//===-- AArch64ISelLowering.cpp - AArch64 DAG Lowering Implementation -----===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines the interfaces that AArch64 uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "aarch64-isel"
#include "AArch64.h"
#include "AArch64ISelLowering.h"
#include "AArch64MachineFunctionInfo.h"
#include "AArch64TargetMachine.h"
#include "AArch64TargetObjectFile.h"
#include "Utils/AArch64BaseInfo.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/IR/CallingConv.h"

using namespace llvm;

static TargetLoweringObjectFile *createTLOF(AArch64TargetMachine &TM) {
  const AArch64Subtarget *Subtarget = &TM.getSubtarget<AArch64Subtarget>();
  assert (Subtarget->isTargetELF() && "unknown subtarget type");
  return new AArch64ElfTargetObjectFile();
}

AArch64TargetLowering::AArch64TargetLowering(AArch64TargetMachine &TM)
  : TargetLowering(TM, createTLOF(TM)), Itins(TM.getInstrItineraryData()) {

  const AArch64Subtarget *Subtarget = &TM.getSubtarget<AArch64Subtarget>();

  // SIMD compares set the entire lane's bits to 1
  setBooleanVectorContents(ZeroOrNegativeOneBooleanContent);

  // Scalar register <-> type mapping
  addRegisterClass(MVT::i32, &AArch64::GPR32RegClass);
  addRegisterClass(MVT::i64, &AArch64::GPR64RegClass);

  if (Subtarget->hasFPARMv8()) {
    addRegisterClass(MVT::f16, &AArch64::FPR16RegClass);
    addRegisterClass(MVT::f32, &AArch64::FPR32RegClass);
    addRegisterClass(MVT::f64, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::f128, &AArch64::FPR128RegClass);
  }

  if (Subtarget->hasNEON()) {
    // And the vectors
    addRegisterClass(MVT::v1i8,  &AArch64::FPR8RegClass);
    addRegisterClass(MVT::v1i16, &AArch64::FPR16RegClass);
    addRegisterClass(MVT::v1i32, &AArch64::FPR32RegClass);
    addRegisterClass(MVT::v1i64, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v1f32, &AArch64::FPR32RegClass);
    addRegisterClass(MVT::v1f64, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v8i8,  &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v4i16, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v2i32, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v1i64, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v2f32, &AArch64::FPR64RegClass);
    addRegisterClass(MVT::v16i8, &AArch64::FPR128RegClass);
    addRegisterClass(MVT::v8i16, &AArch64::FPR128RegClass);
    addRegisterClass(MVT::v4i32, &AArch64::FPR128RegClass);
    addRegisterClass(MVT::v2i64, &AArch64::FPR128RegClass);
    addRegisterClass(MVT::v4f32, &AArch64::FPR128RegClass);
    addRegisterClass(MVT::v2f64, &AArch64::FPR128RegClass);
  }

  computeRegisterProperties();

  // We combine OR nodes for bitfield and NEON BSL operations.
  setTargetDAGCombine(ISD::OR);

  setTargetDAGCombine(ISD::AND);
  setTargetDAGCombine(ISD::SRA);
  setTargetDAGCombine(ISD::SRL);
  setTargetDAGCombine(ISD::SHL);

  setTargetDAGCombine(ISD::INTRINSIC_WO_CHAIN);
  setTargetDAGCombine(ISD::INTRINSIC_VOID);
  setTargetDAGCombine(ISD::INTRINSIC_W_CHAIN);

  // AArch64 does not have i1 loads, or much of anything for i1 really.
  setLoadExtAction(ISD::SEXTLOAD, MVT::i1, Promote);
  setLoadExtAction(ISD::ZEXTLOAD, MVT::i1, Promote);
  setLoadExtAction(ISD::EXTLOAD, MVT::i1, Promote);

  setStackPointerRegisterToSaveRestore(AArch64::XSP);
  setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i64, Expand);
  setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand);
  setOperationAction(ISD::STACKSAVE, MVT::Other, Expand);

  // We'll lower globals to wrappers for selection.
  setOperationAction(ISD::GlobalAddress, MVT::i64, Custom);
  setOperationAction(ISD::GlobalTLSAddress, MVT::i64, Custom);

  // A64 instructions have the comparison predicate attached to the user of the
  // result, but having a separate comparison is valuable for matching.
  setOperationAction(ISD::BR_CC, MVT::i32, Custom);
  setOperationAction(ISD::BR_CC, MVT::i64, Custom);
  setOperationAction(ISD::BR_CC, MVT::f32, Custom);
  setOperationAction(ISD::BR_CC, MVT::f64, Custom);

  setOperationAction(ISD::SELECT, MVT::i32, Custom);
  setOperationAction(ISD::SELECT, MVT::i64, Custom);
  setOperationAction(ISD::SELECT, MVT::f32, Custom);
  setOperationAction(ISD::SELECT, MVT::f64, Custom);

  setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);
  setOperationAction(ISD::SELECT_CC, MVT::i64, Custom);
  setOperationAction(ISD::SELECT_CC, MVT::f32, Custom);
  setOperationAction(ISD::SELECT_CC, MVT::f64, Custom);

  setOperationAction(ISD::BRCOND, MVT::Other, Custom);

  setOperationAction(ISD::SETCC, MVT::i32, Custom);
  setOperationAction(ISD::SETCC, MVT::i64, Custom);
  setOperationAction(ISD::SETCC, MVT::f32, Custom);
  setOperationAction(ISD::SETCC, MVT::f64, Custom);

  setOperationAction(ISD::BR_JT, MVT::Other, Expand);
  setOperationAction(ISD::JumpTable, MVT::i32, Custom);
  setOperationAction(ISD::JumpTable, MVT::i64, Custom);

  setOperationAction(ISD::VASTART, MVT::Other, Custom);
  setOperationAction(ISD::VACOPY, MVT::Other, Custom);
  setOperationAction(ISD::VAEND, MVT::Other, Expand);
  setOperationAction(ISD::VAARG, MVT::Other, Expand);

  setOperationAction(ISD::BlockAddress, MVT::i64, Custom);

  setOperationAction(ISD::ROTL, MVT::i32, Expand);
  setOperationAction(ISD::ROTL, MVT::i64, Expand);

  setOperationAction(ISD::UREM, MVT::i32, Expand);
  setOperationAction(ISD::UREM, MVT::i64, Expand);
  setOperationAction(ISD::UDIVREM, MVT::i32, Expand);
  setOperationAction(ISD::UDIVREM, MVT::i64, Expand);

  setOperationAction(ISD::SREM, MVT::i32, Expand);
  setOperationAction(ISD::SREM, MVT::i64, Expand);
  setOperationAction(ISD::SDIVREM, MVT::i32, Expand);
  setOperationAction(ISD::SDIVREM, MVT::i64, Expand);

  setOperationAction(ISD::CTPOP, MVT::i32, Expand);
  setOperationAction(ISD::CTPOP, MVT::i64, Expand);

  // Legal floating-point operations.
  setOperationAction(ISD::FABS, MVT::f32, Legal);
  setOperationAction(ISD::FABS, MVT::f64, Legal);

  setOperationAction(ISD::FCEIL, MVT::f32, Legal);
  setOperationAction(ISD::FCEIL, MVT::f64, Legal);

  setOperationAction(ISD::FFLOOR, MVT::f32, Legal);
  setOperationAction(ISD::FFLOOR, MVT::f64, Legal);

  setOperationAction(ISD::FNEARBYINT, MVT::f32, Legal);
  setOperationAction(ISD::FNEARBYINT, MVT::f64, Legal);

  setOperationAction(ISD::FNEG, MVT::f32, Legal);
  setOperationAction(ISD::FNEG, MVT::f64, Legal);

  setOperationAction(ISD::FRINT, MVT::f32, Legal);
  setOperationAction(ISD::FRINT, MVT::f64, Legal);

  setOperationAction(ISD::FSQRT, MVT::f32, Legal);
  setOperationAction(ISD::FSQRT, MVT::f64, Legal);

  setOperationAction(ISD::FTRUNC, MVT::f32, Legal);
  setOperationAction(ISD::FTRUNC, MVT::f64, Legal);

  setOperationAction(ISD::ConstantFP, MVT::f32, Legal);
  setOperationAction(ISD::ConstantFP, MVT::f64, Legal);
  setOperationAction(ISD::ConstantFP, MVT::f128, Legal);

  // Illegal floating-point operations.
  setOperationAction(ISD::FCOPYSIGN, MVT::f32, Expand);
  setOperationAction(ISD::FCOPYSIGN, MVT::f64, Expand);

  setOperationAction(ISD::FCOS, MVT::f32, Expand);
  setOperationAction(ISD::FCOS, MVT::f64, Expand);

  setOperationAction(ISD::FEXP, MVT::f32, Expand);
  setOperationAction(ISD::FEXP, MVT::f64, Expand);

  setOperationAction(ISD::FEXP2, MVT::f32, Expand);
  setOperationAction(ISD::FEXP2, MVT::f64, Expand);

  setOperationAction(ISD::FLOG, MVT::f32, Expand);
  setOperationAction(ISD::FLOG, MVT::f64, Expand);

  setOperationAction(ISD::FLOG2, MVT::f32, Expand);
  setOperationAction(ISD::FLOG2, MVT::f64, Expand);

  setOperationAction(ISD::FLOG10, MVT::f32, Expand);
  setOperationAction(ISD::FLOG10, MVT::f64, Expand);

  setOperationAction(ISD::FPOW, MVT::f32, Expand);
  setOperationAction(ISD::FPOW, MVT::f64, Expand);

  setOperationAction(ISD::FPOWI, MVT::f32, Expand);
  setOperationAction(ISD::FPOWI, MVT::f64, Expand);

  setOperationAction(ISD::FREM, MVT::f32, Expand);
  setOperationAction(ISD::FREM, MVT::f64, Expand);

  setOperationAction(ISD::FSIN, MVT::f32, Expand);
  setOperationAction(ISD::FSIN, MVT::f64, Expand);

  setOperationAction(ISD::FSINCOS, MVT::f32, Expand);
  setOperationAction(ISD::FSINCOS, MVT::f64, Expand);

  // Virtually no operation on f128 is legal, but LLVM can't expand them when
  // there's a valid register class, so we need custom operations in most cases.
  setOperationAction(ISD::FABS,       MVT::f128, Expand);
  setOperationAction(ISD::FADD,       MVT::f128, Custom);
  setOperationAction(ISD::FCOPYSIGN,  MVT::f128, Expand);
  setOperationAction(ISD::FCOS,       MVT::f128, Expand);
  setOperationAction(ISD::FDIV,       MVT::f128, Custom);
  setOperationAction(ISD::FMA,        MVT::f128, Expand);
  setOperationAction(ISD::FMUL,       MVT::f128, Custom);
  setOperationAction(ISD::FNEG,       MVT::f128, Expand);
  setOperationAction(ISD::FP_EXTEND,  MVT::f128, Expand);
  setOperationAction(ISD::FP_ROUND,   MVT::f128, Expand);
  setOperationAction(ISD::FPOW,       MVT::f128, Expand);
  setOperationAction(ISD::FREM,       MVT::f128, Expand);
  setOperationAction(ISD::FRINT,      MVT::f128, Expand);
  setOperationAction(ISD::FSIN,       MVT::f128, Expand);
  setOperationAction(ISD::FSINCOS,    MVT::f128, Expand);
  setOperationAction(ISD::FSQRT,      MVT::f128, Expand);
  setOperationAction(ISD::FSUB,       MVT::f128, Custom);
  setOperationAction(ISD::FTRUNC,     MVT::f128, Expand);
  setOperationAction(ISD::SETCC,      MVT::f128, Custom);
  setOperationAction(ISD::BR_CC,      MVT::f128, Custom);
  setOperationAction(ISD::SELECT,     MVT::f128, Expand);
  setOperationAction(ISD::SELECT_CC,  MVT::f128, Custom);
  setOperationAction(ISD::FP_EXTEND,  MVT::f128, Custom);

  // Lowering for many of the conversions is actually specified by the non-f128
  // type. The LowerXXX function will be trivial when f128 isn't involved.
  setOperationAction(ISD::FP_TO_SINT, MVT::i32, Custom);
  setOperationAction(ISD::FP_TO_SINT, MVT::i64, Custom);
  setOperationAction(ISD::FP_TO_SINT, MVT::i128, Custom);
  setOperationAction(ISD::FP_TO_UINT, MVT::i32, Custom);
  setOperationAction(ISD::FP_TO_UINT, MVT::i64, Custom);
  setOperationAction(ISD::FP_TO_UINT, MVT::i128, Custom);
  setOperationAction(ISD::SINT_TO_FP, MVT::i32, Custom);
  setOperationAction(ISD::SINT_TO_FP, MVT::i64, Custom);
  setOperationAction(ISD::SINT_TO_FP, MVT::i128, Custom);
  setOperationAction(ISD::UINT_TO_FP, MVT::i32, Custom);
  setOperationAction(ISD::UINT_TO_FP, MVT::i64, Custom);
  setOperationAction(ISD::UINT_TO_FP, MVT::i128, Custom);
  setOperationAction(ISD::FP_ROUND,  MVT::f32, Custom);
  setOperationAction(ISD::FP_ROUND,  MVT::f64, Custom);

  // This prevents LLVM trying to compress double constants into a floating
  // constant-pool entry and trying to load from there. It's of doubtful benefit
  // for A64: we'd need LDR followed by FCVT, I believe.
  setLoadExtAction(ISD::EXTLOAD, MVT::f64, Expand);
  setLoadExtAction(ISD::EXTLOAD, MVT::f32, Expand);
  setLoadExtAction(ISD::EXTLOAD, MVT::f16, Expand);

  setTruncStoreAction(MVT::f128, MVT::f64, Expand);
  setTruncStoreAction(MVT::f128, MVT::f32, Expand);
  setTruncStoreAction(MVT::f128, MVT::f16, Expand);
  setTruncStoreAction(MVT::f64, MVT::f32, Expand);
  setTruncStoreAction(MVT::f64, MVT::f16, Expand);
  setTruncStoreAction(MVT::f32, MVT::f16, Expand);

  setExceptionPointerRegister(AArch64::X0);
  setExceptionSelectorRegister(AArch64::X1);

  if (Subtarget->hasNEON()) {
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1i8, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v8i8, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v16i8, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1i16, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v4i16, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v8i16, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1i32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v2i32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v4i32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1i64, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v2i64, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1f32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v2f32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v4f32, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v1f64, Custom);
    setOperationAction(ISD::BUILD_VECTOR, MVT::v2f64, Custom);

    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v8i8, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v16i8, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v4i16, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v8i16, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v2i32, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v4i32, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v1i64, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v2i64, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v2f32, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v4f32, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v1f64, Custom);
    setOperationAction(ISD::VECTOR_SHUFFLE, MVT::v2f64, Custom);

    setOperationAction(ISD::CONCAT_VECTORS, MVT::v16i8, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v8i16, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v4i32, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v2i64, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v8i16, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v4i32, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v2i64, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v4f32, Legal);
    setOperationAction(ISD::CONCAT_VECTORS, MVT::v2f64, Legal);

    setOperationAction(ISD::SETCC, MVT::v8i8, Custom);
    setOperationAction(ISD::SETCC, MVT::v16i8, Custom);
    setOperationAction(ISD::SETCC, MVT::v4i16, Custom);
    setOperationAction(ISD::SETCC, MVT::v8i16, Custom);
    setOperationAction(ISD::SETCC, MVT::v2i32, Custom);
    setOperationAction(ISD::SETCC, MVT::v4i32, Custom);
    setOperationAction(ISD::SETCC, MVT::v1i64, Custom);
    setOperationAction(ISD::SETCC, MVT::v2i64, Custom);
    setOperationAction(ISD::SETCC, MVT::v1f32, Custom);
    setOperationAction(ISD::SETCC, MVT::v2f32, Custom);
    setOperationAction(ISD::SETCC, MVT::v4f32, Custom);
    setOperationAction(ISD::SETCC, MVT::v1f64, Custom);
    setOperationAction(ISD::SETCC, MVT::v2f64, Custom);

    setOperationAction(ISD::FFLOOR, MVT::v2f32, Legal);
    setOperationAction(ISD::FFLOOR, MVT::v4f32, Legal);
    setOperationAction(ISD::FFLOOR, MVT::v1f64, Legal);
    setOperationAction(ISD::FFLOOR, MVT::v2f64, Legal);

    setOperationAction(ISD::FCEIL, MVT::v2f32, Legal);
    setOperationAction(ISD::FCEIL, MVT::v4f32, Legal);
    setOperationAction(ISD::FCEIL, MVT::v1f64, Legal);
    setOperationAction(ISD::FCEIL, MVT::v2f64, Legal);

    setOperationAction(ISD::FTRUNC, MVT::v2f32, Legal);
    setOperationAction(ISD::FTRUNC, MVT::v4f32, Legal);
    setOperationAction(ISD::FTRUNC, MVT::v1f64, Legal);
    setOperationAction(ISD::FTRUNC, MVT::v2f64, Legal);

    setOperationAction(ISD::FRINT, MVT::v2f32, Legal);
    setOperationAction(ISD::FRINT, MVT::v4f32, Legal);
    setOperationAction(ISD::FRINT, MVT::v1f64, Legal);
    setOperationAction(ISD::FRINT, MVT::v2f64, Legal);

    setOperationAction(ISD::FNEARBYINT, MVT::v2f32, Legal);
    setOperationAction(ISD::FNEARBYINT, MVT::v4f32, Legal);
    setOperationAction(ISD::FNEARBYINT, MVT::v1f64, Legal);
    setOperationAction(ISD::FNEARBYINT, MVT::v2f64, Legal);

    setOperationAction(ISD::FROUND, MVT::v2f32, Legal);
    setOperationAction(ISD::FROUND, MVT::v4f32, Legal);
    setOperationAction(ISD::FROUND, MVT::v1f64, Legal);
    setOperationAction(ISD::FROUND, MVT::v2f64, Legal);
  }
}

EVT AArch64TargetLowering::getSetCCResultType(LLVMContext &, EVT VT) const {
  // It's reasonably important that this value matches the "natural" legal
  // promotion from i1 for scalar types. Otherwise LegalizeTypes can get itself
  // in a twist (e.g. inserting an any_extend which then becomes i64 -> i64).
  if (!VT.isVector()) return MVT::i32;
  return VT.changeVectorElementTypeToInteger();
}

static void getExclusiveOperation(unsigned Size, AtomicOrdering Ord,
                                  unsigned &LdrOpc,
                                  unsigned &StrOpc) {
  static const unsigned LoadBares[] = {AArch64::LDXR_byte, AArch64::LDXR_hword,
                                       AArch64::LDXR_word, AArch64::LDXR_dword};
  static const unsigned LoadAcqs[] = {AArch64::LDAXR_byte, AArch64::LDAXR_hword,
                                     AArch64::LDAXR_word, AArch64::LDAXR_dword};
  static const unsigned StoreBares[] = {AArch64::STXR_byte, AArch64::STXR_hword,
                                       AArch64::STXR_word, AArch64::STXR_dword};
  static const unsigned StoreRels[] = {AArch64::STLXR_byte,AArch64::STLXR_hword,
                                     AArch64::STLXR_word, AArch64::STLXR_dword};

  const unsigned *LoadOps, *StoreOps;
  if (Ord == Acquire || Ord == AcquireRelease || Ord == SequentiallyConsistent)
    LoadOps = LoadAcqs;
  else
    LoadOps = LoadBares;

  if (Ord == Release || Ord == AcquireRelease || Ord == SequentiallyConsistent)
    StoreOps = StoreRels;
  else
    StoreOps = StoreBares;

  assert(isPowerOf2_32(Size) && Size <= 8 &&
         "unsupported size for atomic binary op!");

  LdrOpc = LoadOps[Log2_32(Size)];
  StrOpc = StoreOps[Log2_32(Size)];
}

// FIXME: AArch64::DTripleRegClass and AArch64::QTripleRegClass don't really
// have value type mapped, and they are both being defined as MVT::untyped.
// Without knowing the MVT type, MachineLICM::getRegisterClassIDAndCost
// would fail to figure out the register pressure correctly.
std::pair<const TargetRegisterClass*, uint8_t>
AArch64TargetLowering::findRepresentativeClass(MVT VT) const{
  const TargetRegisterClass *RRC = 0;
  uint8_t Cost = 1;
  switch (VT.SimpleTy) {
  default:
    return TargetLowering::findRepresentativeClass(VT);
  case MVT::v4i64:
    RRC = &AArch64::QPairRegClass;
    Cost = 2;
    break;
  case MVT::v8i64:
    RRC = &AArch64::QQuadRegClass;
    Cost = 4;
    break;
  }
  return std::make_pair(RRC, Cost);
}

MachineBasicBlock *
AArch64TargetLowering::emitAtomicBinary(MachineInstr *MI, MachineBasicBlock *BB,
                                        unsigned Size,
                                        unsigned BinOpcode) const {
  // This also handles ATOMIC_SWAP, indicated by BinOpcode==0.
  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();

  const BasicBlock *LLVM_BB = BB->getBasicBlock();
  MachineFunction *MF = BB->getParent();
  MachineFunction::iterator It = BB;
  ++It;

  unsigned dest = MI->getOperand(0).getReg();
  unsigned ptr = MI->getOperand(1).getReg();
  unsigned incr = MI->getOperand(2).getReg();
  AtomicOrdering Ord = static_cast<AtomicOrdering>(MI->getOperand(3).getImm());
  DebugLoc dl = MI->getDebugLoc();

  MachineRegisterInfo &MRI = BB->getParent()->getRegInfo();

  unsigned ldrOpc, strOpc;
  getExclusiveOperation(Size, Ord, ldrOpc, strOpc);

  MachineBasicBlock *loopMBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MachineBasicBlock *exitMBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MF->insert(It, loopMBB);
  MF->insert(It, exitMBB);

  // Transfer the remainder of BB and its successor edges to exitMBB.
  exitMBB->splice(exitMBB->begin(), BB,
                  llvm::next(MachineBasicBlock::iterator(MI)),
                  BB->end());
  exitMBB->transferSuccessorsAndUpdatePHIs(BB);

  const TargetRegisterClass *TRC
    = Size == 8 ? &AArch64::GPR64RegClass : &AArch64::GPR32RegClass;
  unsigned scratch = (!BinOpcode) ? incr : MRI.createVirtualRegister(TRC);

  //  thisMBB:
  //   ...
  //   fallthrough --> loopMBB
  BB->addSuccessor(loopMBB);

  //  loopMBB:
  //   ldxr dest, ptr
  //   <binop> scratch, dest, incr
  //   stxr stxr_status, scratch, ptr
  //   cbnz stxr_status, loopMBB
  //   fallthrough --> exitMBB
  BB = loopMBB;
  BuildMI(BB, dl, TII->get(ldrOpc), dest).addReg(ptr);
  if (BinOpcode) {
    // All arithmetic operations we'll be creating are designed to take an extra
    // shift or extend operand, which we can conveniently set to zero.

    // Operand order needs to go the other way for NAND.
    if (BinOpcode == AArch64::BICwww_lsl || BinOpcode == AArch64::BICxxx_lsl)
      BuildMI(BB, dl, TII->get(BinOpcode), scratch)
        .addReg(incr).addReg(dest).addImm(0);
    else
      BuildMI(BB, dl, TII->get(BinOpcode), scratch)
        .addReg(dest).addReg(incr).addImm(0);
  }

  // From the stxr, the register is GPR32; from the cmp it's GPR32wsp
  unsigned stxr_status = MRI.createVirtualRegister(&AArch64::GPR32RegClass);
  MRI.constrainRegClass(stxr_status, &AArch64::GPR32wspRegClass);

  BuildMI(BB, dl, TII->get(strOpc), stxr_status).addReg(scratch).addReg(ptr);
  BuildMI(BB, dl, TII->get(AArch64::CBNZw))
    .addReg(stxr_status).addMBB(loopMBB);

  BB->addSuccessor(loopMBB);
  BB->addSuccessor(exitMBB);

  //  exitMBB:
  //   ...
  BB = exitMBB;

  MI->eraseFromParent();   // The instruction is gone now.

  return BB;
}

MachineBasicBlock *
AArch64TargetLowering::emitAtomicBinaryMinMax(MachineInstr *MI,
                                              MachineBasicBlock *BB,
                                              unsigned Size,
                                              unsigned CmpOp,
                                              A64CC::CondCodes Cond) const {
  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();

  const BasicBlock *LLVM_BB = BB->getBasicBlock();
  MachineFunction *MF = BB->getParent();
  MachineFunction::iterator It = BB;
  ++It;

  unsigned dest = MI->getOperand(0).getReg();
  unsigned ptr = MI->getOperand(1).getReg();
  unsigned incr = MI->getOperand(2).getReg();
  AtomicOrdering Ord = static_cast<AtomicOrdering>(MI->getOperand(3).getImm());

  unsigned oldval = dest;
  DebugLoc dl = MI->getDebugLoc();

  MachineRegisterInfo &MRI = BB->getParent()->getRegInfo();
  const TargetRegisterClass *TRC, *TRCsp;
  if (Size == 8) {
    TRC = &AArch64::GPR64RegClass;
    TRCsp = &AArch64::GPR64xspRegClass;
  } else {
    TRC = &AArch64::GPR32RegClass;
    TRCsp = &AArch64::GPR32wspRegClass;
  }

  unsigned ldrOpc, strOpc;
  getExclusiveOperation(Size, Ord, ldrOpc, strOpc);

  MachineBasicBlock *loopMBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MachineBasicBlock *exitMBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MF->insert(It, loopMBB);
  MF->insert(It, exitMBB);

  // Transfer the remainder of BB and its successor edges to exitMBB.
  exitMBB->splice(exitMBB->begin(), BB,
                  llvm::next(MachineBasicBlock::iterator(MI)),
                  BB->end());
  exitMBB->transferSuccessorsAndUpdatePHIs(BB);

  unsigned scratch = MRI.createVirtualRegister(TRC);
  MRI.constrainRegClass(scratch, TRCsp);

  //  thisMBB:
  //   ...
  //   fallthrough --> loopMBB
  BB->addSuccessor(loopMBB);

  //  loopMBB:
  //   ldxr dest, ptr
  //   cmp incr, dest (, sign extend if necessary)
  //   csel scratch, dest, incr, cond
  //   stxr stxr_status, scratch, ptr
  //   cbnz stxr_status, loopMBB
  //   fallthrough --> exitMBB
  BB = loopMBB;
  BuildMI(BB, dl, TII->get(ldrOpc), dest).addReg(ptr);

  // Build compare and cmov instructions.
  MRI.constrainRegClass(incr, TRCsp);
  BuildMI(BB, dl, TII->get(CmpOp))
    .addReg(incr).addReg(oldval).addImm(0);

  BuildMI(BB, dl, TII->get(Size == 8 ? AArch64::CSELxxxc : AArch64::CSELwwwc),
          scratch)
    .addReg(oldval).addReg(incr).addImm(Cond);

  unsigned stxr_status = MRI.createVirtualRegister(&AArch64::GPR32RegClass);
  MRI.constrainRegClass(stxr_status, &AArch64::GPR32wspRegClass);

  BuildMI(BB, dl, TII->get(strOpc), stxr_status)
    .addReg(scratch).addReg(ptr);
  BuildMI(BB, dl, TII->get(AArch64::CBNZw))
    .addReg(stxr_status).addMBB(loopMBB);

  BB->addSuccessor(loopMBB);
  BB->addSuccessor(exitMBB);

  //  exitMBB:
  //   ...
  BB = exitMBB;

  MI->eraseFromParent();   // The instruction is gone now.

  return BB;
}

MachineBasicBlock *
AArch64TargetLowering::emitAtomicCmpSwap(MachineInstr *MI,
                                         MachineBasicBlock *BB,
                                         unsigned Size) const {
  unsigned dest    = MI->getOperand(0).getReg();
  unsigned ptr     = MI->getOperand(1).getReg();
  unsigned oldval  = MI->getOperand(2).getReg();
  unsigned newval  = MI->getOperand(3).getReg();
  AtomicOrdering Ord = static_cast<AtomicOrdering>(MI->getOperand(4).getImm());
  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
  DebugLoc dl = MI->getDebugLoc();

  MachineRegisterInfo &MRI = BB->getParent()->getRegInfo();
  const TargetRegisterClass *TRCsp;
  TRCsp = Size == 8 ? &AArch64::GPR64xspRegClass : &AArch64::GPR32wspRegClass;

  unsigned ldrOpc, strOpc;
  getExclusiveOperation(Size, Ord, ldrOpc, strOpc);

  MachineFunction *MF = BB->getParent();
  const BasicBlock *LLVM_BB = BB->getBasicBlock();
  MachineFunction::iterator It = BB;
  ++It; // insert the new blocks after the current block

  MachineBasicBlock *loop1MBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MachineBasicBlock *loop2MBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MachineBasicBlock *exitMBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MF->insert(It, loop1MBB);
  MF->insert(It, loop2MBB);
  MF->insert(It, exitMBB);

  // Transfer the remainder of BB and its successor edges to exitMBB.
  exitMBB->splice(exitMBB->begin(), BB,
                  llvm::next(MachineBasicBlock::iterator(MI)),
                  BB->end());
  exitMBB->transferSuccessorsAndUpdatePHIs(BB);

  //  thisMBB:
  //   ...
  //   fallthrough --> loop1MBB
  BB->addSuccessor(loop1MBB);

  // loop1MBB:
  //   ldxr dest, [ptr]
  //   cmp dest, oldval
  //   b.ne exitMBB
  BB = loop1MBB;
  BuildMI(BB, dl, TII->get(ldrOpc), dest).addReg(ptr);

  unsigned CmpOp = Size == 8 ? AArch64::CMPxx_lsl : AArch64::CMPww_lsl;
  MRI.constrainRegClass(dest, TRCsp);
  BuildMI(BB, dl, TII->get(CmpOp))
    .addReg(dest).addReg(oldval).addImm(0);
  BuildMI(BB, dl, TII->get(AArch64::Bcc))
    .addImm(A64CC::NE).addMBB(exitMBB);
  BB->addSuccessor(loop2MBB);
  BB->addSuccessor(exitMBB);

  // loop2MBB:
  //   strex stxr_status, newval, [ptr]
  //   cbnz stxr_status, loop1MBB
  BB = loop2MBB;
  unsigned stxr_status = MRI.createVirtualRegister(&AArch64::GPR32RegClass);
  MRI.constrainRegClass(stxr_status, &AArch64::GPR32wspRegClass);

  BuildMI(BB, dl, TII->get(strOpc), stxr_status).addReg(newval).addReg(ptr);
  BuildMI(BB, dl, TII->get(AArch64::CBNZw))
    .addReg(stxr_status).addMBB(loop1MBB);
  BB->addSuccessor(loop1MBB);
  BB->addSuccessor(exitMBB);

  //  exitMBB:
  //   ...
  BB = exitMBB;

  MI->eraseFromParent();   // The instruction is gone now.

  return BB;
}

MachineBasicBlock *
AArch64TargetLowering::EmitF128CSEL(MachineInstr *MI,
                                    MachineBasicBlock *MBB) const {
  // We materialise the F128CSEL pseudo-instruction using conditional branches
  // and loads, giving an instruciton sequence like:
  //     str q0, [sp]
  //     b.ne IfTrue
  //     b Finish
  // IfTrue:
  //     str q1, [sp]
  // Finish:
  //     ldr q0, [sp]
  //
  // Using virtual registers would probably not be beneficial since COPY
  // instructions are expensive for f128 (there's no actual instruction to
  // implement them).
  //
  // An alternative would be to do an integer-CSEL on some address. E.g.:
  //     mov x0, sp
  //     add x1, sp, #16
  //     str q0, [x0]
  //     str q1, [x1]
  //     csel x0, x0, x1, ne
  //     ldr q0, [x0]
  //
  // It's unclear which approach is actually optimal.
  const TargetInstrInfo *TII = getTargetMachine().getInstrInfo();
  MachineFunction *MF = MBB->getParent();
  const BasicBlock *LLVM_BB = MBB->getBasicBlock();
  DebugLoc DL = MI->getDebugLoc();
  MachineFunction::iterator It = MBB;
  ++It;

  unsigned DestReg = MI->getOperand(0).getReg();
  unsigned IfTrueReg = MI->getOperand(1).getReg();
  unsigned IfFalseReg = MI->getOperand(2).getReg();
  unsigned CondCode = MI->getOperand(3).getImm();
  bool NZCVKilled = MI->getOperand(4).isKill();

  MachineBasicBlock *TrueBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MachineBasicBlock *EndBB = MF->CreateMachineBasicBlock(LLVM_BB);
  MF->insert(It, TrueBB);
  MF->insert(It, EndBB);

  // Transfer rest of current basic-block to EndBB
  EndBB->splice(EndBB->begin(), MBB,
                llvm::next(MachineBasicBlock::iterator(MI)),
                MBB->end());
  EndBB->transferSuccessorsAndUpdatePHIs(MBB);

  // We need somewhere to store the f128 value needed.
  int ScratchFI = MF->getFrameInfo()->CreateSpillStackObject(16, 16);

  //     [... start of incoming MBB ...]
  //     str qIFFALSE, [sp]
  //     b.cc IfTrue
  //     b Done
  BuildMI(MBB, DL, TII->get(AArch64::LSFP128_STR))
    .addReg(IfFalseReg)
    .addFrameIndex(ScratchFI)
    .addImm(0);
  BuildMI(MBB, DL, TII->get(AArch64::Bcc))
    .addImm(CondCode)
    .addMBB(TrueBB);
  BuildMI(MBB, DL, TII->get(AArch64::Bimm))
    .addMBB(EndBB);
  MBB->addSuccessor(TrueBB);
  MBB->addSuccessor(EndBB);

  if (!NZCVKilled) {
    // NZCV is live-through TrueBB.
    TrueBB->addLiveIn(AArch64::NZCV);
    EndBB->addLiveIn(AArch64::NZCV);
  }

  // IfTrue:
  //     str qIFTRUE, [sp]
  BuildMI(TrueBB, DL, TII->get(AArch64::LSFP128_STR))
    .addReg(IfTrueReg)
    .addFrameIndex(ScratchFI)
    .addImm(0);

  // Note: fallthrough. We can rely on LLVM adding a branch if it reorders the
  // blocks.
  TrueBB->addSuccessor(EndBB);

  // Done:
  //     ldr qDEST, [sp]
  //     [... rest of incoming MBB ...]
  MachineInstr *StartOfEnd = EndBB->begin();
  BuildMI(*EndBB, StartOfEnd, DL, TII->get(AArch64::LSFP128_LDR), DestReg)
    .addFrameIndex(ScratchFI)
    .addImm(0);

  MI->eraseFromParent();
  return EndBB;
}

MachineBasicBlock *
AArch64TargetLowering::EmitInstrWithCustomInserter(MachineInstr *MI,
                                                 MachineBasicBlock *MBB) const {
  switch (MI->getOpcode()) {
  default: llvm_unreachable("Unhandled instruction with custom inserter");
  case AArch64::F128CSEL:
    return EmitF128CSEL(MI, MBB);
  case AArch64::ATOMIC_LOAD_ADD_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::ADDwww_lsl);
  case AArch64::ATOMIC_LOAD_ADD_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::ADDwww_lsl);
  case AArch64::ATOMIC_LOAD_ADD_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::ADDwww_lsl);
  case AArch64::ATOMIC_LOAD_ADD_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::ADDxxx_lsl);

  case AArch64::ATOMIC_LOAD_SUB_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::SUBwww_lsl);
  case AArch64::ATOMIC_LOAD_SUB_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::SUBwww_lsl);
  case AArch64::ATOMIC_LOAD_SUB_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::SUBwww_lsl);
  case AArch64::ATOMIC_LOAD_SUB_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::SUBxxx_lsl);

  case AArch64::ATOMIC_LOAD_AND_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::ANDwww_lsl);
  case AArch64::ATOMIC_LOAD_AND_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::ANDwww_lsl);
  case AArch64::ATOMIC_LOAD_AND_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::ANDwww_lsl);
  case AArch64::ATOMIC_LOAD_AND_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::ANDxxx_lsl);

  case AArch64::ATOMIC_LOAD_OR_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::ORRwww_lsl);
  case AArch64::ATOMIC_LOAD_OR_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::ORRwww_lsl);
  case AArch64::ATOMIC_LOAD_OR_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::ORRwww_lsl);
  case AArch64::ATOMIC_LOAD_OR_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::ORRxxx_lsl);

  case AArch64::ATOMIC_LOAD_XOR_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::EORwww_lsl);
  case AArch64::ATOMIC_LOAD_XOR_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::EORwww_lsl);
  case AArch64::ATOMIC_LOAD_XOR_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::EORwww_lsl);
  case AArch64::ATOMIC_LOAD_XOR_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::EORxxx_lsl);

  case AArch64::ATOMIC_LOAD_NAND_I8:
    return emitAtomicBinary(MI, MBB, 1, AArch64::BICwww_lsl);
  case AArch64::ATOMIC_LOAD_NAND_I16:
    return emitAtomicBinary(MI, MBB, 2, AArch64::BICwww_lsl);
  case AArch64::ATOMIC_LOAD_NAND_I32:
    return emitAtomicBinary(MI, MBB, 4, AArch64::BICwww_lsl);
  case AArch64::ATOMIC_LOAD_NAND_I64:
    return emitAtomicBinary(MI, MBB, 8, AArch64::BICxxx_lsl);

  case AArch64::ATOMIC_LOAD_MIN_I8:
    return emitAtomicBinaryMinMax(MI, MBB, 1, AArch64::CMPww_sxtb, A64CC::GT);
  case AArch64::ATOMIC_LOAD_MIN_I16:
    return emitAtomicBinaryMinMax(MI, MBB, 2, AArch64::CMPww_sxth, A64CC::GT);
  case AArch64::ATOMIC_LOAD_MIN_I32:
    return emitAtomicBinaryMinMax(MI, MBB, 4, AArch64::CMPww_lsl, A64CC::GT);
  case AArch64::ATOMIC_LOAD_MIN_I64:
    return emitAtomicBinaryMinMax(MI, MBB, 8, AArch64::CMPxx_lsl, A64CC::GT);

  case AArch64::ATOMIC_LOAD_MAX_I8:
    return emitAtomicBinaryMinMax(MI, MBB, 1, AArch64::CMPww_sxtb, A64CC::LT);
  case AArch64::ATOMIC_LOAD_MAX_I16:
    return emitAtomicBinaryMinMax(MI, MBB, 2, AArch64::CMPww_sxth, A64CC::LT);
  case AArch64::ATOMIC_LOAD_MAX_I32:
    return emitAtomicBinaryMinMax(MI, MBB, 4, AArch64::CMPww_lsl, A64CC::LT);
  case AArch64::ATOMIC_LOAD_MAX_I64:
    return emitAtomicBinaryMinMax(MI, MBB, 8, AArch64::CMPxx_lsl, A64CC::LT);

  case AArch64::ATOMIC_LOAD_UMIN_I8:
    return emitAtomicBinaryMinMax(MI, MBB, 1, AArch64::CMPww_uxtb, A64CC::HI);
  case AArch64::ATOMIC_LOAD_UMIN_I16:
    return emitAtomicBinaryMinMax(MI, MBB, 2, AArch64::CMPww_uxth, A64CC::HI);
  case AArch64::ATOMIC_LOAD_UMIN_I32:
    return emitAtomicBinaryMinMax(MI, MBB, 4, AArch64::CMPww_lsl, A64CC::HI);
  case AArch64::ATOMIC_LOAD_UMIN_I64:
    return emitAtomicBinaryMinMax(MI, MBB, 8, AArch64::CMPxx_lsl, A64CC::HI);

  case AArch64::ATOMIC_LOAD_UMAX_I8:
    return emitAtomicBinaryMinMax(MI, MBB, 1, AArch64::CMPww_uxtb, A64CC::LO);
  case AArch64::ATOMIC_LOAD_UMAX_I16:
    return emitAtomicBinaryMinMax(MI, MBB, 2, AArch64::CMPww_uxth, A64CC::LO);
  case AArch64::ATOMIC_LOAD_UMAX_I32:
    return emitAtomicBinaryMinMax(MI, MBB, 4, AArch64::CMPww_lsl, A64CC::LO);
  case AArch64::ATOMIC_LOAD_UMAX_I64:
    return emitAtomicBinaryMinMax(MI, MBB, 8, AArch64::CMPxx_lsl, A64CC::LO);

  case AArch64::ATOMIC_SWAP_I8:
    return emitAtomicBinary(MI, MBB, 1, 0);
  case AArch64::ATOMIC_SWAP_I16:
    return emitAtomicBinary(MI, MBB, 2, 0);
  case AArch64::ATOMIC_SWAP_I32:
    return emitAtomicBinary(MI, MBB, 4, 0);
  case AArch64::ATOMIC_SWAP_I64:
    return emitAtomicBinary(MI, MBB, 8, 0);

  case AArch64::ATOMIC_CMP_SWAP_I8:
    return emitAtomicCmpSwap(MI, MBB, 1);
  case AArch64::ATOMIC_CMP_SWAP_I16:
    return emitAtomicCmpSwap(MI, MBB, 2);
  case AArch64::ATOMIC_CMP_SWAP_I32:
    return emitAtomicCmpSwap(MI, MBB, 4);
  case AArch64::ATOMIC_CMP_SWAP_I64:
    return emitAtomicCmpSwap(MI, MBB, 8);
  }
}


const char *AArch64TargetLowering::getTargetNodeName(unsigned Opcode) const {
  switch (Opcode) {
  case AArch64ISD::BR_CC:          return "AArch64ISD::BR_CC";
  case AArch64ISD::Call:           return "AArch64ISD::Call";
  case AArch64ISD::FPMOV:          return "AArch64ISD::FPMOV";
  case AArch64ISD::GOTLoad:        return "AArch64ISD::GOTLoad";
  case AArch64ISD::BFI:            return "AArch64ISD::BFI";
  case AArch64ISD::EXTR:           return "AArch64ISD::EXTR";
  case AArch64ISD::Ret:            return "AArch64ISD::Ret";
  case AArch64ISD::SBFX:           return "AArch64ISD::SBFX";
  case AArch64ISD::SELECT_CC:      return "AArch64ISD::SELECT_CC";
  case AArch64ISD::SETCC:          return "AArch64ISD::SETCC";
  case AArch64ISD::TC_RETURN:      return "AArch64ISD::TC_RETURN";
  case AArch64ISD::THREAD_POINTER: return "AArch64ISD::THREAD_POINTER";
  case AArch64ISD::TLSDESCCALL:    return "AArch64ISD::TLSDESCCALL";
  case AArch64ISD::WrapperLarge:   return "AArch64ISD::WrapperLarge";
  case AArch64ISD::WrapperSmall:   return "AArch64ISD::WrapperSmall";

  case AArch64ISD::NEON_BSL:
    return "AArch64ISD::NEON_BSL";
  case AArch64ISD::NEON_MOVIMM:
    return "AArch64ISD::NEON_MOVIMM";
  case AArch64ISD::NEON_MVNIMM:
    return "AArch64ISD::NEON_MVNIMM";
  case AArch64ISD::NEON_FMOVIMM:
    return "AArch64ISD::NEON_FMOVIMM";
  case AArch64ISD::NEON_CMP:
    return "AArch64ISD::NEON_CMP";
  case AArch64ISD::NEON_CMPZ:
    return "AArch64ISD::NEON_CMPZ";
  case AArch64ISD::NEON_TST:
    return "AArch64ISD::NEON_TST";
  case AArch64ISD::NEON_QSHLs:
    return "AArch64ISD::NEON_QSHLs";
  case AArch64ISD::NEON_QSHLu:
    return "AArch64ISD::NEON_QSHLu";
  case AArch64ISD::NEON_VDUP:
    return "AArch64ISD::NEON_VDUP";
  case AArch64ISD::NEON_VDUPLANE:
    return "AArch64ISD::NEON_VDUPLANE";
  case AArch64ISD::NEON_REV16:
    return "AArch64ISD::NEON_REV16";
  case AArch64ISD::NEON_REV32:
    return "AArch64ISD::NEON_REV32";
  case AArch64ISD::NEON_REV64:
    return "AArch64ISD::NEON_REV64";
  case AArch64ISD::NEON_UZP1:
    return "AArch64ISD::NEON_UZP1";
  case AArch64ISD::NEON_UZP2:
    return "AArch64ISD::NEON_UZP2";
  case AArch64ISD::NEON_ZIP1:
    return "AArch64ISD::NEON_ZIP1";
  case AArch64ISD::NEON_ZIP2:
    return "AArch64ISD::NEON_ZIP2";
  case AArch64ISD::NEON_TRN1:
    return "AArch64ISD::NEON_TRN1";
  case AArch64ISD::NEON_TRN2:
    return "AArch64ISD::NEON_TRN2";
  case AArch64ISD::NEON_LD1_UPD:
    return "AArch64ISD::NEON_LD1_UPD";
  case AArch64ISD::NEON_LD2_UPD:
    return "AArch64ISD::NEON_LD2_UPD";
  case AArch64ISD::NEON_LD3_UPD:
    return "AArch64ISD::NEON_LD3_UPD";
  case AArch64ISD::NEON_LD4_UPD:
    return "AArch64ISD::NEON_LD4_UPD";
  case AArch64ISD::NEON_ST1_UPD:
    return "AArch64ISD::NEON_ST1_UPD";
  case AArch64ISD::NEON_ST2_UPD:
    return "AArch64ISD::NEON_ST2_UPD";
  case AArch64ISD::NEON_ST3_UPD:
    return "AArch64ISD::NEON_ST3_UPD";
  case AArch64ISD::NEON_ST4_UPD:
    return "AArch64ISD::NEON_ST4_UPD";
  case AArch64ISD::NEON_LD1x2_UPD:
    return "AArch64ISD::NEON_LD1x2_UPD";
  case AArch64ISD::NEON_LD1x3_UPD:
    return "AArch64ISD::NEON_LD1x3_UPD";
  case AArch64ISD::NEON_LD1x4_UPD:
    return "AArch64ISD::NEON_LD1x4_UPD";
  case AArch64ISD::NEON_ST1x2_UPD:
    return "AArch64ISD::NEON_ST1x2_UPD";
  case AArch64ISD::NEON_ST1x3_UPD:
    return "AArch64ISD::NEON_ST1x3_UPD";
  case AArch64ISD::NEON_ST1x4_UPD:
    return "AArch64ISD::NEON_ST1x4_UPD";
  case AArch64ISD::NEON_LD2DUP:
    return "AArch64ISD::NEON_LD2DUP";
  case AArch64ISD::NEON_LD3DUP:
    return "AArch64ISD::NEON_LD3DUP";
  case AArch64ISD::NEON_LD4DUP:
    return "AArch64ISD::NEON_LD4DUP";
  case AArch64ISD::NEON_LD2DUP_UPD:
    return "AArch64ISD::NEON_LD2DUP_UPD";
  case AArch64ISD::NEON_LD3DUP_UPD:
    return "AArch64ISD::NEON_LD3DUP_UPD";
  case AArch64ISD::NEON_LD4DUP_UPD:
    return "AArch64ISD::NEON_LD4DUP_UPD";
  case AArch64ISD::NEON_LD2LN_UPD:
    return "AArch64ISD::NEON_LD2LN_UPD";
  case AArch64ISD::NEON_LD3LN_UPD:
    return "AArch64ISD::NEON_LD3LN_UPD";
  case AArch64ISD::NEON_LD4LN_UPD:
    return "AArch64ISD::NEON_LD4LN_UPD";
  case AArch64ISD::NEON_ST2LN_UPD:
    return "AArch64ISD::NEON_ST2LN_UPD";
  case AArch64ISD::NEON_ST3LN_UPD:
    return "AArch64ISD::NEON_ST3LN_UPD";
  case AArch64ISD::NEON_ST4LN_UPD:
    return "AArch64ISD::NEON_ST4LN_UPD";
  case AArch64ISD::NEON_VEXTRACT:
    return "AArch64ISD::NEON_VEXTRACT";
  default:
    return NULL;
  }
}

static const uint16_t AArch64FPRArgRegs[] = {
  AArch64::Q0, AArch64::Q1, AArch64::Q2, AArch64::Q3,
  AArch64::Q4, AArch64::Q5, AArch64::Q6, AArch64::Q7
};
static const unsigned NumFPRArgRegs = llvm::array_lengthof(AArch64FPRArgRegs);

static const uint16_t AArch64ArgRegs[] = {
  AArch64::X0, AArch64::X1, AArch64::X2, AArch64::X3,
  AArch64::X4, AArch64::X5, AArch64::X6, AArch64::X7
};
static const unsigned NumArgRegs = llvm::array_lengthof(AArch64ArgRegs);

static bool CC_AArch64NoMoreRegs(unsigned ValNo, MVT ValVT, MVT LocVT,
                                 CCValAssign::LocInfo LocInfo,
                                 ISD::ArgFlagsTy ArgFlags, CCState &State) {
  // Mark all remaining general purpose registers as allocated. We don't
  // backtrack: if (for example) an i128 gets put on the stack, no subsequent
  // i64 will go in registers (C.11).
  for (unsigned i = 0; i < NumArgRegs; ++i)
    State.AllocateReg(AArch64ArgRegs[i]);

  return false;
}

#include "AArch64GenCallingConv.inc"

CCAssignFn *AArch64TargetLowering::CCAssignFnForNode(CallingConv::ID CC) const {

  switch(CC) {
  default: llvm_unreachable("Unsupported calling convention");
  case CallingConv::Fast:
  case CallingConv::C:
    return CC_A64_APCS;
  }
}

void
AArch64TargetLowering::SaveVarArgRegisters(CCState &CCInfo, SelectionDAG &DAG,
                                           SDLoc DL, SDValue &Chain) const {
  MachineFunction &MF = DAG.getMachineFunction();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  AArch64MachineFunctionInfo *FuncInfo
    = MF.getInfo<AArch64MachineFunctionInfo>();

  SmallVector<SDValue, 8> MemOps;

  unsigned FirstVariadicGPR = CCInfo.getFirstUnallocated(AArch64ArgRegs,
                                                         NumArgRegs);
  unsigned FirstVariadicFPR = CCInfo.getFirstUnallocated(AArch64FPRArgRegs,
                                                         NumFPRArgRegs);

  unsigned GPRSaveSize = 8 * (NumArgRegs - FirstVariadicGPR);
  int GPRIdx = 0;
  if (GPRSaveSize != 0) {
    GPRIdx = MFI->CreateStackObject(GPRSaveSize, 8, false);

    SDValue FIN = DAG.getFrameIndex(GPRIdx, getPointerTy());

    for (unsigned i = FirstVariadicGPR; i < NumArgRegs; ++i) {
      unsigned VReg = MF.addLiveIn(AArch64ArgRegs[i], &AArch64::GPR64RegClass);
      SDValue Val = DAG.getCopyFromReg(Chain, DL, VReg, MVT::i64);
      SDValue Store = DAG.getStore(Val.getValue(1), DL, Val, FIN,
                                   MachinePointerInfo::getStack(i * 8),
                                   false, false, 0);
      MemOps.push_back(Store);
      FIN = DAG.getNode(ISD::ADD, DL, getPointerTy(), FIN,
                        DAG.getConstant(8, getPointerTy()));
    }
  }

  if (getSubtarget()->hasFPARMv8()) {
  unsigned FPRSaveSize = 16 * (NumFPRArgRegs - FirstVariadicFPR);
  int FPRIdx = 0;
    // According to the AArch64 Procedure Call Standard, section B.1/B.3, we
    // can omit a register save area if we know we'll never use registers of
    // that class.
    if (FPRSaveSize != 0) {
      FPRIdx = MFI->CreateStackObject(FPRSaveSize, 16, false);

      SDValue FIN = DAG.getFrameIndex(FPRIdx, getPointerTy());

      for (unsigned i = FirstVariadicFPR; i < NumFPRArgRegs; ++i) {
        unsigned VReg = MF.addLiveIn(AArch64FPRArgRegs[i],
            &AArch64::FPR128RegClass);
        SDValue Val = DAG.getCopyFromReg(Chain, DL, VReg, MVT::f128);
        SDValue Store = DAG.getStore(Val.getValue(1), DL, Val, FIN,
            MachinePointerInfo::getStack(i * 16),
            false, false, 0);
        MemOps.push_back(Store);
        FIN = DAG.getNode(ISD::ADD, DL, getPointerTy(), FIN,
            DAG.getConstant(16, getPointerTy()));
      }
    }
    FuncInfo->setVariadicFPRIdx(FPRIdx);
    FuncInfo->setVariadicFPRSize(FPRSaveSize);
  }

  int StackIdx = MFI->CreateFixedObject(8, CCInfo.getNextStackOffset(), true);

  FuncInfo->setVariadicStackIdx(StackIdx);
  FuncInfo->setVariadicGPRIdx(GPRIdx);
  FuncInfo->setVariadicGPRSize(GPRSaveSize);

  if (!MemOps.empty()) {
    Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, &MemOps[0],
                        MemOps.size());
  }
}


SDValue
AArch64TargetLowering::LowerFormalArguments(SDValue Chain,
                                      CallingConv::ID CallConv, bool isVarArg,
                                      const SmallVectorImpl<ISD::InputArg> &Ins,
                                      SDLoc dl, SelectionDAG &DAG,
                                      SmallVectorImpl<SDValue> &InVals) const {
  MachineFunction &MF = DAG.getMachineFunction();
  AArch64MachineFunctionInfo *FuncInfo
    = MF.getInfo<AArch64MachineFunctionInfo>();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  bool TailCallOpt = MF.getTarget().Options.GuaranteedTailCallOpt;

  SmallVector<CCValAssign, 16> ArgLocs;
  CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
                 getTargetMachine(), ArgLocs, *DAG.getContext());
  CCInfo.AnalyzeFormalArguments(Ins, CCAssignFnForNode(CallConv));

  SmallVector<SDValue, 16> ArgValues;

  SDValue ArgValue;
  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
    CCValAssign &VA = ArgLocs[i];
    ISD::ArgFlagsTy Flags = Ins[i].Flags;

    if (Flags.isByVal()) {
      // Byval is used for small structs and HFAs in the PCS, but the system
      // should work in a non-compliant manner for larger structs.
      EVT PtrTy = getPointerTy();
      int Size = Flags.getByValSize();
      unsigned NumRegs = (Size + 7) / 8;

      unsigned FrameIdx = MFI->CreateFixedObject(8 * NumRegs,
                                                 VA.getLocMemOffset(),
                                                 false);
      SDValue FrameIdxN = DAG.getFrameIndex(FrameIdx, PtrTy);
      InVals.push_back(FrameIdxN);

      continue;
    } else if (VA.isRegLoc()) {
      MVT RegVT = VA.getLocVT();
      const TargetRegisterClass *RC = getRegClassFor(RegVT);
      unsigned Reg = MF.addLiveIn(VA.getLocReg(), RC);

      ArgValue = DAG.getCopyFromReg(Chain, dl, Reg, RegVT);
    } else { // VA.isRegLoc()
      assert(VA.isMemLoc());

      int FI = MFI->CreateFixedObject(VA.getLocVT().getSizeInBits()/8,
                                      VA.getLocMemOffset(), true);

      SDValue FIN = DAG.getFrameIndex(FI, getPointerTy());
      ArgValue = DAG.getLoad(VA.getLocVT(), dl, Chain, FIN,
                             MachinePointerInfo::getFixedStack(FI),
                             false, false, false, 0);


    }

    switch (VA.getLocInfo()) {
    default: llvm_unreachable("Unknown loc info!");
    case CCValAssign::Full: break;
    case CCValAssign::BCvt:
      ArgValue = DAG.getNode(ISD::BITCAST,dl, VA.getValVT(), ArgValue);
      break;
    case CCValAssign::SExt:
    case CCValAssign::ZExt:
    case CCValAssign::AExt: {
      unsigned DestSize = VA.getValVT().getSizeInBits();
      unsigned DestSubReg;

      switch (DestSize) {
      case 8: DestSubReg = AArch64::sub_8; break;
      case 16: DestSubReg = AArch64::sub_16; break;
      case 32: DestSubReg = AArch64::sub_32; break;
      case 64: DestSubReg = AArch64::sub_64; break;
      default: llvm_unreachable("Unexpected argument promotion");
      }

      ArgValue = SDValue(DAG.getMachineNode(TargetOpcode::EXTRACT_SUBREG, dl,
                                   VA.getValVT(), ArgValue,
                                   DAG.getTargetConstant(DestSubReg, MVT::i32)),
                         0);
      break;
    }
    }

    InVals.push_back(ArgValue);
  }

  if (isVarArg)
    SaveVarArgRegisters(CCInfo, DAG, dl, Chain);

  unsigned StackArgSize = CCInfo.getNextStackOffset();
  if (DoesCalleeRestoreStack(CallConv, TailCallOpt)) {
    // This is a non-standard ABI so by fiat I say we're allowed to make full
    // use of the stack area to be popped, which must be aligned to 16 bytes in
    // any case:
    StackArgSize = RoundUpToAlignment(StackArgSize, 16);

    // If we're expected to restore the stack (e.g. fastcc) then we'll be adding
    // a multiple of 16.
    FuncInfo->setArgumentStackToRestore(StackArgSize);

    // This realignment carries over to the available bytes below. Our own
    // callers will guarantee the space is free by giving an aligned value to
    // CALLSEQ_START.
  }
  // Even if we're not expected to free up the space, it's useful to know how
  // much is there while considering tail calls (because we can reuse it).
  FuncInfo->setBytesInStackArgArea(StackArgSize);

  return Chain;
}

SDValue
AArch64TargetLowering::LowerReturn(SDValue Chain,
                                   CallingConv::ID CallConv, bool isVarArg,
                                   const SmallVectorImpl<ISD::OutputArg> &Outs,
                                   const SmallVectorImpl<SDValue> &OutVals,
                                   SDLoc dl, SelectionDAG &DAG) const {
  // CCValAssign - represent the assignment of the return value to a location.
  SmallVector<CCValAssign, 16> RVLocs;

  // CCState - Info about the registers and stack slots.
  CCState CCInfo(CallConv, isVarArg, DAG.getMachineFunction(),
                 getTargetMachine(), RVLocs, *DAG.getContext());

  // Analyze outgoing return values.
  CCInfo.AnalyzeReturn(Outs, CCAssignFnForNode(CallConv));

  SDValue Flag;
  SmallVector<SDValue, 4> RetOps(1, Chain);

  for (unsigned i = 0, e = RVLocs.size(); i != e; ++i) {
    // PCS: "If the type, T, of the result of a function is such that
    // void func(T arg) would require that arg be passed as a value in a
    // register (or set of registers) according to the rules in 5.4, then the
    // result is returned in the same registers as would be used for such an
    // argument.
    //
    // Otherwise, the caller shall reserve a block of memory of sufficient
    // size and alignment to hold the result. The address of the memory block
    // shall be passed as an additional argument to the function in x8."
    //
    // This is implemented in two places. The register-return values are dealt
    // with here, more complex returns are passed as an sret parameter, which
    // means we don't have to worry about it during actual return.
    CCValAssign &VA = RVLocs[i];
    assert(VA.isRegLoc() && "Only register-returns should be created by PCS");


    SDValue Arg = OutVals[i];

    // There's no convenient note in the ABI about this as there is for normal
    // arguments, but it says return values are passed in the same registers as
    // an argument would be. I believe that includes the comments about
    // unspecified higher bits, putting the burden of widening on the *caller*
    // for return values.
    switch (VA.getLocInfo()) {
    default: llvm_unreachable("Unknown loc info");
    case CCValAssign::Full: break;
    case CCValAssign::SExt:
    case CCValAssign::ZExt:
    case CCValAssign::AExt:
      // Floating-point values should only be extended when they're going into
      // memory, which can't happen here so an integer extend is acceptable.
      Arg = DAG.getNode(ISD::ANY_EXTEND, dl, VA.getLocVT(), Arg);
      break;
    case CCValAssign::BCvt:
      Arg = DAG.getNode(ISD::BITCAST, dl, VA.getLocVT(), Arg);
      break;
    }

    Chain = DAG.getCopyToReg(Chain, dl, VA.getLocReg(), Arg, Flag);
    Flag = Chain.getValue(1);
    RetOps.push_back(DAG.getRegister(VA.getLocReg(), VA.getLocVT()));
  }

  RetOps[0] = Chain;  // Update chain.

  // Add the flag if we have it.
  if (Flag.getNode())
    RetOps.push_back(Flag);

  return DAG.getNode(AArch64ISD::Ret, dl, MVT::Other,
                     &RetOps[0], RetOps.size());
}

SDValue
AArch64TargetLowering::LowerCall(CallLoweringInfo &CLI,
                                 SmallVectorImpl<SDValue> &InVals) const {
  SelectionDAG &DAG                     = CLI.DAG;
  SDLoc &dl                             = CLI.DL;
  SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs;
  SmallVectorImpl<SDValue> &OutVals     = CLI.OutVals;
  SmallVectorImpl<ISD::InputArg> &Ins   = CLI.Ins;
  SDValue Chain                         = CLI.Chain;
  SDValue Callee                        = CLI.Callee;
  bool &IsTailCall                      = CLI.IsTailCall;
  CallingConv::ID CallConv              = CLI.CallConv;
  bool IsVarArg                         = CLI.IsVarArg;

  MachineFunction &MF = DAG.getMachineFunction();
  AArch64MachineFunctionInfo *FuncInfo
    = MF.getInfo<AArch64MachineFunctionInfo>();
  bool TailCallOpt = MF.getTarget().Options.GuaranteedTailCallOpt;
  bool IsStructRet = !Outs.empty() && Outs[0].Flags.isSRet();
  bool IsSibCall = false;

  if (IsTailCall) {
    IsTailCall = IsEligibleForTailCallOptimization(Callee, CallConv,
                    IsVarArg, IsStructRet, MF.getFunction()->hasStructRetAttr(),
                                                   Outs, OutVals, Ins, DAG);

    // A sibling call is one where we're under the usual C ABI and not planning
    // to change that but can still do a tail call:
    if (!TailCallOpt && IsTailCall)
      IsSibCall = true;
  }

  SmallVector<CCValAssign, 16> ArgLocs;
  CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(),
                 getTargetMachine(), ArgLocs, *DAG.getContext());
  CCInfo.AnalyzeCallOperands(Outs, CCAssignFnForNode(CallConv));

  // On AArch64 (and all other architectures I'm aware of) the most this has to
  // do is adjust the stack pointer.
  unsigned NumBytes = RoundUpToAlignment(CCInfo.getNextStackOffset(), 16);
  if (IsSibCall) {
    // Since we're not changing the ABI to make this a tail call, the memory
    // operands are already available in the caller's incoming argument space.
    NumBytes = 0;
  }

  // FPDiff is the byte offset of the call's argument area from the callee's.
  // Stores to callee stack arguments will be placed in FixedStackSlots offset
  // by this amount for a tail call. In a sibling call it must be 0 because the
  // caller will deallocate the entire stack and the callee still expects its
  // arguments to begin at SP+0. Completely unused for non-tail calls.
  int FPDiff = 0;

  if (IsTailCall && !IsSibCall) {
    unsigned NumReusableBytes = FuncInfo->getBytesInStackArgArea();

    // FPDiff will be negative if this tail call requires more space than we
    // would automatically have in our incoming argument space. Positive if we
    // can actually shrink the stack.
    FPDiff = NumReusableBytes - NumBytes;

    // The stack pointer must be 16-byte aligned at all times it's used for a
    // memory operation, which in practice means at *all* times and in
    // particular across call boundaries. Therefore our own arguments started at
    // a 16-byte aligned SP and the delta applied for the tail call should
    // satisfy the same constraint.
    assert(FPDiff % 16 == 0 && "unaligned stack on tail call");
  }

  if (!IsSibCall)
    Chain = DAG.getCALLSEQ_START(Chain, DAG.getIntPtrConstant(NumBytes, true),
                                 dl);

  SDValue StackPtr = DAG.getCopyFromReg(Chain, dl, AArch64::XSP,
                                        getPointerTy());

  SmallVector<SDValue, 8> MemOpChains;
  SmallVector<std::pair<unsigned, SDValue>, 8> RegsToPass;

  for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
    CCValAssign &VA = ArgLocs[i];
    ISD::ArgFlagsTy Flags = Outs[i].Flags;
    SDValue Arg = OutVals[i];

    // Callee does the actual widening, so all extensions just use an implicit
    // definition of the rest of the Loc. Aesthetically, this would be nicer as
    // an ANY_EXTEND, but that isn't valid for floating-point types and this
    // alternative works on integer types too.
    switch (VA.getLocInfo()) {
    default: llvm_unreachable("Unknown loc info!");
    case CCValAssign::Full: break;
    case CCValAssign::SExt:
    case CCValAssign::ZExt:
    case CCValAssign::AExt: {
      unsigned SrcSize = VA.getValVT().getSizeInBits();
      unsigned SrcSubReg;

      switch (SrcSize) {
      case 8: SrcSubReg = AArch64::sub_8; break;
      case 16: SrcSubReg = AArch64::sub_16; break;
      case 32: SrcSubReg = AArch64::sub_32; break;
      case 64: SrcSubReg = AArch64::sub_64; break;
      default: llvm_unreachable("Unexpected argument promotion");
      }

      Arg = SDValue(DAG.getMachineNode(TargetOpcode::INSERT_SUBREG, dl,
                                    VA.getLocVT(),
                                    DAG.getUNDEF(VA.getLocVT()),
                                    Arg,
                                    DAG.getTargetConstant(SrcSubReg, MVT::i32)),
                    0);

      break;
    }
    case CCValAssign::BCvt:
      Arg = DAG.getNode(ISD::BITCAST, dl, VA.getLocVT(), Arg);
      break;
    }

    if (VA.isRegLoc()) {
      // A normal register (sub-) argument. For now we just note it down because
      // we want to copy things into registers as late as possible to avoid
      // register-pressure (and possibly worse).
      RegsToPass.push_back(std::make_pair(VA.getLocReg(), Arg));
      continue;
    }

    assert(VA.isMemLoc() && "unexpected argument location");

    SDValue DstAddr;
    MachinePointerInfo DstInfo;
    if (IsTailCall) {
      uint32_t OpSize = Flags.isByVal() ? Flags.getByValSize() :
                                          VA.getLocVT().getSizeInBits();
      OpSize = (OpSize + 7) / 8;
      int32_t Offset = VA.getLocMemOffset() + FPDiff;
      int FI = MF.getFrameInfo()->CreateFixedObject(OpSize, Offset, true);

      DstAddr = DAG.getFrameIndex(FI, getPointerTy());
      DstInfo = MachinePointerInfo::getFixedStack(FI);

      // Make sure any stack arguments overlapping with where we're storing are
      // loaded before this eventual operation. Otherwise they'll be clobbered.
      Chain = addTokenForArgument(Chain, DAG, MF.getFrameInfo(), FI);
    } else {
      SDValue PtrOff = DAG.getIntPtrConstant(VA.getLocMemOffset());

      DstAddr = DAG.getNode(ISD::ADD, dl, getPointerTy(), StackPtr, PtrOff);
      DstInfo = MachinePointerInfo::getStack(VA.getLocMemOffset());
    }

    if (Flags.isByVal()) {
      SDValue SizeNode = DAG.getConstant(Flags.getByValSize(), MVT::i64);
      SDValue Cpy = DAG.getMemcpy(Chain, dl, DstAddr, Arg, SizeNode,
                                  Flags.getByValAlign(),
                                  /*isVolatile = */ false,
                                  /*alwaysInline = */ false,
                                  DstInfo, MachinePointerInfo(0));
      MemOpChains.push_back(Cpy);
    } else {
      // Normal stack argument, put it where it's needed.
      SDValue Store = DAG.getStore(Chain, dl, Arg, DstAddr, DstInfo,
                                   false, false, 0);
      MemOpChains.push_back(Store);
    }
  }

  // The loads and stores generated above shouldn't clash with each
  // other. Combining them with this TokenFactor notes that fact for the rest of
  // the backend.
  if (!MemOpChains.empty())
    Chain = DAG.getNode(ISD::TokenFactor, dl, MVT::Other,
                        &MemOpChains[0], MemOpChains.size());

  // Most of the rest of the instructions need to be glued together; we don't
  // want assignments to actual registers used by a call to be rearranged by a
  // well-meaning scheduler.
  SDValue InFlag;

  for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i) {
    Chain = DAG.getCopyToReg(Chain, dl, RegsToPass[i].first,
                             RegsToPass[i].second, InFlag);
    InFlag = Chain.getValue(1);
  }

  // The linker is responsible for inserting veneers when necessary to put a
  // function call destination in range, so we don't need to bother with a
  // wrapper here.
  if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
    const GlobalValue *GV = G->getGlobal();
    Callee = DAG.getTargetGlobalAddress(GV, dl, getPointerTy());
  } else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
    const char *Sym = S->getSymbol();
    Callee = DAG.getTargetExternalSymbol(Sym, getPointerTy());
  }

  // We don't usually want to end the call-sequence here because we would tidy
  // the frame up *after* the call, however in the ABI-changing tail-call case
  // we've carefully laid out the parameters so that when sp is reset they'll be
  // in the correct location.
  if (IsTailCall && !IsSibCall) {
    Chain = DAG.getCALLSEQ_END(Chain, DAG.getIntPtrConstant(NumBytes, true),
                               DAG.getIntPtrConstant(0, true), InFlag, dl);
    InFlag = Chain.getValue(1);
  }

  // We produce the following DAG scheme for the actual call instruction:
  //     (AArch64Call Chain, Callee, reg1, ..., regn, preserveMask, inflag?
  //
  // Most arguments aren't going to be used and just keep the values live as
  // far as LLVM is concerned. It's expected to be selected as simply "bl
  // callee" (for a direct, non-tail call).
  std::vector<SDValue> Ops;
  Ops.push_back(Chain);
  Ops.push_back(Callee);

  if (IsTailCall) {
    // Each tail call may have to adjust the stack by a different amount, so
    // this information must travel along with the operation for eventual
    // consumption by emitEpilogue.
    Ops.push_back(DAG.getTargetConstant(FPDiff, MVT::i32));
  }

  for (unsigned i = 0, e = RegsToPass.size(); i != e; ++i)
    Ops.push_back(DAG.getRegister(RegsToPass[i].first,
                                  RegsToPass[i].second.getValueType()));


  // Add a register mask operand representing the call-preserved registers. This
  // is used later in codegen to constrain register-allocation.
  const TargetRegisterInfo *TRI = getTargetMachine().getRegisterInfo();
  const uint32_t *Mask = TRI->getCallPreservedMask(CallConv);
  assert(Mask && "Missing call preserved mask for calling convention");
  Ops.push_back(DAG.getRegisterMask(Mask));

  // If we needed glue, put it in as the last argument.
  if (InFlag.getNode())
    Ops.push_back(InFlag);

  SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);

  if (IsTailCall) {
    return DAG.getNode(AArch64ISD::TC_RETURN, dl, NodeTys, &Ops[0], Ops.size());
  }

  Chain = DAG.getNode(AArch64ISD::Call, dl, NodeTys, &Ops[0], Ops.size());
  InFlag = Chain.getValue(1);

  // Now we can reclaim the stack, just as well do it before working out where
  // our return value is.
  if (!IsSibCall) {
    uint64_t CalleePopBytes
      = DoesCalleeRestoreStack(CallConv, TailCallOpt) ? NumBytes : 0;

    Chain = DAG.getCALLSEQ_END(Chain, DAG.getIntPtrConstant(NumBytes, true),
                               DAG.getIntPtrConstant(CalleePopBytes, true),
                               InFlag, dl);
    InFlag = Chain.getValue(1);
  }

  return LowerCallResult(Chain, InFlag, CallConv,
                         IsVarArg, Ins, dl, DAG, InVals);
}

SDValue
AArch64TargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
                                      CallingConv::ID CallConv, bool IsVarArg,
                                      const SmallVectorImpl<ISD::InputArg> &Ins,
                                      SDLoc dl, SelectionDAG &DAG,
                                      SmallVectorImpl<SDValue> &InVals) const {
  // Assign locations to each value returned by this call.
  SmallVector<CCValAssign, 16> RVLocs;
  CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(),
                 getTargetMachine(), RVLocs, *DAG.getContext());
  CCInfo.AnalyzeCallResult(Ins, CCAssignFnForNode(CallConv));

  for (unsigned i = 0; i != RVLocs.size(); ++i) {
    CCValAssign VA = RVLocs[i];

    // Return values that are too big to fit into registers should use an sret
    // pointer, so this can be a lot simpler than the main argument code.
    assert(VA.isRegLoc() && "Memory locations not expected for call return");

    SDValue Val = DAG.getCopyFromReg(Chain, dl, VA.getLocReg(), VA.getLocVT(),
                                     InFlag);
    Chain = Val.getValue(1);
    InFlag = Val.getValue(2);

    switch (VA.getLocInfo()) {
    default: llvm_unreachable("Unknown loc info!");
    case CCValAssign::Full: break;
    case CCValAssign::BCvt:
      Val = DAG.getNode(ISD::BITCAST, dl, VA.getValVT(), Val);
      break;
    case CCValAssign::ZExt:
    case CCValAssign::SExt:
    case CCValAssign::AExt:
      // Floating-point arguments only get extended/truncated if they're going
      // in memory, so using the integer operation is acceptable here.
      Val = DAG.getNode(ISD::TRUNCATE, dl, VA.getValVT(), Val);
      break;
    }

    InVals.push_back(Val);
  }

  return Chain;
}

bool
AArch64TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
                                    CallingConv::ID CalleeCC,
                                    bool IsVarArg,
                                    bool IsCalleeStructRet,
                                    bool IsCallerStructRet,
                                    const SmallVectorImpl<ISD::OutputArg> &Outs,
                                    const SmallVectorImpl<SDValue> &OutVals,
                                    const SmallVectorImpl<ISD::InputArg> &Ins,
                                    SelectionDAG& DAG) const {

  // For CallingConv::C this function knows whether the ABI needs
  // changing. That's not true for other conventions so they will have to opt in
  // manually.
  if (!IsTailCallConvention(CalleeCC) && CalleeCC != CallingConv::C)
    return false;

  const MachineFunction &MF = DAG.getMachineFunction();
  const Function *CallerF = MF.getFunction();
  CallingConv::ID CallerCC = CallerF->getCallingConv();
  bool CCMatch = CallerCC == CalleeCC;

  // Byval parameters hand the function a pointer directly into the stack area
  // we want to reuse during a tail call. Working around this *is* possible (see
  // X86) but less efficient and uglier in LowerCall.
  for (Function::const_arg_iterator i = CallerF->arg_begin(),
         e = CallerF->arg_end(); i != e; ++i)
    if (i->hasByValAttr())
      return false;

  if (getTargetMachine().Options.GuaranteedTailCallOpt) {
    if (IsTailCallConvention(CalleeCC) && CCMatch)
      return true;
    return false;
  }

  // Now we search for cases where we can use a tail call without changing the
  // ABI. Sibcall is used in some places (particularly gcc) to refer to this
  // concept.

  // I want anyone implementing a new calling convention to think long and hard
  // about this assert.
  assert((!IsVarArg || CalleeCC == CallingConv::C)
         && "Unexpected variadic calling convention");

  if (IsVarArg && !Outs.empty()) {
    // At least two cases here: if caller is fastcc then we can't have any
    // memory arguments (we'd be expected to clean up the stack afterwards). If
    // caller is C then we could potentially use its argument area.

    // FIXME: for now we take the most conservative of these in both cases:
    // disallow all variadic memory operands.
    SmallVector<CCValAssign, 16> ArgLocs;
    CCState CCInfo(CalleeCC, IsVarArg, DAG.getMachineFunction(),
                   getTargetMachine(), ArgLocs, *DAG.getContext());

    CCInfo.AnalyzeCallOperands(Outs, CCAssignFnForNode(CalleeCC));
    for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i)
      if (!ArgLocs[i].isRegLoc())
        return false;
  }

  // If the calling conventions do not match, then we'd better make sure the
  // results are returned in the same way as what the caller expects.
  if (!CCMatch) {
    SmallVector<CCValAssign, 16> RVLocs1;
    CCState CCInfo1(CalleeCC, false, DAG.getMachineFunction(),
                    getTargetMachine(), RVLocs1, *DAG.getContext());
    CCInfo1.AnalyzeCallResult(Ins, CCAssignFnForNode(CalleeCC));

    SmallVector<CCValAssign, 16> RVLocs2;
    CCState CCInfo2(CallerCC, false, DAG.getMachineFunction(),
                    getTargetMachine(), RVLocs2, *DAG.getContext());
    CCInfo2.AnalyzeCallResult(Ins, CCAssignFnForNode(CallerCC));

    if (RVLocs1.size() != RVLocs2.size())
      return false;
    for (unsigned i = 0, e = RVLocs1.size(); i != e; ++i) {
      if (RVLocs1[i].isRegLoc() != RVLocs2[i].isRegLoc())
        return false;
      if (RVLocs1[i].getLocInfo() != RVLocs2[i].getLocInfo())
        return false;
      if (RVLocs1[i].isRegLoc()) {
        if (RVLocs1[i].getLocReg() != RVLocs2[i].getLocReg())
          return false;
      } else {
        if (RVLocs1[i].getLocMemOffset() != RVLocs2[i].getLocMemOffset())
          return false;
      }
    }
  }

  // Nothing more to check if the callee is taking no arguments
  if (Outs.empty())
    return true;

  SmallVector<CCValAssign, 16> ArgLocs;
  CCState CCInfo(CalleeCC, IsVarArg, DAG.getMachineFunction(),
                 getTargetMachine(), ArgLocs, *DAG.getContext());

  CCInfo.AnalyzeCallOperands(Outs, CCAssignFnForNode(CalleeCC));

  const AArch64MachineFunctionInfo *FuncInfo
    = MF.getInfo<AArch64MachineFunctionInfo>();

  // If the stack arguments for this call would fit into our own save area then
  // the call can be made tail.
  return CCInfo.getNextStackOffset() <= FuncInfo->getBytesInStackArgArea();
}

bool AArch64TargetLowering::DoesCalleeRestoreStack(CallingConv::ID CallCC,
                                                   bool TailCallOpt) const {
  return CallCC == CallingConv::Fast && TailCallOpt;
}

bool AArch64TargetLowering::IsTailCallConvention(CallingConv::ID CallCC) const {
  return CallCC == CallingConv::Fast;
}

SDValue AArch64TargetLowering::addTokenForArgument(SDValue Chain,
                                                   SelectionDAG &DAG,
                                                   MachineFrameInfo *MFI,
                                                   int ClobberedFI) const {
  SmallVector<SDValue, 8> ArgChains;
  int64_t FirstByte = MFI->getObjectOffset(ClobberedFI);
  int64_t LastByte = FirstByte + MFI->getObjectSize(ClobberedFI) - 1;

  // Include the original chain at the beginning of the list. When this is
  // used by target LowerCall hooks, this helps legalize find the
  // CALLSEQ_BEGIN node.
  ArgChains.push_back(Chain);

  // Add a chain value for each stack argument corresponding
  for (SDNode::use_iterator U = DAG.getEntryNode().getNode()->use_begin(),
         UE = DAG.getEntryNode().getNode()->use_end(); U != UE; ++U)
    if (LoadSDNode *L = dyn_cast<LoadSDNode>(*U))
      if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(L->getBasePtr()))
        if (FI->getIndex() < 0) {
          int64_t InFirstByte = MFI->getObjectOffset(FI->getIndex());
          int64_t InLastByte = InFirstByte;
          InLastByte += MFI->getObjectSize(FI->getIndex()) - 1;

          if ((InFirstByte <= FirstByte && FirstByte <= InLastByte) ||
              (FirstByte <= InFirstByte && InFirstByte <= LastByte))
            ArgChains.push_back(SDValue(L, 1));
        }

   // Build a tokenfactor for all the chains.
   return DAG.getNode(ISD::TokenFactor, SDLoc(Chain), MVT::Other,
                      &ArgChains[0], ArgChains.size());
}

static A64CC::CondCodes IntCCToA64CC(ISD::CondCode CC) {
  switch (CC) {
  case ISD::SETEQ:  return A64CC::EQ;
  case ISD::SETGT:  return A64CC::GT;
  case ISD::SETGE:  return A64CC::GE;
  case ISD::SETLT:  return A64CC::LT;
  case ISD::SETLE:  return A64CC::LE;
  case ISD::SETNE:  return A64CC::NE;
  case ISD::SETUGT: return A64CC::HI;
  case ISD::SETUGE: return A64CC::HS;
  case ISD::SETULT: return A64CC::LO;
  case ISD::SETULE: return A64CC::LS;
  default: llvm_unreachable("Unexpected condition code");
  }
}

bool AArch64TargetLowering::isLegalICmpImmediate(int64_t Val) const {
  // icmp is implemented using adds/subs immediate, which take an unsigned
  // 12-bit immediate, optionally shifted left by 12 bits.

  // Symmetric by using adds/subs
  if (Val < 0)
    Val = -Val;

  return (Val & ~0xfff) == 0 || (Val & ~0xfff000) == 0;
}

SDValue AArch64TargetLowering::getSelectableIntSetCC(SDValue LHS, SDValue RHS,
                                        ISD::CondCode CC, SDValue &A64cc,
                                        SelectionDAG &DAG, SDLoc &dl) const {
  if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(RHS.getNode())) {
    int64_t C = 0;
    EVT VT = RHSC->getValueType(0);
    bool knownInvalid = false;

    // I'm not convinced the rest of LLVM handles these edge cases properly, but
    // we can at least get it right.
    if (isSignedIntSetCC(CC)) {
      C = RHSC->getSExtValue();
    } else if (RHSC->getZExtValue() > INT64_MAX) {
      // A 64-bit constant not representable by a signed 64-bit integer is far
      // too big to fit into a SUBS immediate anyway.
      knownInvalid = true;
    } else {
      C = RHSC->getZExtValue();
    }

    if (!knownInvalid && !isLegalICmpImmediate(C)) {
      // Constant does not fit, try adjusting it by one?
      switch (CC) {
      default: break;
      case ISD::SETLT:
      case ISD::SETGE:
        if (isLegalICmpImmediate(C-1)) {
          CC = (CC == ISD::SETLT) ? ISD::SETLE : ISD::SETGT;
          RHS = DAG.getConstant(C-1, VT);
        }
        break;
      case ISD::SETULT:
      case ISD::SETUGE:
        if (isLegalICmpImmediate(C-1)) {
          CC = (CC == ISD::SETULT) ? ISD::SETULE : ISD::SETUGT;
          RHS = DAG.getConstant(C-1, VT);
        }
        break;
      case ISD::SETLE:
      case ISD::SETGT:
        if (isLegalICmpImmediate(C+1)) {
          CC = (CC == ISD::SETLE) ? ISD::SETLT : ISD::SETGE;
          RHS = DAG.getConstant(C+1, VT);
        }
        break;
      case ISD::SETULE:
      case ISD::SETUGT:
        if (isLegalICmpImmediate(C+1)) {
          CC = (CC == ISD::SETULE) ? ISD::SETULT : ISD::SETUGE;
          RHS = DAG.getConstant(C+1, VT);
        }
        break;
      }
    }
  }

  A64CC::CondCodes CondCode = IntCCToA64CC(CC);
  A64cc = DAG.getConstant(CondCode, MVT::i32);
  return DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, LHS, RHS,
                     DAG.getCondCode(CC));
}

static A64CC::CondCodes FPCCToA64CC(ISD::CondCode CC,
                                    A64CC::CondCodes &Alternative) {
  A64CC::CondCodes CondCode = A64CC::Invalid;
  Alternative = A64CC::Invalid;

  switch (CC) {
  default: llvm_unreachable("Unknown FP condition!");
  case ISD::SETEQ:
  case ISD::SETOEQ: CondCode = A64CC::EQ; break;
  case ISD::SETGT:
  case ISD::SETOGT: CondCode = A64CC::GT; break;
  case ISD::SETGE:
  case ISD::SETOGE: CondCode = A64CC::GE; break;
  case ISD::SETOLT: CondCode = A64CC::MI; break;
  case ISD::SETOLE: CondCode = A64CC::LS; break;
  case ISD::SETONE: CondCode = A64CC::MI; Alternative = A64CC::GT; break;
  case ISD::SETO:   CondCode = A64CC::VC; break;
  case ISD::SETUO:  CondCode = A64CC::VS; break;
  case ISD::SETUEQ: CondCode = A64CC::EQ; Alternative = A64CC::VS; break;
  case ISD::SETUGT: CondCode = A64CC::HI; break;
  case ISD::SETUGE: CondCode = A64CC::PL; break;
  case ISD::SETLT:
  case ISD::SETULT: CondCode = A64CC::LT; break;
  case ISD::SETLE:
  case ISD::SETULE: CondCode = A64CC::LE; break;
  case ISD::SETNE:
  case ISD::SETUNE: CondCode = A64CC::NE; break;
  }
  return CondCode;
}

SDValue
AArch64TargetLowering::LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const {
  SDLoc DL(Op);
  EVT PtrVT = getPointerTy();
  const BlockAddress *BA = cast<BlockAddressSDNode>(Op)->getBlockAddress();

  switch(getTargetMachine().getCodeModel()) {
  case CodeModel::Small:
    // The most efficient code is PC-relative anyway for the small memory model,
    // so we don't need to worry about relocation model.
    return DAG.getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
                       DAG.getTargetBlockAddress(BA, PtrVT, 0,
                                                 AArch64II::MO_NO_FLAG),
                       DAG.getTargetBlockAddress(BA, PtrVT, 0,
                                                 AArch64II::MO_LO12),
                       DAG.getConstant(/*Alignment=*/ 4, MVT::i32));
  case CodeModel::Large:
    return DAG.getNode(
      AArch64ISD::WrapperLarge, DL, PtrVT,
      DAG.getTargetBlockAddress(BA, PtrVT, 0, AArch64II::MO_ABS_G3),
      DAG.getTargetBlockAddress(BA, PtrVT, 0, AArch64II::MO_ABS_G2_NC),
      DAG.getTargetBlockAddress(BA, PtrVT, 0, AArch64II::MO_ABS_G1_NC),
      DAG.getTargetBlockAddress(BA, PtrVT, 0, AArch64II::MO_ABS_G0_NC));
  default:
    llvm_unreachable("Only small and large code models supported now");
  }
}


// (BRCOND chain, val, dest)
SDValue
AArch64TargetLowering::LowerBRCOND(SDValue Op, SelectionDAG &DAG) const {
  SDLoc dl(Op);
  SDValue Chain = Op.getOperand(0);
  SDValue TheBit = Op.getOperand(1);
  SDValue DestBB = Op.getOperand(2);

  // AArch64 BooleanContents is the default UndefinedBooleanContent, which means
  // that as the consumer we are responsible for ignoring rubbish in higher
  // bits.
  TheBit = DAG.getNode(ISD::AND, dl, MVT::i32, TheBit,
                       DAG.getConstant(1, MVT::i32));

  SDValue A64CMP = DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, TheBit,
                               DAG.getConstant(0, TheBit.getValueType()),
                               DAG.getCondCode(ISD::SETNE));

  return DAG.getNode(AArch64ISD::BR_CC, dl, MVT::Other, Chain,
                     A64CMP, DAG.getConstant(A64CC::NE, MVT::i32),
                     DestBB);
}

// (BR_CC chain, condcode, lhs, rhs, dest)
SDValue
AArch64TargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
  SDLoc dl(Op);
  SDValue Chain = Op.getOperand(0);
  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(1))->get();
  SDValue LHS = Op.getOperand(2);
  SDValue RHS = Op.getOperand(3);
  SDValue DestBB = Op.getOperand(4);

  if (LHS.getValueType() == MVT::f128) {
    // f128 comparisons are lowered to runtime calls by a routine which sets
    // LHS, RHS and CC appropriately for the rest of this function to continue.
    softenSetCCOperands(DAG, MVT::f128, LHS, RHS, CC, dl);

    // If softenSetCCOperands returned a scalar, we need to compare the result
    // against zero to select between true and false values.
    if (RHS.getNode() == 0) {
      RHS = DAG.getConstant(0, LHS.getValueType());
      CC = ISD::SETNE;
    }
  }

  if (LHS.getValueType().isInteger()) {
    SDValue A64cc;

    // Integers are handled in a separate function because the combinations of
    // immediates and tests can get hairy and we may want to fiddle things.
    SDValue CmpOp = getSelectableIntSetCC(LHS, RHS, CC, A64cc, DAG, dl);

    return DAG.getNode(AArch64ISD::BR_CC, dl, MVT::Other,
                       Chain, CmpOp, A64cc, DestBB);
  }

  // Note that some LLVM floating-point CondCodes can't be lowered to a single
  // conditional branch, hence FPCCToA64CC can set a second test, where either
  // passing is sufficient.
  A64CC::CondCodes CondCode, Alternative = A64CC::Invalid;
  CondCode = FPCCToA64CC(CC, Alternative);
  SDValue A64cc = DAG.getConstant(CondCode, MVT::i32);
  SDValue SetCC = DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, LHS, RHS,
                              DAG.getCondCode(CC));
  SDValue A64BR_CC = DAG.getNode(AArch64ISD::BR_CC, dl, MVT::Other,
                                 Chain, SetCC, A64cc, DestBB);

  if (Alternative != A64CC::Invalid) {
    A64cc = DAG.getConstant(Alternative, MVT::i32);
    A64BR_CC = DAG.getNode(AArch64ISD::BR_CC, dl, MVT::Other,
                           A64BR_CC, SetCC, A64cc, DestBB);

  }

  return A64BR_CC;
}

SDValue
AArch64TargetLowering::LowerF128ToCall(SDValue Op, SelectionDAG &DAG,
                                       RTLIB::Libcall Call) const {
  ArgListTy Args;
  ArgListEntry Entry;
  for (unsigned i = 0, e = Op->getNumOperands(); i != e; ++i) {
    EVT ArgVT = Op.getOperand(i).getValueType();
    Type *ArgTy = ArgVT.getTypeForEVT(*DAG.getContext());
    Entry.Node = Op.getOperand(i); Entry.Ty = ArgTy;
    Entry.isSExt = false;
    Entry.isZExt = false;
    Args.push_back(Entry);
  }
  SDValue Callee = DAG.getExternalSymbol(getLibcallName(Call), getPointerTy());

  Type *RetTy = Op.getValueType().getTypeForEVT(*DAG.getContext());

  // By default, the input chain to this libcall is the entry node of the
  // function. If the libcall is going to be emitted as a tail call then
  // isUsedByReturnOnly will change it to the right chain if the return
  // node which is being folded has a non-entry input chain.
  SDValue InChain = DAG.getEntryNode();

  // isTailCall may be true since the callee does not reference caller stack
  // frame. Check if it's in the right position.
  SDValue TCChain = InChain;
  bool isTailCall = isInTailCallPosition(DAG, Op.getNode(), TCChain);
  if (isTailCall)
    InChain = TCChain;

  TargetLowering::
  CallLoweringInfo CLI(InChain, RetTy, false, false, false, false,
                    0, getLibcallCallingConv(Call), isTailCall,
                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
                    Callee, Args, DAG, SDLoc(Op));
  std::pair<SDValue, SDValue> CallInfo = LowerCallTo(CLI);

  if (!CallInfo.second.getNode())
    // It's a tailcall, return the chain (which is the DAG root).
    return DAG.getRoot();

  return CallInfo.first;
}

SDValue
AArch64TargetLowering::LowerFP_ROUND(SDValue Op, SelectionDAG &DAG) const {
  if (Op.getOperand(0).getValueType() != MVT::f128) {
    // It's legal except when f128 is involved
    return Op;
  }

  RTLIB::Libcall LC;
  LC  = RTLIB::getFPROUND(Op.getOperand(0).getValueType(), Op.getValueType());

  SDValue SrcVal = Op.getOperand(0);
  return makeLibCall(DAG, LC, Op.getValueType(), &SrcVal, 1,
                     /*isSigned*/ false, SDLoc(Op)).first;
}

SDValue
AArch64TargetLowering::LowerFP_EXTEND(SDValue Op, SelectionDAG &DAG) const {
  assert(Op.getValueType() == MVT::f128 && "Unexpected lowering");

  RTLIB::Libcall LC;
  LC  = RTLIB::getFPEXT(Op.getOperand(0).getValueType(), Op.getValueType());

  return LowerF128ToCall(Op, DAG, LC);
}

SDValue
AArch64TargetLowering::LowerFP_TO_INT(SDValue Op, SelectionDAG &DAG,
                                      bool IsSigned) const {
  if (Op.getOperand(0).getValueType() != MVT::f128) {
    // It's legal except when f128 is involved
    return Op;
  }

  RTLIB::Libcall LC;
  if (IsSigned)
    LC = RTLIB::getFPTOSINT(Op.getOperand(0).getValueType(), Op.getValueType());
  else
    LC = RTLIB::getFPTOUINT(Op.getOperand(0).getValueType(), Op.getValueType());

  return LowerF128ToCall(Op, DAG, LC);
}

SDValue AArch64TargetLowering::LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const{
  MachineFunction &MF = DAG.getMachineFunction();
  MachineFrameInfo *MFI = MF.getFrameInfo();
  MFI->setReturnAddressIsTaken(true);

  EVT VT = Op.getValueType();
  SDLoc dl(Op);
  unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
  if (Depth) {
    SDValue FrameAddr = LowerFRAMEADDR(Op, DAG);
    SDValue Offset = DAG.getConstant(8, MVT::i64);
    return DAG.getLoad(VT, dl, DAG.getEntryNode(),
                       DAG.getNode(ISD::ADD, dl, VT, FrameAddr, Offset),
                       MachinePointerInfo(), false, false, false, 0);
  }

  // Return X30, which contains the return address. Mark it an implicit live-in.
  unsigned Reg = MF.addLiveIn(AArch64::X30, getRegClassFor(MVT::i64));
  return DAG.getCopyFromReg(DAG.getEntryNode(), dl, Reg, MVT::i64);
}


SDValue AArch64TargetLowering::LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG)
                                              const {
  MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
  MFI->setFrameAddressIsTaken(true);

  EVT VT = Op.getValueType();
  SDLoc dl(Op);
  unsigned Depth = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
  unsigned FrameReg = AArch64::X29;
  SDValue FrameAddr = DAG.getCopyFromReg(DAG.getEntryNode(), dl, FrameReg, VT);
  while (Depth--)
    FrameAddr = DAG.getLoad(VT, dl, DAG.getEntryNode(), FrameAddr,
                            MachinePointerInfo(),
                            false, false, false, 0);
  return FrameAddr;
}

SDValue
AArch64TargetLowering::LowerGlobalAddressELFLarge(SDValue Op,
                                                  SelectionDAG &DAG) const {
  assert(getTargetMachine().getCodeModel() == CodeModel::Large);
  assert(getTargetMachine().getRelocationModel() == Reloc::Static);

  EVT PtrVT = getPointerTy();
  SDLoc dl(Op);
  const GlobalAddressSDNode *GN = cast<GlobalAddressSDNode>(Op);
  const GlobalValue *GV = GN->getGlobal();

  SDValue GlobalAddr = DAG.getNode(
      AArch64ISD::WrapperLarge, dl, PtrVT,
      DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, AArch64II::MO_ABS_G3),
      DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, AArch64II::MO_ABS_G2_NC),
      DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, AArch64II::MO_ABS_G1_NC),
      DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0, AArch64II::MO_ABS_G0_NC));

  if (GN->getOffset() != 0)
    return DAG.getNode(ISD::ADD, dl, PtrVT, GlobalAddr,
                       DAG.getConstant(GN->getOffset(), PtrVT));

  return GlobalAddr;
}

SDValue
AArch64TargetLowering::LowerGlobalAddressELFSmall(SDValue Op,
                                                  SelectionDAG &DAG) const {
  assert(getTargetMachine().getCodeModel() == CodeModel::Small);

  EVT PtrVT = getPointerTy();
  SDLoc dl(Op);
  const GlobalAddressSDNode *GN = cast<GlobalAddressSDNode>(Op);
  const GlobalValue *GV = GN->getGlobal();
  unsigned Alignment = GV->getAlignment();
  Reloc::Model RelocM = getTargetMachine().getRelocationModel();
  if (GV->isWeakForLinker() && GV->isDeclaration() && RelocM == Reloc::Static) {
    // Weak undefined symbols can't use ADRP/ADD pair since they should evaluate
    // to zero when they remain undefined. In PIC mode the GOT can take care of
    // this, but in absolute mode we use a constant pool load.
    SDValue PoolAddr;
    PoolAddr = DAG.getNode(AArch64ISD::WrapperSmall, dl, PtrVT,
                           DAG.getTargetConstantPool(GV, PtrVT, 0, 0,
                                                     AArch64II::MO_NO_FLAG),
                           DAG.getTargetConstantPool(GV, PtrVT, 0, 0,
                                                     AArch64II::MO_LO12),
                           DAG.getConstant(8, MVT::i32));
    SDValue GlobalAddr = DAG.getLoad(PtrVT, dl, DAG.getEntryNode(), PoolAddr,
                                     MachinePointerInfo::getConstantPool(),
                                     /*isVolatile=*/ false,
                                     /*isNonTemporal=*/ true,
                                     /*isInvariant=*/ true, 8);
    if (GN->getOffset() != 0)
      return DAG.getNode(ISD::ADD, dl, PtrVT, GlobalAddr,
                         DAG.getConstant(GN->getOffset(), PtrVT));

    return GlobalAddr;
  }

  if (Alignment == 0) {
    const PointerType *GVPtrTy = cast<PointerType>(GV->getType());
    if (GVPtrTy->getElementType()->isSized()) {
      Alignment
        = getDataLayout()->getABITypeAlignment(GVPtrTy->getElementType());
    } else {
      // Be conservative if we can't guess, not that it really matters:
      // functions and labels aren't valid for loads, and the methods used to
      // actually calculate an address work with any alignment.
      Alignment = 1;
    }
  }

  unsigned char HiFixup, LoFixup;
  bool UseGOT = getSubtarget()->GVIsIndirectSymbol(GV, RelocM);

  if (UseGOT) {
    HiFixup = AArch64II::MO_GOT;
    LoFixup = AArch64II::MO_GOT_LO12;
    Alignment = 8;
  } else {
    HiFixup = AArch64II::MO_NO_FLAG;
    LoFixup = AArch64II::MO_LO12;
  }

  // AArch64's small model demands the following sequence:
  // ADRP x0, somewhere
  // ADD x0, x0, #:lo12:somewhere ; (or LDR directly).
  SDValue GlobalRef = DAG.getNode(AArch64ISD::WrapperSmall, dl, PtrVT,
                                  DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0,
                                                             HiFixup),
                                  DAG.getTargetGlobalAddress(GV, dl, PtrVT, 0,
                                                             LoFixup),
                                  DAG.getConstant(Alignment, MVT::i32));

  if (UseGOT) {
    GlobalRef = DAG.getNode(AArch64ISD::GOTLoad, dl, PtrVT, DAG.getEntryNode(),
                            GlobalRef);
  }

  if (GN->getOffset() != 0)
    return DAG.getNode(ISD::ADD, dl, PtrVT, GlobalRef,
                       DAG.getConstant(GN->getOffset(), PtrVT));

  return GlobalRef;
}

SDValue
AArch64TargetLowering::LowerGlobalAddressELF(SDValue Op,
                                             SelectionDAG &DAG) const {
  // TableGen doesn't have easy access to the CodeModel or RelocationModel, so
  // we make those distinctions here.

  switch (getTargetMachine().getCodeModel()) {
  case CodeModel::Small:
    return LowerGlobalAddressELFSmall(Op, DAG);
  case CodeModel::Large:
    return LowerGlobalAddressELFLarge(Op, DAG);
  default:
    llvm_unreachable("Only small and large code models supported now");
  }
}

SDValue AArch64TargetLowering::LowerTLSDescCall(SDValue SymAddr,
                                                SDValue DescAddr,
                                                SDLoc DL,
                                                SelectionDAG &DAG) const {
  EVT PtrVT = getPointerTy();

  // The function we need to call is simply the first entry in the GOT for this
  // descriptor, load it in preparation.
  SDValue Func, Chain;
  Func = DAG.getNode(AArch64ISD::GOTLoad, DL, PtrVT, DAG.getEntryNode(),
                     DescAddr);

  // The function takes only one argument: the address of the descriptor itself
  // in X0.
  SDValue Glue;
  Chain = DAG.getCopyToReg(DAG.getEntryNode(), DL, AArch64::X0, DescAddr, Glue);
  Glue = Chain.getValue(1);

  // Finally, there's a special calling-convention which means that the lookup
  // must preserve all registers (except X0, obviously).
  const TargetRegisterInfo *TRI  = getTargetMachine().getRegisterInfo();
  const AArch64RegisterInfo *A64RI
    = static_cast<const AArch64RegisterInfo *>(TRI);
  const uint32_t *Mask = A64RI->getTLSDescCallPreservedMask();

  // We're now ready to populate the argument list, as with a normal call:
  std::vector<SDValue> Ops;
  Ops.push_back(Chain);
  Ops.push_back(Func);
  Ops.push_back(SymAddr);
  Ops.push_back(DAG.getRegister(AArch64::X0, PtrVT));
  Ops.push_back(DAG.getRegisterMask(Mask));
  Ops.push_back(Glue);

  SDVTList NodeTys = DAG.getVTList(MVT::Other, MVT::Glue);
  Chain = DAG.getNode(AArch64ISD::TLSDESCCALL, DL, NodeTys, &Ops[0],
                      Ops.size());
  Glue = Chain.getValue(1);

  // After the call, the offset from TPIDR_EL0 is in X0, copy it out and pass it
  // back to the generic handling code.
  return DAG.getCopyFromReg(Chain, DL, AArch64::X0, PtrVT, Glue);
}

SDValue
AArch64TargetLowering::LowerGlobalTLSAddress(SDValue Op,
                                             SelectionDAG &DAG) const {
  assert(getSubtarget()->isTargetELF() &&
         "TLS not implemented for non-ELF targets");
  assert(getTargetMachine().getCodeModel() == CodeModel::Small
         && "TLS only supported in small memory model");
  const GlobalAddressSDNode *GA = cast<GlobalAddressSDNode>(Op);

  TLSModel::Model Model = getTargetMachine().getTLSModel(GA->getGlobal());

  SDValue TPOff;
  EVT PtrVT = getPointerTy();
  SDLoc DL(Op);
  const GlobalValue *GV = GA->getGlobal();

  SDValue ThreadBase = DAG.getNode(AArch64ISD::THREAD_POINTER, DL, PtrVT);

  if (Model == TLSModel::InitialExec) {
    TPOff = DAG.getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
                        DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0,
                                                   AArch64II::MO_GOTTPREL),
                        DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0,
                                                   AArch64II::MO_GOTTPREL_LO12),
                        DAG.getConstant(8, MVT::i32));
    TPOff = DAG.getNode(AArch64ISD::GOTLoad, DL, PtrVT, DAG.getEntryNode(),
                        TPOff);
  } else if (Model == TLSModel::LocalExec) {
    SDValue HiVar = DAG.getTargetGlobalAddress(GV, DL, MVT::i64, 0,
                                               AArch64II::MO_TPREL_G1);
    SDValue LoVar = DAG.getTargetGlobalAddress(GV, DL, MVT::i64, 0,
                                               AArch64II::MO_TPREL_G0_NC);

    TPOff = SDValue(DAG.getMachineNode(AArch64::MOVZxii, DL, PtrVT, HiVar,
                                       DAG.getTargetConstant(1, MVT::i32)), 0);
    TPOff = SDValue(DAG.getMachineNode(AArch64::MOVKxii, DL, PtrVT,
                                       TPOff, LoVar,
                                       DAG.getTargetConstant(0, MVT::i32)), 0);
  } else if (Model == TLSModel::GeneralDynamic) {
    // Accesses used in this sequence go via the TLS descriptor which lives in
    // the GOT. Prepare an address we can use to handle this.
    SDValue HiDesc = DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0,
                                                AArch64II::MO_TLSDESC);
    SDValue LoDesc = DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0,
                                                AArch64II::MO_TLSDESC_LO12);
    SDValue DescAddr = DAG.getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
                                   HiDesc, LoDesc,
                                   DAG.getConstant(8, MVT::i32));
    SDValue SymAddr = DAG.getTargetGlobalAddress(GV, DL, PtrVT, 0);

    TPOff = LowerTLSDescCall(SymAddr, DescAddr, DL, DAG);
  } else if (Model == TLSModel::LocalDynamic) {
    // Local-dynamic accesses proceed in two phases. A general-dynamic TLS
    // descriptor call against the special symbol _TLS_MODULE_BASE_ to calculate
    // the beginning of the module's TLS region, followed by a DTPREL offset
    // calculation.

    // These accesses will need deduplicating if there's more than one.
    AArch64MachineFunctionInfo* MFI = DAG.getMachineFunction()
      .getInfo<AArch64MachineFunctionInfo>();
    MFI->incNumLocalDynamicTLSAccesses();


    // Get the location of _TLS_MODULE_BASE_:
    SDValue HiDesc = DAG.getTargetExternalSymbol("_TLS_MODULE_BASE_", PtrVT,
                                                AArch64II::MO_TLSDESC);
    SDValue LoDesc = DAG.getTargetExternalSymbol("_TLS_MODULE_BASE_", PtrVT,
                                                AArch64II::MO_TLSDESC_LO12);
    SDValue DescAddr = DAG.getNode(AArch64ISD::WrapperSmall, DL, PtrVT,
                                   HiDesc, LoDesc,
                                   DAG.getConstant(8, MVT::i32));
    SDValue SymAddr = DAG.getTargetExternalSymbol("_TLS_MODULE_BASE_", PtrVT);

    ThreadBase = LowerTLSDescCall(SymAddr, DescAddr, DL, DAG);

    // Get the variable's offset from _TLS_MODULE_BASE_
    SDValue HiVar = DAG.getTargetGlobalAddress(GV, DL, MVT::i64, 0,
                                               AArch64II::MO_DTPREL_G1);
    SDValue LoVar = DAG.getTargetGlobalAddress(GV, DL, MVT::i64, 0,
                                               AArch64II::MO_DTPREL_G0_NC);

    TPOff = SDValue(DAG.getMachineNode(AArch64::MOVZxii, DL, PtrVT, HiVar,
                                       DAG.getTargetConstant(0, MVT::i32)), 0);
    TPOff = SDValue(DAG.getMachineNode(AArch64::MOVKxii, DL, PtrVT,
                                       TPOff, LoVar,
                                       DAG.getTargetConstant(0, MVT::i32)), 0);
  } else
      llvm_unreachable("Unsupported TLS access model");


  return DAG.getNode(ISD::ADD, DL, PtrVT, ThreadBase, TPOff);
}

SDValue
AArch64TargetLowering::LowerINT_TO_FP(SDValue Op, SelectionDAG &DAG,
                                      bool IsSigned) const {
  if (Op.getValueType() != MVT::f128) {
    // Legal for everything except f128.
    return Op;
  }

  RTLIB::Libcall LC;
  if (IsSigned)
    LC = RTLIB::getSINTTOFP(Op.getOperand(0).getValueType(), Op.getValueType());
  else
    LC = RTLIB::getUINTTOFP(Op.getOperand(0).getValueType(), Op.getValueType());

  return LowerF128ToCall(Op, DAG, LC);
}


SDValue
AArch64TargetLowering::LowerJumpTable(SDValue Op, SelectionDAG &DAG) const {
  JumpTableSDNode *JT = cast<JumpTableSDNode>(Op);
  SDLoc dl(JT);
  EVT PtrVT = getPointerTy();

  // When compiling PIC, jump tables get put in the code section so a static
  // relocation-style is acceptable for both cases.
  switch (getTargetMachine().getCodeModel()) {
  case CodeModel::Small:
    return DAG.getNode(AArch64ISD::WrapperSmall, dl, PtrVT,
                       DAG.getTargetJumpTable(JT->getIndex(), PtrVT),
                       DAG.getTargetJumpTable(JT->getIndex(), PtrVT,
                                              AArch64II::MO_LO12),
                       DAG.getConstant(1, MVT::i32));
  case CodeModel::Large:
    return DAG.getNode(
      AArch64ISD::WrapperLarge, dl, PtrVT,
      DAG.getTargetJumpTable(JT->getIndex(), PtrVT, AArch64II::MO_ABS_G3),
      DAG.getTargetJumpTable(JT->getIndex(), PtrVT, AArch64II::MO_ABS_G2_NC),
      DAG.getTargetJumpTable(JT->getIndex(), PtrVT, AArch64II::MO_ABS_G1_NC),
      DAG.getTargetJumpTable(JT->getIndex(), PtrVT, AArch64II::MO_ABS_G0_NC));
  default:
    llvm_unreachable("Only small and large code models supported now");
  }
}

// (SELECT_CC lhs, rhs, iftrue, iffalse, condcode)
SDValue
AArch64TargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const {
  SDLoc dl(Op);
  SDValue LHS = Op.getOperand(0);
  SDValue RHS = Op.getOperand(1);
  SDValue IfTrue = Op.getOperand(2);
  SDValue IfFalse = Op.getOperand(3);
  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();

  if (LHS.getValueType() == MVT::f128) {
    // f128 comparisons are lowered to libcalls, but slot in nicely here
    // afterwards.
    softenSetCCOperands(DAG, MVT::f128, LHS, RHS, CC, dl);

    // If softenSetCCOperands returned a scalar, we need to compare the result
    // against zero to select between true and false values.
    if (RHS.getNode() == 0) {
      RHS = DAG.getConstant(0, LHS.getValueType());
      CC = ISD::SETNE;
    }
  }

  if (LHS.getValueType().isInteger()) {
    SDValue A64cc;

    // Integers are handled in a separate function because the combinations of
    // immediates and tests can get hairy and we may want to fiddle things.
    SDValue CmpOp = getSelectableIntSetCC(LHS, RHS, CC, A64cc, DAG, dl);

    return DAG.getNode(AArch64ISD::SELECT_CC, dl, Op.getValueType(),
                       CmpOp, IfTrue, IfFalse, A64cc);
  }

  // Note that some LLVM floating-point CondCodes can't be lowered to a single
  // conditional branch, hence FPCCToA64CC can set a second test, where either
  // passing is sufficient.
  A64CC::CondCodes CondCode, Alternative = A64CC::Invalid;
  CondCode = FPCCToA64CC(CC, Alternative);
  SDValue A64cc = DAG.getConstant(CondCode, MVT::i32);
  SDValue SetCC = DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, LHS, RHS,
                              DAG.getCondCode(CC));
  SDValue A64SELECT_CC = DAG.getNode(AArch64ISD::SELECT_CC, dl,
                                     Op.getValueType(),
                                     SetCC, IfTrue, IfFalse, A64cc);

  if (Alternative != A64CC::Invalid) {
    A64cc = DAG.getConstant(Alternative, MVT::i32);
    A64SELECT_CC = DAG.getNode(AArch64ISD::SELECT_CC, dl, Op.getValueType(),
                               SetCC, IfTrue, A64SELECT_CC, A64cc);

  }

  return A64SELECT_CC;
}

// (SELECT testbit, iftrue, iffalse)
SDValue
AArch64TargetLowering::LowerSELECT(SDValue Op, SelectionDAG &DAG) const {
  SDLoc dl(Op);
  SDValue TheBit = Op.getOperand(0);
  SDValue IfTrue = Op.getOperand(1);
  SDValue IfFalse = Op.getOperand(2);

  // AArch64 BooleanContents is the default UndefinedBooleanContent, which means
  // that as the consumer we are responsible for ignoring rubbish in higher
  // bits.
  TheBit = DAG.getNode(ISD::AND, dl, MVT::i32, TheBit,
                       DAG.getConstant(1, MVT::i32));
  SDValue A64CMP = DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, TheBit,
                               DAG.getConstant(0, TheBit.getValueType()),
                               DAG.getCondCode(ISD::SETNE));

  return DAG.getNode(AArch64ISD::SELECT_CC, dl, Op.getValueType(),
                     A64CMP, IfTrue, IfFalse,
                     DAG.getConstant(A64CC::NE, MVT::i32));
}

static SDValue LowerVectorSETCC(SDValue Op, SelectionDAG &DAG) {
  SDLoc DL(Op);
  SDValue LHS = Op.getOperand(0);
  SDValue RHS = Op.getOperand(1);
  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
  EVT VT = Op.getValueType();
  bool Invert = false;
  SDValue Op0, Op1;
  unsigned Opcode;

  if (LHS.getValueType().isInteger()) {

    // Attempt to use Vector Integer Compare Mask Test instruction.
    // TST = icmp ne (and (op0, op1), zero).
    if (CC == ISD::SETNE) {
      if (((LHS.getOpcode() == ISD::AND) &&
           ISD::isBuildVectorAllZeros(RHS.getNode())) ||
          ((RHS.getOpcode() == ISD::AND) &&
           ISD::isBuildVectorAllZeros(LHS.getNode()))) {

        SDValue AndOp = (LHS.getOpcode() == ISD::AND) ? LHS : RHS;
        SDValue NewLHS = DAG.getNode(ISD::BITCAST, DL, VT, AndOp.getOperand(0));
        SDValue NewRHS = DAG.getNode(ISD::BITCAST, DL, VT, AndOp.getOperand(1));
        return DAG.getNode(AArch64ISD::NEON_TST, DL, VT, NewLHS, NewRHS);
      }
    }

    // Attempt to use Vector Integer Compare Mask against Zero instr (Signed).
    // Note: Compare against Zero does not support unsigned predicates.
    if ((ISD::isBuildVectorAllZeros(RHS.getNode()) ||
         ISD::isBuildVectorAllZeros(LHS.getNode())) &&
        !isUnsignedIntSetCC(CC)) {

      // If LHS is the zero value, swap operands and CondCode.
      if (ISD::isBuildVectorAllZeros(LHS.getNode())) {
        CC = getSetCCSwappedOperands(CC);
        Op0 = RHS;
      } else
        Op0 = LHS;

      // Ensure valid CondCode for Compare Mask against Zero instruction:
      // EQ, GE, GT, LE, LT.
      if (ISD::SETNE == CC) {
        Invert = true;
        CC = ISD::SETEQ;
      }

      // Using constant type to differentiate integer and FP compares with zero.
      Op1 = DAG.getConstant(0, MVT::i32);
      Opcode = AArch64ISD::NEON_CMPZ;

    } else {
      // Attempt to use Vector Integer Compare Mask instr (Signed/Unsigned).
      // Ensure valid CondCode for Compare Mask instr: EQ, GE, GT, UGE, UGT.
      bool Swap = false;
      switch (CC) {
      default:
        llvm_unreachable("Illegal integer comparison.");
      case ISD::SETEQ:
      case ISD::SETGT:
      case ISD::SETGE:
      case ISD::SETUGT:
      case ISD::SETUGE:
        break;
      case ISD::SETNE:
        Invert = true;
        CC = ISD::SETEQ;
        break;
      case ISD::SETULT:
      case ISD::SETULE:
      case ISD::SETLT:
      case ISD::SETLE:
        Swap = true;
        CC = getSetCCSwappedOperands(CC);
      }

      if (Swap)
        std::swap(LHS, RHS);

      Opcode = AArch64ISD::NEON_CMP;
      Op0 = LHS;
      Op1 = RHS;
    }

    // Generate Compare Mask instr or Compare Mask against Zero instr.
    SDValue NeonCmp =
        DAG.getNode(Opcode, DL, VT, Op0, Op1, DAG.getCondCode(CC));

    if (Invert)
      NeonCmp = DAG.getNOT(DL, NeonCmp, VT);

    return NeonCmp;
  }

  // Now handle Floating Point cases.
  // Attempt to use Vector Floating Point Compare Mask against Zero instruction.
  if (ISD::isBuildVectorAllZeros(RHS.getNode()) ||
      ISD::isBuildVectorAllZeros(LHS.getNode())) {

    // If LHS is the zero value, swap operands and CondCode.
    if (ISD::isBuildVectorAllZeros(LHS.getNode())) {
      CC = getSetCCSwappedOperands(CC);
      Op0 = RHS;
    } else
      Op0 = LHS;

    // Using constant type to differentiate integer and FP compares with zero.
    Op1 = DAG.getConstantFP(0, MVT::f32);
    Opcode = AArch64ISD::NEON_CMPZ;
  } else {
    // Attempt to use Vector Floating Point Compare Mask instruction.
    Op0 = LHS;
    Op1 = RHS;
    Opcode = AArch64ISD::NEON_CMP;
  }

  SDValue NeonCmpAlt;
  // Some register compares have to be implemented with swapped CC and operands,
  // e.g.: OLT implemented as OGT with swapped operands.
  bool SwapIfRegArgs = false;

  // Ensure valid CondCode for FP Compare Mask against Zero instruction:
  // EQ, GE, GT, LE, LT.
  // And ensure valid CondCode for FP Compare Mask instruction: EQ, GE, GT.
  switch (CC) {
  default:
    llvm_unreachable("Illegal FP comparison");
  case ISD::SETUNE:
  case ISD::SETNE:
    Invert = true; // Fallthrough
  case ISD::SETOEQ:
  case ISD::SETEQ:
    CC = ISD::SETEQ;
    break;
  case ISD::SETOLT:
  case ISD::SETLT:
    CC = ISD::SETLT;
    SwapIfRegArgs = true;
    break;
  case ISD::SETOGT:
  case ISD::SETGT:
    CC = ISD::SETGT;
    break;
  case ISD::SETOLE:
  case ISD::SETLE:
    CC = ISD::SETLE;
    SwapIfRegArgs = true;
    break;
  case ISD::SETOGE:
  case ISD::SETGE:
    CC = ISD::SETGE;
    break;
  case ISD::SETUGE:
    Invert = true;
    CC = ISD::SETLT;
    SwapIfRegArgs = true;
    break;
  case ISD::SETULE:
    Invert = true;
    CC = ISD::SETGT;
    break;
  case ISD::SETUGT:
    Invert = true;
    CC = ISD::SETLE;
    SwapIfRegArgs = true;
    break;
  case ISD::SETULT:
    Invert = true;
    CC = ISD::SETGE;
    break;
  case ISD::SETUEQ:
    Invert = true; // Fallthrough
  case ISD::SETONE:
    // Expand this to (OGT |OLT).
    NeonCmpAlt =
        DAG.getNode(Opcode, DL, VT, Op0, Op1, DAG.getCondCode(ISD::SETGT));
    CC = ISD::SETLT;
    SwapIfRegArgs = true;
    break;
  case ISD::SETUO:
    Invert = true; // Fallthrough
  case ISD::SETO:
    // Expand this to (OGE | OLT).
    NeonCmpAlt =
        DAG.getNode(Opcode, DL, VT, Op0, Op1, DAG.getCondCode(ISD::SETGE));
    CC = ISD::SETLT;
    SwapIfRegArgs = true;
    break;
  }

  if (Opcode == AArch64ISD::NEON_CMP && SwapIfRegArgs) {
    CC = getSetCCSwappedOperands(CC);
    std::swap(Op0, Op1);
  }

  // Generate FP Compare Mask instr or FP Compare Mask against Zero instr
  SDValue NeonCmp = DAG.getNode(Opcode, DL, VT, Op0, Op1, DAG.getCondCode(CC));

  if (NeonCmpAlt.getNode())
    NeonCmp = DAG.getNode(ISD::OR, DL, VT, NeonCmp, NeonCmpAlt);

  if (Invert)
    NeonCmp = DAG.getNOT(DL, NeonCmp, VT);

  return NeonCmp;
}

// (SETCC lhs, rhs, condcode)
SDValue
AArch64TargetLowering::LowerSETCC(SDValue Op, SelectionDAG &DAG) const {
  SDLoc dl(Op);
  SDValue LHS = Op.getOperand(0);
  SDValue RHS = Op.getOperand(1);
  ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(2))->get();
  EVT VT = Op.getValueType();

  if (VT.isVector())
    return LowerVectorSETCC(Op, DAG);

  if (LHS.getValueType() == MVT::f128) {
    // f128 comparisons will be lowered to libcalls giving a valid LHS and RHS
    // for the rest of the function (some i32 or i64 values).
    softenSetCCOperands(DAG, MVT::f128, LHS, RHS, CC, dl);

    // If softenSetCCOperands returned a scalar, use it.
    if (RHS.getNode() == 0) {
      assert(LHS.getValueType() == Op.getValueType() &&
             "Unexpected setcc expansion!");
      return LHS;
    }
  }

  if (LHS.getValueType().isInteger()) {
    SDValue A64cc;

    // Integers are handled in a separate function because the combinations of
    // immediates and tests can get hairy and we may want to fiddle things.
    SDValue CmpOp = getSelectableIntSetCC(LHS, RHS, CC, A64cc, DAG, dl);

    return DAG.getNode(AArch64ISD::SELECT_CC, dl, VT,
                       CmpOp, DAG.getConstant(1, VT), DAG.getConstant(0, VT),
                       A64cc);
  }

  // Note that some LLVM floating-point CondCodes can't be lowered to a single
  // conditional branch, hence FPCCToA64CC can set a second test, where either
  // passing is sufficient.
  A64CC::CondCodes CondCode, Alternative = A64CC::Invalid;
  CondCode = FPCCToA64CC(CC, Alternative);
  SDValue A64cc = DAG.getConstant(CondCode, MVT::i32);
  SDValue CmpOp = DAG.getNode(AArch64ISD::SETCC, dl, MVT::i32, LHS, RHS,
                              DAG.getCondCode(CC));
  SDValue A64SELECT_CC = DAG.getNode(AArch64ISD::SELECT_CC, dl, VT,
                                     CmpOp, DAG.getConstant(1, VT),
                                     DAG.getConstant(0, VT), A64cc);

  if (Alternative != A64CC::Invalid) {
    A64cc = DAG.getConstant(Alternative, MVT::i32);
    A64SELECT_CC = DAG.getNode(AArch64ISD::SELECT_CC, dl, VT, CmpOp,
                               DAG.getConstant(1, VT), A64SELECT_CC, A64cc);
  }

  return A64SELECT_CC;
}

SDValue
AArch64TargetLowering::LowerVACOPY(SDValue Op, SelectionDAG &DAG) const {
  const Value *DestSV = cast<SrcValueSDNode>(Op.getOperand(3))->getValue();
  const Value *SrcSV = cast<SrcValueSDNode>(Op.getOperand(4))->getValue();

  // We have to make sure we copy the entire structure: 8+8+8+4+4 = 32 bytes
  // rather than just 8.
  return DAG.getMemcpy(Op.getOperand(0), SDLoc(Op),
                       Op.getOperand(1), Op.getOperand(2),
                       DAG.getConstant(32, MVT::i32), 8, false, false,
                       MachinePointerInfo(DestSV), MachinePointerInfo(SrcSV));
}

SDValue
AArch64TargetLowering::LowerVASTART(SDValue Op, SelectionDAG &DAG) const {
  // The layout of the va_list struct is specified in the AArch64 Procedure Call
  // Standard, section B.3.
  MachineFunction &MF = DAG.getMachineFunction();
  AArch64MachineFunctionInfo *FuncInfo
    = MF.getInfo<AArch64MachineFunctionInfo>();
  SDLoc DL(Op);

  SDValue Chain = Op.getOperand(0);
  SDValue VAList = Op.getOperand(1);
  const Value *SV = cast<SrcValueSDNode>(Op.getOperand(2))->getValue();
  SmallVector<SDValue, 4> MemOps;

  // void *__stack at offset 0
  SDValue Stack = DAG.getFrameIndex(FuncInfo->getVariadicStackIdx(),
                                    getPointerTy());
  MemOps.push_back(DAG.getStore(Chain, DL, Stack, VAList,
                                MachinePointerInfo(SV), false, false, 0));

  // void *__gr_top at offset 8
  int GPRSize = FuncInfo->getVariadicGPRSize();
  if (GPRSize > 0) {
    SDValue GRTop, GRTopAddr;

    GRTopAddr = DAG.getNode(ISD::ADD, DL, getPointerTy(), VAList,
                            DAG.getConstant(8, getPointerTy()));

    GRTop = DAG.getFrameIndex(FuncInfo->getVariadicGPRIdx(), getPointerTy());
    GRTop = DAG.getNode(ISD::ADD, DL, getPointerTy(), GRTop,
                        DAG.getConstant(GPRSize, getPointerTy()));

    MemOps.push_back(DAG.getStore(Chain, DL, GRTop, GRTopAddr,
                                  MachinePointerInfo(SV, 8),
                                  false, false, 0));
  }

  // void *__vr_top at offset 16
  int FPRSize = FuncInfo->getVariadicFPRSize();
  if (FPRSize > 0) {
    SDValue VRTop, VRTopAddr;
    VRTopAddr = DAG.getNode(ISD::ADD, DL, getPointerTy(), VAList,
                            DAG.getConstant(16, getPointerTy()));

    VRTop = DAG.getFrameIndex(FuncInfo->getVariadicFPRIdx(), getPointerTy());
    VRTop = DAG.getNode(ISD::ADD, DL, getPointerTy(), VRTop,
                        DAG.getConstant(FPRSize, getPointerTy()));

    MemOps.push_back(DAG.getStore(Chain, DL, VRTop, VRTopAddr,
                                  MachinePointerInfo(SV, 16),
                                  false, false, 0));
  }

  // int __gr_offs at offset 24
  SDValue GROffsAddr = DAG.getNode(ISD::ADD, DL, getPointerTy(), VAList,
                                   DAG.getConstant(24, getPointerTy()));
  MemOps.push_back(DAG.getStore(Chain, DL, DAG.getConstant(-GPRSize, MVT::i32),
                                GROffsAddr, MachinePointerInfo(SV, 24),
                                false, false, 0));

  // int __vr_offs at offset 28
  SDValue VROffsAddr = DAG.getNode(ISD::ADD, DL, getPointerTy(), VAList,
                                   DAG.getConstant(28, getPointerTy()));
  MemOps.push_back(DAG.getStore(Chain, DL, DAG.getConstant(-FPRSize, MVT::i32),
                                VROffsAddr, MachinePointerInfo(SV, 28),
                                false, false, 0));

  return DAG.getNode(ISD::TokenFactor, DL, MVT::Other, &MemOps[0],
                     MemOps.size());
}

SDValue
AArch64TargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const {
  switch (Op.getOpcode()) {
  default: llvm_unreachable("Don't know how to custom lower this!");
  case ISD::FADD: return LowerF128ToCall(Op, DAG, RTLIB::ADD_F128);
  case ISD::FSUB: return LowerF128ToCall(Op, DAG, RTLIB::SUB_F128);
  case ISD::FMUL: return LowerF128ToCall(Op, DAG, RTLIB::MUL_F128);
  case ISD::FDIV: return LowerF128ToCall(Op, DAG, RTLIB::DIV_F128);
  case ISD::FP_TO_SINT: return LowerFP_TO_INT(Op, DAG, true);
  case ISD::FP_TO_UINT: return LowerFP_TO_INT(Op, DAG, false);
  case ISD::SINT_TO_FP: return LowerINT_TO_FP(Op, DAG, true);
  case ISD::UINT_TO_FP: return LowerINT_TO_FP(Op, DAG, false);
  case ISD::FP_ROUND: return LowerFP_ROUND(Op, DAG);
  case ISD::FP_EXTEND: return LowerFP_EXTEND(Op, DAG);
  case ISD::RETURNADDR:    return LowerRETURNADDR(Op, DAG);
  case ISD::FRAMEADDR:     return LowerFRAMEADDR(Op, DAG);

  case ISD::BlockAddress: return LowerBlockAddress(Op, DAG);
  case ISD::BRCOND: return LowerBRCOND(Op, DAG);
  case ISD::BR_CC: return LowerBR_CC(Op, DAG);
  case ISD::GlobalAddress: return LowerGlobalAddressELF(Op, DAG);
  case ISD::GlobalTLSAddress: return LowerGlobalTLSAddress(Op, DAG);
  case ISD::JumpTable: return LowerJumpTable(Op, DAG);
  case ISD::SELECT: return LowerSELECT(Op, DAG);
  case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
  case ISD::SETCC: return LowerSETCC(Op, DAG);
  case ISD::VACOPY: return LowerVACOPY(Op, DAG);
  case ISD::VASTART: return LowerVASTART(Op, DAG);
  case ISD::BUILD_VECTOR:
    return LowerBUILD_VECTOR(Op, DAG, getSubtarget());
  case ISD::VECTOR_SHUFFLE: return LowerVECTOR_SHUFFLE(Op, DAG);
  }

  return SDValue();
}

/// Check if the specified splat value corresponds to a valid vector constant
/// for a Neon instruction with a "modified immediate" operand (e.g., MOVI).  If
/// so, return the encoded 8-bit immediate and the OpCmode instruction fields
/// values.
static bool isNeonModifiedImm(uint64_t SplatBits, uint64_t SplatUndef,
                              unsigned SplatBitSize, SelectionDAG &DAG,
                              bool is128Bits, NeonModImmType type, EVT &VT,
                              unsigned &Imm, unsigned &OpCmode) {
  switch (SplatBitSize) {
  default:
    llvm_unreachable("unexpected size for isNeonModifiedImm");
  case 8: {
    if (type != Neon_Mov_Imm)
      return false;
    assert((SplatBits & ~0xff) == 0 && "one byte splat value is too big");
    // Neon movi per byte: Op=0, Cmode=1110.
    OpCmode = 0xe;
    Imm = SplatBits;
    VT = is128Bits ? MVT::v16i8 : MVT::v8i8;
    break;
  }
  case 16: {
    // Neon move inst per halfword
    VT = is128Bits ? MVT::v8i16 : MVT::v4i16;
    if ((SplatBits & ~0xff) == 0) {
      // Value = 0x00nn is 0x00nn LSL 0
      // movi: Op=0, Cmode=1000; mvni: Op=1, Cmode=1000
      // bic:  Op=1, Cmode=1001;  orr:  Op=0, Cmode=1001
      // Op=x, Cmode=100y
      Imm = SplatBits;
      OpCmode = 0x8;
      break;
    }
    if ((SplatBits & ~0xff00) == 0) {
      // Value = 0xnn00 is 0x00nn LSL 8
      // movi: Op=0, Cmode=1010; mvni: Op=1, Cmode=1010
      // bic:  Op=1, Cmode=1011;  orr:  Op=0, Cmode=1011
      // Op=x, Cmode=101x
      Imm = SplatBits >> 8;
      OpCmode = 0xa;
      break;
    }
    // can't handle any other
    return false;
  }

  case 32: {
    // First the LSL variants (MSL is unusable by some interested instructions).

    // Neon move instr per word, shift zeros
    VT = is128Bits ? MVT::v4i32 : MVT::v2i32;
    if ((SplatBits & ~0xff) == 0) {
      // Value = 0x000000nn is 0x000000nn LSL 0
      // movi: Op=0, Cmode= 0000; mvni: Op=1, Cmode= 0000
      // bic:  Op=1, Cmode= 0001; orr:  Op=0, Cmode= 0001
      // Op=x, Cmode=000x
      Imm = SplatBits;
      OpCmode = 0;
      break;
    }
    if ((SplatBits & ~0xff00) == 0) {
      // Value = 0x0000nn00 is 0x000000nn LSL 8
      // movi: Op=0, Cmode= 0010;  mvni: Op=1, Cmode= 0010
      // bic:  Op=1, Cmode= 0011;  orr : Op=0, Cmode= 0011
      // Op=x, Cmode=001x
      Imm = SplatBits >> 8;
      OpCmode = 0x2;
      break;
    }
    if ((SplatBits & ~0xff0000) == 0) {
      // Value = 0x00nn0000 is 0x000000nn LSL 16
      // movi: Op=0, Cmode= 0100; mvni: Op=1, Cmode= 0100
      // bic:  Op=1, Cmode= 0101; orr:  Op=0, Cmode= 0101
      // Op=x, Cmode=010x
      Imm = SplatBits >> 16;
      OpCmode = 0x4;
      break;
    }
    if ((SplatBits & ~0xff000000) == 0) {
      // Value = 0xnn000000 is 0x000000nn LSL 24
      // movi: Op=0, Cmode= 0110; mvni: Op=1, Cmode= 0110
      // bic:  Op=1, Cmode= 0111; orr:  Op=0, Cmode= 0111
      // Op=x, Cmode=011x
      Imm = SplatBits >> 24;
      OpCmode = 0x6;
      break;
    }

    // Now the MSL immediates.

    // Neon move instr per word, shift ones
    if ((SplatBits & ~0xffff) == 0 &&
        ((SplatBits | SplatUndef) & 0xff) == 0xff) {
      // Value = 0x0000nnff is 0x000000nn MSL 8
      // movi: Op=0, Cmode= 1100; mvni: Op=1, Cmode= 1100
      // Op=x, Cmode=1100
      Imm = SplatBits >> 8;
      OpCmode = 0xc;
      break;
    }
    if ((SplatBits & ~0xffffff) == 0 &&
        ((SplatBits | SplatUndef) & 0xffff) == 0xffff) {
      // Value = 0x00nnffff is 0x000000nn MSL 16
      // movi: Op=1, Cmode= 1101; mvni: Op=1, Cmode= 1101
      // Op=x, Cmode=1101
      Imm = SplatBits >> 16;
      OpCmode = 0xd;
      break;
    }
    // can't handle any other
    return false;
  }

  case 64: {
    if (type != Neon_Mov_Imm)
      return false;
    // Neon move instr bytemask, where each byte is either 0x00 or 0xff.
    // movi Op=1, Cmode=1110.
    OpCmode = 0x1e;
    uint64_t BitMask = 0xff;
    uint64_t Val = 0;
    unsigned ImmMask = 1;
    Imm = 0;
    for (int ByteNum = 0; ByteNum < 8; ++ByteNum) {
      if (((SplatBits | SplatUndef) & BitMask) == BitMask) {
        Val |= BitMask;
        Imm |= ImmMask;
      } else if ((SplatBits & BitMask) != 0) {
        return false;
      }
      BitMask <<= 8;
      ImmMask <<= 1;
    }
    SplatBits = Val;
    VT = is128Bits ? MVT::v2i64 : MVT::v1i64;
    break;
  }
  }

  return true;
}

static SDValue PerformANDCombine(SDNode *N,
                                 TargetLowering::DAGCombinerInfo &DCI) {

  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  // We're looking for an SRA/SHL pair which form an SBFX.

  if (VT != MVT::i32 && VT != MVT::i64)
    return SDValue();

  if (!isa<ConstantSDNode>(N->getOperand(1)))
    return SDValue();

  uint64_t TruncMask = N->getConstantOperandVal(1);
  if (!isMask_64(TruncMask))
    return SDValue();

  uint64_t Width = CountPopulation_64(TruncMask);
  SDValue Shift = N->getOperand(0);

  if (Shift.getOpcode() != ISD::SRL)
    return SDValue();

  if (!isa<ConstantSDNode>(Shift->getOperand(1)))
    return SDValue();
  uint64_t LSB = Shift->getConstantOperandVal(1);

  if (LSB > VT.getSizeInBits() || Width > VT.getSizeInBits())
    return SDValue();

  return DAG.getNode(AArch64ISD::UBFX, DL, VT, Shift.getOperand(0),
                     DAG.getConstant(LSB, MVT::i64),
                     DAG.getConstant(LSB + Width - 1, MVT::i64));
}

/// For a true bitfield insert, the bits getting into that contiguous mask
/// should come from the low part of an existing value: they must be formed from
/// a compatible SHL operation (unless they're already low). This function
/// checks that condition and returns the least-significant bit that's
/// intended. If the operation not a field preparation, -1 is returned.
static int32_t getLSBForBFI(SelectionDAG &DAG, SDLoc DL, EVT VT,
                            SDValue &MaskedVal, uint64_t Mask) {
  if (!isShiftedMask_64(Mask))
    return -1;

  // Now we need to alter MaskedVal so that it is an appropriate input for a BFI
  // instruction. BFI will do a left-shift by LSB before applying the mask we've
  // spotted, so in general we should pre-emptively "undo" that by making sure
  // the incoming bits have had a right-shift applied to them.
  //
  // This right shift, however, will combine with existing left/right shifts. In
  // the simplest case of a completely straight bitfield operation, it will be
  // expected to completely cancel out with an existing SHL. More complicated
  // cases (e.g. bitfield to bitfield copy) may still need a real shift before
  // the BFI.

  uint64_t LSB = countTrailingZeros(Mask);
  int64_t ShiftRightRequired = LSB;
  if (MaskedVal.getOpcode() == ISD::SHL &&
      isa<ConstantSDNode>(MaskedVal.getOperand(1))) {
    ShiftRightRequired -= MaskedVal.getConstantOperandVal(1);
    MaskedVal = MaskedVal.getOperand(0);
  } else if (MaskedVal.getOpcode() == ISD::SRL &&
             isa<ConstantSDNode>(MaskedVal.getOperand(1))) {
    ShiftRightRequired += MaskedVal.getConstantOperandVal(1);
    MaskedVal = MaskedVal.getOperand(0);
  }

  if (ShiftRightRequired > 0)
    MaskedVal = DAG.getNode(ISD::SRL, DL, VT, MaskedVal,
                            DAG.getConstant(ShiftRightRequired, MVT::i64));
  else if (ShiftRightRequired < 0) {
    // We could actually end up with a residual left shift, for example with
    // "struc.bitfield = val << 1".
    MaskedVal = DAG.getNode(ISD::SHL, DL, VT, MaskedVal,
                            DAG.getConstant(-ShiftRightRequired, MVT::i64));
  }

  return LSB;
}

/// Searches from N for an existing AArch64ISD::BFI node, possibly surrounded by
/// a mask and an extension. Returns true if a BFI was found and provides
/// information on its surroundings.
static bool findMaskedBFI(SDValue N, SDValue &BFI, uint64_t &Mask,
                          bool &Extended) {
  Extended = false;
  if (N.getOpcode() == ISD::ZERO_EXTEND) {
    Extended = true;
    N = N.getOperand(0);
  }

  if (N.getOpcode() == ISD::AND && isa<ConstantSDNode>(N.getOperand(1))) {
    Mask = N->getConstantOperandVal(1);
    N = N.getOperand(0);
  } else {
    // Mask is the whole width.
    Mask = -1ULL >> (64 - N.getValueType().getSizeInBits());
  }

  if (N.getOpcode() == AArch64ISD::BFI) {
    BFI = N;
    return true;
  }

  return false;
}

/// Try to combine a subtree (rooted at an OR) into a "masked BFI" node, which
/// is roughly equivalent to (and (BFI ...), mask). This form is used because it
/// can often be further combined with a larger mask. Ultimately, we want mask
/// to be 2^32-1 or 2^64-1 so the AND can be skipped.
static SDValue tryCombineToBFI(SDNode *N,
                               TargetLowering::DAGCombinerInfo &DCI,
                               const AArch64Subtarget *Subtarget) {
  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  assert(N->getOpcode() == ISD::OR && "Unexpected root");

  // We need the LHS to be (and SOMETHING, MASK). Find out what that mask is or
  // abandon the effort.
  SDValue LHS = N->getOperand(0);
  if (LHS.getOpcode() != ISD::AND)
    return SDValue();

  uint64_t LHSMask;
  if (isa<ConstantSDNode>(LHS.getOperand(1)))
    LHSMask = LHS->getConstantOperandVal(1);
  else
    return SDValue();

  // We also need the RHS to be (and SOMETHING, MASK). Find out what that mask
  // is or abandon the effort.
  SDValue RHS = N->getOperand(1);
  if (RHS.getOpcode() != ISD::AND)
    return SDValue();

  uint64_t RHSMask;
  if (isa<ConstantSDNode>(RHS.getOperand(1)))
    RHSMask = RHS->getConstantOperandVal(1);
  else
    return SDValue();

  // Can't do anything if the masks are incompatible.
  if (LHSMask & RHSMask)
    return SDValue();

  // Now we need one of the masks to be a contiguous field. Without loss of
  // generality that should be the RHS one.
  SDValue Bitfield = LHS.getOperand(0);
  if (getLSBForBFI(DAG, DL, VT, Bitfield, LHSMask) != -1) {
    // We know that LHS is a candidate new value, and RHS isn't already a better
    // one.
    std::swap(LHS, RHS);
    std::swap(LHSMask, RHSMask);
  }

  // We've done our best to put the right operands in the right places, all we
  // can do now is check whether a BFI exists.
  Bitfield = RHS.getOperand(0);
  int32_t LSB = getLSBForBFI(DAG, DL, VT, Bitfield, RHSMask);
  if (LSB == -1)
    return SDValue();

  uint32_t Width = CountPopulation_64(RHSMask);
  assert(Width && "Expected non-zero bitfield width");

  SDValue BFI = DAG.getNode(AArch64ISD::BFI, DL, VT,
                            LHS.getOperand(0), Bitfield,
                            DAG.getConstant(LSB, MVT::i64),
                            DAG.getConstant(Width, MVT::i64));

  // Mask is trivial
  if ((LHSMask | RHSMask) == (-1ULL >> (64 - VT.getSizeInBits())))
    return BFI;

  return DAG.getNode(ISD::AND, DL, VT, BFI,
                     DAG.getConstant(LHSMask | RHSMask, VT));
}

/// Search for the bitwise combining (with careful masks) of a MaskedBFI and its
/// original input. This is surprisingly common because SROA splits things up
/// into i8 chunks, so the originally detected MaskedBFI may actually only act
/// on the low (say) byte of a word. This is then orred into the rest of the
/// word afterwards.
///
/// Basic input: (or (and OLDFIELD, MASK1), (MaskedBFI MASK2, OLDFIELD, ...)).
///
/// If MASK1 and MASK2 are compatible, we can fold the whole thing into the
/// MaskedBFI. We can also deal with a certain amount of extend/truncate being
/// involved.
static SDValue tryCombineToLargerBFI(SDNode *N,
                                     TargetLowering::DAGCombinerInfo &DCI,
                                     const AArch64Subtarget *Subtarget) {
  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  // First job is to hunt for a MaskedBFI on either the left or right. Swap
  // operands if it's actually on the right.
  SDValue BFI;
  SDValue PossExtraMask;
  uint64_t ExistingMask = 0;
  bool Extended = false;
  if (findMaskedBFI(N->getOperand(0), BFI, ExistingMask, Extended))
    PossExtraMask = N->getOperand(1);
  else if (findMaskedBFI(N->getOperand(1), BFI, ExistingMask, Extended))
    PossExtraMask = N->getOperand(0);
  else
    return SDValue();

  // We can only combine a BFI with another compatible mask.
  if (PossExtraMask.getOpcode() != ISD::AND ||
      !isa<ConstantSDNode>(PossExtraMask.getOperand(1)))
    return SDValue();

  uint64_t ExtraMask = PossExtraMask->getConstantOperandVal(1);

  // Masks must be compatible.
  if (ExtraMask & ExistingMask)
    return SDValue();

  SDValue OldBFIVal = BFI.getOperand(0);
  SDValue NewBFIVal = BFI.getOperand(1);
  if (Extended) {
    // We skipped a ZERO_EXTEND above, so the input to the MaskedBFIs should be
    // 32-bit and we'll be forming a 64-bit MaskedBFI. The MaskedBFI arguments
    // need to be made compatible.
    assert(VT == MVT::i64 && BFI.getValueType() == MVT::i32
           && "Invalid types for BFI");
    OldBFIVal = DAG.getNode(ISD::ANY_EXTEND, DL, VT, OldBFIVal);
    NewBFIVal = DAG.getNode(ISD::ANY_EXTEND, DL, VT, NewBFIVal);
  }

  // We need the MaskedBFI to be combined with a mask of the *same* value.
  if (PossExtraMask.getOperand(0) != OldBFIVal)
    return SDValue();

  BFI = DAG.getNode(AArch64ISD::BFI, DL, VT,
                    OldBFIVal, NewBFIVal,
                    BFI.getOperand(2), BFI.getOperand(3));

  // If the masking is trivial, we don't need to create it.
  if ((ExtraMask | ExistingMask) == (-1ULL >> (64 - VT.getSizeInBits())))
    return BFI;

  return DAG.getNode(ISD::AND, DL, VT, BFI,
                     DAG.getConstant(ExtraMask | ExistingMask, VT));
}

/// An EXTR instruction is made up of two shifts, ORed together. This helper
/// searches for and classifies those shifts.
static bool findEXTRHalf(SDValue N, SDValue &Src, uint32_t &ShiftAmount,
                         bool &FromHi) {
  if (N.getOpcode() == ISD::SHL)
    FromHi = false;
  else if (N.getOpcode() == ISD::SRL)
    FromHi = true;
  else
    return false;

  if (!isa<ConstantSDNode>(N.getOperand(1)))
    return false;

  ShiftAmount = N->getConstantOperandVal(1);
  Src = N->getOperand(0);
  return true;
}

/// EXTR instruction extracts a contiguous chunk of bits from two existing
/// registers viewed as a high/low pair. This function looks for the pattern:
/// (or (shl VAL1, #N), (srl VAL2, #RegWidth-N)) and replaces it with an
/// EXTR. Can't quite be done in TableGen because the two immediates aren't
/// independent.
static SDValue tryCombineToEXTR(SDNode *N,
                                TargetLowering::DAGCombinerInfo &DCI) {
  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  assert(N->getOpcode() == ISD::OR && "Unexpected root");

  if (VT != MVT::i32 && VT != MVT::i64)
    return SDValue();

  SDValue LHS;
  uint32_t ShiftLHS = 0;
  bool LHSFromHi = 0;
  if (!findEXTRHalf(N->getOperand(0), LHS, ShiftLHS, LHSFromHi))
    return SDValue();

  SDValue RHS;
  uint32_t ShiftRHS = 0;
  bool RHSFromHi = 0;
  if (!findEXTRHalf(N->getOperand(1), RHS, ShiftRHS, RHSFromHi))
    return SDValue();

  // If they're both trying to come from the high part of the register, they're
  // not really an EXTR.
  if (LHSFromHi == RHSFromHi)
    return SDValue();

  if (ShiftLHS + ShiftRHS != VT.getSizeInBits())
    return SDValue();

  if (LHSFromHi) {
    std::swap(LHS, RHS);
    std::swap(ShiftLHS, ShiftRHS);
  }

  return DAG.getNode(AArch64ISD::EXTR, DL, VT,
                     LHS, RHS,
                     DAG.getConstant(ShiftRHS, MVT::i64));
}

/// Target-specific dag combine xforms for ISD::OR
static SDValue PerformORCombine(SDNode *N,
                                TargetLowering::DAGCombinerInfo &DCI,
                                const AArch64Subtarget *Subtarget) {

  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  if(!DAG.getTargetLoweringInfo().isTypeLegal(VT))
    return SDValue();

  // Attempt to recognise bitfield-insert operations.
  SDValue Res = tryCombineToBFI(N, DCI, Subtarget);
  if (Res.getNode())
    return Res;

  // Attempt to combine an existing MaskedBFI operation into one with a larger
  // mask.
  Res = tryCombineToLargerBFI(N, DCI, Subtarget);
  if (Res.getNode())
    return Res;

  Res = tryCombineToEXTR(N, DCI);
  if (Res.getNode())
    return Res;

  if (!Subtarget->hasNEON())
    return SDValue();

  // Attempt to use vector immediate-form BSL
  // (or (and B, A), (and C, ~A)) => (VBSL A, B, C) when A is a constant.

  SDValue N0 = N->getOperand(0);
  if (N0.getOpcode() != ISD::AND)
    return SDValue();

  SDValue N1 = N->getOperand(1);
  if (N1.getOpcode() != ISD::AND)
    return SDValue();

  if (VT.isVector() && DAG.getTargetLoweringInfo().isTypeLegal(VT)) {
    APInt SplatUndef;
    unsigned SplatBitSize;
    bool HasAnyUndefs;
    BuildVectorSDNode *BVN0 = dyn_cast<BuildVectorSDNode>(N0->getOperand(1));
    APInt SplatBits0;
    if (BVN0 && BVN0->isConstantSplat(SplatBits0, SplatUndef, SplatBitSize,
                                      HasAnyUndefs) &&
        !HasAnyUndefs) {
      BuildVectorSDNode *BVN1 = dyn_cast<BuildVectorSDNode>(N1->getOperand(1));
      APInt SplatBits1;
      if (BVN1 && BVN1->isConstantSplat(SplatBits1, SplatUndef, SplatBitSize,
                                        HasAnyUndefs) &&
          !HasAnyUndefs && SplatBits0 == ~SplatBits1) {
        // Canonicalize the vector type to make instruction selection simpler.
        EVT CanonicalVT = VT.is128BitVector() ? MVT::v16i8 : MVT::v8i8;
        SDValue Result = DAG.getNode(AArch64ISD::NEON_BSL, DL, CanonicalVT,
                                     N0->getOperand(1), N0->getOperand(0),
                                     N1->getOperand(0));
        return DAG.getNode(ISD::BITCAST, DL, VT, Result);
      }
    }
  }

  return SDValue();
}

/// Target-specific dag combine xforms for ISD::SRA
static SDValue PerformSRACombine(SDNode *N,
                                 TargetLowering::DAGCombinerInfo &DCI) {

  SelectionDAG &DAG = DCI.DAG;
  SDLoc DL(N);
  EVT VT = N->getValueType(0);

  // We're looking for an SRA/SHL pair which form an SBFX.

  if (VT != MVT::i32 && VT != MVT::i64)
    return SDValue();

  if (!isa<ConstantSDNode>(N->getOperand(1)))
    return SDValue();

  uint64_t ExtraSignBits = N->getConstantOperandVal(1);
  SDValue Shift = N->getOperand(0);

  if (Shift.getOpcode() != ISD::SHL)
    return SDValue();

  if (!isa<ConstantSDNode>(Shift->getOperand(1)))
    return SDValue();

  uint64_t BitsOnLeft = Shift->getConstantOperandVal(1);
  uint64_t Width = VT.getSizeInBits() - ExtraSignBits;
  uint64_t LSB = VT.getSizeInBits() - Width - BitsOnLeft;

  if (LSB > VT.getSizeInBits() || Width > VT.getSizeInBits())
    return SDValue();

  return DAG.getNode(AArch64ISD::SBFX, DL, VT, Shift.getOperand(0),
                     DAG.getConstant(LSB, MVT::i64),
                     DAG.getConstant(LSB + Width - 1, MVT::i64));
}

/// Check if this is a valid build_vector for the immediate operand of
/// a vector shift operation, where all the elements of the build_vector
/// must have the same constant integer value.
static bool getVShiftImm(SDValue Op, unsigned ElementBits, int64_t &Cnt) {
  // Ignore bit_converts.
  while (Op.getOpcode() == ISD::BITCAST)
    Op = Op.getOperand(0);
  BuildVectorSDNode *BVN = dyn_cast<BuildVectorSDNode>(Op.getNode());
  APInt SplatBits, SplatUndef;
  unsigned SplatBitSize;
  bool HasAnyUndefs;
  if (!BVN || !BVN->isConstantSplat(SplatBits, SplatUndef, SplatBitSize,
                                      HasAnyUndefs, ElementBits) ||
      SplatBitSize > ElementBits)
    return false;
  Cnt = SplatBits.getSExtValue();
  return true;
}

/// Check if this is a valid build_vector for the immediate operand of
/// a vector shift left operation.  That value must be in the range:
/// 0 <= Value < ElementBits
static bool isVShiftLImm(SDValue Op, EVT VT, int64_t &Cnt) {
  assert(VT.isVector() && "vector shift count is not a vector type");
  unsigned ElementBits = VT.getVectorElementType().getSizeInBits();
  if (!getVShiftImm(Op, ElementBits, Cnt))
    return false;
  return (Cnt >= 0 && Cnt < ElementBits);
}

/// Check if this is a valid build_vector for the immediate operand of a
/// vector shift right operation. The value must be in the range:
///   1 <= Value <= ElementBits
static bool isVShiftRImm(SDValue Op, EVT VT, int64_t &Cnt) {
  assert(VT.isVector() && "vector shift count is not a vector type");
  unsigned ElementBits = VT.getVectorElementType().getSizeInBits();
  if (!getVShiftImm(Op, ElementBits, Cnt))
    return false;
  return (Cnt >= 1 && Cnt <= ElementBits);
}

/// Checks for immediate versions of vector shifts and lowers them.
static SDValue PerformShiftCombine(SDNode *N,
                                   TargetLowering::DAGCombinerInfo &DCI,
                                   const AArch64Subtarget *ST) {
  SelectionDAG &DAG = DCI.DAG;
  EVT VT = N->getValueType(0);
  if (N->getOpcode() == ISD::SRA && (VT == MVT::i32 || VT == MVT::i64))
    return PerformSRACombine(N, DCI);

  // Nothing to be done for scalar shifts.
  const TargetLowering &TLI = DAG.getTargetLoweringInfo();
  if (!VT.isVector() || !TLI.isTypeLegal(VT))
    return SDValue();

  assert(ST->hasNEON() && "unexpected vector shift");
  int64_t Cnt;

  switch (N->getOpcode()) {
  default:
    llvm_unreachable("unexpected shift opcode");

  case ISD::SHL:
    if (isVShiftLImm(N->getOperand(1), VT, Cnt)) {
      SDValue RHS =
          DAG.getNode(AArch64ISD::NEON_VDUP, SDLoc(N->getOperand(1)), VT,
                      DAG.getConstant(Cnt, MVT::i32));
      return DAG.getNode(ISD::SHL, SDLoc(N), VT, N->getOperand(0), RHS);
    }
    break;

  case ISD::SRA:
  case ISD::SRL:
    if (isVShiftRImm(N->getOperand(1), VT, Cnt)) {
      SDValue RHS =
          DAG.getNode(AArch64ISD::NEON_VDUP, SDLoc(N->getOperand(1)), VT,
                      DAG.getConstant(Cnt, MVT::i32));
      return DAG.getNode(N->getOpcode(), SDLoc(N), VT, N->getOperand(0), RHS);
    }
    break;
  }

  return SDValue();
}

/// ARM-specific DAG combining for intrinsics.
static SDValue PerformIntrinsicCombine(SDNode *N, SelectionDAG &DAG) {
  unsigned IntNo = cast<ConstantSDNode>(N->getOperand(0))->getZExtValue();

  switch (IntNo) {
  default:
    // Don't do anything for most intrinsics.
    break;

  case Intrinsic::arm_neon_vqshifts:
  case Intrinsic::arm_neon_vqshiftu:
    EVT VT = N->getOperand(1).getValueType();
    int64_t Cnt;
    if (!isVShiftLImm(N->getOperand(2), VT, Cnt))
      break;
    unsigned VShiftOpc = (IntNo == Intrinsic::arm_neon_vqshifts)
                             ? AArch64ISD::NEON_QSHLs
                             : AArch64ISD::NEON_QSHLu;
    return DAG.getNode(VShiftOpc, SDLoc(N), N->getValueType(0),
                       N->getOperand(1), DAG.getConstant(Cnt, MVT::i32));
  }

  return SDValue();
}

/// Target-specific DAG combine function for NEON load/store intrinsics
/// to merge base address updates.
static SDValue CombineBaseUpdate(SDNode *N,
                                 TargetLowering::DAGCombinerInfo &DCI) {
  if (DCI.isBeforeLegalize() || DCI.isCalledByLegalizer())
    return SDValue();

  SelectionDAG &DAG = DCI.DAG;
  bool isIntrinsic = (N->getOpcode() == ISD::INTRINSIC_VOID ||
                      N->getOpcode() == ISD::INTRINSIC_W_CHAIN);
  unsigned AddrOpIdx = (isIntrinsic ? 2 : 1);
  SDValue Addr = N->getOperand(AddrOpIdx);

  // Search for a use of the address operand that is an increment.
  for (SDNode::use_iterator UI = Addr.getNode()->use_begin(),
       UE = Addr.getNode()->use_end(); UI != UE; ++UI) {
    SDNode *User = *UI;
    if (User->getOpcode() != ISD::ADD ||
        UI.getUse().getResNo() != Addr.getResNo())
      continue;

    // Check that the add is independent of the load/store.  Otherwise, folding
    // it would create a cycle.
    if (User->isPredecessorOf(N) || N->isPredecessorOf(User))
      continue;

    // Find the new opcode for the updating load/store.
    bool isLoad = true;
    bool isLaneOp = false;
    unsigned NewOpc = 0;
    unsigned NumVecs = 0;
    if (isIntrinsic) {
      unsigned IntNo = cast<ConstantSDNode>(N->getOperand(1))->getZExtValue();
      switch (IntNo) {
      default: llvm_unreachable("unexpected intrinsic for Neon base update");
      case Intrinsic::arm_neon_vld1:       NewOpc = AArch64ISD::NEON_LD1_UPD;
        NumVecs = 1; break;
      case Intrinsic::arm_neon_vld2:       NewOpc = AArch64ISD::NEON_LD2_UPD;
        NumVecs = 2; break;
      case Intrinsic::arm_neon_vld3:       NewOpc = AArch64ISD::NEON_LD3_UPD;
        NumVecs = 3; break;
      case Intrinsic::arm_neon_vld4:       NewOpc = AArch64ISD::NEON_LD4_UPD;
        NumVecs = 4; break;
      case Intrinsic::arm_neon_vst1:       NewOpc = AArch64ISD::NEON_ST1_UPD;
        NumVecs = 1; isLoad = false; break;
      case Intrinsic::arm_neon_vst2:       NewOpc = AArch64ISD::NEON_ST2_UPD;
        NumVecs = 2; isLoad = false; break;
      case Intrinsic::arm_neon_vst3:       NewOpc = AArch64ISD::NEON_ST3_UPD;
        NumVecs = 3; isLoad = false; break;
      case Intrinsic::arm_neon_vst4:       NewOpc = AArch64ISD::NEON_ST4_UPD;
        NumVecs = 4; isLoad = false; break;
      case Intrinsic::aarch64_neon_vld1x2: NewOpc = AArch64ISD::NEON_LD1x2_UPD;
        NumVecs = 2; break;
      case Intrinsic::aarch64_neon_vld1x3: NewOpc = AArch64ISD::NEON_LD1x3_UPD;
        NumVecs = 3; break;
      case Intrinsic::aarch64_neon_vld1x4: NewOpc = AArch64ISD::NEON_LD1x4_UPD;
        NumVecs = 4; break;
      case Intrinsic::aarch64_neon_vst1x2: NewOpc = AArch64ISD::NEON_ST1x2_UPD;
        NumVecs = 2; isLoad = false; break;
      case Intrinsic::aarch64_neon_vst1x3: NewOpc = AArch64ISD::NEON_ST1x3_UPD;
        NumVecs = 3; isLoad = false; break;
      case Intrinsic::aarch64_neon_vst1x4: NewOpc = AArch64ISD::NEON_ST1x4_UPD;
        NumVecs = 4; isLoad = false; break;
      case Intrinsic::arm_neon_vld2lane:   NewOpc = AArch64ISD::NEON_LD2LN_UPD;
        NumVecs = 2; isLaneOp = true; break;
      case Intrinsic::arm_neon_vld3lane:   NewOpc = AArch64ISD::NEON_LD3LN_UPD;
        NumVecs = 3; isLaneOp = true; break;
      case Intrinsic::arm_neon_vld4lane:   NewOpc = AArch64ISD::NEON_LD4LN_UPD;
        NumVecs = 4; isLaneOp = true; break;
      case Intrinsic::arm_neon_vst2lane:   NewOpc = AArch64ISD::NEON_ST2LN_UPD;
        NumVecs = 2; isLoad = false; isLaneOp = true; break;
      case Intrinsic::arm_neon_vst3lane:   NewOpc = AArch64ISD::NEON_ST3LN_UPD;
        NumVecs = 3; isLoad = false; isLaneOp = true; break;
      case Intrinsic::arm_neon_vst4lane:   NewOpc = AArch64ISD::NEON_ST4LN_UPD;
        NumVecs = 4; isLoad = false; isLaneOp = true; break;
      }
    } else {
      isLaneOp = true;
      switch (N->getOpcode()) {
      default: llvm_unreachable("unexpected opcode for Neon base update");
      case AArch64ISD::NEON_LD2DUP: NewOpc = AArch64ISD::NEON_LD2DUP_UPD;
        NumVecs = 2; break;
      case AArch64ISD::NEON_LD3DUP: NewOpc = AArch64ISD::NEON_LD3DUP_UPD;
        NumVecs = 3; break;
      case AArch64ISD::NEON_LD4DUP: NewOpc = AArch64ISD::NEON_LD4DUP_UPD;
        NumVecs = 4; break;
      }
    }

    // Find the size of memory referenced by the load/store.
    EVT VecTy;
    if (isLoad)
      VecTy = N->getValueType(0);
    else
      VecTy = N->getOperand(AddrOpIdx + 1).getValueType();
    unsigned NumBytes = NumVecs * VecTy.getSizeInBits() / 8;
    if (isLaneOp)
      NumBytes /= VecTy.getVectorNumElements();

    // If the increment is a constant, it must match the memory ref size.
    SDValue Inc = User->getOperand(User->getOperand(0) == Addr ? 1 : 0);
    if (ConstantSDNode *CInc = dyn_cast<ConstantSDNode>(Inc.getNode())) {
      uint32_t IncVal = CInc->getZExtValue();
      if (IncVal != NumBytes)
        continue;
      Inc = DAG.getTargetConstant(IncVal, MVT::i32);
    }

    // Create the new updating load/store node.
    EVT Tys[6];
    unsigned NumResultVecs = (isLoad ? NumVecs : 0);
    unsigned n;
    for (n = 0; n < NumResultVecs; ++n)
      Tys[n] = VecTy;
    Tys[n++] = MVT::i64;
    Tys[n] = MVT::Other;
    SDVTList SDTys = DAG.getVTList(Tys, NumResultVecs + 2);
    SmallVector<SDValue, 8> Ops;
    Ops.push_back(N->getOperand(0)); // incoming chain
    Ops.push_back(N->getOperand(AddrOpIdx));
    Ops.push_back(Inc);
    for (unsigned i = AddrOpIdx + 1; i < N->getNumOperands(); ++i) {
      Ops.push_back(N->getOperand(i));
    }
    MemIntrinsicSDNode *MemInt = cast<MemIntrinsicSDNode>(N);
    SDValue UpdN = DAG.getMemIntrinsicNode(NewOpc, SDLoc(N), SDTys,
                                           Ops.data(), Ops.size(),
                                           MemInt->getMemoryVT(),
                                           MemInt->getMemOperand());

    // Update the uses.
    std::vector<SDValue> NewResults;
    for (unsigned i = 0; i < NumResultVecs; ++i) {
      NewResults.push_back(SDValue(UpdN.getNode(), i));
    }
    NewResults.push_back(SDValue(UpdN.getNode(), NumResultVecs + 1)); // chain
    DCI.CombineTo(N, NewResults);
    DCI.CombineTo(User, SDValue(UpdN.getNode(), NumResultVecs));

    break;
  }
  return SDValue();
}

/// For a VDUPLANE node N, check if its source operand is a vldN-lane (N > 1)
/// intrinsic, and if all the other uses of that intrinsic are also VDUPLANEs.
/// If so, combine them to a vldN-dup operation and return true.
static SDValue CombineVLDDUP(SDNode *N, TargetLowering::DAGCombinerInfo &DCI) {
  SelectionDAG &DAG = DCI.DAG;
  EVT VT = N->getValueType(0);

  // Check if the VDUPLANE operand is a vldN-dup intrinsic.
  SDNode *VLD = N->getOperand(0).getNode();
  if (VLD->getOpcode() != ISD::INTRINSIC_W_CHAIN)
    return SDValue();
  unsigned NumVecs = 0;
  unsigned NewOpc = 0;
  unsigned IntNo = cast<ConstantSDNode>(VLD->getOperand(1))->getZExtValue();
  if (IntNo == Intrinsic::arm_neon_vld2lane) {
    NumVecs = 2;
    NewOpc = AArch64ISD::NEON_LD2DUP;
  } else if (IntNo == Intrinsic::arm_neon_vld3lane) {
    NumVecs = 3;
    NewOpc = AArch64ISD::NEON_LD3DUP;
  } else if (IntNo == Intrinsic::arm_neon_vld4lane) {
    NumVecs = 4;
    NewOpc = AArch64ISD::NEON_LD4DUP;
  } else {
    return SDValue();
  }

  // First check that all the vldN-lane uses are VDUPLANEs and that the lane
  // numbers match the load.
  unsigned VLDLaneNo =
      cast<ConstantSDNode>(VLD->getOperand(NumVecs + 3))->getZExtValue();
  for (SDNode::use_iterator UI = VLD->use_begin(), UE = VLD->use_end();
       UI != UE; ++UI) {
    // Ignore uses of the chain result.
    if (UI.getUse().getResNo() == NumVecs)
      continue;
    SDNode *User = *UI;
    if (User->getOpcode() != AArch64ISD::NEON_VDUPLANE ||
        VLDLaneNo != cast<ConstantSDNode>(User->getOperand(1))->getZExtValue())
      return SDValue();
  }

  // Create the vldN-dup node.
  EVT Tys[5];
  unsigned n;
  for (n = 0; n < NumVecs; ++n)
    Tys[n] = VT;
  Tys[n] = MVT::Other;
  SDVTList SDTys = DAG.getVTList(Tys, NumVecs + 1);
  SDValue Ops[] = { VLD->getOperand(0), VLD->getOperand(2) };
  MemIntrinsicSDNode *VLDMemInt = cast<MemIntrinsicSDNode>(VLD);
  SDValue VLDDup = DAG.getMemIntrinsicNode(NewOpc, SDLoc(VLD), SDTys, Ops, 2,
                                           VLDMemInt->getMemoryVT(),
                                           VLDMemInt->getMemOperand());

  // Update the uses.
  for (SDNode::use_iterator UI = VLD->use_begin(), UE = VLD->use_end();
       UI != UE; ++UI) {
    unsigned ResNo = UI.getUse().getResNo();
    // Ignore uses of the chain result.
    if (ResNo == NumVecs)
      continue;
    SDNode *User = *UI;
    DCI.CombineTo(User, SDValue(VLDDup.getNode(), ResNo));
  }

  // Now the vldN-lane intrinsic is dead except for its chain result.
  // Update uses of the chain.
  std::vector<SDValue> VLDDupResults;
  for (unsigned n = 0; n < NumVecs; ++n)
    VLDDupResults.push_back(SDValue(VLDDup.getNode(), n));
  VLDDupResults.push_back(SDValue(VLDDup.getNode(), NumVecs));
  DCI.CombineTo(VLD, VLDDupResults);

  return SDValue(N, 0);
}

SDValue
AArch64TargetLowering::PerformDAGCombine(SDNode *N,
                                         DAGCombinerInfo &DCI) const {
  switch (N->getOpcode()) {
  default: break;
  case ISD::AND: return PerformANDCombine(N, DCI);
  case ISD::OR: return PerformORCombine(N, DCI, getSubtarget());
  case ISD::SHL:
  case ISD::SRA:
  case ISD::SRL:
    return PerformShiftCombine(N, DCI, getSubtarget());
  case ISD::INTRINSIC_WO_CHAIN:
    return PerformIntrinsicCombine(N, DCI.DAG);
  case AArch64ISD::NEON_VDUPLANE:
    return CombineVLDDUP(N, DCI);
  case AArch64ISD::NEON_LD2DUP:
  case AArch64ISD::NEON_LD3DUP:
  case AArch64ISD::NEON_LD4DUP:
    return CombineBaseUpdate(N, DCI);
  case ISD::INTRINSIC_VOID:
  case ISD::INTRINSIC_W_CHAIN:
    switch (cast<ConstantSDNode>(N->getOperand(1))->getZExtValue()) {
    case Intrinsic::arm_neon_vld1:
    case Intrinsic::arm_neon_vld2:
    case Intrinsic::arm_neon_vld3:
    case Intrinsic::arm_neon_vld4:
    case Intrinsic::arm_neon_vst1:
    case Intrinsic::arm_neon_vst2:
    case Intrinsic::arm_neon_vst3:
    case Intrinsic::arm_neon_vst4:
    case Intrinsic::arm_neon_vld2lane:
    case Intrinsic::arm_neon_vld3lane:
    case Intrinsic::arm_neon_vld4lane:
    case Intrinsic::aarch64_neon_vld1x2:
    case Intrinsic::aarch64_neon_vld1x3:
    case Intrinsic::aarch64_neon_vld1x4:
    case Intrinsic::aarch64_neon_vst1x2:
    case Intrinsic::aarch64_neon_vst1x3:
    case Intrinsic::aarch64_neon_vst1x4:
    case Intrinsic::arm_neon_vst2lane:
    case Intrinsic::arm_neon_vst3lane:
    case Intrinsic::arm_neon_vst4lane:
      return CombineBaseUpdate(N, DCI);
    default:
      break;
    }
  }
  return SDValue();
}

bool
AArch64TargetLowering::isFMAFasterThanFMulAndFAdd(EVT VT) const {
  VT = VT.getScalarType();

  if (!VT.isSimple())
    return false;

  switch (VT.getSimpleVT().SimpleTy) {
  case MVT::f16:
  case MVT::f32:
  case MVT::f64:
    return true;
  case MVT::f128:
    return false;
  default:
    break;
  }

  return false;
}

// Check whether a Build Vector could be presented as Shuffle Vector. If yes,
// try to call LowerVECTOR_SHUFFLE to lower it.
bool AArch64TargetLowering::isKnownShuffleVector(SDValue Op, SelectionDAG &DAG,
                                                 SDValue &Res) const {
  SDLoc DL(Op);
  EVT VT = Op.getValueType();
  unsigned NumElts = VT.getVectorNumElements();
  unsigned V0NumElts = 0;
  int Mask[16];
  SDValue V0, V1;

  // Check if all elements are extracted from less than 3 vectors.
  for (unsigned i = 0; i < NumElts; ++i) {
    SDValue Elt = Op.getOperand(i);
    if (Elt.getOpcode() != ISD::EXTRACT_VECTOR_ELT)
      return false;

    if (V0.getNode() == 0) {
      V0 = Elt.getOperand(0);
      V0NumElts = V0.getValueType().getVectorNumElements();
    }
    if (Elt.getOperand(0) == V0) {
      Mask[i] = (cast<ConstantSDNode>(Elt->getOperand(1))->getZExtValue());
      continue;
    } else if (V1.getNode() == 0) {
      V1 = Elt.getOperand(0);
    }
    if (Elt.getOperand(0) == V1) {
      unsigned Lane = cast<ConstantSDNode>(Elt->getOperand(1))->getZExtValue();
      Mask[i] = (Lane + V0NumElts);
      continue;
    } else {
      return false;
    }
  }

  if (!V1.getNode() && V0NumElts == NumElts * 2) {
    V1 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, V0,
                     DAG.getConstant(NumElts, MVT::i64));
    V0 = DAG.getNode(ISD::EXTRACT_SUBVECTOR, DL, VT, V0,
                     DAG.getConstant(0, MVT::i64));
    V0NumElts = V0.getValueType().getVectorNumElements();
  }

  if (V1.getNode() && NumElts == V0NumElts &&
      V0NumElts == V1.getValueType().getVectorNumElements()) {
    SDValue Shuffle = DAG.getVectorShuffle(VT, DL, V0, V1, Mask);
    Res = LowerVECTOR_SHUFFLE(Shuffle, DAG);
    return true;
  } else
    return false;
}

// If this is a case we can't handle, return null and let the default
// expansion code take care of it.
SDValue
AArch64TargetLowering::LowerBUILD_VECTOR(SDValue Op, SelectionDAG &DAG,
                                         const AArch64Subtarget *ST) const {

  BuildVectorSDNode *BVN = cast<BuildVectorSDNode>(Op.getNode());
  SDLoc DL(Op);
  EVT VT = Op.getValueType();

  APInt SplatBits, SplatUndef;
  unsigned SplatBitSize;
  bool HasAnyUndefs;

  unsigned UseNeonMov = VT.getSizeInBits() >= 64;

  // Note we favor lowering MOVI over MVNI.
  // This has implications on the definition of patterns in TableGen to select
  // BIC immediate instructions but not ORR immediate instructions.
  // If this lowering order is changed, TableGen patterns for BIC immediate and
  // ORR immediate instructions have to be updated.
  if (UseNeonMov &&
      BVN->isConstantSplat(SplatBits, SplatUndef, SplatBitSize, HasAnyUndefs)) {
    if (SplatBitSize <= 64) {
      // First attempt to use vector immediate-form MOVI
      EVT NeonMovVT;
      unsigned Imm = 0;
      unsigned OpCmode = 0;

      if (isNeonModifiedImm(SplatBits.getZExtValue(), SplatUndef.getZExtValue(),
                            SplatBitSize, DAG, VT.is128BitVector(),
                            Neon_Mov_Imm, NeonMovVT, Imm, OpCmode)) {
        SDValue ImmVal = DAG.getTargetConstant(Imm, MVT::i32);
        SDValue OpCmodeVal = DAG.getConstant(OpCmode, MVT::i32);

        if (ImmVal.getNode() && OpCmodeVal.getNode()) {
          SDValue NeonMov = DAG.getNode(AArch64ISD::NEON_MOVIMM, DL, NeonMovVT,
                                        ImmVal, OpCmodeVal);
          return DAG.getNode(ISD::BITCAST, DL, VT, NeonMov);
        }
      }

      // Then attempt to use vector immediate-form MVNI
      uint64_t NegatedImm = (~SplatBits).getZExtValue();
      if (isNeonModifiedImm(NegatedImm, SplatUndef.getZExtValue(), SplatBitSize,
                            DAG, VT.is128BitVector(), Neon_Mvn_Imm, NeonMovVT,
                            Imm, OpCmode)) {
        SDValue ImmVal = DAG.getTargetConstant(Imm, MVT::i32);
        SDValue OpCmodeVal = DAG.getConstant(OpCmode, MVT::i32);
        if (ImmVal.getNode() && OpCmodeVal.getNode()) {
          SDValue NeonMov = DAG.getNode(AArch64ISD::NEON_MVNIMM, DL, NeonMovVT,
                                        ImmVal, OpCmodeVal);
          return DAG.getNode(ISD::BITCAST, DL, VT, NeonMov);
        }
      }

      // Attempt to use vector immediate-form FMOV
      if (((VT == MVT::v2f32 || VT == MVT::v4f32) && SplatBitSize == 32) ||
          (VT == MVT::v2f64 && SplatBitSize == 64)) {
        APFloat RealVal(
            SplatBitSize == 32 ? APFloat::IEEEsingle : APFloat::IEEEdouble,
            SplatBits);
        uint32_t ImmVal;
        if (A64Imms::isFPImm(RealVal, ImmVal)) {
          SDValue Val = DAG.getTargetConstant(ImmVal, MVT::i32);
          return DAG.getNode(AArch64ISD::NEON_FMOVIMM, DL, VT, Val);
        }
      }
    }
  }

  unsigned NumElts = VT.getVectorNumElements();
  bool isOnlyLowElement = true;
  bool usesOnlyOneValue = true;
  bool hasDominantValue = false;
  bool isConstant = true;

  // Map of the number of times a particular SDValue appears in the
  // element list.
  DenseMap<SDValue, unsigned> ValueCounts;
  SDValue Value;
  for (unsigned i = 0; i < NumElts; ++i) {
    SDValue V = Op.getOperand(i);
    if (V.getOpcode() == ISD::UNDEF)
      continue;
    if (i > 0)
      isOnlyLowElement = false;
    if (!isa<ConstantFPSDNode>(V) && !isa<ConstantSDNode>(V))
      isConstant = false;

    ValueCounts.insert(std::make_pair(V, 0));
    unsigned &Count = ValueCounts[V];

    // Is this value dominant? (takes up more than half of the lanes)
    if (++Count > (NumElts / 2)) {
      hasDominantValue = true;
      Value = V;
    }
  }
  if (ValueCounts.size() != 1)
    usesOnlyOneValue = false;
  if (!Value.getNode() && ValueCounts.size() > 0)
    Value = ValueCounts.begin()->first;

  if (ValueCounts.size() == 0)
    return DAG.getUNDEF(VT);

  // Loads are better lowered with insert_vector_elt.
  // Keep going if we are hitting this case.
  if (isOnlyLowElement && !ISD::isNormalLoad(Value.getNode()))
    return DAG.getNode(ISD::SCALAR_TO_VECTOR, DL, VT, Value);

  unsigned EltSize = VT.getVectorElementType().getSizeInBits();
  if (hasDominantValue && EltSize <= 64) {
    // Use VDUP for non-constant splats.
    if (!isConstant) {
      SDValue N;

      // If we are DUPing a value that comes directly from a vector, we could
      // just use DUPLANE. We can only do this if the lane being extracted
      // is at a constant index, as the DUP from lane instructions only have
      // constant-index forms.
      if (Value->getOpcode() == ISD::EXTRACT_VECTOR_ELT &&
          isa<ConstantSDNode>(Value->getOperand(1))) {
          N = DAG.getNode(AArch64ISD::NEON_VDUPLANE, DL, VT,
                        Value->getOperand(0), Value->getOperand(1));
      } else
        N = DAG.getNode(AArch64ISD::NEON_VDUP, DL, VT, Value);

      if (!usesOnlyOneValue) {
        // The dominant value was splatted as 'N', but we now have to insert
        // all differing elements.
        for (unsigned I = 0; I < NumElts; ++I) {
          if (Op.getOperand(I) == Value)
            continue;
          SmallVector<SDValue, 3> Ops;
          Ops.push_back(N);
          Ops.push_back(Op.getOperand(I));
          Ops.push_back(DAG.getConstant(I, MVT::i64));
          N = DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, VT, &Ops[0], 3);
        }
      }
      return N;
    }
    if (usesOnlyOneValue && isConstant) {
      return DAG.getNode(AArch64ISD::NEON_VDUP, DL, VT, Value);
    }
  }
  // If all elements are constants and the case above didn't get hit, fall back
  // to the default expansion, which will generate a load from the constant
  // pool.
  if (isConstant)
    return SDValue();

  // Try to lower this in lowering ShuffleVector way.
  SDValue Shuf;
  if (isKnownShuffleVector(Op, DAG, Shuf))
    return Shuf;

  // If all else fails, just use a sequence of INSERT_VECTOR_ELT when we
  // know the default expansion would otherwise fall back on something even
  // worse. For a vector with one or two non-undef values, that's
  // scalar_to_vector for the elements followed by a shuffle (provided the
  // shuffle is valid for the target) and materialization element by element
  // on the stack followed by a load for everything else.
  if (!isConstant && !usesOnlyOneValue) {
    SDValue Vec = DAG.getUNDEF(VT);
    for (unsigned i = 0 ; i < NumElts; ++i) {
      SDValue V = Op.getOperand(i);
      if (V.getOpcode() == ISD::UNDEF)
        continue;
      SDValue LaneIdx = DAG.getConstant(i, MVT::i64);
      Vec = DAG.getNode(ISD::INSERT_VECTOR_ELT, DL, VT, Vec, V, LaneIdx);
    }
    return Vec;
  }
  return SDValue();
}

/// isREVMask - Check if a vector shuffle corresponds to a REV
/// instruction with the specified blocksize.  (The order of the elements
/// within each block of the vector is reversed.)
static bool isREVMask(ArrayRef<int> M, EVT VT, unsigned BlockSize) {
  assert((BlockSize == 16 || BlockSize == 32 || BlockSize == 64) &&
         "Only possible block sizes for REV are: 16, 32, 64");

  unsigned EltSz = VT.getVectorElementType().getSizeInBits();
  if (EltSz == 64)
    return false;

  unsigned NumElts = VT.getVectorNumElements();
  unsigned BlockElts = M[0] + 1;
  // If the first shuffle index is UNDEF, be optimistic.
  if (M[0] < 0)
    BlockElts = BlockSize / EltSz;

  if (BlockSize <= EltSz || BlockSize != BlockElts * EltSz)
    return false;

  for (unsigned i = 0; i < NumElts; ++i) {
    if (M[i] < 0)
      continue; // ignore UNDEF indices
    if ((unsigned)M[i] != (i - i % BlockElts) + (BlockElts - 1 - i % BlockElts))
      return false;
  }

  return true;
}

// isPermuteMask - Check whether the vector shuffle matches to UZP, ZIP and
// TRN instruction.
static unsigned isPermuteMask(ArrayRef<int> M, EVT VT) {
  unsigned NumElts = VT.getVectorNumElements();
  if (NumElts < 4)
    return 0;

  bool ismatch = true;

  // Check UZP1
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != i * 2) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_UZP1;

  // Check UZP2
  ismatch = true;
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != i * 2 + 1) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_UZP2;

  // Check ZIP1
  ismatch = true;
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != i / 2 + NumElts * (i % 2)) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_ZIP1;

  // Check ZIP2
  ismatch = true;
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != (NumElts + i) / 2 + NumElts * (i % 2)) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_ZIP2;

  // Check TRN1
  ismatch = true;
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != i + (NumElts - 1) * (i % 2)) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_TRN1;

  // Check TRN2
  ismatch = true;
  for (unsigned i = 0; i < NumElts; ++i) {
    if ((unsigned)M[i] != 1 + i + (NumElts - 1) * (i % 2)) {
      ismatch = false;
      break;
    }
  }
  if (ismatch)
    return AArch64ISD::NEON_TRN2;

  return 0;
}

SDValue
AArch64TargetLowering::LowerVECTOR_SHUFFLE(SDValue Op,
                                           SelectionDAG &DAG) const {
  SDValue V1 = Op.getOperand(0);
  SDValue V2 = Op.getOperand(1);
  SDLoc dl(Op);
  EVT VT = Op.getValueType();
  ShuffleVectorSDNode *SVN = cast<ShuffleVectorSDNode>(Op.getNode());

  // Convert shuffles that are directly supported on NEON to target-specific
  // DAG nodes, instead of keeping them as shuffles and matching them again
  // during code selection.  This is more efficient and avoids the possibility
  // of inconsistencies between legalization and selection.
  ArrayRef<int> ShuffleMask = SVN->getMask();

  unsigned EltSize = VT.getVectorElementType().getSizeInBits();
  if (EltSize > 64)
    return SDValue();

  if (isREVMask(ShuffleMask, VT, 64))
    return DAG.getNode(AArch64ISD::NEON_REV64, dl, VT, V1);
  if (isREVMask(ShuffleMask, VT, 32))
    return DAG.getNode(AArch64ISD::NEON_REV32, dl, VT, V1);
  if (isREVMask(ShuffleMask, VT, 16))
    return DAG.getNode(AArch64ISD::NEON_REV16, dl, VT, V1);

  unsigned ISDNo = isPermuteMask(ShuffleMask, VT);
  if (ISDNo)
    return DAG.getNode(ISDNo, dl, VT, V1, V2);

  // If the element of shuffle mask are all the same constant, we can
  // transform it into either NEON_VDUP or NEON_VDUPLANE
  if (ShuffleVectorSDNode::isSplatMask(&ShuffleMask[0], VT)) {
    int Lane = SVN->getSplatIndex();
    // If this is undef splat, generate it via "just" vdup, if possible.
    if (Lane == -1) Lane = 0;

    // Test if V1 is a SCALAR_TO_VECTOR.
    if (V1.getOpcode() == ISD::SCALAR_TO_VECTOR) {
      return DAG.getNode(AArch64ISD::NEON_VDUP, dl, VT, V1.getOperand(0));
    }
    // Test if V1 is a BUILD_VECTOR which is equivalent to a SCALAR_TO_VECTOR.
    if (V1.getOpcode() == ISD::BUILD_VECTOR) {
      bool IsScalarToVector = true;
      for (unsigned i = 0, e = V1.getNumOperands(); i != e; ++i)
        if (V1.getOperand(i).getOpcode() != ISD::UNDEF &&
            i != (unsigned)Lane) {
          IsScalarToVector = false;
          break;
        }
      if (IsScalarToVector)
        return DAG.getNode(AArch64ISD::NEON_VDUP, dl, VT,
                           V1.getOperand(Lane));
    }

    // Test if V1 is a EXTRACT_SUBVECTOR.
    if (V1.getOpcode() == ISD::EXTRACT_SUBVECTOR) {
      int ExtLane = cast<ConstantSDNode>(V1.getOperand(1))->getZExtValue();
      return DAG.getNode(AArch64ISD::NEON_VDUPLANE, dl, VT, V1.getOperand(0),
                         DAG.getConstant(Lane + ExtLane, MVT::i64));
    }
    // Test if V1 is a CONCAT_VECTORS.
    if (V1.getOpcode() == ISD::CONCAT_VECTORS &&
        V1.getOperand(1).getOpcode() == ISD::UNDEF) {
      SDValue Op0 = V1.getOperand(0);
      assert((unsigned)Lane < Op0.getValueType().getVectorNumElements() &&
             "Invalid vector lane access");
      return DAG.getNode(AArch64ISD::NEON_VDUPLANE, dl, VT, Op0,
                         DAG.getConstant(Lane, MVT::i64));
    }

    return DAG.getNode(AArch64ISD::NEON_VDUPLANE, dl, VT, V1,
                       DAG.getConstant(Lane, MVT::i64));
  }

  int Length = ShuffleMask.size();
  int V1EltNum = V1.getValueType().getVectorNumElements();

  // If the number of v1 elements is the same as the number of shuffle mask
  // element and the shuffle masks are sequential values, we can transform
  // it into NEON_VEXTRACT.
  if (V1EltNum == Length) {
    // Check if the shuffle mask is sequential.
    bool IsSequential = true;
    int CurMask = ShuffleMask[0];
    for (int I = 0; I < Length; ++I) {
      if (ShuffleMask[I] != CurMask) {
        IsSequential = false;
        break;
      }
      CurMask++;
    }
    if (IsSequential) {
      assert((EltSize % 8 == 0) && "Bitsize of vector element is incorrect");
      unsigned VecSize = EltSize * V1EltNum;
      unsigned Index = (EltSize/8) * ShuffleMask[0];
      if (VecSize == 64 || VecSize == 128)
        return DAG.getNode(AArch64ISD::NEON_VEXTRACT, dl, VT, V1, V2,
                           DAG.getConstant(Index, MVT::i64));
    }
  }

  // For shuffle mask like "0, 1, 2, 3, 4, 5, 13, 7", try to generate insert
  // by element from V2 to V1 .
  // If shuffle mask is like "0, 1, 10, 11, 12, 13, 14, 15", V2 would be a
  // better choice to be inserted than V1 as less insert needed, so we count
  // element to be inserted for both V1 and V2, and select less one as insert
  // target.

  // Collect elements need to be inserted and their index.
  SmallVector<int, 8> NV1Elt;
  SmallVector<int, 8> N1Index;
  SmallVector<int, 8> NV2Elt;
  SmallVector<int, 8> N2Index;
  for (int I = 0; I != Length; ++I) {
    if (ShuffleMask[I] != I) {
      NV1Elt.push_back(ShuffleMask[I]);
      N1Index.push_back(I);
    }
  }
  for (int I = 0; I != Length; ++I) {
    if (ShuffleMask[I] != (I + V1EltNum)) {
      NV2Elt.push_back(ShuffleMask[I]);
      N2Index.push_back(I);
    }
  }

  // Decide which to be inserted. If all lanes mismatch, neither V1 nor V2
  // will be inserted.
  SDValue InsV = V1;
  SmallVector<int, 8> InsMasks = NV1Elt;
  SmallVector<int, 8> InsIndex = N1Index;
  if ((int)NV1Elt.size() != Length || (int)NV2Elt.size() != Length) {
    if (NV1Elt.size() > NV2Elt.size()) {
      InsV = V2;
      InsMasks = NV2Elt;
      InsIndex = N2Index;
    }
  } else {
    InsV = DAG.getNode(ISD::UNDEF, dl, VT);
  }

  for (int I = 0, E = InsMasks.size(); I != E; ++I) {
    SDValue ExtV = V1;
    int Mask = InsMasks[I];
    if (Mask >= V1EltNum) {
      ExtV = V2;
      Mask -= V1EltNum;
    }
    // Any value type smaller than i32 is illegal in AArch64, and this lower
    // function is called after legalize pass, so we need to legalize
    // the result here.
    EVT EltVT;
    if (VT.getVectorElementType().isFloatingPoint())
      EltVT = (EltSize == 64) ? MVT::f64 : MVT::f32;
    else
      EltVT = (EltSize == 64) ? MVT::i64 : MVT::i32;

    if (Mask >= 0) {
      ExtV = DAG.getNode(ISD::EXTRACT_VECTOR_ELT, dl, EltVT, ExtV,
                         DAG.getConstant(Mask, MVT::i64));
      InsV = DAG.getNode(ISD::INSERT_VECTOR_ELT, dl, VT, InsV, ExtV,
                         DAG.getConstant(InsIndex[I], MVT::i64));
    }
  }
  return InsV;
}

AArch64TargetLowering::ConstraintType
AArch64TargetLowering::getConstraintType(const std::string &Constraint) const {
  if (Constraint.size() == 1) {
    switch (Constraint[0]) {
    default: break;
    case 'w': // An FP/SIMD vector register
      return C_RegisterClass;
    case 'I': // Constant that can be used with an ADD instruction
    case 'J': // Constant that can be used with a SUB instruction
    case 'K': // Constant that can be used with a 32-bit logical instruction
    case 'L': // Constant that can be used with a 64-bit logical instruction
    case 'M': // Constant that can be used as a 32-bit MOV immediate
    case 'N': // Constant that can be used as a 64-bit MOV immediate
    case 'Y': // Floating point constant zero
    case 'Z': // Integer constant zero
      return C_Other;
    case 'Q': // A memory reference with base register and no offset
      return C_Memory;
    case 'S': // A symbolic address
      return C_Other;
    }
  }

  // FIXME: Ump, Utf, Usa, Ush
  // Ump: A memory address suitable for ldp/stp in SI, DI, SF and DF modes,
  //      whatever they may be
  // Utf: A memory address suitable for ldp/stp in TF mode, whatever it may be
  // Usa: An absolute symbolic address
  // Ush: The high part (bits 32:12) of a pc-relative symbolic address
  assert(Constraint != "Ump" && Constraint != "Utf" && Constraint != "Usa"
         && Constraint != "Ush" && "Unimplemented constraints");

  return TargetLowering::getConstraintType(Constraint);
}

TargetLowering::ConstraintWeight
AArch64TargetLowering::getSingleConstraintMatchWeight(AsmOperandInfo &Info,
                                                const char *Constraint) const {

  llvm_unreachable("Constraint weight unimplemented");
}

void
AArch64TargetLowering::LowerAsmOperandForConstraint(SDValue Op,
                                                    std::string &Constraint,
                                                    std::vector<SDValue> &Ops,
                                                    SelectionDAG &DAG) const {
  SDValue Result(0, 0);

  // Only length 1 constraints are C_Other.
  if (Constraint.size() != 1) return;

  // Only C_Other constraints get lowered like this. That means constants for us
  // so return early if there's no hope the constraint can be lowered.

  switch(Constraint[0]) {
  default: break;
  case 'I': case 'J': case 'K': case 'L':
  case 'M': case 'N': case 'Z': {
    ConstantSDNode *C = dyn_cast<ConstantSDNode>(Op);
    if (!C)
      return;

    uint64_t CVal = C->getZExtValue();
    uint32_t Bits;

    switch (Constraint[0]) {
    default:
      // FIXME: 'M' and 'N' are MOV pseudo-insts -- unsupported in assembly. 'J'
      // is a peculiarly useless SUB constraint.
      llvm_unreachable("Unimplemented C_Other constraint");
    case 'I':
      if (CVal <= 0xfff)
        break;
      return;
    case 'K':
      if (A64Imms::isLogicalImm(32, CVal, Bits))
        break;
      return;
    case 'L':
      if (A64Imms::isLogicalImm(64, CVal, Bits))
        break;
      return;
    case 'Z':
      if (CVal == 0)
        break;
      return;
    }

    Result = DAG.getTargetConstant(CVal, Op.getValueType());
    break;
  }
  case 'S': {
    // An absolute symbolic address or label reference.
    if (const GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op)) {
      Result = DAG.getTargetGlobalAddress(GA->getGlobal(), SDLoc(Op),
                                          GA->getValueType(0));
    } else if (const BlockAddressSDNode *BA
                 = dyn_cast<BlockAddressSDNode>(Op)) {
      Result = DAG.getTargetBlockAddress(BA->getBlockAddress(),
                                         BA->getValueType(0));
    } else if (const ExternalSymbolSDNode *ES
                 = dyn_cast<ExternalSymbolSDNode>(Op)) {
      Result = DAG.getTargetExternalSymbol(ES->getSymbol(),
                                           ES->getValueType(0));
    } else
      return;
    break;
  }
  case 'Y':
    if (const ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(Op)) {
      if (CFP->isExactlyValue(0.0)) {
        Result = DAG.getTargetConstantFP(0.0, CFP->getValueType(0));
        break;
      }
    }
    return;
  }

  if (Result.getNode()) {
    Ops.push_back(Result);
    return;
  }

  // It's an unknown constraint for us. Let generic code have a go.
  TargetLowering::LowerAsmOperandForConstraint(Op, Constraint, Ops, DAG);
}

std::pair<unsigned, const TargetRegisterClass*>
AArch64TargetLowering::getRegForInlineAsmConstraint(
                                                  const std::string &Constraint,
                                                  MVT VT) const {
  if (Constraint.size() == 1) {
    switch (Constraint[0]) {
    case 'r':
      if (VT.getSizeInBits() <= 32)
        return std::make_pair(0U, &AArch64::GPR32RegClass);
      else if (VT == MVT::i64)
        return std::make_pair(0U, &AArch64::GPR64RegClass);
      break;
    case 'w':
      if (VT == MVT::f16)
        return std::make_pair(0U, &AArch64::FPR16RegClass);
      else if (VT == MVT::f32)
        return std::make_pair(0U, &AArch64::FPR32RegClass);
      else if (VT.getSizeInBits() == 64)
        return std::make_pair(0U, &AArch64::FPR64RegClass);
      else if (VT.getSizeInBits() == 128)
        return std::make_pair(0U, &AArch64::FPR128RegClass);
      break;
    }
  }

  // Use the default implementation in TargetLowering to convert the register
  // constraint into a member of a register class.
  return TargetLowering::getRegForInlineAsmConstraint(Constraint, VT);
}

/// Represent NEON load and store intrinsics as MemIntrinsicNodes.
/// The associated MachineMemOperands record the alignment specified
/// in the intrinsic calls.
bool AArch64TargetLowering::getTgtMemIntrinsic(IntrinsicInfo &Info,
                                               const CallInst &I,
                                               unsigned Intrinsic) const {
  switch (Intrinsic) {
  case Intrinsic::arm_neon_vld1:
  case Intrinsic::arm_neon_vld2:
  case Intrinsic::arm_neon_vld3:
  case Intrinsic::arm_neon_vld4:
  case Intrinsic::aarch64_neon_vld1x2:
  case Intrinsic::aarch64_neon_vld1x3:
  case Intrinsic::aarch64_neon_vld1x4:
  case Intrinsic::arm_neon_vld2lane:
  case Intrinsic::arm_neon_vld3lane:
  case Intrinsic::arm_neon_vld4lane: {
    Info.opc = ISD::INTRINSIC_W_CHAIN;
    // Conservatively set memVT to the entire set of vectors loaded.
    uint64_t NumElts = getDataLayout()->getTypeAllocSize(I.getType()) / 8;
    Info.memVT = EVT::getVectorVT(I.getType()->getContext(), MVT::i64, NumElts);
    Info.ptrVal = I.getArgOperand(0);
    Info.offset = 0;
    Value *AlignArg = I.getArgOperand(I.getNumArgOperands() - 1);
    Info.align = cast<ConstantInt>(AlignArg)->getZExtValue();
    Info.vol = false; // volatile loads with NEON intrinsics not supported
    Info.readMem = true;
    Info.writeMem = false;
    return true;
  }
  case Intrinsic::arm_neon_vst1:
  case Intrinsic::arm_neon_vst2:
  case Intrinsic::arm_neon_vst3:
  case Intrinsic::arm_neon_vst4:
  case Intrinsic::aarch64_neon_vst1x2:
  case Intrinsic::aarch64_neon_vst1x3:
  case Intrinsic::aarch64_neon_vst1x4:
  case Intrinsic::arm_neon_vst2lane:
  case Intrinsic::arm_neon_vst3lane:
  case Intrinsic::arm_neon_vst4lane: {
    Info.opc = ISD::INTRINSIC_VOID;
    // Conservatively set memVT to the entire set of vectors stored.
    unsigned NumElts = 0;
    for (unsigned ArgI = 1, ArgE = I.getNumArgOperands(); ArgI < ArgE; ++ArgI) {
      Type *ArgTy = I.getArgOperand(ArgI)->getType();
      if (!ArgTy->isVectorTy())
        break;
      NumElts += getDataLayout()->getTypeAllocSize(ArgTy) / 8;
    }
    Info.memVT = EVT::getVectorVT(I.getType()->getContext(), MVT::i64, NumElts);
    Info.ptrVal = I.getArgOperand(0);
    Info.offset = 0;
    Value *AlignArg = I.getArgOperand(I.getNumArgOperands() - 1);
    Info.align = cast<ConstantInt>(AlignArg)->getZExtValue();
    Info.vol = false; // volatile stores with NEON intrinsics not supported
    Info.readMem = false;
    Info.writeMem = true;
    return true;
  }
  default:
    break;
  }

  return false;
}
