Jim Mussared 3ac8b5851e py/obj: Add slot-index mp_obj_type_t representation.
The existings mp_obj_type_t uses a sparse representation for slots for the
capability methods of the type (eg print, make_new).  This commit adds a
compact slot-index representation.  The basic idea is that where the
mp_obj_type_t struct used to have 12 pointer fields, it now has 12 uint8_t
indices, and a variable-length array of pointers.  So in the best case (no
fields used) it saves 12x4-12=36 bytes (on a 32-bit machine) and in the
common case (three fields used) it saves 9x4-12=24 bytes.

Overall with all associated changes, this slot-index representation reduces
code size by 1000 to 3000 bytes on bare-metal ports.  Performance is
marginally better on a few tests (eg about 1% better on misc_pystone.py and
misc_raytrace.py on PYBv1.1), but overall marginally worse by a percent or
so.

See issue #7542 for further analysis and discussion.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
2022-09-19 19:06:09 +10:00
..
2019-11-21 12:04:53 +11:00