include/llvm/Support/ErrorHandling.h

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