Makefile

LENGTH=100000000

bench: test_boxing.exe
	echo "System: $$(uname -a)" > results.log
	for i in {0..10}; do (echo "run $$i"; ./test_boxing.exe) >> results.log; done

test_boxing.exe: test_boxing.cpp
	g++ -O0 --std=c++11 -DLENGTH=$(LENGTH) test_boxing.cpp -o test_boxing.exe

results.log

System: Darwin Grahams-MacBook-Pro-2.local 19.2.0 Darwin Kernel Version 19.2.0: Sat Nov  9 03:47:04 PST 2019; root:xnu-6153.61.1~20/RELEASE_X86_64 x86_64
run 0
  test_1: primitive and alloc runtime: 357.496 ms
  test_2: boxed and alloc runtime: 1010.83 ms
  test_3: primitive and no-alloc runtime: 342.527 ms
  test_4: boxed and no-alloc runtime: 209.27 ms
run 1
  test_1: primitive and alloc runtime: 342.769 ms
  test_2: boxed and alloc runtime: 993.804 ms
  test_3: primitive and no-alloc runtime: 336.365 ms
  test_4: boxed and no-alloc runtime: 213.019 ms
run 2
  test_1: primitive and alloc runtime: 332.564 ms
  test_2: boxed and alloc runtime: 957.733 ms
  test_3: primitive and no-alloc runtime: 337.576 ms
  test_4: boxed and no-alloc runtime: 203.382 ms
run 3
  test_1: primitive and alloc runtime: 338.737 ms
  test_2: boxed and alloc runtime: 972.019 ms
  test_3: primitive and no-alloc runtime: 345.216 ms
  test_4: boxed and no-alloc runtime: 216.245 ms
run 4
  test_1: primitive and alloc runtime: 334.753 ms
  test_2: boxed and alloc runtime: 967.459 ms
  test_3: primitive and no-alloc runtime: 379.589 ms
  test_4: boxed and no-alloc runtime: 217.279 ms
run 5
  test_1: primitive and alloc runtime: 347.914 ms
  test_2: boxed and alloc runtime: 1179.76 ms
  test_3: primitive and no-alloc runtime: 359.037 ms
  test_4: boxed and no-alloc runtime: 204.748 ms
run 6
  test_1: primitive and alloc runtime: 326.357 ms
  test_2: boxed and alloc runtime: 1034.79 ms
  test_3: primitive and no-alloc runtime: 394.06 ms
  test_4: boxed and no-alloc runtime: 230.615 ms
run 7
  test_1: primitive and alloc runtime: 374.186 ms
  test_2: boxed and alloc runtime: 1033.29 ms
  test_3: primitive and no-alloc runtime: 355.135 ms
  test_4: boxed and no-alloc runtime: 206.27 ms
run 8
  test_1: primitive and alloc runtime: 382.636 ms
  test_2: boxed and alloc runtime: 1076.76 ms
  test_3: primitive and no-alloc runtime: 408.046 ms
  test_4: boxed and no-alloc runtime: 226.272 ms
run 9
  test_1: primitive and alloc runtime: 392.07 ms
  test_2: boxed and alloc runtime: 1187.21 ms
  test_3: primitive and no-alloc runtime: 376.981 ms
  test_4: boxed and no-alloc runtime: 228.64 ms
run 10
  test_1: primitive and alloc runtime: 340.865 ms
  test_2: boxed and alloc runtime: 1024.61 ms
  test_3: primitive and no-alloc runtime: 349.574 ms
  test_4: boxed and no-alloc runtime: 224.538 ms

test_boxing.cpp

#include <chrono>
#include <iostream>

using namespace std;

#ifndef LENGTH
#define LENGTH 100 * 1000 * 1000
#endif

class Box {
public:
  bool missing = false;
};

class Int : public Box {
public:
  int val;
};

int main() {
  // TEST 1: Primitive
  auto t1 = chrono::high_resolution_clock::now();

  int *a = new int[LENGTH];
  for (int i = 0; i < LENGTH; i++) {
    a[i] = LENGTH - i;
  }

  auto t2 = chrono::high_resolution_clock::now();
  chrono::duration<double, milli> diff = t2 - t1;
  cout << "  test_1: primitive and alloc runtime: " << diff.count() << " ms"
       << endl;

  delete[] a;

  // TEST 2: Boxed
  auto t3 = chrono::high_resolution_clock::now();

  Int *a2 = new Int[LENGTH];
  for (int i = 0; i < LENGTH; i++) {
    a2[i].val = LENGTH - i;
  }

  auto t4 = chrono::high_resolution_clock::now();
  chrono::duration<double, milli> diff2 = t4 - t3;
  cout << "  test_2: boxed and alloc runtime: " << diff2.count() << " ms"
       << endl;

  delete[] a2;

  // TEST 3: Primitive
  int *a3 = new int[LENGTH];

  auto t5 = chrono::high_resolution_clock::now();

  for (int i = 0; i < LENGTH; i++) {
    a3[i] = LENGTH - i;
  }

  auto t6 = chrono::high_resolution_clock::now();
  chrono::duration<double, milli> diff3 = t6 - t5;
  cout << "  test_3: primitive and no-alloc runtime: " << diff3.count() << " ms"
       << endl;

  delete[] a3;

  // TEST 4: Boxed
  Int *a4 = new Int[LENGTH];
  auto t7 = chrono::high_resolution_clock::now();

  for (int i = 0; i < LENGTH; i++) {
    a4[i].val = LENGTH - i;
  }

  auto t8 = chrono::high_resolution_clock::now();
  chrono::duration<double, milli> diff4 = t8 - t7;
  cout << "  test_4: boxed and no-alloc runtime: " << diff4.count() << " ms"
       << endl;

  delete[] a4;
}