Speed-up dictionary constructor by about 10%.
New opcode, STORE_MAP saves the compiler from awkward stack manipulations
and specializes for dicts using PyDict_SetItem instead of PyObject_SetItem.
Old disassembly:
0 BUILD_MAP 0
3 DUP_TOP
4 LOAD_CONST 1 (1)
7 ROT_TWO
8 LOAD_CONST 2 ('x')
11 STORE_SUBSCR
12 DUP_TOP
13 LOAD_CONST 3 (2)
16 ROT_TWO
17 LOAD_CONST 4 ('y')
20 STORE_SUBSCR
New disassembly:
0 BUILD_MAP 0
3 LOAD_CONST 1 (1)
6 LOAD_CONST 2 ('x')
9 STORE_MAP
10 LOAD_CONST 3 (2)
13 LOAD_CONST 4 ('y')
16 STORE_MAP
diff --git a/Python/ceval.c b/Python/ceval.c
index d74d017..1af998d 100644
--- a/Python/ceval.c
+++ b/Python/ceval.c
@@ -2002,6 +2002,18 @@
if (x != NULL) continue;
break;
+ case STORE_MAP:
+ w = TOP(); /* key */
+ u = SECOND(); /* value */
+ v = THIRD(); /* dict */
+ STACKADJ(-2);
+ assert (PyDict_CheckExact(v));
+ err = PyDict_SetItem(v, w, u); /* v[w] = u */
+ Py_DECREF(u);
+ Py_DECREF(w);
+ if (err == 0) continue;
+ break;
+
case LOAD_ATTR:
w = GETITEM(names, oparg);
v = TOP();