The Ada -E binder option stores a stack traceback in the exception.
This doesn't work with llvm-gcc.  Testcase:

procedure Trace is
begin
   raise Program_Error;
end;

$ gnatmake trace.adb -bargs -E
gcc -c trace.adb
gnatbind -aO./ -E -I- -x trace.ali
gnatlink trace.ali
$ ./trace
Segmentation fault (core dumped)

How such stuff is represented in terms of gcc builtins / llvm IR ?

A quick glance shows it using:

__builtin_frame_address
_Unwind_Backtrace
_Unwind_GetIP