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Chandler Carruth
ebbdc11877
Testing this hash function with representative hash table implementations showed significant differences in quality between different multiplicative hashing constants. The constants used and documented were OK but had clear limitations when merely using a single 64-bit multiplication. However, a search uncovered (partly by luck) a constant that has empirically been shown to be both significantly better than other constants and generally not have problematic weaknesses. There are still plenty of collisions for string keys and heavily loaded hash tables of course, but no examples of severe outlier collision rates as observed with all other constants we have tried. There is a slightly longer comment explaining some of this context and the other constants we have tried in the PR as well. To this day, we still don't fully understand why the constant used here behaves so much better than other constants we have tried, including all of those we've found in other hashing algorithms.