From 9241011b31bbfac0d99cd89f4545e0f905276914 Mon Sep 17 00:00:00 2001
From: Tomasz Patejko <tomasz.patejko@intel.com>
Date: Tue, 22 May 2018 02:12:54 +0200
Subject: [PATCH] MKL elementwise add backward: backward works for integral
 types with fall back to default impl

---
 paddle/fluid/operators/elementwise_add_op.cc |  6 +-
 paddle/fluid/operators/elementwise_add_op.h  | 69 +++++++++++++++-----
 2 files changed, 57 insertions(+), 18 deletions(-)

diff --git a/paddle/fluid/operators/elementwise_add_op.cc b/paddle/fluid/operators/elementwise_add_op.cc
index 7824dea5d..d2c205371 100644
--- a/paddle/fluid/operators/elementwise_add_op.cc
+++ b/paddle/fluid/operators/elementwise_add_op.cc
@@ -25,6 +25,6 @@ REGISTER_OP_CPU_KERNEL(
 REGISTER_OP_CPU_KERNEL(
     elementwise_add_grad,
     ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, float>,
-    ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, double>);
-// ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, int>,
-// ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, int64_t>);
+    ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, double>,
+    ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, int>,
+    ops::ElementwiseAddGradKernel<paddle::platform::CPUDeviceContext, int64_t>);
diff --git a/paddle/fluid/operators/elementwise_add_op.h b/paddle/fluid/operators/elementwise_add_op.h
index 3286aa848..d85f78528 100644
--- a/paddle/fluid/operators/elementwise_add_op.h
+++ b/paddle/fluid/operators/elementwise_add_op.h
@@ -85,6 +85,57 @@ struct IdentityGrad {
   HOSTDEVICE T operator()(T x, T y, T out, T dout) const { return dout; }
 };
 
+template<typename DeviceContext, typename T>
+void default_elementwise_add_grad(const framework::ExecutionContext& ctx,
+                                  const framework::Tensor* x,
+                                  const framework::Tensor* y,
+                                  const framework::Tensor* out,
+                                  const framework::Tensor* dout,
+                                  framework::Tensor* dx,
+                                  framework::Tensor* dy) {
+  int axis = ctx.Attr<int>("axis");
+
+  ElemwiseGradCompute<DeviceContext, T, IdentityGrad<T>, IdentityGrad<T>>(
+      ctx, *x, *y, *out, *dout, axis, dx, dy, IdentityGrad<T>(),
+      IdentityGrad<T>());
+}
+
+template<typename DeviceContext, typename T>
+typename std::enable_if<
+    std::is_floating_point<T>::value &&
+    std::is_same<DeviceContext, platform::CPUDeviceContext>::value>::type
+elementwise_add_grad(const framework::ExecutionContext& ctx,
+                     const framework::Tensor* x,
+                     const framework::Tensor* y,
+                     const framework::Tensor* out,
+                     const framework::Tensor* dout,
+                     framework::Tensor* dx, framework::Tensor* dy) {
+  auto blas = math::GetBlas<DeviceContext, T>(ctx);
+
+  if (dx) {
+    blas.VCOPY(dout->numel(), dout->data<T>(),
+               dx->mutable_data<T>(ctx.GetPlace()));
+  }
+
+  if (dy) {
+    blas.VCOPY(dout->numel(), dout->data<T>(),
+               dy->mutable_data<T>(ctx.GetPlace()));
+  }
+}
+
+template<typename DeviceContext, typename T>
+typename std::enable_if<
+    !std::is_floating_point<T>::value ||
+    !std::is_same<DeviceContext, platform::CPUDeviceContext>::value>::type
+elementwise_add_grad(const framework::ExecutionContext& ctx,
+                     const framework::Tensor* x,
+                     const framework::Tensor* y,
+                     const framework::Tensor* out,
+                     const framework::Tensor* dout,
+                     framework::Tensor* dx, framework::Tensor* dy) {
+  default_elementwise_add_grad<DeviceContext, T>(ctx, x, y, out, dout, dx, dy);
+}
+
 template <typename DeviceContext, typename T>
 class ElementwiseAddGradKernel : public framework::OpKernel<T> {
  public:
@@ -97,24 +148,12 @@ class ElementwiseAddGradKernel : public framework::OpKernel<T> {
     auto* dout = ctx.Input<Tensor>(framework::GradVarName("Out"));
     auto* dx = ctx.Output<Tensor>(framework::GradVarName("X"));
     auto* dy = ctx.Output<Tensor>(framework::GradVarName("Y"));
-    int axis = ctx.Attr<int>("axis");
 
     if (platform::is_cpu_place(ctx.GetPlace()) && (x->dims() == y->dims())) {
-      auto blas = math::GetBlas<DeviceContext, T>(ctx);
-
-      if (dx) {
-        blas.VCOPY(dout->numel(), dout->data<T>(),
-                   dx->mutable_data<T>(ctx.GetPlace()));
-      }
-
-      if (dy) {
-        blas.VCOPY(dout->numel(), dout->data<T>(),
-                   dy->mutable_data<T>(ctx.GetPlace()));
-      }
+      elementwise_add_grad<DeviceContext, T>(ctx, x, y, out, dout, dx, dy);
     } else {
-      ElemwiseGradCompute<DeviceContext, T, IdentityGrad<T>, IdentityGrad<T>>(
-          ctx, *x, *y, *out, *dout, axis, dx, dy, IdentityGrad<T>(),
-          IdentityGrad<T>());
+      default_elementwise_add_grad<DeviceContext, T>(
+            ctx, x, y, out, dout, dx, dy);
     }
   }
 };
-- 
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