// Copyright 2022 The Tint Authors.
//
// 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.

#include "src/tint/resolver/const_eval.h"

#include <algorithm>
#include <iomanip>
#include <limits>
#include <optional>
#include <string>
#include <type_traits>
#include <utility>

#include "src/tint/program_builder.h"
#include "src/tint/sem/abstract_float.h"
#include "src/tint/sem/abstract_int.h"
#include "src/tint/sem/array.h"
#include "src/tint/sem/bool.h"
#include "src/tint/sem/constant.h"
#include "src/tint/sem/f16.h"
#include "src/tint/sem/f32.h"
#include "src/tint/sem/i32.h"
#include "src/tint/sem/matrix.h"
#include "src/tint/sem/member_accessor_expression.h"
#include "src/tint/sem/type_initializer.h"
#include "src/tint/sem/u32.h"
#include "src/tint/sem/vector.h"
#include "src/tint/utils/bitcast.h"
#include "src/tint/utils/compiler_macros.h"
#include "src/tint/utils/map.h"
#include "src/tint/utils/transform.h"

using namespace tint::number_suffixes;  // NOLINT

namespace tint::resolver {

namespace {

/// Returns the first element of a parameter pack
template <typename T>
T First(T&& first, ...) {
    return std::forward<T>(first);
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_iu32(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::U32*) { return f(cs->template As<u32>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_ia_iu32(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractInt*) { return f(cs->template As<AInt>()...); },
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::U32*) { return f(cs->template As<u32>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_ia_iu32_bool(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractInt*) { return f(cs->template As<AInt>()...); },
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::U32*) { return f(cs->template As<u32>()...); },
        [&](const sem::Bool*) { return f(cs->template As<bool>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_fia_fi32_f16(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractInt*) { return f(cs->template As<AInt>()...); },
        [&](const sem::AbstractFloat*) { return f(cs->template As<AFloat>()...); },
        [&](const sem::F32*) { return f(cs->template As<f32>()...); },
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::F16*) { return f(cs->template As<f16>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_fia_fiu32_f16(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractInt*) { return f(cs->template As<AInt>()...); },
        [&](const sem::AbstractFloat*) { return f(cs->template As<AFloat>()...); },
        [&](const sem::F32*) { return f(cs->template As<f32>()...); },
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::U32*) { return f(cs->template As<u32>()...); },
        [&](const sem::F16*) { return f(cs->template As<f16>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_fia_fiu32_f16_bool(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractInt*) { return f(cs->template As<AInt>()...); },
        [&](const sem::AbstractFloat*) { return f(cs->template As<AFloat>()...); },
        [&](const sem::F32*) { return f(cs->template As<f32>()...); },
        [&](const sem::I32*) { return f(cs->template As<i32>()...); },
        [&](const sem::U32*) { return f(cs->template As<u32>()...); },
        [&](const sem::F16*) { return f(cs->template As<f16>()...); },
        [&](const sem::Bool*) { return f(cs->template As<bool>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_fa_f32_f16(F&& f, CONSTANTS&&... cs) {
    return Switch(
        First(cs...)->Type(),  //
        [&](const sem::AbstractFloat*) { return f(cs->template As<AFloat>()...); },
        [&](const sem::F32*) { return f(cs->template As<f32>()...); },
        [&](const sem::F16*) { return f(cs->template As<f16>()...); });
}

/// Helper that calls `f` passing in the value of all `cs`.
/// Calls `f` with all constants cast to the type of the first `cs` argument.
template <typename F, typename... CONSTANTS>
auto Dispatch_bool(F&& f, CONSTANTS&&... cs) {
    return f(cs->template As<bool>()...);
}

/// ZeroTypeDispatch is a helper for calling the function `f`, passing a single zero-value argument
/// of the C++ type that corresponds to the sem::Type `type`. For example, calling
/// `ZeroTypeDispatch()` with a type of `sem::I32*` will call the function f with a single argument
/// of `i32(0)`.
/// @returns the value returned by calling `f`.
/// @note `type` must be a scalar or abstract numeric type. Other types will not call `f`, and will
/// return the zero-initialized value of the return type for `f`.
template <typename F>
auto ZeroTypeDispatch(const sem::Type* type, F&& f) {
    return Switch(
        type,                                                     //
        [&](const sem::AbstractInt*) { return f(AInt(0)); },      //
        [&](const sem::AbstractFloat*) { return f(AFloat(0)); },  //
        [&](const sem::I32*) { return f(i32(0)); },               //
        [&](const sem::U32*) { return f(u32(0)); },               //
        [&](const sem::F32*) { return f(f32(0)); },               //
        [&](const sem::F16*) { return f(f16(0)); },               //
        [&](const sem::Bool*) { return f(static_cast<bool>(0)); });
}

/// @returns `value` if `T` is not a Number, otherwise ValueOf returns the inner value of the
/// Number.
template <typename T>
inline auto ValueOf(T value) {
    if constexpr (std::is_same_v<UnwrapNumber<T>, T>) {
        return value;
    } else {
        return value.value;
    }
}

/// @returns true if `value` is a positive zero.
template <typename T>
inline bool IsPositiveZero(T value) {
    using N = UnwrapNumber<T>;
    return Number<N>(value) == Number<N>(0);  // Considers sign bit
}

template <typename NumberT>
std::string OverflowErrorMessage(NumberT lhs, const char* op, NumberT rhs) {
    std::stringstream ss;
    ss << std::setprecision(20);
    ss << "'" << lhs.value << " " << op << " " << rhs.value << "' cannot be represented as '"
       << FriendlyName<NumberT>() << "'";
    return ss.str();
}

template <typename VALUE_TY>
std::string OverflowErrorMessage(VALUE_TY value, std::string_view target_ty) {
    std::stringstream ss;
    ss << std::setprecision(20);
    ss << "value " << value << " cannot be represented as "
       << "'" << target_ty << "'";
    return ss.str();
}

template <typename NumberT>
std::string OverflowExpErrorMessage(std::string_view base, NumberT value) {
    std::stringstream ss;
    ss << std::setprecision(20);
    ss << base << "^" << value << " cannot be represented as "
       << "'" << FriendlyName<NumberT>() << "'";
    return ss.str();
}

/// @returns the number of consecutive leading bits in `@p e` set to `@p bit_value_to_count`.
template <typename T>
std::make_unsigned_t<T> CountLeadingBits(T e, T bit_value_to_count) {
    using UT = std::make_unsigned_t<T>;
    constexpr UT kNumBits = sizeof(UT) * 8;
    constexpr UT kLeftMost = UT{1} << (kNumBits - 1);
    const UT b = bit_value_to_count == 0 ? UT{0} : kLeftMost;

    auto v = static_cast<UT>(e);
    auto count = UT{0};
    while ((count < kNumBits) && ((v & kLeftMost) == b)) {
        ++count;
        v <<= 1;
    }
    return count;
}

/// @returns the number of consecutive trailing bits set to `@p bit_value_to_count` in `@p e`
template <typename T>
std::make_unsigned_t<T> CountTrailingBits(T e, T bit_value_to_count) {
    using UT = std::make_unsigned_t<T>;
    constexpr UT kNumBits = sizeof(UT) * 8;
    constexpr UT kRightMost = UT{1};
    const UT b = static_cast<UT>(bit_value_to_count);

    auto v = static_cast<UT>(e);
    auto count = UT{0};
    while ((count < kNumBits) && ((v & kRightMost) == b)) {
        ++count;
        v >>= 1;
    }
    return count;
}

/// ImplConstant inherits from sem::Constant to add an private implementation method for conversion.
struct ImplConstant : public sem::Constant {
    /// Convert attempts to convert the constant value to the given type. On error, Convert()
    /// creates a new diagnostic message and returns a Failure.
    virtual utils::Result<const ImplConstant*> Convert(ProgramBuilder& builder,
                                                       const sem::Type* target_ty,
                                                       const Source& source) const = 0;
};

/// A result templated with a ImplConstant.
using ImplResult = utils::Result<const ImplConstant*>;

// Forward declaration
const ImplConstant* CreateComposite(ProgramBuilder& builder,
                                    const sem::Type* type,
                                    utils::VectorRef<const sem::Constant*> elements);

/// Element holds a single scalar or abstract-numeric value.
/// Element implements the Constant interface.
template <typename T>
struct Element : ImplConstant {
    static_assert(!std::is_same_v<UnwrapNumber<T>, T> || std::is_same_v<T, bool>,
                  "T must be a Number or bool");

    Element(const sem::Type* t, T v) : type(t), value(v) {
        if constexpr (IsFloatingPoint<T>) {
            TINT_ASSERT(Resolver, std::isfinite(v.value));
        }
    }
    ~Element() override = default;
    const sem::Type* Type() const override { return type; }
    std::variant<std::monostate, AInt, AFloat> Value() const override {
        if constexpr (IsFloatingPoint<UnwrapNumber<T>>) {
            return static_cast<AFloat>(value);
        } else {
            return static_cast<AInt>(value);
        }
    }
    const sem::Constant* Index(size_t) const override { return nullptr; }
    bool AllZero() const override { return IsPositiveZero(value); }
    bool AnyZero() const override { return IsPositiveZero(value); }
    bool AllEqual() const override { return true; }
    size_t Hash() const override { return utils::Hash(type, ValueOf(value)); }

    ImplResult Convert(ProgramBuilder& builder,
                       const sem::Type* target_ty,
                       const Source& source) const override {
        TINT_BEGIN_DISABLE_WARNING(UNREACHABLE_CODE);
        if (target_ty == type) {
            // If the types are identical, then no conversion is needed.
            return this;
        }
        return ZeroTypeDispatch(target_ty, [&](auto zero_to) -> ImplResult {
            // `value` is the source value.
            // `FROM` is the source type.
            // `TO` is the target type.
            using TO = std::decay_t<decltype(zero_to)>;
            using FROM = T;
            if constexpr (std::is_same_v<TO, bool>) {
                // [x -> bool]
                return builder.create<Element<TO>>(target_ty, !IsPositiveZero(value));
            } else if constexpr (std::is_same_v<FROM, bool>) {
                // [bool -> x]
                return builder.create<Element<TO>>(target_ty, TO(value ? 1 : 0));
            } else if (auto conv = CheckedConvert<TO>(value)) {
                // Conversion success
                return builder.create<Element<TO>>(target_ty, conv.Get());
                // --- Below this point are the failure cases ---
            } else if constexpr (IsAbstract<FROM>) {
                // [abstract-numeric -> x] - materialization failure
                builder.Diagnostics().add_error(
                    tint::diag::System::Resolver,
                    OverflowErrorMessage(value, builder.FriendlyName(target_ty)), source);
                return utils::Failure;
            } else if constexpr (IsFloatingPoint<TO>) {
                // [x -> floating-point] - number not exactly representable
                // https://www.w3.org/TR/WGSL/#floating-point-conversion
                builder.Diagnostics().add_error(
                    tint::diag::System::Resolver,
                    OverflowErrorMessage(value, builder.FriendlyName(target_ty)), source);
                return utils::Failure;
            } else if constexpr (IsFloatingPoint<FROM>) {
                // [floating-point -> integer] - number not exactly representable
                // https://www.w3.org/TR/WGSL/#floating-point-conversion
                switch (conv.Failure()) {
                    case ConversionFailure::kExceedsNegativeLimit:
                        return builder.create<Element<TO>>(target_ty, TO::Lowest());
                    case ConversionFailure::kExceedsPositiveLimit:
                        return builder.create<Element<TO>>(target_ty, TO::Highest());
                }
            } else if constexpr (IsIntegral<FROM>) {
                // [integer -> integer] - number not exactly representable
                // Static cast
                return builder.create<Element<TO>>(target_ty, static_cast<TO>(value));
            }
            return nullptr;  // Expression is not constant.
        });
        TINT_END_DISABLE_WARNING(UNREACHABLE_CODE);
    }

    sem::Type const* const type;
    const T value;
};

/// Splat holds a single Constant value, duplicated as all children.
/// Splat is used for zero-initializers, 'splat' initializers, or initializers where each element is
/// identical. Splat may be of a vector, matrix or array type.
/// Splat implements the Constant interface.
struct Splat : ImplConstant {
    Splat(const sem::Type* t, const sem::Constant* e, size_t n) : type(t), el(e), count(n) {}
    ~Splat() override = default;
    const sem::Type* Type() const override { return type; }
    std::variant<std::monostate, AInt, AFloat> Value() const override { return {}; }
    const sem::Constant* Index(size_t i) const override { return i < count ? el : nullptr; }
    bool AllZero() const override { return el->AllZero(); }
    bool AnyZero() const override { return el->AnyZero(); }
    bool AllEqual() const override { return true; }
    size_t Hash() const override { return utils::Hash(type, el->Hash(), count); }

    ImplResult Convert(ProgramBuilder& builder,
                       const sem::Type* target_ty,
                       const Source& source) const override {
        // Convert the single splatted element type.
        // Note: This file is the only place where `sem::Constant`s are created, so this static_cast
        // is safe.
        auto conv_el = static_cast<const ImplConstant*>(el)->Convert(
            builder, sem::Type::ElementOf(target_ty), source);
        if (!conv_el) {
            return utils::Failure;
        }
        if (!conv_el.Get()) {
            return nullptr;
        }
        return builder.create<Splat>(target_ty, conv_el.Get(), count);
    }

    sem::Type const* const type;
    const sem::Constant* el;
    const size_t count;
};

/// Composite holds a number of mixed child Constant values.
/// Composite may be of a vector, matrix or array type.
/// If each element is the same type and value, then a Splat would be a more efficient constant
/// implementation. Use CreateComposite() to create the appropriate Constant type.
/// Composite implements the Constant interface.
struct Composite : ImplConstant {
    Composite(const sem::Type* t,
              utils::VectorRef<const sem::Constant*> els,
              bool all_0,
              bool any_0)
        : type(t), elements(std::move(els)), all_zero(all_0), any_zero(any_0), hash(CalcHash()) {}
    ~Composite() override = default;
    const sem::Type* Type() const override { return type; }
    std::variant<std::monostate, AInt, AFloat> Value() const override { return {}; }
    const sem::Constant* Index(size_t i) const override {
        return i < elements.Length() ? elements[i] : nullptr;
    }
    bool AllZero() const override { return all_zero; }
    bool AnyZero() const override { return any_zero; }
    bool AllEqual() const override { return false; /* otherwise this should be a Splat */ }
    size_t Hash() const override { return hash; }

    ImplResult Convert(ProgramBuilder& builder,
                       const sem::Type* target_ty,
                       const Source& source) const override {
        // Convert each of the composite element types.
        utils::Vector<const sem::Constant*, 4> conv_els;
        conv_els.Reserve(elements.Length());
        std::function<const sem::Type*(size_t idx)> target_el_ty;
        if (auto* str = target_ty->As<sem::Struct>()) {
            if (str->Members().size() != elements.Length()) {
                TINT_ICE(Resolver, builder.Diagnostics())
                    << "const-eval conversion of structure has mismatched element counts";
                return utils::Failure;
            }
            target_el_ty = [str](size_t idx) { return str->Members()[idx]->Type(); };
        } else {
            auto* el_ty = sem::Type::ElementOf(target_ty);
            target_el_ty = [el_ty](size_t) { return el_ty; };
        }

        for (auto* el : elements) {
            // Note: This file is the only place where `sem::Constant`s are created, so the
            // static_cast is safe.
            auto conv_el = static_cast<const ImplConstant*>(el)->Convert(
                builder, target_el_ty(conv_els.Length()), source);
            if (!conv_el) {
                return utils::Failure;
            }
            if (!conv_el.Get()) {
                return nullptr;
            }
            conv_els.Push(conv_el.Get());
        }
        return CreateComposite(builder, target_ty, std::move(conv_els));
    }

    size_t CalcHash() {
        auto h = utils::Hash(type, all_zero, any_zero);
        for (auto* el : elements) {
            h = utils::HashCombine(h, el->Hash());
        }
        return h;
    }

    sem::Type const* const type;
    const utils::Vector<const sem::Constant*, 8> elements;
    const bool all_zero;
    const bool any_zero;
    const size_t hash;
};

/// CreateElement constructs and returns an Element<T>.
template <typename T>
ImplResult CreateElement(ProgramBuilder& builder, const Source& source, const sem::Type* t, T v) {
    if constexpr (IsFloatingPoint<T>) {
        if (!std::isfinite(v.value)) {
            auto msg = OverflowErrorMessage(v, builder.FriendlyName(t));
            builder.Diagnostics().add_error(diag::System::Resolver, msg, source);
            return utils::Failure;
        }
    }
    return builder.create<Element<T>>(t, v);
}

/// ZeroValue returns a Constant for the zero-value of the type `type`.
const ImplConstant* ZeroValue(ProgramBuilder& builder, const sem::Type* type) {
    return Switch(
        type,  //
        [&](const sem::Vector* v) -> const ImplConstant* {
            auto* zero_el = ZeroValue(builder, v->type());
            return builder.create<Splat>(type, zero_el, v->Width());
        },
        [&](const sem::Matrix* m) -> const ImplConstant* {
            auto* zero_el = ZeroValue(builder, m->ColumnType());
            return builder.create<Splat>(type, zero_el, m->columns());
        },
        [&](const sem::Array* a) -> const ImplConstant* {
            if (auto n = a->ConstantCount()) {
                if (auto* zero_el = ZeroValue(builder, a->ElemType())) {
                    return builder.create<Splat>(type, zero_el, n.value());
                }
            }
            return nullptr;
        },
        [&](const sem::Struct* s) -> const ImplConstant* {
            utils::Hashmap<const sem::Type*, const ImplConstant*, 8> zero_by_type;
            utils::Vector<const sem::Constant*, 4> zeros;
            zeros.Reserve(s->Members().size());
            for (auto* member : s->Members()) {
                auto* zero = zero_by_type.GetOrCreate(
                    member->Type(), [&] { return ZeroValue(builder, member->Type()); });
                if (!zero) {
                    return nullptr;
                }
                zeros.Push(zero);
            }
            if (zero_by_type.Count() == 1) {
                // All members were of the same type, so the zero value is the same for all members.
                return builder.create<Splat>(type, zeros[0], s->Members().size());
            }
            return CreateComposite(builder, s, std::move(zeros));
        },
        [&](Default) -> const ImplConstant* {
            return ZeroTypeDispatch(type, [&](auto zero) -> const ImplConstant* {
                auto el = CreateElement(builder, Source{}, type, zero);
                TINT_ASSERT(Resolver, el);
                return el.Get();
            });
        });
}

/// Equal returns true if the constants `a` and `b` are of the same type and value.
bool Equal(const sem::Constant* a, const sem::Constant* b) {
    if (a->Hash() != b->Hash()) {
        return false;
    }
    if (a->Type() != b->Type()) {
        return false;
    }
    return Switch(
        a->Type(),  //
        [&](const sem::Vector* vec) {
            for (size_t i = 0; i < vec->Width(); i++) {
                if (!Equal(a->Index(i), b->Index(i))) {
                    return false;
                }
            }
            return true;
        },
        [&](const sem::Matrix* mat) {
            for (size_t i = 0; i < mat->columns(); i++) {
                if (!Equal(a->Index(i), b->Index(i))) {
                    return false;
                }
            }
            return true;
        },
        [&](const sem::Array* arr) {
            if (auto count = arr->ConstantCount()) {
                for (size_t i = 0; i < count; i++) {
                    if (!Equal(a->Index(i), b->Index(i))) {
                        return false;
                    }
                }
                return true;
            }

            return false;
        },
        [&](Default) { return a->Value() == b->Value(); });
}

/// CreateComposite is used to construct a constant of a vector, matrix or array type.
/// CreateComposite examines the element values and will return either a Composite or a Splat,
/// depending on the element types and values.
const ImplConstant* CreateComposite(ProgramBuilder& builder,
                                    const sem::Type* type,
                                    utils::VectorRef<const sem::Constant*> elements) {
    if (elements.IsEmpty()) {
        return nullptr;
    }
    bool any_zero = false;
    bool all_zero = true;
    bool all_equal = true;
    auto* first = elements.Front();
    for (auto* el : elements) {
        if (!el) {
            return nullptr;
        }
        if (!any_zero && el->AnyZero()) {
            any_zero = true;
        }
        if (all_zero && !el->AllZero()) {
            all_zero = false;
        }
        if (all_equal && el != first) {
            if (!Equal(el, first)) {
                all_equal = false;
            }
        }
    }
    if (all_equal) {
        return builder.create<Splat>(type, elements[0], elements.Length());
    } else {
        return builder.create<Composite>(type, std::move(elements), all_zero, any_zero);
    }
}

namespace detail {
/// Implementation of TransformElements
template <typename F, typename... CONSTANTS>
ImplResult TransformElements(ProgramBuilder& builder,
                             const sem::Type* composite_ty,
                             F&& f,
                             size_t index,
                             CONSTANTS&&... cs) {
    uint32_t n = 0;
    auto* ty = First(cs...)->Type();
    auto* el_ty = sem::Type::ElementOf(ty, &n);
    if (el_ty == ty) {
        constexpr bool kHasIndexParam = traits::IsType<size_t, traits::LastParameterType<F>>;
        if constexpr (kHasIndexParam) {
            return f(cs..., index);
        } else {
            return f(cs...);
        }
    }
    utils::Vector<const sem::Constant*, 8> els;
    els.Reserve(n);
    for (uint32_t i = 0; i < n; i++) {
        if (auto el = detail::TransformElements(builder, sem::Type::ElementOf(composite_ty),
                                                std::forward<F>(f), index + i, cs->Index(i)...)) {
            els.Push(el.Get());

        } else {
            return el.Failure();
        }
    }
    return CreateComposite(builder, composite_ty, std::move(els));
}
}  // namespace detail

/// TransformElements constructs a new constant of type `composite_ty` by applying the
/// transformation function `f` on each of the most deeply nested elements of 'cs'. Assumes that all
/// input constants `cs` are of the same arity (all scalars or all vectors of the same size).
/// If `f`'s last argument is a `size_t`, then the index of the most deeply nested element inside
/// the most deeply nested aggregate type will be passed in.
template <typename F, typename... CONSTANTS>
ImplResult TransformElements(ProgramBuilder& builder,
                             const sem::Type* composite_ty,
                             F&& f,
                             CONSTANTS&&... cs) {
    return detail::TransformElements(builder, composite_ty, f, 0, cs...);
}

/// TransformBinaryElements constructs a new constant of type `composite_ty` by applying the
/// transformation function 'f' on each of the most deeply nested elements of both `c0` and `c1`.
/// Unlike TransformElements, this function handles the constants being of different arity, e.g.
/// vector-scalar, scalar-vector.
template <typename F>
ImplResult TransformBinaryElements(ProgramBuilder& builder,
                                   const sem::Type* composite_ty,
                                   F&& f,
                                   const sem::Constant* c0,
                                   const sem::Constant* c1) {
    uint32_t n0 = 0, n1 = 0;
    sem::Type::ElementOf(c0->Type(), &n0);
    sem::Type::ElementOf(c1->Type(), &n1);
    uint32_t max_n = std::max(n0, n1);
    // If arity of both constants is 1, invoke callback
    if (max_n == 1u) {
        return f(c0, c1);
    }

    utils::Vector<const sem::Constant*, 8> els;
    els.Reserve(max_n);
    for (uint32_t i = 0; i < max_n; i++) {
        auto nested_or_self = [&](auto& c, uint32_t num_elems) {
            if (num_elems == 1) {
                return c;
            }
            return c->Index(i);
        };
        if (auto el = TransformBinaryElements(builder, sem::Type::ElementOf(composite_ty),
                                              std::forward<F>(f), nested_or_self(c0, n0),
                                              nested_or_self(c1, n1))) {
            els.Push(el.Get());
        } else {
            return el.Failure();
        }
    }
    return CreateComposite(builder, composite_ty, std::move(els));
}
}  // namespace

ConstEval::ConstEval(ProgramBuilder& b) : builder(b) {}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Add(const Source& source, NumberT a, NumberT b) {
    NumberT result;
    if constexpr (IsAbstract<NumberT> || IsFloatingPoint<NumberT>) {
        if (auto r = CheckedAdd(a, b)) {
            result = r->value;
        } else {
            AddError(OverflowErrorMessage(a, "+", b), source);
            return utils::Failure;
        }
    } else {
        using T = UnwrapNumber<NumberT>;
        auto add_values = [](T lhs, T rhs) {
            if constexpr (std::is_integral_v<T> && std::is_signed_v<T>) {
                // Ensure no UB for signed overflow
                using UT = std::make_unsigned_t<T>;
                return static_cast<T>(static_cast<UT>(lhs) + static_cast<UT>(rhs));
            } else {
                return lhs + rhs;
            }
        };
        result = add_values(a.value, b.value);
    }
    return result;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Sub(const Source& source, NumberT a, NumberT b) {
    NumberT result;
    if constexpr (IsAbstract<NumberT> || IsFloatingPoint<NumberT>) {
        if (auto r = CheckedSub(a, b)) {
            result = r->value;
        } else {
            AddError(OverflowErrorMessage(a, "-", b), source);
            return utils::Failure;
        }
    } else {
        using T = UnwrapNumber<NumberT>;
        auto sub_values = [](T lhs, T rhs) {
            if constexpr (std::is_integral_v<T> && std::is_signed_v<T>) {
                // Ensure no UB for signed overflow
                using UT = std::make_unsigned_t<T>;
                return static_cast<T>(static_cast<UT>(lhs) - static_cast<UT>(rhs));
            } else {
                return lhs - rhs;
            }
        };
        result = sub_values(a.value, b.value);
    }
    return result;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Mul(const Source& source, NumberT a, NumberT b) {
    using T = UnwrapNumber<NumberT>;
    NumberT result;
    if constexpr (IsAbstract<NumberT> || IsFloatingPoint<NumberT>) {
        // Check for over/underflow for abstract values
        if (auto r = CheckedMul(a, b)) {
            result = r->value;
        } else {
            AddError(OverflowErrorMessage(a, "*", b), source);
            return utils::Failure;
        }
    } else {
        auto mul_values = [](T lhs, T rhs) {
            if constexpr (std::is_integral_v<T> && std::is_signed_v<T>) {
                // For signed integrals, avoid C++ UB by multiplying as unsigned
                using UT = std::make_unsigned_t<T>;
                return static_cast<T>(static_cast<UT>(lhs) * static_cast<UT>(rhs));
            } else {
                return lhs * rhs;
            }
        };
        result = mul_values(a.value, b.value);
    }
    return result;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Div(const Source& source, NumberT a, NumberT b) {
    NumberT result;
    if constexpr (IsAbstract<NumberT> || IsFloatingPoint<NumberT>) {
        // Check for over/underflow for abstract values
        if (auto r = CheckedDiv(a, b)) {
            result = r->value;
        } else {
            AddError(OverflowErrorMessage(a, "/", b), source);
            return utils::Failure;
        }
    } else {
        using T = UnwrapNumber<NumberT>;
        auto divide_values = [](T lhs, T rhs) {
            if constexpr (std::is_integral_v<T>) {
                // For integers, lhs / 0 returns lhs
                if (rhs == 0) {
                    return lhs;
                }

                if constexpr (std::is_signed_v<T>) {
                    // For signed integers, for lhs / -1, return lhs if lhs is the
                    // most negative value
                    if (rhs == -1 && lhs == std::numeric_limits<T>::min()) {
                        return lhs;
                    }
                }
            }
            return lhs / rhs;
        };
        result = divide_values(a.value, b.value);
    }
    return result;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Dot2(const Source& source,
                                       NumberT a1,
                                       NumberT a2,
                                       NumberT b1,
                                       NumberT b2) {
    auto r1 = Mul(source, a1, b1);
    if (!r1) {
        return utils::Failure;
    }
    auto r2 = Mul(source, a2, b2);
    if (!r2) {
        return utils::Failure;
    }
    auto r = Add(source, r1.Get(), r2.Get());
    if (!r) {
        return utils::Failure;
    }
    return r;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Dot3(const Source& source,
                                       NumberT a1,
                                       NumberT a2,
                                       NumberT a3,
                                       NumberT b1,
                                       NumberT b2,
                                       NumberT b3) {
    auto r1 = Mul(source, a1, b1);
    if (!r1) {
        return utils::Failure;
    }
    auto r2 = Mul(source, a2, b2);
    if (!r2) {
        return utils::Failure;
    }
    auto r3 = Mul(source, a3, b3);
    if (!r3) {
        return utils::Failure;
    }
    auto r = Add(source, r1.Get(), r2.Get());
    if (!r) {
        return utils::Failure;
    }
    r = Add(source, r.Get(), r3.Get());
    if (!r) {
        return utils::Failure;
    }
    return r;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Dot4(const Source& source,
                                       NumberT a1,
                                       NumberT a2,
                                       NumberT a3,
                                       NumberT a4,
                                       NumberT b1,
                                       NumberT b2,
                                       NumberT b3,
                                       NumberT b4) {
    auto r1 = Mul(source, a1, b1);
    if (!r1) {
        return utils::Failure;
    }
    auto r2 = Mul(source, a2, b2);
    if (!r2) {
        return utils::Failure;
    }
    auto r3 = Mul(source, a3, b3);
    if (!r3) {
        return utils::Failure;
    }
    auto r4 = Mul(source, a4, b4);
    if (!r4) {
        return utils::Failure;
    }
    auto r = Add(source, r1.Get(), r2.Get());
    if (!r) {
        return utils::Failure;
    }
    r = Add(source, r.Get(), r3.Get());
    if (!r) {
        return utils::Failure;
    }
    r = Add(source, r.Get(), r4.Get());
    if (!r) {
        return utils::Failure;
    }
    return r;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Det2(const Source& source,
                                       NumberT a,
                                       NumberT b,
                                       NumberT c,
                                       NumberT d) {
    // | a c |
    // | b d |
    //
    // =
    //
    // a * d - c * b

    auto r1 = Mul(source, a, d);
    if (!r1) {
        return utils::Failure;
    }
    auto r2 = Mul(source, c, b);
    if (!r2) {
        return utils::Failure;
    }
    auto r = Sub(source, r1.Get(), r2.Get());
    if (!r) {
        return utils::Failure;
    }
    return r;
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Det3(const Source& source,
                                       NumberT a,
                                       NumberT b,
                                       NumberT c,
                                       NumberT d,
                                       NumberT e,
                                       NumberT f,
                                       NumberT g,
                                       NumberT h,
                                       NumberT i) {
    // | a d g |
    // | b e h |
    // | c f i |
    //
    // =
    //
    // a | e h | - d | b h | + g | b e |
    //   | f i |     | c i |     | c f |

    auto det1 = Det2(source, e, f, h, i);
    if (!det1) {
        return utils::Failure;
    }
    auto a_det1 = Mul(source, a, det1.Get());
    if (!a_det1) {
        return utils::Failure;
    }
    auto det2 = Det2(source, b, c, h, i);
    if (!det2) {
        return utils::Failure;
    }
    auto d_det2 = Mul(source, d, det2.Get());
    if (!d_det2) {
        return utils::Failure;
    }
    auto det3 = Det2(source, b, c, e, f);
    if (!det3) {
        return utils::Failure;
    }
    auto g_det3 = Mul(source, g, det3.Get());
    if (!g_det3) {
        return utils::Failure;
    }
    auto r = Sub(source, a_det1.Get(), d_det2.Get());
    if (!r) {
        return utils::Failure;
    }
    return Add(source, r.Get(), g_det3.Get());
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Det4(const Source& source,
                                       NumberT a,
                                       NumberT b,
                                       NumberT c,
                                       NumberT d,
                                       NumberT e,
                                       NumberT f,
                                       NumberT g,
                                       NumberT h,
                                       NumberT i,
                                       NumberT j,
                                       NumberT k,
                                       NumberT l,
                                       NumberT m,
                                       NumberT n,
                                       NumberT o,
                                       NumberT p) {
    // | a e i m |
    // | b f j n |
    // | c g k o |
    // | d h l p |
    //
    // =
    //
    // a | f j n | - e | b j n | + i | b f n | - m | b f j |
    //   | g k o |     | c k o |     | c g o |     | c g k |
    //   | h l p |     | d l p |     | d h p |     | d h l |

    auto det1 = Det3(source, f, g, h, j, k, l, n, o, p);
    if (!det1) {
        return utils::Failure;
    }
    auto a_det1 = Mul(source, a, det1.Get());
    if (!a_det1) {
        return utils::Failure;
    }
    auto det2 = Det3(source, b, c, d, j, k, l, n, o, p);
    if (!det2) {
        return utils::Failure;
    }
    auto e_det2 = Mul(source, e, det2.Get());
    if (!e_det2) {
        return utils::Failure;
    }
    auto det3 = Det3(source, b, c, d, f, g, h, n, o, p);
    if (!det3) {
        return utils::Failure;
    }
    auto i_det3 = Mul(source, i, det3.Get());
    if (!i_det3) {
        return utils::Failure;
    }
    auto det4 = Det3(source, b, c, d, f, g, h, j, k, l);
    if (!det4) {
        return utils::Failure;
    }
    auto m_det4 = Mul(source, m, det4.Get());
    if (!m_det4) {
        return utils::Failure;
    }
    auto r = Sub(source, a_det1.Get(), e_det2.Get());
    if (!r) {
        return utils::Failure;
    }
    r = Add(source, r.Get(), i_det3.Get());
    if (!r) {
        return utils::Failure;
    }
    return Sub(source, r.Get(), m_det4.Get());
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Sqrt(const Source& source, NumberT v) {
    if (v < NumberT(0)) {
        AddError("sqrt must be called with a value >= 0", source);
        return utils::Failure;
    }
    return NumberT{std::sqrt(v)};
}

auto ConstEval::SqrtFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto v) -> ImplResult {
        if (auto r = Sqrt(source, v)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

template <typename NumberT>
utils::Result<NumberT> ConstEval::Clamp(const Source&, NumberT e, NumberT low, NumberT high) {
    return NumberT{std::min(std::max(e, low), high)};
}

auto ConstEval::ClampFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto e, auto low, auto high) -> ImplResult {
        if (auto r = Clamp(source, e, low, high)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::AddFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2) -> ImplResult {
        if (auto r = Add(source, a1, a2)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::SubFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2) -> ImplResult {
        if (auto r = Sub(source, a1, a2)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::MulFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2) -> ImplResult {
        if (auto r = Mul(source, a1, a2)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::DivFunc(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2) -> ImplResult {
        if (auto r = Div(source, a1, a2)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::Dot2Func(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2, auto b1, auto b2) -> ImplResult {
        if (auto r = Dot2(source, a1, a2, b1, b2)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::Dot3Func(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a1, auto a2, auto a3, auto b1, auto b2, auto b3) -> ImplResult {
        if (auto r = Dot3(source, a1, a2, a3, b1, b2, b3)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::Dot4Func(const Source& source, const sem::Type* elem_ty) {
    return
        [=](auto a1, auto a2, auto a3, auto a4, auto b1, auto b2, auto b3, auto b4) -> ImplResult {
            if (auto r = Dot4(source, a1, a2, a3, a4, b1, b2, b3, b4)) {
                return CreateElement(builder, source, elem_ty, r.Get());
            }
            return utils::Failure;
        };
}

ConstEval::Result ConstEval::Dot(const Source& source,
                                 const sem::Constant* v1,
                                 const sem::Constant* v2) {
    auto* vec_ty = v1->Type()->As<sem::Vector>();
    TINT_ASSERT(Resolver, vec_ty);
    auto* elem_ty = vec_ty->type();
    switch (vec_ty->Width()) {
        case 2:
            return Dispatch_fia_fiu32_f16(   //
                Dot2Func(source, elem_ty),   //
                v1->Index(0), v1->Index(1),  //
                v2->Index(0), v2->Index(1));
        case 3:
            return Dispatch_fia_fiu32_f16(                 //
                Dot3Func(source, elem_ty),                 //
                v1->Index(0), v1->Index(1), v1->Index(2),  //
                v2->Index(0), v2->Index(1), v2->Index(2));
        case 4:
            return Dispatch_fia_fiu32_f16(                               //
                Dot4Func(source, elem_ty),                               //
                v1->Index(0), v1->Index(1), v1->Index(2), v1->Index(3),  //
                v2->Index(0), v2->Index(1), v2->Index(2), v2->Index(3));
    }
    TINT_ICE(Resolver, builder.Diagnostics()) << "Expected vector";
    return utils::Failure;
}

auto ConstEval::Det2Func(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a, auto b, auto c, auto d) -> ImplResult {
        if (auto r = Det2(source, a, b, c, d)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

auto ConstEval::Det3Func(const Source& source, const sem::Type* elem_ty) {
    return
        [=](auto a, auto b, auto c, auto d, auto e, auto f, auto g, auto h, auto i) -> ImplResult {
            if (auto r = Det3(source, a, b, c, d, e, f, g, h, i)) {
                return CreateElement(builder, source, elem_ty, r.Get());
            }
            return utils::Failure;
        };
}

auto ConstEval::Det4Func(const Source& source, const sem::Type* elem_ty) {
    return [=](auto a, auto b, auto c, auto d, auto e, auto f, auto g, auto h, auto i, auto j,
               auto k, auto l, auto m, auto n, auto o, auto p) -> ImplResult {
        if (auto r = Det4(source, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p)) {
            return CreateElement(builder, source, elem_ty, r.Get());
        }
        return utils::Failure;
    };
}

ConstEval::Result ConstEval::Literal(const sem::Type* ty, const ast::LiteralExpression* literal) {
    auto& source = literal->source;
    return Switch(
        literal,
        [&](const ast::BoolLiteralExpression* lit) {
            return CreateElement(builder, source, ty, lit->value);
        },
        [&](const ast::IntLiteralExpression* lit) -> ImplResult {
            switch (lit->suffix) {
                case ast::IntLiteralExpression::Suffix::kNone:
                    return CreateElement(builder, source, ty, AInt(lit->value));
                case ast::IntLiteralExpression::Suffix::kI:
                    return CreateElement(builder, source, ty, i32(lit->value));
                case ast::IntLiteralExpression::Suffix::kU:
                    return CreateElement(builder, source, ty, u32(lit->value));
            }
            return nullptr;
        },
        [&](const ast::FloatLiteralExpression* lit) -> ImplResult {
            switch (lit->suffix) {
                case ast::FloatLiteralExpression::Suffix::kNone:
                    return CreateElement(builder, source, ty, AFloat(lit->value));
                case ast::FloatLiteralExpression::Suffix::kF:
                    return CreateElement(builder, source, ty, f32(lit->value));
                case ast::FloatLiteralExpression::Suffix::kH:
                    return CreateElement(builder, source, ty, f16(lit->value));
            }
            return nullptr;
        });
}

ConstEval::Result ConstEval::ArrayOrStructInit(const sem::Type* ty,
                                               utils::VectorRef<const sem::Expression*> args) {
    if (args.IsEmpty()) {
        return ZeroValue(builder, ty);
    }

    if (args.Length() == 1 && args[0]->Type() == ty) {
        // Identity initializer.
        return args[0]->ConstantValue();
    }

    // Multiple arguments. Must be a type initializer.
    utils::Vector<const sem::Constant*, 4> els;
    els.Reserve(args.Length());
    for (auto* arg : args) {
        els.Push(arg->ConstantValue());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::Conv(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    uint32_t el_count = 0;
    auto* el_ty = sem::Type::ElementOf(ty, &el_count);
    if (!el_ty) {
        return nullptr;
    }

    if (!args[0]) {
        return nullptr;  // Single argument is not constant.
    }

    return Convert(ty, args[0], source);
}

ConstEval::Result ConstEval::Zero(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*>,
                                  const Source&) {
    return ZeroValue(builder, ty);
}

ConstEval::Result ConstEval::Identity(const sem::Type*,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    return args[0];
}

ConstEval::Result ConstEval::VecSplat(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    if (auto* arg = args[0]) {
        return builder.create<Splat>(ty, arg, static_cast<const sem::Vector*>(ty)->Width());
    }
    return nullptr;
}

ConstEval::Result ConstEval::VecInitS(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    return CreateComposite(builder, ty, args);
}

ConstEval::Result ConstEval::VecInitM(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    utils::Vector<const sem::Constant*, 4> els;
    for (auto* arg : args) {
        auto* val = arg;
        if (!val) {
            return nullptr;
        }
        auto* arg_ty = arg->Type();
        if (auto* arg_vec = arg_ty->As<sem::Vector>()) {
            // Extract out vector elements.
            for (uint32_t j = 0; j < arg_vec->Width(); j++) {
                auto* el = val->Index(j);
                if (!el) {
                    return nullptr;
                }
                els.Push(el);
            }
        } else {
            els.Push(val);
        }
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::MatInitS(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    auto* m = static_cast<const sem::Matrix*>(ty);

    utils::Vector<const sem::Constant*, 4> els;
    for (uint32_t c = 0; c < m->columns(); c++) {
        utils::Vector<const sem::Constant*, 4> column;
        for (uint32_t r = 0; r < m->rows(); r++) {
            auto i = r + c * m->rows();
            column.Push(args[i]);
        }
        els.Push(CreateComposite(builder, m->ColumnType(), std::move(column)));
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::MatInitV(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source&) {
    return CreateComposite(builder, ty, args);
}

ConstEval::Result ConstEval::Index(const sem::Expression* obj_expr,
                                   const sem::Expression* idx_expr) {
    auto idx_val = idx_expr->ConstantValue();
    if (!idx_val) {
        return nullptr;
    }

    uint32_t el_count = 0;
    sem::Type::ElementOf(obj_expr->Type()->UnwrapRef(), &el_count);

    AInt idx = idx_val->As<AInt>();
    if (idx < 0 || (el_count > 0 && idx >= el_count)) {
        std::string range;
        if (el_count > 0) {
            range = " [0.." + std::to_string(el_count - 1) + "]";
        }
        AddError("index " + std::to_string(idx) + " out of bounds" + range,
                 idx_expr->Declaration()->source);
        return utils::Failure;
    }

    auto obj_val = obj_expr->ConstantValue();
    if (!obj_val) {
        return nullptr;
    }

    return obj_val->Index(static_cast<size_t>(idx));
}

ConstEval::Result ConstEval::MemberAccess(const sem::Expression* obj_expr,
                                          const sem::StructMember* member) {
    auto obj_val = obj_expr->ConstantValue();
    if (!obj_val) {
        return nullptr;
    }
    return obj_val->Index(static_cast<size_t>(member->Index()));
}

ConstEval::Result ConstEval::Swizzle(const sem::Type* ty,
                                     const sem::Expression* vec_expr,
                                     utils::VectorRef<uint32_t> indices) {
    auto* vec_val = vec_expr->ConstantValue();
    if (!vec_val) {
        return nullptr;
    }
    if (indices.Length() == 1) {
        return vec_val->Index(static_cast<size_t>(indices[0]));
    }
    auto values = utils::Transform<4>(
        indices, [&](uint32_t i) { return vec_val->Index(static_cast<size_t>(i)); });
    return CreateComposite(builder, ty, std::move(values));
}

ConstEval::Result ConstEval::Bitcast(const sem::Type*, const sem::Expression*) {
    // TODO(crbug.com/tint/1581): Implement @const intrinsics
    return nullptr;
}

ConstEval::Result ConstEval::OpComplement(const sem::Type* ty,
                                          utils::VectorRef<const sem::Constant*> args,
                                          const Source& source) {
    auto transform = [&](const sem::Constant* c) {
        auto create = [&](auto i) {
            return CreateElement(builder, source, c->Type(), decltype(i)(~i.value));
        };
        return Dispatch_ia_iu32(create, c);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::OpUnaryMinus(const sem::Type* ty,
                                          utils::VectorRef<const sem::Constant*> args,
                                          const Source& source) {
    auto transform = [&](const sem::Constant* c) {
        auto create = [&](auto i) {
            // For signed integrals, avoid C++ UB by not negating the
            // smallest negative number. In WGSL, this operation is well
            // defined to return the same value, see:
            // https://gpuweb.github.io/gpuweb/wgsl/#arithmetic-expr.
            using T = UnwrapNumber<decltype(i)>;
            if constexpr (std::is_integral_v<T>) {
                auto v = i.value;
                if (v != std::numeric_limits<T>::min()) {
                    v = -v;
                }
                return CreateElement(builder, source, c->Type(), decltype(i)(v));
            } else {
                return CreateElement(builder, source, c->Type(), decltype(i)(-i.value));
            }
        };
        return Dispatch_fia_fi32_f16(create, c);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::OpNot(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c) {
        auto create = [&](auto i) {
            return CreateElement(builder, source, c->Type(), decltype(i)(!i));
        };
        return Dispatch_bool(create, c);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::OpPlus(const sem::Type* ty,
                                    utils::VectorRef<const sem::Constant*> args,
                                    const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        return Dispatch_fia_fiu32_f16(AddFunc(source, c0->Type()), c0, c1);
    };

    return TransformBinaryElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpMinus(const sem::Type* ty,
                                     utils::VectorRef<const sem::Constant*> args,
                                     const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        return Dispatch_fia_fiu32_f16(SubFunc(source, c0->Type()), c0, c1);
    };

    return TransformBinaryElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpMultiply(const sem::Type* ty,
                                        utils::VectorRef<const sem::Constant*> args,
                                        const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        return Dispatch_fia_fiu32_f16(MulFunc(source, c0->Type()), c0, c1);
    };

    return TransformBinaryElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpMultiplyMatVec(const sem::Type* ty,
                                              utils::VectorRef<const sem::Constant*> args,
                                              const Source& source) {
    auto* mat_ty = args[0]->Type()->As<sem::Matrix>();
    auto* vec_ty = args[1]->Type()->As<sem::Vector>();
    auto* elem_ty = vec_ty->type();

    auto dot = [&](const sem::Constant* m, size_t row, const sem::Constant* v) {
        ImplResult result;
        switch (mat_ty->columns()) {
            case 2:
                result = Dispatch_fa_f32_f16(Dot2Func(source, elem_ty),  //
                                             m->Index(0)->Index(row),    //
                                             m->Index(1)->Index(row),    //
                                             v->Index(0),                //
                                             v->Index(1));
                break;
            case 3:
                result = Dispatch_fa_f32_f16(Dot3Func(source, elem_ty),  //
                                             m->Index(0)->Index(row),    //
                                             m->Index(1)->Index(row),    //
                                             m->Index(2)->Index(row),    //
                                             v->Index(0),                //
                                             v->Index(1), v->Index(2));
                break;
            case 4:
                result = Dispatch_fa_f32_f16(Dot4Func(source, elem_ty),  //
                                             m->Index(0)->Index(row),    //
                                             m->Index(1)->Index(row),    //
                                             m->Index(2)->Index(row),    //
                                             m->Index(3)->Index(row),    //
                                             v->Index(0),                //
                                             v->Index(1),                //
                                             v->Index(2),                //
                                             v->Index(3));
                break;
        }
        return result;
    };

    utils::Vector<const sem::Constant*, 4> result;
    for (size_t i = 0; i < mat_ty->rows(); ++i) {
        auto r = dot(args[0], i, args[1]);  // matrix row i * vector
        if (!r) {
            return utils::Failure;
        }
        result.Push(r.Get());
    }
    return CreateComposite(builder, ty, result);
}
ConstEval::Result ConstEval::OpMultiplyVecMat(const sem::Type* ty,
                                              utils::VectorRef<const sem::Constant*> args,
                                              const Source& source) {
    auto* vec_ty = args[0]->Type()->As<sem::Vector>();
    auto* mat_ty = args[1]->Type()->As<sem::Matrix>();
    auto* elem_ty = vec_ty->type();

    auto dot = [&](const sem::Constant* v, const sem::Constant* m, size_t col) {
        ImplResult result;
        switch (mat_ty->rows()) {
            case 2:
                result = Dispatch_fa_f32_f16(Dot2Func(source, elem_ty),  //
                                             m->Index(col)->Index(0),    //
                                             m->Index(col)->Index(1),    //
                                             v->Index(0),                //
                                             v->Index(1));
                break;
            case 3:
                result = Dispatch_fa_f32_f16(Dot3Func(source, elem_ty),  //
                                             m->Index(col)->Index(0),    //
                                             m->Index(col)->Index(1),    //
                                             m->Index(col)->Index(2),
                                             v->Index(0),  //
                                             v->Index(1),  //
                                             v->Index(2));
                break;
            case 4:
                result = Dispatch_fa_f32_f16(Dot4Func(source, elem_ty),  //
                                             m->Index(col)->Index(0),    //
                                             m->Index(col)->Index(1),    //
                                             m->Index(col)->Index(2),    //
                                             m->Index(col)->Index(3),    //
                                             v->Index(0),                //
                                             v->Index(1),                //
                                             v->Index(2),                //
                                             v->Index(3));
        }
        return result;
    };

    utils::Vector<const sem::Constant*, 4> result;
    for (size_t i = 0; i < mat_ty->columns(); ++i) {
        auto r = dot(args[0], args[1], i);  // vector * matrix col i
        if (!r) {
            return utils::Failure;
        }
        result.Push(r.Get());
    }
    return CreateComposite(builder, ty, result);
}

ConstEval::Result ConstEval::OpMultiplyMatMat(const sem::Type* ty,
                                              utils::VectorRef<const sem::Constant*> args,
                                              const Source& source) {
    auto* mat1 = args[0];
    auto* mat2 = args[1];
    auto* mat1_ty = mat1->Type()->As<sem::Matrix>();
    auto* mat2_ty = mat2->Type()->As<sem::Matrix>();
    auto* elem_ty = mat1_ty->type();

    auto dot = [&](const sem::Constant* m1, size_t row, const sem::Constant* m2, size_t col) {
        auto m1e = [&](size_t r, size_t c) { return m1->Index(c)->Index(r); };
        auto m2e = [&](size_t r, size_t c) { return m2->Index(c)->Index(r); };

        ImplResult result;
        switch (mat1_ty->columns()) {
            case 2:
                result = Dispatch_fa_f32_f16(Dot2Func(source, elem_ty),  //
                                             m1e(row, 0),                //
                                             m1e(row, 1),                //
                                             m2e(0, col),                //
                                             m2e(1, col));
                break;
            case 3:
                result = Dispatch_fa_f32_f16(Dot3Func(source, elem_ty),  //
                                             m1e(row, 0),                //
                                             m1e(row, 1),                //
                                             m1e(row, 2),                //
                                             m2e(0, col),                //
                                             m2e(1, col),                //
                                             m2e(2, col));
                break;
            case 4:
                result = Dispatch_fa_f32_f16(Dot4Func(source, elem_ty),  //
                                             m1e(row, 0),                //
                                             m1e(row, 1),                //
                                             m1e(row, 2),                //
                                             m1e(row, 3),                //
                                             m2e(0, col),                //
                                             m2e(1, col),                //
                                             m2e(2, col),                //
                                             m2e(3, col));
                break;
        }
        return result;
    };

    utils::Vector<const sem::Constant*, 4> result_mat;
    for (size_t c = 0; c < mat2_ty->columns(); ++c) {
        utils::Vector<const sem::Constant*, 4> col_vec;
        for (size_t r = 0; r < mat1_ty->rows(); ++r) {
            auto v = dot(mat1, r, mat2, c);  // mat1 row r * mat2 col c
            if (!v) {
                return utils::Failure;
            }
            col_vec.Push(v.Get());  // mat1 row r * mat2 col c
        }

        // Add column vector to matrix
        auto* col_vec_ty = ty->As<sem::Matrix>()->ColumnType();
        result_mat.Push(CreateComposite(builder, col_vec_ty, col_vec));
    }
    return CreateComposite(builder, ty, result_mat);
}

ConstEval::Result ConstEval::OpDivide(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        return Dispatch_fia_fiu32_f16(DivFunc(source, c0->Type()), c0, c1);
    };

    return TransformBinaryElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpEqual(const sem::Type* ty,
                                     utils::VectorRef<const sem::Constant*> args,
                                     const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i == j);
        };
        return Dispatch_fia_fiu32_f16_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpNotEqual(const sem::Type* ty,
                                        utils::VectorRef<const sem::Constant*> args,
                                        const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i != j);
        };
        return Dispatch_fia_fiu32_f16_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpLessThan(const sem::Type* ty,
                                        utils::VectorRef<const sem::Constant*> args,
                                        const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i < j);
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpGreaterThan(const sem::Type* ty,
                                           utils::VectorRef<const sem::Constant*> args,
                                           const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i > j);
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpLessThanEqual(const sem::Type* ty,
                                             utils::VectorRef<const sem::Constant*> args,
                                             const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i <= j);
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpGreaterThanEqual(const sem::Type* ty,
                                                utils::VectorRef<const sem::Constant*> args,
                                                const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), i >= j);
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpAnd(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            using T = decltype(i);
            T result;
            if constexpr (std::is_same_v<T, bool>) {
                result = i && j;
            } else {  // integral
                result = i & j;
            }
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), result);
        };
        return Dispatch_ia_iu32_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpOr(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            using T = decltype(i);
            T result;
            if constexpr (std::is_same_v<T, bool>) {
                result = i || j;
            } else {  // integral
                result = i | j;
            }
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), result);
        };
        return Dispatch_ia_iu32_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpXor(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty),
                                 decltype(i){i ^ j});
        };
        return Dispatch_ia_iu32(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::OpShiftLeft(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto e1, auto e2) -> ImplResult {
            using NumberT = decltype(e1);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            constexpr size_t bit_width = BitWidth<NumberT>;
            UT e1u = static_cast<UT>(e1);
            UT e2u = static_cast<UT>(e2);

            if constexpr (IsAbstract<NumberT>) {
                // The e2 + 1 most significant bits of e1 must have the same bit value, otherwise
                // sign change (overflow) would occur.
                // Check sign change only if e2 is less than bit width of e1. If e1 is larger
                // than bit width, we check for non-representable value below.
                if (e2u < bit_width) {
                    UT must_match_msb = e2u + 1;
                    UT mask = ~UT{0} << (bit_width - must_match_msb);
                    if ((e1u & mask) != 0 && (e1u & mask) != mask) {
                        AddError("shift left operation results in sign change", source);
                        return utils::Failure;
                    }
                } else {
                    // If shift value >= bit_width, then any non-zero value would overflow
                    if (e1 != 0) {
                        AddError(OverflowErrorMessage(e1, "<<", e2), source);
                        return utils::Failure;
                    }

                    // It's UB in C++ to shift by greater or equal to the bit width (even if the lhs
                    // is 0), so we make sure to avoid this by setting the shift value to 0.
                    e2 = 0;
                }
            } else {
                if (static_cast<size_t>(e2) >= bit_width) {
                    // At shader/pipeline-creation time, it is an error to shift by the bit width of
                    // the lhs or greater.
                    // NOTE: At runtime, we shift by e2 % (bit width of e1).
                    AddError(
                        "shift left value must be less than the bit width of the lhs, which is " +
                            std::to_string(bit_width),
                        source);
                    return utils::Failure;
                }

                if constexpr (std::is_signed_v<T>) {
                    // If T is a signed integer type, and the e2+1 most significant bits of e1 do
                    // not have the same bit value, then error.
                    size_t must_match_msb = e2u + 1;
                    UT mask = ~UT{0} << (bit_width - must_match_msb);
                    if ((e1u & mask) != 0 && (e1u & mask) != mask) {
                        AddError("shift left operation results in sign change", source);
                        return utils::Failure;
                    }
                } else {
                    // If T is an unsigned integer type, and any of the e2 most significant bits of
                    // e1 are 1, then error.
                    if (e2u > 0) {
                        size_t must_be_zero_msb = e2u;
                        UT mask = ~UT{0} << (bit_width - must_be_zero_msb);
                        if ((e1u & mask) != 0) {
                            AddError(OverflowErrorMessage(e1, "<<", e2), source);
                            return utils::Failure;
                        }
                    }
                }
            }

            // Avoid UB by left shifting as unsigned value
            auto result = static_cast<T>(static_cast<UT>(e1) << e2);
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), NumberT{result});
        };
        return Dispatch_ia_iu32(create, c0, c1);
    };

    if (!sem::Type::DeepestElementOf(args[1]->Type())->Is<sem::U32>()) {
        TINT_ICE(Resolver, builder.Diagnostics())
            << "Element type of rhs of ShiftLeft must be a u32";
        return utils::Failure;
    }

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::abs(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            NumberT result;
            if constexpr (IsUnsignedIntegral<NumberT>) {
                result = e;
            } else if constexpr (IsSignedIntegral<NumberT>) {
                if (e == NumberT::Lowest()) {
                    result = e;
                } else {
                    result = NumberT{std::abs(e)};
                }
            } else {
                result = NumberT{std::abs(e)};
            }
            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_fia_fiu32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::acos(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            if (i < NumberT(-1.0) || i > NumberT(1.0)) {
                AddError("acos must be called with a value in the range [-1 .. 1] (inclusive)",
                         source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::acos(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::acosh(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            if (i < NumberT(1.0)) {
                AddError("acosh must be called with a value >= 1.0", source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::acosh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };

    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::all(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    return CreateElement(builder, source, ty, !args[0]->AnyZero());
}

ConstEval::Result ConstEval::any(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    return CreateElement(builder, source, ty, !args[0]->AllZero());
}

ConstEval::Result ConstEval::asin(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            if (i < NumberT(-1.0) || i > NumberT(1.0)) {
                AddError("asin must be called with a value in the range [-1 .. 1] (inclusive)",
                         source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::asin(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::asinh(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) {
            return CreateElement(builder, source, c0->Type(), decltype(i)(std::asinh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };

    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::atan(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) {
            return CreateElement(builder, source, c0->Type(), decltype(i)(std::atan(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::atanh(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            if (i <= NumberT(-1.0) || i >= NumberT(1.0)) {
                AddError("atanh must be called with a value in the range (-1 .. 1) (exclusive)",
                         source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::atanh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };

    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::atan2(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto i, auto j) {
            return CreateElement(builder, source, c0->Type(),
                                 decltype(i)(std::atan2(i.value, j.value)));
        };
        return Dispatch_fa_f32_f16(create, c0, c1);
    };
    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::ceil(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            return CreateElement(builder, source, c0->Type(), decltype(e)(std::ceil(e)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::clamp(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1,
                         const sem::Constant* c2) {
        return Dispatch_fia_fiu32_f16(ClampFunc(source, c0->Type()), c0, c1, c2);
    };
    return TransformElements(builder, ty, transform, args[0], args[1], args[2]);
}

ConstEval::Result ConstEval::cos(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::cos(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::cosh(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::cosh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::countLeadingZeros(const sem::Type* ty,
                                               utils::VectorRef<const sem::Constant*> args,
                                               const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;
            auto count = CountLeadingBits(T{e}, T{0});
            return CreateElement(builder, source, c0->Type(), NumberT(count));
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::countOneBits(const sem::Type* ty,
                                          utils::VectorRef<const sem::Constant*> args,
                                          const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            constexpr UT kRightMost = UT{1};

            auto count = UT{0};
            for (auto v = static_cast<UT>(e); v != UT{0}; v >>= 1) {
                if ((v & kRightMost) == 1) {
                    ++count;
                }
            }

            return CreateElement(builder, source, c0->Type(), NumberT(count));
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::countTrailingZeros(const sem::Type* ty,
                                                utils::VectorRef<const sem::Constant*> args,
                                                const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;
            auto count = CountTrailingBits(T{e}, T{0});
            return CreateElement(builder, source, c0->Type(), NumberT(count));
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::cross(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto* u = args[0];
    auto* v = args[1];
    auto* elem_ty = u->Type()->As<sem::Vector>()->type();

    // cross product of a v3 is the determinant of the 3x3 matrix:
    //
    // |i   j   k |
    // |u0  u1  u2|
    // |v0  v1  v2|
    //
    // |u1 u2|i  - |u0 u2|j + |u0 u1|k
    // |v1 v2|     |v0 v2|    |v0 v1|
    //
    // |u1 u2|i  + |v0 v2|j + |u0 u1|k
    // |v1 v2|     |u0 u2|    |v0 v1|

    auto* u0 = u->Index(0);
    auto* u1 = u->Index(1);
    auto* u2 = u->Index(2);
    auto* v0 = v->Index(0);
    auto* v1 = v->Index(1);
    auto* v2 = v->Index(2);

    auto x = Dispatch_fa_f32_f16(Det2Func(source, elem_ty), u1, u2, v1, v2);
    if (!x) {
        return utils::Failure;
    }
    auto y = Dispatch_fa_f32_f16(Det2Func(source, elem_ty), v0, v2, u0, u2);
    if (!y) {
        return utils::Failure;
    }
    auto z = Dispatch_fa_f32_f16(Det2Func(source, elem_ty), u0, u1, v0, v1);
    if (!z) {
        return utils::Failure;
    }

    return CreateComposite(builder, ty,
                           utils::Vector<const sem::Constant*, 3>{x.Get(), y.Get(), z.Get()});
}

ConstEval::Result ConstEval::degrees(const sem::Type* ty,
                                     utils::VectorRef<const sem::Constant*> args,
                                     const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) -> ImplResult {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;

            auto pi = kPi<T>;
            auto scale = Div(source, NumberT(180), NumberT(pi));
            if (!scale) {
                AddNote("when calculating degrees", source);
                return utils::Failure;
            }
            auto result = Mul(source, e, scale.Get());
            if (!result) {
                AddNote("when calculating degrees", source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), result.Get());
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::determinant(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto calculate = [&]() -> ImplResult {
        auto* m = args[0];
        auto* mat_ty = m->Type()->As<sem::Matrix>();
        auto me = [&](size_t r, size_t c) { return m->Index(c)->Index(r); };
        switch (mat_ty->rows()) {
            case 2:
                return Dispatch_fa_f32_f16(Det2Func(source, ty),  //
                                           me(0, 0), me(1, 0),    //
                                           me(0, 1), me(1, 1));

            case 3:
                return Dispatch_fa_f32_f16(Det3Func(source, ty),          //
                                           me(0, 0), me(1, 0), me(2, 0),  //
                                           me(0, 1), me(1, 1), me(2, 1),  //
                                           me(0, 2), me(1, 2), me(2, 2));

            case 4:
                return Dispatch_fa_f32_f16(Det4Func(source, ty),                    //
                                           me(0, 0), me(1, 0), me(2, 0), me(3, 0),  //
                                           me(0, 1), me(1, 1), me(2, 1), me(3, 1),  //
                                           me(0, 2), me(1, 2), me(2, 2), me(3, 2),  //
                                           me(0, 3), me(1, 3), me(2, 3), me(3, 3));
        }
        TINT_ICE(Resolver, builder.Diagnostics()) << "Unexpected number of matrix rows";
        return utils::Failure;
    };
    auto r = calculate();
    if (!r) {
        AddNote("when calculating determinant", source);
    }
    return r;
}
ConstEval::Result ConstEval::dot(const sem::Type*,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto r = Dot(source, args[0], args[1]);
    if (!r) {
        AddNote("when calculating dot", source);
    }
    return r;
}

ConstEval::Result ConstEval::exp(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e0) -> ImplResult {
            using NumberT = decltype(e0);
            auto val = NumberT(std::exp(e0));
            if (!std::isfinite(val.value)) {
                AddError(OverflowExpErrorMessage("e", e0), source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), val);
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::exp2(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e0) -> ImplResult {
            using NumberT = decltype(e0);
            auto val = NumberT(std::exp2(e0));
            if (!std::isfinite(val.value)) {
                AddError(OverflowExpErrorMessage("2", e0), source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), val);
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::extractBits(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto in_e) -> ImplResult {
            using NumberT = decltype(in_e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            using NumberUT = Number<UT>;

            // Read args that are always scalar
            NumberUT in_offset = args[1]->As<NumberUT>();
            NumberUT in_count = args[2]->As<NumberUT>();

            // Cast all to unsigned
            UT e = static_cast<UT>(in_e);
            UT o = static_cast<UT>(in_offset);
            UT c = static_cast<UT>(in_count);

            constexpr UT w = sizeof(UT) * 8;
            if (o > w || c > w || (o + c) > w) {
                AddError("'offset + 'count' must be less than or equal to the bit width of 'e'",
                         source);
                return utils::Failure;
            }

            NumberT result;
            if (c == UT{0}) {
                // The result is 0 if c is 0
                result = NumberT{0};
            } else if (c == w) {
                // The result is e if c is w
                result = NumberT{e};
            } else {
                // Otherwise, bits 0..c - 1 of the result are copied from bits o..o + c - 1 of e.
                UT src_mask = ((UT{1} << c) - UT{1}) << o;
                UT r = (e & src_mask) >> o;
                if constexpr (IsSignedIntegral<NumberT>) {
                    // Other bits of the result are the same as bit c - 1 of the result.
                    // Only need to set other bits if bit at c - 1 of result is 1
                    if ((r & (UT{1} << (c - UT{1}))) != UT{0}) {
                        UT dst_mask = src_mask >> o;
                        r |= (~UT{0} & ~dst_mask);
                    }
                }

                result = NumberT{r};
            }
            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::firstLeadingBit(const sem::Type* ty,
                                             utils::VectorRef<const sem::Constant*> args,
                                             const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            constexpr UT kNumBits = sizeof(UT) * 8;

            NumberT result;
            if constexpr (IsUnsignedIntegral<T>) {
                if (e == T{0}) {
                    // T(-1) if e is zero.
                    result = NumberT(static_cast<T>(-1));
                } else {
                    // Otherwise the position of the most significant 1 bit in e.
                    static_assert(std::is_same_v<T, UT>);
                    UT count = CountLeadingBits(UT{e}, UT{0});
                    UT pos = kNumBits - count - 1;
                    result = NumberT(pos);
                }
            } else {
                if (e == T{0} || e == T{-1}) {
                    // -1 if e is 0 or -1.
                    result = NumberT(-1);
                } else {
                    // Otherwise the position of the most significant bit in e that is different
                    // from e's sign bit.
                    UT eu = static_cast<UT>(e);
                    UT sign_bit = eu >> (kNumBits - 1);
                    UT count = CountLeadingBits(eu, sign_bit);
                    UT pos = kNumBits - count - 1;
                    result = NumberT(pos);
                }
            }

            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::firstTrailingBit(const sem::Type* ty,
                                              utils::VectorRef<const sem::Constant*> args,
                                              const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;

            NumberT result;
            if (e == T{0}) {
                // T(-1) if e is zero.
                result = NumberT(static_cast<T>(-1));
            } else {
                // Otherwise the position of the least significant 1 bit in e.
                UT pos = CountTrailingBits(T{e}, T{0});
                result = NumberT(pos);
            }

            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::floor(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            return CreateElement(builder, source, c0->Type(), decltype(e)(std::floor(e)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::frexp(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto* arg = args[0];

    struct FractExp {
        ImplResult fract;
        ImplResult exp;
    };

    auto scalar = [&](const sem::Constant* s) {
        int exp = 0;
        double fract = std::frexp(s->As<AFloat>(), &exp);
        return Switch(
            s->Type(),
            [&](const sem::F32*) {
                return FractExp{
                    CreateElement(builder, source, builder.create<sem::F32>(), f32(fract)),
                    CreateElement(builder, source, builder.create<sem::I32>(), i32(exp)),
                };
            },
            [&](const sem::F16*) {
                return FractExp{
                    CreateElement(builder, source, builder.create<sem::F16>(), f16(fract)),
                    CreateElement(builder, source, builder.create<sem::I32>(), i32(exp)),
                };
            },
            [&](const sem::AbstractFloat*) {
                return FractExp{
                    CreateElement(builder, source, builder.create<sem::AbstractFloat>(),
                                  AFloat(fract)),
                    CreateElement(builder, source, builder.create<sem::AbstractInt>(), AInt(exp)),
                };
            },
            [&](Default) {
                TINT_ICE(Resolver, builder.Diagnostics())
                    << "unhandled element type for frexp() const-eval: "
                    << builder.FriendlyName(s->Type());
                return FractExp{utils::Failure, utils::Failure};
            });
    };

    if (auto* vec = arg->Type()->As<sem::Vector>()) {
        utils::Vector<const sem::Constant*, 4> fract_els;
        utils::Vector<const sem::Constant*, 4> exp_els;
        for (uint32_t i = 0; i < vec->Width(); i++) {
            auto fe = scalar(arg->Index(i));
            if (!fe.fract || !fe.exp) {
                return utils::Failure;
            }
            fract_els.Push(fe.fract.Get());
            exp_els.Push(fe.exp.Get());
        }
        auto fract_ty = builder.create<sem::Vector>(fract_els[0]->Type(), vec->Width());
        auto exp_ty = builder.create<sem::Vector>(exp_els[0]->Type(), vec->Width());
        return CreateComposite(builder, ty,
                               utils::Vector<const sem::Constant*, 2>{
                                   CreateComposite(builder, fract_ty, std::move(fract_els)),
                                   CreateComposite(builder, exp_ty, std::move(exp_els)),
                               });
    } else {
        auto fe = scalar(arg);
        if (!fe.fract || !fe.exp) {
            return utils::Failure;
        }
        return CreateComposite(builder, ty,
                               utils::Vector<const sem::Constant*, 2>{
                                   fe.fract.Get(),
                                   fe.exp.Get(),
                               });
    }
}

ConstEval::Result ConstEval::insertBits(const sem::Type* ty,
                                        utils::VectorRef<const sem::Constant*> args,
                                        const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto in_e, auto in_newbits) -> ImplResult {
            using NumberT = decltype(in_e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            using NumberUT = Number<UT>;

            // Read args that are always scalar
            NumberUT in_offset = args[2]->As<NumberUT>();
            NumberUT in_count = args[3]->As<NumberUT>();

            // Cast all to unsigned
            UT e = static_cast<UT>(in_e);
            UT newbits = static_cast<UT>(in_newbits);
            UT o = static_cast<UT>(in_offset);
            UT c = static_cast<UT>(in_count);

            constexpr UT w = sizeof(UT) * 8;
            if (o > w || c > w || (o + c) > w) {
                AddError("'offset + 'count' must be less than or equal to the bit width of 'e'",
                         source);
                return utils::Failure;
            }

            NumberT result;
            if (c == UT{0}) {
                // The result is e if c is 0
                result = NumberT{e};
            } else if (c == w) {
                // The result is newbits if c is w
                result = NumberT{newbits};
            } else {
                // Otherwise, bits o..o + c - 1 of the result are copied from bits 0..c - 1 of
                // newbits. Other bits of the result are copied from e.
                UT from = newbits << o;
                UT mask = ((UT{1} << c) - UT{1}) << UT{o};
                auto r = e;          // Start with 'e' as the result
                r &= ~mask;          // Zero the bits in 'e' we're overwriting
                r |= (from & mask);  // Overwrite from 'newbits' (shifted into position)
                result = NumberT{r};
            }

            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_iu32(create, c0, c1);
    };
    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::inverseSqrt(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) -> ImplResult {
            using NumberT = decltype(e);

            if (e <= NumberT(0)) {
                AddError("inverseSqrt must be called with a value > 0", source);
                return utils::Failure;
            }

            auto err = [&] {
                AddNote("when calculating inverseSqrt", source);
                return utils::Failure;
            };

            auto s = Sqrt(source, e);
            if (!s) {
                return err();
            }
            auto div = Div(source, NumberT(1), s.Get());
            if (!div) {
                return err();
            }

            return CreateElement(builder, source, c0->Type(), div.Get());
        };
        return Dispatch_fa_f32_f16(create, c0);
    };

    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::length(const sem::Type* ty,
                                    utils::VectorRef<const sem::Constant*> args,
                                    const Source& source) {
    auto calculate = [&]() -> ImplResult {
        auto* vec_ty = args[0]->Type()->As<sem::Vector>();

        // Evaluates to the absolute value of e if T is scalar.
        if (vec_ty == nullptr) {
            auto create = [&](auto e) {
                using NumberT = decltype(e);
                return CreateElement(builder, source, ty, NumberT{std::abs(e)});
            };
            return Dispatch_fa_f32_f16(create, args[0]);
        }

        // Evaluates to sqrt(e[0]^2 + e[1]^2 + ...) if T is a vector type.
        auto d = Dot(source, args[0], args[0]);
        if (!d) {
            return utils::Failure;
        }
        return Dispatch_fa_f32_f16(SqrtFunc(source, ty), d.Get());
    };
    auto r = calculate();
    if (!r) {
        AddNote("when calculating length", source);
    }
    return r;
}

ConstEval::Result ConstEval::log(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto v) -> ImplResult {
            using NumberT = decltype(v);
            if (v <= NumberT(0)) {
                AddError("log must be called with a value > 0", source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::log(v)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::log2(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto v) -> ImplResult {
            using NumberT = decltype(v);
            if (v <= NumberT(0)) {
                AddError("log2 must be called with a value > 0", source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), NumberT(std::log2(v)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::max(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto e0, auto e1) {
            return CreateElement(builder, source, c0->Type(), decltype(e0)(std::max(e0, e1)));
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };
    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::min(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto e0, auto e1) {
            return CreateElement(builder, source, c0->Type(), decltype(e0)(std::min(e0, e1)));
        };
        return Dispatch_fia_fiu32_f16(create, c0, c1);
    };
    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::modf(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform_fract = [&](const sem::Constant* c) {
        auto create = [&](auto e) {
            return CreateElement(builder, source, c->Type(),
                                 decltype(e)(e.value - std::trunc(e.value)));
        };
        return Dispatch_fa_f32_f16(create, c);
    };
    auto transform_whole = [&](const sem::Constant* c) {
        auto create = [&](auto e) {
            return CreateElement(builder, source, c->Type(), decltype(e)(std::trunc(e.value)));
        };
        return Dispatch_fa_f32_f16(create, c);
    };

    utils::Vector<const sem::Constant*, 2> fields;

    if (auto fract = TransformElements(builder, args[0]->Type(), transform_fract, args[0])) {
        fields.Push(fract.Get());
    } else {
        return utils::Failure;
    }

    if (auto whole = TransformElements(builder, args[0]->Type(), transform_whole, args[0])) {
        fields.Push(whole.Get());
    } else {
        return utils::Failure;
    }

    return CreateComposite(builder, ty, std::move(fields));
}

ConstEval::Result ConstEval::pack2x16float(const sem::Type* ty,
                                           utils::VectorRef<const sem::Constant*> args,
                                           const Source& source) {
    auto convert = [&](f32 val) -> utils::Result<uint32_t> {
        auto conv = CheckedConvert<f16>(val);
        if (!conv) {
            AddError(OverflowErrorMessage(val, "f16"), source);
            return utils::Failure;
        }
        uint16_t v = conv.Get().BitsRepresentation();
        return utils::Result<uint32_t>{v};
    };

    auto* e = args[0];
    auto e0 = convert(e->Index(0)->As<f32>());
    if (!e0) {
        return utils::Failure;
    }

    auto e1 = convert(e->Index(1)->As<f32>());
    if (!e1) {
        return utils::Failure;
    }

    u32 ret = u32((e0.Get() & 0x0000'ffff) | (e1.Get() << 16));
    return CreateElement(builder, source, ty, ret);
}

ConstEval::Result ConstEval::pack2x16snorm(const sem::Type* ty,
                                           utils::VectorRef<const sem::Constant*> args,
                                           const Source& source) {
    auto calc = [&](f32 val) -> u32 {
        auto clamped = Clamp(source, val, f32(-1.0f), f32(1.0f)).Get();
        return u32(utils::Bitcast<uint16_t>(
            static_cast<int16_t>(std::floor(0.5f + (32767.0f * clamped)))));
    };

    auto* e = args[0];
    auto e0 = calc(e->Index(0)->As<f32>());
    auto e1 = calc(e->Index(1)->As<f32>());

    u32 ret = u32((e0 & 0x0000'ffff) | (e1 << 16));
    return CreateElement(builder, source, ty, ret);
}

ConstEval::Result ConstEval::pack2x16unorm(const sem::Type* ty,
                                           utils::VectorRef<const sem::Constant*> args,
                                           const Source& source) {
    auto calc = [&](f32 val) -> u32 {
        auto clamped = Clamp(source, val, f32(0.0f), f32(1.0f)).Get();
        return u32{std::floor(0.5f + (65535.0f * clamped))};
    };

    auto* e = args[0];
    auto e0 = calc(e->Index(0)->As<f32>());
    auto e1 = calc(e->Index(1)->As<f32>());

    u32 ret = u32((e0 & 0x0000'ffff) | (e1 << 16));
    return CreateElement(builder, source, ty, ret);
}

ConstEval::Result ConstEval::pack4x8snorm(const sem::Type* ty,
                                          utils::VectorRef<const sem::Constant*> args,
                                          const Source& source) {
    auto calc = [&](f32 val) -> u32 {
        auto clamped = Clamp(source, val, f32(-1.0f), f32(1.0f)).Get();
        return u32(
            utils::Bitcast<uint8_t>(static_cast<int8_t>(std::floor(0.5f + (127.0f * clamped)))));
    };

    auto* e = args[0];
    auto e0 = calc(e->Index(0)->As<f32>());
    auto e1 = calc(e->Index(1)->As<f32>());
    auto e2 = calc(e->Index(2)->As<f32>());
    auto e3 = calc(e->Index(3)->As<f32>());

    uint32_t mask = 0x0000'00ff;
    u32 ret = u32((e0 & mask) | ((e1 & mask) << 8) | ((e2 & mask) << 16) | ((e3 & mask) << 24));
    return CreateElement(builder, source, ty, ret);
}

ConstEval::Result ConstEval::pack4x8unorm(const sem::Type* ty,
                                          utils::VectorRef<const sem::Constant*> args,
                                          const Source& source) {
    auto calc = [&](f32 val) -> u32 {
        auto clamped = Clamp(source, val, f32(0.0f), f32(1.0f)).Get();
        return u32{std::floor(0.5f + (255.0f * clamped))};
    };

    auto* e = args[0];
    auto e0 = calc(e->Index(0)->As<f32>());
    auto e1 = calc(e->Index(1)->As<f32>());
    auto e2 = calc(e->Index(2)->As<f32>());
    auto e3 = calc(e->Index(3)->As<f32>());

    uint32_t mask = 0x0000'00ff;
    u32 ret = u32((e0 & mask) | ((e1 & mask) << 8) | ((e2 & mask) << 16) | ((e3 & mask) << 24));
    return CreateElement(builder, source, ty, ret);
}

ConstEval::Result ConstEval::radians(const sem::Type* ty,
                                     utils::VectorRef<const sem::Constant*> args,
                                     const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) -> ImplResult {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;

            auto pi = kPi<T>;
            auto scale = Div(source, NumberT(pi), NumberT(180));
            if (!scale) {
                AddNote("when calculating radians", source);
                return utils::Failure;
            }
            auto result = Mul(source, e, scale.Get());
            if (!result) {
                AddNote("when calculating radians", source);
                return utils::Failure;
            }
            return CreateElement(builder, source, c0->Type(), result.Get());
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::reverseBits(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto in_e) -> ImplResult {
            using NumberT = decltype(in_e);
            using T = UnwrapNumber<NumberT>;
            using UT = std::make_unsigned_t<T>;
            constexpr UT kNumBits = sizeof(UT) * 8;

            UT e = static_cast<UT>(in_e);
            UT r = UT{0};
            for (size_t s = 0; s < kNumBits; ++s) {
                // Write source 's' bit to destination 'd' bit if 1
                if (e & (UT{1} << s)) {
                    size_t d = kNumBits - s - 1;
                    r |= (UT{1} << d);
                }
            }

            return CreateElement(builder, source, c0->Type(), NumberT{r});
        };
        return Dispatch_iu32(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::round(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            using T = UnwrapNumber<NumberT>;

            auto integral = NumberT(0);
            auto fract = std::abs(std::modf(e.value, &(integral.value)));
            // When e lies halfway between integers k and k + 1, the result is k when k is even,
            // and k + 1 when k is odd.
            NumberT result = NumberT(0.0);
            if (fract == NumberT(0.5)) {
                // If the integral value is negative, then we need to subtract one in order to move
                // to the correct `k`. The half way check is `k` and `k + 1` which in the positive
                // case is `x` and `x + 1` but in the negative case is `x - 1` and `x`.
                T integral_val = integral.value;
                if (std::signbit(integral_val)) {
                    integral_val = std::abs(integral_val - 1);
                }
                if (uint64_t(integral_val) % 2 == 0) {
                    result = NumberT(std::floor(e.value));
                } else {
                    result = NumberT(std::ceil(e.value));
                }
            } else {
                result = NumberT(std::round(e.value));
            }
            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::saturate(const sem::Type* ty,
                                      utils::VectorRef<const sem::Constant*> args,
                                      const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) {
            using NumberT = decltype(e);
            return CreateElement(builder, source, c0->Type(),
                                 NumberT(std::min(std::max(e, NumberT(0.0)), NumberT(1.0))));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::select_bool(const sem::Type* ty,
                                         utils::VectorRef<const sem::Constant*> args,
                                         const Source& source) {
    auto cond = args[2]->As<bool>();
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto f, auto t) -> ImplResult {
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), cond ? t : f);
        };
        return Dispatch_fia_fiu32_f16_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::select_boolvec(const sem::Type* ty,
                                            utils::VectorRef<const sem::Constant*> args,
                                            const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1, size_t index) {
        auto create = [&](auto f, auto t) -> ImplResult {
            // Get corresponding bool value at the current vector value index
            auto cond = args[2]->Index(index)->As<bool>();
            return CreateElement(builder, source, sem::Type::DeepestElementOf(ty), cond ? t : f);
        };
        return Dispatch_fia_fiu32_f16_bool(create, c0, c1);
    };

    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::sign(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto e) -> ImplResult {
            using NumberT = decltype(e);
            NumberT result;
            NumberT zero{0.0};
            if (e.value < zero) {
                result = NumberT{-1.0};
            } else if (e.value > zero) {
                result = NumberT{1.0};
            } else {
                result = zero;
            }
            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::sin(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::sin(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::sinh(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::sinh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::smoothstep(const sem::Type* ty,
                                        utils::VectorRef<const sem::Constant*> args,
                                        const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1,
                         const sem::Constant* c2) {
        auto create = [&](auto low, auto high, auto x) -> ImplResult {
            using NumberT = decltype(low);

            auto err = [&] {
                AddNote("when calculating smoothstep", source);
                return utils::Failure;
            };

            // t = clamp((x - low) / (high - low), 0.0, 1.0)
            auto x_minus_low = Sub(source, x, low);
            auto high_minus_low = Sub(source, high, low);
            if (!x_minus_low || !high_minus_low) {
                return err();
            }

            auto div = Div(source, x_minus_low.Get(), high_minus_low.Get());
            if (!div) {
                return err();
            }

            auto clamp = Clamp(source, div.Get(), NumberT(0), NumberT(1));
            auto t = clamp.Get();

            // result = t * t * (3.0 - 2.0 * t)
            auto t_times_t = Mul(source, t, t);
            auto t_times_2 = Mul(source, NumberT(2), t);
            if (!t_times_t || !t_times_2) {
                return err();
            }

            auto three_minus_t_times_2 = Sub(source, NumberT(3), t_times_2.Get());
            if (!three_minus_t_times_2) {
                return err();
            }

            auto result = Mul(source, t_times_t.Get(), three_minus_t_times_2.Get());
            if (!result) {
                return err();
            }
            return CreateElement(builder, source, c0->Type(), result.Get());
        };
        return Dispatch_fa_f32_f16(create, c0, c1, c2);
    };
    return TransformElements(builder, ty, transform, args[0], args[1], args[2]);
}

ConstEval::Result ConstEval::step(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0, const sem::Constant* c1) {
        auto create = [&](auto edge, auto x) -> ImplResult {
            using NumberT = decltype(edge);
            NumberT result = x.value < edge.value ? NumberT(0.0) : NumberT(1.0);
            return CreateElement(builder, source, c0->Type(), result);
        };
        return Dispatch_fa_f32_f16(create, c0, c1);
    };
    return TransformElements(builder, ty, transform, args[0], args[1]);
}

ConstEval::Result ConstEval::sqrt(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        return Dispatch_fa_f32_f16(SqrtFunc(source, c0->Type()), c0);
    };

    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::tan(const sem::Type* ty,
                                 utils::VectorRef<const sem::Constant*> args,
                                 const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::tan(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::tanh(const sem::Type* ty,
                                  utils::VectorRef<const sem::Constant*> args,
                                  const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) -> ImplResult {
            using NumberT = decltype(i);
            return CreateElement(builder, source, c0->Type(), NumberT(std::tanh(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::transpose(const sem::Type* ty,
                                       utils::VectorRef<const sem::Constant*> args,
                                       const Source&) {
    auto* m = args[0];
    auto* mat_ty = m->Type()->As<sem::Matrix>();
    auto me = [&](size_t r, size_t c) { return m->Index(c)->Index(r); };
    auto* result_mat_ty = ty->As<sem::Matrix>();

    // Produce column vectors from each row
    utils::Vector<const sem::Constant*, 4> result_mat;
    for (size_t r = 0; r < mat_ty->rows(); ++r) {
        utils::Vector<const sem::Constant*, 4> new_col_vec;
        for (size_t c = 0; c < mat_ty->columns(); ++c) {
            new_col_vec.Push(me(r, c));
        }
        result_mat.Push(CreateComposite(builder, result_mat_ty->ColumnType(), new_col_vec));
    }
    return CreateComposite(builder, ty, result_mat);
}

ConstEval::Result ConstEval::trunc(const sem::Type* ty,
                                   utils::VectorRef<const sem::Constant*> args,
                                   const Source& source) {
    auto transform = [&](const sem::Constant* c0) {
        auto create = [&](auto i) {
            return CreateElement(builder, source, c0->Type(), decltype(i)(std::trunc(i.value)));
        };
        return Dispatch_fa_f32_f16(create, c0);
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::unpack2x16float(const sem::Type* ty,
                                             utils::VectorRef<const sem::Constant*> args,
                                             const Source& source) {
    auto* inner_ty = sem::Type::DeepestElementOf(ty);
    auto e = args[0]->As<u32>().value;

    utils::Vector<const sem::Constant*, 2> els;
    els.Reserve(2);
    for (size_t i = 0; i < 2; ++i) {
        auto in = f16::FromBits(uint16_t((e >> (16 * i)) & 0x0000'ffff));
        auto val = CheckedConvert<f32>(in);
        if (!val) {
            AddError(OverflowErrorMessage(in, "f32"), source);
            return utils::Failure;
        }
        auto el = CreateElement(builder, source, inner_ty, val.Get());
        if (!el) {
            return el;
        }
        els.Push(el.Get());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::unpack2x16snorm(const sem::Type* ty,
                                             utils::VectorRef<const sem::Constant*> args,
                                             const Source& source) {
    auto* inner_ty = sem::Type::DeepestElementOf(ty);
    auto e = args[0]->As<u32>().value;

    utils::Vector<const sem::Constant*, 2> els;
    els.Reserve(2);
    for (size_t i = 0; i < 2; ++i) {
        auto val = f32(
            std::max(static_cast<float>(int16_t((e >> (16 * i)) & 0x0000'ffff)) / 32767.f, -1.f));
        auto el = CreateElement(builder, source, inner_ty, val);
        if (!el) {
            return el;
        }
        els.Push(el.Get());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::unpack2x16unorm(const sem::Type* ty,
                                             utils::VectorRef<const sem::Constant*> args,
                                             const Source& source) {
    auto* inner_ty = sem::Type::DeepestElementOf(ty);
    auto e = args[0]->As<u32>().value;

    utils::Vector<const sem::Constant*, 2> els;
    els.Reserve(2);
    for (size_t i = 0; i < 2; ++i) {
        auto val = f32(static_cast<float>(uint16_t((e >> (16 * i)) & 0x0000'ffff)) / 65535.f);
        auto el = CreateElement(builder, source, inner_ty, val);
        if (!el) {
            return el;
        }
        els.Push(el.Get());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::unpack4x8snorm(const sem::Type* ty,
                                            utils::VectorRef<const sem::Constant*> args,
                                            const Source& source) {
    auto* inner_ty = sem::Type::DeepestElementOf(ty);
    auto e = args[0]->As<u32>().value;

    utils::Vector<const sem::Constant*, 4> els;
    els.Reserve(4);
    for (size_t i = 0; i < 4; ++i) {
        auto val =
            f32(std::max(static_cast<float>(int8_t((e >> (8 * i)) & 0x0000'00ff)) / 127.f, -1.f));
        auto el = CreateElement(builder, source, inner_ty, val);
        if (!el) {
            return el;
        }
        els.Push(el.Get());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::unpack4x8unorm(const sem::Type* ty,
                                            utils::VectorRef<const sem::Constant*> args,
                                            const Source& source) {
    auto* inner_ty = sem::Type::DeepestElementOf(ty);
    auto e = args[0]->As<u32>().value;

    utils::Vector<const sem::Constant*, 4> els;
    els.Reserve(4);
    for (size_t i = 0; i < 4; ++i) {
        auto val = f32(static_cast<float>(uint8_t((e >> (8 * i)) & 0x0000'00ff)) / 255.f);
        auto el = CreateElement(builder, source, inner_ty, val);
        if (!el) {
            return el;
        }
        els.Push(el.Get());
    }
    return CreateComposite(builder, ty, std::move(els));
}

ConstEval::Result ConstEval::quantizeToF16(const sem::Type* ty,
                                           utils::VectorRef<const sem::Constant*> args,
                                           const Source& source) {
    auto transform = [&](const sem::Constant* c) -> ImplResult {
        auto value = c->As<f32>();
        auto conv = CheckedConvert<f32>(f16(value));
        if (!conv) {
            AddError(OverflowErrorMessage(value, "f16"), source);
            return utils::Failure;
        }
        return CreateElement(builder, source, c->Type(), conv.Get());
    };
    return TransformElements(builder, ty, transform, args[0]);
}

ConstEval::Result ConstEval::Convert(const sem::Type* target_ty,
                                     const sem::Constant* value,
                                     const Source& source) {
    if (value->Type() == target_ty) {
        return value;
    }
    return static_cast<const ImplConstant*>(value)->Convert(builder, target_ty, source);
}

void ConstEval::AddError(const std::string& msg, const Source& source) const {
    builder.Diagnostics().add_error(diag::System::Resolver, msg, source);
}

void ConstEval::AddWarning(const std::string& msg, const Source& source) const {
    builder.Diagnostics().add_warning(diag::System::Resolver, msg, source);
}

void ConstEval::AddNote(const std::string& msg, const Source& source) const {
    builder.Diagnostics().add_note(diag::System::Resolver, msg, source);
}

}  // namespace tint::resolver