Export of internal Abseil changes.

-- cd076f55c1fa600131f6dda392533dfe61679fc0 by Abseil Team <absl-team@google.com>: Internal change PiperOrigin-RevId: 224008762 -- e05f62b01286d51044ff86ec6ef565749b9faf82 by Abseil Team <absl-team@google.com>: Create a pow10() test helper function to compute guaranteed-precise double values of 10^x. Not all standard libraries ship bit-accurate pow() functions, causing tests to fail that rely on expected values generated by it. PiperOrigin-RevId: 223883762 -- fd88e5e3f7ab80f7f5df9fd1488cd58b4573be69 by Abseil Team <absl-team@google.com>: Remove some absl:: qualifications to work around inline namespace bugs on MSVC 2015. PiperOrigin-RevId: 223869642 -- 6276cfff969d596edd36a2bbaba65ee045808903 by Abseil Team <absl-team@google.com>: Update absl/memory/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223854224 -- 359de9afc7a34c975fd3e0cbc52afd96637d97bd by Chris Kennelly <ckennelly@google.com>: Mark spinlock_benchmark_common as alwayslink = 1. PiperOrigin-RevId: 223844536 -- 450cd8cbe2789a6d54ed1eb87170259bb334f8b9 by Abseil Team <absl-team@google.com>: Support .* (pointer-to-member dereference) expressions in demangle.cc. PiperOrigin-RevId: 223826797 -- 772ca92179c3634f3e31a80bbc272ed8022e3572 by Abseil Team <absl-team@google.com>: Fix misspellings in absl::variant comments and replace a ' with a `. PiperOrigin-RevId: 223807911 -- 35dcdc2fbf299d195658aac101887f6dcad1de2f by Abseil Team <absl-team@google.com>: Bug fix in CMakeLists.txt file (SRCS --> HDRS). The compressed_tuple header-only library is being defined with the SRCS parameter instead of the HDRS parameter and this has been observed to cause some builds on some platforms to attempt to create a static library from it which fails since there are no .cc sources. PiperOrigin-RevId: 223805367 -- 4a57a3d2045bb137c0c97958e45ce425190b8d3e by Chris Kennelly <ckennelly@google.com>: Add test that absl::make_unique value initializes memory. PiperOrigin-RevId: 223801819 -- dfe8289d7f4dcc6bb568a26aaf192a89e896bdfd by Chris Kennelly <ckennelly@google.com>: SpinLock: Use exchange to avoid missing wakeups. The default fast path for SpinLock::Unlock does not use an atomic. If the SpinLock becomes contended while we are unlocking between lockword_.load and lockword_.store, we will fail to wake up the new waiter. This can cause unexpected latency spikes. PiperOrigin-RevId: 223800369 -- 9b9d35df786482f0016f77dd31691eff81503d23 by Abseil Team <absl-team@google.com>: Update absl/hash/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223755819 -- c2014e2704b87e7cdce2d2a0287c7e2397752296 by Abseil Team <absl-team@google.com>: Update absl/debugging/CMakeLists.txt to use new functions i.e. absl_cc_(library|test) PiperOrigin-RevId: 223751986 -- d83a4e09126400e3fd80645cb03ee558f532271e by Derek Mauro <dmauro@google.com>: Cleanup synchronization benchmarks. PiperOrigin-RevId: 223589416 -- fad140b473586531b5b12843f942ec27dfcf5e93 by CJ Johnson <johnsoncj@google.com>: Makes unifies the order of forward_iterator and input_iterator overloads PiperOrigin-RevId: 223580660 -- 6cd7c96faa7cc5f79f574e35a1b13837ef187d05 by Abseil Team <absl-team@google.com>: Internal Change. PiperOrigin-RevId: 223561629 -- bd2e545356b0f548af0e3c14bb2f7f0e712e49d0 by Shaindel Schwartz <shaindel@google.com>: Remove misleading comments. try_emplace() does not exist for the hash_set containers. PiperOrigin-RevId: 223543089 -- 0cd380a53b587eb7aacc4003a4a3bbb6c78d7c10 by Derek Mauro <dmauro@google.com>: Internal change PiperOrigin-RevId: 223512551 -- 7156dfee599cb72e9adddfe0e6ae07a95ddf10bb by Greg Miller <jgm@google.com>: Fixes UB that would result from constructing, multiplying, or dividing a Duration with a double "NaN" value. This CL changes the absl::Duration *implementation* to return an InfiniteDuration value that has the same sign as the given NaN. PiperOrigin-RevId: 223407499 -- 196b7d18609958267951882baf7f9429e49bcafa by CJ Johnson <johnsoncj@google.com>: Addresses NVCC+MSVC compilation bug where `inlined_capacity()` was not considered valid in constexpr PiperOrigin-RevId: 223397718 GitOrigin-RevId: cd076f55c1fa600131f6dda392533dfe61679fc0 Change-Id: I5423ca6470f661a7c6f73aa8fee49990446f157f
fa5aad · Dec 4, 2018 · 44b0faf · 44b0faf
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Showing 30 changed files with 1,104 additions and 361 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -17,6 +17,12 @@
 # We require 3.0 for modern, target-based CMake.  We require 3.1 for the use of
 # CXX_STANDARD in our targets.
 cmake_minimum_required(VERSION 3.1)
+
+# Compiler id for Apple Clang is now AppleClang.
+if (POLICY CMP0025)
+  cmake_policy(SET CMP0025 NEW)
+endif()
+
 project(absl)
 
 list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/CMake)
@@ -68,6 +74,12 @@ set(CMAKE_CXX_FLAGS "${ABSL_STD_CXX_FLAG} ${CMAKE_CXX_FLAGS}")
 # -fexceptions
 set(ABSL_EXCEPTIONS_FLAG "${CMAKE_CXX_EXCEPTIONS}")
 
+if("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang")
+  set(ABSL_USING_CLANG ON)
+else()
+  set(ABSL_USING_CLANG OFF)
+endif()
+
 # find dependencies
 ## pthread
 find_package(Threads REQUIRED)

diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
@@ -107,6 +107,7 @@ cc_library(
         "internal/identity.h",
         "internal/inline_variable.h",
         "internal/invoke.h",
+        "internal/scheduling_mode.h",
     ],
     copts = ABSL_DEFAULT_COPTS,
     visibility = [
@@ -313,6 +314,33 @@ cc_test(
     ],
 )
 
+cc_library(
+    name = "spinlock_benchmark_common",
+    testonly = 1,
+    srcs = ["internal/spinlock_benchmark.cc"],
+    copts = ABSL_DEFAULT_COPTS,
+    visibility = [
+        "//absl/base:__pkg__",
+    ],
+    deps = [
+        ":base",
+        ":base_internal",
+        "//absl/synchronization",
+        "@com_github_google_benchmark//:benchmark_main",
+    ],
+    alwayslink = 1,
+)
+
+cc_binary(
+    name = "spinlock_benchmark",
+    testonly = 1,
+    copts = ABSL_DEFAULT_COPTS,
+    visibility = ["//visibility:private"],
+    deps = [
+        ":spinlock_benchmark_common",
+    ],
+)
+
 cc_library(
     name = "endian",
     hdrs = [

diff --git a/absl/base/internal/spinlock.h b/absl/base/internal/spinlock.h
@@ -101,8 +101,8 @@ class LOCKABLE SpinLock {
   inline void Unlock() UNLOCK_FUNCTION() {
     ABSL_TSAN_MUTEX_PRE_UNLOCK(this, 0);
     uint32_t lock_value = lockword_.load(std::memory_order_relaxed);
-    lockword_.store(lock_value & kSpinLockCooperative,
-                    std::memory_order_release);
+    lock_value = lockword_.exchange(lock_value & kSpinLockCooperative,
+                                    std::memory_order_release);
 
     if ((lock_value & kSpinLockDisabledScheduling) != 0) {
       base_internal::SchedulingGuard::EnableRescheduling(true);

diff --git a/absl/base/internal/spinlock_benchmark.cc b/absl/base/internal/spinlock_benchmark.cc
@@ -0,0 +1,52 @@
+// Copyright 2018 The Abseil Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// See also //absl/synchronization:mutex_benchmark for a comparison of SpinLock
+// and Mutex performance under varying levels of contention.
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/scheduling_mode.h"
+#include "absl/base/internal/spinlock.h"
+#include "absl/synchronization/internal/create_thread_identity.h"
+#include "benchmark/benchmark.h"
+
+namespace {
+
+template <absl::base_internal::SchedulingMode scheduling_mode>
+static void BM_SpinLock(benchmark::State& state) {
+  // Ensure a ThreadIdentity is installed.
+  ABSL_INTERNAL_CHECK(
+      absl::synchronization_internal::GetOrCreateCurrentThreadIdentity() !=
+          nullptr,
+      "GetOrCreateCurrentThreadIdentity() failed");
+
+  static auto* spinlock = new absl::base_internal::SpinLock(scheduling_mode);
+  for (auto _ : state) {
+    absl::base_internal::SpinLockHolder holder(spinlock);
+  }
+}
+
+BENCHMARK_TEMPLATE(BM_SpinLock,
+                   absl::base_internal::SCHEDULE_KERNEL_ONLY)
+    ->UseRealTime()
+    ->Threads(1)
+    ->ThreadPerCpu();
+
+BENCHMARK_TEMPLATE(BM_SpinLock,
+                   absl::base_internal::SCHEDULE_COOPERATIVE_AND_KERNEL)
+    ->UseRealTime()
+    ->Threads(1)
+    ->ThreadPerCpu();
+
+}  // namespace
diff --git a/absl/container/CMakeLists.txt b/absl/container/CMakeLists.txt
@@ -30,7 +30,7 @@ absl_cc_library(
 absl_cc_library(
   NAME
     compressed_tuple
-  SRCS
+  HDRS
    "internal/compressed_tuple.h"
   DEPS
     absl::utility

diff --git a/absl/container/flat_hash_set.h b/absl/container/flat_hash_set.h
@@ -279,8 +279,7 @@ class flat_hash_set
   //
   // The element may be constructed even if there already is an element with the
   // key in the container, in which case the newly constructed element will be
-  // destroyed immediately. Prefer `try_emplace()` unless your key is not
-  // copyable or moveable.
+  // destroyed immediately.
   //
   // If rehashing occurs due to the insertion, all iterators are invalidated.
   using Base::emplace;
@@ -294,8 +293,7 @@ class flat_hash_set
   //
   // The element may be constructed even if there already is an element with the
   // key in the container, in which case the newly constructed element will be
-  // destroyed immediately. Prefer `try_emplace()` unless your key is not
-  // copyable or moveable.
+  // destroyed immediately.
   //
   // If rehashing occurs due to the insertion, all iterators are invalidated.
   using Base::emplace_hint;

diff --git a/absl/container/inlined_vector.h b/absl/container/inlined_vector.h
@@ -66,12 +66,11 @@ namespace absl {
 // designed to cover the same API footprint as covered by `std::vector`.
 template <typename T, size_t N, typename A = std::allocator<T>>
 class InlinedVector {
+  static_assert(N > 0, "InlinedVector requires inline capacity greater than 0");
   constexpr static typename A::size_type inlined_capacity() {
     return static_cast<typename A::size_type>(N);
   }
 
-  static_assert(inlined_capacity() > 0, "InlinedVector needs inlined capacity");
-
   template <typename Iterator>
   using DisableIfIntegral =
       absl::enable_if_t<!std::is_integral<Iterator>::value>;
@@ -131,7 +130,8 @@ class InlinedVector {
   InlinedVector(std::initializer_list<value_type> init_list,
                 const allocator_type& alloc = allocator_type())
       : allocator_and_tag_(alloc) {
-    AppendRange(init_list.begin(), init_list.end());
+    AppendRange(init_list.begin(), init_list.end(),
+                IteratorCategory<decltype(init_list.begin())>{});
   }
 
   // Creates an inlined vector with elements constructed from the provided
@@ -144,7 +144,7 @@ class InlinedVector {
   InlinedVector(InputIterator first, InputIterator last,
                 const allocator_type& alloc = allocator_type())
       : allocator_and_tag_(alloc) {
-    AppendRange(first, last);
+    AppendRange(first, last, IteratorCategory<InputIterator>{});
   }
 
   // Creates a copy of `other` using `other`'s allocator.
@@ -366,7 +366,6 @@ class InlinedVector {
   // Returns a copy of the allocator of the inlined vector.
   allocator_type get_allocator() const { return allocator(); }
 
-
   // ---------------------------------------------------------------------------
   // InlinedVector Member Mutators
   // ---------------------------------------------------------------------------
@@ -376,7 +375,8 @@ class InlinedVector {
   // Replaces the contents of the inlined vector with copies of the elements in
   // the provided `std::initializer_list`.
   InlinedVector& operator=(std::initializer_list<value_type> init_list) {
-    AssignRange(init_list.begin(), init_list.end());
+    AssignRange(init_list.begin(), init_list.end(),
+                IteratorCategory<decltype(init_list.begin())>{});
     return *this;
   }
 
@@ -453,14 +453,15 @@ class InlinedVector {
   // inlined vector with copies of the values in the provided
   // `std::initializer_list`.
   void assign(std::initializer_list<value_type> init_list) {
-    AssignRange(init_list.begin(), init_list.end());
+    AssignRange(init_list.begin(), init_list.end(),
+                IteratorCategory<decltype(init_list.begin())>{});
   }
 
   // Overload of `InlinedVector::assign()` to replace the contents of the
   // inlined vector with values constructed from the range [`first`, `last`).
   template <typename InputIterator, DisableIfIntegral<InputIterator>* = nullptr>
   void assign(InputIterator first, InputIterator last) {
-    AssignRange(first, last);
+    AssignRange(first, last, IteratorCategory<InputIterator>{});
   }
 
   // `InlinedVector::resize()`
@@ -844,41 +845,29 @@ class InlinedVector {
   // Destroy [`from`, `to`) in place.
   void Destroy(pointer from, pointer to);
 
-  template <typename Iterator>
-  void AppendRange(Iterator first, Iterator last, std::input_iterator_tag) {
-    std::copy(first, last, std::back_inserter(*this));
-  }
-
   template <typename Iterator>
   void AppendRange(Iterator first, Iterator last, std::forward_iterator_tag);
 
   template <typename Iterator>
-  void AppendRange(Iterator first, Iterator last) {
-    AppendRange(first, last, IteratorCategory<Iterator>());
-  }
-
-  template <typename Iterator>
-  void AssignRange(Iterator first, Iterator last, std::input_iterator_tag);
+  void AppendRange(Iterator first, Iterator last, std::input_iterator_tag);
 
   template <typename Iterator>
   void AssignRange(Iterator first, Iterator last, std::forward_iterator_tag);
 
   template <typename Iterator>
-  void AssignRange(Iterator first, Iterator last) {
-    AssignRange(first, last, IteratorCategory<Iterator>());
-  }
+  void AssignRange(Iterator first, Iterator last, std::input_iterator_tag);
 
   iterator InsertWithCount(const_iterator position, size_type n,
                            const_reference v);
 
-  template <typename InputIterator>
-  iterator InsertWithRange(const_iterator position, InputIterator first,
-                           InputIterator last, std::input_iterator_tag);
-
   template <typename ForwardIterator>
   iterator InsertWithRange(const_iterator position, ForwardIterator first,
                            ForwardIterator last, std::forward_iterator_tag);
 
+  template <typename InputIterator>
+  iterator InsertWithRange(const_iterator position, InputIterator first,
+                           InputIterator last, std::input_iterator_tag);
+
   // Stores either the inlined or allocated representation
   union Rep {
     using ValueTypeBuffer =
@@ -889,7 +878,7 @@ class InlinedVector {
     // Structs wrap the buffers to perform indirection that solves a bizarre
     // compilation error on Visual Studio (all known versions).
     struct InlinedRep {
-      ValueTypeBuffer inlined[inlined_capacity()];
+      ValueTypeBuffer inlined[N];
     };
     struct AllocatedRep {
       AllocationBuffer allocation;
@@ -1364,15 +1353,8 @@ void InlinedVector<T, N, A>::AppendRange(Iterator first, Iterator last,
 
 template <typename T, size_t N, typename A>
 template <typename Iterator>
-void InlinedVector<T, N, A>::AssignRange(Iterator first, Iterator last,
+void InlinedVector<T, N, A>::AppendRange(Iterator first, Iterator last,
                                          std::input_iterator_tag) {
-  // Optimized to avoid reallocation.
-  // Prefer reassignment to copy construction for elements.
-  iterator out = begin();
-  for (; first != last && out != end(); ++first, ++out) {
-    *out = *first;
-  }
-  erase(out, end());
   std::copy(first, last, std::back_inserter(*this));
 }
 
@@ -1398,6 +1380,20 @@ void InlinedVector<T, N, A>::AssignRange(Iterator first, Iterator last,
   }
 }
 
+template <typename T, size_t N, typename A>
+template <typename Iterator>
+void InlinedVector<T, N, A>::AssignRange(Iterator first, Iterator last,
+                                         std::input_iterator_tag) {
+  // Optimized to avoid reallocation.
+  // Prefer reassignment to copy construction for elements.
+  iterator out = begin();
+  for (; first != last && out != end(); ++first, ++out) {
+    *out = *first;
+  }
+  erase(out, end());
+  std::copy(first, last, std::back_inserter(*this));
+}
+
 template <typename T, size_t N, typename A>
 auto InlinedVector<T, N, A>::InsertWithCount(const_iterator position,
                                              size_type n, const_reference v)
@@ -1413,20 +1409,6 @@ auto InlinedVector<T, N, A>::InsertWithCount(const_iterator position,
   return it_pair.first;
 }
 
-template <typename T, size_t N, typename A>
-template <typename InputIterator>
-auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
-                                             InputIterator first,
-                                             InputIterator last,
-                                             std::input_iterator_tag)
-    -> iterator {
-  assert(position >= begin() && position <= end());
-  size_type index = position - cbegin();
-  size_type i = index;
-  while (first != last) insert(begin() + i++, *first++);
-  return begin() + index;
-}
-
 template <typename T, size_t N, typename A>
 template <typename ForwardIterator>
 auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
@@ -1446,6 +1428,20 @@ auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
   return it_pair.first;
 }
 
+template <typename T, size_t N, typename A>
+template <typename InputIterator>
+auto InlinedVector<T, N, A>::InsertWithRange(const_iterator position,
+                                             InputIterator first,
+                                             InputIterator last,
+                                             std::input_iterator_tag)
+    -> iterator {
+  assert(position >= begin() && position <= end());
+  size_type index = position - cbegin();
+  size_type i = index;
+  while (first != last) insert(begin() + i++, *first++);
+  return begin() + index;
+}
+
 }  // namespace absl
 
 #endif  // ABSL_CONTAINER_INLINED_VECTOR_H_
diff --git a/absl/container/internal/layout.h b/absl/container/internal/layout.h
@@ -253,8 +253,10 @@ template <class From, class To>
 using CopyConst =
     typename std::conditional<std::is_const<From>::value, const To, To>::type;
 
+// Note: We're not qualifying this with absl:: because it doesn't compile under
+// MSVC.
 template <class T>
-using SliceType = absl::Span<T>;
+using SliceType = Span<T>;
 
 // This namespace contains no types. It prevents functions defined in it from
 // being found by ADL.

diff --git a/absl/container/internal/raw_hash_set.cc b/absl/container/internal/raw_hash_set.cc
@@ -14,6 +14,7 @@
 
 #include "absl/container/internal/raw_hash_set.h"
 
+#include <atomic>
 #include <cstddef>
 
 #include "absl/base/config.h"
@@ -29,7 +30,7 @@ inline size_t RandomSeed() {
   static thread_local size_t counter = 0;
   size_t value = ++counter;
 #else   // ABSL_HAVE_THREAD_LOCAL
-  static std::atomic<size_t> counter;
+  static std::atomic<size_t> counter(0);
   size_t value = counter.fetch_add(1, std::memory_order_relaxed);
 #endif  // ABSL_HAVE_THREAD_LOCAL
   return value ^ static_cast<size_t>(reinterpret_cast<uintptr_t>(&counter));