[TOPI] improve elemwise schedule (#393)

* [TOPI] improve elemwise schedule

* modify fuse

topi/python/topi/cuda/elemwise.py

@@ -23,17 +23,10 @@ def schedule_elemwise(outs):
 
     x = outs[0]
     num_dim = len(x.shape)
-    block_factor = tvm.ir_pass.Simplify(x.op.output(0).shape[num_dim-1]).value
-    if block_factor % 48 == 0:
-        block_factor = 48
-    elif block_factor % 32 == 0:
-        block_factor = 32
-    bx, tx = s[x].split(x.op.axis[num_dim-1], factor=block_factor)
-    for i in range(num_dim-2, 0, -1):
-        bx = s[x].fuse(bx, x.op.axis[i])
-
+    fused = s[x].fuse(*x.op.axis)
+    num_thread = 64
+    bx, tx = s[x].split(fused, factor=num_thread)
     s[x].bind(bx, tvm.thread_axis("blockIdx.x"))
     s[x].bind(tx, tvm.thread_axis("threadIdx.x"))
 
-
     return s