std.variant benchmark

[Dmitry Olshansky]

On 29-Jul-12 18:17, Andrei Alexandrescu wrote:
> On 7/29/12 8:17 AM, Gor Gyolchanyan wrote:
>> std.variant is so incredibly slow! It's practically unusable for
>> anything, which requires even a tiny bit of performance.
>
> You do realize you actually benchmark against a function that does
> nothing, right? Clearly there are ways in which we can improve
> std.variant to the point initialization costs assignment of two words,
> but this benchmark doesn't help. (Incidentally I just prepared a class
> at C++ and Beyond on benchmarking, and this benchmark makes a lot of the
> mistakes described therein...)
>
>
> Andrei


This should be more relevant then:

//fib.d
import std.datetime, std.stdio, std.variant;

auto fib(Int)()
{
	Int a = 1, b = 1;
	for(size_t i=0; i<100; i++){
		Int c = a + b;
		a = b;
		b = c;
	}
	return a;	
}

void main()
{
	writeln(benchmark!(fib!int, fib!long, fib!Variant)(10_000));
}


dmd -O -inline -release fib.d

Output:

[TickDuration(197), TickDuration(276), TickDuration(93370107)]

I'm horrified. Who was working on std.variant enhancements? Please chime in.

-- 
Dmitry Olshansky