Fix `cupyx.ndimage.spline_filter1d` for hip
@@ -169,7 +169,9 @@ def _get_spline1d_code(mode, poles, n_boundary):
for (i = 1; i < n; ++i) {{
c[i * element_stride] += z * c[(i - 1) * element_stride];
}}''')
-
+ code.append('''
+ __syncthreads();
+ ''')
# initialize and apply the anti-causal filter
code.append(_anticausal_init_code(mode))
code.append('''
