[webkit-dev] Compile time increase over time

Alex Christensen achristensen at apple.com
Mon Apr 24 11:10:25 PDT 2017

Thanks for the data, Carlos! This is a growing problem that is hurting productivity.  We’ve discussed it a bit and haven’t done enough about it.  Here are some of the ideas I’ve heard:

1) Reduce #includes by doing more forward declaring and less inlining.  We would probably need link time optimization to not lose performance benefits of inlining functions in headers.
2) Use distributed build tools and caches to cover up the problem.  WebKit would still be prohibitively hard to compile for people without lots of expensive computers, but we could greatly improve the productivity of large teams.
3) Use C++ modules
4) Put more commonly included headers into precompiled headers
5) I remember somebody claiming a few years ago that replacing #include “Something.h” with #include “path/to/Something.h” reduced compile times because it required fewer include paths, but I don’t think anybody has measured the improvement recently.
6) Optimize the compilers we use

We should look into all of these and more.  Compiling WebKit also uses a lot of memory, and our binary size continues to increase.

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