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 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. 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 in release mode, the -debug-* options and all code in DEBUG() 22 // statements disappears, so it does not effect the runtime of the code. 23 // 24 //===----------------------------------------------------------------------===// 25 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" 30 31 using namespace llvm; 32 33 // All Debug.h functionality is a no-op in NDEBUG mode. 34 #ifndef NDEBUG 35 bool llvm::DebugFlag; // DebugFlag - Exported boolean set by the -debug option 36 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)); 42 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]"), 50 cl::Hidden, 51 cl::init(0)); 52 53 static std::string CurrentDebugType; 54 static struct DebugOnlyOpt { 55 void operator=(const std::string &Val) const { 56 DebugFlag |= !Val.empty(); 57 CurrentDebugType = Val; 58 } 59 } DebugOnlyOptLoc; 60 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); 65 66 // Signal handlers - dump debug output on termination. 67 static void debug_user_sig_handler(void *Cookie) 68 { 69 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we 70 // know that debug mode is enabled and dbgs() really is a 71 // circular_raw_ostream. If NDEBUG is defined, then dbgs() == 72 // errs() but this will never be invoked. 73 llvm::circular_raw_ostream *dbgout = 74 static_cast<llvm::circular_raw_ostream *>(&llvm::dbgs()); 75 dbgout->flushBufferWithBanner(); 76 } 77 78 // isCurrentDebugType - Return true if the specified string is the debug type 79 // specified on the command line, or if none was specified on the command line 80 // with the -debug-only=X option. 81 // 82 bool llvm::isCurrentDebugType(const char *DebugType) { 83 return CurrentDebugType.empty() || DebugType == CurrentDebugType; 84 } 85 86 /// SetCurrentDebugType - Set the current debug type, as if the -debug-only=X 87 /// option were specified. Note that DebugFlag also needs to be set to true for 88 /// debug output to be produced. 89 /// 90 void llvm::SetCurrentDebugType(const char *Type) { 91 CurrentDebugType = Type; 92 } 93 94 /// dbgs - Return a circular-buffered debug stream. 95 raw_ostream &llvm::dbgs() { 96 // Do one-time initialization in a thread-safe way. 97 static struct dbgstream { 98 circular_raw_ostream strm; 99 100 dbgstream() : 101 strm(errs(), "*** Debug Log Output ***\n", 102 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) { 103 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0) 104 // TODO: Add a handler for SIGUSER1-type signals so the user can 105 // force a debug dump. 106 sys::AddSignalHandler(&debug_user_sig_handler, 0); 107 // Otherwise we've already set the debug stream buffer size to 108 // zero, disabling buffering. 109 } 110 } thestrm; 111 112 return thestrm.strm; 113 } 114 115 #else 116 // Avoid "has no symbols" warning. 117 namespace llvm { 118 /// dbgs - Return dbgs(). 119 raw_ostream &dbgs() { 120 return dbgs(); 121 } 122 } 123 124 #endif 125 126 /// EnableDebugBuffering - Turn on signal handler installation. 127 /// 128 bool llvm::EnableDebugBuffering = false; 129