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Diffstat (limited to 'third_party/highway/hwy/examples/benchmark.cc')
| -rw-r--r-- | third_party/highway/hwy/examples/benchmark.cc | 255 |
1 files changed, 255 insertions, 0 deletions
diff --git a/third_party/highway/hwy/examples/benchmark.cc b/third_party/highway/hwy/examples/benchmark.cc new file mode 100644 index 0000000000..55afd3bcca --- /dev/null +++ b/third_party/highway/hwy/examples/benchmark.cc @@ -0,0 +1,255 @@ +// 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. + +#ifndef __STDC_FORMAT_MACROS +#define __STDC_FORMAT_MACROS // before inttypes.h +#endif +#include <inttypes.h> +#include <stddef.h> +#include <stdint.h> +#include <stdio.h> + +#include <cmath> // std::abs +#include <memory> +#include <numeric> // std::iota, std::inner_product + +#undef HWY_TARGET_INCLUDE +#define HWY_TARGET_INCLUDE "hwy/examples/benchmark.cc" +#include "hwy/foreach_target.h" // IWYU pragma: keep + +// Must come after foreach_target.h to avoid redefinition errors. +#include "hwy/aligned_allocator.h" +#include "hwy/highway.h" +#include "hwy/nanobenchmark.h" + +HWY_BEFORE_NAMESPACE(); +namespace hwy { +namespace HWY_NAMESPACE { + +// These templates are not found via ADL. +#if HWY_TARGET != HWY_SCALAR +using hwy::HWY_NAMESPACE::CombineShiftRightLanes; +#endif + +class TwoArray { + public: + // Must be a multiple of the vector lane count * 8. + static size_t NumItems() { return 3456; } + + TwoArray() + : a_(AllocateAligned<float>(NumItems() * 2)), b_(a_.get() + NumItems()) { + // = 1, but compiler doesn't know + const float init = static_cast<float>(Unpredictable1()); + std::iota(a_.get(), a_.get() + NumItems(), init); + std::iota(b_, b_ + NumItems(), init); + } + + protected: + AlignedFreeUniquePtr<float[]> a_; + float* b_; +}; + +// Measures durations, verifies results, prints timings. +template <class Benchmark> +void RunBenchmark(const char* caption) { + printf("%10s: ", caption); + const size_t kNumInputs = 1; + const size_t num_items = Benchmark::NumItems() * size_t(Unpredictable1()); + const FuncInput inputs[kNumInputs] = {num_items}; + Result results[kNumInputs]; + + Benchmark benchmark; + + Params p; + p.verbose = false; + p.max_evals = 7; + p.target_rel_mad = 0.002; + const size_t num_results = MeasureClosure( + [&benchmark](const FuncInput input) { return benchmark(input); }, inputs, + kNumInputs, results, p); + if (num_results != kNumInputs) { + fprintf(stderr, "MeasureClosure failed.\n"); + } + + benchmark.Verify(num_items); + + for (size_t i = 0; i < num_results; ++i) { + const double cycles_per_item = + results[i].ticks / static_cast<double>(results[i].input); + const double mad = results[i].variability * cycles_per_item; + printf("%6" PRIu64 ": %6.3f (+/- %5.3f)\n", + static_cast<uint64_t>(results[i].input), cycles_per_item, mad); + } +} + +void Intro() { + const float in[16] = {1, 2, 3, 4, 5, 6}; + float out[16]; + const ScalableTag<float> d; // largest possible vector + for (size_t i = 0; i < 16; i += Lanes(d)) { + const auto vec = LoadU(d, in + i); // no alignment requirement + auto result = Mul(vec, vec); + result = Add(result, result); // can update if not const + StoreU(result, d, out + i); + } + printf("\nF(x)->2*x^2, F(%.0f) = %.1f\n", in[2], out[2]); +} + +// BEGINNER: dot product +// 0.4 cyc/float = bronze, 0.25 = silver, 0.15 = gold! +class BenchmarkDot : public TwoArray { + public: + BenchmarkDot() : dot_{-1.0f} {} + + FuncOutput operator()(const size_t num_items) { + const ScalableTag<float> d; + const size_t N = Lanes(d); + using V = decltype(Zero(d)); + // Compiler doesn't make independent sum* accumulators, so unroll manually. + // We cannot use an array because V might be a sizeless type. For reasonable + // code, we unroll 4x, but 8x might help (2 FMA ports * 4 cycle latency). + V sum0 = Zero(d); + V sum1 = Zero(d); + V sum2 = Zero(d); + V sum3 = Zero(d); + const float* const HWY_RESTRICT pa = &a_[0]; + const float* const HWY_RESTRICT pb = b_; + for (size_t i = 0; i < num_items; i += 4 * N) { + const auto a0 = Load(d, pa + i + 0 * N); + const auto b0 = Load(d, pb + i + 0 * N); + sum0 = MulAdd(a0, b0, sum0); + const auto a1 = Load(d, pa + i + 1 * N); + const auto b1 = Load(d, pb + i + 1 * N); + sum1 = MulAdd(a1, b1, sum1); + const auto a2 = Load(d, pa + i + 2 * N); + const auto b2 = Load(d, pb + i + 2 * N); + sum2 = MulAdd(a2, b2, sum2); + const auto a3 = Load(d, pa + i + 3 * N); + const auto b3 = Load(d, pb + i + 3 * N); + sum3 = MulAdd(a3, b3, sum3); + } + // Reduction tree: sum of all accumulators by pairs into sum0. + sum0 = Add(sum0, sum1); + sum2 = Add(sum2, sum3); + sum0 = Add(sum0, sum2); + dot_ = GetLane(SumOfLanes(d, sum0)); + return static_cast<FuncOutput>(dot_); + } + void Verify(size_t num_items) { + if (dot_ == -1.0f) { + fprintf(stderr, "Dot: must call Verify after benchmark"); + abort(); + } + + const float expected = + std::inner_product(a_.get(), a_.get() + num_items, b_, 0.0f); + const float rel_err = std::abs(expected - dot_) / expected; + if (rel_err > 1.1E-6f) { + fprintf(stderr, "Dot: expected %e actual %e (%e)\n", expected, dot_, + rel_err); + abort(); + } + } + + private: + float dot_; // for Verify +}; + +// INTERMEDIATE: delta coding +// 1.0 cycles/float = bronze, 0.7 = silver, 0.4 = gold! +struct BenchmarkDelta : public TwoArray { + FuncOutput operator()(const size_t num_items) const { +#if HWY_TARGET == HWY_SCALAR + b_[0] = a_[0]; + for (size_t i = 1; i < num_items; ++i) { + b_[i] = a_[i] - a_[i - 1]; + } +#elif HWY_CAP_GE256 + // Larger vectors are split into 128-bit blocks, easiest to use the + // unaligned load support to shift between them. + const ScalableTag<float> df; + const size_t N = Lanes(df); + size_t i; + b_[0] = a_[0]; + for (i = 1; i < N; ++i) { + b_[i] = a_[i] - a_[i - 1]; + } + for (; i < num_items; i += N) { + const auto a = Load(df, &a_[i]); + const auto shifted = LoadU(df, &a_[i - 1]); + Store(a - shifted, df, &b_[i]); + } +#else // 128-bit + // Slightly better than unaligned loads + const HWY_CAPPED(float, 4) df; + const size_t N = Lanes(df); + size_t i; + b_[0] = a_[0]; + for (i = 1; i < N; ++i) { + b_[i] = a_[i] - a_[i - 1]; + } + auto prev = Load(df, &a_[0]); + for (; i < num_items; i += Lanes(df)) { + const auto a = Load(df, &a_[i]); + const auto shifted = CombineShiftRightLanes<3>(df, a, prev); + prev = a; + Store(Sub(a, shifted), df, &b_[i]); + } +#endif + return static_cast<FuncOutput>(b_[num_items - 1]); + } + + void Verify(size_t num_items) { + for (size_t i = 0; i < num_items; ++i) { + const float expected = (i == 0) ? a_[0] : a_[i] - a_[i - 1]; + const float err = std::abs(expected - b_[i]); + if (err > 1E-6f) { + fprintf(stderr, "Delta: expected %e, actual %e\n", expected, b_[i]); + } + } + } +}; + +void RunBenchmarks() { + Intro(); + printf("------------------------ %s\n", TargetName(HWY_TARGET)); + RunBenchmark<BenchmarkDot>("dot"); + RunBenchmark<BenchmarkDelta>("delta"); +} + +// NOLINTNEXTLINE(google-readability-namespace-comments) +} // namespace HWY_NAMESPACE +} // namespace hwy +HWY_AFTER_NAMESPACE(); + +#if HWY_ONCE +namespace hwy { +HWY_EXPORT(RunBenchmarks); + +void Run() { + for (int64_t target : SupportedAndGeneratedTargets()) { + SetSupportedTargetsForTest(target); + HWY_DYNAMIC_DISPATCH(RunBenchmarks)(); + } + SetSupportedTargetsForTest(0); // Reset the mask afterwards. +} + +} // namespace hwy + +int main(int /*argc*/, char** /*argv*/) { + hwy::Run(); + return 0; +} +#endif // HWY_ONCE |