1// -*- C++ -*- Exception handling routines for Transactional Memory.
2// Copyright (C) 2009-2017 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#include "eh_atomics.h"
28
29using namespace __cxxabiv1;
30
31// Free one C++ exception.
32
33static void
34free_any_cxa_exception (_Unwind_Exception *eo)
35{
36 __cxa_refcounted_exception *h
37 = __get_refcounted_exception_header_from_ue (eo);
38
39 if (__is_dependent_exception (eo->exception_class))
40 {
41 __cxa_dependent_exception *dep
42 = __get_dependent_exception_from_ue (eo);
43
44 h = __get_refcounted_exception_header_from_obj (dep->primaryException);
45
46 __cxa_free_dependent_exception (dep);
47 }
48
49 if (__gnu_cxx::__eh_atomic_dec (&h->referenceCount))
50 __cxa_free_exception (h + 1);
51}
52
53// Cleanup exception handling state while rolling back state for
54// a software transactional memory transaction.
55//
56// UNTHROWN_OBJ is non-null if we've called __cxa_allocate_exception
57// but not yet called __cxa_throw for it.
58//
59// CLEANUP_EXC is non-null if we're currently processing a cleanup
60// along an exception path, but we've not caught the exception yet.
61//
62// CAUGHT_COUNT is the nesting depth of __cxa_begin_catch within
63// the transaction; undo as if calling __cxa_end_catch that many times.
64
65extern "C" void
66__cxxabiv1::__cxa_tm_cleanup (void *unthrown_obj,
67 void *cleanup_exc,
68 unsigned int caught_count) throw()
69{
70 __cxa_eh_globals *globals = __cxa_get_globals_fast ();
71
72 // Handle a C++ exception not yet thrown.
73 if (unthrown_obj)
74 {
75 globals->uncaughtExceptions -= 1;
76 __cxa_free_exception (unthrown_obj);
77 }
78
79 // Handle an exception not yet caught ie. processing a cleanup
80 // in between the throw and the catch.
81 if (cleanup_exc)
82 {
83 _Unwind_Exception *eo
84 = reinterpret_cast <_Unwind_Exception *>(cleanup_exc);
85 if (__is_gxx_exception_class (eo->exception_class))
86 free_any_cxa_exception (eo);
87 else
88 _Unwind_DeleteException (eo);
89 }
90
91 // Do __cxa_end_catch caught_count times, but don't bother running
92 // the destructors for the objects involved. All of that is being
93 // undone by the transaction restart.
94 if (caught_count > 0)
95 {
96 __cxa_exception *h = globals->caughtExceptions;
97
98 // Rethrown foreign exceptions are removed from the stack immediately.
99 // We would have freed this exception via THIS_EXC above.
100 if (h == NULL)
101 return;
102
103 do
104 {
105 __cxa_exception *next;
106 _Unwind_Exception *eo = &h->unwindHeader;
107
108 if (__is_gxx_exception_class (eo->exception_class))
109 {
110 next = h->nextException;
111 free_any_cxa_exception (eo);
112 }
113 else
114 {
115 _Unwind_DeleteException (eo);
116 next = 0;
117 }
118
119 h = next;
120 }
121 while (--caught_count);
122
123 globals->caughtExceptions = h;
124 }
125}
126