[mypyc] Avoid cyclic reference in nested functions#16268
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ilevkivskyi
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Oct 17, 2023
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Looks great! Just one suggestion for a test.
| return any( | ||
| has_nested_func_self_reference(builder, nested) | ||
| for nested in builder.encapsulating_funcs.get(fitem, []) | ||
| ) |
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I think it may be worth testing mutually recursive functions, something involving:
def f():
def g():
h()
def h():
g()
return g, hor are we already testing this?
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Yeah, we already have at least the test case testNestedFunctions2 in mypyc/test-data/run-functions.test (mutual_recursion).
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Mypyc used to always put nested functions into the environment object, which results
in cyclic references, since the function object contains a reference to the environment.
Now we only do this if the body of a nested function refers to a nested function (e.g.
due to a recursive call). This means that in the majority of cases we can avoid the
cyclic reference.
This speeds up self check by an impressive 7%. I'm not sure exactly why the impact
is so big, but spending less time in the cyclic garbage collector is probably a big part.