[PATCH] D29376: LTO: align the Monolithic LTO optimization pipeline on the ThinLTO and O2/O3 one

[Peter Collingbourne via Phabricator via llvm-commits]

pcc added a comment.

We already use regular LTO at opt level 1 -- this basically provides "dead stripping with support for CFI and devirtualization". That is essentially all we need from the LTO pipeline at the moment. Getting more out of LTO (cross-module inlining, etc.) would be nice to have, and is part of the motivation for switching to thin LTO.

Based on my reading of the code, the thin LTO opt level 1 pipeline does a lot more than the current regular LTO opt level 1 pipeline. Switching the pipeline like this would likely make link times unacceptably slow until we switch to thin LTO.


https://reviews.llvm.org/D29376