Dispatch on type pairs for begin iter

ConflictSet.cpp

@@ -4285,13 +4285,10 @@ void pointIter(Job *job, Context *context) {
 
 template <class NodeTFrom, class NodeTTo>
 PRESERVE_NONE void prefixIter(Job *, Context *);
-template <class NodeT> PRESERVE_NONE void beginIter(Job *, Context *);
+template <class NodeTFrom, class NodeTTo>
+PRESERVE_NONE void beginIter(Job *, Context *);
 template <class NodeT> PRESERVE_NONE void endIter(Job *, Context *);
 
-static Continuation beginIterTable[] = {beginIter<Node0>, beginIter<Node3>,
-                                        beginIter<Node16>, beginIter<Node48>,
-                                        beginIter<Node256>};
-
 static Continuation endIterTable[] = {endIter<Node0>, endIter<Node3>,
                                       endIter<Node16>, endIter<Node48>,
                                       endIter<Node256>};
@@ -4309,6 +4306,19 @@ static constexpr Continuation const *prefixIterTable[] = {
     PrefixIterTable<Node256>::table,
 };
 
+template <class NodeTFrom> struct BeginIterTable {
+  static constexpr Continuation table[] = {
+      beginIter<NodeTFrom, Node0>, beginIter<NodeTFrom, Node3>,
+      beginIter<NodeTFrom, Node16>, beginIter<NodeTFrom, Node48>,
+      beginIter<NodeTFrom, Node256>};
+};
+
+static constexpr Continuation const *beginIterTable[] = {
+    BeginIterTable<Node0>::table,   BeginIterTable<Node3>::table,
+    BeginIterTable<Node16>::table,  BeginIterTable<Node48>::table,
+    BeginIterTable<Node256>::table,
+};
+
 template <class NodeTFrom, class NodeTTo>
 void prefixIter(Job *job, Context *context) {
   assert(NodeTFrom::kType == job->n->getType());
@@ -4348,11 +4358,14 @@ void prefixIter(Job *job, Context *context) {
     job->end = job->end.subspan(job->commonPrefixLen,
                                 job->end.size() - job->commonPrefixLen);
     if (job->begin.size() == 0) [[unlikely]] {
-      job->continuation = endIterTable[child->getType()];
+      MUSTTAIL return endIter<NodeTTo>(job, context);
+    } else if (!job->getChildAndIndex(child, job->begin.front())) [[unlikely]] {
+      MUSTTAIL return endIter<NodeTTo>(job, context);
     } else {
-      job->continuation = beginIterTable[child->getType()];
+      job->continuation = BeginIterTable<NodeTTo>::table[job->child.getType()];
+      __builtin_prefetch(job->child);
+      MUSTTAIL return keepGoing(job, context);
     }
-    MUSTTAIL return keepGoing(job, context);
   }
 
   if (!job->getChildAndIndex(child, job->remaining.front())) [[unlikely]] {
@@ -4377,22 +4390,49 @@ noNodeOnSearchPath:
   MUSTTAIL return complete(job, context);
 }
 
-template <class NodeT> void beginIter(Job *job, Context *context) {
+template <class NodeTFrom, class NodeTTo>
-  assert(NodeT::kType == job->n->getType());
+void beginIter(Job *job, Context *context) {
-  NodeT *n = static_cast<NodeT *>(job->n);
+  assert(NodeTFrom::kType == job->n->getType());
+  NodeTFrom *n = static_cast<NodeTFrom *>(job->n);
+  assert(NodeTTo::kType == job->child->getType());
+  NodeTTo *child = static_cast<NodeTTo *>(job->child);
 
-  TaggedNodePointer *child =
+  auto key = job->begin.subspan(1, job->begin.size() - 1);
-      getChildUpdatingMaxVersion(n, job->begin, context->writeVersion);
+  if (child->partialKeyLen > 0) {
-  if (child == nullptr) [[unlikely]] {
+    int commonLen = std::min<int>(child->partialKeyLen, key.size());
-    MUSTTAIL return endIterTable[job->endNode->getType()](job, context);
+    int partialKeyIndex =
+        longestCommonPrefix(child->partialKey(), key.data(), commonLen);
+    if (partialKeyIndex < child->partialKeyLen) {
+      MUSTTAIL return endIterTable[job->endNode->getType()](job, context);
+    }
   }
-  job->n = *child;
+
+  // child is on the search path. Commit to advancing and updating max version
+  job->n = child;
+  job->begin =
+      key.subspan(child->partialKeyLen, key.size() - child->partialKeyLen);
+  if constexpr (std::is_same_v<NodeTFrom, Node3> ||
+                std::is_same_v<NodeTFrom, Node16>) {
+    n->childMaxVersion[job->childIndex] = context->writeVersion;
+  } else if constexpr (std::is_same_v<NodeTFrom, Node48> ||
+                       std::is_same_v<NodeTFrom, Node256>) {
+    n->maxOfMax[job->childIndex >> NodeTFrom::kMaxOfMaxShift] =
+        std::max(n->maxOfMax[job->childIndex >> NodeTFrom::kMaxOfMaxShift],
+                 context->writeVersion);
+    n->childMaxVersion[job->childIndex] = context->writeVersion;
+  }
+
   if (job->begin.size() == 0) [[unlikely]] {
     MUSTTAIL return endIterTable[job->endNode->getType()](job, context);
   }
+
+  if (!job->getChildAndIndex(child, job->begin.front())) [[unlikely]] {
+    MUSTTAIL return endIterTable[job->endNode->getType()](job, context);
+  }
+
   ++context->iterations;
-  job->continuation = beginIterTable[child->getType()];
+  job->continuation = BeginIterTable<NodeTTo>::table[job->child.getType()];
-  __builtin_prefetch(job->n);
+  __builtin_prefetch(job->child);
   MUSTTAIL return keepGoing(job, context);
 }
 
@@ -4456,7 +4496,11 @@ void Job::init(Context *context, int index) {
     }
   } else if (begin.size() > 0) {
     endNode = n;
-    continuation = beginIterTable[n->getType()];
+    if (!getChildAndIndex(n, begin.front())) [[unlikely]] {
+      continuation = endIterTable[n->getType()];
+    } else {
+      continuation = beginIterTable[n->getType()][child.getType()];
+    }
   } else {
     endNode = n;
     continuation = endIterTable[n->getType()];