[llvm] [KeyInstr] MDNodeKeyImpl<DILocation> skip zero values for hash (PR #143357)

[Orlando Cazalet-Hyams via llvm-commits]

OCHyams wrote:

I hadn't thought of that, thanks. I tried reducing it to the 32 byte hash by reducing `column` to a u16 (since it looks like the parser only accepts column numbers up to u16 max?). According to compiletimetracker that is an improvement over the baseline, but nowhere near the savings of this patch:

https://llvm-compile-time-tracker.com/compare.php?from=3fa3a147a0d7a579f92f5ca6db1bfcdd485f8ffa&to=dd9e6b697dd916cc9cbd00e124d265188290a903&stat=instructions%3Au

(note the comparison is 32 bytes against this patch as a base).

https://github.com/llvm/llvm-project/pull/143357