Re: [Libunwind-devel] Libunwind reports the same ip and fp for Fortran code compiled with PGI

[Lassi Tuura]

You can use "otool -l" to list segments in a Mach-O binary. You'd be looking for compiler options that create __unwind_info, presumably.

However libunwind doesn't currently support OS X or Mach-O at all. It's unclear to me from your question what you tried. There's a system libunwind, but it has little or nothing to do with this one, and doesn't for example have the same API. But see http://opensource.apple.com/source/libunwind/libunwind-30/include/mach-o/compact_unwind_encoding.h for some docs.

On Tue, Feb 3, 2015 at 10:09 PM, Scott Biersdorff <address@hidden> wrote:

Thanks, adding this worked great on Linux, Do you know the equivalent section in a Mach-O binary (OSX) that needs to be present for libunwind to get the correct IP and FP (eh_frame_hdr does not appear to be present for gnu compiled binaries)?

- Scott

-----Original Message-----
From: Chris January [mailto:address@hidden]
Sent: Tuesday, January 20, 2015 1:45 AM
To: Scott Biersdorff
Cc: address@hidden; Juul VanderSpek
Subject: Re: [Libunwind-devel] Libunwind reports the same ip and fp for Fortran code compiled with PGI

Hello Scott,

The PGI compiled executable is missing the .eh_frame_hdr section. Try adding -Wl,--eh-frame-hdr to LDFLAGS in Makefile. This fixes the problem.

Regards,
Chris January - VP Engineering - Allinea Software Ltd.

On Mon, 2015-01-19 at 22:02 +0000, Scott Biersdorff wrote:
> We are looking into an issue with libunwind where it reports the same
> address as both a IP and FP. This happens with a simple PGI compiled
> Fortran example. This same example compiled with gfortran reports
> different addresses:
>
>
>
> ./fortran-standalone.gnu.exe
>
>  ip= 0x0000000000400b19  fp= 0x0000000000400aff
>
>  ip= 0x0000000000400a45  fp= 0x000000000040098d
>
>  ip= 0x0000000000400aa4  fp= 0x0000000000400a82
>
>  ip= 0x0000000000400af8  fp= 0x0000000000400ac4
>
>  ip= 0x00007f43bad53ec5  fp= 0x00007f43bad53dd0
>
>  ip= 0x00000000004008c9  fp= 0x00000000004008a0
>
>
>
> ./fortran-standalone.pgi.exe
>
>  ip= 0x00000000004027eb  fp= 0x00000000004027eb
>
>  ip= 0x00000000004027b0  fp= 0x00000000004027b0
>
>  ip= 0x0000000000402712  fp= 0x0000000000402712
>
>  ip= 0x00000000004026c4  fp= 0x00000000004026c4
>
>
>
> (Note that both stacks run into strange addresses unknown in the
> object file; my suspicion is that these are trampoline functions
> somewhere on stack or heap).
>
>
>
> I’ve attached the sources and binaries for this example. Can you help
> us understand what is particular about this binary compiled by PGI
> that causes this? Is there another way to retrieve the function
> pointer?



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