1 //===-- Debug.cpp - An easy way to add debug output to your code ----------===//
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 implements a handy way of adding debugging information to your
11 // code, without it being enabled all of the time, and without having to add
12 // command line options to enable it.
13 //
14 // In particular, just wrap your code with the DEBUG() macro, and it will be
15 // enabled automatically if you specify '-debug' on the command-line.
16 // Alternatively, you can also use the SET_DEBUG_TYPE("foo") macro to specify
17 // that your debug code belongs to class "foo". Then, on the command line, you
18 // can specify '-debug-only=foo' to enable JUST the debug information for the
19 // foo class.
20 //
21 // When compiling without assertions, the -debug-* options and all code in
22 // DEBUG() statements disappears, so it does not affect the runtime of the code.
23 //
24 //===----------------------------------------------------------------------===//
25
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Support/Signals.h"
30 #include "llvm/Support/circular_raw_ostream.h"
31 #include "llvm/Support/raw_ostream.h"
32
33 #undef isCurrentDebugType
34 #undef setCurrentDebugType
35
36 using namespace llvm;
37
38 // Even though LLVM might be built with NDEBUG, define symbols that the code
39 // built without NDEBUG can depend on via the llvm/Support/Debug.h header.
40 namespace llvm {
41 /// Exported boolean set by the -debug option.
42 bool DebugFlag = false;
43
44 static ManagedStatic<std::vector<std::string>> CurrentDebugType;
45
46 /// Return true if the specified string is the debug type
47 /// specified on the command line, or if none was specified on the command line
48 /// with the -debug-only=X option.
isCurrentDebugType(const char * DebugType)49 bool isCurrentDebugType(const char *DebugType) {
50 if (CurrentDebugType->empty())
51 return true;
52 // See if DebugType is in list. Note: do not use find() as that forces us to
53 // unnecessarily create an std::string instance.
54 for (auto &d : *CurrentDebugType) {
55 if (d == DebugType)
56 return true;
57 }
58 return false;
59 }
60
61 /// Set the current debug type, as if the -debug-only=X
62 /// option were specified. Note that DebugFlag also needs to be set to true for
63 /// debug output to be produced.
64 ///
setCurrentDebugType(const char * Type)65 void setCurrentDebugType(const char *Type) {
66 CurrentDebugType->clear();
67 CurrentDebugType->push_back(Type);
68 }
69
70 } // namespace llvm
71
72 // All Debug.h functionality is a no-op in NDEBUG mode.
73 #ifndef NDEBUG
74
75 // -debug - Command line option to enable the DEBUG statements in the passes.
76 // This flag may only be enabled in debug builds.
77 static cl::opt<bool, true>
78 Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
79 cl::location(DebugFlag));
80
81 // -debug-buffer-size - Buffer the last N characters of debug output
82 //until program termination.
83 static cl::opt<unsigned>
84 DebugBufferSize("debug-buffer-size",
85 cl::desc("Buffer the last N characters of debug output "
86 "until program termination. "
87 "[default 0 -- immediate print-out]"),
88 cl::Hidden,
89 cl::init(0));
90
91 namespace {
92
93 struct DebugOnlyOpt {
operator =__anon94bb45300111::DebugOnlyOpt94 void operator=(const std::string &Val) const {
95 if (Val.empty())
96 return;
97 DebugFlag = true;
98 SmallVector<StringRef,8> dbgTypes;
99 StringRef(Val).split(dbgTypes, ',', -1, false);
100 for (auto dbgType : dbgTypes)
101 CurrentDebugType->push_back(dbgType);
102 }
103 };
104
105 }
106
107 static DebugOnlyOpt DebugOnlyOptLoc;
108
109 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
110 DebugOnly("debug-only", cl::desc("Enable a specific type of debug output (comma separated list of types)"),
111 cl::Hidden, cl::ZeroOrMore, cl::value_desc("debug string"),
112 cl::location(DebugOnlyOptLoc), cl::ValueRequired);
113 // Signal handlers - dump debug output on termination.
debug_user_sig_handler(void * Cookie)114 static void debug_user_sig_handler(void *Cookie) {
115 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we
116 // know that debug mode is enabled and dbgs() really is a
117 // circular_raw_ostream. If NDEBUG is defined, then dbgs() ==
118 // errs() but this will never be invoked.
119 llvm::circular_raw_ostream &dbgout =
120 static_cast<circular_raw_ostream &>(llvm::dbgs());
121 dbgout.flushBufferWithBanner();
122 }
123
124 /// dbgs - Return a circular-buffered debug stream.
dbgs()125 raw_ostream &llvm::dbgs() {
126 // Do one-time initialization in a thread-safe way.
127 static struct dbgstream {
128 circular_raw_ostream strm;
129
130 dbgstream() :
131 strm(errs(), "*** Debug Log Output ***\n",
132 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) {
133 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0)
134 // TODO: Add a handler for SIGUSER1-type signals so the user can
135 // force a debug dump.
136 sys::AddSignalHandler(&debug_user_sig_handler, nullptr);
137 // Otherwise we've already set the debug stream buffer size to
138 // zero, disabling buffering so it will output directly to errs().
139 }
140 } thestrm;
141
142 return thestrm.strm;
143 }
144
145 #else
146 // Avoid "has no symbols" warning.
147 namespace llvm {
148 /// dbgs - Return errs().
dbgs()149 raw_ostream &dbgs() {
150 return errs();
151 }
152 }
153
154 #endif
155
156 /// EnableDebugBuffering - Turn on signal handler installation.
157 ///
158 bool llvm::EnableDebugBuffering = false;
159