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

[Philip Reames via llvm-commits]

On 11/26/2017 05:15 PM, Davide Italiano via llvm-commits wrote:
> 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.
Was there resolution on this I haven't seen?  If not, we should revert 
the patch due to non-response.