Fix reduce_ops for mixed-precision FP16 support (#55573)

paddle/fluid/framework/ir/auto_mixed_precision_pass.cc

@@ -415,7 +415,8 @@ void AutoMixedPrecisionPass::GetOpPrecision() const {
           auto out_dtype = op_node->Op()->GetAttrIfExists<int>("out_dtype");
           support_low_precision =
               support_low_precision &&
-              IsFP32AndFP64(static_cast<VarType::Type>(out_dtype));
+              (IsFP32AndFP64(static_cast<VarType::Type>(out_dtype)) ||
+               out_dtype == -1);
         }
 
         // If scale op's "scale" and "bias" attr value exceed the range of fp16