Faster bypass re cache when DEBUG is passed

[serhiy-storchaka]

BPO	22510
Nosy	@pitrou, @ezio-melotti, @serhiy-storchaka
Files	re_debug_cache_faster.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2014-09-29.17:02:10.439>
created_at = <Date 2014-09-28.13:43:11.638>
labels = ['expert-regex', 'type-feature', 'library']
title = 'Faster bypass re cache when DEBUG is passed'
updated_at = <Date 2014-09-29.17:02:10.438>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2014-09-29.17:02:10.438>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = True
closed_date = <Date 2014-09-29.17:02:10.439>
closer = 'serhiy.storchaka'
components = ['Library (Lib)', 'Regular Expressions']
creation = <Date 2014-09-28.13:43:11.638>
creator = 'serhiy.storchaka'
dependencies = []
files = ['36749']
hgrepos = []
issue_num = 22510
keywords = ['patch']
message_count = 3.0
messages = ['227758', '227801', '227810']
nosy_count = 5.0
nosy_names = ['pitrou', 'ezio.melotti', 'mrabarnett', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue22510'
versions = ['Python 3.5']

[serhiy-storchaka]

Here is a patch which gets rid of small performance regression introduced by bpo-20426 patch. No need to check flags before cache lookup because patterns with the DEBUG flag are newer cached.

$ ./python -m timeit -s "import re" -- "re.match('', '')"

Before patch: 9.08 usec per loop
After patch: 8 usec per loop

[python-dev]

New changeset 565096a32ce4 by Serhiy Storchaka in branch 'default':
Issue bpo-22510: Get rid of little overhead of testing re.DEBUG flag.
https://hg.python.org/cpython/rev/565096a32ce4

[serhiy-storchaka]

Thank you Antoine for your review.