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

[Nikita Popov via llvm-commits]

nikic wrote:

Interesting! What I find peculiar is how big the difference between stage1-O0-g and stage2-O0-g is. It seems like Clang is doing something extremely terrible here compared to GCC, and it would be nice to find out what that is and whether we can fix it...

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