Compare local function to instance method or static method.

perffunc.dart

var a = -4;

int logicToGetA() => a;

class A {
  final int flag;
  A(this.flag);
  int foo() {
    int a = logicToGetA();
    int _bar() => someOtherLogic(a);
    int b = _bar();
    return b;
  }

  int someOtherLogic(int a) {
    // Should prevent inlining.
    if (a < 0) return someOtherLogic(a + 1);
    return a + flag;
  }
}

class B {
  final int flag;
  B(this.flag);
  int _bar(int a) => someOtherLogic(a);

  int foo() {
    int a = logicToGetA();
    int b = _bar(a);
    return b;
  }

  int someOtherLogic(int a) {
    // Should prevent inlining.
    if (a < 0) return someOtherLogic(a + 1);
    return a + flag;
  }
}

class S {
  final int flag;
  S(this.flag);
  int foo() {
    int a = logicToGetA();
    int _bar() => someOtherLogic(a, this);
    int b = _bar();
    return b;
  }

  static int someOtherLogic(int a, S self) {
    // Should prevent inlining.
    if (a < 0) return someOtherLogic(a + 1, self);
    return a + self.flag;
  }
}

double benchA(int ms, int flag) {
  var a = A(flag);
  var count = 0;
  var elapsed = 0;
  var sw = Stopwatch()..start();
  int r = 0;
  do {
    for (var i = 0; i < 10000; i++) {
      r ^= a.foo();
    }
    elapsed = sw.elapsedMilliseconds;
    count += 10000;
  } while (elapsed < ms);
  if (r != 0) throw "wrong";
  return count / elapsed;
}

double benchB(int ms, int flag) {
  var a = B(flag);
  var count = 0;
  var elapsed = 0;
  var sw = Stopwatch()..start();
  int r = 0;
  do {
    for (var i = 0; i < 10000; i++) {
      r ^= a.foo();
    }
    elapsed = sw.elapsedMilliseconds;
    count += 10000;
  } while (elapsed < ms);
  if (r != 0) throw "wrong";
  return count / elapsed;
}

double benchS(int ms, int flag) {
  var a = S(flag);
  var count = 0;
  var elapsed = 0;
  var sw = Stopwatch()..start();
  int r = 0;
  do {
    for (var i = 0; i < 10000; i++) {
      r ^= a.foo();
    }
    elapsed = sw.elapsedMilliseconds;
    count += 10000;
  } while (elapsed < ms);
  if (r != 0) throw "wrong";
  return count / elapsed;
}

main(List<String> args) async {
  a = args.isEmpty ? 0 : 1; // Make value unpredictable to compiler
  // Warmup.
  benchA(500, 1);
  benchB(500, 1);
  benchS(500, 1);
  // Run bench three times.
  for (var i = 0; i < 3; i++) {
    await sleep;
    print("A: ${benchA(2000, 0)} /ms");
    await sleep;
    print("B: ${benchB(2000, 0)} /ms");
    await sleep;
    print("S: ${benchS(2000, 0)} /ms");
  }
}

Future<void> get sleep => Future(() {});