Krister Walfridsson is a user on octodon.social. You can follow them or interact with them if you have an account anywhere in the fediverse.
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I blogged about what GCCs interprocedural optimizations do
https://kristerw.blogspot.se/2017/05/interprocedural-optimization-in-gcc.html
I wrote a follow-up post with some more information about what -fipa-pta actually do
https://kristerw.blogspot.se/2017/06/fipa-pta.html