//===-- 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,
};

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

} // 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();

  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.isCopyLike() ? 1 : MI.getNumOperands();
  unsigned MappingID = DefaultMappingID;

  // Track the size and bank of each register.  We don't do partial mappings.
  SmallVector<unsigned, 8> OpSize(NumOperands);
  SmallVector<WebAssembly::PartialMappingIdx, 8> OpRegBankIdx(NumOperands);
  for (unsigned Idx = 0; Idx < NumOperands; ++Idx) {
    auto &MO = MI.getOperand(Idx);
    if (!MO.isReg() || !MO.getReg())
      continue;

    LLT Ty = MRI.getType(MO.getReg());
    if (!Ty.isValid())
      continue;

    OpSize[Idx] = Ty.getSizeInBits().getKnownMinValue();

    if (Ty.isInteger()) {
      if (OpSize[Idx] == 32) {
        OpRegBankIdx[Idx] = WebAssembly::PMI_I32;
      } else if (OpSize[Idx] == 64) {
        OpRegBankIdx[Idx] = WebAssembly::PMI_I64;
      }
    }
  }

  SmallVector<const ValueMapping *, 8> OpdsMapping(NumOperands);
  for (unsigned Idx = 0; Idx < NumOperands; ++Idx) {
    if (MI.getOperand(Idx).isReg() && MI.getOperand(Idx).getReg()) {
      LLT Ty = MRI.getType(MI.getOperand(Idx).getReg());
      if (!Ty.isValid())
        continue;

      if (OpRegBankIdx[Idx] <= 0) {
        return getInvalidInstructionMapping();
      }

      const auto &Mapping = getValueMapping(
          &WebAssembly::PartMappings[OpRegBankIdx[Idx] - WebAssembly::PMI_Min],
          1);

      if (!Mapping.isValid())
        return getInvalidInstructionMapping();

      OpdsMapping[Idx] = &Mapping;
    }
  }

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