Status

• OpenBLAS can be built from source for WoA using LLVM toolchain (clang-cl and flang)

• Build and test passing for v0.3.24 (prebuilt package).

Build from Source

Requirements

• LLVM >= 17.0.4
  (<= 16 emits conflicting symbols_QQ*, <= 17.0.3 mlir conflicting symbol)

• CMake >= 3.28 (previous version fail with flang targeting MSVC ABI)

Build Steps

• Clone OpenBLAS from GitHub - OpenMathLib/OpenBLAS: OpenBLAS is an optimized BLAS library based on GotoBLAS2 1.13 BSD version.

  git clone https://github.com/OpenMathLib/OpenBLAS cd OpenBLAS mkdir build cd build cmake .. -G Ninja -DCMAKE_C_COMPILER=clang-cl -DCMAKE_Fortran_COMPILER=flang-new -DBUILD_SHARED_LIBS=TRUE -DCMAKE_BUILD_TYPE=Release ninja

Related PRs

• Add support for windows/arm64 targets with clang by niyas-sait · Pull Request #3345 · OpenMathLib/OpenBLAS

• [win/arm64]: Explicit casting for GEMM_DEFAULT_ALIGN to create 64-bit value by niyas-sait · Pull Request #3354 · OpenMathLib/OpenBLAS

• https://gitlab.kitware.com/cmake/cmake/-/merge_requests/8852

• LLVM 17.0.4 fix: PR for llvm/llvm-project#70458 by llvmbot · Pull Request #752 · llvm/llvm-project-release-prs

Binary availability

OpenBLAS has to be built from source for windows-arm64.

CI

There is no official windows-arm64 CI running for OpenBLAS, due to lack of machines on GitHub Actions. We run a downstream nightly CI (building develop branch and running tests) on our infrastructure: linaro / WindowsOnArm / nightly · GitLab.