GV

GeezerVison

The World Wide Web, restored to 800 pixels of glory.

Home|About|Gaming cabinet|Archives|How it works|Starter sites

On this site

  • Sign in
  • ActionsCI/CD and automation
  • CodespacesCloud development environments
  • All Features
  • Documentation
  • Training
  • Certifications
  • Build with Copilot
  • Customize Copilot
  • Integrations
  • Trending repos
  • GitHub Sponsors
  • Developer articles
  • Enterprises

This view

  • Original page
  • New address

GeezerVison is showing github.com — gh-160247: Reduce padding in _PyInstructionSequence by ashm-dev · Pull Request #160271 · python/cpython

Conversation

@ashm-dev

@ashm-dev ashm-dev commented Oct 22, 2026 •
edited by bedevere-app Bot
Loading

Uh oh!

There was an error while loading. Please reload this page.

Copy link
Copy Markdown
Contributor

Move s_labelmap_size immediately before s_labelmap to eliminate the two alignment gaps in _PyInstructionSequence.

On the tested x86-64 GCC build, this reduces sizeof(_PyInstructionSequence) from 72 to 64 bytes without changing any field types. No compiler behavior or public API changes are intended.

Verified with a C layout check and the rebuilt interpreter. The following tests pass on a --with-pydebug build: test_compile, test_compiler_assemble, test_compiler_codegen, test_dis, test_peepholer, test_type_annotations, and test_grammar.

Closes #160247.

  • Issue: Reduce padding in the instruction sequence structure #160247

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
All reactions
@ashm-dev
perf(compiler): reduce padding in _PyInstructionSequence
1c2143b
@bedevere-app bedevere-app Bot added the type-feature A feature request or enhancement label Oct 22, 2026
@bedevere-app bedevere-app Bot mentioned this pull request Oct 22, 2026
Reduce padding in the instruction sequence structure #160247
Open
@bedevere-app bedevere-app Bot added the awaiting review label Oct 22, 2026
@ashm-dev
Merge branch 'main' into pythongh-160247
94f111d
@ashm-dev

ashm-dev commented Oct 27, 2026

Copy link
Copy Markdown
Contributor Author

Friendly ping
All reactions

Sorry, something went wrong.

Uh oh!

There was an error while loading. Please reload this page.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

No reviews

Uh oh!

There was an error while loading. Please reload this page.

Assignees

No one assigned

Labels

awaiting review type-feature A feature request or enhancement

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

Reduce padding in the instruction sequence structure

Uh oh!

There was an error while loading. Please reload this page.

1 participant

@ashm-dev
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
You are visitor 01402503 — GeezerVison does not store the pages you look up.
Best viewed with Netscape Navigator 4.7 or Internet Explorer 6 at 800×600. No cookies required.