Is there a compiler feature to inject custom function entry and exit code?

Question

Currently coding on Windows with VS2005 (but wouldn\'t mind knowing if there are options for other compilers and platforms. I\'m most interested in OSX as an alternative pl

Answer 1

It's Microsoft-specific, but you can hook into the _penter and _pexit functions to do something when entering and exiting a function -- you'll have to compile your project with some special flags.

There's a little bit of a tutorial here, and you can find a few more results on how to use them on Google. Also, this blog post goes into some detail on the assembly that you need to do to avoid messing up the stack on entry and exit.

Answer 2

OpenWatcom C and C++ compilers have -ee and -ep parameters for that:

-ee           call epilogue hook routine
-ep[=<num>]   call prologue hook routine with <num> stack bytes available

They will cause the compiler to emit calls to __EPI and __PRO user-defined hook routines.

There is also

-en           emit routine names in the code segment

that will emit the function name into the object code as a string of characters just before the function prologue sequence is generated. May be useful for the __PRO routine.

More information in these and other compiler options can be found in the C/C++ user guide available among other manuals at http://openwatcom.org/index.php/Manuals

Answer 3

You're looking for something called aspect oriented programming or AOP.

This isn't something that's supported natively in C (or C++). There are some library based implementations listed on the linked page for C (though I don't know how mature / useful these are)

Answer 4

GCC has the -finstrument-functions flag which allows you to define two functions that will be called at the beginning and end of each function call:

void __cyg_profile_func_enter(void *this_fn, void *call_site);
void __cyg_profile_func_exit(void *this_fn, void *call_site);