import foo
def func():
    return foo.bar()

The snippet above will generate the following code;

2 0 LOAD_GLOBAL 0 (foo)
2 LOAD_METHOD 1 (bar)
4 CALL_METHOD 0
6 RETURN_VALUE

Though this will make things harder for specializing the LOAD_ATTR for modules since now the handling of LOAD_METHOD for that case is necessary so for the imports that we can infer during the symbol analysis pass, we'll generate LOAD_ATTR+CALL_ATTR instead of LOAD_METHOD+CALL_METHOD and hopefully the generated code will get specialized via the PEP-659.

Ref: faster-cpython/ideas#55 (comment)

@mark.shannon what do you think about doing this both for import <module> and from <module> import <something>. It will definitely simplify the implementation (no need to extra visitors or flags, just using the default DEF_IMPORT one isidentical@f8f8fce) and also might help you to specialize other cases too (e.g importing submodules, from concurrent import futures).

Yes. Simpler is good.

I think it will also be better for performance:

In general, we don't know what X is in from Y import X. It could be a module or anything else.

However, if we are accessing an attribute it is quite likely to be a module or class.
For X defined by from Y import X, X is likely to be a module, class, function, or some sort of constant like a string, int or Enum.

If it is a string, int or function then it is rare to call a method on it, so we can ignore that case.
Calling methods on an Enum constant is probably not very common either (I'm guessing here)

For a module, LOAD_ATTR; CALL_FUNCTION is clearly better than LOAD_METHOD; CALL_METHOD.

For a class, specializing LOAD_ATTR is no more complex than LOAD_METHOD, probably simpler.
So, for a class LOAD_ATTR; CALL_FUNCTION is no worse than LOAD_METHOD; CALL_METHOD, and might be better.

Overall, it looks like X.foo() when X is defiend by from Y import X is best as LOAD_ATTR; CALL_FUNCTION not LOAD_METHOD; CALL_METHOD.

New changeset 1b28187 by Batuhan Taskaya in branch 'main':
bpo-44313: generate LOAD_ATTR/CALL_FUNCTION for top-level imported objects (GH-26677)
1b28187

New changeset 0d7f61d by Batuhan Taskaya in branch 'main':
bpo-44313: bump up magic (bpo-26983)
0d7f61d