llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp

//===- ARMTargetTransformInfo.cpp - ARM specific TTI ----------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "ARMTargetTransformInfo.h"
#include "ARMSubtarget.h"
#include "MCTargetDesc/ARMAddressingModes.h"
#include "llvm/ADT/APInt.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/CodeGen/ISDOpcodes.h"
#include "llvm/CodeGen/MachineValueType.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/Type.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/Casting.h"
#include "llvm/Target/CostTable.h"
#include "llvm/Target/TargetMachine.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <utility>

using namespace llvm;

#define DEBUG_TYPE "armtti"

bool ARMTTIImpl::areInlineCompatible(const Function *Caller,
                                     const Function *Callee) const {
  const TargetMachine &TM = getTLI()->getTargetMachine();
  const FeatureBitset &CallerBits =
      TM.getSubtargetImpl(*Caller)->getFeatureBits();
  const FeatureBitset &CalleeBits =
      TM.getSubtargetImpl(*Callee)->getFeatureBits();

  // To inline a callee, all features not in the whitelist must match exactly.
  bool MatchExact = (CallerBits & ~InlineFeatureWhitelist) ==
                    (CalleeBits & ~InlineFeatureWhitelist);
  // For features in the whitelist, the callee's features must be a subset of
  // the callers'.
  bool MatchSubset = ((CallerBits & CalleeBits) & InlineFeatureWhitelist) ==
                     (CalleeBits & InlineFeatureWhitelist);
  return MatchExact && MatchSubset;
}

int ARMTTIImpl::getIntImmCost(const APInt &Imm, Type *Ty) {
  assert(Ty->isIntegerTy());

 unsigned Bits = Ty->getPrimitiveSizeInBits();
 if (Bits == 0 || Imm.getActiveBits() >= 64)
   return 4;

  int64_t SImmVal = Imm.getSExtValue();
  uint64_t ZImmVal = Imm.getZExtValue();
  if (!ST->isThumb()) {
    if ((SImmVal >= 0 && SImmVal < 65536) ||
        (ARM_AM::getSOImmVal(ZImmVal) != -1) ||
        (ARM_AM::getSOImmVal(~ZImmVal) != -1))
      return 1;
    return ST->hasV6T2Ops() ? 2 : 3;
  }
  if (ST->isThumb2()) {
    if ((SImmVal >= 0 && SImmVal < 65536) ||
        (ARM_AM::getT2SOImmVal(ZImmVal) != -1) ||
        (ARM_AM::getT2SOImmVal(~ZImmVal) != -1))
      return 1;
    return ST->hasV6T2Ops() ? 2 : 3;
  }
  // Thumb1.
  if (SImmVal >= 0 && SImmVal < 256)
    return 1;
  if ((~SImmVal < 256) || ARM_AM::isThumbImmShiftedVal(ZImmVal))
    return 2;
  // Load from constantpool.
  return 3;
}

// Constants smaller than 256 fit in the immediate field of
// Thumb1 instructions so we return a zero cost and 1 otherwise.
int ARMTTIImpl::getIntImmCodeSizeCost(unsigned Opcode, unsigned Idx,
                                      const APInt &Imm, Type *Ty) {
  if (Imm.isNonNegative() && Imm.getLimitedValue() < 256)
    return 0;

  return 1;
}

int ARMTTIImpl::getIntImmCost(unsigned Opcode, unsigned Idx, const APInt &Imm,
                              Type *Ty) {
  // Division by a constant can be turned into multiplication, but only if we
  // know it's constant. So it's not so much that the immediate is cheap (it's
  // not), but that the alternative is worse.
  // FIXME: this is probably unneeded with GlobalISel.
  if ((Opcode == Instruction::SDiv || Opcode == Instruction::UDiv ||
       Opcode == Instruction::SRem || Opcode == Instruction::URem) &&
      Idx == 1)
    return 0;

  if (Opcode == Instruction::And)
      // Conversion to BIC is free, and means we can use ~Imm instead.
      return std::min(getIntImmCost(Imm, Ty), getIntImmCost(~Imm, Ty));

  if (Opcode == Instruction::Add)
    // Conversion to SUB is free, and means we can use -Imm instead.
    return std::min(getIntImmCost(Imm, Ty), getIntImmCost(-Imm, Ty));

  if (Opcode == Instruction::ICmp && Imm.isNegative() &&
      Ty->getIntegerBitWidth() == 32) {
    int64_t NegImm = -Imm.getSExtValue();
    if (ST->isThumb2() && NegImm < 1<<12)
      // icmp X, #-C -> cmn X, #C
      return 0;
    if (ST->isThumb() && NegImm < 1<<8)
      // icmp X, #-C -> adds X, #C
      return 0;
  }

  return getIntImmCost(Imm, Ty);
}

int ARMTTIImpl::getCastInstrCost(unsigned Opcode, Type *Dst, Type *Src,
                                 const Instruction *I) {
  int ISD = TLI->InstructionOpcodeToISD(Opcode);
  assert(ISD && "Invalid opcode");

  // Single to/from double precision conversions.
  static const CostTblEntry NEONFltDblTbl[] = {
    // Vector fptrunc/fpext conversions.
    { ISD::FP_ROUND,   MVT::v2f64, 2 },
    { ISD::FP_EXTEND,  MVT::v2f32, 2 },
    { ISD::FP_EXTEND,  MVT::v4f32, 4 }
  };

  if (Src->isVectorTy() && ST->hasNEON() && (ISD == ISD::FP_ROUND ||
                                          ISD == ISD::FP_EXTEND)) {
    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);
    if (const auto *Entry = CostTableLookup(NEONFltDblTbl, ISD, LT.second))
      return LT.first * Entry->Cost;
  }

  EVT SrcTy = TLI->getValueType(DL, Src);
  EVT DstTy = TLI->getValueType(DL, Dst);

  if (!SrcTy.isSimple() || !DstTy.isSimple())
    return BaseT::getCastInstrCost(Opcode, Dst, Src);

  // Some arithmetic, load and store operations have specific instructions
  // to cast up/down their types automatically at no extra cost.
  // TODO: Get these tables to know at least what the related operations are.
  static const TypeConversionCostTblEntry NEONVectorConversionTbl[] = {
    { ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
    { ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
    { ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
    { ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
    { ISD::TRUNCATE,    MVT::v4i32, MVT::v4i64, 0 },
    { ISD::TRUNCATE,    MVT::v4i16, MVT::v4i32, 1 },

    // The number of vmovl instructions for the extension.
    { ISD::SIGN_EXTEND, MVT::v4i64, MVT::v4i16, 3 },
    { ISD::ZERO_EXTEND, MVT::v4i64, MVT::v4i16, 3 },
    { ISD::SIGN_EXTEND, MVT::v8i32, MVT::v8i8, 3 },
    { ISD::ZERO_EXTEND, MVT::v8i32, MVT::v8i8, 3 },
    { ISD::SIGN_EXTEND, MVT::v8i64, MVT::v8i8, 7 },
    { ISD::ZERO_EXTEND, MVT::v8i64, MVT::v8i8, 7 },
    { ISD::SIGN_EXTEND, MVT::v8i64, MVT::v8i16, 6 },
    { ISD::ZERO_EXTEND, MVT::v8i64, MVT::v8i16, 6 },
    { ISD::SIGN_EXTEND, MVT::v16i32, MVT::v16i8, 6 },
    { ISD::ZERO_EXTEND, MVT::v16i32, MVT::v16i8, 6 },

    // Operations that we legalize using splitting.
    { ISD::TRUNCATE,    MVT::v16i8, MVT::v16i32, 6 },
    { ISD::TRUNCATE,    MVT::v8i8, MVT::v8i32, 3 },

    // Vector float <-> i32 conversions.
    { ISD::SINT_TO_FP,  MVT::v4f32, MVT::v4i32, 1 },
    { ISD::UINT_TO_FP,  MVT::v4f32, MVT::v4i32, 1 },

    { ISD::SINT_TO_FP,  MVT::v2f32, MVT::v2i8, 3 },
    { ISD::UINT_TO_FP,  MVT::v2f32, MVT::v2i8, 3 },
    { ISD::SINT_TO_FP,  MVT::v2f32, MVT::v2i16, 2 },
    { ISD::UINT_TO_FP,  MVT::v2f32, MVT::v2i16, 2 },
    { ISD::SINT_TO_FP,  MVT::v2f32, MVT::v2i32, 1 },
    { ISD::UINT_TO_FP,  MVT::v2f32, MVT::v2i32, 1 },
    { ISD::SINT_TO_FP,  MVT::v4f32, MVT::v4i1, 3 },
    { ISD::UINT_TO_FP,  MVT::v4f32, MVT::v4i1, 3 },
    { ISD::SINT_TO_FP,  MVT::v4f32, MVT::v4i8, 3 },
    { ISD::UINT_TO_FP,  MVT::v4f32, MVT::v4i8, 3 },
    { ISD::SINT_TO_FP,  MVT::v4f32, MVT::v4i16, 2 },
    { ISD::UINT_TO_FP,  MVT::v4f32, MVT::v4i16, 2 },
    { ISD::SINT_TO_FP,  MVT::v8f32, MVT::v8i16, 4 },
    { ISD::UINT_TO_FP,  MVT::v8f32, MVT::v8i16, 4 },
    { ISD::SINT_TO_FP,  MVT::v8f32, MVT::v8i32, 2 },
    { ISD::UINT_TO_FP,  MVT::v8f32, MVT::v8i32, 2 },
    { ISD::SINT_TO_FP,  MVT::v16f32, MVT::v16i16, 8 },
    { ISD::UINT_TO_FP,  MVT::v16f32, MVT::v16i16, 8 },
    { ISD::SINT_TO_FP,  MVT::v16f32, MVT::v16i32, 4 },
    { ISD::UINT_TO_FP,  MVT::v16f32, MVT::v16i32, 4 },

    { ISD::FP_TO_SINT,  MVT::v4i32, MVT::v4f32, 1 },
    { ISD::FP_TO_UINT,  MVT::v4i32, MVT::v4f32, 1 },
    { ISD::FP_TO_SINT,  MVT::v4i8, MVT::v4f32, 3 },
    { ISD::FP_TO_UINT,  MVT::v4i8, MVT::v4f32, 3 },
    { ISD::FP_TO_SINT,  MVT::v4i16, MVT::v4f32, 2 },
    { ISD::FP_TO_UINT,  MVT::v4i16, MVT::v4f32, 2 },

    // Vector double <-> i32 conversions.
    { ISD::SINT_TO_FP,  MVT::v2f64, MVT::v2i32, 2 },
    { ISD::UINT_TO_FP,  MVT::v2f64, MVT::v2i32, 2 },

    { ISD::SINT_TO_FP,  MVT::v2f64, MVT::v2i8, 4 },
    { ISD::UINT_TO_FP,  MVT::v2f64, MVT::v2i8, 4 },
    { ISD::SINT_TO_FP,  MVT::v2f64, MVT::v2i16, 3 },
    { ISD::UINT_TO_FP,  MVT::v2f64, MVT::v2i16, 3 },
    { ISD::SINT_TO_FP,  MVT::v2f64, MVT::v2i32, 2 },
    { ISD::UINT_TO_FP,  MVT::v2f64, MVT::v2i32, 2 },

    { ISD::FP_TO_SINT,  MVT::v2i32, MVT::v2f64, 2 },
    { ISD::FP_TO_UINT,  MVT::v2i32, MVT::v2f64, 2 },
    { ISD::FP_TO_SINT,  MVT::v8i16, MVT::v8f32, 4 },
    { ISD::FP_TO_UINT,  MVT::v8i16, MVT::v8f32, 4 },
    { ISD::FP_TO_SINT,  MVT::v16i16, MVT::v16f32, 8 },
    { ISD::FP_TO_UINT,  MVT::v16i16, MVT::v16f32, 8 }
  };

  if (SrcTy.isVector() && ST->hasNEON()) {
    if (const auto *Entry = ConvertCostTableLookup(NEONVectorConversionTbl, ISD,
                                                   DstTy.getSimpleVT(),
                                                   SrcTy.getSimpleVT()))
      return Entry->Cost;
  }

  // Scalar float to integer conversions.
  static const TypeConversionCostTblEntry NEONFloatConversionTbl[] = {
    { ISD::FP_TO_SINT,  MVT::i1, MVT::f32, 2 },
    { ISD::FP_TO_UINT,  MVT::i1, MVT::f32, 2 },
    { ISD::FP_TO_SINT,  MVT::i1, MVT::f64, 2 },
    { ISD::FP_TO_UINT,  MVT::i1, MVT::f64, 2 },
    { ISD::FP_TO_SINT,  MVT::i8, MVT::f32, 2 },
    { ISD::FP_TO_UINT,  MVT::i8, MVT::f32, 2 },
    { ISD::FP_TO_SINT,  MVT::i8, MVT::f64, 2 },
    { ISD::FP_TO_UINT,  MVT::i8, MVT::f64, 2 },
    { ISD::FP_TO_SINT,  MVT::i16, MVT::f32, 2 },
    { ISD::FP_TO_UINT,  MVT::i16, MVT::f32, 2 },
    { ISD::FP_TO_SINT,  MVT::i16, MVT::f64, 2 },
    { ISD::FP_TO_UINT,  MVT::i16, MVT::f64, 2 },
    { ISD::FP_TO_SINT,  MVT::i32, MVT::f32, 2 },
    { ISD::FP_TO_UINT,  MVT::i32, MVT::f32, 2 },
    { ISD::FP_TO_SINT,  MVT::i32, MVT::f64, 2 },
    { ISD::FP_TO_UINT,  MVT::i32, MVT::f64, 2 },
    { ISD::FP_TO_SINT,  MVT::i64, MVT::f32, 10 },
    { ISD::FP_TO_UINT,  MVT::i64, MVT::f32, 10 },
    { ISD::FP_TO_SINT,  MVT::i64, MVT::f64, 10 },
    { ISD::FP_TO_UINT,  MVT::i64, MVT::f64, 10 }
  };
  if (SrcTy.isFloatingPoint() && ST->hasNEON()) {
    if (const auto *Entry = ConvertCostTableLookup(NEONFloatConversionTbl, ISD,
                                                   DstTy.getSimpleVT(),
                                                   SrcTy.getSimpleVT()))
      return Entry->Cost;
  }

  // Scalar integer to float conversions.
  static const TypeConversionCostTblEntry NEONIntegerConversionTbl[] = {
    { ISD::SINT_TO_FP,  MVT::f32, MVT::i1, 2 },
    { ISD::UINT_TO_FP,  MVT::f32, MVT::i1, 2 },
    { ISD::SINT_TO_FP,  MVT::f64, MVT::i1, 2 },
    { ISD::UINT_TO_FP,  MVT::f64, MVT::i1, 2 },
    { ISD::SINT_TO_FP,  MVT::f32, MVT::i8, 2 },
    { ISD::UINT_TO_FP,  MVT::f32, MVT::i8, 2 },
    { ISD::SINT_TO_FP,  MVT::f64, MVT::i8, 2 },
    { ISD::UINT_TO_FP,  MVT::f64, MVT::i8, 2 },
    { ISD::SINT_TO_FP,  MVT::f32, MVT::i16, 2 },
    { ISD::UINT_TO_FP,  MVT::f32, MVT::i16, 2 },
    { ISD::SINT_TO_FP,  MVT::f64, MVT::i16, 2 },
    { ISD::UINT_TO_FP,  MVT::f64, MVT::i16, 2 },
    { ISD::SINT_TO_FP,  MVT::f32, MVT::i32, 2 },
    { ISD::UINT_TO_FP,  MVT::f32, MVT::i32, 2 },
    { ISD::SINT_TO_FP,  MVT::f64, MVT::i32, 2 },
    { ISD::UINT_TO_FP,  MVT::f64, MVT::i32, 2 },
    { ISD::SINT_TO_FP,  MVT::f32, MVT::i64, 10 },
    { ISD::UINT_TO_FP,  MVT::f32, MVT::i64, 10 },
    { ISD::SINT_TO_FP,  MVT::f64, MVT::i64, 10 },
    { ISD::UINT_TO_FP,  MVT::f64, MVT::i64, 10 }
  };

  if (SrcTy.isInteger() && ST->hasNEON()) {
    if (const auto *Entry = ConvertCostTableLookup(NEONIntegerConversionTbl,
                                                   ISD, DstTy.getSimpleVT(),
                                                   SrcTy.getSimpleVT()))
      return Entry->Cost;
  }

  // Scalar integer conversion costs.
  static const TypeConversionCostTblEntry ARMIntegerConversionTbl[] = {
    // i16 -> i64 requires two dependent operations.
    { ISD::SIGN_EXTEND, MVT::i64, MVT::i16, 2 },

    // Truncates on i64 are assumed to be free.
    { ISD::TRUNCATE,    MVT::i32, MVT::i64, 0 },
    { ISD::TRUNCATE,    MVT::i16, MVT::i64, 0 },
    { ISD::TRUNCATE,    MVT::i8,  MVT::i64, 0 },
    { ISD::TRUNCATE,    MVT::i1,  MVT::i64, 0 }
  };

  if (SrcTy.isInteger()) {
    if (const auto *Entry = ConvertCostTableLookup(ARMIntegerConversionTbl, ISD,
                                                   DstTy.getSimpleVT(),
                                                   SrcTy.getSimpleVT()))
      return Entry->Cost;
  }

  return BaseT::getCastInstrCost(Opcode, Dst, Src);
}

int ARMTTIImpl::getVectorInstrCost(unsigned Opcode, Type *ValTy,
                                   unsigned Index) {
  // Penalize inserting into an D-subregister. We end up with a three times
  // lower estimated throughput on swift.
  if (ST->hasSlowLoadDSubregister() && Opcode == Instruction::InsertElement &&
      ValTy->isVectorTy() && ValTy->getScalarSizeInBits() <= 32)
    return 3;

  if ((Opcode == Instruction::InsertElement ||
       Opcode == Instruction::ExtractElement)) {
    // Cross-class copies are expensive on many microarchitectures,
    // so assume they are expensive by default.
    if (ValTy->getVectorElementType()->isIntegerTy())
      return 3;

    // Even if it's not a cross class copy, this likely leads to mixing
    // of NEON and VFP code and should be therefore penalized.
    if (ValTy->isVectorTy() &&
        ValTy->getScalarSizeInBits() <= 32)
      return std::max(BaseT::getVectorInstrCost(Opcode, ValTy, Index), 2U);
  }

  return BaseT::getVectorInstrCost(Opcode, ValTy, Index);
}

int ARMTTIImpl::getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy,
                                   const Instruction *I) {
  int ISD = TLI->InstructionOpcodeToISD(Opcode);
  // On NEON a a vector select gets lowered to vbsl.
  if (ST->hasNEON() && ValTy->isVectorTy() && ISD == ISD::SELECT) {
    // Lowering of some vector selects is currently far from perfect.
    static const TypeConversionCostTblEntry NEONVectorSelectTbl[] = {
      { ISD::SELECT, MVT::v4i1, MVT::v4i64, 4*4 + 1*2 + 1 },
      { ISD::SELECT, MVT::v8i1, MVT::v8i64, 50 },
      { ISD::SELECT, MVT::v16i1, MVT::v16i64, 100 }
    };

    EVT SelCondTy = TLI->getValueType(DL, CondTy);
    EVT SelValTy = TLI->getValueType(DL, ValTy);
    if (SelCondTy.isSimple() && SelValTy.isSimple()) {
      if (const auto *Entry = ConvertCostTableLookup(NEONVectorSelectTbl, ISD,
                                                     SelCondTy.getSimpleVT(),
                                                     SelValTy.getSimpleVT()))
        return Entry->Cost;
    }

    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, ValTy);
    return LT.first;
  }

  return BaseT::getCmpSelInstrCost(Opcode, ValTy, CondTy, I);
}

int ARMTTIImpl::getAddressComputationCost(Type *Ty, ScalarEvolution *SE,
                                          const SCEV *Ptr) {
  // Address computations in vectorized code with non-consecutive addresses will
  // likely result in more instructions compared to scalar code where the
  // computation can more often be merged into the index mode. The resulting
  // extra micro-ops can significantly decrease throughput.
  unsigned NumVectorInstToHideOverhead = 10;
  int MaxMergeDistance = 64;

  if (Ty->isVectorTy() && SE && 
      !BaseT::isConstantStridedAccessLessThan(SE, Ptr, MaxMergeDistance + 1))
    return NumVectorInstToHideOverhead;

  // In many cases the address computation is not merged into the instruction
  // addressing mode.
  return 1;
}

int ARMTTIImpl::getFPOpCost(Type *Ty) {
  // Use similar logic that's in ARMISelLowering:
  // Any ARM CPU with VFP2 has floating point, but Thumb1 didn't have access
  // to VFP.

  if (ST->hasVFP2() && !ST->isThumb1Only()) {
    if (Ty->isFloatTy()) {
      return TargetTransformInfo::TCC_Basic;
    }

    if (Ty->isDoubleTy()) {
      return ST->isFPOnlySP() ? TargetTransformInfo::TCC_Expensive :
        TargetTransformInfo::TCC_Basic;
    }
  }

  return TargetTransformInfo::TCC_Expensive;
}

int ARMTTIImpl::getShuffleCost(TTI::ShuffleKind Kind, Type *Tp, int Index,
                               Type *SubTp) {
  // We only handle costs of reverse and alternate shuffles for now.
  if (Kind != TTI::SK_Reverse && Kind != TTI::SK_Alternate)
    return BaseT::getShuffleCost(Kind, Tp, Index, SubTp);

  if (Kind == TTI::SK_Reverse) {
    static const CostTblEntry NEONShuffleTbl[] = {
        // Reverse shuffle cost one instruction if we are shuffling within a
        // double word (vrev) or two if we shuffle a quad word (vrev, vext).
        {ISD::VECTOR_SHUFFLE, MVT::v2i32, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},

        {ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
        {ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
        {ISD::VECTOR_SHUFFLE, MVT::v8i16, 2},
        {ISD::VECTOR_SHUFFLE, MVT::v16i8, 2}};

    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);

    if (const auto *Entry = CostTableLookup(NEONShuffleTbl, ISD::VECTOR_SHUFFLE,
                                            LT.second))
      return LT.first * Entry->Cost;

    return BaseT::getShuffleCost(Kind, Tp, Index, SubTp);
  }
  if (Kind == TTI::SK_Alternate) {
    static const CostTblEntry NEONAltShuffleTbl[] = {
        // Alt shuffle cost table for ARM. Cost is the number of instructions
        // required to create the shuffled vector.

        {ISD::VECTOR_SHUFFLE, MVT::v2f32, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2i64, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2f64, 1},
        {ISD::VECTOR_SHUFFLE, MVT::v2i32, 1},

        {ISD::VECTOR_SHUFFLE, MVT::v4i32, 2},
        {ISD::VECTOR_SHUFFLE, MVT::v4f32, 2},
        {ISD::VECTOR_SHUFFLE, MVT::v4i16, 2},

        {ISD::VECTOR_SHUFFLE, MVT::v8i16, 16},

        {ISD::VECTOR_SHUFFLE, MVT::v16i8, 32}};

    std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Tp);
    if (const auto *Entry = CostTableLookup(NEONAltShuffleTbl,
                                            ISD::VECTOR_SHUFFLE, LT.second))
      return LT.first * Entry->Cost;
    return BaseT::getShuffleCost(Kind, Tp, Index, SubTp);
  }
  return BaseT::getShuffleCost(Kind, Tp, Index, SubTp);
}

int ARMTTIImpl::getArithmeticInstrCost(
    unsigned Opcode, Type *Ty, TTI::OperandValueKind Op1Info,
    TTI::OperandValueKind Op2Info, TTI::OperandValueProperties Opd1PropInfo,
    TTI::OperandValueProperties Opd2PropInfo,
    ArrayRef<const Value *> Args) {
  int ISDOpcode = TLI->InstructionOpcodeToISD(Opcode);
  std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Ty);

  const unsigned FunctionCallDivCost = 20;
  const unsigned ReciprocalDivCost = 10;
  static const CostTblEntry CostTbl[] = {
    // Division.
    // These costs are somewhat random. Choose a cost of 20 to indicate that
    // vectorizing devision (added function call) is going to be very expensive.
    // Double registers types.
    { ISD::SDIV, MVT::v1i64, 1 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v1i64, 1 * FunctionCallDivCost},
    { ISD::SREM, MVT::v1i64, 1 * FunctionCallDivCost},
    { ISD::UREM, MVT::v1i64, 1 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v2i32, 2 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v2i32, 2 * FunctionCallDivCost},
    { ISD::SREM, MVT::v2i32, 2 * FunctionCallDivCost},
    { ISD::UREM, MVT::v2i32, 2 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v4i16,     ReciprocalDivCost},
    { ISD::UDIV, MVT::v4i16,     ReciprocalDivCost},
    { ISD::SREM, MVT::v4i16, 4 * FunctionCallDivCost},
    { ISD::UREM, MVT::v4i16, 4 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v8i8,      ReciprocalDivCost},
    { ISD::UDIV, MVT::v8i8,      ReciprocalDivCost},
    { ISD::SREM, MVT::v8i8,  8 * FunctionCallDivCost},
    { ISD::UREM, MVT::v8i8,  8 * FunctionCallDivCost},
    // Quad register types.
    { ISD::SDIV, MVT::v2i64, 2 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v2i64, 2 * FunctionCallDivCost},
    { ISD::SREM, MVT::v2i64, 2 * FunctionCallDivCost},
    { ISD::UREM, MVT::v2i64, 2 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v4i32, 4 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v4i32, 4 * FunctionCallDivCost},
    { ISD::SREM, MVT::v4i32, 4 * FunctionCallDivCost},
    { ISD::UREM, MVT::v4i32, 4 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v8i16, 8 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v8i16, 8 * FunctionCallDivCost},
    { ISD::SREM, MVT::v8i16, 8 * FunctionCallDivCost},
    { ISD::UREM, MVT::v8i16, 8 * FunctionCallDivCost},
    { ISD::SDIV, MVT::v16i8, 16 * FunctionCallDivCost},
    { ISD::UDIV, MVT::v16i8, 16 * FunctionCallDivCost},
    { ISD::SREM, MVT::v16i8, 16 * FunctionCallDivCost},
    { ISD::UREM, MVT::v16i8, 16 * FunctionCallDivCost},
    // Multiplication.
  };

  if (ST->hasNEON())
    if (const auto *Entry = CostTableLookup(CostTbl, ISDOpcode, LT.second))
      return LT.first * Entry->Cost;

  int Cost = BaseT::getArithmeticInstrCost(Opcode, Ty, Op1Info, Op2Info,
                                           Opd1PropInfo, Opd2PropInfo);

  // This is somewhat of a hack. The problem that we are facing is that SROA
  // creates a sequence of shift, and, or instructions to construct values.
  // These sequences are recognized by the ISel and have zero-cost. Not so for
  // the vectorized code. Because we have support for v2i64 but not i64 those
  // sequences look particularly beneficial to vectorize.
  // To work around this we increase the cost of v2i64 operations to make them
  // seem less beneficial.
  if (LT.second == MVT::v2i64 &&
      Op2Info == TargetTransformInfo::OK_UniformConstantValue)
    Cost += 4;

  return Cost;
}

int ARMTTIImpl::getMemoryOpCost(unsigned Opcode, Type *Src, unsigned Alignment,
                                unsigned AddressSpace, const Instruction *I) {
  std::pair<int, MVT> LT = TLI->getTypeLegalizationCost(DL, Src);

  if (Src->isVectorTy() && Alignment != 16 &&
      Src->getVectorElementType()->isDoubleTy()) {
    // Unaligned loads/stores are extremely inefficient.
    // We need 4 uops for vst.1/vld.1 vs 1uop for vldr/vstr.
    return LT.first * 4;
  }
  return LT.first;
}

int ARMTTIImpl::getInterleavedMemoryOpCost(unsigned Opcode, Type *VecTy,
                                           unsigned Factor,
                                           ArrayRef<unsigned> Indices,
                                           unsigned Alignment,
                                           unsigned AddressSpace) {
  assert(Factor >= 2 && "Invalid interleave factor");
  assert(isa<VectorType>(VecTy) && "Expect a vector type");

  // vldN/vstN doesn't support vector types of i64/f64 element.
  bool EltIs64Bits = DL.getTypeSizeInBits(VecTy->getScalarType()) == 64;

  if (Factor <= TLI->getMaxSupportedInterleaveFactor() && !EltIs64Bits) {
    unsigned NumElts = VecTy->getVectorNumElements();
    auto *SubVecTy = VectorType::get(VecTy->getScalarType(), NumElts / Factor);

    // vldN/vstN only support legal vector types of size 64 or 128 in bits.
    // Accesses having vector types that are a multiple of 128 bits can be
    // matched to more than one vldN/vstN instruction.
    if (NumElts % Factor == 0 &&
        TLI->isLegalInterleavedAccessType(SubVecTy, DL))
      return Factor * TLI->getNumInterleavedAccesses(SubVecTy, DL);
  }

  return BaseT::getInterleavedMemoryOpCost(Opcode, VecTy, Factor, Indices,
                                           Alignment, AddressSpace);
}

void ARMTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
                                         TTI::UnrollingPreferences &UP) {
  // Only currently enable these preferences for M-Class cores.
  if (!ST->isMClass())
    return BasicTTIImplBase::getUnrollingPreferences(L, SE, UP);

  // Disable loop unrolling for Oz and Os.
  UP.OptSizeThreshold = 0;
  UP.PartialOptSizeThreshold = 0;
  if (L->getHeader()->getParent()->optForSize())
    return;

  // Only enable on Thumb-2 targets.
  if (!ST->isThumb2())
    return;

  SmallVector<BasicBlock*, 4> ExitingBlocks;
  L->getExitingBlocks(ExitingBlocks);
  DEBUG(dbgs() << "Loop has:\n"
      << "Blocks: " << L->getNumBlocks() << "\n"
      << "Exit blocks: " << ExitingBlocks.size() << "\n");

  // Only allow another exit other than the latch. This acts as an early exit
  // as it mirrors the profitability calculation of the runtime unroller.
  if (ExitingBlocks.size() > 2)
    return;

  // Limit the CFG of the loop body for targets with a branch predictor.
  // Allowing 4 blocks permits if-then-else diamonds in the body.
  if (ST->hasBranchPredictor() && L->getNumBlocks() > 4)
    return;

  // Scan the loop: don't unroll loops with calls as this could prevent
  // inlining.
  unsigned Cost = 0;
  for (auto *BB : L->getBlocks()) {
    for (auto &I : *BB) {
      if (isa<CallInst>(I) || isa<InvokeInst>(I)) {
        ImmutableCallSite CS(&I);
        if (const Function *F = CS.getCalledFunction()) {
          if (!isLoweredToCall(F))
            continue;
        }
        return;
      }
      SmallVector<const Value*, 4> Operands(I.value_op_begin(),
                                            I.value_op_end());
      Cost += getUserCost(&I, Operands);
    }
  }

  DEBUG(dbgs() << "Cost of loop: " << Cost << "\n");

  UP.Partial = true;
  UP.Runtime = true;
  UP.UnrollRemainder = true;
  UP.DefaultUnrollRuntimeCount = 4;

  // Force unrolling small loops can be very useful because of the branch
  // taken cost of the backedge.
  if (Cost < 12)
    UP.Force = true;
}