Embedded software developers normally prefer to use a pure C, however in some cases and especially in complex projects using C++ gives a more clear structured implementation. Unfortunately, by default C++ compiler produces pretty big binaries. This can be acceptable in case of a normal OS with a big amount of memory, but things are getting complicated when it comes to microcontrollers. I played a bit with compiler and linker options and it seems that the most size-consuming options CPP features are RTTI (run-time type information) and exceptions. I strongly believe that these are not things you can’t live without. So, I came up with the following configuration (valid for GCC toolchain):
C++ compiler flags
| Flag | Description |
|---|---|
| -fno-rtti | (Don’t generate run-time typed identification) |
| -fno-exceptions | (Don’t catch exceptions) |
Linker flags:
| Flag | Description |
|---|---|
| -flto | (Use link time optimization) |
| -lstdc++ | Use C++ libraries. You use them, right? |
Resulting binary size is pretty small and comparable with the equivalent C compiler output. Of course, you can reduce the size even more, but flags above are the most effective.