Add Windows ARM64 builds

.github/scripts/install_openblas_arm64.ps1

@@ -0,0 +1,53 @@
+# Follow OpenBLAS's Windows ARM64 CI recipe, using its portable ARMV8 target:
+# https://github.com/OpenMathLib/OpenBLAS/blob/v0.3.33/.github/workflows/windows_arm64.yml
+$ErrorActionPreference = 'Stop'
+$PSNativeCommandUseErrorActionPreference = $true
+
+$version = '0.3.33'
+$archive = Join-Path $env:RUNNER_TEMP 'openblas-source.tar.gz'
+$source = Join-Path $env:RUNNER_TEMP "OpenBLAS-$version"
+$build = Join-Path $env:RUNNER_TEMP 'openblas-build'
+$prefix = Join-Path $env:RUNNER_TEMP 'openblas'
+$llvm = Join-Path $env:RUNNER_TEMP 'openblas-llvm'
+$installer = Join-Path $env:RUNNER_TEMP 'LLVM-20.1.8-woa64.exe'
+
+Invoke-WebRequest -OutFile $archive -Uri "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/OpenMathLib/OpenBLAS/releases/download/v$version/OpenBLAS-$version.tar.gz"
+if ((Get-FileHash $archive -Algorithm SHA256).Hash -ne '6761af1d9f5d353ab4f0b7497be2643313b36c8f31caec0144bfef198e71e6ab') {
+    throw 'OpenBLAS source checksum mismatch'
+}
+tar -xf $archive -C $env:RUNNER_TEMP
+
+# Pin the C and Fortran toolchain used by the upstream recipe. Keep it separate
+# from the runner's LLVM, which does not necessarily include flang-new.
+Invoke-WebRequest -OutFile $installer -Uri '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/llvm/llvm-project/releases/download/llvmorg-20.1.8/LLVM-20.1.8-woa64.exe'
+if ((Get-FileHash $installer -Algorithm SHA256).Hash -ne '7c4ac97eb2ae6b960ca5f9caf3ff6124c8d2a18cc07a7840a4d2ea15537bad8e') {
+    throw 'LLVM installer checksum mismatch'
+}
+$install = Start-Process -FilePath $installer -ArgumentList '/S', "/D=$llvm" -Wait -PassThru
+if ($install.ExitCode -ne 0) { throw "LLVM installation failed: $($install.ExitCode)" }
+
+# Locate Visual Studio rather than depending on its version or edition.
+$vswhere = Join-Path ${env:ProgramFiles(x86)} 'Microsoft Visual Studio\Installer\vswhere.exe'
+$vs = & $vswhere -latest -products '*' -requires Microsoft.VisualStudio.Component.VC.Tools.ARM64 -property installationPath
+if (-not $vs) { throw 'Visual Studio ARM64 tools were not found' }
+# Initialize the current PowerShell process without passing paths through cmd.
+& (Join-Path $vs 'Common7\Tools\Launch-VsDevShell.ps1') -Arch arm64 -HostArch arm64 -SkipAutomaticLocation
+$env:PATH = "$llvm\bin;$env:PATH"
+
+cmake -S $source -B $build -G Ninja `
+    -DCMAKE_BUILD_TYPE=Release `
+    -DTARGET=ARMV8 `
+    -DDYNAMIC_ARCH=OFF `
+    -DBINARY=64 `
+    -DCMAKE_C_COMPILER=clang-cl `
+    -DCMAKE_Fortran_COMPILER=flang-new `
+    -DBUILD_SHARED_LIBS=ON `
+    -DCMAKE_SYSTEM_PROCESSOR=arm64 `
+    -DCMAKE_SYSTEM_NAME=Windows `
+    "-DCMAKE_INSTALL_PREFIX=$prefix"
+cmake --build $build --parallel 4
+cmake --install $build
+
+# Meson uses the CMake package; delvewheel bundles the DLL found on PATH.
+"CMAKE_PREFIX_PATH=$prefix" | Out-File -Append -Encoding utf8 $env:GITHUB_ENV
+"$prefix\bin" | Out-File -Append -Encoding utf8 $env:GITHUB_PATH

.github/workflows/build.yml

@@ -241,29 +241,45 @@ jobs:
             arch: auto
           - os: windows-latest
             arch: auto
+          - os: windows-11-arm
+            arch: auto
 
     steps:
       - uses: actions/checkout@v7
         with:
           submodules: true
 
-      - name: Set up MSVC for Windows
-        if: runner.os == 'Windows'
-        uses: egor-tensin/vs-shell@v2
-
-      - name: Install conda on Windows
-        if: runner.os == 'Windows'
-        uses: conda-incubator/setup-miniconda@v4
-        with:
-          miniconda-version: "latest"
-          channels: conda-forge, anaconda
+      - name: Install OpenBLAS on Windows x64
+        # meson finds OpenBLAS via its CMake config; delvewheel finds the DLL via PATH.
+        # 0.3.34 is skipped: its DGEMM kernels crash on AMD Zen 4/5 CPUs that
+        # expose AVX-512 (Fixed in OpenMathLib/OpenBLAS#6013. Bump with the next release.)
+        if: runner.os == 'Windows' && runner.arch == 'X64'
+        shell: pwsh
+        run: |
+          $version = '0.3.33'
+          $sha256 = '7ad797ef0c9a5c42e28903bf726eaaaade307dafe187ff0e923d90cd4002780c'
+          $zip = Join-Path $env:RUNNER_TEMP 'openblas.zip'
+          $dest = Join-Path $env:RUNNER_TEMP 'openblas'
+          Invoke-WebRequest -OutFile $zip `
+            -Uri "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/OpenMathLib/OpenBLAS/releases/download/v$version/OpenBLAS-$version-x64.zip"
+          if ((Get-FileHash $zip -Algorithm SHA256).Hash -ne $sha256) { throw 'OpenBLAS checksum mismatch' }
+          Expand-Archive $zip -DestinationPath $dest
+          $root = $dest
+          # The x64 (MinGW) CMake config points the linker at the DLL instead of its import library.
+          # (Fixed in OpenMathLib/OpenBLAS#6091. Can be removed with the next release.)
+          $cfg = Join-Path $root 'lib\cmake\openblas\OpenBLASConfig.cmake'
+          if (Test-Path $cfg) {
+            (Get-Content $cfg) -replace 'bin/libopenblas\.dll', 'lib/libopenblas.lib' | Set-Content $cfg
+          }
+          "CMAKE_PREFIX_PATH=$root" | Out-File -Append -Encoding utf8 $env:GITHUB_ENV
+          "$root\bin" | Out-File -Append -Encoding utf8 $env:GITHUB_PATH
 
-      - name: Install openblas from conda on Windows
-        if: runner.os == 'Windows'
-        # 0.3.33 pinned: conda-forge's win-64 0.3.34 build crashes inside its
-        # DGEMM kernels on AMD Zen 4/5 CPUs that expose AVX-512
-        # (conda-forge/openblas-feedstock#196). Unpin once a fixed build ships.
-        run: conda install -y "openblas=0.3.33" pkgconfig
+      - name: Build OpenBLAS for Windows ARM64
+        # The upstream woa64 DLL targets NEOVERSEN1 and requires LSE atomics.
+        # Build for ARMV8 so the wheels also work on older Windows ARM64 CPUs.
+        if: runner.os == 'Windows' && runner.arch == 'ARM64'
+        shell: pwsh
+        run: ./.github/scripts/install_openblas_arm64.ps1
 
       - name: Build wheels
         uses: pypa/cibuildwheel@v4.2.1

pyproject.toml

@@ -41,6 +41,8 @@ dependencies = [
 [tool.cibuildwheel]
 skip = [
   "*-win32", # fails on locating Python headers, probably meson.build is misconfigured
+  # there are no CPython win_arm64 releases before 3.11
+  "cp39-win_arm64", "cp310-win_arm64",
   "*musllinux*aarch64*" # no Scipy wheels for this
 ]
 # Test
@@ -61,6 +63,7 @@ archs = [
 
 [tool.cibuildwheel.windows]
 before-build = "pip install delvewheel"
+config-settings = {setup-args = "--vsenv"}
 # This will probably become default in newer cibuildwheels versions
 repair-wheel-command = "delvewheel repair -w {dest_dir} {wheel}"