Preserve parent validity when filtering struct layouts

[AdamGS]

Filtering a nullable struct delegated predicates to child layouts without applying the parent validity bitmap. A null parent with stored a = 7 could therefore fail a IS NULL. Apply parent validity before child filtering, then evaluate the predicate on a null struct to retain matching null-parent rows.

Skip child-statistics pruning at nullable struct boundaries because those statistics omit inherited nulls. This is conservative and can reduce pruning even when all parent rows are valid. Regression tests cover IS NULL, IS NOT NULL, comparisons, null roots, and incoming row masks.

🤖 Generated with Codex

[codspeed-hq]

Merging this PR will degrade performance by 15.17%

⚠️ Unknown Walltime execution environment detected

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For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
❌ 2 regressed benchmarks
✅ 2194 untouched benchmarks
⏩ 218 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	arrow_checked_add_u32_neon[16384]	12.3 µs	20.3 µs	-39.6%
❌	WallTime	mul_u32_nonnull_avx512	5.6 µs	6.3 µs	-10.92%
⚡	Simulation	allocate_drop_arrow[0]	456.9 ns	402.7 ns	+13.45%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing adamg/nullable-struct-filter (f6eec47) with develop (8f3dfb4)}

Footnotes

1. 218 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩