Merge new upstream LTS 20230802.0

1 files changed, 437 insertions, 236 deletions

diff --git a/absl/container/internal/raw_hash_set.h b/absl/container/internal/raw_hash_set.h
index 61ef196d..5f89d8ef 100644
--- a/absl/container/internal/raw_hash_set.h
+++ b/absl/container/internal/raw_hash_set.h
@@ -62,6 +62,8 @@
 // pseudo-struct:
 //
 //   struct BackingArray {
+//     // The number of elements we can insert before growing the capacity.
+//     size_t growth_left;
 //     // Control bytes for the "real" slots.
 //     ctrl_t ctrl[capacity];
 //     // Always `ctrl_t::kSentinel`. This is used by iterators to find when to
@@ -115,7 +117,7 @@
 // starting with that index and extract potential candidates: occupied slots
 // with a control byte equal to `H2(hash(x))`. If we find an empty slot in the
 // group, we stop and return an error. Each candidate slot `y` is compared with
-// `x`; if `x == y`, we are done and return `&y`; otherwise we contine to the
+// `x`; if `x == y`, we are done and return `&y`; otherwise we continue to the
 // next probe index. Tombstones effectively behave like full slots that never
 // match the value we're looking for.
 //
@@ -174,21 +176,23 @@
 
 #include <algorithm>
 #include <cmath>
+#include <cstddef>
 #include <cstdint>
 #include <cstring>
 #include <iterator>
 #include <limits>
 #include <memory>
+#include <string>
 #include <tuple>
 #include <type_traits>
 #include <utility>
 
 #include "absl/base/config.h"
 #include "absl/base/internal/endian.h"
-#include "absl/base/internal/prefetch.h"
 #include "absl/base/internal/raw_logging.h"
 #include "absl/base/optimization.h"
 #include "absl/base/port.h"
+#include "absl/base/prefetch.h"
 #include "absl/container/internal/common.h"
 #include "absl/container/internal/compressed_tuple.h"
 #include "absl/container/internal/container_memory.h"
@@ -235,6 +239,14 @@ namespace container_internal {
 // We use uint8_t so we don't need to worry about padding.
 using GenerationType = uint8_t;
 
+// A sentinel value for empty generations. Using 0 makes it easy to constexpr
+// initialize an array of this value.
+constexpr GenerationType SentinelEmptyGeneration() { return 0; }
+
+constexpr GenerationType NextGeneration(GenerationType generation) {
+  return ++generation == SentinelEmptyGeneration() ? ++generation : generation;
+}
+
 #ifdef ABSL_SWISSTABLE_ENABLE_GENERATIONS
 constexpr bool SwisstableGenerationsEnabled() { return true; }
 constexpr size_t NumGenerationBytes() { return sizeof(GenerationType); }
@@ -367,12 +379,12 @@ class NonIterableBitMask {
     return static_cast<uint32_t>((bit_width(mask_) - 1) >> Shift);
   }
 
-  // Return the number of trailing zero *abstract* bits.
+  // Returns the number of trailing zero *abstract* bits.
   uint32_t TrailingZeros() const {
     return container_internal::TrailingZeros(mask_) >> Shift;
   }
 
-  // Return the number of leading zero *abstract* bits.
+  // Returns the number of leading zero *abstract* bits.
   uint32_t LeadingZeros() const {
     constexpr int total_significant_bits = SignificantBits << Shift;
     constexpr int extra_bits = sizeof(T) * 8 - total_significant_bits;
@@ -475,19 +487,23 @@ static_assert(ctrl_t::kDeleted == static_cast<ctrl_t>(-2),
               "ctrl_t::kDeleted must be -2 to make the implementation of "
               "ConvertSpecialToEmptyAndFullToDeleted efficient");
 
-ABSL_DLL extern const ctrl_t kEmptyGroup[17];
+// See definition comment for why this is size 32.
+ABSL_DLL extern const ctrl_t kEmptyGroup[32];
 
 // Returns a pointer to a control byte group that can be used by empty tables.
 inline ctrl_t* EmptyGroup() {
   // Const must be cast away here; no uses of this function will actually write
   // to it, because it is only used for empty tables.
-  return const_cast<ctrl_t*>(kEmptyGroup);
+  return const_cast<ctrl_t*>(kEmptyGroup + 16);
 }
 
-// Returns a pointer to the generation byte at the end of the empty group, if it
-// exists.
-inline GenerationType* EmptyGeneration() {
-  return reinterpret_cast<GenerationType*>(EmptyGroup() + 16);
+// Returns a pointer to a generation to use for an empty hashtable.
+GenerationType* EmptyGeneration();
+
+// Returns whether `generation` is a generation for an empty hashtable that
+// could be returned by EmptyGeneration().
+inline bool IsEmptyGeneration(const GenerationType* generation) {
+  return *generation == SentinelEmptyGeneration();
 }
 
 // Mixes a randomly generated per-process seed with `hash` and `ctrl` to
@@ -674,9 +690,10 @@ struct GroupAArch64Impl {
   void ConvertSpecialToEmptyAndFullToDeleted(ctrl_t* dst) const {
     uint64_t mask = vget_lane_u64(vreinterpret_u64_u8(ctrl), 0);
     constexpr uint64_t msbs = 0x8080808080808080ULL;
-    constexpr uint64_t lsbs = 0x0101010101010101ULL;
-    auto x = mask & msbs;
-    auto res = (~x + (x >> 7)) & ~lsbs;
+    constexpr uint64_t slsbs = 0x0202020202020202ULL;
+    constexpr uint64_t midbs = 0x7e7e7e7e7e7e7e7eULL;
+    auto x = slsbs & (mask >> 6);
+    auto res = (x + midbs) | msbs;
     little_endian::Store64(dst, res);
   }
 
@@ -749,6 +766,15 @@ using Group = GroupAArch64Impl;
 using Group = GroupPortableImpl;
 #endif
 
+// When there is an insertion with no reserved growth, we rehash with
+// probability `min(1, RehashProbabilityConstant() / capacity())`. Using a
+// constant divided by capacity ensures that inserting N elements is still O(N)
+// in the average case. Using the constant 16 means that we expect to rehash ~8
+// times more often than when generations are disabled. We are adding expected
+// rehash_probability * #insertions/capacity_growth = 16/capacity * ((7/8 -
+// 7/16) * capacity)/capacity_growth = ~7 extra rehashes per capacity growth.
+inline size_t RehashProbabilityConstant() { return 16; }
+
 class CommonFieldsGenerationInfoEnabled {
   // A sentinel value for reserved_growth_ indicating that we just ran out of
   // reserved growth on the last insertion. When reserve is called and then
@@ -760,8 +786,11 @@ class CommonFieldsGenerationInfoEnabled {
  public:
   CommonFieldsGenerationInfoEnabled() = default;
   CommonFieldsGenerationInfoEnabled(CommonFieldsGenerationInfoEnabled&& that)
-      : reserved_growth_(that.reserved_growth_), generation_(that.generation_) {
+      : reserved_growth_(that.reserved_growth_),
+        reservation_size_(that.reservation_size_),
+        generation_(that.generation_) {
     that.reserved_growth_ = 0;
+    that.reservation_size_ = 0;
     that.generation_ = EmptyGeneration();
   }
   CommonFieldsGenerationInfoEnabled& operator=(
@@ -769,19 +798,17 @@ class CommonFieldsGenerationInfoEnabled {
 
   // Whether we should rehash on insert in order to detect bugs of using invalid
   // references. We rehash on the first insertion after reserved_growth_ reaches
-  // 0 after a call to reserve.
-  // TODO(b/254649633): we could potentially do a rehash with low probability
+  // 0 after a call to reserve. We also do a rehash with low probability
   // whenever reserved_growth_ is zero.
-  bool should_rehash_for_bug_detection_on_insert() const {
-    return reserved_growth_ == kReservedGrowthJustRanOut;
-  }
+  bool should_rehash_for_bug_detection_on_insert(const ctrl_t* ctrl,
+                                                 size_t capacity) const;
   void maybe_increment_generation_on_insert() {
     if (reserved_growth_ == kReservedGrowthJustRanOut) reserved_growth_ = 0;
 
     if (reserved_growth_ > 0) {
       if (--reserved_growth_ == 0) reserved_growth_ = kReservedGrowthJustRanOut;
     } else {
-      ++*generation_;
+      *generation_ = NextGeneration(*generation_);
     }
   }
   void reset_reserved_growth(size_t reservation, size_t size) {
@@ -789,6 +816,8 @@ class CommonFieldsGenerationInfoEnabled {
   }
   size_t reserved_growth() const { return reserved_growth_; }
   void set_reserved_growth(size_t r) { reserved_growth_ = r; }
+  size_t reservation_size() const { return reservation_size_; }
+  void set_reservation_size(size_t r) { reservation_size_ = r; }
   GenerationType generation() const { return *generation_; }
   void set_generation(GenerationType g) { *generation_ = g; }
   GenerationType* generation_ptr() const { return generation_; }
@@ -796,10 +825,14 @@ class CommonFieldsGenerationInfoEnabled {
 
  private:
   // The number of insertions remaining that are guaranteed to not rehash due to
-  // a prior call to reserve. Note: we store reserved growth rather than
+  // a prior call to reserve. Note: we store reserved growth in addition to
   // reservation size because calls to erase() decrease size_ but don't decrease
   // reserved growth.
   size_t reserved_growth_ = 0;
+  // The maximum argument to reserve() since the container was cleared. We need
+  // to keep track of this, in addition to reserved growth, because we reset
+  // reserved growth to this when erase(begin(), end()) is called.
+  size_t reservation_size_ = 0;
   // Pointer to the generation counter, which is used to validate iterators and
   // is stored in the backing array between the control bytes and the slots.
   // Note that we can't store the generation inside the container itself and
@@ -820,11 +853,15 @@ class CommonFieldsGenerationInfoDisabled {
   CommonFieldsGenerationInfoDisabled& operator=(
       CommonFieldsGenerationInfoDisabled&&) = default;
 
-  bool should_rehash_for_bug_detection_on_insert() const { return false; }
+  bool should_rehash_for_bug_detection_on_insert(const ctrl_t*, size_t) const {
+    return false;
+  }
   void maybe_increment_generation_on_insert() {}
   void reset_reserved_growth(size_t, size_t) {}
   size_t reserved_growth() const { return 0; }
   void set_reserved_growth(size_t) {}
+  size_t reservation_size() const { return 0; }
+  void set_reservation_size(size_t) {}
   GenerationType generation() const { return 0; }
   void set_generation(GenerationType) {}
   GenerationType* generation_ptr() const { return nullptr; }
@@ -867,6 +904,44 @@ using CommonFieldsGenerationInfo = CommonFieldsGenerationInfoDisabled;
 using HashSetIteratorGenerationInfo = HashSetIteratorGenerationInfoDisabled;
 #endif
 
+// Returns whether `n` is a valid capacity (i.e., number of slots).
+//
+// A valid capacity is a non-zero integer `2^m - 1`.
+inline bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; }
+
+// Computes the offset from the start of the backing allocation of the control
+// bytes. growth_left is stored at the beginning of the backing array.
+inline size_t ControlOffset() { return sizeof(size_t); }
+
+// Returns the number of "cloned control bytes".
+//
+// This is the number of control bytes that are present both at the beginning
+// of the control byte array and at the end, such that we can create a
+// `Group::kWidth`-width probe window starting from any control byte.
+constexpr size_t NumClonedBytes() { return Group::kWidth - 1; }
+
+// Given the capacity of a table, computes the offset (from the start of the
+// backing allocation) of the generation counter (if it exists).
+inline size_t GenerationOffset(size_t capacity) {
+  assert(IsValidCapacity(capacity));
+  const size_t num_control_bytes = capacity + 1 + NumClonedBytes();
+  return ControlOffset() + num_control_bytes;
+}
+
+// Given the capacity of a table, computes the offset (from the start of the
+// backing allocation) at which the slots begin.
+inline size_t SlotOffset(size_t capacity, size_t slot_align) {
+  assert(IsValidCapacity(capacity));
+  return (GenerationOffset(capacity) + NumGenerationBytes() + slot_align - 1) &
+         (~slot_align + 1);
+}
+
+// Given the capacity of a table, computes the total size of the backing
+// array.
+inline size_t AllocSize(size_t capacity, size_t slot_size, size_t slot_align) {
+  return SlotOffset(capacity, slot_align) + capacity * slot_size;
+}
+
 // CommonFields hold the fields in raw_hash_set that do not depend
 // on template parameters. This allows us to conveniently pass all
 // of this state to helper functions as a single argument.
@@ -884,72 +959,102 @@ class CommonFields : public CommonFieldsGenerationInfo {
             std::move(static_cast<CommonFieldsGenerationInfo&&>(that))),
         // Explicitly copying fields into "this" and then resetting "that"
         // fields generates less code then calling absl::exchange per field.
-        control_(that.control_),
-        slots_(that.slots_),
-        size_(that.size_),
-        capacity_(that.capacity_),
-        compressed_tuple_(that.growth_left(), std::move(that.infoz())) {
-    that.control_ = EmptyGroup();
-    that.slots_ = nullptr;
-    that.size_ = 0;
-    that.capacity_ = 0;
-    that.growth_left() = 0;
+        control_(that.control()),
+        slots_(that.slot_array()),
+        capacity_(that.capacity()),
+        compressed_tuple_(that.size(), std::move(that.infoz())) {
+    that.set_control(EmptyGroup());
+    that.set_slots(nullptr);
+    that.set_capacity(0);
+    that.set_size(0);
   }
   CommonFields& operator=(CommonFields&&) = default;
 
+  ctrl_t* control() const { return control_; }
+  void set_control(ctrl_t* c) { control_ = c; }
+  void* backing_array_start() const {
+    // growth_left is stored before control bytes.
+    assert(reinterpret_cast<uintptr_t>(control()) % alignof(size_t) == 0);
+    return control() - sizeof(size_t);
+  }
+
+  // Note: we can't use slots() because Qt defines "slots" as a macro.
+  void* slot_array() const { return slots_; }
+  void set_slots(void* s) { slots_ = s; }
+
+  // The number of filled slots.
+  size_t size() const { return compressed_tuple_.template get<0>(); }
+  void set_size(size_t s) { compressed_tuple_.template get<0>() = s; }
+
+  // The total number of available slots.
+  size_t capacity() const { return capacity_; }
+  void set_capacity(size_t c) {
+    assert(c == 0 || IsValidCapacity(c));
+    capacity_ = c;
+  }
+
   // The number of slots we can still fill without needing to rehash.
-  size_t& growth_left() { return compressed_tuple_.template get<0>(); }
+  // This is stored in the heap allocation before the control bytes.
+  size_t growth_left() const {
+    return *reinterpret_cast<size_t*>(backing_array_start());
+  }
+  void set_growth_left(size_t gl) {
+    *reinterpret_cast<size_t*>(backing_array_start()) = gl;
+  }
 
   HashtablezInfoHandle& infoz() { return compressed_tuple_.template get<1>(); }
   const HashtablezInfoHandle& infoz() const {
     return compressed_tuple_.template get<1>();
   }
 
+  bool should_rehash_for_bug_detection_on_insert() const {
+    return CommonFieldsGenerationInfo::
+        should_rehash_for_bug_detection_on_insert(control(), capacity());
+  }
   void reset_reserved_growth(size_t reservation) {
-    CommonFieldsGenerationInfo::reset_reserved_growth(reservation, size_);
+    CommonFieldsGenerationInfo::reset_reserved_growth(reservation, size());
+  }
+
+  // The size of the backing array allocation.
+  size_t alloc_size(size_t slot_size, size_t slot_align) const {
+    return AllocSize(capacity(), slot_size, slot_align);
   }
 
+  // Returns the number of control bytes set to kDeleted. For testing only.
+  size_t TombstonesCount() const {
+    return static_cast<size_t>(
+        std::count(control(), control() + capacity(), ctrl_t::kDeleted));
+  }
+
+ private:
   // TODO(b/259599413): Investigate removing some of these fields:
   // - control/slots can be derived from each other
-  // - size can be moved into the slot array
+  // - we can use 6 bits for capacity since it's always a power of two minus 1
 
-  // The control bytes (and, also, a pointer to the base of the backing array).
+  // The control bytes (and, also, a pointer near to the base of the backing
+  // array).
   //
   // This contains `capacity + 1 + NumClonedBytes()` entries, even
   // when the table is empty (hence EmptyGroup).
+  //
+  // Note that growth_left is stored immediately before this pointer.
   ctrl_t* control_ = EmptyGroup();
 
   // The beginning of the slots, located at `SlotOffset()` bytes after
   // `control`. May be null for empty tables.
   void* slots_ = nullptr;
 
-  // The number of filled slots.
-  size_t size_ = 0;
-
-  // The total number of available slots.
   size_t capacity_ = 0;
 
-  // Bundle together growth_left and HashtablezInfoHandle to ensure EBO for
+  // Bundle together size and HashtablezInfoHandle to ensure EBO for
   // HashtablezInfoHandle when sampling is turned off.
   absl::container_internal::CompressedTuple<size_t, HashtablezInfoHandle>
       compressed_tuple_{0u, HashtablezInfoHandle{}};
 };
 
-// Returns he number of "cloned control bytes".
-//
-// This is the number of control bytes that are present both at the beginning
-// of the control byte array and at the end, such that we can create a
-// `Group::kWidth`-width probe window starting from any control byte.
-constexpr size_t NumClonedBytes() { return Group::kWidth - 1; }
-
 template <class Policy, class Hash, class Eq, class Alloc>
 class raw_hash_set;
 
-// Returns whether `n` is a valid capacity (i.e., number of slots).
-//
-// A valid capacity is a non-zero integer `2^m - 1`.
-inline bool IsValidCapacity(size_t n) { return ((n + 1) & n) == 0 && n > 0; }
-
 // Returns the next valid capacity after `n`.
 inline size_t NextCapacity(size_t n) {
   assert(IsValidCapacity(n) || n == 0);
@@ -1021,34 +1126,75 @@ size_t SelectBucketCountForIterRange(InputIter first, InputIter last,
   return 0;
 }
 
-#define ABSL_INTERNAL_ASSERT_IS_FULL(ctrl, generation, generation_ptr,         \
-                                     operation)                                \
-  do {                                                                         \
-    ABSL_HARDENING_ASSERT(                                                     \
-        (ctrl != nullptr) && operation                                         \
-        " called on invalid iterator. The iterator might be an end() "         \
-        "iterator or may have been default constructed.");                     \
-    if (SwisstableGenerationsEnabled() && generation != *generation_ptr)       \
-      ABSL_INTERNAL_LOG(FATAL, operation                                       \
-                        " called on invalidated iterator. The table could "    \
-                        "have rehashed since this iterator was initialized."); \
-    ABSL_HARDENING_ASSERT(                                                     \
-        (IsFull(*ctrl)) && operation                                           \
-        " called on invalid iterator. The element might have been erased or "  \
-        "the table might have rehashed.");                                     \
-  } while (0)
+constexpr bool SwisstableDebugEnabled() {
+#if defined(ABSL_SWISSTABLE_ENABLE_GENERATIONS) || \
+    ABSL_OPTION_HARDENED == 1 || !defined(NDEBUG)
+  return true;
+#else
+  return false;
+#endif
+}
+
+inline void AssertIsFull(const ctrl_t* ctrl, GenerationType generation,
+                         const GenerationType* generation_ptr,
+                         const char* operation) {
+  if (!SwisstableDebugEnabled()) return;
+  if (ctrl == nullptr) {
+    ABSL_INTERNAL_LOG(FATAL,
+                      std::string(operation) + " called on end() iterator.");
+  }
+  if (ctrl == EmptyGroup()) {
+    ABSL_INTERNAL_LOG(FATAL, std::string(operation) +
+                                 " called on default-constructed iterator.");
+  }
+  if (SwisstableGenerationsEnabled()) {
+    if (generation != *generation_ptr) {
+      ABSL_INTERNAL_LOG(FATAL,
+                        std::string(operation) +
+                            " called on invalid iterator. The table could have "
+                            "rehashed since this iterator was initialized.");
+    }
+    if (!IsFull(*ctrl)) {
+      ABSL_INTERNAL_LOG(
+          FATAL,
+          std::string(operation) +
+              " called on invalid iterator. The element was likely erased.");
+    }
+  } else {
+    if (!IsFull(*ctrl)) {
+      ABSL_INTERNAL_LOG(
+          FATAL,
+          std::string(operation) +
+              " called on invalid iterator. The element might have been erased "
+              "or the table might have rehashed. Consider running with "
+              "--config=asan to diagnose rehashing issues.");
+    }
+  }
+}
 
 // Note that for comparisons, null/end iterators are valid.
 inline void AssertIsValidForComparison(const ctrl_t* ctrl,
                                        GenerationType generation,
                                        const GenerationType* generation_ptr) {
-  ABSL_HARDENING_ASSERT((ctrl == nullptr || IsFull(*ctrl)) &&
-                        "Invalid iterator comparison. The element might have "
-                        "been erased or the table might have rehashed.");
-  if (SwisstableGenerationsEnabled() && generation != *generation_ptr) {
-    ABSL_INTERNAL_LOG(FATAL,
-                      "Invalid iterator comparison. The table could have "
-                      "rehashed since this iterator was initialized.");
+  if (!SwisstableDebugEnabled()) return;
+  const bool ctrl_is_valid_for_comparison =
+      ctrl == nullptr || ctrl == EmptyGroup() || IsFull(*ctrl);
+  if (SwisstableGenerationsEnabled()) {
+    if (generation != *generation_ptr) {
+      ABSL_INTERNAL_LOG(FATAL,
+                        "Invalid iterator comparison. The table could have "
+                        "rehashed since this iterator was initialized.");
+    }
+    if (!ctrl_is_valid_for_comparison) {
+      ABSL_INTERNAL_LOG(
+          FATAL, "Invalid iterator comparison. The element was likely erased.");
+    }
+  } else {
+    ABSL_HARDENING_ASSERT(
+        ctrl_is_valid_for_comparison &&
+        "Invalid iterator comparison. The element might have been erased or "
+        "the table might have rehashed. Consider running with --config=asan to "
+        "diagnose rehashing issues.");
   }
 }
 
@@ -1074,16 +1220,54 @@ inline bool AreItersFromSameContainer(const ctrl_t* ctrl_a,
 // Asserts that two iterators come from the same container.
 // Note: we take slots by reference so that it's not UB if they're uninitialized
 // as long as we don't read them (when ctrl is null).
-// TODO(b/254649633): when generations are enabled, we can detect more cases of
-// different containers by comparing the pointers to the generations - this
-// can cover cases of end iterators that we would otherwise miss.
 inline void AssertSameContainer(const ctrl_t* ctrl_a, const ctrl_t* ctrl_b,
                                 const void* const& slot_a,
-                                const void* const& slot_b) {
-  ABSL_HARDENING_ASSERT(
-      AreItersFromSameContainer(ctrl_a, ctrl_b, slot_a, slot_b) &&
-      "Invalid iterator comparison. The iterators may be from different "
-      "containers or the container might have rehashed.");
+                                const void* const& slot_b,
+                                const GenerationType* generation_ptr_a,
+                                const GenerationType* generation_ptr_b) {
+  if (!SwisstableDebugEnabled()) return;
+  const bool a_is_default = ctrl_a == EmptyGroup();
+  const bool b_is_default = ctrl_b == EmptyGroup();
+  if (a_is_default != b_is_default) {
+    ABSL_INTERNAL_LOG(
+        FATAL,
+        "Invalid iterator comparison. Comparing default-constructed iterator "
+        "with non-default-constructed iterator.");
+  }
+  if (a_is_default && b_is_default) return;
+
+  if (SwisstableGenerationsEnabled()) {
+    if (generation_ptr_a == generation_ptr_b) return;
+    const bool a_is_empty = IsEmptyGeneration(generation_ptr_a);
+    const bool b_is_empty = IsEmptyGeneration(generation_ptr_b);
+    if (a_is_empty != b_is_empty) {
+      ABSL_INTERNAL_LOG(FATAL,
+                        "Invalid iterator comparison. Comparing iterator from "
+                        "a non-empty hashtable with an iterator from an empty "
+                        "hashtable.");
+    }
+    if (a_is_empty && b_is_empty) {
+      ABSL_INTERNAL_LOG(FATAL,
+                        "Invalid iterator comparison. Comparing iterators from "
+                        "different empty hashtables.");
+    }
+    const bool a_is_end = ctrl_a == nullptr;
+    const bool b_is_end = ctrl_b == nullptr;
+    if (a_is_end || b_is_end) {
+      ABSL_INTERNAL_LOG(FATAL,
+                        "Invalid iterator comparison. Comparing iterator with "
+                        "an end() iterator from a different hashtable.");
+    }
+    ABSL_INTERNAL_LOG(FATAL,
+                      "Invalid iterator comparison. Comparing non-end() "
+                      "iterators from different hashtables.");
+  } else {
+    ABSL_HARDENING_ASSERT(
+        AreItersFromSameContainer(ctrl_a, ctrl_b, slot_a, slot_b) &&
+        "Invalid iterator comparison. The iterators may be from different "
+        "containers or the container might have rehashed. Consider running "
+        "with --config=asan to diagnose rehashing issues.");
+  }
 }
 
 struct FindInfo {
@@ -1106,11 +1290,13 @@ struct FindInfo {
 inline bool is_small(size_t capacity) { return capacity < Group::kWidth - 1; }
 
 // Begins a probing operation on `common.control`, using `hash`.
-inline probe_seq<Group::kWidth> probe(const CommonFields& common, size_t hash) {
-  const ctrl_t* ctrl = common.control_;
-  const size_t capacity = common.capacity_;
+inline probe_seq<Group::kWidth> probe(const ctrl_t* ctrl, const size_t capacity,
+                                      size_t hash) {
   return probe_seq<Group::kWidth>(H1(hash, ctrl), capacity);
 }
+inline probe_seq<Group::kWidth> probe(const CommonFields& common, size_t hash) {
+  return probe(common.control(), common.capacity(), hash);
+}
 
 // Probes an array of control bits using a probe sequence derived from `hash`,
 // and returns the offset corresponding to the first deleted or empty slot.
@@ -1122,7 +1308,7 @@ inline probe_seq<Group::kWidth> probe(const CommonFields& common, size_t hash) {
 template <typename = void>
 inline FindInfo find_first_non_full(const CommonFields& common, size_t hash) {
   auto seq = probe(common, hash);
-  const ctrl_t* ctrl = common.control_;
+  const ctrl_t* ctrl = common.control();
   while (true) {
     Group g{ctrl + seq.offset()};
     auto mask = g.MaskEmptyOrDeleted();
@@ -1132,14 +1318,14 @@ inline FindInfo find_first_non_full(const CommonFields& common, size_t hash) {
       // In debug build we will randomly insert in either the front or back of
       // the group.
       // TODO(kfm,sbenza): revisit after we do unconditional mixing
-      if (!is_small(common.capacity_) && ShouldInsertBackwards(hash, ctrl)) {
+      if (!is_small(common.capacity()) && ShouldInsertBackwards(hash, ctrl)) {
         return {seq.offset(mask.HighestBitSet()), seq.index()};
       }
 #endif
       return {seq.offset(mask.LowestBitSet()), seq.index()};
     }
     seq.next();
-    assert(seq.index() <= common.capacity_ && "full table!");
+    assert(seq.index() <= common.capacity() && "full table!");
   }
 }
 
@@ -1153,18 +1339,18 @@ extern template FindInfo find_first_non_full(const CommonFields&, size_t);
 FindInfo find_first_non_full_outofline(const CommonFields&, size_t);
 
 inline void ResetGrowthLeft(CommonFields& common) {
-  common.growth_left() = CapacityToGrowth(common.capacity_) - common.size_;
+  common.set_growth_left(CapacityToGrowth(common.capacity()) - common.size());
 }
 
 // Sets `ctrl` to `{kEmpty, kSentinel, ..., kEmpty}`, marking the entire
 // array as marked as empty.
 inline void ResetCtrl(CommonFields& common, size_t slot_size) {
-  const size_t capacity = common.capacity_;
-  ctrl_t* ctrl = common.control_;
+  const size_t capacity = common.capacity();
+  ctrl_t* ctrl = common.control();
   std::memset(ctrl, static_cast<int8_t>(ctrl_t::kEmpty),
               capacity + 1 + NumClonedBytes());
   ctrl[capacity] = ctrl_t::kSentinel;
-  SanitizerPoisonMemoryRegion(common.slots_, slot_size * capacity);
+  SanitizerPoisonMemoryRegion(common.slot_array(), slot_size * capacity);
   ResetGrowthLeft(common);
 }
 
@@ -1174,17 +1360,17 @@ inline void ResetCtrl(CommonFields& common, size_t slot_size) {
 // mirror the value to the cloned tail if necessary.
 inline void SetCtrl(const CommonFields& common, size_t i, ctrl_t h,
                     size_t slot_size) {
-  const size_t capacity = common.capacity_;
+  const size_t capacity = common.capacity();
   assert(i < capacity);
 
-  auto* slot_i = static_cast<const char*>(common.slots_) + i * slot_size;
+  auto* slot_i = static_cast<const char*>(common.slot_array()) + i * slot_size;
   if (IsFull(h)) {
     SanitizerUnpoisonMemoryRegion(slot_i, slot_size);
   } else {
     SanitizerPoisonMemoryRegion(slot_i, slot_size);
   }
 
-  ctrl_t* ctrl = common.control_;
+  ctrl_t* ctrl = common.control();
   ctrl[i] = h;
   ctrl[((i - NumClonedBytes()) & capacity) + (NumClonedBytes() & capacity)] = h;
 }
@@ -1195,56 +1381,41 @@ inline void SetCtrl(const CommonFields& common, size_t i, h2_t h,
   SetCtrl(common, i, static_cast<ctrl_t>(h), slot_size);
 }
 
-// Given the capacity of a table, computes the offset (from the start of the
-// backing allocation) of the generation counter (if it exists).
-inline size_t GenerationOffset(size_t capacity) {
-  assert(IsValidCapacity(capacity));
-  const size_t num_control_bytes = capacity + 1 + NumClonedBytes();
-  return num_control_bytes;
-}
-
-// Given the capacity of a table, computes the offset (from the start of the
-// backing allocation) at which the slots begin.
-inline size_t SlotOffset(size_t capacity, size_t slot_align) {
-  assert(IsValidCapacity(capacity));
-  const size_t num_control_bytes = capacity + 1 + NumClonedBytes();
-  return (num_control_bytes + NumGenerationBytes() + slot_align - 1) &
-         (~slot_align + 1);
-}
-
-// Given the capacity of a table, computes the total size of the backing
-// array.
-inline size_t AllocSize(size_t capacity, size_t slot_size, size_t slot_align) {
-  return SlotOffset(capacity, slot_align) + capacity * slot_size;
+// growth_left (which is a size_t) is stored with the backing array.
+constexpr size_t BackingArrayAlignment(size_t align_of_slot) {
+  return (std::max)(align_of_slot, alignof(size_t));
 }
 
 template <typename Alloc, size_t SizeOfSlot, size_t AlignOfSlot>
 ABSL_ATTRIBUTE_NOINLINE void InitializeSlots(CommonFields& c, Alloc alloc) {
-  assert(c.capacity_);
+  assert(c.capacity());
   // Folks with custom allocators often make unwarranted assumptions about the
   // behavior of their classes vis-a-vis trivial destructability and what
   // calls they will or won't make.  Avoid sampling for people with custom
   // allocators to get us out of this mess.  This is not a hard guarantee but
   // a workaround while we plan the exact guarantee we want to provide.
   const size_t sample_size =
-      (std::is_same<Alloc, std::allocator<char>>::value && c.slots_ == nullptr)
+      (std::is_same<Alloc, std::allocator<char>>::value &&
+       c.slot_array() == nullptr)
           ? SizeOfSlot
           : 0;
 
-  const size_t cap = c.capacity_;
+  const size_t cap = c.capacity();
+  const size_t alloc_size = AllocSize(cap, SizeOfSlot, AlignOfSlot);
+  // growth_left (which is a size_t) is stored with the backing array.
   char* mem = static_cast<char*>(
-      Allocate<AlignOfSlot>(&alloc, AllocSize(cap, SizeOfSlot, AlignOfSlot)));
+      Allocate<BackingArrayAlignment(AlignOfSlot)>(&alloc, alloc_size));
   const GenerationType old_generation = c.generation();
   c.set_generation_ptr(
       reinterpret_cast<GenerationType*>(mem + GenerationOffset(cap)));
-  c.set_generation(old_generation + 1);
-  c.control_ = reinterpret_cast<ctrl_t*>(mem);
-  c.slots_ = mem + SlotOffset(cap, AlignOfSlot);
+  c.set_generation(NextGeneration(old_generation));
+  c.set_control(reinterpret_cast<ctrl_t*>(mem + ControlOffset()));
+  c.set_slots(mem + SlotOffset(cap, AlignOfSlot));
   ResetCtrl(c, SizeOfSlot);
   if (sample_size) {
     c.infoz() = Sample(sample_size);
   }
-  c.infoz().RecordStorageChanged(c.size_, cap);
+  c.infoz().RecordStorageChanged(c.size(), cap);
 }
 
 // PolicyFunctions bundles together some information for a particular
@@ -1254,15 +1425,14 @@ ABSL_ATTRIBUTE_NOINLINE void InitializeSlots(CommonFields& c, Alloc alloc) {
 struct PolicyFunctions {
   size_t slot_size;
 
-  // Return the hash of the pointed-to slot.
+  // Returns the hash of the pointed-to slot.
   size_t (*hash_slot)(void* set, void* slot);
 
   // Transfer the contents of src_slot to dst_slot.
   void (*transfer)(void* set, void* dst_slot, void* src_slot);
 
-  // Deallocate the specified backing store which is sized for n slots.
-  void (*dealloc)(void* set, const PolicyFunctions& policy, ctrl_t* ctrl,
-                  void* slot_array, size_t n);
+  // Deallocate the backing store from common.
+  void (*dealloc)(CommonFields& common, const PolicyFunctions& policy);
 };
 
 // ClearBackingArray clears the backing array, either modifying it in place,
@@ -1279,16 +1449,16 @@ void EraseMetaOnly(CommonFields& c, ctrl_t* it, size_t slot_size);
 // function body for raw_hash_set instantiations that have the
 // same slot alignment.
 template <size_t AlignOfSlot>
-ABSL_ATTRIBUTE_NOINLINE void DeallocateStandard(void*,
-                                                const PolicyFunctions& policy,
-                                                ctrl_t* ctrl, void* slot_array,
-                                                size_t n) {
+ABSL_ATTRIBUTE_NOINLINE void DeallocateStandard(CommonFields& common,
+                                                const PolicyFunctions& policy) {
   // Unpoison before returning the memory to the allocator.
-  SanitizerUnpoisonMemoryRegion(slot_array, policy.slot_size * n);
+  SanitizerUnpoisonMemoryRegion(common.slot_array(),
+                                policy.slot_size * common.capacity());
 
   std::allocator<char> alloc;
-  Deallocate<AlignOfSlot>(&alloc, ctrl,
-                          AllocSize(n, policy.slot_size, AlignOfSlot));
+  Deallocate<BackingArrayAlignment(AlignOfSlot)>(
+      &alloc, common.backing_array_start(),
+      common.alloc_size(policy.slot_size, AlignOfSlot));
 }
 
 // For trivially relocatable types we use memcpy directly. This allows us to
@@ -1419,22 +1589,19 @@ class raw_hash_set {
 
     // PRECONDITION: not an end() iterator.
     reference operator*() const {
-      ABSL_INTERNAL_ASSERT_IS_FULL(ctrl_, generation(), generation_ptr(),
-                                   "operator*()");
+      AssertIsFull(ctrl_, generation(), generation_ptr(), "operator*()");
       return PolicyTraits::element(slot_);
     }
 
     // PRECONDITION: not an end() iterator.
     pointer operator->() const {
-      ABSL_INTERNAL_ASSERT_IS_FULL(ctrl_, generation(), generation_ptr(),
-                                   "operator->");
+      AssertIsFull(ctrl_, generation(), generation_ptr(), "operator->");
       return &operator*();
     }
 
     // PRECONDITION: not an end() iterator.
     iterator& operator++() {
-      ABSL_INTERNAL_ASSERT_IS_FULL(ctrl_, generation(), generation_ptr(),
-                                   "operator++");
+      AssertIsFull(ctrl_, generation(), generation_ptr(), "operator++");
       ++ctrl_;
       ++slot_;
       skip_empty_or_deleted();
@@ -1448,9 +1615,10 @@ class raw_hash_set {
     }
 
     friend bool operator==(const iterator& a, const iterator& b) {
-      AssertSameContainer(a.ctrl_, b.ctrl_, a.slot_, b.slot_);
       AssertIsValidForComparison(a.ctrl_, a.generation(), a.generation_ptr());
       AssertIsValidForComparison(b.ctrl_, b.generation(), b.generation_ptr());
+      AssertSameContainer(a.ctrl_, b.ctrl_, a.slot_, b.slot_,
+                          a.generation_ptr(), b.generation_ptr());
       return a.ctrl_ == b.ctrl_;
     }
     friend bool operator!=(const iterator& a, const iterator& b) {
@@ -1469,7 +1637,7 @@ class raw_hash_set {
     }
     // For end() iterators.
     explicit iterator(const GenerationType* generation_ptr)
-        : HashSetIteratorGenerationInfo(generation_ptr) {}
+        : HashSetIteratorGenerationInfo(generation_ptr), ctrl_(nullptr) {}
 
     // Fixes up `ctrl_` to point to a full by advancing it and `slot_` until
     // they reach one.
@@ -1484,7 +1652,9 @@ class raw_hash_set {
       if (ABSL_PREDICT_FALSE(*ctrl_ == ctrl_t::kSentinel)) ctrl_ = nullptr;
     }
 
-    ctrl_t* ctrl_ = nullptr;
+    // We use EmptyGroup() for default-constructed iterators so that they can
+    // be distinguished from end iterators, which have nullptr ctrl_.
+    ctrl_t* ctrl_ = EmptyGroup();
     // To avoid uninitialized member warnings, put slot_ in an anonymous union.
     // The member is not initialized on singleton and end iterators.
     union {
@@ -1537,9 +1707,9 @@ class raw_hash_set {
   // Note: can't use `= default` due to non-default noexcept (causes
   // problems for some compilers). NOLINTNEXTLINE
   raw_hash_set() noexcept(
-      std::is_nothrow_default_constructible<hasher>::value&&
-          std::is_nothrow_default_constructible<key_equal>::value&&
-              std::is_nothrow_default_constructible<allocator_type>::value) {}
+      std::is_nothrow_default_constructible<hasher>::value &&
+      std::is_nothrow_default_constructible<key_equal>::value &&
+      std::is_nothrow_default_constructible<allocator_type>::value) {}
 
   ABSL_ATTRIBUTE_NOINLINE explicit raw_hash_set(
       size_t bucket_count, const hasher& hash = hasher(),
@@ -1547,7 +1717,7 @@ class raw_hash_set {
       const allocator_type& alloc = allocator_type())
       : settings_(CommonFields{}, hash, eq, alloc) {
     if (bucket_count) {
-      common().capacity_ = NormalizeCapacity(bucket_count);
+      common().set_capacity(NormalizeCapacity(bucket_count));
       initialize_slots();
     }
   }
@@ -1649,7 +1819,9 @@ class raw_hash_set {
 
   raw_hash_set(const raw_hash_set& that, const allocator_type& a)
       : raw_hash_set(0, that.hash_ref(), that.eq_ref(), a) {
-    reserve(that.size());
+    const size_t size = that.size();
+    if (size == 0) return;
+    reserve(size);
     // Because the table is guaranteed to be empty, we can do something faster
     // than a full `insert`.
     for (const auto& v : that) {
@@ -1660,14 +1832,14 @@ class raw_hash_set {
       common().maybe_increment_generation_on_insert();
       infoz().RecordInsert(hash, target.probe_length);
     }
-    common().size_ = that.size();
-    growth_left() -= that.size();
+    common().set_size(size);
+    set_growth_left(growth_left() - size);
   }
 
   ABSL_ATTRIBUTE_NOINLINE raw_hash_set(raw_hash_set&& that) noexcept(
-      std::is_nothrow_copy_constructible<hasher>::value&&
-          std::is_nothrow_copy_constructible<key_equal>::value&&
-              std::is_nothrow_copy_constructible<allocator_type>::value)
+      std::is_nothrow_copy_constructible<hasher>::value &&
+      std::is_nothrow_copy_constructible<key_equal>::value &&
+      std::is_nothrow_copy_constructible<allocator_type>::value)
       :  // Hash, equality and allocator are copied instead of moved because
          // `that` must be left valid. If Hash is std::function<Key>, moving it
          // would create a nullptr functor that cannot be called.
@@ -1696,9 +1868,9 @@ class raw_hash_set {
   }
 
   raw_hash_set& operator=(raw_hash_set&& that) noexcept(
-      absl::allocator_traits<allocator_type>::is_always_equal::value&&
-          std::is_nothrow_move_assignable<hasher>::value&&
-              std::is_nothrow_move_assignable<key_equal>::value) {
+      absl::allocator_traits<allocator_type>::is_always_equal::value &&
+      std::is_nothrow_move_assignable<hasher>::value &&
+      std::is_nothrow_move_assignable<key_equal>::value) {
     // TODO(sbenza): We should only use the operations from the noexcept clause
     // to make sure we actually adhere to that contract.
     // NOLINTNEXTLINE: not returning *this for performance.
@@ -1714,30 +1886,36 @@ class raw_hash_set {
 
     // Unpoison before returning the memory to the allocator.
     SanitizerUnpoisonMemoryRegion(slot_array(), sizeof(slot_type) * cap);
-    Deallocate<alignof(slot_type)>(
-        &alloc_ref(), control(),
+    Deallocate<BackingArrayAlignment(alignof(slot_type))>(
+        &alloc_ref(), common().backing_array_start(),
         AllocSize(cap, sizeof(slot_type), alignof(slot_type)));
 
     infoz().Unregister();
   }
 
-  iterator begin() {
+  iterator begin() ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto it = iterator_at(0);
     it.skip_empty_or_deleted();
     return it;
   }
-  iterator end() { return iterator(common().generation_ptr()); }
+  iterator end() ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return iterator(common().generation_ptr());
+  }
 
-  const_iterator begin() const {
+  const_iterator begin() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return const_cast<raw_hash_set*>(this)->begin();
   }
-  const_iterator end() const { return iterator(common().generation_ptr()); }
-  const_iterator cbegin() const { return begin(); }
-  const_iterator cend() const { return end(); }
+  const_iterator end() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return iterator(common().generation_ptr());
+  }
+  const_iterator cbegin() const ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    return begin();
+  }
+  const_iterator cend() const ABSL_ATTRIBUTE_LIFETIME_BOUND { return end(); }
 
   bool empty() const { return !size(); }
-  size_t size() const { return common().size_; }
-  size_t capacity() const { return common().capacity_; }
+  size_t size() const { return common().size(); }
+  size_t capacity() const { return common().capacity(); }
   size_t max_size() const { return (std::numeric_limits<size_t>::max)(); }
 
   ABSL_ATTRIBUTE_REINITIALIZES void clear() {
@@ -1753,10 +1931,10 @@ class raw_hash_set {
       // Already guaranteed to be empty; so nothing to do.
     } else {
       destroy_slots();
-      ClearBackingArray(common(), GetPolicyFunctions(),
-                        /*reuse=*/cap < 128);
+      ClearBackingArray(common(), GetPolicyFunctions(), /*reuse=*/cap < 128);
     }
     common().set_reserved_growth(0);
+    common().set_reservation_size(0);
   }
 
   inline void destroy_slots() {
@@ -1780,7 +1958,7 @@ class raw_hash_set {
   template <class T, RequiresInsertable<T> = 0, class T2 = T,
             typename std::enable_if<IsDecomposable<T2>::value, int>::type = 0,
             T* = nullptr>
-  std::pair<iterator, bool> insert(T&& value) {
+  std::pair<iterator, bool> insert(T&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return emplace(std::forward<T>(value));
   }
 
@@ -1795,13 +1973,11 @@ class raw_hash_set {
   //   const char* p = "hello";
   //   s.insert(p);
   //
-  // TODO(romanp): Once we stop supporting gcc 5.1 and below, replace
-  // RequiresInsertable<T> with RequiresInsertable<const T&>.
-  // We are hitting this bug: https://godbolt.org/g/1Vht4f.
   template <
-      class T, RequiresInsertable<T> = 0,
+      class T, RequiresInsertable<const T&> = 0,
       typename std::enable_if<IsDecomposable<const T&>::value, int>::type = 0>
-  std::pair<iterator, bool> insert(const T& value) {
+  std::pair<iterator, bool> insert(const T& value)
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return emplace(value);
   }
 
@@ -1810,7 +1986,8 @@ class raw_hash_set {
   //
   //   flat_hash_map<std::string, int> s;
   //   s.insert({"abc", 42});
-  std::pair<iterator, bool> insert(init_type&& value) {
+  std::pair<iterator, bool> insert(init_type&& value)
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return emplace(std::move(value));
   }
 
@@ -1819,21 +1996,20 @@ class raw_hash_set {
   template <class T, RequiresInsertable<T> = 0, class T2 = T,
             typename std::enable_if<IsDecomposable<T2>::value, int>::type = 0,
             T* = nullptr>
-  iterator insert(const_iterator, T&& value) {
+  iterator insert(const_iterator, T&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return insert(std::forward<T>(value)).first;
   }
 
-  // TODO(romanp): Once we stop supporting gcc 5.1 and below, replace
-  // RequiresInsertable<T> with RequiresInsertable<const T&>.
-  // We are hitting this bug: https://godbolt.org/g/1Vht4f.
   template <
-      class T, RequiresInsertable<T> = 0,
+      class T, RequiresInsertable<const T&> = 0,
       typename std::enable_if<IsDecomposable<const T&>::value, int>::type = 0>
-  iterator insert(const_iterator, const T& value) {
+  iterator insert(const_iterator,
+                  const T& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return insert(value).first;
   }
 
-  iterator insert(const_iterator, init_type&& value) {
+  iterator insert(const_iterator,
+                  init_type&& value) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return insert(std::move(value)).first;
   }
 
@@ -1851,7 +2027,7 @@ class raw_hash_set {
     insert(ilist.begin(), ilist.end());
   }
 
-  insert_return_type insert(node_type&& node) {
+  insert_return_type insert(node_type&& node) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     if (!node) return {end(), false, node_type()};
     const auto& elem = PolicyTraits::element(CommonAccess::GetSlot(node));
     auto res = PolicyTraits::apply(
@@ -1865,7 +2041,8 @@ class raw_hash_set {
     }
   }
 
-  iterator insert(const_iterator, node_type&& node) {
+  iterator insert(const_iterator,
+                  node_type&& node) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto res = insert(std::move(node));
     node = std::move(res.node);
     return res.position;
@@ -1882,7 +2059,8 @@ class raw_hash_set {
   //   m.emplace("abc", "xyz");
   template <class... Args, typename std::enable_if<
                                IsDecomposable<Args...>::value, int>::type = 0>
-  std::pair<iterator, bool> emplace(Args&&... args) {
+  std::pair<iterator, bool> emplace(Args&&... args)
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return PolicyTraits::apply(EmplaceDecomposable{*this},
                                std::forward<Args>(args)...);
   }
@@ -1892,7 +2070,8 @@ class raw_hash_set {
   // destroys.
   template <class... Args, typename std::enable_if<
                                !IsDecomposable<Args...>::value, int>::type = 0>
-  std::pair<iterator, bool> emplace(Args&&... args) {
+  std::pair<iterator, bool> emplace(Args&&... args)
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     alignas(slot_type) unsigned char raw[sizeof(slot_type)];
     slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
@@ -1902,14 +2081,16 @@ class raw_hash_set {
   }
 
   template <class... Args>
-  iterator emplace_hint(const_iterator, Args&&... args) {
+  iterator emplace_hint(const_iterator,
+                        Args&&... args) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return emplace(std::forward<Args>(args)...).first;
   }
 
   // Extension API: support for lazy emplace.
   //
   // Looks up key in the table. If found, returns the iterator to the element.
-  // Otherwise calls `f` with one argument of type `raw_hash_set::constructor`.
+  // Otherwise calls `f` with one argument of type `raw_hash_set::constructor`,
+  // and returns an iterator to the new element.
   //
   // `f` must abide by several restrictions:
   //  - it MUST call `raw_hash_set::constructor` with arguments as if a
@@ -1952,7 +2133,8 @@ class raw_hash_set {
   };
 
   template <class K = key_type, class F>
-  iterator lazy_emplace(const key_arg<K>& key, F&& f) {
+  iterator lazy_emplace(const key_arg<K>& key,
+                        F&& f) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto res = find_or_prepare_insert(key);
     if (res.second) {
       slot_type* slot = slot_array() + res.first;
@@ -1997,13 +2179,25 @@ class raw_hash_set {
   // This overload is necessary because otherwise erase<K>(const K&) would be
   // a better match if non-const iterator is passed as an argument.
   void erase(iterator it) {
-    ABSL_INTERNAL_ASSERT_IS_FULL(it.ctrl_, it.generation(), it.generation_ptr(),
-                                 "erase()");
+    AssertIsFull(it.ctrl_, it.generation(), it.generation_ptr(), "erase()");
     PolicyTraits::destroy(&alloc_ref(), it.slot_);
     erase_meta_only(it);
   }
 
-  iterator erase(const_iterator first, const_iterator last) {
+  iterator erase(const_iterator first,
+                 const_iterator last) ABSL_ATTRIBUTE_LIFETIME_BOUND {
+    // We check for empty first because ClearBackingArray requires that
+    // capacity() > 0 as a precondition.
+    if (empty()) return end();
+    if (first == begin() && last == end()) {
+      // TODO(ezb): we access control bytes in destroy_slots so it could make
+      // sense to combine destroy_slots and ClearBackingArray to avoid cache
+      // misses when the table is large. Note that we also do this in clear().
+      destroy_slots();
+      ClearBackingArray(common(), GetPolicyFunctions(), /*reuse=*/true);
+      common().set_reserved_growth(common().reservation_size());
+      return end();
+    }
     while (first != last) {
       erase(first++);
     }
@@ -2032,9 +2226,8 @@ class raw_hash_set {
   }
 
   node_type extract(const_iterator position) {
-    ABSL_INTERNAL_ASSERT_IS_FULL(position.inner_.ctrl_,
-                                 position.inner_.generation(),
-                                 position.inner_.generation_ptr(), "extract()");
+    AssertIsFull(position.inner_.ctrl_, position.inner_.generation(),
+                 position.inner_.generation_ptr(), "extract()");
     auto node =
         CommonAccess::Transfer<node_type>(alloc_ref(), position.inner_.slot_);
     erase_meta_only(position);
@@ -2064,8 +2257,7 @@ class raw_hash_set {
   void rehash(size_t n) {
     if (n == 0 && capacity() == 0) return;
     if (n == 0 && size() == 0) {
-      ClearBackingArray(common(), GetPolicyFunctions(),
-                        /*reuse=*/false);
+      ClearBackingArray(common(), GetPolicyFunctions(), /*reuse=*/false);
       return;
     }
 
@@ -2092,6 +2284,7 @@ class raw_hash_set {
       infoz().RecordReservation(n);
     }
     common().reset_reserved_growth(n);
+    common().set_reservation_size(n);
   }
 
   // Extension API: support for heterogeneous keys.
@@ -2117,12 +2310,12 @@ class raw_hash_set {
   void prefetch(const key_arg<K>& key) const {
     (void)key;
     // Avoid probing if we won't be able to prefetch the addresses received.
-#ifdef ABSL_INTERNAL_HAVE_PREFETCH
+#ifdef ABSL_HAVE_PREFETCH
     prefetch_heap_block();
     auto seq = probe(common(), hash_ref()(key));
-    base_internal::PrefetchT0(control() + seq.offset());
-    base_internal::PrefetchT0(slot_array() + seq.offset());
-#endif  // ABSL_INTERNAL_HAVE_PREFETCH
+    PrefetchToLocalCache(control() + seq.offset());
+    PrefetchToLocalCache(slot_array() + seq.offset());
+#endif  // ABSL_HAVE_PREFETCH
   }
 
   // The API of find() has two extensions.
@@ -2133,7 +2326,8 @@ class raw_hash_set {
   // 2. The type of the key argument doesn't have to be key_type. This is so
   // called heterogeneous key support.
   template <class K = key_type>
-  iterator find(const key_arg<K>& key, size_t hash) {
+  iterator find(const key_arg<K>& key,
+                size_t hash) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto seq = probe(common(), hash);
     slot_type* slot_ptr = slot_array();
     const ctrl_t* ctrl = control();
@@ -2151,17 +2345,19 @@ class raw_hash_set {
     }
   }
   template <class K = key_type>
-  iterator find(const key_arg<K>& key) {
+  iterator find(const key_arg<K>& key) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     prefetch_heap_block();
     return find(key, hash_ref()(key));
   }
 
   template <class K = key_type>
-  const_iterator find(const key_arg<K>& key, size_t hash) const {
+  const_iterator find(const key_arg<K>& key,
+                      size_t hash) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return const_cast<raw_hash_set*>(this)->find(key, hash);
   }
   template <class K = key_type>
-  const_iterator find(const key_arg<K>& key) const {
+  const_iterator find(const key_arg<K>& key) const
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     prefetch_heap_block();
     return find(key, hash_ref()(key));
   }
@@ -2172,14 +2368,15 @@ class raw_hash_set {
   }
 
   template <class K = key_type>
-  std::pair<iterator, iterator> equal_range(const key_arg<K>& key) {
+  std::pair<iterator, iterator> equal_range(const key_arg<K>& key)
+      ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto it = find(key);
     if (it != end()) return {it, std::next(it)};
     return {it, it};
   }
   template <class K = key_type>
   std::pair<const_iterator, const_iterator> equal_range(
-      const key_arg<K>& key) const {
+      const key_arg<K>& key) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
     auto it = find(key);
     if (it != end()) return {it, std::next(it)};
     return {it, it};
@@ -2313,8 +2510,8 @@ class raw_hash_set {
     assert(IsValidCapacity(new_capacity));
     auto* old_ctrl = control();
     auto* old_slots = slot_array();
-    const size_t old_capacity = common().capacity_;
-    common().capacity_ = new_capacity;
+    const size_t old_capacity = common().capacity();
+    common().set_capacity(new_capacity);
     initialize_slots();
 
     auto* new_slots = slot_array();
@@ -2333,8 +2530,8 @@ class raw_hash_set {
     if (old_capacity) {
       SanitizerUnpoisonMemoryRegion(old_slots,
                                     sizeof(slot_type) * old_capacity);
-      Deallocate<alignof(slot_type)>(
-          &alloc_ref(), old_ctrl,
+      Deallocate<BackingArrayAlignment(alignof(slot_type))>(
+          &alloc_ref(), old_ctrl - ControlOffset(),
           AllocSize(old_capacity, sizeof(slot_type), alignof(slot_type)));
     }
     infoz().RecordRehash(total_probe_length);
@@ -2357,8 +2554,8 @@ class raw_hash_set {
   void rehash_and_grow_if_necessary() {
     const size_t cap = capacity();
     if (cap > Group::kWidth &&
-        // Do these calcuations in 64-bit to avoid overflow.
-        size() * uint64_t{32} <= cap* uint64_t{25}) {
+        // Do these calculations in 64-bit to avoid overflow.
+        size() * uint64_t{32} <= cap * uint64_t{25}) {
       // Squash DELETED without growing if there is enough capacity.
       //
       // Rehash in place if the current size is <= 25/32 of capacity.
@@ -2481,8 +2678,8 @@ class raw_hash_set {
       rehash_and_grow_if_necessary();
       target = find_first_non_full(common(), hash);
     }
-    ++common().size_;
-    growth_left() -= IsEmpty(control()[target.offset]);
+    common().set_size(common().size() + 1);
+    set_growth_left(growth_left() - IsEmpty(control()[target.offset]));
     SetCtrl(common(), target.offset, H2(hash), sizeof(slot_type));
     common().maybe_increment_generation_on_insert();
     infoz().RecordInsert(hash, target.probe_length);
@@ -2507,10 +2704,10 @@ class raw_hash_set {
            "constructed value does not match the lookup key");
   }
 
-  iterator iterator_at(size_t i) {
+  iterator iterator_at(size_t i) ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return {control() + i, slot_array() + i, common().generation_ptr()};
   }
-  const_iterator iterator_at(size_t i) const {
+  const_iterator iterator_at(size_t i) const ABSL_ATTRIBUTE_LIFETIME_BOUND {
     return {control() + i, slot_array() + i, common().generation_ptr()};
   }
 
@@ -2527,19 +2724,24 @@ class raw_hash_set {
   // side-effect.
   //
   // See `CapacityToGrowth()`.
-  size_t& growth_left() { return common().growth_left(); }
-
-  // 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.
-  void prefetch_heap_block() const { base_internal::PrefetchT2(control()); }
+  size_t growth_left() const { return common().growth_left(); }
+  void set_growth_left(size_t gl) { return common().set_growth_left(gl); }
+
+  // Prefetch the heap-allocated memory region to resolve potential TLB and
+  // cache misses. This is intended to overlap with execution of calculating the
+  // hash for a key.
+  void prefetch_heap_block() const {
+#if ABSL_HAVE_BUILTIN(__builtin_prefetch) || defined(__GNUC__)
+    __builtin_prefetch(control(), 0, 1);
+#endif
+  }
 
   CommonFields& common() { return settings_.template get<0>(); }
   const CommonFields& common() const { return settings_.template get<0>(); }
 
-  ctrl_t* control() const { return common().control_; }
+  ctrl_t* control() const { return common().control(); }
   slot_type* slot_array() const {
-    return static_cast<slot_type*>(common().slots_);
+    return static_cast<slot_type*>(common().slot_array());
   }
   HashtablezInfoHandle& infoz() { return common().infoz(); }
 
@@ -2565,16 +2767,16 @@ class raw_hash_set {
                            static_cast<slot_type*>(src));
   }
   // Note: dealloc_fn will only be used if we have a non-standard allocator.
-  static void dealloc_fn(void* set, const PolicyFunctions&, ctrl_t* ctrl,
-                         void* slot_mem, size_t n) {
-    auto* h = static_cast<raw_hash_set*>(set);
+  static void dealloc_fn(CommonFields& common, const PolicyFunctions&) {
+    auto* set = reinterpret_cast<raw_hash_set*>(&common);
 
     // Unpoison before returning the memory to the allocator.
-    SanitizerUnpoisonMemoryRegion(slot_mem, sizeof(slot_type) * n);
+    SanitizerUnpoisonMemoryRegion(common.slot_array(),
+                                  sizeof(slot_type) * common.capacity());
 
-    Deallocate<alignof(slot_type)>(
-        &h->alloc_ref(), ctrl,
-        AllocSize(n, sizeof(slot_type), alignof(slot_type)));
+    Deallocate<BackingArrayAlignment(alignof(slot_type))>(
+        &set->alloc_ref(), common.backing_array_start(),
+        common.alloc_size(sizeof(slot_type), alignof(slot_type)));
   }
 
   static const PolicyFunctions& GetPolicyFunctions() {
@@ -2680,6 +2882,5 @@ ABSL_NAMESPACE_END
 }  // namespace absl
 
 #undef ABSL_SWISSTABLE_ENABLE_GENERATIONS
-#undef ABSL_INTERNAL_ASSERT_IS_FULL
 
 #endif  // ABSL_CONTAINER_INTERNAL_RAW_HASH_SET_H_