Export of internal Abseil changes

--
77c85460dc3c46593b231c5161ac55273bb0c7ef by Abseil Team <absl-team@google.com>:

Support int128 in SimpleAtoi.

PiperOrigin-RevId: 337946262

--
0be53049ccf8309650e4e22f23b290e5f75ee828 by Gennadiy Rozental <rogeeff@google.com>:

Update build scripts to use --mount instead of --volume to mount the host data into a container.

This is somewhat more verbose, but more readable and flexible. More importantly this is what docker documentation is recomending to use now.

PiperOrigin-RevId: 337898761

--
3bc877f1679fdf61ecbf4365287a0403cfc9b53e by Samuel Benzaquen <sbenza@google.com>:

Add Cord constructor for constinit instances.

PiperOrigin-RevId: 337871148

--
8b87701892b9c325e78ad4e8e4f16b785a744622 by Chris Kennelly <ckennelly@google.com>:

Use the address of kSeed, rather than its value.

We initialize kSeed with &kSeed, so these are equivalent, but kSeed requires a
load from memory while &kSeed can be formed as a RIP-relative lea.

PiperOrigin-RevId: 337868415
GitOrigin-RevId: 77c85460dc3c46593b231c5161ac55273bb0c7ef
Change-Id: I3d06c18a123f1be29dad5801e8625952dc41cd95

11 files changed, 538 insertions, 15 deletions

diff --git a/absl/strings/BUILD.bazel b/absl/strings/BUILD.bazel
index 64a13cef..30a8dd28 100644
--- a/absl/strings/BUILD.bazel
+++ b/absl/strings/BUILD.bazel
@@ -54,6 +54,7 @@ cc_library(
         "ascii.h",
         "charconv.h",
         "escaping.h",
+        "internal/string_constant.h",
         "match.h",
         "numbers.h",
         "str_cat.h",
@@ -223,6 +224,19 @@ cc_test(
 )
 
 cc_test(
+    name = "string_constant_test",
+    size = "small",
+    srcs = ["internal/string_constant_test.cc"],
+    copts = ABSL_TEST_COPTS,
+    visibility = ["//visibility:private"],
+    deps = [
+        ":strings",
+        "//absl/meta:type_traits",
+        "@com_google_googletest//:gtest_main",
+    ],
+)
+
+cc_test(
     name = "string_view_benchmark",
     srcs = ["string_view_benchmark.cc"],
     copts = ABSL_TEST_COPTS,
diff --git a/absl/strings/CMakeLists.txt b/absl/strings/CMakeLists.txt
index d6c2126d..2b994a71 100644
--- a/absl/strings/CMakeLists.txt
+++ b/absl/strings/CMakeLists.txt
@@ -21,6 +21,7 @@ absl_cc_library(
     "ascii.h"
     "charconv.h"
     "escaping.h"
+    "internal/string_constant.h"
     "match.h"
     "numbers.h"
     "str_cat.h"
@@ -160,6 +161,19 @@ absl_cc_test(
 
 absl_cc_test(
   NAME
+    string_constant_test
+  SRCS
+    "internal/string_constant_test.cc"
+  COPTS
+    ${ABSL_TEST_COPTS}
+  DEPS
+    absl::strings
+    absl::type_traits
+    gmock_main
+)
+
+absl_cc_test(
+  NAME
     string_view_test
   SRCS
     "string_view_test.cc"
diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 5092fd14..9efd1357 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -241,6 +241,7 @@ static void UnrefInternal(CordRep* rep) {
 
   absl::InlinedVector<CordRep*, kInlinedVectorSize> pending;
   while (true) {
+    assert(!rep->refcount.IsImmortal());
     if (rep->tag == CONCAT) {
       CordRepConcat* rep_concat = rep->concat();
       CordRep* right = rep_concat->right;
@@ -256,6 +257,7 @@ static void UnrefInternal(CordRep* rep) {
       }
     } else if (rep->tag == EXTERNAL) {
       CordRepExternal* rep_external = rep->external();
+      assert(rep_external->releaser_invoker != nullptr);
       rep_external->releaser_invoker(rep_external);
       rep = nullptr;
     } else if (rep->tag == SUBSTRING) {
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 653a1181..5d5c897e 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -79,6 +79,7 @@
 #include "absl/meta/type_traits.h"
 #include "absl/strings/internal/cord_internal.h"
 #include "absl/strings/internal/resize_uninitialized.h"
+#include "absl/strings/internal/string_constant.h"
 #include "absl/strings/string_view.h"
 #include "absl/types/optional.h"
 
@@ -624,6 +625,14 @@ class Cord {
     return c.HashFragmented(std::move(hash_state));
   }
 
+  // Create a Cord with the contents of StringConstant<T>::value.
+  // No allocations will be done and no data will be copied.
+  // This is an INTERNAL API and subject to change or removal. This API can only
+  // be used by spelling absl::strings_internal::MakeStringConstant, which is
+  // also an internal API.
+  template <typename T>
+  explicit constexpr Cord(strings_internal::StringConstant<T>);
+
  private:
   friend class CordTestPeer;
   friend bool operator==(const Cord& lhs, const Cord& rhs);
@@ -655,6 +664,8 @@ class Cord {
     InlineRep& operator=(const InlineRep& src);
     InlineRep& operator=(InlineRep&& src) noexcept;
 
+    explicit constexpr InlineRep(cord_internal::InlineData data);
+
     void Swap(InlineRep* rhs);
     bool empty() const;
     size_t size() const;
@@ -884,6 +895,9 @@ Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser) {
   return cord;
 }
 
+constexpr Cord::InlineRep::InlineRep(cord_internal::InlineData data)
+    : data_(data) {}
+
 inline Cord::InlineRep::InlineRep(const Cord::InlineRep& src) {
   data_ = src.data_;
 }
@@ -981,6 +995,18 @@ inline void Cord::InlineRep::CopyToArray(char* dst) const {
 
 constexpr inline Cord::Cord() noexcept {}
 
+template <typename T>
+constexpr Cord::Cord(strings_internal::StringConstant<T>)
+    : contents_(strings_internal::StringConstant<T>::value.size() <=
+                        cord_internal::kMaxInline
+                    ? cord_internal::InlineData(
+                          strings_internal::StringConstant<T>::value)
+                    : cord_internal::InlineData(cord_internal::AsTree{
+                          &cord_internal::ConstInitExternalStorage<
+                              strings_internal::StringConstant<T>>::value,
+                          {},
+                          cord_internal::kTreeFlag})) {}
+
 inline Cord& Cord::operator=(const Cord& x) {
   contents_ = x.contents_;
   return *this;
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index dbed3e9a..7942bfc0 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -181,6 +181,8 @@ class CordTestPeer {
       const Cord& c, absl::FunctionRef<void(absl::string_view)> callback) {
     c.ForEachChunk(callback);
   }
+
+  static bool IsTree(const Cord& c) { return c.contents_.is_tree(); }
 };
 
 ABSL_NAMESPACE_END
@@ -1627,3 +1629,83 @@ TEST(CordDeathTest, Hardening) {
   EXPECT_DEATH_IF_SUPPORTED(static_cast<void>(cord.chunk_end()->empty()), "");
   EXPECT_DEATH_IF_SUPPORTED(++cord.chunk_end(), "");
 }
+
+class AfterExitCordTester {
+ public:
+  bool Set(absl::Cord* cord, absl::string_view expected) {
+    cord_ = cord;
+    expected_ = expected;
+    return true;
+  }
+
+  ~AfterExitCordTester() {
+    EXPECT_EQ(*cord_, expected_);
+  }
+ private:
+  absl::Cord* cord_;
+  absl::string_view expected_;
+};
+
+template <typename Str>
+void TestConstinitConstructor(Str) {
+  const auto expected = Str::value;
+  // Defined before `cord` to be destroyed after it.
+  static AfterExitCordTester exit_tester;  // NOLINT
+  ABSL_CONST_INIT static absl::Cord cord(Str{});  // NOLINT
+  static bool init_exit_tester = exit_tester.Set(&cord, expected);
+  (void)init_exit_tester;
+
+  EXPECT_EQ(cord, expected);
+  // Copy the object and test the copy, and the original.
+  {
+    absl::Cord copy = cord;
+    EXPECT_EQ(copy, expected);
+  }
+  // The original still works
+  EXPECT_EQ(cord, expected);
+
+  // Try making adding more structure to the tree.
+  {
+    absl::Cord copy = cord;
+    std::string expected_copy(expected);
+    for (int i = 0; i < 10; ++i) {
+      copy.Append(cord);
+      absl::StrAppend(&expected_copy, expected);
+      EXPECT_EQ(copy, expected_copy);
+    }
+  }
+
+  // Make sure we are using the right branch during constant evaluation.
+  EXPECT_EQ(absl::CordTestPeer::IsTree(cord), cord.size() >= 16);
+
+  for (int i = 0; i < 10; ++i) {
+    // Make a few more Cords from the same global rep.
+    // This tests what happens when the refcount for it gets below 1.
+    EXPECT_EQ(expected, absl::Cord(Str{}));
+  }
+}
+
+constexpr int SimpleStrlen(const char* p) {
+  return *p ? 1 + SimpleStrlen(p + 1) : 0;
+}
+
+struct ShortView {
+  constexpr absl::string_view operator()() const {
+    return absl::string_view("SSO string", SimpleStrlen("SSO string"));
+  }
+};
+
+struct LongView {
+  constexpr absl::string_view operator()() const {
+    return absl::string_view("String that does not fit SSO.",
+                             SimpleStrlen("String that does not fit SSO."));
+  }
+};
+
+
+TEST(Cord, ConstinitConstructor) {
+  TestConstinitConstructor(
+      absl::strings_internal::MakeStringConstant(ShortView{}));
+  TestConstinitConstructor(
+      absl::strings_internal::MakeStringConstant(LongView{}));
+}
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index 00b9baa9..aa91a691 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -33,14 +33,17 @@ namespace cord_internal {
 // Wraps std::atomic for reference counting.
 class Refcount {
  public:
-  Refcount() : count_{1} {}
-  ~Refcount() {}
+  constexpr Refcount() : count_{kRefIncrement} {}
+  struct Immortal {};
+  explicit constexpr Refcount(Immortal) : count_(kImmortalTag) {}
 
-  // Increments the reference count by 1. Imposes no memory ordering.
-  inline void Increment() { count_.fetch_add(1, std::memory_order_relaxed); }
+  // Increments the reference count. Imposes no memory ordering.
+  inline void Increment() {
+    count_.fetch_add(kRefIncrement, std::memory_order_relaxed);
+  }
 
   // Asserts that the current refcount is greater than 0. If the refcount is
-  // greater than 1, decrements the reference count by 1.
+  // greater than 1, decrements the reference count.
   //
   // Returns false if there are no references outstanding; true otherwise.
   // Inserts barriers to ensure that state written before this method returns
@@ -48,19 +51,24 @@ class Refcount {
   // false.
   inline bool Decrement() {
     int32_t refcount = count_.load(std::memory_order_acquire);
-    assert(refcount > 0);
-    return refcount != 1 && count_.fetch_sub(1, std::memory_order_acq_rel) != 1;
+    assert(refcount > 0 || refcount & kImmortalTag);
+    return refcount != kRefIncrement &&
+           count_.fetch_sub(kRefIncrement, std::memory_order_acq_rel) !=
+               kRefIncrement;
   }
 
   // Same as Decrement but expect that refcount is greater than 1.
   inline bool DecrementExpectHighRefcount() {
-    int32_t refcount = count_.fetch_sub(1, std::memory_order_acq_rel);
-    assert(refcount > 0);
-    return refcount != 1;
+    int32_t refcount =
+        count_.fetch_sub(kRefIncrement, std::memory_order_acq_rel);
+    assert(refcount > 0 || refcount & kImmortalTag);
+    return refcount != kRefIncrement;
   }
 
   // Returns the current reference count using acquire semantics.
-  inline int32_t Get() const { return count_.load(std::memory_order_acquire); }
+  inline int32_t Get() const {
+    return count_.load(std::memory_order_acquire) >> kImmortalShift;
+  }
 
   // Returns whether the atomic integer is 1.
   // If the reference count is used in the conventional way, a
@@ -70,9 +78,27 @@ class Refcount {
   // performs the memory barrier needed for the owning thread
   // to act on the object, knowing that it has exclusive access to the
   // object.
-  inline bool IsOne() { return count_.load(std::memory_order_acquire) == 1; }
+  inline bool IsOne() {
+    return count_.load(std::memory_order_acquire) == kRefIncrement;
+  }
+
+  bool IsImmortal() const {
+    return (count_.load(std::memory_order_relaxed) & kImmortalTag) != 0;
+  }
 
  private:
+  // We reserve the bottom bit to tag a reference count as immortal.
+  // By making it `1` we ensure that we never reach `0` when adding/subtracting
+  // `2`, thus it never looks as if it should be destroyed.
+  // These are used for the StringConstant constructor where we do not increase
+  // the refcount at construction time (due to constinit requirements) but we
+  // will still decrease it at destruction time to avoid branching on Unref.
+  enum {
+    kImmortalShift = 1,
+    kRefIncrement = 1 << kImmortalShift,
+    kImmortalTag = kRefIncrement - 1
+  };
+
   std::atomic<int32_t> count_;
 };
 
@@ -97,6 +123,10 @@ enum CordRepKind {
 };
 
 struct CordRep {
+  CordRep() = default;
+  constexpr CordRep(Refcount::Immortal immortal, size_t l)
+      : length(l), refcount(immortal), tag(EXTERNAL), data{} {}
+
   // The following three fields have to be less than 32 bytes since
   // that is the smallest supported flat node size.
   size_t length;
@@ -135,6 +165,12 @@ using ExternalReleaserInvoker = void (*)(CordRepExternal*);
 // External CordReps are allocated together with a type erased releaser. The
 // releaser is stored in the memory directly following the CordRepExternal.
 struct CordRepExternal : public CordRep {
+  CordRepExternal() = default;
+  explicit constexpr CordRepExternal(absl::string_view str)
+      : CordRep(Refcount::Immortal{}, str.size()),
+        base(str.data()),
+        releaser_invoker(nullptr) {}
+
   const char* base;
   // Pointer to function that knows how to call and destroy the releaser.
   ExternalReleaserInvoker releaser_invoker;
@@ -178,6 +214,14 @@ struct CordRepExternalImpl
   }
 };
 
+template <typename Str>
+struct ConstInitExternalStorage {
+  ABSL_CONST_INIT static CordRepExternal value;
+};
+
+template <typename Str>
+CordRepExternal ConstInitExternalStorage<Str>::value(Str::value);
+
 enum {
   kMaxInline = 15,
   // Tag byte & kMaxInline means we are storing a pointer.
@@ -195,9 +239,23 @@ struct AsTree {
   char padding[kMaxInline + 1 - sizeof(absl::cord_internal::CordRep*) - 1];
   char tagged_size;
 };
+
+constexpr char GetOrNull(absl::string_view data, size_t pos) {
+  return pos < data.size() ? data[pos] : '\0';
+}
+
 union InlineData {
   constexpr InlineData() : as_chars{} {}
   explicit constexpr InlineData(AsTree tree) : as_tree(tree) {}
+  explicit constexpr InlineData(absl::string_view chars)
+      : as_chars{GetOrNull(chars, 0),  GetOrNull(chars, 1),
+                 GetOrNull(chars, 2),  GetOrNull(chars, 3),
+                 GetOrNull(chars, 4),  GetOrNull(chars, 5),
+                 GetOrNull(chars, 6),  GetOrNull(chars, 7),
+                 GetOrNull(chars, 8),  GetOrNull(chars, 9),
+                 GetOrNull(chars, 10), GetOrNull(chars, 11),
+                 GetOrNull(chars, 12), GetOrNull(chars, 13),
+                 GetOrNull(chars, 14), static_cast<char>(chars.size())} {}
 
   AsTree as_tree;
   char as_chars[kMaxInline + 1];
diff --git a/absl/strings/internal/string_constant.h b/absl/strings/internal/string_constant.h
new file mode 100644
index 00000000..b15f1d9b
--- /dev/null
+++ b/absl/strings/internal/string_constant.h
@@ -0,0 +1,70 @@
+// Copyright 2020 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
+//
+//      https://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.
+
+#ifndef ABSL_STRINGS_INTERNAL_STRING_CONSTANT_H_
+#define ABSL_STRINGS_INTERNAL_STRING_CONSTANT_H_
+
+#include "absl/meta/type_traits.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace strings_internal {
+
+// StringConstant<T> represents a compile time string constant.
+// It can be accessed via its `absl::string_view value` static member.
+// It is guaranteed that the `string_view` returned has constant `.data()`,
+// constant `.size()` and constant `value[i]` for all `0 <= i < .size()`
+//
+// The `T` is an opaque type. It is guaranteed that different string constants
+// will have different values of `T`. This allows users to associate the string
+// constant with other static state at compile time.
+//
+// Instances should be made using the `MakeStringConstant()` factory function
+// below.
+template <typename T>
+struct StringConstant {
+ private:
+  // Returns true if `view` points to constant data.
+  // Otherwise, it can't be constant evaluated.
+  static constexpr bool ValidateConstant(absl::string_view view) {
+    return view.empty() || 2 * view[0] != 1;
+  }
+
+ public:
+  static constexpr absl::string_view value = T{}();
+  constexpr absl::string_view operator()() const { return value; }
+
+  static_assert(ValidateConstant(value),
+                "The input string_view must point to constant data.");
+};
+
+template <typename T>
+constexpr absl::string_view StringConstant<T>::value;  // NOLINT
+
+// Factory function for `StringConstant` instances.
+// It supports callables that have a constexpr default constructor and a
+// constexpr operator().
+// It must return an `absl::string_view` or `const char*` pointing to constant
+// data. This is validated at compile time.
+template <typename T>
+constexpr StringConstant<T> MakeStringConstant(T) {
+  return {};
+}
+
+}  // namespace strings_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+#endif  // ABSL_STRINGS_INTERNAL_STRING_CONSTANT_H_
diff --git a/absl/strings/internal/string_constant_test.cc b/absl/strings/internal/string_constant_test.cc
new file mode 100644
index 00000000..392833cf
--- /dev/null
+++ b/absl/strings/internal/string_constant_test.cc
@@ -0,0 +1,60 @@
+// Copyright 2020 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
+//
+//      https://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.
+
+#include "absl/strings/internal/string_constant.h"
+
+#include "absl/meta/type_traits.h"
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+namespace {
+
+using absl::strings_internal::MakeStringConstant;
+
+struct Callable {
+  constexpr absl::string_view operator()() const {
+    return absl::string_view("Callable", 8);
+  }
+};
+
+TEST(StringConstant, Traits) {
+  constexpr auto str = MakeStringConstant(Callable{});
+  using T = decltype(str);
+
+  EXPECT_TRUE(std::is_empty<T>::value);
+  EXPECT_TRUE(std::is_trivial<T>::value);
+  EXPECT_TRUE(absl::is_trivially_default_constructible<T>::value);
+  EXPECT_TRUE(absl::is_trivially_copy_constructible<T>::value);
+  EXPECT_TRUE(absl::is_trivially_move_constructible<T>::value);
+  EXPECT_TRUE(absl::is_trivially_destructible<T>::value);
+}
+
+TEST(StringConstant, MakeFromCallable) {
+  constexpr auto str = MakeStringConstant(Callable{});
+  using T = decltype(str);
+  EXPECT_EQ(Callable{}(), T::value);
+  EXPECT_EQ(Callable{}(), str());
+}
+
+TEST(StringConstant, MakeFromStringConstant) {
+  // We want to make sure the StringConstant itself is a valid input to the
+  // factory function.
+  constexpr auto str = MakeStringConstant(Callable{});
+  constexpr auto str2 = MakeStringConstant(str);
+  using T = decltype(str2);
+  EXPECT_EQ(Callable{}(), T::value);
+  EXPECT_EQ(Callable{}(), str2());
+}
+
+}  // namespace
diff --git a/absl/strings/numbers.cc b/absl/strings/numbers.cc
index 68c26dd6..3da1059c 100644
--- a/absl/strings/numbers.cc
+++ b/absl/strings/numbers.cc
@@ -736,9 +736,18 @@ struct LookupTables {
         X / 35, X / 36,                                                   \
   }
 
+// This kVmaxOverBase is generated with
+//  for (int base = 2; base < 37; ++base) {
+//    absl::uint128 max = std::numeric_limits<absl::uint128>::max();
+//    auto result = max / base;
+//    std::cout << "    MakeUint128(" << absl::Uint128High64(result) << "u, "
+//              << absl::Uint128Low64(result) << "u),\n";
+//  }
+// See https://godbolt.org/z/aneYsb
+//
 // uint128& operator/=(uint128) is not constexpr, so hardcode the resulting
 // array to avoid a static initializer.
-template <>
+template<>
 const uint128 LookupTables<uint128>::kVmaxOverBase[] = {
     0,
     0,
@@ -779,6 +788,111 @@ const uint128 LookupTables<uint128>::kVmaxOverBase[] = {
     MakeUint128(512409557603043100u, 8198552921648689607u),
 };
 
+// This kVmaxOverBase generated with
+//   for (int base = 2; base < 37; ++base) {
+//    absl::int128 max = std::numeric_limits<absl::int128>::max();
+//    auto result = max / base;
+//    std::cout << "\tMakeInt128(" << absl::Int128High64(result) << ", "
+//              << absl::Int128Low64(result) << "u),\n";
+//  }
+// See https://godbolt.org/z/7djYWz
+//
+// int128& operator/=(int128) is not constexpr, so hardcode the resulting array
+// to avoid a static initializer.
+template<>
+const int128 LookupTables<int128>::kVmaxOverBase[] = {
+    0,
+    0,
+    MakeInt128(4611686018427387903, 18446744073709551615u),
+    MakeInt128(3074457345618258602, 12297829382473034410u),
+    MakeInt128(2305843009213693951, 18446744073709551615u),
+    MakeInt128(1844674407370955161, 11068046444225730969u),
+    MakeInt128(1537228672809129301, 6148914691236517205u),
+    MakeInt128(1317624576693539401, 2635249153387078802u),
+    MakeInt128(1152921504606846975, 18446744073709551615u),
+    MakeInt128(1024819115206086200, 16397105843297379214u),
+    MakeInt128(922337203685477580, 14757395258967641292u),
+    MakeInt128(838488366986797800, 13415813871788764811u),
+    MakeInt128(768614336404564650, 12297829382473034410u),
+    MakeInt128(709490156681136600, 11351842506898185609u),
+    MakeInt128(658812288346769700, 10540996613548315209u),
+    MakeInt128(614891469123651720, 9838263505978427528u),
+    MakeInt128(576460752303423487, 18446744073709551615u),
+    MakeInt128(542551296285575047, 9765923333140350855u),
+    MakeInt128(512409557603043100, 8198552921648689607u),
+    MakeInt128(485440633518672410, 17475862806672206794u),
+    MakeInt128(461168601842738790, 7378697629483820646u),
+    MakeInt128(439208192231179800, 7027331075698876806u),
+    MakeInt128(419244183493398900, 6707906935894382405u),
+    MakeInt128(401016175515425035, 2406097053092550210u),
+    MakeInt128(384307168202282325, 6148914691236517205u),
+    MakeInt128(368934881474191032, 5902958103587056517u),
+    MakeInt128(354745078340568300, 5675921253449092804u),
+    MakeInt128(341606371735362066, 17763531330238827482u),
+    MakeInt128(329406144173384850, 5270498306774157604u),
+    MakeInt128(318047311615681924, 7633135478776366185u),
+    MakeInt128(307445734561825860, 4919131752989213764u),
+    MakeInt128(297528130221121800, 4760450083537948804u),
+    MakeInt128(288230376151711743, 18446744073709551615u),
+    MakeInt128(279496122328932600, 4471937957262921603u),
+    MakeInt128(271275648142787523, 14106333703424951235u),
+    MakeInt128(263524915338707880, 4216398645419326083u),
+    MakeInt128(256204778801521550, 4099276460824344803u),
+};
+
+// This kVminOverBase generated with
+//  for (int base = 2; base < 37; ++base) {
+//    absl::int128 min = std::numeric_limits<absl::int128>::min();
+//    auto result = min / base;
+//    std::cout << "\tMakeInt128(" << absl::Int128High64(result) << ", "
+//              << absl::Int128Low64(result) << "u),\n";
+//  }
+//
+// See https://godbolt.org/z/7djYWz
+//
+// int128& operator/=(int128) is not constexpr, so hardcode the resulting array
+// to avoid a static initializer.
+template<>
+const int128 LookupTables<int128>::kVminOverBase[] = {
+    0,
+    0,
+    MakeInt128(-4611686018427387904, 0u),
+    MakeInt128(-3074457345618258603, 6148914691236517206u),
+    MakeInt128(-2305843009213693952, 0u),
+    MakeInt128(-1844674407370955162, 7378697629483820647u),
+    MakeInt128(-1537228672809129302, 12297829382473034411u),
+    MakeInt128(-1317624576693539402, 15811494920322472814u),
+    MakeInt128(-1152921504606846976, 0u),
+    MakeInt128(-1024819115206086201, 2049638230412172402u),
+    MakeInt128(-922337203685477581, 3689348814741910324u),
+    MakeInt128(-838488366986797801, 5030930201920786805u),
+    MakeInt128(-768614336404564651, 6148914691236517206u),
+    MakeInt128(-709490156681136601, 7094901566811366007u),
+    MakeInt128(-658812288346769701, 7905747460161236407u),
+    MakeInt128(-614891469123651721, 8608480567731124088u),
+    MakeInt128(-576460752303423488, 0u),
+    MakeInt128(-542551296285575048, 8680820740569200761u),
+    MakeInt128(-512409557603043101, 10248191152060862009u),
+    MakeInt128(-485440633518672411, 970881267037344822u),
+    MakeInt128(-461168601842738791, 11068046444225730970u),
+    MakeInt128(-439208192231179801, 11419412998010674810u),
+    MakeInt128(-419244183493398901, 11738837137815169211u),
+    MakeInt128(-401016175515425036, 16040647020617001406u),
+    MakeInt128(-384307168202282326, 12297829382473034411u),
+    MakeInt128(-368934881474191033, 12543785970122495099u),
+    MakeInt128(-354745078340568301, 12770822820260458812u),
+    MakeInt128(-341606371735362067, 683212743470724134u),
+    MakeInt128(-329406144173384851, 13176245766935394012u),
+    MakeInt128(-318047311615681925, 10813608594933185431u),
+    MakeInt128(-307445734561825861, 13527612320720337852u),
+    MakeInt128(-297528130221121801, 13686293990171602812u),
+    MakeInt128(-288230376151711744, 0u),
+    MakeInt128(-279496122328932601, 13974806116446630013u),
+    MakeInt128(-271275648142787524, 4340410370284600381u),
+    MakeInt128(-263524915338707881, 14230345428290225533u),
+    MakeInt128(-256204778801521551, 14347467612885206813u),
+};
+
 template <typename IntType>
 const IntType LookupTables<IntType>::kVmaxOverBase[] =
     X_OVER_BASE_INITIALIZER(std::numeric_limits<IntType>::max());
@@ -948,6 +1062,10 @@ bool safe_strto64_base(absl::string_view text, int64_t* value, int base) {
   return safe_int_internal<int64_t>(text, value, base);
 }
 
+bool safe_strto128_base(absl::string_view text, int128* value, int base) {
+  return safe_int_internal<absl::int128>(text, value, base);
+}
+
 bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base) {
   return safe_uint_internal<uint32_t>(text, value, base);
 }
diff --git a/absl/strings/numbers.h b/absl/strings/numbers.h
index d872cca5..2e004b44 100644
--- a/absl/strings/numbers.h
+++ b/absl/strings/numbers.h
@@ -127,6 +127,8 @@ inline void PutTwoDigits(size_t i, char* buf) {
 // safe_strto?() functions for implementing SimpleAtoi()
 bool safe_strto32_base(absl::string_view text, int32_t* value, int base);
 bool safe_strto64_base(absl::string_view text, int64_t* value, int base);
+bool safe_strto128_base(absl::string_view text, absl::int128* value,
+                         int base);
 bool safe_strtou32_base(absl::string_view text, uint32_t* value, int base);
 bool safe_strtou64_base(absl::string_view text, uint64_t* value, int base);
 bool safe_strtou128_base(absl::string_view text, absl::uint128* value,
@@ -256,6 +258,11 @@ ABSL_MUST_USE_RESULT bool SimpleAtoi(absl::string_view str, int_type* out) {
 }
 
 ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str,
+                                            absl::int128* out) {
+  return numbers_internal::safe_strto128_base(str, out, 10);
+}
+
+ABSL_MUST_USE_RESULT inline bool SimpleAtoi(absl::string_view str,
                                             absl::uint128* out) {
   return numbers_internal::safe_strtou128_base(str, out, 10);
 }
diff --git a/absl/strings/numbers_test.cc b/absl/strings/numbers_test.cc
index c2f03b63..4ab67fb6 100644
--- a/absl/strings/numbers_test.cc
+++ b/absl/strings/numbers_test.cc
@@ -251,7 +251,7 @@ TEST(Numbers, TestFastPrints) {
 template <typename int_type, typename in_val_type>
 void VerifySimpleAtoiGood(in_val_type in_value, int_type exp_value) {
   std::string s;
-  // uint128 can be streamed but not StrCat'd
+  // (u)int128 can be streamed but not StrCat'd.
   absl::strings_internal::OStringStream(&s) << in_value;
   int_type x = static_cast<int_type>(~exp_value);
   EXPECT_TRUE(SimpleAtoi(s, &x))
@@ -264,7 +264,9 @@ void VerifySimpleAtoiGood(in_val_type in_value, int_type exp_value) {
 
 template <typename int_type, typename in_val_type>
 void VerifySimpleAtoiBad(in_val_type in_value) {
-  std::string s = absl::StrCat(in_value);
+  std::string s;
+  // (u)int128 can be streamed but not StrCat'd.
+  absl::strings_internal::OStringStream(&s) << in_value;
   int_type x;
   EXPECT_FALSE(SimpleAtoi(s, &x));
   EXPECT_FALSE(SimpleAtoi(s.c_str(), &x));
@@ -347,6 +349,31 @@ TEST(NumbersTest, Atoi) {
       std::numeric_limits<absl::uint128>::max(),
       std::numeric_limits<absl::uint128>::max());
 
+  // SimpleAtoi(absl::string_view, absl::int128)
+  VerifySimpleAtoiGood<absl::int128>(0, 0);
+  VerifySimpleAtoiGood<absl::int128>(42, 42);
+  VerifySimpleAtoiGood<absl::int128>(-42, -42);
+
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<int32_t>::min(),
+                                      std::numeric_limits<int32_t>::min());
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<int32_t>::max(),
+                                      std::numeric_limits<int32_t>::max());
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<uint32_t>::max(),
+                                      std::numeric_limits<uint32_t>::max());
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<int64_t>::min(),
+                                      std::numeric_limits<int64_t>::min());
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<int64_t>::max(),
+                                      std::numeric_limits<int64_t>::max());
+  VerifySimpleAtoiGood<absl::int128>(std::numeric_limits<uint64_t>::max(),
+                                      std::numeric_limits<uint64_t>::max());
+  VerifySimpleAtoiGood<absl::int128>(
+      std::numeric_limits<absl::int128>::min(),
+      std::numeric_limits<absl::int128>::min());
+  VerifySimpleAtoiGood<absl::int128>(
+      std::numeric_limits<absl::int128>::max(),
+      std::numeric_limits<absl::int128>::max());
+  VerifySimpleAtoiBad<absl::int128>(std::numeric_limits<absl::uint128>::max());
+
   // Some other types
   VerifySimpleAtoiGood<int>(-42, -42);
   VerifySimpleAtoiGood<int32_t>(-42, -42);
@@ -725,6 +752,51 @@ TEST(stringtest, safe_strtou128_random) {
     EXPECT_FALSE(parse_func(s, &parsed_value, base));
   }
 }
+TEST(stringtest, safe_strto128_random) {
+  // random number generators don't work for int128, and
+  // int128 can be streamed but not StrCat'd, so this code must be custom
+  // implemented for int128, but is generally the same as what's above.
+  // test_random_integer_parse_base<absl::int128>(
+  //     &absl::numbers_internal::safe_strto128_base);
+  using RandomEngine = std::minstd_rand0;
+  using IntType = absl::int128;
+  constexpr auto parse_func = &absl::numbers_internal::safe_strto128_base;
+
+  std::random_device rd;
+  RandomEngine rng(rd());
+  std::uniform_int_distribution<int64_t> random_int64(
+      std::numeric_limits<int64_t>::min());
+  std::uniform_int_distribution<uint64_t> random_uint64(
+      std::numeric_limits<uint64_t>::min());
+  std::uniform_int_distribution<int> random_base(2, 35);
+
+  for (size_t i = 0; i < kNumRandomTests; ++i) {
+    int64_t high = random_int64(rng);
+    uint64_t low = random_uint64(rng);
+    IntType value = absl::MakeInt128(high, low);
+
+    int base = random_base(rng);
+    std::string str_value;
+    EXPECT_TRUE(Itoa<IntType>(value, base, &str_value));
+    IntType parsed_value;
+
+    // Test successful parse
+    EXPECT_TRUE(parse_func(str_value, &parsed_value, base));
+    EXPECT_EQ(parsed_value, value);
+
+    // Test overflow
+    std::string s;
+    absl::strings_internal::OStringStream(&s)
+        << std::numeric_limits<IntType>::max() << value;
+    EXPECT_FALSE(parse_func(s, &parsed_value, base));
+
+    // Test underflow
+    s.clear();
+    absl::strings_internal::OStringStream(&s)
+        << std::numeric_limits<IntType>::min() << value;
+    EXPECT_FALSE(parse_func(s, &parsed_value, base));
+  }
+}
 
 TEST(stringtest, safe_strtou32_base) {
   for (int i = 0; strtouint32_test_cases()[i].str != nullptr; ++i) {