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
Mine, patch in progress.
Created attachment 31843 [details] initial patch The attached initial patch works fine and fixes the testcase from the PR, but is unacceptable as is. Initially, I attempted to force direct binding to the libgcc_s unwinder by linking with a special mapfile if linking with -lgcc_s. This doesn't work since libtool builds shared libraries with -shared -nostdlib, adding -lgcc_s itself. The second attempt (attached) instead uses that mapfile when -shared is passed. When libtool adds -lgcc_s -lc -lgcc_s itself, it usually `optimizes' this into -lc -lgcc_s. When direct binding is in effect due to the mapfile, we achieve exactly what this patch intends to avoid, namely binding to the partial unwinder in amd64 libc. This can be avoided by patching libtool to disable this optimization on *solaris2*, which this patch does. While this works fine for the gcc runtime libraries, as can be observed with elfdump -y, gcc 4.9 cannot be released with this patch included: even if the libtool (ltmain.sh actually) patch were accepted upstream, every package built with libtool will contain an old copy without that change, causing the breakage this patch is designed to avoid. While the optimization can be avoided by invoking libtool with --preserve-dup-deps, this seem unacceptable, as would requiring users to run libtoolize from a hypothetical new libtool release with the ltmain.sh patch.
Patch submitted.
Author: ro Date: Tue Feb 4 09:31:38 2014 New Revision: 207454 URL: http://gcc.gnu.org/viewcvs?rev=207454&root=gcc&view=rev Log: Ensure libgcc_s unwinder is always used on 64-bit Solaris 10+/x86 (PR target/59788) gcc: PR target/59788 * config/sol2.h (LINK_LIBGCC_MAPFILE_SPEC): Define. (LINK_SPEC): Use it for -shared, -shared-libgcc. libgcc: PR target/59788 * config/t-slibgcc-sld (libgcc-unwind.map): New target. (install-libgcc-unwind-map-forbuild): New target. (all): Depend on install-libgcc-unwind-map-forbuild. (install-libgcc-unwind-map): New target. (install): Depend on install-libgcc-unwind-map. gcc/testsuite: PR target/59788 * g++.dg/eh/unwind-direct.C: New test. toplevel: PR target/59788 * ltmain.sh (opt_duplicate_compiler_generated_deps): Enable on *solaris2*. Added: trunk/gcc/testsuite/g++.dg/eh/unwind-direct.C Modified: trunk/ChangeLog trunk/gcc/ChangeLog trunk/gcc/config/sol2.h trunk/gcc/testsuite/ChangeLog trunk/libgcc/ChangeLog trunk/libgcc/config/t-slibgcc-sld trunk/ltmain.sh
Fixed for 4.9.0.