[llvm] [DebugInfo] Add DILayerLoc/DILayerLocList and DILocation irlayers operand (PR #215666)

[Stephen Tozer via llvm-commits]

https://github.com/SLTozer commented:

A few minor comments, but no major issues with this in terms of debug info - the classes seem straightforwardly implemented. The performance concerns are worth a brief look - 0.13% geomean slowdown isn't that much, but it justifies spending a bit of extra time to confirm/see if it can be cut down on. If it turns out that it's just an irreducible cost of the extra check for IRLayers though, then it's an acceptable tradeoff for a new feature (imo).

https://github.com/llvm/llvm-project/pull/215666