VariableLengthLoadBenchmark.cpp

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/*
    RawSpeed - RAW file decoder.
 
    Copyright (C) 2024 Roman Lebedev
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.
 
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
 
#include "adt/VariableLengthLoad.h"
#include "adt/Array1DRef.h"
#include "adt/Casts.h"
#include "adt/Invariant.h"
#include "bench/Common.h"
#include "common/Common.h"
#include <array>
#include <cstddef>
#include <cstdint>
#include <vector>
#include <benchmark/benchmark.h>
 
namespace rawspeed {
 
namespace {
 
[[maybe_unused]] inline void fixedLengthLoad(Array1DRef<std::byte> out,
                                             Array1DRef<const std::byte> in,
                                             int inPos) {
  invariant(out.size() != 0);
  invariant(in.size() != 0);
  invariant(out.size() <= in.size());
  invariant(inPos >= 0);
 
  // Here we "somehow" know that the load is always in-bounds.
  invariant(inPos < in.size());
  invariant(inPos + out.size() <= in.size());
 
  variableLengthLoadNaiveViaMemcpy(out, in, inPos);
}
 
template <decltype(fixedLengthLoad) Callable>
[[maybe_unused]] inline void
fixedLengthLoadOr(rawspeed::Array1DRef<std::byte> out,
                  rawspeed::Array1DRef<const std::byte> in, int inPos) {
  invariant(out.size() != 0);
  invariant(in.size() != 0);
  invariant(out.size() <= in.size());
  invariant(inPos >= 0);
 
  if (inPos + out.size() <= in.size()) {
    fixedLengthLoad(out, in, inPos);
    return;
  }
 
  Callable(out, in, inPos);
}
 
} // namespace
 
} // namespace rawspeed
 
namespace {
 
using rawspeed::fixedLengthLoad;
using rawspeed::fixedLengthLoadOr;
using rawspeed::variableLengthLoad;
using rawspeed::variableLengthLoadNaiveViaConditionalLoad;
using rawspeed::variableLengthLoadNaiveViaMemcpy;
 
template <decltype(variableLengthLoadNaiveViaMemcpy) Impl, typename T>
void BM_Impl(benchmark::State& state) {
  constexpr int bytesPerItem = sizeof(T);
 
  int64_t numBytes = rawspeed::roundUp(state.range(0), bytesPerItem);
  benchmark::DoNotOptimize(numBytes);
 
  const std::vector<std::byte> inStorage(
      rawspeed::implicit_cast<size_t>(numBytes));
 
  const auto in = rawspeed::Array1DRef<const std::byte>(
      inStorage.data(), rawspeed::implicit_cast<int>(numBytes));
 
  std::array<std::byte, bytesPerItem> outStorage;
  auto out = rawspeed::Array1DRef<std::byte>(
      outStorage.data(), rawspeed::implicit_cast<int>(bytesPerItem));
 
  for (auto _ : state) {
    for (int inPos = 0; inPos < numBytes; inPos += bytesPerItem) {
      Impl(out, in, inPos);
      benchmark::DoNotOptimize(out.begin());
    }
  }
 
  state.SetComplexityN(numBytes);
  state.counters.insert({
      {"Throughput",
       benchmark::Counter(sizeof(std::byte) * state.complexity_length_n(),
                          benchmark::Counter::Flags::kIsIterationInvariantRate,
                          benchmark::Counter::kIs1024)},
      {"Latency",
       benchmark::Counter(sizeof(std::byte) * state.complexity_length_n(),
                          benchmark::Counter::Flags::kIsIterationInvariantRate |
                              benchmark::Counter::Flags::kInvert,
                          benchmark::Counter::kIs1000)},
  });
}
 
void CustomArguments(benchmark::internal::Benchmark* b) {
  b->Unit(benchmark::kMicrosecond);
 
  static constexpr int L1dByteSize = 32U * (1U << 10U);
  static constexpr int L2dByteSize = 512U * (1U << 10U);
  static constexpr int MaxBytesOptimal = L2dByteSize;
 
  if (benchmarkDryRun()) {
    b->Arg(L1dByteSize);
    return;
  }
 
  b->RangeMultiplier(2);
  if constexpr ((true))
    b->Arg(MaxBytesOptimal);
  else
    b->Range(1, 2048UL << 20)->Complexity(benchmark::oN);
}
 
// NOLINTBEGIN(cppcoreguidelines-macro-usage)
 
#define GEN(I, T) BENCHMARK(BM_Impl<I, T>)->Apply(CustomArguments)
 
#define GEN_CALLABLE(I)                                                        \
  GEN(I, uint8_t);                                                             \
  GEN(I, uint16_t);                                                            \
  GEN(I, uint32_t);                                                            \
  GEN(I, uint64_t)
 
#define GEN_TIME()                                                             \
  GEN_CALLABLE(GEN_WRAPPER(fixedLengthLoad));                                  \
  GEN_CALLABLE(GEN_WRAPPER(variableLengthLoad));                               \
  GEN_CALLABLE(GEN_WRAPPER(variableLengthLoadNaiveViaConditionalLoad));        \
  GEN_CALLABLE(GEN_WRAPPER(variableLengthLoadNaiveViaMemcpy))
 
#undef GEN_WRAPPER
#define GEN_WRAPPER(I) I
 
GEN_TIME();
 
#undef GEN_WRAPPER
#define GEN_WRAPPER(I) fixedLengthLoadOr<I>
 
GEN_TIME();
 
// NOLINTEND(cppcoreguidelines-macro-usage)
 
} // namespace
 
BENCHMARK_MAIN();