Instantiate inline class method

Question

I write a library, this library includes a function void f() this function is a one line function and when I compile the library to shared object with -O3 gcc optimization flag it is inlined. I call it in a critical place in the code (must be as fast as possible) and I don't want to call it not inlined (hits performance substantially). The problem is that this function is part of the API that my library exposes so when library users link with my library and call this function they get undefined reference linkage error. Is there a way for my code to use the function inlined but still instantiate it in the object file so library users will be able to link and use it? (When I say "instantiate it in the object file" I mean I'd like to see it when I run objdump -t on the shared object). Just to make it clear, I'm not interested in a solution to wrap it with a function

void F() __attribute__((noinline)) { f(); }

Because I have many functions like that and I don't want to keep a copy for every function due to the enormous amount of overhead. I'm looking for a way to tell the compiler to use it inline when the definition is available to it, but still instantiate the function in the object file, so library users can link to with it too.

Would it help to store its address in a `volatile` variable somewhere in your code? — Angew is no longer proud of SO, Jul 07 '15 at 14:39
I was looking for a more conventional way to do this, some way to tell the compiler what I want from it, not some hack. — e271p314, Jul 07 '15 at 14:41

score 0 · Accepted Answer · edited May 23 '17 at 11:51

Check out this How can I tell gcc not to inline a function? I found this solution the most appropriate. I'd like to note the main thing is that the code inside the library is still inlined so there is no performance penalty but users can still use the API as all functions have instantiation

Also another possible solution in the compilation level is to use -fkeep-inline-functions gcc switch which also instantiates inline functions and and uses them inlined where possible (unlike -fno-inline switch). The main problem with this switch is that if your code is heavily templated compilation time is much longer and the binary product becomes much bigger

Instantiate inline class method

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