Export of internal Abseil changes

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4ff721439234e91caf6f7b772e5f554e7dd423c8 by Benjamin Barenblat <bbaren@google.com>:

Remove endian-sensitivity from hash slow path

Prior to this commit, the Abseil hash fast path was endian-agnostic, but
the slow path assumed a little-endian platform. Change the slow path to
be endian-correct, ensuring that values produced by the fast and slow
paths are equal even on big-endian systems.

PiperOrigin-RevId: 355424258

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7f4fe1aa4de46ad0a2ef19fa9c061fc12a7391ed by Abseil Team <absl-team@google.com>:

Directly store CordzInfo in the InlineData data contents of InlineRep

This greatly reduces the cost of coping and moving cords. Especially the move constructor and move assignment are now back to lean loads and stores without needing any CordzInfo lookups for tracked cords.

PiperOrigin-RevId: 355409161

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3ca4ca84ed6d98f1e383ffd8d12c28876e905bb3 by Abseil Team <absl-team@google.com>:

Add #include <unordered_map>

PiperOrigin-RevId: 355386114

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30b0ffad0621971b3135148fcc9e183b0dd2a6bb by Abseil Team <absl-team@google.com>:

Optimize Cord copy constructor

This change avoids double stores of the Cord copy constructor from the zero init of the InlineData / InlineRep contents followed by the assignment and inlines the copy constructor.

PiperOrigin-RevId: 355287939

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0c043fa7b6e41ca7cefc5edc1e17ad46223e4e77 by CJ Johnson <johnsoncj@google.com>:

Now that the absl::Cleanup example returns absl::Status, since we decided on absl::FailedPreconditionError, the precondition should be a positive statement and then the check should be failure to adhere to that positive statement

PiperOrigin-RevId: 355216923

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9ed922ca5d28fe8790ec6bc0837cf39fbcc92896 by Gennadiy Rozental <rogeeff@google.com>:

Do not set mvsc linker flags for clang-cl (fixes #874)

Import of https://github.com/abseil/abseil-cpp/pull/891

PiperOrigin-RevId: 355199380
GitOrigin-RevId: 4ff721439234e91caf6f7b772e5f554e7dd423c8
Change-Id: I3d9d2383549720d7a91f9108dfcd979ad6632fce

4 files changed, 37 insertions, 9 deletions

diff --git a/absl/strings/cord.cc b/absl/strings/cord.cc
index 39191ef5..93533757 100644
--- a/absl/strings/cord.cc
+++ b/absl/strings/cord.cc
@@ -495,7 +495,9 @@ void Cord::InlineRep::AssignSlow(const Cord::InlineRep& src) {
 
   data_ = src.data_;
   if (is_tree()) {
+    data_.set_profiled(false);
     CordRep::Ref(tree());
+    clear_cordz_info();
   }
 }
 
@@ -509,12 +511,6 @@ void Cord::InlineRep::ClearSlow() {
 // --------------------------------------------------------------------
 // Constructors and destructors
 
-Cord::Cord(const Cord& src) : contents_(src.contents_) {
-  if (CordRep* tree = contents_.tree()) {
-    CordRep::Ref(tree);
-  }
-}
-
 Cord::Cord(absl::string_view src) {
   const size_t n = src.size();
   if (n <= InlineRep::kMaxInline) {
diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index aefb5e53..320226d2 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -755,6 +755,23 @@ class Cord {
 
     bool is_tree() const { return data_.is_tree(); }
 
+    // Returns true if the Cord is being profiled by cordz.
+    bool is_profiled() const { return data_.is_tree() && data_.is_profiled(); }
+
+    // Returns the profiled CordzInfo, or nullptr if not sampled.
+    absl::cord_internal::CordzInfo* cordz_info() const {
+      return data_.cordz_info();
+    }
+
+    // Sets the profiled CordzInfo. `cordz_info` must not be null.
+    void set_cordz_info(cord_internal::CordzInfo* cordz_info) {
+      assert(cordz_info != nullptr);
+      data_.set_cordz_info(cordz_info);
+    }
+
+    // Resets the current cordz_info to null / empty.
+    void clear_cordz_info() { data_.clear_cordz_info(); }
+
    private:
     friend class Cord;
 
@@ -921,8 +938,12 @@ Cord MakeCordFromExternal(absl::string_view data, Releaser&& releaser) {
 constexpr Cord::InlineRep::InlineRep(cord_internal::InlineData data)
     : data_(data) {}
 
-inline Cord::InlineRep::InlineRep(const Cord::InlineRep& src) {
-  data_ = src.data_;
+inline Cord::InlineRep::InlineRep(const Cord::InlineRep& src)
+    : data_(src.data_) {
+  if (is_tree()) {
+    data_.clear_cordz_info();
+    absl::cord_internal::CordRep::Ref(as_tree());
+  }
 }
 
 inline Cord::InlineRep::InlineRep(Cord::InlineRep&& src) {
@@ -956,7 +977,6 @@ inline void Cord::InlineRep::Swap(Cord::InlineRep* rhs) {
   if (rhs == this) {
     return;
   }
-
   std::swap(data_, rhs->data_);
 }
 
@@ -1037,6 +1057,8 @@ inline Cord& Cord::operator=(const Cord& x) {
   return *this;
 }
 
+inline Cord::Cord(const Cord& src) : contents_(src.contents_) {}
+
 inline Cord::Cord(Cord&& src) noexcept : contents_(std::move(src.contents_)) {}
 
 inline void Cord::swap(Cord& other) noexcept {
diff --git a/absl/strings/cord_test.cc b/absl/strings/cord_test.cc
index bf7a6820..f9982428 100644
--- a/absl/strings/cord_test.cc
+++ b/absl/strings/cord_test.cc
@@ -183,6 +183,10 @@ class CordTestPeer {
   }
 
   static bool IsTree(const Cord& c) { return c.contents_.is_tree(); }
+
+  static cord_internal::CordzInfo* GetCordzInfo(const Cord& c) {
+    return c.contents_.cordz_info();
+  }
 };
 
 ABSL_NAMESPACE_END
diff --git a/absl/strings/internal/cord_internal.h b/absl/strings/internal/cord_internal.h
index cda00a44..a1ba67fe 100644
--- a/absl/strings/internal/cord_internal.h
+++ b/absl/strings/internal/cord_internal.h
@@ -387,6 +387,12 @@ class InlineData {
     as_tree_.cordz_info = absl::big_endian::FromHost64(info);
   }
 
+  // Resets the current cordz_info to null / empty.
+  void clear_cordz_info() {
+    assert(is_tree());
+    as_tree_.cordz_info = kNullCordzInfo;
+  }
+
   // Returns a read only pointer to the character data inside this instance.
   // Requires the current instance to hold inline data.
   const char* as_chars() const {