[llvm] [MC][X86] Set SHF_X86_64_LARGE on mergeable constant sections for large code-model (PR #190903)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

yeah I think this change is good on its own anyway. still needs the other place I mentioned to be updated. I'm not sure if there's any way to deduplicate the multiple places that we choose the section name/flags between this and what #81900 touched

https://github.com/llvm/llvm-project/pull/190903