perf(ir): avoid exponential growth on name attribute access
#8445
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This commit changes the use of `hasattr` + `name` attribute access to eagerly access the `name` attribute, store it and check for `None`. Accessing the attribute twice may seem innocuous, but since names may be generated recursively, this results in 2 ** n growth in the number of accesses: once for the `hasattr` call, and once for the access if `hasattr` succeeds. This can happen with large operation trees where names are automatically generated.
cpcloud
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name attribute accessname attribute access
kszucs
approved these changes
Feb 26, 2024
kszucs
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Feb 26, 2024
| @@ -85,7 +85,11 @@ def __coerce__( | |||
| # TODO(kszucs): figure out how to represent not named arguments | |||
| @property | |||
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I think we should turn this into @attribute in a follow-up since the .name property is accessed multiple times during both construction and compilation.
NickCrews
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Feb 26, 2024
| for _ in range(n): # noqa: F402 | ||
| x = x + 1 | ||
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| assert x.op().name.count("Add") == n |
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@cpcloud do we want to add some way of checking for recursion explosion? Maybe use n=200 and then test this doesn't take longer than 3 seconds to compute?
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It didn't finish in any reasonable amount of time, so just having it as a standard unit test seems fine.
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ahh, I see, so you would just notice it during local dev, no automation needed. Sure that works.
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Fixes #8432. In short, the pattern we are using here for accessing
nameresults in exponential growth of attribute accesses.