ErrorHandling.h revision 8316f2d3810dd37bae0f847bc3efd495432b5893 
1//===- llvm/Support/ErrorHandling.h - Callbacks for errors ------*- 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 error conditions.
11// Callbacks can be registered for these errors through this API.
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 {
22  class Twine;
23
24  /// An error handler callback.
25  typedef void (*llvm_error_handler_t)(void *user_data,
26                                       const std::string& reason);
27
28  /// llvm_install_error_handler - Installs a new error handler to be used
29  /// whenever a serious (non-recoverable) error is encountered by LLVM.
30  ///
31  /// If you are using llvm_start_multithreaded, you should register the handler
32  /// before doing that.
33  ///
34  /// If no error handler is installed the default is to print the error message
35  /// to stderr, and call exit(1).  If an error handler is installed then it is
36  /// the handler's responsibility to log the message, it will no longer be
37  /// printed to stderr.  If the error handler returns, then exit(1) will be
38  /// called.
39  ///
40  /// It is dangerous to naively use an error handler which throws an exception.
41  /// Even though some applications desire to gracefully recover from arbitrary
42  /// faults, blindly throwing exceptions through unfamiliar code isn't a way to
43  /// achieve this.
44  ///
45  /// \param user_data - An argument which will be passed to the install error
46  /// handler.
47  void llvm_install_error_handler(llvm_error_handler_t handler,
48                                  void *user_data = 0);
49
50  /// Restores default error handling behaviour.
51  /// This must not be called between llvm_start_multithreaded() and
52  /// llvm_stop_multithreaded().
53  void llvm_remove_error_handler();
54
55  /// Reports a serious error, calling any installed error handler. These
56  /// functions are intended to be used for error conditions which are outside
57  /// the control of the compiler (I/O errors, invalid user input, etc.)
58  ///
59  /// If no error handler is installed the default is to print the message to
60  /// standard error, followed by a newline.
61  /// After the error handler is called this function will call exit(1), it
62  /// does not return.
63  NORETURN void report_fatal_error(const char *reason);
64  NORETURN void report_fatal_error(const std::string &reason);
65  NORETURN void report_fatal_error(const Twine &reason);
66
67  /// This function calls abort(), and prints the optional message to stderr.
68  /// Use the llvm_unreachable macro (that adds location info), instead of
69  /// calling this function directly.
70  NORETURN void llvm_unreachable_internal(const char *msg=0,
71                                          const char *file=0, unsigned line=0);
72}
73
74/// Prints the message and location info to stderr in !NDEBUG builds.
75/// This is intended to be used for "impossible" situations that imply
76/// a bug in the compiler.
77///
78/// In NDEBUG mode it only prints "UNREACHABLE executed".
79/// Use this instead of assert(0), so that the compiler knows this path
80/// is not reachable even for NDEBUG builds.
81#ifndef NDEBUG
82#define llvm_unreachable(msg) \
83  ::llvm::llvm_unreachable_internal(msg, __FILE__, __LINE__)
84#else
85#define llvm_unreachable(msg) ::llvm::llvm_unreachable_internal()
86#endif
87
88#endif
89