replace concat_op with merge_ids_op

Author: jacquesqiao

python/paddle/fluid/transpiler/distribute_transpiler.py

@@ -618,7 +618,7 @@ def _replace_lookup_table_op_with_prefetch(self, program,
                 if op.type == LOOKUP_TABLE_TYPE:
                     continue_search_lookup_table_op = True
 
-                    op_index = list(all_ops).index(op)
+                    lookup_table_op_index = list(all_ops).index(op)
                     ids_name = op.input("Ids")
                     out_name = op.output("Out")
 
@@ -637,7 +637,7 @@ def _replace_lookup_table_op_with_prefetch(self, program,
 
                     # insert split_ids_op
                     program.global_block().insert_op(
-                        index=op_index,
+                        index=lookup_table_op_index,
                         type="split_ids",
                         inputs={
                             'Ids': [
@@ -649,7 +649,7 @@ def _replace_lookup_table_op_with_prefetch(self, program,
 
                     # insert prefetch_op
                     program.global_block().insert_op(
-                        index=op_index + 1,
+                        index=lookup_table_op_index + 1,
                         type="prefetch",
                         inputs={'X': self.prefetch_input_vars},
                         outputs={"Out": self.prefetch_output_vars},
@@ -660,16 +660,21 @@ def _replace_lookup_table_op_with_prefetch(self, program,
 
                     # insert concat_op
                     program.global_block().insert_op(
-                        index=op_index + 2,
-                        type="concat",
-                        inputs={'X': self.prefetch_output_vars},
+                        index=lookup_table_op_index + 2,
+                        type="merge_ids",
+                        inputs={
+                            'Ids': [
+                                program.global_block().vars[varname]
+                                for varname in ids_name
+                            ],
+                            'X': self.prefetch_output_vars
+                        },
                         outputs={
                             "Out": [
                                 program.global_block().vars[varname]
                                 for varname in out_name
                             ]
-                        },
-                        attrs={"axis": 0})
+                        })
 
                     # delete lookup_table_op
                     delete_ops(program.global_block(), [op])