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Speed up make_simplified_union, fix recursive tuple crash #15128

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merged 8 commits into from May 6, 2023
Merged

Speed up make_simplified_union, fix recursive tuple crash #15128

merged 8 commits into from May 6, 2023

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hauntsaninja
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@hauntsaninja hauntsaninja commented Apr 25, 2023 •
edited

Fixes #15192

The following code optimises make_simplified_union in the common case that there are exact duplicates in the union. In this regard, this is similar to #15104

There's a behaviour change in one unit test. I think it's good? We'll see what mypy_primer has to say.

To get this to work, I needed to use partial tuple fallbacks in a couple places (these maybe had the potential to be latent crashes anyway?) There were some interesting things going on with recursive type aliases and type state assumptions

This is about a 25% speedup on the pydantic codebase and about a 2% speedup on self check (measured with uncompiled mypy)

hauntsaninja and others added 2 commits April 25, 2023 10:18
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Speed up make_simplified_union, remove a potential crash
184e415 
The following code optimises make_simplified_union in the common case
that there are exact duplicates in the union. In this regard, this is
similar to python#15104

To get this to work, I needed to use partial tuple fallbacks in a couple
places (these maybe had the potential to be latent crashes anyway?)
There were some interesting things going on with recursive type aliases
and type state assumptions

This is about a 25% speedup on the pydantic codebase and about a 2%
speedup on self check (measured with uncompiled mypy)
@pre-commit-ci
[pre-commit.ci] auto fixes from pre-commit.com hooks
cd5f40b 
for more information, see https://pre-commit.ci
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hauntsaninja commented Apr 25, 2023 •
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Looks like there's a major performance regression in materialize

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Diff from mypy_primer, showing the effect of this PR on open source code:

pandas-stubs (https://github.com/pandas-dev/pandas-stubs) got 1.14 faster (68.0s -> 59.5s)

speedrun.com_global_scoreboard_webapp (https://github.com/Avasam/speedrun.com_global_scoreboard_webapp) got 1.24 faster (43.8s -> 35.2s)

@hauntsaninja hauntsaninja marked this pull request as ready for review April 26, 2023 00:11
@hauntsaninja hauntsaninja mentioned this pull request Apr 26, 2023
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(note to self: once this is merged, rename is_simple_literal to is_simple_str_literal or see if we can get rid of it)

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JukkaL commented May 3, 2023

I did a measurement using misc/perf-compare.py and this seems roughly performance-neutral for self check using a compiled mypy:

=== Results ===

hauntsaninja-msu          4.393s (0.0%)
master                    4.405s (+0.3%)

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JukkaL reviewed May 3, 2023
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Looks good! I'm happy to see additional performance wins. I finally got around to reviewing this now that my jet lag is better.

Left a few additional ideas (optional, since this already seems like a nice improvement).

mypy/typeops.py Show resolved Hide resolved
mypy/typeops.py Show resolved Hide resolved
mypy/typeops.py Outdated Show resolved Hide resolved
mypy/typeops.py
# If deleted subtypes had more general truthiness, use that
orig_item = new_items[duplicate_index]
if not orig_item.can_be_true and ti.can_be_true:
new_items[duplicate_index] = true_or_false(orig_item)
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Should we only change can_be_true, or is it ok to only adjust can_be_false?

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This is a good question. I'm going to preserve the existing behaviour for now and explore this in another PR. These code paths don't have many unit tests (see #15094 and #15098), so I want to be careful here

mypy/typeops.py
if not orig_item.can_be_true and ti.can_be_true:
new_items[duplicate_index] = true_or_false(orig_item)
elif not orig_item.can_be_false and ti.can_be_false:
new_items[duplicate_index] = true_or_false(orig_item)
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Similar to above.

@hauntsaninja hauntsaninja mentioned this pull request May 5, 2023
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@hauntsaninja hauntsaninja changed the title Speed up make_simplified_union, remove a potential crash Speed up make_simplified_union, fix a crash May 5, 2023
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hauntsaninja commented May 5, 2023 •
edited

This fixes a crash that just got reported #15192, so I added a regression test for it.

I added the two micro optimisations suggested.

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github-actions bot commented May 5, 2023

Diff from mypy_primer, showing the effect of this PR on open source code:

pandas-stubs (https://github.com/pandas-dev/pandas-stubs) got 1.15x faster (66.6s -> 58.0s)

speedrun.com_global_scoreboard_webapp (https://github.com/Avasam/speedrun.com_global_scoreboard_webapp) got 1.27x faster (33.3s -> 26.2s)

@hauntsaninja hauntsaninja changed the title Speed up make_simplified_union, fix a crash Speed up make_simplified_union, fix recursive tuple crash May 6, 2023
@hauntsaninja hauntsaninja merged commit 7832e1f into python:master May 6, 2023
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@hauntsaninja hauntsaninja deleted the msu branch May 6, 2023 20:22
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hauntsaninja commented May 6, 2023 •
edited

Nice, looks like the primer timings are pretty consistent between:
#15128 (comment)
#15128 (comment)
and some of the earlier commits on this PR (although those earlier commits had the regression on Materialize)

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This PR actually introduced a recursive tuple crash

[case testAliasRecursiveUnpack]
from typing import Tuple, TypeVar, Optional

T = TypeVar("T")
S = TypeVar("S")

A = Tuple[T, S, Optional[A[T, S]]]  # Must have two non-recursive items to crash
x: A[int, str]

*_, last = x
if last is not None:
    reveal_type(last)
[builtins fixtures/tuple.pyi]

I will check maybe there is a simple fix for it.

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It looks like there is (a bug is quite obvious). I will submit a PR shortly.

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See #15216

@hauntsaninja hauntsaninja mentioned this pull request Jun 14, 2023
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Segfault when manipulating a recursive union
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@hauntsaninja @JukkaL @ilevkivskyi