Return inserted physical node from insert

ConflictSet.cpp

@@ -615,6 +615,13 @@ Node *prevPhysical(Node *node) {
   }
 }
 
+Node *prevLogical(Node *node) {
+  for (node = prevPhysical(node); node != nullptr && !node->entryPresent;
+       node = prevPhysical(node))
+    ;
+  return node;
+}
+
 struct Iterator {
   Node *n;
   int cmp;
@@ -707,7 +714,12 @@ outerLoop:
   return {n, -1};
 }
 
-void insert(Node **self_, std::span<const uint8_t> key, int64_t writeVersion) {
+// Returns a pointer to the newly inserted node.  caller is reponsible for
+// setting 'entry' fields on the result, which may have !entryPresent. The
+// search path for `key` will have maxVersion at least `writeVersion` as a
+// postcondition.
+[[nodiscard]] Node *insert(Node **self_, std::span<const uint8_t> key,
+                           int64_t writeVersion) {
   for (;;) {
     auto &self = *self_;
     // Handle an existing partial key
@@ -745,13 +757,7 @@ void insert(Node **self_, std::span<const uint8_t> key, int64_t writeVersion) {
     self->maxVersion = std::max(self->maxVersion, writeVersion);
 
     if (key.size() == 0) {
-      auto l = lastLeq(self, key);
-      self->entryPresent = true;
-      self->entry.pointVersion = writeVersion;
-      assert(l.n != nullptr);
-      assert(l.n->entryPresent);
-      self->entry.rangeVersion = l.n->entry.rangeVersion;
-      return;
+      return self;
     }
     auto &child = getOrCreateChild(self, key.front());
     if (!child) {
@@ -812,8 +818,17 @@ struct __attribute__((visibility("hidden"))) ConflictSet::Impl {
       const auto &w = writes[i];
       // TODO support non-point writes
       assert(w.end.len == 0);
-      insert(&root, std::span<const uint8_t>(w.begin.p, w.begin.len),
+      auto *n = insert(&root, std::span<const uint8_t>(w.begin.p, w.begin.len),
                        w.writeVersion);
+      if (!n->entryPresent) {
+        auto *p = prevLogical(n);
+        assert(p != nullptr);
+        n->entryPresent = true;
+        n->entry.pointVersion = w.writeVersion;
+        n->entry.rangeVersion = p->entry.rangeVersion;
+      } else {
+        n->entry.pointVersion = std::max(n->entry.pointVersion, w.writeVersion);
+      }
     }
   }
   void setOldestVersion(int64_t oldestVersion) {