1 files changed, 24 insertions, 0 deletions
diff --git a/erts/emulator/beam/emu/instrs.tab b/erts/emulator/beam/emu/instrs.tab
index 2c794aa4b0..88e6da9bf1 100644
--- a/erts/emulator/beam/emu/instrs.tab
+++ b/erts/emulator/beam/emu/instrs.tab
@@ -762,6 +762,30 @@ self(Dst) {
     $Dst = c_p->common.id;
 }
 
+i_update_record(Size, Src, Dst, Offset, Element) {
+    Eterm *untagged_source = tuple_val($Src);
+    Uint size_on_heap = $Size + 1;
+
+    /* Copy the entire tuple up-front, mimicking the behavior of the old
+     * setelement/3 + set_tuple_element method. This overwrites every field
+     * we're setting, but that cost is generally pretty small. */
+    sys_memcpy(HTOP, untagged_source, size_on_heap * sizeof(Eterm));
+    HTOP[$Offset] = $Element;
+
+    /* We stash the contents of the destination register in SCRATCH_X_REG in
+     * case it's used in subsequent `i_update_record_continue` instructions.
+     * The updates have been rewritten accordingly. */
+    reg[SCRATCH_X_REG] = $Dst;
+    $Dst = make_tuple(HTOP);
+
+    HTOP += size_on_heap;
+}
+
+i_update_record_continue(OffsetFromEnd, Element) {
+    Sint offset = -(Sint)$OffsetFromEnd;
+    HTOP[offset] = $Element;
+}
+
 set_tuple_element(Element, Tuple, Offset) {
     Eterm* p;