[llvm] [DWARF] Add option to add linkage_names to call_origin declaration refs (PR #89640)

[Orlando Cazalet-Hyams via llvm-commits]

https://github.com/OCHyams commented:

Thanks both for the reviews.

> By "upstream" you mean "anyone not using -gsce"?

Ah, yes indeed. I'll edit the summary so that it makes more sense.

> And any chance you've measured the impact of not always adding linkage names to subprogram DIEs for SCE lately? Is that optimization still pulling its weight for you, or would it be possible to converge on the non-sce behavior and remove some special cases here, rather than adding a new one?

I have - across some internal codebases and configurations I measured an increase of total linked binary size including debug info of between ~4% (-O0 builds) to as much as ~19% (thinLTO -O3 builds) when using `-dwarf-linkage-names=All` instead of `=Abstract`.

https://github.com/llvm/llvm-project/pull/89640