lib/Support/Debug.cpp

   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 using namespace llvm;
  29
  30 bool llvm::DebugFlag;  // DebugFlag - Exported boolean set by the -debug option
  31
  32 namespace {
  33 #ifndef NDEBUG
  34   // -debug - Command line option to enable the DEBUG statements in the passes.
  35   // This flag may only be enabled in debug builds.
  36   static cl::opt<bool, true>
  37   Debug("debug", cl::desc("Enable debug output"), cl::Hidden,
  38         cl::location(DebugFlag));
  39
  40   static std::string CurrentDebugType;
  41   static struct DebugOnlyOpt {
  42     void operator=(const std::string &Val) const {
  43       DebugFlag |= !Val.empty();
  44       CurrentDebugType = Val;
  45     }
  46   } DebugOnlyOptLoc;
  47
  48   static cl::opt<DebugOnlyOpt, true, cl::parser<std::string> >
  49   DebugOnly("debug-only", cl::desc("Enable a specific type of debug output"),
  50             cl::Hidden, cl::value_desc("debug string"),
  51             cl::location(DebugOnlyOptLoc), cl::ValueRequired);
  52 #endif
  53 }
  54
  55 // isCurrentDebugType - Return true if the specified string is the debug type
  56 // specified on the command line, or if none was specified on the command line
  57 // with the -debug-only=X option.
  58 //
  59 bool llvm::isCurrentDebugType(const char *DebugType) {
  60 #ifndef NDEBUG
  61   return CurrentDebugType.empty() || DebugType == CurrentDebugType;
  62 #else
  63   return false;
  64 #endif
  65 }
  66
  67 /// getNullOutputStream - Return a null string that does not output
  68 /// anything.  This hides the static variable from other modules.
  69 ///
  70 OStream &llvm::getNullOutputStream() {
  71   static llvm::OStream NullStream(0);
  72   return NullStream;
  73 }
  74
  75 // getErrorOutputStream - Returns the error output stream (std::cerr). This
  76 // places the std::c* I/O streams into one .cpp file and relieves the whole
  77 // program from having to have hundreds of static c'tor/d'tors for them.
  78 //
  79 OStream &llvm::getErrorOutputStream(const char *DebugType) {
  80   static OStream cnoout(0);
  81   if (DebugFlag && isCurrentDebugType(DebugType))
  82     return cerr;
  83   else
  84     return cnoout;
  85 }