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

[Davide Italiano via llvm-commits]

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