Theano flipping wtf

gistfile1.py

In [1]: import theano
Using gpu device 0: GeForce GT 540M

In [2]: import theano.tensor as T

In [3]: y = T.tensor4('y')

In [4]: f = theano.function([y], y)

In [5]: theano.printing.debugprint(y)
y [@A]

In [6]: theano.printing.debugprint(f)
DeepCopyOp [@A] 'y'   0
 |y [@B]

In [7]: f = theano.function([y], y[::-1])

In [8]: theano.printing.debugprint(f)
HostFromGpu [@A] ''   2
 |GpuSubtensor{::int64} [@B] ''   1
   |GpuFromHost [@C] ''   0
   | |y [@D]
   |Constant{-1} [@E]

In [9]: f = theano.function([y], y[::-1][::-1])

In [10]: theano.printing.debugprint(f)
HostFromGpu [@A] ''   12
 |GpuSubtensor{int64:int64:int64} [@B] ''   11
   |GpuFromHost [@C] ''   1
   | |y [@D]
   |ScalarFromTensor [@E] ''   9
   | |Elemwise{Composite{[Switch(i0, i1, maximum(i2, sub(i3, i4)))]}}[(0, 4)] [@F] ''   7
   |   |Elemwise{Composite{[LE(sub(i0, i1), i2)]}} [@G] ''   6
   |   | |Elemwise{Composite{[Switch(LT(*1 -> sub(i0, i1), i2), i2, *1)]}} [@H] ''   4
   |   | | |Elemwise{Composite{[Switch(LT(i0, i1), i1, i0)]}} [@I] ''   2
   |   | | | |Shape_i{0} [@J] ''   0
   |   | | | | |y [@D]
   |   | | | |TensorConstant{0} [@K]
   |   | | |Elemwise{Composite{[Switch(LT(*2 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, Switch(LT(i1, i2), i2, i1))]}(i0, Composite{[add(i0, int_div(i1, i0))]}(i1, *1 -> add(i2, i0)), i3), i3, *1), i3), i4), *2, i4)]}}[(0, 0)] [@L] ''   3
   |   | | | |Shape_i{0} [@J] ''   0
   |   | | | |TensorConstant{1} [@M]
   |   | | | |TensorConstant{-1} [@N]
   |   | | | |TensorConstant{0} [@K]
   |   | | | |Elemwise{Composite{[Switch(LT(i0, i1), i1, i0)]}} [@I] ''   2
   |   | | |TensorConstant{0} [@K]
   |   | |Elemwise{Composite{[Switch(LT(*1 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, add(i1, Switch(LT(i2, i3), i3, i2)))]}(i0, i1, Composite{[add(i0, int_div(i1, i0))]}(i2, *2 -> Composite{[sub(add(i0, i1), i2)]}(i3, i0, i1)), i4), i4, *2), i4), i5), *1, i5)]}} [@O] ''   5
   |   | | |Elemwise{Composite{[Switch(LT(i0, i1), i1, i0)]}} [@I] ''   2
   |   | | |Elemwise{Composite{[Switch(LT(*2 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, Switch(LT(i1, i2), i2, i1))]}(i0, Composite{[add(i0, int_div(i1, i0))]}(i1, *1 -> add(i2, i0)), i3), i3, *1), i3), i4), *2, i4)]}}[(0, 0)] [@L] ''   3
   |   | | |TensorConstant{1} [@M]
   |   | | |TensorConstant{-1} [@N]
   |   | | |TensorConstant{0} [@K]
   |   | | |Elemwise{Composite{[Switch(LT(*1 -> sub(i0, i1), i2), i2, *1)]}} [@H] ''   4
   |   | |TensorConstant{0} [@K]
   |   |TensorConstant{0} [@K]
   |   |Elemwise{Composite{[Switch(LT(*2 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, Switch(LT(i1, i2), i2, i1))]}(i0, Composite{[add(i0, int_div(i1, i0))]}(i1, *1 -> add(i2, i0)), i3), i3, *1), i3), i4), *2, i4)]}}[(0, 0)] [@L] ''   3
   |   |Elemwise{Composite{[Switch(LT(i0, i1), i1, i0)]}} [@I] ''   2
   |   |Elemwise{Composite{[Switch(LT(*1 -> sub(i0, i1), i2), i2, *1)]}} [@H] ''   4
   |ScalarFromTensor [@P] ''   10
   | |Elemwise{Composite{[Switch(i0, i1, maximum(i2, sub(i3, i4)))]}}[(0, 2)] [@Q] ''   8
   |   |Elemwise{Composite{[LE(sub(i0, i1), i2)]}} [@G] ''   6
   |   |TensorConstant{0} [@K]
   |   |Elemwise{Composite{[Switch(LT(*2 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, Switch(LT(i1, i2), i2, i1))]}(i0, Composite{[add(i0, int_div(i1, i0))]}(i1, *1 -> add(i2, i0)), i3), i3, *1), i3), i4), *2, i4)]}}[(0, 0)] [@L] ''   3
   |   |Elemwise{Composite{[Switch(LT(i0, i1), i1, i0)]}} [@I] ''   2
   |   |Elemwise{Composite{[Switch(LT(*1 -> Composite{[Switch(LT(i0, i1), i1, i0)]}(Composite{[Switch(LT(i0, i1), i2, i0)]}(Composite{[sub(i0, add(i1, Switch(LT(i2, i3), i3, i2)))]}(i0, i1, Composite{[add(i0, int_div(i1, i0))]}(i2, *2 -> Composite{[sub(add(i0, i1), i2)]}(i3, i0, i1)), i4), i4, *2), i4), i5), *1, i5)]}} [@O] ''   5
   |Constant{1} [@R]