))
      return true;
    break;
  }
  }
 
  return computeKnownBits(Op, DemandedElts, Depth).isNonZero();
}
 
bool SelectionDAG::cannotBeOrderedNegativeFP(SDValue Op) const {
  if (ConstantFPSDNode *C1 = isConstOrConstSplatFP(Op, true))
    return !C1->isNegative();
 
  switch (Op.getOpcode()) {
  case ISD::FABS:
  case ISD::FEXP:
  case ISD::FEXP2:
  case ISD::FEXP10:
    return true;
  default:
    return false;
  }
 
  llvm_unreachable("covered opcode switch");
}
 
bool SelectionDAG::canIgnoreSignBitOfZero(const SDUse &Use) const {
  assert(Use.getValueType().isFloatingPoint());
  const SDNode *User = Use.getUser();
  if (User->getFlags().hasNoSignedZeros())
    return true;
 
  unsigned OperandNo = Use.getOperandNo();
  // Check if this use is insensitive to the sign of zero
  switch (User->getOpcode()) {
  case ISD::SETCC:
    // Comparisons: IEEE-754 specifies +0.0 == -0.0.
  case ISD::FABS:
    // fabs always produces +0.0.
    return true;
  case ISD::FCOPYSIGN:
    // copysign overwrites the sign bit of the first operand.
    return OperandNo == 0;
  case ISD::FADD:
  case ISD::FSUB: {
    // Arithmetic with non-zero constants fixes the uncertainty around the
    // sign bit.
    SDValue Other = User->getOperand(1 - OperandNo);
    return isKnownNeverLogicalZero(Other);
  }
  case ISD::FP_TO_SINT:
  case ISD::FP_TO_UINT:
    // fp-to-int conversions normalize signed zeros.
    return true;
  default:
    return false;
  }
}
 
bool SelectionDAG::canIgnoreSignBitOfZero(SDValue Op) const {
  if (Op->getFlags().hasNoSignedZeros())
    return true;
  // FIXME: Limit the amount of checked uses to not introduce a compile-time
  // regression. Ideally, this should be implemented as a demanded-bits
  // optimization that stems from the users.
  if (Op->use_size() > 2)
    return false;
  return all_of(Op->uses(),
                [&](const SDUse &Use) { return canIgnoreSignBitOfZero(Use); });
}
 
bool SelectionDAG::isEqualTo(SDValue A, SDValue B) const {
  // Check the obvious case.
  if (A == B) return true;
 
  // For negative and positive zero.
  if (const ConstantFPSDNode *CA = dyn_cast<ConstantFPSDNode>(A))
    if (const ConstantFPSDNode *CB = dyn_cast<ConstantFPSDNode>(B))
      if (CA->isZero() && CB->isZero()) return true;
 
  // Otherwise they may not be equal.
  return false;
}
 
// Only bits set in Mask must be negated, other bits may be arbitrary.
SDValue llvm::getBitwiseNotOperand(SDValue V, SDValue Mask, bool AllowUndefs) {
  if (isBitwiseNot(V, AllowUndefs))
    return V.getOperand(0);
 
  // Handle any_extend (not (truncate X)) pattern, where Mask only sets
  // bits in the non-extended part.
  ConstantSDNode *MaskC = isConstOrConstSplat(Mask);
  if (!MaskC || V.getOpcode() != ISD::ANY_EXTEND)
    return SDValue();
  SDValue ExtArg = V.getOperand(0);
  if (ExtArg.getScalarValueSizeInBits() >=
          MaskC->getAPIntValue().getActiveBits() &&
      isBitwiseNot(ExtArg, AllowUndefs) &&
      ExtArg.getOperand(0).getOpcode() == ISD::TRUNCATE &&
      ExtArg.getOperand(0).getOperand(0).getValueType() == V.getValueType())
    return ExtArg.getOperand(0).getOperand(0);
  return SDValue();
}
 
static bool haveNoCommonBitsSetCommutative(SDValue A, SDValue B) {
  // Match masked merge pattern (X & ~M) op (Y & M)
  // Including degenerate case (X & ~M) op M
  auto MatchNoCommonBitsPattern = [&](SDValue Not, SDValue Mask,
                                      SDValue Other) {
    if (SDValue NotOperand =
            getBitwiseNotOperand(Not, Mask, /* AllowUndefs */ true)) {
      if (NotOperand->getOpcode() == ISD::ZERO_EXTEND ||
          NotOperand->getOpcode() == ISD::TRUNCATE)
        NotOperand = NotOperand->getOperand(0);
 
      if (Other == NotOperand)
        return true;
      if (Other->getOpcode() == ISD::AND)
        return NotOperand == Other->getOperand(0) ||
               NotOperand == Other->getOperand(1);
    }
    return false;
  };
 
  if (A->getOpcode() == ISD::ZERO_EXTEND || A->getOpcode() == ISD::TRUNCATE)
    A = A->getOperand(0);
 
  if (B->getOpcode() == ISD::ZERO_EXTEND || B->getOpcode() == ISD::TRUNCATE)
    B = B->getOperand(0);
 
  if (A->getOpcode() == ISD::AND)
    return MatchNoCommonBitsPattern(A->getOperand(0), A->getOperand(1), B) ||
           MatchNoCommonBitsPattern(A->getOperand(1), A->getOperand(0), B);
  return false;
}
 
// FIXME: unify with llvm::haveNoCommonBitsSet.
bool SelectionDAG::haveNoCommonBitsSet(SDValue A, SDValue B) const {
  assert(A.getValueType() == B.getValueType() &&
         "Values must have the same type");
  if (haveNoCommonBitsSetCommutative(A, B) ||
      haveNoCommonBitsSetCommutative(B, A))
    return true;
  return KnownBits::haveNoCommonBitsSet(computeKnownBits(A),
                                        computeKnownBits(B));
}
 
static SDValue FoldSTEP_VECTOR(const SDLoc &DL, EVT VT, SDValue Step,
                               SelectionDAG &DAG) {
  if (cast<ConstantSDNode>(Step)->isZero())
    return DAG.getConstant(0, DL, VT);
 
  return SDValue();
}
 
static SDValue FoldBUILD_VECTOR(const SDLoc &DL, EVT VT,
                                ArrayRef<SDValue> Ops,
                                SelectionDAG &DAG) {
  int NumOps = Ops.size();
  assert(NumOps != 0 && "Can't build an empty vector!");
  assert(!VT.isScalableVector() &&
         "BUILD_VECTOR cannot be used with scalable types");
  assert(VT.getVectorNumElements() == (unsigned)NumOps &&
         "Incorrect element count in BUILD_VECTOR!");
 
  // BUILD_VECTOR of UNDEFs is UNDEF.
  bool AllPoison = true;
  if (llvm::all_of(Ops, [&AllPoison](SDValue Op) {
        AllPoison &= Op.getOpcode() == ISD::POISON;
        return Op.isUndef();
      }))
    return AllPoison ? DAG.getPOISON(VT) : DAG.getUNDEF(VT);
 
  // BUILD_VECTOR of seq extract/insert from the same vector + type is Identity.
  SDValue IdentitySrc;
  bool IsIdentity = true;
  for (int i = 0; i != NumOps; ++i) {
    if (Ops[i].getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
        Ops[i].getOperand(0).getValueType() != VT ||
        (IdentitySrc && Ops[i].getOperand(0) != IdentitySrc) ||
        !isa<ConstantSDNode>(Ops[i].getOperand(1)) ||
        Ops[i].getConstantOperandAPInt(1) != i) {
      IsIdentity = false;
      break;
    }
    IdentitySrc = Ops[i].getOperand(0);
  }
  if (IsIdentity)
    return IdentitySrc;
 
  return SDValue();
}
 
/// Try to simplify vector concatenation to an input value, undef, or build
/// vector.
static SDValue foldCONCAT_VECTORS(const SDLoc &DL, EVT VT,
                                  ArrayRef<SDValue> Ops,
                                  SelectionDAG &DAG) {
  assert(!Ops.empty() && "Can't concatenate an empty list of vectors!");
  assert(llvm::all_of(Ops,
                      [Ops](SDValue Op) {
                        return Ops[0].getValueType() == Op.getValueType();
                      }) &&
         "Concatenation of vectors with inconsistent value types!");
  assert((Ops[0].getValueType().getVectorElementCount() * Ops.size()) ==
             VT.getVectorElementCount() &&
         "Incorrect element count in vector concatenation!");
 
  if (Ops.size() == 1)
    return Ops[0];
 
  // Concat of UNDEFs is UNDEF.
  bool AllPoison = true;
  if (llvm::all_of(Ops, [&AllPoison](SDValue Op) {
        AllPoison &= Op.getOpcode() == ISD::POISON;
        return Op.isUndef();
      }))
    return AllPoison ? DAG.getPOISON(VT) : DAG.getUNDEF(VT);
 
  // Scan the operands and look for extract operations from a single source
  // that correspond to insertion at the same location via this concatenation:
  // concat (extract X, 0*subvec_elts), (extract X, 1*subvec_elts), ...
  SDValue IdentitySrc;
  bool IsIdentity = true;
  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
    SDValue Op = Ops[i];
    unsigned IdentityIndex = i * Op.getValueType().getVectorMinNumElements();
    if (Op.getOpcode() != ISD::EXTRACT_SUBVECTOR ||
        Op.getOperand(0).getValueType() != VT ||
        (IdentitySrc && Op.getOperand(0) != IdentitySrc) ||
        Op.getConstantOperandVal(1) != IdentityIndex) {
      IsIdentity = false;
      break;
    }
    assert((!IdentitySrc || IdentitySrc == Op.getOperand(0)) &&
           "Unexpected identity source vector for concat of extracts");
    IdentitySrc = Op.getOperand(0);
  }
  if (IsIdentity) {
    assert(IdentitySrc && "Failed to set source vector of extracts");
    return IdentitySrc;
  }
 
  // The code below this point is only designed to work for fixed width
  // vectors, so we bail out for now.
  if (VT.isScalableVector())
    return SDValue();
 
  // A CONCAT_VECTOR of scalar sources, such as UNDEF, BUILD_VECTOR and
  // single-element INSERT_VECTOR_ELT operands can be simplified to one big
  // BUILD_VECTOR.
  // FIXME: Add support for SCALAR_TO_VECTOR as well.
  EVT SVT = VT.getScalarType();
  SmallVector<SDValue, 16> Elts;
  for (SDValue Op : Ops) {
    EVT OpVT = Op.getValueType();
    if (Op.getOpcode() == ISD::POISON)
      Elts.append(OpVT.getVectorNumElements(), DAG.getPOISON(SVT));
    else if (Op.getOpcode() == ISD::UNDEF)
      Elts.append(OpVT.getVectorNumElements(), DAG.getUNDEF(SVT));
    else if (Op.getOpcode() == ISD::BUILD_VECTOR)
      Elts.append(Op->op_begin(), Op->op_end());
    else if (Op.getOpcode() == ISD::INSERT_VECTOR_ELT &&
             OpVT.getVectorNumElements() == 1 &&
             isNullConstant(Op.getOperand(2)))
      Elts.push_back(Op.getOperand(1));
    else
      return SDValue();
  }
 
  // BUILD_VECTOR requires all inputs to be of the same type, find the
  // maximum type and extend them all.
  for (SDValue Op : Elts)
    SVT = (SVT.bitsLT(Op.getValueType()) ? Op.getValueType() : SVT);
 
  if (SVT.bitsGT(VT.getScalarType())) {
    for (SDValue &Op : Elts) {
      if (Op.getOpcode() == ISD::POISON)
        Op = DAG.getPOISON(SVT);
      else if (Op.getOpcode() == ISD::UNDEF)
        Op = DAG.getUNDEF(SVT);
      else
        Op = DAG.getTargetLoweringInfo().isZExtFree(Op.getValueType(), SVT)
                 ? DAG.getZExtOrTrunc(Op, DL, SVT)
                 : DAG.getSExtOrTrunc(Op, DL, SVT);
    }
  }
 
  SDValue V = DAG.getBuildVector(VT, DL, Elts);
  NewSDValueDbgMsg(V, "New node fold concat vectors: ", &DAG);
  return V;
}
 
/// Gets or creates the specified node.
SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT) {
  SDVTList VTs = getVTList(VT);
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opcode, VTs, {});
  FoldingSetInsertToken InsertToken;
  if (SDNode *E = lookupNode(ID, DL, InsertToken))
    return SDValue(E, 0);
 
  auto *N = newSDNode<SDNode>(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs);
  CSEMap.insert(N, InsertToken);
 
  InsertNode(N);
  SDValue V = SDValue(N, 0);
  NewSDValueDbgMsg(V, "Creating new node: ", this);
  return V;
}
 
SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
                              SDValue N1) {
  SDNodeFlags Flags;
  if (Inserter)
    Flags = Inserter->getFlags();
  return getNode(Opcode, DL, VT, N1, Flags);
}
 
SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
                              SDValue N1, const SDNodeFlags Flags) {
  assert(N1.getOpcode() != ISD::DELETED_NODE && "Operand is DELETED_NODE!");
 
  // Constant fold unary operations with a vector integer or float operand.
  switch (Opcode) {
  default:
    // FIXME: Entirely reasonable to perform folding of other unary
    // operations here as the need arises.
    break;
  case ISD::FNEG:
  case ISD::FABS:
  case ISD::FCEIL:
  case ISD::FTRUNC:
  case ISD::FFLOOR:
  case ISD::FP_EXTEND:
  case ISD::FP_TO_SINT:
  case ISD::FP_TO_UINT:
  case ISD::FP_TO_FP16:
  case ISD::FP_TO_BF16:
  case ISD::TRUNCATE:
  case ISD::ANY_EXTEND:
  case ISD::ZERO_EXTEND:
  case ISD::SIGN_EXTEND:
  case ISD::UINT_TO_FP:
  case ISD::SINT_TO_FP:
  case ISD::FP16_TO_FP:
  case ISD::BF16_TO_FP:
  case ISD::BITCAST:
  case ISD::ABS:
  case ISD::ABS_MIN_POISON:
  case ISD::BITREVERSE:
  case ISD::BSWAP:
  case ISD::CTLZ:
  case ISD::CTLZ_ZERO_POISON:
  case ISD::CTTZ:
  case ISD::CTTZ_ZERO_POISON:
  case ISD::CTPOP:
  case ISD::CTLS:
  case ISD::VECREDUCE_ADD:
  case ISD::VECREDUCE_SMAX:
  case ISD::VECREDUCE_SMIN:
  case ISD::VECREDUCE_UMAX:
  case ISD::VECREDUCE_UMIN:
  case ISD::VECREDUCE_MUL:
  case ISD::VECREDUCE_AND:
  case ISD::VECREDUCE_OR:
  case ISD::VECREDUCE_XOR:
  case ISD::STEP_VECTOR: {
    SDValue Ops = {N1};
    if (SDValue Fold = FoldConstantArithmetic(Opcode, DL, VT, Ops))
      return Fold;
  }
  }
 
  unsigned OpOpcode = N1.getNode()->getOpcode();
  switch (Opcode) {
  case ISD::STEP_VECTOR:
    assert(VT.isScalableVector() &&
           "STEP_VECTOR can only be used with scalable types");
    assert(OpOpcode == ISD::TargetConstant &&
           VT.getVectorElementType() == N1.getValueType() &&
           "Unexpected step operand");
    break;
  case ISD::FREEZE:
    assert(VT == N1.getValueType() && "Unexpected VT!");
    if (isGuaranteedNotToBeUndefOrPoison(N1, UndefPoisonKind::UndefOrPoison))
      return N1;
    break;
  case ISD::TokenFactor:
  case ISD::MERGE_VALUES:
  case ISD::CONCAT_VECTORS:
    return N1;         // Factor, merge or concat of one node?  No need.
  case ISD::BUILD_VECTOR: {
    // Attempt to simplify BUILD_VECTOR.
    SDValue Ops[] = {N1};
    if (SDValue V = FoldBUILD_VECTOR(DL, VT, Ops, *this))
      return V;
    break;
  }
  case ISD::FP_ROUND: llvm_unreachable("Invalid method to make FP_ROUND node");
  case ISD::FP_EXTEND:
    assert(VT.isFloatingPoint() && N1.getValueType().isFloatingPoint() &&
           "Invalid FP cast!");
    if (N1.getValueType() == VT) return N1;  // noop conversion.
    assert((!VT.isVector() || VT.getVectorElementCount() ==
                                  N1.getValueType().getVectorElementCount()) &&
           "Vector element count mismatch!");
    assert(N1.getValueType().bitsLT(VT) && "Invalid fpext node, dst < src!");
    if (N1.isUndef())
      return getUNDEF(VT);
    break;
  case ISD::FP_TO_SINT:
  case ISD::FP_TO_UINT:
    if (N1.isUndef())
      return getUNDEF(VT);
    break;
  case ISD::SINT_TO_FP:
  case ISD::UINT_TO_FP:
    // [us]itofp(undef) = 0, because the result value is bounded.
    if (N1.isUndef())
      return getConstantFP(0.0, DL, VT);
    break;
  case ISD::SIGN_EXTEND:
    assert(VT.isInteger() && N1.getValueType().isInteger() &&
           "Invalid SIGN_EXTEND!");
    assert(VT.isVector() == N1.getValueType().isVector() &&
           "SIGN_EXTEND result type type should be vector iff the operand "
           "type is vector!");
    if (N1.getValueType() == VT) return N1;   // noop extension
    assert((!VT.isVector() || VT.getVectorElementCount() ==
                                  N1.getValueType().getVectorElementCount()) &&
           "Vector element count mismatch!");
    assert(N1.getValueType().bitsLT(VT) && "Invalid sext node, dst < src!");
    if (OpOpcode == ISD::SIGN_EXTEND || OpOpcode == ISD::ZERO_EXTEND) {
      SDNodeFlags Flags;
      if (OpOpcode == ISD::ZERO_EXTEND)
        Flags.setNonNeg(N1->getFlags().hasNonNeg());
      SDValue NewVal = getNode(OpOpcode, DL, VT, N1.getOperand(0), Flags);
      transferDbgValues(N1, NewVal);
      return NewVal;
    }
 
    if (OpOpcode == ISD::POISON)
      return getPOISON(VT);
 
    if (N1.isUndef())
      // sext(undef) = 0, because the top bits will all be the same.
      return getConstant(0, DL, VT);
 
    // Skip unnecessary sext_inreg pattern:
    // (sext (trunc x)) -> x iff the upper bits are all signbits.
    if (OpOpcode == ISD::TRUNCATE) {
      SDValue OpOp = N1.getOperand(0);
      if (OpOp.getValueType() == VT) {
        unsigned NumSignExtBits =
            VT.getScalarSizeInBits() - N1.getScalarValueSizeInBits();
        if (ComputeNumSignBits(OpOp) > NumSignExtBits) {
          transferDbgValues(N1, OpOp);
          return OpOp;
        }
      }
    }
    break;
  case ISD::ZERO_EXTEND:
    assert(VT.isInteger() && N1.getValueType().isInteger() &&
           "Invalid ZERO_EXTEND!");
    assert(VT.isVector() == N1.getValueType().isVector() &&
           "ZERO_EXTEND result type type should be vector iff the operand "
           "type is vector!");
    if (N1.getValueType() == VT) return N1;   // noop extension
    assert((!VT.isVector() || VT.getVectorElementCount() ==
                                  N1.getValueType().getVectorElementCount()) &&
           "Vector element count mismatch!");
    assert(N1.getValueType().bitsLT(VT) && "Invalid zext node, dst < src!");
    if (OpOpcode == ISD::ZERO_EXTEND) { // (zext (zext x)) -> (zext x)
      SDNodeFlags Flags;
      Flags.setNonNeg(N1->getFlags().hasNonNeg());
      SDValue NewVal =
          getNode(ISD::ZERO_EXTEND, DL, VT, N1.getOperand(0), Flags);
      transferDbgValues(N1, NewVal);
      return NewVal;
    }
 
    if (OpOpcode == ISD::POISON)
      return getPOISON(VT);
 
    if (N1.isUndef())
      // zext(undef) = 0, because the top bits will be zero.
      return getConstant(0, DL, VT);
 
    // Skip unnecessary zext_inreg pattern:
    // (zext (trunc x)) -> x iff the upper bits are known zero.
    // TODO: Remove (zext (trunc (and x, c))) exception which some targets
    // use to recognise zext_inreg patterns.
    if (OpOpcode == ISD::TRUNCATE) {
      SDValue OpOp = N1.getOperand(0);
      if (OpOp.getValueType() == VT) {
        if (OpOp.getOpcode() != ISD::AND) {
          APInt HiBits = APInt::getBitsSetFrom(VT.getScalarSizeInBits(),
                                               N1.getScalarValueSizeInBits());
          if (MaskedValueIsZero(OpOp, HiBits)) {
            transferDbgValues(N1, OpOp);
            return OpOp;
          }
        }
      }
    }
    break;
  case ISD::ANY_EXTEND:
    assert(VT.isInteger() && N1.getValueType().isInteger() &&
           "Invalid ANY_EXTEND!");
    assert(VT.isVector() == N1.getValueType().isVector() &&
           "ANY_EXTEND result type type should be vector iff the operand "
           "type is vector!");
    if (N1.getValueType() == VT) return N1;   // noop extension
    assert((!VT.isVector() || VT.getVectorElementCount() ==
                                  N1.getValueType().getVectorElementCount()) &&
           "Vector element count mismatch!");
    assert(N1.getValueType().bitsLT(VT) && "Invalid anyext node, dst < src!");
 
    if (OpOpcode == ISD::ZERO_EXTEND || OpOpcode == ISD::SIGN_EXTEND ||
        OpOpcode == ISD::ANY_EXTEND) {
      SDNodeFlags Flags;
      if (OpOpcode == ISD::ZERO_EXTEND)
        Flags.setNonNeg(N1->getFlags().hasNonNeg());
      // (ext (zext x)) -> (zext x)  and  (ext (sext x)) -> (sext x)
      return getNode(OpOpcode, DL, VT, N1.getOperand(0), Flags);
    }
    if (N1.isUndef())
      return getUNDEF(VT);
 
    // (ext (trunc x)) -> x
    if (OpOpcode == ISD::TRUNCATE) {
      SDValue OpOp = N1.getOperand(0);
      if (OpOp.getValueType() == VT) {
        transferDbgValues(N1, OpOp);
        return OpOp;
      }
    }
    break;
  case ISD::TRUNCATE:
    assert(VT.isInteger() && N1.getValueType().isInteger() &&
           "Invalid TRUNCATE!");
    assert(VT.isVector() == N1.getValueType().isVector() &&
           "TRUNCATE result type type should be vector iff the operand "
           "type is vector!");
    if (N1.getValueType() == VT) return N1;   // noop truncate
    assert((!VT.isVector() || VT.getVectorElementCount() ==
                                  N1.getValueType().getVectorElementCount()) &&
           "Vector element count mismatch!");
    assert(N1.getValueType().bitsGT(VT) && "Invalid truncate node, src < dst!");
    if (OpOpcode == ISD::TRUNCATE)
      return getNode(ISD::TRUNCATE, DL, VT, N1.getOperand(0));
    if (OpOpcode == ISD::ZERO_EXTEND || OpOpcode == ISD::SIGN_EXTEND ||
        OpOpcode == ISD::ANY_EXTEND) {
      // If the source is smaller than the dest, we still need an extend.
      if (N1.getOperand(0).getValueType().getScalarType().bitsLT(
              VT.getScalarType())) {
        SDNodeFlags Flags;
        if (OpOpcode == ISD::ZERO_EXTEND)
          Flags.setNonNeg(N1->getFlags().hasNonNeg());
        return getNode(OpOpcode, DL, VT, N1.getOperand(0), Flags);
      }
      if (N1.getOperand(0).getValueType().bitsGT(VT))
        return getNode(ISD::TRUNCATE, DL, VT, N1.getOperand(0));
      return N1.getOperand(0);
    }
    if (N1.isUndef())
      return getUNDEF(VT);
    if (OpOpcode == ISD::VSCALE && !NewNodesMustHaveLegalTypes)
      return getVScale(DL, VT,
                       N1.getConstantOperandAPInt(0).trunc(VT.getSizeInBits()));
    break;
  case ISD::ANY_EXTEND_VECTOR_INREG:
  case ISD::ZERO_EXTEND_VECTOR_INREG:
  case ISD::SIGN_EXTEND_VECTOR_INREG:
    assert(VT.isVector() && "This DAG node is restricted to vector types.");
    assert(N1.getValueType().bitsLE(VT) &&
           "The input must be the same size or smaller than the result.");
    assert(VT.getVectorMinNumElements() <
               N1.getValueType().getVectorMinNumElements() &&
           "The destination vector type must have fewer lanes than the input.");
    break;
  case ISD::ABS:
    assert(VT.isInteger() && VT == N1.getValueType() && "Invalid ABS!");
    if (N1.isUndef())
      return getConstant(0, DL, VT);
    break;
  case ISD::ABS_MIN_POISON:
    assert(VT.isInteger() && VT == N1.getValueType() &&
           "Invalid ABS_MIN_POISON!");
    if (N1.isUndef())
      return getConstant(0, DL, VT);
    break;
  case ISD::BSWAP:
    assert(VT.isInteger() && VT == N1.getValueType() && "Invalid BSWAP!");
    assert((VT.getScalarSizeInBits() % 16 == 0) &&
           "BSWAP types must be a multiple of 16 bits!");
    if (N1.isUndef())
      return getUNDEF(VT);
    // bswap(bswap(X)) -> X.
    if (OpOpcode == ISD::BSWAP)
      return N1.getOperand(0);
    break;
  case ISD::BITREVERSE:
    assert(VT.isInteger() && VT == N1.getValueType() && "Invalid BITREVERSE!");
    if (N1.isUndef())
      return getUNDEF(VT);
    break;
  case ISD::BITCAST:
    assert(VT.getSizeInBits() == N1.getValueSizeInBits() &&
           "Cannot BITCAST between types of different sizes!");
    if (VT == N1.getValueType()) return N1;   // noop conversion.
    if (OpOpcode == ISD::BITCAST) // bitconv(bitconv(x)) -> bitconv(x)
      return getNode(ISD::BITCAST, DL, VT, N1.getOperand(0));
    if (N1.isUndef())
      return getUNDEF(VT);
    break;
  case ISD::SCALAR_TO_VECTOR:
    assert(VT.isVector() && !N1.getValueType().isVector() &&
           (VT.getVectorElementType() == N1.getValueType() ||
            (VT.getVectorElementType().isInteger() &&
             N1.getValueType().isInteger() &&
             VT.getVectorElementType().bitsLE(N1.getValueType()))) &&
           "Illegal SCALAR_TO_VECTOR node!");
    if (N1.isUndef())
      return getUNDEF(VT);
    // scalar_to_vector(extract_vector_elt V, 0) -> V, top bits are undefined.
    if (OpOpcode == ISD::EXTRACT_VECTOR_ELT &&
        isa<ConstantSDNode>(N1.getOperand(1)) &&
        N1.getConstantOperandVal(1) == 0 &&
        N1.getOperand(0).getValueType() == VT)
      return N1.getOperand(0);
    break;
  case ISD::FNEG:
    // Negation of an unknown bag of bits is still completely undefined.
    if (N1.isUndef())
      return getUNDEF(VT);
 
    if (OpOpcode == ISD::FNEG) // --X -> X
      return N1.getOperand(0);
    break;
  case ISD::FABS:
    if (OpOpcode == ISD::FNEG) // abs(-X) -> abs(X)
      return getNode(ISD::FABS, DL, VT, N1.getOperand(0));
    break;
  case ISD::VSCALE:
    assert(VT == N1.getValueType() && "Unexpected VT!");
    break;
  case ISD::CTPOP:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return N1;
    break;
  case ISD::CTLZ:
  case ISD::CTTZ:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNOT(DL, N1, N1.getValueType());
    break;
  case ISD::CTLS:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getConstant(0, DL, VT);
    break;
  case ISD::VECREDUCE_ADD:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNode(ISD::VECREDUCE_XOR, DL, VT, N1);
    break;
  case ISD::VECREDUCE_SMIN:
  case ISD::VECREDUCE_UMAX:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNode(ISD::VECREDUCE_OR, DL, VT, N1);
    break;
  case ISD::VECREDUCE_SMAX:
  case ISD::VECREDUCE_UMIN:
    if (N1.getValueType().getScalarType() == MVT::i1)
      return getNode(ISD::VECREDUCE_AND, DL, VT, N1);
    break;
  case ISD::SPLAT_VECTOR:
    assert(VT.isVector() && "Wrong return type!");
    // FIXME: Hexagon uses i32 scalar for a floating point zero vector so allow
    // that for now.
    assert((VT.getVectorElementType() == N1.getValueType() ||
            (VT.isFloatingPoint() && N1.getValueType() == MVT::i32) ||
            (VT.getVectorElementType().isInteger() &&
             N1.getValueType().isInteger() &&
             VT.getVectorElementType().bitsLE(N1.getValueType()))) &&
           "Wrong operand type!");
    break;
  }
 
  SDNode *N;
  SDVTList VTs = getVTList(VT);
  SDValue Ops[] = {N1};
  if (VT != MVT::Glue) { // Don't CSE glue producing nodes
    FoldingSetNodeID ID;
    AddNodeIDNode(ID, Opcode, VTs, Ops);
    FoldingSetInsertToken InsertToken;
    if (SDNode *E = lookupNode(ID, DL, InsertToken)) {
      E->intersectFlagsWith(Flags);
      return SDValue(E, 0);
    }
 
    N = newSDNode<SDNode>(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs);
    N->setFlags(Flags);
    createOperands(N, Ops);
    CSEMap.insert(N, InsertToken);
  } else {
    N = newSDNode<SDNode>(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs);
    createOperands(N, Ops);
  }
 
  InsertNode(N);
  SDValue V = SDValue(N, 0);
  NewSDValueDbgMsg(V, "Creating new node: ", this);
  return V;
}
 
static APInt getIntegerIdentity(unsigned Opcode, unsigned BitWidth) {
  switch (Opcode) {
  default:
    llvm_unreachable("Unexpected integer identity opcode");
  case ISD::ADD:
  case ISD::OR:
  case ISD::XOR:
  case ISD::UMAX:
    return APInt::getZero(BitWidth);
  case ISD::MUL:
    return APInt(BitWidth, 1);
  case ISD::AND:
  case ISD::UMIN:
    return APInt::getAllOnes(BitWidth);
  case ISD::SMAX:
    return APInt::getSignedMinValue(BitWidth);
  case ISD::SMIN:
    return APInt::getSignedMaxValue(BitWidth);
  }
}
 
static std::optional<APInt> FoldValue(unsigned Opcode, const APInt &C1,
                                      const APInt &C2) {
  switch (Opcode) {
  case ISD::ADD:  return C1 + C2;
  case ISD::SUB:  return C1 - C2;
  case ISD::MUL:  return C1 * C2;
  case ISD::AND:  return C1 & C2;
  case ISD::OR:   return C1 | C2;
  case ISD::XOR:  return C1 ^ C2;
  case ISD::SHL:  return C1 << C2;
  case ISD::SRL:  return C1.lshr(C2);
  case ISD::SRA:  return C1.ashr(C2);
  case ISD::ROTL: return C1.rotl(C2);
  case ISD::ROTR: return C1.rotr(C2);
  case ISD::SMIN: return C1.sle(C2) ? C1 : C2;
  case ISD::SMAX: return C1.sge(C2) ? C1 : C2;
  case ISD::UMIN: return C1.ule(C2) ? C1 : C2;
  case ISD::UMAX: return C1.uge(C2) ? C1 : C2;
  case ISD::SADDSAT: return C1.sadd_sat(C2);
  case ISD::UADDSAT: return C1.uadd_sat(C2);
  case ISD::SSUBSAT: return C1.ssub_sat(C2);
  case ISD::USUBSAT: return C1.usub_sat(C2);
  case ISD::SSHLSAT: return C1.sshl_sat(C2);
  case ISD::USHLSAT: return C1.ushl_sat(C2);
  case ISD::UDIV:
    if (!C2.getBoolValue())
      break;
    return C1.udiv(C2);
  case ISD::UREM:
    if (!C2.getBoolValue())
      break;
    return C1.urem(C2);
  case ISD::SDIV:
    if (!C2.getBoolValue())
      break;
    return C1.sdiv(C2);
  case ISD::SREM:
    if (!C2.getBoolValue())
      break;
    return C1.srem(C2);
  case ISD::AVGFLOORS:
    return APIntOps::avgFloorS(C1, C2);
  case ISD::AVGFLOORU:
    return APIntOps::avgFloorU(C1, C2);
  case ISD::AVGCEILS:
    return APIntOps::avgCeilS(C1, C2);
  case ISD::AVGCEILU:
    return APIntOps::avgCeilU(C1, C2);
  case ISD::ABDS:
    return APIntOps::abds(C1, C2);
  case ISD::ABDU:
    return APIntOps::abdu(C1, C2);
  case ISD::MULHS:
    return APIntOps::mulhs(C1, C2);
  case ISD::MULHU:
    return APIntOps::mulhu(C1, C2);
  case ISD::CLMUL:
    return APIntOps::clmul(C1, C2);
  case ISD::CLMULR:
    return APIntOps::clmulr(C1, C2);
  case ISD::CLMULH:
    return APIntOps::clmulh(C1, C2);
  case ISD::PEXT:
    return APIntOps::pext(C1, C2);
  case ISD::PDEP:
    return APIntOps::pdep(C1, C2);
  }
  return std::nullopt;
}
// Handle constant folding with UNDEF.
// TODO: Handle more cases.
static std::optional<APInt> FoldValueWithUndef(unsigned Opcode, const APInt &C1,
                                               bool IsUndef1, const APInt &C2,
                                               bool IsUndef2) {
  if (!(IsUndef1 || IsUndef2))
    return FoldValue(Opcode, C1, C2);
 
  // Fold and(x, undef) -> 0
  // Fold mul(x, undef) -> 0
  if (Opcode == ISD::AND || Opcode == ISD::MUL)
    return APInt::getZero(C1.getBitWidth());
 
  return std::nullopt;
}
 
SDValue SelectionDAG::FoldSymbolOffset(unsigned Opcode, EVT VT,
                                       const GlobalAddressSDNode *GA,
                                       const SDNode *N2) {
  if (GA->getOpcode() != ISD::GlobalAddress)
    return SDValue();
  if (!TLI->isOffsetFoldingLegal(GA))
    return SDValue();
  auto *C2 = dyn_cast<ConstantSDNode>(N2);
  if (!C2)
    return SDValue();
  int64_t Offset = C2->getSExtValue();
  switch (Opcode) {
  case ISD::ADD:
  case ISD::PTRADD:
    break;
  case ISD::SUB: Offset = -uint64_t(Offset); break;
  default: return SDValue();
  }
  return getGlobalAddress(GA->getGlobal(), SDLoc(C2), VT,
                          GA->getOffset() + uint64_t(Offset));
}
 
bool SelectionDAG::isUndef(unsigned Opcode, ArrayRef<SDValue> Ops) {
  switch (Opcode) {
  case ISD::SDIV:
  case ISD::UDIV:
  case ISD::SREM:
  case ISD::UREM: {
    // If a divisor is zero/undef or any element of a divisor vector is
    // zero/undef, the whole op is undef.
    assert(Ops.size() == 2 && "Div/rem should have 2 operands");
    SDValue Divisor = Ops[1];
    if (Divisor.isUndef() || isNullConstant(Divisor))
      return true;
 
    return ISD::isBuildVectorOfConstantSDNodes(Divisor.getNode()) &&
           llvm::any_of(Divisor->op_values(),
                        [](SDValue V) { return V.isUndef() ||
                                        isNullConstant(V); });
    // TODO: Handle signed overflow.
  }
  // TODO: Handle oversized shifts.
  default:
    return false;
  }
}
 
SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode, const SDLoc &DL,
                                             EVT VT, ArrayRef<SDValue> Ops,
                                             SDNodeFlags Flags) {
  // If the opcode is a target-specific ISD node, there's nothing we can
  // do here and the operand rules may not line up with the below, so
  // bail early.
  // We can't create a scalar CONCAT_VECTORS so skip it. It will break
  // for concats involving SPLAT_VECTOR. Concats of BUILD_VECTORS are handled by
  // foldCONCAT_VECTORS in getNode before this is called.
  if (Opcode >= ISD::BUILTIN_OP_END || Opcode == ISD::CONCAT_VECTORS)
    return SDValue();
 
  unsigned NumOps = Ops.size();
  if (NumOps == 0)
    return SDValue();
 
  if (isUndef(Opcode, Ops))
    return getUNDEF(VT);
 
  // Handle unary special cases.
  if (NumOps == 1) {
    SDValue N1 = Ops[0];
 
    // Constant fold unary operations with an integer constant operand. Even
    // opaque constant will be folded, because the folding of unary operations
    // doesn't create new constants with different values. Nevertheless, the
    // opaque flag is preserved during folding to prevent future folding with
    // other constants.
    if (auto *C = dyn_cast<ConstantSDNode>(N1)) {
      const APInt &Val = C->getAPIntValue();
      switch (Opcode) {
      case ISD::SIGN_EXTEND:
        return getConstant(Val.sextOrTrunc(VT.getSizeInBits()), DL, VT,
                           C->isTargetOpcode(), C->isOpaque());
      case ISD::TRUNCATE:
        if (C->isOpaque())
          break;
        [[fallthrough]];
      case ISD::ZERO_EXTEND:
        return getConstant(Val.zextOrTrunc(VT.getSizeInBits()), DL, VT,
                           C->isTargetOpcode(), C->isOpaque());
      case ISD::ANY_EXTEND:
        // Some targets like RISCV prefer to sign extend some types.
        if (TLI->isSExtCheaperThanZExt(N1.getValueType(), VT))
          return getConstant(Val.sextOrTrunc(VT.getSizeInBits()), DL, VT,
                             C->isTargetOpcode(), C->isOpaque());
        return getConstant(Val.zextOrTrunc(VT.getSizeInBits()), DL, VT,
                           C->isTargetOpcode(), C->isOpaque());
      case ISD::ABS:
        return getConstant(Val.abs(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::ABS_MIN_POISON:
        if (Val.isMinSignedValue())
          return getPOISON(VT);
        return getConstant(Val.abs(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::BITREVERSE:
        return getConstant(Val.reverseBits(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::BSWAP:
        return getConstant(Val.byteSwap(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::CTPOP:
        return getConstant(Val.popcount(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::CTLZ:
      case ISD::CTLZ_ZERO_POISON:
        return getConstant(Val.countl_zero(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::CTTZ:
      case ISD::CTTZ_ZERO_POISON:
        return getConstant(Val.countr_zero(), DL, VT, C->isTargetOpcode(),
                           C->isOpaque());
      case ISD::CTLS:
        // CTLS returns the number of extra sign bits so subtract one.
        return getConstant(Val.getNumSignBits() - 1, DL, VT,
                           C->isTargetOpcode(), C->isOpaque());
      case ISD::UINT_TO_FP:
      case ISD::SINT_TO_FP: {
        APFloat FPV(VT.getFltSemantics(), APInt::getZero(VT.getSizeInBits()));
        (void)FPV.convertFromAPInt(Val, Opcode == ISD::SINT_TO_FP,
                                   APFloat::rmNearestTiesToEven);
        return getConstantFP(FPV, DL, VT);
      }
      case ISD::FP16_TO_FP:
      case ISD::BF16_TO_FP: {
        bool Ignored;
        APFloat FPV(Opcode == ISD::FP16_TO_FP ? APFloat::IEEEhalf()
                                              : APFloat::BFloat(),
                    (Val.getBitWidth() == 16) ? Val : Val.trunc(16));
 
        // This can return overflow, underflow, or inexact; we don't care.
        // FIXME need to be more flexible about rounding mode.
        (void)FPV.convert(VT.getFltSemantics(), APFloat::rmNearestTiesToEven,
                          &Ignored);
        return getConstantFP(FPV, DL, VT);
      }
      case ISD::STEP_VECTOR:
        if (SDValue V = FoldSTEP_VECTOR(DL, VT, N1, *this))
          return V;
        break;
      case ISD::BITCAST:
        if (VT == MVT::f16 && C->getValueType(0) == MVT::i16)
          return getConstantFP(APFloat(APFloat::IEEEhalf(), Val), DL, VT);
        if (VT == MVT::f32 && C->getValueType(0) == MVT::i32)
          return getConstantFP(APFloat(APFloat::IEEEsingle(), Val), DL, VT);
        if (VT == MVT::f64 && C->getValueType(0) == MVT::i64)
          return getConstantFP(APFloat(APFloat::IEEEdouble(), Val), DL, VT);
        if (VT == MVT::f128 && C->getValueType(0) == MVT::i128)
          return getConstantFP(APFloat(APFloat::IEEEquad(), Val), DL, VT);
        break;
      }
    }
 
    // Constant fold unary operations with a floating point constant operand.
    if (auto *C = dyn_cast<ConstantFPSDNode>(N1)) {
      APFloat V = C->getValueAPF(); // make copy
      switch (Opcode) {
      case ISD::FNEG:
        V.changeSign();
        return getConstantFP(V, DL, VT);
      case ISD::FABS:
        V.clearSign();
        return getConstantFP(V, DL, VT);
      case ISD::FCEIL: {
        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardPositive);
        if (fs == APFloat::opOK || fs == APFloat::opInexact)
          return getConstantFP(V, DL, VT);
        return SDValue();
      }
      case ISD::FTRUNC: {
        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardZero);
        if (fs == APFloat::opOK || fs == APFloat::opInexact)
          return getConstantFP(V, DL, VT);
        return SDValue();
      }
      case ISD::FFLOOR: {
        APFloat::opStatus fs = V.roundToIntegral(APFloat::rmTowardNegative);
        if (fs == APFloat::opOK || fs == APFloat::opInexact)
          return getConstantFP(V, DL, VT);
        return SDValue();
      }
      case ISD::FP_EXTEND: {
        bool ignored;
        // This can return overflow, underflow, or inexact; we don't care.
        // FIXME need to be more flexible about rounding mode.
        (void)V.convert(VT.getFltSemantics(), APFloat::rmNearestTiesToEven,
                        &ignored);
        return getConstantFP(V, DL, VT);
      }
      case ISD::FP_TO_SINT:
      case ISD::FP_TO_UINT: {
        bool ignored;
        APSInt IntVal(VT.getSizeInBits(), Opcode == ISD::FP_TO_UINT);
        // FIXME need to be more flexible about rounding mode.
        APFloat::opStatus s =
            V.convertToInteger(IntVal, APFloat::rmTowardZero, &ignored);
        if (s == APFloat::opInvalidOp) // inexact is OK, in fact usual
          break;
        return getConstant(IntVal, DL, VT);
      }
      case ISD::FP_TO_FP16:
      case ISD::FP_TO_BF16: {
        bool Ignored;
        // This can return overflow, underflow, or inexact; we don't care.
        // FIXME need to be more flexible about rounding mode.
        (void)V.convert(Opcode == ISD::FP_TO_FP16 ? APFloat::IEEEhalf()
                                                  : APFloat::BFloat(),
                        APFloat::rmNearestTiesToEven, &Ignored);
        return getConstant(V.bitcastToAPInt().getZExtValue(), DL, VT);
      }
      case ISD::BITCAST:
        if (VT == MVT::i16 && C->getValueType(0) == MVT::f16)
          return getConstant((uint16_t)V.bitcastToAPInt().getZExtValue(), DL,
                             VT);
        if (VT == MVT::i16 && C->getValueType(0) == MVT::bf16)
          return getConstant((uint16_t)V.bitcastToAPInt().getZExtValue(), DL,
                             VT);
        if (VT == MVT::i32 && C->getValueType(0) == MVT::f32)
          return getConstant((uint32_t)V.bitcastToAPInt().getZExtValue(), DL,
                             VT);
        if (VT == MVT::i64 && C->getValueType(0) == MVT::f64)
          return getConstant(V.bitcastToAPInt().getZExtValue(), DL, VT);
        break;
      }
    }
 
    // Early-out if we failed to constant fold a bitcast.
    if (Opcode == ISD::BITCAST)
      return SDValue();
 
    // Constant fold integer vector reductions with constant BUILD_VECTORs.
    if ((Opcode == ISD::VECREDUCE_ADD || Opcode == ISD::VECREDUCE_SMAX ||
         Opcode == ISD::VECREDUCE_SMIN || Opcode == ISD::VECREDUCE_UMAX ||
         Opcode == ISD::VECREDUCE_UMIN || Opcode == ISD::VECREDUCE_MUL ||
         Opcode == ISD::VECREDUCE_OR || Opcode == ISD::VECREDUCE_XOR ||
         Opcode == ISD::VECREDUCE_AND) &&
        ISD::isBuildVectorOfConstantSDNodes(N1.getNode())) {
      unsigned EltBits = N1.getValueType().getScalarSizeInBits();
      unsigned BaseOpcode = ISD::getVecReduceBaseOpcode(Opcode);
      APInt Acc = getIntegerIdentity(BaseOpcode, EltBits);
      for (SDValue Elt : N1->op_values()) {
        if (Elt.getOpcode() == ISD::POISON)
          return getPOISON(VT);
        if (Elt.isUndef() || cast<ConstantSDNode>(Elt)->isOpaque())
          return SDValue();
        APInt Value = cast<ConstantSDNode>(Elt)->getAPIntValue().trunc(EltBits);
        std::optional<APInt> Folded = FoldValue(BaseOpcode, Acc, Value);
        assert(Folded &&
               "Expected vector reduction base opcode to be foldable");
        Acc = *Folded;
      }
      EVT EltVT = N1.getValueType().getScalarType();
      return getAnyExtOrTrunc(getConstant(Acc, DL, EltVT), DL, VT);
    }
  }
 
  // Handle binops special cases.
  if (NumOps == 2) {
    if (SDValue CFP = foldConstantFPMath(Opcode, DL, VT, Ops))
      return CFP;
 
    if (auto *C1 = dyn_cast<ConstantSDNode>(Ops[0])) {
      if (auto *C2 = dyn_cast<ConstantSDNode>(Ops[1])) {
        if (C1->isOpaque() || C2->isOpaque())
          return SDValue();
 
        std::optional<APInt> FoldAttempt =
            FoldValue(Opcode, C1->getAPIntValue(), C2->getAPIntValue());
        if (!FoldAttempt)
          return SDValue();
 
        SDValue Folded = getConstant(*FoldAttempt, DL, VT);
        assert((!Folded || !VT.isVector()) &&
               "Can't fold vectors ops with scalar operands");
        return Folded;
      }
    }
 
    // fold (add Sym, c) -> Sym+c
    if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Ops[0]))
      return FoldSymbolOffset(Opcode, VT, GA, Ops[1].getNode());
    if (TLI->isCommutativeBinOp(Opcode))
      if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Ops[1]))
        return FoldSymbolOffset(Opcode, VT, GA, Ops[0].getNode());
 
    // fold (sext_in_reg c1) -> c2
    if (Opcode == ISD::SIGN_EXTEND_INREG) {
      EVT EVT = cast<VTSDNode>(Ops[1])->getVT();
 
      auto SignExtendInReg = [&](APInt Val, llvm::EVT ConstantVT) {
        unsigned FromBits = EVT.getScalarSizeInBits();
        Val <<= Val.getBitWidth() - FromBits;
        Val.ashrInPlace(Val.getBitWidth() - FromBits);
        return getConstant(Val, DL, ConstantVT);
      };
 
      if (auto *C1 = dyn_cast<ConstantSDNode>(Ops[0])) {
        const APInt &Val = C1->getAPIntValue();
        return SignExtendInReg(Val, VT);
      }
 
      if (ISD::isBuildVectorOfConstantSDNodes(Ops[0].getNode())) {
        SmallVector<SDValue, 8> ScalarOps;
        llvm::EVT OpVT = Ops[0].getOperand(0).getValueType();
        for (int I = 0, E = VT.getVectorNumElements(); I != E; ++I) {
          SDValue Op = Ops[0].getOperand(I);
          if (Op.isUndef()) {
            ScalarOps.push_back(getUNDEF(OpVT));
            continue;
          }
          const APInt &Val = cast<ConstantSDNode>(Op)->getAPIntValue();
          ScalarOps.push_back(SignExtendInReg(Val, OpVT));
        }
        return getBuildVector(VT, DL, ScalarOps);
      }
 
      if (Ops[0].getOpcode() == ISD::SPLAT_VECTOR &&
          isa<ConstantSDNode>(Ops[0].getOperand(0)))
        return getNode(ISD::SPLAT_VECTOR, DL, VT,
                       SignExtendInReg(Ops[0].getConstantOperandAPInt(0),
                                       Ops[0].getOperand(0).getValueType()));
    }
  }
 
  // Handle fshl/fshr special cases.
  if (Opcode == ISD::FSHL || Opcode == ISD::FSHR) {
    auto *C1 = dyn_cast<ConstantSDNode>(Ops[0]);
    auto *C2 = dyn_cast<ConstantSDNode>(Ops[1]);
    auto *C3 = dyn_cast<ConstantSDNode>(Ops[2]);
 
    if (C1 && C2 && C3) {
      if (C1->isOpaque() || C2->isOpaque() || C3->isOpaque())
        return SDValue();
      const APInt &V1 = C1->getAPIntValue(), &V2 = C2->getAPIntValue(),
                  &V3 = C3->getAPIntValue();
 
      APInt FoldedVal = Opcode == ISD::FSHL ? APIntOps::fshl(V1, V2, V3)
                                            : APIntOps::fshr(V1, V2, V3);
      return getConstant(FoldedVal, DL, VT);
    }
  }
 
  // Handle fma/fmad special cases.
  if (Opcode == ISD::FMA || Opcode == ISD::FMAD || Opcode == ISD::FMULADD) {
    assert(VT.isFloatingPoint() && "This operator only applies to FP types!");
    assert(Ops[0].getValueType() == VT && Ops[1].getValueType() == VT &&
           Ops[2].getValueType() == VT && "FMA types must match!");
    ConstantFPSDNode *C1 = dyn_cast<ConstantFPSDNode>(Ops[0]);
    ConstantFPSDNode *C2 = dyn_cast<ConstantFPSDNode>(Ops[1]);
    ConstantFPSDNode *C3 = dyn_cast<ConstantFPSDNode>(Ops[2]);
    if (C1 && C2 && C3) {
      APFloat V1 = C1->getValueAPF();
      const APFloat &V2 = C2->getValueAPF();
      const APFloat &V3 = C3->getValueAPF();
      if (Opcode == ISD::FMAD || Opcode == ISD::FMULADD) {
        V1.multiply(V2, APFloat::rmNearestTiesToEven);
        V1.add(V3, APFloat::rmNearestTiesToEven);
      } else
        V1.fusedMultiplyAdd(V2, V3, APFloat::rmNearestTiesToEven);
      return getConstantFP(V1, DL, VT);
    }
  }
 
  // This is for vector folding only from here on.
  if (!VT.isVector())
    return SDValue();
 
  // Constant fold integer partial reductions with constant BUILD_VECTOR
  // operands. The reduction order is deliberately unspecified. Use the same
  // subvector layout as TargetLowering::expandPartialReduceMLA(), where input
  // lane I contributes to accumulator lane I % NumAccElts.
  if (Opcode == ISD::PARTIAL_REDUCE_SMLA ||
      Opcode == ISD::PARTIAL_REDUCE_UMLA ||
      Opcode == ISD::PARTIAL_REDUCE_SUMLA) {
    // These nodes have no scalar form, so unsupported cases must not fall
    // through to generic per-lane vector folding.
    if (!llvm::all_of(Ops, [](SDValue Op) {
          return ISD::isBuildVectorOfConstantSDNodes(Op.getNode());
        }))
      return SDValue();
 
    unsigned AccEltBits = VT.getScalarSizeInBits();
    unsigned InputEltBits = Ops[1].getScalarValueSizeInBits();
    unsigned NumAccElts = VT.getVectorNumElements();
    unsigned NumInputElts = Ops[1].getValueType().getVectorNumElements();
    SmallVector<APInt, 8> Results(NumAccElts, APInt::getZero(AccEltBits));
    BitVector PoisonElts(NumAccElts);
 
    for (unsigned I = 0; I != NumAccElts; ++I) {
      SDValue Elt = Ops[0].getOperand(I);
      if (Elt.getOpcode() == ISD::POISON) {
        PoisonElts.set(I);
        continue;
      }
      auto *C = dyn_cast<ConstantSDNode>(Elt);
      if (!C || C->isOpaque())
        return SDValue();
      Results[I] = C->getAPIntValue().trunc(AccEltBits);
    }
 
    bool IsLHSSigned = Opcode != ISD::PARTIAL_REDUCE_UMLA;
    bool IsRHSSigned = Opcode == ISD::PARTIAL_REDUCE_SMLA;
    for (unsigned I = 0; I != NumInputElts; ++I) {
      const unsigned AccIdx = I % NumAccElts;
      SDValue LHSElt = Ops[1].getOperand(I);
      SDValue RHSElt = Ops[2].getOperand(I);
      if (LHSElt.getOpcode() == ISD::POISON ||
          RHSElt.getOpcode() == ISD::POISON) {
        PoisonElts.set(AccIdx);
        continue;
      }
 
      auto *LHS = dyn_cast<ConstantSDNode>(LHSElt);
      auto *RHS = dyn_cast<ConstantSDNode>(RHSElt);
      if (!LHS || !RHS || LHS->isOpaque() || RHS->isOpaque())
        return SDValue();
 
      APInt LHSVal = LHS->getAPIntValue().trunc(InputEltBits);
      APInt RHSVal = RHS->getAPIntValue().trunc(InputEltBits);
      LHSVal = IsLHSSigned ? LHSVal.sext(AccEltBits) : LHSVal.zext(AccEltBits);
      RHSVal = IsRHSSigned ? RHSVal.sext(AccEltBits) : RHSVal.zext(AccEltBits);
      Results[AccIdx] += LHSVal * RHSVal;
    }
 
    // After type legalization the vector element type may not be a legal
    // scalar type (e.g. i16 on AArch64). Create the folded constants in the
    // promoted legal scalar type instead, matching the generic per-lane path
    // below. Bail out if legalization would narrow the type, since the lane
    // value would not fit.
    EVT AccEltVT = VT.getVectorElementType();
    EVT LegalSVT = AccEltVT;
    if (NewNodesMustHaveLegalTypes && LegalSVT.isInteger()) {
      LegalSVT = TLI->getTypeToTransformTo(*getContext(), LegalSVT);
      if (LegalSVT.bitsLT(AccEltVT))
        return SDValue();
    }
 
    SmallVector<SDValue, 8> ResultOps;
    for (unsigned I = 0; I != NumAccElts; ++I)
      ResultOps.push_back(
          PoisonElts[I] ? getPOISON(LegalSVT)
                        : getConstant(Results[I].sext(LegalSVT.getSizeInBits()),
                                      DL, LegalSVT));
    return getBuildVector(VT, DL, ResultOps);
  }
 
  ElementCount NumElts = VT.getVectorElementCount();
 
  // See if we can fold through any bitcasted integer ops.
  if (NumOps == 2 && VT.isFixedLengthVector() && VT.isInteger() &&
      Ops[0].getValueType() == VT && Ops[1].getValueType() == VT &&
      (Ops[0].getOpcode() == ISD::BITCAST ||
       Ops[1].getOpcode() == ISD::BITCAST)) {
    SDValue N1 = peekThroughBitcasts(Ops[0]);
    SDValue N2 = peekThroughBitcasts(Ops[1]);
    auto *BV1 = dyn_cast<BuildVectorSDNode>(N1);
    auto *BV2 = dyn_cast<BuildVectorSDNode>(N2);
    if (BV1 && BV2 && N1.getValueType().isInteger() &&
        N2.getValueType().isInteger()) {
      bool IsLE = getDataLayout().isLittleEndian();
      unsigned EltBits = VT.getScalarSizeInBits();
      SmallVector<APInt> RawBits1, RawBits2;
      BitVector UndefElts1, UndefElts2;
      if (BV1->getConstantRawBits(IsLE, EltBits, RawBits1, UndefElts1) &&
          BV2->getConstantRawBits(IsLE, EltBits, RawBits2, UndefElts2)) {
        SmallVector<APInt> RawBits;
        for (unsigned I = 0, E = NumElts.getFixedValue(); I != E; ++I) {
          std::optional<APInt> Fold = FoldValueWithUndef(
              Opcode, RawBits1[I], UndefElts1[I], RawBits2[I], UndefElts2[I]);
          if (!Fold)
            break;
          RawBits.push_back(*Fold);
        }
        if (RawBits.size() == NumElts.getFixedValue()) {
          // We have constant folded, but we might need to cast this again back
          // to the original (possibly legalized) type.
          EVT BVVT, BVEltVT;
          if (N1.getValueType() == VT) {
            BVVT = N1.getValueType();
            BVEltVT = BV1->getOperand(0).getValueType();
          } else {
            BVVT = N2.getValueType();
            BVEltVT = BV2->getOperand(0).getValueType();
          }
          unsigned BVEltBits = BVEltVT.getSizeInBits();
          SmallVector<APInt> DstBits;
          BitVector DstUndefs;
          BuildVectorSDNode::recastRawBits(IsLE, BVVT.getScalarSizeInBits(),
                                           DstBits, RawBits, DstUndefs,
                                           BitVector(RawBits.size(), false));
          SmallVector<SDValue> Ops(DstBits.size(), getUNDEF(BVEltVT));
          for (unsigned I = 0, E = DstBits.size(); I != E; ++I) {
            if (DstUndefs[I])
              continue;
            Ops[I] = getConstant(DstBits[I].sext(BVEltBits), DL, BVEltVT);
          }
          return getBitcast(VT, getBuildVector(BVVT, DL, Ops));
        }
      }
    }
    // Logic ops can be folded from raw integer bits - mainly for AVX512 masks.
    if (ISD::isBitwiseLogicOp(Opcode) && isa<ConstantSDNode>(N1) &&
        isa<ConstantSDNode>(N2)) {
      if (SDValue Res = FoldConstantArithmetic(Opcode, DL, N1.getValueType(),
                                               {N1, N2}, Flags))
        return getBitcast(VT, Res);
    }
  }
 
  // Fold (mul step_vector(C0), C1) to (step_vector(C0 * C1)).
  //      (shl step_vector(C0), C1) -> (step_vector(C0 << C1))
  if ((Opcode == ISD::MUL || Opcode == ISD::SHL) &&
      Ops[0].getOpcode() == ISD::STEP_VECTOR) {
    APInt RHSVal;
    if (ISD::isConstantSplatVector(Ops[1].getNode(), RHSVal)) {
      APInt NewStep = Opcode == ISD::MUL
                          ? Ops[0].getConstantOperandAPInt(0) * RHSVal
                          : Ops[0].getConstantOperandAPInt(0) << RHSVal;
      return getStepVector(DL, VT, NewStep);
    }
  }
 
  auto IsScalarOrSameVectorSize = [NumElts](const SDValue &Op) {
    return !Op.getValueType().isVector() ||
           Op.getValueType().getVectorElementCount() == NumElts;
  };
 
  auto IsBuildVectorSplatVectorOrUndef = [](const SDValue &Op) {
    return Op.isUndef() || Op.getOpcode() == ISD::CONDCODE ||
           Op.getOpcode() == ISD::BUILD_VECTOR ||
           Op.getOpcode() == ISD::SPLAT_VECTOR;
  };
 
  // All operands must be vector types with the same number of elements as
  // the result type and must be either UNDEF or a build/splat vector
  // or UNDEF scalars.
  if (!llvm::all_of(Ops, IsBuildVectorSplatVectorOrUndef) ||
      !llvm::all_of(Ops, IsScalarOrSameVectorSize))
    return SDValue();
 
  // If we are comparing vectors, then the result needs to be a i1 boolean that
  // is then extended back to the legal result type depending on how booleans
  // are represented.
  EVT SVT = (Opcode == ISD::SETCC ? MVT::i1 : VT.getScalarType());
  ISD::NodeType ExtendCode =
      (Opcode == ISD::SETCC && SVT != VT.getScalarType())
          ? TargetLowering::getExtendForContent(TLI->getBooleanContents(VT))
          : ISD::SIGN_EXTEND;
 
  // Find legal integer scalar type for constant promotion and
  // ensure that its scalar size is at least as large as source.
  EVT LegalSVT = VT.getScalarType();
  if (NewNodesMustHaveLegalTypes && LegalSVT.isInteger()) {
    LegalSVT = TLI->getTypeToTransformTo(*getContext(), LegalSVT);
    if (LegalSVT.bitsLT(VT.getScalarType()))
      return SDValue();
  }
 
  // For scalable vector types we know we're dealing with SPLAT_VECTORs. We
  // only have one operand to check. For fixed-length vector types we may have
  // a combination of BUILD_VECTOR and SPLAT_VECTOR.
  unsigned NumVectorElts = NumElts.isScalable() ? 1 : NumElts.getFixedValue();
 
  // Constant fold each scalar lane separately.
  SmallVector<SDValue, 4> ScalarResults;
  for (unsigned I = 0; I != NumVectorElts; I++) {
    SmallVector<SDValue, 4> ScalarOps;
    for (SDValue Op : Ops) {
      EVT InSVT = Op.getValueType().getScalarType();
      if (Op.getOpcode() != ISD::BUILD_VECTOR &&
          Op.getOpcode() != ISD::SPLAT_VECTOR) {
        if (Op.isUndef())
          ScalarOps.push_back(getUNDEF(InSVT));
        else
          ScalarOps.push_back(Op);
        continue;
      }
 
      SDValue ScalarOp =
          Op.getOperand(Op.getOpcode() == ISD::SPLAT_VECTOR ? 0 : I);
      EVT ScalarVT = ScalarOp.getValueType();
 
      // Build vector (integer) scalar operands may need implicit
      // truncation - do this before constant folding.
      if (ScalarVT.isInteger() && ScalarVT.bitsGT(InSVT)) {
        // Don't create illegally-typed nodes unless they're constants or undef
        // - if we fail to constant fold we can't guarantee the (dead) nodes
        // we're creating will be cleaned up before being visited for
        // legalization.
        if (NewNodesMustHaveLegalTypes && !ScalarOp.isUndef() &&
            !isa<ConstantSDNode>(ScalarOp) &&
            TLI->getTypeAction(*getContext(), InSVT) !=
                TargetLowering::TypeLegal)
          return SDValue();
        ScalarOp = getNode(ISD::TRUNCATE, DL, InSVT, ScalarOp);
      }
 
      ScalarOps.push_back(ScalarOp);
    }
 
    // Constant fold the scalar operands.
    SDValue ScalarResult = getNode(Opcode, DL, SVT, ScalarOps, Flags);
 
    // Scalar folding only succeeded if the result is a constant or UNDEF.
    if (!ScalarResult.isUndef() && ScalarResult.getOpcode() != ISD::Constant &&
        ScalarResult.getOpcode() != ISD::ConstantFP)
      return SDValue();
 
    // Legalize the (integer) scalar constant if necessary. We only do
    // this once we know the folding succeeded, since otherwise we would
    // get a node with illegal type which has a user.
    if (LegalSVT != SVT)
      ScalarResult = getNode(ExtendCode, DL, LegalSVT, ScalarResult);
 
    ScalarResults.push_back(ScalarResult);
  }
 
  SDValue V = NumElts.isScalable() ? getSplatVector(VT, DL, ScalarResults[0])
                                   : getBuildVector(VT, DL, ScalarResults);
  NewSDValueDbgMsg(V, "New node fold constant vector: ", this);
  return V;
}
 
SDValue SelectionDAG::foldConstantFPMath(unsigned Opcode, const SDLoc &DL,
                                         EVT VT, ArrayRef<SDValue> Ops) {
  // TODO: Add support for unary/ternary fp opcodes.
  if (Ops.size() != 2)
    return SDValue();
 
  // TODO: We don't do any constant folding for strict FP opcodes here, but we
  //       should. That will require dealing with a potentially non-default
  //       rounding mode, checking the "opStatus" return value from the APFloat
  //       math calculations, and possibly other variations.
  SDValue N1 = Ops[0];
  SDValue N2 = Ops[1];
  ConstantFPSDNode *N1CFP = isConstOrConstSplatFP(N1, /*AllowUndefs*/ false);
  ConstantFPSDNode *N2CFP = isConstOrConstSplatFP(N2, /*AllowUndefs*/ false);
  if (N1CFP && N2CFP) {
    APFloat C1 = N1CFP->getValueAPF(); // make copy
    const APFloat &C2 = N2CFP->getValueAPF();
    switch (Opcode) {
    case ISD::FADD:
      C1.add(C2, APFloat::rmNearestTiesToEven);
      return getConstantFP(C1, DL, VT);
    case ISD::FSUB:
      C1.subtract(C2, APFloat::rmNearestTiesToEven);
      return getConstantFP(C1, DL, VT);
    case ISD::FMUL:
      C1.multiply(C2, APFloat::rmNearestTiesToEven);
      return getConstantFP(C1, DL, VT);
    case ISD::FDIV:
      C1.divide(C2, APFloat::rmNearestTiesToEven);
      return getConstantFP(C1, DL, VT);
    case ISD::FREM:
      C1.mod(C2);
      return getConstantFP(C1, DL, VT);
    case ISD::FCOPYSIGN:
      C1.copySign(C2);
      return getConstantFP(C1, DL, VT);
    case ISD::FMINNUM:
      return getConstantFP(minnum(C1, C2), DL, VT);
    case ISD::FMAXNUM:
      return getConstantFP(maxnum(C1, C2), DL, VT);
    case ISD::FMINIMUM:
      return getConstantFP(minimum(C1, C2), DL, VT);
    case ISD::FMAXIMUM:
      return getConstantFP(maximum(C1, C2), DL, VT);
    case ISD::FMINIMUMNUM:
      return getConstantFP(minimumnum(C1, C2), DL, VT);
    case ISD::FMAXIMUMNUM:
      return getConstantFP(maximumnum(C1, C2), DL, VT);
    default: break;
    }
  }
  if (N1CFP && Opcode == ISD::FP_ROUND) {
    APFloat C1 = N1CFP->getValueAPF();    // make copy
    bool Unused;
    // This can return overflow, underflow, or inexact; we don't care.
    // FIXME need to be more flexible about rounding mode.
    (void)C1.convert(VT.getFltSemantics(), APFloat::rmNearestTiesToEven,
                     &Unused);
    return getConstantFP(C1, DL, VT);
  }
 
  switch (Opcode) {
  case ISD::FSUB:
    // -0.0 - undef --> undef (consistent with "fneg undef")
    if (ConstantFPSDNode *N1C = isConstOrConstSplatFP(N1, /*AllowUndefs*/ true))
      if (N1C && N1C->getValueAPF().isNegZero() && N2.isUndef())
        return getUNDEF(VT);
    [[fallthrough]];
 
  case ISD::FADD:
  case ISD::FMUL:
  case ISD::FDIV:
  case ISD::FREM:
    // If both operands are undef, the result is undef. If 1 operand is undef,
    // the result is NaN. This should match the behavior of the IR optimizer.
    if (N1.isUndef() && N2.isUndef())
      return getUNDEF(VT);
    if (N1.isUndef() || N2.isUndef())
      return getConstantFP(APFloat::getNaN(VT.getFltSemantics()), DL, VT);
  }
  return SDValue();
}
 
SDValue SelectionDAG::FoldConstantBuildVector(BuildVectorSDNode *BV,
                                              const SDLoc &DL, EVT DstEltVT) {
  EVT SrcEltVT = BV->getValueType(0).getVectorElementType();
 
  // If this is already the right type, we're done.
  if (SrcEltVT == DstEltVT)
    return SDValue(BV, 0);
 
  unsigned SrcBitSize = SrcEltVT.getSizeInBits();
  unsigned DstBitSize = DstEltVT.getSizeInBits();
 
  // If this is a conversion of N elements of one type to N elements of another
  // type, convert each element.  This handles FP<->INT cases.
  if (SrcBitSize == DstBitSize) {
    SmallVector<SDValue, 8> Ops;
    for (SDValue Op : BV->op_values()) {
      // If the vector element type is not legal, the BUILD_VECTOR operands
      // are promoted and implicitly truncated.  Make that explicit here.
      if (Op.getValueType() != SrcEltVT)
        Op = getNode(ISD::TRUNCATE, DL, SrcEltVT, Op);
      Ops.push_back(getBitcast(DstEltVT, Op));
    }
    EVT VT = EVT::getVectorVT(*getContext(), DstEltVT,
                              BV->getValueType(0).getVectorNumElements());
    return getBuildVector(VT, DL, Ops);
  }
 
  // Otherwise, we're growing or shrinking the elements.  To avoid having to
  // handle annoying details of growing/shrinking FP values, we convert them to
  // int first.
  if (SrcEltVT.isFloatingPoint()) {
    // Convert the input float vector to a int vector where the elements are the
    // same sizes.
    EVT IntEltVT = EVT::getIntegerVT(*getContext(), SrcEltVT.getSizeInBits());