Prepare for erase to invalidate children of parent

ConflictSet.cpp

@@ -829,7 +829,7 @@ void maybeDecreaseCapacity(Node *&self, NodeAllocators *allocators,
 
 // TODO fuse into erase child so we don't need to repeat branches on type
 void maybeDownsize(Node *self, NodeAllocators *allocators,
-                   ConflictSet::Impl *impl) {
+                   ConflictSet::Impl *impl, Node *&dontInvalidate) {
   switch (self->type) {
   case Type::Node0:
     __builtin_unreachable(); // GCOVR_EXCL_LINE
@@ -954,7 +954,8 @@ void maybeDownsize(Node *self, NodeAllocators *allocators,
 }
 
 // Precondition: self is not the root. May invalidate nodes along the search
-// path to self.
+// path to self. May invalidate children of self->parent. Returns a pointer to
+// the node after self.
 Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl) {
   assert(self->parent != nullptr);
 
@@ -1019,7 +1020,7 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl) {
       parent->parent != nullptr) {
     erase(parent, allocators, impl);
   } else {
-    maybeDownsize(parent, allocators, impl);
+    maybeDownsize(parent, allocators, impl, result);
   }
   return result;
 }
@@ -2014,8 +2015,14 @@ void addWriteRange(Node *&root, int64_t oldestVersion,
     assert(beginNode->entryPresent);
   }
 
-  for (beginNode = nextLogical(beginNode); beginNode != endNode;
-       beginNode = erase(beginNode, allocators, impl)) {
+  for (beginNode = nextLogical(beginNode); beginNode != endNode;) {
+    auto *next = nextLogical(beginNode);
+    bool done = next == endNode;
+    erase(beginNode, allocators, impl);
+    if (done) {
+      break;
+    }
+    beginNode = next;
   }
 }