[screcth]

Why does an optimizing compiler introduce nondeterminism?

In my mind an optimizing compiler is a pure function that takes source code and produces an object file.

[stevefan1999]

Well, lot of things can influence here. Multithreaded build, PGO, or even the different access order of the hash table inside the code optimizer can be a factor. Things are getting probalistic and thus somewhat nondeterministic: the build itself is nondeterministic but the runtime/final execution is deterministic