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py/map: Add fast-path for hashing of map index when it is a qstr. 

Map indicies are most commonly a qstr, and adding a fast-path for hashing
of a qstr increases overall performance of the runtime.

On pyboard there is a 4% improvement in the pystone benchmark for a cost
of 20 bytes of code size.  It's about a 2% improvement on unix.
readthedocs
Damien George 2015-12-26 21:15:47 +00:00
parent e5ce5e2a43
commit bbe8d51bd9
1 changed files with 8 additions and 1 deletions
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9
py/map.c
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@ -201,7 +201,14 @@ mp_map_elem_t *mp_map_lookup(mp_map_t *map, mp_obj_t index, mp_map_lookup_kind_t
}
}
mp_uint_t hash = MP_OBJ_SMALL_INT_VALUE(mp_unary_op(MP_UNARY_OP_HASH, index));
// get hash of index, with fast path for common case of qstr
mp_uint_t hash;
if (MP_OBJ_IS_QSTR(index)) {
hash = qstr_hash(MP_OBJ_QSTR_VALUE(index));
} else {
hash = MP_OBJ_SMALL_INT_VALUE(mp_unary_op(MP_UNARY_OP_HASH, index));
}
mp_uint_t pos = hash % map->alloc;
mp_uint_t start_pos = pos;
mp_map_elem_t *avail_slot = NULL;