neuralnetworks/aidl/vts/functional/ValidateModel.cpp

/*
 * Copyright (C) 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define LOG_TAG "neuralnetworks_aidl_hal_test"

#include <aidl/android/hardware/common/NativeHandle.h>
#include <android/binder_auto_utils.h>
#include <android/binder_enums.h>
#include <android/binder_interface_utils.h>
#include <nnapi/TypeUtils.h>
#include <nnapi/hal/aidl/Conversions.h>
#include <nnapi/hal/aidl/Utils.h>

#include <optional>
#include <type_traits>
#include <utility>

#include "Callbacks.h"
#include "GeneratedTestHarness.h"
#include "Utils.h"
#include "VtsHalNeuralnetworks.h"

namespace aidl::android::hardware::neuralnetworks::vts::functional {

using common::NativeHandle;
using implementation::PreparedModelCallback;

using PrepareModelMutation = std::function<void(Model*, ExecutionPreference*, Priority*)>;

///////////////////////// UTILITY FUNCTIONS /////////////////////////

static void validateGetSupportedOperations(const std::shared_ptr<IDevice>& device,
                                           const std::string& message, const Model& model) {
    SCOPED_TRACE(message + " [getSupportedOperations]");

    std::vector<bool> supported;
    const auto retStatus = device->getSupportedOperations(model, &supported);

    ASSERT_FALSE(retStatus.isOk());
    ASSERT_EQ(retStatus.getExceptionCode(), EX_SERVICE_SPECIFIC);
    ASSERT_EQ(static_cast<ErrorStatus>(retStatus.getServiceSpecificError()),
              ErrorStatus::INVALID_ARGUMENT);
}

static void validatePrepareModel(const std::shared_ptr<IDevice>& device, const std::string& message,
                                 const Model& model, ExecutionPreference preference,
                                 Priority priority) {
    SCOPED_TRACE(message + " [prepareModel]");

    std::shared_ptr<PreparedModelCallback> preparedModelCallback =
            ndk::SharedRefBase::make<PreparedModelCallback>();
    const auto prepareLaunchStatus =
            device->prepareModel(model, preference, priority, kNoDeadline, {}, {}, kEmptyCacheToken,
                                 preparedModelCallback);
    ASSERT_FALSE(prepareLaunchStatus.isOk());
    ASSERT_EQ(prepareLaunchStatus.getExceptionCode(), EX_SERVICE_SPECIFIC);
    ASSERT_EQ(static_cast<ErrorStatus>(prepareLaunchStatus.getServiceSpecificError()),
              ErrorStatus::INVALID_ARGUMENT);

    preparedModelCallback->wait();
    ErrorStatus prepareReturnStatus = preparedModelCallback->getStatus();
    ASSERT_EQ(ErrorStatus::INVALID_ARGUMENT, prepareReturnStatus);
    std::shared_ptr<IPreparedModel> preparedModel = preparedModelCallback->getPreparedModel();
    ASSERT_EQ(nullptr, preparedModel.get());
}

static bool validExecutionPreference(ExecutionPreference preference) {
    return preference == ExecutionPreference::LOW_POWER ||
           preference == ExecutionPreference::FAST_SINGLE_ANSWER ||
           preference == ExecutionPreference::SUSTAINED_SPEED;
}

static bool validExecutionPriority(Priority priority) {
    return priority == Priority::LOW || priority == Priority::MEDIUM || priority == Priority::HIGH;
}

// Primary validation function. This function will take a valid model, apply a
// mutation to invalidate the model, the execution preference, or the priority,
// then pass these to supportedOperations and/or prepareModel if that method is
// called with an invalid argument.
static void validate(const std::shared_ptr<IDevice>& device, const std::string& message,
                     const Model& originalModel, const PrepareModelMutation& mutate) {
    Model model = utils::clone(originalModel).value();
    ExecutionPreference preference = ExecutionPreference::FAST_SINGLE_ANSWER;
    Priority priority = kDefaultPriority;
    mutate(&model, &preference, &priority);

    if (validExecutionPreference(preference) && validExecutionPriority(priority)) {
        validateGetSupportedOperations(device, message, model);
    }

    validatePrepareModel(device, message, model, preference, priority);
}

static uint32_t addOperand(Model* model) {
    model->main.operands.push_back({
            .type = OperandType::INT32,
            .dimensions = {},
            .scale = 0.0f,
            .zeroPoint = 0,
            .lifetime = OperandLifeTime::SUBGRAPH_INPUT,
            .location = {.poolIndex = 0, .offset = 0, .length = 0},
    });
    return model->main.operands.size() - 1;
}

static uint32_t addOperand(Model* model, OperandLifeTime lifetime) {
    uint32_t index = addOperand(model);
    model->main.operands[index].lifetime = lifetime;
    return index;
}

// If we introduce a CONSTANT_COPY for an operand of size operandSize,
// how much will this increase the size of the model?  This assumes
// that we can (re)use all of model.operandValues for the operand
// value.
static size_t constantCopyExtraSize(const Model& model, size_t operandSize) {
    const size_t operandValuesSize = model.operandValues.size();
    return (operandValuesSize < operandSize) ? (operandSize - operandValuesSize) : 0;
}

// Highly specialized utility routine for converting an operand to
// CONSTANT_COPY lifetime.
//
// Expects that:
// - operand has a known size
// - operand->lifetime has already been set to CONSTANT_COPY
// - operand->location has been zeroed out
//
// Does the following:
// - initializes operand->location to point to the beginning of model->operandValues
// - resizes model->operandValues (if necessary) to be large enough for the operand
//   value, padding it with zeroes on the end
//
// Potential problem:
// By changing the operand to CONSTANT_COPY lifetime, this function is effectively initializing the
// operand with unspecified (but deterministic) data. This means that the model may be invalidated
// in two ways: not only is the lifetime of CONSTANT_COPY invalid, but the operand's value in the
// graph may also be invalid (e.g., if the operand is used as an activation code and has an invalid
// value). For now, this should be fine because it just means we're not testing what we think we're
// testing in certain cases; but we can handwave this and assume we're probabilistically likely to
// exercise the validation code over the span of the entire test set and operand space.
//
// Aborts if the specified operand type is an extension type or OEM type.
static void becomeConstantCopy(Model* model, Operand* operand) {
    // sizeOfData will abort if the specified type is an extension type or OEM type.
    const size_t sizeOfOperand = sizeOfData(*operand);
    EXPECT_NE(sizeOfOperand, size_t(0));
    operand->location.poolIndex = 0;
    operand->location.offset = 0;
    operand->location.length = sizeOfOperand;
    if (model->operandValues.size() < sizeOfOperand) {
        model->operandValues.resize(sizeOfOperand);
    }
}

// The sizeForBinder() functions estimate the size of the
// representation of a value when sent to binder.  It's probably a bit
// of an under-estimate, because we don't know the size of the
// metadata in the binder format (e.g., representation of the size of
// a vector); but at least it adds up "big" things like vector
// contents.  However, it doesn't treat inter-field or end-of-struct
// padding in a methodical way -- there's no attempt to be consistent
// in whether or not padding in the native (C++) representation
// contributes to the estimated size for the binder representation;
// and there's no attempt to understand what padding (if any) is
// needed in the binder representation.
//
// This assumes that non-metadata uses a fixed length encoding (e.g.,
// a uint32_t is always encoded in sizeof(uint32_t) bytes, rather than
// using an encoding whose length is related to the magnitude of the
// encoded value).

template <typename Type>
static size_t sizeForBinder(const Type& val) {
    static_assert(std::is_trivially_copyable_v<std::remove_reference_t<Type>>,
                  "expected a trivially copyable type");
    return sizeof(val);
}

template <typename Type>
static size_t sizeForBinder(const std::vector<Type>& vec) {
    return std::accumulate(vec.begin(), vec.end(), 0,
                           [](size_t acc, const Type& x) { return acc + sizeForBinder(x); });
}

template <>
size_t sizeForBinder(const SymmPerChannelQuantParams& symmPerChannelQuantParams) {
    size_t size = 0;

    size += sizeForBinder(symmPerChannelQuantParams.scales);
    size += sizeForBinder(symmPerChannelQuantParams.channelDim);

    return size;
}

template <>
size_t sizeForBinder(const std::optional<OperandExtraParams>& optionalExtraParams) {
    if (!optionalExtraParams.has_value()) {
        return 0;
    }
    const auto& extraParams = optionalExtraParams.value();
    using Tag = OperandExtraParams::Tag;
    switch (extraParams.getTag()) {
        case Tag::channelQuant:
            return sizeForBinder(extraParams.get<Tag::channelQuant>());
        case Tag::extension:
            return sizeForBinder(extraParams.get<Tag::extension>());
    }
    LOG(FATAL) << "Unrecognized extraParams tag: " << static_cast<int>(extraParams.getTag());
    return 0;
}

template <>
size_t sizeForBinder(const Operand& operand) {
    size_t size = 0;

    size += sizeForBinder(operand.type);
    size += sizeForBinder(operand.dimensions);
    size += sizeForBinder(operand.scale);
    size += sizeForBinder(operand.zeroPoint);
    size += sizeForBinder(operand.lifetime);
    size += sizeForBinder(operand.location);
    size += sizeForBinder(operand.extraParams);

    return size;
}

template <>
size_t sizeForBinder(const Operation& operation) {
    size_t size = 0;

    size += sizeForBinder(operation.type);
    size += sizeForBinder(operation.inputs);
    size += sizeForBinder(operation.outputs);

    return size;
}

template <>
size_t sizeForBinder(const std::string& name) {
    return name.size();
}

template <>
size_t sizeForBinder(const Memory& memory) {
    // This is just a guess.

    size_t size = 0;
    const NativeHandle& handle = memory.handle;
    size += sizeof(decltype(handle.fds)::value_type) * handle.fds.size();
    size += sizeof(decltype(handle.ints)::value_type) * handle.ints.size();
    size += sizeForBinder(memory.name);
    size += sizeof(memory);

    return size;
}

template <>
size_t sizeForBinder(const Subgraph& subgraph) {
    size_t size = 0;

    size += sizeForBinder(subgraph.operands);
    size += sizeForBinder(subgraph.operations);
    size += sizeForBinder(subgraph.inputIndexes);
    size += sizeForBinder(subgraph.outputIndexes);

    return size;
}

template <>
size_t sizeForBinder(const ExtensionNameAndPrefix& extensionNameToPrefix) {
    size_t size = 0;

    size += sizeForBinder(extensionNameToPrefix.name);
    size += sizeForBinder(extensionNameToPrefix.prefix);

    return size;
}

template <>
size_t sizeForBinder(const Model& model) {
    size_t size = 0;

    size += sizeForBinder(model.main);
    size += sizeForBinder(model.referenced);
    size += sizeForBinder(model.operandValues);
    size += sizeForBinder(model.pools);
    size += sizeForBinder(model.relaxComputationFloat32toFloat16);
    size += sizeForBinder(model.extensionNameToPrefix);

    return size;
}

// https://developer.android.com/reference/android/os/TransactionTooLargeException.html
//
//     "The Binder transaction buffer has a limited fixed size,
//     currently 1Mb, which is shared by all transactions in progress
//     for the process."
//
// Will our representation fit under this limit?  There are two complications:
// - Our representation size is just approximate (see sizeForBinder()).
// - This object may not be the only occupant of the Binder transaction buffer.
// So we'll be very conservative: We want the representation size to be no
// larger than half the transaction buffer size.
//
// If our representation grows large enough that it still fits within
// the transaction buffer but combined with other transactions may
// exceed the buffer size, then we may see intermittent HAL transport
// errors.
static bool exceedsBinderSizeLimit(size_t representationSize) {
    // Instead of using this fixed buffer size, we might instead be able to use
    // ProcessState::self()->getMmapSize(). However, this has a potential
    // problem: The binder/mmap size of the current process does not necessarily
    // indicate the binder/mmap size of the service (i.e., the other process).
    // The only way it would be a good indication is if both the current process
    // and the service use the default size.
    static const size_t kHalfBufferSize = 1024 * 1024 / 2;

    return representationSize > kHalfBufferSize;
}

///////////////////////// VALIDATE EXECUTION ORDER ////////////////////////////

static void mutateExecutionOrderTest(const std::shared_ptr<IDevice>& device, const Model& model,
                                     const std::vector<uint32_t>& numberOfConsumers) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        const Operation& operationObj = model.main.operations[operation];
        for (uint32_t input : operationObj.inputs) {
            if (model.main.operands[input].lifetime == OperandLifeTime::TEMPORARY_VARIABLE ||
                model.main.operands[input].lifetime == OperandLifeTime::SUBGRAPH_OUTPUT) {
                // This operation reads an operand written by some
                // other operation.  Move this operation to the
                // beginning of the sequence, ensuring that it reads
                // the operand before that operand is written, thereby
                // violating execution order rules.
                const std::string message = "mutateExecutionOrderTest: operation " +
                                            std::to_string(operation) + " is a reader";
                validate(device, message, model,
                         [operation](Model* model, ExecutionPreference*, Priority*) {
                             auto& operations = model->main.operations;
                             std::rotate(operations.begin(), operations.begin() + operation,
                                         operations.begin() + operation + 1);
                         });
                break;  // only need to do this once per operation
            }
        }
        for (uint32_t output : operationObj.outputs) {
            if (numberOfConsumers[output] > 0) {
                // This operation writes an operand read by some other
                // operation.  Move this operation to the end of the
                // sequence, ensuring that it writes the operand after
                // that operand is read, thereby violating execution
                // order rules.
                const std::string message = "mutateExecutionOrderTest: operation " +
                                            std::to_string(operation) + " is a writer";
                validate(device, message, model,
                         [operation](Model* model, ExecutionPreference*, Priority*) {
                             auto& operations = model->main.operations;
                             std::rotate(operations.begin() + operation,
                                         operations.begin() + operation + 1, operations.end());
                         });
                break;  // only need to do this once per operation
            }
        }
    }
}

///////////////////////// VALIDATE MODEL OPERAND TYPE /////////////////////////

static const int32_t invalidOperandTypes[] = {
        -1,
        static_cast<int32_t>(*(ndk::enum_range<OperandType>().end() - 1)) + 1,
};

static void mutateOperandTypeTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        for (int32_t invalidOperandType : invalidOperandTypes) {
            const std::string message = "mutateOperandTypeTest: operand " +
                                        std::to_string(operand) + " set to value " +
                                        std::to_string(invalidOperandType);
            validate(device, message, model,
                     [operand, invalidOperandType](Model* model, ExecutionPreference*, Priority*) {
                         model->main.operands[operand].type =
                                 static_cast<OperandType>(invalidOperandType);
                     });
        }
    }
}

///////////////////////// VALIDATE OPERAND RANK /////////////////////////

static uint32_t getInvalidRank(OperandType type) {
    switch (type) {
        case OperandType::FLOAT16:
        case OperandType::FLOAT32:
        case OperandType::INT32:
        case OperandType::UINT32:
        case OperandType::BOOL:
            return 1;
        case OperandType::TENSOR_BOOL8:
        case OperandType::TENSOR_FLOAT16:
        case OperandType::TENSOR_FLOAT32:
        case OperandType::TENSOR_INT32:
        case OperandType::TENSOR_QUANT8_ASYMM:
        case OperandType::TENSOR_QUANT8_SYMM:
        case OperandType::TENSOR_QUANT16_ASYMM:
        case OperandType::TENSOR_QUANT16_SYMM:
        case OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL:
            return 0;
        default:
            return 0;
    }
}

static void mutateOperandRankTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        const uint32_t invalidRank = getInvalidRank(model.main.operands[operand].type);
        if (invalidRank == 0) {
            continue;
        }
        const std::string message = "mutateOperandRankTest: operand " + std::to_string(operand) +
                                    " has rank of " + std::to_string(invalidRank);
        validate(device, message, model,
                 [operand, invalidRank](Model* model, ExecutionPreference*, Priority*) {
                     model->main.operands[operand].dimensions =
                             std::vector<int32_t>(invalidRank, 0);
                 });
    }
}

///////////////////////// VALIDATE OPERAND SCALE /////////////////////////

static float getInvalidScale(OperandType type) {
    switch (type) {
        case OperandType::FLOAT16:
        case OperandType::FLOAT32:
        case OperandType::INT32:
        case OperandType::UINT32:
        case OperandType::BOOL:
        case OperandType::TENSOR_BOOL8:
        case OperandType::TENSOR_FLOAT16:
        case OperandType::TENSOR_FLOAT32:
        case OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL:
        case OperandType::SUBGRAPH:
            return 1.0f;
        case OperandType::TENSOR_INT32:
            return -1.0f;
        case OperandType::TENSOR_QUANT8_SYMM:
        case OperandType::TENSOR_QUANT8_ASYMM:
        case OperandType::TENSOR_QUANT16_ASYMM:
        case OperandType::TENSOR_QUANT16_SYMM:
            return 0.0f;
        default:
            return 0.0f;
    }
}

static void mutateOperandScaleTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        const float invalidScale = getInvalidScale(model.main.operands[operand].type);
        const std::string message = "mutateOperandScaleTest: operand " + std::to_string(operand) +
                                    " has scale of " + std::to_string(invalidScale);
        validate(device, message, model,
                 [operand, invalidScale](Model* model, ExecutionPreference*, Priority*) {
                     model->main.operands[operand].scale = invalidScale;
                 });
    }
}

///////////////////////// VALIDATE OPERAND ZERO POINT /////////////////////////

static std::vector<int32_t> getInvalidZeroPoints(OperandType type) {
    switch (type) {
        case OperandType::FLOAT16:
        case OperandType::FLOAT32:
        case OperandType::INT32:
        case OperandType::UINT32:
        case OperandType::BOOL:
        case OperandType::TENSOR_BOOL8:
        case OperandType::TENSOR_FLOAT16:
        case OperandType::TENSOR_FLOAT32:
        case OperandType::TENSOR_INT32:
        case OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL:
        case OperandType::SUBGRAPH:
            return {1};
        case OperandType::TENSOR_QUANT8_ASYMM:
            return {-1, 256};
        case OperandType::TENSOR_QUANT8_SYMM:
            return {-129, -1, 1, 128};
        case OperandType::TENSOR_QUANT16_ASYMM:
            return {-1, 65536};
        case OperandType::TENSOR_QUANT16_SYMM:
            return {-32769, -1, 1, 32768};
        default:
            return {};
    }
}

static void mutateOperandZeroPointTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        const std::vector<int32_t> invalidZeroPoints =
                getInvalidZeroPoints(model.main.operands[operand].type);
        for (int32_t invalidZeroPoint : invalidZeroPoints) {
            const std::string message = "mutateOperandZeroPointTest: operand " +
                                        std::to_string(operand) + " has zero point of " +
                                        std::to_string(invalidZeroPoint);
            validate(device, message, model,
                     [operand, invalidZeroPoint](Model* model, ExecutionPreference*, Priority*) {
                         model->main.operands[operand].zeroPoint = invalidZeroPoint;
                     });
        }
    }
}

///////////////////////// VALIDATE OPERAND LIFETIME /////////////////////////////////////////////

static std::vector<OperandLifeTime> getInvalidLifeTimes(const Model& model, size_t modelSize,
                                                        const Operand& operand) {
    // TODO: Support OperandLifeTime::CONSTANT_REFERENCE as an invalid lifetime
    // TODO: Support OperandLifeTime::NO_VALUE as an invalid lifetime

    // Ways to get an invalid lifetime:
    // - change whether a lifetime means an operand should have a writer
    std::vector<OperandLifeTime> ret;
    switch (operand.lifetime) {
        case OperandLifeTime::SUBGRAPH_OUTPUT:
        case OperandLifeTime::TEMPORARY_VARIABLE:
            ret = {
                    OperandLifeTime::SUBGRAPH_INPUT,
                    OperandLifeTime::CONSTANT_COPY,
            };
            break;
        case OperandLifeTime::CONSTANT_COPY:
        case OperandLifeTime::CONSTANT_POOL:
        case OperandLifeTime::SUBGRAPH_INPUT:
            ret = {
                    OperandLifeTime::TEMPORARY_VARIABLE,
                    OperandLifeTime::SUBGRAPH_OUTPUT,
            };
            break;
        case OperandLifeTime::NO_VALUE:
            // Not enough information to know whether
            // TEMPORARY_VARIABLE or CONSTANT_COPY would be invalid --
            // is this operand written (then CONSTANT_COPY would be
            // invalid) or not (then TEMPORARY_VARIABLE would be
            // invalid)?
            break;
        case OperandLifeTime::SUBGRAPH:
            break;
        default:
            ADD_FAILURE();
            break;
    }

    const size_t operandSize = sizeOfData(operand);  // will be zero if shape is unknown
    if (!operandSize ||
        exceedsBinderSizeLimit(modelSize + constantCopyExtraSize(model, operandSize))) {
        // Unknown size or too-large size
        ret.erase(std::remove(ret.begin(), ret.end(), OperandLifeTime::CONSTANT_COPY), ret.end());
    }

    return ret;
}

static void mutateOperandLifeTimeTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    const size_t modelSize = sizeForBinder(model);
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        const std::vector<OperandLifeTime> invalidLifeTimes =
                getInvalidLifeTimes(model, modelSize, model.main.operands[operand]);
        for (OperandLifeTime invalidLifeTime : invalidLifeTimes) {
            const std::string message = "mutateOperandLifetimeTest: operand " +
                                        std::to_string(operand) + " has lifetime " +
                                        toString(invalidLifeTime) + " instead of lifetime " +
                                        toString(model.main.operands[operand].lifetime);
            validate(device, message, model,
                     [operand, invalidLifeTime](Model* model, ExecutionPreference*, Priority*) {
                         static const DataLocation kZeroDataLocation = {};
                         Operand& operandObj = model->main.operands[operand];
                         switch (operandObj.lifetime) {
                             case OperandLifeTime::SUBGRAPH_INPUT: {
                                 auto& inputs = model->main.inputIndexes;
                                 inputs.erase(std::remove(inputs.begin(), inputs.end(), operand),
                                              inputs.end());
                                 break;
                             }
                             case OperandLifeTime::SUBGRAPH_OUTPUT: {
                                 auto& outputs = model->main.outputIndexes;
                                 outputs.erase(std::remove(outputs.begin(), outputs.end(), operand),
                                               outputs.end());
                                 break;
                             }
                             default:
                                 break;
                         }
                         operandObj.lifetime = invalidLifeTime;
                         operandObj.location = kZeroDataLocation;
                         switch (invalidLifeTime) {
                             case OperandLifeTime::CONSTANT_COPY: {
                                 becomeConstantCopy(model, &operandObj);
                                 break;
                             }
                             case OperandLifeTime::SUBGRAPH_INPUT:
                                 model->main.inputIndexes.push_back(operand);
                                 break;
                             case OperandLifeTime::SUBGRAPH_OUTPUT:
                                 model->main.outputIndexes.push_back(operand);
                                 break;
                             default:
                                 break;
                         }
                     });
        }
    }
}

///////////////////////// VALIDATE OPERAND INPUT-or-OUTPUT //////////////////////////////////////

static std::optional<OperandLifeTime> getInputOutputLifeTime(const Model& model, size_t modelSize,
                                                             const Operand& operand) {
    // Ways to get an invalid lifetime (with respect to model inputIndexes and outputIndexes):
    // - change whether a lifetime means an operand is a model input, a model output, or neither
    // - preserve whether or not a lifetime means an operand should have a writer
    switch (operand.lifetime) {
        case OperandLifeTime::CONSTANT_COPY:
        case OperandLifeTime::CONSTANT_POOL:
            return OperandLifeTime::SUBGRAPH_INPUT;
        case OperandLifeTime::SUBGRAPH_INPUT: {
            const size_t operandSize = sizeOfData(operand);  // will be zero if shape is unknown
            if (!operandSize ||
                exceedsBinderSizeLimit(modelSize + constantCopyExtraSize(model, operandSize))) {
                // Unknown size or too-large size
                break;
            }
            return OperandLifeTime::CONSTANT_COPY;
        }
        case OperandLifeTime::SUBGRAPH_OUTPUT:
            return OperandLifeTime::TEMPORARY_VARIABLE;
        case OperandLifeTime::TEMPORARY_VARIABLE:
            return OperandLifeTime::SUBGRAPH_OUTPUT;
        case OperandLifeTime::NO_VALUE:
            // Not enough information to know whether
            // TEMPORARY_VARIABLE or CONSTANT_COPY would be an
            // appropriate choice -- is this operand written (then
            // TEMPORARY_VARIABLE would be appropriate) or not (then
            // CONSTANT_COPY would be appropriate)?
            break;
        case OperandLifeTime::SUBGRAPH:
            break;
        default:
            ADD_FAILURE();
            break;
    }

    return std::nullopt;
}

static void mutateOperandInputOutputTest(const std::shared_ptr<IDevice>& device,
                                         const Model& model) {
    const size_t modelSize = sizeForBinder(model);
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        const std::optional<OperandLifeTime> changedLifeTime =
                getInputOutputLifeTime(model, modelSize, model.main.operands[operand]);
        if (changedLifeTime) {
            const std::string message = "mutateOperandInputOutputTest: operand " +
                                        std::to_string(operand) + " has lifetime " +
                                        toString(*changedLifeTime) + " instead of lifetime " +
                                        toString(model.main.operands[operand].lifetime);
            validate(device, message, model,
                     [operand, changedLifeTime](Model* model, ExecutionPreference*, Priority*) {
                         static const DataLocation kZeroDataLocation = {};
                         Operand& operandObj = model->main.operands[operand];
                         operandObj.lifetime = *changedLifeTime;
                         operandObj.location = kZeroDataLocation;
                         if (*changedLifeTime == OperandLifeTime::CONSTANT_COPY) {
                             becomeConstantCopy(model, &operandObj);
                         }
                     });
        }
    }
}

///////////////////////// VALIDATE OPERAND NUMBER OF WRITERS ////////////////////////////////////

static void mutateOperandAddWriterTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        for (size_t badOutputNum = 0;
             badOutputNum < model.main.operations[operation].outputs.size(); ++badOutputNum) {
            const uint32_t outputOperandIndex =
                    model.main.operations[operation].outputs[badOutputNum];
            const std::string message = "mutateOperandAddWriterTest: operation " +
                                        std::to_string(operation) + " writes to " +
                                        std::to_string(outputOperandIndex);
            // We'll insert a copy of the operation, all of whose
            // OTHER output operands are newly-created -- i.e.,
            // there'll only be a duplicate write of ONE of that
            // operation's output operands.
            validate(device, message, model,
                     [operation, badOutputNum](Model* model, ExecutionPreference*, Priority*) {
                         Operation newOperation = model->main.operations[operation];
                         for (size_t outputNum = 0; outputNum < newOperation.outputs.size();
                              ++outputNum) {
                             if (outputNum == badOutputNum) continue;

                             Operand operandValue =
                                     model->main.operands[newOperation.outputs[outputNum]];
                             if (operandValue.lifetime == OperandLifeTime::SUBGRAPH_OUTPUT) {
                                 operandValue.lifetime = OperandLifeTime::TEMPORARY_VARIABLE;
                             } else {
                                 ASSERT_EQ(operandValue.lifetime,
                                           OperandLifeTime::TEMPORARY_VARIABLE);
                             }
                             newOperation.outputs[outputNum] = model->main.operands.size();
                             model->main.operands.push_back(operandValue);
                         }
                         // Where do we insert the extra writer (a new
                         // operation)?  It has to be later than all the
                         // writers of its inputs.  The easiest thing to do
                         // is to insert it at the end of the operation
                         // sequence.
                         model->main.operations.push_back(newOperation);
                     });
        }
    }
}

///////////////////////// VALIDATE EXTRA ??? /////////////////////////

// TODO: Operand::location

///////////////////////// VALIDATE OPERATION OPERAND TYPE /////////////////////////

static void mutateOperand(Operand* operand, OperandType type) {
    Operand newOperand = *operand;
    newOperand.type = type;
    switch (type) {
        case OperandType::FLOAT16:
        case OperandType::FLOAT32:
        case OperandType::INT32:
        case OperandType::UINT32:
        case OperandType::BOOL:
            newOperand.dimensions = {};
            newOperand.scale = 0.0f;
            newOperand.zeroPoint = 0;
            break;
        case OperandType::TENSOR_BOOL8:
        case OperandType::TENSOR_FLOAT16:
        case OperandType::TENSOR_FLOAT32:
            newOperand.dimensions = operand->dimensions.size() > 0 ? operand->dimensions
                                                                   : std::vector<int32_t>({1});
            newOperand.scale = 0.0f;
            newOperand.zeroPoint = 0;
            break;
        case OperandType::TENSOR_INT32:
            newOperand.dimensions = operand->dimensions.size() > 0 ? operand->dimensions
                                                                   : std::vector<int32_t>({1});
            newOperand.zeroPoint = 0;
            break;
        case OperandType::TENSOR_QUANT8_ASYMM:
        case OperandType::TENSOR_QUANT8_SYMM:
        case OperandType::TENSOR_QUANT16_ASYMM:
        case OperandType::TENSOR_QUANT16_SYMM:
            newOperand.dimensions = operand->dimensions.size() > 0 ? operand->dimensions
                                                                   : std::vector<int32_t>({1});
            newOperand.scale = operand->scale != 0.0f ? operand->scale : 1.0f;
            break;
        case OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL: {
            newOperand.dimensions = operand->dimensions.size() > 0 ? operand->dimensions
                                                                   : std::vector<int32_t>({1});
            newOperand.scale = 0.0f;
            newOperand.zeroPoint = 0;

            SymmPerChannelQuantParams channelQuant;
            channelQuant.channelDim = 0;
            channelQuant.scales = std::vector<float>(
                    operand->dimensions.size() > 0 ? static_cast<size_t>(operand->dimensions[0])
                                                   : 0);
            for (size_t i = 0; i < channelQuant.scales.size(); ++i) {
                channelQuant.scales[i] = 1.0f;
            }
            newOperand.extraParams->set<OperandExtraParams::Tag::channelQuant>(
                    std::move(channelQuant));
        } break;
        default:
            break;
    }
    *operand = newOperand;
}

static bool mutateOperationOperandTypeSkip(size_t operand, OperandType type, const Model& model) {
    if (type == model.main.operands[operand].type) {
        return true;
    }
    for (const Operation& operation : model.main.operations) {
        // Skip mutateOperationOperandTypeTest for the following operations.
        // - LSH_PROJECTION's second argument is allowed to have any type.
        // - ARGMIN and ARGMAX's first argument can be any of
        // TENSOR_(FLOAT16|FLOAT32|INT32|QUANT8_ASYMM).
        // - CAST's argument can be any of TENSOR_(FLOAT16|FLOAT32|INT32|QUANT8_ASYMM).
        // - RANDOM_MULTINOMIAL's argument can be either TENSOR_FLOAT16 or TENSOR_FLOAT32.
        // - DEQUANTIZE input can be any of
        // TENSOR_(QUANT8_ASYMM|QUANT8_ASYMM_SIGNED|QUANT8_SYMM|QUANT8_SYMM_PER_CHANNEL),
        // output can be of either TENSOR_FLOAT16 or TENSOR_FLOAT32.
        // - QUANTIZE input can be either TENSOR_FLOAT16 or TENSOR_FLOAT32
        // - CONV_2D filter type (arg 1) can be QUANT8_ASYMM or QUANT8_SYMM_PER_CHANNEL
        // - DEPTHWISE_CONV_2D filter type (arg 1) can be QUANT8_ASYMM or QUANT8_SYMM_PER_CHANNEL
        // - GROUPED_CONV_2D filter type (arg 1) can be QUANT8_ASYMM or QUANT8_SYMM_PER_CHANNEL
        // - TRANSPOSE_CONV_2D filter type (arg 1) can be QUANT8_ASYMM or QUANT8_SYMM_PER_CHANNEL
        // - AXIS_ALIGNED_BBOX_TRANSFORM bounding boxes (arg 1) can be of
        //     TENSOR_QUANT8_ASYMM or TENSOR_QUANT8_ASYMM_SIGNED.
        // - RANK's input can have any TENSOR_* type.
        switch (operation.type) {
            case OperationType::LSH_PROJECTION: {
                if (operand == operation.inputs[1]) {
                    return true;
                }
            } break;
            case OperationType::CAST:
            case OperationType::ARGMAX:
            case OperationType::ARGMIN: {
                if (type == OperandType::TENSOR_FLOAT16 || type == OperandType::TENSOR_FLOAT32 ||
                    type == OperandType::TENSOR_INT32 || type == OperandType::TENSOR_QUANT8_ASYMM ||
                    type == OperandType::TENSOR_QUANT8_ASYMM_SIGNED) {
                    return true;
                }
            } break;
            case OperationType::QUANTIZE: {
                if (operand == operation.inputs[0] &&
                    (type == OperandType::TENSOR_FLOAT16 || type == OperandType::TENSOR_FLOAT32)) {
                    return true;
                }
                if (operand == operation.outputs[0] &&
                    (type == OperandType::TENSOR_QUANT8_ASYMM ||
                     type == OperandType::TENSOR_QUANT8_ASYMM_SIGNED)) {
                    return true;
                }
            } break;
            case OperationType::RANDOM_MULTINOMIAL: {
                if (operand == operation.inputs[0] &&
                    (type == OperandType::TENSOR_FLOAT16 || type == OperandType::TENSOR_FLOAT32)) {
                    return true;
                }
            } break;
            case OperationType::DEQUANTIZE: {
                if (operand == operation.inputs[0] &&
                    (type == OperandType::TENSOR_QUANT8_ASYMM ||
                     type == OperandType::TENSOR_QUANT8_ASYMM_SIGNED ||
                     type == OperandType::TENSOR_QUANT8_SYMM ||
                     type == OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL)) {
                    return true;
                }
                if (operand == operation.outputs[0] &&
                    (type == OperandType::TENSOR_FLOAT16 || type == OperandType::TENSOR_FLOAT32)) {
                    return true;
                }
            } break;
            case OperationType::TRANSPOSE_CONV_2D:
            case OperationType::GROUPED_CONV_2D:
            case OperationType::DEPTHWISE_CONV_2D:
            case OperationType::CONV_2D: {
                if (operand == operation.inputs[1] &&
                    (type == OperandType::TENSOR_QUANT8_ASYMM ||
                     type == OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL)) {
                    return true;
                }
            } break;
            case OperationType::AXIS_ALIGNED_BBOX_TRANSFORM: {
                if (operand == operation.inputs[1] &&
                    (type == OperandType::TENSOR_QUANT8_ASYMM ||
                     type == OperandType::TENSOR_QUANT8_ASYMM_SIGNED)) {
                    return true;
                }
            } break;
            case OperationType::RANK: {
                if (operand == operation.inputs[0] &&
                    (type == OperandType::TENSOR_FLOAT16 || type == OperandType::TENSOR_FLOAT32 ||
                     type == OperandType::TENSOR_INT32 ||
                     type == OperandType::TENSOR_QUANT8_ASYMM ||
                     type == OperandType::TENSOR_QUANT16_SYMM ||
                     type == OperandType::TENSOR_BOOL8 ||
                     type == OperandType::TENSOR_QUANT8_SYMM_PER_CHANNEL ||
                     type == OperandType::TENSOR_QUANT16_ASYMM ||
                     type == OperandType::TENSOR_QUANT8_SYMM ||
                     type == OperandType::TENSOR_QUANT8_ASYMM_SIGNED)) {
                    return true;
                }
            } break;
            default:
                break;
        }
    }
    return false;
}

static void mutateOperationOperandTypeTest(const std::shared_ptr<IDevice>& device,
                                           const Model& model) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        for (OperandType invalidOperandType : ndk::enum_range<OperandType>()) {
            if (mutateOperationOperandTypeSkip(operand, invalidOperandType, model)) {
                continue;
            }
            const std::string message = "mutateOperationOperandTypeTest: operand " +
                                        std::to_string(operand) + " set to type " +
                                        toString(invalidOperandType);
            validate(device, message, model,
                     [operand, invalidOperandType](Model* model, ExecutionPreference*, Priority*) {
                         mutateOperand(&model->main.operands[operand], invalidOperandType);
                     });
        }
    }
}

///////////////////////// VALIDATE MODEL OPERATION TYPE /////////////////////////

static const int32_t invalidOperationTypes[] = {
        -1,
        static_cast<int32_t>(*(ndk::enum_range<OperationType>().end() - 1)) + 1,
};

static void mutateOperationTypeTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        for (int32_t invalidOperationType : invalidOperationTypes) {
            const std::string message = "mutateOperationTypeTest: operation " +
                                        std::to_string(operation) + " set to value " +
                                        std::to_string(invalidOperationType);
            validate(device, message, model,
                     [operation, invalidOperationType](Model* model, ExecutionPreference*,
                                                       Priority*) {
                         model->main.operations[operation].type =
                                 static_cast<OperationType>(invalidOperationType);
                     });
        }
    }
}

///////////////////////// VALIDATE MODEL OPERATION INPUT OPERAND INDEX /////////////////////////

static void mutateOperationInputOperandIndexTest(const std::shared_ptr<IDevice>& device,
                                                 const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        const uint32_t invalidOperand = model.main.operands.size();
        for (size_t input = 0; input < model.main.operations[operation].inputs.size(); ++input) {
            const std::string message = "mutateOperationInputOperandIndexTest: operation " +
                                        std::to_string(operation) + " input " +
                                        std::to_string(input);
            validate(device, message, model,
                     [operation, input, invalidOperand](Model* model, ExecutionPreference*,
                                                        Priority*) {
                         model->main.operations[operation].inputs[input] = invalidOperand;
                     });
        }
    }
}

///////////////////////// VALIDATE MODEL OPERATION OUTPUT OPERAND INDEX /////////////////////////

static void mutateOperationOutputOperandIndexTest(const std::shared_ptr<IDevice>& device,
                                                  const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        const uint32_t invalidOperand = model.main.operands.size();
        for (size_t output = 0; output < model.main.operations[operation].outputs.size();
             ++output) {
            const std::string message = "mutateOperationOutputOperandIndexTest: operation " +
                                        std::to_string(operation) + " output " +
                                        std::to_string(output);
            validate(device, message, model,
                     [operation, output, invalidOperand](Model* model, ExecutionPreference*,
                                                         Priority*) {
                         model->main.operations[operation].outputs[output] = invalidOperand;
                     });
        }
    }
}

///////////////////////// VALIDATE MODEL OPERANDS WRITTEN ///////////////////////////////////////

static void mutateOperationRemoveWriteTest(const std::shared_ptr<IDevice>& device,
                                           const Model& model,
                                           const std::vector<uint32_t>& numberOfConsumers) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        for (size_t outputNum = 0; outputNum < model.main.operations[operation].outputs.size();
             ++outputNum) {
            const uint32_t outputOperandIndex = model.main.operations[operation].outputs[outputNum];
            if (numberOfConsumers[outputOperandIndex] > 0) {
                const std::string message = "mutateOperationRemoveWriteTest: operation " +
                                            std::to_string(operation) + " writes to " +
                                            std::to_string(outputOperandIndex);
                validate(device, message, model,
                         [operation, outputNum](Model* model, ExecutionPreference*, Priority*) {
                             int32_t& outputOperandIndex =
                                     model->main.operations[operation].outputs[outputNum];
                             Operand operandValue = model->main.operands[outputOperandIndex];
                             if (operandValue.lifetime == OperandLifeTime::SUBGRAPH_OUTPUT) {
                                 operandValue.lifetime = OperandLifeTime::TEMPORARY_VARIABLE;
                             } else {
                                 ASSERT_EQ(operandValue.lifetime,
                                           OperandLifeTime::TEMPORARY_VARIABLE);
                             }
                             outputOperandIndex = model->main.operands.size();
                             model->main.operands.push_back(operandValue);
                         });
            }
        }
    }
}

///////////////////////// REMOVE OPERAND FROM EVERYTHING /////////////////////////

static void removeValueAndDecrementGreaterValues(std::vector<int32_t>* vec, uint32_t value) {
    if (vec) {
        // remove elements matching "value"
        vec->erase(std::remove(vec->begin(), vec->end(), value), vec->end());

        // decrement elements exceeding "value"
        std::transform(vec->begin(), vec->end(), vec->begin(),
                       [value](uint32_t v) { return v > value ? v-- : v; });
    }
}

static void removeOperand(Model* model, uint32_t index) {
    model->main.operands.erase(model->main.operands.begin() + index);
    for (Operation& operation : model->main.operations) {
        removeValueAndDecrementGreaterValues(&operation.inputs, index);
        removeValueAndDecrementGreaterValues(&operation.outputs, index);
    }
    removeValueAndDecrementGreaterValues(&model->main.inputIndexes, index);
    removeValueAndDecrementGreaterValues(&model->main.outputIndexes, index);
}

static bool removeOperandSkip(size_t operandIndex, const Model& model,
                              const std::vector<uint32_t>& numberOfConsumers) {
    if (numberOfConsumers[operandIndex] == 0) {
        // Removing an unused operand has no effect.
        return true;
    }
    for (const Operation& operation : model.main.operations) {
        // Skip removeOperandTest for the following operations.
        // - SPLIT's outputs are not checked during prepareModel.
        if (operation.type == OperationType::SPLIT) {
            for (const size_t index : operation.outputs) {
                if (index == operandIndex) {
                    return true;
                }
            }
        }
        // BIDIRECTIONAL_SEQUENCE_LSTM and BIDIRECTIONAL_SEQUENCE_RNN can have
        // either one, two, three or four outputs depending on their
        // mergeOutputs parameter and if state outputs are provided.
        // UNIDIRECTIONAL_SEQUENCE_LSTM and UNIDIRECTIONAL_SEQUENCE_RNN can have
        // either one or three outputs depending on whether state outputs are
        // provided.
        if (operation.type == OperationType::UNIDIRECTIONAL_SEQUENCE_LSTM ||
            operation.type == OperationType::UNIDIRECTIONAL_SEQUENCE_RNN ||
            operation.type == OperationType::BIDIRECTIONAL_SEQUENCE_LSTM ||
            operation.type == OperationType::BIDIRECTIONAL_SEQUENCE_RNN) {
            for (const size_t index : operation.outputs) {
                if (index == operandIndex) {
                    return true;
                }
            }
        }
    }
    return false;
}

static void removeOperandTest(const std::shared_ptr<IDevice>& device, const Model& model,
                              const std::vector<uint32_t>& numberOfConsumers) {
    for (size_t operand = 0; operand < model.main.operands.size(); ++operand) {
        if (removeOperandSkip(operand, model, numberOfConsumers)) {
            continue;
        }
        const std::string message = "removeOperandTest: operand " + std::to_string(operand);
        validate(device, message, model, [operand](Model* model, ExecutionPreference*, Priority*) {
            removeOperand(model, operand);
        });
    }
}

///////////////////////// REMOVE OPERATION /////////////////////////

static void removeOperation(Model* model, uint32_t index) {
    auto& operations = model->main.operations;
    operations.erase(operations.begin() + index);
}

static void removeOperationTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        const std::string message = "removeOperationTest: operation " + std::to_string(operation);
        validate(device, message, model,
                 [operation](Model* model, ExecutionPreference*, Priority*) {
                     removeOperation(model, operation);
                 });
    }
}

///////////////////////// REMOVE OPERATION INPUT /////////////////////////

static bool removeOperationInputSkip(const Operation& op, size_t input) {
    // Skip removeOperationInputTest for the following operations.
    // - CONCATENATION has at least 2 inputs, with the last element being INT32.
    // - CONV_2D, DEPTHWISE_CONV_2D, MAX_POOL_2D, AVERAGE_POOL_2D, L2_POOL_2D, RESIZE_BILINEAR,
    //   SPACE_TO_DEPTH, SPACE_TO_DEPTH, SPACE_TO_BATCH_ND, BATCH_TO_SPACE_ND can have an optional
    //   layout parameter.
    //   RESIZE_BILINEAR and RESIZE_NEAREST_NEIGHBOR can have optional
    //   align_corners and half_pixel_centers parameters.
    // - L2_NORMALIZATION, LOCAL_RESPONSE_NORMALIZATION, SOFTMAX can have an optional axis
    //   parameter.
    switch (op.type) {
        case OperationType::CONCATENATION: {
            if (op.inputs.size() > 2 && input != op.inputs.size() - 1) {
                return true;
            }
        } break;
        case OperationType::DEPTHWISE_CONV_2D: {
            if ((op.inputs.size() == 12 && input == 11) || (op.inputs.size() == 9 && input == 8)) {
                return true;
            }
        } break;
        case OperationType::CONV_2D:
        case OperationType::AVERAGE_POOL_2D:
        case OperationType::MAX_POOL_2D:
        case OperationType::L2_POOL_2D: {
            if ((op.inputs.size() == 11 && input == 10) || (op.inputs.size() == 8 && input == 7)) {
                return true;
            }
        } break;
        case OperationType::RESIZE_BILINEAR: {
            if (op.inputs.size() >= 4 && input >= 3) {
                return true;
            }
        } break;
        case OperationType::RESIZE_NEAREST_NEIGHBOR: {
            if (op.inputs.size() >= 5 && input >= 3) {
                return true;
            }
        } break;
        case OperationType::SPACE_TO_DEPTH:
        case OperationType::DEPTH_TO_SPACE:
        case OperationType::BATCH_TO_SPACE_ND: {
            if (op.inputs.size() == 3 && input == 2) {
                return true;
            }
        } break;
        case OperationType::SPACE_TO_BATCH_ND: {
            if (op.inputs.size() == 4 && input == 3) {
                return true;
            }
        } break;
        case OperationType::L2_NORMALIZATION: {
            if (op.inputs.size() == 2 && input == 1) {
                return true;
            }
        } break;
        case OperationType::LOCAL_RESPONSE_NORMALIZATION: {
            if (op.inputs.size() == 6 && input == 5) {
                return true;
            }
        } break;
        case OperationType::SOFTMAX: {
            if (op.inputs.size() == 3 && input == 2) {
                return true;
            }
        } break;
        default:
            break;
    }
    return false;
}

static void removeOperationInputTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        for (size_t input = 0; input < model.main.operations[operation].inputs.size(); ++input) {
            const Operation& op = model.main.operations[operation];
            if (removeOperationInputSkip(op, input)) {
                continue;
            }
            const std::string message = "removeOperationInputTest: operation " +
                                        std::to_string(operation) + ", input " +
                                        std::to_string(input);
            validate(device, message, model,
                     [operation, input](Model* model, ExecutionPreference*, Priority*) {
                         auto& inputs = model->main.operations[operation].inputs;
                         inputs.erase(inputs.begin() + input);
                     });
        }
    }
}

///////////////////////// REMOVE OPERATION OUTPUT /////////////////////////

static void removeOperationOutputTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        for (size_t output = 0; output < model.main.operations[operation].outputs.size();
             ++output) {
            const std::string message = "removeOperationOutputTest: operation " +
                                        std::to_string(operation) + ", output " +
                                        std::to_string(output);
            validate(device, message, model,
                     [operation, output](Model* model, ExecutionPreference*, Priority*) {
                         auto& outputs = model->main.operations[operation].outputs;
                         outputs.erase(outputs.begin() + output);
                     });
        }
    }
}

///////////////////////// MODEL VALIDATION /////////////////////////

// TODO: remove model input
// TODO: remove model output
// TODO: add unused operation

///////////////////////// ADD OPERATION INPUT /////////////////////////

static bool addOperationInputSkip(const Operation& op) {
    // Skip addOperationInputTest for the following operations.
    // - L2_NORMALIZATION, LOCAL_RESPONSE_NORMALIZATION, SOFTMAX can have an optional INT32 axis
    //   parameter.
    if ((op.type == OperationType::L2_NORMALIZATION && op.inputs.size() == 1) ||
        (op.type == OperationType::LOCAL_RESPONSE_NORMALIZATION && op.inputs.size() == 5) ||
        (op.type == OperationType::SOFTMAX && op.inputs.size() == 2) ||
        (op.type == OperationType::RESIZE_BILINEAR && op.inputs.size() < 6) ||
        (op.type == OperationType::RESIZE_NEAREST_NEIGHBOR && op.inputs.size() < 6)) {
        return true;
    }
    return false;
}

static void addOperationInputTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        if (addOperationInputSkip(model.main.operations[operation])) {
            continue;
        }
        const std::string message = "addOperationInputTest: operation " + std::to_string(operation);
        validate(device, message, model,
                 [operation](Model* model, ExecutionPreference*, Priority*) {
                     uint32_t index = addOperand(model, OperandLifeTime::SUBGRAPH_INPUT);
                     model->main.operations[operation].inputs.push_back(index);
                     model->main.inputIndexes.push_back(index);
                 });
    }
}

///////////////////////// ADD OPERATION OUTPUT /////////////////////////

static void addOperationOutputTest(const std::shared_ptr<IDevice>& device, const Model& model) {
    for (size_t operation = 0; operation < model.main.operations.size(); ++operation) {
        const std::string message =
                "addOperationOutputTest: operation " + std::to_string(operation);
        validate(device, message, model,
                 [operation](Model* model, ExecutionPreference*, Priority*) {
                     uint32_t index = addOperand(model, OperandLifeTime::SUBGRAPH_OUTPUT);
                     model->main.operations[operation].outputs.push_back(index);
                     model->main.outputIndexes.push_back(index);
                 });
    }
}

///////////////////////// VALIDATE EXECUTION PREFERENCE /////////////////////////

static const int32_t invalidExecutionPreferences[] = {
        static_cast<int32_t>(ExecutionPreference::LOW_POWER) - 1,        // lower bound
        static_cast<int32_t>(ExecutionPreference::SUSTAINED_SPEED) + 1,  // upper bound
};

static void mutateExecutionPreferenceTest(const std::shared_ptr<IDevice>& device,
                                          const Model& model) {
    for (int32_t invalidPreference : invalidExecutionPreferences) {
        const std::string message =
                "mutateExecutionPreferenceTest: preference " + std::to_string(invalidPreference);
        validate(device, message, model,
                 [invalidPreference](Model*, ExecutionPreference* preference, Priority*) {
                     *preference = static_cast<ExecutionPreference>(invalidPreference);
                 });
    }
}

///////////////////////// VALIDATE PRIORITY /////////////////////////

static const int32_t invalidPriorities[] = {
        static_cast<int32_t>(Priority::LOW) - 1,   // lower bound
        static_cast<int32_t>(Priority::HIGH) + 1,  // upper bound
};

static void mutateExecutionPriorityTest(const std::shared_ptr<IDevice>& device,
                                        const Model& model) {
    for (int32_t invalidPriority : invalidPriorities) {
        const std::string message =
                "mutatePriorityTest: priority " + std::to_string(invalidPriority);
        validate(device, message, model,
                 [invalidPriority](Model*, ExecutionPreference*, Priority* priority) {
                     *priority = static_cast<Priority>(invalidPriority);
                 });
    }
}

////////////////////////// ENTRY POINT //////////////////////////////

void validateModel(const std::shared_ptr<IDevice>& device, const Model& model) {
    const auto numberOfConsumers =
            nn::countNumberOfConsumers(model.main.operands.size(),
                                       nn::convert(model.main.operations).value())
                    .value();
    mutateExecutionOrderTest(device, model, numberOfConsumers);
    mutateOperandTypeTest(device, model);
    mutateOperandRankTest(device, model);
    mutateOperandScaleTest(device, model);
    mutateOperandZeroPointTest(device, model);
    mutateOperandLifeTimeTest(device, model);
    mutateOperandInputOutputTest(device, model);
    mutateOperandAddWriterTest(device, model);
    mutateOperationOperandTypeTest(device, model);
    mutateOperationTypeTest(device, model);
    mutateOperationInputOperandIndexTest(device, model);
    mutateOperationOutputOperandIndexTest(device, model);
    mutateOperationRemoveWriteTest(device, model, numberOfConsumers);
    removeOperandTest(device, model, numberOfConsumers);
    removeOperationTest(device, model);
    removeOperationInputTest(device, model);
    removeOperationOutputTest(device, model);
    addOperationInputTest(device, model);
    addOperationOutputTest(device, model);
    mutateExecutionPreferenceTest(device, model);
    mutateExecutionPriorityTest(device, model);
}

}  // namespace aidl::android::hardware::neuralnetworks::vts::functional