Export of internal Abseil changes

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ed829ac612f090375427c3488827c6e74deb2e3f by Derek Mauro <dmauro@google.com>:

Update latest GCC/Clang Linux tests to Bazel 5.0.0 and CMake 3.22.2

PiperOrigin-RevId: 429369775

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76952303c4d942288c4e7657ffb5893cec54a132 by Martijn Vels <mvels@google.com>:

Optimize Cord::ChunkIterator now that CordRepConcat is removed

PiperOrigin-RevId: 429321455

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dcd0d287793649aba9b98268c5783e449a34749f by Martijn Vels <mvels@google.com>:

Add IsDataEdge() and DataEdgeValue() helper functions.

This moves repetitive logic accessing data edges into its own header, and more strongly defines the notion of what a data edge is, enforcing the internal invariants. This will also be incorporated in optimized Cord iteration logic once CordRepConcat is totally removed from the Cord code.

PiperOrigin-RevId: 429307248

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6a0903962155988085bf8656743fda9c4cdcba6c by Abseil Team <absl-team@google.com>:

Make it clear that the probability function given for the zipf distribution is unnormalized, i.e., sum(p(x) for x = 0..k) != 100%.

Quoting Section 7 of the paper cited in the comments, where this formula comes from (emphasis mine): "We will consider the two parameter generalization as defined in Dagpunar [1988] with the *unnormalized* probability function ..."

PiperOrigin-RevId: 429068258

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3899ff6d444ba755148bc521a6ee031d9e9d4485 by Abseil Team <absl-team@google.com>:

Internal Changes

PiperOrigin-RevId: 428644856

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319de702d2b537cbb76c4c71277ae89b349b162e by Benjamin Barenblat <bbaren@google.com>:

Support symbolization on PA-RISC

Null out supervisor bits in PA-RISC addresses before symbolizing, and
handle function descriptor tables correctly.

Change symbolize_test.cc to use 32-bit aligned addresses, allowing that
test to pass on PA-RISC.

PiperOrigin-RevId: 428590564
GitOrigin-RevId: ed829ac612f090375427c3488827c6e74deb2e3f
Change-Id: Ie01ff3b9365fd45e5a55f858038552679f3180d3

1 files changed, 24 insertions, 32 deletions

diff --git a/absl/strings/cord.h b/absl/strings/cord.h
index 7f34ef48..081b6311 100644
--- a/absl/strings/cord.h
+++ b/absl/strings/cord.h
@@ -80,6 +80,7 @@
 #include "absl/functional/function_ref.h"
 #include "absl/meta/type_traits.h"
 #include "absl/strings/cord_analysis.h"
+#include "absl/strings/internal/cord_data_edge.h"
 #include "absl/strings/internal/cord_internal.h"
 #include "absl/strings/internal/cord_rep_btree.h"
 #include "absl/strings/internal/cord_rep_btree_reader.h"
@@ -388,12 +389,6 @@ class Cord {
     using CordRepBtree = absl::cord_internal::CordRepBtree;
     using CordRepBtreeReader = absl::cord_internal::CordRepBtreeReader;
 
-    // Stack of right children of concat nodes that we have to visit.
-    // Keep this at the end of the structure to avoid cache-thrashing.
-    // TODO(jgm): Benchmark to see if there's a more optimal value than 47 for
-    // the inlined vector size (47 exists for backward compatibility).
-    using Stack = absl::InlinedVector<absl::cord_internal::CordRep*, 47>;
-
     // Constructs a `begin()` iterator from `tree`. `tree` must not be null.
     explicit ChunkIterator(cord_internal::CordRep* tree);
 
@@ -409,17 +404,10 @@ class Cord {
     Cord AdvanceAndReadBytes(size_t n);
     void AdvanceBytes(size_t n);
 
-    // Stack specific operator++
-    ChunkIterator& AdvanceStack();
-
     // Btree specific operator++
     ChunkIterator& AdvanceBtree();
     void AdvanceBytesBtree(size_t n);
 
-    // Iterates `n` bytes, where `n` is expected to be greater than or equal to
-    // `current_chunk_.size()`.
-    void AdvanceBytesSlowPath(size_t n);
-
     // A view into bytes of the current `CordRep`. It may only be a view to a
     // suffix of bytes if this is being used by `CharIterator`.
     absl::string_view current_chunk_;
@@ -432,9 +420,6 @@ class Cord {
 
     // Cord reader for cord btrees. Empty if not traversing a btree.
     CordRepBtreeReader btree_reader_;
-
-    // See 'Stack' alias definition.
-    Stack stack_of_right_children_;
   };
 
   // Cord::ChunkIterator::chunk_begin()
@@ -725,7 +710,8 @@ class Cord {
   // be used by spelling absl::strings_internal::MakeStringConstant, which is
   // also an internal API.
   template <typename T>
-  explicit constexpr Cord(strings_internal::StringConstant<T>);
+  // NOLINTNEXTLINE(google-explicit-constructor)
+  constexpr Cord(strings_internal::StringConstant<T>);
 
  private:
   using CordRep = absl::cord_internal::CordRep;
@@ -1321,25 +1307,24 @@ inline void Cord::ChunkIterator::InitTree(cord_internal::CordRep* tree) {
   tree = cord_internal::SkipCrcNode(tree);
   if (tree->tag == cord_internal::BTREE) {
     current_chunk_ = btree_reader_.Init(tree->btree());
-    return;
+  } else {
+    current_leaf_ = tree;
+    current_chunk_ = cord_internal::EdgeData(tree);
   }
-
-  stack_of_right_children_.push_back(tree);
-  operator++();
 }
 
-inline Cord::ChunkIterator::ChunkIterator(cord_internal::CordRep* tree)
-    : bytes_remaining_(tree->length) {
+inline Cord::ChunkIterator::ChunkIterator(cord_internal::CordRep* tree) {
+  bytes_remaining_ = tree->length;
   InitTree(tree);
 }
 
-inline Cord::ChunkIterator::ChunkIterator(const Cord* cord)
-    : bytes_remaining_(cord->size()) {
-  if (cord->contents_.is_tree()) {
-    InitTree(cord->contents_.as_tree());
+inline Cord::ChunkIterator::ChunkIterator(const Cord* cord) {
+  if (CordRep* tree = cord->contents_.tree()) {
+    bytes_remaining_ = tree->length;
+    InitTree(tree);
   } else {
-    current_chunk_ =
-        absl::string_view(cord->contents_.data(), bytes_remaining_);
+    bytes_remaining_ = cord->contents_.inline_size();
+    current_chunk_ = {cord->contents_.data(), bytes_remaining_};
   }
 }
 
@@ -1369,8 +1354,11 @@ inline Cord::ChunkIterator& Cord::ChunkIterator::operator++() {
   assert(bytes_remaining_ >= current_chunk_.size());
   bytes_remaining_ -= current_chunk_.size();
   if (bytes_remaining_ > 0) {
-    return btree_reader_ ? AdvanceBtree() : AdvanceStack();
-  } else {
+    if (btree_reader_) {
+      return AdvanceBtree();
+    } else {
+      assert(!current_chunk_.empty());  // Called on invalid iterator.
+    }
     current_chunk_ = {};
   }
   return *this;
@@ -1411,7 +1399,11 @@ inline void Cord::ChunkIterator::AdvanceBytes(size_t n) {
   if (ABSL_PREDICT_TRUE(n < current_chunk_.size())) {
     RemoveChunkPrefix(n);
   } else if (n != 0) {
-    btree_reader_ ? AdvanceBytesBtree(n) : AdvanceBytesSlowPath(n);
+    if (btree_reader_) {
+      AdvanceBytesBtree(n);
+    } else {
+      bytes_remaining_ = 0;
+    }
   }
 }