fix error message in broadcast/allreduce/gather (#27302)

* fix error message

paddle/fluid/operators/distributed_ops/allreduce_op.h

@@ -76,7 +76,8 @@ class AllReduceOpKernel : public framework::OpKernel<T> {
       PADDLE_ENFORCE_CUDA_SUCCESS(cudaStreamSynchronize(stream));
     }
 #else
-    PADDLE_THROW("PaddlePaddle should compile with GPU.");
+    PADDLE_THROW(platform::errors::PreconditionNotMet(
+        "PaddlePaddle should compile with GPU."));
 #endif
   }
 };

paddle/fluid/operators/distributed_ops/broadcast_op.cc

@@ -58,7 +58,8 @@ template <typename T>
 class BroadcastOpKernel : public framework::OpKernel<T> {
  public:
   void Compute(const framework::ExecutionContext& ctx) const override {
-    PADDLE_THROW("Broadcast op can run on gpu place only for now.");
+    PADDLE_THROW(platform::errors::PreconditionNotMet(
+        "Broadcast op can run on gpu place only for now."));
   }
 };
 

paddle/fluid/operators/distributed_ops/broadcast_op.cu.cc

@@ -68,10 +68,11 @@ class NCCLBroadcastOpKernel : public framework::OpKernel<T> {
             << " From " << root_dev_id << " to " << dev_id;
 
     if (ctx.Attr<bool>("sync_mode")) {
-      PADDLE_ENFORCE(cudaStreamSynchronize(stream));
+      PADDLE_ENFORCE_CUDA_SUCCESS(cudaStreamSynchronize(stream));
     }
 #else
-    PADDLE_THROW("PaddlePaddle should compile with GPU.");
+    PADDLE_THROW(platform::errors::PreconditionNotMet(
+        "PaddlePaddle should compile with GPU."));
 #endif
   }
 };

paddle/fluid/operators/gather_op.cc

@@ -37,8 +37,21 @@ class GatherOp : public framework::OperatorWithKernel {
                           "Output(Out) of GatherOp should not be null."));
 
     auto index_dims = ctx->GetInputDim("Index");
-    PADDLE_ENFORCE(index_dims.size() == 1 ||
-                   (index_dims.size() == 2 && index_dims[1] == 1));
+
+    if (index_dims.size() == 2) {
+      PADDLE_ENFORCE_EQ(
+          index_dims[1], 1,
+          platform::errors::InvalidArgument(
+              "The last dim of index should be 1 when it is 2D, but we get %d",
+              index_dims[1]));
+    } else {
+      PADDLE_ENFORCE_EQ(
+          index_dims.size(), 1,
+          platform::errors::InvalidArgument(
+              "The index should be 1D, when it is not 2D, but we get %d",
+              index_dims.size()));
+    }
+
     int batch_size = ctx->GetInputDim("Index")[0];
     framework::DDim output_dims(ctx->GetInputDim("X"));
     output_dims[0] = batch_size;

python/paddle/fluid/tests/unittests/test_broadcast_error.py

@@ -0,0 +1,38 @@
+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import unittest
+import numpy as np
+from op_test import OpTest
+import paddle.fluid.core as core
+
+
+class TestBroadcastOpCpu(OpTest):
+    def setUp(self):
+        self.op_type = "broadcast"
+        input = np.random.random((100, 2)).astype("float32")
+        np_out = input[:]
+        self.inputs = {"X": input}
+        self.attrs = {"sync_mode": False, "root": 0}
+        self.outputs = {"Out": np_out}
+
+    def test_check_output_cpu(self):
+        try:
+            self.check_output_with_place(place=core.CPUPlace())
+        except:
+            print("do not support cpu test, skip")
+
+
+if __name__ == "__main__":
+    unittest.main()