[llvm] [DebugInfo] getMergedLocation: match scopes based on their location (PR #132286)

[Vladislav Dzhidzhoev via llvm-commits]

dzhidzhoev wrote:

> Though I'm not sure exactly how we could/should pick that shared one - "do any collide" seems a bit too vague to me.

It doesn't seem vague to me, since if we have `DILexicalBlock *S1, *S2`, if `S1 == S2`, then they collide. So we should not lose "precision" compared to the mainline (though DILexicalBlockFiles that have different children DILocations may add some imprecision, as we define the location of DILexicalBlockFile as the line of the previous location in a chain).



> Perhaps a strict suffix/tail in the source location chain could be preserved?

Then it would reproduce the algorithm for matching inlinedAt chains (which wraps `MergeLocPair()`). I have tried to implement it here https://github.com/llvm/llvm-project/pull/125780.

https://github.com/llvm/llvm-project/pull/132286