reduce .text size by methane · Pull Request #129 · methane/cpython · GitHub

Summary by CodeRabbit

Refactor
- Streamlined generation and initialization of AST metadata and static strings.
- Consolidated runtime setup and cleanup paths.
- Improved handling of generated interpreter state during initialization and cleanup.
- Added safeguards for generated data sizes and state layout.
Build and Tooling
- Updated source-size analysis limits for generated Unicode and AST files.
Compatibility
- No changes to public APIs or user-facing behavior.

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Review configuration:

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 5b195b1b-2172-41d2-93b4-cc8190c7b764

📥 Commits

Reviewing files that changed from the base of the PR and between 59734b4 and 21bc6fc.

📒 Files selected for processing (3)

Include/internal/pycore_unicodeobject_generated.h
Parser/asdl_c.py
Python/Python-ast.c

📝 Walkthrough

Walkthrough

The change replaces repeated generated C statements with table-driven AST annotation metadata, offset-based cleanup, offset-based static string interning, and parser size limits for two generated files.

Changes

Generated initialization

Layer / File(s)	Summary
AST annotation metadata and cleanup Parser/asdl_c.py	AnnotationsVisitor records node and field metadata, then generates offset-based annotation creation with centralized failure cleanup. AST state cleanup now iterates over generated offsets.
Static string initialization Tools/build/generate_global_objects.py	Static string initialization generates an offset array and interns identifiers and literals in one loop while preserving consistency and length assertions.
Generated file size limits Tools/c-analyzer/cpython/_parser.py	The parser adds size and line-count limits for the generated Unicode and AST files.

Priority: ⬇️ Low

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Refactor

Suggested reviewers: lysnikolaou, ericsnowcurrently

Merge Risk: 🟠 High · up to 59734

The code generator produces an invalid type name, so the regenerated interpreter source will not build. This one-token fix should be corrected before merging; the rest of the table-driven changes show no further blocking issues.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 6 functions across 3 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title, "reduce .text size," accurately describes the main objective of the changes: reducing generated code size through table-driven implementations and shared initialization logic.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com> Co-authored-by: Inada Naoki <songofacandy@gmail.com>

Actionable comments posted: 1

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Inline comments:
In `@Parser/asdl_c.py`:
- Line 814: Update the generated flags declaration in the relevant AST structure
from the invalid uint8_5 type to the standard uint8_t type so the generated C
source compiles.

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ℹ️ Review info ⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: ac3fe3ca-254c-41cb-87a2-66baf15710d9

📥 Commits

Reviewing files that changed from the base of the PR and between b22fdca and 59734b4.

📒 Files selected for processing (2)

Parser/asdl_c.py
Tools/build/generate_global_objects.py

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reduce .text size

cf44a1a

methane and others added 3 commits September 13, 2026 07:23

fix check-c-globals

851f123

fix indent and use more compact table

b22fdca

Apply batched suggestions from code review

59734b4

Co-authored-by: Pieter Eendebak <pieter.eendebak@gmail.com> Co-authored-by: Inada Naoki <songofacandy@gmail.com>

coderabbitai Bot reviewed Sep 22, 2026

View reviewed changes

Comment thread Parser/asdl_c.py Outdated

methane added 2 commits September 22, 2026 12:54

fixup and regen

d54cc70

make regen-all

21bc6fc

reduce .text size by methane · Pull Request #129 · methane/cpython · GitHub

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reduce .text size - #129

reduce .text size#129
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reduce-codesize

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reduce .text size by methane · Pull Request #129 · methane/cpython · GitHub

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reduce .text size - #129

reduce .text size#129methane wants to merge 6 commits intomainmethane/cpython:mainfrom reduce-codesizemethane/cpython:reduce-codesizeCopy head branch name to clipboard

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reduce .text size#129
methane wants to merge 6 commits into
mainfrom
reduce-codesize

methane commented Sep 13, 2026 •
edited by coderabbitai Bot
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