//===----------------------------------------------------------------------===//
//
// 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/Dialect/Torch/IR/TorchOps.h"
#include "torch-mlir/Dialect/Torch/Utils/Utils.h"

#include "mlir/Dialect/Func/IR/FuncOps.h"
#include "mlir/IR/Builders.h"
#include "mlir/IR/BuiltinOps.h"
#include "mlir/IR/PatternMatch.h"
#include "mlir/IR/TypeUtilities.h"
#include "mlir/Support/LLVM.h"
#include "torch-mlir/Dialect/Torch/Utils/Utils.h"
#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/Support/Casting.h"

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

//===----------------------------------------------------------------------===//
// Utilities
//===----------------------------------------------------------------------===//

Value mlir::torch::Torch::adjustStaticInformation(OpBuilder &builder,
                                                  Location loc, Value value,
                                                  Type desiredType,
                                                  bool userAllowsRefinement) {
  Type type = value.getType();

  // If the value is already of the desired type, we're done.
  if (type == desiredType)
    return value;

  // If the type is a tensor, then adjust the static information.
  if ((type.isa<ValueTensorType>() && desiredType.isa<ValueTensorType>()) ||
      (type.isa<NonValueTensorType>() &&
       desiredType.isa<NonValueTensorType>())) {
    Value adjusted = builder.create<TensorStaticInfoCastOp>(value.getLoc(),
                                                            desiredType, value);
    return adjusted;
  }

  // If the type is a subtype of desiredType, then we need to derefine it to
  // desiredType, unless the user allows refinement.
  if (isValidSubtype(type, desiredType)) {
    if (!userAllowsRefinement) {
      Value adjusted =
          builder.create<DerefineOp>(value.getLoc(), desiredType, value);
      return adjusted;
    } else {
      return value;
    }
  }

  // If the desiredType is subtype of type, then we assume that the desiredType
  // is dynamically valid, so we do an unchecked cast.
  if (isValidSubtype(desiredType, type)) {
    Value adjusted =
        builder.create<PrimUncheckedCastOp>(value.getLoc(), desiredType, value);
    return adjusted;
  }

  // No known adjustment.
  return Value();
}

Value mlir::torch::Torch::copyTensorToType(OpBuilder &builder, Location loc,
                                           BaseTensorType newType,
                                           Value tensor) {
  auto originalType = tensor.getType().cast<BaseTensorType>();
  // Adjust the static information in the type to match between the original and
  // new types.
  if (!originalType.hasSameSizesAndDtype(newType)) {
    tensor = builder.create<TensorStaticInfoCastOp>(
        loc, originalType.getWithSizesAndDtypeFrom(newType), tensor);
  }

  // Unless both the original and new types are both value tensors, we end
  // up creating one op that converts between the value and non-value tensor
  // domains. If both the original and new types are both non-value tensors,
  // then we do the copy by going to a value tensor and back.
  if (tensor.getType().isa<NonValueTensorType>())
    tensor = builder.create<CopyToValueTensorOp>(loc, tensor);
  if (newType.isa<NonValueTensorType>())
    tensor = builder.create<CopyToNonValueTensorOp>(loc, tensor);

  return tensor;
}

bool mlir::torch::Torch::isListPotentiallyMutated(Value list) {
  assert(list.getType().isa<Torch::ListType>());
  return llvm::any_of(list.getUsers(), potentiallyMutatesListOperands);
}

bool mlir::torch::Torch::potentiallyMutatesListOperands(Operation *op) {
  // TODO: Find a better place to put this assertion.
  assert((!op->hasTrait<Torch::OpTrait::HasValueSemantics>() ||
          op->hasTrait<OpTrait::ReadOnly>()) &&
         "HasValueSemantics should imply ReadOnly!");
  // ReadOnly ops trivially do not mutate any list operands.
  if (op->hasTrait<Torch::OpTrait::ReadOnly>())
    return false;

  // Ops with no MemoryEffectOpInterface effects also do not mutate any list
  // operands.
  if (auto effects = dyn_cast<MemoryEffectOpInterface>(op)) {
    if (effects.hasNoEffect())
      return false;
  }

  // Conservatively assume that an op might mutate any list operands.
  return true;
}

static IntegerAttr getI64IntegerAttr(MLIRContext *context, int64_t value) {
  return IntegerAttr::get(IntegerType::get(context, 64), value);
}

static FloatAttr getF64FloatAttr(MLIRContext *context, double value) {
  return FloatAttr::get(Float64Type::get(context), value);
}

static Value getScalarIntValue(Value input, Location loc,
                               PatternRewriter &rewriter) {
  auto inputType = input.getType();
  if (inputType.isa<Torch::IntType>()) {
    return input;
  }

  auto inputTensorType = inputType.dyn_cast<BaseTensorType>();
  if (!inputTensorType)
    return nullptr;

  Type inputDtype = inputTensorType.getOptionalDtype();
  if (!inputDtype || !inputDtype.isInteger(64))
    return nullptr;

  std::optional<unsigned> inputRank = getTensorRank(input);
  if (!inputRank || *inputRank != 0)
    return nullptr;

  if (auto valueTensorLiteralOp = input.getDefiningOp<ValueTensorLiteralOp>()) {
    auto val = valueTensorLiteralOp.getValue()
                   .cast<DenseElementsAttr>()
                   .getSplatValue<int64_t>();
    return rewriter.create<Torch::ConstantIntOp>(
        loc, rewriter.getI64IntegerAttr(val));
  } else if (auto primNumToTensorScalarOp =
                 input.getDefiningOp<PrimNumToTensorScalarOp>()) {
    return primNumToTensorScalarOp.getA();
  } else if (auto tensorIntOp = input.getDefiningOp<AtenTensorIntOp>()) {
    return tensorIntOp.getT();
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// MethodOp
//===----------------------------------------------------------------------===//

LogicalResult MethodOp::verifySymbolUses(SymbolTableCollection &symbolTable) {
  auto func =
      symbolTable.lookupNearestSymbolFrom<func::FuncOp>(*this, getFunctionAttr());
  if (!func)
    return emitError() << "'@" << getFunction()
                       << "' does not reference a valid function";
  if (func.getVisibility() != SymbolTable::Visibility::Private)
    return emitError() << "'@" << getFunction()
                       << "' must reference a private function";
  if (func.isDeclaration())
    return emitError() << "'@" << getFunction()
                       << "' must reference a function that is defined (not "
                          "merely declared)";
  auto expectedReceiverArgType = NnModuleType::get(
      getContext(), getOperation()->getParentOfType<ClassTypeOp>().getName());
  if (func.getFunctionType().getNumInputs() == 0 ||
      func.getFunctionType().getInput(0) != expectedReceiverArgType) {
    return emitError() << "the referenced function '" << getFunction()
                       << "' must have a first argument of type "
                       << expectedReceiverArgType;
  }
  return success();
}

//===----------------------------------------------------------------------===//
// NnModuleOp
//===----------------------------------------------------------------------===//

LogicalResult NnModuleOp::verify() {
  for (Operation &child : *getBody())
    if (!isa<SlotOp, NnModuleTerminatorOp>(&child))
      return child.emitOpError() << "is not allowed inside 'torch.nn_module'";
  return success();
}

LogicalResult NnModuleOp::verifySymbolUses(SymbolTableCollection &symbolTable) {
  auto classType = symbolTable.lookupNearestSymbolFrom<ClassTypeOp>(
      *this, SymbolRefAttr::get(getContext(), getClassName()));
  if (!classType)
    return emitError() << "'" << getClassName()
                       << "' does not reference a valid class type";

  auto attrs = llvm::to_vector<6>(getBody()->getOps<SlotOp>());
  auto attrDefs = llvm::to_vector<6>(classType.getBody()->getOps<AttrOp>());
  if (attrs.size() != attrDefs.size())
    return emitError() << "number of 'torch.slot's in a 'torch.nn_module' must "
                          "match number of 'torch.attr's in "
                          "the corresponding 'torch.class_type'";
  for (int i = 0, e = attrs.size(); i != e; i++) {
    SlotOp attr = attrs[i];
    AttrOp attrDef = attrDefs[i];
    if (!isValidSubtype(attr.getValue().getType(), attrDef.getType()) ||
        attr.getName() != attrDef.getName()) {
      return attr.emitOpError()
          .append("is expected to match type and name of '",
                  attrDef.getOperation(), "'")
          .attachNote(attrDef.getLoc())
          .append("see torch.attr at corresponding index ", i, " here");
    }
  }

  return success();
}

//===----------------------------------------------------------------------===//
// PrimListConstructOp
//===----------------------------------------------------------------------===//

LogicalResult PrimListConstructOp::verify() {
  auto resultType = getResult().getType();
  auto resultElementType = resultType.dyn_cast<ListType>().getContainedType();
  auto matchResultElementType = [&](Type type) {
    return isValidSubtype(type, resultElementType);
  };
  if (!llvm::all_of(getOperandTypes(), matchResultElementType)) {
    return emitError() << "operand types should have the same type as the "
                          "list contained type";
  }

  return success();
}

//===----------------------------------------------------------------------===//
// PrimDictConstructOp
//===----------------------------------------------------------------------===//

LogicalResult PrimDictConstructOp::verify() {
  auto isValidSubTypeOf = [](Type expectedType) {
    return [=](Type type) { return isValidSubtype(type, expectedType); };
  };

  if (!llvm::all_of(getKeys().getTypes(), isValidSubTypeOf(getKeyType())))
    return emitError() << "keys should be of Dict key type";

  if (!llvm::all_of(getValues().getTypes(), isValidSubTypeOf(getValueType())))
    return emitError() << "values  should be of Dict value type";

  return success();
}

//===----------------------------------------------------------------------===//
// ClassTypeOp
//===----------------------------------------------------------------------===//

LogicalResult ClassTypeOp::verify() {
  llvm::StringMap<Operation *> namesToOps;
  for (Operation &child : getBody()->without_terminator()) {
    if (!isa<AttrOp, MethodOp>(&child))
      return child.emitOpError() << "is not allowed inside `torch.class_type`";
    StringRef name;
    if (auto attr = dyn_cast<AttrOp>(child))
      name = attr.getName();
    else
      name = cast<MethodOp>(child).getName();
    auto itAndWasInserted = namesToOps.insert({name, &child});
    auto it = itAndWasInserted.first;
    bool wasInserted = itAndWasInserted.second;
    if (!wasInserted) {
      auto diag = emitOpError().append("has duplicate attr/method with name '",
                                       name, "'");
      diag.attachNote(it->second->getLoc())
          .append("see first conflicting attr/method here");
      diag.attachNote(child.getLoc())
          .append("see second conflicting attr/method here");
      return failure();
    }
  }

  return success();
}

//===----------------------------------------------------------------------===//
// PrimLoopOp
//===----------------------------------------------------------------------===//

OperandRange
PrimLoopOp::getEntrySuccessorOperands(std::optional<unsigned int> index) {
  assert(index.has_value() && index.value() == 0);
  return getIterArgsInit();
}

void PrimLoopOp::getSuccessorRegions(
    std::optional<unsigned> index, SmallVectorImpl<RegionSuccessor> &regions) {

  if (!index.has_value()) {
    regions.emplace_back(&getRegion(), getRegion().getArguments().slice(1));
    return;
  }
  assert(*index == 0);
  regions.emplace_back(&getRegion(), getRegion().getArguments().slice(1));
  regions.emplace_back(getResults());
}

bool PrimLoopOp::isForLike() {
  bool b;
  return matchPattern(getInitialCondition(), m_TorchConstantBool(&b)) && b;
}

//===----------------------------------------------------------------------===//
// PrimLoopConditionOp
//===----------------------------------------------------------------------===//

MutableOperandRange PrimLoopConditionOp::getMutableSuccessorOperands(
    std::optional<unsigned> index) {
  // Pass all operands except the condition to the successor which is the
  // parent loop op.
  return getIterArgsMutable();
}

//===----------------------------------------------------------------------===//
// PrimIfOp
//===----------------------------------------------------------------------===//

ParseResult PrimIfOp::parse(OpAsmParser &parser, OperationState &result) {
  // Create the regions.
  result.regions.reserve(2);
  Region *thenRegion = result.addRegion();
  Region *elseRegion = result.addRegion();

  auto &builder = parser.getBuilder();
  OpAsmParser::UnresolvedOperand cond;
  Type boolType = builder.getType<Torch::BoolType>();
  if (parser.parseOperand(cond) ||
      parser.resolveOperand(cond, boolType, result.operands))
    return failure();
  // Parse results type list.
  if (parser.parseArrowTypeList(result.types))
    return failure();
  // Parse the 'then' region.
  if (parser.parseRegion(*thenRegion, /*arguments=*/{}, /*argTypes=*/{}))
    return failure();
  // Parse the 'else' region.
  if (parser.parseKeyword("else"))
    return failure();
  if (parser.parseRegion(*elseRegion, /*arguments=*/{}, /*argTypes=*/{}))
    return failure();
  // Parse the optional attribute list.
  if (parser.parseOptionalAttrDict(result.attributes))
    return failure();
  return success();
}

void PrimIfOp::print(OpAsmPrinter &p) {
  p << " " << getCondition();
  p << " -> (" << getResultTypes() << ") ";
  p.printRegion(getThenRegion(), /*printEntryBlockArgs=*/false);
  p << " else ";
  p.printRegion(getElseRegion(), /*printEntryBlockArgs=*/false);

  p.printOptionalAttrDict((*this)->getAttrs());
}

void PrimIfOp::getSuccessorRegions(std::optional<unsigned> index,
                                   SmallVectorImpl<RegionSuccessor> &regions) {
  // The `then` and the `else` region branch back to the parent operation.
  if (index.has_value()) {
    regions.push_back(RegionSuccessor(getResults()));
    return;
  }

  // If the condition is constant, we can give a more precise answer.
  bool condition;
  if (matchPattern(getCondition(), m_TorchConstantBool(&condition))) {
    Region *executedRegion = condition ? &getThenRegion() : &getElseRegion();
    regions.push_back(RegionSuccessor(executedRegion));
    return;
  }

  // If the condition isn't constant, both regions may be executed.
  regions.push_back(RegionSuccessor(&getThenRegion()));
  regions.push_back(RegionSuccessor(&getElseRegion()));
  return;
}

/// Replaces the given op with the contents of the given single-block region,
/// using the operands of the block terminator to replace operation results.
static void replaceOpWithRegion(PatternRewriter &rewriter, Operation *op,
                                Region &region, ValueRange blockArgs = {}) {
  assert(llvm::hasSingleElement(region) && "expected single-region block");
  Block *block = &region.front();
  Operation *terminator = block->getTerminator();
  ValueRange results = terminator->getOperands();
  rewriter.inlineBlockBefore(block, op, blockArgs);
  rewriter.replaceOp(op, results);
  rewriter.eraseOp(terminator);
}

void PrimIfOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                           MLIRContext *context) {
  // If the condition is constant, delete the dead branch and inline the live
  // branch.
  patterns.add(+[](PrimIfOp op, PatternRewriter &rewriter) {
    auto constantBool = op.getCondition().getDefiningOp<Torch::ConstantBoolOp>();
    if (!constantBool)
      return rewriter.notifyMatchFailure(op, "non-constant condition");
    replaceOpWithRegion(
        rewriter, op, constantBool.getValue() ? op.getThenRegion() : op.getElseRegion());
    return success();
  });
  // If the thenRegion and elseRegion yield the same Value's, then use those
  // directly.
  patterns.add(+[](PrimIfOp op, PatternRewriter &rewriter) {
    auto trueTerminator = op.getThenRegion().front().getTerminator();
    auto falseTerminator = op.getElseRegion().front().getTerminator();
    bool madeChange = false;
    SmallVector<int> resultsToErase;
    for (auto t : llvm::zip(trueTerminator->getOperands(),
                            falseTerminator->getOperands(), op->getResults())) {
      auto trueVal = std::get<0>(t);
      auto falseVal = std::get<1>(t);
      auto resultToBeReplaced = std::get<2>(t);
      if (trueVal == falseVal) {
        madeChange |= !resultToBeReplaced.use_empty();
        resultToBeReplaced.replaceAllUsesWith(trueVal);
      }
    }
    // We leave it up to a separate pattern (not yet implemented) to erase the
    // results that are now dead. That transformation is independently useful,
    // and also pretty tricky to implement because it changes the number of
    // results.
    return success(madeChange);
  });
  // Erase any dead results.
  patterns.add(+[](PrimIfOp op, PatternRewriter &rewriter) {
    llvm::BitVector resultsToErase(op.getNumResults());
    for (auto result : llvm::enumerate(op->getResults())) {
      if (result.value().use_empty())
        resultsToErase.set(result.index());
    }

    // If no results have uses and there are no side effects, just erase the op.
    // Approximate the body having no side effects by checking if it is just a
    // terminator.
    // Note: We don't want to make this logic too fancy, because in general,
    // checking for recursive side effects can result in a quadratic amount of
    // work (N nested If's each resulting in O(N) work). It should probably be
    // split into its own pattern if we want to make it fancier.
    if (resultsToErase.all() &&
        llvm::hasSingleElement(op.getThenRegion().front()) &&
        llvm::hasSingleElement(op.getElseRegion().front())) {
      rewriter.eraseOp(op);
      return success();
    }

    // If there are no results to erase, we're done.
    if (!resultsToErase.any())
      return failure();

    SmallVector<Type> newResultTypes;
    for (int i = 0, e = op->getNumResults(); i < e; ++i) {
      if (resultsToErase[i])
        continue;
      newResultTypes.push_back(op->getResult(i).getType());
    }
    auto newIf =
        rewriter.create<PrimIfOp>(op->getLoc(), newResultTypes, op.getCondition());
    rewriter.inlineRegionBefore(op.getThenRegion(), newIf.getThenRegion(),
                                newIf.getThenRegion().end());
    rewriter.inlineRegionBefore(op.getElseRegion(), newIf.getElseRegion(),
                                newIf.getElseRegion().end());
    newIf.getThenRegion().front().getTerminator()->eraseOperands(resultsToErase);
    newIf.getElseRegion().front().getTerminator()->eraseOperands(resultsToErase);
    SmallVector<Value> replacementValues;
    for (int i = 0, e = op->getNumResults(), nextNewValue = 0; i < e; ++i) {
      if (resultsToErase[i])
        replacementValues.push_back(nullptr);
      else
        replacementValues.push_back(newIf->getResult(nextNewValue++));
    }
    rewriter.replaceOp(op, replacementValues);

    return success();
  });
}

//===----------------------------------------------------------------------===//
// RuntimeAssertOp
//===----------------------------------------------------------------------===//

void RuntimeAssertOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](RuntimeAssertOp op, PatternRewriter &rewriter) {
    bool value;
    if (!matchPattern(op.getCondition(), m_TorchConstantBool(&value)))
      return failure();

    if (value) {
        rewriter.eraseOp(op);
        return success();
    }
    // Even if the condition is statically false, the assert might never be
    // executed.
    return failure();
  });
}

//===----------------------------------------------------------------------===//
// DerefineOp
//===----------------------------------------------------------------------===//

bool DerefineOp::areCastCompatible(mlir::TypeRange inputs,
                                   mlir::TypeRange outputs) {
  return isValidSubtype(inputs[0], outputs[0]);
}

OpFoldResult DerefineOp::fold(FoldAdaptor adaptor) {
  auto uncheckedCast = getOperand().getDefiningOp<PrimUncheckedCastOp>();
  if (!uncheckedCast)
    return nullptr;
  if (uncheckedCast.getOperand().getType() == getType())
    return uncheckedCast.getOperand();
  return nullptr;
}

void DerefineOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                             MLIRContext *context) {
  patterns.add(+[](DerefineOp op, PatternRewriter &rewriter) {
    bool madeChange = false;
    for (OpOperand &use : llvm::make_early_inc_range(op->getUses())) {
      if (use.getOwner()->hasTrait<OpTrait::AllowsTypeRefinement>()) {
        use.set(op.getOperand());
        madeChange = true;
      }
    }
    return success(madeChange);
  });
}

static OpFoldResult atenIsOrIsNotFoldHelper(Operation *op, bool equalIsTrue) {
  Value lhs = op->getOperand(0);
  Value rhs = op->getOperand(1);
  // Look through DerefineOp's to get more refined static information.
  if (auto derefine = lhs.getDefiningOp<DerefineOp>())
    lhs = derefine.getOperand();
  if (auto derefine = rhs.getDefiningOp<DerefineOp>())
    rhs = derefine.getOperand();
  Type lhsType = lhs.getType();
  Type rhsType = rhs.getType();

  // If either type is a NoneType, make it be the lhsType.
  if (rhsType.isa<Torch::NoneType>()) {
    std::swap(lhsType, rhsType);
    std::swap(lhs, rhs);
  }

  // For now, check a few specific cases.

  // If both types are the singleton `!torch.none` type, then we don't even need
  // to look at the values.
  if (lhsType.isa<Torch::NoneType>() && rhsType.isa<Torch::NoneType>())
    return IntegerAttr::get(IntegerType::get(op->getContext(), 1), equalIsTrue);

  // If neither type is a subtype of the other, then the result is false.
  // TODO: Implement and use subtype infra for this.
  // For now, check a specific case.
  // If the rhs is not OptionalType, then we know it cannot be None.
  if (lhsType.isa<Torch::NoneType>() && !rhsType.isa<Torch::OptionalType>()) {
    return IntegerAttr::get(IntegerType::get(op->getContext(), 1),
                            !equalIsTrue);
  }

  return nullptr;
}

//===----------------------------------------------------------------------===//
// Aten__RangeLengthOp
//===----------------------------------------------------------------------===//

OpFoldResult Aten__RangeLengthOp::fold(FoldAdaptor adaptor) {
  auto lo = adaptor.getLo();
  auto hi = adaptor.getHi();
  auto step = adaptor.getStep();
  if (!lo || !hi || !step)
    return nullptr;
  auto loInt = lo.dyn_cast_or_null<IntegerAttr>().getValue();
  auto hiInt = hi.dyn_cast_or_null<IntegerAttr>().getValue();
  auto stepInt = step.dyn_cast_or_null<IntegerAttr>().getValue();
  // TODO: Implement folding for negative steps.
  if (stepInt.isNegative())
    return nullptr;
  // From Python language spec:
  // r[i] = lo + step*i such that i >= 0 and r[i] < hi
  // So maximize `i` such that lo + step * i < hi
  // ==> i == ceildiv(hi - lo, step)
  return IntegerAttr::get(lo.cast<TypedAttr>().getType(),
                          llvm::APIntOps::RoundingSDiv(hiInt - loInt, stepInt,
                                                       APInt::Rounding::UP));
}

//===----------------------------------------------------------------------===//
// Aten__DeriveIndexOp
//===----------------------------------------------------------------------===//

OpFoldResult Aten__DeriveIndexOp::fold(FoldAdaptor adaptor) {
  auto index = adaptor.getIndex();
  auto start = adaptor.getStart();
  auto step = adaptor.getStep();
  if (!index || !start || !step)
    return nullptr;
  auto indexInt = index.dyn_cast_or_null<IntegerAttr>().getValue();
  auto startInt = start.dyn_cast_or_null<IntegerAttr>().getValue();
  auto stepInt = step.dyn_cast_or_null<IntegerAttr>().getValue();
  return IntegerAttr::get(index.cast<TypedAttr>().getType(),
                          startInt + stepInt * indexInt);
}

//===----------------------------------------------------------------------===//
// Aten__Is__Op
//===----------------------------------------------------------------------===//

OpFoldResult Aten__Is__Op::fold(FoldAdaptor adaptor) {
  return atenIsOrIsNotFoldHelper(*this, /*equalIsTrue=*/true);
}

//===----------------------------------------------------------------------===//
// Aten__Isnot__Op
//===----------------------------------------------------------------------===//

OpFoldResult Aten__Isnot__Op::fold(FoldAdaptor adaptor) {
  return atenIsOrIsNotFoldHelper(*this, /*equalIsTrue=*/false);
}

//===----------------------------------------------------------------------===//
// Aten__Not__Op
//===----------------------------------------------------------------------===//

OpFoldResult Aten__Not__Op::fold(FoldAdaptor adaptor) {
  bool value;
  if (!matchPattern(getOperand(), m_TorchConstantBool(&value)))
    return nullptr;
  return IntegerAttr::get(IntegerType::get(getContext(), 1), !value);
}

//===----------------------------------------------------------------------===//
// AtenNeBoolOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenNeBoolOp::fold(FoldAdaptor adaptor) {
  if (getOperand(0) == getOperand(1))
    return IntegerAttr::get(IntegerType::get(getContext(), 1), false);

  bool a, b;
  if (!matchPattern(getOperand(0), m_TorchConstantBool(&a)))
    return nullptr;
  if (!matchPattern(getOperand(1), m_TorchConstantBool(&b)))
    return nullptr;
  return IntegerAttr::get(IntegerType::get(getContext(), 1), a != b);
}

//===----------------------------------------------------------------------===//
// AtenSqueezeOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSqueezeOp::fold(FoldAdaptor adaptor) {
  if (auto tensorType = getOperand().getType().dyn_cast<BaseTensorType>()) {
    if (tensorType.hasSizes() && tensorType.getSizes().size() == 0)
      return getOperand();
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenSqueezeDimOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSqueezeDimOp::fold(FoldAdaptor adaptor) {
  if (auto tensorType = getOperand(0).getType().dyn_cast<BaseTensorType>()) {
    if (tensorType.hasSizes() && tensorType.getSizes().size() == 0)
      return getOperand(0);
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenRoundOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenRoundOp::fold(FoldAdaptor adaptor) {
  if (auto selfType = getSelf().getType().dyn_cast<BaseTensorType>()) {
    if (selfType.hasDtype() && selfType.getDtype().isa<mlir::IntegerType>())
      return getSelf();
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenToDtypeOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenToDtypeOp::fold(FoldAdaptor adaptor) {
  bool nonBlocking, copyArg;
  // The non_blocking arg must be `False`.
  if (!matchPattern(getNonBlocking(), m_TorchConstantBool(&nonBlocking)) ||
      nonBlocking)
    return nullptr;
  // The copy arg must be `False`.
  if (!matchPattern(getCopy(), m_TorchConstantBool(&copyArg)) || copyArg)
    return nullptr;
  // The memory_format arg must be `none`.
  if (!getMemoryFormat().getType().isa<Torch::NoneType>())
    return nullptr;

  auto inputType = getSelf().getType().cast<BaseTensorType>();
  auto resType = getType().cast<BaseTensorType>();
  // If the types aren't equal, then we can't fold.
  if (inputType != resType)
    return nullptr;
  // If the type does not have a statically known dtype, then we cannot fold.
  // For example, folding `tensor<*,unk>` to `tensor<*,unk>` would be wrong,
  // since the `unk` could be dynamically different for the operand and result.
  if (!inputType.hasDtype())
    return nullptr;
  // Fold when both the input tensor and result are of the same type.
  return getOperand(0);
}

//===----------------------------------------------------------------------===//
// AtenToDtypeLayoutOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenToDtypeLayoutOp::fold(FoldAdaptor adaptor) {
  // The pin_memory arg should be either constant `False` or `none`.
  if (!getPinMemory().getType().isa<Torch::NoneType>()) {
    bool pinMemory;
    if (!matchPattern(getPinMemory(), m_TorchConstantBool(&pinMemory)))
      return nullptr;
    else if (pinMemory)
      return nullptr;
  }

  // The non_blocking arg should be constant `False`.
  bool nonBlocking;
  if (!matchPattern(getNonBlocking(), m_TorchConstantBool(&nonBlocking)))
    return nullptr;
  else if (nonBlocking)
    return nullptr;

  // The copy arg should be constant `False`.
  bool copyArg;
  if (!matchPattern(getCopy(), m_TorchConstantBool(&copyArg)))
    return nullptr;
  else if (copyArg)
    return nullptr;

  // The device arg must be `none`.
  if (!getDevice().getType().isa<Torch::NoneType>())
    return nullptr;

  // The memory_format arg must be `none`.
  if (!getMemoryFormat().getType().isa<Torch::NoneType>())
    return nullptr;

  auto inputType = getSelf().getType().cast<BaseTensorType>();
  auto resType = getType().cast<BaseTensorType>();
  // If the types aren't equal, then we can't fold.
  if (inputType != resType)
    return nullptr;
  // If the type does not have a statically known dtype, then we cannot fold.
  // For example, folding `tensor<*,unk>` to `tensor<*,unk>` would be wrong,
  // since the `unk` could be dynamically different for the operand and result.
  if (!inputType.hasDtype())
    return nullptr;

  // The layout arg should be either `none` or `0` i.e. strided.
  if (!getLayout().getType().isa<Torch::NoneType>()) {
    int64_t tensorLayout;
    if (!matchPattern(getLayout(), m_TorchConstantInt(&tensorLayout)))
      return nullptr;
    else if (tensorLayout != torch_upstream::Layout::Strided)
      return nullptr;
  }

  // Fold when both the input tensor and result are of the same type and the
  // layout arg is strided.
  return getOperand(0);
}

void AtenToDtypeLayoutOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  // `to.dtype_layout` -> `to.device/to.dtype` if layout is none and pin memory
  // is false
  patterns.add(+[](AtenToDtypeLayoutOp op, PatternRewriter &rewriter) {
    // The pin_memory arg should be either constant `False` or `none`.
    if (!op.getPinMemory().getType().isa<Torch::NoneType>()) {
      bool pinMemory;
      if (!matchPattern(op.getPinMemory(), m_TorchConstantBool(&pinMemory)))
        return failure();
      else if (pinMemory)
        return failure();
    }

    // The layout arg should be either `none` or `0` i.e. strided.
    if (!op.getLayout().getType().isa<Torch::NoneType>()) {
      int64_t tensorLayout;
      if (!matchPattern(op.getLayout(), m_TorchConstantInt(&tensorLayout)))
        return failure();
      else if (tensorLayout != torch_upstream::Layout::Strided)
        return failure();
    }

    if (op.getDevice().getType().isa<Torch::NoneType>()) {
      // The device arg is `none`. Rewrite to to.dtype.
      AtenToDtypeOp toDtype = rewriter.create<AtenToDtypeOp>(
          op.getLoc(), op.getType(), op.getSelf(), op.getDtype(),
          op.getNonBlocking(), op.getCopy(), op.getMemoryFormat());
      rewriter.replaceOp(op, toDtype->getResults());
    } else {
      // The device arg is not `none`. Rewrite to to.device.
      AtenToDeviceOp toDevice = rewriter.create<AtenToDeviceOp>(
          op.getLoc(), op.getType(), op.getSelf(), op.getDevice(),
          op.getDtype(), op.getNonBlocking(), op.getCopy(),
          op.getMemoryFormat());
      rewriter.replaceOp(op, toDevice->getResults());
    }

    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenToOtherOp
//===----------------------------------------------------------------------===//

void AtenToOtherOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                MLIRContext *context) {
  // Canonicalize `aten.to.other` to `aten.to.device`
  patterns.add(+[](AtenToOtherOp op, PatternRewriter &rewriter) {
    auto lhs = op.getSelf();
    auto rhs = op.getOther();
    auto getRhsDevice = rewriter.create<PrimDeviceOp>(op.getLoc(), rhs);
    auto getRhsDtype = rewriter.create<PrimDtypeOp>(op.getLoc(), rhs);
                           rewriter.replaceOpWithNewOp<AtenToDeviceOp>(
                               op, op.getType(), lhs, getRhsDevice.getResult(),
                               getRhsDtype.getResult(), op.getNonBlocking(),
                               op.getCopy(), op.getMemoryFormat());
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenViewOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenViewOp::fold(FoldAdaptor adaptor) {
  auto inputType = getOperand(0).getType().dyn_cast<BaseTensorType>();
  if (!inputType || !inputType.hasSizes() || inputType.getSizes().size() != 1)
    return nullptr;
  auto resType = getType().dyn_cast<BaseTensorType>();
  if (!resType || !resType.hasSizes() || resType.getSizes().size() != 1)
    return nullptr;
  // Fold when both the input tensor and result are unity rank tensors.
  return getOperand(0);
}

//===----------------------------------------------------------------------===//
// PrimsViewOfOp
//===----------------------------------------------------------------------===//

OpFoldResult PrimsViewOfOp::fold(FoldAdaptor adaptor) {
  // Always fold the op with its only input operand.
  return getOperand();
}

//===----------------------------------------------------------------------===//
// AtenDimOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenDimOp::fold(FoldAdaptor adaptor) {
  if (auto tensorType = getOperand().getType().dyn_cast<BaseTensorType>()) {
    if (tensorType.hasSizes())
      return IntegerAttr::get(IntegerType::get(getContext(), 64),
                              tensorType.getSizes().size());
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenLenTOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenLenTOp::fold(FoldAdaptor adaptor) {
  // `len([1,1,1])` -> `3`, if it is not mutated.
  if (auto listConstruct =
          getOperand().getDefiningOp<Torch::PrimListConstructOp>()) {
    if (!isListPotentiallyMutated(listConstruct)) {
      return IntegerAttr::get(IntegerType::get(getContext(), 64),
                              listConstruct.getNumOperands());
    }
  }
  return nullptr;
}

void AtenLenTOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                             MLIRContext *context) {
  // `len(t.size())` -> `t.ndim`
  patterns.add(+[](AtenLenTOp op, PatternRewriter &rewriter) {
    auto size = op.getOperand().getDefiningOp<AtenSizeOp>();
    if (!size)
      return rewriter.notifyMatchFailure(op, "operand not AtenSizeOp");
    rewriter.replaceOpWithNewOp<AtenDimOp>(op, size.getOperand());
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenLenStrOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenLenStrOp::fold(FoldAdaptor adaptor) {
  if (auto stringConstruct = getS().getDefiningOp<ConstantStrOp>())
    return getI64IntegerAttr(getContext(),
                             stringConstruct.getValueAttr().getValue().size());

  return nullptr;
}

LogicalResult rewrite0DBinaryTensorOp(Operation *op,
                                      PatternRewriter &rewriter) {
  Location loc = op->getLoc();
  // This canonicalization pattern also includes aten div/mul/add/sub ops
  // between tensor and scalar, like aten.add.Scalar op
  if (op->getNumOperands() < 2) {
    return failure();
  }
  auto lhs = getScalarIntValue(op->getOperand(0), loc, rewriter);
  auto rhs = getScalarIntValue(op->getOperand(1), loc, rewriter);
  auto outType = op->getResult(0).getType();

  if (!lhs || !rhs) {
    return rewriter.notifyMatchFailure(
        op, "only int scalar lhs or rhs is supported");
  }
  if (isa<AtenSubTensorOp, AtenSubScalarOp, AtenRsubScalarOp, AtenAddTensorOp,
          AtenAddScalarOp>(op)) {
    Value alpha = getScalarIntValue(op->getOperand(2), loc, rewriter);
    if (!alpha) {
      return rewriter.notifyMatchFailure(op,
                                         "only int scalar alpha is supported");
    }
    if (isa<AtenRsubScalarOp>(op))
      lhs = rewriter.create<AtenMulIntOp>(loc, lhs, alpha);
    else
      rhs = rewriter.create<AtenMulIntOp>(loc, rhs, alpha);
  }

  if (isa<AtenDivTensorModeOp>(op)) {
    // None rounding mode
    if (op->getOperand(2).getType().isa<Torch::NoneType>()) {
      Value quotient = rewriter.create<AtenDivOp>(loc, lhs, rhs);
      rewriter.replaceOpWithNewOp<PrimNumToTensorScalarOp>(op, outType,
                                                           quotient);
      return success();
    }
    std::string roundingMode;
    if (!matchPattern(op->getOperand(2), m_TorchConstantStr(roundingMode))) {
      return rewriter.notifyMatchFailure(
          op, "only None, 'floor' or 'trunc' rounding mode is supported");
    }
    if (roundingMode == "floor") {
      Value quotient = rewriter.create<AtenFloordivIntOp>(loc, lhs, rhs);
      rewriter.replaceOpWithNewOp<PrimNumToTensorScalarOp>(op, outType,
                                                           quotient);
      return success();
    }
    // For "trunc" rounding mode, insted of canonicalizing it into
    // aten.abs, aten.floor, aten.sign and aten.mul.int ops, which adds
    // complexity but helps little in optimization (such as constant folding),
    // we are trying to fold it.
    if (roundingMode == "trunc") {
      int64_t lhsInt;
      int64_t rhsInt;
      if (!matchPattern(lhs, m_TorchConstantInt(&lhsInt))) {
        return failure();
      }
      if (!matchPattern(rhs, m_TorchConstantInt(&rhsInt))) {
        return failure();
      }

      int64_t result = (int64_t)std::trunc((double)lhsInt / rhsInt);
      Value resultScalar = rewriter.create<ConstantIntOp>(
          loc, rewriter.getI64IntegerAttr(result));
      rewriter.replaceOpWithNewOp<PrimNumToTensorScalarOp>(op, outType,
                                                           resultScalar);
      return success();
    }

    return failure();
  }

  Value result;
  // Other Add/Sub/Mul ops
  if (isa<AtenAddTensorOp, AtenAddScalarOp>(op)) {
    result = rewriter.create<AtenAddIntOp>(loc, lhs, rhs);
  } else if (isa<AtenSubScalarOp, AtenSubTensorOp>(op)) {
    result = rewriter.create<AtenSubIntOp>(loc, lhs, rhs);
  } else if (isa<AtenRsubScalarOp>(op)) {
    result = rewriter.create<AtenSubIntOp>(loc, rhs, lhs);
  } else if (isa<AtenMulScalarOp, AtenMulTensorOp>(op)) {
    result = rewriter.create<AtenMulIntOp>(loc, lhs, rhs);
  }
  rewriter.replaceOpWithNewOp<PrimNumToTensorScalarOp>(op, outType, result);
  return success();
}

//===----------------------------------------------------------------------===//
// AtenAddTensorOp
//===----------------------------------------------------------------------===//
void AtenAddTensorOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenAddTensorOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenAddScalarOp
//===----------------------------------------------------------------------===//
void AtenAddScalarOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenAddScalarOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenSubTensorOp
//===----------------------------------------------------------------------===//
void AtenSubTensorOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenSubTensorOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenSubScalarOp
//===----------------------------------------------------------------------===//
void AtenSubScalarOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenSubScalarOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenRSubScalarOp
//===----------------------------------------------------------------------===//
void AtenRsubScalarOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                   MLIRContext *context) {
  patterns.add(+[](AtenRsubScalarOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenMulTensorOp
//===----------------------------------------------------------------------===//
void AtenMulTensorOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenMulTensorOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenMulScalarOp
//===----------------------------------------------------------------------===//
void AtenMulScalarOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                  MLIRContext *context) {
  patterns.add(+[](AtenMulScalarOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenDivTensorModeOp
//===----------------------------------------------------------------------===//
void AtenDivTensorModeOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](AtenDivTensorModeOp op, PatternRewriter &rewriter) {
    return rewrite0DBinaryTensorOp(op, rewriter);
  });
}

//===----------------------------------------------------------------------===//
// AtenScalarImplicitOp
//===----------------------------------------------------------------------===//
void AtenScalarImplicitOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](AtenScalarImplicitOp op, PatternRewriter &rewriter) {
    Location loc = op.getLoc();
    Value a = op.getA();
    auto outType = op.getResult().getType();
    Value scalarValue = getScalarIntValue(a, loc, rewriter);
    if (!scalarValue)
      return failure();
    rewriter.replaceOpWithNewOp<Torch::DerefineOp>(op, outType, scalarValue);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenSizeOp
//===----------------------------------------------------------------------===//

// Traces at most 6 parents of `value` to determine the tensor type with known
// dimension size or returns failure if such a type was not found.  If `dim` is
// `None`, then all dimension's sizes must be known.
static FailureOr<BaseTensorType>
traceKnownSizeTensorType(Value value, std::optional<int64_t> dim) {
  // Function to check if we found a type that contains the queried information.
  auto foundType = [](BaseTensorType tensorType, std::optional<int64_t>(dim)) {
    if (!tensorType.hasSizes())
      return false;

    if (dim == std::nullopt)
      return tensorType.areAllSizesKnown();

    // If the dimension value is negative, then convert it to a positive value.
    ArrayRef<int64_t> sizes = tensorType.getSizes();
    *dim = toPositiveDim(*dim, sizes.size());
    return isValidDim(*dim, sizes.size()) && sizes[*dim] != kUnknownSize;
  };

  // Limit the loop count to 6 to avoid indefinite compilation times from
  // unbounded IR traversals.
  for (auto idx = 0; idx < 6; ++idx) {
    if (!value || !value.getType().isa<BaseTensorType>())
      return failure();

    auto tensorType = value.getType().cast<BaseTensorType>();
    if (foundType(tensorType, dim))
      return tensorType;

    auto op = value.getDefiningOp();
    if (!op || !isa<CopyToValueTensorOp, CopyToNonValueTensorOp,
                    TensorStaticInfoCastOp>(op))
      return failure();

    // In all ops of interest to us, the source tensor is operand #0.
    value = op->getOperand(0);
  }

  return failure();
}

void AtenSizeOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                             MLIRContext *context) {
  patterns.add(+[](AtenSizeOp op, PatternRewriter &rewriter) {
    auto type = traceKnownSizeTensorType(op.getOperand(), std::nullopt);
    if (failed(type))
      return rewriter.notifyMatchFailure(op, "all sizes not known");
    SmallVector<Value> listElements;
    for (int64_t size : type->getSizes()) {
      listElements.push_back(rewriter.create<Torch::ConstantIntOp>(
          op->getLoc(), rewriter.getI64IntegerAttr(size)));
    }
    rewriter.replaceOpWithNewOp<Torch::PrimListConstructOp>(
        op, Torch::ListType::get(rewriter.getType<Torch::IntType>()),
        listElements);
    return success();
  });
  // One-off pattern to erase if dead.
  // TODO: Use the effects infra to express the semantics of this op and enable
  // a centralized "erase if dead" canonicalization.
  // Specifically, we need to mark the op as only MemoryEffects::Allocate
  // so that `mlir::wouldOpBeTriviallyDead` does the right thing.
  patterns.add(+[](AtenSizeOp op, PatternRewriter &rewriter) {
    if (!op.use_empty())
      return failure();
    rewriter.eraseOp(op);
    return failure();
  });
}

//===----------------------------------------------------------------------===//
// AtenSizeIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSizeIntOp::fold(FoldAdaptor adaptor) {
  int64_t dim;
  if (!matchPattern(this->getDim(), m_TorchConstantInt(&dim)))
    return nullptr;
  auto type = traceKnownSizeTensorType(this->getSelf(), dim);
  if (failed(type))
    return nullptr;
  ArrayRef<int64_t> sizes = type->getSizes();
  dim = toPositiveDim(dim, sizes.size());
  if (!isValidDim(dim, sizes.size()))
    return nullptr;
  return IntegerAttr::get(IntegerType::get(getContext(), 64), sizes[dim]);
}

//===----------------------------------------------------------------------===//
// AtenGtIntOp
//===----------------------------------------------------------------------===//

static IntegerAttr getI1IntegerAttr(MLIRContext *context, bool value) {
  return IntegerAttr::get(IntegerType::get(context, 1),
                          static_cast<int64_t>(value));
}

using ConstantFloatComparator = std::function<bool(double, double)>;
template <typename OpTy>
static OpFoldResult
floatComparatorFoldHelper(OpTy op, ConstantFloatComparator comparator) {
  if (op.getOperand(0) == op.getOperand(1))
    return getI1IntegerAttr(op.getContext(), comparator(0, 0));

  double lhs, rhs;
  if (!matchPattern(op.getOperand(0), m_TorchConstantFloat(&lhs)) ||
      !matchPattern(op.getOperand(1), m_TorchConstantFloat(&rhs)))
    return nullptr;

  return getI1IntegerAttr(op.getContext(), comparator(lhs, rhs));
}

//===----------------------------------------------------------------------===//
// AtenLtFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenLtFloatOp::fold(FoldAdaptor adaptor) {
  return floatComparatorFoldHelper(*this,
                                   [](double a, double b) { return a < b; });
}

//===----------------------------------------------------------------------===//
// AtenGtFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenGtFloatOp::fold(FoldAdaptor adaptor) {
  return floatComparatorFoldHelper(*this,
                                   [](double a, double b) { return a > b; });
}

//===----------------------------------------------------------------------===//
// AtenGeFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenGeFloatOp::fold(FoldAdaptor adaptor) {
  return floatComparatorFoldHelper(*this,
                                   [](double a, double b) { return a >= b; });
}

//===----------------------------------------------------------------------===//
// AtenEqFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenEqFloatOp::fold(FoldAdaptor adaptor) {
  return floatComparatorFoldHelper(*this,
                                   [](double a, double b) { return a == b; });
}

using ConstantIntComparator = std::function<bool(int64_t, int64_t)>;
template <typename OpTy>
static OpFoldResult intComparatorFoldHelper(OpTy op,
                                            ConstantIntComparator comparator) {

  Value lhsValue = op->getOperand(0);
  Value rhsValue = op->getOperand(1);
  if (lhsValue == rhsValue)
    return getI1IntegerAttr(op.getContext(), comparator(0, 0));

  int64_t lhs, rhs;
  bool lhsIsConstant = matchPattern(lhsValue, m_TorchConstantInt(&lhs));
  bool rhsIsConstant = matchPattern(rhsValue, m_TorchConstantInt(&rhs));
  if (lhsIsConstant && rhsIsConstant)
    return getI1IntegerAttr(op.getContext(), comparator(lhs, rhs));

  // Ensure that if there is a constant, it is on the right.
  if (lhsIsConstant && !rhsIsConstant) {
    std::swap(lhs, rhs);
    std::swap(lhsValue, rhsValue);
    std::swap(lhsIsConstant, rhsIsConstant);
    auto newComparator = [comparator](int64_t lhs, int64_t rhs) {
      return comparator(rhs, lhs);
    };
    comparator = newComparator;
  }

  // Fold comparisons of AtenSizeIntOp against negative values.
  // AtenSizeIntOp is known to always be non-negative.
  if (rhsIsConstant && rhs < 0) {
    // We can return `comparator(0, -1)` here because of the property:
    // If x >= 0 && y < 0, then:
    // - cmp(x, y) == cmp(x + 1, y)
    // - cmp(x, y) == cmp(x, y - 1)
    // By induction all cases here are covered.
    if (auto size = lhsValue.getDefiningOp<AtenSizeIntOp>())
      return getI1IntegerAttr(op->getContext(), comparator(0, -1));
  }

  // Fold comparisons of AtenSizeIntOp against 0:
  // - torch.aten.size.int >= 0 ==> True.
  // - torch.aten.size.int < 0 ==> False.
  // (and the operand-swapped versions of the above)
  if (rhsIsConstant && rhs == 0) {
    if (auto size = lhsValue.getDefiningOp<AtenSizeIntOp>()) {
      // >= 0 comparison.
      if (comparator(0, 0) && comparator(1, 0))
        return getI1IntegerAttr(op->getContext(), true);
      // < 0 comparison.
      if (!comparator(0, 0) && comparator(-1, 0) && !comparator(1, 0))
        return getI1IntegerAttr(op->getContext(), false);
    }
  }

  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenDetachOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenDetachOp::fold(FoldAdaptor adaptor) { return getSelf(); }

//===----------------------------------------------------------------------===//
// AtenNeIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenNeIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a != b; });
}

//===----------------------------------------------------------------------===//
// AtenEqIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenEqIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a == b; });
}

//===----------------------------------------------------------------------===//
// AtenEqStrOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenEqStrOp::fold(FoldAdaptor adaptor) {
  if (getOperand(0) == getOperand(1))
    return getI1IntegerAttr(getContext(), true);

  auto aStr = getA().getDefiningOp<ConstantStrOp>();
  auto bStr = getB().getDefiningOp<ConstantStrOp>();

  if (aStr && bStr)
    return getI1IntegerAttr(getContext(), aStr == bStr);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenLtIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenLtIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a < b; });
}

//===----------------------------------------------------------------------===//
// AtenLeIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenLeIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a <= b; });
}

//===----------------------------------------------------------------------===//
// AtenGtIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenGtIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a > b; });
}

//===----------------------------------------------------------------------===//
// AtenGeIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenGeIntOp::fold(FoldAdaptor adaptor) {
  return intComparatorFoldHelper(*this,
                                 [](int64_t a, int64_t b) { return a >= b; });
}

//===----------------------------------------------------------------------===//
// AtenBoolFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenBoolFloatOp::fold(FoldAdaptor adaptor) {
  double c;
  if (matchPattern(getOperand(), m_TorchConstantFloat(&c)))
    return getI1IntegerAttr(getContext(), c != 0.0);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenBoolIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenBoolIntOp::fold(FoldAdaptor adaptor) {
  int64_t c;
  if (matchPattern(getOperand(), m_TorchConstantInt(&c)))
    return getI1IntegerAttr(getContext(), c != 0);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenAnyBoolOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenAnyBoolOp::fold(FoldAdaptor adaptor) {
  auto inputConstruct = getSelf().getDefiningOp<Torch::PrimListConstructOp>();
  if (!inputConstruct || isListPotentiallyMutated(inputConstruct))
    return nullptr;
  // If any operand is a constant true, return true.
  for (auto operand : inputConstruct.getOperands()) {
    bool b = false;
    if (matchPattern(operand, m_TorchConstantBool(&b)) && b) {
      return getI1IntegerAttr(getContext(), true);
    }
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenFloatScalarOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenFloatScalarOp::fold(FoldAdaptor adaptor) {
  // Constant fold int -> float conversion.
  if (auto integerAttr = adaptor.getA().dyn_cast_or_null<IntegerAttr>()) {
    return FloatAttr::get(
        mlir::Float64Type::get(getContext()),
        static_cast<double>(integerAttr.getValue().getSExtValue()));
  }
  // If the input is float type already, the op is an identity.
  if (getType() == getOperand().getType())
    return getOperand();
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenIntFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenIntFloatOp::fold(FoldAdaptor adaptor) {
  // Constant fold float -> int conversion.
  if (auto floatAttr = adaptor.getA().dyn_cast_or_null<FloatAttr>()) {
    return IntegerAttr::get(
        mlir::IntegerType::get(getContext(), 64),
        static_cast<int64_t>(floatAttr.getValue().convertToDouble()));
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenIntScalarOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenIntScalarOp::fold(FoldAdaptor adaptor) {
  // Constant fold float -> int conversion.
  if (auto floatAttr = adaptor.getA().dyn_cast_or_null<FloatAttr>()) {
    return IntegerAttr::get(
        mlir::IntegerType::get(getContext(), 64),
        static_cast<long>(floatAttr.getValue().convertToDouble()));
  }
  // If the input is int type already, the op is an identity.
  if (getType() == getOperand().getType())
    return getOperand();
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenIntBoolOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenIntBoolOp::fold(FoldAdaptor adaptor) {
  bool b;
  if (matchPattern(getOperand(), m_TorchConstantBool(&b))) {
    return getI64IntegerAttr(getContext(), static_cast<long>(b));
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenSortIntOp
//===----------------------------------------------------------------------===//

void AtenSortIntOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                MLIRContext *context) {
  patterns.add(+[](AtenSortIntOp op, PatternRewriter &rewriter) {
    SmallVector<int64_t> listElements;
    if (!matchPattern(op.getSelf(), m_TorchListOfConstantInts(listElements)))
      return rewriter.notifyMatchFailure(
          op, "all input list elements must be constant ints");
    bool reverse;
    if (!matchPattern(op.getReverse(), m_TorchConstantBool(&reverse)))
      return rewriter.notifyMatchFailure(
          op, "Expected reverse arg to be constant bool.");

    std::sort(listElements.begin(), listElements.end());
    if (reverse)
      std::reverse(listElements.begin(), listElements.end());

    SmallVector<Value> sortedListElements;
    for (int64_t elem : listElements)
      sortedListElements.push_back(rewriter.create<Torch::ConstantIntOp>(
          op->getLoc(), rewriter.getI64IntegerAttr(elem)));
    Value result = rewriter.create<Torch::PrimListConstructOp>(
        op->getLoc(), Torch::ListType::get(rewriter.getType<Torch::IntType>()),
        sortedListElements);

    op.getSelf().replaceAllUsesWith(result);
    rewriter.eraseOp(op);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// NonValueTensorLiteralOp
//===----------------------------------------------------------------------===//

LogicalResult NonValueTensorLiteralOp::inferReturnTypes(
    MLIRContext *context, std::optional<Location> location, ValueRange operands,
    DictionaryAttr attributes, OpaqueProperties properties, RegionRange regions,
    SmallVectorImpl<Type> &inferredReturnTypes) {
  auto attr = attributes.get("value").dyn_cast_or_null<ElementsAttr>();
  if (!attr)
    return failure();
  RankedTensorType tensorType = attr.getType().cast<RankedTensorType>();
  NonValueTensorType returnType =
      NonValueTensorType::get(tensorType.getContext(), tensorType.getShape(),
                              tensorType.getElementType());
  inferredReturnTypes.push_back(returnType);
  return success();
}

static bool areSizesAndDtypesCompatible(BaseTensorType a, BaseTensorType b) {
  if (a.hasSizes() && b.hasSizes()) {
    if (failed(verifyCompatibleShape(makeShapeLLVMCompatible(a.getSizes()),
                                     makeShapeLLVMCompatible(b.getSizes()))))
      return false;
  }
  if (a.hasDtype() && b.hasDtype()) {
    if (a.getDtype() != b.getDtype())
      return false;
  }
  return true;
}

bool NonValueTensorLiteralOp::isCompatibleReturnTypes(TypeRange inferred,
                                                      TypeRange actual) {
  if (!actual[0].isa<BaseTensorType>())
    return false;
  return areSizesAndDtypesCompatible(inferred[0].cast<BaseTensorType>(),
                                     actual[0].cast<BaseTensorType>());
}

//===----------------------------------------------------------------------===//
// ValueTensorLiteralOp
//===----------------------------------------------------------------------===//

LogicalResult ValueTensorLiteralOp::inferReturnTypes(
    MLIRContext *context, std::optional<Location> location, ValueRange operands,
    DictionaryAttr attributes, OpaqueProperties properties, RegionRange regions,
    SmallVectorImpl<Type> &inferredReturnTypes) {
  auto attr = attributes.get("value").dyn_cast_or_null<ElementsAttr>();
  if (!attr)
    return failure();
  RankedTensorType tensorType = attr.getType().cast<RankedTensorType>();
  ValueTensorType returnType =
      ValueTensorType::get(tensorType.getContext(), tensorType.getShape(),
                           tensorType.getElementType());
  inferredReturnTypes.push_back(returnType);
  return success();
}

OpFoldResult ValueTensorLiteralOp::fold(FoldAdaptor adaptor) {
  return getValueAttr();
}

//----------------------------------------------------------------------------//
// TensorStaticInfoCast
//----------------------------------------------------------------------------//

bool TensorStaticInfoCastOp::areCastCompatible(mlir::TypeRange inputs,
                                               mlir::TypeRange outputs) {
  return areSizesAndDtypesCompatible(inputs[0].cast<BaseTensorType>(),
                                     outputs[0].cast<BaseTensorType>());
}

void TensorStaticInfoCastOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](TensorStaticInfoCastOp op, PatternRewriter &rewriter) {
    auto reverseCast =
        op.getOperand().getDefiningOp<Torch::TensorStaticInfoCastOp>();
    if (!reverseCast || reverseCast.getOperand().getType() != op.getType())
      return failure();

    rewriter.replaceOp(op, reverseCast.getOperand());
    return success();
  });
  patterns.add(+[](TensorStaticInfoCastOp op, PatternRewriter &rewriter) {
    if (isValidSubtype(op.getOperand().getType(), op.getType())) {
      SmallVector<std::reference_wrapper<OpOperand>> usesToChange(
          llvm::make_filter_range(op->getUses(), [](OpOperand &operand) {
            return operand.getOwner()
                ->hasTrait<mlir::torch::Torch::OpTrait::AllowsTypeRefinement>();
          }));

      if (usesToChange.empty())
        return failure();

      for (OpOperand &use : usesToChange) {
        Operation *user = use.getOwner();
        user->setOperand(use.getOperandNumber(), op.getOperand());
      }

      return success();
    }
    return failure();
  });
}

//===----------------------------------------------------------------------===//
// CopyToNonValueTensorOp
//===----------------------------------------------------------------------===//

LogicalResult CopyToNonValueTensorOp::verify() {
  auto resultType = getResult().getType().cast<BaseTensorType>();
  auto operandType = getOperand().getType().cast<BaseTensorType>();
  if (!resultType.hasSameSizesAndDtype(operandType))
    return emitError() << "operand and result must have same sizes and dtype";
  return success();
}

LogicalResult CopyToNonValueTensorOp::inferReturnTypes(
    MLIRContext *context, std::optional<Location> location, ValueRange operands,
    DictionaryAttr attributes, OpaqueProperties properties, RegionRange regions,
    SmallVectorImpl<Type> &inferredReturnTypes) {
  auto resultType = operands[0].getType().cast<ValueTensorType>();
  inferredReturnTypes.push_back(resultType.getWithoutValueSemantics());
  return success();
}

void CopyToNonValueTensorOp::getEffects(
    SmallVectorImpl<SideEffects::EffectInstance<MemoryEffects::Effect>>
        &effects) {
  effects.emplace_back(MemoryEffects::Allocate::get(), getResult());
}

//===----------------------------------------------------------------------===//
// CopyToValueTensorOp
//===----------------------------------------------------------------------===//

LogicalResult CopyToValueTensorOp::verify() {
  auto resultType = getResult().getType().cast<BaseTensorType>();
  auto operandType = getOperand().getType().cast<BaseTensorType>();
  if (!resultType.hasSameSizesAndDtype(operandType))
    return emitError() << "operand and result must have same sizes and dtype";
  return success();
}

LogicalResult CopyToValueTensorOp::inferReturnTypes(
    MLIRContext *context, std::optional<Location> location, ValueRange operands,
    DictionaryAttr attributes, OpaqueProperties properties, RegionRange regions,
    SmallVectorImpl<Type> &inferredReturnTypes) {
  auto resultType = operands[0].getType().cast<NonValueTensorType>();
  inferredReturnTypes.push_back(resultType.getWithValueSemantics());
  return success();
}

void CopyToValueTensorOp::getEffects(
    SmallVectorImpl<SideEffects::EffectInstance<MemoryEffects::Effect>>
        &effects) {
  effects.emplace_back(MemoryEffects::Read::get(), getOperand());
}

//===----------------------------------------------------------------------===//
// ConstantNoneOp
//===----------------------------------------------------------------------===//

OpFoldResult ConstantNoneOp::fold(FoldAdaptor adaptor) {
  return TypeAttr::get(Torch::NoneType::get(getContext()));
}

void ConstantNoneOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  setNameFn(getResult(), "none");
}

//===----------------------------------------------------------------------===//
// ConstantStrOp
//===----------------------------------------------------------------------===//

OpFoldResult ConstantStrOp::fold(FoldAdaptor adaptor) { return getValueAttr(); }

void ConstantStrOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  setNameFn(getResult(), "str");
}

//===----------------------------------------------------------------------===//
// ConstantDeviceOp
//===----------------------------------------------------------------------===//

void ConstantDeviceOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  setNameFn(getResult(), getValue());
}

//===----------------------------------------------------------------------===//
// ConstantIntOp
//===----------------------------------------------------------------------===//

ParseResult ConstantIntOp::parse(OpAsmParser &parser, OperationState &result) {
  Builder builder(result.getContext());
  result.addTypes(builder.getType<Torch::IntType>());
  if (parser.parseOptionalAttrDict(result.attributes))
    return failure();
  int64_t value;
  if (parser.parseInteger(value))
    return failure();
  result.addAttribute("value", builder.getI64IntegerAttr(value));
  return success();
}

void ConstantIntOp::print(OpAsmPrinter &p) {
  p << " ";
  p << getValueAttr().getInt();
  p.printOptionalAttrDict((*this)->getAttrs(), {"value"});
}

OpFoldResult Torch::ConstantIntOp::fold(FoldAdaptor adaptor) {
  return getValueAttr();
}

void Torch::ConstantIntOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  SmallVector<char> buf;
  llvm::raw_svector_ostream os(buf);
  os << "int" << getValueAttr().getInt();
  setNameFn(getResult(), os.str());
}

//===----------------------------------------------------------------------===//
// ConstantFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult Torch::ConstantFloatOp::fold(FoldAdaptor adaptor) {
  return getValueAttr();
}

void Torch::ConstantFloatOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  // Calculate a stringified version of the number, compatible with MLIR
  // identifier syntax. (in practice, this just removes the '+' from 'e+' in
  // float string representation).
  SmallVector<char> buf;
  getValue().toString(buf, /*FormatPrecision=*/6, /*FormatMaxPadding=*/0,
                   /*TruncateZero=*/false);
  auto isValidMLIRIdentifierChar = [](char c) {
    return isalpha(c) || isdigit(c) || c == '_' || c == '$' || c == '.' ||
           c == '-';
  };
  auto numberStr = llvm::to_vector<16>(
      llvm::make_filter_range(buf, isValidMLIRIdentifierChar));

  // Construct the identifier string.
  buf.clear();
  llvm::append_range(buf, StringRef("float"));
  llvm::append_range(buf, numberStr);
  setNameFn(getResult(), StringRef(buf.data(), buf.size()));
}

//===----------------------------------------------------------------------===//
// ConstantNumberOp
//===----------------------------------------------------------------------===//

OpFoldResult Torch::ConstantNumberOp::fold(FoldAdaptor adaptor) {
  return getValueAttr();
}

void Torch::ConstantNumberOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](Torch::ConstantNumberOp op, PatternRewriter &rewriter) {
    Location loc = op->getLoc();

    Value constValue;
    Attribute value = op.getValueAttr();
    if (auto floatValue = value.dyn_cast<mlir::FloatAttr>()) {
      constValue = rewriter.create<Torch::ConstantFloatOp>(loc, floatValue);
    } else if (auto intValue = value.dyn_cast<mlir::IntegerAttr>()) {
      constValue = rewriter.create<Torch::ConstantIntOp>(loc, intValue);
    } else {
      return failure();
    }
    rewriter.replaceOpWithNewOp<Torch::DerefineOp>(op, op.getType(),
                                                   constValue);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// ConstantBoolOp
//===----------------------------------------------------------------------===//

OpFoldResult Torch::ConstantBoolOp::fold(FoldAdaptor adaptor) {
  return getValueAttr();
}

void Torch::ConstantBoolOp::getAsmResultNames(
    function_ref<void(Value, StringRef)> setNameFn) {
  setNameFn(getResult(), getValue() ? "true" : "false");
}

//===----------------------------------------------------------------------===//
// PrimUncheckedCastOp
//===----------------------------------------------------------------------===//

bool PrimUncheckedCastOp::areCastCompatible(mlir::TypeRange inputs,
                                            mlir::TypeRange outputs) {
  return isValidSubtype(outputs[0], inputs[0]);
}

OpFoldResult PrimUncheckedCastOp::fold(FoldAdaptor adaptor) {
  if (auto derefineOp = getX().getDefiningOp<Torch::DerefineOp>()) {
    if (derefineOp.getOperand().getType() == getType())
      return derefineOp.getOperand();
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// Aten__Getitem__TOp
//===----------------------------------------------------------------------===//

void Aten__Getitem__TOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](Aten__Getitem__TOp op, PatternRewriter &rewriter) {
    auto torchList = op.getOperand(0);
    if (isListPotentiallyMutated(torchList))
      return failure();

    auto listConstruct = torchList.getDefiningOp<Torch::PrimListConstructOp>();
    if (!listConstruct)
      return failure();

    // Get the index, but be careful because it might be statically invalid.
    std::optional<int64_t> indexOpt = matchLegalConstantIndexIntoListOfSize(
        op.getOperand(1), listConstruct.getNumOperands());
    if (!indexOpt)
      return rewriter.notifyMatchFailure(op, "statically invalid index");

    rewriter.replaceOp(op, {listConstruct.getOperand(*indexOpt)});
    return success();
  });
  patterns.add(+[](Aten__Getitem__TOp op, PatternRewriter &rewriter) {
    auto sizeOp = op.getList().getDefiningOp<AtenSizeOp>();
    if (!sizeOp)
      return failure();
    // This assumes tht the size doesn't change between the
    // AtenSizeOp and the Aten__Getitem__TOp.
    // `t_` is the only op I can find that changes the shape in-place. It seems
    // like otherwise we can treat the size of a tensor as having value
    // semantics. The other view-like ops don't have in-place variants --
    // they always return a new SSA value that is aliased to the input.
    // Can we have a pass to normalize the `t_` case and then elsewhere in the
    // compiler treat the size as having value semantics?
    // There's a small number of such ops, and they are marked as `inplace_view`
    // in PyTorch's `native_functions.yaml` file.
    rewriter.replaceOpWithNewOp<AtenSizeIntOp>(op, sizeOp.getSelf(), op.getIdx());
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenIsFloatingPointOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenIsFloatingPointOp::fold(FoldAdaptor adaptor) {
  auto operandType = getSelf().getType().dyn_cast<BaseTensorType>();
  if (!operandType)
    return nullptr;
  if (operandType.hasDtype()) {
    bool isFloatType = operandType.getDtype().isa<mlir::FloatType>();
    return IntegerAttr::get(IntegerType::get(getContext(), 1), isFloatType);
  }
  // doesn't has dtype
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenAddTOp
//===----------------------------------------------------------------------===//

void AtenAddTOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                             MLIRContext *context) {
  patterns.add(+[](AtenAddTOp op, PatternRewriter &rewriter) {
    auto lhsListConstruct = op.getA().getDefiningOp<Torch::PrimListConstructOp>();
    if (!lhsListConstruct || isListPotentiallyMutated(lhsListConstruct))
      return failure();

    auto rhsListConstruct = op.getB().getDefiningOp<Torch::PrimListConstructOp>();
    if (!rhsListConstruct || isListPotentiallyMutated(rhsListConstruct))
      return failure();

    SmallVector<Value> concatenatedList;
    for (auto a : lhsListConstruct.getOperands()) {
      concatenatedList.push_back(a);
    }
    for (auto b : rhsListConstruct.getOperands()) {
      concatenatedList.push_back(b);
    }

    rewriter.replaceOpWithNewOp<Torch::PrimListConstructOp>(op, op.getType(),
                                                            concatenatedList);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenSliceTOp
//===----------------------------------------------------------------------===//

void AtenSliceTOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                               MLIRContext *context) {
  patterns.add(+[](AtenSliceTOp op, PatternRewriter &rewriter) {
    auto valueList = op.getL();
    auto listConstructOp = valueList.getDefiningOp<PrimListConstructOp>();
    if (!listConstructOp || isListPotentiallyMutated(listConstructOp)) {
      return failure();
    }

    SmallVector<Value> listElements =
        llvm::to_vector<4>(listConstructOp.getElements());
    int64_t size = static_cast<int64_t>(listElements.size());

    int64_t start;
    int64_t end;
    int64_t step;
    if (op.getStart().getType().isa<Torch::NoneType>()) {
      start = 0;
    } else if (!matchPattern(op.getStart(), m_TorchConstantInt(&start))) {
      return failure();
    }
    if (op.getEnd().getType().isa<Torch::NoneType>()) {
      end = listElements.size();
    } else if (!matchPattern(op.getEnd(), m_TorchConstantInt(&end))) {
      return failure();
    }
    if (!matchPattern(op.getStep(), m_TorchConstantInt(&step))) {
      return failure();
    }

    start = start >= 0 ? start : start + size;
    start = start >= 0 ? start : 0;
    end = end >= 0 ? end : end + size;
    end = end < size ? end : size;
    SmallVector<Value> newListElements;

    for (int64_t i = start; i < end; i += step) {
      newListElements.push_back(listElements[i]);
    }

    rewriter.replaceOpWithNewOp<PrimListConstructOp>(
        op, Torch::ListType::get(listElements[0].getType()), newListElements);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenEqIntListOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenEqIntListOp::fold(FoldAdaptor adaptor) {
  auto lhsLiteral = getA().getDefiningOp<Torch::PrimListConstructOp>();
  if (!lhsLiteral)
    return nullptr;
  auto rhsLiteral = getB().getDefiningOp<Torch::PrimListConstructOp>();
  if (!rhsLiteral)
    return nullptr;

  // If the sizes don't match, then we know the lists aren't equal.
  if (lhsLiteral.getNumOperands() != rhsLiteral.getNumOperands())
    return getI1IntegerAttr(getContext(), false);

  // If the sizes match and all corresponding list elements are the same Value,
  // then we know the lists are equal.
  // Note that we can't prove that the lists are not-equal with this method,
  // since two different Value's might dynamically be equal.
  if (llvm::all_of(
          llvm::zip(lhsLiteral.getOperands(), rhsLiteral.getOperands()),
          [](const auto &pair) {
            return std::get<0>(pair) == std::get<1>(pair);
          }))
    return getI1IntegerAttr(getContext(), true);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// PrimTupleConstructOp
//===----------------------------------------------------------------------===//

LogicalResult PrimTupleConstructOp::verify() {
  if (!(isValidSubtype(
          Torch::TupleType::get(getContext(),
                                llvm::to_vector<6>(getElements().getType())),
          getResult().getType())))
    return emitOpError(
        "failed to verify that contained types correspond to operand types");
  return success();
}

//===----------------------------------------------------------------------===//
// PrimTupleIndexOp
//===----------------------------------------------------------------------===//

void PrimTupleIndexOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                   MLIRContext *context) {
  patterns.add(+[](PrimTupleIndexOp op, PatternRewriter &rewriter) {
    auto tupleConstruct = op.getTup().getDefiningOp<Torch::PrimTupleConstructOp>();
    if (!tupleConstruct)
      return failure();

    int64_t i;
    if (!matchPattern(op.getI(), m_TorchConstantInt(&i)))
      return failure();

    if (i >= (int64_t)tupleConstruct.getElements().size())
      return failure();

    // TODO: We should have a clear picture of whether we want to consistently
    // allow refinement, and where. It seems desirable to require precise
    // type equality for TupleConstruct / TupleIndex, but that might break
    // things.
    Value replacement = tupleConstruct.getElements()[i];
    if (replacement.getType() != op.getType()) {
      if (op.getType().isa<BaseTensorType>()) {
        replacement = rewriter.create<Torch::TensorStaticInfoCastOp>(
            op.getLoc(), op.getType(), replacement);
      } else {
        return failure();
      }
    }
    rewriter.replaceOp(op, replacement);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// PrimUninitializedOp
//===----------------------------------------------------------------------===//

void PrimUninitializedOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](PrimUninitializedOp op, PatternRewriter &rewriter) {
    if (!op.use_empty())
      return failure();
    rewriter.eraseOp(op);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// PrimTupleUnpackOp
//===----------------------------------------------------------------------===//

void PrimTupleUnpackOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                    MLIRContext *context) {
  patterns.add(+[](PrimTupleUnpackOp op, PatternRewriter &rewriter) {
    auto tupleConstruct = op.getTup().getDefiningOp<Torch::PrimTupleConstructOp>();
    if (!tupleConstruct)
      return failure();

    llvm::SmallVector<Value> derefinedElements;
    // The result types may be supertypes of the tuple element types.
    // Ensure we maintain the exact type, with identity `derefine`s being
    // folded.
    for (auto [type, element] :
         llvm::zip(op.getResultTypes(), tupleConstruct.getElements())) {
      derefinedElements.push_back(
          rewriter.createOrFold<DerefineOp>(op.getLoc(), type, element));
    }
    rewriter.replaceOp(op, derefinedElements);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// PrimListUnpackOp
//===----------------------------------------------------------------------===//

void PrimListUnpackOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                                   MLIRContext *context) {
  patterns.add(+[](PrimListUnpackOp op, PatternRewriter &rewriter) {
    auto torchList = op.getOperand();
    if (isListPotentiallyMutated(torchList)) {
      return failure();
    }

    auto listConstruct = torchList.getDefiningOp<Torch::PrimListConstructOp>();
    if (!listConstruct)
      return failure();

    rewriter.replaceOp(op, listConstruct.getElements());
    return success();
  });
}

static PrimDictConstructOp getDictConstructIfNotModified(Value torchDict) {
  if (!llvm::all_of(torchDict.getUsers(), [](Operation *op) {
        return isa<Aten__Getitem__DictStrOp, Aten__Contains__StrOp,
                   AtenKeysStrOp, AtenGetDefaultStrOp, PrimDictConstructOp>(op);
      }))
    return nullptr;

  return torchDict.getDefiningOp<Torch::PrimDictConstructOp>();
}

//===----------------------------------------------------------------------===//
// Aten__Getitem__DictStrOp
//===----------------------------------------------------------------------===//

OpFoldResult Aten__Getitem__DictStrOp::fold(FoldAdaptor adaptor) {
  auto dictConstruct = getDictConstructIfNotModified(getSelf());
  if (!dictConstruct)
    return nullptr;

  auto targetKey = getKey();
  for (auto i : llvm::zip(dictConstruct.getKeys(), dictConstruct.getValues())) {
    auto k = std::get<0>(i);
    if (k == targetKey)
      return std::get<1>(i);
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// Aten__Contains__StrOp
//===----------------------------------------------------------------------===//

OpFoldResult Aten__Contains__StrOp::fold(FoldAdaptor adaptor) {
  auto dictConstruct = getDictConstructIfNotModified(getDict());
  if (!dictConstruct)
    return nullptr;

  auto targetKey = getKey();
  for (auto key : dictConstruct.getKeys()) {
    if (key == targetKey)
      return getI1IntegerAttr(getContext(), true);
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// Aten__Contains__IntListOp
//===----------------------------------------------------------------------===//

static bool isListConstructNotModified(Value torchList) {
  return llvm::all_of(torchList.getUsers(), [](Operation *op) {
    return isa<Aten__Contains__IntListOp>(op);
  });
}

OpFoldResult Aten__Contains__IntListOp::fold(FoldAdaptor adaptor) {
  auto itemConstruct = getItem();
  if (!isListConstructNotModified(getL()))
    return nullptr;

  int64_t item;
  SmallVector<int64_t> list;

  if (!matchPattern(itemConstruct, m_TorchConstantInt(&item)))
    return nullptr;

  if (!matchPattern(getL(), m_TorchListOfConstantInts(list)))
    return nullptr;

  for (auto elem : list) {
    if (elem == item)
      return getI1IntegerAttr(getContext(), true);
  }
  return getI1IntegerAttr(getContext(), false);
}

using BinaryIntOperatorFn = std::function<int64_t(int64_t, int64_t)>;
static OpFoldResult
atenBinaryIntOperatorFoldHelper(ArrayRef<Attribute> operands,
                                BinaryIntOperatorFn f) {
  auto intLhs = operands[0].dyn_cast_or_null<IntegerAttr>();
  auto intRhs = operands[1].dyn_cast_or_null<IntegerAttr>();
  if (!intLhs || !intRhs) {
    return nullptr;
  }
  return IntegerAttr::get(
      intLhs.getType(),
      f(intLhs.getValue().getSExtValue(), intRhs.getValue().getSExtValue()));
}

using BinaryFloatOperatorFn = std::function<double(double, double)>;
static OpFoldResult
atenBinaryFloatOperatorFoldHelper(ArrayRef<Attribute> operands,
                                  BinaryFloatOperatorFn f) {
  double lhs, rhs;
  auto parseDoubleAttribute = [](Attribute attr, double &value) -> bool {
    if (auto intLhs = attr.dyn_cast_or_null<IntegerAttr>()) {
      value = static_cast<double>(intLhs.getValue().getSExtValue());
    } else if (auto floatLhs = attr.dyn_cast_or_null<FloatAttr>()) {
      value = floatLhs.getValue().convertToDouble();
    } else {
      return false;
    }
    return true;
  };
  if (!parseDoubleAttribute(operands[0], lhs) ||
      !parseDoubleAttribute(operands[1], rhs)) {
    return nullptr;
  }
  return getF64FloatAttr(operands[0].getContext(), f(lhs, rhs));
}

//===----------------------------------------------------------------------===//
// AtenAliasOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenAliasOp::fold(FoldAdaptor adaptor) {
  return getOperand();
}

//===----------------------------------------------------------------------===//
// AtenFloordivIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenFloordivIntOp::fold(FoldAdaptor adaptor) {
  return atenBinaryIntOperatorFoldHelper(
      adaptor.getOperands(),
      [](int64_t a, int64_t b) { return std::floor(a / (double)b); });
}

//===----------------------------------------------------------------------===//
// AtenRemainderIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenRemainderIntOp::fold(FoldAdaptor adaptor) {
  return atenBinaryIntOperatorFoldHelper(
      adaptor.getOperands(), [](int64_t a, int64_t b) { return a % b; });
}

//===----------------------------------------------------------------------===//
// AtenAddIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenAddIntOp::fold(FoldAdaptor adaptor) {
  return atenBinaryIntOperatorFoldHelper(
      adaptor.getOperands(), [](int64_t a, int64_t b) { return a + b; });
}

//===----------------------------------------------------------------------===//
// AtenSubIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSubIntOp::fold(FoldAdaptor adaptor) {
  return atenBinaryIntOperatorFoldHelper(
      adaptor.getOperands(), [](int64_t a, int64_t b) { return a - b; });
}

//===----------------------------------------------------------------------===//
// AtenCatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenCatOp::fold(FoldAdaptor adaptor) {
  auto list = getOperand(0).getDefiningOp<PrimListConstructOp>();
  if (!list || !list->hasOneUse() || list.getElements().size() != 1)
    return nullptr;
  return list.getElements()[0];
}

//===----------------------------------------------------------------------===//
// AtenStackOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenStackOp::fold(FoldAdaptor adaptor) {
  auto list = getOperand(0).getDefiningOp<PrimListConstructOp>();
  if (!list || !list->hasOneUse() || list.getElements().size() != 1)
    return nullptr;
  return list.getElements()[0];
}

//===----------------------------------------------------------------------===//
// AtenBroadcastToOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenBroadcastToOp::fold(FoldAdaptor adaptor) {
  auto inType = getOperand(0).getType().dyn_cast<BaseTensorType>();
  auto outType = getResult().getType().dyn_cast<BaseTensorType>();
  if (!inType || !outType || !inType.hasSizes() || !outType.hasSizes())
    return nullptr;
  if (inType.getSizes().size() != outType.getSizes().size() ||
      !inType.areAllSizesKnown() || !outType.areAllSizesKnown())
    return nullptr;
  for (size_t i = 0; i < inType.getSizes().size(); ++i) {
    if (inType.getSizes()[i] != outType.getSizes()[i])
      return nullptr;
  }
  return getOperand(0);
}

//===----------------------------------------------------------------------===//
// AtenSliceTensorOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSliceTensorOp::fold(FoldAdaptor adaptor) {
    int64_t start, end, step;
    if (matchPattern(getStart(), m_TorchConstantInt(&start)) &&
        matchPattern(getEnd(), m_TorchConstantInt(&end)) &&
        matchPattern(getStep(), m_TorchConstantInt(&step))
        && step == 1
        && start == 0
        && end == std::numeric_limits<int64_t>::max())
      return getOperand(0);

  auto inType = getOperand(0).getType().dyn_cast<BaseTensorType>();
  auto outType = getResult().getType().dyn_cast<BaseTensorType>();
  if (!inType || !outType || !inType.hasSizes() || !outType.hasSizes())
    return nullptr;
  if (inType.getSizes().size() != outType.getSizes().size() ||
      !inType.areAllSizesKnown() || !outType.areAllSizesKnown())
    return nullptr;
  for (size_t i = 0; i < inType.getSizes().size(); ++i) {
    if (inType.getSizes()[i] != outType.getSizes()[i])
      return nullptr;
  }
  return getOperand(0);
}

//===----------------------------------------------------------------------===//
// AtenMulIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenMulIntOp::fold(FoldAdaptor adaptor) {
  int64_t lhs, rhs;
  bool lConstant = matchPattern(getOperand(0), m_TorchConstantInt(&lhs));
  bool rConstant = matchPattern(getOperand(1), m_TorchConstantInt(&rhs));
  if ((lConstant && lhs == 0) || (rConstant && rhs == 0))
    return getI64IntegerAttr(getContext(), 0);
  if (lConstant && rConstant)
    return getI64IntegerAttr(getContext(), lhs * rhs);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenMulFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenMulFloatOp::fold(FoldAdaptor adaptor) {
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(), [](double a, double b) { return a * b; });
}

//===----------------------------------------------------------------------===//
// AtenSubFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSubFloatOp::fold(FoldAdaptor adaptor) {
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(), [](double a, double b) { return a - b; });
}

//===----------------------------------------------------------------------===//
// AtenAddOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenAddOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA() || !adaptor.getB()) {
    return nullptr;
  }

  if (adaptor.getA().isa<IntegerAttr>() && adaptor.getB().isa<IntegerAttr>()) {
    return atenBinaryIntOperatorFoldHelper(
        adaptor.getOperands(),
        [](int64_t a, int64_t b) -> int64_t { return a + b; });
  }
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(),
      [](double a, double b) -> double { return a + b; });
}

//===----------------------------------------------------------------------===//
// AtenSubOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSubOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA() || !adaptor.getB()) {
    return nullptr;
  }

  if (adaptor.getA().isa<IntegerAttr>() && adaptor.getB().isa<IntegerAttr>()) {
    return atenBinaryIntOperatorFoldHelper(
        adaptor.getOperands(),
        [](int64_t a, int64_t b) -> int64_t { return a - b; });
  }
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(),
      [](double a, double b) -> double { return a - b; });
}

//===----------------------------------------------------------------------===//
// AtenDivOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenDivOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA() || !adaptor.getB()) {
    return nullptr;
  }
  // Since AtenDivOp always returns float value, we don't need to deal with the
  // case where the operands are both integers separately.
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(),
      [](double a, double b) -> double { return a / b; });
}

//===----------------------------------------------------------------------===//
// AtenAddFloatIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenAddFloatIntOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA() || !adaptor.getB()) {
    return nullptr;
  }
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(), [](double a, double b) { return a + b; });
}

//===----------------------------------------------------------------------===//
// AtenPowIntFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenPowIntFloatOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA() || !adaptor.getB()) {
    return nullptr;
  }
  return atenBinaryFloatOperatorFoldHelper(
      adaptor.getOperands(), [](double a, double b) { return std::pow(a, b); });
}

//===----------------------------------------------------------------------===//
// AtenCeilScalarOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenCeilScalarOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA()) {
    return nullptr;
  }
  auto floatValue = adaptor.getA().dyn_cast_or_null<FloatAttr>();
  if (!floatValue) {
    return nullptr;
  }
  return getI64IntegerAttr(
      getContext(),
      static_cast<int64_t>(std::ceil(floatValue.getValue().convertToDouble())));
}

//===----------------------------------------------------------------------===//
// AtenNegIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenNegIntOp::fold(FoldAdaptor adaptor) {
  int64_t c;
  if (matchPattern(getOperand(), m_TorchConstantInt(&c)))
    return getI64IntegerAttr(getContext(), -c);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenNegFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenNegFloatOp::fold(FoldAdaptor adaptor) {
  if (!adaptor.getA()) {
    return nullptr;
  }
  auto value = adaptor.getA().dyn_cast_or_null<FloatAttr>();
  if (!value) {
    return nullptr;
  }
  return getF64FloatAttr(getContext(), -value.getValue().convertToDouble());
}

//===----------------------------------------------------------------------===//
// AtenSqrtIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenSqrtIntOp::fold(FoldAdaptor adaptor) {
  int64_t c;
  if (matchPattern(getOperand(), m_TorchConstantInt(&c)))
    return getF64FloatAttr(getContext(), std::sqrt(c));
  return nullptr;
}

//===----------------------------------------------------------------------===//
// PrimDtypeOp
//===----------------------------------------------------------------------===//

OpFoldResult PrimDtypeOp::fold(FoldAdaptor adaptor) {
  BaseTensorType tensorType = getA().getType().cast<BaseTensorType>();
  if (tensorType.hasDtype()) {
    torch_upstream::ScalarType scalarType =
        Torch::getScalarTypeForType(tensorType.getDtype());
    return getI64IntegerAttr(getContext(), static_cast<int64_t>(scalarType));
  }
  return nullptr;
}

//===----------------------------------------------------------------------===//
// PrimDeviceOp
//===----------------------------------------------------------------------===//

void PrimDeviceOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                               MLIRContext *context) {
  patterns.add(+[](PrimDeviceOp op, PatternRewriter &rewriter) {
    // Device information isn't relevant to torch-mlir, just replace it with
    // "cpu".
    rewriter.replaceOpWithNewOp<Torch::ConstantDeviceOp>(op, "cpu");
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenCudaOp
//===----------------------------------------------------------------------===//

void AtenCudaOp::getCanonicalizationPatterns(RewritePatternSet &patterns,
                                             MLIRContext *context) {
  patterns.add(+[](AtenCudaOp op, PatternRewriter &rewriter) {
    // Device information isn't relevant to torch-mlir
    auto inputTensor = op.getSelf();
    rewriter.replaceOp(op, inputTensor);
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenDeviceWithIndexOp
//===----------------------------------------------------------------------===//

void AtenDeviceWithIndexOp::getCanonicalizationPatterns(
    RewritePatternSet &patterns, MLIRContext *context) {
  patterns.add(+[](AtenDeviceWithIndexOp op, PatternRewriter &rewriter) {
    std::string type;
    int64_t index;
    if (!matchPattern(op.getType(), m_TorchConstantStr(type))) {
      return rewriter.notifyMatchFailure(
          op, "unimplemented: type must be a constant string");
    }
    if (!matchPattern(op.getIndex(), m_TorchConstantInt(&index))) {
      return rewriter.notifyMatchFailure(
          op, "unimplemented: index must be a constant integer");
    }
    rewriter.replaceOpWithNewOp<Torch::ConstantDeviceOp>(
        op, type + ":" + std::to_string(index));
    return success();
  });
}

//===----------------------------------------------------------------------===//
// AtenIntTensorOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenIntTensorOp::fold(FoldAdaptor adaptor) {
  // If a scalar number is converted to a 0-d tensor and passed on to
  // aten.Int.Tensor, fold to the scalar number.
  if (auto numToTensorScalar = getA().getDefiningOp<PrimNumToTensorScalarOp>())
    return numToTensorScalar.getA();
  if (auto tensorIntOp = getA().getDefiningOp<AtenTensorIntOp>()) 
    return tensorIntOp.getT();
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenFloatTensorOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenFloatTensorOp::fold(FoldAdaptor adaptor) {
  // If a scalar number is converted to a 0-d tensor and passed on to
  // aten.Float.Tensor, fold to the scalar number.
  if (auto numToTensorScalar = getA().getDefiningOp<PrimNumToTensorScalarOp>())
    return numToTensorScalar.getA();
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenDivFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenDivFloatOp::fold(FoldAdaptor adaptor) {
  double lhs, rhs;
  bool lConstant = matchPattern(getOperand(0), m_TorchConstantFloat(&lhs));
  bool rConstant = matchPattern(getOperand(1), m_TorchConstantFloat(&rhs));
  if (lConstant && lhs == 0.0)
    return getF64FloatAttr(getContext(), 0.0);
  if (lConstant && rConstant && rhs == 1.0)
    return getF64FloatAttr(getContext(), lhs);
  if (lConstant && rConstant)
    return getF64FloatAttr(getContext(), lhs / rhs);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenDivIntOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenDivIntOp::fold(FoldAdaptor adaptor) {
  int64_t lhs, rhs;
  bool lConstant = matchPattern(getOperand(0), m_TorchConstantInt(&lhs));
  bool rConstant = matchPattern(getOperand(1), m_TorchConstantInt(&rhs));
  if (lConstant && rConstant)
    return getF64FloatAttr(getContext(), double(lhs) / rhs);
  return nullptr;
}

//===----------------------------------------------------------------------===//
// AtenCeilFloatOp
//===----------------------------------------------------------------------===//

OpFoldResult AtenCeilFloatOp::fold(FoldAdaptor adaptor) {
  double c;
  if (matchPattern(getOperand(), m_TorchConstantFloat(&c)))
    return getI64IntegerAttr(getContext(), std::ceil(c));
  return nullptr;
}

//===----------------------------------------------------------------------===//
// PrimMaxIntOp
//===----------------------------------------------------------------------===//

OpFoldResult PrimMaxIntOp::fold(FoldAdaptor adaptor) {
  // If both operands are the same, then the operation is an identity.
  if (getA() == getB())
    return getA();

  auto lhs = adaptor.getA().dyn_cast_or_null<IntegerAttr>();
  auto rhs = adaptor.getB().dyn_cast_or_null<IntegerAttr>();
  if (!lhs || !rhs)
    return nullptr;
  // Torch semantics are that !torch.int is 64-bit signed.
  return IntegerAttr::get(
      lhs.getType(),
      std::max(lhs.getValue().getSExtValue(), rhs.getValue().getSExtValue()));
}

//===----------------------------------------------------------------------===//
// PrimMinSelfIntOp
//===----------------------------------------------------------------------===//

OpFoldResult PrimMinSelfIntOp::fold(FoldAdaptor adaptor) {
  auto list = getOperand().getDefiningOp<PrimListConstructOp>();
  if (!list)
    return nullptr;
  // TODO: What does it return for an empty list?
  if (list->getNumOperands() == 0)
    return nullptr;

  SmallVector<int64_t> values;
  for (auto operand : list->getOperands()) {
    int64_t value;
    if (!matchPattern(operand, m_TorchConstantInt(&value)))
      return nullptr;
    values.push_back(value);
  }
  return getI64IntegerAttr(getContext(),
                           *std::min_element(values.begin(), values.end()));
}

//===----------------------------------------------------------------------===//
// PrimMinIntOp
//===----------------------------------------------------------------------===//

OpFoldResult PrimMinIntOp::fold(FoldAdaptor adaptor) {
  // If both operands are the same, then the operation is an identity.
  if (getA() == getB())
    return getA();

  auto lhs = adaptor.getA().dyn_cast_or_null<IntegerAttr>();
  auto rhs = adaptor.getB().dyn_cast_or_null<IntegerAttr>();
  if (!lhs || !rhs)
    return nullptr;
  // Torch semantics are that !torch.int is 64-bit signed.
  return IntegerAttr::get(
      lhs.getType(),
      std::min(lhs.getValue().getSExtValue(), rhs.getValue().getSExtValue()));
}

//===----------------------------------------------------------------------===//
// ShapeCalculateOp
//===----------------------------------------------------------------------===//

template <typename CalculateOp>
static void
getSuccessorRegionsForCalculateOp(CalculateOp op, std::optional<unsigned> index,
                                  SmallVectorImpl<RegionSuccessor> &regions) {
  if (!index.has_value()) {
    // First thing the op does is branch into the calculation.
    regions.emplace_back(&op.getCalculation());
    return;
  }
  if (*index == 0) {
    // Body returns control to the outer op, passing through results.
    regions.emplace_back(op.getResults());
    return;
  }
  assert(*index == 1);
  // Calculation branches to the body.
  regions.emplace_back(&op.getBody());
}

void ShapeCalculateOp::getSuccessorRegions(
    std::optional<unsigned> index, SmallVectorImpl<RegionSuccessor> &regions) {
  getSuccessorRegionsForCalculateOp(*this, index, regions);
}

//===----------------------------------------------------------------------===//
// DtypeCalculateOp
//===----------------------------------------------------------------------===//

void DtypeCalculateOp::getSuccessorRegions(
    std::optional<unsigned> index, SmallVectorImpl<RegionSuccessor> &regions) {
  getSuccessorRegionsForCalculateOp(*this, index, regions);
}

//===----------------------------------------------------------------------===//
// ShapeCalculateYieldShapesOp
//===----------------------------------------------------------------------===//

MutableOperandRange ShapeCalculateYieldShapesOp::getMutableSuccessorOperands(
    std::optional<unsigned> index) {
  // The shape operands don't get forwarded to the body.
  // MutableOperandRange always has an owning operation, even if empty, so
  // create a 0-length range.
  return MutableOperandRange(*this, /*start=*/0, /*length=*/0);
}

LogicalResult ShapeCalculateYieldShapesOp::verify() {
  auto parent = cast<ShapeCalculateOp>(getOperation()->getParentOp());
  if (parent.getNumResults() != getNumOperands())
    return emitOpError("expected number of shapes to match number of results");
  return success();
}

//===----------------------------------------------------------------------===//
// DtypeCalculateYieldDtypesOp
//===----------------------------------------------------------------------===//

MutableOperandRange DtypeCalculateYieldDtypesOp::getMutableSuccessorOperands(
    std::optional<unsigned> index) {
  // The dtype operands don't get forwarded to the body.
  // MutableOperandRange always has an owning operation, even if empty, so
  // create a 0-length range.
  return MutableOperandRange(*this, /*start=*/0, /*length=*/0);
}

LogicalResult DtypeCalculateYieldDtypesOp::verify() {
  auto parent = cast<DtypeCalculateOp>(getOperation()->getParentOp());
  if (parent.getNumResults() != getNumOperands())
    return emitOpError("expected number of dtypes to match number of results");
  return success();
}

//===----------------------------------------------------------------------===//
// GlobalSlotModuleInitializerOp
//===----------------------------------------------------------------------===//

LogicalResult GlobalSlotModuleInitializerOp::verify() {
  // We centralize all verification of the global slots and the
  // InitializeGlobalSlotsOp into here, since it requires processing the whole
  // module.

  // TODO: We should really have a `torch.module` and have this initializer be
  // a region attached to it.

  ModuleOp module = cast<ModuleOp>(getOperation()->getParentOp());
  for (auto op : module.getOps<GlobalSlotModuleInitializerOp>()) {
    if (op.getOperation() != getOperation())
      return op.emitError("there must be only one global slot initializer");
  }

  // Collect the relevant symbol names we will verify.
  DenseSet</*StringAttr*/ Attribute> knownGlobalSlots;
  for (auto op : module.getOps<GlobalSlotOp>())
    knownGlobalSlots.insert(op.getSymNameAttr());
  DenseSet</*StringAttr*/ Attribute> initializedGlobalSlots;
  auto initialize = cast<InitializeGlobalSlotsOp>(getBody()->getTerminator());
  for (Attribute symName : initialize.getSlotSymNames()) {
    auto wasInserted = initializedGlobalSlots
                           .insert(symName.cast<FlatSymbolRefAttr>().getAttr())
                           .second;
    if (!wasInserted)
      return initialize.emitError("duplicate initialization of global slot: ")
             << symName;
  }
  auto lessThanByStringValue = [](Attribute lhs, Attribute rhs) {
    return lhs.cast<StringAttr>().getValue() <
           rhs.cast<StringAttr>().getValue();
  };
  auto known = llvm::to_vector(knownGlobalSlots);
  llvm::sort(known, lessThanByStringValue);
  auto initialized = llvm::to_vector(initializedGlobalSlots);
  llvm::sort(initialized, lessThanByStringValue);

  // Check that the global slots in the module are all initialized.
  SymbolTable symbolTable(module);
  if (initializedGlobalSlots != knownGlobalSlots) {
    InFlightDiagnostic diag = initialize.emitOpError(
        "must have one initializer for each global slot in the module");
    for (auto knownGlobalSlot : known) {
      auto symName = FlatSymbolRefAttr::get(knownGlobalSlot.cast<StringAttr>());
      if (!initializedGlobalSlots.count(knownGlobalSlot)) {
        diag.attachNote(
                symbolTable.lookup<GlobalSlotOp>(symName.getAttr()).getLoc())
            .append("missing global slot initializer for ", symName);
      }
    }
    for (auto initializedGlobalSlot : initialized) {
      if (!knownGlobalSlots.count(initializedGlobalSlot)) {
        diag.attachNote().append(
            "unexpected global slot initializer for non-existent global slot ",
            FlatSymbolRefAttr::get(initializedGlobalSlot.cast<StringAttr>()));
      }
    }
    return diag;
  }

  // Check that initial values satisfy type bounds.
  for (int i = 0, e = initialize.getNumOperands(); i < e; ++i) {
    auto symName = initialize.getSlotSymNames()[i].cast<FlatSymbolRefAttr>();
    auto initialValue = initialize.getOperand(i);
    auto globalSlotOp = symbolTable.lookup<GlobalSlotOp>(symName.getValue());
    if (!isValidSubtype(initialValue.getType(), globalSlotOp.getTypeBound())) {
      return initialize.emitOpError().append(
          "initial value for global slot ", symName, " has type ",
          initialValue.getType(), " which is not within the bound ",
          globalSlotOp.getTypeBound());
    }
  }

  auto walkResult = getOperation()->walk([](Operation *op) {
    // We only permit a small set of ops in the module initializer.
    // These ops are essentially those which can be produced by the IValue
    // importer.
    if (op->hasTrait<mlir::torch::Torch::OpTrait::AllowedInModuleInitializer>())
      return WalkResult::advance();
    op->emitOpError() << "is not allowed in a module initializer";
    return WalkResult::interrupt();
  });
  if (walkResult.wasInterrupted())
    return failure();

  return success();
}

//===----------------------------------------------------------------------===//
// InitializeGlobalSlotsOp
//===----------------------------------------------------------------------===//

ParseResult InitializeGlobalSlotsOp::parse(OpAsmParser &parser,
                                           OperationState &result) {
  if (parser.parseOptionalAttrDict(result.attributes))
    return failure();
  if (parser.parseLSquare())
    return failure();
  SmallVector<Attribute> slotSymNames;
  while (!succeeded(parser.parseOptionalRSquare())) {
    NamedAttrList dummy;
    StringAttr slotSymName;
    if (parser.parseSymbolName(slotSymName, "dummy", dummy))
      return failure();
    slotSymNames.push_back(FlatSymbolRefAttr::get(slotSymName));
    if (parser.parseLParen())
      return failure();
    OpAsmParser::UnresolvedOperand initialValue;
    if (parser.parseOperand(initialValue))
      return failure();
    Type initialValueType;
    if (parser.parseColonType(initialValueType))
      return failure();
    if (parser.parseRParen())
      return failure();
    if (parser.resolveOperand(initialValue, initialValueType, result.operands))
      return failure();
  }
  result.addAttribute("slotSymNames",
                      ArrayAttr::get(parser.getContext(), slotSymNames));
  return success();
}

void InitializeGlobalSlotsOp::print(OpAsmPrinter &p) {
  p.printOptionalAttrDict(getOperation()->getAttrs(),
                          /*elidedAttrs=*/{"slotSymNames"});
  p << " [";
  p.printNewline();
  for (int i = 0, e = getNumOperands(); i < e; ++i) {
    p << "  " << getSlotSymNames()[i] << "(" << getInitialValues()[i] << " : "
      << getInitialValues()[i].getType() << ")";
    p.printNewline();
  }
  p << "]";
}

LogicalResult InitializeGlobalSlotsOp::verify() {
  if (getInitialValues().size() != getSlotSymNames().size())
    return emitOpError("expected number of operands to match number of slots");
  return success();
}