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bpo-39434: Improve float __floordiv__ performance and error message#18147

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corona10:bpo-39434
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bpo-39434: Improve float __floordiv__ performance and error message#18147
mdickinson merged 1 commit intopython:masterfrom
corona10:bpo-39434

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@corona10 corona10 commented Jan 23, 2020 •
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@corona10 corona10 changed the title [WIP] bpo-39434: Add float __floordiv__ fast path bpo-39434: Add float __floordiv__ fast path Jan 23, 2020
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corona10 commented Jan 23, 2020

@mdickinson, @vstinner
If this proposal is accepted, I am going to add news.d since the error message is changed.

@corona10 corona10 changed the title bpo-39434: Add float __floordiv__ fast path bpo-39434: Remove unnecessary logic of float __floordiv__ Jan 23, 2020
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Neat trick: I was worried about duplicated code (see the issue discussion), but it seems we can rely on the compiler to inline _float_div_mod and then strip out the redundant stuff.

LGTM

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mdickinson commented Jan 23, 2020

Is there benefit to applying the same approach to float_rem? Apart from the possibility of a performance boost, it looks as though it would actually make the code simpler (removing existing duplication) and safer. And for floats, % is possibly used more often than // (for argument reduction, for example).

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mdickinson commented Jan 23, 2020

Apart from the possibility of a performance boost,

Sorry, of course that doesn't apply, since float_rem is already special-cased and doesn't go via divmod.

@corona10 corona10 changed the title bpo-39434: Remove unnecessary logic of float __floordiv__ bpo-39434: Improve float __floordiv__ performance and update error message Jan 24, 2020
@corona10 corona10 changed the title bpo-39434: Improve float __floordiv__ performance and update error message bpo-39434: Improve float __floordiv__ performance and error message Jan 24, 2020
@corona10 corona10 requested a review from pablogsal January 27, 2020 17:41
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corona10 commented Jan 28, 2020

@vstinner @pablogsal If you don't mind can you please take a look? :)

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mdickinson commented Jan 30, 2020

I've done some manual testing as well as reviewing. Still LGTM.

@mdickinson mdickinson merged commit 8d49f7c into python:master Jan 30, 2020
shihai1991 pushed a commit to shihai1991/cpython that referenced this pull request Jan 31, 2020
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bpo-39434: Improve float __floordiv__ performance and error message (p…
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…ythonGH-18147)
@mdickinson mdickinson mentioned this pull request Feb 2, 2020
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@vstinner vstinner Awaiting requested review from vstinner

@pablogsal pablogsal Awaiting requested review from pablogsal

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@mdickinson mdickinson mdickinson approved these changes

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