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      1 // Copyright 2014 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef V8_COMPILER_NODE_CACHE_H_
      6 #define V8_COMPILER_NODE_CACHE_H_
      7 
      8 #include "src/base/functional.h"
      9 #include "src/base/macros.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 
     14 // Forward declarations.
     15 class Zone;
     16 template <typename>
     17 class ZoneVector;
     18 
     19 
     20 namespace compiler {
     21 
     22 // Forward declarations.
     23 class Node;
     24 
     25 
     26 // A cache for nodes based on a key. Useful for implementing canonicalization of
     27 // nodes such as constants, parameters, etc.
     28 template <typename Key, typename Hash = base::hash<Key>,
     29           typename Pred = std::equal_to<Key> >
     30 class NodeCache final {
     31  public:
     32   explicit NodeCache(unsigned max = 256)
     33       : entries_(nullptr), size_(0), max_(max) {}
     34   ~NodeCache() {}
     35 
     36   // Search for node associated with {key} and return a pointer to a memory
     37   // location in this cache that stores an entry for the key. If the location
     38   // returned by this method contains a non-nullptr node, the caller can use
     39   // that
     40   // node. Otherwise it is the responsibility of the caller to fill the entry
     41   // with a new node.
     42   // Note that a previous cache entry may be overwritten if the cache becomes
     43   // too full or encounters too many hash collisions.
     44   Node** Find(Zone* zone, Key key);
     45 
     46   // Appends all nodes from this cache to {nodes}.
     47   void GetCachedNodes(ZoneVector<Node*>* nodes);
     48 
     49  private:
     50   struct Entry;
     51 
     52   Entry* entries_;  // lazily-allocated hash entries.
     53   size_t size_;
     54   size_t max_;
     55   Hash hash_;
     56   Pred pred_;
     57 
     58   bool Resize(Zone* zone);
     59 
     60   DISALLOW_COPY_AND_ASSIGN(NodeCache);
     61 };
     62 
     63 // Various default cache types.
     64 typedef NodeCache<int32_t> Int32NodeCache;
     65 typedef NodeCache<int64_t> Int64NodeCache;
     66 
     67 // All we want is the numeric value of the RelocInfo::Mode enum. We typedef
     68 // below to avoid pulling in assembler.h
     69 typedef char RelocInfoMode;
     70 typedef std::pair<int32_t, RelocInfoMode> RelocInt32Key;
     71 typedef std::pair<int64_t, RelocInfoMode> RelocInt64Key;
     72 typedef NodeCache<RelocInt32Key> RelocInt32NodeCache;
     73 typedef NodeCache<RelocInt64Key> RelocInt64NodeCache;
     74 #if V8_HOST_ARCH_32_BIT
     75 typedef Int32NodeCache IntPtrNodeCache;
     76 #else
     77 typedef Int64NodeCache IntPtrNodeCache;
     78 #endif
     79 
     80 }  // namespace compiler
     81 }  // namespace internal
     82 }  // namespace v8
     83 
     84 #endif  // V8_COMPILER_NODE_CACHE_H_
     85