simplify expr in get_const_tuple (#795)

* fix upsampling output shape

* simplify expr in get_const_tuple

topi/python/topi/nn/upsampling.py

 """TVM operator upsampling compute."""
 from __future__ import absolute_import
 import tvm
+from .. import util
 
 
 def upsampling(data, scale):
@@ -21,8 +22,8 @@ def upsampling(data, scale):
         4-D with shape [batch, channel, in_height*scale, in_width*scale]
     """
     batch, channel, height, width = data.shape
-    out_height = height * scale
-    out_width = width * scale
+    out_height = util.simplify(height * scale)
+    out_width = util.simplify(width * scale)
 
     return tvm.compute((batch, channel, out_height, out_width), \
                         lambda n, c, h, w: data[n, c, h/scale, w/scale])

topi/python/topi/util.py

@@ -59,9 +59,8 @@ def get_const_tuple(in_tuple):
     """
     out_tuple = ()
     for elem in in_tuple:
-        if not isinstance(elem, (tvm.expr.IntImm, tvm.expr.UIntImm)):
-            raise ValueError("Element of input tuple should be const int")
-        out_tuple = out_tuple + (elem.value, )
+        value = get_const_int(elem)
+        out_tuple = out_tuple + (value, )
     return out_tuple