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
103void install_out_of_memory_new_handler();
104
105/// Reports a bad alloc error, calling any user defined bad alloc
106/// error handler. In contrast to the generic 'report_fatal_error'
107/// functions, this function is expected to return, e.g. the user
108/// defined error handler throws an exception.
109///
110/// Note: When throwing an exception in the bad alloc handler, make sure that
111/// the following unwind succeeds, e.g. do not trigger additional allocations
112/// in the unwind chain.
113///
114/// If no error handler is installed (default), then a bad_alloc exception
115/// is thrown, if LLVM is compiled with exception support, otherwise an
116/// assertion is called.
117void report_bad_alloc_error(const char *Reason, bool GenCrashDiag = true);
118
119/// This function calls abort(), and prints the optional message to stderr.
120/// Use the llvm_unreachable macro (that adds location info), instead of
121/// calling this function directly.
122LLVM_ATTRIBUTE_NORETURN void
123llvm_unreachable_internal(const char *msg = nullptr, const char *file = nullptr,
124 unsigned line = 0);
125}
126
127/// Marks that the current location is not supposed to be reachable.
128/// In !NDEBUG builds, prints the message and location info to stderr.
129/// In NDEBUG builds, becomes an optimizer hint that the current location
130/// is not supposed to be reachable. On compilers that don't support
131/// such hints, prints a reduced message instead.
132///
133/// Use this instead of assert(0). It conveys intent more clearly and
134/// allows compilers to omit some unnecessary code.
135#ifndef NDEBUG
136#define llvm_unreachable(msg) \
137 ::llvm::llvm_unreachable_internal(msg, __FILE__, __LINE__)
138#elif defined(LLVM_BUILTIN_UNREACHABLE)
139#define llvm_unreachable(msg) LLVM_BUILTIN_UNREACHABLE
140#else
141#define llvm_unreachable(msg) ::llvm::llvm_unreachable_internal()
142#endif
143
144#endif
145