xref: /aosp_15_r20/external/cronet/third_party/libc++abi/src/src/cxa_exception.h (revision 6777b5387eb2ff775bb5750e3f5d96f37fb7352b)
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
170