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

Mehdi AMINI via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Wed Feb 1 11:48:20 PST 2017

mehdi_amini added a comment.

In https://reviews.llvm.org/D29376#663665, @pcc wrote:

> For a start, this pipeline doesn't look right as it needs to include at least the CFI passes with the correct summary action.

Yes I noticed it while doing it, but promised to the other guys that I'll get a patch out to be able to test the performance and the build time impact.

> But a higher level point is that it seems premature to do this until there is a proven migration path from regular to thin LTO for users of the CFI and whole-program devirtualization features, such as Chromium.

I disagree that we would hold back the whole LTO optimization strategy based on a single large project that is using CFI-features. If the extra build-time is a real problem for Chromium and CFI, then a better strategy is to lower the optimization level during LTO to https://reviews.llvm.org/owners/package/1/.


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