// Copyright 2019 Google LLC
// SPDX-License-Identifier: Apache-2.0
//
// 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.

// 128-bit WASM vectors and operations.
// External include guard in highway.h - see comment there.

#include <stddef.h>
#include <stdint.h>
#include <wasm_simd128.h>

#include "hwy/base.h"
#include "hwy/ops/shared-inl.h"

#ifdef HWY_WASM_OLD_NAMES
#define wasm_i8x16_shuffle wasm_v8x16_shuffle
#define wasm_i16x8_shuffle wasm_v16x8_shuffle
#define wasm_i32x4_shuffle wasm_v32x4_shuffle
#define wasm_i64x2_shuffle wasm_v64x2_shuffle
#define wasm_u16x8_extend_low_u8x16 wasm_i16x8_widen_low_u8x16
#define wasm_u32x4_extend_low_u16x8 wasm_i32x4_widen_low_u16x8
#define wasm_i32x4_extend_low_i16x8 wasm_i32x4_widen_low_i16x8
#define wasm_i16x8_extend_low_i8x16 wasm_i16x8_widen_low_i8x16
#define wasm_u32x4_extend_high_u16x8 wasm_i32x4_widen_high_u16x8
#define wasm_i32x4_extend_high_i16x8 wasm_i32x4_widen_high_i16x8
#define wasm_i32x4_trunc_sat_f32x4 wasm_i32x4_trunc_saturate_f32x4
#define wasm_u8x16_add_sat wasm_u8x16_add_saturate
#define wasm_u8x16_sub_sat wasm_u8x16_sub_saturate
#define wasm_u16x8_add_sat wasm_u16x8_add_saturate
#define wasm_u16x8_sub_sat wasm_u16x8_sub_saturate
#define wasm_i8x16_add_sat wasm_i8x16_add_saturate
#define wasm_i8x16_sub_sat wasm_i8x16_sub_saturate
#define wasm_i16x8_add_sat wasm_i16x8_add_saturate
#define wasm_i16x8_sub_sat wasm_i16x8_sub_saturate
#endif

HWY_BEFORE_NAMESPACE();
namespace hwy {
namespace HWY_NAMESPACE {

namespace detail {

template <typename T>
struct Raw128 {
  using type = __v128_u;
};
template <>
struct Raw128<float> {
  using type = __f32x4;
};

} // namespace detail

template <typename T, size_t N = 16 / sizeof(T)>
class Vec128 {
  using Raw = typename detail::Raw128<T>::type;

 public:
  // Compound assignment. Only usable if there is a corresponding non-member
  // binary operator overload. For example, only f32 and f64 support division.
  HWY_INLINE Vec128& operator*=(const Vec128 other) {
    return *this = (*this * other);
  }
  HWY_INLINE Vec128& operator/=(const Vec128 other) {
    return *this = (*this / other);
  }
  HWY_INLINE Vec128& operator+=(const Vec128 other) {
    return *this = (*this + other);
  }
  HWY_INLINE Vec128& operator-=(const Vec128 other) {
    return *this = (*this - other);
  }
  HWY_INLINE Vec128& operator&=(const Vec128 other) {
    return *this = (*this & other);
  }
  HWY_INLINE Vec128& operator|=(const Vec128 other) {
    return *this = (*this | other);
  }
  HWY_INLINE Vec128& operator^=(const Vec128 other) {
    return *this = (*this ^ other);
  }

  Raw raw;
};

template <typename T>
using Vec64 = Vec128<T, 8 / sizeof(T)>;

template <typename T>
using Vec32 = Vec128<T, 4 / sizeof(T)>;

// FF..FF or 0.
template <typename T, size_t N = 16 / sizeof(T)>
struct Mask128 {
  typename detail::Raw128<T>::type raw;
};

namespace detail {

// Deduce Simd<T, N, 0> from Vec128<T, N>
struct DeduceD {
  template <typename T, size_t N>
  Simd<T, N, 0> operator()(Vec128<T, N>) const {
    return Simd<T, N, 0>();
  }
};

}  // namespace detail

template <class V>
using DFromV = decltype(detail::DeduceD()(V()));

template <class V>
using TFromV = TFromD<DFromV<V>>;

// ------------------------------ BitCast

namespace detail {

HWY_INLINE __v128_u BitCastToInteger(__v128_u v) { return v; }
HWY_INLINE __v128_u BitCastToInteger(__f32x4 v) {
  return static_cast<__v128_u>(v);
}
HWY_INLINE __v128_u BitCastToInteger(__f64x2 v) {
  return static_cast<__v128_u>(v);
}

template <typename T, size_t N>
HWY_INLINE Vec128<uint8_t, N * sizeof(T)> BitCastToByte(Vec128<T, N> v) {
  return Vec128<uint8_t, N * sizeof(T)>{BitCastToInteger(v.raw)};
}

// Cannot rely on function overloading because return types differ.
template <typename T>
struct BitCastFromInteger128 {
  HWY_INLINE __v128_u operator()(__v128_u v) { return v; }
};
template <>
struct BitCastFromInteger128<float> {
  HWY_INLINE __f32x4 operator()(__v128_u v) { return static_cast<__f32x4>(v); }
};

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> BitCastFromByte(Simd<T, N, 0> /* tag */,
                                        Vec128<uint8_t, N * sizeof(T)> v) {
  return Vec128<T, N>{BitCastFromInteger128<T>()(v.raw)};
}

}  // namespace detail

template <typename T, size_t N, typename FromT>
HWY_API Vec128<T, N> BitCast(Simd<T, N, 0> d,
                             Vec128<FromT, N * sizeof(T) / sizeof(FromT)> v) {
  return detail::BitCastFromByte(d, detail::BitCastToByte(v));
}

// ------------------------------ Zero

// Returns an all-zero vector/part.
template <typename T, size_t N, HWY_IF_LE128(T, N)>
HWY_API Vec128<T, N> Zero(Simd<T, N, 0> /* tag */) {
  return Vec128<T, N>{wasm_i32x4_splat(0)};
}
template <size_t N, HWY_IF_LE128(float, N)>
HWY_API Vec128<float, N> Zero(Simd<float, N, 0> /* tag */) {
  return Vec128<float, N>{wasm_f32x4_splat(0.0f)};
}

template <class D>
using VFromD = decltype(Zero(D()));

// ------------------------------ Set

// Returns a vector/part with all lanes set to "t".
template <size_t N, HWY_IF_LE128(uint8_t, N)>
HWY_API Vec128<uint8_t, N> Set(Simd<uint8_t, N, 0> /* tag */, const uint8_t t) {
  return Vec128<uint8_t, N>{wasm_i8x16_splat(static_cast<int8_t>(t))};
}
template <size_t N, HWY_IF_LE128(uint16_t, N)>
HWY_API Vec128<uint16_t, N> Set(Simd<uint16_t, N, 0> /* tag */,
                                const uint16_t t) {
  return Vec128<uint16_t, N>{wasm_i16x8_splat(static_cast<int16_t>(t))};
}
template <size_t N, HWY_IF_LE128(uint32_t, N)>
HWY_API Vec128<uint32_t, N> Set(Simd<uint32_t, N, 0> /* tag */,
                                const uint32_t t) {
  return Vec128<uint32_t, N>{wasm_i32x4_splat(static_cast<int32_t>(t))};
}
template <size_t N, HWY_IF_LE128(uint64_t, N)>
HWY_API Vec128<uint64_t, N> Set(Simd<uint64_t, N, 0> /* tag */,
                                const uint64_t t) {
  return Vec128<uint64_t, N>{wasm_i64x2_splat(static_cast<int64_t>(t))};
}

template <size_t N, HWY_IF_LE128(int8_t, N)>
HWY_API Vec128<int8_t, N> Set(Simd<int8_t, N, 0> /* tag */, const int8_t t) {
  return Vec128<int8_t, N>{wasm_i8x16_splat(t)};
}
template <size_t N, HWY_IF_LE128(int16_t, N)>
HWY_API Vec128<int16_t, N> Set(Simd<int16_t, N, 0> /* tag */, const int16_t t) {
  return Vec128<int16_t, N>{wasm_i16x8_splat(t)};
}
template <size_t N, HWY_IF_LE128(int32_t, N)>
HWY_API Vec128<int32_t, N> Set(Simd<int32_t, N, 0> /* tag */, const int32_t t) {
  return Vec128<int32_t, N>{wasm_i32x4_splat(t)};
}
template <size_t N, HWY_IF_LE128(int64_t, N)>
HWY_API Vec128<int64_t, N> Set(Simd<int64_t, N, 0> /* tag */, const int64_t t) {
  return Vec128<int64_t, N>{wasm_i64x2_splat(t)};
}

template <size_t N, HWY_IF_LE128(float, N)>
HWY_API Vec128<float, N> Set(Simd<float, N, 0> /* tag */, const float t) {
  return Vec128<float, N>{wasm_f32x4_splat(t)};
}

HWY_DIAGNOSTICS(push)
HWY_DIAGNOSTICS_OFF(disable : 4700, ignored "-Wuninitialized")

// Returns a vector with uninitialized elements.
template <typename T, size_t N, HWY_IF_LE128(T, N)>
HWY_API Vec128<T, N> Undefined(Simd<T, N, 0> d) {
  return Zero(d);
}

HWY_DIAGNOSTICS(pop)

// Returns a vector with lane i=[0, N) set to "first" + i.
template <typename T, size_t N, typename T2>
Vec128<T, N> Iota(const Simd<T, N, 0> d, const T2 first) {
  HWY_ALIGN T lanes[16 / sizeof(T)];
  for (size_t i = 0; i < 16 / sizeof(T); ++i) {
    lanes[i] = static_cast<T>(first + static_cast<T2>(i));
  }
  return Load(d, lanes);
}

// ================================================== ARITHMETIC

// ------------------------------ Addition

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> operator+(const Vec128<uint8_t, N> a,
                                     const Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_i8x16_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> operator+(const Vec128<uint16_t, N> a,
                                      const Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_i16x8_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> operator+(const Vec128<uint32_t, N> a,
                                      const Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_i32x4_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> operator+(const Vec128<uint64_t, N> a,
                                      const Vec128<uint64_t, N> b) {
  return Vec128<uint64_t, N>{wasm_i64x2_add(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> operator+(const Vec128<int8_t, N> a,
                                    const Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> operator+(const Vec128<int16_t, N> a,
                                     const Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> operator+(const Vec128<int32_t, N> a,
                                     const Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_add(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> operator+(const Vec128<int64_t, N> a,
                                     const Vec128<int64_t, N> b) {
  return Vec128<int64_t, N>{wasm_i64x2_add(a.raw, b.raw)};
}

// Float
template <size_t N>
HWY_API Vec128<float, N> operator+(const Vec128<float, N> a,
                                   const Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_add(a.raw, b.raw)};
}

// ------------------------------ Subtraction

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> operator-(const Vec128<uint8_t, N> a,
                                     const Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_i8x16_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> operator-(Vec128<uint16_t, N> a,
                                      Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_i16x8_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> operator-(const Vec128<uint32_t, N> a,
                                      const Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_i32x4_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> operator-(const Vec128<uint64_t, N> a,
                                      const Vec128<uint64_t, N> b) {
  return Vec128<uint64_t, N>{wasm_i64x2_sub(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> operator-(const Vec128<int8_t, N> a,
                                    const Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> operator-(const Vec128<int16_t, N> a,
                                     const Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> operator-(const Vec128<int32_t, N> a,
                                     const Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_sub(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> operator-(const Vec128<int64_t, N> a,
                                     const Vec128<int64_t, N> b) {
  return Vec128<int64_t, N>{wasm_i64x2_sub(a.raw, b.raw)};
}

// Float
template <size_t N>
HWY_API Vec128<float, N> operator-(const Vec128<float, N> a,
                                   const Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_sub(a.raw, b.raw)};
}

// ------------------------------ SaturatedAdd

// Returns a + b clamped to the destination range.

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> SaturatedAdd(const Vec128<uint8_t, N> a,
                                        const Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_u8x16_add_sat(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> SaturatedAdd(const Vec128<uint16_t, N> a,
                                         const Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_u16x8_add_sat(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> SaturatedAdd(const Vec128<int8_t, N> a,
                                       const Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_add_sat(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> SaturatedAdd(const Vec128<int16_t, N> a,
                                        const Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_add_sat(a.raw, b.raw)};
}

// ------------------------------ SaturatedSub

// Returns a - b clamped to the destination range.

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> SaturatedSub(const Vec128<uint8_t, N> a,
                                        const Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_u8x16_sub_sat(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> SaturatedSub(const Vec128<uint16_t, N> a,
                                         const Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_u16x8_sub_sat(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> SaturatedSub(const Vec128<int8_t, N> a,
                                       const Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_sub_sat(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> SaturatedSub(const Vec128<int16_t, N> a,
                                        const Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_sub_sat(a.raw, b.raw)};
}

// ------------------------------ Average

// Returns (a + b + 1) / 2

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> AverageRound(const Vec128<uint8_t, N> a,
                                        const Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_u8x16_avgr(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> AverageRound(const Vec128<uint16_t, N> a,
                                         const Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_u16x8_avgr(a.raw, b.raw)};
}

// ------------------------------ Absolute value

// Returns absolute value, except that LimitsMin() maps to LimitsMax() + 1.
template <size_t N>
HWY_API Vec128<int8_t, N> Abs(const Vec128<int8_t, N> v) {
  return Vec128<int8_t, N>{wasm_i8x16_abs(v.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> Abs(const Vec128<int16_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_abs(v.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> Abs(const Vec128<int32_t, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_abs(v.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> Abs(const Vec128<int64_t, N> v) {
  return Vec128<int64_t, N>{wasm_i64x2_abs(v.raw)};
}

template <size_t N>
HWY_API Vec128<float, N> Abs(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_abs(v.raw)};
}

// ------------------------------ Shift lanes by constant #bits

// Unsigned
template <int kBits, size_t N>
HWY_API Vec128<uint16_t, N> ShiftLeft(const Vec128<uint16_t, N> v) {
  return Vec128<uint16_t, N>{wasm_i16x8_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<uint16_t, N> ShiftRight(const Vec128<uint16_t, N> v) {
  return Vec128<uint16_t, N>{wasm_u16x8_shr(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<uint32_t, N> ShiftLeft(const Vec128<uint32_t, N> v) {
  return Vec128<uint32_t, N>{wasm_i32x4_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<uint64_t, N> ShiftLeft(const Vec128<uint64_t, N> v) {
  return Vec128<uint64_t, N>{wasm_i64x2_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<uint32_t, N> ShiftRight(const Vec128<uint32_t, N> v) {
  return Vec128<uint32_t, N>{wasm_u32x4_shr(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<uint64_t, N> ShiftRight(const Vec128<uint64_t, N> v) {
  return Vec128<uint64_t, N>{wasm_u64x2_shr(v.raw, kBits)};
}

// Signed
template <int kBits, size_t N>
HWY_API Vec128<int16_t, N> ShiftLeft(const Vec128<int16_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<int16_t, N> ShiftRight(const Vec128<int16_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_shr(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<int32_t, N> ShiftLeft(const Vec128<int32_t, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<int64_t, N> ShiftLeft(const Vec128<int64_t, N> v) {
  return Vec128<int64_t, N>{wasm_i64x2_shl(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<int32_t, N> ShiftRight(const Vec128<int32_t, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_shr(v.raw, kBits)};
}
template <int kBits, size_t N>
HWY_API Vec128<int64_t, N> ShiftRight(const Vec128<int64_t, N> v) {
  return Vec128<int64_t, N>{wasm_i64x2_shr(v.raw, kBits)};
}

// 8-bit
template <int kBits, typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> ShiftLeft(const Vec128<T, N> v) {
  const DFromV<decltype(v)> d8;
  // Use raw instead of BitCast to support N=1.
  const Vec128<T, N> shifted{ShiftLeft<kBits>(Vec128<MakeWide<T>>{v.raw}).raw};
  return kBits == 1
             ? (v + v)
             : (shifted & Set(d8, static_cast<T>((0xFF << kBits) & 0xFF)));
}

template <int kBits, size_t N>
HWY_API Vec128<uint8_t, N> ShiftRight(const Vec128<uint8_t, N> v) {
  const DFromV<decltype(v)> d8;
  // Use raw instead of BitCast to support N=1.
  const Vec128<uint8_t, N> shifted{
      ShiftRight<kBits>(Vec128<uint16_t>{v.raw}).raw};
  return shifted & Set(d8, 0xFF >> kBits);
}

template <int kBits, size_t N>
HWY_API Vec128<int8_t, N> ShiftRight(const Vec128<int8_t, N> v) {
  const DFromV<decltype(v)> di;
  const RebindToUnsigned<decltype(di)> du;
  const auto shifted = BitCast(di, ShiftRight<kBits>(BitCast(du, v)));
  const auto shifted_sign = BitCast(di, Set(du, 0x80 >> kBits));
  return (shifted ^ shifted_sign) - shifted_sign;
}

// ------------------------------ RotateRight (ShiftRight, Or)
template <int kBits, typename T, size_t N>
HWY_API Vec128<T, N> RotateRight(const Vec128<T, N> v) {
  constexpr size_t kSizeInBits = sizeof(T) * 8;
  static_assert(0 <= kBits && kBits < kSizeInBits, "Invalid shift count");
  if (kBits == 0) return v;
  return Or(ShiftRight<kBits>(v), ShiftLeft<kSizeInBits - kBits>(v));
}

// ------------------------------ Shift lanes by same variable #bits

// After https://reviews.llvm.org/D108415 shift argument became unsigned.
HWY_DIAGNOSTICS(push)
HWY_DIAGNOSTICS_OFF(disable : 4245 4365, ignored "-Wsign-conversion")

// Unsigned
template <size_t N>
HWY_API Vec128<uint16_t, N> ShiftLeftSame(const Vec128<uint16_t, N> v,
                                          const int bits) {
  return Vec128<uint16_t, N>{wasm_i16x8_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> ShiftRightSame(const Vec128<uint16_t, N> v,
                                           const int bits) {
  return Vec128<uint16_t, N>{wasm_u16x8_shr(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> ShiftLeftSame(const Vec128<uint32_t, N> v,
                                          const int bits) {
  return Vec128<uint32_t, N>{wasm_i32x4_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> ShiftRightSame(const Vec128<uint32_t, N> v,
                                           const int bits) {
  return Vec128<uint32_t, N>{wasm_u32x4_shr(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> ShiftLeftSame(const Vec128<uint64_t, N> v,
                                          const int bits) {
  return Vec128<uint64_t, N>{wasm_i64x2_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> ShiftRightSame(const Vec128<uint64_t, N> v,
                                           const int bits) {
  return Vec128<uint64_t, N>{wasm_u64x2_shr(v.raw, bits)};
}

// Signed
template <size_t N>
HWY_API Vec128<int16_t, N> ShiftLeftSame(const Vec128<int16_t, N> v,
                                         const int bits) {
  return Vec128<int16_t, N>{wasm_i16x8_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> ShiftRightSame(const Vec128<int16_t, N> v,
                                          const int bits) {
  return Vec128<int16_t, N>{wasm_i16x8_shr(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> ShiftLeftSame(const Vec128<int32_t, N> v,
                                         const int bits) {
  return Vec128<int32_t, N>{wasm_i32x4_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> ShiftRightSame(const Vec128<int32_t, N> v,
                                          const int bits) {
  return Vec128<int32_t, N>{wasm_i32x4_shr(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> ShiftLeftSame(const Vec128<int64_t, N> v,
                                         const int bits) {
  return Vec128<int64_t, N>{wasm_i64x2_shl(v.raw, bits)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> ShiftRightSame(const Vec128<int64_t, N> v,
                                          const int bits) {
  return Vec128<int64_t, N>{wasm_i64x2_shr(v.raw, bits)};
}

// 8-bit
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> ShiftLeftSame(const Vec128<T, N> v, const int bits) {
  const DFromV<decltype(v)> d8;
  // Use raw instead of BitCast to support N=1.
  const Vec128<T, N> shifted{
      ShiftLeftSame(Vec128<MakeWide<T>>{v.raw}, bits).raw};
  return shifted & Set(d8, static_cast<T>((0xFF << bits) & 0xFF));
}

template <size_t N>
HWY_API Vec128<uint8_t, N> ShiftRightSame(Vec128<uint8_t, N> v,
                                          const int bits) {
  const DFromV<decltype(v)> d8;
  // Use raw instead of BitCast to support N=1.
  const Vec128<uint8_t, N> shifted{
      ShiftRightSame(Vec128<uint16_t>{v.raw}, bits).raw};
  return shifted & Set(d8, 0xFF >> bits);
}

template <size_t N>
HWY_API Vec128<int8_t, N> ShiftRightSame(Vec128<int8_t, N> v, const int bits) {
  const DFromV<decltype(v)> di;
  const RebindToUnsigned<decltype(di)> du;
  const auto shifted = BitCast(di, ShiftRightSame(BitCast(du, v), bits));
  const auto shifted_sign = BitCast(di, Set(du, 0x80 >> bits));
  return (shifted ^ shifted_sign) - shifted_sign;
}

// ignore Wsign-conversion
HWY_DIAGNOSTICS(pop)

// ------------------------------ Minimum

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> Min(Vec128<uint8_t, N> a, Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_u8x16_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> Min(Vec128<uint16_t, N> a, Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_u16x8_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> Min(Vec128<uint32_t, N> a, Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_u32x4_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> Min(Vec128<uint64_t, N> a, Vec128<uint64_t, N> b) {
  // Avoid wasm_u64x2_extract_lane - not all implementations have it yet.
  const uint64_t a0 = static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 0));
  const uint64_t b0 = static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 0));
  const uint64_t a1 = static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 1));
  const uint64_t b1 = static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 1));
  alignas(16) uint64_t min[2] = {HWY_MIN(a0, b0), HWY_MIN(a1, b1)};
  return Vec128<uint64_t, N>{wasm_v128_load(min)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> Min(Vec128<int8_t, N> a, Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> Min(Vec128<int16_t, N> a, Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> Min(Vec128<int32_t, N> a, Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_min(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> Min(Vec128<int64_t, N> a, Vec128<int64_t, N> b) {
  alignas(16) int64_t min[4];
  min[0] = HWY_MIN(wasm_i64x2_extract_lane(a.raw, 0),
                   wasm_i64x2_extract_lane(b.raw, 0));
  min[1] = HWY_MIN(wasm_i64x2_extract_lane(a.raw, 1),
                   wasm_i64x2_extract_lane(b.raw, 1));
  return Vec128<int64_t, N>{wasm_v128_load(min)};
}

// Float
template <size_t N>
HWY_API Vec128<float, N> Min(Vec128<float, N> a, Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_min(a.raw, b.raw)};
}

// ------------------------------ Maximum

// Unsigned
template <size_t N>
HWY_API Vec128<uint8_t, N> Max(Vec128<uint8_t, N> a, Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_u8x16_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> Max(Vec128<uint16_t, N> a, Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_u16x8_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> Max(Vec128<uint32_t, N> a, Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_u32x4_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> Max(Vec128<uint64_t, N> a, Vec128<uint64_t, N> b) {
  // Avoid wasm_u64x2_extract_lane - not all implementations have it yet.
  const uint64_t a0 = static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 0));
  const uint64_t b0 = static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 0));
  const uint64_t a1 = static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 1));
  const uint64_t b1 = static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 1));
  alignas(16) uint64_t max[2] = {HWY_MAX(a0, b0), HWY_MAX(a1, b1)};
  return Vec128<uint64_t, N>{wasm_v128_load(max)};
}

// Signed
template <size_t N>
HWY_API Vec128<int8_t, N> Max(Vec128<int8_t, N> a, Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> Max(Vec128<int16_t, N> a, Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> Max(Vec128<int32_t, N> a, Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_max(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> Max(Vec128<int64_t, N> a, Vec128<int64_t, N> b) {
  alignas(16) int64_t max[2];
  max[0] = HWY_MAX(wasm_i64x2_extract_lane(a.raw, 0),
                   wasm_i64x2_extract_lane(b.raw, 0));
  max[1] = HWY_MAX(wasm_i64x2_extract_lane(a.raw, 1),
                   wasm_i64x2_extract_lane(b.raw, 1));
  return Vec128<int64_t, N>{wasm_v128_load(max)};
}

// Float
template <size_t N>
HWY_API Vec128<float, N> Max(Vec128<float, N> a, Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_max(a.raw, b.raw)};
}

// ------------------------------ Integer multiplication

// Unsigned
template <size_t N>
HWY_API Vec128<uint16_t, N> operator*(const Vec128<uint16_t, N> a,
                                      const Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{wasm_i16x8_mul(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> operator*(const Vec128<uint32_t, N> a,
                                      const Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_i32x4_mul(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Vec128<int16_t, N> operator*(const Vec128<int16_t, N> a,
                                     const Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{wasm_i16x8_mul(a.raw, b.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> operator*(const Vec128<int32_t, N> a,
                                     const Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_mul(a.raw, b.raw)};
}

// Returns the upper 16 bits of a * b in each lane.
template <size_t N>
HWY_API Vec128<uint16_t, N> MulHigh(const Vec128<uint16_t, N> a,
                                    const Vec128<uint16_t, N> b) {
  // TODO(eustas): replace, when implemented in WASM.
  const auto al = wasm_u32x4_extend_low_u16x8(a.raw);
  const auto ah = wasm_u32x4_extend_high_u16x8(a.raw);
  const auto bl = wasm_u32x4_extend_low_u16x8(b.raw);
  const auto bh = wasm_u32x4_extend_high_u16x8(b.raw);
  const auto l = wasm_i32x4_mul(al, bl);
  const auto h = wasm_i32x4_mul(ah, bh);
  // TODO(eustas): shift-right + narrow?
  return Vec128<uint16_t, N>{
      wasm_i16x8_shuffle(l, h, 1, 3, 5, 7, 9, 11, 13, 15)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> MulHigh(const Vec128<int16_t, N> a,
                                   const Vec128<int16_t, N> b) {
  // TODO(eustas): replace, when implemented in WASM.
  const auto al = wasm_i32x4_extend_low_i16x8(a.raw);
  const auto ah = wasm_i32x4_extend_high_i16x8(a.raw);
  const auto bl = wasm_i32x4_extend_low_i16x8(b.raw);
  const auto bh = wasm_i32x4_extend_high_i16x8(b.raw);
  const auto l = wasm_i32x4_mul(al, bl);
  const auto h = wasm_i32x4_mul(ah, bh);
  // TODO(eustas): shift-right + narrow?
  return Vec128<int16_t, N>{
      wasm_i16x8_shuffle(l, h, 1, 3, 5, 7, 9, 11, 13, 15)};
}

template <size_t N>
HWY_API Vec128<int16_t, N> MulFixedPoint15(Vec128<int16_t, N> a,
                                           Vec128<int16_t, N> b) {
  const DFromV<decltype(a)> d;
  const RebindToUnsigned<decltype(d)> du;

  const Vec128<uint16_t, N> lo = BitCast(du, Mul(a, b));
  const Vec128<int16_t, N> hi = MulHigh(a, b);
  // We want (lo + 0x4000) >> 15, but that can overflow, and if it does we must
  // carry that into the result. Instead isolate the top two bits because only
  // they can influence the result.
  const Vec128<uint16_t, N> lo_top2 = ShiftRight<14>(lo);
  // Bits 11: add 2, 10: add 1, 01: add 1, 00: add 0.
  const Vec128<uint16_t, N> rounding = ShiftRight<1>(Add(lo_top2, Set(du, 1)));
  return Add(Add(hi, hi), BitCast(d, rounding));
}

// Multiplies even lanes (0, 2 ..) and returns the double-width result.
template <size_t N>
HWY_API Vec128<int64_t, (N + 1) / 2> MulEven(const Vec128<int32_t, N> a,
                                             const Vec128<int32_t, N> b) {
  // TODO(eustas): replace, when implemented in WASM.
  const auto kEvenMask = wasm_i32x4_make(-1, 0, -1, 0);
  const auto ae = wasm_v128_and(a.raw, kEvenMask);
  const auto be = wasm_v128_and(b.raw, kEvenMask);
  return Vec128<int64_t, (N + 1) / 2>{wasm_i64x2_mul(ae, be)};
}
template <size_t N>
HWY_API Vec128<uint64_t, (N + 1) / 2> MulEven(const Vec128<uint32_t, N> a,
                                              const Vec128<uint32_t, N> b) {
  // TODO(eustas): replace, when implemented in WASM.
  const auto kEvenMask = wasm_i32x4_make(-1, 0, -1, 0);
  const auto ae = wasm_v128_and(a.raw, kEvenMask);
  const auto be = wasm_v128_and(b.raw, kEvenMask);
  return Vec128<uint64_t, (N + 1) / 2>{wasm_i64x2_mul(ae, be)};
}

// ------------------------------ Negate

template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Vec128<T, N> Neg(const Vec128<T, N> v) {
  return Xor(v, SignBit(DFromV<decltype(v)>()));
}

template <size_t N>
HWY_API Vec128<int8_t, N> Neg(const Vec128<int8_t, N> v) {
  return Vec128<int8_t, N>{wasm_i8x16_neg(v.raw)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> Neg(const Vec128<int16_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_neg(v.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> Neg(const Vec128<int32_t, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_neg(v.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> Neg(const Vec128<int64_t, N> v) {
  return Vec128<int64_t, N>{wasm_i64x2_neg(v.raw)};
}

// ------------------------------ Floating-point mul / div

template <size_t N>
HWY_API Vec128<float, N> operator*(Vec128<float, N> a, Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_mul(a.raw, b.raw)};
}

template <size_t N>
HWY_API Vec128<float, N> operator/(const Vec128<float, N> a,
                                   const Vec128<float, N> b) {
  return Vec128<float, N>{wasm_f32x4_div(a.raw, b.raw)};
}

// Approximate reciprocal
template <size_t N>
HWY_API Vec128<float, N> ApproximateReciprocal(const Vec128<float, N> v) {
  const Vec128<float, N> one = Vec128<float, N>{wasm_f32x4_splat(1.0f)};
  return one / v;
}

// Absolute value of difference.
template <size_t N>
HWY_API Vec128<float, N> AbsDiff(const Vec128<float, N> a,
                                 const Vec128<float, N> b) {
  return Abs(a - b);
}

// ------------------------------ Floating-point multiply-add variants

// Returns mul * x + add
template <size_t N>
HWY_API Vec128<float, N> MulAdd(const Vec128<float, N> mul,
                                const Vec128<float, N> x,
                                const Vec128<float, N> add) {
  // TODO(eustas): replace, when implemented in WASM.
  // TODO(eustas): is it wasm_f32x4_qfma?
  return mul * x + add;
}

// Returns add - mul * x
template <size_t N>
HWY_API Vec128<float, N> NegMulAdd(const Vec128<float, N> mul,
                                   const Vec128<float, N> x,
                                   const Vec128<float, N> add) {
  // TODO(eustas): replace, when implemented in WASM.
  return add - mul * x;
}

// Returns mul * x - sub
template <size_t N>
HWY_API Vec128<float, N> MulSub(const Vec128<float, N> mul,
                                const Vec128<float, N> x,
                                const Vec128<float, N> sub) {
  // TODO(eustas): replace, when implemented in WASM.
  // TODO(eustas): is it wasm_f32x4_qfms?
  return mul * x - sub;
}

// Returns -mul * x - sub
template <size_t N>
HWY_API Vec128<float, N> NegMulSub(const Vec128<float, N> mul,
                                   const Vec128<float, N> x,
                                   const Vec128<float, N> sub) {
  // TODO(eustas): replace, when implemented in WASM.
  return Neg(mul) * x - sub;
}

// ------------------------------ Floating-point square root

// Full precision square root
template <size_t N>
HWY_API Vec128<float, N> Sqrt(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_sqrt(v.raw)};
}

// Approximate reciprocal square root
template <size_t N>
HWY_API Vec128<float, N> ApproximateReciprocalSqrt(const Vec128<float, N> v) {
  // TODO(eustas): find cheaper a way to calculate this.
  const Vec128<float, N> one = Vec128<float, N>{wasm_f32x4_splat(1.0f)};
  return one / Sqrt(v);
}

// ------------------------------ Floating-point rounding

// Toward nearest integer, ties to even
template <size_t N>
HWY_API Vec128<float, N> Round(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_nearest(v.raw)};
}

// Toward zero, aka truncate
template <size_t N>
HWY_API Vec128<float, N> Trunc(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_trunc(v.raw)};
}

// Toward +infinity, aka ceiling
template <size_t N>
HWY_API Vec128<float, N> Ceil(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_ceil(v.raw)};
}

// Toward -infinity, aka floor
template <size_t N>
HWY_API Vec128<float, N> Floor(const Vec128<float, N> v) {
  return Vec128<float, N>{wasm_f32x4_floor(v.raw)};
}

// ------------------------------ Floating-point classification
template <typename T, size_t N>
HWY_API Mask128<T, N> IsNaN(const Vec128<T, N> v) {
  return v != v;
}

template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Mask128<T, N> IsInf(const Vec128<T, N> v) {
  const Simd<T, N, 0> d;
  const RebindToSigned<decltype(d)> di;
  const VFromD<decltype(di)> vi = BitCast(di, v);
  // 'Shift left' to clear the sign bit, check for exponent=max and mantissa=0.
  return RebindMask(d, Eq(Add(vi, vi), Set(di, hwy::MaxExponentTimes2<T>())));
}

// Returns whether normal/subnormal/zero.
template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Mask128<T, N> IsFinite(const Vec128<T, N> v) {
  const Simd<T, N, 0> d;
  const RebindToUnsigned<decltype(d)> du;
  const RebindToSigned<decltype(d)> di;  // cheaper than unsigned comparison
  const VFromD<decltype(du)> vu = BitCast(du, v);
  // 'Shift left' to clear the sign bit, then right so we can compare with the
  // max exponent (cannot compare with MaxExponentTimes2 directly because it is
  // negative and non-negative floats would be greater).
  const VFromD<decltype(di)> exp =
      BitCast(di, ShiftRight<hwy::MantissaBits<T>() + 1>(Add(vu, vu)));
  return RebindMask(d, Lt(exp, Set(di, hwy::MaxExponentField<T>())));
}

// ================================================== COMPARE

// Comparisons fill a lane with 1-bits if the condition is true, else 0.

template <typename TFrom, typename TTo, size_t N>
HWY_API Mask128<TTo, N> RebindMask(Simd<TTo, N, 0> /*tag*/,
                                   Mask128<TFrom, N> m) {
  static_assert(sizeof(TFrom) == sizeof(TTo), "Must have same size");
  return Mask128<TTo, N>{m.raw};
}

template <typename T, size_t N>
HWY_API Mask128<T, N> TestBit(Vec128<T, N> v, Vec128<T, N> bit) {
  static_assert(!hwy::IsFloat<T>(), "Only integer vectors supported");
  return (v & bit) == bit;
}

// ------------------------------ Equality

// Unsigned
template <size_t N>
HWY_API Mask128<uint8_t, N> operator==(const Vec128<uint8_t, N> a,
                                       const Vec128<uint8_t, N> b) {
  return Mask128<uint8_t, N>{wasm_i8x16_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint16_t, N> operator==(const Vec128<uint16_t, N> a,
                                        const Vec128<uint16_t, N> b) {
  return Mask128<uint16_t, N>{wasm_i16x8_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint32_t, N> operator==(const Vec128<uint32_t, N> a,
                                        const Vec128<uint32_t, N> b) {
  return Mask128<uint32_t, N>{wasm_i32x4_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint64_t, N> operator==(const Vec128<uint64_t, N> a,
                                        const Vec128<uint64_t, N> b) {
  return Mask128<uint64_t, N>{wasm_i64x2_eq(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Mask128<int8_t, N> operator==(const Vec128<int8_t, N> a,
                                      const Vec128<int8_t, N> b) {
  return Mask128<int8_t, N>{wasm_i8x16_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int16_t, N> operator==(Vec128<int16_t, N> a,
                                       Vec128<int16_t, N> b) {
  return Mask128<int16_t, N>{wasm_i16x8_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int32_t, N> operator==(const Vec128<int32_t, N> a,
                                       const Vec128<int32_t, N> b) {
  return Mask128<int32_t, N>{wasm_i32x4_eq(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int64_t, N> operator==(const Vec128<int64_t, N> a,
                                       const Vec128<int64_t, N> b) {
  return Mask128<int64_t, N>{wasm_i64x2_eq(a.raw, b.raw)};
}

// Float
template <size_t N>
HWY_API Mask128<float, N> operator==(const Vec128<float, N> a,
                                     const Vec128<float, N> b) {
  return Mask128<float, N>{wasm_f32x4_eq(a.raw, b.raw)};
}

// ------------------------------ Inequality

// Unsigned
template <size_t N>
HWY_API Mask128<uint8_t, N> operator!=(const Vec128<uint8_t, N> a,
                                       const Vec128<uint8_t, N> b) {
  return Mask128<uint8_t, N>{wasm_i8x16_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint16_t, N> operator!=(const Vec128<uint16_t, N> a,
                                        const Vec128<uint16_t, N> b) {
  return Mask128<uint16_t, N>{wasm_i16x8_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint32_t, N> operator!=(const Vec128<uint32_t, N> a,
                                        const Vec128<uint32_t, N> b) {
  return Mask128<uint32_t, N>{wasm_i32x4_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint64_t, N> operator!=(const Vec128<uint64_t, N> a,
                                        const Vec128<uint64_t, N> b) {
  return Mask128<uint64_t, N>{wasm_i64x2_ne(a.raw, b.raw)};
}

// Signed
template <size_t N>
HWY_API Mask128<int8_t, N> operator!=(const Vec128<int8_t, N> a,
                                      const Vec128<int8_t, N> b) {
  return Mask128<int8_t, N>{wasm_i8x16_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int16_t, N> operator!=(const Vec128<int16_t, N> a,
                                       const Vec128<int16_t, N> b) {
  return Mask128<int16_t, N>{wasm_i16x8_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int32_t, N> operator!=(const Vec128<int32_t, N> a,
                                       const Vec128<int32_t, N> b) {
  return Mask128<int32_t, N>{wasm_i32x4_ne(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int64_t, N> operator!=(const Vec128<int64_t, N> a,
                                       const Vec128<int64_t, N> b) {
  return Mask128<int64_t, N>{wasm_i64x2_ne(a.raw, b.raw)};
}

// Float
template <size_t N>
HWY_API Mask128<float, N> operator!=(const Vec128<float, N> a,
                                     const Vec128<float, N> b) {
  return Mask128<float, N>{wasm_f32x4_ne(a.raw, b.raw)};
}

// ------------------------------ Strict inequality

template <size_t N>
HWY_API Mask128<int8_t, N> operator>(const Vec128<int8_t, N> a,
                                     const Vec128<int8_t, N> b) {
  return Mask128<int8_t, N>{wasm_i8x16_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int16_t, N> operator>(const Vec128<int16_t, N> a,
                                      const Vec128<int16_t, N> b) {
  return Mask128<int16_t, N>{wasm_i16x8_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int32_t, N> operator>(const Vec128<int32_t, N> a,
                                      const Vec128<int32_t, N> b) {
  return Mask128<int32_t, N>{wasm_i32x4_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<int64_t, N> operator>(const Vec128<int64_t, N> a,
                                      const Vec128<int64_t, N> b) {
  return Mask128<int64_t, N>{wasm_i64x2_gt(a.raw, b.raw)};
}

template <size_t N>
HWY_API Mask128<uint8_t, N> operator>(const Vec128<uint8_t, N> a,
                                      const Vec128<uint8_t, N> b) {
  return Mask128<uint8_t, N>{wasm_u8x16_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint16_t, N> operator>(const Vec128<uint16_t, N> a,
                                       const Vec128<uint16_t, N> b) {
  return Mask128<uint16_t, N>{wasm_u16x8_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint32_t, N> operator>(const Vec128<uint32_t, N> a,
                                       const Vec128<uint32_t, N> b) {
  return Mask128<uint32_t, N>{wasm_u32x4_gt(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<uint64_t, N> operator>(const Vec128<uint64_t, N> a,
                                       const Vec128<uint64_t, N> b) {
  const DFromV<decltype(a)> d;
  const Repartition<uint32_t, decltype(d)> d32;
  const auto a32 = BitCast(d32, a);
  const auto b32 = BitCast(d32, b);
  // If the upper halves are not equal, this is the answer.
  const auto m_gt = a32 > b32;

  // Otherwise, the lower half decides.
  const auto m_eq = a32 == b32;
  const auto lo_in_hi = wasm_i32x4_shuffle(m_gt.raw, m_gt.raw, 0, 0, 2, 2);
  const auto lo_gt = And(m_eq, MaskFromVec(VFromD<decltype(d32)>{lo_in_hi}));

  const auto gt = Or(lo_gt, m_gt);
  // Copy result in upper 32 bits to lower 32 bits.
  return Mask128<uint64_t, N>{wasm_i32x4_shuffle(gt.raw, gt.raw, 1, 1, 3, 3)};
}

template <size_t N>
HWY_API Mask128<float, N> operator>(const Vec128<float, N> a,
                                    const Vec128<float, N> b) {
  return Mask128<float, N>{wasm_f32x4_gt(a.raw, b.raw)};
}

template <typename T, size_t N>
HWY_API Mask128<T, N> operator<(const Vec128<T, N> a, const Vec128<T, N> b) {
  return operator>(b, a);
}

// ------------------------------ Weak inequality

// Float <= >=
template <size_t N>
HWY_API Mask128<float, N> operator<=(const Vec128<float, N> a,
                                     const Vec128<float, N> b) {
  return Mask128<float, N>{wasm_f32x4_le(a.raw, b.raw)};
}
template <size_t N>
HWY_API Mask128<float, N> operator>=(const Vec128<float, N> a,
                                     const Vec128<float, N> b) {
  return Mask128<float, N>{wasm_f32x4_ge(a.raw, b.raw)};
}

// ------------------------------ FirstN (Iota, Lt)

template <typename T, size_t N>
HWY_API Mask128<T, N> FirstN(const Simd<T, N, 0> d, size_t num) {
  const RebindToSigned<decltype(d)> di;  // Signed comparisons may be cheaper.
  return RebindMask(d, Iota(di, 0) < Set(di, static_cast<MakeSigned<T>>(num)));
}

// ================================================== LOGICAL

// ------------------------------ Not

template <typename T, size_t N>
HWY_API Vec128<T, N> Not(Vec128<T, N> v) {
  return Vec128<T, N>{wasm_v128_not(v.raw)};
}

// ------------------------------ And

template <typename T, size_t N>
HWY_API Vec128<T, N> And(Vec128<T, N> a, Vec128<T, N> b) {
  return Vec128<T, N>{wasm_v128_and(a.raw, b.raw)};
}

// ------------------------------ AndNot

// Returns ~not_mask & mask.
template <typename T, size_t N>
HWY_API Vec128<T, N> AndNot(Vec128<T, N> not_mask, Vec128<T, N> mask) {
  return Vec128<T, N>{wasm_v128_andnot(mask.raw, not_mask.raw)};
}

// ------------------------------ Or

template <typename T, size_t N>
HWY_API Vec128<T, N> Or(Vec128<T, N> a, Vec128<T, N> b) {
  return Vec128<T, N>{wasm_v128_or(a.raw, b.raw)};
}

// ------------------------------ Xor

template <typename T, size_t N>
HWY_API Vec128<T, N> Xor(Vec128<T, N> a, Vec128<T, N> b) {
  return Vec128<T, N>{wasm_v128_xor(a.raw, b.raw)};
}

// ------------------------------ Or3

template <typename T, size_t N>
HWY_API Vec128<T, N> Or3(Vec128<T, N> o1, Vec128<T, N> o2, Vec128<T, N> o3) {
  return Or(o1, Or(o2, o3));
}

// ------------------------------ OrAnd

template <typename T, size_t N>
HWY_API Vec128<T, N> OrAnd(Vec128<T, N> o, Vec128<T, N> a1, Vec128<T, N> a2) {
  return Or(o, And(a1, a2));
}

// ------------------------------ IfVecThenElse

template <typename T, size_t N>
HWY_API Vec128<T, N> IfVecThenElse(Vec128<T, N> mask, Vec128<T, N> yes,
                                   Vec128<T, N> no) {
  return IfThenElse(MaskFromVec(mask), yes, no);
}

// ------------------------------ Operator overloads (internal-only if float)

template <typename T, size_t N>
HWY_API Vec128<T, N> operator&(const Vec128<T, N> a, const Vec128<T, N> b) {
  return And(a, b);
}

template <typename T, size_t N>
HWY_API Vec128<T, N> operator|(const Vec128<T, N> a, const Vec128<T, N> b) {
  return Or(a, b);
}

template <typename T, size_t N>
HWY_API Vec128<T, N> operator^(const Vec128<T, N> a, const Vec128<T, N> b) {
  return Xor(a, b);
}

// ------------------------------ CopySign

template <typename T, size_t N>
HWY_API Vec128<T, N> CopySign(const Vec128<T, N> magn,
                              const Vec128<T, N> sign) {
  static_assert(IsFloat<T>(), "Only makes sense for floating-point");
  const auto msb = SignBit(DFromV<decltype(magn)>());
  return Or(AndNot(msb, magn), And(msb, sign));
}

template <typename T, size_t N>
HWY_API Vec128<T, N> CopySignToAbs(const Vec128<T, N> abs,
                                   const Vec128<T, N> sign) {
  static_assert(IsFloat<T>(), "Only makes sense for floating-point");
  return Or(abs, And(SignBit(DFromV<decltype(abs)>()), sign));
}

// ------------------------------ BroadcastSignBit (compare)

template <typename T, size_t N, HWY_IF_NOT_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> BroadcastSignBit(const Vec128<T, N> v) {
  return ShiftRight<sizeof(T) * 8 - 1>(v);
}
template <size_t N>
HWY_API Vec128<int8_t, N> BroadcastSignBit(const Vec128<int8_t, N> v) {
  const DFromV<decltype(v)> d;
  return VecFromMask(d, v < Zero(d));
}

// ------------------------------ Mask

// Mask and Vec are the same (true = FF..FF).
template <typename T, size_t N>
HWY_API Mask128<T, N> MaskFromVec(const Vec128<T, N> v) {
  return Mask128<T, N>{v.raw};
}

template <typename T, size_t N>
HWY_API Vec128<T, N> VecFromMask(Simd<T, N, 0> /* tag */, Mask128<T, N> v) {
  return Vec128<T, N>{v.raw};
}

// mask ? yes : no
template <typename T, size_t N>
HWY_API Vec128<T, N> IfThenElse(Mask128<T, N> mask, Vec128<T, N> yes,
                                Vec128<T, N> no) {
  return Vec128<T, N>{wasm_v128_bitselect(yes.raw, no.raw, mask.raw)};
}

// mask ? yes : 0
template <typename T, size_t N>
HWY_API Vec128<T, N> IfThenElseZero(Mask128<T, N> mask, Vec128<T, N> yes) {
  return yes & VecFromMask(DFromV<decltype(yes)>(), mask);
}

// mask ? 0 : no
template <typename T, size_t N>
HWY_API Vec128<T, N> IfThenZeroElse(Mask128<T, N> mask, Vec128<T, N> no) {
  return AndNot(VecFromMask(DFromV<decltype(no)>(), mask), no);
}

template <typename T, size_t N>
HWY_API Vec128<T, N> IfNegativeThenElse(Vec128<T, N> v, Vec128<T, N> yes,
                                        Vec128<T, N> no) {
  static_assert(IsSigned<T>(), "Only works for signed/float");
  const DFromV<decltype(v)> d;
  const RebindToSigned<decltype(d)> di;

  v = BitCast(d, BroadcastSignBit(BitCast(di, v)));
  return IfThenElse(MaskFromVec(v), yes, no);
}

template <typename T, size_t N, HWY_IF_FLOAT(T)>
HWY_API Vec128<T, N> ZeroIfNegative(Vec128<T, N> v) {
  const DFromV<decltype(v)> d;
  const auto zero = Zero(d);
  return IfThenElse(Mask128<T, N>{(v > zero).raw}, v, zero);
}

// ------------------------------ Mask logical

template <typename T, size_t N>
HWY_API Mask128<T, N> Not(const Mask128<T, N> m) {
  return MaskFromVec(Not(VecFromMask(Simd<T, N, 0>(), m)));
}

template <typename T, size_t N>
HWY_API Mask128<T, N> And(const Mask128<T, N> a, Mask128<T, N> b) {
  const Simd<T, N, 0> d;
  return MaskFromVec(And(VecFromMask(d, a), VecFromMask(d, b)));
}

template <typename T, size_t N>
HWY_API Mask128<T, N> AndNot(const Mask128<T, N> a, Mask128<T, N> b) {
  const Simd<T, N, 0> d;
  return MaskFromVec(AndNot(VecFromMask(d, a), VecFromMask(d, b)));
}

template <typename T, size_t N>
HWY_API Mask128<T, N> Or(const Mask128<T, N> a, Mask128<T, N> b) {
  const Simd<T, N, 0> d;
  return MaskFromVec(Or(VecFromMask(d, a), VecFromMask(d, b)));
}

template <typename T, size_t N>
HWY_API Mask128<T, N> Xor(const Mask128<T, N> a, Mask128<T, N> b) {
  const Simd<T, N, 0> d;
  return MaskFromVec(Xor(VecFromMask(d, a), VecFromMask(d, b)));
}

// ------------------------------ Shl (BroadcastSignBit, IfThenElse)

// The x86 multiply-by-Pow2() trick will not work because WASM saturates
// float->int correctly to 2^31-1 (not 2^31). Because WASM's shifts take a
// scalar count operand, per-lane shift instructions would require extract_lane
// for each lane, and hoping that shuffle is correctly mapped to a native
// instruction. Using non-vector shifts would incur a store-load forwarding
// stall when loading the result vector. We instead test bits of the shift
// count to "predicate" a shift of the entire vector by a constant.

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> operator<<(Vec128<T, N> v, const Vec128<T, N> bits) {
  const DFromV<decltype(v)> d;
  Mask128<T, N> mask;
  // Need a signed type for BroadcastSignBit.
  auto test = BitCast(RebindToSigned<decltype(d)>(), bits);
  // Move the highest valid bit of the shift count into the sign bit.
  test = ShiftLeft<12>(test);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<8>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<4>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<2>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  return IfThenElse(mask, ShiftLeft<1>(v), v);
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> operator<<(Vec128<T, N> v, const Vec128<T, N> bits) {
  const DFromV<decltype(v)> d;
  Mask128<T, N> mask;
  // Need a signed type for BroadcastSignBit.
  auto test = BitCast(RebindToSigned<decltype(d)>(), bits);
  // Move the highest valid bit of the shift count into the sign bit.
  test = ShiftLeft<27>(test);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<16>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<8>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<4>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftLeft<2>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  return IfThenElse(mask, ShiftLeft<1>(v), v);
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> operator<<(Vec128<T, N> v, const Vec128<T, N> bits) {
  const DFromV<decltype(v)> d;
  alignas(16) T lanes[2];
  alignas(16) T bits_lanes[2];
  Store(v, d, lanes);
  Store(bits, d, bits_lanes);
  lanes[0] <<= bits_lanes[0];
  lanes[1] <<= bits_lanes[1];
  return Load(d, lanes);
}

// ------------------------------ Shr (BroadcastSignBit, IfThenElse)

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> operator>>(Vec128<T, N> v, const Vec128<T, N> bits) {
  const DFromV<decltype(v)> d;
  Mask128<T, N> mask;
  // Need a signed type for BroadcastSignBit.
  auto test = BitCast(RebindToSigned<decltype(d)>(), bits);
  // Move the highest valid bit of the shift count into the sign bit.
  test = ShiftLeft<12>(test);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<8>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<4>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<2>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  return IfThenElse(mask, ShiftRight<1>(v), v);
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> operator>>(Vec128<T, N> v, const Vec128<T, N> bits) {
  const DFromV<decltype(v)> d;
  Mask128<T, N> mask;
  // Need a signed type for BroadcastSignBit.
  auto test = BitCast(RebindToSigned<decltype(d)>(), bits);
  // Move the highest valid bit of the shift count into the sign bit.
  test = ShiftLeft<27>(test);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<16>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<8>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<4>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  test = ShiftLeft<1>(test);  // next bit (descending order)
  v = IfThenElse(mask, ShiftRight<2>(v), v);

  mask = RebindMask(d, MaskFromVec(BroadcastSignBit(test)));
  return IfThenElse(mask, ShiftRight<1>(v), v);
}

// ================================================== MEMORY

// ------------------------------ Load

template <typename T>
HWY_API Vec128<T> Load(Full128<T> /* tag */, const T* HWY_RESTRICT aligned) {
  return Vec128<T>{wasm_v128_load(aligned)};
}

template <typename T, size_t N>
HWY_API Vec128<T, N> MaskedLoad(Mask128<T, N> m, Simd<T, N, 0> d,
                                const T* HWY_RESTRICT aligned) {
  return IfThenElseZero(m, Load(d, aligned));
}

// Partial load.
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API Vec128<T, N> Load(Simd<T, N, 0> /* tag */, const T* HWY_RESTRICT p) {
  Vec128<T, N> v;
  CopyBytes<sizeof(T) * N>(p, &v);
  return v;
}

// LoadU == Load.
template <typename T, size_t N>
HWY_API Vec128<T, N> LoadU(Simd<T, N, 0> d, const T* HWY_RESTRICT p) {
  return Load(d, p);
}

// 128-bit SIMD => nothing to duplicate, same as an unaligned load.
template <typename T, size_t N, HWY_IF_LE128(T, N)>
HWY_API Vec128<T, N> LoadDup128(Simd<T, N, 0> d, const T* HWY_RESTRICT p) {
  return Load(d, p);
}

// ------------------------------ Store

template <typename T>
HWY_API void Store(Vec128<T> v, Full128<T> /* tag */, T* HWY_RESTRICT aligned) {
  wasm_v128_store(aligned, v.raw);
}

// Partial store.
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API void Store(Vec128<T, N> v, Simd<T, N, 0> /* tag */, T* HWY_RESTRICT p) {
  CopyBytes<sizeof(T) * N>(&v, p);
}

HWY_API void Store(const Vec128<float, 1> v, Simd<float, 1, 0> /* tag */,
                   float* HWY_RESTRICT p) {
  *p = wasm_f32x4_extract_lane(v.raw, 0);
}

// StoreU == Store.
template <typename T, size_t N>
HWY_API void StoreU(Vec128<T, N> v, Simd<T, N, 0> d, T* HWY_RESTRICT p) {
  Store(v, d, p);
}

template <typename T, size_t N>
HWY_API void BlendedStore(Vec128<T, N> v, Mask128<T, N> m, Simd<T, N, 0> d,
                          T* HWY_RESTRICT p) {
  StoreU(IfThenElse(m, v, LoadU(d, p)), d, p);
}

// ------------------------------ Non-temporal stores

// Same as aligned stores on non-x86.

template <typename T, size_t N>
HWY_API void Stream(Vec128<T, N> v, Simd<T, N, 0> /* tag */,
                    T* HWY_RESTRICT aligned) {
  wasm_v128_store(aligned, v.raw);
}

// ------------------------------ Scatter (Store)

template <typename T, size_t N, typename Offset, HWY_IF_LE128(T, N)>
HWY_API void ScatterOffset(Vec128<T, N> v, Simd<T, N, 0> d,
                           T* HWY_RESTRICT base,
                           const Vec128<Offset, N> offset) {
  static_assert(sizeof(T) == sizeof(Offset), "Must match for portability");

  alignas(16) T lanes[N];
  Store(v, d, lanes);

  alignas(16) Offset offset_lanes[N];
  Store(offset, Rebind<Offset, decltype(d)>(), offset_lanes);

  uint8_t* base_bytes = reinterpret_cast<uint8_t*>(base);
  for (size_t i = 0; i < N; ++i) {
    CopyBytes<sizeof(T)>(&lanes[i], base_bytes + offset_lanes[i]);
  }
}

template <typename T, size_t N, typename Index, HWY_IF_LE128(T, N)>
HWY_API void ScatterIndex(Vec128<T, N> v, Simd<T, N, 0> d, T* HWY_RESTRICT base,
                          const Vec128<Index, N> index) {
  static_assert(sizeof(T) == sizeof(Index), "Must match for portability");

  alignas(16) T lanes[N];
  Store(v, d, lanes);

  alignas(16) Index index_lanes[N];
  Store(index, Rebind<Index, decltype(d)>(), index_lanes);

  for (size_t i = 0; i < N; ++i) {
    base[index_lanes[i]] = lanes[i];
  }
}

// ------------------------------ Gather (Load/Store)

template <typename T, size_t N, typename Offset>
HWY_API Vec128<T, N> GatherOffset(const Simd<T, N, 0> d,
                                  const T* HWY_RESTRICT base,
                                  const Vec128<Offset, N> offset) {
  static_assert(sizeof(T) == sizeof(Offset), "Must match for portability");

  alignas(16) Offset offset_lanes[N];
  Store(offset, Rebind<Offset, decltype(d)>(), offset_lanes);

  alignas(16) T lanes[N];
  const uint8_t* base_bytes = reinterpret_cast<const uint8_t*>(base);
  for (size_t i = 0; i < N; ++i) {
    CopyBytes<sizeof(T)>(base_bytes + offset_lanes[i], &lanes[i]);
  }
  return Load(d, lanes);
}

template <typename T, size_t N, typename Index>
HWY_API Vec128<T, N> GatherIndex(const Simd<T, N, 0> d,
                                 const T* HWY_RESTRICT base,
                                 const Vec128<Index, N> index) {
  static_assert(sizeof(T) == sizeof(Index), "Must match for portability");

  alignas(16) Index index_lanes[N];
  Store(index, Rebind<Index, decltype(d)>(), index_lanes);

  alignas(16) T lanes[N];
  for (size_t i = 0; i < N; ++i) {
    lanes[i] = base[index_lanes[i]];
  }
  return Load(d, lanes);
}

// ================================================== SWIZZLE

// ------------------------------ ExtractLane

namespace detail {

template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_INLINE T ExtractLane(const Vec128<T, N> v) {
  return static_cast<T>(wasm_i8x16_extract_lane(v.raw, kLane));
}
template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_INLINE T ExtractLane(const Vec128<T, N> v) {
  return static_cast<T>(wasm_i16x8_extract_lane(v.raw, kLane));
}
template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_INLINE T ExtractLane(const Vec128<T, N> v) {
  return static_cast<T>(wasm_i32x4_extract_lane(v.raw, kLane));
}
template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_INLINE T ExtractLane(const Vec128<T, N> v) {
  return static_cast<T>(wasm_i64x2_extract_lane(v.raw, kLane));
}

template <size_t kLane, size_t N>
HWY_INLINE float ExtractLane(const Vec128<float, N> v) {
  return wasm_f32x4_extract_lane(v.raw, kLane);
}

}  // namespace detail

// One overload per vector length just in case *_extract_lane raise compile
// errors if their argument is out of bounds (even if that would never be
// reached at runtime).
template <typename T>
HWY_API T ExtractLane(const Vec128<T, 1> v, size_t i) {
  HWY_DASSERT(i == 0);
  (void)i;
  return GetLane(v);
}

template <typename T>
HWY_API T ExtractLane(const Vec128<T, 2> v, size_t i) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::ExtractLane<0>(v);
      case 1:
        return detail::ExtractLane<1>(v);
    }
  }
#endif
  alignas(16) T lanes[2];
  Store(v, DFromV<decltype(v)>(), lanes);
  return lanes[i];
}

template <typename T>
HWY_API T ExtractLane(const Vec128<T, 4> v, size_t i) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::ExtractLane<0>(v);
      case 1:
        return detail::ExtractLane<1>(v);
      case 2:
        return detail::ExtractLane<2>(v);
      case 3:
        return detail::ExtractLane<3>(v);
    }
  }
#endif
  alignas(16) T lanes[4];
  Store(v, DFromV<decltype(v)>(), lanes);
  return lanes[i];
}

template <typename T>
HWY_API T ExtractLane(const Vec128<T, 8> v, size_t i) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::ExtractLane<0>(v);
      case 1:
        return detail::ExtractLane<1>(v);
      case 2:
        return detail::ExtractLane<2>(v);
      case 3:
        return detail::ExtractLane<3>(v);
      case 4:
        return detail::ExtractLane<4>(v);
      case 5:
        return detail::ExtractLane<5>(v);
      case 6:
        return detail::ExtractLane<6>(v);
      case 7:
        return detail::ExtractLane<7>(v);
    }
  }
#endif
  alignas(16) T lanes[8];
  Store(v, DFromV<decltype(v)>(), lanes);
  return lanes[i];
}

template <typename T>
HWY_API T ExtractLane(const Vec128<T, 16> v, size_t i) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::ExtractLane<0>(v);
      case 1:
        return detail::ExtractLane<1>(v);
      case 2:
        return detail::ExtractLane<2>(v);
      case 3:
        return detail::ExtractLane<3>(v);
      case 4:
        return detail::ExtractLane<4>(v);
      case 5:
        return detail::ExtractLane<5>(v);
      case 6:
        return detail::ExtractLane<6>(v);
      case 7:
        return detail::ExtractLane<7>(v);
      case 8:
        return detail::ExtractLane<8>(v);
      case 9:
        return detail::ExtractLane<9>(v);
      case 10:
        return detail::ExtractLane<10>(v);
      case 11:
        return detail::ExtractLane<11>(v);
      case 12:
        return detail::ExtractLane<12>(v);
      case 13:
        return detail::ExtractLane<13>(v);
      case 14:
        return detail::ExtractLane<14>(v);
      case 15:
        return detail::ExtractLane<15>(v);
    }
  }
#endif
  alignas(16) T lanes[16];
  Store(v, DFromV<decltype(v)>(), lanes);
  return lanes[i];
}

// ------------------------------ GetLane
template <typename T, size_t N>
HWY_API T GetLane(const Vec128<T, N> v) {
  return detail::ExtractLane<0>(v);
}

// ------------------------------ InsertLane

namespace detail {

template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_INLINE Vec128<T, N> InsertLane(const Vec128<T, N> v, T t) {
  static_assert(kLane < N, "Lane index out of bounds");
  return Vec128<T, N>{
      wasm_i8x16_replace_lane(v.raw, kLane, static_cast<int8_t>(t))};
}

template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_INLINE Vec128<T, N> InsertLane(const Vec128<T, N> v, T t) {
  static_assert(kLane < N, "Lane index out of bounds");
  return Vec128<T, N>{
      wasm_i16x8_replace_lane(v.raw, kLane, static_cast<int16_t>(t))};
}

template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_INLINE Vec128<T, N> InsertLane(const Vec128<T, N> v, T t) {
  static_assert(kLane < N, "Lane index out of bounds");
  return Vec128<T, N>{
      wasm_i32x4_replace_lane(v.raw, kLane, static_cast<int32_t>(t))};
}

template <size_t kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_INLINE Vec128<T, N> InsertLane(const Vec128<T, N> v, T t) {
  static_assert(kLane < N, "Lane index out of bounds");
  return Vec128<T, N>{
      wasm_i64x2_replace_lane(v.raw, kLane, static_cast<int64_t>(t))};
}

template <size_t kLane, size_t N>
HWY_INLINE Vec128<float, N> InsertLane(const Vec128<float, N> v, float t) {
  static_assert(kLane < N, "Lane index out of bounds");
  return Vec128<float, N>{wasm_f32x4_replace_lane(v.raw, kLane, t)};
}

template <size_t kLane, size_t N>
HWY_INLINE Vec128<double, N> InsertLane(const Vec128<double, N> v, double t) {
  static_assert(kLane < 2, "Lane index out of bounds");
  return Vec128<double, N>{wasm_f64x2_replace_lane(v.raw, kLane, t)};
}

}  // namespace detail

// Requires one overload per vector length because InsertLane<3> may be a
// compile error if it calls wasm_f64x2_replace_lane.

template <typename T>
HWY_API Vec128<T, 1> InsertLane(const Vec128<T, 1> v, size_t i, T t) {
  HWY_DASSERT(i == 0);
  (void)i;
  return Set(DFromV<decltype(v)>(), t);
}

template <typename T>
HWY_API Vec128<T, 2> InsertLane(const Vec128<T, 2> v, size_t i, T t) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::InsertLane<0>(v, t);
      case 1:
        return detail::InsertLane<1>(v, t);
    }
  }
#endif
  const DFromV<decltype(v)> d;
  alignas(16) T lanes[2];
  Store(v, d, lanes);
  lanes[i] = t;
  return Load(d, lanes);
}

template <typename T>
HWY_API Vec128<T, 4> InsertLane(const Vec128<T, 4> v, size_t i, T t) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::InsertLane<0>(v, t);
      case 1:
        return detail::InsertLane<1>(v, t);
      case 2:
        return detail::InsertLane<2>(v, t);
      case 3:
        return detail::InsertLane<3>(v, t);
    }
  }
#endif
  const DFromV<decltype(v)> d;
  alignas(16) T lanes[4];
  Store(v, d, lanes);
  lanes[i] = t;
  return Load(d, lanes);
}

template <typename T>
HWY_API Vec128<T, 8> InsertLane(const Vec128<T, 8> v, size_t i, T t) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::InsertLane<0>(v, t);
      case 1:
        return detail::InsertLane<1>(v, t);
      case 2:
        return detail::InsertLane<2>(v, t);
      case 3:
        return detail::InsertLane<3>(v, t);
      case 4:
        return detail::InsertLane<4>(v, t);
      case 5:
        return detail::InsertLane<5>(v, t);
      case 6:
        return detail::InsertLane<6>(v, t);
      case 7:
        return detail::InsertLane<7>(v, t);
    }
  }
#endif
  const DFromV<decltype(v)> d;
  alignas(16) T lanes[8];
  Store(v, d, lanes);
  lanes[i] = t;
  return Load(d, lanes);
}

template <typename T>
HWY_API Vec128<T, 16> InsertLane(const Vec128<T, 16> v, size_t i, T t) {
#if !HWY_IS_DEBUG_BUILD && HWY_COMPILER_GCC  // includes clang
  if (__builtin_constant_p(i)) {
    switch (i) {
      case 0:
        return detail::InsertLane<0>(v, t);
      case 1:
        return detail::InsertLane<1>(v, t);
      case 2:
        return detail::InsertLane<2>(v, t);
      case 3:
        return detail::InsertLane<3>(v, t);
      case 4:
        return detail::InsertLane<4>(v, t);
      case 5:
        return detail::InsertLane<5>(v, t);
      case 6:
        return detail::InsertLane<6>(v, t);
      case 7:
        return detail::InsertLane<7>(v, t);
      case 8:
        return detail::InsertLane<8>(v, t);
      case 9:
        return detail::InsertLane<9>(v, t);
      case 10:
        return detail::InsertLane<10>(v, t);
      case 11:
        return detail::InsertLane<11>(v, t);
      case 12:
        return detail::InsertLane<12>(v, t);
      case 13:
        return detail::InsertLane<13>(v, t);
      case 14:
        return detail::InsertLane<14>(v, t);
      case 15:
        return detail::InsertLane<15>(v, t);
    }
  }
#endif
  const DFromV<decltype(v)> d;
  alignas(16) T lanes[16];
  Store(v, d, lanes);
  lanes[i] = t;
  return Load(d, lanes);
}

// ------------------------------ LowerHalf

template <typename T, size_t N>
HWY_API Vec128<T, N / 2> LowerHalf(Simd<T, N / 2, 0> /* tag */,
                                   Vec128<T, N> v) {
  return Vec128<T, N / 2>{v.raw};
}

template <typename T, size_t N>
HWY_API Vec128<T, N / 2> LowerHalf(Vec128<T, N> v) {
  return LowerHalf(Simd<T, N / 2, 0>(), v);
}

// ------------------------------ ShiftLeftBytes

// 0x01..0F, kBytes = 1 => 0x02..0F00
template <int kBytes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftLeftBytes(Simd<T, N, 0> /* tag */, Vec128<T, N> v) {
  static_assert(0 <= kBytes && kBytes <= 16, "Invalid kBytes");
  const __i8x16 zero = wasm_i8x16_splat(0);
  switch (kBytes) {
    case 0:
      return v;

    case 1:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 0, 1, 2, 3, 4, 5,
                                             6, 7, 8, 9, 10, 11, 12, 13, 14)};

    case 2:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 0, 1, 2, 3, 4,
                                             5, 6, 7, 8, 9, 10, 11, 12, 13)};

    case 3:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 0, 1, 2,
                                             3, 4, 5, 6, 7, 8, 9, 10, 11, 12)};

    case 4:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 0, 1,
                                             2, 3, 4, 5, 6, 7, 8, 9, 10, 11)};

    case 5:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16, 0,
                                             1, 2, 3, 4, 5, 6, 7, 8, 9, 10)};

    case 6:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9)};

    case 7:
      return Vec128<T, N>{wasm_i8x16_shuffle(
          v.raw, zero, 16, 16, 16, 16, 16, 16, 16, 0, 1, 2, 3, 4, 5, 6, 7, 8)};

    case 8:
      return Vec128<T, N>{wasm_i8x16_shuffle(
          v.raw, zero, 16, 16, 16, 16, 16, 16, 16, 16, 0, 1, 2, 3, 4, 5, 6, 7)};

    case 9:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 0, 1, 2, 3, 4, 5,
                                             6)};

    case 10:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 0, 1, 2, 3, 4,
                                             5)};

    case 11:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 16, 0, 1, 2, 3,
                                             4)};

    case 12:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 16, 16, 0, 1,
                                             2, 3)};

    case 13:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 16, 16, 16, 0,
                                             1, 2)};

    case 14:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 16, 16, 16, 16,
                                             0, 1)};

    case 15:
      return Vec128<T, N>{wasm_i8x16_shuffle(v.raw, zero, 16, 16, 16, 16, 16,
                                             16, 16, 16, 16, 16, 16, 16, 16, 16,
                                             16, 0)};
  }
  return Vec128<T, N>{zero};
}

template <int kBytes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftLeftBytes(Vec128<T, N> v) {
  return ShiftLeftBytes<kBytes>(Simd<T, N, 0>(), v);
}

// ------------------------------ ShiftLeftLanes

template <int kLanes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftLeftLanes(Simd<T, N, 0> d, const Vec128<T, N> v) {
  const Repartition<uint8_t, decltype(d)> d8;
  return BitCast(d, ShiftLeftBytes<kLanes * sizeof(T)>(BitCast(d8, v)));
}

template <int kLanes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftLeftLanes(const Vec128<T, N> v) {
  return ShiftLeftLanes<kLanes>(DFromV<decltype(v)>(), v);
}

// ------------------------------ ShiftRightBytes
namespace detail {

// Helper function allows zeroing invalid lanes in caller.
template <int kBytes, typename T, size_t N>
HWY_API __i8x16 ShrBytes(const Vec128<T, N> v) {
  static_assert(0 <= kBytes && kBytes <= 16, "Invalid kBytes");
  const __i8x16 zero = wasm_i8x16_splat(0);

  switch (kBytes) {
    case 0:
      return v.raw;

    case 1:
      return wasm_i8x16_shuffle(v.raw, zero, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
                                12, 13, 14, 15, 16);

    case 2:
      return wasm_i8x16_shuffle(v.raw, zero, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
                                13, 14, 15, 16, 16);

    case 3:
      return wasm_i8x16_shuffle(v.raw, zero, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
                                13, 14, 15, 16, 16, 16);

    case 4:
      return wasm_i8x16_shuffle(v.raw, zero, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13,
                                14, 15, 16, 16, 16, 16);

    case 5:
      return wasm_i8x16_shuffle(v.raw, zero, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
                                15, 16, 16, 16, 16, 16);

    case 6:
      return wasm_i8x16_shuffle(v.raw, zero, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
                                16, 16, 16, 16, 16, 16);

    case 7:
      return wasm_i8x16_shuffle(v.raw, zero, 7, 8, 9, 10, 11, 12, 13, 14, 15,
                                16, 16, 16, 16, 16, 16, 16);

    case 8:
      return wasm_i8x16_shuffle(v.raw, zero, 8, 9, 10, 11, 12, 13, 14, 15, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 9:
      return wasm_i8x16_shuffle(v.raw, zero, 9, 10, 11, 12, 13, 14, 15, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 10:
      return wasm_i8x16_shuffle(v.raw, zero, 10, 11, 12, 13, 14, 15, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 11:
      return wasm_i8x16_shuffle(v.raw, zero, 11, 12, 13, 14, 15, 16, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 12:
      return wasm_i8x16_shuffle(v.raw, zero, 12, 13, 14, 15, 16, 16, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 13:
      return wasm_i8x16_shuffle(v.raw, zero, 13, 14, 15, 16, 16, 16, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 14:
      return wasm_i8x16_shuffle(v.raw, zero, 14, 15, 16, 16, 16, 16, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);

    case 15:
      return wasm_i8x16_shuffle(v.raw, zero, 15, 16, 16, 16, 16, 16, 16, 16, 16,
                                16, 16, 16, 16, 16, 16, 16);
    case 16:
      return zero;
  }
}

}  // namespace detail

// 0x01..0F, kBytes = 1 => 0x0001..0E
template <int kBytes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftRightBytes(Simd<T, N, 0> /* tag */, Vec128<T, N> v) {
  // For partial vectors, clear upper lanes so we shift in zeros.
  if (N != 16 / sizeof(T)) {
    const Vec128<T> vfull{v.raw};
    v = Vec128<T, N>{IfThenElseZero(FirstN(Full128<T>(), N), vfull).raw};
  }
  return Vec128<T, N>{detail::ShrBytes<kBytes>(v)};
}

// ------------------------------ ShiftRightLanes
template <int kLanes, typename T, size_t N>
HWY_API Vec128<T, N> ShiftRightLanes(Simd<T, N, 0> d, const Vec128<T, N> v) {
  const Repartition<uint8_t, decltype(d)> d8;
  return BitCast(d, ShiftRightBytes<kLanes * sizeof(T)>(d8, BitCast(d8, v)));
}

// ------------------------------ UpperHalf (ShiftRightBytes)

// Full input: copy hi into lo (smaller instruction encoding than shifts).
template <typename T>
HWY_API Vec64<T> UpperHalf(Full64<T> /* tag */, const Vec128<T> v) {
  return Vec64<T>{wasm_i32x4_shuffle(v.raw, v.raw, 2, 3, 2, 3)};
}
HWY_API Vec64<float> UpperHalf(Full64<float> /* tag */, const Vec128<float> v) {
  return Vec64<float>{wasm_i32x4_shuffle(v.raw, v.raw, 2, 3, 2, 3)};
}

// Partial
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API Vec128<T, (N + 1) / 2> UpperHalf(Half<Simd<T, N, 0>> /* tag */,
                                         Vec128<T, N> v) {
  const DFromV<decltype(v)> d;
  const RebindToUnsigned<decltype(d)> du;
  const auto vu = BitCast(du, v);
  const auto upper = BitCast(d, ShiftRightBytes<N * sizeof(T) / 2>(du, vu));
  return Vec128<T, (N + 1) / 2>{upper.raw};
}

// ------------------------------ CombineShiftRightBytes

template <int kBytes, typename T, class V = Vec128<T>>
HWY_API V CombineShiftRightBytes(Full128<T> /* tag */, V hi, V lo) {
  static_assert(0 <= kBytes && kBytes <= 16, "Invalid kBytes");
  switch (kBytes) {
    case 0:
      return lo;

    case 1:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
                                  11, 12, 13, 14, 15, 16)};

    case 2:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 2, 3, 4, 5, 6, 7, 8, 9, 10,
                                  11, 12, 13, 14, 15, 16, 17)};

    case 3:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 3, 4, 5, 6, 7, 8, 9, 10, 11,
                                  12, 13, 14, 15, 16, 17, 18)};

    case 4:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 4, 5, 6, 7, 8, 9, 10, 11, 12,
                                  13, 14, 15, 16, 17, 18, 19)};

    case 5:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 5, 6, 7, 8, 9, 10, 11, 12, 13,
                                  14, 15, 16, 17, 18, 19, 20)};

    case 6:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 6, 7, 8, 9, 10, 11, 12, 13,
                                  14, 15, 16, 17, 18, 19, 20, 21)};

    case 7:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 7, 8, 9, 10, 11, 12, 13, 14,
                                  15, 16, 17, 18, 19, 20, 21, 22)};

    case 8:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 8, 9, 10, 11, 12, 13, 14, 15,
                                  16, 17, 18, 19, 20, 21, 22, 23)};

    case 9:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 9, 10, 11, 12, 13, 14, 15, 16,
                                  17, 18, 19, 20, 21, 22, 23, 24)};

    case 10:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 10, 11, 12, 13, 14, 15, 16,
                                  17, 18, 19, 20, 21, 22, 23, 24, 25)};

    case 11:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 11, 12, 13, 14, 15, 16, 17,
                                  18, 19, 20, 21, 22, 23, 24, 25, 26)};

    case 12:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 12, 13, 14, 15, 16, 17, 18,
                                  19, 20, 21, 22, 23, 24, 25, 26, 27)};

    case 13:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 13, 14, 15, 16, 17, 18, 19,
                                  20, 21, 22, 23, 24, 25, 26, 27, 28)};

    case 14:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 14, 15, 16, 17, 18, 19, 20,
                                  21, 22, 23, 24, 25, 26, 27, 28, 29)};

    case 15:
      return V{wasm_i8x16_shuffle(lo.raw, hi.raw, 15, 16, 17, 18, 19, 20, 21,
                                  22, 23, 24, 25, 26, 27, 28, 29, 30)};
  }
  return hi;
}

template <int kBytes, typename T, size_t N, HWY_IF_LE64(T, N),
          class V = Vec128<T, N>>
HWY_API V CombineShiftRightBytes(Simd<T, N, 0> d, V hi, V lo) {
  constexpr size_t kSize = N * sizeof(T);
  static_assert(0 < kBytes && kBytes < kSize, "kBytes invalid");
  const Repartition<uint8_t, decltype(d)> d8;
  const Full128<uint8_t> d_full8;
  using V8 = VFromD<decltype(d_full8)>;
  const V8 hi8{BitCast(d8, hi).raw};
  // Move into most-significant bytes
  const V8 lo8 = ShiftLeftBytes<16 - kSize>(V8{BitCast(d8, lo).raw});
  const V8 r = CombineShiftRightBytes<16 - kSize + kBytes>(d_full8, hi8, lo8);
  return V{BitCast(Full128<T>(), r).raw};
}

// ------------------------------ Broadcast/splat any lane

template <int kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Broadcast(const Vec128<T, N> v) {
  static_assert(0 <= kLane && kLane < N, "Invalid lane");
  return Vec128<T, N>{wasm_i16x8_shuffle(v.raw, v.raw, kLane, kLane, kLane,
                                         kLane, kLane, kLane, kLane, kLane)};
}

template <int kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Broadcast(const Vec128<T, N> v) {
  static_assert(0 <= kLane && kLane < N, "Invalid lane");
  return Vec128<T, N>{
      wasm_i32x4_shuffle(v.raw, v.raw, kLane, kLane, kLane, kLane)};
}

template <int kLane, typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> Broadcast(const Vec128<T, N> v) {
  static_assert(0 <= kLane && kLane < N, "Invalid lane");
  return Vec128<T, N>{wasm_i64x2_shuffle(v.raw, v.raw, kLane, kLane)};
}

// ------------------------------ TableLookupBytes

// Returns vector of bytes[from[i]]. "from" is also interpreted as bytes, i.e.
// lane indices in [0, 16).
template <typename T, size_t N, typename TI, size_t NI>
HWY_API Vec128<TI, NI> TableLookupBytes(const Vec128<T, N> bytes,
                                        const Vec128<TI, NI> from) {
// Not yet available in all engines, see
// https://github.com/WebAssembly/simd/blob/bdcc304b2d379f4601c2c44ea9b44ed9484fde7e/proposals/simd/ImplementationStatus.md
// V8 implementation of this had a bug, fixed on 2021-04-03:
// https://chromium-review.googlesource.com/c/v8/v8/+/2822951
#if 0
  return Vec128<TI, NI>{wasm_i8x16_swizzle(bytes.raw, from.raw)};
#else
  alignas(16) uint8_t control[16];
  alignas(16) uint8_t input[16];
  alignas(16) uint8_t output[16];
  wasm_v128_store(control, from.raw);
  wasm_v128_store(input, bytes.raw);
  for (size_t i = 0; i < 16; ++i) {
    output[i] = control[i] < 16 ? input[control[i]] : 0;
  }
  return Vec128<TI, NI>{wasm_v128_load(output)};
#endif
}

template <typename T, size_t N, typename TI, size_t NI>
HWY_API Vec128<TI, NI> TableLookupBytesOr0(const Vec128<T, N> bytes,
                                           const Vec128<TI, NI> from) {
  const Simd<TI, NI, 0> d;
  // Mask size must match vector type, so cast everything to this type.
  Repartition<int8_t, decltype(d)> di8;
  Repartition<int8_t, Simd<T, N, 0>> d_bytes8;
  const auto msb = BitCast(di8, from) < Zero(di8);
  const auto lookup =
      TableLookupBytes(BitCast(d_bytes8, bytes), BitCast(di8, from));
  return BitCast(d, IfThenZeroElse(msb, lookup));
}

// ------------------------------ Hard-coded shuffles

// Notation: let Vec128<int32_t> have lanes 3,2,1,0 (0 is least-significant).
// Shuffle0321 rotates one lane to the right (the previous least-significant
// lane is now most-significant). These could also be implemented via
// CombineShiftRightBytes but the shuffle_abcd notation is more convenient.

// Swap 32-bit halves in 64-bit halves.
template <typename T, size_t N>
HWY_API Vec128<T, N> Shuffle2301(const Vec128<T, N> v) {
  static_assert(sizeof(T) == 4, "Only for 32-bit lanes");
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i32x4_shuffle(v.raw, v.raw, 1, 0, 3, 2)};
}

// These are used by generic_ops-inl to implement LoadInterleaved3.
namespace detail {

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> Shuffle2301(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i8x16_shuffle(a.raw, b.raw, 1, 0, 3 + 16, 2 + 16,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Shuffle2301(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i16x8_shuffle(a.raw, b.raw, 1, 0, 3 + 8, 2 + 8,
                                         0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Shuffle2301(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i32x4_shuffle(a.raw, b.raw, 1, 0, 3 + 4, 2 + 4)};
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> Shuffle1230(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i8x16_shuffle(a.raw, b.raw, 0, 3, 2 + 16, 1 + 16,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Shuffle1230(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i16x8_shuffle(a.raw, b.raw, 0, 3, 2 + 8, 1 + 8,
                                         0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Shuffle1230(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i32x4_shuffle(a.raw, b.raw, 0, 3, 2 + 4, 1 + 4)};
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, N> Shuffle3012(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i8x16_shuffle(a.raw, b.raw, 2, 1, 0 + 16, 3 + 16,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F,
                                         0x7F, 0x7F, 0x7F, 0x7F, 0x7F, 0x7F)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Shuffle3012(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i16x8_shuffle(a.raw, b.raw, 2, 1, 0 + 8, 3 + 8,
                                         0x7FFF, 0x7FFF, 0x7FFF, 0x7FFF)};
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Shuffle3012(const Vec128<T, N> a, const Vec128<T, N> b) {
  static_assert(N == 2 || N == 4, "Does not make sense for N=1");
  return Vec128<T, N>{wasm_i32x4_shuffle(a.raw, b.raw, 2, 1, 0 + 4, 3 + 4)};
}

}  // namespace detail

// Swap 64-bit halves
template <typename T>
HWY_API Vec128<T> Shuffle01(const Vec128<T> v) {
  static_assert(sizeof(T) == 8, "Only for 64-bit lanes");
  return Vec128<T>{wasm_i64x2_shuffle(v.raw, v.raw, 1, 0)};
}
template <typename T>
HWY_API Vec128<T> Shuffle1032(const Vec128<T> v) {
  static_assert(sizeof(T) == 4, "Only for 32-bit lanes");
  return Vec128<T>{wasm_i64x2_shuffle(v.raw, v.raw, 1, 0)};
}

// Rotate right 32 bits
template <typename T>
HWY_API Vec128<T> Shuffle0321(const Vec128<T> v) {
  static_assert(sizeof(T) == 4, "Only for 32-bit lanes");
  return Vec128<T>{wasm_i32x4_shuffle(v.raw, v.raw, 1, 2, 3, 0)};
}

// Rotate left 32 bits
template <typename T>
HWY_API Vec128<T> Shuffle2103(const Vec128<T> v) {
  static_assert(sizeof(T) == 4, "Only for 32-bit lanes");
  return Vec128<T>{wasm_i32x4_shuffle(v.raw, v.raw, 3, 0, 1, 2)};
}

// Reverse
template <typename T>
HWY_API Vec128<T> Shuffle0123(const Vec128<T> v) {
  static_assert(sizeof(T) == 4, "Only for 32-bit lanes");
  return Vec128<T>{wasm_i32x4_shuffle(v.raw, v.raw, 3, 2, 1, 0)};
}

// ------------------------------ TableLookupLanes

// Returned by SetTableIndices for use by TableLookupLanes.
template <typename T, size_t N>
struct Indices128 {
  __v128_u raw;
};

template <typename T, size_t N, typename TI, HWY_IF_LE128(T, N)>
HWY_API Indices128<T, N> IndicesFromVec(Simd<T, N, 0> d, Vec128<TI, N> vec) {
  static_assert(sizeof(T) == sizeof(TI), "Index size must match lane");
#if HWY_IS_DEBUG_BUILD
  const Rebind<TI, decltype(d)> di;
  HWY_DASSERT(AllFalse(di, Lt(vec, Zero(di))) &&
              AllTrue(di, Lt(vec, Set(di, static_cast<TI>(N)))));
#endif

  const Repartition<uint8_t, decltype(d)> d8;
  using V8 = VFromD<decltype(d8)>;
  const Repartition<uint16_t, decltype(d)> d16;

  // Broadcast each lane index to all bytes of T and shift to bytes
  static_assert(sizeof(T) == 4 || sizeof(T) == 8, "");
  if (sizeof(T) == 4) {
    alignas(16) constexpr uint8_t kBroadcastLaneBytes[16] = {
        0, 0, 0, 0, 4, 4, 4, 4, 8, 8, 8, 8, 12, 12, 12, 12};
    const V8 lane_indices =
        TableLookupBytes(BitCast(d8, vec), Load(d8, kBroadcastLaneBytes));
    const V8 byte_indices =
        BitCast(d8, ShiftLeft<2>(BitCast(d16, lane_indices)));
    alignas(16) constexpr uint8_t kByteOffsets[16] = {0, 1, 2, 3, 0, 1, 2, 3,
                                                      0, 1, 2, 3, 0, 1, 2, 3};
    return Indices128<T, N>{Add(byte_indices, Load(d8, kByteOffsets)).raw};
  } else {
    alignas(16) constexpr uint8_t kBroadcastLaneBytes[16] = {
        0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8};
    const V8 lane_indices =
        TableLookupBytes(BitCast(d8, vec), Load(d8, kBroadcastLaneBytes));
    const V8 byte_indices =
        BitCast(d8, ShiftLeft<3>(BitCast(d16, lane_indices)));
    alignas(16) constexpr uint8_t kByteOffsets[16] = {0, 1, 2, 3, 4, 5, 6, 7,
                                                      0, 1, 2, 3, 4, 5, 6, 7};
    return Indices128<T, N>{Add(byte_indices, Load(d8, kByteOffsets)).raw};
  }
}

template <typename T, size_t N, typename TI, HWY_IF_LE128(T, N)>
HWY_API Indices128<T, N> SetTableIndices(Simd<T, N, 0> d, const TI* idx) {
  const Rebind<TI, decltype(d)> di;
  return IndicesFromVec(d, LoadU(di, idx));
}

template <typename T, size_t N>
HWY_API Vec128<T, N> TableLookupLanes(Vec128<T, N> v, Indices128<T, N> idx) {
  using TI = MakeSigned<T>;
  const DFromV<decltype(v)> d;
  const Rebind<TI, decltype(d)> di;
  return BitCast(d, TableLookupBytes(BitCast(di, v), Vec128<TI, N>{idx.raw}));
}

// ------------------------------ Reverse (Shuffle0123, Shuffle2301, Shuffle01)

// Single lane: no change
template <typename T>
HWY_API Vec128<T, 1> Reverse(Simd<T, 1, 0> /* tag */, const Vec128<T, 1> v) {
  return v;
}

// Two lanes: shuffle
template <typename T, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, 2> Reverse(Simd<T, 2, 0> /* tag */, const Vec128<T, 2> v) {
  return Vec128<T, 2>{Shuffle2301(Vec128<T>{v.raw}).raw};
}

template <typename T, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T> Reverse(Full128<T> /* tag */, const Vec128<T> v) {
  return Shuffle01(v);
}

// Four lanes: shuffle
template <typename T, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T> Reverse(Full128<T> /* tag */, const Vec128<T> v) {
  return Shuffle0123(v);
}

// 16-bit
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Reverse(Simd<T, N, 0> d, const Vec128<T, N> v) {
  const RepartitionToWide<RebindToUnsigned<decltype(d)>> du32;
  return BitCast(d, RotateRight<16>(Reverse(du32, BitCast(du32, v))));
}

// ------------------------------ Reverse2

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Reverse2(Simd<T, N, 0> d, const Vec128<T, N> v) {
  const RepartitionToWide<RebindToUnsigned<decltype(d)>> du32;
  return BitCast(d, RotateRight<16>(BitCast(du32, v)));
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Reverse2(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return Shuffle2301(v);
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> Reverse2(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return Shuffle01(v);
}

// ------------------------------ Reverse4

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Reverse4(Simd<T, N, 0> d, const Vec128<T, N> v) {
  return BitCast(d, Vec128<uint16_t, N>{wasm_i16x8_shuffle(v.raw, v.raw, 3, 2,
                                                           1, 0, 7, 6, 5, 4)});
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> Reverse4(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return Shuffle0123(v);
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> Reverse4(Simd<T, N, 0> /* tag */, const Vec128<T, N>) {
  HWY_ASSERT(0);  // don't have 8 u64 lanes
}

// ------------------------------ Reverse8

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Reverse8(Simd<T, N, 0> d, const Vec128<T, N> v) {
  return Reverse(d, v);
}

template <typename T, size_t N, HWY_IF_NOT_LANE_SIZE(T, 2)>
HWY_API Vec128<T, N> Reverse8(Simd<T, N, 0>, const Vec128<T, N>) {
  HWY_ASSERT(0);  // don't have 8 lanes unless 16-bit
}

// ------------------------------ InterleaveLower

template <size_t N>
HWY_API Vec128<uint8_t, N> InterleaveLower(Vec128<uint8_t, N> a,
                                           Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_i8x16_shuffle(
      a.raw, b.raw, 0, 16, 1, 17, 2, 18, 3, 19, 4, 20, 5, 21, 6, 22, 7, 23)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> InterleaveLower(Vec128<uint16_t, N> a,
                                            Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{
      wasm_i16x8_shuffle(a.raw, b.raw, 0, 8, 1, 9, 2, 10, 3, 11)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> InterleaveLower(Vec128<uint32_t, N> a,
                                            Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_i32x4_shuffle(a.raw, b.raw, 0, 4, 1, 5)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> InterleaveLower(Vec128<uint64_t, N> a,
                                            Vec128<uint64_t, N> b) {
  return Vec128<uint64_t, N>{wasm_i64x2_shuffle(a.raw, b.raw, 0, 2)};
}

template <size_t N>
HWY_API Vec128<int8_t, N> InterleaveLower(Vec128<int8_t, N> a,
                                          Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_shuffle(
      a.raw, b.raw, 0, 16, 1, 17, 2, 18, 3, 19, 4, 20, 5, 21, 6, 22, 7, 23)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> InterleaveLower(Vec128<int16_t, N> a,
                                           Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{
      wasm_i16x8_shuffle(a.raw, b.raw, 0, 8, 1, 9, 2, 10, 3, 11)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> InterleaveLower(Vec128<int32_t, N> a,
                                           Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_shuffle(a.raw, b.raw, 0, 4, 1, 5)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> InterleaveLower(Vec128<int64_t, N> a,
                                           Vec128<int64_t, N> b) {
  return Vec128<int64_t, N>{wasm_i64x2_shuffle(a.raw, b.raw, 0, 2)};
}

template <size_t N>
HWY_API Vec128<float, N> InterleaveLower(Vec128<float, N> a,
                                         Vec128<float, N> b) {
  return Vec128<float, N>{wasm_i32x4_shuffle(a.raw, b.raw, 0, 4, 1, 5)};
}

template <size_t N>
HWY_API Vec128<double, N> InterleaveLower(Vec128<double, N> a,
                                          Vec128<double, N> b) {
  return Vec128<double, N>{wasm_i64x2_shuffle(a.raw, b.raw, 0, 2)};
}

// Additional overload for the optional tag.
template <class V>
HWY_API V InterleaveLower(DFromV<V> /* tag */, V a, V b) {
  return InterleaveLower(a, b);
}

// ------------------------------ InterleaveUpper (UpperHalf)

// All functions inside detail lack the required D parameter.
namespace detail {

template <size_t N>
HWY_API Vec128<uint8_t, N> InterleaveUpper(Vec128<uint8_t, N> a,
                                           Vec128<uint8_t, N> b) {
  return Vec128<uint8_t, N>{wasm_i8x16_shuffle(a.raw, b.raw, 8, 24, 9, 25, 10,
                                               26, 11, 27, 12, 28, 13, 29, 14,
                                               30, 15, 31)};
}
template <size_t N>
HWY_API Vec128<uint16_t, N> InterleaveUpper(Vec128<uint16_t, N> a,
                                            Vec128<uint16_t, N> b) {
  return Vec128<uint16_t, N>{
      wasm_i16x8_shuffle(a.raw, b.raw, 4, 12, 5, 13, 6, 14, 7, 15)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> InterleaveUpper(Vec128<uint32_t, N> a,
                                            Vec128<uint32_t, N> b) {
  return Vec128<uint32_t, N>{wasm_i32x4_shuffle(a.raw, b.raw, 2, 6, 3, 7)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> InterleaveUpper(Vec128<uint64_t, N> a,
                                            Vec128<uint64_t, N> b) {
  return Vec128<uint64_t, N>{wasm_i64x2_shuffle(a.raw, b.raw, 1, 3)};
}

template <size_t N>
HWY_API Vec128<int8_t, N> InterleaveUpper(Vec128<int8_t, N> a,
                                          Vec128<int8_t, N> b) {
  return Vec128<int8_t, N>{wasm_i8x16_shuffle(a.raw, b.raw, 8, 24, 9, 25, 10,
                                              26, 11, 27, 12, 28, 13, 29, 14,
                                              30, 15, 31)};
}
template <size_t N>
HWY_API Vec128<int16_t, N> InterleaveUpper(Vec128<int16_t, N> a,
                                           Vec128<int16_t, N> b) {
  return Vec128<int16_t, N>{
      wasm_i16x8_shuffle(a.raw, b.raw, 4, 12, 5, 13, 6, 14, 7, 15)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> InterleaveUpper(Vec128<int32_t, N> a,
                                           Vec128<int32_t, N> b) {
  return Vec128<int32_t, N>{wasm_i32x4_shuffle(a.raw, b.raw, 2, 6, 3, 7)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> InterleaveUpper(Vec128<int64_t, N> a,
                                           Vec128<int64_t, N> b) {
  return Vec128<int64_t, N>{wasm_i64x2_shuffle(a.raw, b.raw, 1, 3)};
}

template <size_t N>
HWY_API Vec128<float, N> InterleaveUpper(Vec128<float, N> a,
                                         Vec128<float, N> b) {
  return Vec128<float, N>{wasm_i32x4_shuffle(a.raw, b.raw, 2, 6, 3, 7)};
}

template <size_t N>
HWY_API Vec128<double, N> InterleaveUpper(Vec128<double, N> a,
                                          Vec128<double, N> b) {
  return Vec128<double, N>{wasm_i64x2_shuffle(a.raw, b.raw, 1, 3)};
}

}  // namespace detail

// Full
template <typename T, class V = Vec128<T>>
HWY_API V InterleaveUpper(Full128<T> /* tag */, V a, V b) {
  return detail::InterleaveUpper(a, b);
}

// Partial
template <typename T, size_t N, HWY_IF_LE64(T, N), class V = Vec128<T, N>>
HWY_API V InterleaveUpper(Simd<T, N, 0> d, V a, V b) {
  const Half<decltype(d)> d2;
  return InterleaveLower(d, V{UpperHalf(d2, a).raw}, V{UpperHalf(d2, b).raw});
}

// ------------------------------ ZipLower/ZipUpper (InterleaveLower)

// Same as Interleave*, except that the return lanes are double-width integers;
// this is necessary because the single-lane scalar cannot return two values.
template <class V, class DW = RepartitionToWide<DFromV<V>>>
HWY_API VFromD<DW> ZipLower(V a, V b) {
  return BitCast(DW(), InterleaveLower(a, b));
}
template <class V, class D = DFromV<V>, class DW = RepartitionToWide<D>>
HWY_API VFromD<DW> ZipLower(DW dw, V a, V b) {
  return BitCast(dw, InterleaveLower(D(), a, b));
}

template <class V, class D = DFromV<V>, class DW = RepartitionToWide<D>>
HWY_API VFromD<DW> ZipUpper(DW dw, V a, V b) {
  return BitCast(dw, InterleaveUpper(D(), a, b));
}

// ================================================== COMBINE

// ------------------------------ Combine (InterleaveLower)

// N = N/2 + N/2 (upper half undefined)
template <typename T, size_t N>
HWY_API Vec128<T, N> Combine(Simd<T, N, 0> d, Vec128<T, N / 2> hi_half,
                             Vec128<T, N / 2> lo_half) {
  const Half<decltype(d)> d2;
  const RebindToUnsigned<decltype(d2)> du2;
  // Treat half-width input as one lane, and expand to two lanes.
  using VU = Vec128<UnsignedFromSize<N * sizeof(T) / 2>, 2>;
  const VU lo{BitCast(du2, lo_half).raw};
  const VU hi{BitCast(du2, hi_half).raw};
  return BitCast(d, InterleaveLower(lo, hi));
}

// ------------------------------ ZeroExtendVector (Combine, IfThenElseZero)

template <typename T, size_t N>
HWY_API Vec128<T, N> ZeroExtendVector(Simd<T, N, 0> d, Vec128<T, N / 2> lo) {
  return IfThenElseZero(FirstN(d, N / 2), Vec128<T, N>{lo.raw});
}

// ------------------------------ ConcatLowerLower

// hiH,hiL loH,loL |-> hiL,loL (= lower halves)
template <typename T>
HWY_API Vec128<T> ConcatLowerLower(Full128<T> /* tag */, const Vec128<T> hi,
                                   const Vec128<T> lo) {
  return Vec128<T>{wasm_i64x2_shuffle(lo.raw, hi.raw, 0, 2)};
}
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API Vec128<T, N> ConcatLowerLower(Simd<T, N, 0> d, const Vec128<T, N> hi,
                                      const Vec128<T, N> lo) {
  const Half<decltype(d)> d2;
  return Combine(d, LowerHalf(d2, hi), LowerHalf(d2, lo));
}

// ------------------------------ ConcatUpperUpper

template <typename T>
HWY_API Vec128<T> ConcatUpperUpper(Full128<T> /* tag */, const Vec128<T> hi,
                                   const Vec128<T> lo) {
  return Vec128<T>{wasm_i64x2_shuffle(lo.raw, hi.raw, 1, 3)};
}
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API Vec128<T, N> ConcatUpperUpper(Simd<T, N, 0> d, const Vec128<T, N> hi,
                                      const Vec128<T, N> lo) {
  const Half<decltype(d)> d2;
  return Combine(d, UpperHalf(d2, hi), UpperHalf(d2, lo));
}

// ------------------------------ ConcatLowerUpper

template <typename T>
HWY_API Vec128<T> ConcatLowerUpper(Full128<T> d, const Vec128<T> hi,
                                   const Vec128<T> lo) {
  return CombineShiftRightBytes<8>(d, hi, lo);
}
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API Vec128<T, N> ConcatLowerUpper(Simd<T, N, 0> d, const Vec128<T, N> hi,
                                      const Vec128<T, N> lo) {
  const Half<decltype(d)> d2;
  return Combine(d, LowerHalf(d2, hi), UpperHalf(d2, lo));
}

// ------------------------------ ConcatUpperLower
template <typename T, size_t N>
HWY_API Vec128<T, N> ConcatUpperLower(Simd<T, N, 0> d, const Vec128<T, N> hi,
                                      const Vec128<T, N> lo) {
  return IfThenElse(FirstN(d, Lanes(d) / 2), lo, hi);
}

// ------------------------------ ConcatOdd

// 8-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T> ConcatOdd(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{wasm_i8x16_shuffle(lo.raw, hi.raw, 1, 3, 5, 7, 9, 11, 13, 15,
                                      17, 19, 21, 23, 25, 27, 29, 31)};
}

// 8-bit x8
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, 8> ConcatOdd(Simd<T, 8, 0> /* tag */, Vec128<T, 8> hi,
                               Vec128<T, 8> lo) {
  // Don't care about upper half.
  return Vec128<T, 8>{wasm_i8x16_shuffle(lo.raw, hi.raw, 1, 3, 5, 7, 17, 19, 21,
                                         23, 1, 3, 5, 7, 17, 19, 21, 23)};
}

// 8-bit x4
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, 4> ConcatOdd(Simd<T, 4, 0> /* tag */, Vec128<T, 4> hi,
                               Vec128<T, 4> lo) {
  // Don't care about upper 3/4.
  return Vec128<T, 4>{wasm_i8x16_shuffle(lo.raw, hi.raw, 1, 3, 17, 19, 1, 3, 17,
                                         19, 1, 3, 17, 19, 1, 3, 17, 19)};
}

// 16-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T> ConcatOdd(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{
      wasm_i16x8_shuffle(lo.raw, hi.raw, 1, 3, 5, 7, 9, 11, 13, 15)};
}

// 16-bit x4
template <typename T, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, 4> ConcatOdd(Simd<T, 4, 0> /* tag */, Vec128<T, 4> hi,
                               Vec128<T, 4> lo) {
  // Don't care about upper half.
  return Vec128<T, 4>{
      wasm_i16x8_shuffle(lo.raw, hi.raw, 1, 3, 9, 11, 1, 3, 9, 11)};
}

// 32-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T> ConcatOdd(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{wasm_i32x4_shuffle(lo.raw, hi.raw, 1, 3, 5, 7)};
}

// Any T x2
template <typename T>
HWY_API Vec128<T, 2> ConcatOdd(Simd<T, 2, 0> d, Vec128<T, 2> hi,
                               Vec128<T, 2> lo) {
  return InterleaveUpper(d, lo, hi);
}

// ------------------------------ ConcatEven (InterleaveLower)

// 8-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T> ConcatEven(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{wasm_i8x16_shuffle(lo.raw, hi.raw, 0, 2, 4, 6, 8, 10, 12, 14,
                                      16, 18, 20, 22, 24, 26, 28, 30)};
}

// 8-bit x8
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, 8> ConcatEven(Simd<T, 8, 0> /* tag */, Vec128<T, 8> hi,
                                Vec128<T, 8> lo) {
  // Don't care about upper half.
  return Vec128<T, 8>{wasm_i8x16_shuffle(lo.raw, hi.raw, 0, 2, 4, 6, 16, 18, 20,
                                         22, 0, 2, 4, 6, 16, 18, 20, 22)};
}

// 8-bit x4
template <typename T, HWY_IF_LANE_SIZE(T, 1)>
HWY_API Vec128<T, 4> ConcatEven(Simd<T, 4, 0> /* tag */, Vec128<T, 4> hi,
                                Vec128<T, 4> lo) {
  // Don't care about upper 3/4.
  return Vec128<T, 4>{wasm_i8x16_shuffle(lo.raw, hi.raw, 0, 2, 16, 18, 0, 2, 16,
                                         18, 0, 2, 16, 18, 0, 2, 16, 18)};
}

// 16-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T> ConcatEven(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{
      wasm_i16x8_shuffle(lo.raw, hi.raw, 0, 2, 4, 6, 8, 10, 12, 14)};
}

// 16-bit x4
template <typename T, HWY_IF_LANE_SIZE(T, 2)>
HWY_API Vec128<T, 4> ConcatEven(Simd<T, 4, 0> /* tag */, Vec128<T, 4> hi,
                                Vec128<T, 4> lo) {
  // Don't care about upper half.
  return Vec128<T, 4>{
      wasm_i16x8_shuffle(lo.raw, hi.raw, 0, 2, 8, 10, 0, 2, 8, 10)};
}

// 32-bit full
template <typename T, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T> ConcatEven(Full128<T> /* tag */, Vec128<T> hi, Vec128<T> lo) {
  return Vec128<T>{wasm_i32x4_shuffle(lo.raw, hi.raw, 0, 2, 4, 6)};
}

// Any T x2
template <typename T>
HWY_API Vec128<T, 2> ConcatEven(Simd<T, 2, 0> d, Vec128<T, 2> hi,
                                Vec128<T, 2> lo) {
  return InterleaveLower(d, lo, hi);
}

// ------------------------------ DupEven (InterleaveLower)

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> DupEven(Vec128<T, N> v) {
  return Vec128<T, N>{wasm_i32x4_shuffle(v.raw, v.raw, 0, 0, 2, 2)};
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> DupEven(const Vec128<T, N> v) {
  return InterleaveLower(DFromV<decltype(v)>(), v, v);
}

// ------------------------------ DupOdd (InterleaveUpper)

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_API Vec128<T, N> DupOdd(Vec128<T, N> v) {
  return Vec128<T, N>{wasm_i32x4_shuffle(v.raw, v.raw, 1, 1, 3, 3)};
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_API Vec128<T, N> DupOdd(const Vec128<T, N> v) {
  return InterleaveUpper(DFromV<decltype(v)>(), v, v);
}

// ------------------------------ OddEven

namespace detail {

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> OddEven(hwy::SizeTag<1> /* tag */, const Vec128<T, N> a,
                                const Vec128<T, N> b) {
  const DFromV<decltype(a)> d;
  const Repartition<uint8_t, decltype(d)> d8;
  alignas(16) constexpr uint8_t mask[16] = {0xFF, 0, 0xFF, 0, 0xFF, 0, 0xFF, 0,
                                            0xFF, 0, 0xFF, 0, 0xFF, 0, 0xFF, 0};
  return IfThenElse(MaskFromVec(BitCast(d, Load(d8, mask))), b, a);
}
template <typename T, size_t N>
HWY_INLINE Vec128<T, N> OddEven(hwy::SizeTag<2> /* tag */, const Vec128<T, N> a,
                                const Vec128<T, N> b) {
  return Vec128<T, N>{
      wasm_i16x8_shuffle(a.raw, b.raw, 8, 1, 10, 3, 12, 5, 14, 7)};
}
template <typename T, size_t N>
HWY_INLINE Vec128<T, N> OddEven(hwy::SizeTag<4> /* tag */, const Vec128<T, N> a,
                                const Vec128<T, N> b) {
  return Vec128<T, N>{wasm_i32x4_shuffle(a.raw, b.raw, 4, 1, 6, 3)};
}
template <typename T, size_t N>
HWY_INLINE Vec128<T, N> OddEven(hwy::SizeTag<8> /* tag */, const Vec128<T, N> a,
                                const Vec128<T, N> b) {
  return Vec128<T, N>{wasm_i64x2_shuffle(a.raw, b.raw, 2, 1)};
}

}  // namespace detail

template <typename T, size_t N>
HWY_API Vec128<T, N> OddEven(const Vec128<T, N> a, const Vec128<T, N> b) {
  return detail::OddEven(hwy::SizeTag<sizeof(T)>(), a, b);
}
template <size_t N>
HWY_API Vec128<float, N> OddEven(const Vec128<float, N> a,
                                 const Vec128<float, N> b) {
  return Vec128<float, N>{wasm_i32x4_shuffle(a.raw, b.raw, 4, 1, 6, 3)};
}

// ------------------------------ OddEvenBlocks
template <typename T, size_t N>
HWY_API Vec128<T, N> OddEvenBlocks(Vec128<T, N> /* odd */, Vec128<T, N> even) {
  return even;
}

// ------------------------------ SwapAdjacentBlocks

template <typename T, size_t N>
HWY_API Vec128<T, N> SwapAdjacentBlocks(Vec128<T, N> v) {
  return v;
}

// ------------------------------ ReverseBlocks

// Single block: no change
template <typename T>
HWY_API Vec128<T> ReverseBlocks(Full128<T> /* tag */, const Vec128<T> v) {
  return v;
}

// ================================================== CONVERT

// ------------------------------ Promotions (part w/ narrow lanes -> full)

// Unsigned: zero-extend.
template <size_t N>
HWY_API Vec128<uint16_t, N> PromoteTo(Simd<uint16_t, N, 0> /* tag */,
                                      const Vec128<uint8_t, N> v) {
  return Vec128<uint16_t, N>{wasm_u16x8_extend_low_u8x16(v.raw)};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> PromoteTo(Simd<uint32_t, N, 0> /* tag */,
                                      const Vec128<uint8_t, N> v) {
  return Vec128<uint32_t, N>{
      wasm_u32x4_extend_low_u16x8(wasm_u16x8_extend_low_u8x16(v.raw))};
}
template <size_t N>
HWY_API Vec128<int16_t, N> PromoteTo(Simd<int16_t, N, 0> /* tag */,
                                     const Vec128<uint8_t, N> v) {
  return Vec128<int16_t, N>{wasm_u16x8_extend_low_u8x16(v.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> PromoteTo(Simd<int32_t, N, 0> /* tag */,
                                     const Vec128<uint8_t, N> v) {
  return Vec128<int32_t, N>{
      wasm_u32x4_extend_low_u16x8(wasm_u16x8_extend_low_u8x16(v.raw))};
}
template <size_t N>
HWY_API Vec128<uint32_t, N> PromoteTo(Simd<uint32_t, N, 0> /* tag */,
                                      const Vec128<uint16_t, N> v) {
  return Vec128<uint32_t, N>{wasm_u32x4_extend_low_u16x8(v.raw)};
}
template <size_t N>
HWY_API Vec128<uint64_t, N> PromoteTo(Simd<uint64_t, N, 0> /* tag */,
                                      const Vec128<uint32_t, N> v) {
  return Vec128<uint64_t, N>{wasm_u64x2_extend_low_u32x4(v.raw)};
}

template <size_t N>
HWY_API Vec128<int32_t, N> PromoteTo(Simd<int32_t, N, 0> /* tag */,
                                     const Vec128<uint16_t, N> v) {
  return Vec128<int32_t, N>{wasm_u32x4_extend_low_u16x8(v.raw)};
}

// Signed: replicate sign bit.
template <size_t N>
HWY_API Vec128<int16_t, N> PromoteTo(Simd<int16_t, N, 0> /* tag */,
                                     const Vec128<int8_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_extend_low_i8x16(v.raw)};
}
template <size_t N>
HWY_API Vec128<int32_t, N> PromoteTo(Simd<int32_t, N, 0> /* tag */,
                                     const Vec128<int8_t, N> v) {
  return Vec128<int32_t, N>{
      wasm_i32x4_extend_low_i16x8(wasm_i16x8_extend_low_i8x16(v.raw))};
}
template <size_t N>
HWY_API Vec128<int32_t, N> PromoteTo(Simd<int32_t, N, 0> /* tag */,
                                     const Vec128<int16_t, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_extend_low_i16x8(v.raw)};
}
template <size_t N>
HWY_API Vec128<int64_t, N> PromoteTo(Simd<int64_t, N, 0> /* tag */,
                                     const Vec128<int32_t, N> v) {
  return Vec128<int64_t, N>{wasm_i64x2_extend_low_i32x4(v.raw)};
}

template <size_t N>
HWY_API Vec128<double, N> PromoteTo(Simd<double, N, 0> /* tag */,
                                    const Vec128<int32_t, N> v) {
  return Vec128<double, N>{wasm_f64x2_convert_low_i32x4(v.raw)};
}

template <size_t N>
HWY_API Vec128<float, N> PromoteTo(Simd<float, N, 0> df32,
                                   const Vec128<float16_t, N> v) {
  const RebindToSigned<decltype(df32)> di32;
  const RebindToUnsigned<decltype(df32)> du32;
  // Expand to u32 so we can shift.
  const auto bits16 = PromoteTo(du32, Vec128<uint16_t, N>{v.raw});
  const auto sign = ShiftRight<15>(bits16);
  const auto biased_exp = ShiftRight<10>(bits16) & Set(du32, 0x1F);
  const auto mantissa = bits16 & Set(du32, 0x3FF);
  const auto subnormal =
      BitCast(du32, ConvertTo(df32, BitCast(di32, mantissa)) *
                        Set(df32, 1.0f / 16384 / 1024));

  const auto biased_exp32 = biased_exp + Set(du32, 127 - 15);
  const auto mantissa32 = ShiftLeft<23 - 10>(mantissa);
  const auto normal = ShiftLeft<23>(biased_exp32) | mantissa32;
  const auto bits32 = IfThenElse(biased_exp == Zero(du32), subnormal, normal);
  return BitCast(df32, ShiftLeft<31>(sign) | bits32);
}

template <size_t N>
HWY_API Vec128<float, N> PromoteTo(Simd<float, N, 0> df32,
                                   const Vec128<bfloat16_t, N> v) {
  const Rebind<uint16_t, decltype(df32)> du16;
  const RebindToSigned<decltype(df32)> di32;
  return BitCast(df32, ShiftLeft<16>(PromoteTo(di32, BitCast(du16, v))));
}

// ------------------------------ Demotions (full -> part w/ narrow lanes)

template <size_t N>
HWY_API Vec128<uint16_t, N> DemoteTo(Simd<uint16_t, N, 0> /* tag */,
                                     const Vec128<int32_t, N> v) {
  return Vec128<uint16_t, N>{wasm_u16x8_narrow_i32x4(v.raw, v.raw)};
}

template <size_t N>
HWY_API Vec128<int16_t, N> DemoteTo(Simd<int16_t, N, 0> /* tag */,
                                    const Vec128<int32_t, N> v) {
  return Vec128<int16_t, N>{wasm_i16x8_narrow_i32x4(v.raw, v.raw)};
}

template <size_t N>
HWY_API Vec128<uint8_t, N> DemoteTo(Simd<uint8_t, N, 0> /* tag */,
                                    const Vec128<int32_t, N> v) {
  const auto intermediate = wasm_i16x8_narrow_i32x4(v.raw, v.raw);
  return Vec128<uint8_t, N>{
      wasm_u8x16_narrow_i16x8(intermediate, intermediate)};
}

template <size_t N>
HWY_API Vec128<uint8_t, N> DemoteTo(Simd<uint8_t, N, 0> /* tag */,
                                    const Vec128<int16_t, N> v) {
  return Vec128<uint8_t, N>{wasm_u8x16_narrow_i16x8(v.raw, v.raw)};
}

template <size_t N>
HWY_API Vec128<int8_t, N> DemoteTo(Simd<int8_t, N, 0> /* tag */,
                                   const Vec128<int32_t, N> v) {
  const auto intermediate = wasm_i16x8_narrow_i32x4(v.raw, v.raw);
  return Vec128<int8_t, N>{wasm_i8x16_narrow_i16x8(intermediate, intermediate)};
}

template <size_t N>
HWY_API Vec128<int8_t, N> DemoteTo(Simd<int8_t, N, 0> /* tag */,
                                   const Vec128<int16_t, N> v) {
  return Vec128<int8_t, N>{wasm_i8x16_narrow_i16x8(v.raw, v.raw)};
}

template <size_t N>
HWY_API Vec128<int32_t, N> DemoteTo(Simd<int32_t, N, 0> /* di */,
                                    const Vec128<double, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_trunc_sat_f64x2_zero(v.raw)};
}

template <size_t N>
HWY_API Vec128<float16_t, N> DemoteTo(Simd<float16_t, N, 0> df16,
                                      const Vec128<float, N> v) {
  const RebindToUnsigned<decltype(df16)> du16;
  const Rebind<uint32_t, decltype(du16)> du;
  const RebindToSigned<decltype(du)> di;
  const auto bits32 = BitCast(du, v);
  const auto sign = ShiftRight<31>(bits32);
  const auto biased_exp32 = ShiftRight<23>(bits32) & Set(du, 0xFF);
  const auto mantissa32 = bits32 & Set(du, 0x7FFFFF);

  const auto k15 = Set(di, 15);
  const auto exp = Min(BitCast(di, biased_exp32) - Set(di, 127), k15);
  const auto is_tiny = exp < Set(di, -24);

  const auto is_subnormal = exp < Set(di, -14);
  const auto biased_exp16 =
      BitCast(du, IfThenZeroElse(is_subnormal, exp + k15));
  const auto sub_exp = BitCast(du, Set(di, -14) - exp);  // [1, 11)
  const auto sub_m = (Set(du, 1) << (Set(du, 10) - sub_exp)) +
                     (mantissa32 >> (Set(du, 13) + sub_exp));
  const auto mantissa16 = IfThenElse(RebindMask(du, is_subnormal), sub_m,
                                     ShiftRight<13>(mantissa32));  // <1024

  const auto sign16 = ShiftLeft<15>(sign);
  const auto normal16 = sign16 | ShiftLeft<10>(biased_exp16) | mantissa16;
  const auto bits16 = IfThenZeroElse(is_tiny, BitCast(di, normal16));
  return Vec128<float16_t, N>{DemoteTo(du16, bits16).raw};
}

template <size_t N>
HWY_API Vec128<bfloat16_t, N> DemoteTo(Simd<bfloat16_t, N, 0> dbf16,
                                       const Vec128<float, N> v) {
  const Rebind<int32_t, decltype(dbf16)> di32;
  const Rebind<uint32_t, decltype(dbf16)> du32;  // for logical shift right
  const Rebind<uint16_t, decltype(dbf16)> du16;
  const auto bits_in_32 = BitCast(di32, ShiftRight<16>(BitCast(du32, v)));
  return BitCast(dbf16, DemoteTo(du16, bits_in_32));
}

template <size_t N>
HWY_API Vec128<bfloat16_t, 2 * N> ReorderDemote2To(
    Simd<bfloat16_t, 2 * N, 0> dbf16, Vec128<float, N> a, Vec128<float, N> b) {
  const RebindToUnsigned<decltype(dbf16)> du16;
  const Repartition<uint32_t, decltype(dbf16)> du32;
  const Vec128<uint32_t, N> b_in_even = ShiftRight<16>(BitCast(du32, b));
  return BitCast(dbf16, OddEven(BitCast(du16, a), BitCast(du16, b_in_even)));
}

// For already range-limited input [0, 255].
template <size_t N>
HWY_API Vec128<uint8_t, N> U8FromU32(const Vec128<uint32_t, N> v) {
  const auto intermediate = wasm_i16x8_narrow_i32x4(v.raw, v.raw);
  return Vec128<uint8_t, N>{
      wasm_u8x16_narrow_i16x8(intermediate, intermediate)};
}

// ------------------------------ Convert i32 <=> f32 (Round)

template <size_t N>
HWY_API Vec128<float, N> ConvertTo(Simd<float, N, 0> /* tag */,
                                   const Vec128<int32_t, N> v) {
  return Vec128<float, N>{wasm_f32x4_convert_i32x4(v.raw)};
}
// Truncates (rounds toward zero).
template <size_t N>
HWY_API Vec128<int32_t, N> ConvertTo(Simd<int32_t, N, 0> /* tag */,
                                     const Vec128<float, N> v) {
  return Vec128<int32_t, N>{wasm_i32x4_trunc_sat_f32x4(v.raw)};
}

template <size_t N>
HWY_API Vec128<int32_t, N> NearestInt(const Vec128<float, N> v) {
  return ConvertTo(Simd<int32_t, N, 0>(), Round(v));
}

// ================================================== MISC

// ------------------------------ SumsOf8 (ShiftRight, Add)
template <size_t N>
HWY_API Vec128<uint64_t, N / 8> SumsOf8(const Vec128<uint8_t, N> v) {
  const DFromV<decltype(v)> du8;
  const RepartitionToWide<decltype(du8)> du16;
  const RepartitionToWide<decltype(du16)> du32;
  const RepartitionToWide<decltype(du32)> du64;
  using VU16 = VFromD<decltype(du16)>;

  const VU16 vFDB97531 = ShiftRight<8>(BitCast(du16, v));
  const VU16 vECA86420 = And(BitCast(du16, v), Set(du16, 0xFF));
  const VU16 sFE_DC_BA_98_76_54_32_10 = Add(vFDB97531, vECA86420);

  const VU16 szz_FE_zz_BA_zz_76_zz_32 =
      BitCast(du16, ShiftRight<16>(BitCast(du32, sFE_DC_BA_98_76_54_32_10)));
  const VU16 sxx_FC_xx_B8_xx_74_xx_30 =
      Add(sFE_DC_BA_98_76_54_32_10, szz_FE_zz_BA_zz_76_zz_32);
  const VU16 szz_zz_xx_FC_zz_zz_xx_74 =
      BitCast(du16, ShiftRight<32>(BitCast(du64, sxx_FC_xx_B8_xx_74_xx_30)));
  const VU16 sxx_xx_xx_F8_xx_xx_xx_70 =
      Add(sxx_FC_xx_B8_xx_74_xx_30, szz_zz_xx_FC_zz_zz_xx_74);
  return And(BitCast(du64, sxx_xx_xx_F8_xx_xx_xx_70), Set(du64, 0xFFFF));
}

// ------------------------------ LoadMaskBits (TestBit)

namespace detail {

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 1)>
HWY_INLINE Mask128<T, N> LoadMaskBits(Simd<T, N, 0> d, uint64_t bits) {
  const RebindToUnsigned<decltype(d)> du;
  // Easier than Set(), which would require an >8-bit type, which would not
  // compile for T=uint8_t, N=1.
  const Vec128<T, N> vbits{wasm_i32x4_splat(static_cast<int32_t>(bits))};

  // Replicate bytes 8x such that each byte contains the bit that governs it.
  alignas(16) constexpr uint8_t kRep8[16] = {0, 0, 0, 0, 0, 0, 0, 0,
                                             1, 1, 1, 1, 1, 1, 1, 1};
  const auto rep8 = TableLookupBytes(vbits, Load(du, kRep8));

  alignas(16) constexpr uint8_t kBit[16] = {1, 2, 4, 8, 16, 32, 64, 128,
                                            1, 2, 4, 8, 16, 32, 64, 128};
  return RebindMask(d, TestBit(rep8, LoadDup128(du, kBit)));
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2)>
HWY_INLINE Mask128<T, N> LoadMaskBits(Simd<T, N, 0> d, uint64_t bits) {
  const RebindToUnsigned<decltype(d)> du;
  alignas(16) constexpr uint16_t kBit[8] = {1, 2, 4, 8, 16, 32, 64, 128};
  return RebindMask(
      d, TestBit(Set(du, static_cast<uint16_t>(bits)), Load(du, kBit)));
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 4)>
HWY_INLINE Mask128<T, N> LoadMaskBits(Simd<T, N, 0> d, uint64_t bits) {
  const RebindToUnsigned<decltype(d)> du;
  alignas(16) constexpr uint32_t kBit[8] = {1, 2, 4, 8};
  return RebindMask(
      d, TestBit(Set(du, static_cast<uint32_t>(bits)), Load(du, kBit)));
}

template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 8)>
HWY_INLINE Mask128<T, N> LoadMaskBits(Simd<T, N, 0> d, uint64_t bits) {
  const RebindToUnsigned<decltype(d)> du;
  alignas(16) constexpr uint64_t kBit[8] = {1, 2};
  return RebindMask(d, TestBit(Set(du, bits), Load(du, kBit)));
}

}  // namespace detail

// `p` points to at least 8 readable bytes, not all of which need be valid.
template <typename T, size_t N, HWY_IF_LE128(T, N)>
HWY_API Mask128<T, N> LoadMaskBits(Simd<T, N, 0> d,
                                   const uint8_t* HWY_RESTRICT bits) {
  uint64_t mask_bits = 0;
  CopyBytes<(N + 7) / 8>(bits, &mask_bits);
  return detail::LoadMaskBits(d, mask_bits);
}

// ------------------------------ Mask

namespace detail {

// Full
template <typename T>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<1> /*tag*/,
                                 const Mask128<T> mask) {
  alignas(16) uint64_t lanes[2];
  wasm_v128_store(lanes, mask.raw);

  constexpr uint64_t kMagic = 0x103070F1F3F80ULL;
  const uint64_t lo = ((lanes[0] * kMagic) >> 56);
  const uint64_t hi = ((lanes[1] * kMagic) >> 48) & 0xFF00;
  return (hi + lo);
}

// 64-bit
template <typename T>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<1> /*tag*/,
                                 const Mask128<T, 8> mask) {
  constexpr uint64_t kMagic = 0x103070F1F3F80ULL;
  return (static_cast<uint64_t>(wasm_i64x2_extract_lane(mask.raw, 0)) *
          kMagic) >>
         56;
}

// 32-bit or less: need masking
template <typename T, size_t N, HWY_IF_LE32(T, N)>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<1> /*tag*/,
                                 const Mask128<T, N> mask) {
  uint64_t bytes = static_cast<uint64_t>(wasm_i64x2_extract_lane(mask.raw, 0));
  // Clear potentially undefined bytes.
  bytes &= (1ULL << (N * 8)) - 1;
  constexpr uint64_t kMagic = 0x103070F1F3F80ULL;
  return (bytes * kMagic) >> 56;
}

template <typename T, size_t N>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<2> /*tag*/,
                                 const Mask128<T, N> mask) {
  // Remove useless lower half of each u16 while preserving the sign bit.
  const __i16x8 zero = wasm_i16x8_splat(0);
  const Mask128<uint8_t, N> mask8{wasm_i8x16_narrow_i16x8(mask.raw, zero)};
  return BitsFromMask(hwy::SizeTag<1>(), mask8);
}

template <typename T, size_t N>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<4> /*tag*/,
                                 const Mask128<T, N> mask) {
  const __i32x4 mask_i = static_cast<__i32x4>(mask.raw);
  const __i32x4 slice = wasm_i32x4_make(1, 2, 4, 8);
  const __i32x4 sliced_mask = wasm_v128_and(mask_i, slice);
  alignas(16) uint32_t lanes[4];
  wasm_v128_store(lanes, sliced_mask);
  return lanes[0] | lanes[1] | lanes[2] | lanes[3];
}

template <typename T, size_t N>
HWY_INLINE uint64_t BitsFromMask(hwy::SizeTag<8> /*tag*/,
                                 const Mask128<T, N> mask) {
  const __i64x2 mask_i = static_cast<__i64x2>(mask.raw);
  const __i64x2 slice = wasm_i64x2_make(1, 2);
  const __i64x2 sliced_mask = wasm_v128_and(mask_i, slice);
  alignas(16) uint64_t lanes[2];
  wasm_v128_store(lanes, sliced_mask);
  return lanes[0] | lanes[1];
}

// Returns the lowest N bits for the BitsFromMask result.
template <typename T, size_t N>
constexpr uint64_t OnlyActive(uint64_t bits) {
  return ((N * sizeof(T)) == 16) ? bits : bits & ((1ull << N) - 1);
}

// Returns 0xFF for bytes with index >= N, otherwise 0.
template <size_t N>
constexpr __i8x16 BytesAbove() {
  return /**/
      (N == 0)    ? wasm_i32x4_make(-1, -1, -1, -1)
      : (N == 4)  ? wasm_i32x4_make(0, -1, -1, -1)
      : (N == 8)  ? wasm_i32x4_make(0, 0, -1, -1)
      : (N == 12) ? wasm_i32x4_make(0, 0, 0, -1)
      : (N == 16) ? wasm_i32x4_make(0, 0, 0, 0)
      : (N == 2)  ? wasm_i16x8_make(0, -1, -1, -1, -1, -1, -1, -1)
      : (N == 6)  ? wasm_i16x8_make(0, 0, 0, -1, -1, -1, -1, -1)
      : (N == 10) ? wasm_i16x8_make(0, 0, 0, 0, 0, -1, -1, -1)
      : (N == 14) ? wasm_i16x8_make(0, 0, 0, 0, 0, 0, 0, -1)
      : (N == 1)  ? wasm_i8x16_make(0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                                   -1, -1, -1, -1, -1)
      : (N == 3)  ? wasm_i8x16_make(0, 0, 0, -1, -1, -1, -1, -1, -1, -1, -1, -1,
                                   -1, -1, -1, -1)
      : (N == 5)  ? wasm_i8x16_make(0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -1, -1,
                                   -1, -1, -1, -1)
      : (N == 7)  ? wasm_i8x16_make(0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1, -1,
                                   -1, -1, -1)
      : (N == 9)  ? wasm_i8x16_make(0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1,
                                   -1, -1, -1)
      : (N == 11)
          ? wasm_i8x16_make(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1, -1, -1)
      : (N == 13)
          ? wasm_i8x16_make(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1, -1, -1)
          : wasm_i8x16_make(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, -1);
}

template <typename T, size_t N>
HWY_INLINE uint64_t BitsFromMask(const Mask128<T, N> mask) {
  return OnlyActive<T, N>(BitsFromMask(hwy::SizeTag<sizeof(T)>(), mask));
}

template <typename T>
HWY_INLINE size_t CountTrue(hwy::SizeTag<1> tag, const Mask128<T> m) {
  return PopCount(BitsFromMask(tag, m));
}

template <typename T>
HWY_INLINE size_t CountTrue(hwy::SizeTag<2> tag, const Mask128<T> m) {
  return PopCount(BitsFromMask(tag, m));
}

template <typename T>
HWY_INLINE size_t CountTrue(hwy::SizeTag<4> /*tag*/, const Mask128<T> m) {
  const __i32x4 var_shift = wasm_i32x4_make(1, 2, 4, 8);
  const __i32x4 shifted_bits = wasm_v128_and(m.raw, var_shift);
  alignas(16) uint64_t lanes[2];
  wasm_v128_store(lanes, shifted_bits);
  return PopCount(lanes[0] | lanes[1]);
}

template <typename T>
HWY_INLINE size_t CountTrue(hwy::SizeTag<8> /*tag*/, const Mask128<T> m) {
  alignas(16) int64_t lanes[2];
  wasm_v128_store(lanes, m.raw);
  return static_cast<size_t>(-(lanes[0] + lanes[1]));
}

}  // namespace detail

// `p` points to at least 8 writable bytes.
template <typename T, size_t N>
HWY_API size_t StoreMaskBits(const Simd<T, N, 0> /* tag */,
                             const Mask128<T, N> mask, uint8_t* bits) {
  const uint64_t mask_bits = detail::BitsFromMask(mask);
  const size_t kNumBytes = (N + 7) / 8;
  CopyBytes<kNumBytes>(&mask_bits, bits);
  return kNumBytes;
}

template <typename T, size_t N>
HWY_API size_t CountTrue(const Simd<T, N, 0> /* tag */, const Mask128<T> m) {
  return detail::CountTrue(hwy::SizeTag<sizeof(T)>(), m);
}

// Partial vector
template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API size_t CountTrue(const Simd<T, N, 0> d, const Mask128<T, N> m) {
  // Ensure all undefined bytes are 0.
  const Mask128<T, N> mask{detail::BytesAbove<N * sizeof(T)>()};
  return CountTrue(d, Mask128<T>{AndNot(mask, m).raw});
}

// Full vector
template <typename T>
HWY_API bool AllFalse(const Full128<T> d, const Mask128<T> m) {
#if 0
  // Casting followed by wasm_i8x16_any_true results in wasm error:
  // i32.eqz[0] expected type i32, found i8x16.popcnt of type s128
  const auto v8 = BitCast(Full128<int8_t>(), VecFromMask(d, m));
  return !wasm_i8x16_any_true(v8.raw);
#else
  (void)d;
  return (wasm_i64x2_extract_lane(m.raw, 0) |
          wasm_i64x2_extract_lane(m.raw, 1)) == 0;
#endif
}

// Full vector
namespace detail {
template <typename T>
HWY_INLINE bool AllTrue(hwy::SizeTag<1> /*tag*/, const Mask128<T> m) {
  return wasm_i8x16_all_true(m.raw);
}
template <typename T>
HWY_INLINE bool AllTrue(hwy::SizeTag<2> /*tag*/, const Mask128<T> m) {
  return wasm_i16x8_all_true(m.raw);
}
template <typename T>
HWY_INLINE bool AllTrue(hwy::SizeTag<4> /*tag*/, const Mask128<T> m) {
  return wasm_i32x4_all_true(m.raw);
}
template <typename T>
HWY_INLINE bool AllTrue(hwy::SizeTag<8> /*tag*/, const Mask128<T> m) {
  return wasm_i64x2_all_true(m.raw);
}

}  // namespace detail

template <typename T, size_t N>
HWY_API bool AllTrue(const Simd<T, N, 0> /* tag */, const Mask128<T> m) {
  return detail::AllTrue(hwy::SizeTag<sizeof(T)>(), m);
}

// Partial vectors

template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API bool AllFalse(Simd<T, N, 0> /* tag */, const Mask128<T, N> m) {
  // Ensure all undefined bytes are 0.
  const Mask128<T, N> mask{detail::BytesAbove<N * sizeof(T)>()};
  return AllFalse(Full128<T>(), Mask128<T>{AndNot(mask, m).raw});
}

template <typename T, size_t N, HWY_IF_LE64(T, N)>
HWY_API bool AllTrue(const Simd<T, N, 0> /* d */, const Mask128<T, N> m) {
  // Ensure all undefined bytes are FF.
  const Mask128<T, N> mask{detail::BytesAbove<N * sizeof(T)>()};
  return AllTrue(Full128<T>(), Mask128<T>{Or(mask, m).raw});
}

template <typename T, size_t N>
HWY_API intptr_t FindFirstTrue(const Simd<T, N, 0> /* tag */,
                               const Mask128<T, N> mask) {
  const uint64_t bits = detail::BitsFromMask(mask);
  return bits ? static_cast<intptr_t>(Num0BitsBelowLS1Bit_Nonzero64(bits)) : -1;
}

// ------------------------------ Compress

namespace detail {

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Idx16x8FromBits(const uint64_t mask_bits) {
  HWY_DASSERT(mask_bits < 256);
  const Simd<T, N, 0> d;
  const Rebind<uint8_t, decltype(d)> d8;
  const Simd<uint16_t, N, 0> du;

  // We need byte indices for TableLookupBytes (one vector's worth for each of
  // 256 combinations of 8 mask bits). Loading them directly requires 4 KiB. We
  // can instead store lane indices and convert to byte indices (2*lane + 0..1),
  // with the doubling baked into the table. Unpacking nibbles is likely more
  // costly than the higher cache footprint from storing bytes.
  alignas(16) constexpr uint8_t table[256 * 8] = {
      0,  2,  4,  6,  8,  10, 12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      2,  0,  4,  6,  8,  10, 12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      4,  0,  2,  6,  8,  10, 12, 14, /**/ 0, 4,  2,  6,  8,  10, 12, 14,  //
      2,  4,  0,  6,  8,  10, 12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      6,  0,  2,  4,  8,  10, 12, 14, /**/ 0, 6,  2,  4,  8,  10, 12, 14,  //
      2,  6,  0,  4,  8,  10, 12, 14, /**/ 0, 2,  6,  4,  8,  10, 12, 14,  //
      4,  6,  0,  2,  8,  10, 12, 14, /**/ 0, 4,  6,  2,  8,  10, 12, 14,  //
      2,  4,  6,  0,  8,  10, 12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      8,  0,  2,  4,  6,  10, 12, 14, /**/ 0, 8,  2,  4,  6,  10, 12, 14,  //
      2,  8,  0,  4,  6,  10, 12, 14, /**/ 0, 2,  8,  4,  6,  10, 12, 14,  //
      4,  8,  0,  2,  6,  10, 12, 14, /**/ 0, 4,  8,  2,  6,  10, 12, 14,  //
      2,  4,  8,  0,  6,  10, 12, 14, /**/ 0, 2,  4,  8,  6,  10, 12, 14,  //
      6,  8,  0,  2,  4,  10, 12, 14, /**/ 0, 6,  8,  2,  4,  10, 12, 14,  //
      2,  6,  8,  0,  4,  10, 12, 14, /**/ 0, 2,  6,  8,  4,  10, 12, 14,  //
      4,  6,  8,  0,  2,  10, 12, 14, /**/ 0, 4,  6,  8,  2,  10, 12, 14,  //
      2,  4,  6,  8,  0,  10, 12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      10, 0,  2,  4,  6,  8,  12, 14, /**/ 0, 10, 2,  4,  6,  8,  12, 14,  //
      2,  10, 0,  4,  6,  8,  12, 14, /**/ 0, 2,  10, 4,  6,  8,  12, 14,  //
      4,  10, 0,  2,  6,  8,  12, 14, /**/ 0, 4,  10, 2,  6,  8,  12, 14,  //
      2,  4,  10, 0,  6,  8,  12, 14, /**/ 0, 2,  4,  10, 6,  8,  12, 14,  //
      6,  10, 0,  2,  4,  8,  12, 14, /**/ 0, 6,  10, 2,  4,  8,  12, 14,  //
      2,  6,  10, 0,  4,  8,  12, 14, /**/ 0, 2,  6,  10, 4,  8,  12, 14,  //
      4,  6,  10, 0,  2,  8,  12, 14, /**/ 0, 4,  6,  10, 2,  8,  12, 14,  //
      2,  4,  6,  10, 0,  8,  12, 14, /**/ 0, 2,  4,  6,  10, 8,  12, 14,  //
      8,  10, 0,  2,  4,  6,  12, 14, /**/ 0, 8,  10, 2,  4,  6,  12, 14,  //
      2,  8,  10, 0,  4,  6,  12, 14, /**/ 0, 2,  8,  10, 4,  6,  12, 14,  //
      4,  8,  10, 0,  2,  6,  12, 14, /**/ 0, 4,  8,  10, 2,  6,  12, 14,  //
      2,  4,  8,  10, 0,  6,  12, 14, /**/ 0, 2,  4,  8,  10, 6,  12, 14,  //
      6,  8,  10, 0,  2,  4,  12, 14, /**/ 0, 6,  8,  10, 2,  4,  12, 14,  //
      2,  6,  8,  10, 0,  4,  12, 14, /**/ 0, 2,  6,  8,  10, 4,  12, 14,  //
      4,  6,  8,  10, 0,  2,  12, 14, /**/ 0, 4,  6,  8,  10, 2,  12, 14,  //
      2,  4,  6,  8,  10, 0,  12, 14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      12, 0,  2,  4,  6,  8,  10, 14, /**/ 0, 12, 2,  4,  6,  8,  10, 14,  //
      2,  12, 0,  4,  6,  8,  10, 14, /**/ 0, 2,  12, 4,  6,  8,  10, 14,  //
      4,  12, 0,  2,  6,  8,  10, 14, /**/ 0, 4,  12, 2,  6,  8,  10, 14,  //
      2,  4,  12, 0,  6,  8,  10, 14, /**/ 0, 2,  4,  12, 6,  8,  10, 14,  //
      6,  12, 0,  2,  4,  8,  10, 14, /**/ 0, 6,  12, 2,  4,  8,  10, 14,  //
      2,  6,  12, 0,  4,  8,  10, 14, /**/ 0, 2,  6,  12, 4,  8,  10, 14,  //
      4,  6,  12, 0,  2,  8,  10, 14, /**/ 0, 4,  6,  12, 2,  8,  10, 14,  //
      2,  4,  6,  12, 0,  8,  10, 14, /**/ 0, 2,  4,  6,  12, 8,  10, 14,  //
      8,  12, 0,  2,  4,  6,  10, 14, /**/ 0, 8,  12, 2,  4,  6,  10, 14,  //
      2,  8,  12, 0,  4,  6,  10, 14, /**/ 0, 2,  8,  12, 4,  6,  10, 14,  //
      4,  8,  12, 0,  2,  6,  10, 14, /**/ 0, 4,  8,  12, 2,  6,  10, 14,  //
      2,  4,  8,  12, 0,  6,  10, 14, /**/ 0, 2,  4,  8,  12, 6,  10, 14,  //
      6,  8,  12, 0,  2,  4,  10, 14, /**/ 0, 6,  8,  12, 2,  4,  10, 14,  //
      2,  6,  8,  12, 0,  4,  10, 14, /**/ 0, 2,  6,  8,  12, 4,  10, 14,  //
      4,  6,  8,  12, 0,  2,  10, 14, /**/ 0, 4,  6,  8,  12, 2,  10, 14,  //
      2,  4,  6,  8,  12, 0,  10, 14, /**/ 0, 2,  4,  6,  8,  12, 10, 14,  //
      10, 12, 0,  2,  4,  6,  8,  14, /**/ 0, 10, 12, 2,  4,  6,  8,  14,  //
      2,  10, 12, 0,  4,  6,  8,  14, /**/ 0, 2,  10, 12, 4,  6,  8,  14,  //
      4,  10, 12, 0,  2,  6,  8,  14, /**/ 0, 4,  10, 12, 2,  6,  8,  14,  //
      2,  4,  10, 12, 0,  6,  8,  14, /**/ 0, 2,  4,  10, 12, 6,  8,  14,  //
      6,  10, 12, 0,  2,  4,  8,  14, /**/ 0, 6,  10, 12, 2,  4,  8,  14,  //
      2,  6,  10, 12, 0,  4,  8,  14, /**/ 0, 2,  6,  10, 12, 4,  8,  14,  //
      4,  6,  10, 12, 0,  2,  8,  14, /**/ 0, 4,  6,  10, 12, 2,  8,  14,  //
      2,  4,  6,  10, 12, 0,  8,  14, /**/ 0, 2,  4,  6,  10, 12, 8,  14,  //
      8,  10, 12, 0,  2,  4,  6,  14, /**/ 0, 8,  10, 12, 2,  4,  6,  14,  //
      2,  8,  10, 12, 0,  4,  6,  14, /**/ 0, 2,  8,  10, 12, 4,  6,  14,  //
      4,  8,  10, 12, 0,  2,  6,  14, /**/ 0, 4,  8,  10, 12, 2,  6,  14,  //
      2,  4,  8,  10, 12, 0,  6,  14, /**/ 0, 2,  4,  8,  10, 12, 6,  14,  //
      6,  8,  10, 12, 0,  2,  4,  14, /**/ 0, 6,  8,  10, 12, 2,  4,  14,  //
      2,  6,  8,  10, 12, 0,  4,  14, /**/ 0, 2,  6,  8,  10, 12, 4,  14,  //
      4,  6,  8,  10, 12, 0,  2,  14, /**/ 0, 4,  6,  8,  10, 12, 2,  14,  //
      2,  4,  6,  8,  10, 12, 0,  14, /**/ 0, 2,  4,  6,  8,  10, 12, 14,  //
      14, 0,  2,  4,  6,  8,  10, 12, /**/ 0, 14, 2,  4,  6,  8,  10, 12,  //
      2,  14, 0,  4,  6,  8,  10, 12, /**/ 0, 2,  14, 4,  6,  8,  10, 12,  //
      4,  14, 0,  2,  6,  8,  10, 12, /**/ 0, 4,  14, 2,  6,  8,  10, 12,  //
      2,  4,  14, 0,  6,  8,  10, 12, /**/ 0, 2,  4,  14, 6,  8,  10, 12,  //
      6,  14, 0,  2,  4,  8,  10, 12, /**/ 0, 6,  14, 2,  4,  8,  10, 12,  //
      2,  6,  14, 0,  4,  8,  10, 12, /**/ 0, 2,  6,  14, 4,  8,  10, 12,  //
      4,  6,  14, 0,  2,  8,  10, 12, /**/ 0, 4,  6,  14, 2,  8,  10, 12,  //
      2,  4,  6,  14, 0,  8,  10, 12, /**/ 0, 2,  4,  6,  14, 8,  10, 12,  //
      8,  14, 0,  2,  4,  6,  10, 12, /**/ 0, 8,  14, 2,  4,  6,  10, 12,  //
      2,  8,  14, 0,  4,  6,  10, 12, /**/ 0, 2,  8,  14, 4,  6,  10, 12,  //
      4,  8,  14, 0,  2,  6,  10, 12, /**/ 0, 4,  8,  14, 2,  6,  10, 12,  //
      2,  4,  8,  14, 0,  6,  10, 12, /**/ 0, 2,  4,  8,  14, 6,  10, 12,  //
      6,  8,  14, 0,  2,  4,  10, 12, /**/ 0, 6,  8,  14, 2,  4,  10, 12,  //
      2,  6,  8,  14, 0,  4,  10, 12, /**/ 0, 2,  6,  8,  14, 4,  10, 12,  //
      4,  6,  8,  14, 0,  2,  10, 12, /**/ 0, 4,  6,  8,  14, 2,  10, 12,  //
      2,  4,  6,  8,  14, 0,  10, 12, /**/ 0, 2,  4,  6,  8,  14, 10, 12,  //
      10, 14, 0,  2,  4,  6,  8,  12, /**/ 0, 10, 14, 2,  4,  6,  8,  12,  //
      2,  10, 14, 0,  4,  6,  8,  12, /**/ 0, 2,  10, 14, 4,  6,  8,  12,  //
      4,  10, 14, 0,  2,  6,  8,  12, /**/ 0, 4,  10, 14, 2,  6,  8,  12,  //
      2,  4,  10, 14, 0,  6,  8,  12, /**/ 0, 2,  4,  10, 14, 6,  8,  12,  //
      6,  10, 14, 0,  2,  4,  8,  12, /**/ 0, 6,  10, 14, 2,  4,  8,  12,  //
      2,  6,  10, 14, 0,  4,  8,  12, /**/ 0, 2,  6,  10, 14, 4,  8,  12,  //
      4,  6,  10, 14, 0,  2,  8,  12, /**/ 0, 4,  6,  10, 14, 2,  8,  12,  //
      2,  4,  6,  10, 14, 0,  8,  12, /**/ 0, 2,  4,  6,  10, 14, 8,  12,  //
      8,  10, 14, 0,  2,  4,  6,  12, /**/ 0, 8,  10, 14, 2,  4,  6,  12,  //
      2,  8,  10, 14, 0,  4,  6,  12, /**/ 0, 2,  8,  10, 14, 4,  6,  12,  //
      4,  8,  10, 14, 0,  2,  6,  12, /**/ 0, 4,  8,  10, 14, 2,  6,  12,  //
      2,  4,  8,  10, 14, 0,  6,  12, /**/ 0, 2,  4,  8,  10, 14, 6,  12,  //
      6,  8,  10, 14, 0,  2,  4,  12, /**/ 0, 6,  8,  10, 14, 2,  4,  12,  //
      2,  6,  8,  10, 14, 0,  4,  12, /**/ 0, 2,  6,  8,  10, 14, 4,  12,  //
      4,  6,  8,  10, 14, 0,  2,  12, /**/ 0, 4,  6,  8,  10, 14, 2,  12,  //
      2,  4,  6,  8,  10, 14, 0,  12, /**/ 0, 2,  4,  6,  8,  10, 14, 12,  //
      12, 14, 0,  2,  4,  6,  8,  10, /**/ 0, 12, 14, 2,  4,  6,  8,  10,  //
      2,  12, 14, 0,  4,  6,  8,  10, /**/ 0, 2,  12, 14, 4,  6,  8,  10,  //
      4,  12, 14, 0,  2,  6,  8,  10, /**/ 0, 4,  12, 14, 2,  6,  8,  10,  //
      2,  4,  12, 14, 0,  6,  8,  10, /**/ 0, 2,  4,  12, 14, 6,  8,  10,  //
      6,  12, 14, 0,  2,  4,  8,  10, /**/ 0, 6,  12, 14, 2,  4,  8,  10,  //
      2,  6,  12, 14, 0,  4,  8,  10, /**/ 0, 2,  6,  12, 14, 4,  8,  10,  //
      4,  6,  12, 14, 0,  2,  8,  10, /**/ 0, 4,  6,  12, 14, 2,  8,  10,  //
      2,  4,  6,  12, 14, 0,  8,  10, /**/ 0, 2,  4,  6,  12, 14, 8,  10,  //
      8,  12, 14, 0,  2,  4,  6,  10, /**/ 0, 8,  12, 14, 2,  4,  6,  10,  //
      2,  8,  12, 14, 0,  4,  6,  10, /**/ 0, 2,  8,  12, 14, 4,  6,  10,  //
      4,  8,  12, 14, 0,  2,  6,  10, /**/ 0, 4,  8,  12, 14, 2,  6,  10,  //
      2,  4,  8,  12, 14, 0,  6,  10, /**/ 0, 2,  4,  8,  12, 14, 6,  10,  //
      6,  8,  12, 14, 0,  2,  4,  10, /**/ 0, 6,  8,  12, 14, 2,  4,  10,  //
      2,  6,  8,  12, 14, 0,  4,  10, /**/ 0, 2,  6,  8,  12, 14, 4,  10,  //
      4,  6,  8,  12, 14, 0,  2,  10, /**/ 0, 4,  6,  8,  12, 14, 2,  10,  //
      2,  4,  6,  8,  12, 14, 0,  10, /**/ 0, 2,  4,  6,  8,  12, 14, 10,  //
      10, 12, 14, 0,  2,  4,  6,  8,  /**/ 0, 10, 12, 14, 2,  4,  6,  8,   //
      2,  10, 12, 14, 0,  4,  6,  8,  /**/ 0, 2,  10, 12, 14, 4,  6,  8,   //
      4,  10, 12, 14, 0,  2,  6,  8,  /**/ 0, 4,  10, 12, 14, 2,  6,  8,   //
      2,  4,  10, 12, 14, 0,  6,  8,  /**/ 0, 2,  4,  10, 12, 14, 6,  8,   //
      6,  10, 12, 14, 0,  2,  4,  8,  /**/ 0, 6,  10, 12, 14, 2,  4,  8,   //
      2,  6,  10, 12, 14, 0,  4,  8,  /**/ 0, 2,  6,  10, 12, 14, 4,  8,   //
      4,  6,  10, 12, 14, 0,  2,  8,  /**/ 0, 4,  6,  10, 12, 14, 2,  8,   //
      2,  4,  6,  10, 12, 14, 0,  8,  /**/ 0, 2,  4,  6,  10, 12, 14, 8,   //
      8,  10, 12, 14, 0,  2,  4,  6,  /**/ 0, 8,  10, 12, 14, 2,  4,  6,   //
      2,  8,  10, 12, 14, 0,  4,  6,  /**/ 0, 2,  8,  10, 12, 14, 4,  6,   //
      4,  8,  10, 12, 14, 0,  2,  6,  /**/ 0, 4,  8,  10, 12, 14, 2,  6,   //
      2,  4,  8,  10, 12, 14, 0,  6,  /**/ 0, 2,  4,  8,  10, 12, 14, 6,   //
      6,  8,  10, 12, 14, 0,  2,  4,  /**/ 0, 6,  8,  10, 12, 14, 2,  4,   //
      2,  6,  8,  10, 12, 14, 0,  4,  /**/ 0, 2,  6,  8,  10, 12, 14, 4,   //
      4,  6,  8,  10, 12, 14, 0,  2,  /**/ 0, 4,  6,  8,  10, 12, 14, 2,   //
      2,  4,  6,  8,  10, 12, 14, 0,  /**/ 0, 2,  4,  6,  8,  10, 12, 14};

  const Vec128<uint8_t, 2 * N> byte_idx{Load(d8, table + mask_bits * 8).raw};
  const Vec128<uint16_t, N> pairs = ZipLower(byte_idx, byte_idx);
  return BitCast(d, pairs + Set(du, 0x0100));
}

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Idx32x4FromBits(const uint64_t mask_bits) {
  HWY_DASSERT(mask_bits < 16);

  // There are only 4 lanes, so we can afford to load the index vector directly.
  alignas(16) constexpr uint8_t packed_array[16 * 16] = {
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,  //
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,  //
      4,  5,  6,  7,  0,  1,  2,  3,  8,  9,  10, 11, 12, 13, 14, 15,  //
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,  //
      8,  9,  10, 11, 0,  1,  2,  3,  4,  5,  6,  7,  12, 13, 14, 15,  //
      0,  1,  2,  3,  8,  9,  10, 11, 4,  5,  6,  7,  12, 13, 14, 15,  //
      4,  5,  6,  7,  8,  9,  10, 11, 0,  1,  2,  3,  12, 13, 14, 15,  //
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15,  //
      12, 13, 14, 15, 0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11,  //
      0,  1,  2,  3,  12, 13, 14, 15, 4,  5,  6,  7,  8,  9,  10, 11,  //
      4,  5,  6,  7,  12, 13, 14, 15, 0,  1,  2,  3,  8,  9,  10, 11,  //
      0,  1,  2,  3,  4,  5,  6,  7,  12, 13, 14, 15, 8,  9,  10, 11,  //
      8,  9,  10, 11, 12, 13, 14, 15, 0,  1,  2,  3,  4,  5,  6,  7,   //
      0,  1,  2,  3,  8,  9,  10, 11, 12, 13, 14, 15, 4,  5,  6,  7,   //
      4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15, 0,  1,  2,  3,   //
      0,  1,  2,  3,  4,  5,  6,  7,  8,  9,  10, 11, 12, 13, 14, 15};
  const Simd<T, N, 0> d;
  const Repartition<uint8_t, decltype(d)> d8;
  return BitCast(d, Load(d8, packed_array + 16 * mask_bits));
}

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Idx64x2FromBits(const uint64_t mask_bits) {
  HWY_DASSERT(mask_bits < 4);

  // There are only 2 lanes, so we can afford to load the index vector directly.
  alignas(16) constexpr uint8_t packed_array[4 * 16] = {
      0, 1, 2,  3,  4,  5,  6,  7,  8, 9, 10, 11, 12, 13, 14, 15,
      0, 1, 2,  3,  4,  5,  6,  7,  8, 9, 10, 11, 12, 13, 14, 15,
      8, 9, 10, 11, 12, 13, 14, 15, 0, 1, 2,  3,  4,  5,  6,  7,
      0, 1, 2,  3,  4,  5,  6,  7,  8, 9, 10, 11, 12, 13, 14, 15};

  const Simd<T, N, 0> d;
  const Repartition<uint8_t, decltype(d)> d8;
  return BitCast(d, Load(d8, packed_array + 16 * mask_bits));
}

// Helper functions called by both Compress and CompressStore - avoids a
// redundant BitsFromMask in the latter.

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Compress(hwy::SizeTag<2> /*tag*/, Vec128<T, N> v,
                                 const uint64_t mask_bits) {
  const auto idx = detail::Idx16x8FromBits<T, N>(mask_bits);
  const DFromV<decltype(v)> d;
  const RebindToSigned<decltype(d)> di;
  return BitCast(d, TableLookupBytes(BitCast(di, v), BitCast(di, idx)));
}

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Compress(hwy::SizeTag<4> /*tag*/, Vec128<T, N> v,
                                 const uint64_t mask_bits) {
  const auto idx = detail::Idx32x4FromBits<T, N>(mask_bits);
  const DFromV<decltype(v)> d;
  const RebindToSigned<decltype(d)> di;
  return BitCast(d, TableLookupBytes(BitCast(di, v), BitCast(di, idx)));
}

template <typename T, size_t N>
HWY_INLINE Vec128<T, N> Compress(hwy::SizeTag<8> /*tag*/, Vec128<T, N> v,
                                 const uint64_t mask_bits) {
  const auto idx = detail::Idx64x2FromBits<T, N>(mask_bits);
  const DFromV<decltype(v)> d;
  const RebindToSigned<decltype(d)> di;
  return BitCast(d, TableLookupBytes(BitCast(di, v), BitCast(di, idx)));
}

}  // namespace detail

template <typename T>
struct CompressIsPartition {
  enum { value = 1 };
};

template <typename T, size_t N>
HWY_API Vec128<T, N> Compress(Vec128<T, N> v, const Mask128<T, N> mask) {
  const uint64_t mask_bits = detail::BitsFromMask(mask);
  return detail::Compress(hwy::SizeTag<sizeof(T)>(), v, mask_bits);
}

// ------------------------------ CompressBits

template <typename T, size_t N>
HWY_API Vec128<T, N> CompressBits(Vec128<T, N> v,
                                  const uint8_t* HWY_RESTRICT bits) {
  uint64_t mask_bits = 0;
  constexpr size_t kNumBytes = (N + 7) / 8;
  CopyBytes<kNumBytes>(bits, &mask_bits);
  if (N < 8) {
    mask_bits &= (1ull << N) - 1;
  }

  return detail::Compress(hwy::SizeTag<sizeof(T)>(), v, mask_bits);
}

// ------------------------------ CompressStore
template <typename T, size_t N>
HWY_API size_t CompressStore(Vec128<T, N> v, const Mask128<T, N> mask,
                             Simd<T, N, 0> d, T* HWY_RESTRICT unaligned) {
  const uint64_t mask_bits = detail::BitsFromMask(mask);
  const auto c = detail::Compress(hwy::SizeTag<sizeof(T)>(), v, mask_bits);
  StoreU(c, d, unaligned);
  return PopCount(mask_bits);
}

// ------------------------------ CompressBlendedStore
template <typename T, size_t N>
HWY_API size_t CompressBlendedStore(Vec128<T, N> v, Mask128<T, N> m,
                                    Simd<T, N, 0> d,
                                    T* HWY_RESTRICT unaligned) {
  const RebindToUnsigned<decltype(d)> du;  // so we can support fp16/bf16
  using TU = TFromD<decltype(du)>;
  const uint64_t mask_bits = detail::BitsFromMask(m);
  const size_t count = PopCount(mask_bits);
  const Vec128<TU, N> compressed =
      detail::Compress(hwy::SizeTag<sizeof(T)>(), BitCast(du, v), mask_bits);
  const Mask128<T, N> store_mask = RebindMask(d, FirstN(du, count));
  BlendedStore(BitCast(d, compressed), store_mask, d, unaligned);
  return count;
}

// ------------------------------ CompressBitsStore

template <typename T, size_t N>
HWY_API size_t CompressBitsStore(Vec128<T, N> v,
                                 const uint8_t* HWY_RESTRICT bits,
                                 Simd<T, N, 0> d, T* HWY_RESTRICT unaligned) {
  uint64_t mask_bits = 0;
  constexpr size_t kNumBytes = (N + 7) / 8;
  CopyBytes<kNumBytes>(bits, &mask_bits);
  if (N < 8) {
    mask_bits &= (1ull << N) - 1;
  }

  const auto c = detail::Compress(hwy::SizeTag<sizeof(T)>(), v, mask_bits);
  StoreU(c, d, unaligned);
  return PopCount(mask_bits);
}

// ------------------------------ StoreInterleaved2/3/4

// HWY_NATIVE_LOAD_STORE_INTERLEAVED not set, hence defined in
// generic_ops-inl.h.

// ------------------------------ MulEven/Odd (Load)

HWY_INLINE Vec128<uint64_t> MulEven(const Vec128<uint64_t> a,
                                    const Vec128<uint64_t> b) {
  alignas(16) uint64_t mul[2];
  mul[0] =
      Mul128(static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 0)),
             static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 0)), &mul[1]);
  return Load(Full128<uint64_t>(), mul);
}

HWY_INLINE Vec128<uint64_t> MulOdd(const Vec128<uint64_t> a,
                                   const Vec128<uint64_t> b) {
  alignas(16) uint64_t mul[2];
  mul[0] =
      Mul128(static_cast<uint64_t>(wasm_i64x2_extract_lane(a.raw, 1)),
             static_cast<uint64_t>(wasm_i64x2_extract_lane(b.raw, 1)), &mul[1]);
  return Load(Full128<uint64_t>(), mul);
}

// ------------------------------ ReorderWidenMulAccumulate (MulAdd, ZipLower)

template <size_t N>
HWY_API Vec128<float, N> ReorderWidenMulAccumulate(Simd<float, N, 0> df32,
                                                   Vec128<bfloat16_t, 2 * N> a,
                                                   Vec128<bfloat16_t, 2 * N> b,
                                                   const Vec128<float, N> sum0,
                                                   Vec128<float, N>& sum1) {
  const Repartition<uint16_t, decltype(df32)> du16;
  const RebindToUnsigned<decltype(df32)> du32;
  const Vec128<uint16_t, 2 * N> zero = Zero(du16);
  const Vec128<uint32_t, N> a0 = ZipLower(du32, zero, BitCast(du16, a));
  const Vec128<uint32_t, N> a1 = ZipUpper(du32, zero, BitCast(du16, a));
  const Vec128<uint32_t, N> b0 = ZipLower(du32, zero, BitCast(du16, b));
  const Vec128<uint32_t, N> b1 = ZipUpper(du32, zero, BitCast(du16, b));
  sum1 = MulAdd(BitCast(df32, a1), BitCast(df32, b1), sum1);
  return MulAdd(BitCast(df32, a0), BitCast(df32, b0), sum0);
}

// ------------------------------ Reductions

namespace detail {

// N=1 for any T: no-op
template <typename T>
HWY_INLINE Vec128<T, 1> SumOfLanes(hwy::SizeTag<sizeof(T)> /* tag */,
                                   const Vec128<T, 1> v) {
  return v;
}
template <typename T>
HWY_INLINE Vec128<T, 1> MinOfLanes(hwy::SizeTag<sizeof(T)> /* tag */,
                                   const Vec128<T, 1> v) {
  return v;
}
template <typename T>
HWY_INLINE Vec128<T, 1> MaxOfLanes(hwy::SizeTag<sizeof(T)> /* tag */,
                                   const Vec128<T, 1> v) {
  return v;
}

// u32/i32/f32:

// N=2
template <typename T>
HWY_INLINE Vec128<T, 2> SumOfLanes(hwy::SizeTag<4> /* tag */,
                                   const Vec128<T, 2> v10) {
  return v10 + Vec128<T, 2>{Shuffle2301(Vec128<T>{v10.raw}).raw};
}
template <typename T>
HWY_INLINE Vec128<T, 2> MinOfLanes(hwy::SizeTag<4> /* tag */,
                                   const Vec128<T, 2> v10) {
  return Min(v10, Vec128<T, 2>{Shuffle2301(Vec128<T>{v10.raw}).raw});
}
template <typename T>
HWY_INLINE Vec128<T, 2> MaxOfLanes(hwy::SizeTag<4> /* tag */,
                                   const Vec128<T, 2> v10) {
  return Max(v10, Vec128<T, 2>{Shuffle2301(Vec128<T>{v10.raw}).raw});
}

// N=4 (full)
template <typename T>
HWY_INLINE Vec128<T> SumOfLanes(hwy::SizeTag<4> /* tag */,
                                const Vec128<T> v3210) {
  const Vec128<T> v1032 = Shuffle1032(v3210);
  const Vec128<T> v31_20_31_20 = v3210 + v1032;
  const Vec128<T> v20_31_20_31 = Shuffle0321(v31_20_31_20);
  return v20_31_20_31 + v31_20_31_20;
}
template <typename T>
HWY_INLINE Vec128<T> MinOfLanes(hwy::SizeTag<4> /* tag */,
                                const Vec128<T> v3210) {
  const Vec128<T> v1032 = Shuffle1032(v3210);
  const Vec128<T> v31_20_31_20 = Min(v3210, v1032);
  const Vec128<T> v20_31_20_31 = Shuffle0321(v31_20_31_20);
  return Min(v20_31_20_31, v31_20_31_20);
}
template <typename T>
HWY_INLINE Vec128<T> MaxOfLanes(hwy::SizeTag<4> /* tag */,
                                const Vec128<T> v3210) {
  const Vec128<T> v1032 = Shuffle1032(v3210);
  const Vec128<T> v31_20_31_20 = Max(v3210, v1032);
  const Vec128<T> v20_31_20_31 = Shuffle0321(v31_20_31_20);
  return Max(v20_31_20_31, v31_20_31_20);
}

// u64/i64/f64:

// N=2 (full)
template <typename T>
HWY_INLINE Vec128<T> SumOfLanes(hwy::SizeTag<8> /* tag */,
                                const Vec128<T> v10) {
  const Vec128<T> v01 = Shuffle01(v10);
  return v10 + v01;
}
template <typename T>
HWY_INLINE Vec128<T> MinOfLanes(hwy::SizeTag<8> /* tag */,
                                const Vec128<T> v10) {
  const Vec128<T> v01 = Shuffle01(v10);
  return Min(v10, v01);
}
template <typename T>
HWY_INLINE Vec128<T> MaxOfLanes(hwy::SizeTag<8> /* tag */,
                                const Vec128<T> v10) {
  const Vec128<T> v01 = Shuffle01(v10);
  return Max(v10, v01);
}

// u16/i16
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2), HWY_IF_GE32(T, N)>
HWY_API Vec128<T, N> MinOfLanes(hwy::SizeTag<2> /* tag */, Vec128<T, N> v) {
  const DFromV<decltype(v)> d;
  const Repartition<int32_t, decltype(d)> d32;
  const auto even = And(BitCast(d32, v), Set(d32, 0xFFFF));
  const auto odd = ShiftRight<16>(BitCast(d32, v));
  const auto min = MinOfLanes(d32, Min(even, odd));
  // Also broadcast into odd lanes.
  return BitCast(d, Or(min, ShiftLeft<16>(min)));
}
template <typename T, size_t N, HWY_IF_LANE_SIZE(T, 2), HWY_IF_GE32(T, N)>
HWY_API Vec128<T, N> MaxOfLanes(hwy::SizeTag<2> /* tag */, Vec128<T, N> v) {
  const DFromV<decltype(v)> d;
  const Repartition<int32_t, decltype(d)> d32;
  const auto even = And(BitCast(d32, v), Set(d32, 0xFFFF));
  const auto odd = ShiftRight<16>(BitCast(d32, v));
  const auto min = MaxOfLanes(d32, Max(even, odd));
  // Also broadcast into odd lanes.
  return BitCast(d, Or(min, ShiftLeft<16>(min)));
}

}  // namespace detail

// Supported for u/i/f 32/64. Returns the same value in each lane.
template <typename T, size_t N>
HWY_API Vec128<T, N> SumOfLanes(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return detail::SumOfLanes(hwy::SizeTag<sizeof(T)>(), v);
}
template <typename T, size_t N>
HWY_API Vec128<T, N> MinOfLanes(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return detail::MinOfLanes(hwy::SizeTag<sizeof(T)>(), v);
}
template <typename T, size_t N>
HWY_API Vec128<T, N> MaxOfLanes(Simd<T, N, 0> /* tag */, const Vec128<T, N> v) {
  return detail::MaxOfLanes(hwy::SizeTag<sizeof(T)>(), v);
}

// ------------------------------ Lt128

namespace detail {

template <size_t kLanes, typename T, size_t N>
Mask128<T, N> ShiftMaskLeft(Mask128<T, N> m) {
  return MaskFromVec(ShiftLeftLanes<kLanes>(VecFromMask(Simd<T, N, 0>(), m)));
}

}  // namespace detail

template <typename T, size_t N, HWY_IF_LE128(T, N)>
HWY_INLINE Mask128<T, N> Lt128(Simd<T, N, 0> d, Vec128<T, N> a,
                               Vec128<T, N> b) {
  static_assert(!IsSigned<T>() && sizeof(T) == 8, "Use u64");
  // Truth table of Eq and Lt for Hi and Lo u64.
  // (removed lines with (=H && cH) or (=L && cL) - cannot both be true)
  // =H =L cH cL  | out = cH | (=H & cL)
  //  0  0  0  0  |  0
  //  0  0  0  1  |  0
  //  0  0  1  0  |  1
  //  0  0  1  1  |  1
  //  0  1  0  0  |  0
  //  0  1  0  1  |  0
  //  0  1  1  0  |  1
  //  1  0  0  0  |  0
  //  1  0  0  1  |  1
  //  1  1  0  0  |  0
  const Mask128<T, N> eqHL = Eq(a, b);
  const Mask128<T, N> ltHL = Lt(a, b);
  // We need to bring cL to the upper lane/bit corresponding to cH. Comparing
  // the result of InterleaveUpper/Lower requires 9 ops, whereas shifting the
  // comparison result leftwards requires only 4.
  const Mask128<T, N> ltLx = detail::ShiftMaskLeft<1>(ltHL);
  const Mask128<T, N> outHx = Or(ltHL, And(eqHL, ltLx));
  const Vec128<T, N> vecHx = VecFromMask(d, outHx);
  return MaskFromVec(InterleaveUpper(d, vecHx, vecHx));
}

// ------------------------------ Min128, Max128 (Lt128)

// Without a native OddEven, it seems infeasible to go faster than Lt128.
template <class D>
HWY_INLINE VFromD<D> Min128(D d, const VFromD<D> a, const VFromD<D> b) {
  return IfThenElse(Lt128(d, a, b), a, b);
}

template <class D>
HWY_INLINE VFromD<D> Max128(D d, const VFromD<D> a, const VFromD<D> b) {
  return IfThenElse(Lt128(d, a, b), b, a);
}

// ================================================== Operator wrapper

template <class V>
HWY_API V Add(V a, V b) {
  return a + b;
}
template <class V>
HWY_API V Sub(V a, V b) {
  return a - b;
}

template <class V>
HWY_API V Mul(V a, V b) {
  return a * b;
}
template <class V>
HWY_API V Div(V a, V b) {
  return a / b;
}

template <class V>
V Shl(V a, V b) {
  return a << b;
}
template <class V>
V Shr(V a, V b) {
  return a >> b;
}

template <class V>
HWY_API auto Eq(V a, V b) -> decltype(a == b) {
  return a == b;
}
template <class V>
HWY_API auto Ne(V a, V b) -> decltype(a == b) {
  return a != b;
}
template <class V>
HWY_API auto Lt(V a, V b) -> decltype(a == b) {
  return a < b;
}

template <class V>
HWY_API auto Gt(V a, V b) -> decltype(a == b) {
  return a > b;
}
template <class V>
HWY_API auto Ge(V a, V b) -> decltype(a == b) {
  return a >= b;
}

template <class V>
HWY_API auto Le(V a, V b) -> decltype(a == b) {
  return a <= b;
}

// NOLINTNEXTLINE(google-readability-namespace-comments)
}  // namespace HWY_NAMESPACE
}  // namespace hwy
HWY_AFTER_NAMESPACE();
