!6973 [AutoParallel]Semi_auto_parallel_support_gpt2

Merge pull request !6973 from lichen/semi_auto_support_gpt2

mindspore/ccsrc/frontend/parallel/step_parallel.cc

@@ -876,6 +876,15 @@ void InsertMirrorOps(const MirrorOps &mirror_ops, const CNodePtr &node) {
       // if there is already a MirrorOp in the same graph, use MirrorOp CNode as a input instead
       if (next_cnode.first) {
         MS_EXCEPTION_IF_NULL(next_cnode.second);
+        // param->cast->op, insert mirror before cast
+        if (node->input(index)->isa<CNode>()) {
+          auto pre_cnode = node->input(index)->cast<CNodePtr>();
+          auto pre_prim = GetValueNode<PrimitivePtr>(pre_cnode->input(0));
+          if (pre_prim->name() == CAST) {
+            manager->SetEdge(pre_cnode, 1, next_cnode.second);
+            continue;
+          }
+        }
         manager->SetEdge(node, SizeToInt(index), next_cnode.second);
         continue;
       }