[clang] [llvm] [HIPSPV] Add in-tree SPIR-V backend support for chipStar (PR #206910)

[Henry Linjamäki via cfe-commits]

linehill wrote:

> … preferring an external llvm-spirv when one is found next to the toolchain, otherwise falling back to the in-tree SPIR-V backend (clang -cc1 -emit-obj).

I personally would like to have the SPIR-V backend to be preferred. I heard the backend is in good shape now and it seemed so when I tested it a while ago. But it’s fine in case the backend is not yet good enough for chipStar.

I think, the choice of using either the translator or the backend should be configurable (possibly controlled via a command line option*) to avoid subtle issues - e.g. having clang to switch to use the translator while the backend is preferred because a user happens to install llvm-spriv on their system.

*: There is `-f[no-]integrated-objemitter` option that would be suited for this. IIUC, the regular SPIR-V toolchain can be commanded to use the translator with `-fno-integrated-objemitter` and otherwise it uses the backend.


https://github.com/llvm/llvm-project/pull/206910