[clang] [llvm] Support -mnop-mcount and -mrecord-mcount on x86_64 elf targets. (PR #184641)

[Nikita Popov via cfe-commits]

nikic wrote:

Added some X86 reviewers, but I think this could use more context on why we want to support these options, and why we want to support them on s390x and x86 in particular. Is it just because those are the two arches where GCC supports them?

https://github.com/llvm/llvm-project/pull/184641