linqpadMicrobenchValueFromNullalbeSnippet.cs

//timings "on my machine", fixed clockspeed, multiple runs have stable timings with less than 1% variation, x64 .net core 3.0 roslyn 3.3.1-beta4 via linqpad 6.3.0 beta.
//obviously there's some noise, but even the timing differences between 0.66 and 0.68 appear to be reproducible on this machine; not just random happenstance


var arr = Enumerable.Range(1, 10_000).Select(i => i % 2 == 0 ? default(int?) : i).ToArray();
var filteredSeq = arr.Where(o=>o!=null);
var sw = Stopwatch.StartNew();
var sum =0l;

for (int iter = 0; iter < 100_000; iter++)
{
#if false
    foreach (var val in arr)
    {
        //empty loop: 0.2s
        //sum += val.HasValue ? val.GetValueOrDefault() : 0; //0.81s
        sum += val ?? 0; //0.45s
        //sum += val.HasValue ? val.Value : 0;//0.66s
        //sum += val.GetValueOrDefault(); //0.45s

        //sum += val.HasValue ? val.GetValueOrDefault() : 1; //0.68s
        //sum += val ?? 1; //0.68s
        //sum += val.HasValue ? val.Value : 1;//0.66s
    }

#elif false
    for (int idx = 0; idx < arr.Length; idx++)
        {
            //empty loop: 0.2s
            //sum += arr[idx].HasValue ? arr[idx].GetValueOrDefault() : 0; //0.81s
            //sum += arr[idx] ?? 0; //0.45s
            //sum += arr[idx].HasValue ? arr[idx].Value : 0; 0.66s
            //sum += arr[idx].GetValueOrDefault(); 0.45s
        }

#else
    foreach (var val in filteredSeq)
    {
        //empty loop: 0.2s
        //sum += val.HasValue ? val.GetValueOrDefault() : 0; //7.2s
        //sum += val ?? 0; //7.1s
        //sum += val.HasValue ? val.Value : 0;//7.2s
        sum += val.GetValueOrDefault(); //7.1s
    }
#endif
}

sw.Elapsed.TotalSeconds.Dump();