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Break up the YIELD_FROM instruction. #90197

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markshannon opened this issue Dec 10, 2021 · 2 comments
Closed

Break up the YIELD_FROM instruction. #90197

markshannon opened this issue Dec 10, 2021 · 2 comments
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@markshannon
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3.11 only security fixes interpreter-core (Objects, Python, Grammar, and Parser dirs)

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@markshannon
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BPO 46039
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PRs
  • bpo-46039: Split yield from in two #30035
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    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/markshannon'
closed_at = <Date 2022-01-06.12:53:07.294>
created_at = <Date 2021-12-10.17:48:52.500>
labels = ['interpreter-core', '3.11']
title = 'Break up the YIELD_FROM instruction.'
updated_at = <Date 2022-01-06.12:53:07.293>
user = 'https://github.com/markshannon'

    bugs.python.org fields:

    activity = <Date 2022-01-06.12:53:07.293>
actor = 'Mark.Shannon'
assignee = 'Mark.Shannon'
closed = True
closed_date = <Date 2022-01-06.12:53:07.294>
closer = 'Mark.Shannon'
components = ['Interpreter Core']
creation = <Date 2021-12-10.17:48:52.500>
creator = 'Mark.Shannon'
dependencies = []
files = []
hgrepos = []
issue_num = 46039
keywords = ['patch']
message_count = 2.0
messages = ['408232', '408593']
nosy_count = 1.0
nosy_names = ['Mark.Shannon']
pr_nums = ['30035']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue46039'
versions = ['Python 3.11']
    @markshannon
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    The YIELD_FROM instruction does three things:

    • It sends a value to the sub-iterator
    • It yields the value from the sub-iterator back up to its caller
    • Loops back on itself

    So we should implement this as:

    SEND <--+
    YIELD_VALUE |
    JUMP_ABSOLUTE -+

    Doing so would allow us to simplify gen.send and gen.throw as they wouldn't need all the special cases for 'yield from'.

    Zero cost exception handling allows us to handle throw in the bytecode with no runtime overhead:

    while True:
    SEND -> exit
    try:
        YIELD_VALUE
    except BaseException as ex:
        sub_iterator.throw(ex)
exit:

    @markshannon markshannon added the 3.11 only security fixes label Dec 10, 2021
    @markshannon markshannon self-assigned this Dec 10, 2021
    @markshannon markshannon added interpreter-core (Objects, Python, Grammar, and Parser dirs) 3.11 only security fixes labels Dec 10, 2021
    @markshannon markshannon self-assigned this Dec 10, 2021
    @markshannon markshannon added the interpreter-core (Objects, Python, Grammar, and Parser dirs) label Dec 10, 2021
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    New changeset 0b50a4f by Mark Shannon in branch 'main':
    bpo-46039: Split yield from in two (GH-30035)
    0b50a4f

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @MatthieuDartiailh MatthieuDartiailh mentioned this issue Jul 18, 2022
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