ops/shared-inl.h
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// Copyright 2020 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.
// Per-target definitions shared by ops/*.h and user code.
// We are covered by the highway.h include guard, but generic_ops-inl.h
// includes this again #if HWY_IDE.
#if defined(HIGHWAY_HWY_OPS_SHARED_TOGGLE) == \
defined(HWY_TARGET_TOGGLE)
#ifdef HIGHWAY_HWY_OPS_SHARED_TOGGLE
#undef HIGHWAY_HWY_OPS_SHARED_TOGGLE
#else
#define HIGHWAY_HWY_OPS_SHARED_TOGGLE
#endif
#ifndef HWY_NO_LIBCXX
#include <math.h>
#endif
#include "hwy/base.h"
// Separate header because foreach_target.h re-enables its include guard.
#include "hwy/ops/set_macros-inl.h"
// Relies on the external include guard in highway.h.
HWY_BEFORE_NAMESPACE();
namespace hwy {
namespace HWY_NAMESPACE {
// Highway operations are implemented as overloaded functions selected using an
// internal-only tag type D := Simd<T, N, kPow2>. T is the lane type. kPow2 is a
// shift count applied to scalable vectors. Instead of referring to Simd<>
// directly, users create D via aliases ScalableTag<T[, kPow2]>() (defaults to a
// full vector, or fractions/groups if the argument is negative/positive),
// CappedTag<T, kLimit> or FixedTag<T, kNumLanes>. The actual number of lanes is
// Lanes(D()), a power of two. For scalable vectors, N is either HWY_LANES or a
// cap. For constexpr-size vectors, N is the actual number of lanes. This
// ensures Half<Full512<T>> is the same type as Full256<T>, as required by x86.
template <typename Lane, size_t N, int kPow2>
struct Simd {
constexpr Simd() = default;
using T = Lane;
static_assert((N & (N - 1)) == 0 && N != 0, "N must be a power of two");
// Only for use by MaxLanes, required by MSVC. Cannot be enum because GCC
// warns when using enums and non-enums in the same expression. Cannot be
// static constexpr function (another MSVC limitation).
static constexpr size_t kPrivateN = N;
static constexpr int kPrivatePow2 = kPow2;
template <typename NewT>
static constexpr size_t NewN() {
// Round up to correctly handle scalars with N=1.
return (N * sizeof(T) + sizeof(NewT) - 1) / sizeof(NewT);
}
#if HWY_HAVE_SCALABLE
template <typename NewT>
static constexpr int Pow2Ratio() {
return (sizeof(NewT) > sizeof(T))
? static_cast<int>(CeilLog2(sizeof(NewT) / sizeof(T)))
: -static_cast<int>(CeilLog2(sizeof(T) / sizeof(NewT)));
}
#endif
// Widening/narrowing ops change the number of lanes and/or their type.
// To initialize such vectors, we need the corresponding tag types:
// PromoteTo/DemoteTo() with another lane type, but same number of lanes.
#if HWY_HAVE_SCALABLE
template <typename NewT>
using Rebind = Simd<NewT, N, kPow2 + Pow2Ratio<NewT>()>;
#else
template <typename NewT>
using Rebind = Simd<NewT, N, kPow2>;
#endif
// Change lane type while keeping the same vector size, e.g. for MulEven.
template <typename NewT>
using Repartition = Simd<NewT, NewN<NewT>(), kPow2>;
// Half the lanes while keeping the same lane type, e.g. for LowerHalf.
// Round up to correctly handle scalars with N=1.
#if HWY_HAVE_SCALABLE
// Reducing the cap (N) is required for SVE - if N is the limiter for f32xN,
// then we expect Half<Rebind<u16>> to have N/2 lanes (rounded up).
using Half = Simd<T, (N + 1) / 2, kPow2 - 1>;
#else
using Half = Simd<T, (N + 1) / 2, kPow2>;
#endif
// Twice the lanes while keeping the same lane type, e.g. for Combine.
#if HWY_HAVE_SCALABLE
using Twice = Simd<T, 2 * N, kPow2 + 1>;
#else
using Twice = Simd<T, 2 * N, kPow2>;
#endif
};
namespace detail {
template <typename T, size_t N, int kPow2>
constexpr bool IsFull(Simd<T, N, kPow2> /* d */) {
return N == HWY_LANES(T) && kPow2 == 0;
}
// Returns the number of lanes (possibly zero) after applying a shift:
// - 0: no change;
// - [1,3]: a group of 2,4,8 [fractional] vectors;
// - [-3,-1]: a fraction of a vector from 1/8 to 1/2.
constexpr size_t ScaleByPower(size_t N, int pow2) {
#if HWY_TARGET == HWY_RVV
return pow2 >= 0 ? (N << pow2) : (N >> (-pow2));
#else
return pow2 >= 0 ? N : (N >> (-pow2));
#endif
}
// Struct wrappers enable validation of arguments via static_assert.
template <typename T, int kPow2>
struct ScalableTagChecker {
static_assert(-3 <= kPow2 && kPow2 <= 3, "Fraction must be 1/8 to 8");
#if HWY_TARGET == HWY_RVV
// Only RVV supports register groups.
using type = Simd<T, HWY_LANES(T), kPow2>;
#elif HWY_HAVE_SCALABLE
// For SVE[2], only allow full or fractions.
using type = Simd<T, HWY_LANES(T), HWY_MIN(kPow2, 0)>;
#elif HWY_TARGET == HWY_SCALAR
using type = Simd<T, /*N=*/1, 0>;
#else
// Only allow full or fractions.
using type = Simd<T, ScaleByPower(HWY_LANES(T), HWY_MIN(kPow2, 0)), 0>;
#endif
};
template <typename T, size_t kLimit>
struct CappedTagChecker {
static_assert(kLimit != 0, "Does not make sense to have zero lanes");
// Safely handle non-power-of-two inputs by rounding down, which is allowed by
// CappedTag. Otherwise, Simd<T, 3, 0> would static_assert.
static constexpr size_t kLimitPow2 = size_t{1} << hwy::FloorLog2(kLimit);
using type = Simd<T, HWY_MIN(kLimitPow2, HWY_LANES(T)), 0>;
};
template <typename T, size_t kNumLanes>
struct FixedTagChecker {
static_assert(kNumLanes != 0, "Does not make sense to have zero lanes");
static_assert(kNumLanes <= HWY_LANES(T), "Too many lanes");
using type = Simd<T, kNumLanes, 0>;
};
} // namespace detail
// Alias for a tag describing a full vector (kPow2 == 0: the most common usage,
// e.g. 1D loops where the application does not care about the vector size) or a
// fraction/multiple of one. Multiples are the same as full vectors for all
// targets except RVV. Fractions (kPow2 < 0) are useful as the argument/return
// value of type promotion and demotion.
template <typename T, int kPow2 = 0>
using ScalableTag = typename detail::ScalableTagChecker<T, kPow2>::type;
// Alias for a tag describing a vector with *up to* kLimit active lanes, even on
// targets with scalable vectors and HWY_SCALAR. The runtime lane count
// `Lanes(tag)` may be less than kLimit, and is 1 on HWY_SCALAR. This alias is
// typically used for 1D loops with a relatively low application-defined upper
// bound, e.g. for 8x8 DCTs. However, it is better if data structures are
// designed to be vector-length-agnostic (e.g. a hybrid SoA where there are
// chunks of `M >= MaxLanes(d)` DC components followed by M AC1, .., and M AC63;
// this would enable vector-length-agnostic loops using ScalableTag).
template <typename T, size_t kLimit>
using CappedTag = typename detail::CappedTagChecker<T, kLimit>::type;
// Alias for a tag describing a vector with *exactly* kNumLanes active lanes,
// even on targets with scalable vectors. Requires `kNumLanes` to be a power of
// two not exceeding `HWY_LANES(T)`.
//
// NOTE: if the application does not need to support HWY_SCALAR (+), use this
// instead of CappedTag to emphasize that there will be exactly kNumLanes lanes.
// This is useful for data structures that rely on exactly 128-bit SIMD, but
// these are discouraged because they cannot benefit from wider vectors.
// Instead, applications would ideally define a larger problem size and loop
// over it with the (unknown size) vectors from ScalableTag.
//
// + e.g. if the baseline is known to support SIMD, or the application requires
// ops such as TableLookupBytes not supported by HWY_SCALAR.
template <typename T, size_t kNumLanes>
using FixedTag = typename detail::FixedTagChecker<T, kNumLanes>::type;
template <class D>
using TFromD = typename D::T;
// Tag for the same number of lanes as D, but with the LaneType T.
template <class T, class D>
using Rebind = typename D::template Rebind<T>;
template <class D>
using RebindToSigned = Rebind<MakeSigned<TFromD<D>>, D>;
template <class D>
using RebindToUnsigned = Rebind<MakeUnsigned<TFromD<D>>, D>;
template <class D>
using RebindToFloat = Rebind<MakeFloat<TFromD<D>>, D>;
// Tag for the same total size as D, but with the LaneType T.
template <class T, class D>
using Repartition = typename D::template Repartition<T>;
template <class D>
using RepartitionToWide = Repartition<MakeWide<TFromD<D>>, D>;
template <class D>
using RepartitionToNarrow = Repartition<MakeNarrow<TFromD<D>>, D>;
// Tag for the same lane type as D, but half the lanes.
template <class D>
using Half = typename D::Half;
// Tag for the same lane type as D, but twice the lanes.
template <class D>
using Twice = typename D::Twice;
template <typename T>
using Full16 = Simd<T, 2 / sizeof(T), 0>;
template <typename T>
using Full32 = Simd<T, 4 / sizeof(T), 0>;
template <typename T>
using Full64 = Simd<T, 8 / sizeof(T), 0>;
template <typename T>
using Full128 = Simd<T, 16 / sizeof(T), 0>;
// Same as base.h macros but with a Simd<T, N, kPow2> argument instead of T.
#define HWY_IF_UNSIGNED_D(D) HWY_IF_UNSIGNED(TFromD<D>)
#define HWY_IF_SIGNED_D(D) HWY_IF_SIGNED(TFromD<D>)
#define HWY_IF_FLOAT_D(D) HWY_IF_FLOAT(TFromD<D>)
#define HWY_IF_NOT_FLOAT_D(D) HWY_IF_NOT_FLOAT(TFromD<D>)
#define HWY_IF_LANE_SIZE_D(D, bytes) HWY_IF_LANE_SIZE(TFromD<D>, bytes)
#define HWY_IF_NOT_LANE_SIZE_D(D, bytes) HWY_IF_NOT_LANE_SIZE(TFromD<D>, bytes)
#define HWY_IF_LANE_SIZE_ONE_OF_D(D, bit_array) \
HWY_IF_LANE_SIZE_ONE_OF(TFromD<D>, bit_array)
// MSVC workaround: use PrivateN directly instead of MaxLanes.
#define HWY_IF_LT128_D(D) \
hwy::EnableIf<D::kPrivateN * sizeof(TFromD<D>) < 16>* = nullptr
#define HWY_IF_GE128_D(D) \
hwy::EnableIf<D::kPrivateN * sizeof(TFromD<D>) >= 16>* = nullptr
// Same, but with a vector argument. ops/*-inl.h define their own TFromV.
#define HWY_IF_UNSIGNED_V(V) HWY_IF_UNSIGNED(TFromV<V>)
#define HWY_IF_SIGNED_V(V) HWY_IF_SIGNED(TFromV<V>)
#define HWY_IF_FLOAT_V(V) HWY_IF_FLOAT(TFromV<V>)
#define HWY_IF_LANE_SIZE_V(V, bytes) HWY_IF_LANE_SIZE(TFromV<V>, bytes)
#define HWY_IF_NOT_LANE_SIZE_V(V, bytes) HWY_IF_NOT_LANE_SIZE(TFromV<V>, bytes)
#define HWY_IF_LANE_SIZE_ONE_OF_V(V, bit_array) \
HWY_IF_LANE_SIZE_ONE_OF(TFromV<V>, bit_array)
template <class D>
HWY_INLINE HWY_MAYBE_UNUSED constexpr int Pow2(D /* d */) {
return D::kPrivatePow2;
}
// MSVC requires the explicit <D>.
#define HWY_IF_POW2_GE(D, MIN) hwy::EnableIf<Pow2<D>(D()) >= (MIN)>* = nullptr
#if HWY_HAVE_SCALABLE
// Upper bound on the number of lanes. Intended for template arguments and
// reducing code size (e.g. for SSE4, we know at compile-time that vectors will
// not exceed 16 bytes). WARNING: this may be a loose bound, use Lanes() as the
// actual size for allocating storage. WARNING: MSVC might not be able to deduce
// arguments if this is used in EnableIf. See HWY_IF_LT128_D above.
template <class D>
HWY_INLINE HWY_MAYBE_UNUSED constexpr size_t MaxLanes(D) {
return detail::ScaleByPower(HWY_MIN(D::kPrivateN, HWY_LANES(TFromD<D>)),
D::kPrivatePow2);
}
#else
// Workaround for MSVC 2017: T,N,kPow2 argument deduction fails, so returning N
// is not an option, nor does a member function work.
template <class D>
HWY_INLINE HWY_MAYBE_UNUSED constexpr size_t MaxLanes(D) {
return D::kPrivateN;
}
// (Potentially) non-constant actual size of the vector at runtime, subject to
// the limit imposed by the Simd. Useful for advancing loop counters.
// Targets with scalable vectors define this themselves.
template <typename T, size_t N, int kPow2>
HWY_INLINE HWY_MAYBE_UNUSED size_t Lanes(Simd<T, N, kPow2>) {
return N;
}
#endif // !HWY_HAVE_SCALABLE
// NOTE: GCC generates incorrect code for vector arguments to non-inlined
// functions in two situations:
// - on Windows and GCC 10.3, passing by value crashes due to unaligned loads:
// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54412.
// - on ARM64 and GCC 9.3.0 or 11.2.1, passing by value causes many (but not
// all) tests to fail.
//
// We therefore pass by const& only on GCC and (Windows or ARM64). This alias
// must be used for all vector/mask parameters of functions marked HWY_NOINLINE,
// and possibly also other functions that are not inlined.
#if HWY_COMPILER_GCC_ACTUAL && (HWY_OS_WIN || HWY_ARCH_ARM_A64)
template <class V>
using VecArg = const V&;
#else
template <class V>
using VecArg = V;
#endif
// NOLINTNEXTLINE(google-readability-namespace-comments)
} // namespace HWY_NAMESPACE
} // namespace hwy
HWY_AFTER_NAMESPACE();
#endif // HIGHWAY_HWY_OPS_SHARED_TOGGLE
base.h
HWY_MIN
#define HWY_MIN(a, b)
Definition base.h:134
HWY_INLINE
#define HWY_INLINE
Definition base.h:70
HWY_MAYBE_UNUSED
#define HWY_MAYBE_UNUSED
Definition base.h:82
hwy::HWY_NAMESPACE::detail::ScaleByPower
constexpr size_t ScaleByPower(size_t N, int pow2)
Definition ops/shared-inl.h:123
hwy::HWY_NAMESPACE::detail::IsFull
constexpr bool IsFull(Simd< T, N, kPow2 >)
Definition ops/shared-inl.h:115
hwy::HWY_NAMESPACE::VecArg
V VecArg
Definition ops/shared-inl.h:324
hwy::HWY_NAMESPACE::RepartitionToWide
Repartition< MakeWide< TFromD< D > >, D > RepartitionToWide
Definition ops/shared-inl.h:221
hwy::HWY_NAMESPACE::MaxLanes
HWY_INLINE HWY_MAYBE_UNUSED constexpr size_t MaxLanes(D)
Definition ops/shared-inl.h:295
hwy::HWY_NAMESPACE::RebindToUnsigned
Rebind< MakeUnsigned< TFromD< D > >, D > RebindToUnsigned
Definition ops/shared-inl.h:212
hwy::HWY_NAMESPACE::CappedTag
typename detail::CappedTagChecker< T, kLimit >::type CappedTag
Definition ops/shared-inl.h:184
hwy::HWY_NAMESPACE::RebindToFloat
Rebind< MakeFloat< TFromD< D > >, D > RebindToFloat
Definition ops/shared-inl.h:214
hwy::HWY_NAMESPACE::Twice
typename D::Twice Twice
Definition ops/shared-inl.h:231
hwy::HWY_NAMESPACE::RebindToSigned
Rebind< MakeSigned< TFromD< D > >, D > RebindToSigned
Definition ops/shared-inl.h:210
hwy::HWY_NAMESPACE::Lanes
HWY_API constexpr size_t Lanes(Simd< T, N, kPow2 >)
Definition arm_sve-inl.h:243
hwy::HWY_NAMESPACE::RepartitionToNarrow
Repartition< MakeNarrow< TFromD< D > >, D > RepartitionToNarrow
Definition ops/shared-inl.h:223
hwy::HWY_NAMESPACE::ScalableTag
typename detail::ScalableTagChecker< T, kPow2 >::type ScalableTag
Definition ops/shared-inl.h:173
hwy::HWY_NAMESPACE::Rebind
typename D::template Rebind< T > Rebind
Definition ops/shared-inl.h:207
hwy::HWY_NAMESPACE::Pow2
HWY_INLINE HWY_MAYBE_UNUSED constexpr int Pow2(D)
Definition ops/shared-inl.h:271
hwy::HWY_NAMESPACE::FixedTag
typename detail::FixedTagChecker< T, kNumLanes >::type FixedTag
Definition ops/shared-inl.h:200
hwy::HWY_NAMESPACE::Half
typename D::Half Half
Definition ops/shared-inl.h:227
hwy::HWY_NAMESPACE::Repartition
typename D::template Repartition< T > Repartition
Definition ops/shared-inl.h:218
hwy::HWY_NAMESPACE::N
N
Definition rvv-inl.h:1998
hwy::HWY_NAMESPACE::TFromD
typename D::T TFromD
Definition ops/shared-inl.h:203
hwy
Definition aligned_allocator.h:27
hwy::FloorLog2
constexpr size_t FloorLog2(TI x)
Definition base.h:892
hwy::CeilLog2
constexpr size_t CeilLog2(TI x)
Definition base.h:899
HWY_AFTER_NAMESPACE
HWY_AFTER_NAMESPACE()
HWY_BEFORE_NAMESPACE
HWY_BEFORE_NAMESPACE()
set_macros-inl.h
HWY_LANES
#define HWY_LANES(T)
Definition set_macros-inl.h:85
HWY_NAMESPACE
#define HWY_NAMESPACE
Definition set_macros-inl.h:82
hwy::HWY_NAMESPACE::Simd
Definition ops/shared-inl.h:52
hwy::HWY_NAMESPACE::Simd::Simd
constexpr Simd()=default
hwy::HWY_NAMESPACE::Simd::Rebind
Simd< NewT, N, kPow2 > Rebind
Definition ops/shared-inl.h:87
hwy::HWY_NAMESPACE::Simd::NewN
static constexpr size_t NewN()
Definition ops/shared-inl.h:64
hwy::HWY_NAMESPACE::Simd::kPrivatePow2
static constexpr int kPrivatePow2
Definition ops/shared-inl.h:61
hwy::HWY_NAMESPACE::Simd::kPrivateN
static constexpr size_t kPrivateN
Definition ops/shared-inl.h:60
hwy::HWY_NAMESPACE::Simd::T
Lane T
Definition ops/shared-inl.h:54
hwy::HWY_NAMESPACE::detail::CappedTagChecker
Definition ops/shared-inl.h:150
hwy::HWY_NAMESPACE::detail::CappedTagChecker::kLimitPow2
static constexpr size_t kLimitPow2
Definition ops/shared-inl.h:154
hwy::HWY_NAMESPACE::detail::FixedTagChecker
Definition ops/shared-inl.h:159
hwy::HWY_NAMESPACE::detail::ScalableTagChecker
Definition ops/shared-inl.h:133