WIP on building wheel variants

.github/workflows/variant-wheels.yml

@@ -0,0 +1,55 @@
+# Workflow to build and test wheels.
+# To work on the wheel building infrastructure on a fork, comment out:
+#
+# if: github.repository == 'numpy/numpy'
+#
+# in the get_commit_message job. Be sure to include [wheel build] in your commit
+# message to trigger the build. All files related to wheel building are located
+# at tools/wheels/
+# Alternatively, you can add labels to the pull request in order to trigger wheel
+# builds.
+# The labels that trigger builds are:
+# 36 - Build(for changes to the building process,
+# 14 - Release(ensure wheels build before release)
+name: Wheel builder
+
+on:
+  push:
+
+permissions:
+  contents: read # to fetch code (actions/checkout)
+
+jobs:
+  build_wheels:
+    name: Build wheel ${{ matrix.python }}-${{ matrix.blas }}-x86_64-${{ matrix.x86_64 }}
+    runs-on: ${{ matrix.buildplat[0] }}
+    strategy:
+      # Ensure that a wheel builder finishes even if another fails
+      fail-fast: false
+      matrix:
+        blas: [openblas, mkl]
+        # Github Actions doesn't support pairing matrix values together, let's improvise
+        # https://github.com/github/feedback/discussions/7835#discussioncomment-1769026
+        buildplat:
+          - [ubuntu-22.04, manylinux_x86_64, ""]
+        python: ["3.12"]
+        x86_64: [v1, v2, v3, v4]
+
+    steps:
+      - name: Checkout numpy
+        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2
+        with:
+          submodules: true
+          persist-credentials: false
+
+      - uses: prefix-dev/[email protected]
+
+      - name: Build wheels
+        run: pixi run -e ${{ matrix.blas }} build -Csetup-args=-Duse-ilp64=true -Cvariant=blas::variant::${{ matrix.blas }} -Cvariant=x86_64::level::${{ matrix.x86_64 }} -Ccompile-args=-v
+
+      - uses: actions/upload-artifact@v4
+        with:
+          name: wheel-${{ matrix.blas }}-x86-64-${{ matrix.x86_64 }}
+          path: dist/*.whl
+          if-no-files-found: error
+          compression-level: 0

meson.build

@@ -88,5 +88,25 @@ if host_machine.system() == 'darwin' and cc.has_link_argument('-Wl,-ld_classic')
   add_project_link_arguments('-Wl,-ld_classic', language : ['c', 'cpp'])
 endif
 
+blas_variant = ''
+x86_64_variant = ''
+
+foreach variant_meta : get_option('variant')
+  split_meta = variant_meta.split('::')
+  if split_meta.length() != 3
+    error('Invalid variant key: ' + variant_meta)
+  endif
+  if split_meta[0].strip() == 'blas' and split_meta[1].strip() == 'variant'
+    blas_variant = split_meta[2].strip()
+  elif split_meta[0].strip() == 'x86_64' and split_meta[1].strip() == 'level'
+    if host_machine.cpu_family() != 'x86_64'
+      error('Variant valid only on x86_64: ' + variant_meta)
+    endif
+    x86_64_variant = split_meta[2].strip()
+  else
+    error('Unsupported variant key: ' + variant_meta)
+  endif
+endforeach
+
 subdir('meson_cpu')
 subdir('numpy')

meson.options

@@ -40,3 +40,5 @@ option('test-simd', type: 'array',
         description: 'Specify a list of CPU features to be tested against NumPy SIMD interface')
 option('test-simd-args', type: 'string', value: '',
         description: 'Extra args to be passed to the `_simd` module that is used for testing the NumPy SIMD interface')
+option('variant', type: 'array', value: [],
+        description: 'Wheel variant keys')

meson_cpu/x86/meson.build

@@ -1,6 +1,23 @@
 source_root = meson.project_source_root()
 mod_features = import('features')
 
+if x86_64_variant != ''
+  if x86_64_variant == 'v1'
+    CPU_CONF_BASELINE = 'min'
+    CPU_CONF_DISPATCH = ''
+  elif x86_64_variant == 'v2'
+    CPU_CONF_BASELINE = 'SSE42'
+    CPU_CONF_DISPATCH = ''
+  elif x86_64_variant == 'v3'
+    CPU_CONF_BASELINE = 'AVX2'
+    CPU_CONF_DISPATCH = ''
+  elif x86_64_variant == 'v4'
+    CPU_CONF_BASELINE = 'AVX512_SKX'
+  else
+    error('Unknown x86_64 variant: ' + x86_64_variant)
+  endif
+endif
+
 SSE = mod_features.new(
   'SSE', 1,  args: '-msse',
   test_code: files(source_root + '/numpy/distutils/checks/cpu_sse.c')[0]

numpy/meson.build

@@ -60,14 +60,20 @@ allow_noblas = get_option('allow-noblas')
 # (see cibuildwheel settings in pyproject.toml), but used by CI jobs already
 blas_symbol_suffix = get_option('blas-symbol-suffix')
 
+# Variant overrides options directly specified
+if blas_variant != ''
+  blas_name = blas_variant
+  lapack_name = blas_variant
+  allow_noblas = false
+endif
+
 use_ilp64 = get_option('use-ilp64')
 if use_ilp64
   blas_interface = ['interface: ilp64']
 else
   blas_interface = ['interface: lp64']
 endif
 
-
 blas_order = get_option('blas-order')
 if blas_order == ['auto']
   blas_order = []

pixi.toml

@@ -0,0 +1,28 @@
+[workspace]
+channels = ["conda-forge"]
+name = "numpy-wheel-build"
+platforms = ["linux-64"]
+
+[tasks]
+build = "python -m build -w"
+
+[dependencies]
+c-compiler = "*"
+cxx-compiler = "*"
+fortran-compiler = "*"
+pkg-config = "*"
+pip = "*"
+python = "*"
+
+[pypi-dependencies]
+build = { git = "https://github.com/mgorny/build", branch = "variant-deps" }
+
+[feature.mkl.dependencies]
+mkl-devel = "*"
+
+[feature.openblas.dependencies]
+openblas = "*"
+
+[environments]
+mkl = ["mkl"]
+openblas = ["openblas"]

pyproject.toml

@@ -1,8 +1,9 @@
 [build-system]
 build-backend = "mesonpy"
 requires = [
-    "meson-python>=0.15.0",
+    "meson-python @ https://github.com/mgorny/meson-python/archive/wheel-variants.tar.gz",
     "Cython>=3.0.6",  # keep in sync with version check in meson.build
+    "variant_x86_64 @ https://github.com/wheelnext/variant_x86_64/archive/main.tar.gz ; 'x86_64' in variants"
 ]
 
 [project]