Challenge: write a reference counted slice that works as much as possible like a built-in slice

[deadalnix]

On Monday, 8 November 2021 at 22:38:27 UTC, Andrei Alexandrescu 
wrote:
>> shared_ptr does atomic operation all the time. The reality is 
>> that on modern machines, atomic operation are cheap *granted 
>> there is no contention*. It will certainly limit what the 
>> optimizer can do, but all in all, it's almost certainly better 
>> than keeping the info around and doing a runtime check.
>
> In my measurements uncontested atomic increment are 2.5x or 
> more slower than the equivalent increment.
>

Do you mind sharing this?

I find that curious, because load/stores on x86 are almost 
sequentially consistent by default, and you don't even need 
sequential consistency to increment the counter to begin with, so 
a good old `inc` instruction is enough.

I'd look to look at what's the compiler is doing here, because 
maybe we are trying to fix the wrong problem.