1 files changed, 150 insertions, 2 deletions
diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc
index c63a2e02..fae12793 100644
--- a/absl/container/internal/raw_hash_set.cc
+++ b/absl/container/internal/raw_hash_set.cc
@@ -63,8 +63,156 @@ void ConvertDeletedToEmptyAndFullToDeleted(ctrl_t* ctrl, size_t capacity) {
   std::memcpy(ctrl + capacity + 1, ctrl, NumClonedBytes());
   ctrl[capacity] = ctrl_t::kSentinel;
 }
-// Extern template instantiotion for inline function.
-template FindInfo find_first_non_full(const ctrl_t*, size_t, size_t);
+// Extern template instantiation for inline function.
+template FindInfo find_first_non_full(const CommonFields&, size_t);
+
+FindInfo find_first_non_full_outofline(const CommonFields& common,
+                                       size_t hash) {
+  return find_first_non_full(common, hash);
+}
+
+// Return address of the ith slot in slots where each slot occupies slot_size.
+static inline void* SlotAddress(void* slot_array, size_t slot,
+                                size_t slot_size) {
+  return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(slot_array) +
+                                 (slot * slot_size));
+}
+
+// Return the address of the slot just after slot assuming each slot
+// has the specified size.
+static inline void* NextSlot(void* slot, size_t slot_size) {
+  return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(slot) + slot_size);
+}
+
+// Return the address of the slot just before slot assuming each slot
+// has the specified size.
+static inline void* PrevSlot(void* slot, size_t slot_size) {
+  return reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(slot) - slot_size);
+}
+
+void DropDeletesWithoutResize(CommonFields& common, size_t& growth_left,
+                              const PolicyFunctions& policy, void* tmp_space) {
+  void* set = &common;
+  void* slot_array = common.slots_;
+  const size_t capacity = common.capacity_;
+  assert(IsValidCapacity(capacity));
+  assert(!is_small(capacity));
+  // Algorithm:
+  // - mark all DELETED slots as EMPTY
+  // - mark all FULL slots as DELETED
+  // - for each slot marked as DELETED
+  //     hash = Hash(element)
+  //     target = find_first_non_full(hash)
+  //     if target is in the same group
+  //       mark slot as FULL
+  //     else if target is EMPTY
+  //       transfer element to target
+  //       mark slot as EMPTY
+  //       mark target as FULL
+  //     else if target is DELETED
+  //       swap current element with target element
+  //       mark target as FULL
+  //       repeat procedure for current slot with moved from element (target)
+  ctrl_t* ctrl = common.control_;
+  ConvertDeletedToEmptyAndFullToDeleted(ctrl, capacity);
+  auto hasher = policy.hash_slot;
+  auto transfer = policy.transfer;
+  const size_t slot_size = policy.slot_size;
+
+  size_t total_probe_length = 0;
+  void* slot_ptr = SlotAddress(slot_array, 0, slot_size);
+  for (size_t i = 0; i != capacity;
+       ++i, slot_ptr = NextSlot(slot_ptr, slot_size)) {
+    assert(slot_ptr == SlotAddress(slot_array, i, slot_size));
+    if (!IsDeleted(ctrl[i])) continue;
+    const size_t hash = (*hasher)(set, slot_ptr);
+    const FindInfo target = find_first_non_full(common, hash);
+    const size_t new_i = target.offset;
+    total_probe_length += target.probe_length;
+
+    // Verify if the old and new i fall within the same group wrt the hash.
+    // If they do, we don't need to move the object as it falls already in the
+    // best probe we can.
+    const size_t probe_offset = probe(common, hash).offset();
+    const auto probe_index = [probe_offset, capacity](size_t pos) {
+      return ((pos - probe_offset) & capacity) / Group::kWidth;
+    };
+
+    // Element doesn't move.
+    if (ABSL_PREDICT_TRUE(probe_index(new_i) == probe_index(i))) {
+      SetCtrl(common, i, H2(hash), slot_size);
+      continue;
+    }
+
+    void* new_slot_ptr = SlotAddress(slot_array, new_i, slot_size);
+    if (IsEmpty(ctrl[new_i])) {
+      // Transfer element to the empty spot.
+      // SetCtrl poisons/unpoisons the slots so we have to call it at the
+      // right time.
+      SetCtrl(common, new_i, H2(hash), slot_size);
+      (*transfer)(set, new_slot_ptr, slot_ptr);
+      SetCtrl(common, i, ctrl_t::kEmpty, slot_size);
+    } else {
+      assert(IsDeleted(ctrl[new_i]));
+      SetCtrl(common, new_i, H2(hash), slot_size);
+      // Until we are done rehashing, DELETED marks previously FULL slots.
+
+      // Swap i and new_i elements.
+      (*transfer)(set, tmp_space, new_slot_ptr);
+      (*transfer)(set, new_slot_ptr, slot_ptr);
+      (*transfer)(set, slot_ptr, tmp_space);
+
+      // repeat the processing of the ith slot
+      --i;
+      slot_ptr = PrevSlot(slot_ptr, slot_size);
+    }
+  }
+  ResetGrowthLeft(common, growth_left);
+  common.infoz().RecordRehash(total_probe_length);
+}
+
+void EraseMetaOnly(CommonFields& c, size_t& growth_left, ctrl_t* it,
+                   size_t slot_size) {
+  assert(IsFull(*it) && "erasing a dangling iterator");
+  --c.size_;
+  const auto index = static_cast<size_t>(it - c.control_);
+  const size_t index_before = (index - Group::kWidth) & c.capacity_;
+  const auto empty_after = Group(it).MaskEmpty();
+  const auto empty_before = Group(c.control_ + index_before).MaskEmpty();
+
+  // We count how many consecutive non empties we have to the right and to the
+  // left of `it`. If the sum is >= kWidth then there is at least one probe
+  // window that might have seen a full group.
+  bool was_never_full =
+      empty_before && empty_after &&
+      static_cast<size_t>(empty_after.TrailingZeros() +
+                          empty_before.LeadingZeros()) < Group::kWidth;
+
+  SetCtrl(c, index, was_never_full ? ctrl_t::kEmpty : ctrl_t::kDeleted,
+          slot_size);
+  growth_left += (was_never_full ? 1 : 0);
+  c.infoz().RecordErase();
+}
+
+void ClearBackingArray(CommonFields& c, size_t& growth_left,
+                       const PolicyFunctions& policy, bool reuse) {
+  if (reuse) {
+    c.size_ = 0;
+    ResetCtrl(c, growth_left, policy.slot_size);
+    c.infoz().RecordStorageChanged(0, c.capacity_);
+  } else {
+    void* set = &c;
+    (*policy.dealloc)(set, policy, c.control_, c.slots_, c.capacity_);
+    c.control_ = EmptyGroup();
+    c.slots_ = nullptr;
+    c.size_ = 0;
+    c.capacity_ = 0;
+    growth_left = 0;
+    c.infoz().RecordClearedReservation();
+    assert(c.size_ == 0);
+    c.infoz().RecordStorageChanged(0, 0);
+  }
+}
 
 }  // namespace container_internal
 ABSL_NAMESPACE_END