Exclude functions with changed header from reluctant destabilization #663
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We discovered that one common case where reluctant destabilization leads to a greater number of evaluation and a worse runtime as without reluctant destabilization, is when the header (that is for example the type) of a function changes.
When the type of a function changes, the contexts for which it needs to be analyzed also change and therefore it is superfluous to analyze it for the previous but outdated context first. Also for functions whose type changed, the program point where this function is called is also detected to have changed, so the changed function is destabilized completely anyway.
This optimization substantially reduces the number of commits in the zstd repository for which reluctant destabilization deteriorates the runtime of an incremental analysis.