llvm dev - Apr 2017 - Do we still need the self move protection in APInt's move assignment operator?

The comment says it was added due to a bug in MSVC 2013 implementation of
stable_sort. Newer versions of MSVC have fixed this bug in stable_sort
according to this webpage record
https://connect.microsoft.com/VisualStudio/feedback/details/886652

Can we remove the check now?

~Craig
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I think so. Besides, recommended VS version is VS 2015 [1], the bug
should be long gone.

[1]
http://llvm.org/docs/GettingStarted.html#host-c-toolchain-both-compiler-and-standard-library

Regards,
chenwj


--
Wei-Ren Chen (陳韋任)
Homepage: https://people.cs.nctu.edu.tw/~chenwj


2017-04-03 3:28 GMT+08:00 Craig Topper via llvm-dev <llvm-dev at
lists.llvm.org>:
> The comment says it was added due to a bug in MSVC 2013 implementation of
> stable_sort. Newer versions of MSVC have fixed this bug in stable_sort
> according to this webpage record
> https://connect.microsoft.com/VisualStudio/feedback/details/886652
>
> Can we remove the check now?
>
> ~Craig
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>

The way the code is currently written we only do the self-move check on the
multiword case. But on if we do a self move on a single word, we'll end up
calling a memcpy with src and dest the same which is UB. So either way this
code needs to change. We need to either move it up to cover single word too
or remove it entirely.

~Craig

On Sun, Apr 2, 2017 at 3:10 PM, 陳韋任 <chenwj.cs97g at g2.nctu.edu.tw>
wrote:
> I think so. Besides, recommended VS version is VS 2015 [1], the bug
> should be long gone.
>
> [1] http://llvm.org/docs/GettingStarted.html#host-c-
> toolchain-both-compiler-and-standard-library
>
> Regards,
> chenwj
>
>
> --
> Wei-Ren Chen (陳韋任)
> Homepage: https://people.cs.nctu.edu.tw/~chenwj
>
>
> 2017-04-03 3:28 GMT+08:00 Craig Topper via llvm-dev <
> llvm-dev at lists.llvm.org>:
> > The comment says it was added due to a bug in MSVC 2013 implementation
of
> > stable_sort. Newer versions of MSVC have fixed this bug in stable_sort
> > according to this webpage record
> > https://connect.microsoft.com/VisualStudio/feedback/details/886652
> >
> > Can we remove the check now?
> >
> > ~Craig
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> >
>
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