Evaluate using Profile-Guided Optimization (PGO) and Post Link Optimization (PLO) for Clingo

[zamazan4ik]

Hi!

Recently I checked Profile-Guided Optimization (PGO) improvements on multiple projects. The results are here. According to the multiple tests, PGO can help with improving performance in many cases. E.g. Clingo is already built with PGO. Since this, I think PGO integration into the Clingo would be a good thing to have.

I can suggest the following action points:

• Perform more PGO benchmarks on Clingo. And if it shows improvements - add a note to the documentation about possible improvements in Clingo performance with PGO.
• Providing an easier way (e.g. a build option) to build scripts with PGO can be helpful for the end-users and maintainers since they will be able to optimize Clingo according to their own workloads.
• Optimize pre-built binaries (if it's possible to do)

Maybe testing Post-Link Optimization techniques (like LLVM BOLT) would be interesting too (Clang and Rustc already use BOLT as an addition to PGO) but I recommend starting from the usual PGO.

Here are some examples of how PGO optimization is integrated in other projects:

• Rustc: a CI script for the multi-stage build
• GCC:
  • Official docs, section "Building with profile feedback" (even AutoFDO build is supported)
  • A part in a "wonderful" configure script
• Clang: Docs
• Python:
  • CPython: README
  • Pyston: README
• Go: Bash script
• V8: Bazel flag
• ChakraCore: Scripts
• Chromium: Script
• Firefox: Docs
  • Thunderbird has PGO support too
• PHP - Makefile command and old Centminmod scripts
• MySQL: CMake script
• YugabyteDB: GitHub commit
• FoundationDB: Script
• Zstd: Makefile
• Foot: Scripts
• Windows Terminal: GitHub PR
• Pydantic-core: GitHub PR
• file.d: GitHub PR
• OceanBase: CMake flag

[rkaminsk]

Thanks for the heads up. I think it's a good idea to extend the build scripts to ease PGO. This should allow users to optimize their builds for particular tasks. However, I don't have a benchmark ready that could be used to enable PGO in general.

I'll leave this issue open for future development.