[cfe-commits] [PATCH] Smarter implicit copy-construction/copy-assignment.

[Richard Smith]

On Fri, Jan 11, 2013 at 7:05 PM, Lang Hames <lhames at gmail.com> wrote:

> At present, if a class contains any Non-POD members we perform
> element-wise copies for each field when generating the implicit
> copy-constructor and implicit copy-assignment operator (with an
> optimization for array members).
>
> This patch changes this behavior - adjacent POD members will be memcpy'd,
> with Non-POD members output as usual.
>
> This is an initial implementation that I'd like to get in tree. Obvious
> deficiencies are:
>
> It punts entirely when LangOpts.getGC != None.
> It doesn't handle inner classes/unions.
> It doesn't attach any TBAA info, even when all members are the same type.
> It isn't particularly smart about when it falls back on element-wise
> copies (at the moment it emits a memcpy any time it finds more than one POD
> field).
>
> These should all be easy to test and remedy once the code's in tree though.
>
> Does anybody see any problems with this?
> Style comments?
>
> Feedback much appreciated.
>

This generally seems reasonable to me, but I've not looked at the patch in
detail. Any reason not to apply this to move assignment operators too?

Do you handle bitfields? See r151963 for an example of that.
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