Target/AMDGPU/AMDGPURegisterBankInfo.cpp

//===- AMDGPURegisterBankInfo.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 RegisterBankInfo class for
/// AMDGPU.
/// \todo This should be generated by TableGen.
//===----------------------------------------------------------------------===//

#include "AMDGPURegisterBankInfo.h"
#include "AMDGPUInstrInfo.h"
#include "AMDGPUSubtarget.h"
#include "SIMachineFunctionInfo.h"
#include "SIRegisterInfo.h"
#include "MCTargetDesc/AMDGPUMCTargetDesc.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/RegisterBank.h"
#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/IR/Constants.h"

#define GET_TARGET_REGBANK_IMPL
#include "AMDGPUGenRegisterBank.inc"

// This file will be TableGen'ed at some point.
#include "AMDGPUGenRegisterBankInfo.def"

using namespace llvm;

AMDGPURegisterBankInfo::AMDGPURegisterBankInfo(const TargetRegisterInfo &TRI)
    : AMDGPUGenRegisterBankInfo(),
      TRI(static_cast<const SIRegisterInfo*>(&TRI)) {

  // HACK: Until this is fully tablegen'd.
  static bool AlreadyInit = false;
  if (AlreadyInit)
    return;

  AlreadyInit = true;

  const RegisterBank &RBSGPR = getRegBank(AMDGPU::SGPRRegBankID);
  (void)RBSGPR;
  assert(&RBSGPR == &AMDGPU::SGPRRegBank);

  const RegisterBank &RBVGPR = getRegBank(AMDGPU::VGPRRegBankID);
  (void)RBVGPR;
  assert(&RBVGPR == &AMDGPU::VGPRRegBank);

}

unsigned AMDGPURegisterBankInfo::copyCost(const RegisterBank &Dst,
                                          const RegisterBank &Src,
                                          unsigned Size) const {
  if (Dst.getID() == AMDGPU::SGPRRegBankID &&
      Src.getID() == AMDGPU::VGPRRegBankID) {
    return std::numeric_limits<unsigned>::max();
  }

  // SGPRRegBank with size 1 is actually vcc or another 64-bit sgpr written by
  // the valu.
  if (Size == 1 && Dst.getID() == AMDGPU::SCCRegBankID &&
      (Src.getID() == AMDGPU::SGPRRegBankID ||
       Src.getID() == AMDGPU::VGPRRegBankID ||
       Src.getID() == AMDGPU::VCCRegBankID))
    return std::numeric_limits<unsigned>::max();

  if (Dst.getID() == AMDGPU::SCCRegBankID &&
      Src.getID() == AMDGPU::VCCRegBankID)
    return std::numeric_limits<unsigned>::max();

  return RegisterBankInfo::copyCost(Dst, Src, Size);
}

unsigned AMDGPURegisterBankInfo::getBreakDownCost(
  const ValueMapping &ValMapping,
  const RegisterBank *CurBank) const {
  assert(ValMapping.NumBreakDowns == 2 &&
         ValMapping.BreakDown[0].Length == 32 &&
         ValMapping.BreakDown[0].StartIdx == 0 &&
         ValMapping.BreakDown[1].Length == 32 &&
         ValMapping.BreakDown[1].StartIdx == 32 &&
         ValMapping.BreakDown[0].RegBank == ValMapping.BreakDown[1].RegBank);

  // 32-bit extract of a 64-bit value is just access of a subregister, so free.
  // TODO: Cost of 0 hits assert, though it's not clear it's what we really
  // want.

  // TODO: 32-bit insert to a 64-bit SGPR may incur a non-free copy due to SGPR
  // alignment restrictions, but this probably isn't important.
  return 1;
}

const RegisterBank &AMDGPURegisterBankInfo::getRegBankFromRegClass(
    const TargetRegisterClass &RC) const {

  if (TRI->isSGPRClass(&RC))
    return getRegBank(AMDGPU::SGPRRegBankID);

  return getRegBank(AMDGPU::VGPRRegBankID);
}

template <unsigned NumOps>
RegisterBankInfo::InstructionMappings
AMDGPURegisterBankInfo::addMappingFromTable(
    const MachineInstr &MI, const MachineRegisterInfo &MRI,
    const std::array<unsigned, NumOps> RegSrcOpIdx,
    ArrayRef<OpRegBankEntry<NumOps>> Table) const {

  InstructionMappings AltMappings;

  SmallVector<const ValueMapping *, 10> Operands(MI.getNumOperands());

  unsigned Sizes[NumOps];
  for (unsigned I = 0; I < NumOps; ++I) {
    unsigned Reg = MI.getOperand(RegSrcOpIdx[I]).getReg();
    Sizes[I] = getSizeInBits(Reg, MRI, *TRI);
  }

  for (unsigned I = 0, E = MI.getNumExplicitDefs(); I != E; ++I) {
    unsigned SizeI = getSizeInBits(MI.getOperand(I).getReg(), MRI, *TRI);
    Operands[I] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, SizeI);
  }

  unsigned MappingID = 0;
  for (const auto &Entry : Table) {
    for (unsigned I = 0; I < NumOps; ++I) {
      int OpIdx = RegSrcOpIdx[I];
      Operands[OpIdx] = AMDGPU::getValueMapping(Entry.RegBanks[I], Sizes[I]);
    }

    AltMappings.push_back(&getInstructionMapping(MappingID++, Entry.Cost,
                                                 getOperandsMapping(Operands),
                                                 Operands.size()));
  }

  return AltMappings;
}

RegisterBankInfo::InstructionMappings
AMDGPURegisterBankInfo::getInstrAlternativeMappingsIntrinsicWSideEffects(
    const MachineInstr &MI, const MachineRegisterInfo &MRI) const {

  switch (MI.getOperand(MI.getNumExplicitDefs()).getIntrinsicID()) {
  case Intrinsic::amdgcn_buffer_load: {
    static const OpRegBankEntry<3> Table[4] = {
      // Perfectly legal.
      { { AMDGPU::SGPRRegBankID, AMDGPU::VGPRRegBankID, AMDGPU::SGPRRegBankID }, 1 },
      { { AMDGPU::SGPRRegBankID, AMDGPU::VGPRRegBankID, AMDGPU::VGPRRegBankID }, 1 },

      // Waterfall loop needed for rsrc. In the worst case this will execute
      // approximately an extra 10 * wavesize + 2 instructions.
      { { AMDGPU::VGPRRegBankID, AMDGPU::VGPRRegBankID, AMDGPU::SGPRRegBankID }, 1000 },
      { { AMDGPU::VGPRRegBankID, AMDGPU::VGPRRegBankID, AMDGPU::VGPRRegBankID }, 1000 }
    };

    // rsrc, voffset, offset
    const std::array<unsigned, 3> RegSrcOpIdx = { { 2, 3, 4 } };
    return addMappingFromTable<3>(MI, MRI, RegSrcOpIdx, makeArrayRef(Table));
  }
  case Intrinsic::amdgcn_s_buffer_load: {
    static const OpRegBankEntry<2> Table[4] = {
      // Perfectly legal.
      { { AMDGPU::SGPRRegBankID, AMDGPU::SGPRRegBankID }, 1 },

      // Only need 1 register in loop
      { { AMDGPU::SGPRRegBankID, AMDGPU::VGPRRegBankID }, 300 },

      // Have to waterfall the resource.
      { { AMDGPU::VGPRRegBankID, AMDGPU::SGPRRegBankID }, 1000 },

      // Have to waterfall the resource, and the offset.
      { { AMDGPU::VGPRRegBankID, AMDGPU::VGPRRegBankID }, 1500 }
    };

    // rsrc, offset
    const std::array<unsigned, 2> RegSrcOpIdx = { { 2, 3 } };
    return addMappingFromTable<2>(MI, MRI, RegSrcOpIdx, makeArrayRef(Table));
  }
  default:
    return RegisterBankInfo::getInstrAlternativeMappings(MI);
  }
}

RegisterBankInfo::InstructionMappings
AMDGPURegisterBankInfo::getInstrAlternativeMappings(
    const MachineInstr &MI) const {

  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();


  InstructionMappings AltMappings;
  switch (MI.getOpcode()) {
  case TargetOpcode::G_AND:
  case TargetOpcode::G_OR:
  case TargetOpcode::G_XOR: {
    unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    if (Size != 64)
      break;

    const InstructionMapping &SSMapping = getInstructionMapping(
      1, 1, getOperandsMapping(
        {AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size)}),
      3); // Num Operands
    AltMappings.push_back(&SSMapping);

    const InstructionMapping &VVMapping = getInstructionMapping(
      2, 2, getOperandsMapping(
        {AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size)}),
      3); // Num Operands
    AltMappings.push_back(&VVMapping);

    const InstructionMapping &SVMapping = getInstructionMapping(
      3, 3, getOperandsMapping(
        {AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size)}),
      3); // Num Operands
    AltMappings.push_back(&SVMapping);

    // SGPR in LHS is slightly preferrable, so make it VS more expnesive than
    // SV.
    const InstructionMapping &VSMapping = getInstructionMapping(
      3, 4, getOperandsMapping(
        {AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
         AMDGPU::getValueMappingSGPR64Only(AMDGPU::SGPRRegBankID, Size)}),
      3); // Num Operands
    AltMappings.push_back(&VSMapping);
    break;
  }
  case TargetOpcode::G_LOAD: {
    unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    // FIXME: Should we be hard coding the size for these mappings?
    const InstructionMapping &SSMapping = getInstructionMapping(
        1, 1, getOperandsMapping(
                  {AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
                   AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 64)}),
        2); // Num Operands
    AltMappings.push_back(&SSMapping);

    const InstructionMapping &VVMapping = getInstructionMapping(
        2, 1, getOperandsMapping(
                  {AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                   AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 64)}),
        2); // Num Operands
    AltMappings.push_back(&VVMapping);

    // FIXME: Should this be the pointer-size (64-bits) or the size of the
    // register that will hold the bufffer resourc (128-bits).
    const InstructionMapping &VSMapping = getInstructionMapping(
        3, 1, getOperandsMapping(
                  {AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                   AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 64)}),
        2); // Num Operands
    AltMappings.push_back(&VSMapping);

    return AltMappings;

  }
  case TargetOpcode::G_ICMP: {
    unsigned Size = getSizeInBits(MI.getOperand(2).getReg(), MRI, *TRI);
    const InstructionMapping &SSMapping = getInstructionMapping(1, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::SCCRegBankID, 1),
                          nullptr, // Predicate operand.
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&SSMapping);

    const InstructionMapping &SVMapping = getInstructionMapping(2, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1),
                          nullptr, // Predicate operand.
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&SVMapping);

    const InstructionMapping &VSMapping = getInstructionMapping(3, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1),
                          nullptr, // Predicate operand.
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&VSMapping);

    const InstructionMapping &VVMapping = getInstructionMapping(4, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1),
                          nullptr, // Predicate operand.
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&VVMapping);

    return AltMappings;
  }
  case TargetOpcode::G_SELECT: {
    unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    const InstructionMapping &SSMapping = getInstructionMapping(1, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::SCCRegBankID, 1),
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&SSMapping);

    const InstructionMapping &VVMapping = getInstructionMapping(2, 1,
      getOperandsMapping({AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1),
                          AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size)}),
      4); // Num Operands
    AltMappings.push_back(&VVMapping);

    return AltMappings;
  }
  case TargetOpcode::G_UADDE:
  case TargetOpcode::G_USUBE:
  case TargetOpcode::G_SADDE:
  case TargetOpcode::G_SSUBE: {
    unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    const InstructionMapping &SSMapping = getInstructionMapping(1, 1,
      getOperandsMapping(
        {AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMapping(AMDGPU::SCCRegBankID, 1),
         AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size),
         AMDGPU::getValueMapping(AMDGPU::SCCRegBankID, 1)}),
      5); // Num Operands
    AltMappings.push_back(&SSMapping);

    const InstructionMapping &VVMapping = getInstructionMapping(2, 1,
      getOperandsMapping({AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1),
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size),
                          AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1)}),
      5); // Num Operands
    AltMappings.push_back(&VVMapping);
    return AltMappings;
  }
  case AMDGPU::G_BRCOND: {
    assert(MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() == 1);

    const InstructionMapping &SMapping = getInstructionMapping(
      1, 1, getOperandsMapping(
        {AMDGPU::getValueMapping(AMDGPU::SCCRegBankID, 1), nullptr}),
      2); // Num Operands
    AltMappings.push_back(&SMapping);

    const InstructionMapping &VMapping = getInstructionMapping(
      1, 1, getOperandsMapping(
        {AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1), nullptr }),
      2); // Num Operands
    AltMappings.push_back(&VMapping);
    return AltMappings;
  }
  case AMDGPU::G_INTRINSIC_W_SIDE_EFFECTS:
    return getInstrAlternativeMappingsIntrinsicWSideEffects(MI, MRI);
  default:
    break;
  }
  return RegisterBankInfo::getInstrAlternativeMappings(MI);
}

void AMDGPURegisterBankInfo::split64BitValueForMapping(
  MachineIRBuilder &B,
  SmallVector<Register, 2> &Regs,
  LLT HalfTy,
  unsigned Reg) const {
  assert(HalfTy.getSizeInBits() == 32);
  MachineRegisterInfo *MRI = B.getMRI();
  unsigned LoLHS = MRI->createGenericVirtualRegister(HalfTy);
  unsigned HiLHS = MRI->createGenericVirtualRegister(HalfTy);
  const RegisterBank *Bank = getRegBank(Reg, *MRI, *TRI);
  MRI->setRegBank(LoLHS, *Bank);
  MRI->setRegBank(HiLHS, *Bank);

  Regs.push_back(LoLHS);
  Regs.push_back(HiLHS);

  B.buildInstr(AMDGPU::G_UNMERGE_VALUES)
    .addDef(LoLHS)
    .addDef(HiLHS)
    .addUse(Reg);
}

/// Replace the current type each register in \p Regs has with \p NewTy
static void setRegsToType(MachineRegisterInfo &MRI, ArrayRef<Register> Regs,
                          LLT NewTy) {
  for (unsigned Reg : Regs) {
    assert(MRI.getType(Reg).getSizeInBits() == NewTy.getSizeInBits());
    MRI.setType(Reg, NewTy);
  }
}

static LLT getHalfSizedType(LLT Ty) {
  if (Ty.isVector()) {
    assert(Ty.getNumElements() % 2 == 0);
    return LLT::scalarOrVector(Ty.getNumElements() / 2, Ty.getElementType());
  }

  assert(Ty.getSizeInBits() % 2 == 0);
  return LLT::scalar(Ty.getSizeInBits() / 2);
}

/// Legalize instruction \p MI where operands in \p OpIndices must be SGPRs. If
/// any of the required SGPR operands are VGPRs, perform a waterfall loop to
/// execute the instruction for each unique combination of values in all lanes
/// in the wave. The block will be split such that rest of the instructions are
/// moved to a new block.
///
/// Essentially performs this loop:
//
/// Save Execution Mask
/// For (Lane : Wavefront) {
///   Enable Lane, Disable all other lanes
///   SGPR = read SGPR value for current lane from VGPR
///   VGPRResult[Lane] = use_op SGPR
/// }
/// Restore Execution Mask
///
/// There is additional complexity to try for compare values to identify the
/// unique values used.
void AMDGPURegisterBankInfo::executeInWaterfallLoop(
  MachineInstr &MI, MachineRegisterInfo &MRI,
  ArrayRef<unsigned> OpIndices) const {
  MachineFunction *MF = MI.getParent()->getParent();
  const GCNSubtarget &ST = MF->getSubtarget<GCNSubtarget>();
  const SIInstrInfo *TII = ST.getInstrInfo();
  MachineBasicBlock::iterator I(MI);

  MachineBasicBlock &MBB = *MI.getParent();
  const DebugLoc &DL = MI.getDebugLoc();

  // Use a set to avoid extra readfirstlanes in the case where multiple operands
  // are the same register.
  SmallSet<Register, 4> SGPROperandRegs;
  for (unsigned Op : OpIndices) {
    assert(MI.getOperand(Op).isUse());
    unsigned Reg = MI.getOperand(Op).getReg();
    const RegisterBank *OpBank = getRegBank(Reg, MRI, *TRI);
    if (OpBank->getID() == AMDGPU::VGPRRegBankID)
      SGPROperandRegs.insert(Reg);
  }

  // No operands need to be replaced, so no need to loop.
  if (SGPROperandRegs.empty())
    return;

  MachineIRBuilder B(MI);
  SmallVector<Register, 4> ResultRegs;
  SmallVector<Register, 4> InitResultRegs;
  SmallVector<Register, 4> PhiRegs;
  for (MachineOperand &Def : MI.defs()) {
    LLT ResTy = MRI.getType(Def.getReg());
    const RegisterBank *DefBank = getRegBank(Def.getReg(), MRI, *TRI);
    ResultRegs.push_back(Def.getReg());
    unsigned InitReg = B.buildUndef(ResTy).getReg(0);
    unsigned PhiReg = MRI.createGenericVirtualRegister(ResTy);
    InitResultRegs.push_back(InitReg);
    PhiRegs.push_back(PhiReg);
    MRI.setRegBank(PhiReg, *DefBank);
    MRI.setRegBank(InitReg, *DefBank);
  }

  unsigned SaveExecReg = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
  unsigned InitSaveExecReg = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);

  // Don't bother using generic instructions/registers for the exec mask.
  B.buildInstr(TargetOpcode::IMPLICIT_DEF)
    .addDef(InitSaveExecReg);

  unsigned PhiExec = MRI.createVirtualRegister(&AMDGPU::SReg_64RegClass);
  unsigned NewExec = MRI.createVirtualRegister(&AMDGPU::SReg_64RegClass);

  // To insert the loop we need to split the block. Move everything before this
  // point to a new block, and insert a new empty block before this instruction.
  MachineBasicBlock *LoopBB = MF->CreateMachineBasicBlock();
  MachineBasicBlock *RemainderBB = MF->CreateMachineBasicBlock();
  MachineBasicBlock *RestoreExecBB = MF->CreateMachineBasicBlock();
  MachineFunction::iterator MBBI(MBB);
  ++MBBI;
  MF->insert(MBBI, LoopBB);
  MF->insert(MBBI, RestoreExecBB);
  MF->insert(MBBI, RemainderBB);

  LoopBB->addSuccessor(RestoreExecBB);
  LoopBB->addSuccessor(LoopBB);

  // Move the rest of the block into a new block.
  RemainderBB->transferSuccessorsAndUpdatePHIs(&MBB);
  RemainderBB->splice(RemainderBB->begin(), &MBB, I, MBB.end());

  MBB.addSuccessor(LoopBB);
  RestoreExecBB->addSuccessor(RemainderBB);

  B.setInsertPt(*LoopBB, LoopBB->end());

  B.buildInstr(TargetOpcode::PHI)
    .addDef(PhiExec)
    .addReg(InitSaveExecReg)
    .addMBB(&MBB)
    .addReg(NewExec)
    .addMBB(LoopBB);

  for (auto Result : zip(InitResultRegs, ResultRegs, PhiRegs)) {
    B.buildInstr(TargetOpcode::G_PHI)
      .addDef(std::get<2>(Result))
      .addReg(std::get<0>(Result)) // Initial value / implicit_def
      .addMBB(&MBB)
      .addReg(std::get<1>(Result)) // Mid-loop value.
      .addMBB(LoopBB);
  }

  // Move the instruction into the loop.
  LoopBB->splice(LoopBB->end(), &MBB, I);
  I = std::prev(LoopBB->end());

  B.setInstr(*I);

  unsigned CondReg = AMDGPU::NoRegister;

  for (MachineOperand &Op : MI.uses()) {
    if (!Op.isReg())
      continue;

    assert(!Op.isDef());
    if (SGPROperandRegs.count(Op.getReg())) {
      LLT OpTy = MRI.getType(Op.getReg());
      unsigned OpSize = OpTy.getSizeInBits();

      // Can only do a readlane of 32-bit pieces.
      if (OpSize == 32) {
        // Avoid extra copies in the simple case of one 32-bit register.
        unsigned CurrentLaneOpReg = MRI.createVirtualRegister(&AMDGPU::SReg_32_XM0RegClass);
        MRI.setType(CurrentLaneOpReg, OpTy);

        constrainGenericRegister(Op.getReg(), AMDGPU::VGPR_32RegClass, MRI);
        // Read the next variant <- also loop target.
        BuildMI(*LoopBB, I, DL, TII->get(AMDGPU::V_READFIRSTLANE_B32), CurrentLaneOpReg)
          .addReg(Op.getReg());

        unsigned NewCondReg = MRI.createVirtualRegister(&AMDGPU::SReg_64RegClass);
        bool First = CondReg == AMDGPU::NoRegister;
        if (First)
          CondReg = NewCondReg;

        // Compare the just read M0 value to all possible Idx values.
        B.buildInstr(AMDGPU::V_CMP_EQ_U32_e64)
          .addDef(NewCondReg)
          .addReg(CurrentLaneOpReg)
          .addReg(Op.getReg());
        Op.setReg(CurrentLaneOpReg);

        if (!First) {
          unsigned AndReg = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);

          // If there are multiple operands to consider, and the conditions.
          B.buildInstr(AMDGPU::S_AND_B64)
            .addDef(AndReg)
            .addReg(NewCondReg)
            .addReg(CondReg);
          CondReg = AndReg;
        }
      } else {
        LLT S32 = LLT::scalar(32);
        SmallVector<Register, 8> ReadlanePieces;

        // The compares can be done as 64-bit, but the extract needs to be done
        // in 32-bit pieces.

        bool Is64 = OpSize % 64 == 0;

        LLT UnmergeTy = OpSize % 64 == 0 ? LLT::scalar(64) : LLT::scalar(32);
        unsigned CmpOp = OpSize % 64 == 0 ? AMDGPU::V_CMP_EQ_U64_e64
                                          : AMDGPU::V_CMP_EQ_U32_e64;

        // The compares can be done as 64-bit, but the extract needs to be done
        // in 32-bit pieces.

        // Insert the unmerge before the loop.

        B.setMBB(MBB);
        auto Unmerge = B.buildUnmerge(UnmergeTy, Op.getReg());
        B.setInstr(*I);

        unsigned NumPieces = Unmerge->getNumOperands() - 1;
        for (unsigned PieceIdx = 0; PieceIdx != NumPieces; ++PieceIdx) {
          unsigned UnmergePiece = Unmerge.getReg(PieceIdx);

          unsigned CurrentLaneOpReg;
          if (Is64) {
            unsigned CurrentLaneOpRegLo = MRI.createGenericVirtualRegister(S32);
            unsigned CurrentLaneOpRegHi = MRI.createGenericVirtualRegister(S32);

            MRI.setRegClass(UnmergePiece, &AMDGPU::VReg_64RegClass);
            MRI.setRegClass(CurrentLaneOpRegLo, &AMDGPU::SReg_32_XM0RegClass);
            MRI.setRegClass(CurrentLaneOpRegHi, &AMDGPU::SReg_32_XM0RegClass);

            // Read the next variant <- also loop target.
            BuildMI(*LoopBB, I, DL, TII->get(AMDGPU::V_READFIRSTLANE_B32),
                    CurrentLaneOpRegLo)
              .addReg(UnmergePiece, 0, AMDGPU::sub0);

            // Read the next variant <- also loop target.
            BuildMI(*LoopBB, I, DL, TII->get(AMDGPU::V_READFIRSTLANE_B32),
                    CurrentLaneOpRegHi)
              .addReg(UnmergePiece, 0, AMDGPU::sub1);

            CurrentLaneOpReg =
                B.buildMerge(LLT::scalar(64),
                             {CurrentLaneOpRegLo, CurrentLaneOpRegHi})
                    .getReg(0);

            MRI.setRegClass(CurrentLaneOpReg, &AMDGPU::SReg_64_XEXECRegClass);

            if (OpTy.getScalarSizeInBits() == 64) {
              // If we need to produce a 64-bit element vector, so use the
              // merged pieces
              ReadlanePieces.push_back(CurrentLaneOpReg);
            } else {
              // 32-bit element type.
              ReadlanePieces.push_back(CurrentLaneOpRegLo);
              ReadlanePieces.push_back(CurrentLaneOpRegHi);
            }
          } else {
            CurrentLaneOpReg = MRI.createGenericVirtualRegister(LLT::scalar(32));
            MRI.setRegClass(UnmergePiece, &AMDGPU::VGPR_32RegClass);
            MRI.setRegClass(CurrentLaneOpReg, &AMDGPU::SReg_32_XM0RegClass);

            // Read the next variant <- also loop target.
            BuildMI(*LoopBB, I, DL, TII->get(AMDGPU::V_READFIRSTLANE_B32),
                    CurrentLaneOpReg)
              .addReg(UnmergePiece);
            ReadlanePieces.push_back(CurrentLaneOpReg);
          }

          unsigned NewCondReg
            = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);
          bool First = CondReg == AMDGPU::NoRegister;
          if (First)
            CondReg = NewCondReg;

          B.buildInstr(CmpOp)
            .addDef(NewCondReg)
            .addReg(CurrentLaneOpReg)
            .addReg(UnmergePiece);

          if (!First) {
            unsigned AndReg
              = MRI.createVirtualRegister(&AMDGPU::SReg_64_XEXECRegClass);

            // If there are multiple operands to consider, and the conditions.
            B.buildInstr(AMDGPU::S_AND_B64)
              .addDef(AndReg)
              .addReg(NewCondReg)
              .addReg(CondReg);
            CondReg = AndReg;
          }
        }

        // FIXME: Build merge seems to switch to CONCAT_VECTORS but not
        // BUILD_VECTOR
        if (OpTy.isVector()) {
          auto Merge = B.buildBuildVector(OpTy, ReadlanePieces);
          Op.setReg(Merge.getReg(0));
        } else {
          auto Merge = B.buildMerge(OpTy, ReadlanePieces);
          Op.setReg(Merge.getReg(0));
        }

        MRI.setRegBank(Op.getReg(), getRegBank(AMDGPU::SGPRRegBankID));
      }
    }
  }

  B.setInsertPt(*LoopBB, LoopBB->end());

  // Update EXEC, save the original EXEC value to VCC.
  B.buildInstr(AMDGPU::S_AND_SAVEEXEC_B64)
    .addDef(NewExec)
    .addReg(CondReg, RegState::Kill);

  MRI.setSimpleHint(NewExec, CondReg);

  // Update EXEC, switch all done bits to 0 and all todo bits to 1.
  B.buildInstr(AMDGPU::S_XOR_B64_term)
    .addDef(AMDGPU::EXEC)
    .addReg(AMDGPU::EXEC)
    .addReg(NewExec);

  // XXX - s_xor_b64 sets scc to 1 if the result is nonzero, so can we use
  // s_cbranch_scc0?

  // Loop back to V_READFIRSTLANE_B32 if there are still variants to cover.
  B.buildInstr(AMDGPU::S_CBRANCH_EXECNZ)
    .addMBB(LoopBB);

  // Save the EXEC mask before the loop.
  BuildMI(MBB, MBB.end(), DL, TII->get(AMDGPU::S_MOV_B64_term), SaveExecReg)
    .addReg(AMDGPU::EXEC);

  // Restore the EXEC mask after the loop.
  B.setMBB(*RestoreExecBB);
  B.buildInstr(AMDGPU::S_MOV_B64_term)
    .addDef(AMDGPU::EXEC)
    .addReg(SaveExecReg);
}

void AMDGPURegisterBankInfo::applyMappingImpl(
    const OperandsMapper &OpdMapper) const {
  MachineInstr &MI = OpdMapper.getMI();
  unsigned Opc = MI.getOpcode();
  MachineRegisterInfo &MRI = OpdMapper.getMRI();
  switch (Opc) {
  case AMDGPU::G_SELECT: {
    unsigned DstReg = MI.getOperand(0).getReg();
    LLT DstTy = MRI.getType(DstReg);
    if (DstTy.getSizeInBits() != 64)
      break;

    LLT HalfTy = getHalfSizedType(DstTy);

    SmallVector<Register, 2> DefRegs(OpdMapper.getVRegs(0));
    SmallVector<Register, 1> Src0Regs(OpdMapper.getVRegs(1));
    SmallVector<Register, 2> Src1Regs(OpdMapper.getVRegs(2));
    SmallVector<Register, 2> Src2Regs(OpdMapper.getVRegs(3));

    // All inputs are SGPRs, nothing special to do.
    if (DefRegs.empty()) {
      assert(Src1Regs.empty() && Src2Regs.empty());
      break;
    }

    MachineIRBuilder B(MI);
    if (Src0Regs.empty())
      Src0Regs.push_back(MI.getOperand(1).getReg());
    else {
      assert(Src0Regs.size() == 1);
    }

    if (Src1Regs.empty())
      split64BitValueForMapping(B, Src1Regs, HalfTy, MI.getOperand(2).getReg());
    else {
      setRegsToType(MRI, Src1Regs, HalfTy);
    }

    if (Src2Regs.empty())
      split64BitValueForMapping(B, Src2Regs, HalfTy, MI.getOperand(3).getReg());
    else
      setRegsToType(MRI, Src2Regs, HalfTy);

    setRegsToType(MRI, DefRegs, HalfTy);

    B.buildSelect(DefRegs[0], Src0Regs[0], Src1Regs[0], Src2Regs[0]);
    B.buildSelect(DefRegs[1], Src0Regs[0], Src1Regs[1], Src2Regs[1]);

    MRI.setRegBank(DstReg, getRegBank(AMDGPU::VGPRRegBankID));
    MI.eraseFromParent();
    return;
  }
  case AMDGPU::G_AND:
  case AMDGPU::G_OR:
  case AMDGPU::G_XOR: {
    // 64-bit and is only available on the SALU, so split into 2 32-bit ops if
    // there is a VGPR input.
    unsigned DstReg = MI.getOperand(0).getReg();
    LLT DstTy = MRI.getType(DstReg);
    if (DstTy.getSizeInBits() != 64)
      break;

    LLT HalfTy = getHalfSizedType(DstTy);
    SmallVector<Register, 2> DefRegs(OpdMapper.getVRegs(0));
    SmallVector<Register, 2> Src0Regs(OpdMapper.getVRegs(1));
    SmallVector<Register, 2> Src1Regs(OpdMapper.getVRegs(2));

    // All inputs are SGPRs, nothing special to do.
    if (DefRegs.empty()) {
      assert(Src0Regs.empty() && Src1Regs.empty());
      break;
    }

    assert(DefRegs.size() == 2);
    assert(Src0Regs.size() == Src1Regs.size() &&
           (Src0Regs.empty() || Src0Regs.size() == 2));

    // Depending on where the source registers came from, the generic code may
    // have decided to split the inputs already or not. If not, we still need to
    // extract the values.
    MachineIRBuilder B(MI);

    if (Src0Regs.empty())
      split64BitValueForMapping(B, Src0Regs, HalfTy, MI.getOperand(1).getReg());
    else
      setRegsToType(MRI, Src0Regs, HalfTy);

    if (Src1Regs.empty())
      split64BitValueForMapping(B, Src1Regs, HalfTy, MI.getOperand(2).getReg());
    else
      setRegsToType(MRI, Src1Regs, HalfTy);

    setRegsToType(MRI, DefRegs, HalfTy);

    B.buildInstr(Opc)
      .addDef(DefRegs[0])
      .addUse(Src0Regs[0])
      .addUse(Src1Regs[0]);

    B.buildInstr(Opc)
      .addDef(DefRegs[1])
      .addUse(Src0Regs[1])
      .addUse(Src1Regs[1]);

    MRI.setRegBank(DstReg, getRegBank(AMDGPU::VGPRRegBankID));
    MI.eraseFromParent();
    return;
  }
  case AMDGPU::G_SEXT:
  case AMDGPU::G_ZEXT: {
    Register SrcReg = MI.getOperand(1).getReg();
    LLT SrcTy = MRI.getType(SrcReg);
    bool Signed = Opc == AMDGPU::G_SEXT;

    MachineIRBuilder B(MI);
    const RegisterBank *SrcBank = getRegBank(SrcReg, MRI, *TRI);

    Register DstReg = MI.getOperand(0).getReg();
    LLT DstTy = MRI.getType(DstReg);
    if (DstTy.isScalar() &&
        SrcBank != &AMDGPU::SGPRRegBank &&
        SrcBank != &AMDGPU::SCCRegBank &&
        SrcBank != &AMDGPU::VCCRegBank &&
        // FIXME: Should handle any type that round to s64 when irregular
        // breakdowns supported.
        DstTy.getSizeInBits() == 64 &&
        SrcTy.getSizeInBits() <= 32) {
      const LLT S32 = LLT::scalar(32);
      SmallVector<Register, 2> DefRegs(OpdMapper.getVRegs(0));

      // Extend to 32-bit, and then extend the low half.
      if (Signed) {
        // TODO: Should really be buildSExtOrCopy
        B.buildSExtOrTrunc(DefRegs[0], SrcReg);

        // Replicate sign bit from 32-bit extended part.
        auto ShiftAmt = B.buildConstant(S32, 31);
        MRI.setRegBank(ShiftAmt.getReg(0), *SrcBank);
        B.buildAShr(DefRegs[1], DefRegs[0], ShiftAmt);
      } else {
        B.buildZExtOrTrunc(DefRegs[0], SrcReg);
        B.buildConstant(DefRegs[1], 0);
      }

      MRI.setRegBank(DstReg, *SrcBank);
      MI.eraseFromParent();
      return;
    }

    if (SrcTy != LLT::scalar(1))
      return;

    if (SrcBank == &AMDGPU::SCCRegBank || SrcBank == &AMDGPU::VCCRegBank) {
      SmallVector<Register, 2> DefRegs(OpdMapper.getVRegs(0));

      const RegisterBank *DstBank = SrcBank == &AMDGPU::SCCRegBank ?
        &AMDGPU::SGPRRegBank : &AMDGPU::VGPRRegBank;

      unsigned DstSize = DstTy.getSizeInBits();
      // 64-bit select is SGPR only
      const bool UseSel64 = DstSize > 32 &&
        SrcBank->getID() == AMDGPU::SCCRegBankID;

      // TODO: Should s16 select be legal?
      LLT SelType = UseSel64 ? LLT::scalar(64) : LLT::scalar(32);
      auto True = B.buildConstant(SelType, Signed ? -1 : 1);
      auto False = B.buildConstant(SelType, 0);

      MRI.setRegBank(True.getReg(0), *DstBank);
      MRI.setRegBank(False.getReg(0), *DstBank);
      MRI.setRegBank(DstReg, *DstBank);

      if (DstSize > 32 && SrcBank->getID() != AMDGPU::SCCRegBankID) {
        B.buildSelect(DefRegs[0], SrcReg, True, False);
        B.buildCopy(DefRegs[1], DefRegs[0]);
      } else if (DstSize < 32) {
        auto Sel = B.buildSelect(SelType, SrcReg, True, False);
        MRI.setRegBank(Sel.getReg(0), *DstBank);
        B.buildTrunc(DstReg, Sel);
      } else {
        B.buildSelect(DstReg, SrcReg, True, False);
      }

      MI.eraseFromParent();
      return;
    }

    // Fixup the case with an s1 src that isn't a condition register. Use shifts
    // instead of introducing a compare to avoid an unnecessary condition
    // register (and since there's no scalar 16-bit compares).
    auto Ext = B.buildAnyExt(DstTy, SrcReg);
    auto ShiftAmt = B.buildConstant(LLT::scalar(32), DstTy.getSizeInBits() - 1);
    auto Shl = B.buildShl(DstTy, Ext, ShiftAmt);

    if (MI.getOpcode() == AMDGPU::G_SEXT)
      B.buildAShr(DstReg, Shl, ShiftAmt);
    else
      B.buildLShr(DstReg, Shl, ShiftAmt);

    MRI.setRegBank(DstReg, *SrcBank);
    MRI.setRegBank(Ext.getReg(0), *SrcBank);
    MRI.setRegBank(ShiftAmt.getReg(0), *SrcBank);
    MRI.setRegBank(Shl.getReg(0), *SrcBank);
    MI.eraseFromParent();
    return;
  }
  case AMDGPU::G_EXTRACT_VECTOR_ELT:
    applyDefaultMapping(OpdMapper);
    executeInWaterfallLoop(MI, MRI, { 2 });
    return;
  case AMDGPU::G_INTRINSIC: {
    switch (MI.getOperand(MI.getNumExplicitDefs()).getIntrinsicID()) {
    case Intrinsic::amdgcn_s_buffer_load: {
      // FIXME: Move to G_INTRINSIC_W_SIDE_EFFECTS
      executeInWaterfallLoop(MI, MRI, { 2, 3 });
      return;
    }
    default:
      break;
    }
    break;
  }
  case AMDGPU::G_INTRINSIC_W_SIDE_EFFECTS: {
    switch (MI.getOperand(MI.getNumExplicitDefs()).getIntrinsicID()) {
    case Intrinsic::amdgcn_buffer_load: {
      executeInWaterfallLoop(MI, MRI, { 2 });
      return;
    }
    default:
      break;
    }
    break;
  }
  default:
    break;
  }

  return applyDefaultMapping(OpdMapper);
}

static bool isInstrUniform(const MachineInstr &MI) {
  if (!MI.hasOneMemOperand())
    return false;

  const MachineMemOperand *MMO = *MI.memoperands_begin();
  return AMDGPUInstrInfo::isUniformMMO(MMO);
}

bool AMDGPURegisterBankInfo::isSALUMapping(const MachineInstr &MI) const {
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  for (unsigned i = 0, e = MI.getNumOperands();i != e; ++i) {
    if (!MI.getOperand(i).isReg())
      continue;
    unsigned Reg = MI.getOperand(i).getReg();
    if (const RegisterBank *Bank = getRegBank(Reg, MRI, *TRI)) {
      if (Bank->getID() == AMDGPU::VGPRRegBankID)
        return false;

      assert(Bank->getID() == AMDGPU::SGPRRegBankID ||
             Bank->getID() == AMDGPU::SCCRegBankID);
    }
  }
  return true;
}

const RegisterBankInfo::InstructionMapping &
AMDGPURegisterBankInfo::getDefaultMappingSOP(const MachineInstr &MI) const {
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  SmallVector<const ValueMapping*, 8> OpdsMapping(MI.getNumOperands());

  for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
    unsigned Size = getSizeInBits(MI.getOperand(i).getReg(), MRI, *TRI);
    unsigned BankID = Size == 1 ? AMDGPU::SCCRegBankID : AMDGPU::SGPRRegBankID;
    OpdsMapping[i] = AMDGPU::getValueMapping(BankID, Size);
  }
  return getInstructionMapping(1, 1, getOperandsMapping(OpdsMapping),
                               MI.getNumOperands());
}

const RegisterBankInfo::InstructionMapping &
AMDGPURegisterBankInfo::getDefaultMappingVOP(const MachineInstr &MI) const {
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  SmallVector<const ValueMapping*, 8> OpdsMapping(MI.getNumOperands());
  unsigned OpdIdx = 0;

  unsigned Size0 = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
  OpdsMapping[OpdIdx++] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size0);

  if (MI.getOperand(OpdIdx).isIntrinsicID())
    OpdsMapping[OpdIdx++] = nullptr;

  unsigned Reg1 = MI.getOperand(OpdIdx).getReg();
  unsigned Size1 = getSizeInBits(Reg1, MRI, *TRI);

  unsigned DefaultBankID = Size1 == 1 ?
    AMDGPU::VCCRegBankID : AMDGPU::VGPRRegBankID;
  unsigned Bank1 = getRegBankID(Reg1, MRI, *TRI, DefaultBankID);

  OpdsMapping[OpdIdx++] = AMDGPU::getValueMapping(Bank1, Size1);

  for (unsigned e = MI.getNumOperands(); OpdIdx != e; ++OpdIdx) {
    const MachineOperand &MO = MI.getOperand(OpdIdx);
    if (!MO.isReg())
      continue;

    unsigned Size = getSizeInBits(MO.getReg(), MRI, *TRI);
    unsigned BankID = Size == 1 ? AMDGPU::VCCRegBankID : AMDGPU::VGPRRegBankID;
    OpdsMapping[OpdIdx] = AMDGPU::getValueMapping(BankID, Size);
  }

  return getInstructionMapping(1, 1, getOperandsMapping(OpdsMapping),
                               MI.getNumOperands());
}

const RegisterBankInfo::InstructionMapping &
AMDGPURegisterBankInfo::getDefaultMappingAllVGPR(const MachineInstr &MI) const {
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  SmallVector<const ValueMapping*, 8> OpdsMapping(MI.getNumOperands());

  for (unsigned I = 0, E = MI.getNumOperands(); I != E; ++I) {
    unsigned Size = getSizeInBits(MI.getOperand(I).getReg(), MRI, *TRI);
    OpdsMapping[I] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size);
  }

  return getInstructionMapping(1, 1, getOperandsMapping(OpdsMapping),
                               MI.getNumOperands());
}

const RegisterBankInfo::InstructionMapping &
AMDGPURegisterBankInfo::getInstrMappingForLoad(const MachineInstr &MI) const {

  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  SmallVector<const ValueMapping*, 8> OpdsMapping(MI.getNumOperands());
  unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
  unsigned PtrSize = getSizeInBits(MI.getOperand(1).getReg(), MRI, *TRI);

  const ValueMapping *ValMapping;
  const ValueMapping *PtrMapping;

  if (isInstrUniform(MI)) {
    // We have a uniform instruction so we want to use an SMRD load
    ValMapping = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
    PtrMapping = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, PtrSize);
  } else {
    ValMapping = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size);
    // FIXME: What would happen if we used SGPRRegBankID here?
    PtrMapping = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, PtrSize);
  }

  OpdsMapping[0] = ValMapping;
  OpdsMapping[1] = PtrMapping;
  const RegisterBankInfo::InstructionMapping &Mapping = getInstructionMapping(
      1, 1, getOperandsMapping(OpdsMapping), MI.getNumOperands());
  return Mapping;

  // FIXME: Do we want to add a mapping for FLAT load, or should we just
  // handle that during instruction selection?
}

unsigned
AMDGPURegisterBankInfo::getRegBankID(unsigned Reg,
                                     const MachineRegisterInfo &MRI,
                                     const TargetRegisterInfo &TRI,
                                     unsigned Default) const {

  const RegisterBank *Bank = getRegBank(Reg, MRI, TRI);
  return Bank ? Bank->getID() : Default;
}

///
/// This function must return a legal mapping, because
/// AMDGPURegisterBankInfo::getInstrAlternativeMappings() is not called
/// in RegBankSelect::Mode::Fast.  Any mapping that would cause a
/// VGPR to SGPR generated is illegal.
///
const RegisterBankInfo::InstructionMapping &
AMDGPURegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();

  if (MI.isRegSequence()) {
    // If any input is a VGPR, the result must be a VGPR. The default handling
    // assumes any copy between banks is legal.
    unsigned BankID = AMDGPU::SGPRRegBankID;

    for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
      auto OpBank = getRegBankID(MI.getOperand(I).getReg(), MRI, *TRI);
      // It doesn't make sense to use vcc or scc banks here, so just ignore
      // them.
      if (OpBank != AMDGPU::SGPRRegBankID) {
        BankID = AMDGPU::VGPRRegBankID;
        break;
      }
    }
    unsigned Size = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);

    const ValueMapping &ValMap = getValueMapping(0, Size, getRegBank(BankID));
    return getInstructionMapping(
        1, /*Cost*/ 1,
        /*OperandsMapping*/ getOperandsMapping({&ValMap}), 1);
  }

  // The default handling is broken and doesn't handle illegal SGPR->VGPR copies
  // properly.
  //
  // TODO: There are additional exec masking dependencies to analyze.
  if (MI.getOpcode() == TargetOpcode::G_PHI) {
    // TODO: Generate proper invalid bank enum.
    int ResultBank = -1;

    for (unsigned I = 1, E = MI.getNumOperands(); I != E; I += 2) {
      unsigned Reg = MI.getOperand(I).getReg();
      const RegisterBank *Bank = getRegBank(Reg, MRI, *TRI);

      // FIXME: Assuming VGPR for any undetermined inputs.
      if (!Bank || Bank->getID() == AMDGPU::VGPRRegBankID) {
        ResultBank = AMDGPU::VGPRRegBankID;
        break;
      }

      unsigned OpBank = Bank->getID();
      // scc, scc -> sgpr
      if (OpBank == AMDGPU::SCCRegBankID) {
        // There's only one SCC register, so a phi requires copying to SGPR.
        OpBank = AMDGPU::SGPRRegBankID;
      } else if (OpBank == AMDGPU::VCCRegBankID) {
        // vcc, vcc -> vcc
        // vcc, sgpr -> vgpr
        if (ResultBank != -1 && ResultBank != AMDGPU::VCCRegBankID) {
          ResultBank = AMDGPU::VGPRRegBankID;
          break;
        }
      }

      ResultBank = OpBank;
    }

    assert(ResultBank != -1);

    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();

    const ValueMapping &ValMap =
        getValueMapping(0, Size, getRegBank(ResultBank));
    return getInstructionMapping(
        1, /*Cost*/ 1,
        /*OperandsMapping*/ getOperandsMapping({&ValMap}), 1);
  }

  const RegisterBankInfo::InstructionMapping &Mapping = getInstrMappingImpl(MI);
  if (Mapping.isValid())
    return Mapping;

  SmallVector<const ValueMapping*, 8> OpdsMapping(MI.getNumOperands());

  switch (MI.getOpcode()) {
  default:
    return getInvalidInstructionMapping();

  case AMDGPU::G_AND:
  case AMDGPU::G_OR:
  case AMDGPU::G_XOR: {
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    if (Size == 1) {
      OpdsMapping[0] = OpdsMapping[1] =
        OpdsMapping[2] = AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, Size);
      break;
    }

    if (Size == 64) {

      if (isSALUMapping(MI)) {
        OpdsMapping[0] = getValueMappingSGPR64Only(AMDGPU::SGPRRegBankID, Size);
        OpdsMapping[1] = OpdsMapping[2] = OpdsMapping[0];
      } else {
        OpdsMapping[0] = getValueMappingSGPR64Only(AMDGPU::VGPRRegBankID, Size);
        unsigned Bank1 = getRegBankID(MI.getOperand(1).getReg(), MRI, *TRI/*, DefaultBankID*/);
        OpdsMapping[1] = AMDGPU::getValueMapping(Bank1, Size);

        unsigned Bank2 = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI/*, DefaultBankID*/);
        OpdsMapping[2] = AMDGPU::getValueMapping(Bank2, Size);
      }

      break;
    }

    LLVM_FALLTHROUGH;
  }

  case AMDGPU::G_GEP:
  case AMDGPU::G_ADD:
  case AMDGPU::G_SUB:
  case AMDGPU::G_MUL:
  case AMDGPU::G_SHL:
  case AMDGPU::G_LSHR:
  case AMDGPU::G_ASHR:
  case AMDGPU::G_UADDO:
  case AMDGPU::G_SADDO:
  case AMDGPU::G_USUBO:
  case AMDGPU::G_SSUBO:
  case AMDGPU::G_UADDE:
  case AMDGPU::G_SADDE:
  case AMDGPU::G_USUBE:
  case AMDGPU::G_SSUBE:
  case AMDGPU::G_UMULH:
  case AMDGPU::G_SMULH:
    if (isSALUMapping(MI))
      return getDefaultMappingSOP(MI);
    LLVM_FALLTHROUGH;

  case AMDGPU::G_SMIN:
  case AMDGPU::G_SMAX:
  case AMDGPU::G_UMIN:
  case AMDGPU::G_UMAX:
    // TODO: min/max can be scalar, but requires expanding as a compare and
    // select.

  case AMDGPU::G_FADD:
  case AMDGPU::G_FSUB:
  case AMDGPU::G_FPTOSI:
  case AMDGPU::G_FPTOUI:
  case AMDGPU::G_FMUL:
  case AMDGPU::G_FMA:
  case AMDGPU::G_FSQRT:
  case AMDGPU::G_SITOFP:
  case AMDGPU::G_UITOFP:
  case AMDGPU::G_FPTRUNC:
  case AMDGPU::G_FPEXT:
  case AMDGPU::G_FEXP2:
  case AMDGPU::G_FLOG2:
  case AMDGPU::G_INTRINSIC_TRUNC:
  case AMDGPU::G_INTRINSIC_ROUND:
    return getDefaultMappingVOP(MI);
  case AMDGPU::G_IMPLICIT_DEF: {
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
    break;
  }
  case AMDGPU::G_FCONSTANT:
  case AMDGPU::G_CONSTANT:
  case AMDGPU::G_FRAME_INDEX:
  case AMDGPU::G_BLOCK_ADDR: {
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
    break;
  }
  case AMDGPU::G_INSERT: {
    unsigned BankID = isSALUMapping(MI) ? AMDGPU::SGPRRegBankID :
                                          AMDGPU::VGPRRegBankID;
    unsigned DstSize = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    unsigned SrcSize = getSizeInBits(MI.getOperand(1).getReg(), MRI, *TRI);
    unsigned EltSize = getSizeInBits(MI.getOperand(2).getReg(), MRI, *TRI);
    OpdsMapping[0] = AMDGPU::getValueMapping(BankID, DstSize);
    OpdsMapping[1] = AMDGPU::getValueMapping(BankID, SrcSize);
    OpdsMapping[2] = AMDGPU::getValueMapping(BankID, EltSize);
    OpdsMapping[3] = nullptr;
    break;
  }
  case AMDGPU::G_EXTRACT: {
    unsigned BankID = getRegBankID(MI.getOperand(1).getReg(), MRI, *TRI);
    unsigned DstSize = getSizeInBits(MI.getOperand(0).getReg(), MRI, *TRI);
    unsigned SrcSize = getSizeInBits(MI.getOperand(1).getReg(), MRI, *TRI);
    OpdsMapping[0] = AMDGPU::getValueMapping(BankID, DstSize);
    OpdsMapping[1] = AMDGPU::getValueMapping(BankID, SrcSize);
    OpdsMapping[2] = nullptr;
    break;
  }
  case AMDGPU::G_MERGE_VALUES: {
    unsigned Bank = isSALUMapping(MI) ?
      AMDGPU::SGPRRegBankID : AMDGPU::VGPRRegBankID;
    unsigned DstSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    unsigned SrcSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();

    OpdsMapping[0] = AMDGPU::getValueMapping(Bank, DstSize);
    // Op1 and Dst should use the same register bank.
    for (unsigned i = 1, e = MI.getNumOperands(); i != e; ++i)
      OpdsMapping[i] = AMDGPU::getValueMapping(Bank, SrcSize);
    break;
  }
  case AMDGPU::G_BITCAST:
  case AMDGPU::G_INTTOPTR:
  case AMDGPU::G_PTRTOINT:
  case AMDGPU::G_CTLZ:
  case AMDGPU::G_CTLZ_ZERO_UNDEF:
  case AMDGPU::G_CTTZ:
  case AMDGPU::G_CTTZ_ZERO_UNDEF:
  case AMDGPU::G_CTPOP:
  case AMDGPU::G_BSWAP:
  case AMDGPU::G_FABS:
  case AMDGPU::G_FNEG: {
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    unsigned BankID = getRegBankID(MI.getOperand(1).getReg(), MRI, *TRI);
    OpdsMapping[0] = OpdsMapping[1] = AMDGPU::getValueMapping(BankID, Size);
    break;
  }
  case AMDGPU::G_TRUNC: {
    unsigned Dst = MI.getOperand(0).getReg();
    unsigned Src = MI.getOperand(1).getReg();
    unsigned Bank = getRegBankID(Src, MRI, *TRI);
    unsigned DstSize = getSizeInBits(Dst, MRI, *TRI);
    unsigned SrcSize = getSizeInBits(Src, MRI, *TRI);
    OpdsMapping[0] = AMDGPU::getValueMapping(Bank, DstSize);
    OpdsMapping[1] = AMDGPU::getValueMapping(Bank, SrcSize);
    break;
  }
  case AMDGPU::G_ZEXT:
  case AMDGPU::G_SEXT:
  case AMDGPU::G_ANYEXT: {
    unsigned Dst = MI.getOperand(0).getReg();
    unsigned Src = MI.getOperand(1).getReg();
    unsigned DstSize = getSizeInBits(Dst, MRI, *TRI);
    unsigned SrcSize = getSizeInBits(Src, MRI, *TRI);

    unsigned DstBank;
    const RegisterBank *SrcBank = getRegBank(Src, MRI, *TRI);
    assert(SrcBank);
    switch (SrcBank->getID()) {
    case AMDGPU::SCCRegBankID:
    case AMDGPU::SGPRRegBankID:
      DstBank = AMDGPU::SGPRRegBankID;
      break;
    default:
      DstBank = AMDGPU::VGPRRegBankID;
      break;
    }

    // TODO: Should anyext be split into 32-bit part as well?
    if (MI.getOpcode() == AMDGPU::G_ANYEXT) {
      OpdsMapping[0] = AMDGPU::getValueMapping(DstBank, DstSize);
      OpdsMapping[1] = AMDGPU::getValueMapping(SrcBank->getID(), SrcSize);
    } else {
      // Scalar extend can use 64-bit BFE, but VGPRs require extending to
      // 32-bits, and then to 64.
      OpdsMapping[0] = AMDGPU::getValueMappingSGPR64Only(DstBank, DstSize);
      OpdsMapping[1] = AMDGPU::getValueMappingSGPR64Only(SrcBank->getID(),
                                                         SrcSize);
    }
    break;
  }
  case AMDGPU::G_FCMP: {
    unsigned Size = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
    unsigned Op2Bank = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI);
    OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, 1);
    OpdsMapping[1] = nullptr; // Predicate Operand.
    OpdsMapping[2] = AMDGPU::getValueMapping(Op2Bank, Size);
    OpdsMapping[3] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size);
    break;
  }
  case AMDGPU::G_STORE: {
    assert(MI.getOperand(0).isReg());
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    // FIXME: We need to specify a different reg bank once scalar stores
    // are supported.
    const ValueMapping *ValMapping =
        AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size);
    // FIXME: Depending on the type of store, the pointer could be in
    // the SGPR Reg bank.
    // FIXME: Pointer size should be based on the address space.
    const ValueMapping *PtrMapping =
        AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 64);

    OpdsMapping[0] = ValMapping;
    OpdsMapping[1] = PtrMapping;
    break;
  }

  case AMDGPU::G_ICMP: {
    unsigned Size = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
    unsigned Op2Bank = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI);
    unsigned Op3Bank = getRegBankID(MI.getOperand(3).getReg(), MRI, *TRI);
    unsigned Op0Bank = Op2Bank == AMDGPU::SGPRRegBankID &&
                       Op3Bank == AMDGPU::SGPRRegBankID ?
                       AMDGPU::SCCRegBankID : AMDGPU::VCCRegBankID;
    OpdsMapping[0] = AMDGPU::getValueMapping(Op0Bank, 1);
    OpdsMapping[1] = nullptr; // Predicate Operand.
    OpdsMapping[2] = AMDGPU::getValueMapping(Op2Bank, Size);
    OpdsMapping[3] = AMDGPU::getValueMapping(Op3Bank, Size);
    break;
  }


  case AMDGPU::G_EXTRACT_VECTOR_ELT: {
    unsigned OutputBankID = isSALUMapping(MI) ?
                            AMDGPU::SGPRRegBankID : AMDGPU::VGPRRegBankID;
    unsigned SrcSize = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
    unsigned IdxSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
    unsigned IdxBank = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI);

    OpdsMapping[0] = AMDGPU::getValueMapping(OutputBankID, SrcSize);
    OpdsMapping[1] = AMDGPU::getValueMapping(OutputBankID, SrcSize);

    // The index can be either if the source vector is VGPR.
    OpdsMapping[2] = AMDGPU::getValueMapping(IdxBank, IdxSize);
    break;
  }
  case AMDGPU::G_INSERT_VECTOR_ELT: {
    unsigned OutputBankID = isSALUMapping(MI) ?
      AMDGPU::SGPRRegBankID : AMDGPU::VGPRRegBankID;

    unsigned VecSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    unsigned InsertSize = MRI.getType(MI.getOperand(2).getReg()).getSizeInBits();
    unsigned IdxSize = MRI.getType(MI.getOperand(3).getReg()).getSizeInBits();
    unsigned InsertEltBank = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI);
    unsigned IdxBank = getRegBankID(MI.getOperand(3).getReg(), MRI, *TRI);

    OpdsMapping[0] = AMDGPU::getValueMapping(OutputBankID, VecSize);
    OpdsMapping[1] = AMDGPU::getValueMapping(OutputBankID, VecSize);
    OpdsMapping[2] = AMDGPU::getValueMapping(InsertEltBank, InsertSize);

    // The index can be either if the source vector is VGPR.
    OpdsMapping[3] = AMDGPU::getValueMapping(IdxBank, IdxSize);
    break;
  }
  case AMDGPU::G_UNMERGE_VALUES: {
    unsigned Bank = isSALUMapping(MI) ? AMDGPU::SGPRRegBankID :
      AMDGPU::VGPRRegBankID;

    // Op1 and Dst should use the same register bank.
    // FIXME: Shouldn't this be the default? Why do we need to handle this?
    for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) {
      unsigned Size = getSizeInBits(MI.getOperand(i).getReg(), MRI, *TRI);
      OpdsMapping[i] = AMDGPU::getValueMapping(Bank, Size);
    }
    break;
  }
  case AMDGPU::G_INTRINSIC: {
    switch (MI.getOperand(MI.getNumExplicitDefs()).getIntrinsicID()) {
    default:
      return getInvalidInstructionMapping();
    case Intrinsic::maxnum:
    case Intrinsic::minnum:
    case Intrinsic::amdgcn_cvt_pkrtz:
      return getDefaultMappingVOP(MI);
    case Intrinsic::amdgcn_kernarg_segment_ptr: {
      unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
      break;
    }
    case Intrinsic::amdgcn_wqm_vote: {
      unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      OpdsMapping[0] = OpdsMapping[2]
        = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size);
      break;
    }
    case Intrinsic::amdgcn_s_buffer_load: {
      // FIXME: This should be moved to G_INTRINSIC_W_SIDE_EFFECTS
      unsigned RSrc = MI.getOperand(2).getReg();   // SGPR
      unsigned Offset = MI.getOperand(3).getReg(); // SGPR/imm

      unsigned Size0 = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      unsigned Size2 = MRI.getType(RSrc).getSizeInBits();
      unsigned Size3 = MRI.getType(Offset).getSizeInBits();

      unsigned RSrcBank = getRegBankID(RSrc, MRI, *TRI);
      unsigned OffsetBank = getRegBankID(Offset, MRI, *TRI);

      OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, Size0);
      OpdsMapping[1] = nullptr; // intrinsic id

      // Lie and claim everything is legal, even though some need to be
      // SGPRs. applyMapping will have to deal with it as a waterfall loop.
      OpdsMapping[2] = AMDGPU::getValueMapping(RSrcBank, Size2); // rsrc
      OpdsMapping[3] = AMDGPU::getValueMapping(OffsetBank, Size3);
      OpdsMapping[4] = nullptr;
      break;
    }
    case Intrinsic::amdgcn_div_scale: {
      unsigned Dst0Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      unsigned Dst1Size = MRI.getType(MI.getOperand(1).getReg()).getSizeInBits();
      OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Dst0Size);
      OpdsMapping[1] = AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, Dst1Size);

      unsigned SrcSize = MRI.getType(MI.getOperand(3).getReg()).getSizeInBits();
      OpdsMapping[3] = AMDGPU::getValueMapping(
        getRegBankID(MI.getOperand(3).getReg(), MRI, *TRI), SrcSize);
      OpdsMapping[4] = AMDGPU::getValueMapping(
        getRegBankID(MI.getOperand(4).getReg(), MRI, *TRI), SrcSize);

      break;
    }
    case Intrinsic::amdgcn_class: {
      unsigned Src0Reg = MI.getOperand(2).getReg();
      unsigned Src1Reg = MI.getOperand(3).getReg();
      unsigned Src0Size = MRI.getType(Src0Reg).getSizeInBits();
      unsigned Src1Size = MRI.getType(Src1Reg).getSizeInBits();
      unsigned DstSize = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::VCCRegBankID, DstSize);
      OpdsMapping[2] = AMDGPU::getValueMapping(getRegBankID(Src0Reg, MRI, *TRI),
                                               Src0Size);
      OpdsMapping[3] = AMDGPU::getValueMapping(getRegBankID(Src1Reg, MRI, *TRI),
                                               Src1Size);
      break;
    }
    }
    break;
  }
  case AMDGPU::G_INTRINSIC_W_SIDE_EFFECTS: {
    switch (MI.getOperand(MI.getNumExplicitDefs()).getIntrinsicID()) {
    default:
      return getInvalidInstructionMapping();
    case Intrinsic::amdgcn_exp_compr:
      OpdsMapping[0] = nullptr; // IntrinsicID
      // FIXME: These are immediate values which can't be read from registers.
      OpdsMapping[1] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      OpdsMapping[2] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      // FIXME: Could we support packed types here?
      OpdsMapping[3] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      OpdsMapping[4] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      // FIXME: These are immediate values which can't be read from registers.
      OpdsMapping[5] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      OpdsMapping[6] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      break;
    case Intrinsic::amdgcn_exp:
      OpdsMapping[0] = nullptr; // IntrinsicID
      // FIXME: These are immediate values which can't be read from registers.
      OpdsMapping[1] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      OpdsMapping[2] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      // FIXME: Could we support packed types here?
      OpdsMapping[3] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      OpdsMapping[4] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      OpdsMapping[5] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      OpdsMapping[6] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, 32);
      // FIXME: These are immediate values which can't be read from registers.
      OpdsMapping[7] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      OpdsMapping[8] = AMDGPU::getValueMapping(AMDGPU::SGPRRegBankID, 32);
      break;
    case Intrinsic::amdgcn_buffer_load: {
      unsigned RSrc = MI.getOperand(2).getReg();   // SGPR
      unsigned VIndex = MI.getOperand(3).getReg(); // VGPR
      unsigned Offset = MI.getOperand(4).getReg(); // SGPR/VGPR/imm

      unsigned Size0 = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
      unsigned Size2 = MRI.getType(RSrc).getSizeInBits();
      unsigned Size3 = MRI.getType(VIndex).getSizeInBits();
      unsigned Size4 = MRI.getType(Offset).getSizeInBits();

      unsigned RSrcBank = getRegBankID(RSrc, MRI, *TRI);
      unsigned OffsetBank = getRegBankID(Offset, MRI, *TRI);

      OpdsMapping[0] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size0);
      OpdsMapping[1] = nullptr; // intrinsic id

      // Lie and claim everything is legal, even though some need to be
      // SGPRs. applyMapping will have to deal with it as a waterfall loop.
      OpdsMapping[2] = AMDGPU::getValueMapping(RSrcBank, Size2); // rsrc
      OpdsMapping[3] = AMDGPU::getValueMapping(AMDGPU::VGPRRegBankID, Size3);
      OpdsMapping[4] = AMDGPU::getValueMapping(OffsetBank, Size4);
      OpdsMapping[5] = nullptr;
      OpdsMapping[6] = nullptr;
      break;
    }
    }

    break;
  }
  case AMDGPU::G_SELECT: {
    unsigned Size = MRI.getType(MI.getOperand(0).getReg()).getSizeInBits();
    unsigned Op1Bank = getRegBankID(MI.getOperand(1).getReg(), MRI, *TRI,
                                    AMDGPU::SGPRRegBankID);
    unsigned Op2Bank = getRegBankID(MI.getOperand(2).getReg(), MRI, *TRI);
    unsigned Op3Bank = getRegBankID(MI.getOperand(3).getReg(), MRI, *TRI);
    bool SGPRSrcs = Op1Bank == AMDGPU::SCCRegBankID &&
                    Op2Bank == AMDGPU::SGPRRegBankID &&
                    Op3Bank == AMDGPU::SGPRRegBankID;
    unsigned Bank = SGPRSrcs ? AMDGPU::SGPRRegBankID : AMDGPU::VGPRRegBankID;
    Op1Bank = SGPRSrcs ? AMDGPU::SCCRegBankID : AMDGPU::VCCRegBankID;

    if (Size == 64) {
      OpdsMapping[0] = AMDGPU::getValueMappingSGPR64Only(Bank, Size);
      OpdsMapping[1] = AMDGPU::getValueMapping(Op1Bank, 1);
      OpdsMapping[2] = AMDGPU::getValueMappingSGPR64Only(Bank, Size);
      OpdsMapping[3] = AMDGPU::getValueMappingSGPR64Only(Bank, Size);
    } else {
      OpdsMapping[0] = AMDGPU::getValueMapping(Bank, Size);
      OpdsMapping[1] = AMDGPU::getValueMapping(Op1Bank, 1);
      OpdsMapping[2] = AMDGPU::getValueMapping(Bank, Size);
      OpdsMapping[3] = AMDGPU::getValueMapping(Bank, Size);
    }

    break;
  }

  case AMDGPU::G_LOAD:
    return getInstrMappingForLoad(MI);

  case AMDGPU::G_ATOMICRMW_XCHG:
  case AMDGPU::G_ATOMICRMW_ADD:
  case AMDGPU::G_ATOMICRMW_SUB:
  case AMDGPU::G_ATOMICRMW_AND:
  case AMDGPU::G_ATOMICRMW_OR:
  case AMDGPU::G_ATOMICRMW_XOR:
  case AMDGPU::G_ATOMICRMW_MAX:
  case AMDGPU::G_ATOMICRMW_MIN:
  case AMDGPU::G_ATOMICRMW_UMAX:
  case AMDGPU::G_ATOMICRMW_UMIN:
  case AMDGPU::G_ATOMIC_CMPXCHG: {
    return getDefaultMappingAllVGPR(MI);
  }
  case AMDGPU::G_BRCOND: {
    unsigned Bank = getRegBankID(MI.getOperand(0).getReg(), MRI, *TRI,
                                 AMDGPU::SGPRRegBankID);
    assert(MRI.getType(MI.getOperand(0).getReg()).getSizeInBits() == 1);
    if (Bank != AMDGPU::SCCRegBankID)
      Bank = AMDGPU::VCCRegBankID;

    OpdsMapping[0] = AMDGPU::getValueMapping(Bank, 1);
    break;
  }
  }

  return getInstructionMapping(/*ID*/1, /*Cost*/1,
                               getOperandsMapping(OpdsMapping),
                               MI.getNumOperands());
}