let fast path allocate uninitialized cell values

5 files changed, 40 insertions, 3 deletions

diff --git a/eval/src/vespa/eval/eval/fast_value.cpp b/eval/src/vespa/eval/eval/fast_value.cpp
index 2e8226257a4..aeea49835cd 100644
--- a/eval/src/vespa/eval/eval/fast_value.cpp
+++ b/eval/src/vespa/eval/eval/fast_value.cpp
@@ -15,6 +15,9 @@ struct CreateFastValueBuilderBase {
             size_t num_mapped_dims, size_t subspace_size, size_t expected_subspaces)
     {
         assert(check_cell_type<T>(type.cell_type()));
+        if (num_mapped_dims == 0) {
+            return std::make_unique<FastDenseValue<T>>(type, subspace_size);
+        }
         return std::make_unique<FastValue<T>>(type, num_mapped_dims, subspace_size, expected_subspaces);
     }
 };
diff --git a/eval/src/vespa/eval/eval/fast_value.hpp b/eval/src/vespa/eval/eval/fast_value.hpp
index 49b4cdc0a64..05cd7bf0ec3 100644
--- a/eval/src/vespa/eval/eval/fast_value.hpp
+++ b/eval/src/vespa/eval/eval/fast_value.hpp
@@ -253,6 +253,40 @@ template <typename T> FastValue<T>::~FastValue() = default;
 
 //-----------------------------------------------------------------------------
 
+template <typename T>
+struct FastDenseValue final : Value, ValueBuilder<T> {
+
+    ValueType my_type;
+    FastCells<T> my_cells;
+
+    FastDenseValue(const ValueType &type_in, size_t subspace_size_in)
+        : my_type(type_in), my_cells(subspace_size_in)
+    {
+        my_cells.add_cells(subspace_size_in);
+    }
+    ~FastDenseValue() override;
+    const ValueType &type() const override { return my_type; }
+    const Value::Index &index() const override { return TrivialIndex::get(); }
+    TypedCells cells() const override { return TypedCells(my_cells.memory, get_cell_type<T>(), my_cells.size); }
+    ArrayRef<T> add_subspace(ConstArrayRef<vespalib::stringref>) override {
+        return ArrayRef<T>(my_cells.get(0), my_cells.size);
+    }
+    std::unique_ptr<Value> build(std::unique_ptr<ValueBuilder<T>> self) override {
+        ValueBuilder<T>* me = this;
+        assert(me == self.get());
+        self.release();
+        return std::unique_ptr<Value>(this);
+    }
+    MemoryUsage get_memory_usage() const override {
+        MemoryUsage usage = self_memory_usage<FastValue<T>>();
+        usage.merge(my_cells.estimate_extra_memory_usage());
+        return usage;
+    }
+};
+template <typename T> FastDenseValue<T>::~FastDenseValue() = default;
+
+//-----------------------------------------------------------------------------
+
 template <typename LCT, typename RCT, typename OCT, typename Fun>
 const Value &
 FastValueIndex::sparse_full_overlap_join(const ValueType &res_type, const Fun &fun,
diff --git a/eval/src/vespa/eval/instruction/generic_concat.cpp b/eval/src/vespa/eval/instruction/generic_concat.cpp
index eaa2dbf95ae..7a2280c5db7 100644
--- a/eval/src/vespa/eval/instruction/generic_concat.cpp
+++ b/eval/src/vespa/eval/instruction/generic_concat.cpp
@@ -95,7 +95,7 @@ void my_dense_simple_concat_op(State &state, uint64_t param_in) {
     const Value &rhs = state.peek(0);
     const auto a = lhs.cells().typify<LCT>();
     const auto b = rhs.cells().typify<RCT>();
-    ArrayRef<OCT> result = state.stash.create_array<OCT>(a.size() + b.size());
+    ArrayRef<OCT> result = state.stash.create_uninitialized_array<OCT>(a.size() + b.size());
     auto pos = result.begin();
     for (size_t i = 0; i < a.size(); ++i) {
         *pos++ = a[i];
diff --git a/eval/src/vespa/eval/instruction/generic_join.cpp b/eval/src/vespa/eval/instruction/generic_join.cpp
index 86720d6e539..b7648793e5a 100644
--- a/eval/src/vespa/eval/instruction/generic_join.cpp
+++ b/eval/src/vespa/eval/instruction/generic_join.cpp
@@ -114,7 +114,7 @@ void my_dense_join_op(State &state, uint64_t param_in) {
     Fun fun(param.function);
     auto lhs_cells = state.peek(1).cells().typify<LCT>();
     auto rhs_cells = state.peek(0).cells().typify<RCT>();
-    ArrayRef<OCT> out_cells = state.stash.create_array<OCT>(param.dense_plan.out_size);
+    ArrayRef<OCT> out_cells = state.stash.create_uninitialized_array<OCT>(param.dense_plan.out_size);
     OCT *dst = out_cells.begin();
     auto join_cells = [&](size_t lhs_idx, size_t rhs_idx) { *dst++ = fun(lhs_cells[lhs_idx], rhs_cells[rhs_idx]); };
     param.dense_plan.execute(0, 0, join_cells);
diff --git a/eval/src/vespa/eval/instruction/generic_map.cpp b/eval/src/vespa/eval/instruction/generic_map.cpp
index 272c8b7fc35..c24f6645f70 100644
--- a/eval/src/vespa/eval/instruction/generic_map.cpp
+++ b/eval/src/vespa/eval/instruction/generic_map.cpp
@@ -22,7 +22,7 @@ void my_generic_map_op(State &state, uint64_t param_in) {
     Func function(to_map_fun(param_in));
     const Value &a = state.peek(0);
     auto input_cells = a.cells().typify<CT>();
-    auto output_cells = state.stash.create_array<CT>(input_cells.size());
+    auto output_cells = state.stash.create_uninitialized_array<CT>(input_cells.size());
     auto pos = output_cells.begin();
     for (CT value : input_cells) {
         *pos++ = (CT) function(value);