prune pass simple test

paddle/framework/executor.cc

@@ -145,9 +145,11 @@ std::vector<bool> Executor::Preprocess(const ProgramDesc& pdesc) {
 
       // this op should be executed
       should_run.push_back(true);
+      LOG(INFO) << "Yes " << op_desc.type();
     } else {
       // this op should NOT be executed
       should_run.push_back(false);
+      LOG(INFO) << "No " << op_desc.type();
     }
   }
 

paddle/framework/executor.h

@@ -38,9 +38,13 @@ class Executor {
 
  protected:
   /* @Brief
+   * Pruning the graph
    *
    * @param
    *  ProgramDesc
+   *
+   * @return
+   *  vector<bool> Same size as ops. Indicates whether an op should be run.
    */
   std::vector<bool> Preprocess(const ProgramDesc& pdesc);
 

paddle/framework/executor_test.cc

@@ -226,6 +226,7 @@ class ExecutorTesterFeed : public ::testing::Test {
     Out->set_parameter("Out");
     Out->add_arguments("c");
 
+    add_fetch_op("a", dim, 0, root_block);
     add_fetch_op("c", dim, 0, root_block);
 
     std::vector<float> vec1 = {1.0, 2.0, 3.0, 4.0, 5.0, 6.0};