[PATCH] D81089: Mark InstCombine as not preserving CFG

[Jakub Kuderski via Phabricator via llvm-commits]

kuhar added a comment.

In D81089#2086985 <https://reviews.llvm.org/D81089#2086985>, @nikic wrote:

> If we define that changing successor order constitutes a CFG change, then these optimizations need to be dropped from InstCombine, and moved into SimplifyCFG.
>
> As said before, InstCombine is supposed to be CFG-preserving -- if it isn't because the definition of what "CFG-preserving" means was unclear, then we need to fix InstCombine to be in line with we new definition.
>
> As the pipeline diffs show, not preserving CFG has a very real cost (five new domtree calculations at least). We should try to avoid that :)


+1


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

https://reviews.llvm.org/D81089