Effective optimization strategies on modern C++ compilers

Question

I\'m working on scientific code that is very performance-critical. An initial version of the code has been written and tested, and now, with profiler in hand, it\'s time to

Answer 1

i'm surprised no one has mentioned these two:

• Link time optimization clang and g++ from 4.5 on support link time optimizations. I've heard that on g++ case, the heuristics is still pretty inmature but it should improve quickly since the main architecture is laid out.

  Benefits range from inter procedural optimizations at object file level, including highly sought stuff like inling of virtual calls (devirtualization)

• Project inlining this might seem to some like very crude approach, but it is that very crudeness which makes it so powerful: this amounts at dumping all your headers and .cpp files into a single, really big .cpp file and compile that; basically it will give you the same benefits of link-time optimization in your trip back to 1999. Of course, if your project is really big, you'll still need a 2010 machine; this thing will eat your RAM like there is no tomorrow. However, even in that case, you can split it in more than one no-so-damn-huge .cpp file