[llvm] [ThinLTO] Properly support targets that require importing all external functions (PR #133588)

[Yaxun Liu via llvm-commits]

yxsamliu wrote:

> > Looks like this flag was added several years ago for AMDGPU (https://reviews.llvm.org/D99683). Do you know why it was sufficient then but not now?
> 
> I'm not sure if ThinLTO actually worked on AMDGPU back then. At least, it doesn't seem to be working at the moment. I'd assume @yxsamliu might have more insight on this.
> 
It worked for some HIP apps.

I am still not clear about what issue the linkage available_externally causes. Can you give an example? Thanks.


https://github.com/llvm/llvm-project/pull/133588