From 9c1efa2c93558da3270e63c4d70c189eae78d70a Mon Sep 17 00:00:00 2001
From: 0x45f <wangzhen45@baidu.com>
Date: Thu, 26 May 2022 15:19:05 +0000
Subject: [PATCH] Fix cond_block_grad error when handle no need grad vras

---
 .../controlflow/conditional_block_op.cc       | 21 ++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/paddle/fluid/operators/controlflow/conditional_block_op.cc b/paddle/fluid/operators/controlflow/conditional_block_op.cc
index fd06e33a6bb6e..69e173eb57468 100644
--- a/paddle/fluid/operators/controlflow/conditional_block_op.cc
+++ b/paddle/fluid/operators/controlflow/conditional_block_op.cc
@@ -153,7 +153,7 @@ class ConditionalBlockGradOp : public ConditionalOp {
                /* keep_kid_scopes */ false);
 
       AssignLocalGradientToParentScope(dev_place, cur_scope, scope,
-                                       inside_grads, outside_grads);
+                                       inside_grads, outside_grads, inputs);
       return;
     }
 
@@ -165,27 +165,34 @@ class ConditionalBlockGradOp : public ConditionalOp {
       const platform::Place &place, const framework::Scope &cur_scope,
       const framework::Scope &parent_scope,
       const std::vector<std::string> &inside_grads,
-      const std::vector<std::string> &outside_grads) const {
+      const std::vector<std::string> &outside_grads,
+      const std::vector<std::string> &inputs) const {
+    std::vector<std::string> assign_zero_outside_grads;
+    std::vector<std::string> assign_zero_inputs;
     for (size_t i = 0; i < outside_grads.size(); ++i) {
       const std::string &outside_grad_name = outside_grads[i];
       const std::string &inside_grad_name = inside_grads[i];
       VLOG(4) << "inside_grad_name = " << inside_grad_name
               << ", outside_grad_name = " << outside_grad_name;
-      framework::Variable *inside_var =
-          cur_scope.FindLocalVar(inside_grad_name);
-      if (inside_var == nullptr) {
-        continue;
-      }
       framework::Variable *outside_var =
           parent_scope.FindVar(outside_grad_name);
       if (outside_var == nullptr) {
         continue;
       }
+      framework::Variable *inside_var =
+          cur_scope.FindLocalVar(inside_grad_name);
+      if (inside_var == nullptr) {
+        assign_zero_outside_grads.push_back(outside_grad_name);
+        assign_zero_inputs.push_back(inputs[i]);
+        continue;
+      }
       platform::DeviceContext *dev_ctx =
           platform::DeviceContextPool::Instance().Get(place);
       framework::VisitVarType(*inside_var,
                               AssignFunctor(outside_var, *dev_ctx));
     }
+    AssignZeroToParentScope(place, parent_scope, assign_zero_inputs,
+                            assign_zero_outside_grads);
   }
 
   void AssignZeroToParentScope(