[llvm] [RISC-V] Add SMLoc info for fixup. [NFCI] (PR #142054)

[Francesco Petrogalli via llvm-commits]

fpetrogalli wrote:

> I actually plan to remove SMLoc from MCFixup to reduce its size, as the SMLoc can typically be retrieved from `MCExpr *MCFixup::Value`.
> 
> I also considered removing SMLoc from MCExpr. https://llvm-compile-time-tracker.com/compare.php?from=193135c80019a01e08014b5727088b860a09f493&to=b8a413de2798260fabf6b5650fc22c803fa13831&stat=max-rss&linkStats=on
> 
> The saving is actually quite decent for a -g build, but some folks might need the MCExpr loc.
> 
> #### stage1-ReleaseLTO-g (link only):
> Benchmark | Old | New
> -- | -- | -- kimwitu++ | 248MiB | 242MiB (-2.52%) sqlite3 | 221MiB | 216MiB (-2.43%) consumer-typeset | 162MiB | 158MiB (-2.26%) Bullet | 208MiB | 204MiB (-1.81%) tramp3d-v4 | 624MiB | 616MiB (-1.32%) mafft | 122MiB | 123MiB (+1.08%) ClamAV | 230MiB | 224MiB (-2.61%) lencod | 277MiB | 270MiB (-2.63%) SPASS | 289MiB | 284MiB (-1.67%) 7zip | 467MiB | 454MiB (-2.84%) geomean | 256MiB | 251MiB (-1.91%)
> 
> 

I don't understand how SMLoc is saving size on these non-LLVM executable.

> I think we should remove SMLoc from either MCFixup or MCExpr. If we end up updating MCFixup, this change will be rewritten.

I don't have preferences, as long as we can still prompt errors that point to the line that is causing the error.

Some context on why I created this MR. I am currently debugging some failures in the relocations for Macho-O, adding these SMLoc helped me out to figure out what was wrong. I can keep these changes locally if you don't find them useful. Even if we merged this change, I don't have a regression test for it (other than the failure I am debugging, which of course I cannot upstream as it is), so if you end up removing it in the cleanup, nobody will notice.

https://github.com/llvm/llvm-project/pull/142054