Geometry Nodes: new evaluation system

This refactors the geometry nodes evaluation system. No changes for the
user are expected. At a high level the goals are:
* Support using geometry nodes outside of the geometry nodes modifier.
* Support using the evaluator infrastructure for other purposes like field evaluation.
* Support more nodes, especially when many of them are disabled behind switch nodes.
* Support doing preprocessing on node groups.

For more details see T98492.

There are fairly detailed comments in the code, but here is a high level overview
for how it works now:
* There is a new "lazy-function" system. It is similar in spirit to the multi-function
  system but with different goals. Instead of optimizing throughput for highly
  parallelizable work, this system is designed to compute only the data that is actually
  necessary. What data is necessary can be determined dynamically during evaluation.
  Many lazy-functions can be composed in a graph to form a new lazy-function, which can
  again be used in a graph etc.
* Each geometry node group is converted into a lazy-function graph prior to evaluation.
  To evaluate geometry nodes, one then just has to evaluate that graph. Node groups are
  no longer inlined into their parents.

Next steps for the evaluation system is to reduce the use of threads in some situations
to avoid overhead. Many small node groups don't benefit from multi-threading at all.
This is much easier to do now because not everything has to be inlined in one huge
node tree anymore.

Differential Revision: https://developer.blender.org/D15914

1 files changed, 607 insertions, 0 deletions

diff --git a/source/blender/nodes/intern/geometry_nodes_log.cc b/source/blender/nodes/intern/geometry_nodes_log.cc
new file mode 100644
index 00000000000..2e0ac746ac0
--- /dev/null
+++ b/source/blender/nodes/intern/geometry_nodes_log.cc
@@ -0,0 +1,607 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include "NOD_geometry_nodes_lazy_function.hh"
+#include "NOD_geometry_nodes_log.hh"
+
+#include "BKE_compute_contexts.hh"
+#include "BKE_curves.hh"
+#include "BKE_node_runtime.hh"
+
+#include "FN_field_cpp_type.hh"
+
+#include "DNA_modifier_types.h"
+#include "DNA_space_types.h"
+
+namespace blender::nodes::geo_eval_log {
+
+using fn::FieldInput;
+using fn::FieldInputs;
+
+GenericValueLog::~GenericValueLog()
+{
+  this->value.destruct();
+}
+
+FieldInfoLog::FieldInfoLog(const GField &field) : type(field.cpp_type())
+{
+  const std::shared_ptr<const fn::FieldInputs> &field_input_nodes = field.node().field_inputs();
+
+  /* Put the deduplicated field inputs into a vector so that they can be sorted below. */
+  Vector<std::reference_wrapper<const FieldInput>> field_inputs;
+  if (field_input_nodes) {
+    field_inputs.extend(field_input_nodes->deduplicated_nodes.begin(),
+                        field_input_nodes->deduplicated_nodes.end());
+  }
+
+  std::sort(
+      field_inputs.begin(), field_inputs.end(), [](const FieldInput &a, const FieldInput &b) {
+        const int index_a = (int)a.category();
+        const int index_b = (int)b.category();
+        if (index_a == index_b) {
+          return a.socket_inspection_name().size() < b.socket_inspection_name().size();
+        }
+        return index_a < index_b;
+      });
+
+  for (const FieldInput &field_input : field_inputs) {
+    this->input_tooltips.append(field_input.socket_inspection_name());
+  }
+}
+
+GeometryInfoLog::GeometryInfoLog(const GeometrySet &geometry_set)
+{
+  static std::array all_component_types = {GEO_COMPONENT_TYPE_CURVE,
+                                           GEO_COMPONENT_TYPE_INSTANCES,
+                                           GEO_COMPONENT_TYPE_MESH,
+                                           GEO_COMPONENT_TYPE_POINT_CLOUD,
+                                           GEO_COMPONENT_TYPE_VOLUME};
+
+  /* Keep track handled attribute names to make sure that we do not return the same name twice.
+   * Currently #GeometrySet::attribute_foreach does not do that. Note that this will merge
+   * attributes with the same name but different domains or data types on separate components. */
+  Set<StringRef> names;
+
+  geometry_set.attribute_foreach(
+      all_component_types,
+      true,
+      [&](const bke::AttributeIDRef &attribute_id,
+          const bke::AttributeMetaData &meta_data,
+          const GeometryComponent &UNUSED(component)) {
+        if (attribute_id.is_named() && names.add(attribute_id.name())) {
+          this->attributes.append({attribute_id.name(), meta_data.domain, meta_data.data_type});
+        }
+      });
+
+  for (const GeometryComponent *component : geometry_set.get_components_for_read()) {
+    this->component_types.append(component->type());
+    switch (component->type()) {
+      case GEO_COMPONENT_TYPE_MESH: {
+        const MeshComponent &mesh_component = *(const MeshComponent *)component;
+        MeshInfo &info = this->mesh_info.emplace();
+        info.verts_num = mesh_component.attribute_domain_size(ATTR_DOMAIN_POINT);
+        info.edges_num = mesh_component.attribute_domain_size(ATTR_DOMAIN_EDGE);
+        info.faces_num = mesh_component.attribute_domain_size(ATTR_DOMAIN_FACE);
+        break;
+      }
+      case GEO_COMPONENT_TYPE_CURVE: {
+        const CurveComponent &curve_component = *(const CurveComponent *)component;
+        CurveInfo &info = this->curve_info.emplace();
+        info.splines_num = curve_component.attribute_domain_size(ATTR_DOMAIN_CURVE);
+        break;
+      }
+      case GEO_COMPONENT_TYPE_POINT_CLOUD: {
+        const PointCloudComponent &pointcloud_component = *(const PointCloudComponent *)component;
+        PointCloudInfo &info = this->pointcloud_info.emplace();
+        info.points_num = pointcloud_component.attribute_domain_size(ATTR_DOMAIN_POINT);
+        break;
+      }
+      case GEO_COMPONENT_TYPE_INSTANCES: {
+        const InstancesComponent &instances_component = *(const InstancesComponent *)component;
+        InstancesInfo &info = this->instances_info.emplace();
+        info.instances_num = instances_component.instances_num();
+        break;
+      }
+      case GEO_COMPONENT_TYPE_EDIT: {
+        const GeometryComponentEditData &edit_component = *(
+            const GeometryComponentEditData *)component;
+        if (const bke::CurvesEditHints *curve_edit_hints =
+                edit_component.curves_edit_hints_.get()) {
+          EditDataInfo &info = this->edit_data_info.emplace();
+          info.has_deform_matrices = curve_edit_hints->deform_mats.has_value();
+          info.has_deformed_positions = curve_edit_hints->positions.has_value();
+        }
+        break;
+      }
+      case GEO_COMPONENT_TYPE_VOLUME: {
+        break;
+      }
+    }
+  }
+}
+
+/* Avoid generating these in every translation unit. */
+GeoModifierLog::GeoModifierLog() = default;
+GeoModifierLog::~GeoModifierLog() = default;
+
+GeoTreeLogger::GeoTreeLogger() = default;
+GeoTreeLogger::~GeoTreeLogger() = default;
+
+GeoNodeLog::GeoNodeLog() = default;
+GeoNodeLog::~GeoNodeLog() = default;
+
+GeoTreeLog::GeoTreeLog(GeoModifierLog *modifier_log, Vector<GeoTreeLogger *> tree_loggers)
+    : modifier_log_(modifier_log), tree_loggers_(std::move(tree_loggers))
+{
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const ComputeContextHash &hash : tree_logger->children_hashes) {
+      children_hashes_.add(hash);
+    }
+  }
+}
+
+GeoTreeLog::~GeoTreeLog() = default;
+
+void GeoTreeLogger::log_value(const bNode &node, const bNodeSocket &socket, const GPointer value)
+{
+  const CPPType &type = *value.type();
+
+  auto store_logged_value = [&](destruct_ptr<ValueLog> value_log) {
+    auto &socket_values = socket.in_out == SOCK_IN ? this->input_socket_values :
+                                                     this->output_socket_values;
+    socket_values.append({node.name, socket.identifier, std::move(value_log)});
+  };
+
+  auto log_generic_value = [&](const CPPType &type, const void *value) {
+    void *buffer = this->allocator->allocate(type.size(), type.alignment());
+    type.copy_construct(value, buffer);
+    store_logged_value(this->allocator->construct<GenericValueLog>(GMutablePointer{type, buffer}));
+  };
+
+  if (type.is<GeometrySet>()) {
+    const GeometrySet &geometry = *value.get<GeometrySet>();
+    store_logged_value(this->allocator->construct<GeometryInfoLog>(geometry));
+  }
+  else if (const auto *value_or_field_type = dynamic_cast<const fn::ValueOrFieldCPPType *>(
+               &type)) {
+    const void *value_or_field = value.get();
+    const CPPType &base_type = value_or_field_type->base_type();
+    if (value_or_field_type->is_field(value_or_field)) {
+      const GField *field = value_or_field_type->get_field_ptr(value_or_field);
+      if (field->node().depends_on_input()) {
+        store_logged_value(this->allocator->construct<FieldInfoLog>(*field));
+      }
+      else {
+        BUFFER_FOR_CPP_TYPE_VALUE(base_type, value);
+        fn::evaluate_constant_field(*field, value);
+        log_generic_value(base_type, value);
+      }
+    }
+    else {
+      const void *value = value_or_field_type->get_value_ptr(value_or_field);
+      log_generic_value(base_type, value);
+    }
+  }
+  else {
+    log_generic_value(type, value.get());
+  }
+}
+
+void GeoTreeLogger::log_viewer_node(const bNode &viewer_node,
+                                    const GeometrySet &geometry,
+                                    const GField &field)
+{
+  destruct_ptr<ViewerNodeLog> log = this->allocator->construct<ViewerNodeLog>();
+  log->geometry = geometry;
+  log->field = field;
+  log->geometry.ensure_owns_direct_data();
+  this->viewer_node_logs.append({viewer_node.name, std::move(log)});
+}
+
+void GeoTreeLog::ensure_node_warnings()
+{
+  if (reduced_node_warnings_) {
+    return;
+  }
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::WarningWithNode &warnings : tree_logger->node_warnings) {
+      this->nodes.lookup_or_add_default(warnings.node_name).warnings.append(warnings.warning);
+      this->all_warnings.append(warnings.warning);
+    }
+  }
+  for (const ComputeContextHash &child_hash : children_hashes_) {
+    GeoTreeLog &child_log = modifier_log_->get_tree_log(child_hash);
+    child_log.ensure_node_warnings();
+    const std::optional<std::string> &group_node_name =
+        child_log.tree_loggers_[0]->group_node_name;
+    if (group_node_name.has_value()) {
+      this->nodes.lookup_or_add_default(*group_node_name).warnings.extend(child_log.all_warnings);
+    }
+    this->all_warnings.extend(child_log.all_warnings);
+  }
+  reduced_node_warnings_ = true;
+}
+
+void GeoTreeLog::ensure_node_run_time()
+{
+  if (reduced_node_run_times_) {
+    return;
+  }
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::NodeExecutionTime &timings : tree_logger->node_execution_times) {
+      const std::chrono::nanoseconds duration = timings.end - timings.start;
+      this->nodes.lookup_or_add_default_as(timings.node_name).run_time += duration;
+      this->run_time_sum += duration;
+    }
+  }
+  for (const ComputeContextHash &child_hash : children_hashes_) {
+    GeoTreeLog &child_log = modifier_log_->get_tree_log(child_hash);
+    child_log.ensure_node_run_time();
+    const std::optional<std::string> &group_node_name =
+        child_log.tree_loggers_[0]->group_node_name;
+    if (group_node_name.has_value()) {
+      this->nodes.lookup_or_add_default(*group_node_name).run_time += child_log.run_time_sum;
+    }
+    this->run_time_sum += child_log.run_time_sum;
+  }
+  reduced_node_run_times_ = true;
+}
+
+void GeoTreeLog::ensure_socket_values()
+{
+  if (reduced_socket_values_) {
+    return;
+  }
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::SocketValueLog &value_log_data : tree_logger->input_socket_values) {
+      this->nodes.lookup_or_add_as(value_log_data.node_name)
+          .input_values_.add(value_log_data.socket_identifier, value_log_data.value.get());
+    }
+    for (const GeoTreeLogger::SocketValueLog &value_log_data : tree_logger->output_socket_values) {
+      this->nodes.lookup_or_add_as(value_log_data.node_name)
+          .output_values_.add(value_log_data.socket_identifier, value_log_data.value.get());
+    }
+  }
+  reduced_socket_values_ = true;
+}
+
+void GeoTreeLog::ensure_viewer_node_logs()
+{
+  if (reduced_viewer_node_logs_) {
+    return;
+  }
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::ViewerNodeLogWithNode &viewer_log : tree_logger->viewer_node_logs) {
+      this->viewer_node_logs.add(viewer_log.node_name, viewer_log.viewer_log.get());
+    }
+  }
+  reduced_viewer_node_logs_ = true;
+}
+
+void GeoTreeLog::ensure_existing_attributes()
+{
+  if (reduced_existing_attributes_) {
+    return;
+  }
+  this->ensure_socket_values();
+
+  Set<StringRef> names;
+
+  auto handle_value_log = [&](const ValueLog &value_log) {
+    const GeometryInfoLog *geo_log = dynamic_cast<const GeometryInfoLog *>(&value_log);
+    if (geo_log == nullptr) {
+      return;
+    }
+    for (const GeometryAttributeInfo &attribute : geo_log->attributes) {
+      if (names.add(attribute.name)) {
+        this->existing_attributes.append(&attribute);
+      }
+    }
+  };
+
+  for (const GeoNodeLog &node_log : this->nodes.values()) {
+    for (const ValueLog *value_log : node_log.input_values_.values()) {
+      handle_value_log(*value_log);
+    }
+    for (const ValueLog *value_log : node_log.output_values_.values()) {
+      handle_value_log(*value_log);
+    }
+  }
+  reduced_existing_attributes_ = true;
+}
+
+void GeoTreeLog::ensure_used_named_attributes()
+{
+  if (reduced_used_named_attributes_) {
+    return;
+  }
+
+  auto add_attribute = [&](const StringRef node_name,
+                           const StringRef attribute_name,
+                           const NamedAttributeUsage &usage) {
+    this->nodes.lookup_or_add_as(node_name).used_named_attributes.lookup_or_add_as(attribute_name,
+                                                                                   usage) |= usage;
+    this->used_named_attributes.lookup_or_add_as(attribute_name, usage) |= usage;
+  };
+
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::AttributeUsageWithNode &item : tree_logger->used_named_attributes) {
+      add_attribute(item.node_name, item.attribute_name, item.usage);
+    }
+  }
+  for (const ComputeContextHash &child_hash : children_hashes_) {
+    GeoTreeLog &child_log = modifier_log_->get_tree_log(child_hash);
+    child_log.ensure_used_named_attributes();
+    if (const std::optional<std::string> &group_node_name =
+            child_log.tree_loggers_[0]->group_node_name) {
+      for (const auto &item : child_log.used_named_attributes.items()) {
+        add_attribute(*group_node_name, item.key, item.value);
+      }
+    }
+  }
+  reduced_used_named_attributes_ = true;
+}
+
+void GeoTreeLog::ensure_debug_messages()
+{
+  if (reduced_debug_messages_) {
+    return;
+  }
+  for (GeoTreeLogger *tree_logger : tree_loggers_) {
+    for (const GeoTreeLogger::DebugMessage &debug_message : tree_logger->debug_messages) {
+      this->nodes.lookup_or_add_as(debug_message.node_name)
+          .debug_messages.append(debug_message.message);
+    }
+  }
+  reduced_debug_messages_ = true;
+}
+
+ValueLog *GeoTreeLog::find_socket_value_log(const bNodeSocket &query_socket)
+{
+  /**
+   * Geometry nodes does not log values for every socket. That would produce a lot of redundant
+   * data,because often many linked sockets have the same value. To find the logged value for a
+   * socket one might have to look at linked sockets as well.
+   */
+
+  BLI_assert(reduced_socket_values_);
+  if (query_socket.is_multi_input()) {
+    /* Not supported currently. */
+    return nullptr;
+  }
+
+  Set<const bNodeSocket *> added_sockets;
+  Stack<const bNodeSocket *> sockets_to_check;
+  sockets_to_check.push(&query_socket);
+  added_sockets.add(&query_socket);
+
+  while (!sockets_to_check.is_empty()) {
+    const bNodeSocket &socket = *sockets_to_check.pop();
+    const bNode &node = socket.owner_node();
+    if (GeoNodeLog *node_log = this->nodes.lookup_ptr(node.name)) {
+      ValueLog *value_log = socket.is_input() ?
+                                node_log->input_values_.lookup_default(socket.identifier,
+                                                                       nullptr) :
+                                node_log->output_values_.lookup_default(socket.identifier,
+                                                                        nullptr);
+      if (value_log != nullptr) {
+        return value_log;
+      }
+    }
+
+    if (socket.is_input()) {
+      const Span<const bNodeLink *> links = socket.directly_linked_links();
+      for (const bNodeLink *link : links) {
+        const bNodeSocket &from_socket = *link->fromsock;
+        if (added_sockets.add(&from_socket)) {
+          sockets_to_check.push(&from_socket);
+        }
+      }
+    }
+    else {
+      if (node.is_reroute()) {
+        const bNodeSocket &input_socket = node.input_socket(0);
+        if (added_sockets.add(&input_socket)) {
+          sockets_to_check.push(&input_socket);
+        }
+        const Span<const bNodeLink *> links = input_socket.directly_linked_links();
+        for (const bNodeLink *link : links) {
+          const bNodeSocket &from_socket = *link->fromsock;
+          if (added_sockets.add(&from_socket)) {
+            sockets_to_check.push(&from_socket);
+          }
+        }
+      }
+      else if (node.is_muted()) {
+        if (const bNodeSocket *input_socket = socket.internal_link_input()) {
+          if (added_sockets.add(input_socket)) {
+            sockets_to_check.push(input_socket);
+          }
+          const Span<const bNodeLink *> links = input_socket->directly_linked_links();
+          for (const bNodeLink *link : links) {
+            const bNodeSocket &from_socket = *link->fromsock;
+            if (added_sockets.add(&from_socket)) {
+              sockets_to_check.push(&from_socket);
+            }
+          }
+        }
+      }
+    }
+  }
+
+  return nullptr;
+}
+
+GeoTreeLogger &GeoModifierLog::get_local_tree_logger(const ComputeContext &compute_context)
+{
+  LocalData &local_data = data_per_thread_.local();
+  Map<ComputeContextHash, destruct_ptr<GeoTreeLogger>> &local_tree_loggers =
+      local_data.tree_logger_by_context;
+  destruct_ptr<GeoTreeLogger> &tree_logger_ptr = local_tree_loggers.lookup_or_add_default(
+      compute_context.hash());
+  if (tree_logger_ptr) {
+    return *tree_logger_ptr;
+  }
+  tree_logger_ptr = local_data.allocator.construct<GeoTreeLogger>();
+  GeoTreeLogger &tree_logger = *tree_logger_ptr;
+  tree_logger.allocator = &local_data.allocator;
+  const ComputeContext *parent_compute_context = compute_context.parent();
+  if (parent_compute_context != nullptr) {
+    tree_logger.parent_hash = parent_compute_context->hash();
+    GeoTreeLogger &parent_logger = this->get_local_tree_logger(*parent_compute_context);
+    parent_logger.children_hashes.append(compute_context.hash());
+  }
+  if (const bke::NodeGroupComputeContext *node_group_compute_context =
+          dynamic_cast<const bke::NodeGroupComputeContext *>(&compute_context)) {
+    tree_logger.group_node_name.emplace(node_group_compute_context->node_name());
+  }
+  return tree_logger;
+}
+
+GeoTreeLog &GeoModifierLog::get_tree_log(const ComputeContextHash &compute_context_hash)
+{
+  GeoTreeLog &reduced_tree_log = *tree_logs_.lookup_or_add_cb(compute_context_hash, [&]() {
+    Vector<GeoTreeLogger *> tree_logs;
+    for (LocalData &local_data : data_per_thread_) {
+      destruct_ptr<GeoTreeLogger> *tree_log = local_data.tree_logger_by_context.lookup_ptr(
+          compute_context_hash);
+      if (tree_log != nullptr) {
+        tree_logs.append(tree_log->get());
+      }
+    }
+    return std::make_unique<GeoTreeLog>(this, std::move(tree_logs));
+  });
+  return reduced_tree_log;
+}
+
+struct ObjectAndModifier {
+  const Object *object;
+  const NodesModifierData *nmd;
+};
+
+static std::optional<ObjectAndModifier> get_modifier_for_node_editor(const SpaceNode &snode)
+{
+  if (snode.id == nullptr) {
+    return std::nullopt;
+  }
+  if (GS(snode.id->name) != ID_OB) {
+    return std::nullopt;
+  }
+  const Object *object = reinterpret_cast<Object *>(snode.id);
+  const NodesModifierData *used_modifier = nullptr;
+  if (snode.flag & SNODE_PIN) {
+    LISTBASE_FOREACH (const ModifierData *, md, &object->modifiers) {
+      if (md->type == eModifierType_Nodes) {
+        const NodesModifierData *nmd = reinterpret_cast<const NodesModifierData *>(md);
+        /* Would be good to store the name of the pinned modifier in the node editor. */
+        if (nmd->node_group == snode.nodetree) {
+          used_modifier = nmd;
+          break;
+        }
+      }
+    }
+  }
+  else {
+    LISTBASE_FOREACH (const ModifierData *, md, &object->modifiers) {
+      if (md->type == eModifierType_Nodes) {
+        const NodesModifierData *nmd = reinterpret_cast<const NodesModifierData *>(md);
+        if (nmd->node_group == snode.nodetree) {
+          if (md->flag & eModifierFlag_Active) {
+            used_modifier = nmd;
+            break;
+          }
+        }
+      }
+    }
+  }
+  if (used_modifier == nullptr) {
+    return std::nullopt;
+  }
+  return ObjectAndModifier{object, used_modifier};
+}
+
+GeoTreeLog *GeoModifierLog::get_tree_log_for_node_editor(const SpaceNode &snode)
+{
+  std::optional<ObjectAndModifier> object_and_modifier = get_modifier_for_node_editor(snode);
+  if (!object_and_modifier) {
+    return nullptr;
+  }
+  GeoModifierLog *modifier_log = static_cast<GeoModifierLog *>(
+      object_and_modifier->nmd->runtime_eval_log);
+  if (modifier_log == nullptr) {
+    return nullptr;
+  }
+  Vector<const bNodeTreePath *> tree_path = snode.treepath;
+  if (tree_path.is_empty()) {
+    return nullptr;
+  }
+  ComputeContextBuilder compute_context_builder;
+  compute_context_builder.push<bke::ModifierComputeContext>(
+      object_and_modifier->nmd->modifier.name);
+  for (const bNodeTreePath *path_item : tree_path.as_span().drop_front(1)) {
+    compute_context_builder.push<bke::NodeGroupComputeContext>(path_item->node_name);
+  }
+  return &modifier_log->get_tree_log(compute_context_builder.hash());
+}
+
+const ViewerNodeLog *GeoModifierLog::find_viewer_node_log_for_spreadsheet(
+    const SpaceSpreadsheet &sspreadsheet)
+{
+  Vector<const SpreadsheetContext *> context_path = sspreadsheet.context_path;
+  if (context_path.size() < 3) {
+    return nullptr;
+  }
+  if (context_path[0]->type != SPREADSHEET_CONTEXT_OBJECT) {
+    return nullptr;
+  }
+  if (context_path[1]->type != SPREADSHEET_CONTEXT_MODIFIER) {
+    return nullptr;
+  }
+  const SpreadsheetContextObject *object_context =
+      reinterpret_cast<const SpreadsheetContextObject *>(context_path[0]);
+  const SpreadsheetContextModifier *modifier_context =
+      reinterpret_cast<const SpreadsheetContextModifier *>(context_path[1]);
+  if (object_context->object == nullptr) {
+    return nullptr;
+  }
+  NodesModifierData *nmd = nullptr;
+  LISTBASE_FOREACH (ModifierData *, md, &object_context->object->modifiers) {
+    if (STREQ(md->name, modifier_context->modifier_name)) {
+      if (md->type == eModifierType_Nodes) {
+        nmd = reinterpret_cast<NodesModifierData *>(md);
+      }
+    }
+  }
+  if (nmd == nullptr) {
+    return nullptr;
+  }
+  if (nmd->runtime_eval_log == nullptr) {
+    return nullptr;
+  }
+  nodes::geo_eval_log::GeoModifierLog *modifier_log =
+      static_cast<nodes::geo_eval_log::GeoModifierLog *>(nmd->runtime_eval_log);
+
+  ComputeContextBuilder compute_context_builder;
+  compute_context_builder.push<bke::ModifierComputeContext>(modifier_context->modifier_name);
+  for (const SpreadsheetContext *context : context_path.as_span().drop_front(2).drop_back(1)) {
+    if (context->type != SPREADSHEET_CONTEXT_NODE) {
+      return nullptr;
+    }
+    const SpreadsheetContextNode &node_context = *reinterpret_cast<const SpreadsheetContextNode *>(
+        context);
+    compute_context_builder.push<bke::NodeGroupComputeContext>(node_context.node_name);
+  }
+  const ComputeContextHash context_hash = compute_context_builder.hash();
+  nodes::geo_eval_log::GeoTreeLog &tree_log = modifier_log->get_tree_log(context_hash);
+  tree_log.ensure_viewer_node_logs();
+
+  const SpreadsheetContext *last_context = context_path.last();
+  if (last_context->type != SPREADSHEET_CONTEXT_NODE) {
+    return nullptr;
+  }
+  const SpreadsheetContextNode &last_node_context =
+      *reinterpret_cast<const SpreadsheetContextNode *>(last_context);
+  const ViewerNodeLog *viewer_log = tree_log.viewer_node_logs.lookup(last_node_context.node_name);
+  return viewer_log;
+}
+
+}  // namespace blender::nodes::geo_eval_log