[clang] [flang] [clang] Add option to specify opt pipeline during offload lto (PR #114401)

[via cfe-commits]

macurtis-amd wrote:

> > > Can this be done through `-Xoffload-linker`?
> > 
> > 
> > No. I tried several different things, but was not able to get the right command line option passed to lld (in the clang->clang-linker-wrapper->clang->lld chain).
> 
> This works for me,
> 
> ```
> $ clang input.c -fopenmp --offload-arch=gfx1030 -Xoffload-linker --lto-newpm-passes='default<O3>' -v
> ld.lld ... --lto-newpm-passes=default<O3> ...
> ```

You are right. That works. I thought I had tried `-Xoffload-linker` but I guess not.

https://github.com/llvm/llvm-project/pull/114401