[PATCH] D148010: [Pipelines] Don't run module optimization in full LTO pre-link

[Dave Green via Phabricator via llvm-commits]

dmgreen added a comment.

I have been trying to looks through our downstream performance differences, but they might be quite different to upstream. I think I can reduce or remove most of the regressions with pass pipeline changes in the test we have that run under LTO.

I have been looking at cases similar to D148120 <https://reviews.llvm.org/D148120> recently. It's a problem we already knew about (https://reviews.llvm.org/D125301#3536693). But more than just predication, scalable vectorization in general will lead to loops without precise trip counts. I'm still not 100% sure this is the best, but we need to fix it in some way and for scalable vectors at least it makes sense to limit vectorization during the pre-lto step.

Unfortunately I think there might just be a lot of changes. The first thing to fix should probably be that the pass pipeline is different through addVectorPasses. There will be quite a few differences that come up from that.


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  https://reviews.llvm.org/D148010/new/

https://reviews.llvm.org/D148010