"Tearing off" a method is extremely slow

[DartBot]

This issue was originally filed by danri...@gmail.com

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The following code times two operations:

1. call a closure that calls a method 'tearOff' on a particular object
2. call a closure that returns a closure representing the object's 'tearOff' method, then call that closure

On my machine (Mac Pro, OS X 10.5.8) the second approach is about 1700 times slower.

class Test {
  Test();
  void tearOff() {}
}

class Benchmark {
  Test test;
  Function closure1;
  Function closure2;

  Benchmark();

  void run() {
    test = new Test();
    closure1 = () => test.tearOff();
    closure2 = () => test.tearOff;

    for (int iter = 0; iter < 10; iter++) {
      bench();
    }
  }
  
  void bench() {
    Stopwatch w1 = new Stopwatch();
    w1.start();
    for (int i = 0; i < 10000; i++) {
      closure1();
    }
    w1.stop;
    double t1 = w1.elapsedInUs() / 10000;
    
    Stopwatch w2 = new Stopwatch();
    w2.start();
    for (int i = 0; i < 10000; i++) {
      closure2()();
    }
    w2.stop;
    double t2 = w2.elapsedInUs() / 10000;

    print("$t1 $t2 ${t2 / t1}");
  }
}

void main() {
  new Benchmark().run();
}

[DartBot]

This comment was originally written by rice@google.com

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Added Invalid label.