Add Type template parameter to maybeDownsize to avoid branch

ConflictSet.cpp

@@ -1086,7 +1086,7 @@ void maybeDecreaseCapacity(Node *&self, NodeAllocators *allocators,
                                                      allocators, impl);
 }
 
-// TODO fuse into erase child so we don't need to repeat branches on type
+template <Type kType>
 void maybeDownsize(Node *self, NodeAllocators *allocators,
                    ConflictSet::Impl *impl, Node *&dontInvalidate) {
 
@@ -1094,7 +1094,9 @@ void maybeDownsize(Node *self, NodeAllocators *allocators,
   fprintf(stderr, "maybeDownsize: %s\n", getSearchPathPrintable(self).c_str());
 #endif
 
-  switch (self->getType()) {
+  assert(self->getType() == kType);
+  static_assert(kType != Type_Node0);
+  switch (kType) {
   case Type_Node0:
     __builtin_unreachable(); // GCOVR_EXCL_LINE
   case Type_Node3: {
@@ -1198,7 +1200,24 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
 
   if (self->numChildren != 0) {
     const bool update = result == dontInvalidate;
-    maybeDownsize(self, allocators, impl, result);
+    switch (self->getType()) {
+    case Type_Node0:
+      __builtin_unreachable(); // GCOVR_EXCL_LINE
+    case Type_Node3:
+      maybeDownsize<Type_Node3>(self, allocators, impl, result);
+      break;
+    case Type_Node16:
+      maybeDownsize<Type_Node16>(self, allocators, impl, result);
+      break;
+    case Type_Node48:
+      maybeDownsize<Type_Node48>(self, allocators, impl, result);
+      break;
+    case Type_Node256:
+      maybeDownsize<Type_Node256>(self, allocators, impl, result);
+      break;
+    default:                   // GCOVR_EXCL_LINE
+      __builtin_unreachable(); // GCOVR_EXCL_LINE
+    }
     if (update) {
       dontInvalidate = result;
     }
@@ -1238,6 +1257,18 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
     memmove(parent3->children + nodeIndex, parent3->children + nodeIndex + 1,
             sizeof(parent3->children[0]) *
                 (parent->numChildren - (nodeIndex + 1)));
+
+    --parent->numChildren;
+    if (parent->numChildren == 0 && !parent->entryPresent &&
+        parent->parent != nullptr) {
+      return erase(parent, allocators, impl, dontInvalidate);
+    } else {
+      const bool update = result == dontInvalidate;
+      maybeDownsize<Type_Node3>(parent, allocators, impl, result);
+      if (update) {
+        dontInvalidate = result;
+      }
+    }
   } break;
   case Type_Node16: {
     auto *parent16 = static_cast<Node16 *>(parent);
@@ -1249,6 +1280,18 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
     memmove(parent16->children + nodeIndex, parent16->children + nodeIndex + 1,
             sizeof(parent16->children[0]) *
                 (parent->numChildren - (nodeIndex + 1)));
+
+    --parent->numChildren;
+    if (parent->numChildren == 0 && !parent->entryPresent &&
+        parent->parent != nullptr) {
+      return erase(parent, allocators, impl, dontInvalidate);
+    } else {
+      const bool update = result == dontInvalidate;
+      maybeDownsize<Type_Node16>(parent, allocators, impl, result);
+      if (update) {
+        dontInvalidate = result;
+      }
+    }
   } break;
   case Type_Node48: {
     auto *parent48 = static_cast<Node48 *>(parent);
@@ -1264,27 +1307,40 @@ Node *erase(Node *self, NodeAllocators *allocators, ConflictSet::Impl *impl,
       parent48->index[parent48->children[toRemoveChildrenIndex]
                           .child->parentsIndex] = toRemoveChildrenIndex;
     }
+
+    --parent->numChildren;
+    if (parent->numChildren == 0 && !parent->entryPresent &&
+        parent->parent != nullptr) {
+      return erase(parent, allocators, impl, dontInvalidate);
+    } else {
+      const bool update = result == dontInvalidate;
+      maybeDownsize<Type_Node48>(parent, allocators, impl, result);
+      if (update) {
+        dontInvalidate = result;
+      }
+    }
   } break;
   case Type_Node256: {
     auto *parent256 = static_cast<Node256 *>(parent);
     parent256->bitSet.reset(parentsIndex);
     parent256->children[parentsIndex].child = nullptr;
+
+    --parent->numChildren;
+    if (parent->numChildren == 0 && !parent->entryPresent &&
+        parent->parent != nullptr) {
+      return erase(parent, allocators, impl, dontInvalidate);
+    } else {
+      const bool update = result == dontInvalidate;
+      maybeDownsize<Type_Node256>(parent, allocators, impl, result);
+      if (update) {
+        dontInvalidate = result;
+      }
+    }
   } break;
   default:                   // GCOVR_EXCL_LINE
     __builtin_unreachable(); // GCOVR_EXCL_LINE
   }
 
-  --parent->numChildren;
-  if (parent->numChildren == 0 && !parent->entryPresent &&
-      parent->parent != nullptr) {
-    return erase(parent, allocators, impl, dontInvalidate);
-  } else {
-    const bool update = result == dontInvalidate;
-    maybeDownsize(parent, allocators, impl, result);
-    if (update) {
-      dontInvalidate = result;
-    }
-  }
   return result;
 }