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
19namespace llvm {
20class StringRef;
21class Twine;
22
23/// An error handler callback.
24typedef void (*fatal_error_handler_t)(void *user_data, const char *reason,
25 bool gen_crash_diag);
26
27/// install_fatal_error_handler - Installs a new error handler to be used
28/// whenever a serious (non-recoverable) error is encountered by LLVM.
29///
30/// If no error handler is installed the default is to print the error message
31/// to stderr, and call exit(1). If an error handler is installed then it is
32/// the handler's responsibility to log the message, it will no longer be
33/// printed to stderr. If the error handler returns, then exit(1) will be
34/// called.
35///
36/// It is dangerous to naively use an error handler which throws an exception.
37/// Even though some applications desire to gracefully recover from arbitrary
38/// faults, blindly throwing exceptions through unfamiliar code isn't a way to
39/// achieve this.
40///
41/// \param user_data - An argument which will be passed to the install error
42/// handler.
43LLVM_ABI void install_fatal_error_handler(fatal_error_handler_t handler,
44 void *user_data = nullptr);
45
46/// Restores default error handling behaviour.
47LLVM_ABI void remove_fatal_error_handler();
48
49/// ScopedFatalErrorHandler - This is a simple helper class which just
50/// calls install_fatal_error_handler in its constructor and
51/// remove_fatal_error_handler in its destructor.
52struct ScopedFatalErrorHandler {
53 explicit ScopedFatalErrorHandler(fatal_error_handler_t handler,
54 void *user_data = nullptr) {
55 install_fatal_error_handler(handler, user_data);
56 }
57
58 ~ScopedFatalErrorHandler() { remove_fatal_error_handler(); }
59};
60
61/// @deprecated Use reportFatalInternalError() or reportFatalUsageError()
62/// instead.
63[[noreturn]] LLVM_ABI void report_fatal_error(const char *reason,
64 bool gen_crash_diag = true);
65[[noreturn]] LLVM_ABI void report_fatal_error(StringRef reason,
66 bool gen_crash_diag = true);
67[[noreturn]] LLVM_ABI void report_fatal_error(const Twine &reason,
68 bool gen_crash_diag = true);
69
70/// Report a fatal error that likely indicates a bug in LLVM. It serves a
71/// similar purpose as an assertion, but is always enabled, regardless of the
72/// value of NDEBUG.
73///
74/// This will call installed error handlers (or print the message by default)
75/// and then abort. This will produce a crash trace and *will* ask users to
76/// report an LLVM bug.
77[[noreturn]] LLVM_ABI void reportFatalInternalError(const char *reason);
78[[noreturn]] LLVM_ABI void reportFatalInternalError(StringRef reason);
79[[noreturn]] LLVM_ABI void reportFatalInternalError(const Twine &reason);
80
81/// Report a fatal error that does not indicate a bug in LLVM.
82///
83/// This can be used in contexts where a proper error reporting mechanism
84/// (such as Error/Expected or DiagnosticInfo) is currently not supported, and
85/// would be too involved to introduce at the moment.
86///
87/// Examples where this function should be used instead of
88/// reportFatalInternalError() include invalid inputs or options, but also
89/// environment error conditions outside LLVM's control. It should also be used
90/// for known unsupported/unimplemented functionality.
91///
92/// This will call installed error handlers (or print the message by default)
93/// and then exit with code 1. It will not produce a crash trace and will
94/// *not* ask users to report an LLVM bug.
95[[noreturn]] LLVM_ABI void reportFatalUsageError(const char *reason);
96[[noreturn]] LLVM_ABI void reportFatalUsageError(StringRef reason);
97[[noreturn]] LLVM_ABI void reportFatalUsageError(const Twine &reason);
98
99/// Installs a new bad alloc error handler that should be used whenever a
100/// bad alloc error, e.g. failing malloc/calloc, is encountered by LLVM.
101///
102/// The user can install a bad alloc handler, in order to define the behavior
103/// in case of failing allocations, e.g. throwing an exception. Note that this
104/// handler must not trigger any additional allocations itself.
105///
106/// If no error handler is installed the default is to print the error message
107/// to stderr, and call exit(1). If an error handler is installed then it is
108/// the handler's responsibility to log the message, it will no longer be
109/// printed to stderr. If the error handler returns, then exit(1) will be
110/// called.
111///
112///
113/// \param user_data - An argument which will be passed to the installed error
114/// handler.
115LLVM_ABI void install_bad_alloc_error_handler(fatal_error_handler_t handler,
116 void *user_data = nullptr);
117
118/// Restores default bad alloc error handling behavior.
119LLVM_ABI void remove_bad_alloc_error_handler();
120
121LLVM_ABI void install_out_of_memory_new_handler();
122
123/// Reports a bad alloc error, calling any user defined bad alloc
124/// error handler. In contrast to the generic 'report_fatal_error'
125/// functions, this function might not terminate, e.g. the user
126/// defined error handler throws an exception, but it won't return.
127///
128/// Note: When throwing an exception in the bad alloc handler, make sure that
129/// the following unwind succeeds, e.g. do not trigger additional allocations
130/// in the unwind chain.
131///
132/// If no error handler is installed (default), throws a bad_alloc exception
133/// if LLVM is compiled with exception support. Otherwise prints the error
134/// to standard error and calls abort().
135[[noreturn]] LLVM_ABI void report_bad_alloc_error(const char *Reason,
136 bool GenCrashDiag = true);
137
138/// This function calls abort(), and prints the optional message to stderr.
139/// Use the llvm_unreachable macro (that adds location info), instead of
140/// calling this function directly.
141[[noreturn]] LLVM_ABI void llvm_unreachable_internal(const char *msg = nullptr,
142 const char *file = nullptr,
143 unsigned line = 0);
144} // namespace llvm
145
146/// Marks that the current location is not supposed to be reachable.
147/// In !NDEBUG builds, prints the message and location info to stderr.
148/// In NDEBUG builds, if the platform does not support a builtin unreachable
149/// then we call an internal LLVM runtime function. Otherwise the behavior is
150/// controlled by the CMake flag
151/// -DLLVM_UNREACHABLE_OPTIMIZE
152/// * When "ON" (default) llvm_unreachable() becomes an optimizer hint
153/// that the current location is not supposed to be reachable: the hint
154/// turns such code path into undefined behavior. On compilers that don't
155/// support such hints, prints a reduced message instead and aborts the
156/// program.
157/// * When "OFF", a builtin_trap is emitted instead of an
158// optimizer hint or printing a reduced message.
159///
160/// Use this instead of assert(0). It conveys intent more clearly, suppresses
161/// diagnostics for unreachable code paths, and allows compilers to omit
162/// unnecessary code.
163#ifndef NDEBUG
164#define llvm_unreachable(msg) \
165 ::llvm::llvm_unreachable_internal(msg, __FILE__, __LINE__)
166#elif !defined(LLVM_BUILTIN_UNREACHABLE)
167#define llvm_unreachable(msg) ::llvm::llvm_unreachable_internal()
168#elif LLVM_UNREACHABLE_OPTIMIZE
169#define llvm_unreachable(msg) LLVM_BUILTIN_UNREACHABLE
170#else
171#define llvm_unreachable(msg) \
172 do { \
173 LLVM_BUILTIN_TRAP; \
174 LLVM_BUILTIN_UNREACHABLE; \
175 } while (false)
176#endif
177
178#endif
179

source code of llvm/include/llvm/Support/ErrorHandling.h