libstdc++-v3/libsupc++/eh_tm.cc

   1 // -*- C++ -*- Exception handling routines for Transactional Memory.
   2 // Copyright (C) 2009-2016 Free Software Foundation, Inc.
   3 //
   4 // This file is part of GCC.
   5 //
   6 // GCC is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 3, or (at your option)
   9 // any later version.
  10 //
  11 // GCC is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // Under Section 7 of GPL version 3, you are granted additional
  17 // permissions described in the GCC Runtime Library Exception, version
  18 // 3.1, as published by the Free Software Foundation.
  19
  20 // You should have received a copy of the GNU General Public License and
  21 // a copy of the GCC Runtime Library Exception along with this program;
  22 // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  23 // <http://www.gnu.org/licenses/>.
  24
  25 #include <cstdlib>
  26 #include "unwind-cxx.h"
  27
  28 using namespace __cxxabiv1;
  29
  30 // Free one C++ exception.
  31
  32 static void
  33 free_any_cxa_exception (_Unwind_Exception *eo)
  34 {
  35   __cxa_refcounted_exception *h
  36     = __get_refcounted_exception_header_from_ue (eo);
  37
  38   if (__is_dependent_exception (eo->exception_class))
  39     {
  40       __cxa_dependent_exception *dep
  41         = __get_dependent_exception_from_ue (eo);
  42
  43       h = __get_refcounted_exception_header_from_obj (dep->primaryException);
  44
  45       __cxa_free_dependent_exception (dep);
  46     }
  47
  48 #if __GCC_ATOMIC_INT_LOCK_FREE > 1
  49   if (__atomic_sub_fetch (&h->referenceCount, 1, __ATOMIC_ACQ_REL) == 0)
  50 #endif
  51     __cxa_free_exception (h + 1);
  52 }
  53
  54 // Cleanup exception handling state while rolling back state for
  55 // a software transactional memory transaction.
  56 //
  57 // UNTHROWN_OBJ is non-null if we've called __cxa_allocate_exception
  58 // but not yet called __cxa_throw for it.
  59 //
  60 // CLEANUP_EXC is non-null if we're currently processing a cleanup
  61 // along an exception path, but we've not caught the exception yet.
  62 //
  63 // CAUGHT_COUNT is the nesting depth of __cxa_begin_catch within
  64 // the transaction; undo as if calling __cxa_end_catch that many times.
  65
  66 extern "C" void
  67 __cxxabiv1::__cxa_tm_cleanup (void *unthrown_obj,
  68                               void *cleanup_exc,
  69                               unsigned int caught_count) throw()
  70 {
  71   __cxa_eh_globals *globals = __cxa_get_globals_fast ();
  72
  73   // Handle a C++ exception not yet thrown.
  74   if (unthrown_obj)
  75     {
  76       globals->uncaughtExceptions -= 1;
  77       __cxa_free_exception (unthrown_obj);
  78     }
  79
  80   // Handle an exception not yet caught ie. processing a cleanup
  81   // in between the throw and the catch.
  82   if (cleanup_exc)
  83     {
  84       _Unwind_Exception *eo
  85         = reinterpret_cast <_Unwind_Exception *>(cleanup_exc);
  86       if (__is_gxx_exception_class (eo->exception_class))
  87         free_any_cxa_exception (eo);
  88       else
  89         _Unwind_DeleteException (eo);
  90     }
  91
  92   // Do __cxa_end_catch caught_count times, but don't bother running
  93   // the destructors for the objects involved.  All of that is being
  94   // undone by the transaction restart.
  95   if (caught_count > 0)
  96     {
  97       __cxa_exception *h = globals->caughtExceptions;
  98
  99       // Rethrown foreign exceptions are removed from the stack immediately.
 100       // We would have freed this exception via THIS_EXC above.
 101       if (h == NULL)
 102         return;
 103
 104       do
 105         {
 106           __cxa_exception *next;
 107           _Unwind_Exception *eo = &h->unwindHeader;
 108
 109           if (__is_gxx_exception_class (eo->exception_class))
 110             {
 111               next = h->nextException;
 112               free_any_cxa_exception (eo);
 113             }
 114           else
 115             {
 116               _Unwind_DeleteException (eo);
 117               next = 0;
 118             }
 119
 120           h = next;
 121         }
 122       while (--caught_count);
 123
 124       globals->caughtExceptions = h;
 125     }
 126 }