Adding upstream version 124.0.1.upstream/124.0.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2030 insertions, 0 deletions

diff --git a/third_party/highway/hwy/ops/wasm_256-inl.h b/third_party/highway/hwy/ops/wasm_256-inl.h
new file mode 100644
index 0000000000..1654ae0afb
--- /dev/null
+++ b/third_party/highway/hwy/ops/wasm_256-inl.h
@@ -0,0 +1,2030 @@
+// Copyright 2021 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.
+
+// 256-bit WASM vectors and operations. Experimental.
+// External include guard in highway.h - see comment there.
+
+// For half-width vectors. Already includes base.h and shared-inl.h.
+#include "hwy/ops/wasm_128-inl.h"
+
+HWY_BEFORE_NAMESPACE();
+namespace hwy {
+namespace HWY_NAMESPACE {
+
+template <typename T>
+class Vec256 {
+ public:
+  using PrivateT = T;                                  // only for DFromV
+  static constexpr size_t kPrivateN = 32 / sizeof(T);  // only for DFromV
+
+  // Compound assignment. Only usable if there is a corresponding non-member
+  // binary operator overload. For example, only f32 and f64 support division.
+  HWY_INLINE Vec256& operator*=(const Vec256 other) {
+    return *this = (*this * other);
+  }
+  HWY_INLINE Vec256& operator/=(const Vec256 other) {
+    return *this = (*this / other);
+  }
+  HWY_INLINE Vec256& operator+=(const Vec256 other) {
+    return *this = (*this + other);
+  }
+  HWY_INLINE Vec256& operator-=(const Vec256 other) {
+    return *this = (*this - other);
+  }
+  HWY_INLINE Vec256& operator&=(const Vec256 other) {
+    return *this = (*this & other);
+  }
+  HWY_INLINE Vec256& operator|=(const Vec256 other) {
+    return *this = (*this | other);
+  }
+  HWY_INLINE Vec256& operator^=(const Vec256 other) {
+    return *this = (*this ^ other);
+  }
+
+  Vec128<T> v0;
+  Vec128<T> v1;
+};
+
+template <typename T>
+struct Mask256 {
+  Mask128<T> m0;
+  Mask128<T> m1;
+};
+
+// ------------------------------ Zero
+
+// Avoid VFromD here because it is defined in terms of Zero.
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API Vec256<TFromD<D>> Zero(D d) {
+  const Half<decltype(d)> dh;
+  Vec256<TFromD<D>> ret;
+  ret.v0 = ret.v1 = Zero(dh);
+  return ret;
+}
+
+// ------------------------------ BitCast
+template <class D, typename TFrom>
+HWY_API VFromD<D> BitCast(D d, Vec256<TFrom> v) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = BitCast(dh, v.v0);
+  ret.v1 = BitCast(dh, v.v1);
+  return ret;
+}
+
+// ------------------------------ ResizeBitCast
+
+// 32-byte vector to 32-byte vector: Same as BitCast
+template <class D, typename FromV, HWY_IF_V_SIZE_V(FromV, 32),
+          HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> ResizeBitCast(D d, FromV v) {
+  return BitCast(d, v);
+}
+
+// <= 16-byte vector to 32-byte vector
+template <class D, typename FromV, HWY_IF_V_SIZE_LE_V(FromV, 16),
+          HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> ResizeBitCast(D d, FromV v) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = ResizeBitCast(dh, v);
+  ret.v1 = Zero(dh);
+  return ret;
+}
+
+// 32-byte vector to <= 16-byte vector
+template <class D, typename FromV, HWY_IF_V_SIZE_V(FromV, 32),
+          HWY_IF_V_SIZE_LE_D(D, 16)>
+HWY_API VFromD<D> ResizeBitCast(D d, FromV v) {
+  return ResizeBitCast(d, v.v0);
+}
+
+// ------------------------------ Set
+template <class D, HWY_IF_V_SIZE_D(D, 32), typename T2>
+HWY_API VFromD<D> Set(D d, const T2 t) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = ret.v1 = Set(dh, static_cast<TFromD<D>>(t));
+  return ret;
+}
+
+// Undefined, Iota defined in wasm_128.
+
+// ================================================== ARITHMETIC
+
+template <typename T>
+HWY_API Vec256<T> operator+(Vec256<T> a, const Vec256<T> b) {
+  a.v0 += b.v0;
+  a.v1 += b.v1;
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> operator-(Vec256<T> a, const Vec256<T> b) {
+  a.v0 -= b.v0;
+  a.v1 -= b.v1;
+  return a;
+}
+
+// ------------------------------ SumsOf8
+HWY_API Vec256<uint64_t> SumsOf8(const Vec256<uint8_t> v) {
+  Vec256<uint64_t> ret;
+  ret.v0 = SumsOf8(v.v0);
+  ret.v1 = SumsOf8(v.v1);
+  return ret;
+}
+
+template <typename T>
+HWY_API Vec256<T> SaturatedAdd(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = SaturatedAdd(a.v0, b.v0);
+  a.v1 = SaturatedAdd(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> SaturatedSub(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = SaturatedSub(a.v0, b.v0);
+  a.v1 = SaturatedSub(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> AverageRound(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = AverageRound(a.v0, b.v0);
+  a.v1 = AverageRound(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> Abs(Vec256<T> v) {
+  v.v0 = Abs(v.v0);
+  v.v1 = Abs(v.v1);
+  return v;
+}
+
+// ------------------------------ Shift lanes by constant #bits
+
+template <int kBits, typename T>
+HWY_API Vec256<T> ShiftLeft(Vec256<T> v) {
+  v.v0 = ShiftLeft<kBits>(v.v0);
+  v.v1 = ShiftLeft<kBits>(v.v1);
+  return v;
+}
+
+template <int kBits, typename T>
+HWY_API Vec256<T> ShiftRight(Vec256<T> v) {
+  v.v0 = ShiftRight<kBits>(v.v0);
+  v.v1 = ShiftRight<kBits>(v.v1);
+  return v;
+}
+
+// ------------------------------ RotateRight (ShiftRight, Or)
+template <int kBits, typename T>
+HWY_API Vec256<T> RotateRight(const Vec256<T> 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
+
+template <typename T>
+HWY_API Vec256<T> ShiftLeftSame(Vec256<T> v, const int bits) {
+  v.v0 = ShiftLeftSame(v.v0, bits);
+  v.v1 = ShiftLeftSame(v.v1, bits);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> ShiftRightSame(Vec256<T> v, const int bits) {
+  v.v0 = ShiftRightSame(v.v0, bits);
+  v.v1 = ShiftRightSame(v.v1, bits);
+  return v;
+}
+
+// ------------------------------ Min, Max
+template <typename T>
+HWY_API Vec256<T> Min(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = Min(a.v0, b.v0);
+  a.v1 = Min(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> Max(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = Max(a.v0, b.v0);
+  a.v1 = Max(a.v1, b.v1);
+  return a;
+}
+// ------------------------------ Integer multiplication
+
+template <typename T>
+HWY_API Vec256<T> operator*(Vec256<T> a, const Vec256<T> b) {
+  a.v0 *= b.v0;
+  a.v1 *= b.v1;
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> MulHigh(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = MulHigh(a.v0, b.v0);
+  a.v1 = MulHigh(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> MulFixedPoint15(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = MulFixedPoint15(a.v0, b.v0);
+  a.v1 = MulFixedPoint15(a.v1, b.v1);
+  return a;
+}
+
+// Cannot use MakeWide because that returns uint128_t for uint64_t, but we want
+// uint64_t.
+HWY_API Vec256<uint64_t> MulEven(Vec256<uint32_t> a, const Vec256<uint32_t> b) {
+  Vec256<uint64_t> ret;
+  ret.v0 = MulEven(a.v0, b.v0);
+  ret.v1 = MulEven(a.v1, b.v1);
+  return ret;
+}
+HWY_API Vec256<int64_t> MulEven(Vec256<int32_t> a, const Vec256<int32_t> b) {
+  Vec256<int64_t> ret;
+  ret.v0 = MulEven(a.v0, b.v0);
+  ret.v1 = MulEven(a.v1, b.v1);
+  return ret;
+}
+
+HWY_API Vec256<uint64_t> MulEven(Vec256<uint64_t> a, const Vec256<uint64_t> b) {
+  Vec256<uint64_t> ret;
+  ret.v0 = MulEven(a.v0, b.v0);
+  ret.v1 = MulEven(a.v1, b.v1);
+  return ret;
+}
+HWY_API Vec256<uint64_t> MulOdd(Vec256<uint64_t> a, const Vec256<uint64_t> b) {
+  Vec256<uint64_t> ret;
+  ret.v0 = MulOdd(a.v0, b.v0);
+  ret.v1 = MulOdd(a.v1, b.v1);
+  return ret;
+}
+
+// ------------------------------ Negate
+template <typename T>
+HWY_API Vec256<T> Neg(Vec256<T> v) {
+  v.v0 = Neg(v.v0);
+  v.v1 = Neg(v.v1);
+  return v;
+}
+
+// ------------------------------ Floating-point division
+template <typename T>
+HWY_API Vec256<T> operator/(Vec256<T> a, const Vec256<T> b) {
+  a.v0 /= b.v0;
+  a.v1 /= b.v1;
+  return a;
+}
+
+// Approximate reciprocal
+HWY_API Vec256<float> ApproximateReciprocal(const Vec256<float> v) {
+  const Vec256<float> one = Set(Full256<float>(), 1.0f);
+  return one / v;
+}
+
+// Absolute value of difference.
+HWY_API Vec256<float> AbsDiff(const Vec256<float> a, const Vec256<float> b) {
+  return Abs(a - b);
+}
+
+// ------------------------------ Floating-point multiply-add variants
+
+HWY_API Vec256<float> MulAdd(Vec256<float> mul, Vec256<float> x,
+                             Vec256<float> add) {
+  mul.v0 = MulAdd(mul.v0, x.v0, add.v0);
+  mul.v1 = MulAdd(mul.v1, x.v1, add.v1);
+  return mul;
+}
+
+HWY_API Vec256<float> NegMulAdd(Vec256<float> mul, Vec256<float> x,
+                                Vec256<float> add) {
+  mul.v0 = NegMulAdd(mul.v0, x.v0, add.v0);
+  mul.v1 = NegMulAdd(mul.v1, x.v1, add.v1);
+  return mul;
+}
+
+HWY_API Vec256<float> MulSub(Vec256<float> mul, Vec256<float> x,
+                             Vec256<float> sub) {
+  mul.v0 = MulSub(mul.v0, x.v0, sub.v0);
+  mul.v1 = MulSub(mul.v1, x.v1, sub.v1);
+  return mul;
+}
+
+HWY_API Vec256<float> NegMulSub(Vec256<float> mul, Vec256<float> x,
+                                Vec256<float> sub) {
+  mul.v0 = NegMulSub(mul.v0, x.v0, sub.v0);
+  mul.v1 = NegMulSub(mul.v1, x.v1, sub.v1);
+  return mul;
+}
+
+// ------------------------------ Floating-point square root
+
+template <typename T>
+HWY_API Vec256<T> Sqrt(Vec256<T> v) {
+  v.v0 = Sqrt(v.v0);
+  v.v1 = Sqrt(v.v1);
+  return v;
+}
+
+// Approximate reciprocal square root
+HWY_API Vec256<float> ApproximateReciprocalSqrt(const Vec256<float> v) {
+  // TODO(eustas): find cheaper a way to calculate this.
+  const Vec256<float> one = Set(Full256<float>(), 1.0f);
+  return one / Sqrt(v);
+}
+
+// ------------------------------ Floating-point rounding
+
+// Toward nearest integer, ties to even
+HWY_API Vec256<float> Round(Vec256<float> v) {
+  v.v0 = Round(v.v0);
+  v.v1 = Round(v.v1);
+  return v;
+}
+
+// Toward zero, aka truncate
+HWY_API Vec256<float> Trunc(Vec256<float> v) {
+  v.v0 = Trunc(v.v0);
+  v.v1 = Trunc(v.v1);
+  return v;
+}
+
+// Toward +infinity, aka ceiling
+HWY_API Vec256<float> Ceil(Vec256<float> v) {
+  v.v0 = Ceil(v.v0);
+  v.v1 = Ceil(v.v1);
+  return v;
+}
+
+// Toward -infinity, aka floor
+HWY_API Vec256<float> Floor(Vec256<float> v) {
+  v.v0 = Floor(v.v0);
+  v.v1 = Floor(v.v1);
+  return v;
+}
+
+// ------------------------------ Floating-point classification
+
+template <typename T>
+HWY_API Mask256<T> IsNaN(const Vec256<T> v) {
+  return v != v;
+}
+
+template <typename T, HWY_IF_FLOAT(T)>
+HWY_API Mask256<T> IsInf(const Vec256<T> v) {
+  const DFromV<decltype(v)> 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, HWY_IF_FLOAT(T)>
+HWY_API Mask256<T> IsFinite(const Vec256<T> v) {
+  const DFromV<decltype(v)> 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 <class DTo, typename TFrom, typename TTo = TFromD<DTo>>
+HWY_API MFromD<DTo> RebindMask(DTo /*tag*/, Mask256<TFrom> m) {
+  static_assert(sizeof(TFrom) == sizeof(TTo), "Must have same size");
+  return MFromD<DTo>{Mask128<TTo>{m.m0.raw}, Mask128<TTo>{m.m1.raw}};
+}
+
+template <typename T>
+HWY_API Mask256<T> TestBit(Vec256<T> v, Vec256<T> bit) {
+  static_assert(!hwy::IsFloat<T>(), "Only integer vectors supported");
+  return (v & bit) == bit;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator==(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator==(a.v0, b.v0);
+  m.m1 = operator==(a.v1, b.v1);
+  return m;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator!=(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator!=(a.v0, b.v0);
+  m.m1 = operator!=(a.v1, b.v1);
+  return m;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator<(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator<(a.v0, b.v0);
+  m.m1 = operator<(a.v1, b.v1);
+  return m;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator>(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator>(a.v0, b.v0);
+  m.m1 = operator>(a.v1, b.v1);
+  return m;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator<=(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator<=(a.v0, b.v0);
+  m.m1 = operator<=(a.v1, b.v1);
+  return m;
+}
+
+template <typename T>
+HWY_API Mask256<T> operator>=(Vec256<T> a, const Vec256<T> b) {
+  Mask256<T> m;
+  m.m0 = operator>=(a.v0, b.v0);
+  m.m1 = operator>=(a.v1, b.v1);
+  return m;
+}
+
+// ------------------------------ FirstN (Iota, Lt)
+
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API MFromD<D> FirstN(const D d, size_t num) {
+  const RebindToSigned<decltype(d)> di;  // Signed comparisons may be cheaper.
+  using TI = TFromD<decltype(di)>;
+  return RebindMask(d, Iota(di, 0) < Set(di, static_cast<TI>(num)));
+}
+
+// ================================================== LOGICAL
+
+template <typename T>
+HWY_API Vec256<T> Not(Vec256<T> v) {
+  v.v0 = Not(v.v0);
+  v.v1 = Not(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> And(Vec256<T> a, Vec256<T> b) {
+  a.v0 = And(a.v0, b.v0);
+  a.v1 = And(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> AndNot(Vec256<T> not_mask, Vec256<T> mask) {
+  not_mask.v0 = AndNot(not_mask.v0, mask.v0);
+  not_mask.v1 = AndNot(not_mask.v1, mask.v1);
+  return not_mask;
+}
+
+template <typename T>
+HWY_API Vec256<T> Or(Vec256<T> a, Vec256<T> b) {
+  a.v0 = Or(a.v0, b.v0);
+  a.v1 = Or(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> Xor(Vec256<T> a, Vec256<T> b) {
+  a.v0 = Xor(a.v0, b.v0);
+  a.v1 = Xor(a.v1, b.v1);
+  return a;
+}
+
+template <typename T>
+HWY_API Vec256<T> Xor3(Vec256<T> x1, Vec256<T> x2, Vec256<T> x3) {
+  return Xor(x1, Xor(x2, x3));
+}
+
+template <typename T>
+HWY_API Vec256<T> Or3(Vec256<T> o1, Vec256<T> o2, Vec256<T> o3) {
+  return Or(o1, Or(o2, o3));
+}
+
+template <typename T>
+HWY_API Vec256<T> OrAnd(Vec256<T> o, Vec256<T> a1, Vec256<T> a2) {
+  return Or(o, And(a1, a2));
+}
+
+template <typename T>
+HWY_API Vec256<T> IfVecThenElse(Vec256<T> mask, Vec256<T> yes, Vec256<T> no) {
+  return IfThenElse(MaskFromVec(mask), yes, no);
+}
+
+// ------------------------------ Operator overloads (internal-only if float)
+
+template <typename T>
+HWY_API Vec256<T> operator&(const Vec256<T> a, const Vec256<T> b) {
+  return And(a, b);
+}
+
+template <typename T>
+HWY_API Vec256<T> operator|(const Vec256<T> a, const Vec256<T> b) {
+  return Or(a, b);
+}
+
+template <typename T>
+HWY_API Vec256<T> operator^(const Vec256<T> a, const Vec256<T> b) {
+  return Xor(a, b);
+}
+
+// ------------------------------ CopySign
+
+template <typename T>
+HWY_API Vec256<T> CopySign(const Vec256<T> magn, const Vec256<T> 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>
+HWY_API Vec256<T> CopySignToAbs(const Vec256<T> abs, const Vec256<T> sign) {
+  static_assert(IsFloat<T>(), "Only makes sense for floating-point");
+  return Or(abs, And(SignBit(DFromV<decltype(sign)>()), sign));
+}
+
+// ------------------------------ Mask
+
+// Mask and Vec are the same (true = FF..FF).
+template <typename T>
+HWY_API Mask256<T> MaskFromVec(const Vec256<T> v) {
+  Mask256<T> m;
+  m.m0 = MaskFromVec(v.v0);
+  m.m1 = MaskFromVec(v.v1);
+  return m;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> VecFromMask(D d, Mask256<T> m) {
+  const Half<decltype(d)> dh;
+  Vec256<T> v;
+  v.v0 = VecFromMask(dh, m.m0);
+  v.v1 = VecFromMask(dh, m.m1);
+  return v;
+}
+
+// mask ? yes : no
+template <typename T>
+HWY_API Vec256<T> IfThenElse(Mask256<T> mask, Vec256<T> yes, Vec256<T> no) {
+  yes.v0 = IfThenElse(mask.m0, yes.v0, no.v0);
+  yes.v1 = IfThenElse(mask.m1, yes.v1, no.v1);
+  return yes;
+}
+
+// mask ? yes : 0
+template <typename T>
+HWY_API Vec256<T> IfThenElseZero(Mask256<T> mask, Vec256<T> yes) {
+  return yes & VecFromMask(DFromV<decltype(yes)>(), mask);
+}
+
+// mask ? 0 : no
+template <typename T>
+HWY_API Vec256<T> IfThenZeroElse(Mask256<T> mask, Vec256<T> no) {
+  return AndNot(VecFromMask(DFromV<decltype(no)>(), mask), no);
+}
+
+template <typename T>
+HWY_API Vec256<T> IfNegativeThenElse(Vec256<T> v, Vec256<T> yes, Vec256<T> no) {
+  v.v0 = IfNegativeThenElse(v.v0, yes.v0, no.v0);
+  v.v1 = IfNegativeThenElse(v.v1, yes.v1, no.v1);
+  return v;
+}
+
+template <typename T, HWY_IF_FLOAT(T)>
+HWY_API Vec256<T> ZeroIfNegative(Vec256<T> v) {
+  return IfThenZeroElse(v < Zero(DFromV<decltype(v)>()), v);
+}
+
+// ------------------------------ Mask logical
+
+template <typename T>
+HWY_API Mask256<T> Not(const Mask256<T> m) {
+  return MaskFromVec(Not(VecFromMask(Full256<T>(), m)));
+}
+
+template <typename T>
+HWY_API Mask256<T> And(const Mask256<T> a, Mask256<T> b) {
+  const Full256<T> d;
+  return MaskFromVec(And(VecFromMask(d, a), VecFromMask(d, b)));
+}
+
+template <typename T>
+HWY_API Mask256<T> AndNot(const Mask256<T> a, Mask256<T> b) {
+  const Full256<T> d;
+  return MaskFromVec(AndNot(VecFromMask(d, a), VecFromMask(d, b)));
+}
+
+template <typename T>
+HWY_API Mask256<T> Or(const Mask256<T> a, Mask256<T> b) {
+  const Full256<T> d;
+  return MaskFromVec(Or(VecFromMask(d, a), VecFromMask(d, b)));
+}
+
+template <typename T>
+HWY_API Mask256<T> Xor(const Mask256<T> a, Mask256<T> b) {
+  const Full256<T> d;
+  return MaskFromVec(Xor(VecFromMask(d, a), VecFromMask(d, b)));
+}
+
+template <typename T>
+HWY_API Mask256<T> ExclusiveNeither(const Mask256<T> a, Mask256<T> b) {
+  const Full256<T> d;
+  return MaskFromVec(AndNot(VecFromMask(d, a), Not(VecFromMask(d, b))));
+}
+
+// ------------------------------ Shl (BroadcastSignBit, IfThenElse)
+template <typename T>
+HWY_API Vec256<T> operator<<(Vec256<T> v, const Vec256<T> bits) {
+  v.v0 = operator<<(v.v0, bits.v0);
+  v.v1 = operator<<(v.v1, bits.v1);
+  return v;
+}
+
+// ------------------------------ Shr (BroadcastSignBit, IfThenElse)
+template <typename T>
+HWY_API Vec256<T> operator>>(Vec256<T> v, const Vec256<T> bits) {
+  v.v0 = operator>>(v.v0, bits.v0);
+  v.v1 = operator>>(v.v1, bits.v1);
+  return v;
+}
+
+// ------------------------------ BroadcastSignBit (compare, VecFromMask)
+
+template <typename T, HWY_IF_NOT_T_SIZE(T, 1)>
+HWY_API Vec256<T> BroadcastSignBit(const Vec256<T> v) {
+  return ShiftRight<sizeof(T) * 8 - 1>(v);
+}
+HWY_API Vec256<int8_t> BroadcastSignBit(const Vec256<int8_t> v) {
+  const DFromV<decltype(v)> d;
+  return VecFromMask(d, v < Zero(d));
+}
+
+// ================================================== MEMORY
+
+// ------------------------------ Load
+
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> Load(D d, const TFromD<D>* HWY_RESTRICT aligned) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = Load(dh, aligned);
+  ret.v1 = Load(dh, aligned + Lanes(dh));
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> MaskedLoad(Mask256<T> m, D d, const T* HWY_RESTRICT aligned) {
+  return IfThenElseZero(m, Load(d, aligned));
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> MaskedLoadOr(Vec256<T> v, Mask256<T> m, D d,
+                               const T* HWY_RESTRICT aligned) {
+  return IfThenElse(m, Load(d, aligned), v);
+}
+
+// LoadU == Load.
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> LoadU(D d, const TFromD<D>* HWY_RESTRICT p) {
+  return Load(d, p);
+}
+
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> LoadDup128(D d, const TFromD<D>* HWY_RESTRICT p) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = ret.v1 = Load(dh, p);
+  return ret;
+}
+
+// ------------------------------ Store
+
+template <class D, typename T = TFromD<D>>
+HWY_API void Store(Vec256<T> v, D d, T* HWY_RESTRICT aligned) {
+  const Half<decltype(d)> dh;
+  Store(v.v0, dh, aligned);
+  Store(v.v1, dh, aligned + Lanes(dh));
+}
+
+// StoreU == Store.
+template <class D, typename T = TFromD<D>>
+HWY_API void StoreU(Vec256<T> v, D d, T* HWY_RESTRICT p) {
+  Store(v, d, p);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API void BlendedStore(Vec256<T> v, Mask256<T> m, D d, T* HWY_RESTRICT p) {
+  StoreU(IfThenElse(m, v, LoadU(d, p)), d, p);
+}
+
+// ------------------------------ Stream
+template <class D, typename T = TFromD<D>>
+HWY_API void Stream(Vec256<T> v, D d, T* HWY_RESTRICT aligned) {
+  // Same as aligned stores.
+  Store(v, d, aligned);
+}
+
+// ------------------------------ Scatter, Gather defined in wasm_128
+
+// ================================================== SWIZZLE
+
+// ------------------------------ ExtractLane
+template <typename T>
+HWY_API T ExtractLane(const Vec256<T> v, size_t i) {
+  alignas(32) T lanes[32 / sizeof(T)];
+  Store(v, DFromV<decltype(v)>(), lanes);
+  return lanes[i];
+}
+
+// ------------------------------ InsertLane
+template <typename T>
+HWY_API Vec256<T> InsertLane(const Vec256<T> v, size_t i, T t) {
+  DFromV<decltype(v)> d;
+  alignas(32) T lanes[32 / sizeof(T)];
+  Store(v, d, lanes);
+  lanes[i] = t;
+  return Load(d, lanes);
+}
+
+// ------------------------------ LowerHalf
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec128<T> LowerHalf(D /* tag */, Vec256<T> v) {
+  return v.v0;
+}
+
+template <typename T>
+HWY_API Vec128<T> LowerHalf(Vec256<T> v) {
+  return v.v0;
+}
+
+// ------------------------------ GetLane (LowerHalf)
+template <typename T>
+HWY_API T GetLane(const Vec256<T> v) {
+  return GetLane(LowerHalf(v));
+}
+
+// ------------------------------ ShiftLeftBytes
+
+template <int kBytes, class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ShiftLeftBytes(D d, Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  v.v0 = ShiftLeftBytes<kBytes>(dh, v.v0);
+  v.v1 = ShiftLeftBytes<kBytes>(dh, v.v1);
+  return v;
+}
+
+template <int kBytes, typename T>
+HWY_API Vec256<T> ShiftLeftBytes(Vec256<T> v) {
+  return ShiftLeftBytes<kBytes>(DFromV<decltype(v)>(), v);
+}
+
+// ------------------------------ ShiftLeftLanes
+
+template <int kLanes, class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ShiftLeftLanes(D d, const Vec256<T> v) {
+  const Repartition<uint8_t, decltype(d)> d8;
+  return BitCast(d, ShiftLeftBytes<kLanes * sizeof(T)>(BitCast(d8, v)));
+}
+
+template <int kLanes, typename T>
+HWY_API Vec256<T> ShiftLeftLanes(const Vec256<T> v) {
+  return ShiftLeftLanes<kLanes>(DFromV<decltype(v)>(), v);
+}
+
+// ------------------------------ ShiftRightBytes
+template <int kBytes, class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ShiftRightBytes(D d, Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  v.v0 = ShiftRightBytes<kBytes>(dh, v.v0);
+  v.v1 = ShiftRightBytes<kBytes>(dh, v.v1);
+  return v;
+}
+
+// ------------------------------ ShiftRightLanes
+template <int kLanes, class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ShiftRightLanes(D d, const Vec256<T> v) {
+  const Repartition<uint8_t, decltype(d)> d8;
+  return BitCast(d, ShiftRightBytes<kLanes * sizeof(T)>(d8, BitCast(d8, v)));
+}
+
+// ------------------------------ UpperHalf (ShiftRightBytes)
+template <class D, typename T = TFromD<D>>
+HWY_API Vec128<T> UpperHalf(D /* tag */, const Vec256<T> v) {
+  return v.v1;
+}
+
+// ------------------------------ CombineShiftRightBytes
+
+template <int kBytes, class D, typename T = TFromD<D>>
+HWY_API Vec256<T> CombineShiftRightBytes(D d, Vec256<T> hi, Vec256<T> lo) {
+  const Half<decltype(d)> dh;
+  hi.v0 = CombineShiftRightBytes<kBytes>(dh, hi.v0, lo.v0);
+  hi.v1 = CombineShiftRightBytes<kBytes>(dh, hi.v1, lo.v1);
+  return hi;
+}
+
+// ------------------------------ Broadcast/splat any lane
+
+template <int kLane, typename T>
+HWY_API Vec256<T> Broadcast(const Vec256<T> v) {
+  Vec256<T> ret;
+  ret.v0 = Broadcast<kLane>(v.v0);
+  ret.v1 = Broadcast<kLane>(v.v1);
+  return ret;
+}
+
+// ------------------------------ TableLookupBytes
+
+// Both full
+template <typename T, typename TI>
+HWY_API Vec256<TI> TableLookupBytes(const Vec256<T> bytes, Vec256<TI> from) {
+  from.v0 = TableLookupBytes(bytes.v0, from.v0);
+  from.v1 = TableLookupBytes(bytes.v1, from.v1);
+  return from;
+}
+
+// Partial index vector
+template <typename T, typename TI, size_t NI>
+HWY_API Vec128<TI, NI> TableLookupBytes(Vec256<T> bytes,
+                                        const Vec128<TI, NI> from) {
+  // First expand to full 128, then 256.
+  const auto from_256 = ZeroExtendVector(Full256<TI>(), Vec128<TI>{from.raw});
+  const auto tbl_full = TableLookupBytes(bytes, from_256);
+  // Shrink to 128, then partial.
+  return Vec128<TI, NI>{LowerHalf(Full128<TI>(), tbl_full).raw};
+}
+
+// Partial table vector
+template <typename T, size_t N, typename TI>
+HWY_API Vec256<TI> TableLookupBytes(Vec128<T, N> bytes, const Vec256<TI> from) {
+  // First expand to full 128, then 256.
+  const auto bytes_256 = ZeroExtendVector(Full256<T>(), Vec128<T>{bytes.raw});
+  return TableLookupBytes(bytes_256, from);
+}
+
+// Partial both are handled by wasm_128.
+
+template <class V, class VI>
+HWY_API VI TableLookupBytesOr0(V bytes, VI from) {
+  // wasm out-of-bounds policy already zeros, so TableLookupBytes is fine.
+  return TableLookupBytes(bytes, from);
+}
+
+// ------------------------------ Hard-coded shuffles
+
+template <typename T>
+HWY_API Vec256<T> Shuffle01(Vec256<T> v) {
+  v.v0 = Shuffle01(v.v0);
+  v.v1 = Shuffle01(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> Shuffle2301(Vec256<T> v) {
+  v.v0 = Shuffle2301(v.v0);
+  v.v1 = Shuffle2301(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> Shuffle1032(Vec256<T> v) {
+  v.v0 = Shuffle1032(v.v0);
+  v.v1 = Shuffle1032(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> Shuffle0321(Vec256<T> v) {
+  v.v0 = Shuffle0321(v.v0);
+  v.v1 = Shuffle0321(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> Shuffle2103(Vec256<T> v) {
+  v.v0 = Shuffle2103(v.v0);
+  v.v1 = Shuffle2103(v.v1);
+  return v;
+}
+
+template <typename T>
+HWY_API Vec256<T> Shuffle0123(Vec256<T> v) {
+  v.v0 = Shuffle0123(v.v0);
+  v.v1 = Shuffle0123(v.v1);
+  return v;
+}
+
+// Used by generic_ops-inl.h
+namespace detail {
+
+template <typename T, HWY_IF_T_SIZE(T, 4)>
+HWY_API Vec256<T> ShuffleTwo2301(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = ShuffleTwo2301(a.v0, b.v0);
+  a.v1 = ShuffleTwo2301(a.v1, b.v1);
+  return a;
+}
+template <typename T, HWY_IF_T_SIZE(T, 4)>
+HWY_API Vec256<T> ShuffleTwo1230(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = ShuffleTwo1230(a.v0, b.v0);
+  a.v1 = ShuffleTwo1230(a.v1, b.v1);
+  return a;
+}
+template <typename T, HWY_IF_T_SIZE(T, 4)>
+HWY_API Vec256<T> ShuffleTwo3012(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = ShuffleTwo3012(a.v0, b.v0);
+  a.v1 = ShuffleTwo3012(a.v1, b.v1);
+  return a;
+}
+
+}  // namespace detail
+
+// ------------------------------ TableLookupLanes
+
+// Returned by SetTableIndices for use by TableLookupLanes.
+template <typename T>
+struct Indices256 {
+  __v128_u i0;
+  __v128_u i1;
+};
+
+template <class D, typename T = TFromD<D>, typename TI>
+HWY_API Indices256<T> IndicesFromVec(D /* tag */, Vec256<TI> vec) {
+  static_assert(sizeof(T) == sizeof(TI), "Index size must match lane");
+  Indices256<T> ret;
+  ret.i0 = vec.v0.raw;
+  ret.i1 = vec.v1.raw;
+  return ret;
+}
+
+template <class D, HWY_IF_V_SIZE_D(D, 32), typename TI>
+HWY_API Indices256<TFromD<D>> SetTableIndices(D d, const TI* idx) {
+  const Rebind<TI, decltype(d)> di;
+  return IndicesFromVec(d, LoadU(di, idx));
+}
+
+template <typename T>
+HWY_API Vec256<T> TableLookupLanes(const Vec256<T> v, Indices256<T> idx) {
+  const DFromV<decltype(v)> d;
+  const Half<decltype(d)> dh;
+  const auto idx_i0 = IndicesFromVec(dh, Vec128<T>{idx.i0});
+  const auto idx_i1 = IndicesFromVec(dh, Vec128<T>{idx.i1});
+
+  Vec256<T> result;
+  result.v0 = TwoTablesLookupLanes(v.v0, v.v1, idx_i0);
+  result.v1 = TwoTablesLookupLanes(v.v0, v.v1, idx_i1);
+  return result;
+}
+
+template <typename T>
+HWY_API Vec256<T> TableLookupLanesOr0(Vec256<T> v, Indices256<T> idx) {
+  // The out of bounds behavior will already zero lanes.
+  return TableLookupLanesOr0(v, idx);
+}
+
+template <typename T>
+HWY_API Vec256<T> TwoTablesLookupLanes(const Vec256<T> a, const Vec256<T> b,
+                                       Indices256<T> idx) {
+  const DFromV<decltype(a)> d;
+  const Half<decltype(d)> dh;
+  const RebindToUnsigned<decltype(d)> du;
+  using TU = MakeUnsigned<T>;
+  constexpr size_t kLanesPerVect = 32 / sizeof(TU);
+
+  Vec256<TU> vi;
+  vi.v0 = Vec128<TU>{idx.i0};
+  vi.v1 = Vec128<TU>{idx.i1};
+  const auto vmod = vi & Set(du, TU{kLanesPerVect - 1});
+  const auto is_lo = RebindMask(d, vi == vmod);
+
+  const auto idx_i0 = IndicesFromVec(dh, vmod.v0);
+  const auto idx_i1 = IndicesFromVec(dh, vmod.v1);
+
+  Vec256<T> result_lo;
+  Vec256<T> result_hi;
+  result_lo.v0 = TwoTablesLookupLanes(a.v0, a.v1, idx_i0);
+  result_lo.v1 = TwoTablesLookupLanes(a.v0, a.v1, idx_i1);
+  result_hi.v0 = TwoTablesLookupLanes(b.v0, b.v1, idx_i0);
+  result_hi.v1 = TwoTablesLookupLanes(b.v0, b.v1, idx_i1);
+  return IfThenElse(is_lo, result_lo, result_hi);
+}
+
+// ------------------------------ Reverse
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> Reverse(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v1 = Reverse(dh, v.v0);  // note reversed v1 member order
+  ret.v0 = Reverse(dh, v.v1);
+  return ret;
+}
+
+// ------------------------------ Reverse2
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> Reverse2(D d, Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  v.v0 = Reverse2(dh, v.v0);
+  v.v1 = Reverse2(dh, v.v1);
+  return v;
+}
+
+// ------------------------------ Reverse4
+
+// Each block has only 2 lanes, so swap blocks and their lanes.
+template <class D, typename T = TFromD<D>, HWY_IF_T_SIZE(T, 8)>
+HWY_API Vec256<T> Reverse4(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Reverse2(dh, v.v1);  // swapped
+  ret.v1 = Reverse2(dh, v.v0);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>, HWY_IF_NOT_T_SIZE(T, 8)>
+HWY_API Vec256<T> Reverse4(D d, Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  v.v0 = Reverse4(dh, v.v0);
+  v.v1 = Reverse4(dh, v.v1);
+  return v;
+}
+
+// ------------------------------ Reverse8
+
+template <class D, typename T = TFromD<D>, HWY_IF_T_SIZE(T, 8)>
+HWY_API Vec256<T> Reverse8(D /* tag */, Vec256<T> /* v */) {
+  HWY_ASSERT(0);  // don't have 8 u64 lanes
+}
+
+// Each block has only 4 lanes, so swap blocks and their lanes.
+template <class D, typename T = TFromD<D>, HWY_IF_T_SIZE(T, 4)>
+HWY_API Vec256<T> Reverse8(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Reverse4(dh, v.v1);  // swapped
+  ret.v1 = Reverse4(dh, v.v0);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>,
+          HWY_IF_T_SIZE_ONE_OF(T, (1 << 1) | (1 << 2))>
+HWY_API Vec256<T> Reverse8(D d, Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  v.v0 = Reverse8(dh, v.v0);
+  v.v1 = Reverse8(dh, v.v1);
+  return v;
+}
+
+// ------------------------------ InterleaveLower
+
+template <typename T>
+HWY_API Vec256<T> InterleaveLower(Vec256<T> a, Vec256<T> b) {
+  a.v0 = InterleaveLower(a.v0, b.v0);
+  a.v1 = InterleaveLower(a.v1, b.v1);
+  return a;
+}
+
+// wasm_128 already defines a template with D, V, V args.
+
+// ------------------------------ InterleaveUpper (UpperHalf)
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> InterleaveUpper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  a.v0 = InterleaveUpper(dh, a.v0, b.v0);
+  a.v1 = InterleaveUpper(dh, a.v1, b.v1);
+  return a;
+}
+
+// ------------------------------ ZipLower/ZipUpper defined in wasm_128
+
+// ================================================== COMBINE
+
+// ------------------------------ Combine (InterleaveLower)
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> Combine(D /* d */, Vec128<T> hi, Vec128<T> lo) {
+  Vec256<T> ret;
+  ret.v1 = hi;
+  ret.v0 = lo;
+  return ret;
+}
+
+// ------------------------------ ZeroExtendVector (Combine)
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ZeroExtendVector(D d, Vec128<T> lo) {
+  const Half<decltype(d)> dh;
+  return Combine(d, Zero(dh), lo);
+}
+
+// ------------------------------ ZeroExtendResizeBitCast
+
+namespace detail {
+
+template <size_t kFromVectSize, class DTo, class DFrom,
+          HWY_IF_LANES_LE(kFromVectSize, 8)>
+HWY_INLINE VFromD<DTo> ZeroExtendResizeBitCast(
+    hwy::SizeTag<kFromVectSize> /* from_size_tag */,
+    hwy::SizeTag<32> /* to_size_tag */, DTo d_to, DFrom d_from,
+    VFromD<DFrom> v) {
+  const Half<decltype(d_to)> dh_to;
+  return ZeroExtendVector(d_to, ZeroExtendResizeBitCast(dh_to, d_from, v));
+}
+
+}  // namespace detail
+
+// ------------------------------ ConcatLowerLower
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatLowerLower(D /* tag */, Vec256<T> hi, Vec256<T> lo) {
+  Vec256<T> ret;
+  ret.v1 = hi.v0;
+  ret.v0 = lo.v0;
+  return ret;
+}
+
+// ------------------------------ ConcatUpperUpper
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatUpperUpper(D /* tag */, Vec256<T> hi, Vec256<T> lo) {
+  Vec256<T> ret;
+  ret.v1 = hi.v1;
+  ret.v0 = lo.v1;
+  return ret;
+}
+
+// ------------------------------ ConcatLowerUpper
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatLowerUpper(D /* tag */, Vec256<T> hi, Vec256<T> lo) {
+  Vec256<T> ret;
+  ret.v1 = hi.v0;
+  ret.v0 = lo.v1;
+  return ret;
+}
+
+// ------------------------------ ConcatUpperLower
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatUpperLower(D /* tag */, Vec256<T> hi, Vec256<T> lo) {
+  Vec256<T> ret;
+  ret.v1 = hi.v1;
+  ret.v0 = lo.v0;
+  return ret;
+}
+
+// ------------------------------ ConcatOdd
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatOdd(D d, Vec256<T> hi, Vec256<T> lo) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = ConcatOdd(dh, lo.v1, lo.v0);
+  ret.v1 = ConcatOdd(dh, hi.v1, hi.v0);
+  return ret;
+}
+
+// ------------------------------ ConcatEven
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ConcatEven(D d, Vec256<T> hi, Vec256<T> lo) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = ConcatEven(dh, lo.v1, lo.v0);
+  ret.v1 = ConcatEven(dh, hi.v1, hi.v0);
+  return ret;
+}
+
+// ------------------------------ DupEven
+template <typename T>
+HWY_API Vec256<T> DupEven(Vec256<T> v) {
+  v.v0 = DupEven(v.v0);
+  v.v1 = DupEven(v.v1);
+  return v;
+}
+
+// ------------------------------ DupOdd
+template <typename T>
+HWY_API Vec256<T> DupOdd(Vec256<T> v) {
+  v.v0 = DupOdd(v.v0);
+  v.v1 = DupOdd(v.v1);
+  return v;
+}
+
+// ------------------------------ OddEven
+template <typename T>
+HWY_API Vec256<T> OddEven(Vec256<T> a, const Vec256<T> b) {
+  a.v0 = OddEven(a.v0, b.v0);
+  a.v1 = OddEven(a.v1, b.v1);
+  return a;
+}
+
+// ------------------------------ OddEvenBlocks
+template <typename T>
+HWY_API Vec256<T> OddEvenBlocks(Vec256<T> odd, Vec256<T> even) {
+  odd.v0 = even.v0;
+  return odd;
+}
+
+// ------------------------------ SwapAdjacentBlocks
+template <typename T>
+HWY_API Vec256<T> SwapAdjacentBlocks(Vec256<T> v) {
+  Vec256<T> ret;
+  ret.v0 = v.v1;  // swapped order
+  ret.v1 = v.v0;
+  return ret;
+}
+
+// ------------------------------ ReverseBlocks
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> ReverseBlocks(D /* tag */, const Vec256<T> v) {
+  return SwapAdjacentBlocks(v);  // 2 blocks, so Swap = Reverse
+}
+
+// ================================================== CONVERT
+
+// ------------------------------ Promotions (part w/ narrow lanes -> full)
+
+namespace detail {
+
+// Unsigned: zero-extend.
+template <class D, HWY_IF_U16_D(D)>
+HWY_API Vec128<uint16_t> PromoteUpperTo(D /* tag */, Vec128<uint8_t> v) {
+  return Vec128<uint16_t>{wasm_u16x8_extend_high_u8x16(v.raw)};
+}
+template <class D, HWY_IF_U32_D(D)>
+HWY_API Vec128<uint32_t> PromoteUpperTo(D /* tag */, Vec128<uint8_t> v) {
+  return Vec128<uint32_t>{
+      wasm_u32x4_extend_high_u16x8(wasm_u16x8_extend_high_u8x16(v.raw))};
+}
+template <class D, HWY_IF_I16_D(D)>
+HWY_API Vec128<int16_t> PromoteUpperTo(D /* tag */, Vec128<uint8_t> v) {
+  return Vec128<int16_t>{wasm_u16x8_extend_high_u8x16(v.raw)};
+}
+template <class D, HWY_IF_I32_D(D)>
+HWY_API Vec128<int32_t> PromoteUpperTo(D /* tag */, Vec128<uint8_t> v) {
+  return Vec128<int32_t>{
+      wasm_u32x4_extend_high_u16x8(wasm_u16x8_extend_high_u8x16(v.raw))};
+}
+template <class D, HWY_IF_U32_D(D)>
+HWY_API Vec128<uint32_t> PromoteUpperTo(D /* tag */, Vec128<uint16_t> v) {
+  return Vec128<uint32_t>{wasm_u32x4_extend_high_u16x8(v.raw)};
+}
+template <class D, HWY_IF_U64_D(D)>
+HWY_API Vec128<uint64_t> PromoteUpperTo(D /* tag */, Vec128<uint32_t> v) {
+  return Vec128<uint64_t>{wasm_u64x2_extend_high_u32x4(v.raw)};
+}
+template <class D, HWY_IF_I32_D(D)>
+HWY_API Vec128<int32_t> PromoteUpperTo(D /* tag */, Vec128<uint16_t> v) {
+  return Vec128<int32_t>{wasm_u32x4_extend_high_u16x8(v.raw)};
+}
+template <class D, HWY_IF_I64_D(D)>
+HWY_API Vec128<int64_t> PromoteUpperTo(D /* tag */, Vec128<uint32_t> v) {
+  return Vec128<int64_t>{wasm_u64x2_extend_high_u32x4(v.raw)};
+}
+
+// Signed: replicate sign bit.
+template <class D, HWY_IF_I16_D(D)>
+HWY_API Vec128<int16_t> PromoteUpperTo(D /* tag */, Vec128<int8_t> v) {
+  return Vec128<int16_t>{wasm_i16x8_extend_high_i8x16(v.raw)};
+}
+template <class D, HWY_IF_I32_D(D)>
+HWY_API Vec128<int32_t> PromoteUpperTo(D /* tag */, Vec128<int8_t> v) {
+  return Vec128<int32_t>{
+      wasm_i32x4_extend_high_i16x8(wasm_i16x8_extend_high_i8x16(v.raw))};
+}
+template <class D, HWY_IF_I32_D(D)>
+HWY_API Vec128<int32_t> PromoteUpperTo(D /* tag */, Vec128<int16_t> v) {
+  return Vec128<int32_t>{wasm_i32x4_extend_high_i16x8(v.raw)};
+}
+template <class D, HWY_IF_I64_D(D)>
+HWY_API Vec128<int64_t> PromoteUpperTo(D /* tag */, Vec128<int32_t> v) {
+  return Vec128<int64_t>{wasm_i64x2_extend_high_i32x4(v.raw)};
+}
+
+template <class D, HWY_IF_F64_D(D)>
+HWY_API Vec128<double> PromoteUpperTo(D dd, Vec128<int32_t> v) {
+  // There is no wasm_f64x2_convert_high_i32x4.
+  const Full64<int32_t> di32h;
+  return PromoteTo(dd, UpperHalf(di32h, v));
+}
+
+template <class D, HWY_IF_F32_D(D)>
+HWY_API Vec128<float> PromoteUpperTo(D df32, Vec128<float16_t> v) {
+  const RebindToSigned<decltype(df32)> di32;
+  const RebindToUnsigned<decltype(df32)> du32;
+  // Expand to u32 so we can shift.
+  const auto bits16 = PromoteUpperTo(du32, Vec128<uint16_t>{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 <class D, HWY_IF_F32_D(D)>
+HWY_API Vec128<float> PromoteUpperTo(D df32, Vec128<bfloat16_t> v) {
+  const Full128<uint16_t> du16;
+  const RebindToSigned<decltype(df32)> di32;
+  return BitCast(df32, ShiftLeft<16>(PromoteUpperTo(di32, BitCast(du16, v))));
+}
+
+}  // namespace detail
+
+template <class D, HWY_IF_V_SIZE_D(D, 32), typename TN,
+          HWY_IF_T_SIZE_D(D, sizeof(TN) * 2)>
+HWY_API VFromD<D> PromoteTo(D d, Vec128<TN> v) {
+  const Half<decltype(d)> dh;
+  VFromD<D> ret;
+  ret.v0 = PromoteTo(dh, LowerHalf(v));
+  ret.v1 = detail::PromoteUpperTo(dh, v);
+  return ret;
+}
+
+// 4x promotion: 8-bit to 32-bit or 16-bit to 64-bit
+template <class DW, HWY_IF_V_SIZE_D(DW, 32),
+          HWY_IF_T_SIZE_ONE_OF_D(DW, (1 << 4) | (1 << 8)),
+          HWY_IF_NOT_FLOAT_D(DW), typename TN,
+          HWY_IF_T_SIZE_D(DW, sizeof(TN) * 4),
+          HWY_IF_NOT_FLOAT_NOR_SPECIAL(TN)>
+HWY_API Vec256<TFromD<DW>> PromoteTo(DW d, Vec64<TN> v) {
+  const Half<decltype(d)> dh;
+  // 16-bit lanes for UI8->UI32, 32-bit lanes for UI16->UI64
+  const Rebind<MakeWide<TN>, decltype(d)> d2;
+  const auto v_2x = PromoteTo(d2, v);
+  Vec256<TFromD<DW>> ret;
+  ret.v0 = PromoteTo(dh, LowerHalf(v_2x));
+  ret.v1 = detail::PromoteUpperTo(dh, v_2x);
+  return ret;
+}
+
+// 8x promotion: 8-bit to 64-bit
+template <class DW, HWY_IF_V_SIZE_D(DW, 32), HWY_IF_T_SIZE_D(DW, 8),
+          HWY_IF_NOT_FLOAT_D(DW), typename TN, HWY_IF_T_SIZE(TN, 1)>
+HWY_API Vec256<TFromD<DW>> PromoteTo(DW d, Vec32<TN> v) {
+  const Half<decltype(d)> dh;
+  const Repartition<MakeWide<MakeWide<TN>>, decltype(dh)> d4;  // 32-bit lanes
+  const auto v32 = PromoteTo(d4, v);
+  Vec256<TFromD<DW>> ret;
+  ret.v0 = PromoteTo(dh, LowerHalf(v32));
+  ret.v1 = detail::PromoteUpperTo(dh, v32);
+  return ret;
+}
+
+// ------------------------------ DemoteTo
+
+template <class D, HWY_IF_U16_D(D)>
+HWY_API Vec128<uint16_t> DemoteTo(D /* tag */, Vec256<int32_t> v) {
+  return Vec128<uint16_t>{wasm_u16x8_narrow_i32x4(v.v0.raw, v.v1.raw)};
+}
+
+template <class D, HWY_IF_I16_D(D)>
+HWY_API Vec128<int16_t> DemoteTo(D /* tag */, Vec256<int32_t> v) {
+  return Vec128<int16_t>{wasm_i16x8_narrow_i32x4(v.v0.raw, v.v1.raw)};
+}
+
+template <class D, HWY_IF_U8_D(D)>
+HWY_API Vec64<uint8_t> DemoteTo(D /* tag */, Vec256<int32_t> v) {
+  const auto intermediate = wasm_i16x8_narrow_i32x4(v.v0.raw, v.v1.raw);
+  return Vec64<uint8_t>{wasm_u8x16_narrow_i16x8(intermediate, intermediate)};
+}
+
+template <class D, HWY_IF_U8_D(D)>
+HWY_API Vec128<uint8_t> DemoteTo(D /* tag */, Vec256<int16_t> v) {
+  return Vec128<uint8_t>{wasm_u8x16_narrow_i16x8(v.v0.raw, v.v1.raw)};
+}
+
+template <class D, HWY_IF_I8_D(D)>
+HWY_API Vec64<int8_t> DemoteTo(D /* tag */, Vec256<int32_t> v) {
+  const auto intermediate = wasm_i16x8_narrow_i32x4(v.v0.raw, v.v1.raw);
+  return Vec64<int8_t>{wasm_i8x16_narrow_i16x8(intermediate, intermediate)};
+}
+
+template <class D, HWY_IF_I8_D(D)>
+HWY_API Vec128<int8_t> DemoteTo(D /* tag */, Vec256<int16_t> v) {
+  return Vec128<int8_t>{wasm_i8x16_narrow_i16x8(v.v0.raw, v.v1.raw)};
+}
+
+template <class D, HWY_IF_I32_D(D)>
+HWY_API Vec128<int32_t> DemoteTo(D di, Vec256<double> v) {
+  const Vec64<int32_t> lo{wasm_i32x4_trunc_sat_f64x2_zero(v.v0.raw)};
+  const Vec64<int32_t> hi{wasm_i32x4_trunc_sat_f64x2_zero(v.v1.raw)};
+  return Combine(di, hi, lo);
+}
+
+template <class D, HWY_IF_F16_D(D)>
+HWY_API Vec128<float16_t> DemoteTo(D d16, Vec256<float> v) {
+  const Half<decltype(d16)> d16h;
+  const Vec64<float16_t> lo = DemoteTo(d16h, v.v0);
+  const Vec64<float16_t> hi = DemoteTo(d16h, v.v1);
+  return Combine(d16, hi, lo);
+}
+
+template <class D, HWY_IF_BF16_D(D)>
+HWY_API Vec128<bfloat16_t> DemoteTo(D dbf16, Vec256<float> v) {
+  const Half<decltype(dbf16)> dbf16h;
+  const Vec64<bfloat16_t> lo = DemoteTo(dbf16h, v.v0);
+  const Vec64<bfloat16_t> hi = DemoteTo(dbf16h, v.v1);
+  return Combine(dbf16, hi, lo);
+}
+
+// For already range-limited input [0, 255].
+HWY_API Vec64<uint8_t> U8FromU32(Vec256<uint32_t> v) {
+  const Full64<uint8_t> du8;
+  const Full256<int32_t> di32;  // no unsigned DemoteTo
+  return DemoteTo(du8, BitCast(di32, v));
+}
+
+// ------------------------------ Truncations
+
+template <class D, HWY_IF_U8_D(D)>
+HWY_API Vec32<uint8_t> TruncateTo(D /* tag */, Vec256<uint64_t> v) {
+  return Vec32<uint8_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 8, 16, 24, 0,
+                                           8, 16, 24, 0, 8, 16, 24, 0, 8, 16,
+                                           24)};
+}
+
+template <class D, HWY_IF_U16_D(D)>
+HWY_API Vec64<uint16_t> TruncateTo(D /* tag */, Vec256<uint64_t> v) {
+  return Vec64<uint16_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 1, 8, 9, 16,
+                                            17, 24, 25, 0, 1, 8, 9, 16, 17, 24,
+                                            25)};
+}
+
+template <class D, HWY_IF_U32_D(D)>
+HWY_API Vec128<uint32_t> TruncateTo(D /* tag */, Vec256<uint64_t> v) {
+  return Vec128<uint32_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 1, 2, 3, 8,
+                                             9, 10, 11, 16, 17, 18, 19, 24, 25,
+                                             26, 27)};
+}
+
+template <class D, HWY_IF_U8_D(D)>
+HWY_API Vec64<uint8_t> TruncateTo(D /* tag */, Vec256<uint32_t> v) {
+  return Vec64<uint8_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 4, 8, 12, 16,
+                                           20, 24, 28, 0, 4, 8, 12, 16, 20, 24,
+                                           28)};
+}
+
+template <class D, HWY_IF_U16_D(D)>
+HWY_API Vec128<uint16_t> TruncateTo(D /* tag */, Vec256<uint32_t> v) {
+  return Vec128<uint16_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 1, 4, 5, 8,
+                                             9, 12, 13, 16, 17, 20, 21, 24, 25,
+                                             28, 29)};
+}
+
+template <class D, HWY_IF_U8_D(D)>
+HWY_API Vec128<uint8_t> TruncateTo(D /* tag */, Vec256<uint16_t> v) {
+  return Vec128<uint8_t>{wasm_i8x16_shuffle(v.v0.raw, v.v1.raw, 0, 2, 4, 6, 8,
+                                            10, 12, 14, 16, 18, 20, 22, 24, 26,
+                                            28, 30)};
+}
+
+// ------------------------------ ReorderDemote2To
+template <class DBF16, HWY_IF_BF16_D(DBF16)>
+HWY_API Vec256<bfloat16_t> ReorderDemote2To(DBF16 dbf16, Vec256<float> a,
+                                            Vec256<float> b) {
+  const RebindToUnsigned<decltype(dbf16)> du16;
+  return BitCast(dbf16, ConcatOdd(du16, BitCast(du16, b), BitCast(du16, a)));
+}
+
+template <class DN, typename V, HWY_IF_V_SIZE_D(DN, 32),
+          HWY_IF_NOT_FLOAT_NOR_SPECIAL(TFromD<DN>), HWY_IF_SIGNED_V(V),
+          HWY_IF_T_SIZE_ONE_OF_D(DN, (1 << 1) | (1 << 2) | (1 << 4)),
+          HWY_IF_T_SIZE_V(V, sizeof(TFromD<DN>) * 2)>
+HWY_API VFromD<DN> ReorderDemote2To(DN dn, V a, V b) {
+  const Half<decltype(dn)> dnh;
+  VFromD<DN> demoted;
+  demoted.v0 = DemoteTo(dnh, a);
+  demoted.v1 = DemoteTo(dnh, b);
+  return demoted;
+}
+
+template <class DN, typename V, HWY_IF_V_SIZE_D(DN, 32), HWY_IF_UNSIGNED_D(DN),
+          HWY_IF_UNSIGNED_V(V),
+          HWY_IF_T_SIZE_ONE_OF_D(DN, (1 << 1) | (1 << 2) | (1 << 4)),
+          HWY_IF_T_SIZE_V(V, sizeof(TFromD<DN>) * 2)>
+HWY_API VFromD<DN> ReorderDemote2To(DN dn, V a, V b) {
+  const Half<decltype(dn)> dnh;
+  VFromD<DN> demoted;
+  demoted.v0 = DemoteTo(dnh, a);
+  demoted.v1 = DemoteTo(dnh, b);
+  return demoted;
+}
+
+// ------------------------------ Convert i32 <=> f32 (Round)
+
+template <class DTo, typename TFrom, typename TTo = TFromD<DTo>>
+HWY_API Vec256<TTo> ConvertTo(DTo d, const Vec256<TFrom> v) {
+  const Half<decltype(d)> dh;
+  Vec256<TTo> ret;
+  ret.v0 = ConvertTo(dh, v.v0);
+  ret.v1 = ConvertTo(dh, v.v1);
+  return ret;
+}
+
+HWY_API Vec256<int32_t> NearestInt(const Vec256<float> v) {
+  return ConvertTo(Full256<int32_t>(), Round(v));
+}
+
+// ================================================== MISC
+
+// ------------------------------ LoadMaskBits (TestBit)
+
+// `p` points to at least 8 readable bytes, not all of which need be valid.
+template <class D, HWY_IF_V_SIZE_D(D, 32),
+          HWY_IF_T_SIZE_ONE_OF_D(D, (1 << 4) | (1 << 8))>
+HWY_API MFromD<D> LoadMaskBits(D d, const uint8_t* HWY_RESTRICT bits) {
+  const Half<decltype(d)> dh;
+  MFromD<D> ret;
+  ret.m0 = LoadMaskBits(dh, bits);
+  // If size=4, one 128-bit vector has 4 mask bits; otherwise 2 for size=8.
+  // Both halves fit in one byte's worth of mask bits.
+  constexpr size_t kBitsPerHalf = 16 / sizeof(TFromD<D>);
+  const uint8_t bits_upper[8] = {static_cast<uint8_t>(bits[0] >> kBitsPerHalf)};
+  ret.m1 = LoadMaskBits(dh, bits_upper);
+  return ret;
+}
+
+template <class D, HWY_IF_V_SIZE_D(D, 32),
+          HWY_IF_T_SIZE_ONE_OF_D(D, (1 << 1) | (1 << 2))>
+HWY_API MFromD<D> LoadMaskBits(D d, const uint8_t* HWY_RESTRICT bits) {
+  const Half<decltype(d)> dh;
+  MFromD<D> ret;
+  ret.m0 = LoadMaskBits(dh, bits);
+  constexpr size_t kLanesPerHalf = 16 / sizeof(TFromD<D>);
+  constexpr size_t kBytesPerHalf = kLanesPerHalf / 8;
+  static_assert(kBytesPerHalf != 0, "Lane size <= 16 bits => at least 8 lanes");
+  ret.m1 = LoadMaskBits(dh, bits + kBytesPerHalf);
+  return ret;
+}
+
+// ------------------------------ Mask
+
+// `p` points to at least 8 writable bytes.
+template <class D, typename T = TFromD<D>,
+          HWY_IF_T_SIZE_ONE_OF(T, (1 << 4) | (1 << 8))>
+HWY_API size_t StoreMaskBits(D d, const Mask256<T> mask, uint8_t* bits) {
+  const Half<decltype(d)> dh;
+  StoreMaskBits(dh, mask.m0, bits);
+  const uint8_t lo = bits[0];
+  StoreMaskBits(dh, mask.m1, bits);
+  // If size=4, one 128-bit vector has 4 mask bits; otherwise 2 for size=8.
+  // Both halves fit in one byte's worth of mask bits.
+  constexpr size_t kBitsPerHalf = 16 / sizeof(T);
+  bits[0] = static_cast<uint8_t>(lo | (bits[0] << kBitsPerHalf));
+  return (kBitsPerHalf * 2 + 7) / 8;
+}
+
+template <class D, typename T = TFromD<D>,
+          HWY_IF_T_SIZE_ONE_OF(T, (1 << 1) | (1 << 2))>
+HWY_API size_t StoreMaskBits(D d, const Mask256<T> mask, uint8_t* bits) {
+  const Half<decltype(d)> dh;
+  constexpr size_t kLanesPerHalf = 16 / sizeof(T);
+  constexpr size_t kBytesPerHalf = kLanesPerHalf / 8;
+  static_assert(kBytesPerHalf != 0, "Lane size <= 16 bits => at least 8 lanes");
+  StoreMaskBits(dh, mask.m0, bits);
+  StoreMaskBits(dh, mask.m1, bits + kBytesPerHalf);
+  return kBytesPerHalf * 2;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API size_t CountTrue(D d, const Mask256<T> m) {
+  const Half<decltype(d)> dh;
+  return CountTrue(dh, m.m0) + CountTrue(dh, m.m1);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API bool AllFalse(D d, const Mask256<T> m) {
+  const Half<decltype(d)> dh;
+  return AllFalse(dh, m.m0) && AllFalse(dh, m.m1);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API bool AllTrue(D d, const Mask256<T> m) {
+  const Half<decltype(d)> dh;
+  return AllTrue(dh, m.m0) && AllTrue(dh, m.m1);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API size_t FindKnownFirstTrue(D d, const Mask256<T> mask) {
+  const Half<decltype(d)> dh;
+  const intptr_t lo = FindFirstTrue(dh, mask.m0);  // not known
+  constexpr size_t kLanesPerHalf = 16 / sizeof(T);
+  return lo >= 0 ? static_cast<size_t>(lo)
+                 : kLanesPerHalf + FindKnownFirstTrue(dh, mask.m1);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API intptr_t FindFirstTrue(D d, const Mask256<T> mask) {
+  const Half<decltype(d)> dh;
+  const intptr_t lo = FindFirstTrue(dh, mask.m0);
+  constexpr int kLanesPerHalf = 16 / sizeof(T);
+  if (lo >= 0) return lo;
+
+  const intptr_t hi = FindFirstTrue(dh, mask.m1);
+  return hi + (hi >= 0 ? kLanesPerHalf : 0);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API size_t FindKnownLastTrue(D d, const Mask256<T> mask) {
+  const Half<decltype(d)> dh;
+  const intptr_t hi = FindLastTrue(dh, mask.m1);  // not known
+  constexpr size_t kLanesPerHalf = 16 / sizeof(T);
+  return hi >= 0 ? kLanesPerHalf + static_cast<size_t>(hi)
+                 : FindKnownLastTrue(dh, mask.m0);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API intptr_t FindLastTrue(D d, const Mask256<T> mask) {
+  const Half<decltype(d)> dh;
+  constexpr int kLanesPerHalf = 16 / sizeof(T);
+  const intptr_t hi = FindLastTrue(dh, mask.m1);
+  return hi >= 0 ? kLanesPerHalf + hi : FindLastTrue(dh, mask.m0);
+}
+
+// ------------------------------ CompressStore
+template <class D, typename T = TFromD<D>>
+HWY_API size_t CompressStore(Vec256<T> v, const Mask256<T> mask, D d,
+                             T* HWY_RESTRICT unaligned) {
+  const Half<decltype(d)> dh;
+  const size_t count = CompressStore(v.v0, mask.m0, dh, unaligned);
+  const size_t count2 = CompressStore(v.v1, mask.m1, dh, unaligned + count);
+  return count + count2;
+}
+
+// ------------------------------ CompressBlendedStore
+template <class D, typename T = TFromD<D>>
+HWY_API size_t CompressBlendedStore(Vec256<T> v, const Mask256<T> m, D d,
+                                    T* HWY_RESTRICT unaligned) {
+  const Half<decltype(d)> dh;
+  const size_t count = CompressBlendedStore(v.v0, m.m0, dh, unaligned);
+  const size_t count2 = CompressBlendedStore(v.v1, m.m1, dh, unaligned + count);
+  return count + count2;
+}
+
+// ------------------------------ CompressBitsStore
+
+template <class D, typename T = TFromD<D>>
+HWY_API size_t CompressBitsStore(Vec256<T> v, const uint8_t* HWY_RESTRICT bits,
+                                 D d, T* HWY_RESTRICT unaligned) {
+  const Mask256<T> m = LoadMaskBits(d, bits);
+  return CompressStore(v, m, d, unaligned);
+}
+
+// ------------------------------ Compress
+template <typename T>
+HWY_API Vec256<T> Compress(const Vec256<T> v, const Mask256<T> mask) {
+  const DFromV<decltype(v)> d;
+  alignas(32) T lanes[32 / sizeof(T)] = {};
+  (void)CompressStore(v, mask, d, lanes);
+  return Load(d, lanes);
+}
+
+// ------------------------------ CompressNot
+template <typename T>
+HWY_API Vec256<T> CompressNot(Vec256<T> v, const Mask256<T> mask) {
+  return Compress(v, Not(mask));
+}
+
+// ------------------------------ CompressBlocksNot
+HWY_API Vec256<uint64_t> CompressBlocksNot(Vec256<uint64_t> v,
+                                           Mask256<uint64_t> mask) {
+  const Full128<uint64_t> dh;
+  // Because the non-selected (mask=1) blocks are undefined, we can return the
+  // input unless mask = 01, in which case we must bring down the upper block.
+  return AllTrue(dh, AndNot(mask.m1, mask.m0)) ? SwapAdjacentBlocks(v) : v;
+}
+
+// ------------------------------ CompressBits
+template <typename T>
+HWY_API Vec256<T> CompressBits(Vec256<T> v, const uint8_t* HWY_RESTRICT bits) {
+  const Mask256<T> m = LoadMaskBits(DFromV<decltype(v)>(), bits);
+  return Compress(v, m);
+}
+
+// ------------------------------ Expand
+template <typename T>
+HWY_API Vec256<T> Expand(const Vec256<T> v, const Mask256<T> mask) {
+  Vec256<T> ret;
+  const Full256<T> d;
+  const Half<decltype(d)> dh;
+  alignas(32) T lanes[32 / sizeof(T)] = {};
+  Store(v, d, lanes);
+  ret.v0 = Expand(v.v0, mask.m0);
+  ret.v1 = Expand(LoadU(dh, lanes + CountTrue(dh, mask.m0)), mask.m1);
+  return ret;
+}
+
+// ------------------------------ LoadExpand
+template <class D, HWY_IF_V_SIZE_D(D, 32)>
+HWY_API VFromD<D> LoadExpand(MFromD<D> mask, D d,
+                             const TFromD<D>* HWY_RESTRICT unaligned) {
+  return Expand(LoadU(d, unaligned), mask);
+}
+
+// ------------------------------ LoadInterleaved3/4
+
+// Implemented in generic_ops, we just overload LoadTransposedBlocks3/4.
+
+namespace detail {
+
+// Input:
+// 1 0 (<- first block of unaligned)
+// 3 2
+// 5 4
+// Output:
+// 3 0
+// 4 1
+// 5 2
+template <class D, typename T = TFromD<D>>
+HWY_API void LoadTransposedBlocks3(D d, const T* HWY_RESTRICT unaligned,
+                                   Vec256<T>& A, Vec256<T>& B, Vec256<T>& C) {
+  const Vec256<T> v10 = LoadU(d, unaligned + 0 * MaxLanes(d));
+  const Vec256<T> v32 = LoadU(d, unaligned + 1 * MaxLanes(d));
+  const Vec256<T> v54 = LoadU(d, unaligned + 2 * MaxLanes(d));
+
+  A = ConcatUpperLower(d, v32, v10);
+  B = ConcatLowerUpper(d, v54, v10);
+  C = ConcatUpperLower(d, v54, v32);
+}
+
+// Input (128-bit blocks):
+// 1 0 (first block of unaligned)
+// 3 2
+// 5 4
+// 7 6
+// Output:
+// 4 0 (LSB of A)
+// 5 1
+// 6 2
+// 7 3
+template <class D, typename T = TFromD<D>>
+HWY_API void LoadTransposedBlocks4(D d, const T* HWY_RESTRICT unaligned,
+                                   Vec256<T>& vA, Vec256<T>& vB, Vec256<T>& vC,
+                                   Vec256<T>& vD) {
+  const Vec256<T> v10 = LoadU(d, unaligned + 0 * MaxLanes(d));
+  const Vec256<T> v32 = LoadU(d, unaligned + 1 * MaxLanes(d));
+  const Vec256<T> v54 = LoadU(d, unaligned + 2 * MaxLanes(d));
+  const Vec256<T> v76 = LoadU(d, unaligned + 3 * MaxLanes(d));
+
+  vA = ConcatLowerLower(d, v54, v10);
+  vB = ConcatUpperUpper(d, v54, v10);
+  vC = ConcatLowerLower(d, v76, v32);
+  vD = ConcatUpperUpper(d, v76, v32);
+}
+
+}  // namespace detail
+
+// ------------------------------ StoreInterleaved2/3/4 (ConcatUpperLower)
+
+// Implemented in generic_ops, we just overload StoreTransposedBlocks2/3/4.
+
+namespace detail {
+
+// Input (128-bit blocks):
+// 2 0 (LSB of i)
+// 3 1
+// Output:
+// 1 0
+// 3 2
+template <class D, typename T = TFromD<D>>
+HWY_API void StoreTransposedBlocks2(Vec256<T> i, Vec256<T> j, D d,
+                                    T* HWY_RESTRICT unaligned) {
+  const Vec256<T> out0 = ConcatLowerLower(d, j, i);
+  const Vec256<T> out1 = ConcatUpperUpper(d, j, i);
+  StoreU(out0, d, unaligned + 0 * MaxLanes(d));
+  StoreU(out1, d, unaligned + 1 * MaxLanes(d));
+}
+
+// Input (128-bit blocks):
+// 3 0 (LSB of i)
+// 4 1
+// 5 2
+// Output:
+// 1 0
+// 3 2
+// 5 4
+template <class D, typename T = TFromD<D>>
+HWY_API void StoreTransposedBlocks3(Vec256<T> i, Vec256<T> j, Vec256<T> k, D d,
+                                    T* HWY_RESTRICT unaligned) {
+  const Vec256<T> out0 = ConcatLowerLower(d, j, i);
+  const Vec256<T> out1 = ConcatUpperLower(d, i, k);
+  const Vec256<T> out2 = ConcatUpperUpper(d, k, j);
+  StoreU(out0, d, unaligned + 0 * MaxLanes(d));
+  StoreU(out1, d, unaligned + 1 * MaxLanes(d));
+  StoreU(out2, d, unaligned + 2 * MaxLanes(d));
+}
+
+// Input (128-bit blocks):
+// 4 0 (LSB of i)
+// 5 1
+// 6 2
+// 7 3
+// Output:
+// 1 0
+// 3 2
+// 5 4
+// 7 6
+template <class D, typename T = TFromD<D>>
+HWY_API void StoreTransposedBlocks4(Vec256<T> i, Vec256<T> j, Vec256<T> k,
+                                    Vec256<T> l, D d,
+                                    T* HWY_RESTRICT unaligned) {
+  // Write lower halves, then upper.
+  const Vec256<T> out0 = ConcatLowerLower(d, j, i);
+  const Vec256<T> out1 = ConcatLowerLower(d, l, k);
+  StoreU(out0, d, unaligned + 0 * MaxLanes(d));
+  StoreU(out1, d, unaligned + 1 * MaxLanes(d));
+  const Vec256<T> out2 = ConcatUpperUpper(d, j, i);
+  const Vec256<T> out3 = ConcatUpperUpper(d, l, k);
+  StoreU(out2, d, unaligned + 2 * MaxLanes(d));
+  StoreU(out3, d, unaligned + 3 * MaxLanes(d));
+}
+
+}  // namespace detail
+
+// ------------------------------ WidenMulPairwiseAdd
+template <class D32, typename T16, typename T32 = TFromD<D32>>
+HWY_API Vec256<T32> WidenMulPairwiseAdd(D32 d32, Vec256<T16> a,
+                                             Vec256<T16> b) {
+  const Half<decltype(d32)> d32h;
+  a.v0 = WidenMulPairwiseAdd(d32h, a.v0, b.v0);
+  a.v1 = WidenMulPairwiseAdd(d32h, a.v1, b.v1);
+  return a;
+}
+
+// ------------------------------ ReorderWidenMulAccumulate
+template <class D32, typename T16, typename T32 = TFromD<D32>>
+HWY_API Vec256<T32> ReorderWidenMulAccumulate(D32 d32, Vec256<T16> a,
+                                              Vec256<T16> b, Vec256<T32> sum0,
+                                              Vec256<T32>& sum1) {
+  const Half<decltype(d32)> d32h;
+  sum0.v0 = ReorderWidenMulAccumulate(d32h, a.v0, b.v0, sum0.v0, sum1.v0);
+  sum0.v1 = ReorderWidenMulAccumulate(d32h, a.v1, b.v1, sum0.v1, sum1.v1);
+  return sum0;
+}
+
+// ------------------------------ RearrangeToOddPlusEven
+template <typename TW>
+HWY_API Vec256<TW> RearrangeToOddPlusEven(Vec256<TW> sum0, Vec256<TW> sum1) {
+  sum0.v0 = RearrangeToOddPlusEven(sum0.v0, sum1.v0);
+  sum0.v1 = RearrangeToOddPlusEven(sum0.v1, sum1.v1);
+  return sum0;
+}
+
+// ------------------------------ Reductions
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> SumOfLanes(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  const Vec128<T> lo = SumOfLanes(dh, Add(v.v0, v.v1));
+  return Combine(d, lo, lo);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API T ReduceSum(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  return ReduceSum(dh, Add(v.v0, v.v1));
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> MinOfLanes(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  const Vec128<T> lo = MinOfLanes(dh, Min(v.v0, v.v1));
+  return Combine(d, lo, lo);
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_API Vec256<T> MaxOfLanes(D d, const Vec256<T> v) {
+  const Half<decltype(d)> dh;
+  const Vec128<T> lo = MaxOfLanes(dh, Max(v.v0, v.v1));
+  return Combine(d, lo, lo);
+}
+
+// ------------------------------ Lt128
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Lt128(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Lt128(dh, a.v0, b.v0);
+  ret.m1 = Lt128(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Lt128Upper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Lt128Upper(dh, a.v0, b.v0);
+  ret.m1 = Lt128Upper(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Eq128(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Eq128(dh, a.v0, b.v0);
+  ret.m1 = Eq128(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Eq128Upper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Eq128Upper(dh, a.v0, b.v0);
+  ret.m1 = Eq128Upper(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Ne128(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Ne128(dh, a.v0, b.v0);
+  ret.m1 = Ne128(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Mask256<T> Ne128Upper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Mask256<T> ret;
+  ret.m0 = Ne128Upper(dh, a.v0, b.v0);
+  ret.m1 = Ne128Upper(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Vec256<T> Min128(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Min128(dh, a.v0, b.v0);
+  ret.v1 = Min128(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Vec256<T> Max128(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Max128(dh, a.v0, b.v0);
+  ret.v1 = Max128(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Vec256<T> Min128Upper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Min128Upper(dh, a.v0, b.v0);
+  ret.v1 = Min128Upper(dh, a.v1, b.v1);
+  return ret;
+}
+
+template <class D, typename T = TFromD<D>>
+HWY_INLINE Vec256<T> Max128Upper(D d, Vec256<T> a, Vec256<T> b) {
+  const Half<decltype(d)> dh;
+  Vec256<T> ret;
+  ret.v0 = Max128Upper(dh, a.v0, b.v0);
+  ret.v1 = Max128Upper(dh, a.v1, b.v1);
+  return ret;
+}
+
+// NOLINTNEXTLINE(google-readability-namespace-comments)
+}  // namespace HWY_NAMESPACE
+}  // namespace hwy
+HWY_AFTER_NAMESPACE();