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Speed-up dictionary constructor by about 10%.

Browse source 
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
This commit is contained in:
Raymond Hettinger 2007-12-18 18:26:18 +00:00
parent eb103b3577
commit effde12f5f
5 changed files with 19 additions and 5 deletions
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12
Python/ceval.c
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@ -2002,6 +2002,18 @@ PyEval_EvalFrameEx(PyFrameObject *f, int throwflag)
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();