[PATCH] D81089: Mark InstCombine as not preserving PostDomTree

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri requested changes to this revision.
lebedev.ri added a comment.
This revision now requires changes to proceed.

In D81089#2084784 <https://reviews.llvm.org/D81089#2084784>, @yrouban wrote:

> In D81089#2071195 <https://reviews.llvm.org/D81089#2071195>, @lebedev.ri wrote:
>
> > Which fold is at fault here?
> >  Can it be simply taught to update domtree?
>
>
> There is no way to update for successors switch. It would be a noop for the updater.


Then i'd agree with @asbirlea

In D81089#2072329 <https://reviews.llvm.org/D81089#2072329>, @asbirlea wrote:

> I don't think the solution is to not preserve PDom either.
>  I think your suggestion from the description is spot-on though: "A better fix would be to improve PostDomTree to be insensitive to the order of successors in post-dom unreachable subgraphs." This is indeed an issue with the order of basic blocks when dealing with infinite loops.



CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D81089/new/

https://reviews.llvm.org/D81089