add slice support for dim < 0 (#16494)

* add slice support for dim < 0 test=develop

python/paddle/fluid/framework.py

@@ -789,13 +789,24 @@ class Variable(object):
         if isinstance(item, tuple):
             if len(item) > len(self.shape):
                 raise IndexError("Too many indexes")
+            fixedSize = True
+            for i in range(len(self.shape)):
+                if self.shape[i] == -1:
+                    fixedSize = False
+                    break
+
             newitem = self._reconstructSliceinfo(item) or item
-            check, info = self._detectContinuesSlice(newitem)
-            if check:
-                starts = info[0]
-                ends = info[1]
-                axes = [i for i in range(len(starts))]
-                return self._sliceVar(axes, starts, ends)
+            if fixedSize:
+                check, info = self._detectContinuesSlice(newitem)
+                if check and fixedSize:
+                    starts = info[0]
+                    ends = info[1]
+                    axes = [i for i in range(len(starts))]
+                    return self._sliceVar(axes, starts, ends)
+                else:
+                    new_var = self
+                    for index, o in enumerate(newitem):
+                        new_var = new_var._sliceAndConcatVar(o, index)
             else:
                 new_var = self
                 for index, o in enumerate(newitem):

python/paddle/fluid/tests/unittests/test_variable.py

@@ -61,7 +61,7 @@ class TestVariable(unittest.TestCase):
             name='step_scopes', type=core.VarDesc.VarType.STEP_SCOPES)
         self.assertEqual(core.VarDesc.VarType.STEP_SCOPES, var.type)
 
-    def _test_slice(self):
+    def _test_slice(self, place):
         b = default_main_program().current_block()
         w = b.create_var(dtype="float64", shape=[784, 100, 100], lod_level=0)
 
@@ -83,7 +83,6 @@ class TestVariable(unittest.TestCase):
 
         self.assertEqual(0, nw.lod_level)
 
-        place = fluid.CPUPlace()
         main = fluid.Program()
         with fluid.program_guard(main):
             exe = fluid.Executor(place)
@@ -100,10 +99,23 @@ class TestVariable(unittest.TestCase):
             var6 = var[1, 1:, 1:]
             var7 = var[1, ..., 1:]
             var8 = var[1, ...]
+            var_reshape = fluid.layers.reshape(var, [3, -1, 3])
+            var9 = var_reshape[1, ..., 2]
+            var10 = var_reshape[:, :, -1]
+
+            x = fluid.layers.data(name='x', shape=[13], dtype='float32')
+            y = fluid.layers.fc(input=x, size=1, act=None)
+            var11 = y[:, 0]
+            feeder = fluid.DataFeeder(place=place, feed_list=[x])
+            data = []
+            data.append((np.random.randint(10, size=[13]).astype('float32')))
+            exe.run(fluid.default_startup_program())
+
             local_out = exe.run(main,
+                                feed=feeder.feed([data]),
                                 fetch_list=[
                                     var, var1, var2, var3, var4, var5, var6,
-                                    var7, var8
+                                    var7, var8, var9, var10, var11
                                 ])
 
             self.assertTrue((np.array(local_out[1]) == np.array(tensor_array[
@@ -122,38 +134,16 @@ class TestVariable(unittest.TestCase):
                 1, ..., 1:])).all())
             self.assertTrue((np.array(local_out[8]) == np.array(tensor_array[
                 1, ...])).all())
+            self.assertEqual(local_out[9].shape, (1, 3, 1))
+            self.assertEqual(local_out[10].shape, (3, 3, 1))
+            self.assertEqual(local_out[11].shape, (1, 1))
 
     def test_slice(self):
-        self._test_slice()
-
-
-class TestVariableImperative(unittest.TestCase):
-    def _test_slice(self):
-        b = default_main_program().current_block()
-        w = b.create_var(dtype="float64", shape=[784, 100, 100], lod_level=0)
-
-        for i in range(3):
-            nw = w[i]
-            self.assertEqual([1, 100, 100], nw.shape)
-
-        nw = w[:]
-        self.assertEqual([784, 100, 100], nw.shape)
-
-        nw = w[:, :, :]
-        self.assertEqual([784, 100, 100], nw.shape)
-
-        nw = w[::2, ::2, :]
-        self.assertEqual([392, 50, 100], nw.shape)
-
-        nw = w[::-2, ::-2, :]
-        self.assertEqual([392, 50, 100], nw.shape)
-
-        nw = w[0::-2, 0::-2, :]
-        self.assertEqual([1, 1, 100], nw.shape)
+        place = fluid.CPUPlace()
+        self._test_slice(place)
 
-    def test_slice(self):
-        with fluid.dygraph.guard():
-            self._test_slice()
+        if core.is_compiled_with_cuda():
+            self._test_slice(core.CUDAPlace(0))
 
 
 if __name__ == '__main__':