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/FoldingSet.h"
#include "llvm/ADT/None.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Triple.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Analysis/BlockFrequencyInfo.h"
#include "llvm/Analysis/MemoryLocation.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/ValueTracking.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/RuntimeLibcalls.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/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/IR/Value.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/MachineValueType.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Mutex.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/Utils/SizeOpts.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <limits>
#include <set>
#include <string>
#include <utility>
#include <vector>
 
using namespace llvm;
 
/// 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() {}
 
#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 void NewSDValueDbgMsg(SDValue V, StringRef Msg, SelectionDAG *G) {
  LLVM_DEBUG(dbgs() << Msg; V.getNode()->dump(G););
}
 
//===----------------------------------------------------------------------===//
//                              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(SelectionDAG::EVTToAPFloatSemantics(VT),
                      APFloat::rmNearestTiesToEven,
                      &losesInfo);
  return !losesInfo;
}
 
//===----------------------------------------------------------------------===//
//                              ISD Namespace
//===----------------------------------------------------------------------===//
 
bool ISD::isConstantSplatVector(const SDNode *N, APInt &SplatVal) {
  if (N->getOpcode() == ISD::SPLAT_VECTOR) {
    unsigned EltSize =
        N->getValueType(0).getVectorElementType().getSizeInBits();
    if (auto *Op0 = dyn_cast<ConstantSDNode>(N->getOperand(0))) {
      SplatVal = Op0->getAPIntValue().truncOrSelf(EltSize);
      return true;
    } else if (auto *Op0 = dyn_cast<ConstantFPSDNode>(N->getOperand(0))) {
      SplatVal = Op0->getValueAPF().bitcastToAPInt().truncOrSelf(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();
  return BV->isConstantSplat(SplatVal, SplatUndef, SplatBitSize, HasUndefs,
                             EltSize) &&
         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.isAllOnesValue();
  }
 
  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);
  unsigned EltSize = N->getValueType(0).getScalarSizeInBits();
  if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(NotZero)) {
    if (CN->getAPIntValue().countTrailingOnes() < EltSize)
      return false;
  } else if (ConstantFPSDNode *CFPN = dyn_cast<ConstantFPSDNode>(NotZero)) {
    if (CFPN->getValueAPF().bitcastToAPInt().countTrailingOnes() < 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.isNullValue();
  }
 
  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.
    unsigned EltSize = N->getValueType(0).getScalarSizeInBits();
    if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(Op)) {
      if (CN->getAPIntValue().countTrailingZeros() < EltSize)
        return false;
    } else if (ConstantFPSDNode *CFPN = dyn_cast<ConstantFPSDNode>(Op)) {
      if (CFPN->getValueAPF().bitcastToAPInt().countTrailingZeros() < 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::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::matchUnaryPredicate(SDValue Op,
                              std::function<bool(ConstantSDNode *)> Match,
                              bool AllowUndefs) {
  // FIXME: Add support for scalar UNDEF cases?
  if (auto *Cst = dyn_cast<ConstantSDNode>(Op))
    return Match(Cst);
 
  // FIXME: Add support for vector UNDEF cases?
  if (ISD::BUILD_VECTOR != Op.getOpcode() &&
      ISD::SPLAT_VECTOR != Op.getOpcode())
    return false;
 
  EVT SVT = Op.getValueType().getScalarType();
  for (unsigned i = 0, e = Op.getNumOperands(); i != e; ++i) {
    if (AllowUndefs && Op.getOperand(i).isUndef()) {
      if (!Match(nullptr))
        return false;
      continue;
    }
 
    auto *Cst = dyn_cast<ConstantSDNode>(Op.getOperand(i));
    if (!Cst || Cst->getValueType(0) != SVT || !Match(Cst))
      return false;
  }
  return true;
}
 
bool ISD::matchBinaryPredicate(
    SDValue LHS, SDValue RHS,
    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 (ISD::BUILD_VECTOR != LHS.getOpcode() ||
      ISD::BUILD_VECTOR != RHS.getOpcode())
    return false;
 
  EVT SVT = LHS.getValueType().getScalarType();
  for (unsigned i = 0, e = LHS.getNumOperands(); i != e; ++i) {
    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::getVecReduceBaseOpcode(unsigned VecReduceOpcode) {
  switch (VecReduceOpcode) {
  default:
    llvm_unreachable("Expected VECREDUCE opcode");
  case ISD::VECREDUCE_FADD:
  case ISD::VECREDUCE_SEQ_FADD:
    return ISD::FADD;
  case ISD::VECREDUCE_FMUL:
  case ISD::VECREDUCE_SEQ_FMUL:
    return ISD::FMUL;
  case ISD::VECREDUCE_ADD:
    return ISD::ADD;
  case ISD::VECREDUCE_MUL:
    return ISD::MUL;
  case ISD::VECREDUCE_AND:
    return ISD::AND;
  case ISD::VECREDUCE_OR:
    return ISD::OR;
  case ISD::VECREDUCE_XOR:
    return ISD::XOR;
  case ISD::VECREDUCE_SMAX:
    return ISD::SMAX;
  case ISD::VECREDUCE_SMIN:
    return ISD::SMIN;
  case ISD::VECREDUCE_UMAX:
    return ISD::UMAX;
  case ISD::VECREDUCE_UMIN:
    return ISD::UMIN;
  case ISD::VECREDUCE_FMAX:
    return ISD::FMAXNUM;
  case ISD::VECREDUCE_FMIN:
    return ISD::FMINNUM;
  }
}
 
bool ISD::isVPOpcode(unsigned Opcode) {
  switch (Opcode) {
  default:
    return false;
#define BEGIN_REGISTER_VP_SDNODE(SDOPC, ...)                                   \
  case ISD::SDOPC:                                                             \
    return true;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
/// The operand position of the vector mask.
Optional<unsigned> ISD::getVPMaskIdx(unsigned Opcode) {
  switch (Opcode) {
  default:
    return None;
#define BEGIN_REGISTER_VP_SDNODE(SDOPC, LEGALPOS, TDNAME, MASKPOS, ...)        \
  case ISD::SDOPC:                                                             \
    return MASKPOS;
#include "llvm/IR/VPIntrinsics.def"
  }
}
 
/// The operand position of the explicit vector length parameter.
Optional<unsigned> ISD::getVPExplicitVectorLengthIdx(unsigned Opcode) {
  switch (Opcode) {
  default:
    return None;
#define BEGIN_REGISTER_VP_SDNODE(SDOPC, LEGALPOS, TDNAME, MASKPOS, EVLPOS)     \
  case ISD::SDOPC:                                                             \
    return EVLPOS;
#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 (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 (auto& Op : Ops) {
    ID.AddPointer(Op.getNode());
    ID.AddInteger(Op.getResNo());
  }
}
 
static void AddNodeIDNode(FoldingSetNodeID &ID, unsigned short 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());
    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::LIFETIME_START:
  case ISD::LIFETIME_END:
    if (cast<LifetimeSDNode>(N)->hasOffset()) {
      ID.AddInteger(cast<LifetimeSDNode>(N)->getSize());
      ID.AddInteger(cast<LifetimeSDNode>(N)->getOffset());
    }
    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());
    break;
  }
  case ISD::STORE: {
    const StoreSDNode *ST = cast<StoreSDNode>(N);
    ID.AddInteger(ST->getMemoryVT().getRawBits());
    ID.AddInteger(ST->getRawSubclassData());
    ID.AddInteger(ST->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::MLOAD: {
    const MaskedLoadSDNode *MLD = cast<MaskedLoadSDNode>(N);
    ID.AddInteger(MLD->getMemoryVT().getRawBits());
    ID.AddInteger(MLD->getRawSubclassData());
    ID.AddInteger(MLD->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::MSTORE: {
    const MaskedStoreSDNode *MST = cast<MaskedStoreSDNode>(N);
    ID.AddInteger(MST->getMemoryVT().getRawBits());
    ID.AddInteger(MST->getRawSubclassData());
    ID.AddInteger(MST->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::MGATHER: {
    const MaskedGatherSDNode *MG = cast<MaskedGatherSDNode>(N);
    ID.AddInteger(MG->getMemoryVT().getRawBits());
    ID.AddInteger(MG->getRawSubclassData());
    ID.AddInteger(MG->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::MSCATTER: {
    const MaskedScatterSDNode *MS = cast<MaskedScatterSDNode>(N);
    ID.AddInteger(MS->getMemoryVT().getRawBits());
    ID.AddInteger(MS->getRawSubclassData());
    ID.AddInteger(MS->getPointerInfo().getAddrSpace());
    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());
    break;
  }
  case ISD::PREFETCH: {
    const MemSDNode *PF = cast<MemSDNode>(N);
    ID.AddInteger(PF->getPointerInfo().getAddrSpace());
    break;
  }
  case ISD::VECTOR_SHUFFLE: {
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(N);
    for (unsigned i = 0, e = N->getValueType(0).getVectorNumElements();
         i != e; ++i)
      ID.AddInteger(SVN->getMaskElt(i));
    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;
  }
  } // end switch (N->getOpcode())
 
  // Target specific memory nodes could also have address spaces to check.
  if (N->isTargetMemoryOpcode())
    ID.AddInteger(cast<MemSDNode>(N)->getPointerInfo().getAddrSpace());
}
 
/// 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 flag.
 
  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 flag.
 
  return false;
}
 
/// 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);
}
 
#ifndef NDEBUG
/// VerifySDNode - Sanity check the given SDNode.  Aborts if it is invalid.
static void VerifySDNode(SDNode *N) {
  switch (N->getOpcode()) {
  default:
    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;
  }
  }
}
#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++;
  VerifySDNode(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.RemoveNode(N);
    break;
  }
#ifndef NDEBUG
  // Verify that the node was actually in one of the CSE maps, unless it has a
  // flag 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.GetOrInsertNode(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.
      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,
                                           void *&InsertPos) {
  if (doNotCSE(N))
    return nullptr;
 
  SDValue Ops[] = { Op };
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = FindNodeOrInsertPos(ID, SDLoc(N), InsertPos);
  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,
                                           void *&InsertPos) {
  if (doNotCSE(N))
    return nullptr;
 
  SDValue Ops[] = { Op1, Op2 };
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = FindNodeOrInsertPos(ID, SDLoc(N), InsertPos);
  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,
                                           void *&InsertPos) {
  if (doNotCSE(N))
    return nullptr;
 
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, N->getOpcode(), N->getVTList(), Ops);
  AddNodeIDCustom(ID, N);
  SDNode *Node = FindNodeOrInsertPos(ID, SDLoc(N), InsertPos);
  if (Node)
    Node->intersectFlagsWith(N->getFlags());
  return Node;
}
 
Align SelectionDAG::getEVTAlign(EVT VT) const {
  Type *Ty = VT == MVT::iPTR ?
                   PointerType::get(Type::getInt8Ty(*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, CodeGenOpt::Level OL)
    : TM(tm), OptLevel(OL),
      EntryNode(ISD::EntryToken, 0, DebugLoc(), getVTList(MVT::Other)),
      Root(getEntryNode()) {
  InsertNode(&EntryNode);
  DbgInfo = new SDDbgInfo();
}
 
void SelectionDAG::init(MachineFunction &NewMF,
                        OptimizationRemarkEmitter &NewORE,
                        Pass *PassPtr, const TargetLibraryInfo *LibraryInfo,
                        LegacyDivergenceAnalysis * Divergence,
                        ProfileSummaryInfo *PSIin,
                        BlockFrequencyInfo *BFIin) {
  MF = &NewMF;
  SDAGISelPass = PassPtr;
  ORE = &NewORE;
  TLI = getSubtarget().getTargetLowering();
  TSI = getSubtarget().getSelectionDAGInfo();
  LibInfo = LibraryInfo;
  Context = &MF->getFunction().getContext();
  DA = Divergence;
  PSI = PSIin;
  BFI = BFIin;
}
 
SelectionDAG::~SelectionDAG() {
  assert(!UpdateListeners && "Dangling registered DAGUpdateListeners");
  allnodes_clear();
  OperandRecycler.clear(OperandAllocator);
  delete DbgInfo;
}
 
bool SelectionDAG::shouldOptForSize() const {
  return MF->getFunction().hasOptSize() ||
      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::FindNodeOrInsertPos(const FoldingSetNodeID &ID,
                                          void *&InsertPos) {
  SDNode *N = CSEMap.FindNodeOrInsertPos(ID, InsertPos);
  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::FindNodeOrInsertPos(const FoldingSetNodeID &ID,
                                          const SDLoc &DL, void *&InsertPos) {
  SDNode *N = CSEMap.FindNodeOrInsertPos(ID, InsertPos);
  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();
  SDCallSiteDbgInfo.clear();
  std::fill(CondCodeNodes.begin(), CondCodeNodes.end(),
            static_cast<CondCodeSDNode*>(nullptr));
  std::fill(ValueTypeNodes.begin(), ValueTypeNodes.end(),
            static_cast<SDNode*>(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));
}
 
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)});
 
  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::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.bitsLE(OpVT) && "Not extending!");
  if (OpVT == VT)
    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);
}
 
/// getNOT - Create a bitwise NOT operation as (XOR Val, -1).
SDValue SelectionDAG::getNOT(const SDLoc &DL, SDValue Val, EVT VT) {
  EVT EltVT = VT.getScalarType();
  SDValue NegOne =
    getConstant(APInt::getAllOnesValue(EltVT.getSizeInBits()), DL, VT);
  return getNode(ISD::XOR, DL, VT, Val, NegOne);
}
 
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) {
  EVT EltVT = VT.getScalarType();
  assert((EltVT.getSizeInBits() >= 64 ||
          (uint64_t)((int64_t)Val >> EltVT.getSizeInBits()) + 1 < 2) &&
         "getConstant with a uint64_t value that doesn't fit in the type!");
  return getConstant(APInt(EltVT.getSizeInBits(), Val), 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;
 
  // 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 = 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()) {
      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.lshr(i * ViaEltSizeInBits).trunc(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.lshr(i * ViaEltSizeInBits).zextOrTrunc(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;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(EltVT), None);
  ID.AddPointer(Elt);
  ID.AddBoolean(isO);
  void *IP = nullptr;
  SDNode *N = nullptr;
  if ((N = FindNodeOrInsertPos(ID, DL, IP)))
    if (!VT.isVector())
      return SDValue(N, 0);
 
  if (!N) {
    N = newSDNode<ConstantSDNode>(isT, isO, Elt, EltVT);
    CSEMap.InsertNode(N, IP);
    InsertNode(N);
    NewSDValueDbgMsg(SDValue(N, 0), "Creating constant: ", this);
  }
 
  SDValue Result(N, 0);
  if (VT.isScalableVector())
    Result = getSplatVector(VT, DL, Result);
  else if (VT.isVector())
    Result = getSplatBuildVector(VT, DL, Result);
 
  return Result;
}
 
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, bool LegalTypes) {
  assert(VT.isInteger() && "Shift amount is not an integer type!");
  EVT ShiftVT = TLI->getShiftAmountTy(VT, getDataLayout(), LegalTypes);
  return getConstant(Val, DL, ShiftVT);
}
 
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();
 
  // 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;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(EltVT), None);
  ID.AddPointer(&V);
  void *IP = nullptr;
  SDNode *N = nullptr;
  if ((N = FindNodeOrInsertPos(ID, DL, IP)))
    if (!VT.isVector())
      return SDValue(N, 0);
 
  if (!N) {
    N = newSDNode<ConstantFPSDNode>(isTarget, &V, EltVT);
    CSEMap.InsertNode(N, IP);
    InsertNode(N);
  }
 
  SDValue Result(N, 0);
  if (VT.isScalableVector())
    Result = getSplatVector(VT, DL, Result);
  else if (VT.isVector())
    Result = getSplatBuildVector(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);
  else if (EltVT == MVT::f64)
    return getConstantFP(APFloat(Val), DL, VT, isTarget);
  else if (EltVT == MVT::f80 || EltVT == MVT::f128 || EltVT == MVT::ppcf128 ||
           EltVT == MVT::f16 || EltVT == MVT::bf16) {
    bool Ignored;
    APFloat APF = APFloat(Val);
    APF.convert(EVTToAPFloatSemantics(EltVT), APFloat::rmNearestTiesToEven,
                &Ignored);
    return getConstantFP(APF, DL, VT, isTarget);
  } else
    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;
 
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddPointer(GV);
  ID.AddInteger(Offset);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, DL, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<GlobalAddressSDNode>(
      Opc, DL.getIROrder(), DL.getDebugLoc(), GV, VT, Offset, TargetFlags);
  CSEMap.InsertNode(N, IP);
    InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getFrameIndex(int FI, EVT VT, bool isTarget) {
  unsigned Opc = isTarget ? ISD::TargetFrameIndex : ISD::FrameIndex;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddInteger(FI);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<FrameIndexSDNode>(FI, VT, isTarget);
  CSEMap.InsertNode(N, IP);
  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;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddInteger(JTI);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<JumpTableSDNode>(JTI, VT, isTarget, TargetFlags);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
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;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddInteger(Alignment->value());
  ID.AddInteger(Offset);
  ID.AddPointer(C);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<ConstantPoolSDNode>(isTarget, C, VT, Offset, *Alignment,
                                          TargetFlags);
  CSEMap.InsertNode(N, IP);
  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;
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddInteger(Alignment->value());
  ID.AddInteger(Offset);
  C->addSelectionDAGCSEId(ID);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<ConstantPoolSDNode>(isTarget, C, VT, Offset, *Alignment,
                                          TargetFlags);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getTargetIndex(int Index, EVT VT, int64_t Offset,
                                     unsigned TargetFlags) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::TargetIndex, getVTList(VT), None);
  ID.AddInteger(Index);
  ID.AddInteger(Offset);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<TargetIndexSDNode>(Index, VT, Offset, TargetFlags);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getBasicBlock(MachineBasicBlock *MBB) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::BasicBlock, getVTList(MVT::Other), None);
  ID.AddPointer(MBB);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<BasicBlockSDNode>(MBB);
  CSEMap.InsertNode(N, IP);
  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, VT);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getMCSymbol(MCSymbol *Sym, EVT VT) {
  SDNode *&N = MCSymbols[Sym];
  if (N)
    return SDValue(N, 0);
  N = newSDNode<MCSymbolSDNode>(Sym, 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, VT);
  InsertNode(N);
  return SDValue(N, 0);
}
 
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::getStepVector(const SDLoc &DL, EVT ResVT, SDValue Step) {
  if (ResVT.isScalableVector())
    return getNode(ISD::STEP_VECTOR, DL, ResVT, Step);
 
  EVT OpVT = Step.getValueType();
  APInt StepVal = cast<ConstantSDNode>(Step)->getAPIntValue();
  SmallVector<SDValue, 16> OpsStepConstants;
  for (uint64_t i = 0; i < ResVT.getVectorNumElements(); i++)
    OpsStepConstants.push_back(getConstant(StepVal * i, DL, OpVT));
  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())
    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.begin(), Mask.end());
 
  // Canonicalize shuffle v, v -> v, undef
  if (N1 == N2) {
    N2 = getUNDEF(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, undef
  // Canonicalize all index into rhs, -> shuffle rhs, undef
  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 getUNDEF(VT);
  if (AllLHS && !N2Undef)
    N2 = getUNDEF(VT);
  if (AllRHS) {
    N1 = getUNDEF(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)
    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 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)
          return N1;
        if (auto *C = dyn_cast<ConstantSDNode>(Splat))
          if (C->isNullValue())
            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;
      }
    }
  }
 
  FoldingSetNodeID ID;
  SDValue Ops[2] = { N1, N2 };
  AddNodeIDNode(ID, ISD::VECTOR_SHUFFLE, getVTList(VT), Ops);
  for (int i = 0; i != NElts; ++i)
    ID.AddInteger(MaskVec[i]);
 
  void* IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, dl, IP))
    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>(VT, dl.getIROrder(),
                                           dl.getDebugLoc(), MaskAlloc);
  createOperands(N, Ops);
 
  CSEMap.InsertNode(N, IP);
  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().begin(), SV.getMask().end());
  ShuffleVectorSDNode::commuteMask(MaskVec);
 
  SDValue Op0 = SV.getOperand(0);
  SDValue Op1 = SV.getOperand(1);
  return getVectorShuffle(VT, SDLoc(&SV), Op1, Op0, MaskVec);
}
 
SDValue SelectionDAG::getRegister(unsigned RegNo, EVT VT) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::Register, getVTList(VT), None);
  ID.AddInteger(RegNo);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<RegisterSDNode>(RegNo, VT);
  N->SDNodeBits.IsDivergent = TLI->isSDNodeSourceOfDivergence(N, FLI, DA);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getRegisterMask(const uint32_t *RegMask) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::RegisterMask, getVTList(MVT::Untyped), None);
  ID.AddPointer(RegMask);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<RegisterMaskSDNode>(RegMask);
  CSEMap.InsertNode(N, IP);
  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);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N =
      newSDNode<LabelSDNode>(Opcode, dl.getIROrder(), dl.getDebugLoc(), Label);
  createOperands(N, Ops);
 
  CSEMap.InsertNode(N, IP);
  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;
 
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, Opc, getVTList(VT), None);
  ID.AddPointer(BA);
  ID.AddInteger(Offset);
  ID.AddInteger(TargetFlags);
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<BlockAddressSDNode>(Opc, VT, BA, Offset, TargetFlags);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getSrcValue(const Value *V) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::SRCVALUE, getVTList(MVT::Other), None);
  ID.AddPointer(V);
 
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<SrcValueSDNode>(V);
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getMDNode(const MDNode *MD) {
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::MDNODE_SDNODE, getVTList(MVT::Other), None);
  ID.AddPointer(MD);
 
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<MDNodeSDNode>(MD);
  CSEMap.InsertNode(N, IP);
  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) {
  SDValue Ops[] = {Ptr};
  FoldingSetNodeID ID;
  AddNodeIDNode(ID, ISD::ADDRSPACECAST, getVTList(VT), Ops);
  ID.AddInteger(SrcAS);
  ID.AddInteger(DestAS);
 
  void *IP = nullptr;
  if (SDNode *E = FindNodeOrInsertPos(ID, dl, IP))
    return SDValue(E, 0);
 
  auto *N = newSDNode<AddrSpaceCastSDNode>(dl.getIROrder(), dl.getDebugLoc(),
                                           VT, SrcAS, DestAS);
  createOperands(N, Ops);
 
  CSEMap.InsertNode(N, IP);
  InsertNode(N);
  return SDValue(N, 0);
}
 
SDValue SelectionDAG::getFreeze(SDValue V) {
  return getNode(ISD::FREEZE, SDLoc(V), V.getValueType(), 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,
                getConstant(-(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;
  }
 
  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.getKnownMinSize(), 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.getKnownMinSize() > VT2Size.getKnownMinSize() ? 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) {
  EVT OpVT = N1.getValueType();
 
  // 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 getUNDEF(VT);
 
    // If both operands are undef, we can return undef for int comparison.
    // icmp undef, undef -> undef.
    if (N1.isUndef() && N2.isUndef())
      return getUNDEF(VT);
 
    // icmp X, X -> true/false
    // icmp X, undef -> true/false because undef could be X.
    if (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();
 
      switch (Cond) {
      default: llvm_unreachable("Unknown integer setcc!");
      case ISD::SETEQ:  return getBoolConstant(C1 == C2, dl, VT, OpVT);
      case ISD::SETNE:  return getBoolConstant(C1 != C2, dl, VT, OpVT);
      case ISD::SETULT: return getBoolConstant(C1.ult(C2), dl, VT, OpVT);
      case ISD::SETUGT: return getBoolConstant(C1.ugt(C2), dl, VT, OpVT);
      case ISD::SETULE: return getBoolConstant(C1.ule(C2), dl, VT, OpVT);
      case ISD::SETUGE: return getBoolConstant(C1.uge(C2), dl, VT, OpVT);
      case ISD::SETLT:  return getBoolConstant(C1.slt(C2), dl, VT, OpVT);
      case ISD::SETGT:  return getBoolConstant(C1.sgt(C2), dl, VT, OpVT);
      case ISD::SETLE:  return getBoolConstant(C1.sle(C2), dl, VT, OpVT);
      case ISD::SETGE:  return getBoolConstant(C1.sge(C2), 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 getUNDEF(VT);
                      LLVM_FALLTHROUGH;
    case ISD::SETOEQ: return getBoolConstant(R==APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETNE:  if (R==APFloat::cmpUnordered)
                        return getUNDEF(VT);
                      LLVM_FALLTHROUGH;
    case ISD::SETONE: return getBoolConstant(R==APFloat::cmpGreaterThan ||
                                             R==APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    case ISD::SETLT:  if (R==APFloat::cmpUnordered)
                        return getUNDEF(VT);
                      LLVM_FALLTHROUGH;
    case ISD::SETOLT: return getBoolConstant(R==APFloat::cmpLessThan, dl, VT,
                                             OpVT);
    case ISD::SETGT:  if (R==APFloat::cmpUnordered)
                        return getUNDEF(VT);
                      LLVM_FALLTHROUGH;
    case ISD::SETOGT: return getBoolConstant(R==APFloat::cmpGreaterThan, dl,
                                             VT, OpVT);
    case ISD::SETLE:  if (R==APFloat::cmpUnordered)
                        return getUNDEF(VT);
                      LLVM_FALLTHROUGH;
    case ISD::SETOLE: return getBoolConstant(R==APFloat::cmpLessThan ||
                                             R==APFloat::cmpEqual, dl, VT,
                                             OpVT);
    case ISD::SETGE:  if (R==APFloat::cmpUnordered)
                        return getUNDEF(VT);
                      LLVM_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);
  } 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 getUNDEF(VT);
    }
  }
 
  // Could not fold it.
  return SDValue();
}
 
/// See if the specified operand can be simplified with the knowledge that only
/// the bits specified by DemandedBits are used.
/// TODO: really we should be making this into the DAG equivalent of
/// SimplifyMultipleUseDemandedBits and not generate any new nodes.
SDValue SelectionDAG::GetDemandedBits(SDValue V, const APInt &DemandedBits) {
  EVT VT = V.getValueType();
 
  if (VT.isScalableVector())
    return SDValue();
 
  APInt DemandedElts = VT.isVector()
                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
                           : APInt(1, 1);
  return GetDemandedBits(V, DemandedBits, DemandedElts);
}
 
/// See if the specified operand can be simplified with the knowledge that only
/// the bits specified by DemandedBits are used in the elements specified by
/// DemandedElts.
/// TODO: really we should be making this into the DAG equivalent of
/// SimplifyMultipleUseDemandedBits and not generate any new nodes.
SDValue SelectionDAG::GetDemandedBits(SDValue V, const APInt &DemandedBits,
                                      const APInt &DemandedElts) {
  switch (V.getOpcode()) {
  default:
    return TLI->SimplifyMultipleUseDemandedBits(V, DemandedBits, DemandedElts,
                                                *this, 0);
  case ISD::Constant: {
    const APInt &CVal = cast<ConstantSDNode>(V)->getAPIntValue();
    APInt NewVal = CVal & DemandedBits;
    if (NewVal != CVal)
      return getConstant(NewVal, SDLoc(V), V.getValueType());
    break;
  }
  case ISD::SRL:
    // Only look at single-use SRLs.
    if (!V.getNode()->hasOneUse())
      break;
    if (auto *RHSC = dyn_cast<ConstantSDNode>(V.getOperand(1))) {
      // See if we can recursively simplify the LHS.
      unsigned Amt = RHSC->getZExtValue();
 
      // Watch out for shift count overflow though.
      if (Amt >= DemandedBits.getBitWidth())
        break;
      APInt SrcDemandedBits = DemandedBits << Amt;
      if (SDValue SimplifyLHS =
              GetDemandedBits(V.getOperand(0), SrcDemandedBits))
        return getNode(ISD::SRL, SDLoc(V), V.getValueType(), SimplifyLHS,
                       V.getOperand(1));
    }
    break;
  }
  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);
}
 
/// 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);
}
 
/// 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);
}
 
/// isSplatValue - Return true if the vector V has the same value
/// across all DemandedElts. For scalable vectors it does not make
/// sense to specify which elements are demanded or undefined, therefore
/// they are simply ignored.
bool SelectionDAG::isSplatValue(SDValue V, const APInt &DemandedElts,
                                APInt &UndefElts, unsigned Depth) {
  EVT VT = V.getValueType();
  assert(VT.isVector() && "Vector type expected");
 
  if (!VT.isScalableVector() && !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 (V.getOpcode()) {
  case ISD::SPLAT_VECTOR:
    UndefElts = V.getOperand(0).isUndef()
                    ? APInt::getAllOnesValue(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);
    if (isSplatValue(LHS, DemandedElts, UndefLHS, Depth + 1) &&
        isSplatValue(RHS, DemandedElts, UndefRHS, Depth + 1)) {
      UndefElts = UndefLHS | UndefRHS;
      return true;
    }
    return false;
  }
  case ISD::ABS:
  case ISD::TRUNCATE:
  case ISD::SIGN_EXTEND:
  case ISD::ZERO_EXTEND:
    return isSplatValue(V.getOperand(0), DemandedElts, UndefElts, Depth + 1);
  }
 
  // 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::getNullValue(NumElts);
 
  switch (V.getOpcode()) {
  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.
    // TODO: Do we need to handle shuffle(splat, undef, mask)?
    int SplatIndex = -1;
    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 (0 <= SplatIndex && SplatIndex != M)
        return false;
      SplatIndex = M;
    }
    return true;
  }
  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.zextOrSelf(NumSrcElts).shl(Idx);
    if (isSplatValue(Src, DemandedSrcElts, UndefSrcElts, Depth + 1)) {
      UndefElts = UndefSrcElts.extractBits(NumElts, Idx);
      return true;
    }
    break;
  }
  }
 
  return false;
}
 
/// Helper wrapper to main isSplatValue function.
bool SelectionDAG::isSplatValue(SDValue V, bool AllowUndefs) {
  EVT VT = V.getValueType();
  assert(VT.isVector() && "Vector type expected");
 
  APInt UndefElts;
  APInt DemandedElts;
 
  // For now we don't support this with scalable vectors.
  if (!VT.isScalableVector())
    DemandedElts = APInt::getAllOnesValue(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;
    APInt DemandedElts;
 
    if (!VT.isScalableVector())
      DemandedElts = APInt::getAllOnesValue(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).countTrailingOnes();
      }
      return V;
    }
    break;
  }
  case ISD::SPLAT_VECTOR:
    SplatIdx = 0;
    return V;
  case ISD::VECTOR_SHUFFLE: {
    if (VT.isScalableVector())
      return SDValue();
 
    // 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) {
  int SplatIdx;
  if (SDValue SrcVector = getSplatSourceVector(V, SplatIdx))
    return getNode(ISD::EXTRACT_VECTOR_ELT, SDLoc(V),
                   SrcVector.getValueType().getScalarType(), SrcVector,
                   getVectorIdxConstant(SplatIdx, SDLoc(V)));
  return SDValue();
}
 
const APInt *
SelectionDAG::getValidShiftAmountConstant(SDValue V,
                                          const APInt &DemandedElts) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  unsigned BitWidth = V.getScalarValueSizeInBits();
  if (ConstantSDNode *SA = isConstOrConstSplat(V.getOperand(1), DemandedElts)) {
    // Shifting more than the bitwidth is not valid.
    const APInt &ShAmt = SA->getAPIntValue();
    if (ShAmt.ult(BitWidth))
      return &ShAmt;
  }
  return nullptr;
}
 
const APInt *SelectionDAG::getValidMinimumShiftAmountConstant(
    SDValue V, const APInt &DemandedElts) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  if (const APInt *ValidAmt = getValidShiftAmountConstant(V, DemandedElts))
    return ValidAmt;
  unsigned BitWidth = V.getScalarValueSizeInBits();
  auto *BV = dyn_cast<BuildVectorSDNode>(V.getOperand(1));
  if (!BV)
    return nullptr;
  const APInt *MinShAmt = 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)
      return nullptr;
    // Shifting more than the bitwidth is not valid.
    const APInt &ShAmt = SA->getAPIntValue();
    if (ShAmt.uge(BitWidth))
      return nullptr;
    if (MinShAmt && MinShAmt->ule(ShAmt))
      continue;
    MinShAmt = &ShAmt;
  }
  return MinShAmt;
}
 
const APInt *SelectionDAG::getValidMaximumShiftAmountConstant(
    SDValue V, const APInt &DemandedElts) const {
  assert((V.getOpcode() == ISD::SHL || V.getOpcode() == ISD::SRL ||
          V.getOpcode() == ISD::SRA) &&
         "Unknown shift node");
  if (const APInt *ValidAmt = getValidShiftAmountConstant(V, DemandedElts))
    return ValidAmt;
  unsigned BitWidth = V.getScalarValueSizeInBits();
  auto *BV = dyn_cast<BuildVectorSDNode>(V.getOperand(1));
  if (!BV)
    return nullptr;
  const APInt *MaxShAmt = 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)
      return nullptr;
    // Shifting more than the bitwidth is not valid.
    const APInt &ShAmt = SA->getAPIntValue();
    if (ShAmt.uge(BitWidth))
      return nullptr;
    if (MaxShAmt && MaxShAmt->uge(ShAmt))
      continue;
    MaxShAmt = &ShAmt;
  }
  return MaxShAmt;
}
 
/// 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 {
  EVT VT = Op.getValueType();
 
  // TOOD: Until we have a plan for how to represent demanded elements for
  // scalable vectors, we can just bail out for now.
  if (Op.getValueType().isScalableVector()) {
    unsigned BitWidth = Op.getScalarValueSizeInBits();
    return KnownBits(BitWidth);
  }
 
  APInt DemandedElts = VT.isVector()
                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
                           : APInt(1, 1);
  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.
 
  // TOOD: Until we have a plan for how to represent demanded elements for
  // scalable vectors, we can just bail out for now.
  if (Op.getValueType().isScalableVector())
    return Known;
 
  if (auto *C = dyn_cast<ConstantSDNode>(Op)) {
    // We know all of the bits for a constant!
    return KnownBits::makeConstant(C->getAPIntValue());
  }
  if (auto *C = dyn_cast<ConstantFPSDNode>(Op)) {
    // We know all of the bits for a constant fp!
    return KnownBits::makeConstant(C->getValueAPF().bitcastToAPInt());
  }
 
  if (Depth >= MaxRecursionDepth)
    return Known;  // Limit search depth.
 
  KnownBits Known2;
  unsigned NumElts = DemandedElts.getBitWidth();
  assert((!Op.getValueType().isVector() ||
          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::BUILD_VECTOR:
    // Collect the known bits that are shared by every demanded vector element.
    Known.Zero.setAllBits(); Known.One.setAllBits();
    for (unsigned i = 0, e = Op.getNumOperands(); i != e; ++i) {
      if (!DemandedElts[i])
        continue;
 
      SDValue SrcOp = Op.getOperand(i);
      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 = KnownBits::commonBits(Known, Known2);
 
      // If we don't know any bits, early out.
      if (Known.isUnknown())
        break;
    }
    break;
  case ISD::VECTOR_SHUFFLE: {
    // Collect the known bits that are shared by every vector element referenced
    // by the shuffle.
    APInt DemandedLHS(NumElts, 0), DemandedRHS(NumElts, 0);
    Known.Zero.setAllBits(); Known.One.setAllBits();
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Op);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    for (unsigned i = 0; i != NumElts; ++i) {
      if (!DemandedElts[i])
        continue;
 
      int M = SVN->getMaskElt(i);
      if (M < 0) {
        // For UNDEF elements, we don't know anything about the common state of
        // the shuffle result.
        Known.resetAll();
        DemandedLHS.clearAllBits();
        DemandedRHS.clearAllBits();
        break;
      }
 
      if ((unsigned)M < NumElts)
        DemandedLHS.setBit((unsigned)M % NumElts);
      else
        DemandedRHS.setBit((unsigned)M % NumElts);
    }
    // Known bits are the values that are shared by every demanded element.
    if (!!DemandedLHS) {
      SDValue LHS = Op.getOperand(0);
      Known2 = computeKnownBits(LHS, DemandedLHS, Depth + 1);
      Known = KnownBits::commonBits(Known, 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 = KnownBits::commonBits(Known, Known2);
    }
    break;
  }
  case ISD::CONCAT_VECTORS: {
    // Split DemandedElts and test each of the demanded subvectors.
    Known.Zero.setAllBits(); Known.One.setAllBits();
    EVT SubVectorVT = Op.getOperand(0).getValueType();
    unsigned NumSubVectorElts = SubVectorVT.getVectorNumElements();
    unsigned NumSubVectors = Op.getNumOperands();
    for (unsigned i = 0; i != NumSubVectors; ++i) {
      APInt DemandedSub = DemandedElts.lshr(i * NumSubVectorElts);
      DemandedSub = DemandedSub.trunc(NumSubVectorElts);
      if (!!DemandedSub) {
        SDValue Sub = Op.getOperand(i);
        Known2 = computeKnownBits(Sub, DemandedSub, Depth + 1);
        Known = KnownBits::commonBits(Known, Known2);
      }
      // If we don't know any bits, early out.
      if (Known.isUnknown())
        break;
    }
    break;
  }
  case ISD::INSERT_SUBVECTOR: {
    // 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.insertBits(APInt::getNullValue(NumSubElts), Idx);
 
    Known.One.setAllBits();
    Known.Zero.setAllBits();
    if (!!DemandedSubElts) {
      Known = computeKnownBits(Sub, DemandedSubElts, Depth + 1);
      if (Known.isUnknown())
        break; // early-out.
    }
    if (!!DemandedSrcElts) {
      Known2 = computeKnownBits(Src, DemandedSrcElts, Depth + 1);
      Known = KnownBits::commonBits(Known, Known2);
    }
    break;
  }
  case ISD::EXTRACT_SUBVECTOR: {
    // Offset the demanded elts by the subvector index.
    SDValue Src = Op.getOperand(0);
    // Bail until we can represent demanded elements for scalable vectors.
    if (Src.getValueType().isScalableVector())
      break;
    uint64_t Idx = Op.getConstantOperandVal(1);
    unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
    APInt DemandedSrcElts = DemandedElts.zextOrSelf(NumSrcElts).shl(Idx);
    Known = computeKnownBits(Src, DemandedSrcElts, Depth + 1);
    break;
  }
  case ISD::SCALAR_TO_VECTOR: {
    // 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: {
    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.One |= Known2.One.zext(BitWidth).shl(SubBitWidth * Shifts);
        Known.Zero |= Known2.Zero.zext(BitWidth).shl(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(NumElts / SubScale, 0);
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i])
          SubDemandedElts.setBit(i / SubScale);
 
      Known2 = computeKnownBits(N0, SubDemandedElts, Depth + 1);
 
      Known.Zero.setAllBits(); Known.One.setAllBits();
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i]) {
          unsigned Shifts = IsLE ? i : NumElts - 1 - i;
          unsigned Offset = (Shifts % SubScale) * BitWidth;
          Known.One &= Known2.One.lshr(Offset).trunc(BitWidth);
          Known.Zero &= Known2.Zero.lshr(Offset).trunc(BitWidth);
          // 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);
    Known = KnownBits::mul(Known, Known2);
    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::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);
    if (Op.getResNo() == 0)
      Known = KnownBits::mul(Known, Known2);
    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);
    if (Op.getResNo() == 0)
      Known = KnownBits::mul(Known, Known2);
    else
      Known = KnownBits::mulhs(Known, Known2);
    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);
    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 = KnownBits::commonBits(Known, 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 = KnownBits::commonBits(Known, Known2);
    break;
  case ISD::SMULO:
  case ISD::UMULO:
  case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
    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::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);
    Known = KnownBits::shl(Known, Known2);
 
    // Minimum shift low bits are known zero.
    if (const APInt *ShMinAmt =
            getValidMinimumShiftAmountConstant(Op, DemandedElts))
      Known.Zero.setLowBits(ShMinAmt->getZExtValue());
    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);
 
    // Minimum shift high bits are known zero.
    if (const APInt *ShMinAmt =
            getValidMinimumShiftAmountConstant(Op, DemandedElts))
      Known.Zero.setHighBits(ShMinAmt->getZExtValue());
    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);
    // TODO: Add minimum shift high known sign bits.
    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))
      Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
      Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
      if (Opcode == ISD::FSHL) {
        Known.One <<= Amt;
        Known.Zero <<= Amt;
        Known2.One.lshrInPlace(BitWidth - Amt);
        Known2.Zero.lshrInPlace(BitWidth - Amt);
      } else {
        Known.One <<= BitWidth - Amt;
        Known.Zero <<= BitWidth - Amt;
        Known2.One.lshrInPlace(Amt);
        Known2.Zero.lshrInPlace(Amt);
      }
      Known.One |= Known2.One;
      Known.Zero |= Known2.Zero;
    }
    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_UNDEF: {
    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 = Log2_32(PossibleTZ) + 1;
    Known.Zero.setBitsFrom(LowBits);
    break;
  }
  case ISD::CTLZ:
  case ISD::CTLZ_ZERO_UNDEF: {
    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 = Log2_32(PossibleLZ) + 1;
    Known.Zero.setBitsFrom(LowBits);
    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(Log2_32(PossibleOnes) + 1);
    break;
  }
  case ISD::PARITY: {
    // Parity returns 0 everywhere but the LSB.
    Known.Zero.setBitsFrom(1);
    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()) {
        // 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.One.setAllBits();
          Known.Zero.setAllBits();
          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 (ISD::isZEXTLoad(Op.getNode()) && Op.getResNo() == 0) {
      // If this is a ZEXTLoad and we are looking at the loaded value.
      EVT VT = LD->getMemoryVT();
      unsigned MemBits = VT.getScalarSizeInBits();
      Known.Zero.setBitsFrom(MemBits);
    } else if (const MDNode *Ranges = LD->getRanges()) {
      if (LD->getExtensionType() == ISD::NON_EXTLOAD)
        computeKnownBitsFromRangeMetadata(*Ranges, Known);
    }
    break;
  }
  case ISD::ZERO_EXTEND_VECTOR_INREG: {
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zextOrSelf(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: {
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zextOrSelf(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: {
    EVT InVT = Op.getOperand(0).getValueType();
    APInt InDemandedElts = DemandedElts.zextOrSelf(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::AssertZext: {
    EVT VT = cast<VTSDNode>(Op.getOperand(1))->getVT();
    APInt InMask = APInt::getLowBitsSet(BitWidth, VT.getSizeInBits());
    Known = computeKnownBits(Op.getOperand(0), Depth+1);
    Known.Zero |= (~InMask);
    Known.One  &= (~Known.Zero);
    break;
  }
  case ISD::AssertAlign: {
    unsigned LogOfAlign = Log2(cast<AssertAlignSDNode>(Op)->getAlign());
    assert(LogOfAlign != 0);
    // 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::FGETSIGN:
    // All bits are zero except the low bit.
    Known.Zero.setBitsFrom(1);
    break;
  case ISD::USUBO:
  case ISD::SSUBO:
    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;
    }
    LLVM_FALLTHROUGH;
  case ISD::SUB:
  case ISD::SUBC: {
    assert(Op.getResNo() == 0 &&
           "We only compute knownbits for the difference here.");
 
    Known = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known2 = computeKnownBits(Op.getOperand(1), DemandedElts, Depth + 1);
    Known = KnownBits::computeForAddSub(/* Add */ false, /* NSW */ false,
                                        Known, Known2);
    break;
  }
  case ISD::UADDO:
  case ISD::SADDO:
  case ISD::ADDCARRY:
    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;
    }
    LLVM_FALLTHROUGH;
  case ISD::ADD:
  case ISD::ADDC:
  case ISD::ADDE: {
    assert(Op.getResNo() == 0 && "We only compute knownbits for the sum here.");
 
    // With ADDE and ADDCARRY, 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::ADDCARRY)
      // TODO: Compute known bits for the carry operand. Not sure if it is worth
      // the trouble (how often will we find a known carry bit). And I haven't
      // tested this very much yet, but something like this might work:
      //   Carry = computeKnownBits(Op.getOperand(2), DemandedElts, Depth + 1);
      //   Carry = Carry.zextOrTrunc(1, false);
      Carry.resetAll();
    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::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::getAllOnesValue(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 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.One.setAllBits();
    Known.Zero.setAllBits();
    if (DemandedVal) {
      Known2 = computeKnownBits(InVal, Depth + 1);
      Known = KnownBits::commonBits(Known, Known2.zextOrTrunc(BitWidth));
    }
    if (!!DemandedVecElts) {
      Known2 = computeKnownBits(InVec, DemandedVecElts, Depth + 1);
      Known = KnownBits::commonBits(Known, 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: {
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known = Known2.abs();
    break;
  }
  case ISD::USUBSAT: {
    // The result of usubsat will never be larger than the LHS.
    Known2 = computeKnownBits(Op.getOperand(0), DemandedElts, Depth + 1);
    Known.Zero.setHighBits(Known2.countMinLeadingZeros());
    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);
    break;
  }
  case ISD::FrameIndex:
  case ISD::TargetFrameIndex:
    TLI->computeKnownBitsForFrameIndex(cast<FrameIndexSDNode>(Op)->getIndex(),
                                       Known, getMachineFunction());
    break;
 
  default:
    if (Opcode < ISD::BUILTIN_OP_END)
      break;
    LLVM_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;
  }
 
  assert(!Known.hasConflict() && "Bits known to be one AND zero?");
  return Known;
}
 
SelectionDAG::OverflowKind SelectionDAG::computeOverflowKind(SDValue N0,
                                                             SDValue N1) const {
  // X + 0 never overflow
  if (isNullConstant(N1))
    return OFK_Never;
 
  KnownBits N1Known = computeKnownBits(N1);
  if (N1Known.Zero.getBoolValue()) {
    KnownBits N0Known = computeKnownBits(N0);
 
    bool overflow;
    (void)N0Known.getMaxValue().uadd_ov(N1Known.getMaxValue(), overflow);
    if (!overflow)
      return OFK_Never;
  }
 
  // mulhi + 1 never overflow
  if (N0.getOpcode() == ISD::UMUL_LOHI && N0.getResNo() == 1 &&
      (N1Known.getMaxValue() & 0x01) == N1Known.getMaxValue())
    return OFK_Never;
 
  if (N1.getOpcode() == ISD::UMUL_LOHI && N1.getResNo() == 1) {
    KnownBits N0Known = computeKnownBits(N0);
 
    if ((N0Known.getMaxValue() & 0x01) == N0Known.getMaxValue())
      return OFK_Never;
  }
 
  return OFK_Sometime;
}
 
bool SelectionDAG::isKnownToBeAPowerOfTwo(SDValue Val) const {
  EVT OpVT = Val.getValueType();
  unsigned BitWidth = OpVT.getScalarSizeInBits();
 
  // Is the constant a known power of 2?
  if (ConstantSDNode *Const = dyn_cast<ConstantSDNode>(Val))
    return Const->getAPIntValue().zextOrTrunc(BitWidth).isPowerOf2();
 
  // A left-shift of a constant one will have exactly one bit set because
  // shifting the bit off the end is undefined.
  if (Val.getOpcode() == ISD::SHL) {
    auto *C = isConstOrConstSplat(Val.getOperand(0));
    if (C && C->getAPIntValue() == 1)
      return true;
  }
 
  // Similarly, a logical right-shift of a constant sign-bit will have exactly
  // one bit set.
  if (Val.getOpcode() == ISD::SRL) {
    auto *C = isConstOrConstSplat(Val.getOperand(0));
    if (C && C->getAPIntValue().isSignMask())
      return true;
  }
 
  // Are all operands of a build vector constant powers of two?
  if (Val.getOpcode() == ISD::BUILD_VECTOR)
    if (llvm::all_of(Val->ops(), [BitWidth](SDValue E) {
          if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(E))
            return C->getAPIntValue().zextOrTrunc(BitWidth).isPowerOf2();
          return false;
        }))
      return true;
 
  // More could be done here, though the above checks are enough
  // to handle some common cases.
 
  // Fall back to computeKnownBits to catch other known cases.
  KnownBits Known = computeKnownBits(Val);
  return (Known.countMaxPopulation() == 1) && (Known.countMinPopulation() == 1);
}
 
unsigned SelectionDAG::ComputeNumSignBits(SDValue Op, unsigned Depth) const {
  EVT VT = Op.getValueType();
 
  // TODO: Assume we don't know anything for now.
  if (VT.isScalableVector())
    return 1;
 
  APInt DemandedElts = VT.isVector()
                           ? APInt::getAllOnesValue(VT.getVectorNumElements())
                           : APInt(1, 1);
  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;
 
  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 || VT.isScalableVector())
    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::BUILD_VECTOR:
    Tmp = VTBits;
    for (unsigned i = 0, e = Op.getNumOperands(); (i < e) && (Tmp > 1); ++i) {
      if (!DemandedElts[i])
        continue;
 
      SDValue SrcOp = Op.getOperand(i);
      Tmp2 = ComputeNumSignBits(SrcOp, Depth + 1);
 
      // BUILD_VECTOR can implicitly truncate sources, we must handle this.
      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_SHUFFLE: {
    // Collect the minimum number of sign bits that are shared by every vector
    // element referenced by the shuffle.
    APInt DemandedLHS(NumElts, 0), DemandedRHS(NumElts, 0);
    const ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Op);
    assert(NumElts == SVN->getMask().size() && "Unexpected vector size");
    for (unsigned i = 0; i != NumElts; ++i) {
      int M = SVN->getMaskElt(i);
      if (!DemandedElts[i])
        continue;
      // For UNDEF elements, we don't know anything about the common state of
      // the shuffle result.
      if (M < 0)
        return 1;
      if ((unsigned)M < NumElts)
        DemandedLHS.setBit((unsigned)M % NumElts);
      else
        DemandedRHS.setBit((unsigned)M % NumElts);
    }
    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: {
    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(NumElts / Scale, 0);
      for (unsigned i = 0; i != NumElts; ++i)
        if (DemandedElts[i])
          SrcDemandedElts.setBit(i / 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::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: {
    SDValue Src = Op.getOperand(0);
    EVT SrcVT = Src.getValueType();
    APInt DemandedSrcElts = DemandedElts.zextOrSelf(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 (const APInt *ShAmt =
            getValidMinimumShiftAmountConstant(Op, DemandedElts))
      Tmp = std::min<uint64_t>(Tmp + ShAmt->getZExtValue(), VTBits);
    return Tmp;
  case ISD::SHL:
    if (const APInt *ShAmt =
            getValidMaximumShiftAmountConstant(Op, DemandedElts)) {
      // shl destroys sign bits, ensure it doesn't shift out all sign bits.
      Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
      if (ShAmt->ult(Tmp))
        return Tmp - ShAmt->getZExtValue();
    }
    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::SADDO:
  case ISD::UADDO:
  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::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::ROTL:
  case ISD::ROTR:
    Tmp = ComputeNumSignBits(Op.getOperand(0), DemandedElts, Depth + 1);
 
    // If we're rotating an 0/-1 value, then it stays an 0/-1 value.
    if (Tmp == VTBits)
      return VTBits;
 
    if (ConstantSDNode *C =
            isConstOrConstSplat(Op.getOperand(1), DemandedElts)) {
      unsigned RotAmt = C->getAPIntValue().urem(VTBits);
 
      // Handle rotate right by N like a rotate left by 32-N.
      if (Opcode == ISD::ROTR)
        RotAmt = (VTBits - RotAmt) % VTBits;
 
      // If we aren't rotating out all of the known-in sign bits, return the
      // number that are left.  This handles rotl(sext(x), 1) for example.
      if (Tmp > (RotAmt + 1)) return (Tmp - RotAmt);
    }
    break;
  case ISD::ADD:
  case ISD::ADDC:
    // Add 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.
 
    // Special case decrementing a value (ADD X, -1):
    if (ConstantSDNode *CRHS =
            isConstOrConstSplat(Op.getOperand(1), DemandedElts))
      if (CRHS->isAllOnesValue()) {
        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).isAllOnesValue())
          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.
    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->isNullValue()) {
        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).isAllOnesValue())
          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::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: {
    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::max(std::min(KnownSign - rIndex * BitWidth, BitWidth), 0);
  }
  case ISD::INSERT_VECTOR_ELT: {
    // 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::getAllOnesValue(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);
    // Bail until we can represent demanded elements for scalable vectors.
    if (Src.getValueType().isScalableVector())
      break;
    uint64_t Idx = Op.getConstantOperandVal(1);
    unsigned NumSrcElts = Src.getValueType().getVectorNumElements();
    APInt DemandedSrcElts = DemandedElts.zextOrSelf(NumSrcElts).shl(Idx);
    return ComputeNumSignBits(Src, DemandedSrcElts, Depth + 1);
  }
  case ISD::CONCAT_VECTORS: {
    // 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.lshr(i * NumSubVectorElts);
      DemandedSub = DemandedSub.trunc(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: {
    // 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.insertBits(APInt::getNullValue(NumSubElts), Idx);
 
    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;
  }
  }
 
  // If we are looking at the loaded value of the SDNode.
  if (Op.getResNo() == 0) {
    // Handle LOADX separately here. EXTLOAD case will fallthrough.
    if (LoadSDNode *LD = dyn_cast<LoadSDNode>(Op)) {
      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() &&
              (NumElts * VTBits) == CstTy->getPrimitiveSizeInBits()) {
            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;
      }
    }
  }
 
  // 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) {
    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);
 
  APInt Mask;
  if (Known.isNonNegative()) {        // sign bit is 0
    Mask = Known.Zero;
  } else if (Known.isNegative()) {  // sign bit is 1;
    Mask = Known.One;
  } else {
    // Nothing known.
    return FirstAnswer;
  }
 
  // Okay, we know that the sign bit in Mask is set.  Use CLO to determine
  // the number of identical bits in the top of the input value.
  Mask <<= Mask.getBitWidth()-VTBits;
  return std::max(FirstAnswer, Mask.countLeadingOnes());
}
 
bool SelectionDAG::isBaseWithConstantOffset(SDValue Op) const {
  if ((Op.getOpcode() != ISD::ADD && Op.getOpcode() != ISD::OR) ||
      !isa<ConstantSDNode>(Op.getOperand(1)))
    return false;
 
  if (Op.getOpcode() == ISD::OR &&
      !MaskedValueIsZero(Op.getOperand(0), Op.getConstantOperandAPInt(1)))
    return false;
 
  return true;
}
 
bool SelectionDAG::isKnownNeverNaN(SDValue Op, bool SNaN, unsigned Depth) const {
  // If we're told that NaNs won't happen, assume they won't.
  if (getTarget().Options.NoNaNsFPMath || Op->getFlags().hasNoNaNs())
    return true;
 
  if (Depth >= MaxRecursionDepth)
    return false; // Limit search depth.
 
  // TODO: Handle vectors.
  // If the value is a constant, we can obviously see if it is a NaN or not.
  if (const ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Op)) {
    return !C->getValueAPF().isNaN() ||
           (SNaN && !C->getValueAPF().isSignaling());
  }
 
  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: {
    if (SNaN)
      return true;
    // TODO: Need isKnownNeverInfinity
    return false;
  }
  case ISD::FCANONICALIZE:
  case ISD::FEXP:
  case ISD::FEXP2:
  case ISD::FTRUNC:
  case ISD::FFLOOR:
  case ISD::FCEIL:
  case ISD::FROUND:
  case ISD::FROUNDEVEN:
  case ISD::FRINT:
  case ISD::FNEARBYINT: {
    if (SNaN)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
  }
  case ISD::FABS:
  case ISD::FNEG:
  case ISD::FCOPYSIGN: {
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
  }
  case ISD::SELECT:
    return isKnownNeverNaN(Op.getOperand(1), SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(2), SNaN, Depth + 1);
  case ISD::FP_EXTEND:
  case ISD::FP_ROUND: {
    if (SNaN)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1);
  }
  case ISD::SINT_TO_FP:
  case ISD::UINT_TO_FP:
    return true;
  case ISD::FMA:
  case ISD::FMAD: {
    if (SNaN)
      return true;
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(1), SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(2), SNaN, Depth + 1);
  }
  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: {
    // 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), SNaN, Depth + 1) ||
           isKnownNeverNaN(Op.getOperand(1), 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), false, Depth + 1) &&
            isKnownNeverSNaN(Op.getOperand(1), Depth + 1)) ||
           (isKnownNeverNaN(Op.getOperand(1), false, Depth + 1) &&
            isKnownNeverSNaN(Op.getOperand(0), Depth + 1));
  }
  case ISD::FMINIMUM:
  case ISD::FMAXIMUM: {
    // TODO: Does this quiet or return the origina NaN as-is?
    return isKnownNeverNaN(Op.getOperand(0), SNaN, Depth + 1) &&
           isKnownNeverNaN(Op.getOperand(1), SNaN, Depth + 1);
  }
  case ISD::EXTRACT_VECTOR_ELT: {
    return isKnownNeverNaN(Op.getOperand(0), 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, *this, SNaN, Depth);
    }
 
    return false;
  }
}
 
bool SelectionDAG::isKnownNeverZeroFloat(SDValue Op) const {
  assert(Op.getValueType().isFloatingPoint() &&
         "Floating point type expected");
 
  // If the value is a constant, we can obviously see if it is a zero or not.
  // TODO: Add BuildVector support.
  if (const ConstantFPSDNode *C = dyn_cast<ConstantFPSDNode>(Op))
    return !C->isZero();
  return false;
}
 
bool SelectionDAG::isKnownNeverZero(SDValue Op) const {
  assert(!Op.getValueType().isFloatingPoint() &&
         "Floating point types unsupported - use isKnownNeverZeroFloat");
 
  // If the value is a constant, we can obviously see if it is a zero or not.
  if (ISD::matchUnaryPredicate(
          Op, [](ConstantSDNode *C) { return !C->isNullValue(); }))
    return true;
 
  // TODO: Recognize more cases here.
  switch (Op.getOpcode()) {
  default: break;
  case ISD::OR:
    if (isKnownNeverZero(Op.getOperand(1)) ||
        isKnownNeverZero(Op.getOperand(0)))
      return true;
    break;
  }
 
  return false;
}
 
bool SelectionDAG::isEqualTo(SDValue A, SDValue B) const {
  // Check the obvious case.
  if (A == B) return true;
 
  // For 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;
}
 
// FIXME: unify with llvm::haveNoCommonBitsSet.
// FIXME: could also handle masked merge pattern (X & ~M) op (Y & M)
bool SelectionDAG::haveNoCommonBitsSet(SDValue A, SDValue B) const {
  assert(A.getValueType() == B.getValueType() &&
         "Values must have the same type");
  return KnownBits::haveNoCommonBitsSet(computeKnownBits(A),
                                        computeKnownBits(B));
}
 
static SDValue FoldSTEP_VECTOR(const SDLoc &DL, EVT VT, SDValue Step,
                               SelectionDAG &DAG) {
  if (cast<ConstantSDNode>(Step)->isNullValue())
    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.
  if (llvm::all_of(Ops, [](SDValue Op) { return Op.isUndef(); }))
    return 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)) ||
        cast<ConstantSDNode>(Ops[i].getOperand(1))->getAPIntValue() != 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.
  if (llvm::all_of(Ops, [](SDValue Op) { return Op.isUndef(); }))
    return 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 with all UNDEF/BUILD_VECTOR 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.isUndef())
      Elts.append(OpVT.getVectorNumElements(), DAG.getUNDEF(SVT));
    else if (Op.getOpcode() == ISD::BUILD_VECTOR)
      Elts.append(Op->op_begin(), Op->op_end());
    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.isUndef())
        Op = DAG.getUNDEF(SVT);
      else
        Op = DAG.getTargetLoweringInfo().isZExtFree(Op.getValueType(), SVT)
                 ? DAG.getZExtOrTrunc(