Jakt compiler is quite slow to compile. This slows down development of the language. Most of the time is spent in the Clang.

Currently on my machine:

$ time ./build/jakt selfhost/main.jakt > build/baseline.cpp
real	0m4.788s
$ time clang++ -std=c++20 -I runtime/ -Wno-parentheses-equality -Wno-trigraphs -Wno-user-defined-literals build/baseline.cpp
real	0m14.547s

Clang part

I have profiled this a little and saw some directions how compilation can be sped up:

• A lot of time is spent in one type - Token. It is a Variant with ~100 alternatives, and is very slow to compile. Another one visible in the profile is CheckedExpression. While other variants in the code are not that prominent in the profile individually, they probably take quite some time cumulatively. This suggests that Variant is a good candidate for optimization.
• Quite a lot of time spent compiling debug_description functions.
  • Consider not generating unused debug_decription fucntions
  • debug_description still uses Variant::visit which is particularly slow to compile. Usage of visit has already been removed from other parts of generated code (matches), so it can be removed from here too. PR: #1038 by @Hendiadyoin1 --- -1s build time (-8%)
  • Compilation of debug_description functions can be sped up by minimizing printing calls by merging them together.
• There seems to be lot of redundant parentheses and curly braces. I don't know how much they affect compilation times, but it would be nice to remove them anyways
• Split cpp code into multiple translation units (TUs) which can be compiled in parallel.
• Find what compile flags can be used. Investigate
  • -fno-exceptions #1043 -2.7s (-23%)
  • -fno-rtti, -fno-unwind-tables did not make any measurable difference
• #1042 by @Hendiadyoin1 -0.25s (-2%)

Jakt part

I have not investigated that yet

Appendix

Profiling was done with clang with command line:

time clang++ -std=c++20 -I runtime/ -Wno-parentheses-equality -Wno-trigraphs -Wno-user-defined-literals -ftime-trace -c -o build/baseline.o build/baseline.cpp

This generates baseline.json in the build directory.

Profile is attached:
baseline.zip
you can inspect it using Speedscope, Perfetto, Chrome dev tools, etc.