[clang] [llvm] [Driver][clang-linker-wrapper] Add initial support for OpenMP offloading to generic SPIR-V (PR #120145)

[Nick Sarnie via llvm-commits]

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@@ -922,6 +947,8 @@ void Driver::CreateOffloadingDeviceToolChains(Compilation &C,
                    IsAMDOffloadArch(StringToOffloadArch(
                        getProcessorFromTargetID(*AMDTriple, Arch)))) {
           DerivedArchs[AMDTriple->getTriple()].insert(Arch);
+        } else if (SPIRVTriple && Arch == (*SPIRVTriple).str()) {
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sarnex wrote:

Yeah so here this is a case where SPIR-V is an outlier so stuff gets weird. This code gets hit when `-fopenmp` is passed, `-fopenmp-targets` is not passed, and `--offload-arch` is passed and we need to deduce the toolchain based on the offload arch. I implemented it such that you can pass `spirv64-intel` to `--offload-arch` and it will use the SPIR-V OpenMP toolchain. Arch will be `spirv64-intel` so we go inside the `if` and everything works.

Another option is that we could not allow the `spirv64-intel` option to `--offload-arch` to deduce to the SPIR-V OpenMP toolchain in this case, so basically you can't use `--offload-arch` with this toolchain. Maybe that's philosophically better. 

Let me know what you think.

https://github.com/llvm/llvm-project/pull/120145