text: //===- llvm/PassSupport.h - Pass Support code -------------------*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file defines stuff that is used to define and "use" Passes.  This file
  // is automatically #included by Pass.h, so:
  //
  //           NO .CPP FILES SHOULD INCLUDE THIS FILE DIRECTLY
  //
  // Instead, #include Pass.h.
  //
  // This file defines Pass registration code and classes used for it.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef LLVM_PASSSUPPORT_H
  #define LLVM_PASSSUPPORT_H
  
  #include "Pass.h"
  #include "llvm/InitializePasses.h"
  #include "llvm/PassInfo.h"
  #include "llvm/PassRegistry.h"
  #include "llvm/Support/Atomic.h"
  #include "llvm/Support/Valgrind.h"
  #include <vector>
  
  namespace llvm {
  
  class TargetMachine;
  
  #define CALL_ONCE_INITIALIZATION(function) \
    static volatile sys::cas_flag initialized = 0; \
    sys::cas_flag old_val = sys::CompareAndSwap(&initialized, 1, 0); \
    if (old_val == 0) { \
      function(Registry); \
      sys::MemoryFence(); \
      TsanIgnoreWritesBegin(); \
      TsanHappensBefore(&initialized); \
      initialized = 2; \
      TsanIgnoreWritesEnd(); \
    } else { \
      sys::cas_flag tmp = initialized; \
      sys::MemoryFence(); \
      while (tmp != 2) { \
        tmp = initialized; \
        sys::MemoryFence(); \
      } \
    } \
    TsanHappensAfter(&initialized);
  
  #define INITIALIZE_PASS(passName, arg, name, cfg, analysis) \
    static void* initialize##passName##PassOnce(PassRegistry &Registry) { \
      PassInfo *PI = new PassInfo(name, arg, & passName ::ID, \
        PassInfo::NormalCtor_t(callDefaultCtor< passName >), cfg, analysis); \
      Registry.registerPass(*PI, true); \
      return PI; \
    } \
    void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
      CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce) \
    }
  
  #define INITIALIZE_PASS_BEGIN(passName, arg, name, cfg, analysis) \
    static void* initialize##passName##PassOnce(PassRegistry &Registry) {
  
  #define INITIALIZE_PASS_DEPENDENCY(depName) \
      initialize##depName##Pass(Registry);
  #define INITIALIZE_AG_DEPENDENCY(depName) \
      initialize##depName##AnalysisGroup(Registry);
  
  #define INITIALIZE_PASS_END(passName, arg, name, cfg, analysis) \
      PassInfo *PI = new PassInfo(name, arg, & passName ::ID, \
        PassInfo::NormalCtor_t(callDefaultCtor< passName >), cfg, analysis); \
      Registry.registerPass(*PI, true); \
      return PI; \
    } \
    void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
      CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce) \
    }
  
  template<typename PassName>
  Pass *callDefaultCtor() { return new PassName(); }
  
  template <typename PassName> Pass *callTargetMachineCtor(TargetMachine *TM) {
    return new PassName(TM);
  }
  
  //===---------------------------------------------------------------------------
  /// RegisterPass<t> template - This template class is used to notify the system
  /// that a Pass is available for use, and registers it into the internal
  /// database maintained by the PassManager.  Unless this template is used, opt,
  /// for example will not be able to see the pass and attempts to create the pass
  /// will fail. This template is used in the follow manner (at global scope, in
  /// your .cpp file):
  ///
  /// static RegisterPass<YourPassClassName> tmp("passopt", "My Pass Name");
  ///
  /// This statement will cause your pass to be created by calling the default
  /// constructor exposed by the pass.  If you have a different constructor that
  /// must be called, create a global constructor function (which takes the
  /// arguments you need and returns a Pass*) and register your pass like this:
  ///
  /// static RegisterPass<PassClassName> tmp("passopt", "My Name");
  ///
  template<typename passName>
  struct RegisterPass : public PassInfo {
  
    // Register Pass using default constructor...
    RegisterPass(const char *PassArg, const char *Name, bool CFGOnly = false,
                 bool is_analysis = false)
      : PassInfo(Name, PassArg, &passName::ID,
                 PassInfo::NormalCtor_t(callDefaultCtor<passName>),
                 CFGOnly, is_analysis) {
      PassRegistry::getPassRegistry()->registerPass(*this);
    }
  };
  
  
  /// RegisterAnalysisGroup - Register a Pass as a member of an analysis _group_.
  /// Analysis groups are used to define an interface (which need not derive from
  /// Pass) that is required by passes to do their job.  Analysis Groups differ
  /// from normal analyses because any available implementation of the group will
  /// be used if it is available.
  ///
  /// If no analysis implementing the interface is available, a default
  /// implementation is created and added.  A pass registers itself as the default
  /// implementation by specifying 'true' as the second template argument of this
  /// class.
  ///
  /// In addition to registering itself as an analysis group member, a pass must
  /// register itself normally as well.  Passes may be members of multiple groups
  /// and may still be "required" specifically by name.
  ///
  /// The actual interface may also be registered as well (by not specifying the
  /// second template argument).  The interface should be registered to associate
  /// a nice name with the interface.
  ///
  class RegisterAGBase : public PassInfo {
  public:
    RegisterAGBase(const char *Name,
                   const void *InterfaceID,
                   const void *PassID = nullptr,
                   bool isDefault = false);
  };
  
  template<typename Interface, bool Default = false>
  struct RegisterAnalysisGroup : public RegisterAGBase {
    explicit RegisterAnalysisGroup(PassInfo &RPB)
      : RegisterAGBase(RPB.getPassName(),
                       &Interface::ID, RPB.getTypeInfo(),
                       Default) {
    }
  
    explicit RegisterAnalysisGroup(const char *Name)
      : RegisterAGBase(Name, &Interface::ID) {
    }
  };
  
  #define INITIALIZE_ANALYSIS_GROUP(agName, name, defaultPass) \
    static void* initialize##agName##AnalysisGroupOnce(PassRegistry &Registry) { \
      initialize##defaultPass##Pass(Registry); \
      PassInfo *AI = new PassInfo(name, & agName :: ID); \
      Registry.registerAnalysisGroup(& agName ::ID, 0, *AI, false, true); \
      return AI; \
    } \
    void llvm::initialize##agName##AnalysisGroup(PassRegistry &Registry) { \
      CALL_ONCE_INITIALIZATION(initialize##agName##AnalysisGroupOnce) \
    }
  
  
  #define INITIALIZE_AG_PASS(passName, agName, arg, name, cfg, analysis, def) \
    static void* initialize##passName##PassOnce(PassRegistry &Registry) { \
      if (!def) initialize##agName##AnalysisGroup(Registry); \
      PassInfo *PI = new PassInfo(name, arg, & passName ::ID, \
        PassInfo::NormalCtor_t(callDefaultCtor< passName >), cfg, analysis); \
      Registry.registerPass(*PI, true); \
      \
      PassInfo *AI = new PassInfo(name, & agName :: ID); \
      Registry.registerAnalysisGroup(& agName ::ID, & passName ::ID, \
                                     *AI, def, true); \
      return AI; \
    } \
    void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
      CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce) \
    }
  
  
  #define INITIALIZE_AG_PASS_BEGIN(passName, agName, arg, n, cfg, analysis, def) \
    static void* initialize##passName##PassOnce(PassRegistry &Registry) { \
      if (!def) initialize##agName##AnalysisGroup(Registry);
  
  #define INITIALIZE_AG_PASS_END(passName, agName, arg, n, cfg, analysis, def) \
      PassInfo *PI = new PassInfo(n, arg, & passName ::ID, \
        PassInfo::NormalCtor_t(callDefaultCtor< passName >), cfg, analysis); \
      Registry.registerPass(*PI, true); \
      \
      PassInfo *AI = new PassInfo(n, & agName :: ID); \
      Registry.registerAnalysisGroup(& agName ::ID, & passName ::ID, \
                                     *AI, def, true); \
      return AI; \
    } \
    void llvm::initialize##passName##Pass(PassRegistry &Registry) { \
      CALL_ONCE_INITIALIZATION(initialize##passName##PassOnce) \
    }
  
  //===---------------------------------------------------------------------------
  /// PassRegistrationListener class - This class is meant to be derived from by
  /// clients that are interested in which passes get registered and unregistered
  /// at runtime (which can be because of the RegisterPass constructors being run
  /// as the program starts up, or may be because a shared object just got
  /// loaded).
  ///
  struct PassRegistrationListener {
  
    PassRegistrationListener() {}
    virtual ~PassRegistrationListener() {}
  
    /// Callback functions - These functions are invoked whenever a pass is loaded
    /// or removed from the current executable.
    ///
    virtual void passRegistered(const PassInfo *) {}
  
    /// enumeratePasses - Iterate over the registered passes, calling the
    /// passEnumerate callback on each PassInfo object.
    ///
    void enumeratePasses();
  
    /// passEnumerate - Callback function invoked when someone calls
    /// enumeratePasses on this PassRegistrationListener object.
    ///
    virtual void passEnumerate(const PassInfo *) {}
  };
  
  
  } // End llvm namespace
  
  #endif
  