[issue31954] Don't prevent dict optimization by coupling with OrderedDict
INADA Naoki
report at bugs.python.org
Tue Nov 7 04:11:08 EST 2017
INADA Naoki <songofacandy at gmail.com> added the comment:
I don't know why dk_lookup is in dictkeys object. But I think
it's because sharing 1 word from all key-sharing dict.
So ma_clean flag can be in dictkeys object for same reason.
BTW, We use dk_lookup function pointer and it tooks 1 word.
But PyPy use flags for it. So they can pack other informations into same word.
static dict_lookup_func lookup_funcs = {lookdict_unicode_nodummy, lookdict_unicode, lookdict_split, lookdict};
...
unsigned int ma_clean:1;
unsigned int ma_lookup_func:2; // lookup_funcs[ma_lookup_func]
...
In this way, we can have more flags for future optimization.
(e.g. "all keys are interned string and comparing pointer is enough for searching interned key" flag).
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