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
free_any_cxa_exception(_Unwind_Exception * eo)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
__cxa_tm_cleanup(void * unthrown_obj,void * cleanup_exc,unsigned int caught_count)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 }
127