Target/AMDGPU/AMDGPULegalizerInfo.cpp

//===- AMDGPULegalizerInfo.cpp -----------------------------------*- C++ -*-==//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// This file implements the targeting of the Machinelegalizer class for
/// AMDGPU.
/// \todo This should be generated by TableGen.
//===----------------------------------------------------------------------===//

#if defined(_MSC_VER) || defined(__MINGW32__)
// According to Microsoft, one must set _USE_MATH_DEFINES in order to get M_PI
// from the Visual C++ cmath / math.h headers:
// https://docs.microsoft.com/en-us/cpp/c-runtime-library/math-constants?view=vs-2019
#define _USE_MATH_DEFINES
#endif

#include "AMDGPU.h"
#include "AMDGPULegalizerInfo.h"
#include "AMDGPUTargetMachine.h"
#include "SIMachineFunctionInfo.h"
#include "llvm/CodeGen/GlobalISel/LegalizerHelper.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/Debug.h"

#define DEBUG_TYPE "amdgpu-legalinfo"

using namespace llvm;
using namespace LegalizeActions;
using namespace LegalizeMutations;
using namespace LegalityPredicates;


static LegalityPredicate isMultiple32(unsigned TypeIdx,
                                      unsigned MaxSize = 1024) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    const LLT EltTy = Ty.getScalarType();
    return Ty.getSizeInBits() <= MaxSize && EltTy.getSizeInBits() % 32 == 0;
  };
}

static LegalityPredicate sizeIs(unsigned TypeIdx, unsigned Size) {
  return [=](const LegalityQuery &Query) {
    return Query.Types[TypeIdx].getSizeInBits() == Size;
  };
}

static LegalityPredicate isSmallOddVector(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    return Ty.isVector() &&
           Ty.getNumElements() % 2 != 0 &&
           Ty.getElementType().getSizeInBits() < 32 &&
           Ty.getSizeInBits() % 32 != 0;
  };
}

static LegalizeMutation oneMoreElement(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    const LLT EltTy = Ty.getElementType();
    return std::make_pair(TypeIdx, LLT::vector(Ty.getNumElements() + 1, EltTy));
  };
}

static LegalizeMutation fewerEltsToSize64Vector(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    const LLT EltTy = Ty.getElementType();
    unsigned Size = Ty.getSizeInBits();
    unsigned Pieces = (Size + 63) / 64;
    unsigned NewNumElts = (Ty.getNumElements() + 1) / Pieces;
    return std::make_pair(TypeIdx, LLT::scalarOrVector(NewNumElts, EltTy));
  };
}

// Increase the number of vector elements to reach the next multiple of 32-bit
// type.
static LegalizeMutation moreEltsToNext32Bit(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];

    const LLT EltTy = Ty.getElementType();
    const int Size = Ty.getSizeInBits();
    const int EltSize = EltTy.getSizeInBits();
    const int NextMul32 = (Size + 31) / 32;

    assert(EltSize < 32);

    const int NewNumElts = (32 * NextMul32 + EltSize - 1) / EltSize;
    return std::make_pair(TypeIdx, LLT::vector(NewNumElts, EltTy));
  };
}

static LegalityPredicate vectorSmallerThan(unsigned TypeIdx, unsigned Size) {
  return [=](const LegalityQuery &Query) {
    const LLT QueryTy = Query.Types[TypeIdx];
    return QueryTy.isVector() && QueryTy.getSizeInBits() < Size;
  };
}

static LegalityPredicate vectorWiderThan(unsigned TypeIdx, unsigned Size) {
  return [=](const LegalityQuery &Query) {
    const LLT QueryTy = Query.Types[TypeIdx];
    return QueryTy.isVector() && QueryTy.getSizeInBits() > Size;
  };
}

static LegalityPredicate numElementsNotEven(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT QueryTy = Query.Types[TypeIdx];
    return QueryTy.isVector() && QueryTy.getNumElements() % 2 != 0;
  };
}

// Any combination of 32 or 64-bit elements up to 1024 bits, and multiples of
// v2s16.
static LegalityPredicate isRegisterType(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    if (Ty.isVector()) {
      const int EltSize = Ty.getElementType().getSizeInBits();
      return EltSize == 32 || EltSize == 64 ||
            (EltSize == 16 && Ty.getNumElements() % 2 == 0) ||
             EltSize == 128 || EltSize == 256;
    }

    return Ty.getSizeInBits() % 32 == 0 && Ty.getSizeInBits() <= 1024;
  };
}

static LegalityPredicate elementTypeIs(unsigned TypeIdx, LLT Type) {
  return [=](const LegalityQuery &Query) {
    return Query.Types[TypeIdx].getElementType() == Type;
  };
}

static LegalityPredicate isWideScalarTruncStore(unsigned TypeIdx) {
  return [=](const LegalityQuery &Query) {
    const LLT Ty = Query.Types[TypeIdx];
    return !Ty.isVector() && Ty.getSizeInBits() > 32 &&
           Query.MMODescrs[0].SizeInBits < Ty.getSizeInBits();
  };
}

AMDGPULegalizerInfo::AMDGPULegalizerInfo(const GCNSubtarget &ST_,
                                         const GCNTargetMachine &TM)
  :  ST(ST_) {
  using namespace TargetOpcode;

  auto GetAddrSpacePtr = [&TM](unsigned AS) {
    return LLT::pointer(AS, TM.getPointerSizeInBits(AS));
  };

  const LLT S1 = LLT::scalar(1);
  const LLT S8 = LLT::scalar(8);
  const LLT S16 = LLT::scalar(16);
  const LLT S32 = LLT::scalar(32);
  const LLT S64 = LLT::scalar(64);
  const LLT S96 = LLT::scalar(96);
  const LLT S128 = LLT::scalar(128);
  const LLT S256 = LLT::scalar(256);
  const LLT S1024 = LLT::scalar(1024);

  const LLT V2S16 = LLT::vector(2, 16);
  const LLT V4S16 = LLT::vector(4, 16);

  const LLT V2S32 = LLT::vector(2, 32);
  const LLT V3S32 = LLT::vector(3, 32);
  const LLT V4S32 = LLT::vector(4, 32);
  const LLT V5S32 = LLT::vector(5, 32);
  const LLT V6S32 = LLT::vector(6, 32);
  const LLT V7S32 = LLT::vector(7, 32);
  const LLT V8S32 = LLT::vector(8, 32);
  const LLT V9S32 = LLT::vector(9, 32);
  const LLT V10S32 = LLT::vector(10, 32);
  const LLT V11S32 = LLT::vector(11, 32);
  const LLT V12S32 = LLT::vector(12, 32);
  const LLT V13S32 = LLT::vector(13, 32);
  const LLT V14S32 = LLT::vector(14, 32);
  const LLT V15S32 = LLT::vector(15, 32);
  const LLT V16S32 = LLT::vector(16, 32);
  const LLT V32S32 = LLT::vector(32, 32);

  const LLT V2S64 = LLT::vector(2, 64);
  const LLT V3S64 = LLT::vector(3, 64);
  const LLT V4S64 = LLT::vector(4, 64);
  const LLT V5S64 = LLT::vector(5, 64);
  const LLT V6S64 = LLT::vector(6, 64);
  const LLT V7S64 = LLT::vector(7, 64);
  const LLT V8S64 = LLT::vector(8, 64);
  const LLT V16S64 = LLT::vector(16, 64);

  std::initializer_list<LLT> AllS32Vectors =
    {V2S32, V3S32, V4S32, V5S32, V6S32, V7S32, V8S32,
     V9S32, V10S32, V11S32, V12S32, V13S32, V14S32, V15S32, V16S32, V32S32};
  std::initializer_list<LLT> AllS64Vectors =
    {V2S64, V3S64, V4S64, V5S64, V6S64, V7S64, V8S64, V16S64};

  const LLT GlobalPtr = GetAddrSpacePtr(AMDGPUAS::GLOBAL_ADDRESS);
  const LLT ConstantPtr = GetAddrSpacePtr(AMDGPUAS::CONSTANT_ADDRESS);
  const LLT Constant32Ptr = GetAddrSpacePtr(AMDGPUAS::CONSTANT_ADDRESS_32BIT);
  const LLT LocalPtr = GetAddrSpacePtr(AMDGPUAS::LOCAL_ADDRESS);
  const LLT RegionPtr = GetAddrSpacePtr(AMDGPUAS::REGION_ADDRESS);
  const LLT FlatPtr = GetAddrSpacePtr(AMDGPUAS::FLAT_ADDRESS);
  const LLT PrivatePtr = GetAddrSpacePtr(AMDGPUAS::PRIVATE_ADDRESS);

  const LLT CodePtr = FlatPtr;

  const std::initializer_list<LLT> AddrSpaces64 = {
    GlobalPtr, ConstantPtr, FlatPtr
  };

  const std::initializer_list<LLT> AddrSpaces32 = {
    LocalPtr, PrivatePtr, Constant32Ptr, RegionPtr
  };

  const std::initializer_list<LLT> FPTypesBase = {
    S32, S64
  };

  const std::initializer_list<LLT> FPTypes16 = {
    S32, S64, S16
  };

  const std::initializer_list<LLT> FPTypesPK16 = {
    S32, S64, S16, V2S16
  };

  setAction({G_BRCOND, S1}, Legal);

  // TODO: All multiples of 32, vectors of pointers, all v2s16 pairs, more
  // elements for v3s16
  getActionDefinitionsBuilder(G_PHI)
    .legalFor({S32, S64, V2S16, V4S16, S1, S128, S256})
    .legalFor(AllS32Vectors)
    .legalFor(AllS64Vectors)
    .legalFor(AddrSpaces64)
    .legalFor(AddrSpaces32)
    .clampScalar(0, S32, S256)
    .widenScalarToNextPow2(0, 32)
    .clampMaxNumElements(0, S32, 16)
    .moreElementsIf(isSmallOddVector(0), oneMoreElement(0))
    .legalIf(isPointer(0));

  if (ST.has16BitInsts()) {
    getActionDefinitionsBuilder({G_ADD, G_SUB, G_MUL})
      .legalFor({S32, S16})
      .clampScalar(0, S16, S32)
      .scalarize(0);
  } else {
    getActionDefinitionsBuilder({G_ADD, G_SUB, G_MUL})
      .legalFor({S32})
      .clampScalar(0, S32, S32)
      .scalarize(0);
  }

  getActionDefinitionsBuilder({G_UMULH, G_SMULH})
    .legalFor({S32})
    .clampScalar(0, S32, S32)
    .scalarize(0);

  // Report legal for any types we can handle anywhere. For the cases only legal
  // on the SALU, RegBankSelect will be able to re-legalize.
  getActionDefinitionsBuilder({G_AND, G_OR, G_XOR})
    .legalFor({S32, S1, S64, V2S32, S16, V2S16, V4S16})
    .clampScalar(0, S32, S64)
    .moreElementsIf(isSmallOddVector(0), oneMoreElement(0))
    .fewerElementsIf(vectorWiderThan(0, 64), fewerEltsToSize64Vector(0))
    .widenScalarToNextPow2(0)
    .scalarize(0);

  getActionDefinitionsBuilder({G_UADDO, G_SADDO, G_USUBO, G_SSUBO,
                               G_UADDE, G_SADDE, G_USUBE, G_SSUBE})
    .legalFor({{S32, S1}})
    .clampScalar(0, S32, S32)
    .scalarize(0); // TODO: Implement.

  getActionDefinitionsBuilder(G_BITCAST)
    // Don't worry about the size constraint.
    .legalIf(all(isRegisterType(0), isRegisterType(1)))
    // FIXME: Testing hack
    .legalForCartesianProduct({S16, LLT::vector(2, 8), });

  getActionDefinitionsBuilder(G_FCONSTANT)
    .legalFor({S32, S64, S16})
    .clampScalar(0, S16, S64);

  getActionDefinitionsBuilder(G_IMPLICIT_DEF)
    .legalFor({S1, S32, S64, S16, V2S32, V4S32, V2S16, V4S16, GlobalPtr,
               ConstantPtr, LocalPtr, FlatPtr, PrivatePtr})
    .moreElementsIf(isSmallOddVector(0), oneMoreElement(0))
    .clampScalarOrElt(0, S32, S1024)
    .legalIf(isMultiple32(0))
    .widenScalarToNextPow2(0, 32)
    .clampMaxNumElements(0, S32, 16);


  // FIXME: i1 operands to intrinsics should always be legal, but other i1
  // values may not be legal.  We need to figure out how to distinguish
  // between these two scenarios.
  getActionDefinitionsBuilder(G_CONSTANT)
    .legalFor({S1, S32, S64, S16, GlobalPtr,
               LocalPtr, ConstantPtr, PrivatePtr, FlatPtr })
    .clampScalar(0, S32, S64)
    .widenScalarToNextPow2(0)
    .legalIf(isPointer(0));

  setAction({G_FRAME_INDEX, PrivatePtr}, Legal);
  getActionDefinitionsBuilder(G_GLOBAL_VALUE)
    .customFor({LocalPtr, GlobalPtr, ConstantPtr, Constant32Ptr});


  auto &FPOpActions = getActionDefinitionsBuilder(
    { G_FADD, G_FMUL, G_FMA, G_FCANONICALIZE})
    .legalFor({S32, S64});
  auto &TrigActions = getActionDefinitionsBuilder({G_FSIN, G_FCOS})
    .customFor({S32, S64});

  if (ST.has16BitInsts()) {
    if (ST.hasVOP3PInsts())
      FPOpActions.legalFor({S16, V2S16});
    else
      FPOpActions.legalFor({S16});

    TrigActions.customFor({S16});
  }

  auto &MinNumMaxNum = getActionDefinitionsBuilder({
      G_FMINNUM, G_FMAXNUM, G_FMINNUM_IEEE, G_FMAXNUM_IEEE});

  if (ST.hasVOP3PInsts()) {
    MinNumMaxNum.customFor(FPTypesPK16)
      .clampMaxNumElements(0, S16, 2)
      .clampScalar(0, S16, S64)
      .scalarize(0);
  } else if (ST.has16BitInsts()) {
    MinNumMaxNum.customFor(FPTypes16)
      .clampScalar(0, S16, S64)
      .scalarize(0);
  } else {
    MinNumMaxNum.customFor(FPTypesBase)
      .clampScalar(0, S32, S64)
      .scalarize(0);
  }

  if (ST.hasVOP3PInsts())
    FPOpActions.clampMaxNumElements(0, S16, 2);

  FPOpActions
    .scalarize(0)
    .clampScalar(0, ST.has16BitInsts() ? S16 : S32, S64);

  TrigActions
    .scalarize(0)
    .clampScalar(0, ST.has16BitInsts() ? S16 : S32, S64);

  getActionDefinitionsBuilder({G_FNEG, G_FABS})
    .legalFor(FPTypesPK16)
    .clampMaxNumElements(0, S16, 2)
    .scalarize(0)
    .clampScalar(0, S16, S64);

  // TODO: Implement
  getActionDefinitionsBuilder({G_FMINIMUM, G_FMAXIMUM}).lower();

  if (ST.has16BitInsts()) {
    getActionDefinitionsBuilder({G_FSQRT, G_FFLOOR})
      .legalFor({S32, S64, S16})
      .scalarize(0)
      .clampScalar(0, S16, S64);
  } else {
    getActionDefinitionsBuilder({G_FSQRT, G_FFLOOR})
      .legalFor({S32, S64})
      .scalarize(0)
      .clampScalar(0, S32, S64);
  }

  getActionDefinitionsBuilder(G_FPTRUNC)
    .legalFor({{S32, S64}, {S16, S32}})
    .scalarize(0);

  getActionDefinitionsBuilder(G_FPEXT)
    .legalFor({{S64, S32}, {S32, S16}})
    .lowerFor({{S64, S16}}) // FIXME: Implement
    .scalarize(0);

  // TODO: Verify V_BFI_B32 is generated from expanded bit ops.
  getActionDefinitionsBuilder(G_FCOPYSIGN).lower();

  getActionDefinitionsBuilder(G_FSUB)
      // Use actual fsub instruction
      .legalFor({S32})
      // Must use fadd + fneg
      .lowerFor({S64, S16, V2S16})
      .scalarize(0)
      .clampScalar(0, S32, S64);

  // Whether this is legal depends on the floating point mode for the function.
  auto &FMad = getActionDefinitionsBuilder(G_FMAD);
  if (ST.hasMadF16())
    FMad.customFor({S32, S16});
  else
    FMad.customFor({S32});
  FMad.scalarize(0)
      .lower();

  getActionDefinitionsBuilder({G_SEXT, G_ZEXT, G_ANYEXT})
    .legalFor({{S64, S32}, {S32, S16}, {S64, S16},
               {S32, S1}, {S64, S1}, {S16, S1},
               {S96, S32},
               // FIXME: Hack
               {S64, LLT::scalar(33)},
               {S32, S8}, {S128, S32}, {S128, S64}, {S32, LLT::scalar(24)}})
    .scalarize(0);

  // TODO: Split s1->s64 during regbankselect for VALU.
  auto &IToFP = getActionDefinitionsBuilder({G_SITOFP, G_UITOFP})
    .legalFor({{S32, S32}, {S64, S32}, {S16, S32}, {S32, S1}, {S16, S1}, {S64, S1}})
    .lowerFor({{S32, S64}})
    .customFor({{S64, S64}});
  if (ST.has16BitInsts())
    IToFP.legalFor({{S16, S16}});
  IToFP.clampScalar(1, S32, S64)
       .scalarize(0);

  auto &FPToI = getActionDefinitionsBuilder({G_FPTOSI, G_FPTOUI})
    .legalFor({{S32, S32}, {S32, S64}, {S32, S16}});
  if (ST.has16BitInsts())
    FPToI.legalFor({{S16, S16}});
  else
    FPToI.minScalar(1, S32);

  FPToI.minScalar(0, S32)
       .scalarize(0);

  getActionDefinitionsBuilder(G_INTRINSIC_ROUND)
    .legalFor({S32, S64})
    .scalarize(0);

  if (ST.getGeneration() >= AMDGPUSubtarget::SEA_ISLANDS) {
    getActionDefinitionsBuilder({G_INTRINSIC_TRUNC, G_FCEIL, G_FRINT})
      .legalFor({S32, S64})
      .clampScalar(0, S32, S64)
      .scalarize(0);
  } else {
    getActionDefinitionsBuilder({G_INTRINSIC_TRUNC, G_FCEIL, G_FRINT})
      .legalFor({S32})
      .customFor({S64})
      .clampScalar(0, S32, S64)
      .scalarize(0);
  }

  getActionDefinitionsBuilder(G_GEP)
    .legalForCartesianProduct(AddrSpaces64, {S64})
    .legalForCartesianProduct(AddrSpaces32, {S32})
    .scalarize(0);

  getActionDefinitionsBuilder(G_PTR_MASK)
    .scalarize(0)
    .alwaysLegal();

  setAction({G_BLOCK_ADDR, CodePtr}, Legal);

  auto &CmpBuilder =
    getActionDefinitionsBuilder(G_ICMP)
    .legalForCartesianProduct(
      {S1}, {S32, S64, GlobalPtr, LocalPtr, ConstantPtr, PrivatePtr, FlatPtr})
    .legalFor({{S1, S32}, {S1, S64}});
  if (ST.has16BitInsts()) {
    CmpBuilder.legalFor({{S1, S16}});
  }

  CmpBuilder
    .widenScalarToNextPow2(1)
    .clampScalar(1, S32, S64)
    .scalarize(0)
    .legalIf(all(typeIs(0, S1), isPointer(1)));

  getActionDefinitionsBuilder(G_FCMP)
    .legalForCartesianProduct({S1}, ST.has16BitInsts() ? FPTypes16 : FPTypesBase)
    .widenScalarToNextPow2(1)
    .clampScalar(1, S32, S64)
    .scalarize(0);

  // FIXME: fexp, flog2, flog10 needs to be custom lowered.
  getActionDefinitionsBuilder({G_FPOW, G_FEXP, G_FEXP2,
                               G_FLOG, G_FLOG2, G_FLOG10})
    .legalFor({S32})
    .scalarize(0);

  // The 64-bit versions produce 32-bit results, but only on the SALU.
  getActionDefinitionsBuilder({G_CTLZ, G_CTLZ_ZERO_UNDEF,
                               G_CTTZ, G_CTTZ_ZERO_UNDEF,
                               G_CTPOP})
    .legalFor({{S32, S32}, {S32, S64}})
    .clampScalar(0, S32, S32)
    .clampScalar(1, S32, S64)
    .scalarize(0)
    .widenScalarToNextPow2(0, 32)
    .widenScalarToNextPow2(1, 32);

  // TODO: Expand for > s32
  getActionDefinitionsBuilder({G_BSWAP, G_BITREVERSE})
    .legalFor({S32})
    .clampScalar(0, S32, S32)
    .scalarize(0);

  if (ST.has16BitInsts()) {
    if (ST.hasVOP3PInsts()) {
      getActionDefinitionsBuilder({G_SMIN, G_SMAX, G_UMIN, G_UMAX})
        .legalFor({S32, S16, V2S16})
        .moreElementsIf(isSmallOddVector(0), oneMoreElement(0))
        .clampMaxNumElements(0, S16, 2)
        .clampScalar(0, S16, S32)
        .widenScalarToNextPow2(0)
        .scalarize(0);
    } else {
      getActionDefinitionsBuilder({G_SMIN, G_SMAX, G_UMIN, G_UMAX})
        .legalFor({S32, S16})
        .widenScalarToNextPow2(0)
        .clampScalar(0, S16, S32)
        .scalarize(0);
    }
  } else {
    getActionDefinitionsBuilder({G_SMIN, G_SMAX, G_UMIN, G_UMAX})
      .legalFor({S32})
      .clampScalar(0, S32, S32)
      .widenScalarToNextPow2(0)
      .scalarize(0);
  }

  auto smallerThan = [](unsigned TypeIdx0, unsigned TypeIdx1) {
    return [=](const LegalityQuery &Query) {
      return Query.Types[TypeIdx0].getSizeInBits() <
             Query.Types[TypeIdx1].getSizeInBits();
    };
  };

  auto greaterThan = [](unsigned TypeIdx0, unsigned TypeIdx1) {
    return [=](const LegalityQuery &Query) {
      return Query.Types[TypeIdx0].getSizeInBits() >
             Query.Types[TypeIdx1].getSizeInBits();
    };
  };

  getActionDefinitionsBuilder(G_INTTOPTR)
    // List the common cases
    .legalForCartesianProduct(AddrSpaces64, {S64})
    .legalForCartesianProduct(AddrSpaces32, {S32})
    .scalarize(0)
    // Accept any address space as long as the size matches
    .legalIf(sameSize(0, 1))
    .widenScalarIf(smallerThan(1, 0),
      [](const LegalityQuery &Query) {
        return std::make_pair(1, LLT::scalar(Query.Types[0].getSizeInBits()));
      })
    .narrowScalarIf(greaterThan(1, 0),
      [](const LegalityQuery &Query) {
        return std::make_pair(1, LLT::scalar(Query.Types[0].getSizeInBits()));
      });

  getActionDefinitionsBuilder(G_PTRTOINT)
    // List the common cases
    .legalForCartesianProduct(AddrSpaces64, {S64})
    .legalForCartesianProduct(AddrSpaces32, {S32})
    .scalarize(0)
    // Accept any address space as long as the size matches
    .legalIf(sameSize(0, 1))
    .widenScalarIf(smallerThan(0, 1),
      [](const LegalityQuery &Query) {
        return std::make_pair(0, LLT::scalar(Query.Types[1].getSizeInBits()));
      })
    .narrowScalarIf(
      greaterThan(0, 1),
      [](const LegalityQuery &Query) {
        return std::make_pair(0, LLT::scalar(Query.Types[1].getSizeInBits()));
      });

  getActionDefinitionsBuilder(G_ADDRSPACE_CAST)
    .scalarize(0)
    .custom();

  // TODO: Should load to s16 be legal? Most loads extend to 32-bits, but we
  // handle some operations by just promoting the register during
  // selection. There are also d16 loads on GFX9+ which preserve the high bits.
  auto maxSizeForAddrSpace = [this](unsigned AS) -> unsigned {
    switch (AS) {
    // FIXME: Private element size.
    case AMDGPUAS::PRIVATE_ADDRESS:
      return 32;
    // FIXME: Check subtarget
    case AMDGPUAS::LOCAL_ADDRESS:
      return ST.useDS128() ? 128 : 64;

    // Treat constant and global as identical. SMRD loads are sometimes usable
    // for global loads (ideally constant address space should be eliminated)
    // depending on the context. Legality cannot be context dependent, but
    // RegBankSelect can split the load as necessary depending on the pointer
    // register bank/uniformity and if the memory is invariant or not written in
    // a kernel.
    case AMDGPUAS::CONSTANT_ADDRESS:
    case AMDGPUAS::GLOBAL_ADDRESS:
      return 512;
    default:
      return 128;
    }
  };

  const auto needToSplitLoad = [=](const LegalityQuery &Query) -> bool {
    const LLT DstTy = Query.Types[0];

    // Split vector extloads.
    unsigned MemSize = Query.MMODescrs[0].SizeInBits;
    if (DstTy.isVector() && DstTy.getSizeInBits() > MemSize)
      return true;

    const LLT PtrTy = Query.Types[1];
    unsigned AS = PtrTy.getAddressSpace();
    if (MemSize > maxSizeForAddrSpace(AS))
      return true;

    // Catch weird sized loads that don't evenly divide into the access sizes
    // TODO: May be able to widen depending on alignment etc.
    unsigned NumRegs = MemSize / 32;
    if (NumRegs == 3 && !ST.hasDwordx3LoadStores())
      return true;

    unsigned Align = Query.MMODescrs[0].AlignInBits;
    if (Align < MemSize) {
      const SITargetLowering *TLI = ST.getTargetLowering();
      return !TLI->allowsMisalignedMemoryAccessesImpl(MemSize, AS, Align / 8);
    }

    return false;
  };

  unsigned GlobalAlign32 = ST.hasUnalignedBufferAccess() ? 0 : 32;
  unsigned GlobalAlign16 = ST.hasUnalignedBufferAccess() ? 0 : 16;
  unsigned GlobalAlign8 = ST.hasUnalignedBufferAccess() ? 0 : 8;

  // TODO: Refine based on subtargets which support unaligned access or 128-bit
  // LDS
  // TODO: Unsupported flat for SI.

  for (unsigned Op : {G_LOAD, G_STORE}) {
    const bool IsStore = Op == G_STORE;

    auto &Actions = getActionDefinitionsBuilder(Op);
    // Whitelist the common cases.
    // TODO: Pointer loads
    // TODO: Wide constant loads
    // TODO: Only CI+ has 3x loads
    // TODO: Loads to s16 on gfx9
    Actions.legalForTypesWithMemDesc({{S32, GlobalPtr, 32, GlobalAlign32},
                                      {V2S32, GlobalPtr, 64, GlobalAlign32},
                                      {V3S32, GlobalPtr, 96, GlobalAlign32},
                                      {S96, GlobalPtr, 96, GlobalAlign32},
                                      {V4S32, GlobalPtr, 128, GlobalAlign32},
                                      {S128, GlobalPtr, 128, GlobalAlign32},
                                      {S64, GlobalPtr, 64, GlobalAlign32},
                                      {V2S64, GlobalPtr, 128, GlobalAlign32},
                                      {V2S16, GlobalPtr, 32, GlobalAlign32},
                                      {S32, GlobalPtr, 8, GlobalAlign8},
                                      {S32, GlobalPtr, 16, GlobalAlign16},

                                      {S32, LocalPtr, 32, 32},
                                      {S64, LocalPtr, 64, 32},
                                      {V2S32, LocalPtr, 64, 32},
                                      {S32, LocalPtr, 8, 8},
                                      {S32, LocalPtr, 16, 16},
                                      {V2S16, LocalPtr, 32, 32},

                                      {S32, PrivatePtr, 32, 32},
                                      {S32, PrivatePtr, 8, 8},
                                      {S32, PrivatePtr, 16, 16},
                                      {V2S16, PrivatePtr, 32, 32},

                                      {S32, FlatPtr, 32, GlobalAlign32},
                                      {S32, FlatPtr, 16, GlobalAlign16},
                                      {S32, FlatPtr, 8, GlobalAlign8},
                                      {V2S16, FlatPtr, 32, GlobalAlign32},

                                      {S32, ConstantPtr, 32, GlobalAlign32},
                                      {V2S32, ConstantPtr, 64, GlobalAlign32},
                                      {V3S32, ConstantPtr, 96, GlobalAlign32},
                                      {V4S32, ConstantPtr, 128, GlobalAlign32},
                                      {S64, ConstantPtr, 64, GlobalAlign32},
                                      {S128, ConstantPtr, 128, GlobalAlign32},
                                      {V2S32, ConstantPtr, 32, GlobalAlign32}});
    Actions
        .customIf(typeIs(1, Constant32Ptr))
        .narrowScalarIf(
            [=](const LegalityQuery &Query) -> bool {
              return !Query.Types[0].isVector() && needToSplitLoad(Query);
            },
            [=](const LegalityQuery &Query) -> std::pair<unsigned, LLT> {
              const LLT DstTy = Query.Types[0];
              const LLT PtrTy = Query.Types[1];

              const unsigned DstSize = DstTy.getSizeInBits();
              unsigned MemSize = Query.MMODescrs[0].SizeInBits;

              // Split extloads.
              if (DstSize > MemSize)
                return std::make_pair(0, LLT::scalar(MemSize));

              if (DstSize > 32 && (DstSize % 32 != 0)) {
                // FIXME: Need a way to specify non-extload of larger size if
                // suitably aligned.
                return std::make_pair(0, LLT::scalar(32 * (DstSize / 32)));
              }

              unsigned MaxSize = maxSizeForAddrSpace(PtrTy.getAddressSpace());
              if (MemSize > MaxSize)
                return std::make_pair(0, LLT::scalar(MaxSize));

              unsigned Align = Query.MMODescrs[0].AlignInBits;
              return std::make_pair(0, LLT::scalar(Align));
            })
        .fewerElementsIf(
            [=](const LegalityQuery &Query) -> bool {
              return Query.Types[0].isVector() && needToSplitLoad(Query);
            },
            [=](const LegalityQuery &Query) -> std::pair<unsigned, LLT> {
              const LLT DstTy = Query.Types[0];
              const LLT PtrTy = Query.Types[1];

              LLT EltTy = DstTy.getElementType();
              unsigned MaxSize = maxSizeForAddrSpace(PtrTy.getAddressSpace());

              // Split if it's too large for the address space.
              if (Query.MMODescrs[0].SizeInBits > MaxSize) {
                unsigned NumElts = DstTy.getNumElements();
                unsigned NumPieces = Query.MMODescrs[0].SizeInBits / MaxSize;

                // FIXME: Refine when odd breakdowns handled
                // The scalars will need to be re-legalized.
                if (NumPieces == 1 || NumPieces >= NumElts ||
                    NumElts % NumPieces != 0)
                  return std::make_pair(0, EltTy);

                return std::make_pair(0,
                                      LLT::vector(NumElts / NumPieces, EltTy));
              }

              // Need to split because of alignment.
              unsigned Align = Query.MMODescrs[0].AlignInBits;
              unsigned EltSize = EltTy.getSizeInBits();
              if (EltSize > Align &&
                  (EltSize / Align < DstTy.getNumElements())) {
                return std::make_pair(0, LLT::vector(EltSize / Align, EltTy));
              }

              // May need relegalization for the scalars.
              return std::make_pair(0, EltTy);
            })
        .minScalar(0, S32);

    if (IsStore)
      Actions.narrowScalarIf(isWideScalarTruncStore(0), changeTo(0, S32));

    // TODO: Need a bitcast lower option?
    Actions
        .legalIf([=](const LegalityQuery &Query) {
          const LLT Ty0 = Query.Types[0];
          unsigned Size = Ty0.getSizeInBits();
          unsigned MemSize = Query.MMODescrs[0].SizeInBits;
          unsigned Align = Query.MMODescrs[0].AlignInBits;

          // No extending vector loads.
          if (Size > MemSize && Ty0.isVector())
            return false;

          // FIXME: Widening store from alignment not valid.
          if (MemSize < Size)
            MemSize = std::max(MemSize, Align);

          switch (MemSize) {
          case 8:
          case 16:
            return Size == 32;
          case 32:
          case 64:
          case 128:
            return true;
          case 96:
            return ST.hasDwordx3LoadStores();
          case 256:
          case 512:
            return true;
          default:
            return false;
          }
        })
        .widenScalarToNextPow2(0)
        // TODO: v3s32->v4s32 with alignment
        .moreElementsIf(vectorSmallerThan(0, 32), moreEltsToNext32Bit(0));
  }

  auto &ExtLoads = getActionDefinitionsBuilder({G_SEXTLOAD, G_ZEXTLOAD})
                       .legalForTypesWithMemDesc({{S32, GlobalPtr, 8, 8},
                                                  {S32, GlobalPtr, 16, 2 * 8},
                                                  {S32, LocalPtr, 8, 8},
                                                  {S32, LocalPtr, 16, 16},
                                                  {S32, PrivatePtr, 8, 8},
                                                  {S32, PrivatePtr, 16, 16},
                                                  {S32, ConstantPtr, 8, 8},
                                                  {S32, ConstantPtr, 16, 2 * 8}});
  if (ST.hasFlatAddressSpace()) {
    ExtLoads.legalForTypesWithMemDesc(
        {{S32, FlatPtr, 8, 8}, {S32, FlatPtr, 16, 16}});
  }

  ExtLoads.clampScalar(0, S32, S32)
          .widenScalarToNextPow2(0)
          .unsupportedIfMemSizeNotPow2()
          .lower();

  auto &Atomics = getActionDefinitionsBuilder(
    {G_ATOMICRMW_XCHG, G_ATOMICRMW_ADD, G_ATOMICRMW_SUB,
     G_ATOMICRMW_AND, G_ATOMICRMW_OR, G_ATOMICRMW_XOR,
     G_ATOMICRMW_MAX, G_ATOMICRMW_MIN, G_ATOMICRMW_UMAX,
     G_ATOMICRMW_UMIN, G_ATOMIC_CMPXCHG})
    .legalFor({{S32, GlobalPtr}, {S32, LocalPtr},
               {S64, GlobalPtr}, {S64, LocalPtr}});
  if (ST.hasFlatAddressSpace()) {
    Atomics.legalFor({{S32, FlatPtr}, {S64, FlatPtr}});
  }

  getActionDefinitionsBuilder(G_ATOMICRMW_FADD)
    .legalFor({{S32, LocalPtr}});

  getActionDefinitionsBuilder(G_ATOMIC_CMPXCHG_WITH_SUCCESS)
    .lower();

  // TODO: Pointer types, any 32-bit or 64-bit vector
  getActionDefinitionsBuilder(G_SELECT)
    .legalForCartesianProduct({S32, S64, S16, V2S32, V2S16, V4S16,
          GlobalPtr, LocalPtr, FlatPtr, PrivatePtr,
          LLT::vector(2, LocalPtr), LLT::vector(2, PrivatePtr)}, {S1})
    .clampScalar(0, S16, S64)
    .moreElementsIf(isSmallOddVector(0), oneMoreElement(0))
    .fewerElementsIf(numElementsNotEven(0), scalarize(0))
    .scalarize(1)
    .clampMaxNumElements(0, S32, 2)
    .clampMaxNumElements(0, LocalPtr, 2)
    .clampMaxNumElements(0, PrivatePtr, 2)
    .scalarize(0)
    .widenScalarToNextPow2(0)
    .legalIf(all(isPointer(0), typeIs(1, S1)));

  // TODO: Only the low 4/5/6 bits of the shift amount are observed, so we can
  // be more flexible with the shift amount type.
  auto &Shifts = getActionDefinitionsBuilder({G_SHL, G_LSHR, G_ASHR})
    .legalFor({{S32, S32}, {S64, S32}});
  if (ST.has16BitInsts()) {
    if (ST.hasVOP3PInsts()) {
      Shifts.legalFor({{S16, S32}, {S16, S16}, {V2S16, V2S16}})
            .clampMaxNumElements(0, S16, 2);
    } else
      Shifts.legalFor({{S16, S32}, {S16, S16}});

    Shifts.clampScalar(1, S16, S32);
    Shifts.clampScalar(0, S16, S64);
    Shifts.widenScalarToNextPow2(0, 16);
  } else {
    // Make sure we legalize the shift amount type first, as the general
    // expansion for the shifted type will produce much worse code if it hasn't
    // been truncated already.
    Shifts.clampScalar(1, S32, S32);
    Shifts.clampScalar(0, S32, S64);
    Shifts.widenScalarToNextPow2(0, 32);
  }
  Shifts.scalarize(0);

  for (unsigned Op : {G_EXTRACT_VECTOR_ELT, G_INSERT_VECTOR_ELT}) {
    unsigned VecTypeIdx = Op == G_EXTRACT_VECTOR_ELT ? 1 : 0;
    unsigned EltTypeIdx = Op == G_EXTRACT_VECTOR_ELT ? 0 : 1;
    unsigned IdxTypeIdx = 2;

    getActionDefinitionsBuilder(Op)
      .customIf([=](const LegalityQuery &Query) {
          const LLT EltTy = Query.Types[EltTypeIdx];
          const LLT VecTy = Query.Types[VecTypeIdx];
          const LLT IdxTy = Query.Types[IdxTypeIdx];
          return (EltTy.getSizeInBits() == 16 ||
                  EltTy.getSizeInBits() % 32 == 0) &&
                 VecTy.getSizeInBits() % 32 == 0 &&
                 VecTy.getSizeInBits() <= 1024 &&
                 IdxTy.getSizeInBits() == 32;
        })
      .clampScalar(EltTypeIdx, S32, S64)
      .clampScalar(VecTypeIdx, S32, S64)
      .clampScalar(IdxTypeIdx, S32, S32);
  }

  getActionDefinitionsBuilder(G_EXTRACT_VECTOR_ELT)
    .unsupportedIf([=](const LegalityQuery &Query) {
        const LLT &EltTy = Query.Types[1].getElementType();
        return Query.Types[0] != EltTy;
      });

  for (unsigned Op : {G_EXTRACT, G_INSERT}) {
    unsigned BigTyIdx = Op == G_EXTRACT ? 1 : 0;
    unsigned LitTyIdx = Op == G_EXTRACT ? 0 : 1;

    // FIXME: Doesn't handle extract of illegal sizes.
    getActionDefinitionsBuilder(Op)
      .lowerIf(all(typeIs(LitTyIdx, S16), sizeIs(BigTyIdx, 32)))
      // FIXME: Multiples of 16 should not be legal.
      .legalIf([=](const LegalityQuery &Query) {
          const LLT BigTy = Query.Types[BigTyIdx];
          const LLT LitTy = Query.Types[LitTyIdx];
          return (BigTy.getSizeInBits() % 32 == 0) &&
                 (LitTy.getSizeInBits() % 16 == 0);
        })
      .widenScalarIf(
        [=](const LegalityQuery &Query) {
          const LLT BigTy = Query.Types[BigTyIdx];
          return (BigTy.getScalarSizeInBits() < 16);
        },
        LegalizeMutations::widenScalarOrEltToNextPow2(BigTyIdx, 16))
      .widenScalarIf(
        [=](const LegalityQuery &Query) {
          const LLT LitTy = Query.Types[LitTyIdx];
          return (LitTy.getScalarSizeInBits() < 16);
        },
        LegalizeMutations::widenScalarOrEltToNextPow2(LitTyIdx, 16))
      .moreElementsIf(isSmallOddVector(BigTyIdx), oneMoreElement(BigTyIdx))
      .widenScalarToNextPow2(BigTyIdx, 32);

  }

  auto &BuildVector = getActionDefinitionsBuilder(G_BUILD_VECTOR)
    .legalForCartesianProduct(AllS32Vectors, {S32})
    .legalForCartesianProduct(AllS64Vectors, {S64})
    .clampNumElements(0, V16S32, V32S32)
    .clampNumElements(0, V2S64, V16S64);

  if (ST.hasScalarPackInsts())
    BuildVector.legalFor({V2S16, S32});

  BuildVector
    .minScalarSameAs(1, 0)
    .legalIf(isRegisterType(0))
    .minScalarOrElt(0, S32);

  if (ST.hasScalarPackInsts()) {
    getActionDefinitionsBuilder(G_BUILD_VECTOR_TRUNC)
      .legalFor({V2S16, S32})
      .lower();
  } else {
    getActionDefinitionsBuilder(G_BUILD_VECTOR_TRUNC)
      .lower();
  }

  getActionDefinitionsBuilder(G_CONCAT_VECTORS)
    .legalIf(isRegisterType(0));

  // TODO: Don't fully scalarize v2s16 pieces
  getActionDefinitionsBuilder(G_SHUFFLE_VECTOR).lower();

  // Merge/Unmerge
  for (unsigned Op : {G_MERGE_VALUES, G_UNMERGE_VALUES}) {
    unsigned BigTyIdx = Op == G_MERGE_VALUES ? 0 : 1;
    unsigned LitTyIdx = Op == G_MERGE_VALUES ? 1 : 0;

    auto notValidElt = [=](const LegalityQuery &Query, unsigned TypeIdx) {
      const LLT &Ty = Query.Types[TypeIdx];
      if (Ty.isVector()) {
        const LLT &EltTy = Ty.getElementType();
        if (EltTy.getSizeInBits() < 8 || EltTy.getSizeInBits() > 64)
          return true;
        if (!isPowerOf2_32(EltTy.getSizeInBits()))
          return true;
      }
      return false;
    };

    auto &Builder = getActionDefinitionsBuilder(Op)
      .widenScalarToNextPow2(LitTyIdx, /*Min*/ 16)
      // Clamp the little scalar to s8-s256 and make it a power of 2. It's not
      // worth considering the multiples of 64 since 2*192 and 2*384 are not
      // valid.
      .clampScalar(LitTyIdx, S16, S256)
      .widenScalarToNextPow2(LitTyIdx, /*Min*/ 32)
      .moreElementsIf(isSmallOddVector(BigTyIdx), oneMoreElement(BigTyIdx))
      .fewerElementsIf(all(typeIs(0, S16), vectorWiderThan(1, 32),
                           elementTypeIs(1, S16)),
                       changeTo(1, V2S16))
      // Break up vectors with weird elements into scalars
      .fewerElementsIf(
        [=](const LegalityQuery &Query) { return notValidElt(Query, 0); },
        scalarize(0))
      .fewerElementsIf(
        [=](const LegalityQuery &Query) { return notValidElt(Query, 1); },
        scalarize(1))
      .clampScalar(BigTyIdx, S32, S1024)
      .lowerFor({{S16, V2S16}});

    if (Op == G_MERGE_VALUES) {
      Builder.widenScalarIf(
        // TODO: Use 16-bit shifts if legal for 8-bit values?
        [=](const LegalityQuery &Query) {
          const LLT Ty = Query.Types[LitTyIdx];
          return Ty.getSizeInBits() < 32;
        },
        changeTo(LitTyIdx, S32));
    }

    Builder.widenScalarIf(
      [=](const LegalityQuery &Query) {
        const LLT Ty = Query.Types[BigTyIdx];
        return !isPowerOf2_32(Ty.getSizeInBits()) &&
          Ty.getSizeInBits() % 16 != 0;
      },
      [=](const LegalityQuery &Query) {
        // Pick the next power of 2, or a multiple of 64 over 128.
        // Whichever is smaller.
        const LLT &Ty = Query.Types[BigTyIdx];
        unsigned NewSizeInBits = 1 << Log2_32_Ceil(Ty.getSizeInBits() + 1);
        if (NewSizeInBits >= 256) {
          unsigned RoundedTo = alignTo<64>(Ty.getSizeInBits() + 1);
          if (RoundedTo < NewSizeInBits)
            NewSizeInBits = RoundedTo;
        }
        return std::make_pair(BigTyIdx, LLT::scalar(NewSizeInBits));
      })
      .legalIf([=](const LegalityQuery &Query) {
          const LLT &BigTy = Query.Types[BigTyIdx];
          const LLT &LitTy = Query.Types[LitTyIdx];

          if (BigTy.isVector() && BigTy.getSizeInBits() < 32)
            return false;
          if (LitTy.isVector() && LitTy.getSizeInBits() < 32)
            return false;

          return BigTy.getSizeInBits() % 16 == 0 &&
                 LitTy.getSizeInBits() % 16 == 0 &&
                 BigTy.getSizeInBits() <= 1024;
        })
      // Any vectors left are the wrong size. Scalarize them.
      .scalarize(0)
      .scalarize(1);
  }

  getActionDefinitionsBuilder(G_SEXT_INREG).lower();

  computeTables();
  verify(*ST.getInstrInfo());
}

bool AMDGPULegalizerInfo::legalizeCustom(MachineInstr &MI,
                                         MachineRegisterInfo &MRI,
                                         MachineIRBuilder &B,
                                         GISelChangeObserver &Observer) const {
  switch (MI.getOpcode()) {
  case TargetOpcode::G_ADDRSPACE_CAST:
    return legalizeAddrSpaceCast(MI, MRI, B);
  case TargetOpcode::G_FRINT:
    return legalizeFrint(MI, MRI, B);
  case TargetOpcode::G_FCEIL:
    return legalizeFceil(MI, MRI, B);
  case TargetOpcode::G_INTRINSIC_TRUNC:
    return legalizeIntrinsicTrunc(MI, MRI, B);
  case TargetOpcode::G_SITOFP:
    return legalizeITOFP(MI, MRI, B, true);
  case TargetOpcode::G_UITOFP:
    return legalizeITOFP(MI, MRI, B, false);
  case TargetOpcode::G_FMINNUM:
  case TargetOpcode::G_FMAXNUM:
  case TargetOpcode::G_FMINNUM_IEEE:
  case TargetOpcode::G_FMAXNUM_IEEE:
    return legalizeMinNumMaxNum(MI, MRI, B);
  case TargetOpcode::G_EXTRACT_VECTOR_ELT:
    return legalizeExtractVectorElt(MI, MRI, B);
  case TargetOpcode::G_INSERT_VECTOR_ELT:
    return legalizeInsertVectorElt(MI, MRI, B);
  case TargetOpcode::G_FSIN:
  case TargetOpcode::G_FCOS:
    return legalizeSinCos(MI, MRI, B);
  case TargetOpcode::G_GLOBAL_VALUE:
    return legalizeGlobalValue(MI, MRI, B);
  case TargetOpcode::G_LOAD:
    return legalizeLoad(MI, MRI, B, Observer);
  case TargetOpcode::G_FMAD:
    return legalizeFMad(MI, MRI, B);
  default:
    return false;
  }

  llvm_unreachable("expected switch to return");
}

Register AMDGPULegalizerInfo::getSegmentAperture(
  unsigned AS,
  MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  MachineFunction &MF = B.getMF();
  const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
  const LLT S32 = LLT::scalar(32);

  assert(AS == AMDGPUAS::LOCAL_ADDRESS || AS == AMDGPUAS::PRIVATE_ADDRESS);

  if (ST.hasApertureRegs()) {
    // FIXME: Use inline constants (src_{shared, private}_base) instead of
    // getreg.
    unsigned Offset = AS == AMDGPUAS::LOCAL_ADDRESS ?
        AMDGPU::Hwreg::OFFSET_SRC_SHARED_BASE :
        AMDGPU::Hwreg::OFFSET_SRC_PRIVATE_BASE;
    unsigned WidthM1 = AS == AMDGPUAS::LOCAL_ADDRESS ?
        AMDGPU::Hwreg::WIDTH_M1_SRC_SHARED_BASE :
        AMDGPU::Hwreg::WIDTH_M1_SRC_PRIVATE_BASE;
    unsigned Encoding =
        AMDGPU::Hwreg::ID_MEM_BASES << AMDGPU::Hwreg::ID_SHIFT_ |
        Offset << AMDGPU::Hwreg::OFFSET_SHIFT_ |
        WidthM1 << AMDGPU::Hwreg::WIDTH_M1_SHIFT_;

    Register ApertureReg = MRI.createGenericVirtualRegister(S32);
    Register GetReg = MRI.createVirtualRegister(&AMDGPU::SReg_32RegClass);

    B.buildInstr(AMDGPU::S_GETREG_B32)
      .addDef(GetReg)
      .addImm(Encoding);
    MRI.setType(GetReg, S32);

    auto ShiftAmt = B.buildConstant(S32, WidthM1 + 1);
    B.buildInstr(TargetOpcode::G_SHL)
      .addDef(ApertureReg)
      .addUse(GetReg)
      .addUse(ShiftAmt.getReg(0));

    return ApertureReg;
  }

  Register QueuePtr = MRI.createGenericVirtualRegister(
    LLT::pointer(AMDGPUAS::CONSTANT_ADDRESS, 64));

  const SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
  if (!loadInputValue(QueuePtr, B, &MFI->getArgInfo().QueuePtr))
    return Register();

  // Offset into amd_queue_t for group_segment_aperture_base_hi /
  // private_segment_aperture_base_hi.
  uint32_t StructOffset = (AS == AMDGPUAS::LOCAL_ADDRESS) ? 0x40 : 0x44;

  // FIXME: Don't use undef
  Value *V = UndefValue::get(PointerType::get(
                               Type::getInt8Ty(MF.getFunction().getContext()),
                               AMDGPUAS::CONSTANT_ADDRESS));

  MachinePointerInfo PtrInfo(V, StructOffset);
  MachineMemOperand *MMO = MF.getMachineMemOperand(
    PtrInfo,
    MachineMemOperand::MOLoad |
    MachineMemOperand::MODereferenceable |
    MachineMemOperand::MOInvariant,
    4,
    MinAlign(64, StructOffset));

  Register LoadResult = MRI.createGenericVirtualRegister(S32);
  Register LoadAddr;

  B.materializeGEP(LoadAddr, QueuePtr, LLT::scalar(64), StructOffset);
  B.buildLoad(LoadResult, LoadAddr, *MMO);
  return LoadResult;
}

bool AMDGPULegalizerInfo::legalizeAddrSpaceCast(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  MachineFunction &MF = B.getMF();

  B.setInstr(MI);

  const LLT S32 = LLT::scalar(32);
  Register Dst = MI.getOperand(0).getReg();
  Register Src = MI.getOperand(1).getReg();

  LLT DstTy = MRI.getType(Dst);
  LLT SrcTy = MRI.getType(Src);
  unsigned DestAS = DstTy.getAddressSpace();
  unsigned SrcAS = SrcTy.getAddressSpace();

  // TODO: Avoid reloading from the queue ptr for each cast, or at least each
  // vector element.
  assert(!DstTy.isVector());

  const AMDGPUTargetMachine &TM
    = static_cast<const AMDGPUTargetMachine &>(MF.getTarget());

  const GCNSubtarget &ST = MF.getSubtarget<GCNSubtarget>();
  if (ST.getTargetLowering()->isNoopAddrSpaceCast(SrcAS, DestAS)) {
    MI.setDesc(B.getTII().get(TargetOpcode::G_BITCAST));
    return true;
  }

  if (DestAS == AMDGPUAS::CONSTANT_ADDRESS_32BIT) {
    // Truncate.
    B.buildExtract(Dst, Src, 0);
    MI.eraseFromParent();
    return true;
  }

  if (SrcAS == AMDGPUAS::CONSTANT_ADDRESS_32BIT) {
    const SIMachineFunctionInfo *Info = MF.getInfo<SIMachineFunctionInfo>();
    uint32_t AddrHiVal = Info->get32BitAddressHighBits();

    // FIXME: This is a bit ugly due to creating a merge of 2 pointers to
    // another. Merge operands are required to be the same type, but creating an
    // extra ptrtoint would be kind of pointless.
    auto HighAddr = B.buildConstant(
      LLT::pointer(AMDGPUAS::CONSTANT_ADDRESS_32BIT, 32), AddrHiVal);
    B.buildMerge(Dst, {Src, HighAddr.getReg(0)});
    MI.eraseFromParent();
    return true;
  }

  if (SrcAS == AMDGPUAS::FLAT_ADDRESS) {
    assert(DestAS == AMDGPUAS::LOCAL_ADDRESS ||
           DestAS == AMDGPUAS::PRIVATE_ADDRESS);
    unsigned NullVal = TM.getNullPointerValue(DestAS);

    auto SegmentNull = B.buildConstant(DstTy, NullVal);
    auto FlatNull = B.buildConstant(SrcTy, 0);

    Register PtrLo32 = MRI.createGenericVirtualRegister(DstTy);

    // Extract low 32-bits of the pointer.
    B.buildExtract(PtrLo32, Src, 0);

    Register CmpRes = MRI.createGenericVirtualRegister(LLT::scalar(1));
    B.buildICmp(CmpInst::ICMP_NE, CmpRes, Src, FlatNull.getReg(0));
    B.buildSelect(Dst, CmpRes, PtrLo32, SegmentNull.getReg(0));

    MI.eraseFromParent();
    return true;
  }

  if (SrcAS != AMDGPUAS::LOCAL_ADDRESS && SrcAS != AMDGPUAS::PRIVATE_ADDRESS)
    return false;

  if (!ST.hasFlatAddressSpace())
    return false;

  auto SegmentNull =
      B.buildConstant(SrcTy, TM.getNullPointerValue(SrcAS));
  auto FlatNull =
      B.buildConstant(DstTy, TM.getNullPointerValue(DestAS));

  Register ApertureReg = getSegmentAperture(SrcAS, MRI, B);
  if (!ApertureReg.isValid())
    return false;

  Register CmpRes = MRI.createGenericVirtualRegister(LLT::scalar(1));
  B.buildICmp(CmpInst::ICMP_NE, CmpRes, Src, SegmentNull.getReg(0));

  Register BuildPtr = MRI.createGenericVirtualRegister(DstTy);

  // Coerce the type of the low half of the result so we can use merge_values.
  Register SrcAsInt = MRI.createGenericVirtualRegister(S32);
  B.buildInstr(TargetOpcode::G_PTRTOINT)
    .addDef(SrcAsInt)
    .addUse(Src);

  // TODO: Should we allow mismatched types but matching sizes in merges to
  // avoid the ptrtoint?
  B.buildMerge(BuildPtr, {SrcAsInt, ApertureReg});
  B.buildSelect(Dst, CmpRes, BuildPtr, FlatNull.getReg(0));

  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeFrint(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  B.setInstr(MI);

  Register Src = MI.getOperand(1).getReg();
  LLT Ty = MRI.getType(Src);
  assert(Ty.isScalar() && Ty.getSizeInBits() == 64);

  APFloat C1Val(APFloat::IEEEdouble(), "0x1.0p+52");
  APFloat C2Val(APFloat::IEEEdouble(), "0x1.fffffffffffffp+51");

  auto C1 = B.buildFConstant(Ty, C1Val);
  auto CopySign = B.buildFCopysign(Ty, C1, Src);

  // TODO: Should this propagate fast-math-flags?
  auto Tmp1 = B.buildFAdd(Ty, Src, CopySign);
  auto Tmp2 = B.buildFSub(Ty, Tmp1, CopySign);

  auto C2 = B.buildFConstant(Ty, C2Val);
  auto Fabs = B.buildFAbs(Ty, Src);

  auto Cond = B.buildFCmp(CmpInst::FCMP_OGT, LLT::scalar(1), Fabs, C2);
  B.buildSelect(MI.getOperand(0).getReg(), Cond, Src, Tmp2);
  return true;
}

bool AMDGPULegalizerInfo::legalizeFceil(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  B.setInstr(MI);

  const LLT S1 = LLT::scalar(1);
  const LLT S64 = LLT::scalar(64);

  Register Src = MI.getOperand(1).getReg();
  assert(MRI.getType(Src) == S64);

  // result = trunc(src)
  // if (src > 0.0 && src != result)
  //   result += 1.0

  auto Trunc = B.buildInstr(TargetOpcode::G_INTRINSIC_TRUNC, {S64}, {Src});

  const auto Zero = B.buildFConstant(S64, 0.0);
  const auto One = B.buildFConstant(S64, 1.0);
  auto Lt0 = B.buildFCmp(CmpInst::FCMP_OGT, S1, Src, Zero);
  auto NeTrunc = B.buildFCmp(CmpInst::FCMP_ONE, S1, Src, Trunc);
  auto And = B.buildAnd(S1, Lt0, NeTrunc);
  auto Add = B.buildSelect(S64, And, One, Zero);

  // TODO: Should this propagate fast-math-flags?
  B.buildFAdd(MI.getOperand(0).getReg(), Trunc, Add);
  return true;
}

static MachineInstrBuilder extractF64Exponent(unsigned Hi,
                                              MachineIRBuilder &B) {
  const unsigned FractBits = 52;
  const unsigned ExpBits = 11;
  LLT S32 = LLT::scalar(32);

  auto Const0 = B.buildConstant(S32, FractBits - 32);
  auto Const1 = B.buildConstant(S32, ExpBits);

  auto ExpPart = B.buildIntrinsic(Intrinsic::amdgcn_ubfe, {S32}, false)
    .addUse(Const0.getReg(0))
    .addUse(Const1.getReg(0));

  return B.buildSub(S32, ExpPart, B.buildConstant(S32, 1023));
}

bool AMDGPULegalizerInfo::legalizeIntrinsicTrunc(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  B.setInstr(MI);

  const LLT S1 = LLT::scalar(1);
  const LLT S32 = LLT::scalar(32);
  const LLT S64 = LLT::scalar(64);

  Register Src = MI.getOperand(1).getReg();
  assert(MRI.getType(Src) == S64);

  // TODO: Should this use extract since the low half is unused?
  auto Unmerge = B.buildUnmerge({S32, S32}, Src);
  Register Hi = Unmerge.getReg(1);

  // Extract the upper half, since this is where we will find the sign and
  // exponent.
  auto Exp = extractF64Exponent(Hi, B);

  const unsigned FractBits = 52;

  // Extract the sign bit.
  const auto SignBitMask = B.buildConstant(S32, UINT32_C(1) << 31);
  auto SignBit = B.buildAnd(S32, Hi, SignBitMask);

  const auto FractMask = B.buildConstant(S64, (UINT64_C(1) << FractBits) - 1);

  const auto Zero32 = B.buildConstant(S32, 0);

  // Extend back to 64-bits.
  auto SignBit64 = B.buildMerge(S64, {Zero32.getReg(0), SignBit.getReg(0)});

  auto Shr = B.buildAShr(S64, FractMask, Exp);
  auto Not = B.buildNot(S64, Shr);
  auto Tmp0 = B.buildAnd(S64, Src, Not);
  auto FiftyOne = B.buildConstant(S32, FractBits - 1);

  auto ExpLt0 = B.buildICmp(CmpInst::ICMP_SLT, S1, Exp, Zero32);
  auto ExpGt51 = B.buildICmp(CmpInst::ICMP_SGT, S1, Exp, FiftyOne);

  auto Tmp1 = B.buildSelect(S64, ExpLt0, SignBit64, Tmp0);
  B.buildSelect(MI.getOperand(0).getReg(), ExpGt51, Src, Tmp1);
  return true;
}

bool AMDGPULegalizerInfo::legalizeITOFP(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B, bool Signed) const {
  B.setInstr(MI);

  Register Dst = MI.getOperand(0).getReg();
  Register Src = MI.getOperand(1).getReg();

  const LLT S64 = LLT::scalar(64);
  const LLT S32 = LLT::scalar(32);

  assert(MRI.getType(Src) == S64 && MRI.getType(Dst) == S64);

  auto Unmerge = B.buildUnmerge({S32, S32}, Src);

  auto CvtHi = Signed ?
    B.buildSITOFP(S64, Unmerge.getReg(1)) :
    B.buildUITOFP(S64, Unmerge.getReg(1));

  auto CvtLo = B.buildUITOFP(S64, Unmerge.getReg(0));

  auto ThirtyTwo = B.buildConstant(S32, 32);
  auto LdExp = B.buildIntrinsic(Intrinsic::amdgcn_ldexp, {S64}, false)
    .addUse(CvtHi.getReg(0))
    .addUse(ThirtyTwo.getReg(0));

  // TODO: Should this propagate fast-math-flags?
  B.buildFAdd(Dst, LdExp, CvtLo);
  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeMinNumMaxNum(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  MachineFunction &MF = B.getMF();
  const SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();

  const bool IsIEEEOp = MI.getOpcode() == AMDGPU::G_FMINNUM_IEEE ||
                        MI.getOpcode() == AMDGPU::G_FMAXNUM_IEEE;

  // With ieee_mode disabled, the instructions have the correct behavior
  // already for G_FMINNUM/G_FMAXNUM
  if (!MFI->getMode().IEEE)
    return !IsIEEEOp;

  if (IsIEEEOp)
    return true;

  MachineIRBuilder HelperBuilder(MI);
  GISelObserverWrapper DummyObserver;
  LegalizerHelper Helper(MF, DummyObserver, HelperBuilder);
  HelperBuilder.setInstr(MI);
  return Helper.lowerFMinNumMaxNum(MI) == LegalizerHelper::Legalized;
}

bool AMDGPULegalizerInfo::legalizeExtractVectorElt(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  // TODO: Should move some of this into LegalizerHelper.

  // TODO: Promote dynamic indexing of s16 to s32
  // TODO: Dynamic s64 indexing is only legal for SGPR.
  Optional<int64_t> IdxVal = getConstantVRegVal(MI.getOperand(2).getReg(), MRI);
  if (!IdxVal) // Dynamic case will be selected to register indexing.
    return true;

  Register Dst = MI.getOperand(0).getReg();
  Register Vec = MI.getOperand(1).getReg();

  LLT VecTy = MRI.getType(Vec);
  LLT EltTy = VecTy.getElementType();
  assert(EltTy == MRI.getType(Dst));

  B.setInstr(MI);

  if (IdxVal.getValue() < VecTy.getNumElements())
    B.buildExtract(Dst, Vec, IdxVal.getValue() * EltTy.getSizeInBits());
  else
    B.buildUndef(Dst);

  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeInsertVectorElt(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  // TODO: Should move some of this into LegalizerHelper.

  // TODO: Promote dynamic indexing of s16 to s32
  // TODO: Dynamic s64 indexing is only legal for SGPR.
  Optional<int64_t> IdxVal = getConstantVRegVal(MI.getOperand(3).getReg(), MRI);
  if (!IdxVal) // Dynamic case will be selected to register indexing.
    return true;

  Register Dst = MI.getOperand(0).getReg();
  Register Vec = MI.getOperand(1).getReg();
  Register Ins = MI.getOperand(2).getReg();

  LLT VecTy = MRI.getType(Vec);
  LLT EltTy = VecTy.getElementType();
  assert(EltTy == MRI.getType(Ins));

  B.setInstr(MI);

  if (IdxVal.getValue() < VecTy.getNumElements())
    B.buildInsert(Dst, Vec, Ins, IdxVal.getValue() * EltTy.getSizeInBits());
  else
    B.buildUndef(Dst);

  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeSinCos(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  B.setInstr(MI);

  Register DstReg = MI.getOperand(0).getReg();
  Register SrcReg = MI.getOperand(1).getReg();
  LLT Ty = MRI.getType(DstReg);
  unsigned Flags = MI.getFlags();

  Register TrigVal;
  auto OneOver2Pi = B.buildFConstant(Ty, 0.5 / M_PI);
  if (ST.hasTrigReducedRange()) {
    auto MulVal = B.buildFMul(Ty, SrcReg, OneOver2Pi, Flags);
    TrigVal = B.buildIntrinsic(Intrinsic::amdgcn_fract, {Ty}, false)
      .addUse(MulVal.getReg(0))
      .setMIFlags(Flags).getReg(0);
  } else
    TrigVal = B.buildFMul(Ty, SrcReg, OneOver2Pi, Flags).getReg(0);

  Intrinsic::ID TrigIntrin = MI.getOpcode() == AMDGPU::G_FSIN ?
    Intrinsic::amdgcn_sin : Intrinsic::amdgcn_cos;
  B.buildIntrinsic(TrigIntrin, makeArrayRef<Register>(DstReg), false)
    .addUse(TrigVal)
    .setMIFlags(Flags);
  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::buildPCRelGlobalAddress(
  Register DstReg, LLT PtrTy,
  MachineIRBuilder &B, const GlobalValue *GV,
  unsigned Offset, unsigned GAFlags) const {
  // In order to support pc-relative addressing, SI_PC_ADD_REL_OFFSET is lowered
  // to the following code sequence:
  //
  // For constant address space:
  //   s_getpc_b64 s[0:1]
  //   s_add_u32 s0, s0, $symbol
  //   s_addc_u32 s1, s1, 0
  //
  //   s_getpc_b64 returns the address of the s_add_u32 instruction and then
  //   a fixup or relocation is emitted to replace $symbol with a literal
  //   constant, which is a pc-relative offset from the encoding of the $symbol
  //   operand to the global variable.
  //
  // For global address space:
  //   s_getpc_b64 s[0:1]
  //   s_add_u32 s0, s0, $symbol@{gotpc}rel32@lo
  //   s_addc_u32 s1, s1, $symbol@{gotpc}rel32@hi
  //
  //   s_getpc_b64 returns the address of the s_add_u32 instruction and then
  //   fixups or relocations are emitted to replace $symbol@*@lo and
  //   $symbol@*@hi with lower 32 bits and higher 32 bits of a literal constant,
  //   which is a 64-bit pc-relative offset from the encoding of the $symbol
  //   operand to the global variable.
  //
  // What we want here is an offset from the value returned by s_getpc
  // (which is the address of the s_add_u32 instruction) to the global
  // variable, but since the encoding of $symbol starts 4 bytes after the start
  // of the s_add_u32 instruction, we end up with an offset that is 4 bytes too
  // small. This requires us to add 4 to the global variable offset in order to
  // compute the correct address.

  LLT ConstPtrTy = LLT::pointer(AMDGPUAS::CONSTANT_ADDRESS, 64);

  Register PCReg = PtrTy.getSizeInBits() != 32 ? DstReg :
    B.getMRI()->createGenericVirtualRegister(ConstPtrTy);

  MachineInstrBuilder MIB = B.buildInstr(AMDGPU::SI_PC_ADD_REL_OFFSET)
    .addDef(PCReg);

  MIB.addGlobalAddress(GV, Offset + 4, GAFlags);
  if (GAFlags == SIInstrInfo::MO_NONE)
    MIB.addImm(0);
  else
    MIB.addGlobalAddress(GV, Offset + 4, GAFlags + 1);

  B.getMRI()->setRegClass(PCReg, &AMDGPU::SReg_64RegClass);

  if (PtrTy.getSizeInBits() == 32)
    B.buildExtract(DstReg, PCReg, 0);
  return true;
 }

bool AMDGPULegalizerInfo::legalizeGlobalValue(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  Register DstReg = MI.getOperand(0).getReg();
  LLT Ty = MRI.getType(DstReg);
  unsigned AS = Ty.getAddressSpace();

  const GlobalValue *GV = MI.getOperand(1).getGlobal();
  MachineFunction &MF = B.getMF();
  SIMachineFunctionInfo *MFI = MF.getInfo<SIMachineFunctionInfo>();
  B.setInstr(MI);

  if (AS == AMDGPUAS::LOCAL_ADDRESS || AS == AMDGPUAS::REGION_ADDRESS) {
    if (!MFI->isEntryFunction()) {
      const Function &Fn = MF.getFunction();
      DiagnosticInfoUnsupported BadLDSDecl(
        Fn, "local memory global used by non-kernel function", MI.getDebugLoc());
      Fn.getContext().diagnose(BadLDSDecl);
    }

    // TODO: We could emit code to handle the initialization somewhere.
    if (!AMDGPUTargetLowering::hasDefinedInitializer(GV)) {
      B.buildConstant(DstReg, MFI->allocateLDSGlobal(B.getDataLayout(), *GV));
      MI.eraseFromParent();
      return true;
    }

    const Function &Fn = MF.getFunction();
    DiagnosticInfoUnsupported BadInit(
      Fn, "unsupported initializer for address space", MI.getDebugLoc());
    Fn.getContext().diagnose(BadInit);
    return true;
  }

  const SITargetLowering *TLI = ST.getTargetLowering();

  if (TLI->shouldEmitFixup(GV)) {
    buildPCRelGlobalAddress(DstReg, Ty, B, GV, 0);
    MI.eraseFromParent();
    return true;
  }

  if (TLI->shouldEmitPCReloc(GV)) {
    buildPCRelGlobalAddress(DstReg, Ty, B, GV, 0, SIInstrInfo::MO_REL32);
    MI.eraseFromParent();
    return true;
  }

  LLT PtrTy = LLT::pointer(AMDGPUAS::CONSTANT_ADDRESS, 64);
  Register GOTAddr = MRI.createGenericVirtualRegister(PtrTy);

  MachineMemOperand *GOTMMO = MF.getMachineMemOperand(
    MachinePointerInfo::getGOT(MF),
    MachineMemOperand::MOLoad | MachineMemOperand::MODereferenceable |
    MachineMemOperand::MOInvariant,
    8 /*Size*/, 8 /*Align*/);

  buildPCRelGlobalAddress(GOTAddr, PtrTy, B, GV, 0, SIInstrInfo::MO_GOTPCREL32);

  if (Ty.getSizeInBits() == 32) {
    // Truncate if this is a 32-bit constant adrdess.
    auto Load = B.buildLoad(PtrTy, GOTAddr, *GOTMMO);
    B.buildExtract(DstReg, Load, 0);
  } else
    B.buildLoad(DstReg, GOTAddr, *GOTMMO);

  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeLoad(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B, GISelChangeObserver &Observer) const {
  B.setInstr(MI);
  LLT ConstPtr = LLT::pointer(AMDGPUAS::CONSTANT_ADDRESS, 64);
  auto Cast = B.buildAddrSpaceCast(ConstPtr, MI.getOperand(1).getReg());
  Observer.changingInstr(MI);
  MI.getOperand(1).setReg(Cast.getReg(0));
  Observer.changedInstr(MI);
  return true;
}

bool AMDGPULegalizerInfo::legalizeFMad(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  MachineIRBuilder &B) const {
  LLT Ty = MRI.getType(MI.getOperand(0).getReg());
  assert(Ty.isScalar());

  // TODO: Always legal with future ftz flag.
  if (Ty == LLT::scalar(32) && !ST.hasFP32Denormals())
    return true;
  if (Ty == LLT::scalar(16) && !ST.hasFP16Denormals())
    return true;

  MachineFunction &MF = B.getMF();

  MachineIRBuilder HelperBuilder(MI);
  GISelObserverWrapper DummyObserver;
  LegalizerHelper Helper(MF, DummyObserver, HelperBuilder);
  HelperBuilder.setMBB(*MI.getParent());
  return Helper.lowerFMad(MI) == LegalizerHelper::Legalized;
}

// Return the use branch instruction, otherwise null if the usage is invalid.
static MachineInstr *verifyCFIntrinsic(MachineInstr &MI,
                                       MachineRegisterInfo &MRI) {
  Register CondDef = MI.getOperand(0).getReg();
  if (!MRI.hasOneNonDBGUse(CondDef))
    return nullptr;

  MachineInstr &UseMI = *MRI.use_instr_nodbg_begin(CondDef);
  return UseMI.getParent() == MI.getParent() &&
    UseMI.getOpcode() == AMDGPU::G_BRCOND ? &UseMI : nullptr;
}

Register AMDGPULegalizerInfo::getLiveInRegister(MachineRegisterInfo &MRI,
                                                Register Reg, LLT Ty) const {
  Register LiveIn = MRI.getLiveInVirtReg(Reg);
  if (LiveIn)
    return LiveIn;

  Register NewReg = MRI.createGenericVirtualRegister(Ty);
  MRI.addLiveIn(Reg, NewReg);
  return NewReg;
}

bool AMDGPULegalizerInfo::loadInputValue(Register DstReg, MachineIRBuilder &B,
                                         const ArgDescriptor *Arg) const {
  if (!Arg->isRegister() || !Arg->getRegister().isValid())
    return false; // TODO: Handle these

  assert(Arg->getRegister().isPhysical());

  MachineRegisterInfo &MRI = *B.getMRI();

  LLT Ty = MRI.getType(DstReg);
  Register LiveIn = getLiveInRegister(MRI, Arg->getRegister(), Ty);

  if (Arg->isMasked()) {
    // TODO: Should we try to emit this once in the entry block?
    const LLT S32 = LLT::scalar(32);
    const unsigned Mask = Arg->getMask();
    const unsigned Shift = countTrailingZeros<unsigned>(Mask);

    Register AndMaskSrc = LiveIn;

    if (Shift != 0) {
      auto ShiftAmt = B.buildConstant(S32, Shift);
      AndMaskSrc = B.buildLShr(S32, LiveIn, ShiftAmt).getReg(0);
    }

    B.buildAnd(DstReg, AndMaskSrc, B.buildConstant(S32, Mask >> Shift));
  } else
    B.buildCopy(DstReg, LiveIn);

  // Insert the argument copy if it doens't already exist.
  // FIXME: It seems EmitLiveInCopies isn't called anywhere?
  if (!MRI.getVRegDef(LiveIn)) {
    // FIXME: Should have scoped insert pt
    MachineBasicBlock &OrigInsBB = B.getMBB();
    auto OrigInsPt = B.getInsertPt();

    MachineBasicBlock &EntryMBB = B.getMF().front();
    EntryMBB.addLiveIn(Arg->getRegister());
    B.setInsertPt(EntryMBB, EntryMBB.begin());
    B.buildCopy(LiveIn, Arg->getRegister());

    B.setInsertPt(OrigInsBB, OrigInsPt);
  }

  return true;
}

bool AMDGPULegalizerInfo::legalizePreloadedArgIntrin(
  MachineInstr &MI,
  MachineRegisterInfo &MRI,
  MachineIRBuilder &B,
  AMDGPUFunctionArgInfo::PreloadedValue ArgType) const {
  B.setInstr(MI);

  const SIMachineFunctionInfo *MFI = B.getMF().getInfo<SIMachineFunctionInfo>();

  const ArgDescriptor *Arg;
  const TargetRegisterClass *RC;
  std::tie(Arg, RC) = MFI->getPreloadedValue(ArgType);
  if (!Arg) {
    LLVM_DEBUG(dbgs() << "Required arg register missing\n");
    return false;
  }

  if (loadInputValue(MI.getOperand(0).getReg(), B, Arg)) {
    MI.eraseFromParent();
    return true;
  }

  return false;
}

bool AMDGPULegalizerInfo::legalizeFDIVFast(MachineInstr &MI,
                                           MachineRegisterInfo &MRI,
                                           MachineIRBuilder &B) const {
  B.setInstr(MI);
  Register Res = MI.getOperand(0).getReg();
  Register LHS = MI.getOperand(2).getReg();
  Register RHS = MI.getOperand(3).getReg();
  uint16_t Flags = MI.getFlags();

  LLT S32 = LLT::scalar(32);
  LLT S1 = LLT::scalar(1);

  auto Abs = B.buildFAbs(S32, RHS, Flags);
  const APFloat C0Val(1.0f);

  auto C0 = B.buildConstant(S32, 0x6f800000);
  auto C1 = B.buildConstant(S32, 0x2f800000);
  auto C2 = B.buildConstant(S32, FloatToBits(1.0f));

  auto CmpRes = B.buildFCmp(CmpInst::FCMP_OGT, S1, Abs, C0, Flags);
  auto Sel = B.buildSelect(S32, CmpRes, C1, C2, Flags);

  auto Mul0 = B.buildFMul(S32, RHS, Sel, Flags);

  auto RCP = B.buildIntrinsic(Intrinsic::amdgcn_rcp, {S32}, false)
    .addUse(Mul0.getReg(0))
    .setMIFlags(Flags);

  auto Mul1 = B.buildFMul(S32, LHS, RCP, Flags);

  B.buildFMul(Res, Sel, Mul1, Flags);

  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeImplicitArgPtr(MachineInstr &MI,
                                                 MachineRegisterInfo &MRI,
                                                 MachineIRBuilder &B) const {
  const SIMachineFunctionInfo *MFI = B.getMF().getInfo<SIMachineFunctionInfo>();
  if (!MFI->isEntryFunction()) {
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::IMPLICIT_ARG_PTR);
  }

  B.setInstr(MI);

  uint64_t Offset =
    ST.getTargetLowering()->getImplicitParameterOffset(
      B.getMF(), AMDGPUTargetLowering::FIRST_IMPLICIT);
  Register DstReg = MI.getOperand(0).getReg();
  LLT DstTy = MRI.getType(DstReg);
  LLT IdxTy = LLT::scalar(DstTy.getSizeInBits());

  const ArgDescriptor *Arg;
  const TargetRegisterClass *RC;
  std::tie(Arg, RC)
    = MFI->getPreloadedValue(AMDGPUFunctionArgInfo::KERNARG_SEGMENT_PTR);
  if (!Arg)
    return false;

  Register KernargPtrReg = MRI.createGenericVirtualRegister(DstTy);
  if (!loadInputValue(KernargPtrReg, B, Arg))
    return false;

  B.buildGEP(DstReg, KernargPtrReg, B.buildConstant(IdxTy, Offset).getReg(0));
  MI.eraseFromParent();
  return true;
}

bool AMDGPULegalizerInfo::legalizeIsAddrSpace(MachineInstr &MI,
                                              MachineRegisterInfo &MRI,
                                              MachineIRBuilder &B,
                                              unsigned AddrSpace) const {
  B.setInstr(MI);
  Register ApertureReg = getSegmentAperture(AddrSpace, MRI, B);
  auto Hi32 = B.buildExtract(LLT::scalar(32), MI.getOperand(2).getReg(), 32);
  B.buildICmp(ICmpInst::ICMP_EQ, MI.getOperand(0), Hi32, ApertureReg);
  MI.eraseFromParent();
  return true;
}

/// Handle register layout difference for f16 images for some subtargets.
Register AMDGPULegalizerInfo::handleD16VData(MachineIRBuilder &B,
                                             MachineRegisterInfo &MRI,
                                             Register Reg) const {
  if (!ST.hasUnpackedD16VMem())
    return Reg;

  const LLT S16 = LLT::scalar(16);
  const LLT S32 = LLT::scalar(32);
  LLT StoreVT = MRI.getType(Reg);
  assert(StoreVT.isVector() && StoreVT.getElementType() == S16);

  auto Unmerge = B.buildUnmerge(S16, Reg);

  SmallVector<Register, 4> WideRegs;
  for (int I = 0, E = Unmerge->getNumOperands() - 1; I != E; ++I)
    WideRegs.push_back(B.buildAnyExt(S32, Unmerge.getReg(I)).getReg(0));

  int NumElts = StoreVT.getNumElements();

  return B.buildBuildVector(LLT::vector(NumElts, S32), WideRegs).getReg(0);
}

bool AMDGPULegalizerInfo::legalizeRawBufferStore(MachineInstr &MI,
                                                 MachineRegisterInfo &MRI,
                                                 MachineIRBuilder &B,
                                                 bool IsFormat) const {
  // TODO: Reject f16 format on targets where unsupported.
  Register VData = MI.getOperand(1).getReg();
  LLT Ty = MRI.getType(VData);

  B.setInstr(MI);

  const LLT S32 = LLT::scalar(32);
  const LLT S16 = LLT::scalar(16);

  // Fixup illegal register types for i8 stores.
  if (Ty == LLT::scalar(8) || Ty == S16) {
    Register AnyExt = B.buildAnyExt(LLT::scalar(32), VData).getReg(0);
    MI.getOperand(1).setReg(AnyExt);
    return true;
  }

  if (Ty.isVector()) {
    if (Ty.getElementType() == S16 && Ty.getNumElements() <= 4) {
      if (IsFormat)
        MI.getOperand(1).setReg(handleD16VData(B, MRI, VData));
      return true;
    }

    return Ty.getElementType() == S32 && Ty.getNumElements() <= 4;
  }

  return Ty == S32;
}

bool AMDGPULegalizerInfo::legalizeIntrinsic(MachineInstr &MI,
                                            MachineRegisterInfo &MRI,
                                            MachineIRBuilder &B) const {
  // Replace the use G_BRCOND with the exec manipulate and branch pseudos.
  switch (MI.getIntrinsicID()) {
  case Intrinsic::amdgcn_if: {
    if (MachineInstr *BrCond = verifyCFIntrinsic(MI, MRI)) {
      const SIRegisterInfo *TRI
        = static_cast<const SIRegisterInfo *>(MRI.getTargetRegisterInfo());

      B.setInstr(*BrCond);
      Register Def = MI.getOperand(1).getReg();
      Register Use = MI.getOperand(3).getReg();
      B.buildInstr(AMDGPU::SI_IF)
        .addDef(Def)
        .addUse(Use)
        .addMBB(BrCond->getOperand(1).getMBB());

      MRI.setRegClass(Def, TRI->getWaveMaskRegClass());
      MRI.setRegClass(Use, TRI->getWaveMaskRegClass());
      MI.eraseFromParent();
      BrCond->eraseFromParent();
      return true;
    }

    return false;
  }
  case Intrinsic::amdgcn_loop: {
    if (MachineInstr *BrCond = verifyCFIntrinsic(MI, MRI)) {
      const SIRegisterInfo *TRI
        = static_cast<const SIRegisterInfo *>(MRI.getTargetRegisterInfo());

      B.setInstr(*BrCond);
      Register Reg = MI.getOperand(2).getReg();
      B.buildInstr(AMDGPU::SI_LOOP)
        .addUse(Reg)
        .addMBB(BrCond->getOperand(1).getMBB());
      MI.eraseFromParent();
      BrCond->eraseFromParent();
      MRI.setRegClass(Reg, TRI->getWaveMaskRegClass());
      return true;
    }

    return false;
  }
  case Intrinsic::amdgcn_kernarg_segment_ptr:
    return legalizePreloadedArgIntrin(
      MI, MRI, B, AMDGPUFunctionArgInfo::KERNARG_SEGMENT_PTR);
  case Intrinsic::amdgcn_implicitarg_ptr:
    return legalizeImplicitArgPtr(MI, MRI, B);
  case Intrinsic::amdgcn_workitem_id_x:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKITEM_ID_X);
  case Intrinsic::amdgcn_workitem_id_y:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKITEM_ID_Y);
  case Intrinsic::amdgcn_workitem_id_z:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKITEM_ID_Z);
  case Intrinsic::amdgcn_workgroup_id_x:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKGROUP_ID_X);
  case Intrinsic::amdgcn_workgroup_id_y:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKGROUP_ID_Y);
  case Intrinsic::amdgcn_workgroup_id_z:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::WORKGROUP_ID_Z);
  case Intrinsic::amdgcn_dispatch_ptr:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::DISPATCH_PTR);
  case Intrinsic::amdgcn_queue_ptr:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::QUEUE_PTR);
  case Intrinsic::amdgcn_implicit_buffer_ptr:
    return legalizePreloadedArgIntrin(
      MI, MRI, B, AMDGPUFunctionArgInfo::IMPLICIT_BUFFER_PTR);
  case Intrinsic::amdgcn_dispatch_id:
    return legalizePreloadedArgIntrin(MI, MRI, B,
                                      AMDGPUFunctionArgInfo::DISPATCH_ID);
  case Intrinsic::amdgcn_fdiv_fast:
    return legalizeFDIVFast(MI, MRI, B);
  case Intrinsic::amdgcn_is_shared:
    return legalizeIsAddrSpace(MI, MRI, B, AMDGPUAS::LOCAL_ADDRESS);
  case Intrinsic::amdgcn_is_private:
    return legalizeIsAddrSpace(MI, MRI, B, AMDGPUAS::PRIVATE_ADDRESS);
  case Intrinsic::amdgcn_wavefrontsize: {
    B.setInstr(MI);
    B.buildConstant(MI.getOperand(0), ST.getWavefrontSize());
    MI.eraseFromParent();
    return true;
  }
  case Intrinsic::amdgcn_raw_buffer_store:
    return legalizeRawBufferStore(MI, MRI, B, false);
  case Intrinsic::amdgcn_raw_buffer_store_format:
    return legalizeRawBufferStore(MI, MRI, B, true);
  default:
    return true;
  }

  return true;
}