lib/Support/Annotation.cpp

//===-- Annotation.cpp - Implement the Annotation Classes -----------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the AnnotationManager class.
//
//===----------------------------------------------------------------------===//

#include "llvm/Support/Annotation.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/System/RWMutex.h"
#include <map>
#include <cstring>
using namespace llvm;

Annotation::~Annotation() {}  // Designed to be subclassed

Annotable::~Annotable() {   // Virtual because it's designed to be subclassed...
  Annotation *A = AnnotationList;
  while (A) {
    Annotation *Next = A->getNext();
    delete A;
    A = Next;
  }
}

namespace {
  class StrCmp {
  public:
    bool operator()(const char *a, const char *b) const {
      return strcmp(a, b) < 0;
    }
  };
}

typedef std::map<const char*, unsigned, StrCmp> IDMapType;
static volatile sys::cas_flag IDCounter = 0;  // Unique ID counter

// Static member to ensure initialiation on demand.
static ManagedStatic<IDMapType> IDMap;
static ManagedStatic<sys::SmartRWMutex<true> > AnnotationsLock;

// On demand annotation creation support...
typedef Annotation *(*AnnFactory)(AnnotationID, const Annotable *, void *);
typedef std::map<unsigned, std::pair<AnnFactory,void*> > FactMapType;

static ManagedStatic<FactMapType> TheFactMap;
static FactMapType &getFactMap() {
  return *TheFactMap;
}

static void eraseFromFactMap(unsigned ID) {
  sys::SmartScopedWriter<true> Writer(&*AnnotationsLock);
  TheFactMap->erase(ID);
}

AnnotationID AnnotationManager::getID(const char *Name) {  // Name -> ID
  AnnotationsLock->reader_acquire();
  IDMapType::iterator I = IDMap->find(Name);
  IDMapType::iterator E = IDMap->end();
  AnnotationsLock->reader_release();
  
  if (I == E) {
    sys::SmartScopedWriter<true> Writer(&*AnnotationsLock);
    I = IDMap->find(Name);
    if (I == IDMap->end()) {
      unsigned newCount = sys::AtomicIncrement(&IDCounter);
      (*IDMap)[Name] = newCount-1;   // Add a new element
      return AnnotationID(newCount-1);
    } else
      return AnnotationID(I->second);
  }
  return AnnotationID(I->second);
}

// getID - Name -> ID + registration of a factory function for demand driven
// annotation support.
AnnotationID AnnotationManager::getID(const char *Name, Factory Fact,
                                      void *Data) {
  AnnotationID Result(getID(Name));
  registerAnnotationFactory(Result, Fact, Data);
  return Result;
}

// getName - This function is especially slow, but that's okay because it should
// only be used for debugging.
//
const char *AnnotationManager::getName(AnnotationID ID) {  // ID -> Name
  sys::SmartScopedReader<true> Reader(&*AnnotationsLock);
  IDMapType &TheMap = *IDMap;
  for (IDMapType::iterator I = TheMap.begin(); ; ++I) {
    assert(I != TheMap.end() && "Annotation ID is unknown!");
    if (I->second == ID.ID) return I->first;
  }
}

// registerAnnotationFactory - This method is used to register a callback
// function used to create an annotation on demand if it is needed by the
// Annotable::findOrCreateAnnotation method.
//
void AnnotationManager::registerAnnotationFactory(AnnotationID ID, AnnFactory F,
                                                  void *ExtraData) {
  if (F) {
    sys::SmartScopedWriter<true> Writer(&*AnnotationsLock);
    getFactMap()[ID.ID] = std::make_pair(F, ExtraData);
  } else {
    eraseFromFactMap(ID.ID);
  }
}

// createAnnotation - Create an annotation of the specified ID for the
// specified object, using a register annotation creation function.
//
Annotation *AnnotationManager::createAnnotation(AnnotationID ID,
                                                const Annotable *Obj) {
  AnnotationsLock->reader_acquire();
  FactMapType::iterator I = getFactMap().find(ID.ID);
  if (I == getFactMap().end()) {
    AnnotationsLock->reader_release();
    return 0;
  }
  
  AnnotationsLock->reader_release();
  return I->second.first(ID, Obj, I->second.second);
}