lib.rs

#![feature(test)]
extern crate test;

#[cfg(test)]
mod tests {

  use test::black_box;
  use test::Bencher;
  
  const ITERATIONS: usize = 100_000;

  struct CompoundValue {
    pub a: u64,
    pub b: u64,
    pub c: u64,
    pub d: u64,
    pub e: u64,
  }

  #[bench]
  fn bench_in_place(b: &mut Bencher) {
    let mut compound_value = CompoundValue {
      a: 0,
      b: 2,
      c: 0,
      d: 5,
      e: 0
    };  

    let val: &mut CompoundValue = &mut compound_value;

    let result = b.iter(|| {
      let mut f : u64 = black_box(0);
      for _ in 0..ITERATIONS {
        f += val.a + val.b + val.c + val.d + val.e;
      }   
      f = black_box(f);
      return f;
    }); 
    assert_eq!((), result);
  }
}