numpy · charris · May 4, 2021 · Apr 28, 2021 · Apr 30, 2021 · May 1, 2021
diff --git a/doc/release/upcoming_changes/18874.change.rst b/doc/release/upcoming_changes/18874.change.rst
@@ -0,0 +1,11 @@
+Enable Accelerate Framework
+----------------------------
+With the release of macOS 11.3, several different issues that
+numpy was encountering when using Accelerate Framework's
+implementation of BLAS and LAPACK should be resolved.  This
+change enables the Accelerate Framework as an option on macOS.
+If additional issues are found, please file a bug report
+against Accelerate using the developer feedback assistant
+tool (https://developer.apple.com/bug-reporting/). We
+intend to address issues promptly and plan to continue
+supporting and updating our BLAS and LAPACK libraries.
diff --git a/numpy/core/setup.py b/numpy/core/setup.py
@@ -405,11 +405,6 @@ def configuration(parent_package='',top_path=None):
     from numpy.distutils.system_info import (get_info, blas_opt_info,
                                              lapack_opt_info)
 
-    # Accelerate is buggy, disallow it. See also numpy/linalg/setup.py
-    for opt_order in (blas_opt_info.blas_order, lapack_opt_info.lapack_order):
-        if 'accelerate' in opt_order:
-            opt_order.remove('accelerate')
-
     config = Configuration('core', parent_package, top_path)
     local_dir = config.local_path
     codegen_dir = join(local_dir, 'code_generators')

diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
@@ -6194,6 +6194,71 @@ def test_dot_array_order(self):
         assert_equal(np.dot(b, a), res)
         assert_equal(np.dot(b, b), res)
 
+    def test_accelerate_framework_sgemv_fix(self):
+
+        def aligned_array(shape, align, dtype, order='C'):
+            d = dtype(0)
+            N = np.prod(shape)
+            tmp = np.zeros(N * d.nbytes + align, dtype=np.uint8)
+            address = tmp.__array_interface__["data"][0]
+            for offset in range(align):
+                if (address + offset) % align == 0:
+                    break
+            tmp = tmp[offset:offset+N*d.nbytes].view(dtype=dtype)
+            return tmp.reshape(shape, order=order)
+
+        def as_aligned(arr, align, dtype, order='C'):
+            aligned = aligned_array(arr.shape, align, dtype, order)
+            aligned[:] = arr[:]
+            return aligned
+
+        def assert_dot_close(A, X, desired):
+            assert_allclose(np.dot(A, X), desired, rtol=1e-5, atol=1e-7)
+
+        m = aligned_array(100, 15, np.float32)
+        s = aligned_array((100, 100), 15, np.float32)
+        np.dot(s, m)  # this will always segfault if the bug is present
+
+        testdata = itertools.product((15, 32), (10000,), (200, 89), ('C', 'F'))
+        for align, m, n, a_order in testdata:
+            # Calculation in double precision
+            A_d = np.random.rand(m, n)
+            X_d = np.random.rand(n)
+            desired = np.dot(A_d, X_d)
+            # Calculation with aligned single precision
+            A_f = as_aligned(A_d, align, np.float32, order=a_order)
+            X_f = as_aligned(X_d, align, np.float32)
+            assert_dot_close(A_f, X_f, desired)
+            # Strided A rows
+            A_d_2 = A_d[::2]
+            desired = np.dot(A_d_2, X_d)
+            A_f_2 = A_f[::2]
+            assert_dot_close(A_f_2, X_f, desired)
+            # Strided A columns, strided X vector
+            A_d_22 = A_d_2[:, ::2]
+            X_d_2 = X_d[::2]
+            desired = np.dot(A_d_22, X_d_2)
+            A_f_22 = A_f_2[:, ::2]
+            X_f_2 = X_f[::2]
+            assert_dot_close(A_f_22, X_f_2, desired)
+            # Check the strides are as expected
+            if a_order == 'F':
+                assert_equal(A_f_22.strides, (8, 8 * m))
+            else:
+                assert_equal(A_f_22.strides, (8 * n, 8))
+            assert_equal(X_f_2.strides, (8,))
+            # Strides in A rows + cols only
+            X_f_2c = as_aligned(X_f_2, align, np.float32)
+            assert_dot_close(A_f_22, X_f_2c, desired)
+            # Strides just in A cols
+            A_d_12 = A_d[:, ::2]
+            desired = np.dot(A_d_12, X_d_2)
+            A_f_12 = A_f[:, ::2]
+            assert_dot_close(A_f_12, X_f_2c, desired)
+            # Strides in A cols and X
+            assert_dot_close(A_f_12, X_f_2, desired)
+
+
 
 class MatmulCommon:
     """Common tests for '@' operator and numpy.matmul.

diff --git a/numpy/distutils/system_info.py b/numpy/distutils/system_info.py
@@ -375,22 +375,6 @@ def add_system_root(library_root):
 so_ext = get_shared_lib_extension()
 
 
-def is_symlink_to_accelerate(filename):
-    accelpath = '/System/Library/Frameworks/Accelerate.framework'
-    return (sys.platform == 'darwin' and os.path.islink(filename) and
-            os.path.realpath(filename).startswith(accelpath))
-
-
-_accel_msg = (
-    'Found {filename}, but that file is a symbolic link to the '
-    'MacOS Accelerate framework, which is not supported by NumPy. '
-    'You must configure the build to use a different optimized library, '
-    'or disable the use of optimized BLAS and LAPACK by setting the '
-    'environment variables NPY_BLAS_ORDER="" and NPY_LAPACK_ORDER="" '
-    'before building NumPy.'
-)
-
-
 def get_standard_file(fname):
     """Returns a list of files named 'fname' from
     1) System-wide directory (directory-location of this module)
@@ -539,6 +523,7 @@ def get_info(name, notfound_action=0):
           'blis': blis_info,                  # use blas_opt instead
           'lapack_mkl': lapack_mkl_info,      # use lapack_opt instead
           'blas_mkl': blas_mkl_info,          # use blas_opt instead
+          'accelerate': accelerate_info,      # use blas_opt instead
           'openblas64_': openblas64__info,
           'openblas64__lapack': openblas64__lapack_info,
           'openblas_ilp64': openblas_ilp64_info,
@@ -1029,9 +1014,6 @@ def _find_lib(self, lib_dir, lib, exts):
             for prefix in lib_prefixes:
                 p = self.combine_paths(lib_dir, prefix + lib + ext)
                 if p:
-                    # p[0] is the full path to the binary library file.
-                    if is_symlink_to_accelerate(p[0]):
-                        raise RuntimeError(_accel_msg.format(filename=p[0]))
                     break
             if p:
                assert len(p) == 1
@@ -1766,8 +1748,10 @@ def get_atlas_version(**config):
 
 class lapack_opt_info(system_info):
     notfounderror = LapackNotFoundError
+
     # List of all known LAPACK libraries, in the default order
-    lapack_order = ['mkl', 'openblas', 'flame', 'atlas', 'lapack']
+    lapack_order = ['mkl', 'openblas', 'flame',
+                    'accelerate', 'atlas', 'lapack']
     order_env_var_name = 'NPY_LAPACK_ORDER'
 
     def _calc_info_mkl(self):
@@ -1942,7 +1926,9 @@ class lapack64__opt_info(lapack_ilp64_opt_info):
 class blas_opt_info(system_info):
     notfounderror = BlasNotFoundError
     # List of all known BLAS libraries, in the default order
-    blas_order = ['mkl', 'blis', 'openblas', 'atlas', 'blas']
+
+    blas_order = ['mkl', 'blis', 'openblas',
+                  'accelerate', 'atlas', 'blas']
     order_env_var_name = 'NPY_BLAS_ORDER'
 
     def _calc_info_mkl(self):

diff --git a/numpy/linalg/setup.py b/numpy/linalg/setup.py
@@ -9,11 +9,6 @@ def configuration(parent_package='', top_path=None):
 
     config.add_subpackage('tests')
 
-    # Accelerate is buggy, disallow it. See also numpy/core/setup.py
-    for opt_order in (blas_opt_info.blas_order, lapack_opt_info.lapack_order):
-        if 'accelerate' in opt_order:
-            opt_order.remove('accelerate')
-
     # Configure lapack_lite
 
     src_dir = 'lapack_lite'