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 handle 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 in release mode, the -debug-* options and all code in DEBUG()
22 // statements disappears, so it does not effect the runtime of the code.
24 //===----------------------------------------------------------------------===//
26 #include "llvm/Support/CommandLine.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/circular_raw_ostream.h"
29 #include "llvm/System/Signals.h"
33 // All Debug.h functionality is a no-op in NDEBUG mode.
35 bool llvm::DebugFlag; // DebugFlag - Exported boolean set by the -debug option
37 // -debug - Command line option to enable the DEBUG statements in the passes.
38 // This flag may only be enabled in debug builds.
39 static cl::opt<bool, true>
40 Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
41 cl::location(DebugFlag));
43 // -debug-buffer-size - Buffer the last N characters of debug output
44 //until program termination.
45 static cl::opt<unsigned>
46 DebugBufferSize("debug-buffer-size",
47 cl::desc("Buffer the last N characters of debug output"
48 "until program termination. "
49 "[default 0 -- immediate print-out]"),
53 static std::string CurrentDebugType;
54 static struct DebugOnlyOpt {
55 void operator=(const std::string &Val) const {
56 DebugFlag |= !Val.empty();
57 CurrentDebugType = Val;
61 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
62 DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"),
63 cl::Hidden, cl::value_desc("debug string"),
64 cl::location(DebugOnlyOptLoc), cl::ValueRequired);
66 // Signal handlers - dump debug output on termination.
67 static void debug_user_sig_handler(void *Cookie) {
68 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we
69 // know that debug mode is enabled and dbgs() really is a
70 // circular_raw_ostream. If NDEBUG is defined, then dbgs() ==
71 // errs() but this will never be invoked.
72 llvm::circular_raw_ostream *dbgout =
73 static_cast<llvm::circular_raw_ostream *>(&llvm::dbgs());
74 dbgout->flushBufferWithBanner();
77 // isCurrentDebugType - Return true if the specified string is the debug type
78 // specified on the command line, or if none was specified on the command line
79 // with the -debug-only=X option.
81 bool llvm::isCurrentDebugType(const char *DebugType) {
82 return CurrentDebugType.empty() || DebugType == CurrentDebugType;
85 /// SetCurrentDebugType - Set the current debug type, as if the -debug-only=X
86 /// option were specified. Note that DebugFlag also needs to be set to true for
87 /// debug output to be produced.
89 void llvm::SetCurrentDebugType(const char *Type) {
90 CurrentDebugType = Type;
93 /// dbgs - Return a circular-buffered debug stream.
94 raw_ostream &llvm::dbgs() {
95 // Do one-time initialization in a thread-safe way.
96 static struct dbgstream {
97 circular_raw_ostream strm;
100 strm(errs(), "*** Debug Log Output ***\n",
101 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) {
102 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0)
103 // TODO: Add a handler for SIGUSER1-type signals so the user can
104 // force a debug dump.
105 sys::AddSignalHandler(&debug_user_sig_handler, 0);
106 // Otherwise we've already set the debug stream buffer size to
107 // zero, disabling buffering so it will output directly to errs().
115 // Avoid "has no symbols" warning.
117 /// dbgs - Return errs().
118 raw_ostream &dbgs() {
125 /// EnableDebugBuffering - Turn on signal handler installation.
127 bool llvm::EnableDebugBuffering = false;