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Versions 0.8.19 to 0.8.37 are affected, only with the Yul optimizer enabled. With --via-ir, any code may be affected.

The fix changed no bytecode in verified contracts on Sourcify, which suggests the bug is very rare.

Full write-up and how to check:

https://soliditylang.org/blog/2026/10/22/yul-optimizer-knowledge-base-stale-bookkeeping-bug/

The release also improves the performance of the DataFlowAnalyzer, which several Yul optimizer steps are built on. As a result, compilation with the Yul optimizer enabled is faster.

In the IR pipeline, the function dispatcher now uses one fewer instruction.