Debug.cpp revision 201360
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 31using namespace llvm; 32 33// All Debug.h functionality is a no-op in NDEBUG mode. 34#ifndef NDEBUG 35bool 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. 39static cl::opt<bool, true> 40Debug("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. 45static cl::opt<unsigned> 46DebugBufferSize("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 53static std::string CurrentDebugType; 54static struct DebugOnlyOpt { 55 void operator=(const std::string &Val) const { 56 DebugFlag |= !Val.empty(); 57 CurrentDebugType = Val; 58 } 59} DebugOnlyOptLoc; 60 61static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> > 62DebugOnly("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. 67static 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// 82bool 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/// 90void llvm::SetCurrentDebugType(const char *Type) { 91 CurrentDebugType = Type; 92} 93 94/// dbgs - Return a circular-buffered debug stream. 95raw_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 so it will output directly to errs(). 109 } 110 } thestrm; 111 112 return thestrm.strm; 113} 114 115#else 116// Avoid "has no symbols" warning. 117namespace 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/// 128bool llvm::EnableDebugBuffering = false; 129