[clang] [HIP][SPIRV] Enable the SPIRV backend instead of the translator through an experimental flag. (PR #162282)

[Manuel Carrasco via cfe-commits]

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@@ -3672,29 +3672,45 @@ class OffloadingActionBuilder final {
             // compiler phases, including backend and assemble phases.
             ActionList AL;
             Action *BackendAction = nullptr;
+            bool AssembleAndLink = true;
             if (ToolChains.front()->getTriple().isSPIRV() ||
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mgcarrasco wrote:

@jhuber6 thanks for the feedback! I'm not sure if I follow what's the problem or suggestion. What step(s) and for what scenario(s) can be skipped? If so, where that should/would be handled? 

A backend job was always created independently of SPIRV prior to the PR. Now it has been updated so it does using the SPIRV backend directly if needed. The assembler and linker step are now skipped for SPIRV when using the backend. When using the translator, we still have to maintain the previous phases. 

https://github.com/llvm/llvm-project/pull/162282