llvm dev - Sep 2010 - [LLVMdev] Union type, is it really used or necessary?

Here's a suggestion - can we make the "union patch" (the inverse
of the
patch that removed unions) as a downloadable file so that people who are
interested in finishing the work can do so?

On Tue, Sep 7, 2010 at 7:55 AM, Renato Golin <rengolin at
systemcall.org>wrote:
> On 7 September 2010 15:36, Anton Korobeynikov <anton at
korobeynikov.info>
> wrote:
> > Otherwise the feature being unused will quickly became broken.
>
> It was already broken for ages... :/
>
> Even if you're not using the backends (or MC), having it in front-end
> only will only confuse new users that will try to use it and hope it
> just works (my case, a few months ago).
>
> If there is nothing, you just work around it (by adding new features
> to structs, if necessary) or re-create unions, depending on your
> commitment to the union problem. Although having an union type would
> be quite an improvement to IR readability, I really don't need it that
> badly to write the whole back-end for it.
>
> It's just a matter of priorities, unfortunately... :(
>
> --
> cheers,
> --renato
>
> http://systemcall.org/
>
> Reclaim your digital rights, eliminate DRM, learn more at
> http://www.defectivebydesign.org/what_is_drm
> _______________________________________________
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>


-- 
-- Talin
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On 7 September 2010 16:16, Talin <viridia at gmail.com>
wrote:
> Here's a suggestion - can we make the "union patch" (the
inverse of the
> patch that removed unions) as a downloadable file so that people who are
> interested in finishing the work can do so?
The patch would degenerate quickly and become useless after a few
commits/releases.

Maybe a high level docs would be best, with the basic points like the
one on how to create a FunctionPass, but focused on how to create a
new Type. And a special section on the rationale about unions (and its
intrinsic problems with type sizes in front-end/back-end code
generation).

-- 
cheers,
--renato

http://systemcall.org/

Reclaim your digital rights, eliminate DRM, learn more at
http://www.defectivebydesign.org/what_is_drm

On Sep 7, 2010, at 8:16 AM, Talin wrote:
> Here's a suggestion - can we make the "union patch" (the
inverse of the patch that removed unions) as a downloadable file so that people
who are interested in finishing the work can do so?
It already is.  I reverted it with one commit, so you can obtain that patch with
'svn diff'.

-Chris
> 
> On Tue, Sep 7, 2010 at 7:55 AM, Renato Golin <rengolin at
systemcall.org> wrote:
> On 7 September 2010 15:36, Anton Korobeynikov <anton at
korobeynikov.info> wrote:
> > Otherwise the feature being unused will quickly became broken.
> 
> It was already broken for ages... :/
> 
> Even if you're not using the backends (or MC), having it in front-end
> only will only confuse new users that will try to use it and hope it
> just works (my case, a few months ago).
> 
> If there is nothing, you just work around it (by adding new features
> to structs, if necessary) or re-create unions, depending on your
> commitment to the union problem. Although having an union type would
> be quite an improvement to IR readability, I really don't need it that
> badly to write the whole back-end for it.
> 
> It's just a matter of priorities, unfortunately... :(
> 
> --
> cheers,
> --renato
> 
> http://systemcall.org/
> 
> Reclaim your digital rights, eliminate DRM, learn more at
> http://www.defectivebydesign.org/what_is_drm
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
> 
> 
> -- 
> -- Talin
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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On Tue, Sep 7, 2010 at 8:16 AM, Talin <viridia at gmail.com>
wrote:
> Here's a suggestion - can we make the "union patch" (the
inverse of the
> patch that removed unions) as a downloadable file so that people who are
> interested in finishing the work can do so?
Anyone who's really interested in working on it can just use "svn diff
-c 112356", and apply it with "patch -R".

-Eli

Eli Friedman wrote:
> On Tue, Sep 7, 2010 at 8:16 AM, Talin <viridia at gmail.com> wrote:
> > Here's a suggestion - can we make the "union patch" (the
inverse of the
> > patch that removed unions) as a downloadable file so that people who
are
> > interested in finishing the work can do so?
> 
> Anyone who's really interested in working on it can just use "svn
diff
> -c 112356", and apply it with "patch -R".
Well I tried that, the patch fails to reverse apply. Out of the
34 files touched by the patch, not a single hunk actually manages
to reverse apply.

Assuming I was to decide to embark on the effort of getting unions
back into LLVM:

  a) What is required for them to be accepted back in?

  b) What are the chances of getting them in the 2.8 release?

Erik
-- 
----------------------------------------------------------------------
Erik de Castro Lopo
http://www.mega-nerd.com/