Specialize COMPARE_OP

[sweeneyde]

BPO	45885
Nosy	@markshannon, @brandtbucher, @sweeneyde
PRs	bpo-45885: Specialize COMPARE_OP #29734 bpo-45885: Add more stats for COMPARE_OP in specialize.c #31040 bpo-45885: Don't un-adapt COMPARE_OP when collecting stats #31516

^{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 2021-12-03.23:45:56.141>
created_at = <Date 2021-11-23.21:00:24.137>
labels = ['interpreter-core', '3.11', 'performance']
title = 'Specialize COMPARE_OP'
updated_at = <Date 2022-02-23.11:06:35.684>
user = 'https://github.com/sweeneyde'

bugs.python.org fields:

activity = <Date 2022-02-23.11:06:35.684>
actor = 'Mark.Shannon'
assignee = 'none'
closed = True
closed_date = <Date 2021-12-03.23:45:56.141>
closer = 'Dennis Sweeney'
components = ['Interpreter Core']
creation = <Date 2021-11-23.21:00:24.137>
creator = 'Dennis Sweeney'
dependencies = []
files = []
hgrepos = []
issue_num = 45885
keywords = ['patch']
message_count = 5.0
messages = ['406887', '406930', '407577', '412441', '413784']
nosy_count = 3.0
nosy_names = ['Mark.Shannon', 'brandtbucher', 'Dennis Sweeney']
pr_nums = ['29734', '31040', '31516']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue45885'
versions = ['Python 3.11']

Linked PRs

• GH-90043: Handle NaNs in COMPARE_OP_FLOAT_JUMP #100278

[sweeneyde]

Some specialization statistics:

https://gist.github.com/sweeneyde/49cc3a9d074d56cf095cb0a42d13d7a4

Including 3 opcodes: COMPARE_OP_INT and COMPARE_OP_FLOAT and COMPARE_OP_STR (equality only) seems to give pretty good specialization numbers, better than just 2.

[markshannon]

Is COMPARE_OP worth specializing by itself?

Most comparisons are followed by a jump, and much of the overhead is in the branching around the choice of operator as well as pushing and popping (with inc/decrefs) a value that has only one bit of information (True/False).

[markshannon]

New changeset 03768c4 by Dennis Sweeney in branch 'main':
bpo-45885: Specialize COMPARE_OP (GH-29734)
03768c4

[markshannon]

New changeset 674ab66 by Dennis Sweeney in branch 'main':
bpo-45885: Add more stats for COMPARE_OP in specialize.c (GH-31040)
674ab66

[markshannon]

New changeset 375a56b by Brandt Bucher in branch 'main':
bpo-45885: Don't un-adapt COMPARE_OP when collecting stats (GH-31516)
375a56b