[Bug target/59788] New: Mixing libc and libgcc_s unwinders on 64-bit Solaris 10+/x86 breaks EH

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59788

            Bug ID: 59788
           Summary: Mixing libc and libgcc_s unwinders on 64-bit Solaris
                    10+/x86 breaks EH
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: ro at gcc dot gnu.org
          Reporter: ro at gcc dot gnu.org
              Host: i386-pc-solaris2.1[01]
            Target: i386-pc-solaris2.1[01]
             Build: i386-pc-solaris2.1[01]

I've received a few reports in private mail that exception handling on 64-bit
Solaris 10+/x86 is broken when linking with -Bdirect.

The following testcase shows this:

$ cat unwind-direct.cc
#include <stdexcept>

int
main(void)
{
  try
    { throw std::runtime_error( "Catch me if you can!"); }
  catch(...)
    { return 0; }
  return 1;
}
$ g++ -Wl,-Bdirect -m64 -o unwind-direct unwind-direct.cc
$ ./unwind-direct
terminate called after throwing an instance of 'std::runtime_error'
Segmentation Fault (core dumped)

Investigating this with LD_DEBUG=bindings, one finds

$ LD_DEBUG=bindings ./unwind-direct 2>&1 | grep Unwind
03243: 1: binding
file=../../../i386-pc-solaris2.11/amd64/libstdc++-v3/src/.libs/libstdc++.so.6
to file=/lib/64/libc.so.1: symbol '_Unwind_RaiseException'
03243: 1: binding
file=../../../i386-pc-solaris2.11/amd64/libstdc++-v3/src/.libs/libstdc++.so.6
to file=/lib/64/libc.so.1: symbol '_Unwind_GetLanguageSpecificData'
03243: 1: binding
file=../../../i386-pc-solaris2.11/amd64/libstdc++-v3/src/.libs/libstdc++.so.6
to file=/lib/64/libc.so.1: symbol '_Unwind_GetRegionStart'
03243: 1: binding
file=../../../i386-pc-solaris2.11/amd64/libstdc++-v3/src/.libs/libstdc++.so.6
to file=../../amd64/libgcc_s.so.1: symbol '_Unwind_GetIPInfo'
03243: 1: binding
file=../../../i386-pc-solaris2.11/amd64/libstdc++-v3/src/.libs/libstdc++.so.6
to file=../../amd64/libgcc_s.so.1: symbol '_Unwind_Resume_or_Rethrow'
03243: 1: binding file=../../amd64/libgcc_s.so.1 to file=/lib/64/libc.so.1:
symbol '_Unwind_RaiseException'

The problem is that the amd64 Solaris 10+ libc contains an implementation of
the amd64 unwinder, as prescribed by the amd64 ABI, but only those functions
that are listed there.  libgcc_s contains some more, and both implementations
use different internal datastructures, so mixing them wreaks havoc.

This problem has been seen several times during gcc development when it
affected
gcc runtime libraries.

I'm working on a patch to avoid this once and for all by forcing all gcc-built
executables to bind to the unwinder in libgcc_s.

  Rainer