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Re: [Patch/RFC] libstdc++/19495

Benjamin Kosnik wrote:

Paolo, I think this is reasonable.

Thanks.

For 4.1, or when the ABI can change, anyway, we can consider changing
basic_string to make use of memory aligned only as CharT requires, not
more, but, for the time being, the below seems to me a viable approach...

Opinions? Disagreements?


For so_7, we really need to come up with some changes for std::string.

For one, we have to have link-time differences for various Reps. It's
the only way we are going to be able to do shared allocation strings.


100% agreed. Summarizing, we have at least two open issues:
1- Avoiding _Rep in static memory, probably we can neatly obtain that via a "short-string optimization" type solution.
2- Various alignment issues (the last one manifest itself slightly differently than the the very old one).

In order to fix 2-, basic_string must be profoundly redesigned, as soon as 4.0 branches (and the 4.0 version of type_traits is more or less final) I really want to seriously start on this big project. If we are lucky, the new design will not be blocked too seriously by __attribute__(aligned)...

Paolo.

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