fix QAT export bug in while OP (#38102)

python/paddle/fluid/contrib/slim/quantization/imperative/qat.py

@@ -22,6 +22,7 @@ import warnings
 import paddle
 import paddle.nn.quant.quant_layers as quant_layers
 from paddle.fluid import dygraph, core, framework, unique_name
+from paddle.fluid.framework import IrGraph
 from paddle.fluid.executor import Executor, global_scope
 from paddle.fluid.param_attr import ParamAttr
 from paddle.fluid.initializer import Constant
@@ -486,6 +487,15 @@ class ImperativeQuantizeOutputs(object):
 
         self._gather_scales(infer_program, scope, fetch_targets)
 
+        # Remove `moving_average_abs_max_scale` node in sub graphs.
+        graph = IrGraph(core.Graph(infer_program.desc), for_test=False)
+        for sub_graph in graph.all_sub_graphs():
+            for _op in sub_graph.all_op_nodes():
+                if _op.name() == "moving_average_abs_max_scale":
+                    sub_graph.safe_remove_nodes(_op)
+            sub_graph.resolve_hazard()
+        infer_program = graph.to_program()
+
         self._set_skip_quant_attr(infer_program)
 
         save_inference_model(