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      1 //===- llvm/Support/Debug.h - Easy way to add debug output ------*- C++ -*-===//
      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 // LLVM_DEBUG() requires the DEBUG_TYPE macro to be defined. Set it to "foo"
     16 // specify that your debug code belongs to class "foo". Be careful that you only
     17 // do this after including Debug.h and not around any #include of headers.
     18 // Headers should define and undef the macro acround the code that needs to use
     19 // the LLVM_DEBUG() macro. Then, on the command line, you can specify
     20 // '-debug-only=foo' to enable JUST the debug information for the foo class.
     21 //
     22 // When compiling without assertions, the -debug-* options and all code in
     23 // LLVM_DEBUG() statements disappears, so it does not affect the runtime of the
     24 // code.
     25 //
     26 //===----------------------------------------------------------------------===//
     27 
     28 #ifndef LLVM_SUPPORT_DEBUG_H
     29 #define LLVM_SUPPORT_DEBUG_H
     30 
     31 namespace llvm {
     32 
     33 class raw_ostream;
     34 
     35 #ifndef NDEBUG
     36 
     37 /// isCurrentDebugType - Return true if the specified string is the debug type
     38 /// specified on the command line, or if none was specified on the command line
     39 /// with the -debug-only=X option.
     40 ///
     41 bool isCurrentDebugType(const char *Type);
     42 
     43 /// setCurrentDebugType - Set the current debug type, as if the -debug-only=X
     44 /// option were specified.  Note that DebugFlag also needs to be set to true for
     45 /// debug output to be produced.
     46 ///
     47 void setCurrentDebugType(const char *Type);
     48 
     49 /// setCurrentDebugTypes - Set the current debug type, as if the
     50 /// -debug-only=X,Y,Z option were specified. Note that DebugFlag
     51 /// also needs to be set to true for debug output to be produced.
     52 ///
     53 void setCurrentDebugTypes(const char **Types, unsigned Count);
     54 
     55 /// DEBUG_WITH_TYPE macro - This macro should be used by passes to emit debug
     56 /// information.  In the '-debug' option is specified on the commandline, and if
     57 /// this is a debug build, then the code specified as the option to the macro
     58 /// will be executed.  Otherwise it will not be.  Example:
     59 ///
     60 /// DEBUG_WITH_TYPE("bitset", dbgs() << "Bitset contains: " << Bitset << "\n");
     61 ///
     62 /// This will emit the debug information if -debug is present, and -debug-only
     63 /// is not specified, or is specified as "bitset".
     64 #define DEBUG_WITH_TYPE(TYPE, X)                                        \
     65   do { if (::llvm::DebugFlag && ::llvm::isCurrentDebugType(TYPE)) { X; } \
     66   } while (false)
     67 
     68 #else
     69 #define isCurrentDebugType(X) (false)
     70 #define setCurrentDebugType(X)
     71 #define setCurrentDebugTypes(X, N)
     72 #define DEBUG_WITH_TYPE(TYPE, X) do { } while (false)
     73 #endif
     74 
     75 /// This boolean is set to true if the '-debug' command line option
     76 /// is specified.  This should probably not be referenced directly, instead, use
     77 /// the DEBUG macro below.
     78 ///
     79 extern bool DebugFlag;
     80 
     81 /// \name Verification flags.
     82 ///
     83 /// These flags turns on/off that are expensive and are turned off by default,
     84 /// unless macro EXPENSIVE_CHECKS is defined. The flags allow selectively
     85 /// turning the checks on without need to recompile.
     86 /// \{
     87 
     88 /// Enables verification of dominator trees.
     89 ///
     90 extern bool VerifyDomInfo;
     91 
     92 /// Enables verification of loop info.
     93 ///
     94 extern bool VerifyLoopInfo;
     95 
     96 /// Enables verification of MemorySSA.
     97 ///
     98 extern bool VerifyMemorySSA;
     99 
    100 ///\}
    101 
    102 /// EnableDebugBuffering - This defaults to false.  If true, the debug
    103 /// stream will install signal handlers to dump any buffered debug
    104 /// output.  It allows clients to selectively allow the debug stream
    105 /// to install signal handlers if they are certain there will be no
    106 /// conflict.
    107 ///
    108 extern bool EnableDebugBuffering;
    109 
    110 /// dbgs() - This returns a reference to a raw_ostream for debugging
    111 /// messages.  If debugging is disabled it returns errs().  Use it
    112 /// like: dbgs() << "foo" << "bar";
    113 raw_ostream &dbgs();
    114 
    115 // DEBUG macro - This macro should be used by passes to emit debug information.
    116 // In the '-debug' option is specified on the commandline, and if this is a
    117 // debug build, then the code specified as the option to the macro will be
    118 // executed.  Otherwise it will not be.  Example:
    119 //
    120 // LLVM_DEBUG(dbgs() << "Bitset contains: " << Bitset << "\n");
    121 //
    122 #define LLVM_DEBUG(X) DEBUG_WITH_TYPE(DEBUG_TYPE, X)
    123 
    124 } // end namespace llvm
    125 
    126 #endif // LLVM_SUPPORT_DEBUG_H
    127