[llvm] [HLSL] Migrate pre-commit HLSL CI to Windows (and off Beanz's closet Mac) (PR #226312)

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llvmorg-github-actions[bot] wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-github-workflow

Author: Helena Kotas (hekota)

<details>
<summary>Changes</summary>

Pull requests validation of HLSL and DirectX changes includes a run of [offload test suite](https://github.com/llvm/offload-test-suite), which executes on a Mac laptop in Beanz' closet. This change updates the pipeline to run on an Azure-hosted Windows Server 2022 runner, with software GPU offload coverage through D3D12 WARP.

Moving the build to the VM "as is" resulted in build times up to 3 hours. The pipeline has been adjusted to reduce the build time to approximately 37 minutes by: 

- Building only `hlsl-test-depends` instead of broad LLVM and Clang targets.
- Running only `check-hlsl-unit` and `check-hlsl-clang-warp-d3d12` instead of the full LLVM and Clang test suites. The usual LLVM pre-merge workflow already covers generic LLVM and Clang regressions and there is no need to duplicate this work. 
- Downloading the latest stable `Microsoft.Direct3D.DXC` NuGet package and using its prebuilt `dxv.exe`, `dxcompiler.dll`, and `dxil.dll` instead of building DXC from source.
- Compiling LLVM with `clang-cl` and linking with LLD.
 
Assisted by GPT-5.6 Sol

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Full diff: https://github.com/llvm/llvm-project/pull/226312.diff


2 Files Affected:

- (modified) .github/workflows/hlsl-matrix.yaml (+3-4) 
- (modified) .github/workflows/hlsl-test-all.yaml (+26-25) 


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</details>


https://github.com/llvm/llvm-project/pull/226312