[PATCH] D40049: [PATCH] Global reassociation for improved CSE

[escha via Phabricator via llvm-commits]

escha added a comment.

In https://reviews.llvm.org/D40049#939097, @spatel wrote:

> My understanding of 'reassociate' isn't good enough to approve this, but I'm curious about running the main loop multiple times (ReassociateStep) because I noticed an improvement in some other code by running the pass twice.
>
> 1. Can we split that part into a preliminary patch?
> 2. Is it too expensive in compile time to run that to a fixed-point (like instcombine)?


I'm extremely nervous about running it to a fixed point; I'm not confident that even the *existing pass* will always converge to a fixed point.

Running it twice without any changes seems fairly pointless; the changes are mostly just removal of dead instructions and such that would get instcombined away later.


Repository:
  rL LLVM

https://reviews.llvm.org/D40049