Improve codegen in freeAndMakeCapacityAtLeast

ConflictSet.cpp

@@ -215,9 +215,6 @@ struct Node {
   uint8_t parentsIndex;
   /* end section that's copied to the next node */
 
-  // These survive the free list round trip unscathed, and are only written by
-  // BoundedFreeListAllocator
-
   uint8_t *partialKey();
 
   Type getType() const { return type; }
@@ -252,8 +249,17 @@ struct Node3 : Node {
   uint8_t index[kMaxNodes];
   Child children[kMaxNodes];
   uint8_t *partialKey() { return (uint8_t *)(this + 1); }
+
+  void copyChildrenAndKeyFrom(const Node3 &other);
 };
 
+void Node3::copyChildrenAndKeyFrom(const Node3 &other) {
+  assert(numChildren == other.numChildren);
+  assert(partialKeyLen == other.partialKeyLen);
+  memcpy(index, other.index,
+         sizeof(*this) - offsetof(Node3, index) + partialKeyLen);
+}
+
 struct Node16 : Node {
   constexpr static auto kType = Type_Node16;
   constexpr static auto kMaxNodes = 16;
@@ -261,8 +267,20 @@ struct Node16 : Node {
   uint8_t index[kMaxNodes];
   Child children[kMaxNodes];
   uint8_t *partialKey() { return (uint8_t *)(this + 1); }
+
+  void copyChildrenAndKeyFrom(const Node16 &other);
 };
 
+void Node16::copyChildrenAndKeyFrom(const Node16 &other) {
+  assert(numChildren == other.numChildren);
+  assert(partialKeyLen == other.partialKeyLen);
+  memcpy(index, other.index, sizeof(index));
+  for (int i = 0; i < numChildren; ++i) {
+    children[i] = other.children[i];
+  }
+  memcpy(partialKey(), &other + 1, partialKeyLen);
+}
+
 struct Node48 : Node {
   constexpr static auto kType = Type_Node48;
   BitSet bitSet;
@@ -859,12 +877,7 @@ void freeAndMakeCapacityAtLeast(Node *&self, int capacity,
     auto *newSelf = allocators->node3.allocate(capacity);
     memcpy((char *)newSelf + kNodeCopyBegin, (char *)self + kNodeCopyBegin,
            kNodeCopySize);
-    memcpy(newSelf->partialKey(), self3->partialKey(), self->partialKeyLen);
+    newSelf->copyChildrenAndKeyFrom(*self3);
-    // TODO replace with memcpy?
-    for (int i = 0; i < Node3::kMaxNodes; ++i) {
-      newSelf->index[i] = self3->index[i];
-      newSelf->children[i] = self3->children[i];
-    }
     getInTree(self, impl) = newSelf;
     setChildrenParents(newSelf);
     if constexpr (kUseFreeList) {
@@ -880,12 +893,7 @@ void freeAndMakeCapacityAtLeast(Node *&self, int capacity,
     auto *newSelf = allocators->node16.allocate(capacity);
     memcpy((char *)newSelf + kNodeCopyBegin, (char *)self + kNodeCopyBegin,
            kNodeCopySize);
-    memcpy(newSelf->partialKey(), self16->partialKey(), self->partialKeyLen);
+    newSelf->copyChildrenAndKeyFrom(*self16);
-    // TODO replace with memcpy?
-    for (int i = 0; i < Node16::kMaxNodes; ++i) {
-      newSelf->index[i] = self16->index[i];
-      newSelf->children[i] = self16->children[i];
-    }
     getInTree(self, impl) = newSelf;
     setChildrenParents(newSelf);
     if constexpr (kUseFreeList) {