python / python/cpython

Remove `DELETE_DEREF` bytecode instruction

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#145,858 3 comments 0 reactions 0 assignees View on GitHub

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interpreter-core performance type-feature
Dominant language
Python
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PR merge metrics
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Description

Feature or enhancement

Proposal:

The DELETE_DEREF opcode can be removed and deletion implemented by the sequence:
LOAD_DEREF POP_TOP PUSH_NULL STORE_DEREF

This would free up an opcode, and, since deletion of non-locals variables is practically never used, there is no cost to doing this.

Has this already been discussed elsewhere?

This is a minor feature, which does not need previous discussion elsewhere

Linked PRs
  • gh-148185

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Review the DELETE_DEREF opcode handling and the linked PR gh-148185 first. Determine the affected compiler and runtime paths, then verify that deleting a non-local uses the proposed instruction sequence and that the DELETE_DEREF opcode is removed.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
compilers
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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