1 //===-- Debug.cpp - An easy way to add debug output to your code ----------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements a handy way of adding debugging information to your 10 // code, without it being enabled all of the time, and without having to add 11 // command line options to enable it. 12 // 13 // In particular, just wrap your code with the LLVM_DEBUG() macro, and it will 14 // be enabled automatically if you specify '-debug' on the command-line. 15 // Alternatively, you can also use the SET_DEBUG_TYPE("foo") macro to specify 16 // that your debug code belongs to class "foo". Then, on the command line, you 17 // can specify '-debug-only=foo' to enable JUST the debug information for the 18 // foo class. 19 // 20 // When compiling without assertions, the -debug-* options and all code in 21 // LLVM_DEBUG() statements disappears, so it does not affect the runtime of the 22 // code. 23 // 24 //===----------------------------------------------------------------------===// 25 26 #include "llvm/Support/Debug.h" 27 #include "llvm/Support/CommandLine.h" 28 #include "llvm/Support/ManagedStatic.h" 29 #include "llvm/Support/Signals.h" 30 #include "llvm/Support/circular_raw_ostream.h" 31 #include "llvm/Support/raw_ostream.h" 32 33 #undef isCurrentDebugType 34 #undef setCurrentDebugType 35 #undef setCurrentDebugTypes 36 37 using namespace llvm; 38 39 // Even though LLVM might be built with NDEBUG, define symbols that the code 40 // built without NDEBUG can depend on via the llvm/Support/Debug.h header. 41 namespace llvm { 42 /// Exported boolean set by the -debug option. 43 bool DebugFlag = false; 44 45 static ManagedStatic<std::vector<std::string>> CurrentDebugType; 46 47 /// Return true if the specified string is the debug type 48 /// specified on the command line, or if none was specified on the command line 49 /// with the -debug-only=X option. 50 bool isCurrentDebugType(const char *DebugType) { 51 if (CurrentDebugType->empty()) 52 return true; 53 // See if DebugType is in list. Note: do not use find() as that forces us to 54 // unnecessarily create an std::string instance. 55 for (auto &d : *CurrentDebugType) { 56 if (d == DebugType) 57 return true; 58 } 59 return false; 60 } 61 62 /// Set the current debug type, as if the -debug-only=X 63 /// option were specified. Note that DebugFlag also needs to be set to true for 64 /// debug output to be produced. 65 /// 66 void setCurrentDebugTypes(const char **Types, unsigned Count); 67 68 void setCurrentDebugType(const char *Type) { 69 setCurrentDebugTypes(&Type, 1); 70 } 71 72 void setCurrentDebugTypes(const char **Types, unsigned Count) { 73 CurrentDebugType->clear(); 74 for (size_t T = 0; T < Count; ++T) 75 CurrentDebugType->push_back(Types[T]); 76 } 77 } // namespace llvm 78 79 // All Debug.h functionality is a no-op in NDEBUG mode. 80 #ifndef NDEBUG 81 82 // -debug - Command line option to enable the DEBUG statements in the passes. 83 // This flag may only be enabled in debug builds. 84 static cl::opt<bool, true> 85 Debug("debug", cl::desc("Enable debug output"), cl::Hidden, 86 cl::location(DebugFlag)); 87 88 // -debug-buffer-size - Buffer the last N characters of debug output 89 //until program termination. 90 static cl::opt<unsigned> 91 DebugBufferSize("debug-buffer-size", 92 cl::desc("Buffer the last N characters of debug output " 93 "until program termination. " 94 "[default 0 -- immediate print-out]"), 95 cl::Hidden, 96 cl::init(0)); 97 98 namespace { 99 100 struct DebugOnlyOpt { 101 void operator=(const std::string &Val) const { 102 if (Val.empty()) 103 return; 104 DebugFlag = true; 105 SmallVector<StringRef,8> dbgTypes; 106 StringRef(Val).split(dbgTypes, ',', -1, false); 107 for (auto dbgType : dbgTypes) 108 CurrentDebugType->push_back(dbgType); 109 } 110 }; 111 112 } 113 114 static DebugOnlyOpt DebugOnlyOptLoc; 115 116 static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> > 117 DebugOnly("debug-only", cl::desc("Enable a specific type of debug output (comma separated list of types)"), 118 cl::Hidden, cl::ZeroOrMore, cl::value_desc("debug string"), 119 cl::location(DebugOnlyOptLoc), cl::ValueRequired); 120 // Signal handlers - dump debug output on termination. 121 static void debug_user_sig_handler(void *Cookie) { 122 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we 123 // know that debug mode is enabled and dbgs() really is a 124 // circular_raw_ostream. If NDEBUG is defined, then dbgs() == 125 // errs() but this will never be invoked. 126 llvm::circular_raw_ostream &dbgout = 127 static_cast<circular_raw_ostream &>(llvm::dbgs()); 128 dbgout.flushBufferWithBanner(); 129 } 130 131 /// dbgs - Return a circular-buffered debug stream. 132 raw_ostream &llvm::dbgs() { 133 // Do one-time initialization in a thread-safe way. 134 static struct dbgstream { 135 circular_raw_ostream strm; 136 137 dbgstream() : 138 strm(errs(), "*** Debug Log Output ***\n", 139 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) { 140 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0) 141 // TODO: Add a handler for SIGUSER1-type signals so the user can 142 // force a debug dump. 143 sys::AddSignalHandler(&debug_user_sig_handler, nullptr); 144 // Otherwise we've already set the debug stream buffer size to 145 // zero, disabling buffering so it will output directly to errs(). 146 } 147 } thestrm; 148 149 return thestrm.strm; 150 } 151 152 #else 153 // Avoid "has no symbols" warning. 154 namespace llvm { 155 /// dbgs - Return errs(). 156 raw_ostream &dbgs() { 157 return errs(); 158 } 159 } 160 161 #endif 162 163 /// EnableDebugBuffering - Turn on signal handler installation. 164 /// 165 bool llvm::EnableDebugBuffering = false; 166