node-cache.h

// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_COMPILER_NODE_CACHE_H_
#define V8_COMPILER_NODE_CACHE_H_

#include "src/base/functional.h"
#include "src/base/macros.h"

namespace v8 {
namespace internal {

// Forward declarations.
class Zone;
template <typename>
class ZoneVector;


namespace compiler {

// Forward declarations.
class Node;


// A cache for nodes based on a key. Useful for implementing canonicalization of
// nodes such as constants, parameters, etc.
template <typename Key, typename Hash = base::hash<Key>,
          typename Pred = std::equal_to<Key> >
class V8_EXPORT_PRIVATE NodeCache final {
 public:
  explicit NodeCache(unsigned max = 256)
      : entries_(nullptr), size_(0), max_(max) {}
  ~NodeCache() = default;

  // Search for node associated with {key} and return a pointer to a memory
  // location in this cache that stores an entry for the key. If the location
  // returned by this method contains a non-nullptr node, the caller can use
  // that
  // node. Otherwise it is the responsibility of the caller to fill the entry
  // with a new node.
  // Note that a previous cache entry may be overwritten if the cache becomes
  // too full or encounters too many hash collisions.
  Node** Find(Zone* zone, Key key);

  // Appends all nodes from this cache to {nodes}.
  void GetCachedNodes(ZoneVector<Node*>* nodes);

 private:
  struct Entry;

  Entry* entries_;  // lazily-allocated hash entries.
  size_t size_;
  size_t max_;
  Hash hash_;
  Pred pred_;

  bool Resize(Zone* zone);

  DISALLOW_COPY_AND_ASSIGN(NodeCache);
};

// Various default cache types.
typedef NodeCache<int32_t> Int32NodeCache;
typedef NodeCache<int64_t> Int64NodeCache;

// All we want is the numeric value of the RelocInfo::Mode enum. We typedef
// below to avoid pulling in assembler.h
typedef char RelocInfoMode;
typedef std::pair<int32_t, RelocInfoMode> RelocInt32Key;
typedef std::pair<int64_t, RelocInfoMode> RelocInt64Key;
typedef NodeCache<RelocInt32Key> RelocInt32NodeCache;
typedef NodeCache<RelocInt64Key> RelocInt64NodeCache;
#if V8_HOST_ARCH_32_BIT
typedef Int32NodeCache IntPtrNodeCache;
#else
typedef Int64NodeCache IntPtrNodeCache;
#endif

}  // namespace compiler
}  // namespace internal
}  // namespace v8

#endif  // V8_COMPILER_NODE_CACHE_H_