[clang] [clang][Driver][SPIR-V] Allow linking IR using llvm-link (PR #169572)

[Manuel Carrasco via cfe-commits]

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@@ -4595,7 +4598,14 @@ void Driver::BuildDefaultActions(Compilation &C, DerivedArgList &Args,
       LA->propagateHostOffloadInfo(C.getActiveOffloadKinds(),
                                    /*BoundArch=*/nullptr);
     } else {
-      LA = C.MakeAction<LinkJobAction>(LinkerInputs, types::TY_Image);
+      // If we are linking but were passed -emit-llvm, we will be calling
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mgcarrasco wrote:

I understand your point that based on the test cases, at the moment, the SPIRV TC seems to be the only one that exercises the `types::TY_LLVM_BC` case. However, this is in the driver and it can potentially be exercised by other new or untested compilation paths. I don't have enough context on the driver to know if it is appropriate to always make the `LinkJobAction` emit bitcode for `-emit-llvm` other than the SPIRV TC case. 

How would the condition be to restrict these changes only to your scenario? Perhaps at the cost of readability that is the safest path to take.

https://github.com/llvm/llvm-project/pull/169572