Re: dwarf2 unwind info check broken

[Andreas Jaeger <aj at suse dot de>]

Jakub Jelinek <jakub@redhat.com> writes:

> On Sun, Mar 17, 2002 at 01:25:16PM +0100, Andreas Jaeger wrote:
>> Andreas Jaeger <aj@suse.de> writes:
>> 
>> > Andreas Jaeger <aj@suse.de> writes:
>> >
>> >> With current binutils and both gcc 2.95.3 and GCC 3.2 CVS on
>> >> i686-linux-gnu I now get:
>> >>
>> >> checking for DWARF2 unwind info support... (cached) no
>> >>
>> >> The test program from configure:
>> >> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> >> static char __EH_FRAME_BEGIN__[];
>> >
>> > I figured out the problem: the []; gets removed by autoconf - but my
>> > autoconf version didn't remove it. :-(
>> 
>> But that's not the whole story, something is still broken for me:
>
> There are 2 different cases if the register_frame_info &
> register_frame check both fail.
> Either you have gcc 3.1+ configured with old binutils, or new binutils.
> In the former case, we should define HAVE_DWARF2_UNWIND_INFO and
> HAVE_DWARF2_UNWIND_INFO_STATIC, in the latter case nothing (as in that
> case no registry should happen).
>
> So the unwind info check should be extended to something like
> (untested):
>
>  if AC_TRY_COMMAND([${CC-cc} $CFLAGS -DCHECK__register_frame_info
>                              -nostdlib -nostartfiles
>                              -o conftest conftest.c -lgcc >&AC_FD_CC]); then
>    libc_cv_gcc_dwarf2_unwind_info=static
>  else
>    libc_cv_gcc_dwarf2_unwind_info=no
>  fi
> +if AC_TRY_COMMAND([${CC-cc} $CFLAGS -DCHECK__register_frame_info
> +                            -nostdlib -nostartfiles
> +                            -o conftest conftest.c -lgcc -lgcc_eh >&AC_FD_CC]); then
> +  if ${CC-cc} $CFLAGS -DCHECK__register_frame_info -nostdlib -nostartfiles \
> +     -o conftest conftest.c -lgcc -lgcc_eh 2>&1 >/dev/null \
> +     | grep -q -- --eh-frame-hdr; then
> +    libc_cv_gcc_dwarf2_unwind_info=no_registry_needed
> +  else
> +    libc_cv_gcc_dwarf2_unwind_info=static
> +  fi
> +else
> +  libc_cv_gcc_dwarf2_unwind_info=no
> +fi
>  if test $libc_cv_gcc_dwarf2_unwind_info = no; then
>    if AC_TRY_COMMAND([${CC-cc} $CFLAGS -DCHECK__register_frame
>                                -nostdlib -nostartfiles
>                                -o conftest conftest.c -lgcc >&AC_FD_CC]);
>  then
>      libc_cv_gcc_dwarf2_unwind_info=yes
>    else
>      libc_cv_gcc_dwarf2_unwind_info=no
>    fi
>  fi
>
>> So, how can we fix that configure test - and do we need to add -lgcc_s
>> for sln?
>
> Um, why? Especially since adding -lgcc_s to -static will lead to failed link
> (there is no static -lgcc_s).
> gcc takes care of adding -lgcc_eh when it is necessary for -static link.

Strange, it now works for me - but I installed different binutils.
I'll try to investigate something more what's the problem is,

Andreas
-- 
 Andreas Jaeger
  SuSE Labs aj@suse.de
   private aj@arthur.inka.de
    http://www.suse.de/~aj