gprof : How to generate call graph for functions in shared library that is linked to main program

gprof won’t work, you need to use sprof instead. I found these links helpful:

• How to use sprof?
• http://greg-n-blog.blogspot.com/2010/01/profiling-shared-library-on-linux-using.html

Summary from the 2nd link:

1. Compile your shared library (libmylib.so) in debug (-g) mode. No -pg.
2. export LD_PROFILE_OUTPUT=`pwd`
3. export LD_PROFILE=libmylib.so
4. rm -f $LD_PROFILE.profile
5. execute your program that loads libmylib.so
6. sprof PATH-TO-LIB/$LD_PROFILE $LD_PROFILE.profile -p >log
7. See the log.

I found that in step 2, it needs to be an existing directory — otherwise you get a helpful warning. And in step 3, you might need to specify the library as libmylib.so.X (maybe even .X.Y, not sure) — otherwise you get no warning whatsoever.