Merge pull request #14290 from vespa-engine/arnej/optimize-copy-cells

Arnej/optimize copy cells

1 files changed, 7 insertions, 2 deletions

diff --git a/eval/src/vespa/eval/tensor/sparse/sparse_tensor.cpp b/eval/src/vespa/eval/tensor/sparse/sparse_tensor.cpp
index db35de6786d..b2bd9330160 100644
--- a/eval/src/vespa/eval/tensor/sparse/sparse_tensor.cpp
+++ b/eval/src/vespa/eval/tensor/sparse/sparse_tensor.cpp
@@ -29,10 +29,15 @@ using Cells = SparseTensor::Cells;
 void
 copyCells(Cells &cells, const Cells &cells_in, Stash &stash)
 {
-    for (const auto &cell : cells_in) {
+    // copy the exact hashtable structure:
+    cells = cells_in;
+    // copy the actual contents of the addresses,
+    // and update the pointers inside the hashtable
+    // keys so they point to our copy:
+    for (auto &cell : cells) {
         SparseTensorAddressRef oldRef = cell.first;
         SparseTensorAddressRef newRef(oldRef, stash);
-        cells[newRef] = cell.second;
+        cell.first = newRef;
     }
 }