fix to only check block 0

test=develop

paddle/fluid/framework/ir/graph.cc

@@ -26,15 +26,14 @@ namespace ir {
 namespace {
 
 void CheckProgram(const ProgramDesc &program) {
-  std::map<int, bool> visit;
 #define _INT(role) static_cast<int>(role)
 
-  for (size_t i = 0; i < program.Size(); ++i) {
-    for (OpDesc *op : program.Block(i).AllOps()) {
+  std::map<int, bool> visit;
+  for (OpDesc *op : program.Block(0).AllOps()) {
     // For backward compatibility, some program doesn't have role added.
     if (!op->HasAttr(OpProtoAndCheckerMaker::OpRoleAttrName())) continue;
-      int role_id = boost::get<int>(
-          op->GetAttr(OpProtoAndCheckerMaker::OpRoleAttrName()));
+    int role_id =
+        boost::get<int>(op->GetAttr(OpProtoAndCheckerMaker::OpRoleAttrName()));
     visit[role_id] = true;
     switch (role_id) {
       case _INT(OpRole::kForward):
@@ -48,7 +47,7 @@ void CheckProgram(const ProgramDesc &program) {
       case _INT(OpRole::kBackward) | _INT(OpRole::kLoss):
         PADDLE_ENFORCE(
             visit.find(_INT(OpRole::kOptimize)) == visit.end(),
-              "Cannot add backward operator %s before optimize operator.",
+            "Cannot add backward operator %s after optimize operator.",
             op->Type());
         break;
       case _INT(OpRole::kForward) | _INT(OpRole::kLoss):
@@ -78,7 +77,7 @@ void CheckProgram(const ProgramDesc &program) {
                       "you don't know what you are doing.";
     }
   }
-  }
+
 #undef _INT
 }
 }  // namespace