[Bug fortran/46686] Improve backtracing (unwinding) on MinGW

["burnus at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46686

--- Comment #2 from Tobias Burnus <burnus at gcc dot gnu.org> 2011-05-14 21:11:07 UTC ---
(In reply to comment #1)
> The generic code below relies on libgcc routines, it should work anywhere,
> doesn't it?

Well, on x86-64-linux, I needed at least the following modifications:

- #include "libgfortran.h"
- #include <stdint.h> /* For uintptr_t. */

- On Linux Dl_info does not work by default; as man dladdr states:
       Glibc adds two functions not described by POSIX, with prototypes

       #define _GNU_SOURCE         /* See feature_test_macros(7) */
       #include <dlfcn.h>
  one could assume that _GNU_SOURCE had do be defined - but that does not work.
  With   #define __USE_GNU   it works

- trace_function: The unused parameter gives a fatal warning - thus, I used
__attribute__((undefined)).

Then it compiles - but linking an executable fails with: "undefined reference
to `dladdr", unless I link with "-ldl". But then I get a backtrace of the form:

0x2af48a719fa7
0x2af48a7e2019
0x400698
0x400688
0x40067d
0x4006a1
0x4006d7
0x2af48b0dbbfd (__libc_start_main)

 * * *

Regarding the functionality

* libgo/configure.ac has the check:
  GCC_CHECK_UNWIND_GETIPINFO

Ditto for libada, libjava and libstdc++-v3.

Thus, we might pick some functionality from:

* libgo/runtime/go-unwind.c
* libjava/exception.cc
* libjava/stacktrace.cc