A message's rows read by position where they are, not from a copy of them: input.rows[k] made the rows a list value (LIST_VALUE copies every row) and read the copy, so each read cost the rows' count (140's box layout: 99,067 ns a node, 4,737 now, the answers the same); rows_at in make check (a literal, a computed and a looped position, through a let and a fn's argument, past the last failing the event); no other module of aup's, Pure's or Vega's changes

1 files changed, 5 insertions, 0 deletions

diff --git a/compiler/compile.c b/compiler/compile.c
index 0fcaa1b..5c88b97 100644
--- a/compiler/compile.c
+++ b/compiler/compile.c
@@ -3738,6 +3738,11 @@ static Kind value(Compiler *c, const Expr *e, bool handler, int height) {
         return field_value(r, field);
     }
     case E_INDEX: {
+        int given = e->count == 2 ? rows_list(c, e->args[0]) : -1;
+        if (given >= 0) { /* a message's rows' item at a position: read where they are, not from a copy of them */
+            item_of(c, e->args[1], handler, height, given);
+            return item_value(c, e, given);
+        }
         Kind base = value(c, e->args[0], handler, height);
         if (base.type == LIST && e->count == 2) { /* a list value's item at a position */
             int reg = bind_list(c, e, base);