[PATCH] D94232: [LoopRotate] Add PrepareForLTO stage, avoid rotating with inline cands (WIP).

Thu Jan 14 10:35:30 PST 2021

fhahn added a comment.

In D94232#2498633 <https://reviews.llvm.org/D94232#2498633>, @sanwou01 wrote:

> So on SPEC 2006 this fixes astar (+9.6%) as well as shakes things up enough to "fix" h264ref (+9.0%, see D93946 <https://reviews.llvm.org/D93946>). Other notable changes are libquantum (+3.2%) and omnetpp (-2.8%). Geomean is +1.5%.

Thank you very much for running the numbers!

Just to double check, positive here means good (I assume increase in score)?

> On SPEC 2017 there is still a problem with omnetpp_r (runtime error), which I'll have a look at next, but is otherwise neutral on geomean with only minor wobbles (+1%, -0.5% at most) on individual benchmarks.
>
> With this having a substantial impact on performance, I'm quite keen to help get this in soon, ideally before the LLVM 12 branch, so please let me know if there is anything else I can do to help.

Sounds good! I think the theory behind the change should mean it should be quite safe and the data so far seems encouraging; I can confirm similar improvements for `astar` on our tracking.

It would probably good to get this in well ahead of the 12.0 branch, so it has a chance to make it through various downstream perf-tracking systems.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D94232/new/

https://reviews.llvm.org/D94232