Benchmark alignas , packed on variables

Benchmark_alignas_packed_variables.cpp

//////// demo online: https://quick-bench.com/q/TYcfwD0khRpbE53rn8cRtn7nmvA
#include <vector>
#include <cstddef>

static constexpr auto totalVecSize = 99'999; 

struct __attribute__ ((packed)) AAA_packed {
  int a;
  char b;
  float c;
  char d;
  float e;
  double f[3];
}; 

struct AAA {
  int a;
  char b;
  float c;
  char d;
  float e;
  double f[3];
}; 

static void packedMove(benchmark::State& state) {
  using DefaltType = AAA_packed; 
  for (auto _ : state) { 
    std::vector<DefaltType> vec;
    for(std::size_t i=0;i<totalVecSize;++i)
    {
       DefaltType tmp;
       benchmark::DoNotOptimize(tmp);
       vec.push_back(tmp);
    }
    benchmark::DoNotOptimize(vec);
  }
} 
BENCHMARK(packedMove);

static void normalMove(benchmark::State& state) { 
  using DefaltType = AAA; 
  for (auto _ : state) { 
    std::vector<DefaltType> vec;
    for(std::size_t i=0;i<totalVecSize;++i)
    {
       DefaltType tmp;
       benchmark::DoNotOptimize(tmp);
       vec.push_back(tmp);
    }
    benchmark::DoNotOptimize(vec);
  }
}
BENCHMARK(normalMove);

static void alignAsPackedMove(benchmark::State& state) {  
  using DefaltType = AAA_packed;
  for (auto _ : state) { 
    std::vector<DefaltType> vec;
    for(std::size_t i=0;i<totalVecSize;++i)
    {
       alignas(alignof(DefaltType)) DefaltType tmp;
       benchmark::DoNotOptimize(tmp);
       vec.push_back(tmp);
    }
    benchmark::DoNotOptimize(vec);
  }
}
BENCHMARK(alignAsPackedMove);

static void alignAsNormalMove(benchmark::State& state) { 
  using DefaltType = AAA;
  for (auto _ : state) { 
    std::vector<DefaltType> vec;
    for(std::size_t i=0;i<totalVecSize;++i)
    {
       alignas(alignof(DefaltType)) DefaltType tmp;
       benchmark::DoNotOptimize(tmp);
       vec.push_back(tmp);
    }
    benchmark::DoNotOptimize(vec);
  }
}
BENCHMARK(alignAsNormalMove);

Benchmark_alignas_packed_variables.png