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 21namespace llvm { 22class 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. 72LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const char *reason, 73 bool gen_crash_diag = true); 74LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const std::string &reason, 75 bool gen_crash_diag = true); 76LLVM_ATTRIBUTE_NORETURN void report_fatal_error(StringRef reason, 77 bool gen_crash_diag = true); 78LLVM_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. 97void install_bad_alloc_error_handler(fatal_error_handler_t handler, 98 void *user_data = nullptr); 99 100/// Restores default bad alloc error handling behavior. 101void 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. 115void 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. 120LLVM_ATTRIBUTE_NORETURN void 121llvm_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