src/objects/lookup-cache-inl.h

// Copyright 2016 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_OBJECTS_LOOKUP_CACHE_INL_H_
#define V8_OBJECTS_LOOKUP_CACHE_INL_H_

#include "src/objects/lookup-cache.h"
#include "src/objects/map.h"
#include "src/objects/name-inl.h"

namespace v8 {
namespace internal {

// static
int DescriptorLookupCache::Hash(Tagged<Map> source, Tagged<Name> name) {
  DCHECK(IsUniqueName(name));
  // Uses only lower 32 bits if pointers are larger.
  uint32_t source_hash = static_cast<uint32_t>(source.ptr()) >> kTaggedSizeLog2;
  uint32_t name_hash = name->hash();
  return (source_hash ^ name_hash) % kLength;
}

int DescriptorLookupCache::Lookup(Tagged<Map> source, Tagged<Name> name) {
  int index = Hash(source, name);
  Key& key = keys_[index];
  // Pointers in the table might be stale, so use SafeEquals.
  if (key.source.SafeEquals(source) && key.name.SafeEquals(name)) {
    return results_[index];
  }
  return kAbsent;
}

void DescriptorLookupCache::Update(Tagged<Map> source, Tagged<Name> name,
                                   int result) {
  DCHECK_NE(result, kAbsent);
  int index = Hash(source, name);
  Key& key = keys_[index];
  key.source = source;
  key.name = name;
  results_[index] = result;
}

}  // namespace internal
}  // namespace v8

#endif  // V8_OBJECTS_LOOKUP_CACHE_INL_H_