[llvm] Add pre-merge workflow for HLSL testing (PR #122184)

[Chris B via llvm-commits]

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@@ -0,0 +1,26 @@
+name: HLSL Tests - macOS
+
+permissions:
+  contents: read
+  checks: write
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llvm-beanz wrote:

Probably don't, I think this was a misunderstanding on my part about the permissions required for the action to report its status check. Will remove.

https://github.com/llvm/llvm-project/pull/122184