commit 088740ecc40476fd0796a3ef6a68ee7c677eae64
author Damien George <damien.p.george@gmail.com> Tue Jan 17 15:27:37 2017 +1100
committer Damien George <damien.p.george@gmail.com> Thu Feb 16 18:38:06 2017 +1100
tree 97284e7a795fbf6e0a196bbe56234d7fff5fc74b
parent 6e769da0da2ae24cbdab50c57f0d088e137146e3

py: Optimise storage of iterator so it takes only 4 slots on Py stack.

py/compile.c

diff --git a/py/compile.c b/py/compile.c
index 4fde278..5ea7bb4 100644
--- a/py/compile.c
+++ b/py/compile.c
@@ -2887,7 +2887,7 @@
             EMIT(yield_value);
             EMIT(pop_top);
         } else {
-            EMIT_ARG(store_comp, comp->scope_cur->kind, 5 * for_depth + 6);
+            EMIT_ARG(store_comp, comp->scope_cur->kind, 4 * for_depth + 5);
         }
     } else if (MP_PARSE_NODE_IS_STRUCT_KIND(pn_iter, PN_comp_if)) {
         // if condition
@@ -3070,13 +3070,13 @@
         #endif
         }
 
-        // dummy 4 objects
+        // There are 4 slots on the stack for the iterator, and the first one is
+        // NULL to indicate that the second one points to the iterator object.
         EMIT(load_null);
-        EMIT(load_null);
+        compile_load_id(comp, qstr_arg);
         EMIT(load_null);
         EMIT(load_null);
 
-        compile_load_id(comp, qstr_arg);
         compile_scope_comp_iter(comp, pns_comp_for, pns->nodes[0], 0);
 
         if (scope->kind == SCOPE_GEN_EXPR) {