Pickle 32-bit integers with protocol 0 as INT instead of LONG

[serhiy-storchaka]

BPO	32037
Nosy	@avassalotti, @serhiy-storchaka
PRs	bpo-32037: Use the INT opcode for 32-bit integers in protocol 0 pickles. #4407

^{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 = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2017-11-16.07:45:07.353>
created_at = <Date 2017-11-15.16:59:49.683>
labels = ['3.7', 'type-feature', 'library']
title = 'Pickle 32-bit integers with protocol 0 as INT instead of LONG'
updated_at = <Date 2017-11-16.07:45:07.352>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2017-11-16.07:45:07.352>
actor = 'serhiy.storchaka'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2017-11-16.07:45:07.353>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2017-11-15.16:59:49.683>
creator = 'serhiy.storchaka'
dependencies = []
files = []
hgrepos = []
issue_num = 32037
keywords = ['patch']
message_count = 2.0
messages = ['306285', '306342']
nosy_count = 2.0
nosy_names = ['alexandre.vassalotti', 'serhiy.storchaka']
pr_nums = ['4407']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue32037'
versions = ['Python 3.7']

[serhiy-storchaka]

In Python 3 different opcodes are used for pickling integers with protocol 1 and higher. But pickling with protocol 0 always uses the LONG opcode. In Python all such integers are unpickled to the long instances.

Proposed PR makes integers that fit in a signed 32-bit integer be pickled with the INT opcode. This will decrease the size of a pickle (minus one byte 'L' per integer), speeds up pickling and unpickling, and makes these integers be unpickled to int instances in Python 2, that will save a memory.

[serhiy-storchaka]

New changeset 3daaafb by Serhiy Storchaka in branch 'master':
bpo-32037: Use the INT opcode for 32-bit integers in protocol 0 pickles. (bpo-4407)
3daaafb