Rust Counter Optimization

[bjfish]

From the article: https://blog.sqreen.io/webassembly-performance/

I compiled the rust example for the counter and saw the count function compiles to this wasm:

  (func $count (type $t0) (param $p0 i32)
    i32.const 0
    i32.const 0
    i32.store offset=1048640)

So, I believe the numerical operations you had intended on comparing in this benchmark may have all been optimized away by aggressive compiler optimizations?

[vdeturckheim]

@bjfish make sense! Thanks for pointing that out. What Algorithm would you suggest for a better teste here?

[MaxGraey]

Just use this:

#[allow(non_snake_case)]
#[wasm_bindgen]
pub fn count(max: i32) -> i32 {
    let mut res = 0;
    for i in 0..max {
        res = res + 1;
    };
    res
}

[vdeturckheim]

Thanks @MaxGraey !

[MaxGraey]

Oh, no! It still use some aggressive optimization. Just sec

[MaxGraey]

it seems in rust you should use random value for increment. This affect for run as well.

[MaxGraey]

Or just skip this bench sample as trivial and very syntactic.

[ballercat]

At this point, you might as well write it in plain wast.

[vdeturckheim]

@ballercat that's another possibility, I don't have any bandwidth on this topic until mid-September, also, the latest updates in V8 might give us some new results.