Do unused functions get optimized out?

Question

A fairly simple question... Compilers these days tend to do a significant amount of optimizations. Do they also remove unused functions from the final output?

Answer 1

It depends on the compiler. Visual C++ 9 can do that - unused static functions are removed at compilation phase (there's even a C4505 warning for that), unused functions with external linkage can be removed at link phase depending on linker settings.

Answer 2

MSVC (the Visual Studio compiler/linker) can do this if you compile with /Gy and link with /OPT:REF.

GCC/binutils can do this if you compile with -ffunction-sections -fdata-sections and link with --gc-sections.

Don't know about other compilers.