Re: [C++0x] contiguous bitfields race implementation

[Richard Guenther <richard.guenther@gmail.com>]

On Fri, Sep 2, 2011 at 2:49 PM, Aldy Hernandez <aldyh@redhat.com> wrote:
>
>> Note that with all this mess I'll re-iterate some of my initial thoughts.
>> 1) why not do this C++ (or C) specific stuff in the frontends, maybe
>> at gimplifying/genericization time?  That way you wouldn't need to
>> worry about middle-end features but you could rely solely on what
>> C/C++ permit.  It is, after all, C++ _frontend_ semantics that we
>> enforce here, in the middle-end, which looks out-of-place.
>
> The front-end, really?  After all this going back and forth?

Well, I'm fine with handling it in the middle-end if it's correct there.

> After you were
> all so worried about Ada, and now you're ditching it in favor of handling
> only C++?

I'm just showing you a possible solution for where you'd not need to
worry ;)  Consider LTOing an Ada and a C++ module - you need to
enable the C++ memory model at link-time so it is in effect when we
process bit-fields.  That will automatically enable it for the Ada pieces, too.

>> Is the C++ memory model stuff going to be "ready" for 4.7?
>
> No, not if you expect me rewrite things every day.

I don't expect you to rewrite things every day.

Don't read every comment I make as a definite decision and order to
you.  I am a mere mortal, too, and the bitfield thing is, I must admit,
still partially a mystery to myself (which is why I keep asking questions
instead of simply providing you with definite answers).  After all I pushed
back my idea of lowering bitfield accesses somewhere on GIMPLE and
I'm not sure if I get back to it for 4.7.  And I definitely would consider
2) for that work.

Btw, it would be nice if I weren't the only one reading your updated
patches :/  I'm just punching holes where I see them and hope I and
you learn something in that process.

Richard.