Specialising LOAD_ATTR for mutable class attributes #93657

Fidget-Spinner · 2022-06-09T18:24:48Z

Currently the following code doesn't specialise:

from enum import Enum
class Color(Enum):
    RED = 1
    GREEN = 2
    BLUE = 3

def f():
 for _ in range(10):
  Color.RED

f()

This use pattern is very common in enums and also the recommended way to check constants in pattern matching. Specialising for ~~this~~ all mutable class attributes should speed up those use cases.

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rhettinger · 2022-06-09T20:25:15Z

I don't see any reason to preference one namespace over another. I expect that instance namespaces will be dominant in practice, followed by some mix of class namespaces, module namespaces, SimpleNamespaces, and descriptors. In practice, non-enum attribute lookups dominate the Python world.

Also the mention on Enums in docs was a bit gratuitous. The primary advantages of an Enum over a regular class namespace is in how the object print and that they can be iterated. But when used in a case statement, those features aren't used by the implementation and are not accessible by the user.

Fidget-Spinner · 2022-06-10T03:28:17Z

I misphrased. When specializing for enums it would specialize for all mutable class attributes, not just enums. I just pointed out the enum pattern to justify spending the time and code. I don't plan to really specialise just for the enum type (I'm not sure how to even do that to begin with).

Fidget-Spinner · 2022-06-10T04:12:29Z

I'm going to wait until #93429 is merged because that makes LOAD_ATTR more generic (and also gives me more cache to work with).

Fidget-Spinner added type-feature performance interpreter-core labels Jun 9, 2022

Fidget-Spinner changed the title ~~Optimizing LOAD_ATTR for Enums/mutable class attributes~~ Specialising LOAD_ATTR for Enums/mutable class attributes Jun 9, 2022

Fidget-Spinner self-assigned this Jun 9, 2022

Fidget-Spinner changed the title ~~Specialising LOAD_ATTR for Enums/mutable class attributes~~ Specialising LOAD_ATTR for mutable class attributes Jun 10, 2022

Specialising LOAD_ATTR for mutable class attributes #93657

Specialising LOAD_ATTR for mutable class attributes #93657

Fidget-Spinner commented Jun 9, 2022 •

edited

rhettinger commented Jun 9, 2022 •

edited

Fidget-Spinner commented Jun 10, 2022 •

edited

Fidget-Spinner commented Jun 10, 2022 •

edited

Specialising LOAD_ATTR for mutable class attributes #93657

Specialising LOAD_ATTR for mutable class attributes #93657

Comments

Fidget-Spinner commented Jun 9, 2022 • edited

rhettinger commented Jun 9, 2022 • edited

Fidget-Spinner commented Jun 10, 2022 • edited

Fidget-Spinner commented Jun 10, 2022 • edited

Fidget-Spinner commented Jun 9, 2022 •

edited

rhettinger commented Jun 9, 2022 •

edited

Fidget-Spinner commented Jun 10, 2022 •

edited

Fidget-Spinner commented Jun 10, 2022 •

edited