Make check for SVE support happen on demand and not during module import

The check would invoke an external process which would slow down imports

Author: joaoe

numpy/_core/tests/test_multiarray.py

@@ -30,7 +30,7 @@
     assert_array_equal, assert_raises_regex, assert_array_almost_equal,
     assert_allclose, IS_PYPY, IS_WASM, IS_PYSTON, HAS_REFCOUNT,
     assert_array_less, runstring, temppath, suppress_warnings, break_cycles,
-    _SUPPORTS_SVE, assert_array_compare,
+    check_support_sve, assert_array_compare,
     )
 from numpy.testing._private.utils import requires_memory, _no_tracing
 from numpy._core.tests._locales import CommaDecimalPointLocale
@@ -10119,7 +10119,7 @@ def test_non_c_contiguous(self):
         assert_array_equal(x.view('<i2'), expected)
 
 
-@pytest.mark.xfail(_SUPPORTS_SVE, reason="gh-22982")
+@pytest.mark.xfail(check_support_sve(), reason="gh-22982")
 # Test various array sizes that hit different code paths in quicksort-avx512
 @pytest.mark.parametrize("N", np.arange(1, 512))
 @pytest.mark.parametrize("dtype", ['e', 'f', 'd'])

numpy/_core/tests/test_scalarmath.py

@@ -16,7 +16,7 @@
 from numpy.testing import (
     assert_, assert_equal, assert_raises, assert_almost_equal,
     assert_array_equal, IS_PYPY, suppress_warnings, _gen_alignment_data,
-    assert_warns, _SUPPORTS_SVE,
+    assert_warns, check_support_sve,
     )
 
 types = [np.bool, np.byte, np.ubyte, np.short, np.ushort, np.intc, np.uintc,
@@ -151,7 +151,7 @@ def test_int_float_promotion_truediv(fscalar):
 
 
 class TestBaseMath:
-    @pytest.mark.xfail(_SUPPORTS_SVE, reason="gh-22982")
+    @pytest.mark.xfail(check_support_sve(), reason="gh-22982")
     def test_blocked(self):
         # test alignments offsets for simd instructions
         # alignments for vz + 2 * (vs - 1) + 1

numpy/testing/_private/utils.py

@@ -40,7 +40,7 @@
         'SkipTest', 'KnownFailureException', 'temppath', 'tempdir', 'IS_PYPY',
         'HAS_REFCOUNT', "IS_WASM", 'suppress_warnings', 'assert_array_compare',
         'assert_no_gc_cycles', 'break_cycles', 'HAS_LAPACK64', 'IS_PYSTON',
-        'IS_MUSL', '_SUPPORTS_SVE', 'NOGIL_BUILD',
+        'IS_MUSL', 'check_support_sve', 'NOGIL_BUILD',
         'IS_EDITABLE', 'run_threaded',
         ]
 
@@ -1374,21 +1374,24 @@ def rundocs(filename=None, raise_on_error=True):
         raise AssertionError("Some doctests failed:\n%s" % "\n".join(msg))
 
 
-def check_support_sve():
+def check_support_sve(__cache=[]):
     """
     gh-22982
     """
-
+    
+    if __cache:
+        return __cache[0]
+    
     import subprocess
     cmd = 'lscpu'
     try:
         output = subprocess.run(cmd, capture_output=True, text=True)
-        return 'sve' in output.stdout
-    except OSError:
-        return False
-
+        result = 'sve' in output.stdout
+    except (OSError, subprocess.SubprocessError):
+        result = False
+    __cache.append(result)
+    return __cache[0]
 
-_SUPPORTS_SVE = check_support_sve()
 
 #
 # assert_raises and assert_raises_regex are taken from unittest.