Array fill performance differences between for, foreach, slice

[lithium iodate]

On Wednesday, 1 April 2020 at 06:48:09 UTC, Jacob Carlborg wrote:
> I you care about performance you should really compile using 
> LDC (with `-O5 -release -flto=full 
> -defaultlib=phobos2-ldc-lto,druntime-ldc-lto`), which usually 
> produces much better code:
>
> Slice: Mean time(usecs): 50.58, Standard Deviation: 46.2621
> Foreach: Mean time(usecs): 53.92, Standard Deviation: 19.8039
> For: Mean time(usecs): 39.89, Standard Deviation: 7.80041
>
> Slice: Mean time(usecs): 76.62, Standard Deviation: 73.0014
> Foreach: Mean time(usecs): 49.63, Standard Deviation: 24.5672
> For: Mean time(usecs): 40.02, Standard Deviation: 7.67388

The benchmark is highly flawed, the results for LDC are 
completely meaningless. LDC produces identical code for every 
case and the filling procedures are all elided.