The source file comprise a simple but efficient utility that allows the display of a function call tree in a C/C++ program at run-time.

• etrace.c - tracer linked with your application to enable run-time tracing

This is free software placed in the public domain. Enjoy!

• gcc version 2.95 or later
• linker with support for --export-dynamic

There is an example in the example sub-dir. To compile it, do:

cd example
make

You should now have executables called crumble_c and crumble_cpp. Running them should give you a recipe for an apple crumble with 1-second pauses between sentences to demonstrate the run-time ability. Now let's get to this function call tree:

To get the tree at run-time, open terminal and run:

make run

You should see this:

main
| Crumble_make_apple_crumble
| | Crumble_buy_stuff
| | | Crumble_buy
| | | Crumble_buy (total: 5 times)
| | Crumble_prepare_apples
| | | Crumble_skin_and_dice
| | Crumble_mix
| | Crumble_finalize
| | | Crumble_put
| | | Crumble_put (total: 2 times)
| | Crumble_cook
| | | Crumble_put
| | | Crumble_bake

gcc 2.95 has a nifty feature called "instrument-functions", that adds a couple of function calls to all functions in your code. Every time a function starts, a function called __cyg_profile_func_enter() is called, and every time a function exits, a function called __cyg_profile_func_exit() is called.

The code in etrace.c simply gets the address of currently entered function and gets it's name from the dynamic symbol table. In case of C++ the name is also demangled to be more readable.

To trace a stand-alone program, there is no need to #include any additional file. Just compile you code with the -finstrument-functions and -rdynamic gcc options and link it against etrace.c, dl and rt library. This should do it.

Feedback is always welcome. However, this code is not supported. This is only 100 lines of C, so if you need additional features I'd say you are better off on your own. :-)

N. Devillard Wed May 9 15:29:04 CEST 2001

V. Chudnovsky Mon Mar 8 2004