Compiling the C++ program faster
I have been taking part in Competitve Programming for a while now.
I use vim to write my code and have some helpers to compile and run the test cases.
I have been facing slow compile times for a long time now, but I never invested time in thinking about how to optimise it. But I have been getting increasingly irritated for a while now.
My base template, solution.cpp
has #include <bits/stdc++.h>. While this makes our life easier by not worrying about importing each header separetly,
it puts a huge load on the compile time.
We can reduce the compile time by pre-compiling the bits/stdc++.h.
Steps
- Find the path of header file, On my Mac it was
/usr/local/Cellar/gcc/13.2.0/include/c++/13/x86_64-apple-darwin23/bits.- One easy way to find this on your system is to compile a file that includes this header with
-Hflag ofgcc. This will spit out the path of each header file getting included in your executable.
- One easy way to find this on your system is to compile a file that includes this header with
- Compile the
stdc++.hfile with Exactly the same flag as you used for your file compilation. Please note that the precompiled binary will only be used if the compiler flags matches.- I ran :
g++-13 -std=c++17 -Wall -Wextra -Wshadow -Wconversion -DDEBUG /usr/local/Cellar/gcc/13.2.0/include/c++/13/x86_64-apple-darwin23/bits/stdc++.h - This will produce
stdc++.h.gchfile on the same path.
- I ran :
- Now you should see the speed up next time you compile the file.