diff options
| -rw-r--r-- | absl/container/internal/raw_hash_set.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h index 5c5db12e..47e5a228 100644 --- a/absl/container/internal/raw_hash_set.h +++ b/absl/container/internal/raw_hash_set.h @@ -1446,6 +1446,7 @@ class raw_hash_set { void prefetch(const key_arg<K>& key) const { (void)key; #if defined(__GNUC__) + prefetch_heap_block(); auto seq = probe(ctrl_, hash_ref()(key), capacity_); __builtin_prefetch(static_cast<const void*>(ctrl_ + seq.offset())); __builtin_prefetch(static_cast<const void*>(slots_ + seq.offset())); @@ -1477,6 +1478,7 @@ class raw_hash_set { } template <class K = key_type> iterator find(const key_arg<K>& key) { + prefetch_heap_block(); return find(key, hash_ref()(key)); } @@ -1486,6 +1488,7 @@ class raw_hash_set { } template <class K = key_type> const_iterator find(const key_arg<K>& key) const { + prefetch_heap_block(); return find(key, hash_ref()(key)); } @@ -1856,6 +1859,7 @@ class raw_hash_set { protected: template <class K> std::pair<size_t, bool> find_or_prepare_insert(const K& key) { + prefetch_heap_block(); auto hash = hash_ref()(key); auto seq = probe(ctrl_, hash, capacity_); while (true) { @@ -1918,6 +1922,15 @@ class raw_hash_set { size_t& growth_left() { return settings_.template get<0>(); } + void prefetch_heap_block() const { + // Prefetch the heap-allocated memory region to resolve potential TLB + // misses. This is intended to overlap with execution of calculating the + // hash for a key. +#if defined(__GNUC__) + __builtin_prefetch(static_cast<const void*>(ctrl_), 0, 1); +#endif // __GNUC__ + } + HashtablezInfoHandle& infoz() { return settings_.template get<1>(); } hasher& hash_ref() { return settings_.template get<2>(); } |