[clang] [llvm] [Clang] -fseparate-named-sections option (PR #91028)

[Petr Hosek via cfe-commits]

petrhosek wrote:

> > This is an alternative approach to address the issue described in [discourse.llvm.org/t/rfc-support-for-memory-regions-in-elf/78570](https://discourse.llvm.org/t/rfc-support-for-memory-regions-in-elf/78570) which doesn't require a custom section type.
> 
> This RFC is about `SHT_LLVM_MEMORY` while this patch seems orthogonal?

We might still consider implementing `SHT_LLVM_MEMORY` since it'd enable new use cases, but this PR addresses one of the issues described in that RFC without requiring significant changes in either LLVM or the existing code.

> I agree that the option is useful in some cases. If `ld -r` is used, `--unique` will be needed to not destroy granularity.

https://github.com/llvm/llvm-project/pull/91028