[llvm] r318743 - SLPVectorizer.cpp: Avoid std::stable_sort(properlyDominates()).

[Davide Italiano via llvm-commits]

On Tue, Nov 21, 2017 at 9:54 PM, Davide Italiano <davide at freebsd.org> wrote:
> On Tue, Nov 21, 2017 at 1:41 AM, NAKAMURA Takumi via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Author: chapuni
>> Date: Tue Nov 21 01:41:01 2017
>> New Revision: 318743
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=318743&view=rev
>> Log:
>> SLPVectorizer.cpp: Avoid std::stable_sort(properlyDominates()).
>>
>> properlyDominates() shouldn't be used as sort key. It causes different output between stdlibc++ and libc++.
>> Instead, I introduced RPOT. In most cases, it works for CSE.
>>
>
> Why using the dominator DFSIn/DFSOut numbering not enough? I'm not
> sure you need reverse post order here.
> [I thought this change was never approved, but I might have missed something]
>
> Thanks!
>
> --
> Davide

ahem ... ping? I'm a little worried because this wasn't really
reviewed and you went ahead and committed a patch which uses a
different approach than the one proposed.

-- 
Davide

"There are no solved problems; there are only problems that are more
or less solved" -- Henri Poincare