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 LLVM_DEBUG() macro, and it will 15 // be 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 // LLVM_DEBUG() statements disappears, so it does not affect the runtime of the 23 // code. 24 // 25 //===----------------------------------------------------------------------===// 26 27 #include "llvm/Support/Debug.h" 28 #include "llvm/Support/CommandLine.h" 29 #include "llvm/Support/ManagedStatic.h" 30 #include "llvm/Support/Signals.h" 31 #include "llvm/Support/circular_raw_ostream.h" 32 #include "llvm/Support/raw_ostream.h" 33 34 #undef isCurrentDebugType 35 #undef setCurrentDebugType 36 #undef setCurrentDebugTypes 37 38 using namespace llvm; 39 40 // Even though LLVM might be built with NDEBUG, define symbols that the code 41 // built without NDEBUG can depend on via the llvm/Support/Debug.h header. 42 namespace llvm { 43 /// Exported boolean set by the -debug option. 44 bool DebugFlag = false; 45 46 static ManagedStatic<std::vector<std::string>> CurrentDebugType; 47 48 /// Return true if the specified string is the debug type 49 /// specified on the command line, or if none was specified on the command line 50 /// with the -debug-only=X option. 51 bool isCurrentDebugType(const char *DebugType) { 52 if (CurrentDebugType->empty()) 53 return true; 54 // See if DebugType is in list. Note: do not use find() as that forces us to 55 // unnecessarily create an std::string instance. 56 for (auto &d : *CurrentDebugType) { 57 if (d == DebugType) 58 return true; 59 } 60 return false; 61 } 62 63 /// Set the current debug type, as if the -debug-only=X 64 /// option were specified. Note that DebugFlag also needs to be set to true for 65 /// debug output to be produced. 66 /// 67 void setCurrentDebugTypes(const char **Types, unsigned Count); 68 69 void setCurrentDebugType(const char *Type) { 70 setCurrentDebugTypes(&Type, 1); 71 } 72 73 void setCurrentDebugTypes(const char **Types, unsigned Count) { 74 CurrentDebugType->clear(); 75 for (size_t T = 0; T < Count; ++T) 76 CurrentDebugType->push_back(Types[T]); 77 } 78 } // namespace llvm 79 80 // All Debug.h functionality is a no-op in NDEBUG mode. 81 #ifndef NDEBUG 82 83 // -debug - Command line option to enable the DEBUG statements in the passes. 84 // This flag may only be enabled in debug builds. 85 static cl::opt<bool, true> 86 Debug("debug", cl::desc("Enable debug output"), cl::Hidden, 87 cl::location(DebugFlag)); 88 89 // -debug-buffer-size - Buffer the last N characters of debug output 90 //until program termination. 91 static cl::opt<unsigned> 92 DebugBufferSize("debug-buffer-size", 93 cl::desc("Buffer the last N characters of debug output " 94 "until program termination. " 95 "[default 0 -- immediate print-out]"), 96 cl::Hidden, 97 cl::init(0)); 98 99 namespace { 100 101 struct DebugOnlyOpt { 102 void operator=(const std::string &Val) const { 103 if (Val.empty()) 104 return; 105 DebugFlag = true; 106 SmallVector<StringRef,8> dbgTypes; 107 StringRef(Val).split(dbgTypes, ',', -1, false); 108 for (auto dbgType : dbgTypes) 109 CurrentDebugType->push_back(dbgType); 110 } 111 }; 112 113 } 114 115 static DebugOnlyOpt DebugOnlyOptLoc; 116 117 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> > 118 DebugOnly("debug-only", cl::desc("Enable a specific type of debug output (comma separated list of types)"), 119 cl::Hidden, cl::ZeroOrMore, cl::value_desc("debug string"), 120 cl::location(DebugOnlyOptLoc), cl::ValueRequired); 121 // Signal handlers - dump debug output on termination. 122 static void debug_user_sig_handler(void *Cookie) { 123 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we 124 // know that debug mode is enabled and dbgs() really is a 125 // circular_raw_ostream. If NDEBUG is defined, then dbgs() == 126 // errs() but this will never be invoked. 127 llvm::circular_raw_ostream &dbgout = 128 static_cast<circular_raw_ostream &>(llvm::dbgs()); 129 dbgout.flushBufferWithBanner(); 130 } 131 132 /// dbgs - Return a circular-buffered debug stream. 133 raw_ostream &llvm::dbgs() { 134 // Do one-time initialization in a thread-safe way. 135 static struct dbgstream { 136 circular_raw_ostream strm; 137 138 dbgstream() : 139 strm(errs(), "*** Debug Log Output ***\n", 140 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) { 141 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0) 142 // TODO: Add a handler for SIGUSER1-type signals so the user can 143 // force a debug dump. 144 sys::AddSignalHandler(&debug_user_sig_handler, nullptr); 145 // Otherwise we've already set the debug stream buffer size to 146 // zero, disabling buffering so it will output directly to errs(). 147 } 148 } thestrm; 149 150 return thestrm.strm; 151 } 152 153 #else 154 // Avoid "has no symbols" warning. 155 namespace llvm { 156 /// dbgs - Return errs(). 157 raw_ostream &dbgs() { 158 return errs(); 159 } 160 } 161 162 #endif 163 164 /// EnableDebugBuffering - Turn on signal handler installation. 165 /// 166 bool llvm::EnableDebugBuffering = false; 167