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/Signals.h" 29 #include "llvm/Support/circular_raw_ostream.h" 30 #include "llvm/Support/ManagedStatic.h" 31 32 using namespace llvm; 33 34 // All Debug.h functionality is a no-op in NDEBUG mode. 35 #ifndef NDEBUG 36 bool llvm::DebugFlag; // DebugFlag - Exported boolean set by the -debug option 37 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)); 43 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]"), 51 cl::Hidden, 52 cl::init(0)); 53 54 static ManagedStatic<std::string> CurrentDebugType; 55 56 namespace { 57 58 struct DebugOnlyOpt { 59 void operator=(const std::string &Val) const { 60 DebugFlag |= !Val.empty(); 61 *CurrentDebugType = Val; 62 } 63 }; 64 65 } 66 67 static DebugOnlyOpt DebugOnlyOptLoc; 68 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); 73 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(); 83 } 84 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. 88 // 89 bool llvm::isCurrentDebugType(const char *DebugType) { 90 return CurrentDebugType->empty() || DebugType == *CurrentDebugType; 91 } 92 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. 96 /// 97 void llvm::setCurrentDebugType(const char *Type) { 98 *CurrentDebugType = Type; 99 } 100 101 /// 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; 106 107 dbgstream() : 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(). 116 } 117 } thestrm; 118 119 return thestrm.strm; 120 } 121 122 #else 123 // Avoid "has no symbols" warning. 124 namespace llvm { 125 /// dbgs - Return errs(). 126 raw_ostream &dbgs() { 127 return errs(); 128 } 129 } 130 131 #endif 132 133 /// EnableDebugBuffering - Turn on signal handler installation. 134 /// 135 bool llvm::EnableDebugBuffering = false; 136