Avoid switch on parent type for max version during search

ConflictSet.cpp

@@ -939,6 +939,54 @@ Node *getChild(Node *self, uint8_t index) {
   }
 }
 
+struct ChildAndMaxVersion {
+  Node *child;
+  InternalVersionT maxVersion;
+};
+
+ChildAndMaxVersion getChildAndMaxVersion(Node0 *, uint8_t) { return {}; }
+ChildAndMaxVersion getChildAndMaxVersion(Node3 *self, uint8_t index) {
+  int i = getNodeIndex(self, index);
+  if (i < 0) {
+    return {};
+  }
+  return {self->children[i], self->childMaxVersion[i]};
+}
+ChildAndMaxVersion getChildAndMaxVersion(Node16 *self, uint8_t index) {
+  int i = getNodeIndex(self, index);
+  if (i < 0) {
+    return {};
+  }
+  return {self->children[i], self->childMaxVersion[i]};
+}
+ChildAndMaxVersion getChildAndMaxVersion(Node48 *self, uint8_t index) {
+  int i = self->index[index];
+  if (i < 0) {
+    return {};
+  }
+  return {self->children[i], self->childMaxVersion[i]};
+}
+ChildAndMaxVersion getChildAndMaxVersion(Node256 *self, uint8_t index) {
+  return {self->children[index], self->childMaxVersion[index]};
+}
+
+ChildAndMaxVersion getChildAndMaxVersion(Node *self, uint8_t index) {
+  switch (self->getType()) {
+  case Type_Node0:
+    return getChildAndMaxVersion(static_cast<Node0 *>(self), index);
+  case Type_Node3:
+    return getChildAndMaxVersion(static_cast<Node3 *>(self), index);
+  case Type_Node16:
+    return getChildAndMaxVersion(static_cast<Node16 *>(self), index);
+  case Type_Node48:
+    return getChildAndMaxVersion(static_cast<Node48 *>(self), index);
+  case Type_Node256:
+    return getChildAndMaxVersion(static_cast<Node256 *>(self), index);
+  default:                   // GCOVR_EXCL_LINE
+    __builtin_unreachable(); // GCOVR_EXCL_LINE
+  }
+}
+
 template <class NodeT> Node *getChildGeqSimd(NodeT *self, int child) {
   static_assert(std::is_same_v<NodeT, Node3> || std::is_same_v<NodeT, Node16>);
 
@@ -1783,6 +1831,7 @@ int longestCommonPrefix(const uint8_t *ap, const uint8_t *bp, int cl) {
 // Performs a physical search for remaining
 struct SearchStepWise {
   Node *n;
+  InternalVersionT maxV;
   std::span<const uint8_t> remaining;
 
   SearchStepWise() {}
@@ -1795,7 +1844,8 @@ struct SearchStepWise {
     if (remaining.size() == 0) {
       return true;
     }
-    auto *child = getChild(n, remaining[0]);
+    auto [child, v] = getChildAndMaxVersion(n, remaining[0]);
+    maxV = v;
     if (child == nullptr) {
       return true;
     }
@@ -1825,12 +1875,7 @@ bool checkPointRead(Node *n, const std::span<const uint8_t> key,
   fprintf(stderr, "Check point read: %s\n", printable(key).c_str());
 #endif
   auto remaining = key;
-  auto *impl = tls->impl;
   for (;; ++tls->point_read_iterations_accum) {
-    if (maxVersion(n, impl) <= readVersion) {
-      ++tls->point_read_short_circuit_accum;
-      return true;
-    }
     if (remaining.size() == 0) {
       if (n->entryPresent) {
         return n->entry.pointVersion <= readVersion;
@@ -1839,7 +1884,7 @@ bool checkPointRead(Node *n, const std::span<const uint8_t> key,
       goto downLeftSpine;
     }
 
-    auto *child = getChild(n, remaining[0]);
+    auto [child, maxV] = getChildAndMaxVersion(n, remaining[0]);
     if (child == nullptr) {
       auto c = getChildGeq(n, remaining[0]);
       if (c != nullptr) {
@@ -1881,6 +1926,11 @@ bool checkPointRead(Node *n, const std::span<const uint8_t> key,
         goto downLeftSpine;
       }
     }
+
+    if (maxV <= readVersion) {
+      ++tls->point_read_short_circuit_accum;
+      return true;
+    }
   }
 downLeftSpine:
   for (; !n->entryPresent; n = getFirstChildExists(n)) {
@@ -1900,17 +1950,11 @@ bool checkPrefixRead(Node *n, const std::span<const uint8_t> key,
   auto remaining = key;
   auto *impl = tls->impl;
   for (;; ++tls->prefix_read_iterations_accum) {
-    auto m = maxVersion(n, impl);
     if (remaining.size() == 0) {
-      return m <= readVersion;
+      return maxVersion(n, impl) <= readVersion;
     }
 
-    if (m <= readVersion) {
+    auto [child, maxV] = getChildAndMaxVersion(n, remaining[0]);
-      ++tls->prefix_read_short_circuit_accum;
-      return true;
-    }
-
-    auto *child = getChild(n, remaining[0]);
     if (child == nullptr) {
       auto c = getChildGeq(n, remaining[0]);
       if (c != nullptr) {
@@ -1956,6 +2000,11 @@ bool checkPrefixRead(Node *n, const std::span<const uint8_t> key,
         goto downLeftSpine;
       }
     }
+
+    if (maxV <= readVersion) {
+      ++tls->prefix_read_short_circuit_accum;
+      return true;
+    }
   }
 downLeftSpine:
   for (; !n->entryPresent; n = getFirstChildExists(n)) {
@@ -2511,10 +2560,6 @@ struct CheckRangeLeftSide {
   bool ok;
 
   bool step() {
-    if (maxVersion(n, impl) <= readVersion) {
-      ok = true;
-      return true;
-    }
     if (remaining.size() == 0) {
       assert(searchPathLen >= prefixLen);
       ok = maxVersion(n, impl) <= readVersion;
@@ -2528,7 +2573,7 @@ struct CheckRangeLeftSide {
       }
     }
 
-    auto *child = getChild(n, remaining[0]);
+    auto [child, maxV] = getChildAndMaxVersion(n, remaining[0]);
     if (child == nullptr) {
       auto c = getChildGeq(n, remaining[0]);
       if (c != nullptr) {
@@ -2591,6 +2636,10 @@ struct CheckRangeLeftSide {
         return true;
       }
     }
+    if (maxV <= readVersion) {
+      ok = true;
+      return true;
+    }
     return false;
   }
 
@@ -2752,18 +2801,17 @@ bool checkRangeRead(Node *n, std::span<const uint8_t> begin,
 
   SearchStepWise search{n, begin.subspan(0, lcp)};
   Arena arena;
-  auto *impl = tls->impl;
   for (;; ++tls->range_read_iterations_accum) {
     assert(getSearchPath(arena, search.n) <=>
                begin.subspan(0, lcp - search.remaining.size()) ==
            0);
-    if (maxVersion(search.n, impl) <= readVersion) {
-      ++tls->range_read_short_circuit_accum;
-      return true;
-    }
     if (search.step()) {
       break;
     }
+    if (search.maxV <= readVersion) {
+      ++tls->range_read_short_circuit_accum;
+      return true;
+    }
   }
   assert(getSearchPath(arena, search.n) <=>
              begin.subspan(0, lcp - search.remaining.size()) ==