From c3236f82d698a017e4dffa6d2a0c912a594a43f8 Mon Sep 17 00:00:00 2001
From: Xin Pan <panxin.grad@gmail.com>
Date: Sun, 2 Dec 2018 17:11:58 +0800
Subject: [PATCH] polish

---
 paddle/fluid/imperative/layer.cc | 20 +++++---------------
 1 file changed, 5 insertions(+), 15 deletions(-)

diff --git a/paddle/fluid/imperative/layer.cc b/paddle/fluid/imperative/layer.cc
index 08379a7ed5..c5a8d9c6b6 100644
--- a/paddle/fluid/imperative/layer.cc
+++ b/paddle/fluid/imperative/layer.cc
@@ -44,16 +44,12 @@ class Autograd {
  public:
   explicit Autograd(framework::Scope* scope) : scope_(scope) {}
 
-  void RunBackward(VarBase* var, framework::Variable* grad) {
-    if (!var->pre_op_) {
-      var->ApplyGrad(scope_, grad);
-      return;
-    }
+  void RunBackward(VarBase* var) {
     PADDLE_ENFORCE(var->pre_op_->op_desc_);
     // TODO(panyx0718): Only create vars that "require_grad"
     std::vector<Variable*> op_grads =
         CreateOpGrads(var->pre_op_->output_vars_->size());
-    op_grads[var->pre_op_out_idx_] = grad;
+    op_grads[var->pre_op_out_idx_] = var->grads_;
 
     std::deque<std::pair<OpBase*, std::vector<Variable*>>> ready;
     ready.push_back(std::make_pair(var->pre_op_, op_grads));
@@ -238,8 +234,6 @@ std::vector<Variable*> OpBase::ApplyGrad(framework::Scope* scope) {
           framework::Variable* var = scope->FindVar(outvar);
           LOG(ERROR) << "apply grad " << outvar << " with origin "
                      << origin_var;
-          // TODO(panyx0718): Accumulate.
-          // origin_in_var->grads_ = var;
           origin_in_var->ApplyGrad(scope, var);
           ret[i] = var;
           // TODO(panyx0718): There might be 2 var with the same name. We
@@ -254,15 +248,11 @@ std::vector<Variable*> OpBase::ApplyGrad(framework::Scope* scope) {
 }
 
 void VarBase::RunBackward(framework::Scope* scope) {
-  // TODO(panyx0718): Might not be 0th, need to detect.
-  grads_ = CreateVariable(pre_op_->grad_op_desc_->InputArgumentNames()[0],
+  grads_ = CreateVariable(framework::GradVarName(var_desc_->Name()),
                           var_->Get<framework::LoDTensor>().dims(), 1.0, scope,
                           false);
-  framework::Variable* grad =
-      CreateVariable("init@imperative_grad",
-                     var_->Get<framework::LoDTensor>().dims(), 1.0, scope);
-
-  Autograd(scope).RunBackward(this, grad);
+  if (!pre_op_) return;
+  Autograd(scope).RunBackward(this);
 }
 
 }  // namespace imperative
-- 
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