fix reducer check for main_grad (#57960)

haohongxiang · web-flow · commit 7be2b40caf68 · 2023-10-10T18:40:48.000+08:00
diff --git a/paddle/fluid/distributed/collective/reducer.cc b/paddle/fluid/distributed/collective/reducer.cc
@@ -757,9 +757,7 @@ void EagerReducer::AddDistHook(size_t var_index) {
     auto *autograd_meta = tensors_[var_index].get_autograd_meta();
     auto &grad_tensor = static_cast<egr::AutogradMeta *>(autograd_meta)->Grad();
 
-    if (!HasGrad(var_index)) {
-      group_tensor.ShareDataWith(phi::DenseTensor());
-    } else {
+    if (HasGrad(var_index)) {
       auto grad_dense_tensor =
           *(std::dynamic_pointer_cast<phi::DenseTensor>(grad_tensor.impl()));
       group_tensor.ShareDataWith(grad_dense_tensor);
