Export of internal Abseil changes

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228b5878d7a994656f383666cfaee34e33e0b09b by Abseil Team <absl-team@google.com>:

Add element_type typedef to match std::span<T>

PiperOrigin-RevId: 390186160

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c91d96c88c60be793c525158f76dfcaa5e32d161 by Abseil Team <absl-team@google.com>:

Rollback change to only hide retired flags if human-readable output
is requested

PiperOrigin-RevId: 390183146

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170192c10ef8d513de80f29298ce93eeccc3712c by Abseil Team <absl-team@google.com>:

Move alignas(16) before ABSL_CONST_INIT and ABSL_DLL.

PiperOrigin-RevId: 390182845

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77a5ee5081c81cef625fac7bbcf993cc028b32ed by Evan Brown <ezb@google.com>:

Use simple SlotOffset and AllocSize logic instead of container_internal::Layout in order to save linker input size for non-opt and sanitizer builds.

In opt mode, all of this logic is inlined so we don't save linker input size in opt mode.

PiperOrigin-RevId: 389914594
GitOrigin-RevId: 228b5878d7a994656f383666cfaee34e33e0b09b
Change-Id: I3b904068687574931d8390071b322c0c3c083283

absl/container/BUILD.bazel

@@ -598,7 +598,6 @@ cc_library(
         ":hashtable_debug_hooks",
         ":hashtablez_sampler",
         ":have_sse",
-        ":layout",
         "//absl/base:config",
         "//absl/base:core_headers",
         "//absl/base:endian",

absl/container/CMakeLists.txt

@@ -666,7 +666,6 @@ absl_cc_library(
     absl::hash_policy_traits
     absl::hashtable_debug_hooks
     absl::have_sse
-    absl::layout
     absl::memory
     absl::meta
     absl::optional

absl/container/internal/raw_hash_set.cc

@@ -23,7 +23,7 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace container_internal {
 
-ABSL_CONST_INIT ABSL_DLL alignas(16) const ctrl_t kEmptyGroup[16] = {
+alignas(16) ABSL_CONST_INIT ABSL_DLL const ctrl_t kEmptyGroup[16] = {
     ctrl_t::kSentinel, ctrl_t::kEmpty, ctrl_t::kEmpty, ctrl_t::kEmpty,
     ctrl_t::kEmpty,    ctrl_t::kEmpty, ctrl_t::kEmpty, ctrl_t::kEmpty,
     ctrl_t::kEmpty,    ctrl_t::kEmpty, ctrl_t::kEmpty, ctrl_t::kEmpty,

absl/container/internal/raw_hash_set.h

@@ -112,7 +112,6 @@
 #include "absl/container/internal/hashtable_debug_hooks.h"
 #include "absl/container/internal/hashtablez_sampler.h"
 #include "absl/container/internal/have_sse.h"
-#include "absl/container/internal/layout.h"
 #include "absl/memory/memory.h"
 #include "absl/meta/type_traits.h"
 #include "absl/numeric/bits.h"
@@ -625,6 +624,20 @@ inline void SetCtrl(size_t i, h2_t h, size_t capacity, ctrl_t* ctrl,
   SetCtrl(i, static_cast<ctrl_t>(h), capacity, ctrl, slot, slot_size);
 }
 
+// The allocated block consists of `capacity + 1 + NumClonedBytes()` control
+// bytes followed by `capacity` slots, which must be aligned to `slot_align`.
+// SlotOffset returns the offset of the slots into the allocated block.
+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 + slot_align - 1) & (~slot_align + 1);
+}
+
+// Returns the size of the allocated block. See also above comment.
+inline size_t AllocSize(size_t capacity, size_t slot_size, size_t slot_align) {
+  return SlotOffset(capacity, slot_align) + capacity * slot_size;
+}
+
 // Policy: a policy defines how to perform different operations on
 // the slots of the hashtable (see hash_policy_traits.h for the full interface
 // of policy).
@@ -681,15 +694,6 @@ class raw_hash_set {
   auto KeyTypeCanBeHashed(const Hash& h, const key_type& k) -> decltype(h(k));
   auto KeyTypeCanBeEq(const Eq& eq, const key_type& k) -> decltype(eq(k, k));
 
-  using Layout = absl::container_internal::Layout<ctrl_t, slot_type>;
-
-  static Layout MakeLayout(size_t capacity) {
-    assert(IsValidCapacity(capacity));
-    // The extra control bytes are for 1 sentinel byte followed by
-    // NumClonedBytes() bytes that are cloned from the beginning.
-    return Layout(capacity + 1 + NumClonedBytes(), capacity);
-  }
-
   using AllocTraits = absl::allocator_traits<allocator_type>;
   using SlotAlloc = typename absl::allocator_traits<
       allocator_type>::template rebind_alloc<slot_type>;
@@ -1610,11 +1614,12 @@ class raw_hash_set {
       infoz() = Sample();
     }
 
-    auto layout = MakeLayout(capacity_);
-    char* mem = static_cast<char*>(
-        Allocate<Layout::Alignment()>(&alloc_ref(), layout.AllocSize()));
-    ctrl_ = layout.template Pointer<0>(mem);
-    slots_ = layout.template Pointer<1>(mem);
+    char* mem = static_cast<char*>(Allocate<alignof(slot_type)>(
+        &alloc_ref(),
+        AllocSize(capacity_, sizeof(slot_type), alignof(slot_type))));
+    ctrl_ = reinterpret_cast<ctrl_t*>(mem);
+    slots_ = reinterpret_cast<slot_type*>(
+        mem + SlotOffset(capacity_, alignof(slot_type)));
     ResetCtrl(capacity_, ctrl_, slots_, sizeof(slot_type));
     reset_growth_left();
     infoz().RecordStorageChanged(size_, capacity_);
@@ -1627,10 +1632,11 @@ class raw_hash_set {
         PolicyTraits::destroy(&alloc_ref(), slots_ + i);
       }
     }
-    auto layout = MakeLayout(capacity_);
     // Unpoison before returning the memory to the allocator.
     SanitizerUnpoisonMemoryRegion(slots_, sizeof(slot_type) * capacity_);
-    Deallocate<Layout::Alignment()>(&alloc_ref(), ctrl_, layout.AllocSize());
+    Deallocate<alignof(slot_type)>(
+        &alloc_ref(), ctrl_,
+        AllocSize(capacity_, sizeof(slot_type), alignof(slot_type)));
     ctrl_ = EmptyGroup();
     slots_ = nullptr;
     size_ = 0;
@@ -1661,9 +1667,9 @@ class raw_hash_set {
     if (old_capacity) {
       SanitizerUnpoisonMemoryRegion(old_slots,
                                     sizeof(slot_type) * old_capacity);
-      auto layout = MakeLayout(old_capacity);
-      Deallocate<Layout::Alignment()>(&alloc_ref(), old_ctrl,
-                                      layout.AllocSize());
+      Deallocate<alignof(slot_type)>(
+          &alloc_ref(), old_ctrl,
+          AllocSize(old_capacity, sizeof(slot_type), alignof(slot_type)));
     }
     infoz().RecordRehash(total_probe_length);
   }
@@ -1948,8 +1954,7 @@ struct HashtableDebugAccess<Set, absl::void_t<typename Set::raw_hash_set>> {
   static size_t AllocatedByteSize(const Set& c) {
     size_t capacity = c.capacity_;
     if (capacity == 0) return 0;
-    auto layout = Set::MakeLayout(capacity);
-    size_t m = layout.AllocSize();
+    size_t m = AllocSize(capacity, sizeof(Slot), alignof(Slot));
 
     size_t per_slot = Traits::space_used(static_cast<const Slot*>(nullptr));
     if (per_slot != ~size_t{}) {
@@ -1967,8 +1972,8 @@ struct HashtableDebugAccess<Set, absl::void_t<typename Set::raw_hash_set>> {
   static size_t LowerBoundAllocatedByteSize(size_t size) {
     size_t capacity = GrowthToLowerboundCapacity(size);
     if (capacity == 0) return 0;
-    auto layout = Set::MakeLayout(NormalizeCapacity(capacity));
-    size_t m = layout.AllocSize();
+    size_t m =
+        AllocSize(NormalizeCapacity(capacity), sizeof(Slot), alignof(Slot));
     size_t per_slot = Traits::space_used(static_cast<const Slot*>(nullptr));
     if (per_slot != ~size_t{}) {
       m += per_slot * size;

absl/flags/internal/usage.cc

@@ -17,7 +17,6 @@
 
 #include <stdint.h>
 
-#include <algorithm>
 #include <functional>
 #include <map>
 #include <ostream>
@@ -256,6 +255,9 @@ void FlagsHelpImpl(std::ostream& out, PerFlagFilter filter_cb,
       matching_flags;
 
   flags_internal::ForEachFlag([&](absl::CommandLineFlag& flag) {
+    // Ignore retired flags.
+    if (flag.IsRetired()) return;
+
     // If the flag has been stripped, pretend that it doesn't exist.
     if (flag.Help() == flags_internal::kStrippedFlagHelp) return;
 
@@ -273,14 +275,6 @@ void FlagsHelpImpl(std::ostream& out, PerFlagFilter filter_cb,
   absl::string_view file_separator;     // controls blank lines between files
   for (auto& package : matching_flags) {
     if (format == HelpFormat::kHumanReadable) {
-      // Hide packages with only retired flags
-      bool all_package_flags_are_retired = true;
-      for (const auto& flags_in_file : package.second) {
-        for (const auto* flag : flags_in_file.second) {
-          all_package_flags_are_retired &= flag->IsRetired();
-        }
-      }
-      if (all_package_flags_are_retired) continue;
       out << package_separator;
       package_separator = "\n\n";
     }
@@ -340,11 +334,8 @@ void FlagsHelpImpl(std::ostream& out,
 // Produces the help message describing specific flag.
 void FlagHelp(std::ostream& out, const CommandLineFlag& flag,
               HelpFormat format) {
-  if (format == HelpFormat::kHumanReadable) {
-    // Ignore retired flags
-    if (flag.IsRetired()) return;
+  if (format == HelpFormat::kHumanReadable)
     flags_internal::FlagHelpHumanReadable(flag, out);
-  }
 }
 
 // --------------------------------------------------------------------

absl/flags/internal/usage_test.cc

@@ -61,9 +61,6 @@ ABSL_FLAG(
     "Even more long long long long long long long long long long long long "
     "help message.");
 
-ABSL_RETIRED_FLAG(int64_t, usage_reporting_test_flag_07, 1,
-                  "usage_reporting_test_flag_07 help message");
-
 namespace {
 
 namespace flags = absl::flags_internal;

absl/types/span.h

@@ -40,7 +40,6 @@
 //    * `absl::Span` has compiler-provided move and copy constructors and
 //      assignment. This is due to them being specified as `constexpr`, but that
 //      implies const in C++11.
-//    * `absl::Span` has no `element_type` typedef
 //    * A read-only `absl::Span<const T>` can be implicitly constructed from an
 //      initializer list.
 //    * `absl::Span` has no `bytes()`, `size_bytes()`, `as_bytes()`, or
@@ -170,6 +169,7 @@ class Span {
       typename std::enable_if<!std::is_const<T>::value, U>::type;
 
  public:
+  using element_type = T;
   using value_type = absl::remove_cv_t<T>;
   using pointer = T*;
   using const_pointer = const T*;

absl/types/span_test.cc

@@ -661,6 +661,8 @@ TEST(IntSpan, ExposesContainerTypesAndConsts) {
   CheckType<absl::Span<int>::const_reverse_iterator>(slice.crend());
   testing::StaticAssertTypeEq<int, absl::Span<int>::value_type>();
   testing::StaticAssertTypeEq<int, absl::Span<const int>::value_type>();
+  testing::StaticAssertTypeEq<int, absl::Span<int>::element_type>();
+  testing::StaticAssertTypeEq<const int, absl::Span<const int>::element_type>();
   testing::StaticAssertTypeEq<int*, absl::Span<int>::pointer>();
   testing::StaticAssertTypeEq<const int*, absl::Span<const int>::pointer>();
   testing::StaticAssertTypeEq<int&, absl::Span<int>::reference>();