1 // -*- C++ -*- Exception handling routines for Transactional Memory. 2 // Copyright (C) 2009-2018 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 29 using namespace __cxxabiv1; 30 31 // Free one C++ exception. 32 33 static void 34 free_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 65 extern "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