1 files changed, 25 insertions, 15 deletions

diff --git a/absl/strings/internal/cordz_info.cc b/absl/strings/internal/cordz_info.cc
index 515dfafb..b830c25c 100644
--- a/absl/strings/internal/cordz_info.cc
+++ b/absl/strings/internal/cordz_info.cc
@@ -33,8 +33,6 @@ namespace absl {
 ABSL_NAMESPACE_BEGIN
 namespace cord_internal {
 
-using ::absl::base_internal::SpinLockHolder;
-
 #ifdef ABSL_INTERNAL_NEED_REDUNDANT_CONSTEXPR_DECL
 constexpr size_t CordzInfo::kMaxStackDepth;
 #endif
@@ -79,6 +77,8 @@ class CordRepAnalyzer {
   // adds the results to `statistics`. Note that node counts and memory sizes
   // are not initialized, computed values are added to any existing values.
   void AnalyzeCordRep(const CordRep* rep) {
+    ABSL_ASSERT(rep != nullptr);
+
     // Process all linear nodes.
     // As per the class comments, use refcout - 1 on the top level node, as the
     // top level node is assumed to be referenced only for analysis purposes.
@@ -86,7 +86,7 @@ class CordRepAnalyzer {
     RepRef repref{rep, (refcount > 1) ? refcount - 1 : 1};
 
     // Process the top level CRC node, if present.
-    if (repref.rep->tag == CRC) {
+    if (repref.tag() == CRC) {
       statistics_.node_count++;
       statistics_.node_counts.crc++;
       memory_usage_.Add(sizeof(CordRepCrc), repref.refcount);
@@ -96,15 +96,17 @@ class CordRepAnalyzer {
     // Process all top level linear nodes (substrings and flats).
     repref = CountLinearReps(repref, memory_usage_);
 
-    if (repref.rep != nullptr) {
-      if (repref.rep->tag == RING) {
+    switch (repref.tag()) {
+      case CordRepKind::RING:
         AnalyzeRing(repref);
-      } else if (repref.rep->tag == BTREE) {
+        break;
+      case CordRepKind::BTREE:
         AnalyzeBtree(repref);
-      } else {
-        // We should have either a concat, btree, or ring node if not null.
-        assert(false);
-      }
+        break;
+      default:
+        // We should have either a btree or ring node if not null.
+        ABSL_ASSERT(repref.tag() == CordRepKind::UNUSED_0);
+        break;
     }
 
     // Adds values to output
@@ -122,11 +124,19 @@ class CordRepAnalyzer {
     const CordRep* rep;
     size_t refcount;
 
-    // Returns a 'child' RepRef which contains the cumulative reference count of
-    // this instance multiplied by the child's reference count.
+    // Returns a 'child' RepRef which contains the cumulative reference count
+    // of this instance multiplied by the child's reference count. Returns a
+    // nullptr RepRef value with a refcount of 0 if `child` is nullptr.
     RepRef Child(const CordRep* child) const {
+      if (child == nullptr) return RepRef{nullptr, 0};
       return RepRef{child, refcount * child->refcount.Get()};
     }
+
+    // Returns the tag of this rep, or UNUSED_0 if this instance is null
+    constexpr CordRepKind tag() const {
+      ABSL_ASSERT(rep == nullptr || rep->tag != CordRepKind::UNUSED_0);
+      return rep ? static_cast<CordRepKind>(rep->tag) : CordRepKind::UNUSED_0;
+    }
   };
 
   // Memory usage values
@@ -167,7 +177,7 @@ class CordRepAnalyzer {
   // buffers where we count children unrounded.
   RepRef CountLinearReps(RepRef rep, MemoryUsage& memory_usage) {
     // Consume all substrings
-    while (rep.rep->tag == SUBSTRING) {
+    while (rep.tag() == SUBSTRING) {
       statistics_.node_count++;
       statistics_.node_counts.substring++;
       memory_usage.Add(sizeof(CordRepSubstring), rep.refcount);
@@ -175,7 +185,7 @@ class CordRepAnalyzer {
     }
 
     // Consume possible FLAT
-    if (rep.rep->tag >= FLAT) {
+    if (rep.tag() >= FLAT) {
       size_t size = rep.rep->flat()->AllocatedSize();
       CountFlat(size);
       memory_usage.Add(size, rep.refcount);
@@ -183,7 +193,7 @@ class CordRepAnalyzer {
     }
 
     // Consume possible external
-    if (rep.rep->tag == EXTERNAL) {
+    if (rep.tag() == EXTERNAL) {
       statistics_.node_count++;
       statistics_.node_counts.external++;
       size_t size = rep.rep->length + sizeof(CordRepExternalImpl<intptr_t>);