libitm/eh_cpp.cc

   1 /* Copyright (C) 2009-2015 Free Software Foundation, Inc.
   2    Contributed by Richard Henderson <rth@redhat.com>.
   3
   4    This file is part of the GNU Transactional Memory Library (libitm).
   5
   6    Libitm is free software; you can redistribute it and/or modify it
   7    under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    Libitm is distributed in the hope that it will be useful, but WITHOUT ANY
  12    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  13    FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14    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 "libitm_i.h"
  26
  27 using namespace GTM;
  28
  29 /* Everything from libstdc++ is weak, to avoid requiring that library
  30    to be linked into plain C applications using libitm.so.  */
  31
  32 #define WEAK  __attribute__((weak))
  33
  34 extern "C" {
  35
  36 extern void *__cxa_allocate_exception (size_t) WEAK;
  37 extern void __cxa_throw (void *, void *, void *) WEAK;
  38 extern void *__cxa_begin_catch (void *) WEAK;
  39 extern void __cxa_end_catch (void) WEAK;
  40 extern void __cxa_tm_cleanup (void *, void *, unsigned int) WEAK;
  41
  42 #if !defined (HAVE_ELF_STYLE_WEAKREF)
  43 void *__cxa_allocate_exception (size_t) { return NULL; }
  44 void __cxa_throw (void *, void *, void *) { return; }
  45 void *__cxa_begin_catch (void *) { return NULL; }
  46 void __cxa_end_catch (void) { return; }
  47 void __cxa_tm_cleanup (void *, void *, unsigned int) { return; }
  48 void _Unwind_DeleteException (_Unwind_Exception *) { return; }
  49 #endif /* HAVE_ELF_STYLE_WEAKREF */
  50
  51 }
  52
  53
  54 void *
  55 _ITM_cxa_allocate_exception (size_t size)
  56 {
  57   void *r = __cxa_allocate_exception (size);
  58   gtm_thr()->cxa_unthrown = r;
  59   return r;
  60 }
  61
  62 void
  63 _ITM_cxa_throw (void *obj, void *tinfo, void *dest)
  64 {
  65   gtm_thr()->cxa_unthrown = NULL;
  66   __cxa_throw (obj, tinfo, dest);
  67 }
  68
  69 void *
  70 _ITM_cxa_begin_catch (void *exc_ptr)
  71 {
  72   gtm_thr()->cxa_catch_count++;
  73   return __cxa_begin_catch (exc_ptr);
  74 }
  75
  76 void
  77 _ITM_cxa_end_catch (void)
  78 {
  79   gtm_thr()->cxa_catch_count--;
  80   __cxa_end_catch ();
  81 }
  82
  83 void
  84 GTM::gtm_thread::revert_cpp_exceptions (gtm_transaction_cp *cp)
  85 {
  86   if (cp)
  87     {
  88       // If rolling back a nested transaction, only clean up unthrown
  89       // exceptions since the last checkpoint. Always reset eh_in_flight
  90       // because it just contains the argument provided to
  91       // _ITM_commitTransactionEH
  92       void *unthrown =
  93           (cxa_unthrown != cp->cxa_unthrown ? cxa_unthrown : NULL);
  94       assert (cxa_catch_count >= cp->cxa_catch_count);
  95       uint32_t catch_count = cxa_catch_count - cp->cxa_catch_count;
  96       if (unthrown || catch_count)
  97         {
  98           __cxa_tm_cleanup (unthrown, this->eh_in_flight, catch_count);
  99           cxa_catch_count = cp->cxa_catch_count;
 100           cxa_unthrown = cp->cxa_unthrown;
 101           this->eh_in_flight = NULL;
 102         }
 103     }
 104   else
 105     {
 106       // Both cxa_catch_count and cxa_unthrown are maximal because EH regions
 107       // and transactions are properly nested.
 108       if (this->cxa_unthrown || this->cxa_catch_count)
 109         {
 110           __cxa_tm_cleanup (this->cxa_unthrown, this->eh_in_flight,
 111               this->cxa_catch_count);
 112           this->cxa_catch_count = 0;
 113           this->cxa_unthrown = NULL;
 114           this->eh_in_flight = NULL;
 115         }
 116     }
 117 }