//===---------- CostAllocator.h - PBQP Cost Allocator -----------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Defines classes conforming to the PBQP cost value manager concept.
//
// Cost value managers are memory managers for PBQP cost values (vectors and
// matrices). Since PBQP graphs can grow very large (E.g. hundreds of thousands
// of edges on the largest function in SPEC2006).
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_CODEGEN_PBQP_COSTALLOCATOR_H
#define LLVM_CODEGEN_PBQP_COSTALLOCATOR_H

#include "llvm/ADT/DenseSet.h"
#include <memory>
#include <type_traits>

namespace llvm {
namespace PBQP {

template <typename ValueT>
class ValuePool {
public:
  typedef std::shared_ptr<const ValueT> PoolRef;

private:

  class PoolEntry : public std::enable_shared_from_this<PoolEntry> {
  public:
    template <typename ValueKeyT>
    PoolEntry(ValuePool &Pool, ValueKeyT Value)
        : Pool(Pool), Value(std::move(Value)) {}
    ~PoolEntry() { Pool.removeEntry(this); }
    const ValueT& getValue() const { return Value; }
  private:
    ValuePool &Pool;
    ValueT Value;
  };

  class PoolEntryDSInfo {
  public:
    static inline PoolEntry* getEmptyKey() { return nullptr; }

    static inline PoolEntry* getTombstoneKey() {
      return reinterpret_cast<PoolEntry*>(static_cast<uintptr_t>(1));
    }

    template <typename ValueKeyT>
    static unsigned getHashValue(const ValueKeyT &C) {
      return hash_value(C);
    }

    static unsigned getHashValue(PoolEntry *P) {
      return getHashValue(P->getValue());
    }

    static unsigned getHashValue(const PoolEntry *P) {
      return getHashValue(P->getValue());
    }

    template <typename ValueKeyT1, typename ValueKeyT2>
    static
    bool isEqual(const ValueKeyT1 &C1, const ValueKeyT2 &C2) {
      return C1 == C2;
    }

    template <typename ValueKeyT>
    static bool isEqual(const ValueKeyT &C, PoolEntry *P) {
      if (P == getEmptyKey() || P == getTombstoneKey())
        return false;
      return isEqual(C, P->getValue());
    }

    static bool isEqual(PoolEntry *P1, PoolEntry *P2) {
      if (P1 == getEmptyKey() || P1 == getTombstoneKey())
        return P1 == P2;
      return isEqual(P1->getValue(), P2);
    }

  };

  typedef DenseSet<PoolEntry*, PoolEntryDSInfo> EntrySetT;

  EntrySetT EntrySet;

  void removeEntry(PoolEntry *P) { EntrySet.erase(P); }

public:
  template <typename ValueKeyT> PoolRef getValue(ValueKeyT ValueKey) {
    typename EntrySetT::iterator I = EntrySet.find_as(ValueKey);

    if (I != EntrySet.end())
      return PoolRef((*I)->shared_from_this(), &(*I)->getValue());

    auto P = std::make_shared<PoolEntry>(*this, std::move(ValueKey));
    EntrySet.insert(P.get());
    return PoolRef(std::move(P), &P->getValue());
  }
};

template <typename VectorT, typename MatrixT>
class PoolCostAllocator {
private:
  typedef ValuePool<VectorT> VectorCostPool;
  typedef ValuePool<MatrixT> MatrixCostPool;
public:
  typedef VectorT Vector;
  typedef MatrixT Matrix;
  typedef typename VectorCostPool::PoolRef VectorPtr;
  typedef typename MatrixCostPool::PoolRef MatrixPtr;

  template <typename VectorKeyT>
  VectorPtr getVector(VectorKeyT v) { return VectorPool.getValue(std::move(v)); }

  template <typename MatrixKeyT>
  MatrixPtr getMatrix(MatrixKeyT m) { return MatrixPool.getValue(std::move(m)); }
private:
  VectorCostPool VectorPool;
  MatrixCostPool MatrixPool;
};

} // namespace PBQP
} // namespace llvm

#endif