Don't stop early: Case-folding source code at memory speed

What this post added

This post details optimizations for case folding in GitHub's code search engine, Blackbird. It introduces a branchless ASCII case folding implementation that achieves memory bandwidth speeds by removing early exits and leveraging vectorization. It also discusses efficient Unicode case folding by using a compact data structure and strategies for memory management to avoid heap allocations, including reserving capacity for potential string growth.