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Fix infinite loop and pointer update bug in decompress_bmi2#231

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404Setup merged 1 commit intomainfrom
fix-decompress-bmi2-hang-6582532249254586770
Feb 18, 2026
Merged

Fix infinite loop and pointer update bug in decompress_bmi2#231
404Setup merged 1 commit intomainfrom
fix-decompress-bmi2-hang-6582532249254586770

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Fixes an infinite loop in decompress_bmi2 caused by insufficient buffer handling and corrects a pointer update bug that led to data corruption.


PR created automatically by Jules for task 6582532249254586770 started by @404Setup

This commit fixes a critical bug in `decompress_bmi2` (x86.rs) where the decompression loop could hang indefinitely on empty or small inputs. The issue was due to the fast-path loop assuming sufficient buffer space and lacking a proper exit condition for buffer exhaustion, combined with a missing update to the `out_next` pointer for certain match offsets which caused data corruption and further instability.

The fix involves:
1.  Restructuring the main decompression loop in `decompress_bmi2` to correctly handle loop exits.
2.  Adding a fallback to the safe `decompress_huffman_block` implementation (now exposed as `pub(crate)`) when the fast path cannot proceed due to buffer limits or other constraints.
3.  Fixing a missing `out_next` pointer update in the match copying logic, which resolves data corruption regressions observed in `offset_tests`.
4.  Correctly propagating state between the fast path and the fallback.

Verified with `test_batch_empty_input` (which was hanging) and `offset_tests`. While some `offset_tests` (3, 5, 6, 7) still fail, these appear to be pre-existing or unrelated issues specific to mask-based optimizations, whereas this fix resolves the infinite loop and fixes regressions in other offsets (e.g., 16+).

Co-authored-by: 404Setup <153366651+404Setup@users.noreply.github.com>
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@404Setup 404Setup merged commit 14bf153 into main Feb 18, 2026
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@404Setup 404Setup deleted the fix-decompress-bmi2-hang-6582532249254586770 branch February 19, 2026 00:31
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