I am profiling my program;s compilation and looking for bottlenecks. I originally thought template instantiation would be the most expensive part but seems to be callgraph funciton expansion. Problem is, I have no idea what that stage refers to.
callgraph functions expansion : 28.98 ( 80%) 0.95 ( 39%) 29.98 ( 73%) 782M ( 60%)
template instantiation : 2.36 ( 7%) 0.47 ( 19%) 2.84 ( 7%) 191M ( 15%)
I have tried to search it up online but I find no answers.
CodePudding user response：
It appears to be part of the optimization process implemented by GCC. I was able to find one reference, The GCC call graph module, which describes it as the final step performed by the front-end of the compiler:
- Expansion: We proceed in reverse DFS order on functions that are still present in the call-graph, applying inter-procedural optimizations such as inlining to the functions, and finally leaving them to the back-end to do the actual optimization and compilation.