Subject: hash-table improvements

From: Mattias Engdegård <[email-masked]>
Date: Thu, 4 Jan 2024 17:27:53 +0100

It's the hash-table's turn to be subjected to some performance tuning. The implementation has changed very little over the years and it's not so much a matter of a single big thing to fix as many small ones, so the list of changes is fairly long but ever little helps.

A working patch series can be found in the scratch/hash-table-perf branch. Although it should all be satisfactory and an improvement on what was before, there are a couple of details that I'd like to do better, which is why this hasn't been merged yet: the way shared hash_table_test structs are cached isn't very elegant, nor is the way we deal with Qunbound in pdumper.c.