Re: [review][fixed_string] End of review periodapproaching and a plea

From: Peter Dimov (pdimov_at_[hidden])
Date: 2019-12-04 18:23:52

Andrey Semashev wrote:
> > The idea here is that you win one byte by reusing the last byte of the 
> > storage as the size, overlapping it with the null terminator in the 
> > size() == N case (because capacity - size becomes 0).
>
> I'm not sure this would actually be beneficial in terms if performance. 
> Ignoring the fact that size() becomes more expensive, and this is a 
> relatively often used function, you also have to access the tail of the 
> storage, which is likely on a different cache line than the beginning of 
> the string.

Yes, probably. As I said, it's not clear that we should bother with it (I 
wouldn't), but it at least gives consistent space savings for all short 
strings.

That said, one could use it for N < 32, when the size will be in the same 
cache line.