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

[Mehdi AMINI via Phabricator via llvm-commits]

mehdi_amini added a comment.

In https://reviews.llvm.org/D29376#663757, @pcc wrote:

> 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.


So that's more like a O0 :)

> 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.

`Unacceptably slow` for Chromium is not the majority of use-cases. 
If we end up with Chromium being the only blocker for any progress for the 99.9% other applications, you're likely gonna have to supply you own flag "-mllvm -do-lto-optimizations-but-not-too-much".


https://reviews.llvm.org/D29376