[Bug c++/43581] New: exception handling broken across shared libaries

[Bug c++/43581] New: exception handling broken across shared libaries

[rwild at gcc dot gnu dot org]

This looks like a recent regression, it didn't fail sometime early February, if
I remember correctly.  Test somewhat reduced from a libtool testsuite test.

CXX=g++

cat >lib.h <<\EOF
#include <exception>
#include <string>
class libexc : public std::exception {
public:
  libexc (std::string str) : message (str) { }
  ~libexc () throw () { }
  virtual const char *what () const throw ()
  {
    return message.c_str ();
  }
private:
  std::string message;
};
int libfoo () throw (libexc);
EOF

cat >lib.cpp <<\EOF
#include <iostream>
#include "lib.h"

int libbar (void) throw (libexc)
{
  throw libexc ("exception in library");
}

int libfoo (void) throw (libexc)
{
  try {
    libbar ();
  }
  catch (libexc e) {
    std::cerr << "caught inside lib: " << e.what () << '\n';
    throw libexc ("exception from library");
  }
  return 0;
}
EOF

cat >main.cpp <<\EOF
#include "lib.h"

int exceptions_in_lib (void)
{
  try {
    libfoo ();
  }
  catch (libexc e) {
    return 0;
  }
  return 1;
}

int main (void)
{
  if (exceptions_in_lib ())
    return 1;
  return 0;
}
EOF

$CXX -O2 -c main.cpp
$CXX -O2 -c lib.cpp  -fPIC -DPIC
$CXX  -fPIC -DPIC -shared  lib.o -O2 -Wl,-soname -Wl,liba.so.1 -o liba.so.1
ln -sf liba.so.1 liba.so
$CXX -O2 -o main main.o -L. -la
LD_LIBRARY_PATH=`pwd` ./main

leads to:

caught inside lib: exception in library
terminate called after throwing an instance of 'libexc'
  what():  exception from library
./script: line 73: 24698 Aborted                 (core dumped)
LD_LIBRARY_PATH=`pwd` ./main

Happens with

$ gcc -v
Using built-in specs.
COLLECT_GCC=/opt/bin/gcc
COLLECT_LTO_WRAPPER=/opt/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure -C --enable-maintainer-mode --prefix=/opt
LDFLAGS_FOR_TARGET=-Wl,--as-needed --with-boot-ldflags=-Wl,--as-needed
--with-stage1-ldflags=-Wl,--as-needed --enable-lto --without-cloog
--without-ppl  --enable-languages=c,c++,fortran,java,lto,objc,obj-c++
--enable-gold LD=/opt/bin/ld LD_FOR_TARGET=/opt/bin/ld
Thread model: posix
gcc version 4.5.0 20100329 (experimental) (GCC) 

where ld is

$ /opt/bin/ld -v
GNU gold (GNU Binutils 2.20.51.20100319) 1.9


as well as

$ gcc -v
Using built-in specs.
COLLECT_GCC=/opt/bin/gcc
COLLECT_LTO_WRAPPER=/opt/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure -C --enable-maintainer-mode --prefix=/opt
LDFLAGS_FOR_TARGET=-Wl,--as-needed --with-boot-ldflags=-Wl,--as-needed
--with-stage1-ldflags=-Wl,--as-needed --enable-lto --without-cloog
--without-ppl  --enable-languages=c,c++,fortran,java,lto,objc,obj-c++
Thread model: posix
gcc version 4.5.0 20100329 (experimental) (GCC)


-- 
           Summary: exception handling broken across shared libaries
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Keywords: wrong-code, EH
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: rwild at gcc dot gnu dot org
  GCC host triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug other/43581] [4.5 Regression] exception handling broken across shared libaries

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |other
            Summary|exception handling broken   |[4.5 Regression] exception
                   |across shared libaries      |handling broken across
                   |                            |shared libaries
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug other/43581] [4.5 Regression] exception handling broken across shared libaries

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2010-03-29 20:43 -------
This works for me with:
gcc version 4.5.0 20100326 (experimental) [trunk revision 157759] (GCC) 
GNU ld (GNU Binutils for Debian) 2.18.0.20080103
GNU C Library stable release version 2.7, by Roland McGrath et al.

I tried with both 4.5's libstdc++ and with the default 4.3's.

Can you remove from the configure part --as-needed ?  Since that is the major
difference between my build and yours.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   GCC host triplet|x86_64-unknown-linux-gnu    |
 GCC target triplet|                            |x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug other/43581] [4.5 Regression] exception handling broken across shared libaries

[rguenth at gcc dot gnu dot org]

------- Comment #2 from rguenth at gcc dot gnu dot org  2010-03-30 09:46 -------
Works for me as well.  Building GCC with --as-needed is known to at least
break libjava big times (you can see that when testing).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug other/43581] [4.5 Regression] exception handling broken across shared libaries

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug other/43581] [4.5 Regression] exception handling broken across shared libaries with -fuse-linker-plugin

[rwild at gcc dot gnu dot org]

------- Comment #3 from rwild at gcc dot gnu dot org  2010-03-30 16:58 -------
Bug also happens with

$ g++ -v
Using built-in specs.
COLLECT_GCC=/opt/bin/g++
COLLECT_LTO_WRAPPER=/opt/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.5.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure -C --enable-maintainer-mode --prefix=/opt
--with-libelf=/opt --enable-lto --without-cloog --without-ppl --with-mpc=/opt
--enable-gold LD=/opt/bin/ld LD_FOR_TARGET=/opt/bin/ld
--enable-languages=c,c++,fortran,java,lto,objc,obj-c++
Thread model: posix
gcc version 4.5.0 20100329 (experimental) (GCC) 

and

$ /opt/bin/ld -v
GNU gold (GNU Binutils 2.20.51.20100319) 1.9

$ /lib/libc.so.6
GNU C Library stable release version 2.7, by Roland McGrath et al.

But my overriding of LD_LIBRARY_PATH was bogus, as it was wrongly removing
/opt/lib64 which is where the just-installed libstdc++.so.6 lives.  Sorry about
the testcase reduction error (libtool --mode=execute prepends to
LD_LIBRARY_PATH rather than overriding it).


I still see the original testsuite error, though only with '-flto
-fuse-linker-plugin' (adjusting bug title and keywords).  So, from the original
error description, grab the source files, then

CXX='g++'
CXXFLAGS='-O2 -flto'
LDFLAGS=-fuse-linker-plugin
$CXX $CXXFLAGS -c main.cpp
$CXX $CXXFLAGS -c lib.cpp  -fPIC
$CXX -fPIC -shared $CXXFLAGS $LDFLAGS lib.o -Wl,-soname -Wl,liba.so.1 -o
liba.so.1
ln -sf liba.so.1 liba.so
$CXX $CXXFLAGS $LDFLAGS -o main main.o -L. -la
LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH ./main

leads to

Aborted (core dumped)

with a backtrace of

#0  0x00007fc2ae066095 in raise () from /lib/libc.so.6
(gdb) bt
#0  0x00007fc2ae066095 in raise () from /lib/libc.so.6
#1  0x00007fc2ae067af0 in abort () from /lib/libc.so.6
#2  0x00007fc2ae6f94bd in uw_update_context_1 (context=0x7fff7fe51010,
fs=0x7fff7fe50e90) at ../../../gcc/libgcc/../gcc/unwind-pe.h:155
#3  0x00007fc2ae6f97d9 in uw_update_context (context=0x7fff7fe51010,
fs=0x7fff7fe50e90) at ../../../gcc/libgcc/../gcc/unwind-pe.h:155
#4  0x00007fc2ae6fa40b in _Unwind_RaiseException (exc=0x4030b0) at
../../../gcc/libgcc/../gcc/unwind-pe.h:155
#5  0x00007fc2ae7dba31 in __cxa_throw (obj=<value optimized out>, tinfo=<value
optimized out>, dest=<value optimized out>) at
../../../../gcc/libstdc++-v3/libsupc++/eh_throw.cc:78
#6  0x00007fc200000000 in ?? ()
#7  0x00007fff7fe51408 in ?? ()
#8  0x00007fff7fe513f8 in ?? ()
#9  0x0000000000403028 in ?? ()
#10 0x0000000000000000 in ?? ()

It even fails without -O2, the backtrace is then

#0  0x00007f44e1705095 in raise () from /lib/libc.so.6
#1  0x00007f44e1706af0 in abort () from /lib/libc.so.6
#2  0x00007f44e1e7b6ed in __gnu_cxx::__verbose_terminate_handler () at
../../../../gcc/libstdc++-v3/libsupc++/vterminate.cc:93
#3  0x00007f44e1e79906 in __cxxabiv1::__terminate (handler=<value optimized
out>) at ../../../../gcc/libstdc++-v3/libsupc++/eh_terminate.cc:39
#4  0x00007f44e1e79933 in std::terminate () at
../../../../gcc/libstdc++-v3/libsupc++/eh_terminate.cc:49
#5  0x00007f44e1e79a3e in __cxa_throw (obj=<value optimized out>, tinfo=<value
optimized out>, dest=<value optimized out>) at
../../../../gcc/libstdc++-v3/libsupc++/eh_throw.cc:83
#6  0x00007f44e1ecdac7 in libbar () from /tmp/a/liba.so.1
#7  0x00007f44e1ecdb5c in libfoo () from /tmp/a/liba.so.1
#8  0x00000000004010e2 in exceptions_in_lib ()
#9  0x000000000040116e in main ()

If I add -g to '-O2 -flto', the backtrace is

#0  0x00007fd0d5b75095 in raise () from /lib/libc.so.6
#1  0x00007fd0d5b76af0 in abort () from /lib/libc.so.6
#2  0x00007fd0d6207504 in execute_cfa_program (insn_ptr=0x7fd0d628aabd "",
insn_end=0x7fd0d628b717 "E", context=0x7fffc0cf93a0, fs=0x7fffc0cf9220) at
../../../gcc/libgcc/../gcc/unwind-pe.h:155
#3  0x00007fd0d6208a78 in uw_frame_state_for (context=0x7fffc0cf93a0,
fs=0x7fffc0cf9220) at ../../../gcc/libgcc/../gcc/unwind-pe.h:155
#4  0x00007fd0d6209416 in _Unwind_RaiseException (exc=0x4030b0) at
../../../gcc/libgcc/../gcc/unwind-pe.h:155
#5  0x00007fd0d62eaa31 in __cxa_throw (obj=<value optimized out>, tinfo=<value
optimized out>, dest=<value optimized out>) at
../../../../gcc/libstdc++-v3/libsupc++/eh_throw.cc:78
#6  0x00007fd0d633e57e in libbar () from /tmp/a/liba.so.1
#7  0x00007fffc0cf9788 in ?? ()
#8  0x0000000000403028 in ?? ()
#9  0x0000000000000000 in ?? ()


Without -fuse-linker-plugin, it passes for me.

I get a similar failure for exceptions from dlopen'ed modules, if you like I
can provide a testcase for that as well.


-- 

rwild at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |lto
            Summary|[4.5 Regression] exception  |[4.5 Regression] exception
                   |handling broken across      |handling broken across
                   |shared libaries             |shared libaries with -fuse-
                   |                            |linker-plugin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug lto/43581] exception handling broken across shared libaries with -fuse-linker-plugin

[pinskia at gcc dot gnu dot org]

------- Comment #4 from pinskia at gcc dot gnu dot org  2010-03-30 20:29 -------
So this cannot be a regression.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED
          Component|other                       |lto
            Summary|[4.5 Regression] exception  |exception handling broken
                   |handling broken across      |across shared libaries with
                   |shared libaries with -fuse- |-fuse-linker-plugin
                   |linker-plugin               |
   Target Milestone|4.5.0                       |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug lto/43581] exception handling broken across shared libaries with -fuse-linker-plugin

[rguenth at gcc dot gnu dot org]

------- Comment #5 from rguenth at gcc dot gnu dot org  2010-03-31 09:22 -------
It is enough to build the shared library with -flto -fuse-linker-plugin.
You then get

/tmp> LD_LIBRARY_PATH=. ./main
terminate called after throwing an instance of 'libexc'
  what():  exception in library
Aborted


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2010-03-31 09:22:54
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581

[Bug lto/43581] exception handling broken across shared libaries with -fuse-linker-plugin

[rwild at gcc dot gnu dot org]

------- Comment #6 from rwild at gcc dot gnu dot org  2010-03-31 18:49 -------
Here's the analogous test case from Libtool for dlopen'ed modules.  Also passes
when -fuse-linker-plugin is removed from the link line for module.so.

CXX=g++
CXXFLAGS='-O2 -flto'
LDFLAGS='-fuse-linker-plugin'

cat >module.h <<\EOF
#include <exception>
#include <string>
class modexc : public std::exception {
public:
  modexc (std::string str) : message (str) { }
  ~modexc () throw () { }
  virtual const char *what () const throw ()
  {
    return message.c_str ();
  }
private:
  std::string message;
};
extern "C" int modfoo () throw (modexc);
EOF

cat >module.cpp <<\EOF
#include <iostream>
#include "module.h"

int modbar (void) throw (modexc)
{
  throw modexc ("exception in module");
}

extern "C"
int modfoo (void) throw (modexc)
{
  try {
    modbar ();
  }
  catch (modexc e) {
    std::cerr << "caught inside module: " << e.what () << '\n';
    throw modexc ("exception from module");
  }
  return 0;
}
EOF

cat >main.cpp <<\EOF
#include <dlfcn.h>
#include <iostream>
#include <exception>
#include <string>
#include "module.h"

class exc : public std::exception {
public:
  exc (std::string str) : message (str) { }
  ~exc () throw () { }
  virtual const char *what () const throw ()
  {
    return message.c_str ();
  }
private:
  std::string message;
};

int exceptions_in_module (void)
{
  std::cerr << "exceptions_in_module\n";

  void *handle = dlopen ("module.so", RTLD_GLOBAL | RTLD_LAZY);
  if (handle == NULL)
    {
      std::cerr << "dlopen failed: " << dlerror () << '\n';
      return 1;
    }

  typedef int (*pfun) (void);
  pfun pf = (pfun) dlsym (handle, "modfoo");
  if (pf == NULL)
    {
      std::cerr << "dlsym failed: " << dlerror () << '\n';
      return 1;
    }

  try {
    (*pf) ();
  }
  catch (modexc e) {
    std::cerr << "caught: " << e.what () << '\n';
    if (dlclose (handle))
      {
        std::cerr << "dlclose failed: " << dlerror () << '\n';
        return 1;
      }
    return 0;
  }
  return 1;
}

int main (void)
{
  if (exceptions_in_module ())
    return 1;
  return 0;
}
EOF

$CXX $CXXFLAGS -c main.cpp
$CXX $CXXFLAGS -c module.cpp -fPIC -o module.o
$CXX $CXXFLAGS $LDFLAGS -fPIC -shared module.o -o module.so
$CXX $CXXFLAGS $LDFLAGS -o main main.o -Wl,--export-dynamic -ldl
LD_LIBRARY_PATH=`pwd`:$LD_LIBRARY_PATH ./main


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43581