fix squeeze to output (1,) if all axes are squeezed. E.g squeeze((1,1,1...), None) case (#498)

topi/python/topi/transform.py

@@ -114,6 +114,8 @@ def squeeze(a, axis=None):
     for i, a_dim in enumerate(a_shape):
         if i not in search_axis:
             out_shape.append(a_dim)
+    if not out_shape:
+        out_shape.append(1)
     def _compute(*indices):
         real_indices = []
         flag = 0

topi/tests/python/test_topi_transform.py

@@ -82,7 +82,11 @@ def verify_squeeze(src_shape, axis):
         data_npy = np.random.normal(size=src_shape).astype(A.dtype)
         out_npy = np.squeeze(data_npy, axis=axis)
         data_nd = tvm.nd.array(data_npy, ctx)
-        out_nd = tvm.nd.empty(out_npy.shape, ctx=ctx, dtype=B.dtype)
+        if out_npy.shape == ():
+            out_nd_shape = (1,)
+        else:
+            out_nd_shape = out_npy.shape
+        out_nd = tvm.nd.empty(out_nd_shape, ctx=ctx, dtype=B.dtype)
         foo(data_nd, out_nd)
         np.testing.assert_allclose(out_nd.asnumpy(), out_npy)
 
@@ -159,6 +163,7 @@ def test_squeeze():
     verify_squeeze((1, 2, 3, 4), 0)
     verify_squeeze((1, 2, 1, 4), None)
     verify_squeeze((1, 1, 1, 4), (1, 2))
+    verify_squeeze((1, 1, 1, 1), None)
 
 
 def test_concatenate():