Refactor Leaky ReLU to Use Activations in Backward (#2262)

* Change leaky relu backprop to use activations

* Update backprop requirements

Author: fiedorowicz1

include/lbann/layers/activations/leaky_relu.hpp

@@ -128,7 +128,7 @@ class leaky_relu_layer : public data_type_layer<TensorDataType>
   bool can_run_inplace() const override { return true; }
   int get_backprop_requirements() const override
   {
-    return ERROR_SIGNALS | PREV_ACTIVATIONS;
+    return ERROR_SIGNALS | ACTIVATIONS;
   }
 
 private:

src/layers/activations/leaky_relu.cpp

@@ -84,7 +84,7 @@ template <typename TensorDataType, data_layout Layout, El::Device Device>
 void leaky_relu_layer<TensorDataType, Layout, Device>::bp_compute()
 {
   local_bp<TensorDataType>(this->m_negative_slope,
-                           this->get_local_prev_activations(),
+                           this->get_local_activations(),
                            this->get_local_prev_error_signals(),
                            this->get_local_error_signals());
 }

src/layers/activations/leaky_relu.cu

@@ -179,7 +179,7 @@ void bp_compute_distconv(
   TensorDataType negative_slope)
 {
   assert_always(Layout == data_layout::DATA_PARALLEL);
-  dc.m_leaky_relu->backward(dc.get_prev_activations(),
+  dc.m_leaky_relu->backward(dc.get_activations(),
                             dc.get_prev_error_signals(),
                             negative_slope,
                             dc.get_error_signals());
@@ -211,7 +211,7 @@ void leaky_relu_layer<TensorDataType, Layout, Device>::bp_compute()
   }
 #endif // LBANN_HAS_DISTCONV
   local_bp(this->m_negative_slope,
-           this->get_local_prev_activations(),
+           this->get_local_activations(),
            this->get_local_prev_error_signals(),
            this->get_local_error_signals());
 }