1 //===- llvm/Support/ErrorHandling.h - Fatal error handling ------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file defines an API used to indicate fatal error conditions. Non-fatal 11 // errors (most of them) should be handled through LLVMContext. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #ifndef LLVM_SUPPORT_ERRORHANDLING_H 16 #define LLVM_SUPPORT_ERRORHANDLING_H 17 18 #include "llvm/Support/Compiler.h" 19 #include <string> 20 21 namespace llvm { 22 class StringRef; 23 class Twine; 24 25 /// An error handler callback. 26 typedef void (*fatal_error_handler_t)(void *user_data, 27 const std::string& reason, 28 bool gen_crash_diag); 29 30 /// install_fatal_error_handler - Installs a new error handler to be used 31 /// whenever a serious (non-recoverable) error is encountered by LLVM. 32 /// 33 /// If no error handler is installed the default is to print the error message 34 /// to stderr, and call exit(1). If an error handler is installed then it is 35 /// the handler's responsibility to log the message, it will no longer be 36 /// printed to stderr. If the error handler returns, then exit(1) will be 37 /// called. 38 /// 39 /// It is dangerous to naively use an error handler which throws an exception. 40 /// Even though some applications desire to gracefully recover from arbitrary 41 /// faults, blindly throwing exceptions through unfamiliar code isn't a way to 42 /// achieve this. 43 /// 44 /// \param user_data - An argument which will be passed to the install error 45 /// handler. 46 void install_fatal_error_handler(fatal_error_handler_t handler, 47 void *user_data = nullptr); 48 49 /// Restores default error handling behaviour. 50 void remove_fatal_error_handler(); 51 52 /// ScopedFatalErrorHandler - This is a simple helper class which just 53 /// calls install_fatal_error_handler in its constructor and 54 /// remove_fatal_error_handler in its destructor. 55 struct ScopedFatalErrorHandler { 56 explicit ScopedFatalErrorHandler(fatal_error_handler_t handler, 57 void *user_data = nullptr) { 58 install_fatal_error_handler(handler, user_data); 59 } 60 61 ~ScopedFatalErrorHandler() { remove_fatal_error_handler(); } 62 }; 63 64 /// Reports a serious error, calling any installed error handler. These 65 /// functions are intended to be used for error conditions which are outside 66 /// the control of the compiler (I/O errors, invalid user input, etc.) 67 /// 68 /// If no error handler is installed the default is to print the message to 69 /// standard error, followed by a newline. 70 /// After the error handler is called this function will call exit(1), it 71 /// does not return. 72 LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const char *reason, 73 bool gen_crash_diag = true); 74 LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const std::string &reason, 75 bool gen_crash_diag = true); 76 LLVM_ATTRIBUTE_NORETURN void report_fatal_error(StringRef reason, 77 bool gen_crash_diag = true); 78 LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const Twine &reason, 79 bool gen_crash_diag = true); 80 81 /// Installs a new bad alloc error handler that should be used whenever a 82 /// bad alloc error, e.g. failing malloc/calloc, is encountered by LLVM. 83 /// 84 /// The user can install a bad alloc handler, in order to define the behavior 85 /// in case of failing allocations, e.g. throwing an exception. Note that this 86 /// handler must not trigger any additional allocations itself. 87 /// 88 /// If no error handler is installed the default is to print the error message 89 /// to stderr, and call exit(1). If an error handler is installed then it is 90 /// the handler's responsibility to log the message, it will no longer be 91 /// printed to stderr. If the error handler returns, then exit(1) will be 92 /// called. 93 /// 94 /// 95 /// \param user_data - An argument which will be passed to the installed error 96 /// handler. 97 void install_bad_alloc_error_handler(fatal_error_handler_t handler, 98 void *user_data = nullptr); 99 100 /// Restores default bad alloc error handling behavior. 101 void remove_bad_alloc_error_handler(); 102 103 /// Reports a bad alloc error, calling any user defined bad alloc 104 /// error handler. In contrast to the generic 'report_fatal_error' 105 /// functions, this function is expected to return, e.g. the user 106 /// defined error handler throws an exception. 107 /// 108 /// Note: When throwing an exception in the bad alloc handler, make sure that 109 /// the following unwind succeeds, e.g. do not trigger additional allocations 110 /// in the unwind chain. 111 /// 112 /// If no error handler is installed (default), then a bad_alloc exception 113 /// is thrown if LLVM is compiled with exception support, otherwise an assertion 114 /// is called. 115 void report_bad_alloc_error(const char *Reason, bool GenCrashDiag = true); 116 117 /// This function calls abort(), and prints the optional message to stderr. 118 /// Use the llvm_unreachable macro (that adds location info), instead of 119 /// calling this function directly. 120 LLVM_ATTRIBUTE_NORETURN void 121 llvm_unreachable_internal(const char *msg = nullptr, const char *file = nullptr, 122 unsigned line = 0); 123 } 124 125 /// Marks that the current location is not supposed to be reachable. 126 /// In !NDEBUG builds, prints the message and location info to stderr. 127 /// In NDEBUG builds, becomes an optimizer hint that the current location 128 /// is not supposed to be reachable. On compilers that don't support 129 /// such hints, prints a reduced message instead. 130 /// 131 /// Use this instead of assert(0). It conveys intent more clearly and 132 /// allows compilers to omit some unnecessary code. 133 #ifndef NDEBUG 134 #define llvm_unreachable(msg) \ 135 ::llvm::llvm_unreachable_internal(msg, __FILE__, __LINE__) 136 #elif defined(LLVM_BUILTIN_UNREACHABLE) 137 #define llvm_unreachable(msg) LLVM_BUILTIN_UNREACHABLE 138 #else 139 #define llvm_unreachable(msg) ::llvm::llvm_unreachable_internal() 140 #endif 141 142 #endif 143
