//===----------------------------------------------------------------------===//
//
// 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
// Also available under a BSD-style license. See LICENSE.
//
//===----------------------------------------------------------------------===//

#include "torch-mlir/Conversion/TorchToMhlo/TorchToMhlo.h"

#include "../PassDetail.h"
#include "./MhloLegalizeUtils.h"
#include "./PopulatePatterns.h"
#include "mlir-hlo/Dialect/mhlo/IR/hlo_ops.h"
#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
#include "mlir/Dialect/Tensor/IR/Tensor.h"
#include "stablehlo/dialect/ChloOps.h"
#include "torch-mlir/Conversion/Utils/Utils.h"
#include "torch-mlir/Dialect/Torch/IR/TorchDialect.h"
#include "torch-mlir/Dialect/Torch/IR/TorchOps.h"
#include "torch-mlir/Dialect/Torch/Utils/TorchUpstream.h"
#include "torch-mlir/Dialect/Torch/Utils/Utils.h"
#include "torch-mlir/Dialect/TorchConversion/IR/TorchConversionOps.h"
#include <iostream>
#include <numeric>

using namespace mlir;
using namespace mlir::torch;
using namespace mlir::torch::Torch;

static Value createInitialValueForAtenPoolingOp(Operation *op, Type elementTy,
                                                PatternRewriter &rewriter) {
  auto constType = RankedTensorType::get({}, elementTy);
  // Avg pooling
  if (isa<AtenAdaptiveAvgPool2dOp, AtenAvgPool2dOp>(op)) {
    if (elementTy.isa<mlir::FloatType>()) {
      auto constAttr = DenseElementsAttr::get(
          constType, {APFloat::getZero(
                         elementTy.cast<mlir::FloatType>().getFloatSemantics(),
                         /*negative=*/false)});
      return rewriter.create<mhlo::ConstantOp>(op->getLoc(), constType,
                                               constAttr);
    } else if (elementTy.isa<mlir::IntegerType>() &&
               elementTy.getIntOrFloatBitWidth() != 8) {
      auto constAttr = DenseElementsAttr::get(
          constType, {APInt::getZero(elementTy.getIntOrFloatBitWidth())});
      return rewriter.create<mhlo::ConstantOp>(op->getLoc(), constType,
                                               constAttr);
    }
  }

  // Max pooling
  if (isa<AtenMaxPool2dOp, AtenMaxPool2dWithIndicesOp>(op)) {
    if (elementTy.isa<mlir::FloatType>()) {
      auto constAttr = DenseElementsAttr::get(
          constType, {APFloat::getLargest(
                         elementTy.cast<mlir::FloatType>().getFloatSemantics(),
                         /*negative=*/true)});
      return rewriter.create<mhlo::ConstantOp>(op->getLoc(), constType,
                                               constAttr);
    } else if (elementTy.isa<mlir::IntegerType>() &&
               elementTy.getIntOrFloatBitWidth() != 8) {
      auto constAttr = DenseElementsAttr::get(
          constType,
          {APInt::getSignedMinValue(elementTy.getIntOrFloatBitWidth())});
      return rewriter.create<mhlo::ConstantOp>(op->getLoc(), constType,
                                               constAttr);
    }
  }
  op->emitError("unimplemented lowering in AtenPoolingOp");
  return nullptr;
}

namespace {
template <typename AtenOpT>
class ConvertAtenPoolingOp : public OpConversionPattern<AtenOpT> {
public:
  using OpConversionPattern<AtenOpT>::OpConversionPattern;
  using OpAdaptor = typename AtenOpT::Adaptor;
  LogicalResult
  matchAndRewrite(AtenOpT op, OpAdaptor adaptor,
                  ConversionPatternRewriter &rewriter) const override;
};
} // namespace

// AtenMaxPool2dOp
namespace {
template <>
LogicalResult ConvertAtenPoolingOp<AtenMaxPool2dOp>::matchAndRewrite(
    AtenMaxPool2dOp op, OpAdaptor adaptor,
    ConversionPatternRewriter &rewriter) const {
  Value input = adaptor.self();
  auto inputTy = input.getType().cast<RankedTensorType>();
  auto inputElemTy = inputTy.getElementType();

  auto inputRank = inputTy.getRank();
  auto outTy =
      getTypeConverter()->convertType(op.getType()).cast<RankedTensorType>();

  if (inputRank <= 2) {
    return op.emitError(
        "max_pooling2d only supports inputs with rank higher than 2");
  }
  SmallVector<int64_t, 2> padding, kernelSize, stride, dilation;
  bool ceilMode = false;

  if (!(matchPattern(op.kernel_size(), m_TorchConstantIntList(kernelSize)))) {
    return rewriter.notifyMatchFailure(
        op, "non-const int kernel size unsupported!");
  }
  if (!(matchPattern(op.stride(), m_TorchConstantIntList(stride)))) {
    return rewriter.notifyMatchFailure(op, "non-const int stride unsupported!");
  }
  if (!(matchPattern(op.padding(), m_TorchConstantIntList(padding)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const int padding unsupported!");
  }
  if (!(matchPattern(op.dilation(), m_TorchConstantIntList(dilation)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const int dilation unsupported!");
  }
  if (!(matchPattern(op.ceil_mode(), m_TorchConstantBool(&ceilMode)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const bool ceil_mode unsupported!");
  }

  // prepend 1 to kernelSize, stride, dilation until they are of same rank as
  // input
  SmallVector<int64_t> mhloStride(inputRank, 1);
  SmallVector<int64_t> mhloDilation(inputRank, 1);
  SmallVector<int64_t> mhloKernelSize(inputRank, 1);
  SmallVector<int64_t> mhloPadding(inputRank * 2, 0);
  std::copy(dilation.begin(), dilation.end(),
            mhloDilation.begin() + inputRank - 2);
  std::copy(stride.begin(), stride.end(), mhloStride.begin() + inputRank - 2);
  std::copy(kernelSize.begin(), kernelSize.end(),
            mhloKernelSize.begin() + inputRank - 2);

  Value initVal = createInitialValueForAtenPoolingOp(op, inputElemTy, rewriter);

  mhloPadding[mhloPadding.size() - 4] = padding[0];
  mhloPadding[mhloPadding.size() - 3] = padding[0];
  mhloPadding[mhloPadding.size() - 2] = padding[1];
  mhloPadding[mhloPadding.size() - 1] = padding[1];

  DenseIntElementsAttr windowDimensions = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloKernelSize.size())},
                            rewriter.getI64Type()),
      mhloKernelSize);
  DenseIntElementsAttr windowStrides = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloStride.size())},
                            rewriter.getI64Type()),
      mhloStride);
  DenseIntElementsAttr baseDilations;
  DenseIntElementsAttr windowDilations = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloDilation.size())},
                            rewriter.getI64Type()),
      mhloDilation);
  DenseIntElementsAttr pad = DenseIntElementsAttr::get(
      RankedTensorType::get(
          {static_cast<int64_t>(inputRank), static_cast<int64_t>(2)},
          rewriter.getI64Type()),
      mhloPadding);
  auto reduceWindowOp = rewriter.create<mhlo::ReduceWindowOp>(
      op->getLoc(), outTy, input, initVal, windowDimensions, windowStrides,
      baseDilations, windowDilations, pad);

  Block &block = reduceWindowOp.body().emplaceBlock();

  auto blockArgumentTy = RankedTensorType::get({}, inputElemTy);
  block.addArgument(blockArgumentTy, op->getLoc());
  block.addArgument(blockArgumentTy, op->getLoc());

  auto *firstArg = block.args_begin();
  auto secondArg = block.args_rbegin();

  {
    OpBuilder::InsertionGuard guard(rewriter);
    rewriter.setInsertionPointToStart(&block);
    Value result =
        rewriter.create<mhlo::MaxOp>(op->getLoc(), *firstArg, *secondArg);
    rewriter.create<mhlo::ReturnOp>(op->getLoc(), result);
  }

  rewriter.replaceOp(op, reduceWindowOp.getResults());
  return success();
}
} // namespace

// AtenMaxPool2dWithIndicesOp
namespace {
template <>
LogicalResult ConvertAtenPoolingOp<AtenMaxPool2dWithIndicesOp>::matchAndRewrite(
    AtenMaxPool2dWithIndicesOp op, OpAdaptor adaptor,
    ConversionPatternRewriter &rewriter) const {
  Value input = adaptor.self();
  auto inputTy = input.getType().cast<RankedTensorType>();
  auto inputElemTy = inputTy.getElementType();
  auto inputShape = inputTy.getShape();
  auto inputRank = inputTy.getRank();
  auto outValTy =
      getTypeConverter()->convertType(op.getType(0)).cast<RankedTensorType>();
  auto outIdxTy =
      getTypeConverter()->convertType(op.getType(1)).cast<RankedTensorType>();

  if (inputRank <= 2) {
    return op.emitError(
        "max_pooling2d only supports inputs with rank higher than 2");
  }
  SmallVector<int64_t, 2> padding, kernelSize, stride, dilation;
  bool ceilMode = false;

  if (!(matchPattern(op.kernel_size(), m_TorchConstantIntList(kernelSize)))) {
    return rewriter.notifyMatchFailure(
        op, "non-const int kernel size unsupported!");
  }
  if (!(matchPattern(op.stride(), m_TorchConstantIntList(stride)))) {
    return rewriter.notifyMatchFailure(op, "non-const int stride unsupported!");
  }
  if (!(matchPattern(op.padding(), m_TorchConstantIntList(padding)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const int padding unsupported!");
  }
  if (!(matchPattern(op.dilation(), m_TorchConstantIntList(dilation)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const int dilation unsupported!");
  }
  if (!(matchPattern(op.ceil_mode(), m_TorchConstantBool(&ceilMode)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const bool ceil_mode unsupported!");
  }

  // prepend 1 to kernelSize, stride, dilation until they are of same rank as
  // input
  SmallVector<int64_t> mhloStride(inputRank, 1);
  SmallVector<int64_t> mhloDilation(inputRank, 1);
  SmallVector<int64_t> mhloKernelSize(inputRank, 1);
  SmallVector<int64_t> mhloPadding(inputRank * 2, 0);
  std::copy(dilation.begin(), dilation.end(),
            mhloDilation.begin() + inputRank - 2);
  std::copy(stride.begin(), stride.end(), mhloStride.begin() + inputRank - 2);
  std::copy(kernelSize.begin(), kernelSize.end(),
            mhloKernelSize.begin() + inputRank - 2);

  Value initVal = createInitialValueForAtenPoolingOp(op, inputElemTy, rewriter);

  mhloPadding[mhloPadding.size() - 4] = padding[0];
  mhloPadding[mhloPadding.size() - 3] = padding[0];
  mhloPadding[mhloPadding.size() - 2] = padding[1];
  mhloPadding[mhloPadding.size() - 1] = padding[1];

  DenseIntElementsAttr windowDimensions = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloKernelSize.size())},
                            rewriter.getI64Type()),
      mhloKernelSize);
  DenseIntElementsAttr windowStrides = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloStride.size())},
                            rewriter.getI64Type()),
      mhloStride);
  DenseIntElementsAttr baseDilations;
  DenseIntElementsAttr windowDilations = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloDilation.size())},
                            rewriter.getI64Type()),
      mhloDilation);
  DenseIntElementsAttr pad = DenseIntElementsAttr::get(
      RankedTensorType::get(
          {static_cast<int64_t>(inputRank), static_cast<int64_t>(2)},
          rewriter.getI64Type()),
      mhloPadding);

  auto inputShapeInfo = mhlo::getDimSizesOfTensor(rewriter, op, input);
  if (failed(inputShapeInfo)) {
    return rewriter.notifyMatchFailure(
        op, "failed to get dimension sizes of the input");
  }
  auto inputShapeVec = *inputShapeInfo;
  auto inputShapeTensor = rewriter.create<mlir::tensor::FromElementsOp>(
      op->getLoc(), inputShapeVec);

  SmallVector<Value> initIndexShapeVec;
  for (int64_t i = 0; i < inputRank - 2; i++)
    initIndexShapeVec.push_back(inputShapeVec[i]);
  initIndexShapeVec.push_back(rewriter.create<mlir::arith::MulIOp>(
      op->getLoc(), inputShapeVec[inputRank - 1],
      inputShapeVec[inputRank - 2]));
  auto initIndexShapeTensor = rewriter.create<mlir::tensor::FromElementsOp>(
      op->getLoc(), initIndexShapeVec);

  SmallVector<int64_t> initIndexShapeForType(inputShape.begin(),
                                             inputShape.end() - 2);
  if (inputShape[inputRank - 1] == ShapedType::kDynamicSize ||
      inputShape[inputRank - 2] == ShapedType::kDynamicSize) {
    initIndexShapeForType.push_back(ShapedType::kDynamicSize);
  } else {
    initIndexShapeForType.push_back(inputShape[inputRank - 1] *
                                    inputShape[inputRank - 2]);
  }

  auto initIndexTensor =
      rewriter
          .create<mhlo::DynamicIotaOp>(
              op->getLoc(),
              RankedTensorType::get(initIndexShapeForType,
                                    rewriter.getI64Type()),
              initIndexShapeTensor, static_cast<uint64_t>(inputRank - 2))
          .getResult();

  auto indexTensor =
      rewriter
          .create<mhlo::DynamicReshapeOp>(
              op->getLoc(),
              RankedTensorType::get(inputShape, rewriter.getI64Type()),
              initIndexTensor, inputShapeTensor)
          .getResult();

  Value initIdx = mhlo::getConstTensor<int64_t>(rewriter, op, {0}, {}).value();

  auto reduceWindowOp = rewriter.create<mhlo::ReduceWindowOp>(
      op->getLoc(), mlir::TypeRange{outValTy, outIdxTy},
      mlir::ValueRange{input, indexTensor}, mlir::ValueRange{initVal, initIdx},
      windowDimensions, windowStrides, baseDilations, windowDilations, pad);

  Block &block = reduceWindowOp.body().emplaceBlock();

  // Add bb argument
  auto blockValArgumentType = RankedTensorType::get({}, inputElemTy);
  auto blockIdxArgumentType = RankedTensorType::get({}, rewriter.getI64Type());
  auto compareResultType = RankedTensorType::get({}, rewriter.getI1Type());
  block.addArgument(blockValArgumentType, op->getLoc());
  block.addArgument(blockIdxArgumentType, op->getLoc());
  block.addArgument(blockValArgumentType, op->getLoc());
  block.addArgument(blockIdxArgumentType, op->getLoc());
  auto *firstValArg = block.args_begin();
  auto *firstIdxArg = std::next(firstValArg);
  auto *secondValArg = std::next(firstIdxArg);
  auto *secondIdxArg = std::next(secondValArg);

  mhlo::ComparisonTypeAttr compareTypeAttr;
  if (inputTy.getElementType().isa<mlir::FloatType>()) {
    compareTypeAttr = mhlo::ComparisonTypeAttr::get(
        rewriter.getContext(), mhlo::ComparisonType::FLOAT);
  } else if (inputTy.getElementType().isa<mlir::IntegerType>()) {
    compareTypeAttr = mhlo::ComparisonTypeAttr::get(
        rewriter.getContext(), mhlo::ComparisonType::SIGNED);
  }
  mhlo::ComparisonDirectionAttr compareGeDirectionAttr =
      mhlo::ComparisonDirectionAttr::get(rewriter.getContext(),
                                         mhlo::ComparisonDirection::GE);
  mhlo::ComparisonDirectionAttr compareEqDirectionAttr =
      mhlo::ComparisonDirectionAttr::get(rewriter.getContext(),
                                         mhlo::ComparisonDirection::EQ);

  {
    OpBuilder::InsertionGuard guard(rewriter);
    rewriter.setInsertionPointToStart(&block);

    Value compareGeResult = rewriter.create<mhlo::CompareOp>(
        op->getLoc(), compareResultType, *firstValArg, *secondValArg,
        compareGeDirectionAttr, compareTypeAttr);
    Value retValResult = rewriter.create<mhlo::SelectOp>(
        op->getLoc(), compareGeResult, *firstValArg, *secondValArg);

    // Get smaller index if compared values are equal.
    Value compareEqResult = rewriter.create<mhlo::CompareOp>(
        op->getLoc(), compareResultType, *firstValArg, *secondValArg,
        compareEqDirectionAttr, compareTypeAttr);
    Value minIdx =
        rewriter.create<mhlo::MinOp>(op->getLoc(), *firstIdxArg, *secondIdxArg);
    Value idxWithGeVal = rewriter.create<mhlo::SelectOp>(
        op->getLoc(), compareGeResult, *firstIdxArg, *secondIdxArg);
    Value retIdxResult = rewriter.create<mhlo::SelectOp>(
        op->getLoc(), compareEqResult, minIdx, idxWithGeVal);

    rewriter.create<mhlo::ReturnOp>(
        op->getLoc(), mlir::ValueRange{retValResult, retIdxResult});
  }

  rewriter.replaceOp(op, reduceWindowOp.getResults());
  return success();
}
} // namespace

// AtenAvgPool2dOp
namespace {
template <>
LogicalResult ConvertAtenPoolingOp<AtenAvgPool2dOp>::matchAndRewrite(
    AtenAvgPool2dOp op, OpAdaptor adaptor,
    ConversionPatternRewriter &rewriter) const {
  Value input = adaptor.self();
  auto inputTy = input.getType().cast<RankedTensorType>();
  auto inputElemTy = inputTy.getElementType();
  auto inputRank = inputTy.getRank();
  auto outTy =
      getTypeConverter()->convertType(op.getType()).cast<RankedTensorType>();
  auto outShape = outTy.getShape();

  if (inputRank <= 2) {
    return op.emitError(
        "avg_pooling2d only supports inputs with rank higher than 2");
  }
  SmallVector<int64_t, 2> padding, kernelSize, stride;
  bool ceilMode = false;
  bool countIncludePad = true;

  if (!(matchPattern(op.kernel_size(), m_TorchConstantIntList(kernelSize)))) {
    return rewriter.notifyMatchFailure(
        op, "non-const int kernel size unsupported!");
  }
  if (!(matchPattern(op.stride(), m_TorchConstantIntList(stride)))) {
    return rewriter.notifyMatchFailure(op, "non-const int stride unsupported!");
  }
  if (!(matchPattern(op.padding(), m_TorchConstantIntList(padding)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const int padding unsupported!");
  }
  if (!(matchPattern(op.ceil_mode(), m_TorchConstantBool(&ceilMode)))) {
    return rewriter.notifyMatchFailure(op,
                                       "non-const bool ceil_mode unsupported!");
  }
  if (!(matchPattern(op.count_include_pad(),
                     m_TorchConstantBool(&countIncludePad)))) {
    return rewriter.notifyMatchFailure(
        op, "non-const bool count_include_pad unsupported!");
  }
  if (succeeded(checkNotNone(rewriter, op, op.divisor_override()))) {
    return rewriter.notifyMatchFailure(
        op, "only None divisor_override supported for now!");
  }

  // prepend 1 to kernelSize, stride, dilation until they are of same rank as
  // input
  SmallVector<int64_t> mhloStride(inputRank, 1);
  SmallVector<int64_t> mhloDilation(inputRank, 1);
  SmallVector<int64_t> mhloKernelSize(inputRank, 1);
  SmallVector<int64_t> mhloPadding(inputRank * 2, 0);

  std::copy(stride.begin(), stride.end(), mhloStride.begin() + inputRank - 2);
  std::copy(kernelSize.begin(), kernelSize.end(),
            mhloKernelSize.begin() + inputRank - 2);
  mhloPadding[mhloPadding.size() - 4] = padding[0];
  mhloPadding[mhloPadding.size() - 3] = padding[0];
  mhloPadding[mhloPadding.size() - 2] = padding[1];
  mhloPadding[mhloPadding.size() - 1] = padding[1];

  Value initVal = createInitialValueForAtenPoolingOp(op, inputElemTy, rewriter);

  DenseIntElementsAttr windowDimensions = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloKernelSize.size())},
                            rewriter.getI64Type()),
      mhloKernelSize);
  DenseIntElementsAttr windowStrides = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloStride.size())},
                            rewriter.getI64Type()),
      mhloStride);
  DenseIntElementsAttr baseDilations;
  DenseIntElementsAttr windowDilations = DenseIntElementsAttr::get(
      RankedTensorType::get({static_cast<int64_t>(mhloDilation.size())},
                            rewriter.getI64Type()),
      mhloDilation);
  DenseIntElementsAttr pad = DenseIntElementsAttr::get(
      RankedTensorType::get(
          {static_cast<int64_t>(inputRank), static_cast<int64_t>(2)},
          rewriter.getI64Type()),
      mhloPadding);

  auto reduceWindowSum = rewriter.create<mhlo::ReduceWindowOp>(
      op->getLoc(), outTy, input, initVal, windowDimensions, windowStrides,
      baseDilations, windowDilations, pad);

  Block &sumBlock = reduceWindowSum.body().emplaceBlock();

  // Add bb argument
  auto blockArgumentType = RankedTensorType::get({}, inputElemTy);
  sumBlock.addArgument(blockArgumentType, op->getLoc());
  sumBlock.addArgument(blockArgumentType, op->getLoc());
  auto *firstArg = sumBlock.args_begin();
  auto secondArg = sumBlock.args_rbegin();

  {
    OpBuilder::InsertionGuard guard(rewriter);
    rewriter.setInsertionPointToStart(&sumBlock);

    Value sumResult =
        rewriter.create<mhlo::AddOp>(op->getLoc(), *firstArg, *secondArg);
    rewriter.create<mhlo::ReturnOp>(op->getLoc(), sumResult);
  }

  // Use kernel size as the divisor
  if (countIncludePad) {
    Value divisor = mhlo::getConstTensor<int64_t>(
                        rewriter, op, {kernelSize[0] * kernelSize[1]}, {})
                        .value();
    divisor = mhlo::promoteType(rewriter, divisor, outTy);
    DenseIntElementsAttr bcastDimensions;
    rewriter.replaceOpWithNewOp<mlir::chlo::BroadcastDivOp>(
        op, outTy, reduceWindowSum.getResult(0), divisor, bcastDimensions);
    return success();
  }

  // Use another mhlo.ReduceWindowOp to get the divisor
  Value windowSizeConst =
      mhlo::getConstTensor<float>(rewriter, op, {1.0}, {}).value();
  windowSizeConst = mhlo::promoteType(rewriter, windowSizeConst, outTy);
  auto inputShapeVec = *mhlo::getDimSizesOfTensor(rewriter, op, input);
  auto inputShapeTensor = rewriter.create<mlir::tensor::FromElementsOp>(
      op->getLoc(), inputShapeVec);

  windowSizeConst = rewriter.create<mhlo::DynamicBroadcastInDimOp>(
      op->getLoc(),
      RankedTensorType::get(inputTy.getShape(), outTy.getElementType()),
      windowSizeConst, inputShapeTensor, rewriter.getI64TensorAttr({}));
  
  Value zero = createInitialValueForAtenPoolingOp(op, inputElemTy, rewriter);
  auto reduceWindowSize = rewriter.create<mhlo::ReduceWindowOp>(
      op->getLoc(), RankedTensorType::get(outShape, inputElemTy),
      windowSizeConst, zero, windowDimensions, windowStrides, baseDilations,
      windowDilations, pad);

  Block &sizeBlock = reduceWindowSize.body().emplaceBlock();

  // Add bb argument
  blockArgumentType = RankedTensorType::get({}, inputElemTy);
  sizeBlock.addArgument(blockArgumentType, op->getLoc());
  sizeBlock.addArgument(blockArgumentType, op->getLoc());
  firstArg = sizeBlock.args_begin();
  secondArg = sizeBlock.args_rbegin();

  {
    OpBuilder::InsertionGuard guard(rewriter);
    rewriter.setInsertionPointToStart(&sizeBlock);

    Value sumResult =
        rewriter.create<mhlo::AddOp>(op->getLoc(), *firstArg, *secondArg);
    rewriter.create<mhlo::ReturnOp>(op->getLoc(), sumResult);
  }

  rewriter.replaceOpWithNewOp<mhlo::DivOp>(
      op, outTy, reduceWindowSum.getResult(0), reduceWindowSize.getResult(0));
  return success();
}

} // namespace

void mlir::torch::torch_to_mhlo::populatePoolingOpPatternsAndLegality(
    TypeConverter &typeConverter, RewritePatternSet &patterns,
    ConversionTarget &target) {
  MLIRContext *context = patterns.getContext();
  target.addIllegalOp<AtenMaxPool2dOp>();
  patterns.add<ConvertAtenPoolingOp<AtenMaxPool2dOp>>(typeConverter, context);
  target.addIllegalOp<AtenAvgPool2dOp>();
  patterns.add<ConvertAtenPoolingOp<AtenAvgPool2dOp>>(typeConverter, context);
  target.addIllegalOp<AtenMaxPool2dWithIndicesOp>();
  patterns.add<ConvertAtenPoolingOp<AtenMaxPool2dWithIndicesOp>>(typeConverter,
                                                                 context);
}