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Perform "peephole" optimization directly on control-flow graph. #85495

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Perform "peephole" optimization directly on control-flow graph.#85495
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markshannon
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performancePerformance or resource usage

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@markshannon
markshannon
opened on Jul 17, 2020
BPO 41323
Nosy @tim-one, @rhettinger, @vstinner, @methane, @markshannon
PRs
  • bpo-41323: Perform 'peephole' optimizations directly on the CFG. #21517
  • bpo-41323: compiler: Reuse tuple in constant tuple folding #25419
    		•

    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 2020-07-30.09:04:04.543>
created_at = <Date 2020-07-17.10:27:02.814>
labels = ['performance']
title = 'Perform "peephole" optimization directly on control-flow graph.'
updated_at = <Date 2021-04-16.05:01:32.524>
user = 'https://github.com/markshannon'

    bugs.python.org fields:

    activity = <Date 2021-04-16.05:01:32.524>
actor = 'methane'
assignee = 'Mark.Shannon'
closed = True
closed_date = <Date 2020-07-30.09:04:04.543>
closer = 'Mark.Shannon'
components = []
creation = <Date 2020-07-17.10:27:02.814>
creator = 'Mark.Shannon'
dependencies = []
files = []
hgrepos = []
issue_num = 41323
keywords = ['patch']
message_count = 4.0
messages = ['373811', '373848', '374606', '391165']
nosy_count = 5.0
nosy_names = ['tim.peters', 'rhettinger', 'vstinner', 'methane', 'Mark.Shannon']
pr_nums = ['21517', '25419']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'performance'
url = 'https://bugs.python.org/issue41323'
versions = []

    Activity

    1. markshannon commented on Jul 17, 2020

      @markshannon
      markshannon
      on Jul 17, 2020
      MemberAuthor

      Currently we perform various bytecode improvements as a pass on the code objects after generating the code object.

      This requires parsing the bytecode to find instructions, recreating the CFG, and rewriting the line number table.

      If we perform the optimizations directly on the CFG we can avoid all that additional work.

      This would save hundreds of lines of code and avoid coupling the optimization to the line number table format.

    2. markshannon
      self-assigned this
      on Jul 17, 2020
    3. markshannon
      added
      performancePerformance or resource usage
      on Jul 17, 2020
    4. markshannon
      self-assigned this
      on Jul 17, 2020
    5. markshannon
      added
      performancePerformance or resource usage
      on Jul 17, 2020

    6. rhettinger commented on Jul 17, 2020

      @rhettinger
      rhettinger
      on Jul 17, 2020
      Contributor

      +1 This looks like a nice improvement. I've long wanted the optimizations to be moved upstream.

      At the time the peephole logic was first written, operating directly on the code object was the only option that kept optimizations separate from the core compiler logic. But disassembling and reassembling bytecode was always awkward — it is nice to no longer have to do so.

    7. markshannon commented on Jul 30, 2020

      @markshannon
      markshannon
      on Jul 30, 2020
      MemberAuthor

      New changeset 6e8128f by Mark Shannon in branch 'master':
      bpo-41323: Perform 'peephole' optimizations directly on the CFG. (GH-21517)
      6e8128f

    8. markshannon
      closed this as completedon Jul 30, 2020
    9. markshannon
      closed this as completedon Jul 30, 2020

    10. methane commented on Apr 16, 2021

      @methane
      methane
      on Apr 16, 2021
      Member

      New changeset 8a232c7 by Inada Naoki in branch 'master':
      bpo-41323: compiler: Reuse tuple in constant tuple folding (GH-25419)
      8a232c7

    11. ezio-melotti
      transferred this issue fromon Apr 10, 2022
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