Add gradient for ResizeBilinear (#239)

tensorflow-ops/src/TensorFlow/Gradient.hs

@@ -817,6 +817,17 @@ opGrad "Tile" _ [toT -> x, toT -> multiples] [dz] =
     axes = CoreOps.range 0 (CoreOps.size splitShape) (2 :: Tensor Build Int32)
     reshapedDz = CoreOps.reshape dz splitShape
 
+opGrad "ResizeBilinear" nodeDef [toT -> x, _] [dz] =
+    [ Just $ CoreOps.resizeBilinearGrad'
+               (opAttr "align_corners" .~ align)
+               (CoreOps.cast dz)
+               x
+
+    , Nothing
+    ]
+  where
+    align = lookupAttr nodeDef "align_corners" :: Bool
+
 opGrad "ZerosLike" _ _ _ = [Nothing]
 opGrad "Fill" _ _ [dz] = [Nothing, Just $ sum dz rx]
   where
@@ -894,6 +905,7 @@ numOutputs o =
         "Sum" -> 1
         "Tanh" -> 1
         "Tile" -> 1
+        "ResizeBilinear" -> 1
         "Transpose" -> 1
         "TruncatedNormal" -> 1
         "VarHandleOp" -> 1

tensorflow-ops/tests/GradientTest.hs

@@ -32,7 +32,7 @@ import Control.Monad(forM_, replicateM, zipWithM)
 import Control.Monad.IO.Class (liftIO)
 
 import qualified TensorFlow.Core as TF
-import qualified TensorFlow.GenOps.Core as TF (conv2DBackpropInput', max, maximum, tile, pad, batchToSpaceND, spaceToBatchND, squeeze, sqrt, slice, shape)
+import qualified TensorFlow.GenOps.Core as TF (conv2DBackpropInput', max, maximum, resizeBilinear', tile, pad, batchToSpaceND, spaceToBatchND, squeeze, sqrt, slice, shape)
 import qualified TensorFlow.Gradient as TF
 import qualified TensorFlow.Ops as TF hiding (zeroInitializedVariable, shape)
 import qualified TensorFlow.Output as TF
@@ -429,6 +429,22 @@ testTile2DGrad = testCase "testTileGrad2D" $ do
     shapeX @=? (shapeDX :: V.Vector Int32)
     V.fromList [6, 6, 6, 6, 6, 6::Float] @=? (dx :: V.Vector Float)
 
+testResizeBilinearGrad :: Test
+testResizeBilinearGrad = testCase "testResizeBilinearGrad" $ do
+    (dx, shapeDX, shapeX) <- TF.runSession $ do
+        let shape = TF.vector [1, 2, 2, 1 :: Int32]
+        x <- TF.render $ TF.fill shape (TF.scalar (1 :: Float))
+        let outSize = TF.vector [4, 4 :: Int32]
+            align = TF.opAttr "align_corners" .~ True
+            y = TF.resizeBilinear' align x outSize
+
+        [dx] <- TF.gradients y [x]
+        TF.run (dx, TF.shape dx, TF.shape x)
+    shapeX @=? (shapeDX :: V.Vector Int32)
+    let expect = V.fromList [4, 4, 4, 4 :: Float]
+        near = 0.00001 > (V.sum $ V.zipWith (-) expect (dx :: V.Vector Float))
+    near @=? True
+
 matMulGradient :: Test
 matMulGradient = testCase "matMulGradients" $ do
 
@@ -553,6 +569,7 @@ main = defaultMain
             , testFillGrad
             , testTileGrad
             , testTile2DGrad
+            , testResizeBilinearGrad
             , matMulGradient
             , matMulGradGrad
             , matMulTransposeGradient (False, False)