Re: mprof and new systems..

On Sat, Jun 14, 2008 at 1:10 AM, Julian Elischer <julian_at_elischer.org> wrote:
> Julian Elischer wrote:
[..]
>> Anyone with ideas as to how to make the port act reliably?

Check out __builtin_return_address() and __builtin_frame_pointer().

Or look at src/sys/i386/i386/stack_machdep.c  (it is present on all platforms).

info gcc -> 'C Extensions' -> 'Return Address'

 -- Built-in Function: void * __builtin_return_address (unsigned int
          LEVEL)
     This function returns the return address of the current function,
     or of one of its callers.
..
 -- Built-in Function: void * __builtin_frame_address (unsigned int
          LEVEL)
     This function is similar to `__builtin_return_address', but it
     returns the address of the function frame rather than the return
     address of the function.

__builtin_frame_address() on i386 is basically:
        register_t ebp;
        __asm __volatile("movl %%ebp,%0" : "=r" (ebp));
or for amd64:
        register_t rbp;
        __asm __volatile("movq %%rbp,%0" : "=r" (rbp));


-- 
Peter Wemm - peter_at_wemm.org; peter_at_FreeBSD.org; peter_at_yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5
"If Java had true garbage collection, most programs would delete
themselves upon execution." -- Robert Sewell