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Background:
In a particular project there are about couple of thousand functions in more than hundred files. The functions are divided to reside in two banks of code memory - fast_mem and slow_mem. But now, since the fast_mem area is limited, its running out of space to accommodate any new code changes.

As part of code review, its been found that some functions in fast_mem have no callers. But the list of functions is too huge to check them one by one manually.

Question:
So, coming to the question, is there a tool that can list the callers of all the functions in the project? With this, I can go ahead and remove functions in fast_mem that don't have any callers.

I use cscope for code browsing along with ctags. But this requires one to input the function name manually. Can this be automated some how to get the complete list?
I also tried Doxygen with its caller graph feature. The result is not so comfortable to use though.

Kara
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Shrinidhi
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    Well, there is always the "poor man's" way: Remove _all_ of the fast_mem functions, compile, look at the list of unresolved symbols in the link error, put those functions back, repeat. – Nemo Nov 10 '11 at 19:05

4 Answers4

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I use Scientific Toolworks Understand

jacknad
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If your compiler is a recent GCC (or if you can switch to GCC 4.6, possibly as a cross-compiler) you might develop a GCC plugin or a MELT extension to find out.

Of course, if you are e.g. doing tricks with function pointers (e.g. unportable pointer arithmetic on function pointers) the original question is undecidable.

Actually, if you are using function pointers, often the only reasonable thing to say is that they can reach only functions of the same signature.

And perhaps the project is important enough so that customizing the compiler to make a better (automatic or semi-automatic) trade-off between fast_mem & slow_mem is worthwhile. This is typically an excellent case for GCC plugins or MELT extensions (but that take some work -days or weeks, not hours-, because you need to understand the internal GCC representations to customize GCC), and you are probably the only one who could do it (because your question is very peculiar to some strange systems).

Basile Starynkevitch
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Let's assume there aren't any odd function pointer games going on. Then you can break out the under-used cflow:

http://www.gnu.org/software/cflow/

Generate a "reverse index" with the -r flag. you'll get a list of every function, followed by where it's called. You can feed it multiple files.

Rob Latham
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You can use static code analysis tool like cppcheck. If you call it with --enable=unusedFunction parameter it will warn about unused function.

ovk
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