libcxxabi/src/cxa_exception.h

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //
   8 //  This file implements the "Exception Handling APIs"
   9 //  https://itanium-cxx-abi.github.io/cxx-abi/abi-eh.html
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef _CXA_EXCEPTION_H
  14 #define _CXA_EXCEPTION_H
  15
  16 #include <exception> // for std::unexpected_handler and std::terminate_handler
  17 #include "cxxabi.h"
  18 #include "unwind.h"
  19
  20 namespace __cxxabiv1 {
  21
  22 static const uint64_t kOurExceptionClass          = 0x434C4E47432B2B00; // CLNGC++\0
  23 static const uint64_t kOurDependentExceptionClass = 0x434C4E47432B2B01; // CLNGC++\1
  24 static const uint64_t get_vendor_and_language     = 0xFFFFFFFFFFFFFF00; // mask for CLNGC++
  25
  26 _LIBCXXABI_HIDDEN uint64_t __getExceptionClass  (const _Unwind_Exception*);
  27 _LIBCXXABI_HIDDEN void     __setExceptionClass  (      _Unwind_Exception*, uint64_t);
  28 _LIBCXXABI_HIDDEN bool     __isOurExceptionClass(const _Unwind_Exception*);
  29
  30 struct _LIBCXXABI_HIDDEN __cxa_exception {
  31 #if defined(__LP64__) || defined(_WIN64) || defined(_LIBCXXABI_ARM_EHABI)
  32     // Now _Unwind_Exception is marked with __attribute__((aligned)),
  33     // which implies __cxa_exception is also aligned. Insert padding
  34     // in the beginning of the struct, rather than before unwindHeader.
  35     void *reserve;
  36
  37     // This is a new field to support C++11 exception_ptr.
  38     // For binary compatibility it is at the start of this
  39     // struct which is prepended to the object thrown in
  40     // __cxa_allocate_exception.
  41     size_t referenceCount;
  42 #endif
  43
  44     //  Manage the exception object itself.
  45     std::type_info *exceptionType;
  46     void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
  47     std::unexpected_handler unexpectedHandler;
  48     std::terminate_handler  terminateHandler;
  49
  50     __cxa_exception *nextException;
  51
  52     int handlerCount;
  53
  54 #if defined(_LIBCXXABI_ARM_EHABI)
  55     __cxa_exception* nextPropagatingException;
  56     int propagationCount;
  57 #else
  58     int handlerSwitchValue;
  59     const unsigned char *actionRecord;
  60     const unsigned char *languageSpecificData;
  61     void *catchTemp;
  62     void *adjustedPtr;
  63 #endif
  64
  65 #if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
  66     // This is a new field to support C++11 exception_ptr.
  67     // For binary compatibility it is placed where the compiler
  68     // previously added padding to 64-bit align unwindHeader.
  69     size_t referenceCount;
  70 #endif
  71     _Unwind_Exception unwindHeader;
  72 };
  73
  74 // http://sourcery.mentor.com/archives/cxx-abi-dev/msg01924.html
  75 // The layout of this structure MUST match the layout of __cxa_exception, with
  76 // primaryException instead of referenceCount.
  77 struct _LIBCXXABI_HIDDEN __cxa_dependent_exception {
  78 #if defined(__LP64__) || defined(_WIN64) || defined(_LIBCXXABI_ARM_EHABI)
  79     void* reserve; // padding.
  80     void* primaryException;
  81 #endif
  82
  83     std::type_info *exceptionType;
  84     void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
  85     std::unexpected_handler unexpectedHandler;
  86     std::terminate_handler terminateHandler;
  87
  88     __cxa_exception *nextException;
  89
  90     int handlerCount;
  91
  92 #if defined(_LIBCXXABI_ARM_EHABI)
  93     __cxa_exception* nextPropagatingException;
  94     int propagationCount;
  95 #else
  96     int handlerSwitchValue;
  97     const unsigned char *actionRecord;
  98     const unsigned char *languageSpecificData;
  99     void * catchTemp;
 100     void *adjustedPtr;
 101 #endif
 102
 103 #if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
 104     void* primaryException;
 105 #endif
 106     _Unwind_Exception unwindHeader;
 107 };
 108
 109 // Verify the negative offsets of different fields.
 110 static_assert(sizeof(_Unwind_Exception) +
 111                       offsetof(__cxa_exception, unwindHeader) ==
 112                   sizeof(__cxa_exception),
 113               "unwindHeader has wrong negative offsets");
 114 static_assert(sizeof(_Unwind_Exception) +
 115                       offsetof(__cxa_dependent_exception, unwindHeader) ==
 116                   sizeof(__cxa_dependent_exception),
 117               "unwindHeader has wrong negative offsets");
 118
 119 #if defined(_LIBCXXABI_ARM_EHABI)
 120 static_assert(offsetof(__cxa_exception, propagationCount) +
 121                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 122                   sizeof(__cxa_exception),
 123               "propagationCount has wrong negative offset");
 124 static_assert(offsetof(__cxa_dependent_exception, propagationCount) +
 125                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 126                   sizeof(__cxa_dependent_exception),
 127               "propagationCount has wrong negative offset");
 128 #elif defined(__LP64__) || defined(_WIN64)
 129 static_assert(offsetof(__cxa_exception, adjustedPtr) +
 130                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 131                   sizeof(__cxa_exception),
 132               "adjustedPtr has wrong negative offset");
 133 static_assert(offsetof(__cxa_dependent_exception, adjustedPtr) +
 134                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 135                   sizeof(__cxa_dependent_exception),
 136               "adjustedPtr has wrong negative offset");
 137 #else
 138 static_assert(offsetof(__cxa_exception, referenceCount) +
 139                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 140                   sizeof(__cxa_exception),
 141               "referenceCount has wrong negative offset");
 142 static_assert(offsetof(__cxa_dependent_exception, primaryException) +
 143                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 144                   sizeof(__cxa_dependent_exception),
 145               "primaryException has wrong negative offset");
 146 #endif
 147
 148 struct _LIBCXXABI_HIDDEN __cxa_eh_globals {
 149     __cxa_exception *   caughtExceptions;
 150     unsigned int        uncaughtExceptions;
 151 #if defined(_LIBCXXABI_ARM_EHABI)
 152     __cxa_exception* propagatingExceptions;
 153 #endif
 154 };
 155
 156 extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals      ();
 157 extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals_fast ();
 158
 159 extern "C" _LIBCXXABI_FUNC_VIS void * __cxa_allocate_dependent_exception ();
 160 extern "C" _LIBCXXABI_FUNC_VIS void __cxa_free_dependent_exception (void * dependent_exception);
 161
 162 }  // namespace __cxxabiv1
 163
 164 #endif // _CXA_EXCEPTION_H