llvm/lib/Target/WebAssembly/GISel/WebAssemblyRegisterBankInfo.cpp

//===-- WebAssemblyRegisterBankInfo.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
/// WebAssembly.
/// \todo This should be generated by TableGen.
//===----------------------------------------------------------------------===//

#include "WebAssemblyRegisterBankInfo.h"
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssemblyRegisterInfo.h"
#include "WebAssemblySubtarget.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"

#define GET_TARGET_REGBANK_IMPL

#include "WebAssemblyGenRegisterBank.inc"

namespace llvm {
namespace WebAssembly {
enum PartialMappingIdx {
  PMI_None = -1,
  PMI_I32 = 1,
  PMI_I64,
  PMI_Min = PMI_I32,
};

enum ValueMappingIdx {
  InvalidIdx = 0,
  I32Idx = 1,
  I64Idx = 5,
};

const RegisterBankInfo::PartialMapping PartMappings[]{{0, 32, I32RegBank},
                                                      {0, 64, I64RegBank}};

const RegisterBankInfo::ValueMapping ValueMappings[] = {
    // invalid
    {nullptr, 0},
    // up to 4 operands as I32
    {&PartMappings[PMI_I32 - PMI_Min], 1},
    {&PartMappings[PMI_I32 - PMI_Min], 1},
    {&PartMappings[PMI_I32 - PMI_Min], 1},
    {&PartMappings[PMI_I32 - PMI_Min], 1},
    // up to 4 operands as I64
    {&PartMappings[PMI_I64 - PMI_Min], 1},
    {&PartMappings[PMI_I64 - PMI_Min], 1},
    {&PartMappings[PMI_I64 - PMI_Min], 1},
    {&PartMappings[PMI_I64 - PMI_Min], 1},
};
} // namespace WebAssembly
} // namespace llvm

using namespace llvm;

WebAssemblyRegisterBankInfo::WebAssemblyRegisterBankInfo(
    const TargetRegisterInfo &TRI) {}

const RegisterBankInfo::InstructionMapping &
WebAssemblyRegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
  unsigned Opc = MI.getOpcode();
  const MachineFunction &MF = *MI.getParent()->getParent();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  const WebAssemblySubtarget &STI = MF.getSubtarget<WebAssemblySubtarget>();
  const WebAssemblyRegisterInfo &TRI = *STI.getRegisterInfo();

  if ((Opc != TargetOpcode::COPY && !isPreISelGenericOpcode(Opc)) ||
      Opc == TargetOpcode::G_PHI) {
    const RegisterBankInfo::InstructionMapping &Mapping =
        getInstrMappingImpl(MI);
    if (Mapping.isValid())
      return Mapping;
  }

  const unsigned NumOperands = MI.getNumOperands();
  const ValueMapping *OperandsMapping = nullptr;
  unsigned MappingID = DefaultMappingID;

  const LLT Op0Ty = MRI.getType(MI.getOperand(0).getReg());
  unsigned Op0Size = Op0Ty.getSizeInBits();

  auto &Op0IntValueMapping =
      WebAssembly::ValueMappings[Op0Size == 64 ? WebAssembly::I64Idx
                                               : WebAssembly::I32Idx];

  using namespace TargetOpcode;
  switch (Opc) {
  case G_CONSTANT:
    OperandsMapping = getOperandsMapping({&Op0IntValueMapping, nullptr});
    break;
  case G_IMPLICIT_DEF:
    OperandsMapping = &Op0IntValueMapping;
    break;
  case G_ADD:
  case G_SUB:
  case G_MUL:
  case G_UDIV:
  case G_SDIV:
  case G_UREM:
  case G_SREM:
  case G_AND:
  case G_OR:
  case G_XOR:
  case G_ASHR:
  case G_LSHR:
  case G_SHL:
  case G_CTLZ:
  case G_CTLZ_ZERO_UNDEF:
  case G_CTTZ:
  case G_CTTZ_ZERO_UNDEF:
  case G_CTPOP:
  case G_ROTL:
  case G_ROTR:
    OperandsMapping = &Op0IntValueMapping;
    break;
  case G_ZEXT:
  case G_ANYEXT:
  case G_SEXT:
  case G_TRUNC: {
    const LLT Op1Ty = MRI.getType(MI.getOperand(1).getReg());
    unsigned Op1Size = Op1Ty.getSizeInBits();

    auto &Op1IntValueMapping =
        WebAssembly::ValueMappings[Op1Size == 64 ? WebAssembly::I64Idx
                                                 : WebAssembly::I32Idx];
    OperandsMapping =
        getOperandsMapping({&Op0IntValueMapping, &Op1IntValueMapping});
    break;
  }
  case G_SEXT_INREG:
    OperandsMapping =
        getOperandsMapping({&Op0IntValueMapping, &Op0IntValueMapping, nullptr});
    break;
  case COPY: {
    Register DstReg = MI.getOperand(0).getReg();
    Register SrcReg = MI.getOperand(1).getReg();

    const RegisterBank *DstRB = getRegBank(DstReg, MRI, TRI);
    const RegisterBank *SrcRB = getRegBank(SrcReg, MRI, TRI);

    if (!DstRB)
      DstRB = SrcRB;
    else if (!SrcRB)
      SrcRB = DstRB;

    assert(DstRB && SrcRB && "Both RegBank were nullptr");

    if (DstRB != SrcRB) {
      break; // for now, only allow no-op copies
    }

    return getInstructionMapping(
        MappingID, /*Cost=*/1, &Op0IntValueMapping,
        // We only care about the mapping of the destination for COPY.
        1);
  }
  }

  if (!OperandsMapping)
    return getInvalidInstructionMapping();

  return getInstructionMapping(MappingID, /*Cost=*/1, OperandsMapping,
                               NumOperands);
}