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 #ifdef __USING_WASM_EXCEPTIONS__
  47     // In Wasm, a destructor returns its argument
  48     void *(_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
  49 #else
  50     void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
  51 #endif
  52     std::unexpected_handler unexpectedHandler;
  53     std::terminate_handler  terminateHandler;
  54
  55     __cxa_exception *nextException;
  56
  57     int handlerCount;
  58
  59 #if defined(_LIBCXXABI_ARM_EHABI)
  60     __cxa_exception* nextPropagatingException;
  61     int propagationCount;
  62 #else
  63     int handlerSwitchValue;
  64     const unsigned char *actionRecord;
  65     const unsigned char *languageSpecificData;
  66     void *catchTemp;
  67     void *adjustedPtr;
  68 #endif
  69
  70 #if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
  71     // This is a new field to support C++11 exception_ptr.
  72     // For binary compatibility it is placed where the compiler
  73     // previously added padding to 64-bit align unwindHeader.
  74     size_t referenceCount;
  75 #endif
  76     _Unwind_Exception unwindHeader;
  77 };
  78
  79 // http://sourcery.mentor.com/archives/cxx-abi-dev/msg01924.html
  80 // The layout of this structure MUST match the layout of __cxa_exception, with
  81 // primaryException instead of referenceCount.
  82 struct _LIBCXXABI_HIDDEN __cxa_dependent_exception {
  83 #if defined(__LP64__) || defined(_WIN64) || defined(_LIBCXXABI_ARM_EHABI)
  84     void* reserve; // padding.
  85     void* primaryException;
  86 #endif
  87
  88     std::type_info *exceptionType;
  89     void (_LIBCXXABI_DTOR_FUNC *exceptionDestructor)(void *);
  90     std::unexpected_handler unexpectedHandler;
  91     std::terminate_handler terminateHandler;
  92
  93     __cxa_exception *nextException;
  94
  95     int handlerCount;
  96
  97 #if defined(_LIBCXXABI_ARM_EHABI)
  98     __cxa_exception* nextPropagatingException;
  99     int propagationCount;
 100 #else
 101     int handlerSwitchValue;
 102     const unsigned char *actionRecord;
 103     const unsigned char *languageSpecificData;
 104     void * catchTemp;
 105     void *adjustedPtr;
 106 #endif
 107
 108 #if !defined(__LP64__) && !defined(_WIN64) && !defined(_LIBCXXABI_ARM_EHABI)
 109     void* primaryException;
 110 #endif
 111     _Unwind_Exception unwindHeader;
 112 };
 113
 114 // Verify the negative offsets of different fields.
 115 static_assert(sizeof(_Unwind_Exception) +
 116                       offsetof(__cxa_exception, unwindHeader) ==
 117                   sizeof(__cxa_exception),
 118               "unwindHeader has wrong negative offsets");
 119 static_assert(sizeof(_Unwind_Exception) +
 120                       offsetof(__cxa_dependent_exception, unwindHeader) ==
 121                   sizeof(__cxa_dependent_exception),
 122               "unwindHeader has wrong negative offsets");
 123
 124 #if defined(_LIBCXXABI_ARM_EHABI)
 125 static_assert(offsetof(__cxa_exception, propagationCount) +
 126                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 127                   sizeof(__cxa_exception),
 128               "propagationCount has wrong negative offset");
 129 static_assert(offsetof(__cxa_dependent_exception, propagationCount) +
 130                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 131                   sizeof(__cxa_dependent_exception),
 132               "propagationCount has wrong negative offset");
 133 #elif defined(__LP64__) || defined(_WIN64)
 134 static_assert(offsetof(__cxa_exception, adjustedPtr) +
 135                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 136                   sizeof(__cxa_exception),
 137               "adjustedPtr has wrong negative offset");
 138 static_assert(offsetof(__cxa_dependent_exception, adjustedPtr) +
 139                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 140                   sizeof(__cxa_dependent_exception),
 141               "adjustedPtr has wrong negative offset");
 142 #else
 143 static_assert(offsetof(__cxa_exception, referenceCount) +
 144                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 145                   sizeof(__cxa_exception),
 146               "referenceCount has wrong negative offset");
 147 static_assert(offsetof(__cxa_dependent_exception, primaryException) +
 148                       sizeof(_Unwind_Exception) + sizeof(void*) ==
 149                   sizeof(__cxa_dependent_exception),
 150               "primaryException has wrong negative offset");
 151 #endif
 152
 153 struct _LIBCXXABI_HIDDEN __cxa_eh_globals {
 154     __cxa_exception *   caughtExceptions;
 155     unsigned int        uncaughtExceptions;
 156 #if defined(_LIBCXXABI_ARM_EHABI)
 157     __cxa_exception* propagatingExceptions;
 158 #endif
 159 };
 160
 161 extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals      ();
 162 extern "C" _LIBCXXABI_FUNC_VIS __cxa_eh_globals * __cxa_get_globals_fast ();
 163
 164 extern "C" _LIBCXXABI_FUNC_VIS void * __cxa_allocate_dependent_exception ();
 165 extern "C" _LIBCXXABI_FUNC_VIS void __cxa_free_dependent_exception (void * dependent_exception);
 166
 167 }  // namespace __cxxabiv1
 168
 169 #endif // _CXA_EXCEPTION_H