# "smart-link" a C program.



## fredvs (Oct 14, 2016)

Hello.

Here how to "smart-link" a C program.

It comes from http://stackoverflow.com/questions/6687630/how-to-remove-unused-c-c-symbols-with-gcc-and-ld

You will need to link your program with `--gc-sections` option.


=>

For GCC, this is accomplished in two stages:

First compile the data but tell the compiler to separate the code into separate sections within the translation unit. This will be done for functions, classes, and external variables by using the following two compiler flags:

`-fdata-sections -ffunction-sections`
Link the translation units together using the linker optimization flag (this causes the linker to discard unreferenced sections):

`-Wl,--gc-sections`
So if you had one file called test.cpp that had two functions declared in it, but one of them was unused, you could omit the unused one with the following command to gcc(g++):

`gcc -Os -fdata-sections -ffunction-sections test.cpp -o test -Wl,--gc-sections`
(Note that -Os is an additional compiler flag that tells GCC to optimize for size)


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