How to generate the function stack trace of the last request made?
A function trace will only show you the function calls that lead directly to that piece of code.

PHP provides the functions debug_print_backtrace() for that, which is however not very readable but it will result a huge amount of text. devel.module provides a ddebug_backtrace()function, which us much easier to read.

To see all function calls of a single page, you need to install a profiler like XhProf.