1 //===-- Debug.cpp - An easy way to add debug output to your code ----------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
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
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.
24 //===----------------------------------------------------------------------===//
26 #include "llvm/Support/Debug.h"
27 #include "llvm/Support/CommandLine.h"
28 #include "llvm/Support/Signals.h"
29 #include "llvm/Support/circular_raw_ostream.h"
30 #include "llvm/Support/ManagedStatic.h"
34 // All Debug.h functionality is a no-op in NDEBUG mode.
36 bool llvm::DebugFlag; // DebugFlag - Exported boolean set by the -debug option
38 // -debug - Command line option to enable the DEBUG statements in the passes.
39 // This flag may only be enabled in debug builds.
40 static cl::opt<bool, true>
41 Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
42 cl::location(DebugFlag));
44 // -debug-buffer-size - Buffer the last N characters of debug output
45 //until program termination.
46 static cl::opt<unsigned>
47 DebugBufferSize("debug-buffer-size",
48 cl::desc("Buffer the last N characters of debug output "
49 "until program termination. "
50 "[default 0 -- immediate print-out]"),
54 static ManagedStatic<std::string> CurrentDebugType;
59 void operator=(const std::string &Val) const {
60 DebugFlag |= !Val.empty();
61 *CurrentDebugType = Val;
67 static DebugOnlyOpt DebugOnlyOptLoc;
69 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
70 DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"),
71 cl::Hidden, cl::value_desc("debug string"),
72 cl::location(DebugOnlyOptLoc), cl::ValueRequired);
74 // Signal handlers - dump debug output on termination.
75 static void debug_user_sig_handler(void *Cookie) {
76 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we
77 // know that debug mode is enabled and dbgs() really is a
78 // circular_raw_ostream. If NDEBUG is defined, then dbgs() ==
79 // errs() but this will never be invoked.
80 llvm::circular_raw_ostream *dbgout =
81 static_cast<llvm::circular_raw_ostream *>(&llvm::dbgs());
82 dbgout->flushBufferWithBanner();
85 // isCurrentDebugType - Return true if the specified string is the debug type
86 // specified on the command line, or if none was specified on the command line
87 // with the -debug-only=X option.
89 bool llvm::isCurrentDebugType(const char *DebugType) {
90 return CurrentDebugType->empty() || DebugType == *CurrentDebugType;
93 /// setCurrentDebugType - Set the current debug type, as if the -debug-only=X
94 /// option were specified. Note that DebugFlag also needs to be set to true for
95 /// debug output to be produced.
97 void llvm::setCurrentDebugType(const char *Type) {
98 *CurrentDebugType = Type;
101 /// dbgs - Return a circular-buffered debug stream.
102 raw_ostream &llvm::dbgs() {
103 // Do one-time initialization in a thread-safe way.
104 static struct dbgstream {
105 circular_raw_ostream strm;
108 strm(errs(), "*** Debug Log Output ***\n",
109 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) {
110 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0)
111 // TODO: Add a handler for SIGUSER1-type signals so the user can
112 // force a debug dump.
113 sys::AddSignalHandler(&debug_user_sig_handler, nullptr);
114 // Otherwise we've already set the debug stream buffer size to
115 // zero, disabling buffering so it will output directly to errs().
123 // Avoid "has no symbols" warning.
125 /// dbgs - Return errs().
126 raw_ostream &dbgs() {
133 /// EnableDebugBuffering - Turn on signal handler installation.
135 bool llvm::EnableDebugBuffering = false;