Revert "handle MT issues in setVertexArrivals, fix non-determ crash"

This reverts commit for serVertexArrivals MT safe change 16c2678e51.

graph/Graph.cc

@@ -1126,12 +1126,6 @@ Vertex::deletePaths()
   tag_group_index_ = tag_group_index_max;
 }
 
-void
-Vertex::setPathsDeferred(Path *paths)
-{
-  paths_ = paths;
-}
-
 bool
 Vertex::hasFanin() const
 {

include/sta/Graph.hh

@@ -264,9 +264,6 @@ public:
   Path *makePaths(uint32_t count);
   void setPaths(Path *paths);
   void deletePaths();
-  // Set paths_ without deleting the old array.
-  // Caller is responsible for deferred deletion of the old array.
-  void setPathsDeferred(Path *paths);
   TagGroupIndex tagGroupIndex() const;
   void setTagGroupIndex(TagGroupIndex tag_index);
   // Slew is annotated by sdc set_annotated_transition cmd.

include/sta/Search.hh

@@ -414,7 +414,6 @@ protected:
   void initVars();
   void deleteTags();
   void deleteTagsPrev();
-  void deletePendingPaths();
   void deleteUnusedTagGroups();
   void seedInvalidArrivals();
   void seedArrivals();
@@ -601,10 +600,6 @@ protected:
   std::mutex invalid_arrivals_lock_;
   BfsFwdIterator *arrival_iter_;
   ArrivalVisitor *arrival_visitor_;
-  // Old vertex path arrays deferred for deletion until after the parallel
-  // BFS level completes, preventing use-after-free in concurrent CRPR readers.
-  std::vector<Path*> paths_pending_delete_;
-  std::mutex paths_pending_delete_lock_;
 
   // Some requireds exist.
   bool requireds_exist_;

search/Search.cc

@@ -708,20 +708,6 @@ Search::deleteTagsPrev()
   for (TagGroup** tag_groups: tag_groups_prev_)
     delete [] tag_groups;
   tag_groups_prev_.clear();
-
-  deletePendingPaths();
-}
-
-// Free old vertex path arrays that were deferred during parallel BFS visits.
-// Called after visitParallel completes so no thread can still hold a pointer
-// into any of these arrays.
-void
-Search::deletePendingPaths()
-{
-  LockGuard lock(paths_pending_delete_lock_);
-  for (Path *paths : paths_pending_delete_)
-    delete [] paths;
-  paths_pending_delete_.clear();
 }
 
 void
@@ -2829,28 +2815,8 @@ void
 Search::setVertexArrivals(Vertex *vertex,
                           TagGroupBldr *tag_bldr)
 {
-  if (tag_bldr->empty()) {
-    // Inline the deletePathsIncr logic using deferred deletion so that
-    // concurrent CRPR/latch readers that hold a pointer into the old path
-    // array are not left with a dangling pointer.
-    tnsNotifyBefore(vertex);
-    if (worst_slacks_)
-      worst_slacks_->worstSlackNotifyBefore(vertex);
-    TagGroup *tag_group = tagGroup(vertex);
-    if (tag_group) {
-      Path *old_paths = vertex->paths();
-      // Clear the tag group index first so concurrent readers observe a
-      // null tag group (and return early from Path::vertexPath) before
-      // we touch paths_.
-      vertex->setTagGroupIndex(tag_group_index_max);
-      vertex->setPathsDeferred(nullptr);
-      tag_group->decrRefCount();
-      if (old_paths) {
-        LockGuard lock(paths_pending_delete_lock_);
-        paths_pending_delete_.push_back(old_paths);
-      }
-    }
-  }
+  if (tag_bldr->empty())
+    deletePathsIncr(vertex);
   else {
     TagGroup *prev_tag_group = tagGroup(vertex);
     Path *prev_paths = vertex->paths();
@@ -2861,25 +2827,13 @@ Search::setVertexArrivals(Vertex *vertex,
     }
     else {
       if (prev_tag_group) {
-        // Clear the tag group index before replacing paths so concurrent
-        // readers see a consistent null-tag-group state during the
-        // transition and do not mix the old tag group with the new array.
-        vertex->setTagGroupIndex(tag_group_index_max);
+        vertex->deletePaths();
         prev_tag_group->decrRefCount();
         requiredInvalid(vertex);
       }
       size_t path_count = tag_group->pathCount();
-      // Allocate the new array and switch paths_ directly from old to new
-      // without creating a null window or freeing the old array immediately.
-      // This prevents concurrent CRPR/latch readers from observing either a
-      // null pointer or a freed (dangling) pointer.
-      Path *new_paths = new Path[path_count];
-      vertex->setPathsDeferred(new_paths);
-      if (prev_paths) {
-        LockGuard lock(paths_pending_delete_lock_);
-        paths_pending_delete_.push_back(prev_paths);
-      }
-      tag_bldr->copyPaths(tag_group, new_paths);
+      Path *paths = vertex->makePaths(path_count);
+      tag_bldr->copyPaths(tag_group, paths);
       vertex->setTagGroupIndex(tag_group->index());
       tag_group->incrRefCount();
     }