Dispatch on type pairs for common prefix iter

ConflictSet.cpp

@@ -4283,14 +4283,11 @@ void pointIter(Job *job, Context *context) {
   MUSTTAIL return keepGoing(job, context);
 }
 
-template <class NodeT> PRESERVE_NONE void commonPrefixIter(Job *, Context *);
+template <class NodeTFrom, class NodeTTo>
+PRESERVE_NONE void prefixIter(Job *, Context *);
 template <class NodeT> PRESERVE_NONE void beginIter(Job *, Context *);
 template <class NodeT> PRESERVE_NONE void endIter(Job *, Context *);
 
-static Continuation commonPrefixIterTable[] = {
-    commonPrefixIter<Node0>, commonPrefixIter<Node3>, commonPrefixIter<Node16>,
-    commonPrefixIter<Node48>, commonPrefixIter<Node256>};
-
 static Continuation beginIterTable[] = {beginIter<Node0>, beginIter<Node3>,
                                         beginIter<Node16>, beginIter<Node48>,
                                         beginIter<Node256>};
@@ -4299,26 +4296,51 @@ static Continuation endIterTable[] = {endIter<Node0>, endIter<Node3>,
                                       endIter<Node16>, endIter<Node48>,
                                       endIter<Node256>};
 
-template <class NodeT> void commonPrefixIter(Job *job, Context *context) {
+template <class NodeTFrom> struct PrefixIterTable {
-  assert(NodeT::kType == job->n->getType());
+  static constexpr Continuation table[] = {
-  NodeT *n = static_cast<NodeT *>(job->n);
+      prefixIter<NodeTFrom, Node0>, prefixIter<NodeTFrom, Node3>,
+      prefixIter<NodeTFrom, Node16>, prefixIter<NodeTFrom, Node48>,
+      prefixIter<NodeTFrom, Node256>};
+};
 
-  TaggedNodePointer *child =
+static constexpr Continuation const *prefixIterTable[] = {
-      getChildUpdatingMaxVersion(n, job->remaining, context->writeVersion);
+    PrefixIterTable<Node0>::table,   PrefixIterTable<Node3>::table,
-  if (child == nullptr) [[unlikely]] {
+    PrefixIterTable<Node16>::table,  PrefixIterTable<Node48>::table,
-    int prefixLen = job->commonPrefixLen - job->remaining.size();
+    PrefixIterTable<Node256>::table,
-    assert(prefixLen >= 0);
+};
-    assert(job->n != nullptr);
+
-    *job->result = {
+template <class NodeTFrom, class NodeTTo>
-        job->n,
+void prefixIter(Job *job, Context *context) {
-        job->begin.subspan(prefixLen, job->begin.size() - prefixLen),
+  assert(NodeTFrom::kType == job->n->getType());
-        job->n,
+  NodeTFrom *n = static_cast<NodeTFrom *>(job->n);
-        job->end.subspan(prefixLen, job->end.size() - prefixLen),
+  assert(NodeTTo::kType == job->child->getType());
-    };
+  NodeTTo *child = static_cast<NodeTTo *>(job->child);
-    MUSTTAIL return complete(job, context);
+
+  auto key = job->remaining.subspan(1, job->remaining.size() - 1);
+  if (child->partialKeyLen > 0) {
+    int commonLen = std::min<int>(child->partialKeyLen, key.size());
+    int partialKeyIndex =
+        longestCommonPrefix(child->partialKey(), key.data(), commonLen);
+    if (partialKeyIndex < child->partialKeyLen) {
+      goto noNodeOnSearchPath;
+    }
   }
-  job->n = *child;
+
-  ++context->iterations;
+  // child is on the search path. Commit to advancing and updating max version
+  job->n = child;
+  job->remaining =
+      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->remaining.size() == 0) [[unlikely]] {
     job->endNode = job->n;
     job->begin = job->begin.subspan(job->commonPrefixLen,
@@ -4330,11 +4352,29 @@ template <class NodeT> void commonPrefixIter(Job *job, Context *context) {
     } else {
       job->continuation = beginIterTable[child->getType()];
     }
-  } else {
+    MUSTTAIL return keepGoing(job, context);
-    job->continuation = commonPrefixIterTable[child->getType()];
   }
-  __builtin_prefetch(job->n);
+
+  if (!job->getChildAndIndex(child, job->remaining.front())) [[unlikely]] {
+    goto noNodeOnSearchPath;
+  }
+
+  ++context->iterations;
+  job->continuation = PrefixIterTable<NodeTTo>::table[job->child.getType()];
+  __builtin_prefetch(job->child);
   MUSTTAIL return keepGoing(job, context);
+
+noNodeOnSearchPath:
+  int prefixLen = job->commonPrefixLen - job->remaining.size();
+  assert(prefixLen >= 0);
+  assert(job->n != nullptr);
+  *job->result = {
+      job->n,
+      job->begin.subspan(prefixLen, job->begin.size() - prefixLen),
+      job->n,
+      job->end.subspan(prefixLen, job->end.size() - prefixLen),
+  };
+  MUSTTAIL return complete(job, context);
 }
 
 template <class NodeT> void beginIter(Job *job, Context *context) {
@@ -4403,7 +4443,17 @@ void Job::init(Context *context, int index) {
 
   if (commonPrefixLen > 0) {
     // common prefix iter will set endNode
-    continuation = commonPrefixIterTable[n->getType()];
+    if (!getChildAndIndex(n, remaining.front())) [[unlikely]] {
+      *result = {
+          n,
+          begin,
+          n,
+          end,
+      };
+      continuation = complete;
+    } else {
+      continuation = prefixIterTable[n->getType()][child.getType()];
+    }
   } else if (begin.size() > 0) {
     endNode = n;
     continuation = beginIterTable[n->getType()];
@@ -4417,11 +4467,11 @@ pointWrite:
   remaining = TrivialSpan(context->writes[index].begin.p,
                           context->writes[index].begin.len);
   if (remaining.size() == 0) [[unlikely]] {
-    context->results[index] = {n, remaining};
+    *result = {n, remaining};
     continuation = complete;
   } else {
     if (!getChildAndIndex(n, remaining.front())) [[unlikely]] {
-      context->results[index] = {n, remaining};
+      *result = {n, remaining};
       continuation = complete;
     } else {
       continuation = pointIterTable[n->getType()][child.getType()];