How to get a call stack backtrace? (deeply embedded, no library support)

Question

I want my exception handlers and debug functions to be able to print call stack backtraces, basically just like the backtrace() library function in glibc. Unfortunately, my C li

Answer 1

Some compilers, like GCC optimize function calls like you mentioned in the example. For the operation of the code fragment, it is not needed to store the intermediate return pointers in the call chain. It's perfectly OK to return from func3() to main(), as the intermediate functions don't do anything extra besides calling another function.

It's not the same as code elimination (actually the intermediate functions could be completely optimized out), and a separate compiler parameter might control this kind of optimisation.

If you use GCC, try -fno-optimize-sibling-calls

Another handy GCC option is -mno-sched-prolog, which prevents instruction reordering in the function prologue, which is vital, if you want to parse the code byte-by-byte, like it is done here: http://www.kegel.com/stackcheck/checkstack-pl.txt