[nnethercote]

> This is a supremely surprising conclusion

That's why I started the paragraph with "Contrary to what you might expect".

As for Stabilizer: "Stabilizer eliminates measurement bias by comprehensively and repeatedly randomizing the placement of functions, stack frames, and heap objects in memory." Those placements can affect cycle counts and wall times a lot, but don't affect instruction counts.

[vlovich123]

So have you not found in practice any data dependencies or cache issues show up as bottle necks? Or do current tools just make this more of a blind spot for optimization?

Also is there any work to multi-thread the Rust compiler on a more fine-grained level like the recent GCC work? I know you allude to that potentially that would make the instruction counts potentially less reliable so wondering if that's something being explored.

Finally, while I have you, I'm wondering if there's been any exploration of the idea of keeping track of information across builds so that incremental compilation is faster (i.e. only bother recompiling/relinking the parts of the code impacted by a code change). I've always thought that should almost completely eliminate compilation/linking times (at least for debug builds where full utmost optimization is less important).

[nnethercote]

I mentioned in the post several areas I myself haven't looked at, including cache misses. There may be room for improvements there.

There is an experimental parallel rustc front-end, e.g. see https://internals.rust-lang.org/t/help-test-parallel-rustc/1...

> any exploration of the idea of keeping track of information across builds so that incremental compilation is faster

That's exactly what incremental compilation does.

[vlovich123]

There's an effort to track which functions are modules & what the downstream implications of that are in terms of needing recompilation? Are there any links to technical descriptions? Super interested in reading up on the technical details involved.

[Muximize]

You might want to look into Salsa:

http://smallcultfollowing.com/babysteps/blog/2019/01/29/sals...

http://smallcultfollowing.com/babysteps/blog/2020/04/09/libr...