Debug.cpp revision 239462
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/CommandLine.h" 27#include "llvm/Support/Debug.h" 28#include "llvm/Support/circular_raw_ostream.h" 29#include "llvm/Support/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; 54 55namespace { 56 57struct DebugOnlyOpt { 58 void operator=(const std::string &Val) const { 59 DebugFlag |= !Val.empty(); 60 CurrentDebugType = Val; 61 } 62}; 63 64} 65 66static DebugOnlyOpt DebugOnlyOptLoc; 67 68static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> > 69DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"), 70 cl::Hidden, cl::value_desc("debug string"), 71 cl::location(DebugOnlyOptLoc), cl::ValueRequired); 72 73// Signal handlers - dump debug output on termination. 74static void debug_user_sig_handler(void *Cookie) { 75 // This is a bit sneaky. Since this is under #ifndef NDEBUG, we 76 // know that debug mode is enabled and dbgs() really is a 77 // circular_raw_ostream. If NDEBUG is defined, then dbgs() == 78 // errs() but this will never be invoked. 79 llvm::circular_raw_ostream *dbgout = 80 static_cast<llvm::circular_raw_ostream *>(&llvm::dbgs()); 81 dbgout->flushBufferWithBanner(); 82} 83 84// isCurrentDebugType - Return true if the specified string is the debug type 85// specified on the command line, or if none was specified on the command line 86// with the -debug-only=X option. 87// 88bool llvm::isCurrentDebugType(const char *DebugType) { 89 return CurrentDebugType.empty() || DebugType == CurrentDebugType; 90} 91 92/// setCurrentDebugType - Set the current debug type, as if the -debug-only=X 93/// option were specified. Note that DebugFlag also needs to be set to true for 94/// debug output to be produced. 95/// 96void llvm::setCurrentDebugType(const char *Type) { 97 CurrentDebugType = Type; 98} 99 100/// dbgs - Return a circular-buffered debug stream. 101raw_ostream &llvm::dbgs() { 102 // Do one-time initialization in a thread-safe way. 103 static struct dbgstream { 104 circular_raw_ostream strm; 105 106 dbgstream() : 107 strm(errs(), "*** Debug Log Output ***\n", 108 (!EnableDebugBuffering || !DebugFlag) ? 0 : DebugBufferSize) { 109 if (EnableDebugBuffering && DebugFlag && DebugBufferSize != 0) 110 // TODO: Add a handler for SIGUSER1-type signals so the user can 111 // force a debug dump. 112 sys::AddSignalHandler(&debug_user_sig_handler, 0); 113 // Otherwise we've already set the debug stream buffer size to 114 // zero, disabling buffering so it will output directly to errs(). 115 } 116 } thestrm; 117 118 return thestrm.strm; 119} 120 121#else 122// Avoid "has no symbols" warning. 123namespace llvm { 124 /// dbgs - Return errs(). 125 raw_ostream &dbgs() { 126 return errs(); 127 } 128} 129 130#endif 131 132/// EnableDebugBuffering - Turn on signal handler installation. 133/// 134bool llvm::EnableDebugBuffering = false; 135