census: optional column dump, so a consumer can answer the SIMD question

[AdaWorldAPI]

r2il::columns states that whether vectorizing its scans pays "is a profiling question nobody has answered", and that the crate takes no ndarray dependency on purpose — the consumer holds one. That left no way to get real columns out of a real lift and into such a consumer.

What this adds

An env-gated dump in the win32_census example — WIN32_CENSUS_COLUMNS_OUT=<path>, default off, zero behaviour change when unset — writing the three columns in a flat LE form: u64 n, n×u8 tag, n×u8 space, n×u64 offset.

It is deliberately the smallest possible change: no ndarray edge is created anywhere in this workspace, and r2il's dependency surface is untouched.

What it was used for

AdaWorldAPI/ndarray#308 consumes the dump and answers the question on this fixture's 12 408 p-code ops (four arms — scalar over the native u8/u64 columns, mask_and, mask_ternlog::<AND3>, and the _under chain — all gated bit-for-bit identical before timing, swept 256 → 3.2 M):

• mask arms 1.32–1.42× the scalar scan at the real size;
• the advantage inverts to 0.75–0.80× above ~200 K ops, because the facade's narrowest value type is u32 while these columns are u8, so a consumer pays a 4× widened copy;
• whole-census saving 2.5 µs, against a SLEIGH lift that costs milliseconds.

Also measured, and it bears on find_ram_in_range directly: 100 % of Ram-space offsets in this lift exceed 2³² (image-based, 0x1_4000_105e…0x1_4000_8398), and ndarray's ordered comparator family stops at i32 — so that query has no general vectorized spelling today without a u64 range primitive.

The columns' own doc-comment caution was right, and is now measured rather than assumed.

🤖 Generated with Claude Code

https://claude.ai/code/session_01DCfrD5y19cvFc4AoyydXYv

Summary by CodeRabbit

• New Features
  • Added optional columnar output for the Win32 census tool.
  • Set WIN32_CENSUS_COLUMNS_OUT to export operation counts, tags, spaces, and offsets to a specified file.
  • The tool reports how many operations were exported.
  • When the setting is not provided, no output file is generated.

[coderabbitai]

Caution

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 99d2553 and 0a39849.

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• crates/r2sleigh-lift/examples/win32_census.rs

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📝 Walkthrough

Walkthrough

The Win32 census example now optionally exports projected operation data to a file specified by WIN32_CENSUS_COLUMNS_OUT.

Changes

Win32 census column export

Layer / File(s)	Summary
Environment-controlled column export crates/r2sleigh-lift/examples/win32_census.rs	When WIN32_CENSUS_COLUMNS_OUT is set, the census writes operation counts, tags, spaces, and little-endian offsets to the specified file. It reports the exported operation count and fails if writing fails.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Suggested reviewers: claude

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

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_{A rabbit found columns in rows,
And packed little-endian flows.
The census counted each byte,
Then wrote the results just right.
No path, no dump—quiet repose.}

_{Comment @coderabbitai help to get the list of available commands.}

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