ClangBuildAnalyzer

I've had success using https://github.com/nico/ninjatracing along with Clang's `-ftime-trace` to visualize the build performance of a C++ project using CMake. https://github.com/aras-p/ClangBuildAnalyzer helps further break down what the compiler is spending its time on.

> On another note: C++ compiler should by default keep statistics about the chain of #include's / parsing during compilation and dump it to a file at the end and also summarize how badly you're re-parsing the same .h files during build. Not exactly that, but do you know clang's -ftime-trace and tools like https://github.com/aras-p/ClangBuildAnalyzer which help analyzing where time is actually spent? (In small repeated headers I don't see much of a problem, but they of course may contain not so small things ...)

Coincidentally in the project I'm currently working I managed to reduce our compile times significantly (~35% faster) using ClangBuildAnalyzer [1]. The main two things that helped were precompiled headers and explicit template instantiations. Unfortunately, the project still remains heavy to compile because of our use of Eigen throughout the entire codebase. The analysis with Clang's "-ftime-trace" show that 75-80% of the compilation time is spent in the optimisation stage, but not really sure what to do about that. [1] https://github.com/aras-p/ClangBuildAnalyzer