[llvm] [CI][Github] Enable CIR CI build and test (PR #147430)

[Aiden Grossman via llvm-commits]

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@@ -267,6 +284,12 @@ def get_env_variables(modified_files: list[str], platform: str) -> Set[str]:
     runtimes_check_targets_needs_reconfig = _compute_project_check_targets(
         runtimes_to_test_needs_reconfig
     )
+
+    # Check if both clang and mlir are in projects_to_build to enable CIR
+    enable_cir = (
+        "ON" if "clang" in projects_to_build and "mlir" in projects_to_build else "OFF"
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boomanaiden154 wrote:

Ah, that makes more sense. This is definitely a bit of a hack.

How about making `_compute_projects_to_build` actually return CIR and then just removing it from the `projects_to_build` variable in this function? That keeps things more in line with how the rest of the script works.

https://github.com/llvm/llvm-project/pull/147430