Build numpy with cpu-baseline=none for x86_64/generic

.github/workflows/test-eb-hooks.yml

@@ -168,3 +168,44 @@ jobs:
               # echo "$OUT" | grep -qiF 'add_property("arch","gpu")'
               # echo "$OUT" | grep -qiF 'setenv("EESSIROCMVERSION","6.4.1")'
               # echo "rompi toolchain handled"
+
+  check_numpy_generic_cpu_baseline:
+    runs-on: ubuntu-24.04
+    strategy:
+      matrix:
+        include:
+          - EESSI_VERSION: '2025.06'
+            EASYCONFIG: 'SciPy-bundle-2025.07-gfbf-2025b.eb'
+
+    steps:
+        - name: Check out software-layer repository
+          uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+
+        - name: Mount EESSI CernVM-FS repository
+          uses: eessi/github-action-eessi@v3
+          with:
+            eessi_stack_version: ${{matrix.EESSI_VERSION}}
+            use_eessi_module: true
+
+        - name: Test that numpy uses cpu-baseline=none for x86_64/generic
+          if: ${{ github.event_name == 'pull_request' }}
+          run: |
+              module load EESSI-extend/${{matrix.EESSI_VERSION}}-easybuild
+
+              # the hook prints a message when it adds the option to the numpy installopts
+              baseline_msg() {
+                  eb --hooks=$PWD/eb_hooks.py --extended-dry-run "$@" ${{matrix.EASYCONFIG}} 2>&1 \
+                      | grep -c 'Using cpu-baseline=none for numpy'
+              }
+
+              [ "$(baseline_msg)" = 0 ]
+              echo "Native target keeps the default numpy cpu-baseline"
+
+              [ "$(EESSI_SOFTWARE_SUBDIR=aarch64/generic baseline_msg)" = 0 ]
+              echo "aarch64/generic keeps the default numpy cpu-baseline"
+
+              [ "$(EESSI_SOFTWARE_SUBDIR=x86_64/generic baseline_msg)" = 1 ]
+              echo "x86_64/generic uses cpu-baseline=none"
+
+              [ "$(baseline_msg --optarch=GENERIC)" = 1 ]
+              echo "--optarch=GENERIC uses cpu-baseline=none"

eb_hooks.py

@@ -2105,8 +2105,22 @@ def pre_single_extension_numpy(ext, *args, **kwargs):
     Pre-extension hook for numpy:
       - change -march=native to -march=armv8.4-a for numpy 1.24.2 when building for aarch64/neoverse_v1 CPU target
       - change -march=native to -march=armv8.2-a for numpy 1.24.2 when building for aarch64/a64fx CPU target
+      - use cpu-baseline=none for numpy >= 1.26 (built with meson) when building for x86_64/generic;
+        the default baseline ('min') is SSE3 in numpy 1.26-2.3 and x86-64-v2 in numpy >= 2.4,
+        while x86_64/generic should only need x86-64 (SSE2); the dispatched code paths for newer
+        CPU features are unaffected and are still selected at runtime, see
+        https://numpy.org/doc/stable/reference/simd/build-options.html
     """
     cpu_target = get_eessi_envvar('EESSI_SOFTWARE_SUBDIR')
+    x86_64_generic = cpu_target == CPU_TARGET_X86_64_GENERIC or (
+        get_cpu_architecture() == X86_64 and build_option('optarch') == OPTARCH_GENERIC)
+    if ext.name == 'numpy' and x86_64_generic and LooseVersion(ext.version) >= LooseVersion('1.26'):
+        baseline_opt = "-Csetup-args=-Dcpu-baseline=none"
+        installopts = ext.cfg.get('installopts', '') or ''
+        if baseline_opt not in installopts:
+            ext.cfg['installopts'] = (installopts + ' ' + baseline_opt).strip()
+            print_msg("Using cpu-baseline=none for %s %s on x86_64/generic: %s",
+                      ext.name, ext.version, ext.cfg['installopts'])
     if ext.name == 'numpy' and ext.version == '1.24.2':
         # note: this hook is called before build environment is set up (by calling toolchain.prepare()),
         # so environment variables like $CFLAGS are not defined yet